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STUDENTSYMPOSIUM

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A Letter From The Organizers Dear Attendees, Welcome to the 16th Annual School of Biomedical Engineering & Sciences Graduate Student Research Symposium hosted by the VT-WFU Biomedical Engineering Society Student Chapter! The Virginia Tech-Wake Forest University School of Biomedical Engineering & Sciences (SBES) is a joint graduate program formed in 2003 to bring together three prestigious academic institutions: the College of Engineering at Virginia Tech, the Wake Forest University School of Medicine, and the Regional Virginia-Maryland College of Veterinary Medicine. Each university contributes diverse educational and research opportunities to the students, providing a unique graduate experience. On August 11, 2014, Virginia Tech announced a new collaboration between SBES and the Engineering Science and Mechanics department to form the new Department of Biomedical Engineering and Mechanics. This department fosters important networking opportunities across the Virginia Tech campus as well as provides the framework towards an undergraduate biomedical engineering degree and strong vision for the future. The VT-WFU Biomedical Engineering Society (BMES) Student Chapter was founded to foster communication and collaboration among various research groups. Our mission is to encourage the development, dissemination, integration, and utilization of knowledge in biomedical engineering, as well as interact with the scientific community. The chapter offers unique ways for students to become involved in outreach projects, research collaborations, and social events with other students, faculty, and industry. We are involved in many service opportunities within our local communities, and participate annually in the BMES National meeting. The SBES Graduate Student Research Symposium was developed to provide students and faculty the opportunity to interact and exchange research ideas with colleagues and industry personnel. The VT-WFU BMES Student Chapter would like to thank our sponsors Cook Medical, Wake Forest Innovations, Medtronic, and BMES for their generous support. We greatly appreciate your participation and hope that this symposium will promote enhanced discussion and collaboration among researchers. Thank you for your attendance! The VT-WFU BMES Executive Committee

Alexandra Hyler James Gaewsky

Marc Thompson Kelli Simms

Roy Anderson Derek Jones

Grace Wusk Berkan Guleyopoglu

Presidents Vice Presidents Treasurers Secretaries

Please visit our website for more information www.sbes.vt.edu/bmes/

Scott Verbridge Ashley Weaver VT Faculty Advisor WFU Faculty Advisor

http://www.sbes.vt.edu/bmes/

BIOMATERIALS DEVELOPMENT &

CHARACTERIZATION

THE TUMOR & TISSUE

MICROENVIRONMENTSMODELING THE HUMAN BODY

Smithfield Duck Pond Drillfield

DEVELOPING NOVEL MEDICAL DEVICES EVALUATIONS OF HEAD INJURY LOWER EXTREMITY BIOMECHANICS

Smithfield Duck Pond Drillfield

BIOELECTRICAL SYSTEMS CRASH INJURY & PREVENTION

Smithfield Duck Pond

3:15-3:45AWARDS & CLOSING

Latham A

11:15-11:45POSTER SESSION B

Latham B

11:45-1:00LUNCH

Latham C, D, E, F

1:00-2:00

2:00-2:15AFTERNOON BREAK

Latham Foyer

2:15-3:00

9:30-10:30

10:30-10:45MORNING BREAK

Latham Foyer

10:45-11:15POSTER SESSION A

Latham B

8:30-9:15

REGISTRATION, Latham Foyer

POSTER SET UP, Latham B

REFRESHMENTS, Latham Foyer

9:15-9:30WELCOME, Alex Hyler & Jamie Gaewsky, VT-WFU BMES Presidents

Latham A

ii

Page Number

13

BME

23

MS

9

MS

22

PhD

Page Number

5

PhD

15

PhD

3

MS

8

PhD

Page Number

25

PhD

2

MS

28

PhD

Drillfield

9:30

9:45

10:00

Development of Subject-Specific Proximal Femur and Lumbar Spine Finite Element Models of Obese, Older

Adults to Evaluate the Effects of Weight Loss On Bone Strength

Chair: Derek Jones

Finite Element Based Pelvic Injury Metric Creation and Validation in Lateral Impact for a Human Body

9:30-10:30

9:30-10:30

BIOMATERIALS DEVELOPMENT & CHARACTERIZATION

Smithfield

Duck PondTHE TUMOR & TISSUE MICROENVIRONMENTS

MODELING THE HUMAN BODY

9:30-10:30

Chair: Marc Thompson

Chair: Kelli Simms

9:30

Analyzing Hypoxia Induced Epigenetic Variations in Cell Subpopulations in the Tumor Microenvironment

Megan C. Cox1, Chengyu Deng

2, Yan Zhu

2, Yuan-Pang Hsieh

2, Chang Lu

2, and Scott S. Verbridge

1

1Virginia Tech Department of Biomedical Engineering and Mechanics, Blacksburg, VA

2Virginia Tech, Department of Chemical

Engineering, Blacksburg, VA

Craniofacial Bone Regeneration Guided by 3D Printed Architecture

Allison M. Pekkanen1*

, Callie Zawaski2, Andre T. Stevenson Jr

3, Ross Dickerman

4, Abby R. Whittington

1,3,4, Christopher B.

Williams2,5

, and Timothy E. Long

Macromolecules Innovation Institute, Department of Chemistry, Virginia Tech, Blacksburg, VA 1Biomedical Engineering and

Mechanics, Virginia Tech, Blacksburg, VA 2

Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 3Materials

Science and Engineering, Virginia Tech, Blacksburg, VA 4Department of Chemical Engineering, Virginia Tech, Blacksburg, VA

10:15

10:00

9:451Virginia Tech-Wake Forest School of Biomedical Engineering, Winston Salem, NC

2Department of Biochemistry and Molecular

Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 3

Institute for Regenerative Medicine, Wake Forest

University School of Medicine Winston Salem, NC 4Comprehensive Cancer Center, Wake Forest University, School of

Biomedical Medicine, Winston Salem, NC

Effect of Preservation Fluid Type on the Failure Material Properties of Bovine Liver Parenchyma with

Increasing Post Mortem Time

Kristin M. Dunford1 and Andrew R. Kemper

1


Poly(ether ester) Ionomers as Water-Soluble Polymers for Material Extrusion Additive Manufacturing

Modeling Thrombus Formation and Growth in Stenotic Flow

Hamid Hosseinzadegan1 and Danesh K. Tafti

1

1Mechanical Engineering, Virginia Tech, Blacksburg, VA

Molecular Analysis of Hyaluronic Acid with Solid-State Nanopores

Felipe Rivas1, Osama Zahid

1, Paul L. DeAngelis

2, Aleksander Skardal

1,3,4, Adam R. Hall

1,3,4, Elaheh Rahbar

1

Rheology vs Alignment: Two Operators of the Mechanical Tumor Microenvironment

Mahesh Devarasetty1,2

, Aleksander Skardal1,2

, and Shay Soker1,2

9:30

9:45

10:00

10:15

Carlos V. Kengla1,2

, Anthony Atala1,2

, James J. Yoo1,2

, and Sang Jin Lee1,2

1Wake Forest University, Institute for Regenerative Medicine, School of Biomedical Engineering and Sciences, Winston-Salem,

NC 2Virginia Tech School of Biomedical Engineering and Sciences, Winston-Salem, NC

N-(3-oxododecanoyl)-L-homoserine Lactone Interactions in the Breast Tumor Microenvironment:

Implications for Breast Cancer Viability and Proliferation In Vitro

Brittany N. Balhouse1, Logan Patterson

2,3, Eva M. Schmelz

4, Daniel J. Slade

2 and Scott S. Verbridge

1

1School of Biomedical Engineerng and Sciences, Virginia Tech-Wake Forest Blacksburg, VA

2Department of Biochemistry,

Virginia Tech, Blacksburg, VA 3

Department of Pathology, University of Virginia, Charlottesville, VA 4Department of Human

Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA

Caitlin M. Weaver1,2,3

, Alexander M. Baker1,2

, Matthew L. Davis1,2

, Anna N. Miller4, and Joel D. Stitzel

1,2

1Virginia Tech-Wake Forest University, Center for Injury Biomechanics

2Wake Forest University, School of Medicine

3US Army

Research Laboratory, Soldier Protection Sciences Branch 4Washington University, Department of Orthopaedic Surgery

Samantha L. Schoell1, Ashley A. Weaver

1, Dan P. Beavers

2, Joel D. Stitzel

1, and Kristen M. Beavers

3

1Wake Forest School of Medicine, Department of Biomedical Engineering

2Wake Forest School of Medicine, Department of

Biostatistical Sciences 3Wake Forest School of Medicine, Department of Health and Exercise Science

Development and Validation of a Finite Element Model of the WIAMan Lower Extremity

Wade A. Baker1, Costin Untaroiu

1, and Mostafiz Chowhurdy

2


2Army Research Laboratory

1Wake Forest University, Institute for Regenerative Medicine, Winston-Salem, NC

2Virginia Tech-Wake Forest School of

Biomedical Engineering and Sciences, Winston-Salem, NC

iii

Page Number

11

BME

18

PhD

20

MS

19

PhD

Page Number

1

PhD

26

MS

7

MS

4

MS

Page Number

12

MS

27

MS

17

MS

DEVELOPING NOVEL MEDICAL DEVICES

Smithfield

EVALUATIONS OF HEAD INJURY

Duck Pond

LOWER EXTREMITY BIOMECHANICS

Drillfield

Chair: Berkan Guleyupoglu

Chair: Roy Anderson

Chair: Grace Wusk

1:00-2:00

1:00-2:00

1:00-2:00

Assessing and Optimizing Smart Textile Systems for Human Activity Monitoring

M.I. Mokhlespour Esfahani1, Maury Nussbaum

1

Ryan D.M. Packett1, Philip J. Brown

1, Gautam S. Popli

1, and F. Scott Gayzik

2

1Wake Forest University, Department of Biomedical Engineering, Winston-Salem, NC

2Wake Forest Baptist Medical Center,

Department of Neurology, Winston-Salem, NC

Advanced Statistical Process Control Techniques for Analysis of Medical Linear Accelerator Performance

Callistus M. Nguyen1,2

, Alan H. Baydush1, Charles M. Able

3, and Michael T. Munley

1,2

1Radiation Oncology (Wake Forest School of Medicine, Radiation Oncology)

2Biomedical Engineering (Virginia Tech – Wake

Forest School of Biomedical Engineering and Sciences, Biomedical Engineering) 3Radiation Oncology (Florida Cancer

Specialists, Radiation Oncology)

1Virginia Tech Department of Industrial and Systems Engineering, Blacksburg, VA

Using fMRI Dynamic Networks in a Hypergraph Learning Model for Predicting the Success of Lifestyle

Weight Loss Interventions In Obese Older Adults

Fatemeh Mokhtari1,2

, Jonathan H. Burdette1, Anthony P. Marsh

2-5, W. Jack Rejeski

1, 3-5, Paul J. Laurienti

1-3

1Laboratory for Complex Brain Networks, Department of Radiology, Wake Forest School of Medicine

2Virginia Tech-Wake

Forest University School of Biomedical Engineering and Sciences 3Translational Science Center, Wake Forest University

4Department of Health and Exercise Science, Wake Forest University

5Department of Geriatric Medicine, Wake Forest

University, Winston-Salem, NC

Development and Validation of a Brain Phantom for Therapeutic Cooling Devices

Modular use of Human Body Models of Varying Levels of Complexity: Validation of Head Kinematics

William Decker1,2

, Bharath Koya2, Matthew L. Davis

1,2, and F. Scott Gayzik

1,2

1Wake Forest University School of Medicine

2Virginia Tech – Wake Forest University Center for Injury Biomechanics

High Magnitude Head Impact Exposure in Youth Football

Epigenetic Mechanisms In Blast Induced Neurotrauma

Zachary S. Bailey1, Pamela J. VandeVord

1,2

1Virginia Tech, Biomedical Engineering and Mechanics

2Salem Veterans Affairs Medical Center

STAR for Youth and Varsity Football Helmets: Characterizing Helmet Performance Using Linear and

Rotational Head Acceleration

David W. Sproule1, Eamon T. Campolettano

1, Steven Rowson

1

1:00

1Wake Forest School of Medicine, Department of Orthopaedics

2Virginia Tech, Center for Injury Biomechanics

3Ohio State

University, Injury Biomechanics Research Center

Effects of Achilles Tendon Taping on Joint Energetics in Jumping and Landing

Evan P. McConnell1, Philip Hernandez

1, and Robin M. Queen

1

1:00

1:15

1:30

1:45

1Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA

1:30

1:15

Recovery of Balance In Total Ankle Replacement Patients Across Time

Jonathan R. Gladish1, Robin M. Queen

1

1Kevin P. Granata Biomechanics Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA

Foot and Ankle Response in the Underbody-Blast Environment

Laura C. Watkins1, Aaron T. Scott

1, Andrew R. Kemper

2, John H. Bolte IV

3, Warren N. Hardy

2, Kerry A. Danelson

1

Eamon T. Campolettano1, Ryan A. Gellner

1, and Steven Rowson

1

1Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA

1:00

1:15

1:30

1:45

1Virginia Tech School of Biomedical Engineering and Sciences, Blacksburg, VA

iv

Page Number

10

PhD

16

MS

14

PhD

Page Number

21

PhD

6

PhD

24

MS

Chair: Grace Wusk

2:15-3:00

BIOELECTRICAL SYSTEMS

Smithfield

CRASH INJURY & PREVENTION

Duck Pond

Chair: Roy Anderson

2:15-3:00

1Department of Biomedical Engineering, Wake Forest School of Medicine

2Wake Forest University Center for Injury

Biomechanics

2:45

2:30

Evaluating the Potential of an Intersection Driver Assistance System to Prevent U.S. Intersection Crashes

John M. Scanlon1 and H. Clay Gabler

1

1Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Blacksburg, VA

Development and Full Body Validation of a 5th

Percentile Female Finite Element Model

Matthew L. Davis1,2

, Bharath Koya1,2

, Jeremy M. Schap1,2

, and F. Scott Gayzik1,2

2:15

2:30

2:45

Effects of Extracellular Sodium and Calcium on the Conduction Velocity – Extracellular Potassium

Relationship in Guinea Pigs

Michael W. Entz II1,2

and Steven Poelzing, PhD1,2

1Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA

2Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Roanoke, VA

Interstitial Cells of Cajal Increase Neural-Mediated Relaxation and Electrical Rhythm in an In Vitro

Bioenginnered Model of Pylorus

Dylan T. Knutson1, 2

, Elie Zakhem1, Kenneth L. Koch

3, Khalil N. Bitar

1, 2, 3

1Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, NC

2Viriginia Tech – Wake

Forest University School of Biomedical Engineering, Winston Salem, NC 3Section on Gastroenterology Department of Internal

Medicine, Wake Forest School of Medicine, Winston Salem, NC

Enhancing the Selectivity of Electroporation Therapy for Glioblastoma

Jill W. Ivey1, Eduardo L. Latouche

1, Glenn J. Lesser

2, Waldemar Debinski

2, Rafael V. Davalos

1, Scott S. Verbridge

1

1Virginia Tech-Wake Forest University, Department of Biomedical Engineering and Mechanics

2Wake Forest Baptist Medical

Center, Comprehensive Cancer Center

2:15

1Virginia Tech-Wake Forest Center for Injury Biomechanics, Winston-Salem, NC

2Wake Forest School of Medicine, Winston-

Salem, NC

Investigation of Thoracolumbar Fractures in Motorsport Drivers During Frontal Impacts

John Patalak1,2

, Joel D. Stitzel1,2

v

Poster

NumberSession Poster Title and Authors

Page

Number

1 A DO INSECT TRACHEAL TUBES COLLAPSE UNDER PRESSURE AS THIN-WALLED CYLINDERS? 29

Khaled Adjerid1

, Hodjat Pendar1

, Raffaella DeVita1

, and Jake Socha1

1Virginia Tech Biomedical Engineering And Mechanics

2 BVALIDATION OF A DIRECT METHOD FOR MEASURING HEPATIC AND SPLENIC PRESSURES OF

POST-MORTEM HUMAN SURROGATES DURING FULL-SCALE FRONTAL SLED TESTS30

Devon Albert1

,Stephanie M. Beeman1

, and Andrew R. Kemper1


3 A EFFECTS OF AUTOMATIC EMERGENCY BRAKING ON OCCUPANT KINEMATICS 31

Roy Anderson1

and Andrew R. Kemper1


4 BTHE IMPACTS OF PESTICIDE AND NICOTINE ON FUNCTIONAL BRAIN NETWORKS IN LATINO

FARMWORKERS32

Mohsen Bahami1

, Paul J. Laurienti1,2

, Thomas A. Arcury3

, and Sean L. Simpson1,4

1Virginia Tech – Wake Forest School of Biomedical Engineering and Science,

2Department of Radiology, Wake Forest School of Medicine,

3Department

of Family and Community Medicine, Wake Forest School of Medicine, 4

Department of Biostatistical Sciences, Wake Forest School of Medicine

5 A PROPOSED ANALYSIS OF MEG DELTA POWER FOLLOWING IMPACT EXPOSURE IN YOUTH 33

Leonardo Bezerra1

, Christopher Whitlow2

1Virginia Tech – Wake Forest School of Biomedical Engineering and Sciences,

2Wake Forest School of Medicineand Sciences

6 B BICYCLE HELMET IMPACT PERFORMANCE DURING REAL-WORLD OBLIQUE IMPACTS 34

Megan L. Bland1

, Craig McNally1

, David S. Zuby2

, Becky C. Mueller2

, and Steven Rowson1

1Virginia Tech Biomedical Engineering And Mechanics,

2Insurance Institute for Highway Safety, Ruckersville, VA

7 A KERATIN COATED PLASMA ETCHED PARYLENE C FOR NEURAL INTERFACES 35

Kyle Brown1

, Alexis Trent2

, and Mark Van Dyke3

1Virginia Tech, Biochemistry and Nanoscience,

2Virginia Tech, Material Science and Engineering,

3Virginia Tech, Biomedical Engineering and Sciences

8 B EVALUATING THE PERFORMANCE OF ALTERNATIVE SHOULDER STABILIZATION METHODS 36

Kristine Cantin1

, Sophia Ulman1

, Jang-Ho Park1

, Sunwook Kim1

and Maury A. Nussbaum1

1Virginia Tech

9 A SIMPLE, CUSTOMIZABLE, COST-EFFECTIVE NANOPARTICLE VACCINE DELIVERY SYSTEM 37

Jewel M. Cary1

and Dr. Abby R. Whittington1,2,3

1Virginia Tech-Wake Forest University (School of Biomedical Engineering & Sciences),

2Virginia Tech (Department of Materials Science and

Engineering), 3

Virginia Tech (Department of Chemical Engineering)

10 B RESPONSE OF FEMALE AND MALE PMHS TO BLAST-INDUCED VERTICAL ACCELERATIVE LOADING 38

Danielle M. Cristino1

, Warren N. Hardy1

1Virginia Polytechnic Institute and State University, Biomedical Engineering and Mechanics (BEAM)

11 A DEVELOPMENT OF 19F MRI TRACKABLE NANODELIVERY SYSTEM FOR ANTICANCER DRUGS 39

William Crowe1

, Zhi Dai1

, Lulu Wang1

, Zhongwei Zhang1

, Dawen Zhao1

1Department of Biomedical Engineering, Wake Forest University School of Medicine

12 BMEDICINE APPROACH TO IMPROVING RECONSTRUCTIVE SURGERY OUTCOMES FOR BREAST

CANCER SURVIVORS40

Katherine Degen1

, Kurtis Moyer2

, Robert Gourdie1

1Virginia Tech Carilion Research Institute, School of Biomedical Engineering,

2Carilion Clinic, Plastic and Reconstructive Surgery

13 A IMPULSIVITY IS REDUCED IN SOCIAL DRINKERS FOLLOWING REAL-TIME fMRI 41

Harshawardhan Deshpande1,2

, Jonathan Lisinski2

, Sarah Snider2

, Mikhail Koffarnus2

, Warren K. Bickel2,3

, and Stephen LaConte1,2

1Biomedical Engineering and Mechanics,

2Virginia Tech Carilion Research Institute,

3Psychology, Virginia Tech

14 B PHYSICS BASED MODEL FOR RHO-Z IMAGING FROM SPECTRAL COMPUTED TOMOGRAPHY 42

Xu Dong1

, Olga V. Pen1

, and Guohua Cao1

1Virginia Polytechnic Institute and State University, School of Biomedical Engineering and Sciences

15 ADOWNSTREAM MICROFLUIDIC COLLAGEN CULTURE CHAMBER FOR ADVANCING MECHANISTIC

UNDERSTANDING OF DIELECTROPHORETIC BEHAVIOR IN CELLS43

Temple A. Douglas1

, Philip Graybill2

, Nastaran Alinezhadbalalami1

, Nikita Balani1

, Jaka Cemazar1

, Eva M. Schmelz3

, Rafael

Davalos1

1Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences,

2Virginia Tech Department of Mechanical Engineering,

3Virginia Tech

Department of Human Nutrition, Foods and Exercise

vi

Poster


Page

Number

16 B ASSESSING FUNCTIONAL CONNECTIVITY CHANGES INDUCED BY CIMT USING FNIRS 44

Amnah M. Eltahir1,2

, Stephanie A. DeLuca2

, Brooks King-Casas2

, Stephen M. LaConte1,2

, and Sharon L. Ramey2

1Virginia Tech (Biomedical Engineering and Mechanics),

2Virginia Tech Carilion Research Institute

17 APREPARATION AND OPTIMIZATION OF CHEMICALLY MODIFIED ALGINATES AS VEHICLES FOR

TARGETED DRUG DELIVERY45

Kevin Enck1,2

, Surya Banks3

, Victor Agwu4

, Aubrey Peeden5

, Hariom Yadav6

, Mark Welker3

, Emmanuel C. Opara1,2

1SBES (Wake Forest University Campus),

2Wake Forest Institute for Regenerative Medicine (WFIRM),

3Dept. of Chem. (Wake Forest University),

4Biomedical Sciences Graduate School (Wake Forest University),

5Biotechnology (Forsyth Tech),

6Molecular Medicine (Wake Forest School of Medicine)

18 BPOSTURAL INFLUENCE ON THORACOABDOMINAL ORGANS OF 5TH, 50TH AND 95TH PERCENTILE

MALE SUBJECTS46

James P. Gaewsky1

, Katelyn Greene1

, F. Scott Gayzik1

, and Ashley A. Weaver1

1Wake Forest School of Medicine, Department of Biomedical Engineering

19 A A COMPUTATIONAL FLUID DYNAMICS MODEL OF THE INSECT RESPIRATORY SYSTEM 47

Joel Garrett1

, Rafael Davalos1

, Jake Socha1


20 BCHARACTERIZATION OF ELEVATED HEAD IMPACT EXPOSURE BETWEEN INDIVIDUAL YOUTH

FOOTBALL PLAYERS48

Ryan A. Gellner1

, Eamon T. Campolettano1

, Eric Smith2

, and Steven Rowson1

1Virginia Tech, Biomedical Engineering and Mechanics,

2Virginia Tech, Department of Statistics

21 AOPTIMIZATION OF HYDROGEL-BASED BIOINK PRINTABILITY USING RHEOLOGICAL

PARAMETERS: A SYSTEMATIC APPROACH49

Gregory J. Gillispie1,2

, Teng Gao2

, Josh Copus2

, James Yoo1,2

, Anthony Atala1,2


1Virginia Tech-Wake Forest, School for Biomedical Engineering Sciences,

2Wake Forest University, Wake Forest Institute for Regenerative Medicine

22 BMECHANICAL CHARACTERIZATION OF EMULSIFICATION POLYMERIZED KERATIN

MICROPARTICLES USING VARIED CROSSLINKING AGENTS50

Aaron Giuffre’1

, Marc Thompson2

, Mark Van Dyke2

1Virginia Tech, Electrical and Computer Engineering,


23 AJUMPING BEHAVIORS INCREASE GAP BRIDGING PERFORMANCE IN THE FLYING SNAKE

CHRYSOPELEA PARADISI51

Michelle R. Graham1

, Bruce Jayne2

, Talia M. Weiss1

, and Jake Socha2


2University of Cincinnati, Biology

24 BFAILED RIB REGION PREDICTION IN A HUMAN BODY MODEL DURING COLLISION EVENTS WITH

PRECRASH BRAKING52

Berkan Guleyupoglu1,2

, Jeremy Schap1,2

, Matt Davis1,2

, F. Scott Gayzik1,2

1Wake Forest University School of Medicine,

2Virginia Tech – Wake Forest Center for Injury Biomechanics

25 A MECHANOSENSITIVE RESPONSES OF ASTROCYTES TO SHOCK WAVE INSULT 53

Nora Hlavac1

and Pamela J. VandeVord1,2

1Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA,

2Salem Veterans Affairs Medical Center, Salem, VA

26 B QUANTIFYING LIMP USING TEMPORAL GAIT VARIABLES 54

Cherice Hughes-Oliver1

, Daniel Schmitt2

, Robin Queen1


2Duke University, Department of Evolutionary Anthropology

27 A BUCKLING BEHAVIOR OF SPINAL ANESTHESIA NEEDLES 55

Tessa Hulburt1

, Jessica M. Booth2

, Peter Pan2

, Philip J. Brown1

1Biomedical Engineering, Wake Forest Baptist Health,

2Anesthesiology, Wake Forest Baptist Health

28 BFLUID SHEAR STRESS IMPACTS OVARIAN CANCER CELL VIABILITY, SUBCELLULAR

ORGANIZATION, AND INDUCES MALIGNANT PHENOTYPES56

Alexandra R. Hyler1

, Nicolaas C. Baudoin2

, Mark A. Stremler1

, and Daniela Cimini2

, Rafael V. Davalos1

, Eva M. Schmelz1

1VT-WFU School of Biomedical Engineering, Virginia Tech, Blacksburg, VA,

2Department of Biological Sciences and Biocomplexity Institute, Virginia

Tech, Blacksburg, VA

29 A SKULL DEFLECTION EFFECTS ON BRAIN TISSUE RESPONSE USING FINITE ELEMENT SIMULATION 57

Derek A. Jones1,2

, Jillian E. Urban1,2,3

, Ashley A. Weaver1,2

, and Joel D. Stitzel1,2

1Virginia Tech-Wake Forest University Center for Injury Biomechanics,

2Wake Forest School of Medicine,

3Clinical and Translational Science Institute

30 B UPPER EXTREMITY INJURIES IN SIDE-IMPACT MOTOR VEHICLE COLLISIONS 58

Mireille E. Kelley1

; Jennifer W. Talton2

; Andrew O. Usoro3

; Ashley A. Weaver1

; Eric R. Barnard4

; Anna N. Miller5

1Virginia Tech-Wake Forest University, Center for Injury Biomechanics,

2Wake Forest School of Medicine, Department of Biostatistical Sciences,

3Massachusetts General Hospital, Department of Orthopedic Surgery,

4Loyola University Medical Center, Department of Orthopedic Surgery and

Rehabilitation, 5

Washington University School of Medicine, Department of Orthopedic Surgery

vii

Poster


Page

Number

31 A HOW TEMPERATURE INFLUENCES THE VISCOSITY OF HORNWORM HEMOLYMPH 59

Melissa C. Kenny1

, Matthew N. Giarra2

, and John J. Socha1

1Virginia Tech, Department of Biomedical Engineering and Mechanics,

2Virginia Tech, Department of Mechanical Engineering

32 B ENGINEERING THE GUT-LIVER-BRAIN AXIS TO INVESTIGATE CHEMICAL TOXICITY 60

Anjaney Kothari1

, Rebekah Less1

and Padma Rajagopalan1, 2, 3

1School of Biomedical Engineering and Sciences,

2Department of Chemical Engineering,

3ICTAS Center for Systems Biology of Engineered Tissues

(ISBET)

33 A INTEGRATED IN VITRO GUT-LIVER MODEL FOR THE INVESTIGATION OF FIRST PASS METABOLISM 61

Rebekah Less1

, Anjaney Kothari1

, Padma Rajagopalan1, 2, 3

1School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg VA, 24060,

2Chemical Engineering, Virginia Tech, Blacksburg VA, 24060,

3ICTAS Center for Systems Biology of Engineered Tissues, Virginia Tech, Blacksburg VA, 24060

34 BIRREVERSIBLE ELECTROPORATION FOR THE ABLATION OF PANCREATIC MALIGNANCIES: A

PATIENT-SPECIFIC METHODOLOGY62

Melvin F. Lorenzo1

, Eduardo L. Latouche1

, Michael B. Sano2,3

, Robert C. G. Martin II4


1Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia,

2Radiation Oncology, Stanford

University School of Medicine, Stanford, California, 3

UNC/NCSU Joint Department of Biomedical Engineering, Chapel Hill, North Carolina, 4

Surgery,

Division of Surgical Oncology, University of Louisville, Louisville, Kentucky

35 ACELL TYPE-SPECIFIC MOUSE BRAIN METHYLOMES PROFILED USING AN ULTRALOW-INPUT

MICROFLUIDIC DEVICE63

Sai Ma1

, Zhixiong Sun2

, Chen Sun1

, Travis W. Murphy3

, Hehuang Xie2,4

, Chang Lu2

1School of Biomedical Engineering and Sciences, Virginia Tech,

2Department of Biological Sciences, Virginia Tech,

3Chemical Engineering, Virginia

Tech, 4

Biocomplexity Institute, Virginia Tech

36 B 3D PRINTING OF CANCER ORGANOIDS FOR HIGH THROUGHPUT SCREENING 64

Andrea Mazzocchi1

, Shay Soker1

, Aleksander Skardal1,2

1Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC,

2Comprehensive Cancer Center of Wake Forest

School of Medicine, Winston-Salem, NC

37 AHYPERTHERMIA-INDUCING NANOPARTICLES AS ADJUVANT THERAPY FOR OXALIPLATIN-BASED

CHEMOTHERAPY IN COLORECTAL CANCER65

Bryce D. McCarthy1

and Nicole H. Levi-Polyachenko1

1Wake Forest School of Medicine, Department of Plastic and Reconstructive Surgery

38 BAN INVESTIGATION INTO THE VALIDATION AND FUTURE USE OF FE HYBRID III, THOR, AND

GHBMC M50-OS FOR SPACEFLIGHT CONFIGURATION TESTING66

Kyle P. McNamara1,2

, Derek A. Jones1,2

, James P. Gaewsky1,2





2Virginia Tech-Wake Forest University Center for Injury Biomechanics

39 ACHARACTERIZING HEAD IMPACT EXPOSURE IN YOUTH FEMALE SOCCER WITH A CUSTOM-

INSTRUMENTED MOUTHPIECE67

Logan E. Miller1

, Elizabeth Pinkerton1

, Lyndia Wu2

, Katie Fabian1

, David Camarillo2

, Joel D. Stitzel1

, and Jillian E. Urban1

1Department of Biomedical Engineering, Wake Forest School of Medicine,

2Department of Bioengineering, Stanford University

40 B AGENT-BASED MODELING TO PREDICT THE EFFECT OF ELECTROCHEMOTHERAPY ON TUMORS 68

Maryam Moarefian1

, Luke Achenie2

1Virginia Polytechnic Institute and State University, Mechanical Engineering Department,

2Virginia Polytechnic Institute and State University, Chemical

Engineering Department

41 A NOVEL DEVICE FOR PREVENTING RODENT WOUND SPLINT REMOVAL 69

Jade Montgomery1,2

, Linda J. Jourdan2

, and Robert G. Gourdie1,2

1Virginia Tech, School of Biomedical Engineering and Sciences,

2Virginia Tech Carilion Research Institute

42 B MITIGATING BIOFILM FORMATION WITH SURFACE TOPOGRAPHY MODIFICATIN 70

Carolyn Y. Mottley1

, Zhou Ye2

, AhRam Kim2

, and Bahareh Behkam1,2

1Virginia Tech, Department of Mechanical Engineering,

2Virginia Tech, School of Biomedical Engineering and Sciences

43 ATHE DEVELOPMENT OF AN INTELLIGENT SURGICAL PROBE FOR REAL-TIME MONITORING OF

ELECTROPORATION BASED TREATMENTS71

Timothy J. O’Brien1

, Mohammad Bonakdar2

, and Rafael V. Davalos1


2Virginia Tech, Mechanical Engineering

44 BCORTICAL THINNING AND STRUCTURAL BONE CHANGES IN NON-HUMAN PRIMATES FOLLOWING

72

Catherine Okoukoni, Ph.D.1,2,3

, Michael Farris, M.D.1

, Emory R. McTyre, M.D.1

, J. Daniel Bourland, Ph.D.1,2

, J. Mark Cline, DVM

Ph.D.4

, Greg Dugan DVM4

, Jeffrey S. Willey, Ph.D.1,3

1Wake Forest University, Department of Radiation Oncology,

2Wake Forest University, Department of Physics,

3Wake Forest University, Pathology

Department, 4

Wake Forest University School of Medicine

viii

Poster


Page

Number

45 AA FINITE ELEMENT MODEL OF A SMALL-STATURE FEMALE PEDESTRIAN FOR SIMULATING

TRAFFIC ACCIDENTS73

Wansoo Pak1

, Costin D. Untaroiu1

, Scott Gayzik2

1Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA,

2Department of Biomedical Engineering, Wake Forest

University School of Medicine, Winston-Salem, NC, USA

46 BQUANTITATIVE ANALYSIS OF THE EPIDERMAL NECROSIS IN CUTANEOUS RADIATION INJURIES

INDUCED BY BETA-SOURCE IRRADIATION74

Olga V. Pen1,2

, Peter A. Antinozzi3

, Nancy D. Kock4

, J. Daniel Bourland1,2

1Department of Radiation Oncology, Wake Forest School of Medicine, Wake Forest University,

2Department of Biomedical Engineering, VT-WFU SBES,

Wake Forest University, 3

Department of Biochemistry, Wake Forest University, 4

Department of Pathology and Comparative Medicine, Wake Forest

School of Medicine, Wake Forest University

47 ACHARACTERISTIC DIFFERENCES BETWEEN WATER DIALYZED AND BUFFER DIALYZED KERATOSE

BIOMATERIAL75

Nils A. Potter1

, Mark Van Dyke1

1Virginia Tech, Department of Biomedical Engineering and Mechanics

48 B 3D CELL CULTURE STUDIES IN MICROFLUIDIC SYSTEMS FOR TRANSLATIONAL APPLICATIONS 76

Shiny Rajan1,2,3

, Parker Hambright1

, Aleksander Skardal1,3,4

, and Adam R. Hall1,2,3,4

1Wake Forest University,


3Wake Forest Institute of Regenerative Medicine,

4Comprehensive Cancer Institute, Wake Forest

49 A CHANGES IN LIMB SYMMETRY DURING A 2 MILE OUTDOOR RUN 77

Kristen E. Renner1

, Robin M Queen1


50 BEFFECT OF NON-STEROIDAL ANTI-INFLAMMATORY DRUGS ON ACHILLES TENDINOPATHY IN A

MURINE MODEL78

Sabah N. Rezvani1

, Adam Bitterman2

, Anna Plaas3

, Jun Li3

, Vincent Wang1


2Northwell Health, Huntington, NY,

3Rush University Medical Center, Chicago, IL

51 AHIGH-FREQUENCY IRREVERSIBLE ELECTROPORATION TARGETS MALIGNANT CELLS IN OVARIAN

CANCER MODEL79

Andrea Rolong1

, Eva M. Schmelz2

, and Rafael V. Davalos1

1Virginia Tech – Wake Forest University School of Biomedical Engineering and Sciences,

2Virginia Tech, Department of Human Nutrition, Foods, and

Exercise

52 BPELVIC ANATOMICAL CHARACTERIZATION AND COMPARISON BY SEX AND HISTORY OF

PREGNANCY80

Mona Saffarzadeh1,2

, R. Caresse Hightower1,2


1Virginia Tech-Wake Forest University Center for Injury Biomechanics,

2Wake Forest University School of Medicine, Biomedical Engineering Department

53 AEFFECTS OF FEBUXOSTAT ON SOCIAL INTERACTION AND REPETITIVE GROOMING IN AUTISM

MICE 81

Vince Sannicalos1

, Molly Accord2

, Jaegu (Richard) Yea3

, Sukyoung (Chloe) Kim4

, Jamelle Simmons5

, and Yong Woo Lee5

1Virginia Tech, School of Neuroscience,

2Virginia Tech, Department of Chemical Engineering (ChemE),

3Virginia Tech, Department of Biological

Systems Engineering (BSE), 4

Virginia Tech, Department of Biochemistry, 5

Virginia Tech, Biomedical Engineering and Mechanics (BEAM)

54 B OPTICAL FIBER BASED IMAGING OF BIOENGINEERED TISSUE CONSTRUCT 82

Etai Sapoznik1,2

, Guoguang Niu2

, Peng Lu3

, Yu Zhou2

, Yong Xu3

, Shay Soker1,2

1Virginia Tech-Wake Forest Univ. School of Biomedical Engineering and Sciences,

2Wake Forest Institute for Regenerative Medicine,

3Virginia Tech,

Bradley Department of Electrical and Computer Engineering

55 ATRANSITIONAL LIVER MODELS FOR THE INVESTIGATION OF CHEMICAL AND MECHANICAL CUES

DURING THE PROGRESSION OF FIBROSIS83

Scott-Eugene Saverot1

, Sophia Orbach2

, Andrew Ford2

, Padmavathy Rajagopalan1, 2, 3

1Virginia Tech, School of Biomedical Engineering and Sciences,

2Virginia Tech, Department of Chemical Engineering,

3Virginia Tech, ICTAS Center for

Systems Biology of Engineered Tissues

56 BDIFFUSION MODEL ACROSS A BLOOD-BRAIN BARRIER (BBB) MIMIC FOR THE TREATMENT OF

AUTISM SPECTRUM DISORDER (ASD)84

Jamelle Simmons1

, Luke Achenie2,3

, and Yong W. Lee1,3

1Virginia Tech, Department of Biomedical Engineering and Mechanics (BEAM),

2Virginia Tech, Department of Chemical Engineering,

3Virginia Tech

Center for Autism Research (VTCAR)

57 A A SIMPLE TARGETED METHOD FOR THE REMOVAL OF FREE HEMOGLOBIN 85

Kelli N. Simms1

, Martin Guthold2

, Daniel B. Kim-Shapiro2

, Elaheh Rahbar1

*1

Department of Biomedical Engineering, Wake Forest School of Medicine, Winston Salem, NC, 2

Department of Physics, Wake Forest University, Winston

Salem, NC

58 BUSING VIDEOTAPED MOTION CODING TO IMPROVE UNDERSTAND OF F-NIRS SIGNAL CHANGES

86

Ben Stephens1

, Amnah Eltahir2

, Stephen LaConte3

, and Stephanie DeLuca3

1Virginia Tech Carilion School of Medicine,

2Virginia Tech, Biomedical Engineering,

3Virginia Tech Carillion Research Institute

59 A CALCULATION OF THE DIFFUSIVE PERMABILITY OF CELL MEMBRANES TO PROPIDIUM 87

Daniel C. Sweeney1

, James C. Weaver2


1Virginia Tech, Dpeartment of Biomedical Engineering and Mechanics,

2MIT, Harvard-MIT Division of Health Sciences and Technology

ix

Poster


Page

Number

60 B REAR IMPACT CRASHES IN THE UNITED STATES: HOW DANGEROUS ARE THEY? 88

Whitney M. Tatem1

and H. Clay Gabler1


61 BA MECHANISTIC EVALUATION OF INTRINSIC CROSSLINKING PROPERTIES AND SYNTHESIS

PROCEDURES FOR KERATIN-BASED MICROPARTICLES89

Marc Thompson1

, Aaron Giuffre’2

, Mark Van Dyke1

1Virginia Tech. Blacksburg, VA, Biomedical Engineering and Mechanics,

2Virginia Tech. Blacksburg, VA, Electrical and Computer Engineering

62 ACELL-SUBSTRATE INTERACTIONS ON CHARACTERIZED KERATIN COATING FOR PERCUTANEOUS

PROSTHETIC APPLICATIONS90

Alexis Trent1

, Mark Van Dyke2

1Department of Material Science and Engineering, Virginia Tech, Blacksburg, VA,

2Department of Biomedical Engineering and Mechanics, Virginia Tech,

Blacksburg, VA

63 B ANALYSIS OF BILIARY STENT HINGES USING ABAQUS 91

Aaron R. Van Gorkom1

, Greg J. Gillispie1

, Clifford Howard Jr2

, Philip J. Brown1

1Biomedical Engineering, Wake Forest Baptist Health,

2Wake Forest University Baptist Medical Center

64 ALASER INDUCED PRECISION HEATING FOR IMPROVED BACTERIAL DESTRUCTION WITH

GENTAMICIN 92

Kenneth A. Vogel1

, Anila Pullagura1

, Nicole Levi-Polyachenko1

1Wake Forest University (School of Medicine, Plastic and Reconstructive Surgery)

65 BSHIFTS IN CIRCULATING POLYUNSATURATED FATTY ACID LEVELS IN CHILDREN WITH

TRAUMATIC BRAIN INJURY93

Charlotte Mae K. Waits1

, Steven C. Kosmach2

, Susan Sergeant3

, Floyd H. Chilton4

, Charles S. Cox, Jr2

, and Elaheh Rahbar1

1Department of Biomedical Engineering, Wake Forest School of Medicine,

2Department of Pediatric Surgery, McGovern Medical School at the University

of Texas Health Sciences Center at Houston, 3

Department of Biochemistry, Wake Forest School of Medicine, 4

Department of Physiology and

Pharmacology, Wake Forest School of Medicine

66 AHIGHLY SPECIFIC AND MODULAR AFFINITY LABELING OF EPIGENETIC MODIFICATIONS

94

Fanny Wang1

, Osama K. Zahid1

, Brandi E. Swaibe2

, and Adam R. Hall1,3

1Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences,

2Wake Forest University, Department of Physics,

3Wake Forest University

School of Medicine, Comprehensive Cancer Center

67 BFABRICATING AND TUNING AN ELASTOMERIC BLOOD VESSEL FOR USE IN CORONARY ARTERY

BYPASS SURGERIES95

Harleigh J. Warner1

and William D. Wagner1

1Plastic and Reconstructive Surgery and School of Biomedical Engineering and Sciences, Wake Forest University School of Medicine, Winston-Salem, NC

68 AA RAT MODEL OF SEVERE OSTEOPOROSIS FOR TESTING BONE REGENERATION CONSTRUCTS

96

Michele Waters1

, Nils Potter1

, Marc Thompson1

, Alexis Trent2

, Pamela VandeVord1

and Mark Van Dyke1


2Virginia Tech, Materials Science and Engineering

69 BNON-INVASIVE DETECTION OF RESPIRATION AND HEART RATE WITH A VEHICLE SEAT WEIGHT

SENSOR: A FEASIBILITY STUDY97

Grace C. Wusk1

and Hampton C. Gabler1

1Virginia Tech, Biomedical Engineering

70 AINVESTIGATION OF MLL3 COMPLEX IN DNA REPAIR MECHANISM IN LUNG ADENOCARCINOMA

98

Ted G. Xiao1

, Wei Zhang2

1Wake Forest School of Medicine, Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences,


Department of Cancer Biology

71 BDEVELOPMENT AND VALIDATION OF A GOTTINGEN MINIATURE PIG FINITE ELEMENT MODEL TO

INVESTIGATE INJURY SCALING TECHNIQUES99

Keegan M. Yates1

, Costin D. Untaroiu1

1Virginia Tech, Center for Injury Biomechanics

72 ANUMERICAL INVESTIGATION OF LOWER EXTREMITY INJURIES IN FRONTAL CRASH

RECONSTRUCTION 100

Xin Ye1,2

, James Gaewsky1,2

, Derek Jones1,2

, Logan Miller1,2

, Mireille Kelly1,2

, Jeff Suhey1,2

, Bharath Koya1,2

, Ashley Weaver1,2

and Joel Stitzel1,2

1Wake Forest University School of Medicine

73 B PERICYTE CELL LINE ISOLATION, VALIDATION AND APPLICATIONS 101

Huaning Zhao1

, John C. Chappell1,2

1School of Biomedical Engineering and Science,

2Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute

x

xi

xii

Thank you to Wake Forest Innovations for their gracious sponsorship of the 2017 SBES Graduate Student Research Symposium.

Wake Forest Innovations improves health through collaborative innovation so that important scientific

discoveries can become life-improving realities.

We accomplish this through our three Centers:

Center for Technology Innovation & Commercialization – accelerates the development and

commercialization of inventions.

Center for Industry Research Collaboration – expedites access to specialized clinical and

research capabilities.

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We believe collaborative innovation between our faculty and staff and with industry is based on sharing

expertise, knowledge, risk and reward at all stages of product research and development.

For more information, please visit their website at www.WakeForestInnovations.com.

Wake Forest Innovations 575 North Patterson Avenue, Suite 550 Winston-Salem, NC 27101 [email protected]

http://www.wakeforestinnovations.com/

mailto:[email protected]

xiii

Thank you to Medtronic for their gracious sponsorship of the 2017 SBES Graduate Student Research Symposium. Visit Medtronic’s website to discover how they are creating life-changing therapies to help people with chronic diseases.

As a global leader in medical technology, services and solutions, Medtronic improves the health

and lives of millions of people each year. We believe our deep clinical, therapeutic and

economic expertise can help address the complex challenges — such as rising costs, aging

populations and the burden of chronic disease — faced by families and healthcare systems

today. But no one can do it alone. That’s why we’re committed to partnering in new ways and

developing powerful solutions that deliver better patient outcomes.

Founded in 1949 as a medical repair company, we're now among the world's largest medical

technology, services and solutions companies, employing more than 85,000 people worldwide,

serving physicians, hospitals and patients in more than 155 countries. Join us in our

commitment to take healthcare Further, Together. Learn more at Medtronic.com.

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http://www.medtronic.com/

xiv

Thank you to the Biomedical Engineering Society for their gracious sponsorship of the 2017 SBES Graduate Student Research Symposium. Please visit their website to learn how they have become the leading society of professionals devoted to developing and using engineering to advance human health and well being.

The Biomedical Engineering Society (BMES) is the professional society for biomedical engineering and

bioengineering. Founded in early 1968, the Society now boasts over 7,000 members and is growing, rapidly.

BMES serves as the lead society and professional home for biomedical engineering and bioengineering. Our

leadership in accreditation, potential licensure, publications, scientific meetings, global programs, and diversity

initiatives, as well as our commitment to ethics, all serve our mission to promote and enhance knowledge and

education in biomedical engineering and bioengineering worldwide and its utilization for human health and well-

being.

The Vision of BMES is to serve as the world's leading society of professionals devoted to developing and using

engineering and technology to advance human health and well-being.

The Mission of BMES is to build and support the biomedical engineering community, locally, nationally and

internationally, with activities designed to communicate recent advances, discoveries, and inventions; promote

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Leading and emerging researchers use BMES as a platform for sharing the latest information and research in the

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For more information, please visit the BMES website at www.bmes.org BMES 8201 Corporate Drive, Suite 1125 Landover, MD 20785-2224 [email protected]

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http://www.bmes.org/

16th Annual Graduate Student

Research Symposium

Student Abstracts

1 Evaluations of Head Injury Oral: Drillfield, 1:00

16th Annual Graduate Student Research Symposium, May 10, 2017

EPIGENETIC MECHANISMS IN BLAST INDUCED NEUROTRAUMA

Zachary S. Bailey1, Pamela J. VandeVord1,2

1. Virginia Tech, Biomedical Engineering and Mechanics 2. Salem Veterans Affairs Medical Center

Corresponding Author: Zachary Bailey, Email: [email protected] INTRODUCTION More than 25% of the Veterans returning from Operations Enduring and Iraqi Freedom, and New Dawn (OEF/OIF/OND) are suffering from closed head injuries due to blast exposure1. Despite its frequency, no cure exists and the injury mechanisms are poorly understood. Blast waves typically originate following an explosion. The rapid expansion of combustion products from the detonation leads to the outward, supersonic, flow of the surrounding air, deemed the blast wave. The displacement of air from the source leads to areas of negative pressure relative to ambient conditions. This triggers the reversal of flow towards to blast origin and re-establishes ambient pressures. At a distant observation point from the blast origin, these complex flow dynamics will lead to a pressure profile characterized by a rapid rise in pressure followed by an exponential decay and a brief negative phase before returning to ambient conditions. Clinical manifestations of blast induced neurotrauma (BINT) involve long-term functional and psychological impairments driven by underlying neuropathology that including oxidative stress, blood brain barrier disruption and reactive astrocytosis. The overall hypothesis of this work is that epigenetic regulatory mechanisms contribute to the progression of the BINT pathology and neurological impairments. Epigenetic mechanisms, including DNA methylation and histone acetylation, are important processes by which cells respond to various environmental stimuli and regulate transcription. To date, the role of epigenetics in BINT remains unknown. METHODOLOGY The blast wave was generated using a custom Advanced Blast Simulator that consists of three distinct sections to create, develop, and dissipate the blast wave. The wave originates following helium-driven rupture of calibrated acetate membranes. Pressure measurements were collected at 250 kHz using a Dash 8HF data acquisition system. Analysis of pressure profiles was conducted using a custom Matlab script. Following blast exposure, animals

underwent established behavioral tests to assess functional and psychological impairments. Reverse-transcription polymerase chain reaction, Western Blot, and immunofluorescence techniques were used to assess protein levels/modifications, gene expression, and DNA modifications at various time points following blast. RESULTS The progression of the BINT pathology is manifested as motor function deficits, increased anxiety, and decreased memory function. The underlying neuropathology involves both DNA methylation and histone acetylation changes. Analysis of DNA methylation levels following blast exposure elucidated time-dependent DNA methylation decreases in the hippocampus, a critical region in memory function. No DNA methylations changes were observed in the acute stages of injury but were prevalent in the sub-acute stages which indicate a role in secondary injury cascades. We also observed histone acetylation decreases for histones H2b, H3, and H4. After observing significant increases in astrocyte activation, immunoflourescence showed decreased H3 acetylation in astrocytes following blast exposure. Western blot analysis of intra-cellular signaling molecules responsible for regulating histone acetylation showed increased nuclear localization. CONCLUSIONS The observed changes to DNA methylation and histone acetylation have a potentially broad impact cellular function which may be important to the injury progression. Chronically, BINT increases risk for Alzheimer’s disease and post-traumatic stress disorder which may also involve such changes2. Continuing to increase our understanding of BINT will mitigate current clinical obstacles by making the development of treatment strategies more efficient. REFERENCES 1. MacGregor et al., (2011). J Head Trauma Rehabil. 2. Hoge et al. (2008). N Engl. J Med.

Oral: Duckpond, 9:45 Modeling the Human Body 2


DEVELOPMENT AND VALIDATION OF A FINITE ELEMENT MODEL OF THE WIAMAN LOWER

EXTREMITY

Wade A. Baker1, Costin Untaroiu1, and Mostafiz Chowhurdy2

1. Virginia Tech, BEAM 2. Army Research Laboratory

INTRODUCTION Improvised explosive devices were extensively used by insurgents to target occupants of military vehicles during the conflicts in Iraq and Afghanistan. Casualties of an IED attack are highly susceptible to lower extremity injuries. In a survey of 3,575 extremity wounds, explosive munitions accounted for 75% of injuries [1]. Automotive anthropomorphic test devices (ATD) have been optimized to mimic the kinematic and dynamic responses of a human during the frontal and side impacts characteristic of automotive collisions. However, when subjected to vertical loading conditions these ATDs exhibit poor biofidelity [2]. In order to assess vehicle safety and make informed improvements to vehicle design, a novel Anthropomorphic Test Device (ATD) was developed and optimized for vertical loading. The main objective of this study was to develop and validate a finite element (FE) model of the ATD lower extremity. METHODOLOGY A numerical model of the lower extremity was developed for LS-DYNA based on geometry of the physical dummy. All connections, including joints and hardware, were explicitly modeled and deformable. The soft materials in the dummy, which have the greatest influence on biofidelity, were characterized through uniaxial tension and compression tests. Non-linear strain rate dependent materials were implemented in the FE model based on characterization results. Experiments conducted on the Vertically Accelerated Load Transfer System (VALTS) were used to validate the lower extremity model. Validation was performed with and without the presence of a military combat boot. Comparison between simulation outputs and associated test data was used to validate the FE model. Correlation scores between the simulations and experiments were calculated using the objective rating system Corrlelation and Analysis (CorA). RESULTS

The proposed numerical models of materials exhibiting viscoelastic responses show good correlation to the specimen test data at both high and low strain rates. An example validation is shown in Figure 1 for the unbooted model at an impact rate of 2 m/s. The unbooted model was validated at four different loading rates (max 6m/s) and the booted model was validated at five loading rates (max 12m/s).

Figure 1: Comparison of FE to experiment at the load

cell built in to the tibia shaft of the ATD. CONCLUSIONS Simulations of the entire WIAMan-LX correlate well to the WIAMan physical dummy tests. Good results of the model backed by high objective rating scores lead to the recommendation to use it in numerical studies related to dummy design improvements. ACKNOWLEDGMENTS The authors would like to thank Army Research Laboratory for their support REFERENCES [1] Owens BD, Kragh JF, Wenke JC, Macaitis J, Wade CE, Holcomb JB. Combat wounds in operation Iraqi Freedom and operation Enduring Freedom. J Trauma 2008 [2] Bir C, Barbir A, Dosquet F, Wilhelm M, van der Horst M, Wolfe G. Validation of lower limb surrogates as injury assessment tools in floor impacts due to anti-vehicular land mines. Mil Med 2008

Tibi

a Fo

rce

(kN

)

3 The Tumor & Tissue Microenvironments Oral: Drillfield, 10:00


N-(3-OXODODECANOYL)-L-HOMOSERINE LACTONE INTERACTIONS IN THE BREAST TUMOR

MICROENVIRONMENT: IMPLICATIONS FOR BREAST CANCER VIABILITY AND PROLIFERATION IN VITRO

Brittany N. Balhouse1, Logan Patterson

2,3, Eva M. Schmelz

4, Daniel J. Slade

2 and Scott S. Verbridge

1

1. School of Biomedical Engineering and Sciences, Virginia Tech-Wake Forest University, Blacksburg, VA, USA

2. Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA

3. Department of Pathology, University of Virginia, Charlottesville, VA, USA

4. Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA, USA

Corresponding Author: Brittany N. Balhouse, Email: [email protected]

INTRODUCTION

Hypoxia and dense tumor stroma in the breast tumor

microenvironment predispose cancer progression and

therapy resistance, yet the role of the breast resident

microbiome in this interplay remains uncharacterized. We

hypothesized that the effect of breast relevant bacterial

molecules on breast cell viability and proliferation would

be cell type and culture condition dependent.

METHODOLOGY

We used viability, proliferation, and apoptosis/necrosis

assays in order to assess the effect of bacteria quorum-

sensing molecule N-(3-oxododecanoyl)-L-homoserine

lactone (OdDHL) on human breast adenocarcinoma cells

(MDA-MB-231, MCF-DCIS.com) and non-malignant

breast epithelial cells (MCF-10A) in normoxia and

hypoxia (1% O2) in 2D and in a normoxic 3D

environment (type I collagen hydrogel tissue mimic).

RESULTS

OdDHL selectively decreases viability in breast cancer

cells and has no significant effect on the viability of

normal breast epithelial cells (Fig 1). The effect of

OdDHL is dependent both on cell type and the culture

condition to which the cells are exposed (Fig 1).

Figure 1: The effect of OdDHL is cell type and culture

condition dependent.

It was found that OdDHL treatment not only decreases

proliferation of MDA-MB-231 cells (data not shown), but

also selectively increases MDA-MB-231 necrosis in all

culture conditions (Fig 2). OdDHL also decreased

apoptosis and necrosis for MCF-10A cells in the

3D/normoxia condition (Fig 2).

Figure 2: OdDHL selectively induces necrosis in MDA-

MB-231 cells in all culture conditions.

Thus, the decrease in MDA-MB-231 viability associated

with the OdDHL treatment (Fig 1) is caused by both

decreased proliferation and induction of necrosis (Fig 2).

CONCLUSIONS

This study demonstrates the importance of microbiome-

produced molecules in the tumor microenvironment.

Though the effect of OdDHL was blunted with hypoxia

and 3D culture, it still significant decreased MDA-MB-

231 viability. OdDHL and other microbiome-produced

molecules may hold promise as anti-cancer therapies.

ACKNOWLEDGMENTS

We would like to thank Sara Peterson, Dr. Akanksha

Kanitkar, Dr. Ann Stevens for their assistance.

Oral: Drillfield, 1:45 Evaluations of Head Injury 4


HIGH MAGNITUDE HEAD IMPACT EXPOSURE IN YOUTH FOOTBALL

Eamon T. Campolettano1, Ryan A. Gellner1, and Steven Rowson1

1. Biomedical Engineering and Mechanics (Virginia Tech) Corresponding Author: Eamon Campolettano, Email: [email protected]

INTRODUCTION Most research quantifying head impact exposure in football has focused on high school, collegiate, or professional populations despite youth football players representing 70% of all players in the United States. Biomechanical investigations of youth football have been invaluable in promoting player safety, but the specific causation of higher risk head impacts remains unknown.1,2 The objective of this study was to quantify high magnitude head impact exposure in youth football games and compare that to practice. METHODOLOGY This study investigated head impact exposure and included 45 players (age 10.7 ± 1.1), who received helmets instrumented with accelerometer arrays associated with the HIT System. Players wore the instrumented helmets at each practice and game throughout the season. There were two teams in this study that represented different age groups: Juniors (age 9.9 ± 0.6) and Seniors (age 11.9 ± 0.6). Games and practices were filmed to facilitate video verification of head impacts. All impacts exceeding 40 g were categorized based on the part of the field it occurred in (open field or line of scrimmage), the cause of impact (blocking or tackling), and the specific practice activity (Blocking, Offense vs Defense, Tackling – No Blocker, or Tackling – Blocker), if applicable. Impact rates were compared between games and practice. ANCOVA was used to determine the effect of the factors position and team on high magnitude head impact exposure, while controlling for the continuous covariates of age, weight, and number of practices. RESULTS Among a total of 7590 impacts, 571 (8%) exceeded 40 g. These high magnitude impacts were comprised of 381 (67%) practice impacts and 190 (33%) game impacts. In practice, 4.5% of all impacts for Juniors were high magnitude, while 9.0% of practice impacts for Seniors

exceeded 40 g. For games, 6.6% and 11.4% of impacts for Juniors and Seniors respectively were categorized as high magnitude. Impact rates for most activities were higher for Seniors than Juniors (Figure 1).

Figure 1: For both teams, games were associated with a

higher impact rate than practices. CONCLUSIONS Knowledge of the specific impact scenarios that most frequently occur in games would allow coaches and leagues to construct practice drills that more effectively mimic these impacts. The practice conducted by Seniors was 2x as likely to produce high magnitude impacts as Juniors’ practice. This alludes to increased intensity of Seniors’ practice relative to Juniors’. How practice activities are conducted contributes towards the overall high magnitude head impact exposure for practice, not just the practice activity itself. ACKNOWLEDGMENTS The authors are grateful to the NIH-NINDS under award number R01NS094410 for supporting this work. REFERENCES [1] Daniel, R. et al., Ann. Biomed. Eng., 40(4):976– 981, 2012. [2] Cobb, B. et al., Ann. Biomed. Eng., 41(12): 2463-2473, 2013.

5 The Tumor & Tissue Microenvironments Oral: Drillfield, 9:30


ANALYZING HYPOXIA INDUCED EPIGENETIC VARIATIONS IN CELL SUBPOPULATIONS IN THE TUMOR

MICROENVIRONMENT

Megan C. Cox1, Chengyu Deng2, Yan Zhu2, Yuan-Pang Hsieh2, Chang Lu2, and Scott S. Verbridge1

1. Virginia Tech, Department of Biomedical Engineering and Mechanics 2. Virginia Tech, Department of Chemical Engineering

Corresponding Author: Megan C. Cox, Email: [email protected] INTRODUCTION The tumor microenvironment (TME) and the cancer cell population are highly heterogeneous and are implicated in enhancing the therapeutic resistance of the tumor.1 Epigenetic alterations have been shown to be an important mechanism driving the rapid development of phenotypic variability within a tumor. Specifically, hypoxia can drive phenotypic changes and increase the angiogenic potential of the TME by promoting the production of vascular endothelial cell growth factor (VEGF), enhancing tumor progression.2 The study of epigenetic variations has been inhibited by the need for large cell numbers for analysis. We hypothesize that the utilization of a microfluidic ChIP assay, capable of analyzing as few as 50 cells3, along with discrete localized cell sampling from a gradient generating in vitro platform, will enable us to analyze the role of TME heterogeneity in driving the epigenetic alterations that contribute to therapeutic resistance. METHODOLOGY U87 or U251 glioblastoma multiforme cells will be seeded within an oxygen gradient generating microfluidic device (Figure 1a). Regions of hypoxia will be determined through COMSOL modeling (Figure 1b) and HypoxyprobeTM staining within the platform. Cell samples will be collected from the gradient scaffold and analyzed using ChIP-PCR for histone modifications on the VEGF promoter gene.

Figure 1: (a) U87 in gradient platform, (b) COMSOL

model of oxygen gradient in platform RESULTS Prior to analyzing cells cultured in the gradient generating platform, U87 cells cultured in normoxic and hypoxic

conditions were analyzed using ChIP-PCR for H3K4 methylation of the VEGF promoter gene. The robustness of our microfluidic ChIP protocol was validated by maintaining consistent results when analyzing a 10,000 and 1,000 cell sample group (Figure 2). HypoxyprobeTM labeling of cells in the platform and analysis of cells sampled from platform will be presented at a later time.

Figure 2: ChIP-PCR analysis of H3K4me3 on VEGF

promoter

CONCLUSIONS The ability to understand the complex dynamics occurring within a tumor is essential to developing effective treatment strategies. Analyzing how the heterogeneity within the TME may impact the development of phenotypic variability within a cancer cell subpopulation may enable the discovery of combinatorial therapeutic strategies that target different cellular weaknesses and overcome the resistance limitations that are inherent in more simplistic treatments. ACKNOWLEDGMENTS This work was supported by the NIBIB of the NIH under Award Number R21EB019123 and the College of Engineering and the Institute for Critical Technologies and Applied Sciences at Virginia Tech. REFERENCES 1. Marusyk, A. et al., Nat Rev Cancer, 2012, 12, 323-34 2. Harris, A.L., Nat Rev Cancer, 2002, 2, 38-47 3. Geng, T. et al., Lab Chip, 2011, 11, 2842-48

Oral: Duckpond, 2:30 Crash Injury & Prevention 6


DEVELOPMENT AND FULL BODY VALIDATION OF A 5TH PERCENTILE

FEMALE FINITE ELEMENT MODEL

Matthew L. Davis1,2, Bharath Koya1,2, Jeremy M. Schap1,2, and F. Scott Gayzik1,2

1. Virginia Tech-Wake Forest Center for Injury Biomechanics 2. Wake Forest School of Medicine

Corresponding Author: Matthew Davis, Email: [email protected] INTRODUCTION Computational human body modeling has become an important tool for the development of safety devices in the automotive and defense industries. Such models are often developed to represent a 50th percentile male (M50). However, in order to address the effects of size and sex-related changes in geometry, there is interest in developing models of other cohorts. This study focuses on the female in the 5th percentile of height and weight (F05). The objective of this study is to apply a comprehensive medical image and anthropometrical dataset to generate and validate a detailed finite element model (FEM) of the F05 occupant (F05-O). METHODOLOGY The F05-O model geometry was developed using a multi-modality medical image dataset collected from a representative small female subject in the supine, seated, and standing postures [1]. The CAD geometries assembled from the medical images were utilized for mesh development of the F05-O FEM. The model was compared to experimental data in 10 validation cases ranging from localized rigid hub impacts to full body sled cases. In order to make comparisons to experimental data, which represent the mass of an average male, the model was compared to experimental corridors using two methods: 1) post-hoc scaling the outputs from the baseline F05-O and 2) geometrically morphing the model to the body habitus of the average male. This second step required running the morphed full body model in all cases for a total of 20 simulations in the study. Model outputs were objectively evaluated using ISO/TS 18571. RESULTS The F05-O model consists of 981 parts, 2.6 million elements, and 1.4 million nodes [1]. Thresholds were placed on several element quality criteria: Jacobian (>0.3 for solid elements and >0.4 for shells), tet-collapse (>0.2), zero intersections, and a minimum time step of 0.1 µs. Overall, morphing the model was found to more closely match the target data with an average ISO score for the

rigid impacts of 0.76 compared to 0.67 for the scaled responses. Based on these data, the morphed model was used for model validation in the vehicle sled cases and attained an average weighted score of 0.69. An abdominal bar impact can be seen as an example in Figure 1.

Figure 1: Example of F05-O model response.

CONCLUSIONS This study describes the development of an anatomically representative small female FEM. The F05-O is the third in the GHBMC family of detailed occupant models (M50, M95) [2, 3]. As such, the F05-O will not only be used for the prediction of injury risk for small women, but will also provide a tool for evaluating differences in biomechanical response for occupants of varying body habitus. Furthermore, quantitative comparison between various approaches of model output scaling will provide needed insight, particularly as human body modeling is extended to body sizes beyond the average male. ACKNOWLEDGMENTS Funding for this project was provided by the Global Human Body Models Consortium, LLC REFERENCES [1] Davis et al. Stapp Car Crash J. 60(2016) 509-44. [2] Gayzik et al. ABME 39(2011), 2568. [3] Vavalle et al. Stapp Car Crash J. 58(2014) 361.

7 Evaluations of Head Injury Oral: Drillfield, 1:30


MODULAR USE OF HUMAN BODY MODELS OF VARYING LEVELS OF COMPLEXITY: VALIDATION OF

HEAD KINEMATICS

William Decker1,2, Bharath Koya2, Matthew L. Davis1,2, and F. Scott Gayzik1,2

1. Wake Forest University School of Medicine 2. Virginia Tech – Wake Forest University Center for Injury Biomechanics

Corresponding Author: F. Scott Gayzik, Email: [email protected] INTRODUCTION The significant computational resources required to execute detailed human body finite element models has motivated the development of faster running simplified models (e.g. GHBMC M50-OS). Previous studies have demonstrated the ability to modularly incorporate the validated GHBMC M50-O brain model into the simplified model (GHBMC M50-OS+B), which allows for localized analysis of the brain in a fraction of the computation time required for the detailed model. The objective of this study is to validate the head and neck kinematics of the GHBMC M50-O and M50-OS (detailed and simplified versions of the same model), as well as the M50-OS+B, against human volunteer test data in frontal and lateral loading.

Figure 1: Process of brain integration.

METHODOLOGY Data from the Navy Biodynamics Laboratory (NBDL) human volunteer studies, including a 15g frontal, 8g frontal, and 7g lateral impact were reconstructed and simulated using LS-DYNA. A five-point restraint system was used for all simulations and initial positions of the models were matched with volunteer data using settling and positioning techniques. Both the frontal and lateral simulations were run with the M50-O, M50-OS, and M50-OS+B with active musculature for a total of 9 runs.

15g Frontal 8g Frontal 7g Lateral

Figure 2: Visual comparison of the three simulations.

M50-O is shown at maximum head rotation.

RESULTS The M50-OS and M50-OS+B exhibited a 32 and 9 fold reduction in run time respectively compared to the M50-O. Corridors were re-analyzed for head and T1 kinematics from the NBDL studies. Qualitative evaluation of head rotational accelerations and linear resultant acceleration, as well as linear resultant T1 acceleration, showed reasonable results between all models and the experimental data. Objective evaluation of the kinematic results was completed via ISO TS 18571 with scores for each model ranging generally from 0.6-0.7 in all simulations. The three HBMs experienced similar head and neck motion in the frontal simulations, but the M50-O predicted significantly greater head rotation in the lateral simulation. CONCLUSIONS The greatest departure from the detailed occupant models were noted in lateral flexion. Precise modeling of the belt system however was limited by available data. A sensitivity study of these parameters in the frontal condition showed that belt slack and muscle activation have a modest effect on the ISO score. The reduction in computation time of the M50-OS+B reduces the burden of high computational requirements when handling detailed HBMs. ACKNOWLEDGMENTS Funding was provided by the Global Human Body Models Consortium, LLC (GHBMC) which is supported by its member companies, participants and the National Highway Traffic Safety Administration (NHTSA). REFERENCES [1]Wismans J et al. Omni-directional human head-neck response: SAE Technical Paper;1986. 0148-7191. [2]Thunnissen J et al. Human Volunteer Head-Neck Response in Frontal Flexion: A New Analysis. Society of Automotive Engineers, Inc. . 1995.

Oral: Drillfield, 10:15 The Tumor & Tissue Microenvironments 8


RHEOLOGY VS ALIGNMENT: TWO OPERATORS OF THE MECHANICAL TUMOR MICROENVIRONMENT

Mahesh Devarasetty1,2, Aleksander Skardal1,2, and Shay Soker1,2

1. Wake Forest University, Institute for Regenerative Medicine 2. Virginia Tech Wake Forest University, School of Biomedical Engineering and Sciences

Corresponding Author: Mahesh Devarasetty, Email: [email protected] INTRODUCTION The tumor microenvironment is a complex space consisting of a number of stimuli such as: stromal cells, signaling and paracrine factors, as well as extracellular matrix (ECM) components. Each of these factors push and pull cancer cells in different directions and the sum of the interactions defines a cancer cell’s final disposition. Much has been made of the microenvironment in recent years; one hotly researched aspect is ECM mechanics. In terms of the mechanical interaction of the ECM and the cancer cell, a number of observations have been made, such as: stiffer environments produce more aggressive cancer cells and facilitate migration and invasion[1], and aligned matrices are associated with healthy tissues while unaligned matrices are associated with poor prognosis[2]. Although there is a wealth of literature describing the interaction of both stiffness and alignment, there are few studies that determine the relative input of either stimuli. In this study, we produce submucosal constructs with varying ECM alignments and stiffnesses to provide a framework for understanding these two inputs in a single model system. METHODOLOGY Submucosal organoids are produced from collagen I hydrogel and primary rabbit smooth muscle cells. Stiffness is assayed using rheometry to produce stress-strain relationships while alignment is derived from picrosirius red imaging and image segmentation. Using HCT-116 cell spheroids, we then integrate a tumor compartment into the submucosal construct. Finally, we use WNT activity and epithelial-to-mesenchymal transition (EMT) markers to assess the relative effects of stiffness and alignment on cancer cell progression. RESULTS Collagen I hydrogels of stiffness ranging from 400Pa to 1000Pa were produced then HCT-116 spheroids were embedded within. These spheroids expressed high WNT activation and high Ki-67 expression across all stiffnesses. Then, organoids composed of collagen I and

various cell types were produced and HCT-116 spheroids were embedded within. These organoids displayed varied alignment as seen in Figure 1. Spheroids from organoids with highly aligned matrices demonstrated a reversion from the cancerous, mesenchymal phenotype towards a healthy, epithelial phenotype. In addition, highly disorganized alignment yielded more mesenchymal (cancer-like) phenotypes.

Figure 1: High, Medium, and Not Aligned Matrix CONCLUSIONS We observe matrix alignment produces a dominating effect on cancer cell phenotype across the stiffnesses assayed. Higher stiffness is associated with slightly increased WNT activity, but this effect is significantly diminished when spheroids are cultured in highly aligned matrices. ACKNOWLEDGMENTS WFIRM T32 Fellowship, DTRA XCEL REFERENCES [1] Zaman MH, et al. Migration of tumor cells in 3 D matrices is governed by matrix stiffness along with cell-matrix adhesion and proteolysis. Proc Natl Acad Sci USA. 2006. [2] Birk JW, et al. Second harmonic generation imaging distinguishes both high-grade dysplasia and cancer from normal colonic mucosa. Digestive diseases and sciences. 2014.

9 Biomaterials Development & Characterization Oral: Smithfield, 10:00


EFFECT OF PRESERVATION FLUID TYPE ON THE FAILURE MATERIAL PROPERTIES OF BOVINE LIVER

PARENCHYMA WITH INCREASING POST MORTEM TIME

Kristin M. Dunford1 and Andrew R. Kemper

1

1. Virginia Tech, Department of Biomedical Engineering and Mechanics

Corresponding Author: Kristin M. Dunford, Email: kmcamp.edu

INTRODUCTION

The liver is the second most frequently injured abdominal

organ in motor vehicle collisions (MVCs). Lacerations or

crushing of the liver can result in potentially life

threatening internal bleeding. Although current

anthropomorphic test devices are used to predict injuries

in MVCs, they are not equipped to represent abdominal

organs or assess abdominal organ injury risk.

Consequently, finite element models are frequently used

to assess abdominal organ injury risk in MVCs. The

material response of soft tissue can change considerably

after death. Previous studies have observed changes in

cellular structure within a few hours postmortem. Liver

tissue has also been shown to increase in stiffness with

postmortem time1. However, such studies did not report

failure properties of liver tissue parenchyma. Other

studies have investigated the effects of various conditions

on the tensile failure properties of liver parenchyma. It

was found that freezing the tissue prior to testing resulted

in significantly lower strains2. Also, tensile strain rate

significantly affects the failure stress and strain3.

However, there have been no studies that have evaluated

the change in tensile failure properties of liver

parenchyma between 6 and 48 hours postmortem.

METHODOLOGY

Twelve bovine livers were acquired from a local

slaughterhouse immediately after death. Multiple samples

of the parenchyma were obtained from each liver for

testing at three time points. The three time points were 6

hours, 24 hours, and 48 hours postmortem.

A custom slicing jig and blade assembly was used to

obtain thin slices of parenchyma. The slices were then

stamped to create dog-bone shaped samples. Samples

were prepared and tested immediately after the liver

arrived at the laboratory to obtain data for the first time

point. Remaining liver tissue was divided into large

sections, immersed in preservation fluid, and sealed in

plastic containers until the later time points. Tissue from

six livers were stored in DMEM, while tissue from the

remaining six livers were stored in normal saline.

Uniaxial tension tests were conducted on the dog-bone

samples. A mounting and testing procedure was followed

to minimize variation in specimen alignment and initial

specimen slack. Optical markers were placed on the gage

region of the specimen. The testing system was operated

with a multi-axis controller that simultaneously moved

the top and bottom grips at a constant velocity. Specimens

were pulled to failure at a rate of 1s-1

. Data was collected

for the duration of the test from high-speed video, load

cells, potentiometers, and accelerometers. The optical

markers placed on the front of the sample were tracked

using a motion analysis software. The displacements of

the markers surrounding the failure tear were used to

calculate the Green strain. The 2nd

Piola Kirchhoff Stress

was calculated at each time point during the test. The

average failure stresses and strains were compared across

time points within each liver, and across all twelve livers.

RESULTS

A Block ANOVA was conducted to compare the failure

properties at each of the three time points. The failure

stresses and strains did not significantly change with

respect to time for livers that were preserved in DMEM.

Analysis is underway to determine if there are any

changes in failure properties for the livers stored in saline.

CONCLUSIONS

Uniaxial tension tests were conducted on the liver

parenchyma of twelve bovine livers. Neither the failure

stresses nor strains changed significantly between 6 and

48 hours postmortem for tissue stored in DMEM. Future

analysis will elucidate the effects of postmortem time on

the failure properties for tissue stored in saline.

REFERENCES [1] B. Tay, J. Kim, and M. Srinivasan, “In vivo mechanical behavior of intra-

abdominal organs,” IEEE Transactions on Biomedical Engineering, vol. 53,

no. 11, pp. 2129-2138, 2006.

[2] A.C. Santago, A.R. Kemper, C. McNally, J.L. Sparks, and S.M. Duma,

“Freezing affects the mechanical properties of bovine liver,” Biomedical

Sciences Instrumentation, vol. 45, pp.24-29, 2009.

[3] A.R. Kemper, A.C. Santago, J.D. Stitzel, J.L. Sparks, and S.M. Duma,

“Biomechanical response of human liver in tensile loading,” Ann. Adv.

Automot. Med., vol. 54, pp. 15-26, 2010.

Oral: Smithfield, 2:15 Bioelectrical Systems 10


EFFECTS OF EXTRACELLULAR SODIUM AND CALCIUM ON THE CONDUCTION VELOCITY –

EXTRACELLULAR POTASSIUM RELATIONSHIP IN GUINEA PIGS

Michael W. Entz II1,2

and Steven Poelzing, PhD1,2

1. Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University,

Blacksburg, VA

2. Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Roanoke, VA

Corresponding Author: Michael W. Entz II, Email: [email protected]

INTRODUCTION

Historic studies have shown that there is a biphasic

relationship between cardiac conduction velocity (CV)

and extracellular potassium concentration ([K+]o) known

as supernormal conduction1. However, we recently

demonstrated that increasing [K+]o in the range which was

previously shown to increase CV either does not change

CV or significantly decreases CV2. Our laboratory has

demonstrated a phenomenon known as ephaptic self-

attenuation3, which could explain these confounding

results. Therefore, this study sought to shed further light

onto the relationship between extracellular cationic

concentrations ([Na+]o and [Ca

2+]o) and ephaptic self-

attenuation mechanisms.

METHODOLOGY

[K

+]o was increased in steps between 4.56 and 10 mM in

Langendorff perfused guinea pig ventricles for four

combinations of [Na+]o and [Ca

2+]o (1.25 or 2.0 mM

[Ca2+

]o and 145.5 or 155.5 [Na+]o). Epicardial CV was

quantified by optical mapping. Perinexal width was

measured with transmission electron microscopy (TEM).

RESULTS

For all solution combinations, the biphasic nature between

CV and [K+]o was reproduced as previously reported

1.

Interestingly, when comparing the changes in CV

between two [K+]o, it was found that increasing [Ca

2+]o

from 1.25 to 2.0 mM in solutions with 155 mM [Na+]o

decreased the slope of the CV-[K+]o curve (Figure 1A).

TEM revealed that [Ca2+

]o may decrease perinexal width,

which could explain the decreased CV sensitivity to [K+]o.

However, when [Na+]o was decreased to 145 mM, it was

found that [Ca2+

]o no longer had a significant effect on

ΔCV (Figure 1B). Decreasing [Na+]o increases ephaptic

self-attenuation by reducing sodium driving force.

Therefore, decreasing perinexal width with elevated

[Ca2+

]o should maintain enhanced CV sensitivity to [K+]o

under conditions of reduced [Na+]o. Interestingly, this data

would suggest that changing [Na+]o by 10 mM plays a

larger role in determining the sensitivity of the CV-[K+]o

relationship than changing [Ca2+

]o by 0.75 mM.

Figure 1: [Ca

2+]o decreases CV sensitivity to [K

+]o with

155.5 mM [Na+]o. Effects of [Ca

2+]o and [Na

+]o on CV

differences between [K+]o. (A) Increasing [Ca

2+]o at 155

mM [Na+]o significantly reduces ΔCVT due to [K+]o. (B)

Increasing [Ca2+

]o with 145 mM [Na+]o shows no change

in ΔCVT due to [K+]o. *, p<0.0167 between [Ca

2+]o,

Bonferroni corrected for multiple comparisons.

CONCLUSIONS

Increased ephaptic coupling via elevated [Na+]o and

[Ca2+

]o can decrease CV sensitivity to [K+]o. However,

reducing [Na+]o reduces the modulatory effects of [Ca

2+]o

on the CV-[K+]o relationship. These data suggest that

preserving ephaptic mechanisms prevents alterations in

CV secondary to altered plasma potassium.

ACKNOWLEDGMENTS

This work was supported in part by a grant from the

National Institutes of Health (R01 HL102298 to SP).

REFERENCES

1. Buchanan et al. Circ Res 1985.

2. Entz II et al. Front Physiol 2016.

3. George et al. AM J Physiol Heart Circ Physiol

11 Developing Novel Medical Devices Oral: Smithfield, 1:00


ASSESSING AND OPTIMIZING SMART TEXTILE SYSTEMS FOR HUMAN ACTIVITY MONITORING

M.I. Mokhlespour Esfahani1, Maury Nussbaum

1

1. Virginia Tech, Department of Industrial and Systems Engineering

Corresponding Author: Maury Nussbaum, Email: [email protected]

INTRODUCTION

Physical activity (PA) – human movement generated by the

musculoskeletal system – is strongly associated with

several adverse health outcomes. For example, a physically

inactive lifestyle may contribute to musculoskeletal,

cardiovascular, neurological, and mental disorders. It has

also been reported in the U.S. that the annual cost of

physical inactivity was ~$117 billion between 2006 and

2011 [1]. For purposes of controlling the risk of these

disorders and associated costs, a physically active lifestyle

is one of the most important current goals for health

promotion. To achieve this goal, a critical requirement is to

identify an individual’s amount and level of physical

inactivity during a day. For this purpose, it is necessary to

determine the dimensions of physical activity (e.g., type

and duration). For this, activity monitoring represents an

increasingly effective way for determining the dimensions

of PA during any given day. Therefore, many academic-

and commercially-driven efforts are seeking to develop an

accurate and reliable activity monitor that has applications

to diverse activity domains (i.e., occupational, domestic,

transportation, and leisure time).

METHODOLOGY

A recent and promising wearable technology is being used

increasingly by PA researchers— namely, the use of

interactive or “smart” textiles that have sensing material

incorporated in them. So-called smart textile systems

(STSs) are becoming an increasingly important technology

for a range of fields such as healthcare, the military, public

safety, the consumer fitness realm, gaming/sports, and

aerospace/space exploration. Thus, STS has clear potential

utility for measuring health-relevant aspects of human

activity, in diverse environments. Despite this, however,

limited evidence exists to support the implementation of

STSs during diverse applications. Our objective is to

investigate the accuracy of an STS in three representative

applications: daily life, healthcare, and occupational

scenarios. A particular STS will be examined, consisting of

a commercially-available system (i.e., “smart” socks),

which is based on textile pressure sensors, and a custom

smart shirt, using our textile strain sensors (as in Figure 1).

We will also explore the relative merits of these two

approaches, separately and in combination.

RESULTS

We have recently developed several textile strain sensors

that are called body worn sensors (BWSs). BWSs

measure the strain in a textile using resistance changes

when elongated. Working as a potentiometer, the

resistance range is between 2kΩ and 70kΩ, which linearly

corresponds to zero tension and 50% maximum

elongation, respectively. The size of the BWS to be used

here is 20×40 mm, and its performance is not affected by

humidity [2]. Specific details about manufacturing a body

worn sensor can be obtained from our recent study [2].

Since a BWS is designed to measure strain in textiles, it

connects to an electronic board through wires and

connections. One sensor is illustrated in Figure 1.

Figure 1: One body worn sensor

CONCLUSIONS

The results of this investigation are expected to

demonstrate the potential performance of an STS for

activity monitoring in three broad domains: activities of

daily life, healthcare, and occupational scenarios. We

also expect to identify specific combinations or

configurations of STSs that could provide the most useful

and efficient information for activity recognition and

detection.

REFERENCES

[1] Carlson, S.A., et al., Inadequate physical activity and

health care expenditures in the United States. Progress in

cardiovascular diseases, 2015. 57(4): p. 315-323.

[2] Mokhlespour Esfahani, M.I., et al., Novel printed

body worn sensor for measuring the human movement

orientation. Sensor Review, 2016. 36(3): p. 321-331.

Oral: Duckpond, 1:00 Lower Extremity Biomechanics 12


RECOVERY OF BALANCE IN TOTAL ANKLE REPLACEMENT PATIENTS ACROSS TIME

Jonathan R. Gladish1, Robin M. Queen

1

1. Kevin P. Granata Biomechanics Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech

Corresponding Author: Jonathan R. Gladish, Email: [email protected]

INTRODUCTION

Ankle arthritis is a debilitating condition that affects about

1% of the world population, with around 50,000 new

cases reported each year [1]. The effects on mental health

due to end-stage ankle arthritis have been compared to

those associated with other chronic diseases such as

congestive heart failure, end-stage hip arthritis, and

kidney disease [2]. One promising surgical solution for

this disease is total ankle replacement.

While many studies have investigated improvements in gait

following total ankle replacement [3], few have studied

balance recovery, which impact fall risk [4]. Therefore, the

purpose of this study was to analyze the balance

performance, as measured by center of pressure (COP)

excursion over a period of two years after total ankle

replacement surgery. It was hypothesized that excursion in

the surgical limb would decrease as patients recovered.

METHODOLOGY

A total of 410 subjects (178 left and 232 right ankles)

diagnosed with end-stage ankle OA and scheduled for a

total ankle replacement within two weeks of testing.

Subjects were instructed to stand with one foot on each

force platform for 10 seconds with their feet together, and

shoulder-width apart. Two force platforms (AMTI,

Watertown, MA) collecting at 1200 Hz. were used to

collect data. The force data was used to calculate center of

pressure and related measures as described by Prieto et.

al. [5]. The data was compared across the three time

points using a mixed effects, maximum likelihood

estimation model with time and the square of time as

independent variables. Significance was set at p < 0.05 for

all tests, and all statistical analysis was performed using

STATA (StataCorp LLC, College Station, TX).

RESULTS

Figure 1 shows the bidirectional COP excursion for each

condition by limb over the two-year testing period. In the

FT condition, the results show a significant linear

downward slope in the AP direction of the surgical limb

(pTime = 0.005), a significant linear downward slope in

the ML direction of the surgical limb (pTime = 0.047),

and a significant linear/quadratic upward slope in the ML

direction of the non-surgical limb (pTime < 0.001, pTime2

= 0.006). The results partially support the hypothesis of

decreasing excursion in the surgical limb.

Figure 1: AP and ML Center of Pressure excursions

(with regression) for surgical and non-surgical limbs in

Feet Together and Shoulder Width conditions

CONCLUSIONS

The lack of significant results in the SW condition may

indicate that it is not a sufficiently challenging task to

detect static balance differences. The decreasing surgical

excursions converging with increasing non-surgical

excursions suggest that total ankle replacement improves

static balance performance and restores some symmetry.

However, it has been suggested that center of mass

measures would be a more accurate estimation of balance

performance and center of pressure is a better indicator of

balance strategy [6]. Therefore, future work should be

conducted to investigate this claim and evaluate total

ankle replacement patients in dynamic balance tasks.

REFERENCES

[1] Hintermann et. al. Am J Sports Med. 2002

[2] Glazebrook, et. al. J Bone Jt. Surg. 2008

[3] Queen, et. al. Clin Biomech. 2014

[4] Lord, et. al. J am Geriatr. 1991.

[5] Prieto, et. al. IEEE Trans. Biomd. Eng. 1996

[6] Gladish, et. al. Unpublished Manuscript. 2017



MODELING THROMBUS FORMATION AND GROWTH IN STENOTIC FLOW

Hamid Hosseinzadegan1, Danesh K. Tafti

1

1. Mechanical Engineering Department, Virginia Polytechnic Institute and State University

Corresponding Author: Hamid Hosseinzadegan, Email: [email protected]

INTRODUCTION

This study analyzes platelet deposition in stenosed

damaged vessels, with mild to severe stenosis (29-80%),

within a wide range of pathological shear rates ( 100

sec-1

). Previous numerical models need to be recalibrated

every time they are applied to a new experimental setup

with different flow conditions. In the current study a high-

fidelity general function is presented and validated for

platelet adhesion rate as a function of stenosis severity

and local Reynolds number at the stenosis apex.

METHODOLOGY

In our quest to maintain as much realism in our system as

possible, we choose a continuum approach and following

Sorensen’s approach (2), solve the mass conservation,

Navier Stokes, and mass transport equations. The

GenIDLEST numerical code is used to solve the

governing equations.

In order to have a physically relevant representation of the

complex interactions, all seven mass transport equations

introduced by Sorensen et al. (2) are included in the

present model: 1) resting platelets (RP), 2) activated

platelets (AP), 3) ADP, 4)TxA2, 5) prothrombin (PT), 6)

thrombin (T), 7) antithrombin (ATIII). For all of them the

mass transport equation is solved: 𝜕𝐶𝑖

𝜕𝑡+ 𝑑𝑖𝑣(𝑢. 𝐶𝑖) = 𝑑𝑖𝑣(𝐷𝑖 . 𝑔𝑟𝑎𝑑(𝐶𝑖)) + 𝑆𝑖 (1) 𝑖 = 1,2, … ,7 (3)

where 𝐶𝑖 is the concentration of species 𝑖, 𝐷𝑖 is the mass

diffusivity of species 𝑖, and 𝑆𝑖 is the

generation/consumption term for species 𝑖 to model

platelet-platelet, platelet-agonist, and agonist-agonist

interactions in the lumen area.

RESULTS

Figures 1 a-c show the predicted results using the current

model versus experimental SEM images for four

instances. All predicted occlusion times using our model

are within the confidence limit of experiments, whereas

results predicted using models of Mehrabadi et al. and

Bark et al. do not fall in the experimental uncertainty

range for cases with peak wall shear rates of 3800 sec-1

and 16000 sec-1

( Fig. 1d).

Figure 1: a-c) Comparison of predicted axial distribution

of platelet deposition with experimental measurements of

(1). d) Predicted occlusion times by present model

compared to predictions of Mehrabadi and Bark as well as

experimental data (1). Experimental images are reprinted

from (1) with permission from Springer.

CONCLUSIONS

Using the general functions for shear enhancement factor

𝜆 and reaction rate constant 𝑘𝑖0 , an excellent agreement

was achieved. These functions were obtained by

calibration of the model based on experimental data. Our

results reveal that the platelet adhesion is a function of

stenosis severity and Reynolds number at the stenosis

apex and cannot be defined solely by shear rate values at

the vessel wall.

ACKNOWLEDGMENTS

The authors acknowledge the support provided by

National Science Foundation (grant CBET-1235790) and

the Advanced Research Computing at Virginia Tech.

REFERENCES

1. Casa LDC, Ku DN. Cardiovasc Eng Technol 5: 154–

163, 2014.

2. Sorensen EN, Burgreen GW, Wagner WR, Antaki JF.

Ann Biomed Eng 27: 436–448, 1999.



ENHANCING THE SELECTIVITY OF ELECTROPORATION THERAPY FOR GLIOBLASTOMA

Jill W. Ivey1, Eduardo L. Latouche1, Glenn J. Lesser2, Waldemar Debinski2, Rafael V. Davalos1, Scott S. Verbridge1

1. Virginia Tech-Wake Forest University, Department of Biomedical Engineering and Mechanics 2. Wake Forest Baptist Medical Center, Comprehensive Cancer Center

Corresponding Author: Jill Ivey, Email: [email protected] INTRODUCTION Glioblastoma multiforme (GBM) is an aggressive brain cancer, with a grim prognosis. The nearly universal recurrence of GBM tumors is attributable to the failure of current therapies to selectively target malignant cells without destroying healthy brain tissue. We hypothesize that malignant GBM cells exhibit distinct physical characteristics that can provide targets for selective killing using irreversible electroporation (IRE). We have developed tunable 3D tissue models to study the correlation of cell responses to IRE to cell morphology. METHODOLOGY 3D collagen tissue mimics were created. Scaffolds were seeded with glioblastoma cells (U87, C6, DBTRG, U251), patient derived glioblastoma stem cells (GBM 10, VT061, VT064) or healthy brain cells (NHA, D1TNC1, PC12). Cells were treated with ephrinA1 (eA1) to induce a morphology change. Cells were exposed to 1µs pulse high-frequency irreversible electroporation (HFIRE) pulses. Live/dead staining and finite element modeling was used to determine lethal thresholds. The morphology of the cells are analyzed by confocal microscopy. RESULTS

Figure 1. HFIRE threshold correlation with nuclear area

HFIRE was shown to exhibit intracellular effects with nuclear size being a predictor of HFIRE lethal thresholds. Malignant cells exhibited increased nuclear area and lower HFIRE lethal thresholds compared to healthy cells

(Fig 1). This allows for a margin of selectively treating malignant cells while sparing healthy cells. The selectivity achieved by HFIRE can be enhanced by molecular targeted eA1 due to a morphology change that increases nuclear to cytoplasm ratio (NCR) for malignant cells but leaves healthy cells unchanged (Fig 2). Glioma stem cells (GSCs), often resistant to therapies, also exhibit lower HFIRE thresholds compared to healthy cells.

Figure 2. Margin of selectivity enhanced with ephrinA1

CONCLUSIONS The HFIRE killing mechanism is such that an increased NCR correlates with a lower electric field lethal threshold. This allows for the selective targeting of malignant cells using a range of electric field distributions that induce no damage to the healthy cells studied. This range for selective targeting can be enhanced using targeted eA1 therapy which preferentially changes the NCR of only cells expressing the EphA2 receptor, commonly overexpressed in malignant glioma cells. Additionally, GSCs, which are often resistant to other therapies, succumb to selective damage by HFIRE. The selectivity accomplished by HFIRE targeting may present therapeutic opportunities for treating GBM cells that escape current therapies and cause tumor recurrence. ACKNOWLEDGMENTS This work was supported by an R21 and R01 Award from the NCI and funding from ICTAS at Virginia Tech. REFERENCES Davalos RV. Ann Biomed Eng. 2005; 33(2):223-31.

15 The Tumor & Tissue Microenvironment Oral: Drillfield, 9:45


CRANIOFACIAL BONE REGENERATION GUIDED BY 3D PRINTED ARCHITECTURE

Carlos V. Kengla1,2

, Anthony Atala1,2

, James J. Yoo1,2


1. Wake Forest University, Institute for Regenerative Medicine | School of Biomed. Eng. and Sciences

2. Virginia Polytechnic Institute and State University, School of Biomedical Engineering and Sciences

Corresponding Author: Carlos V. Kengla, Email: [email protected]

INTRODUCTION

Guided bone regeneration (GBR) as a strategy utilizes a

membrane to resist soft tissue ingrowth while localizing

material placed in the site to promote bone growth. In this

study, we tested the GBR effect in a mandibular bone

defect of rabbits with a 3D bioprinted, biomimetic

architecture paired with an internal architecture designed

to facilitate bone ingrowth. Bone grafts were made of a

composite of poly(ε-caprolactone) and β-tricalcium

phosphate (PCL/TCP) and fabricated on the integrated

tissue and organ printing (ITOP) system.1 We examined

bone regeneration in a critically sized defect at 4 and 12

weeks with a dual architecture bone scaffold and inhibited

bone regeneration in a defect treated with a scaffold

without the soft tissue resistant architecture.

METHODOLOGY

Scaffolding bio-ink was produced by mixing

polycaprolactone (PCL) (43-50kDa, Polysciences, USA)

and tricalcium phosphate nano-powder (Berkeley

Advanced Biomaterials, USA) at a 1:1 weight ratio.

Scaffold specimen were printed on the Integrated

Tissue/Organ Printer (ITOP) platform. Amniotic fluid

derived stem (AFS) cells were used for differentiation

studies. An Instron universal testing system was used for

mechanical analysis. NaOH (Sigma, USA) was used for

accelerated degradation. New Zealand white rabbits were

used for a mandibular defect surgical model.

RESULTS

In vitro experiments demonstrated the increased

osteogenic potential of the 1:1 PCL/TCP composite by

showing higher ALP activity and higher calcium mineral

deposition in differentiating AFS cells.

Figure 1: Critical zone defect shows increased new bone

formation.

The results showed increased new bone formation and

maturation with time in a critically sized defect (Figure

1). The Core-Only graft was a homogeneous architecture

while the Core/Shell graft had a bilayer design with a

dense shell to resist soft tissue ingrowth. New bone as

able to grow into the Core/Shell graft which employed

GBR principles.

CONCLUSIONS

We demonstrated that the printed bone grafts were able to

guide stem cells towards bone lineage in vitro and guide

bone regeneration into maturing bone in vivo.

ACKNOWLEDGMENTS

We would like to acknowledge AFIRM II for supporting

this work (W81XWH-08-2-0032).

REFERENCES

1. Kang, H.-W. et al. A 3D bioprinting system to produce

human-scale tissue constructs with structural integrity.

Nat. Biotechnol. 34, 312–319 (2016).



INTERSTITIAL CELLS OF CAJAL INCREASE NEURAL-MEDIATED RELAXATION

AND ELECTRICAL RHYTHM IN AN IN VITRO BIOENGINNERED MODEL OF PYLORUS

Dylan T. Knutson1, 2, Elie Zakhem1, Kenneth L. Koch3, Khalil N. Bitar1, 2, 3

1Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, NC 2Viriginia Tech – Wake Forest University School of Biomedical Engineering, Winston Salem, NC

3Section on Gastroenterology Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, NC Corresponding Author: Dylan T. Knutson, Email: [email protected]

INTRODUCTION Motility in the gut is coordinated by the neuromuscular apparatus, a complex of smooth muscle, enteric neurons and interstitial cells of Cajal (ICC). Gastrointestinal neuromuscular disorders are associated with the depletion of neurons and ICC. In vitro models to study the effect of depletion or restoration of these key cells on neuromuscular function are lacking. The aim of this study was to produce different combinations of neuromuscular cells to measure physiological function of these combinations. METHODOLOGY Smooth muscle cells (SMC) were isolated from human pylorus, ICCs were isolated from GFP-mice small intestines, and neural progenitor cells (NPC) were isolated from rat small intestine. Pyloric constructs were engineered using the following combinations: (1) SMC, (2) SMC+ICC, (3) SMC+NPC and (4) SMC+ICC+NPC. Tissues were characterized by immunohistochemistry and physiological functionality using force and electrical measurements. RESULTS 1. Isolated ICC exhibited normal morphology and stained positive for Ano1. 2. Microscopy of tissues revealed GFP-positive ICC in respective constructs. 3. Organ bath studies were conducted on the engineered neuro-muscular tissues: (i) Basal tone, and subsequent contraction induced by potassium chloride was similar in rate, peak, and magnitude (area) among all tissues (367.5 µN and 348.4 µN peak on average, p>.05, n=4 per group). (ii) Electrical field stimulation (EFS) induced relaxation only in the muscular tissues that contained NPC (-230 ± 32.97 µN. p<.05, n=10). (iii) Relaxation from EFS was blocked by inhibitors Tetrodotoxin and Lω-Nitro Arginine, confirming dependence on a functional nNOS neuron

population to relax muscle. (v) Peak neural-mediated relaxation was amplified significantly in the presence of ICC (SMC+NPC+ICC, 1.9x, p<.05, n=5); both the onset and magnitude of relaxation was increased over the same time as the SMC+NPC tissues (2.4x and 1.7x, n=5) 4. Electrical activity of the different bioengineered tissues was simultaneously measured: electrical peaks correlated with simultaneous increases in force. Tissues containing ICC had higher frequency (6.0 ± .34 cpm) and amplitude (1029 ± 65 µV) compared to tissues without ICCs (frequency 2.0 ± .34 Cpm and amplitude 425 ± 8.3 µV, p<.05, n=2). CONCLUSIONS This study demonstrated the first simultaneous measurement of both force and electrical activity in an engineered neuromuscular apparatus. Three key cell types contributed to physiological changes- 1) Smooth muscle cells were the only cells necessary to develop tone. 2) nNOS neurons were responsible for initiating relaxation, and 3) ICCs increased electrical activity to basal tone and amplified neural-mediated smooth muscle relaxation. . The ability to quantitatively deplete and reinstate key cell populations related to gastrointestinal motility provides a novel model to investigate normal neuromuscular function, dysfunction of neuromuscular activity, and repair of function using specific bioengineered cells.. ACKNOWLEDGMENTS This study was aided by Wake Forest Institutional funds.

17 Lower Extremity Biomechanics Oral: Duckpond, 1:30


EFFECTS OF ACHILLES TENDON TAPING ON JOINT ENERGETICS IN JUMPING AND LANDING

Evan P. McConnell1, Philip Hernandez1, and Robin M. Queen1

1. Virginia Tech, Department of Biomedical Engineering and Mechanics Corresponding Author: Evan McConnell, Email: [email protected]

INTRODUCTION Taping of the Achilles tendon is used by athletes to manage pain during recovery. Previous work has shown differences in ankle work but no differences in force production with various ankle taping techniques during athletic tasks.1 METHODOLOGY 29 subjects - 16 males (20.9 ± 2.4 years, 1.79 ± 0.06 m, 79.0 ± 11.9 kg) and 13 females (21.4 ± 3.2 years, 1.66 ± 0.06 m, 66.1 ± 7.6 kg) - participated in the study. Retroreflective markers were placed at specific landmarks

on each subject to measure three-dimensional kinematics (Figure 1). Each subject’s dominant limb underwent an Achilles tendon assistive taping procedure by a certified athletic trainer. Subjects performed 5 trials of a stop jump task in both a taped and non-taped condition. The taping condition was randomized among all subjects. The first landing and subsequent jump were analyzed with a 10-camera motion analysis

system (240Hz). Joint power was determined based on data from 2 embedded force plates (1920 Hz) using inverse dynamics and was

integrated to yield joint work. 2x2 ANOVAs were performed (p<0.05) to determine gender and taping condition effects on peak power generation, power absorption, and work at each joint during landing and jumping. RESULTS Subject height (p<0.001) and mass (p=0.002) differed based on gender, but age (p=0.633) did not. No significant interactions and no taping condition main effects existed for power or work during either jumping or landing. A main effect of gender was identified, with females

showing decreased peak power generation at each joint during jumping (Table 1).

Table 1: Peak Power Generation

Females Males Gender Effect Non-

Taped Taped Non-Taped Taped

Ank

le La

nd

-12.3 -12.3 -13.0 -11.6 p=0.863

Jum

p 15.6 13.4 18.1 15.9 p=0.042

Kne

e Land

-17.3 -18.6 -21.0 -20.0 p=0.077

Jum

p

11.2 11.5 15.2 14.7 p<0.001

Hip

Land

-7.6 -6.1 -13.3 -14.9 p=0.040

Jum

p

6.3 4.6 10.2 9.6 p=0.009

CONCLUSIONS The assistive taping does not alter peak power generation, power absorption or joint work during landing and jumping in healthy subjects, but gender-specific differences in power generation do exist. Future work is needed to determine the effect of this taping technique in injured athletes. ACKNOWLEDGMENTS Jonathan Gladish, Sean Wilkins, and Nicole Orndorff assisted with data collection for this study. REFERENCES 1. Gehlsen, Gale M., et. al. Journal of Athletic Training 26.1 (1991): 62-65.

Figure 1: Subject preparation

Oral: Smithfield, 1:15 Developing Novel Medical Devices 18


USING FMRI DYNAMIC NETWORKS IN A HYPERGRAPH LEARNING MODEL FOR PREDICTING THE

SUCCESS OF LIFESTYLE WEIGHT LOSS INTERVENTIONS IN OBESE OLDER ADULTS

Fatemeh Mokhtari1,2

, Jonathan H. Burdette1, Anthony P. Marsh

1, W. Jack Rejeski

1, Paul J. Laurienti

1,2

1. Laboratory for Complex Brain Networks, Department of Radiology, Wake Forest School of Medicine,

2. Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences

Winston Salem, NC, USA

INTRODUCTION

Obesity and its adverse health effects is highly prevalent

even among older adults (65+ years), and is uniquely

problematic in this age group, as it is associated with

declines in physical functioning, the main predictor of

disability and loss of independence with aging (1).

The majority of people who follow behavioral treatments

fail to accomplish the pre-established goals. Hence, great

attention has now focused on finding biomarkers to predict

long-term treatment efficiency. In the present study, we

hypothesized that functional magnetic resonance imaging

(fMRI) dynamic networks, as a biomarker, would identify

those overweight and obese older adults who would lose

the largest percentage of body weight in a behaviorally-

based weight loss intervention.

METHODOLOGY

Fifty two obese/overweight older adults participated in a

baseline MR imaging session. Following the completion

of an 18-month lifestyle weight loss intervention, their

weight loss percent was evaluated. A median split of

weight loss (%) was used for identifying participants who

were in the top and bottom halves of percent weight loss,

based on the baseline body weight.

The dynamic functional brain networks were generated

using sliding window correlation technique. The

magnitude of correlations was thresholded to generate

sparse networks with the strong connections retained. The

dimensionality of the networks was reduced using higher-

order singular value decomposition (HOSVD). The

resulting networks were used in a hypergraph learning

model, a multivariate prediction technique (2). Random

subsampling cross validation with 100 permutations was

run to obtain an estimation of average accuracy, with 42

samples in the training and 10 samples in the test subsets.

RESULTS

As evident by Figure 1, prediction performance measures

(mean ± standard deviation) including accuracy,

sensitivity, and specificity were consistently significantly

high (above 0.9) for different sliding window lengths

(range: [61TR, 101TR], with increments of 10TR, where

TR=2s), and different connection density thresholding

values (range: [10%, 30%] with increments of 5%).

Accuracy Sensitivity Specificity

61 71 81 91 101 Total

80

100

80

100

80

100

80

100

61 71 81 91 101 Total

80

100

10

%

Window Size (TR)

15

%2

0%

25

%

30

%

61 71 81 91 101 Total

80

100

80

100

80

100

80

100

61 71 81 91 101 Total

80

100

10

%

Window Size (TR)

15

%2

0%

25

%

30

%

61 71 81 91 101 Total

80

100

80

100

80

100

80

100

61 71 81 91 101 Total

80

100

10

%

Window Size (TR)

15

%2

0%

25

%

30

%

Figure 1: Prediction performance measures

The two brain network components accounting for the

greatest amount of data variability are shown in Figure 2.

Figure 2: (1) high order motor

planning network, 2)

parietoinsular

network. These networks are

involved in

behavioral planning and

executive

functioning.

CONCLUSIONS

The outcomes of this study suggest that functional brain

phenotypes may be useful for tailoring weight loss

treatment to the individual level. Our approach provides

critical groundwork for the growing initiative of

personalized medicine. It will be vital for this work to be

followed by future studies involving larger sample sizes

for different genders and behavioral treatment regimens.

REFERENCES

1. Flegal, K.M. et al. 1999-2010. Jama-Journal of the American Medical Association.

2. Nie, F. et al. 2014. Proceedings of the 20th ACM SIGKDD

international conference on Knowledge discovery and data mining.

19 Developing Novel Medical Devices Oral: Smithfield, 1:45


ADVANCED STATISTICAL PROCESS CONTROL TECHNIQUES FOR ANALYSIS OF MEDICAL LINEAR

ACCELERATOR PERFORMANCE

Callistus M. Nguyen1,2

, Alan H. Baydush1, Charles M. Able

3, and Michael T. Munley

1,2

1. Radiation Oncology (Wake Forest School of Medicine, Radiation Oncology)

2. Virginia Tech – Wake Forest School of Biomedical Engineering and Sciences, Biomedical Engineering

3. Radiation Oncology (Florida Cancer Specialists, Radiation Oncology)

Corresponding Author: Callistus M. Nguyen, Email: [email protected]

INTRODUCTION

The focus of this work is to determine the utility and

effectiveness of SPC techniques in order to predict

machine dysfunction. It will also assess the most effective

data set to use SPC techniques that accurately reflects the

behavior of the process. Specific research objectives are

as follows: (1) Evaluate new SPC techniques for

analyzing accelerator system operating parameters and/or

performance; (2) Determine the effectiveness of

Exponentially Weighted Moving Average (EWMA) and

Cumulative Sum (CUSUM) SPC techniques in the

detection of performance dysfunction; (3) Assess and

validate the quality of digital data being produced by

linear accelerators against those produced by quality

assurance instrumentation.

METHODOLOGY

Seven linear accelerators were monitored by delivering

daily robust quality assurance (QA) treatments. Each QA

treatment generated trajectory and text log files that were

used to monitor various operational components and

subsystem performance. Given the large number of

parameters contained within these log files, the focus of

the project was to monitor performance parameters that

were considered to be clinically relevant in radiation

oncology. EWMA and CUSUM control charts were

constructed to analyze those parameters; evaluation

guidelines were also established to detect performance

dysfunction. Each SPC technique was then compared

using statistical analytics to quantitatively determine their

uniqueness and effectiveness. The quality of the digital

data was compared to determine which data set accurately

represents the performance of a linac during clinical

operation.

RESULTS

Advanced SPC techniques showed their effectiveness in

detecting erratic behavior in linac behavior. EWMA and

CUSUM techniques are responsive to small and subtle

shifts; thus, they are more efficient at tracking changes

when processes do not drift rapidly over time. The

incorporation of quantitative metrics supplemented SPC

techniques as indicators to adjust control limits when the

process is trending upwards or downwards. Although

PdM analytics had utility in predicting and preventing

component failure, traditional SPC techniques were not as

effective. Given the power of advanced SPC techniques,

they can become new tools in overall predictive

maintenance of linacs.

CONCLUSIONS

SPC techniques have unique characteristics that separate

them from each other. Each characteristic is specific to

that technique but ultimately they all have one objective:

determine the variation existing within the process.

Depending upon the level of sensitivity, each technique is

then categorized even further, forcing the user to choose a

technique that is most relevant to the level of detection.

There is no generally accepted definition of which type of

SPC technique is most efficient in detecting changes. In

order to quantitatively assess performance, each SPC

technique was subjected to a custom performance analysis

test consisting of three tests: a tabular analysis, an

operating characteristic curve analysis, and Average Run

Length (ARL) analysis (Figure 1). This test was also used

to verify if there were differences between each technique

in detecting changes. In sum, SPC was reliable in

predicting component failure and an effective method in

monitoring and characterizing process performance.

Figure 1: ARL analysis of SPC techniques.

Oral: Smithfield, 1:30 Developing Novel Medical Devices 20


DEVELOPMENT AND VALIDATION OF A BRAIN PHANTOM FOR THERAPEUTIC COOLING DEVICES

Ryan D.M. Packett1, Philip J. Brown1, Gautam S. Popli1, and F. Scott Gayzik2

1. Wake Forest University, Department of Biomedical Engineering 2. Wake Forest Baptist Medical Center, Department of Neurology Corresponding Author: F. Scott Gayzik, [email protected]

INTRODUCTION Tissue cooling has been proven as a viable therapy for multiple conditions and injuries, and has been applied to the brain to treat epilepsy and concussions, leading to improved long-term outcomes [1,2]. To facilitate the study of temperature reduction as a function of various cooling methods, a thermal brain phantom was developed and analyzed. METHODOLOGY The phantom is composed of a granular hydrogel through which is circulated 37 degree water, representing blood perfusion. The phantom was tested in a series of cooling trials using a fluid-cooled cooling block during which the perfusion rate was varied across a volume-scaled physiologic range. Results were compared against a validated finite difference (FD) model. The model was then used to calculate steady state cooling at a depth of 5 mm for all flow rates, for both the phantom and a model of the brain. This effort was undertaken to 1. validate the FD model against the phantom results and 2. evaluate how similar the thermal response of the phantom is to that of a perfused brain. RESULTS

Figure 1: Internal phantom temperature versus perfusion

rate, comparison of experimental and mathematical results

The FD phantom model showed good agreement with the empirical phantom results. Furthermore, the empirical phantom agreed with the predicted brain response within 3.5% at physiological flow, suggesting a biofidelic thermal response. CONCLUSIONS We presented a thermal phantom of the human brain, its design and construction and demonstrated flow-mediated sensitivity in the steady state temperature at a depth of 5 mm. Comparison of experimental steady temperatures with a previously-validated finite difference solver yielded good agreement, including an average deviation of 2.0% across experimental perfusion rates between the phantom and the FD model of the phantom experiment, while the phantom-to-FD brain model comparison showed an average deviation of -3.5% for the same measure. The brain phantom presented provides a tunable physical analog that reasonably predicts the temperature drop of perfused brain parenchyma during a surface-based, fluid-driven cooling application, and will be used as a platform for future studies of thermally-mediated therapies applied to the cerebral cortex. ACKNOWLEDGMENTS Pilot funding was provided by Wake Forest Innovations and the Wake Forest Alumni Association. Summer internship support (Megan Fritz) was provided by Wake Forest School of Medicine and by the National Science Foundation (REU Site: Imaging and Mechanics-based Projects on Accidental Cases of Trauma Impact, Award No. 1559700). REFERENCES [1] Nolan, J.P., et al, “Therapeutic hypothermia after cardiac arrest…” Circulation, 2003. 108(1): p. 118-21. [2] Karnatovskaia, L.V. et al, “Therapeutic hypothermia for neuroprotection…” Neurohospitalist, 2014. 4(3): p. 153-63.

21 Crash Injury & Prevention Oral: Duckpond, 2:15


INVESTIGATION OF THORACOLUMBAR FRACTURES IN MOTORSPORT DRIVERS DURING FRONTAL IMPACTS

John Patalak1,2, Joel D. Stitzel1,2

1. Wake Forest School of Medicine, Department of Biomedical Engineering, 2. Wake Forest University Center for Injury Biomechanics

Corresponding Author: John Patalak, Email: [email protected] INTRODUCTION Following a frontal on-track incident in 2015 a NASCAR® (National Association for Stock Car Auto Racing, Inc) driver was diagnosed with L1 and L2 superior endplate vertebral body wedge compression fractures without neurologic symptoms. The driver received medical clearance to return to racing activities approximately seven weeks following the incident. The 21-year-old, 69 inch, 168-pound driver was utilizing a helmet, HANS® head & neck restraint, nine-point seat belt restraint system and full containment seat. The details of this restraint system have been described in other publications. Each NASCAR vehicle is equipped with an onboard incident data recorder (IDR) which records tri-axial vehicle acceleration from the left mid frame rail. A post impact vehicle and equipment inspection did not identify any equipment or system abnormalities which could be attributed to the driver’s injuries. Investigation focus was shifted to the seat pan geometry and the driver’s abdominopelvic orientation in the seat. METHODOLOGY Empirical sled testing was conducted to provide validation data for a numeral model of a motorsport restraint system. A material model for the seat insert energy absorbing foam was developed via dynamic drop and quasi-static compression testing. The material model was validated by repeating the drop testing numerically with LS-DYNA. Upright magnetic resonance imaging (MRI) of the driver was conducted in the race seated position to quantify the location of the spine relative to the seat insert, as shown in Figure one. A numerical 50th percentile male anthropomorphic test devices (ATD) was used in numerical sled test simulations for comparison to the empirical sled test. A Sprague and Geers error analysis will provide an

objective evaluation of the validity of the numerical motorsport restraint system model. In phase II of this investigation the Toyota Total Human Model for Safety (THUMS) human body model (HBM) will be placed in the validated motorsport restraint model. Independent simulation variables will include the fore-aft pelvis orientation in the seat, the seat pan ramp angle, the pretension of the seat belt restraint system, and the crash pulse severity and direction. Dependent variables will include cross-sectional thoracic and lumbar vertebral body forces and moments, thoracic and lumbar vertebral body strains, chest displacement and head acceleration. RESULTS A numerical model of a motorsport restraint system has been developed and ATD validation simulations are underway. Quantification of driver spine location relative to the seat insert has been completed.

Figure 1. Upright MRI of driver in race seating posture

CONCLUSIONS This research is ongoing with completion of phase II expected by the summer of 2017. ACKNOWLEDGMENTS Dr. Joel Stitzel, Dr. Matthew Davis, Derek Jones, James Gaewsky, Jeff Suhey, Matthew Harper and Curt Cloutier for their help and contributions to this research.

Oral: Smithfield, 10:15 Biomaterials Development & Characterization 22


POLY(ETHER ESTER) IONOMERS AS WATER-SOLUBLE POLYMERS FOR MATERIAL EXTRUSION

ADDITIVE MANUFACTURING PROCESSES

Allison M. Pekkanen1, Callie Zawaski

2, Andre T. Stevenson Jr

3, Ross Dickerman

4, Abby R. Whittington

1,3,4, Christopher B.

Williams2,5

, and Timothy E. Long

Macromolecules Innovation Institute, Department of Chemistry, Virginia Tech, Blacksburg, VA

1. Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA

2. Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA

3. Materials Science and Engineering, Virginia Tech, Blacksburg, VA

4. Department of Chemical Engineering, Virginia Tech, Blacksburg, VA

Corresponding Author: Allison M. Pekkanen, Email: [email protected]

INTRODUCTION

Additive manufacturing (AM) provides customized

products with well-defined features unattainable with

traditional manufacturing techniques. Material extrusion

AM revolves around the selective deposition of molten

polymer through a nozzle. Commonly, acrylonitrile-

butadiene-styrene copolymers dominate this form of AM

but require high processing temperatures. Water-soluble

polymers for material extrusion AM suitable for biologic

incorporation remain unavailable. This work details the

synthesis and characterization of poly(ether ester)

ionomers suitable for biologic incorporation with low

temperature material extrusion AM.

METHODOLOGY

Poly(ether ester) ionomers were synthesized by melt

polymerization of poly(ethylene glycol) (PEG, 8,000

g/mol) and sulfonated isophthalate (SIP) catalyzed by 40

ppm titanium tetraisopropoxide (Scheme 1). Quantitative

ion exchanged was achieved through dialysis over 6 d.

Poly(PEG8k-co-CaSIP) filament was printed using a direct

drive system with a 0.4 mm diameter nozzle at 70 °C and

a glass bed heated to 40 °C.

RESULTS

Ion exchange imparts a large effect on the melt behavior

of poly(PEG8k-co-XSIP) ionomers, with divalent

counterions exhibiting physical crosslinking between

polymer chains and leading to an increase in melt

viscosity. The calcium ion in particular proved to yield

the highest melt viscosity. Interestingly, the

thermomechanical properties of these ionomers remain

unchanged below the melting temperature. This increase

in viscosity proved crucial in the realization of 3D parts,

especially at lower temperatures. Material extrusion AM

from filament provided well-defined parts (Figure 1).

Scheme 1. Melt transesterification of SIP and PEG8k to

yield poly(ether ester) ionomers.

Figure 1. Poly(PEG8k-co-CaSIP) exhibits printability,

affording well-defined structures. Scale bar = 1 mm.

CONCLUSIONS

Poly(ether ester) ionomers were developed to impart

water solubility to 3D parts created with low temperature

material extrusion AM. Printability at low temperatures

enables the incorporation of biologics, such as enzymes,

into the printing process for controlled release

applications.

REFERENCES

Pekkanen, A.M. et al. ACS Appl. Mat. Inter. 2017, DOI:

10.1021/acsami.7b01777



MOLECULAR ANALYSIS OF HYALURONIC ACID WITH SOLID-STATE NANOPORES

Felipe Rivas1, Osama Zahid1, Paul L. DeAngelis2, Aleksander Skardal1,3,4, Adam R. Hall1,3,4, Elaheh Rahbar1

1. Virginia-Tech Wake Forest School of Biomedical Engineering, Winston Salem, NC 2. Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK

3. Institute for Regenerative Medicine, Wake Forest University School of Medicine Winston Salem, NC 4. Comprehensive Cancer Center, Wake Forest University, School of Biomedical Medicine, Winston Salem, NC

Felipe, Rivas: [email protected]

INTRODUCTION Hyaluronic acid (HA; hyaluronan) has emerged as a powerful indicator for a range of diseases and physiological conditions, including cancer1, osteoarthritis2, and wound healing after injury2. Evidence has also shown that low molecular weight HA triggers pro-inflammatory responses whereas high molecular weight HA is anti-inflammatory2, suggesting the potential importance of HA size as an independent biomarker. However, current methods to quantitate HA size and concentration are costly, time consuming, and rarely distinguish HA by molecular weight. Thus, there is a need for improved HA detection and quantification methods. Herein, we propose a new method to differentiate varying molecular weights of HA based on their electrophoretic movement across a solid-state (SS-) nanopore. METHODOLOGY Using methods described by Yang, et. al3, a single nanopore (5-8 nm diameter) was fabricated on a 30-nm thick silicon nitride membrane supported by a 4.4 mm Si chip. The device was then used as a barrier between two electrically isolated reservoirs. An ionic solution (6M LiCl) was loaded onto both sides of the chip, with one chamber also containing HA. A voltage was applied across the device, generating an electric field gradient capable of translocating HA molecules electrophoretically through the pore. Molecular translocations caused temporary interruptions (“events”) in the trans-membrane ionic current that were measured by a patch-clamp amplifier and recorded using custom software. Event depth, duration, and rate were collected across a voltage range of 100-600 mV. Polydisperse HA was obtained from Sigma Aldrich; monodisperse HA ranging from 50-2,500kDa was provided by Hyalose, LLC. RESULTS Using polydisperse HA, we demonstrated SS-nanopore detection of HA for the first time, yielding a series of

easily resolved current blockades that each marked the passage of a single molecule. Events were observed only towards a positive bias, in agreement with the expected electrophoretic direction of anionic HA. Event rate was found to have a linear dependence on applied voltage, indicating diffusion-limited kinetics, and to vary directly with HA concentration. Subsequent measurements on purified, monodisperse HA yielded well-defined populations of event properties for HA samples 50-2500kDa in size. Specifically, the event charge deficit, (ecd), which is the integrated area of each measured event; was unique for each HA size. Importantly, ecd displayed a power-law dependence on HA molecular weight, showing that the SS-nanopore system can differentiate HA based on molecular weight.

CONCLUSIONS SS-nanopore detection was successfully used to distinguish between different molecular weights of HA based on ecd. The data from this study shows promise in using the SS-nanopore system as a potential quick analytical assay to quantitate HA size and concentration in the clinical setting. ACKNOWLEDGMENTS This project has been supported by Dr. Adam Hall’s and Dr. Elaheh Rahbar’s start-up funds. REFERENCES 1. Lokeshwar, V, B. The Journal of Biological Chemistry. 2001, 276, 11922–11932. 2. Necas, J. Veterinarni Medicina. 2008, 53, 397–411. 3. Yang, J., et al. Nanotechnology. 2011, 22, 285310.

Oral: Duckpond, 2:45 Crash Injury & Prevention 24


EVALUATING THE POTENTIAL OF AN INTERSECTION DRIVER ASSISTANCE SYSTEM TO PREVENT U.S.

INTERSECTION CRASHES

John M. Scanlon1 and H. Clay Gabler

1

1. Virginia Tech, SBES

Corresponding Author: John Scanlon, Email: [email protected]

INTRODUCTION

Intersection crashes account for over 5,000 fatalities each year in the U.S. [1]. Highly automated vehicles are rapidly emerging and aim to end all traffic fatalities. This work evaluated the capacity of intersection advanced driver assistance systems (I-ADAS) to prevent U.S. intersection crashes and mitigate associated injuries. I-ADAS is an emerging technology used by highly automated vehicles to help drivers safely navigate intersections. This technology utilizes onboard sensors, such as radar, to detect oncoming vehicles. If an imminent crash is detected, I-ADAS can respond by (a) warning the driver and/or (b) autonomously braking. Preventing and/or mitigating crashes and injuries that occur in intersection crashes are among the highest priority for designers, evaluators, and regulatory agencies.

METHODOLOGY

The strategy for this research was to examine real-world intersection crashes as they actually occurred, and then consider a scenario where one of the vehicles had been equipped with I-ADAS. This was accomplished by first extracting 661 U.S. intersection crashes from a nationally-representative database [2]. Second, each crash was reconstructed from the intersection approach through impact using information collected by the crash investigator. The position of each vehicle as a function of time was reconstructed using information provided by the crash investigators and a series of driver models. Third, each scenario was simulated as if one of the involved vehicles had been equipped with an I-ADAS. Several variations of I-ADAS were evaluated. First, two I-ADAS countermeasures were considered: one that delivers a warning to the driver and one that uses AEB. Second, several critical time-to-collision (TTC) thresholds for activating I-ADAS were considered, including 1.0, 1.5, 2.0, 2.5, and 3.0 s values. If I-ADAS estimates a crash will occur within some TTC, the system activates.

RESULTS

Potential crash prevention estimates for all 10 variants of I-ADAS that were evaluated in this study can be found in

Figure 1. The model predicted that 31-47% of SCP crashes are potentially preventable by an I-ADAS that autonomously brakes via an AEB system. Conversely, for an I-ADAS that delivers an alert to the driver, the potential crash prevention effectiveness drops to merely

0-18% of SCP crashes.

31%

0%

44%

2%

47%

10%

47%

16%

47%

18%

0

20

40

60

80

100

1.0 1.5 2.0 2.5 3.0

TTC Threshold, s

Pro

port

ion o

fC

rashes P

revente

d, %

Warning Delivered AEB

Figure 1: Proportion of crashes preventable by timing.

CONCLUSIONS

This study has shown the importance of I-ADAS design on system effectiveness. The effect of TTC-threshold is important to consider given the need for I-ADAS to give both a “timely” response and ensure driver acceptance of the technology. Responses too late run the risk of limiting system effectiveness, while responses too early could lead to a higher proportion of false-alarms, driver annoyance, less reactive drivers, and/or drivers turning off the systems altogether. The advantages of an AEB system are that it has the capacity to (a) respond sooner than a driver and (b) ramp up vehicle acceleration at a higher rate (i.e., higher jerk). In general, the results of this study suggest that I-ADAS will be substantially more effective if AEB is utilized over a warning-based system.

ACKNOWLEDGMENTS

This research was supported by Toyota Collaborative

Safety Research Center and Toyota Motor Corporation.

REFERENCES

[1] NHTSA, FARS: Analytical User's Manual 1975-2015. 2016, U.S. Department of Transportation. [2] Bellis, E. and J. Page, NMVCCS SAS Analytical Users Manual. 2008, NHTSA: Washington, DC.

25 Modeling the Human Body Oral: Duckpond, 9:30


DEVELOPMENT OF SUBJECT-SPECIFIC PROXIMAL FEMUR AND LUMBAR SPINE FINITE ELEMENT

MODELS OF OBESE, OLDER ADULTS TO EVALUATE THE EFFECTS OF WEIGHT LOSS ON BONE STRENGTH

Samantha L. Schoell1, Ashley A. Weaver1, Dan P. Beavers2, Joel D. Stitzel1, and Kristen M. Beavers3

1. Wake Forest School of Medicine, Department of Biomedical Engineering 2. Wake Forest School of Medicine, Department of Biostatistical Sciences

3. Wake Forest School of Medicine, Department of Health and Exercise Science Corresponding Author: Samantha L. Schoell, Email: [email protected]

INTRODUCTION Recommendation of intentional weight loss in older adults remain controversial, due in part to loss of bone density known to accompany weight loss, and potential exacerbation of fracture risk [1]. The purpose of this study is to develop subject-specific finite element (FE) models of the proximal femur and lumbar spine and study the effect of intentional weight loss over 18 months in obese, older adults on bone strength and structure. METHODOLOGY Clinical CT scans of the proximal femur and lumbar spine of 25 (19 F + 6 M) and 30 (21 F + 9 M) obese, older adults, respectively, undergoing an 18-month intentional weight loss intervention were obtained at baseline and post-intervention. Image segmentation of the femur and lumbar spine CT scans was performed using Mimics (Materialise, Plymouth, MI) using bone thresholding techniques and manual editing. Quantitative measures of vBMD of the total hip, femoral neck, and lumbar spine were obtained using N-vivo software (Image Analysis, Columbia, KY) and elasticity-density relationships from the literature were used to derive subject-specific material properties. High resolution cortical bone thickness measurements across the entire surface of the proximal femur and lumbar spine were obtained by applying a validated density-based algorithm [2]. Model development of the subject-specific FE models involved homologous landmark collection and morphing techniques to accelerate the development of the models. The atlas models used include the Global Human Body Models Consortium (GHBMC) M50-O v4.4 femur and the Total HUman Model for Safety (THUMS) AM50 v4.01 lumbar spine. Bone strength was estimated through simulation of a single-limb stance and sideways fall configuration for the femur and quasi-static uniaxial compression for the spine based on experimental tests.

RESULTS Participants lost an average of 9.8% and 10.4% of their body weight for the proximal femur and lumbar spine participants, respectively. Analyses show a significant correlation between weight change and change in total hip and femoral neck vBMD and cortical thickness. No significant correlations were present for the strength data for the femur or any bone measures for the lumbar spine.

Table 1: Correlations and parameter estimates between weight change and change in bone measures, adjusted for

baseline measures and gender. *p-value <0.05. Bone Quality Measure Adjusted r B (SE) Δ vBMD (g/cm3) Total Hip 0.46* 0.003 (0.001) Femoral Neck 0.45* 0.004 (0.002) Lumbar Spine 0.22 0.548 (0.481) Δ Cortical Thickness (mm) Total Hip 0.60* 0.003 (0.001) Femoral Neck 0.53* 0.003 (0.001) Lumbar Spine -0.20 -0.002 (0.002) Δ Estimated Strength (kN) Femoral Stance -0.16 -0.004 (0.005) Femoral Fall -0.30 -0.003 (0.002) Lumbar Spine -0.13 -0.007 (0.010)

CONCLUSIONS The techniques used can be applied to a larger sample population to further understand the effects of intentional weight loss on bone health and the help aid clinicians in designing optimal weight loss strategies. REFERENCES [1] Waters DL et al., Exp. Gerontology, 48(10), 2013. [2] Treece GM et al., Med Image Anal, 14(3), 2010.

Oral: Drillfield, 1:15 Evaluations of Head Injury 26


STAR FOR YOUTH AND VARSITY FOOTBALL HELMETS: CHARACTERIZING HELMET PERFORMANCE

USING LINEAR AND ROTATIONAL HEAD ACCELERATION

David W. Sproule1, Eamon T. Campolettano1, Steven Rowson1

1. Virginia Tech, School of Biomedical Engineering and Sciences Corresponding Author: David W. Sproule, Email: [email protected]

INTRODUCTION Two fundamental principles are the basis of all STAR methodology: 1) helmets that reduce head acceleration will reduce concussion risk and 2) each laboratory impact is weighted based on how often a player experiences a similar impact. The STAR evaluation system was originally developed to inform consumers on the relative impact performance of varsity football helmets (intended for players over age 14).1 Although this methodology advanced helmet design, rotational acceleration, which is an important factor in concussion, was not considered. STAR for hockey helmets was developed using exposure specific to hockey players, and addressed the need for rotational acceleration in the evaluation.2 The purpose of this investigation was to update the STAR methodology for varsity football helmets to include rotational acceleration and to also develop a STAR methodology specific to youth football helmets. METHODOLOGY The previously used adult surrogate was scaled to produce a youth-specific surrogate. The differences in impact response were investigated using a vinyl nitrile impactor at locations (front, front boss, side, and back) and impact velocities (3.1, 4.6, and 6.1 m/s) to be tested in STAR tests. Weightings for laboratory tests were produced through bivariate empirical distribution functions specific to players wearing youth and varsity helmets. To demonstrate STAR methods, two pairs of matched youth and varsity football helmets were tested. RESULTS Significant effects existed in the evaluation between the youth and adult surrogate, although the differences found were relatively small and there was little variation in the overall impact response.

Figure 1: The adult surrogate (left) and scaled youth surrogate (right)

STAR values were produced for the two youth and varsity helmets using the outlined evaluation systems. The STAR values for youth helmets are lower due to the decreased impact exposure of the youth players.

Table 1: Summary of results for demonstrative STAR tests.

Varsity Helmet STAR Youth

Helmet STAR

A 5.864 5.864 2.268 B 3.035 3.035 1.314

CONCLUSIONS This investigation put forth methods to advance STAR for youth and varsity football helmets, and demonstrated the ability of the methods to detect relative differences in impact performance between helmets. REFERENCES 1. Rowson S and Duma SM. Development of the STAR Evaluation System for Football Helmets Ann Biomed Eng. 2011; 39: 2130-40. 2. Rowson B, Rowson S and Duma SM. A Methodology for Assessing the Biomechanical Performance of Hockey Helmets. Ann Biomed Eng. 2015; 43: 2429-43.

27 Lower Extremity Biomechanics Oral: Duckpond, 1:15


FOOT AND ANKLE RESPONSE IN THE UNDERBODY-BLAST ENVIRONMENT

Laura C. Watkins1, Aaron T. Scott1, Andrew R. Kemper2, John H. Bolte IV3, Warren N. Hardy2, Kerry A. Danelson1

1. Wake Forest School of Medicine, Department of Orthopaedics 2. Virginia Tech, Center for Injury Biomechanics

3. Ohio State University, Injury Biomechanics Research Center Corresponding Author: Laura Watkins, Email: [email protected]

INTRODUCTION Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF) were among the first conflicts where improvised explosive devices (IEDs) were used strategically and with devastating results (Singer, 2012). Of Warfighters wounded in OIF and OEF, 44% were injured from an explosive device (Mckay, 2010). The lower extremity is the initial impact point during these underbody blasts and receives the largest axial forces in the body. METHODOLOGY Information on Warfighter injuries in mounted UBB attacks was obtained from the Joint Trauma Analysis and Prevention of Injury in Combat (JTAPIC) program. This data was reviewed in a manner similar to automotive case reviews (Schneider et al., 2011). However, the methodology was updated to correlate to military needs. The experimental testing consisted of 14 male post-mortem human surrogates (PMHS) in a series of 8 tests. The accelerative loading fixture (ALF) was designed to produce a high-amplitude, high-rate vertical loading environment commensurate to UBB events. The general PMHS posture and loading environment varied throughout the test series to create a comprehensive dataset. Following the tests, CT and a detailed autopsy were conducted (Danelson et al., 2015). RESULTS Table 1 illustrates the prevalance of foot and ankle fracture among the 14 PHMS in experimental blast testing. The most common foot/ankle fracture was a calcaneus fracture occuring in 8 of the PMHS. Half of those with fractures were bilateral. Talus fractures are the second most common fracture. 5 of 14 PMHS sustained talus fractures. Metatarsal fractures were the most common forefoot fracture. For the two cadavers with forefoot fractures, they each had multiple metatarsal fractures.

Table 1: Summary of Foot and Ankle Fractures Injury Group Frequency of Injury

1 Calcaneus 8/14 2 Talus 5/14 3 Midfoot 2/14 4 Forefoot 2/14 5 Tibia 1/14

CONCLUSIONS The ALF provides an appropriate environment to study UBB responses. The resulting PMHS fracture patterns corresponded to real-life theater injury data. Calcaneus and talus fractures were the most common foot and ankle injuries among the experimental tests. ACKNOWLEDGMENTS This work was funded by the USAMRMC under Award Number W911NF-14-2-0053. REFERENCES Danelson, K. A., Kemper, A. R., Mason, M. J., et al. (2015). Comparison of ATD to PMHS Response in the Under-Body Blast Environment. Stapp Car Crash Journal, 59(November), 445–520. Mckay, B. J. (2010). Development Of Lower Extremity Injury Criteria And Biomechanical Surrogate To Evaluate Military Vehicle Occupant Injury During An Explosive Blast Event. Wayne State University. Schneider, L. W., Rupp, J. D., Scarboro, M., et al. (2011). BioTab--a new method for analyzing and documenting injury causation in motor-vehicle crashes. Traffic Injury Prevention, 12(3), 256–265. Singer, P. (2012). The Evolution of Improvised Explosive Devices (IEDs) | Brookings Institution. Retrieved March 19, 2017.

Oral: Duckpond, 10:00 Modeling the Human Body 28


FINITE ELEMENT BASED PELVIC INJURY METRIC CREATION AND VALIDATION IN LATERAL IMPACT

FOR A HUMAN BODY MODEL

Caitlin M. Weaver1,2,3, Alexander M. Baker1,2, Matthew L. Davis1,2, Anna N. Miller4, and Joel D. Stitzel1,2

1. Virginia Tech-Wake Forest University, Center for Injury Biomechanics 2. Wake Forest University, School of Medicine

3. US Army Research Laboratory, Soldier Protection Sciences Branch 4. Washington University, Department of Orthopaedic Surgery

Corresponding Author: Caitlin M. Weaver, Email: [email protected] INTRODUCTION Pelvic fracture is a very serious injury resulting in a high risk of mortality and resulting morbidity [1]. Mortality and morbidity risk from pelvic fracture vary depending on the type of pelvic fracture. The purpose of this study is to develop injury risk prediction curves for specific regions of the pelvis by comparing the presence of fracture in these regions in experimental testing to the cross-sectional force response in these regions in a total human body FE model. METHODOLOGY The total human body FE model used for this study was Global Human Body Models Consortium (GHBMC) 50th percentile detailed male FE model (v4.3). Lateral impact FE simulations were performed using input data from lateral impact tests performed by Bouquet et al. on post mortem human subjects (PMHS). The simulations were scaled using five normalization techniques. These techniques were validated using log rank testing, Wilcoxon rank sum testing, and correlation and analysis (CORA). Survival analyses were performed on the experimental test data and the simulation test data (scaled and unscaled) to generate injury risk prediction curves for total pelvic injury. This method was used to generate injury risk prediction curves for regional pelvic injury.

RESULTS Pelvic injury risk prediction curves were developed for total pelvic injury risk using applied force and regional pelvic injury risk using cross-sectional force. The results show good correlation for total pelvic injury risk prediction between the experimental and simulation data with most normalization techniques. Based on results from the log rank, Wilcoxon, and CORA analyses, the equal stress equal velocity (ESEV) scaling method was determined to be the best normalizing technique for this study. The injury risk prediction curve generated from

the scaled simulation data shows slight under prediction of injury in comparison to the experimental data curve, however, this difference was determined to not be statistically significant. Injury risk curves were developed for the inferior pubic rami, superior pubic rami, and the sacral iliac region using cross-sectional forces from the simulation results and the occurrence of injury documented in the experimental autopsies.

Figure 1: Weibull model survival analysis for

experimental, simulation, and ESEV scaled simulation. CONCLUSIONS The work performed in the paper provides a robust tool for determining risk of pelvis fracture in the FE environment. The injury risk prediction methods developed in this study analyze injury metrics on a local level based on fracture location. Additionally, this study looks at risk of fracture based on components of force (i.e. axial vs. shear vs. resultant). This research can be used to analyze the effects of risk mitigation techniques on specific regions of the pelvis to help reduce pelvic injury risk and associated morbidity and mortality in real world impact scenarios. REFERENCES [1] Balogh, Z. et al. The Epidemiology of Pelvic Ring Fractures: A Population-Based Study. J Trauma Inj Infect Crit Care. 2007;63(5):1066-1073.

29 Biomechanics Poster A: Latham B, 10:45


DO INSECT TRACHEAL TUBES COLLAPSE UNDER PRESSURE AS THIN-WALLED CYLINDERS?

Khaled Adjerid1, Hodjat Pendar1, Raffaella DeVita1, and Jake Socha1

1. Virginia Tech Biomedical Engineering And Mechanics Corresponding Author: Khaled Adjerid, Email: [email protected]

INTRODUCTION Insects breathe using a network of tracheal tubes, parts of which rhythmically compress in some species, facilitating active ventilation. Studies suggest hemolymph pressures of 1-2 kPa may induce tracheal tube collapse in beetles. However, it’s unknown if pressure induces collapse, or if other physiological processes are at play. Considering the tracheal system as an isolated mechanical system, we ask, do tracheal tubes respond to fluid pressure as thin-walled cylinders? If so, their response to pressure can be predicted using an analytical thin-walled cylinder model, which assumes the tubes to be long, thin, and circular, with elastic and isotropic walls. METHODOLOGY We used atomic force microscopy (AFM) to measure elastic moduli and microtome sectioning to determine thicknesses of tracheae throughout the tracheal system of the beetle Zophobas morio. To determine collapse pressures of tracheae in sacrificed beetles (N=11), we manually increased pressures to physiologically-relevant maxima (~2 kPa, in the thorax) while simultaneously recording collapse using synchrotron X-ray imaging at Argonne National Laboratory.

Figure 1: Histological sections and linear sections made of tracheae (top) and bioAFM measurements of different

sized tracheae, testing tip is at the edge of triangular section (bottom).

RESULTS We found that tracheae collapsed at physiologically relevant values, and that large tubes (d>250 µm) collapsed at roughly twice the pressure (0.59±0.12 vs 0.33±0.06 kPa) than small tubes (d<250 µm). Preliminary AFM results revealed an elastic modulus on the order of ~2 GPa. Sectioning showed that the thicknesses of the tracheae ranged between 4-25 μm for tubes with diameters of 10-200 μm. Wall thickness scaled with negative allometry, meaning that larger tubes are relatively thinner with respect to their diameters than are smaller tubes.

Figure 2: We found that the log of tube thickness scales with negative allometery with the log of diameter of the tubes, with an allometric scaling exponent (b) of 0.46.

CONCLUSIONS Using these values, the model predicts an inverse relationship between collapse pressure and diameter, with larger tubes requiring less pressure for collapse, congruent with the values obtained with X-ray imaging. Additionally, the negative allometric scaling of wall thickness suggests that larger tubes collapse at even lower pressures than would be expected. These results support the hypothesis that increases in hemolymph pressure induce collapse during rhythmic tracheal compression. ACKNOWLEDGMENTS Supported by NSF 1558052. We thank Steve McCartney for help with AFM and Ngozi Nwoke and Alex Mclean for help with analysis, and Kamel Fezzaa of Argonne National Laboratory for help with X-ray imaging.

Poster B: Latham B, 11:15 Biomechanics 30


VALIDATION OF A DIRECT METHOD FOR MEASURING HEPATIC AND SPLENIC PRESSURES OF POST-

MORTEM HUMAN SURROGATES DURING FULL-SCALE FRONTAL SLED TESTS

Devon L. Albert1, Stephanie M. Beeman1, and Andrew R. Kemper1

1. Virginia Tech, Department of Biomedical Engineering and Mechanics Corresponding Author: Devon L. Albert, Email: [email protected]

INTRODUCTION Although the liver and spleen are the two most frequently injured abdominal organs in motor vehicle collisions1-2, there is a lack of research regarding potential splenic injury metrics. Conversely, previous research has been conducted that correlated internal liver pressure to liver injury risk3-4. Such studies have instrumented the livers of whole-body post-mortem human surrogates (PMHSs) with pressure sensors via an indirect method guided by fluoroscopy. Fluoroscopy is expensive and can be time consuming when routing sensors to a target location through peripheral vasculature. Therefore, a more direct approach is needed to instrument the solid abdominal organs with pressure sensors. The objective of this research was to implement a direct approach for pressure sensor instrumentation of the liver and spleen of PMHSs and validate the measured pressures obtained during full-scale frontal sled tests against previous research involving comparable blunt impacts. METHODOLOGY The abdominal cavities of six fresh, previously frozen PMHSs were accessed, and the hepatic and splenic arteries were located. Both arteries were cut after branching from the celiac trunk, and Millar catheter style pressure sensors were inserted into the open arteries and routed through the vasculature to the liver and spleen. Each PMHS underwent one full-scale frontal sled test under one of two safety restraint conditions: knee bolster or knee bolster airbag. All tests involved a seatbelt and steering wheel airbag. Before each test, the vascular system was pressurized as follows: the hepatic artery to 2 psi, the splenic artery to 2 psi, the carotid artery to 2 psi, and the jugular vein to 0.5 psi. The peak hepatic pressures from the sled tests were compared to those reported by previous studies using a Welch’s ANOVA. RESULTS Hepatic peak pressures ranged from approximately 40 to 76 kPa, while splenic peak pressures ranged from approximately 34 to 105 kPa. The pressure time histories

of each organ were variable with different shapes and peak timing. Variation between tests was likely a result of differences in anthropometry between subjects. Organ location relative to safety restraints, such as the seatbelt and airbag, or other vehicle components, such as the steering wheel, can influence the magnitude and timing of loading experienced from contact with these features. The ANOVA comparing the hepatic pressures from the sled tests to previous studies resulted in a p-value of 0.955. This implied that the pressures from the current study were not significantly different from those reported by previous studies. CONCLUSIONS This study successfully implemented a direct approach for instrumenting the livers and spleens of PMHSs with pressure sensors. Further research should be conducted to develop and validate injury risk curves for the liver and spleen. ACKNOWLEDGMENTS The authors would like to thank the Toyota Motor Corporation for sponsoring this research. REFERENCES 1. A. M. Elhagediab et al., "Patterns of abdominal injury

in frontal automotive crashes," in The 16th International Technical Conference on the Enhanced Safety of Vehicles, 1998.

2. N. Yoganandan, et al., "Patterns of abdominal injuries in frontal and side impacts," in Annual Proc Assoc Adv Automot Med, 2000, pp. 17-36.

3. J. L. Sparks, et al., "Using pressure to predict liver injury risk from blunt impact," Stapp car crash journal, vol. 51, pp. 401-432, 2007.

4. M. A. Kremer, et al., "Pressure-based abdominal injury criteria using isolated liver and full-body post-mortem human subject impact tests," Stapp car crash journal, vol. 55, p. 317, 2011



EFFECTS OF AUTOMATIC EMERGENCY BRAKING ON OCCUPANT KINEMATICS

Roy Anderson1, and Andrew Kemper, Ph.D. 1

1. Virginia Tech, School of Biomedical Engineering and Sciences Corresponding Author: Roy Anderson, Email: [email protected]

INTRODUCTION Automatic Emergency Brakes (AEB) is a safety mechanism in cars used to reduce speed or completely stop the car before an impact. AEB utilizes radar scanning to detect traffic or objects in front of the car, alerts the driver of the potential hazard, and then automatically decelerates the car if the driver does not apply brakes. AEB’s are highly effective at preventing crashes at

speeds less than 25 mph. While at speeds greater than 55 mph, the AEB will decrease speed, but not prevent the crash, also while decreasing the speed the occupant can be displaced into a non-ideal position, thus increasing the chance of injuries such as fatal rib fractures1. The occupant kinematics, or the occupant’s movement

through the car is highly related to injury. From this understanding, the focus of this project is to research the effects of AEB braking at high speeds on occupant kinematics to assess the chances of occupant injury. METHODOLOGY A total of 6 subjects 3-male and 3-female will be subjected to testing. A total of 36 tests will be conducted. Subjects will be positioned at the center of the test seat with the feet centered on the footplates and hands on the steering column. Their feet will be centered on the footplates with hands on the steering column. Each try will have a standard load limiting driver-side 3 point seat belt position around the test subject and slack will be removed. Dynamic low severity crash pulse tests will be conducted at varying decelerations using a custom mini-sled and test buck accelerated by a pneumatic piston. A Vicon motion analysis system (Vicon Motion Systems, Centennial, CO), consisting of 12- MX-T20 2 megapixel cameras will be used to quantify the 3-dimensional occupant kinematics of the volunteers and the test sled at a sampling rate of 1kHz. Reflective markers will be adhered to each test subject and the test buck. A 3-D reconstruction of the Vicon data will be generated. High speed video will also be captured from the subjects’ lateral aspect at a sampling

rate of 1kHz with the use of a high resolution, high light sensitivity camera.

Figure 1: (Left) Image of custom test buck with pneumatic piston. (Right) anatomical marker placement

A Vicon motion analysis system (Vicon Motion Systems, Centennial, CO), consisting of 12- MX-T20 2 megapixel cameras will be used to quantify the 3-dimensional occupant kinematics of the volunteers and the test sled at a sampling rate of 1kHz. Reflective markers will be adhered to each test subject and the test buck. A 3-D reconstruction of the Vicon data will be generated. High speed video will also be captured from the subjects’

lateral aspect at a sampling rate of 1kHz with the use of a high resolution, high light sensitivity camera. Changes in occupant kinematics, and injury risk between the AEB pulse and constant deceleration pulse will be compared to assess the effects of AEB on occupant kinematics. Statistical analysis will be conducted using Matrix Laboratory and Microsoft Excel (Microsoft Corp, Redmond, WA). Analysis of variance will be conducted between each severity tests (1.0g vs. 1.15g, 1.15 vs. 1.3 g, 1.0 vs. 1.3 g) to analyze the effects of severity on occupant kinematics. . REFERENCES 1. n.d. (2016). Autonomous Emergency braking. Web. ThatCam Research. 2. Ólafsdóttir et al. (2013). Passenger Kinematics and Muscle Responses in Autonomous Braking Events with Standard and Reversible Pre‐tensioned Restraints. IRCOBI Conference 2013 3. Saito et.al. (2016) Evaluation of Frontal Impact Restraint System in Integrated Safety Scenario Using Human Body Model with PID Controlled Active Muscles. IRCOBI Conference 2016. 4. Beeman et.al. (2011) Effects of Bracing on Human kinematics in low speed frontal sled tests., Annals of Biomedical Engineering

Poster B: Latham B, 11:15 Biomedical Imaging 32


THE IMPACTS OF PESTICIDE AND NICOTINE ON FUNCTIONAL BRAIN NETWORKS IN LATINO

FARMWORKERS

Mohsen Bahami1, Paul J. Laurienti1,2, Thomas A. Arcury3, and Sean L. Simpson1,4

1. Virginia Tech – Wake Forest School of Biomedical Engineering and Science 2. Department of Radiology, Wake Forest School of Medicine

3. Department of Family and Community Medicine, Wake Forest School of Medicine 4. Department of Biostatistical Sciences, Wake Forest School of Medicine

Corresponding Author: M. Bahrami, Email: [email protected] INTRODUCTION Migrant Latino farmworkers are consistently exposed to pesticides as part of their work. Pesticides that inhibit cholinesterase, such as organophosphates and carbamates, alter acetylcholine levels in the nervous system and are neurotoxic. Long-term exposure to these pesticides may increase the risk of developing neurodegenerative diseases such as Parkinson’s disease. Tobacco farmworkers are not only exposed to pesticides but also experience nicotine exposure through dermal absorption. While it is known that large doses of nicotine are toxic, many studies have indicated that lower, nontoxic doses of nicotine improve cognitive performance. Functional brain network analyses that use rs-fMRI have demonstrated great promise in examining systemic brain changes across health and disease [1]. This study used brain network analyses of rs-fMRI data and a mixed-effects modeling framework [2] to compare brain network connectivity patterns between Latino farmworkers and non-farmworkers. METHODOLOGY 48 Latino farmworkers and 26 non-farmworkers had brain MRI scans and serum cholinesterase measures completed in the same agricultural season as part of a larger study. Functional brain networks were constructed for each subject using their resting state fMRI data. The probability and the strength of a connection were both modeled via a mixed-effects modeling framework. RESULTS Average Clustering Coefficient and Modularity in farmworkers were significantly higher than in non-farmworkers (Figure 1). FC probability and strength differed between farmworkers and non-farmworkers by nodal clustering coefficient and modularity (Table1). Cholinesterase activity was associated with population differences in brain community (not shown here) .

Figure 1. Boxplots for population-level measures of clustering

coefficient and modularity in farmworkers and non-farmworkers.

CONCLUSIONS Farmworkers have more clustered and modular networks than non-farmworkers. Increased modularity could create implications for high-level cognitive tasks. ACKNOWLEDGMENTS This work was supported by NEIHS (grant number: R01 ES008739) and NIH award (K25 EB012236). REFERENCES [1] Bullmore, E. and O. Sporns, Complex brain networks: graph theoretical analysis of structural and functional systems. Nature Reviews Neuroscience, 2009. 10(3): p. 186-198. [2] Simpson, S.L. and P.J. Laurienti, A two-part mixed-effects modeling framework for analyzing whole-brain network data. NeuroImage, 2015. 113: p. 310-319.

Parameter Estimate SE *p-value Farmworker Status (FWS)

-0.039 0.047 0.408

Clustering Coef × FWS

2.087 0.996 0.036

Global Efficiency× FWS

-4.532 2.540 0.074

Degree × FWS 0.033 0.041 0.412 Modularity × FWS -4.548 0.798 <0.0001

Table 1. Summary of Abrasion Test Results

33 Biomedical Imaging Poster A: Latham B, 10:45


PROPOSED ANALYSIS OF MEG DELTA POWER FOLLOWING IMPACT EXPOSURE IN YOUTH

Leonardo Bezerra1, Christopher Whitlow2 1. Virginia Tech – Wake Forest School of Biomedical Engineering and Sciences

2. Wake Forest School of Medicine Corresponding Author: Leonardo Bezerra Email: [email protected]

INTRODUCTION Magnetoencephalography, or MEG, is a technique that measures the firing of groups of neurons within the brain through the associated magnetic fields generated from the short electrical bursts. This technique is a direct, noninvasive measure of brain activity with high temporal resolution. MEG can be used to both measure the locations of brain activity, as well as the determination of which frequency bands are involved in a process. The activity of the brain is generally classified based on the firing frequency, with the Gamma band corresponding to the highest and Delta band activity being the lowest. Increased delta band activity within the brain has been demonstrated following concussion. This frequency band is also seen in various other neurological disease states such as; Alzheimer’s disease, Parkinson’s disease, and schizophrenia. In general, increased levels of delta activity are pathologic in awake humans. Recently, work from our lab has shown that there is an increase in delta band activity after only a season of football in high schoolers. Thus, one could assume that even subconcussive impacts could negatively affect the brain. We believe that there is a causal relationship between the level of impact exposure and the level of delta wave power present within the brain. METHODOLOGY Subjects are to be separated into three groups based on their impact exposure. A group consisting of young athletes who play noncontact sports are to be used as a negative control group. Football players who have had concussions as a result of a football impact are to act as a positive control group. Football players who have not had a previous concussion are to be used as an experimental group. We will attempt to match the experimental group in terms of impact exposure as closely as possible to the positive control group up to the point of concussion. Impacts are to be measured through the use of HITS (Head Impact Telemetry System) sensors built into the

helmets of young adults playing football. Analysis of impact of the biomechanical impact data allows the creation of a Risk Weighted cumulative Impact Exposure (RWE) metric to be generated. Subject anatomical MRI scans have been completed for both pre- and postseason. If a patient was diagnosed with a concussion, a third MRI scan was performed. All MEG signals will be beamformed onto the patients corresponding MRI. MRI data will be warped into MNI space to account for individual variations in shape or size. Preseason and postseason resting state MEG scans have been completed. If a subject was diagnosed with a concussion, a third MEG was done at the time of diagnosis. MEG data is to be processed using an in-house pipeline based on SPM software in matlab in order to do a synthetic aperture magnetometry (SAM) analysis. MEG data are to be baseline corrected, bandstop filtered at 60 Hz and its harmonics, downsampled to 100 Hz, and bandpass filtered from 1 to 4 Hz. Head motion and muscle artifacts will be removed. By using the CTF beamformer and SAM, the voxel-wise power of the delta band can be created for each brain scan. The number of abnormal voxels between the pre and post season scans will be used in this study. Abnormal voxels are to be defined as those 2 standard deviations above the mean. Abnormal voxels counts will be generated from taking the difference of the preseason power map from the postseason power map, determining which are 2 standard deviations above the mean, and totaling them. ACKNOWLEDGMENTS We would like to thank the National Science Foundation (NSF) and the National Institute of Health (NIH) for providing funding for this study.



BICYCLE HELMET IMPACT PERFORMANCE DURING REAL-WORLD OBLIQUE IMPACTS

Megan L. Bland1, Craig McNally1, David S. Zuby2, Becky C. Mueller2, and Steven Rowson1

1. Biomedical Engineering and Mechanics, Virginia Tech 2. Insurance Institute for Highway Safety, Ruckersville, VA

Corresponding Author: Megan Bland, Email: [email protected] INTRODUCTION Cycling is the leading cause of sport-related head injuries treated in U.S. emergency rooms.1 Bicycle helmets must pass a safety standard mandating reduction of peak linear acceleration (PLA) to <300 g in impact tests. However, this level impact is much more severe than typical cyclist accidents (~100 g),2 and the helmet rim, a commonly impacted location,2-3 is not tested. The standard also only conducts normal impacts and measures PLA, while real-world accidents are oblique3 and have rotational acceleration as well, a contributor to concussion.4

This study aimed to investigate the impact attenuation capabilities of bicycle helmets under real-world accident conditions using an oblique impact rig. METHODOLOGY Ten varied bicycle helmet models were impacted on a custom drop tower containing a NOCSAE head, Hybrid III 50th-percentile male neck, and an effective torso mass. Oblique impacts were simulated on a 30° anvil. Helmets were tested at a frontal (at the helmet rim) and a temporal location at normal velocities of 4.4 and 5.7 m/s, producing 4 possible configurations. Both locations and the low velocity reflect common cyclist accidents,2-3 while the high velocity represents a more severe case. Each configuration was tested 4x per helmet, totaling 160 tests. Three linear accelerometers and three angular rate sensors at the head center of gravity measured impact kinematics. Rotational accelerations were determined from angular rates, and concussion risk was computed from PLA and peak rotational acceleration (PRA).5 Results were compared using ANOVA with Tukey HSD post hoc tests. RESULTS Large variations in acceleration were observed, with PLA and PRA ranging from 66-234 g and 3.3-12.5 krad/s2. PLA was higher in temporal impacts than frontal, while PRA varied less between location. Risk of concussion spanned 2-99% (Fig. 1), with many significant differences

between helmets at all configurations except frontal-4.4 m/s, where all risks were low (<15%).

Figure 1: Concussion risk for all helmets (standard

deviation error bars). Risk varied significantly by helmet within most configurations.

CONCLUSIONS The bicycle helmets tested herein varied widely in protective capabilities, with concussion risk spanning >60% in single impact configurations. For most helmets, PLA was higher for temporal impacts than frontal, resulting in higher injury risks. This may stem from differences in helmet geometry at these locations. Non-road helmets performed consistently worse, and likely have design parameters that are less conducive to impact mitigation. As these configurations reflect real-world cyclist accidents, the present results can be used to inform safer helmet design. ACKNOWLEDGMENTS The authors thank the Insurance Institute for Highway Safety for their funding and support. REFERENCES 1. CPSC, National Electronic Injury Surveillance System,

Consumer Product Safety Commission. Web, 2016. 2. Williams, M, Accid Anal Prev, 23:119-131, 1991. 3. Bourdet, N, J Sports Eng Tech, 226:282-289, 2012. 4. Gennarelli, T, SAE Tech Paper 720970, 296-308, 1972. 5. Rowson, S, Duma, S, Ann Bio Eng, 41:873-882, 2013.

35 Biomaterials Poster A: Latham B, 10:45


KERATIN COATED PLASMA ETCHED PARYLENE C FOR NEURAL INTERFACES

Kyle Brown1, Alexis Trent

2, and Mark Van Dyke

3

1. Virginia Tech, Biochemistry and Nanoscience

2. Virginia Tech, Material Science and Engineering

3. Virginia Tech, Biomedical Engineering and Sciences

Corresponding Author: Mark Van Dyke, Email: [email protected]

INTRODUCTION

Implantable neural interfaces such as the Utah Electrical

Array have been used to study and treat neural disorders

by converting neural impulses into electrical signals1.

However as with most percutaneous devices significant

problems have arisen from biocompatibility issues that

cause both a foreign body response from the host and a

multitude of infections at the site of implantation2. To

reduce problems with percutaneous neural implants we

want to coat the parylene C with keratin nanomaterials to

reduce the foreign body response from the host and the

risk of infection.

METHODOLOGY

One cm

2 titanium substrates were coated with Parylene C

and plasma etched at the University of Utah. The

substrates were then coated with 10% 3-

Isocyanatopropyltriethoxysilane (ICPTES) or 5 %

Glycidoxypropyl-trimethoxysilane (GPTES) in a 100%

ethanol or a 95:5 ethanol –water mixture and saturated for

3 hours. The silane mixture was removed and the

substrates were dried for 30 minutes at 110C. The

ICPTES coated substrates were then coated with keratin

(iKTN) and GPTES coated substrates were soaked in

keratose (gKOS) and soaked for 24 hours and rinsed with

water thereafter. The substrates were then sterilized via

UV light for 1 hour. X-ray Photoelectron Spectroscopy

(XPS) and Atomic Force Microscopy (AFM) were used to

validate the surface. Glial cells were seeded onto each

substrate and incubated for 24 hours. The cells were then

stained and imaged for cellular adhesion. Coated titanium

wires were inserted into 96 well plates with 10,000 glial

cells to observe the thickness of cellular encapsulation.

The data was statistically analyzed via ANOVA.

RESULTS

Shown in Figure 1, we have confirmed that an increase of

nitrogen is present on the KTN and KOS substrates and

have observed the topography through AFM (data not

shown).

Nitrogen

Pla

in P

aryl

ene

C

ICPTE

S

GPTE

S

iKTN

gKOS

0

5

10

15NonPlama Treated

Plasma Treated

Substrate

Ele

men

t P

erc

en

tag

e

Figure 1: XPS on Parylene C substrates for Nitrogen.

Figure 2 shows the optical differences between Plain

Titanium (pTi) and iKTN for glial cell encapsulation

thickness at Day 7.

Figure 2: A) pTi and B) iKTN are shown to observe glial

cell encapsulation thickness.

CONCLUSIONS

We have confirmed that keratin nanomaterials are able to

attach to Parylene C. We have observed the glial focal

adhesions (data not shown) and cellular encapsulation

thickness.

REFERENCES

1. Xie, X., et al. Journal of Neural Engineering 2014,

11 (2), 026016.

2. Chang, T. Y, et al. A. Langmuir 2007, 23 (23), 11718–

11725.

A B



EVALUATING THE PERFORMANCE OF ALTERNATIVE SHOULDER STABILIZATION METHODS

Kristine Cantin1, Sophia Ulman1, Jang-Ho Park1, Sunwook Kim1 and Maury A. Nussbaum1

1. Virginia Polytechnic Institute and State University Corresponding Author: Kristine Cantin, Email: [email protected]

INTRODUCTION Secondary pain and discomfort cause concern for clinicians when prescribing braces to patients that require shoulder stability, and may result in poor compliance by the patient if prescribed for longer durations1. Shoulder straps are often used in conventional brace design for stability, yet they are potential sources of discomfort. Novel supporting methods used in more recently developed braces could mitigate the above concerns associated with traditional bracing methods while stabilizing the shoulder. By comparing the impacts of different designs on stability, this work was intended to facilitate improved future brace prescriptions. METHODOLOGY A total 10 young adults (M = 24.2±4.9) and 10 older adults (M = 66.9±4.3), gender-balanced in each group, completed this study. A within-subjects design was implemented to test the stability of five arm braces, including four existing braces on the market and one newly developed brace. The study consisted of simulated activities of daily living (ADLs) with stability defined as shoulder immobilization and quantified by muscle activity and movement of the braced arm. Participants were asked to reach and retrieve objects; during these tasks surface electrodes on the descending trapezius and deltoid of the braced arm (Figure 1) measured muscle activity and motion capture tracked displacements between the braced arm and trunk. Raw EMG data were collected at 1000 Hz using a telemetered system (Noraxon DTS EMG TeleMyo) and 3D marker locations were tracked at 100 Hz using a 6-camera system (Nexus MX-T, Vicon).

Figure 1: Surface electrode placement on the braced

shoulder in accordance with SENIAM guidelines.

RESULTS Raw EMG and motion capture data were low-pass filtered, and EMG data were normalized to maximal values. Separate mixed-factor analyses of variance (ANOVA) were used to assess the effects of brace, age, and gender on each of the outcome measures, with brace order as a blocking effect (Table 1, for forward reach).

Table 1: ANOVA results for brace main effect during forward reach (* denotes significance).

Measure F(p)

Mean EMG Signal 11.49 (<0.0001)*

Maximum Forearm Rotation 8.77 (<0.0001)*

Maximum distance of forearm from trunk

21.68 (<0.0001)*

CONCLUSIONS Regardless of additional straps on common braces, there were rarely clinically significant differences (~3mm) in movement when compared to single-waist strapped braces. Muscle activity was frequently lower while wearing a brace without shoulder straps, indicating participants minimally use their “injured” braced shoulder while in the strapless braces. These results reveal that a novel brace design offers a potential solution to shoulder immobilizing without the concern of shoulder straps. ACKNOWLEDGMENTS This research was financially supported by GENEDGE. While contributing to the study design, it had no involvement in data analysis or interpretation. REFERENCES 1. Struijs, P., et al. (2004). Conservative treatment of lateral epicondylitis brace versus physical therapy or a combination of both—a randomized clinical trial. American Journal of Sports Medicine, 32(2), 462-469.



SIMPLE, CUSTOMIZABLE, COST-EFFECTIVE NANOPARTICLE VACCINE DELIVERY SYSTEM

Jewel M. Cary1 and Dr. Abby R. Whittington1,2,3

1. Virginia Tech-Wake Forest University (School of Biomedical Engineering & Sciences) 2. Virginia Tech (Department of Materials Science and Engineering)

3. Virginia Tech (Department of Chemical Engineering) Corresponding Author: Jewel M. Cary, Email: [email protected]

INTRODUCTION Poultry vaccine production for disease prevention is driven by economics and requires balancing animal welfare with human labor costs. The industry is shifting toward mass vaccination strategies that are both cost-effective and less labor intensive for economic reasons as well as to reduce animal stress and human health concerns. Viegas, et al found poultry workers have a high prevalence for asthmatic (42.5%) and nasal (51.1%) symptoms due to increased particulate matter found in poultry farm dust [1]. Additionally, a study in Occupational Medicine found veterinarians and other animal care professionals are at high risk of occupational sensitization to animal allergens and minimizing airborne animal allergens is key to reducing the risk of sensitization [2]. This research attempts to address these needs in developing a novel, low cost mass vaccination system for aerosol or oral delivery of poultry vaccines to replace conventional, labor-intensive individual injection vaccinations. METHODOLOGY A two-step desolvation technique was used for nanoparticle (NP) fabrication utilizing basic lab equipment and materials to make this system cost-effective. For proof of concept fabrication, different inert encapsulation materials and tracking dyes were incorporated to demonstrate the system is simple and customizable. Characterization of NPs included average diameter, average polydispersity index (PDI), changes in the aforementioned parameters over time and after freezing, crosslinking time, and encapsulation. RESULTS Initial NP sizes and PDI range from 217.83 ± 3.95 nm diameter with a PDI of 0.061 ± 0.023 (plain) to 330.37 ±

4.40 nm diameter with a PDI of 0.11 ± 0.030 (with encapsulation). We have shown various NP types are stable for at least one month at room temperature in water. Including a similarly sized encapsulation material alters NP morphology (Figure 1) and leads to less variation in diameter and PDI over time. Additionally, we have found various NP types are stable through the typical vaccine storage freeze/thaw conditions.

CONCLUSIONS We have accomplished our goal of creating a stable nanoparticle delivery system that is simple to fabricate and customizable to the desired application. Future work will include crosslinking, encapsulation, and cell studies to better characterize and streamline fabrication. ACKNOWLEDGMENTS The authors would like to thank the Regenerative Medicine IGEP for support for JM Cary, the VM College of Veterinary Medicine Morphology Lab for assistance with imaging, and Dr. Frank William Pierson for helpful discussion. REFERENCES [1] Viegas, S., V. M. Faísca, H. Dias, A. Clérigo, E. Carolino, and C. Viegas. J Toxic Environ Health: A, 76.4-5 (2013): 230-39. [2] Moghtaderi, M., S. Farjadian, and M. Abbaszadeh Hasiri. Occupat Med 64.7 (2014): 516-20..

Figure 1: Initial scanning electron microscopy NP images. Scale bar represents 1000nm. (A) Plain NP morphology shows a different morphology than (B)

encapsulated NPs

B A



RESPONSE OF FEMALE AND MALE PMHS TO BLAST-INDUCED VERTICAL ACCELERATIVE LOADING

Danielle M. Cristino1, Warren N. Hardy1

1. Virginia Polytechnic Institute and State University, Biomedical Engineering and Mechanics (BEAM) Corresponding Author: Danielle M. Cristino, Email: [email protected]

INTRODUCTION Improvised explosive devices (IEDs) deliver a high energy blast to the underbody of military vehicles, exposing modern Warfighters to considerable risk during ground transport. Biomechanical data are required to develop an operationally relevant anthropomorphic test device (ATD) suited for the assessment of risk associated with the female Warfighter, or to map the injury prediction outputs of a male ATD to the female. The objective of this study is to determine the origin of the differences between female and male impact and injury response, such as sex, morphology, anatomy, or tolerance. METHODOLOGY This study was conducted using the Accelerative Loading Fixture (ALF), which generates floor and seat loading conditions representative of the underbody blast (UBB) environment. The ALF consists of two rigid seats mounted to a platform that is accelerated upward within a superstructure frame. The platform is explosive-driven. A brake system arrests its motion as it passes through the apex of its travel. The floor and seat performance can be modulated independently. Twelve post-mortem human surrogates (PMHS) were tested in pairs, using two different floor conditions. The PMHS tested include 50th percentile males, and 5th and 75th percentile females. The PMHS were instrumented with strain gages, accelerometers, angular rate sensors, and video markers. The data obtained include floor and seat acceleration and speed, generalized kinematics of the distal tibia and femur, sagittal perspective planar segment motion, and PMHS lower extremity damage results. RESULTS The female and male tibia vertical acceleration responses are similar, with the females attaining greater acceleration earlier in the event. The female PMHS tibia (especially 5th percentile) attains greater peak vertical speed compared to males. Also, peak speed for the females is reached earlier in the event compared to males. Similar trends are observed for femur acceleration and speed, with the 5th percentile female reaching greater vertical

acceleration and peak vertical speed earlier in the event. The femur response of the female is notably shorter in duration, but similar in shape to the male response. The female lower extremities initially rotate in the sagittal plane at a higher rate than the males. For the lower-energy floor condition, no female nor male PMHS sustained damage to the lower extremities, with the exception of a minor talus chip observed in a 5th percentile female. For the higher-energy floor condition, differences were seen between 5th and 75th percentile females. In one test, a lighter female sustained a complete separation of the body of the right (outboard) talus, a pilon fracture to the left (inboard) tibia, a segmented bending fracture to the left femur, and bilateral crushed calcanei. In the same test, a large female sustained a crushed right calcaneus, a compression fracture to the left distal tibia, and a complete oblique fracture to the left distal fibula. In another test, a 50th percentile male sustained bilateral crushed calcanei and a spiral wedge fracture of the left femur, while a small female sustained bilateral crushed calcanei and a fracture through the posterior calcaneal articular surface of the left talus. CONCLUSIONS The female and male lower extremity vertical acceleration and speed responses are similar, with the females attaining greater peak acceleration and speed earlier in the event. Damage was sustained by the calcanei, tali, tibiae, and fibulae. ACKNOWLEDGMENTS This work was funded by the USAMRMC. REFERENCES Danelson, K.A., Kemper, A.R., Mason, M.J., Tegtmeyer, M., Swiatkowski, S.A., Bolte, J.H. and Hardy, W.N. (2015) Comparison of ATD to PMHS Response in the Under-Body Blast Environment. Stapp Car Crash J 59: 445-520.

39 Nanobioengineering Poster A: Latham B, 10:45


DEVELOPMENT OF 19F MRI TRACKABLE NANODELIVERY SYSTEM FOR ANTICANCER DRUGS

William Crowe1, Zhi Dai1, Lulu Wang1, Zhongwei Zhang1, Dawen Zhao1

1. Department of Biomedical Engineering, Wake Forest University School of Medicine Corresponding Author: William Crowe, [email protected]

INTRODUCTION One emerging nanotechnology with enormous potential in image-guided anticancer therapy involves the hybrid of imaging and therapeutic agents. Compared to traditional 1H MRI, 19f MRI has yet to be widely applied for MRI-guided drug deliver due to its relatively low sensitivity. However, 19F MRI is advantageous in vivo due to the lack of background signal1. Thus, improving sensitivity of 19F MRI contrast agents is vital to expand the utility of 19F MRI in drug delivery. In this study, we aim to develop a perfluoro-15-crown-5-ether (PFCE)-based nanocarrier system loaded with a potent anticancer drug, Monomethyl auristatin E (MMAE). MMAE is a cell mitosis inhibitor that has been shown to be several orders of magnitude more potent than conventional drugs. METHODOLOGY Polymeric PFCE MMAE micelles (MMAE-mNP-PFCE) were made by dissolving PEG2kPE and MMAE in chloroform, drying the solution to create a lipid film, and hydrating the film with DI water and PFCE. The nanoparticles were characterized using a Zetasizer Nano and HPLC was conducted to measure MMAE concentrations. . 19F MRI experiments were conducted using a Bruker Biospin 7T small animal scanner. Data were analyzed using house-built Matlab scripts. Brain tumor cells G44 and MDA MB231Br were cultured for in vitro cytotoxicity study. RESULTS The scheme of MMAE-mNP-PFCE is shown in Figure 1a. DLS measurement of the particle indicated a diameter of 133 nm with high monodispersity and stability. HPLC revealed that MMAE loading efficiency was 47%, higher than that in micellar MMAE without PFCE (32%). 19F MRI of a serial dilution of MMAE-mNP-PFCE determined sensitivity as low as 0.07 mM PFCE (Figure 1b, d). In vitro cytotoxicity studies showed that MMAE-mNP-PFCE was equally effective against several brain tumor cell lines that were resistant to conventional chemotherapeutic drugs. Furthermore, in vivo longitudinal 19F MRI showed that 19F MRI signal was detected primarily in circulation 1 day after i.v. injection,

while 5 days post-injection 19F MRI signal was primarily present in the reticuloendothelial system. CONCLUSIONS We have developed a novel polymeric micelle loaded with PFCE and MMAE with high 19F MRI sensitivity and high drug loading efficiency. The 19F sensitivity achieved in our study was even higher than previously reported, which will facilitate 19F MRI-guided deliver of MMAE. Here, we have achieved 19F MRI signal in PFCE concentrations in vitro as low as 0.07 mM while previous work by others suggested sensitivity at 0.084 mM3. To further improve its cancer-targeting sensitivity and specificity we are currently working to functionalize the nanocarrier with cancer-specific moieties.

Figure 1. a. Polymeric PFCE MMAE micelle. b) 19F MRI signals in samples 1 through 7 corresponding to

1.96, 0.98, 0.49, 0.25, 0.13, 0.07, and 0.00 mM concentration. c) Proton MRI data. d) Fluorine MRI

signal intensity vs PFCE concentration. ACKNOWLEDGMENTS Brain tumor research has been supported in part by NIH R01 CA194578 and Wells Fargo Scholar Program. REFERENCES 1. Ruiz‐Cabello, Jesús, et al. NMR in Biomedicine 24.2 (2011): 114-129. 2. Dosio, Franco et al. Toxins 3.7 (2011): 848-883. 3.Matsushita, Hisashi, et al. Angewandte Chemie International Edition 53.4 (2014): 1008-1011.


Poster B: Latham B, 11:15 Translational Cancer 40


PRECISION MEDICINE APPROACH TO IMPROVING RECONSTRUCTIVE SURGERY OUTCOMES FOR

BREAST CANCER SURVIVORS

Katherine Degen1, Kurtis Moyer

2, Robert Gourdie

1

1. Virginia Tech Carilion Research Institute, School of Biomedical Engineering

2. Carilion Clinic, Plastic and Reconstructive Surgery

Corresponding Author: Katherine Degen, Email: [email protected]

INTRODUCTION

The single most common and serious complication of

reconstructive surgery is the formation of a dense scar

capsule around the silicone implant called capsular

contracture. Nearly all patients will experience this

complication, though with different degrees of response,

ranging from moderate scarring to major disfigurement

and pain at the implant site. Presently, there is no way to

predict the degree of contraction capsule formation that

individual patients will suffer prospectively, nor is there

clinical approach to preventing this complication.

METHODOLOGY

Dr. Kurtis Moyer MD, Chief of Plastic Surgery at

Carilion, is providing patient samples of scar capsule and

de-identified medical information under an active IRB.

The standardization of collection is achieved by sampling

scar capsule tissue, from around an implanted breast

expander device placed by Dr. Moyer, at a precisely

defined anatomical location and at a standardized time

interval following implantation of the device. Tissue

samples are prepared for histology, RNAseq, and patient

fibroblast explants.

RESULTS

RNAseq has been performed on a cohort of 6 patients.

The most differentially expressed protein was Cysteine

Rich, Angiogenic Inducer 61 (CCN1), a matricellular

protein with various roles depending on the context of

expression. It is known to induce angiogenesis while also

promoting fibroblast senescence; both of which could

play a role in capsular contracture. Further work is being

done to expand on these findings.

Additionally, work is being completed to compare

symmetric and asymmetric responses to implant

placement.

Figure 1. CCN1 Expression. A) RNAseq summary of

grades 2 and 3, B) Patient breakout of CCN1 expression

(RNAseq) C) qPCR Confirmation of RNAseq results

ACKNOWLEDGMENTS

LISA Collaboration: Jiangeng Huang and Sumin Shen

Virginia Tech Biocomplexity Institute

*

A B

C

41 Biomedical Imaging Poster A: Latham B, 10:45


IMPULSIVITY IS REDUCED IN SOCIAL DRINKERS FOLLOWING REAL-TIME FMRI

Harshawardhan Deshpande, Jonathan Lisinski, Sarah Snider, Mikhail Koffarnus, Warren K. Bickel, and Stephen LaConte

1. Biomedical Engineering and Mechanics

2. Virginia Tech Carilion Research Institute

3. Psychology, Virginia Tech

Corresponding Author: Harshawardhan U. Deshpande, Email: [email protected]

INTRODUCTION

The essential requirement of a multivoxel pattern-based

real-time fMRI (rtfMRI) study is to build accurate

classifiers to provide neurofeedback. In addition, offline,

second-level brain maps of these classifiers can lead to

insights about the neurobiological underpinnings of the

neurofeedback. Finally, if the rtfMRI experiment is

efficacious, it would lead to subsequent changes in the

participants’ behavior. In this study, we report an rtfMRI

neurofeedback experiment in social drinkers and

individuals with alcohol use disorder (AUD) to 1) develop

a support vector classifier (SVC) of episodic future vs.

present thinking, 2) help individuals gain volitional

control of brain networks responsible for modulating

impulsivity and 3) utilize episodic future thinking (EFT)

as an intervention to change out-of-scanner impulsivity.

METHODOLOGY

Thirty-one subjects generated hypothetical present and

future purchases of $50 now or $100 in the future. In the

first of three fMRI runs, they were presented with a static

horizontal slider bar display that alternately highlighted

the prompts NOW or FUTURE (counterbalanced

left/right across subjects), with the corresponding

purchase cue at the center of the screen. They were

instructed to think about the relevant time frames for each

cue. Using the first run, an SVC of the future condition

vs. the now condition was trained (3dsvm in AFNI1,2,3

)

and used to provide rt neurofeedback in the form of a

moving slider bar in runs two and three. Subjects

controlled the slider bar by modulating their brain

between now and future time frames.

RESULTS

Across two 12-minute neurofeedback runs (Figure 1A),

subjects demonstrated control over the slider bar with a

mean accuracy significantly greater than chance (p<0.0001). First level GLM analyses and SVC maps ipsilateral to both the now and future conditions showed

activation in the lingual gyrus and fusiform.

Figure 1: Post-scan analyses A: The 31 participants

controlled the slider bar (moving between now and future) as

shown in the average of two real-time neurofeedback runs

with mean accuracy of 69%(±12 sd), which was significantly

greater than chance (p<0.0001). B: A second-level map of

future vs. now shows ipsilateral lingual gyrus/fusiform area

from the perspective of FUTURE on the left and NOW on

the right (p<0.01 FDR corrected). C: After real-time fMRI,

discounting was greater when a subset of these subjects were

presented with their delayed items (p<0.05).

A second-level subtraction accounted for the

counterbalanced display of FUTURE and NOW on the

first level maps. The resulting FDR-corrected group result

is shown in Figure 1B. After neurofeedback, social

drinkers demonstrated significantly less discounting when

presented with cue words related to future items

compared to now items (p<0.05) (Figure 1C).

CONCLUSIONS

We have developed an rtfMRI neurofeedback system in

which subjects successfully modulated their brain activity

in an EFT task. We have demonstrated FDR-corrected

maps relevant to the classification. Further we observed

subsequent improvements in impulsivity in social

drinkers. Together, these results suggest that rtfMRI

enables direct access to brain mechanisms regulating EFT

and has the potential to be used as an intervention for

impulsivity in the context of addiction.

REFERENCES

1. LaConte, 2005, NeuroImage, 2. LaConte, 2007, Hum

Brain Mapp, 3. Cox, 1996, Computers and Biomedical

Research, 4. Bickel, 1999, Psychopharmocology

Poster A: Latham B, 10:45 Biomedical Imaging 42


PHYSICS BASED MODEL FOR RHO-Z IMAGING FROM SPECTRAL COMPUTED TOMOGRAPHY

Xu Dong1, Olga V. Pen1, and Guohua Cao1

1. Virginia Polytechnic Institute and State University, School of Biomedical Engineering and Sciences Corresponding Author: Xu Dong, Email: [email protected]

INTRODUCTION Spectral Computed Tomography (CT) utilize photon counting detectors to collect attenuation information of objects from several different energy ranges instead of integrating all energy information in traditional CT system based on energy integrating detectors. It has been reported that spectral CT systems have the advantages in many applications such as reducing the dose, increasing soft tissue contrast, and characterizing materials. However, since the spectral CT generates a bunch of images at each cross section, it raises a problem that how to represent the massive data from CT images so that all the information could be used to achieve material characterization. Effective atomic number (𝑍𝑒𝑓𝑓) and electron density (𝜌𝑒) are intrinsic properties of materials, which could be used for material characterization. And for compound and mixture, the 𝑍𝑒𝑓𝑓 and 𝜌𝑒 could be calculated based on the composition atoms by the equation of 𝑍𝑒𝑓𝑓 = ∑ 𝑍𝑖 ∗ 𝑤𝑖𝑖 and 𝜌𝑒 = ∑ 𝜌𝑖 ∗ 𝑤𝑖𝑖 . Where 𝑍𝑖 and 𝜌𝑖 are atomic number and electron density of element 𝑖 , and 𝑤𝑖 is the corresponding weight percentage. We developed a mathematical model to retrieve effective atom number map and electron density map from several groups of attenuation images in different energy ranges. And this method could be incorporated with spectral CT for material characterization in the future. METHODOLOGY According to Jackson and Hawkes (1981) [1], the linear attenuation coefficient (𝜇(𝐸, 𝑍)) could be expressed as: 𝜇(𝐸, 𝑍𝑒𝑓𝑓) = 𝜌𝑒 (𝑍𝑒𝑓𝑓

4 𝐹(𝑍𝑒𝑓𝑓 , 𝐸) + 𝐺(𝑍𝑒𝑓𝑓 , 𝐸)) (1) Where:

𝐺(𝐸, 𝑍) = 𝜎𝐾𝑁 +(1 − 𝑍𝑏−1)

𝑍∗ (

𝑍

𝑍′)

2

∗ (3

8∗ 𝜎𝑇)

∗ ∫ (1 + cos2( 𝜃))1

−1

∗ [F(x, Z′)]2𝑑(cos (𝜃)) and

F(𝐸, 𝑍) = 4 ∗ √2 ∗ 𝛼4 ∗ (𝑚𝑐2)72 ∗

𝜎𝑇ℎ

𝐸72

∗ 𝑆(𝐸, 𝑍) ∗ 𝑁(𝑍)

∗ (1 + ℱ(𝛽)) The 𝑍𝑒𝑓𝑓 and 𝜌𝑒 could be recovered from equation (1) using some model fitting algorithm. We implemented the equation (1) in python and applied Levenberg–Marquardt algorithm to fit the model to recover the 𝑍𝑒𝑓𝑓 and 𝜌𝑒 from four groups of attenuation in different energy ranges. Our model was validated by the NIST database [2]. RESULTS

Carbon (Zeff = 6, ρe = 6.799e+29 m-3 )

recovered Zeff 5.99 recovered ρe 6.784E+29 (m-3)

relative error: 0.163% relative error: 0.226%

Calcium (Zeff = 20, ρe = 4.6578e+29 m-3 )



Water (Zeff = 7.217, ρe = 3.34e+29 m-3 )



CONCLUSIONS We created an model to recover the effective atomic number ( 𝑍𝑒𝑓𝑓 ) and the electron density ( 𝜌𝑒 ) from attenuation information in different x-ray energy. This model could be used for material characterization of spectral CT system in the future. REFERENCES [1]. Jackson and Hawkes (1981) [2]. Berger, Martin J., et al. "XCOM: Photon cross sections database." NIST Standard reference database 8.1 (1998): 3587-3597.

43 Translational Research Poster A: Latham B, 10:45


DOWNSTREAM MICROFLUIDIC COLLAGEN CULTURE CHAMBER FOR ADVANCING MECHANISTIC UNDERSTANDING OF DIELECTROPHORETIC BEHAVIOR IN CELLS

Temple A. Douglas1, Philip Graybill2, Nastaran Alinezhadbalalami1, Nikita Balani1, Jaka Cemazar1, Eva M. Schmelz3, Rafael

V. Davalos1 1. Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences

2. Virginia Tech Department of Mechanical Engineering 3. Virginia Tech Department of Human Nutrition, Foods and Exercise

Corresponding Author: Temple Douglas, Email: [email protected] INTRODUCTION Dielectrophoresis is a technique that uses electric fields to induce a dipole in cells and elicits a force that can move them. We have developed a chip that utilizes insulator posts in the electric field to create local inhomogeneities in the electric field and selectively trap cells based on their biophysical phenotype, which we hypothesize correlates with cancer stage. Recently, we found that this effect is enhanced by shear-flow drag, which improves force balancing on cells and enhances their enrichment. Once cells have been separated, they maintain high viability and can be cultured. We are developing a downstream device that would allow for sterile culture of separated subpopulations in a collagen matrix. This matrix will maintain separate subpopulations with distinct biophysical characteristics and can be used for migration studies and chemotherapy testing. In the future, this technique can be used to improve theory of cellular bioelectric phenotype and can be used to improve personalized cancer treatment by testing treatment combinations on tumor subpopulations sorted by malignancy. RESULTS We found that at 30kHz and 350Vrms, late stage and late highly aggressive mouse ovarian surface epithelial (MOSE) cells were able to be separated. We found that as velocity increased, separation between the cell types was enhanced leading us to theorize that the drag force helps to

balance the DEP force. Using COMSOL, we developed a model of a device to separate cells from low conductivity DEP buffer, concentrate them, and mix them with collagen. A wall of small pores with higher net cross-sectional area than a secondary outlet allows DEP buffer to flow through, while cells roll along the edge of the porous wall into a collagen solution. Cells are collected in a serpentine channel, as shown. Cells coming off the DEP separation device flow in batches of 50 ul at ~36 ul/min, separated by 50 ul of cell-free buffer. The experiment in Figure 2 was performed to determine degree of mixing in the chip by using honey to modify the viscosity of cells in media to mimic low density uncured collagen.

CONCLUSIONS Using contactless dielectrophoresis, we can separate highly similar cancer cells. We are developing a downstream collagen matrix for biophysical study and to create a personalized diagnostic tool. ACKNOWLEDGMENTS This work was supported by NIH 5R21 CA173092-01, and CIT MF13-037-LS. REFERENCES T Douglas, J Cemazar, N Balani, D Sweeney, E Schmelz, R Davalos. Electrophoresis (Accepted manuscript). J Cemazar, T Douglas, E Schmelz, R Davalos. Biomicrofluidics (January 2016).

Figure 2: Left shows model of concentrator streamlines, right shows cell gradient in serpentine

channels of width 500 um.

Figure 1: Separation of MOSE cells at 30kHz, 350Vrms.



ASSESSING FUNCTIONAL CONNECTIVITY CHANGES INDUCED BY CIMT USING FNIRS

Amnah M. Eltahir1,2

, Stephanie A. DeLuca2, Brooks King-Casas

2, Stephen M. LaConte

1,2, and Sharon L. Ramey

2

1. Virginia Tech (Biomedical Engineering and Mechanics)


Corresponding Author: Amnah Eltahir, Email: [email protected]

INTRODUCTION

Constraint Induced Motor Therapy (CIMT) is an effective

treatment for hemiparetic cerebral palsy in infants1,2

.

However, the neurological changes that occur in children

receiving CIMT at this age range (6 months – 2 years old)

have not yet been quantified. This study aims to examine

the neural effects of CIMT with functional near infrared

spectroscopy (fNIRS) Advantages of fNIRS, include the

relative low-cost, portability, and non-invasiveness of the

modality as well as the ability to collect data while the

child is seated comfortably with the therapist.

METHODOLOGY

We collected data from three age matched, typically

developing children (single time point) and four

hemiparetic infants with right side impairments treated at

the VTCRI Neuromotor Clinic (pre- and post-treatment

time points). We obtained two “resting state” runs per

session, each four minutes in length. We used a NIRScout

system with 20 channels spanning left and right motor

cortices. We calculated laterality by implementing

singular value decomposition (SVD) to compare across

hemispheres. Equation 1 shows the laterality calculation

using difference in loading between left and right

channels and their singular values.

(1)

RESULTS

Figure 1 Example of SVD results: (top left) 20 channels;

(top right) first eigenvector; (bottom left) loading on each

channel; (bottom right) singular values

Figure 2 Results of laterality calculations.

We note that the typically developing children had left

hemisphere laterality, consistent with right-hand

dominance (although we did not assess handedness). We

also observed changes between pre- and post-therapy,

with a shift in laterality from the unimpaired hemisphere

to a more bilateral pattern of functional connectivity.

CONCLUSIONS

This method of assessing motor cortex connectivity

changes using fNIRS could elucidate the neurobiological

mechanisms of CIMT. These data are highly preliminary,

but suggest an increase in functional connectivity between

impaired and unimpaired hemispheres post-therapy.

ACKNOWLEDGMENTS

We would like to acknowledge the therapists in the VTCRI

Neuromotor Clinic (Mary Rebekah Trucks and Dory

Wallace) as well as helpful discussions and assistance from

Ben Stephens, Allison McKinnon, Christopher Anzalone and

Brennan Delattre.

REFERENCES

1. Gordon, A. M., et al. (2005). Methods of constraint-

induced movement therapy for children with hemiplegic

cerebral palsy: development of a child-friendly intervention

for improving upper-extremity function. Arch Phys Med,

86(4), 837-844.

2. DeLuca, S. C., et al. (2012). Constraint-induced

movement therapy (CIMT) for young children with

cerebral palsy: Effects of therapeutic dosage. J Pediatr

Rehabil Med, 5(2), 133-142.



PREPARATION AND OPTIMIZATION OF CHEMICALLY MODIFIED ALGINATES AS VEHICLES FOR

TARGETED DRUG DELIVERY

Kevin Enck1,2

, Surya Banks3, Victor Agwu

4, Aubrey Peeden

5, Hariom Yadav

6, Mark Welker

3, Emmanuel C. Opara

1,2

1. SBES (Wake Forest University Campus)

2. Wake Forest Institute for Regenerative Medicine (WFIRM)

3. Dept. of Chem. (Wake Forest University)

4. Biomedical Sciences Graduate School (Wake Forest University)

5. Biotechnology (Forsyth Tech)

6. Molecular Medicine (Wake Forest School of Medicine)

Corresponding Author: Kevin Enck, Email: [email protected]

INTRODUCTION

Alginate is a polysacharide that is used as a hydrogel for

encapsulation due to its bioinert and rapid crosslinking

properties. It is also used as an oral drug delivery vehicle

since it can immobilize and protect compounds from the

harsh stomach acid. We have chemically modified the

alginate polymer such that its hydrogel remains intact in

the low pH stomach acid conditions, but fall apart in the

more neutral pH of the gastrointestinal tract (GIT). This

allows for enhanced bioavailability of therapeutic agents

after release and absorption in the small intestine and for a

targeted delivery of other compounds such as probiotics

METHODOLOGY

The alginate has been modified using two different

methods. Method 1 involves covalently bonding

aminoethyl benzoic acid to the alginate backbone in order

to shift the pKa of the alginate. This increases the

sensitivity of the alginate polymer to basic pH.

Method 2 involves oxidizing the vicinal diol in the

alginate chain to an aldehyde. Then, the same amine from

method 1 is coupled to the aldehyde. This provides finer

control of the incorporation of the modifications. The

modified alginate was then mixed with lactobacillus casei

NCDC 298 and extruding through a 15-gauge needle into

a CaCl2 bath for crosslinking (gelation). The

hydrogel/bacteria beads were then placed into simulated

intestinal fluid (SIF) and simulated gastric fluid (SGF) to

mimic the GIT and stomach environment respectively.

Unmodified alginate was used as a control in this study.

RESULTS

The bacteria release from the alginate beads in simulated

intestinal fluid (pH 6.8) is shown in Figure 1. Beads

modified through method 1 released 15.5 ± 1% of the

bacteria within 30 minutes (p>0.05, n=3) and 92.1 ± 8%

within 3 hours (p<0.005, n = 3). Beads modified through

method 2 released 86.4 ± 16% of the bacteria within 30

minutes, which was higher than with method 1 (p<0.01

n=3) and 100% of the bacteria by 1 hour. Unmodified

alginate only released 25 ± 0.8% even after 3 hours

indicating the differences in the release profiles of the

beads from modified and unmodified alginates. The data

also illustrates the varying degradability of the alginate

based on the modification method.

Figure 1: Bacteria release in SIF (pH 6.8).

CONCLUSIONS

Based on these in vitro experiments, we have shown that

we can use modified alginate to encapsulate specific

compounds for oral drug delivery and protect them from

the harsh stomach acid while enabling controlled levels of

degradation to target different sections of the GIT which

will allow for multiple substances to be encapsulated for

different therapeutic purposes.

ACKNOWLEDGEMENTS

Wake Forest University Collaborative Pilot Grant and the

Wake Forest School of Medicine Center on Obesity,

Diabetes & Metabolism Pilot Grant for financial Support

of the Studies.



POSTURAL INFLUENCE ON THORACOABDOMINAL ORGANS OF 5TH, 50TH AND 95TH PERCENTILE MALE

SUBJECTS

James P. Gaewsky1, Katelyn Greene1, F. Scott Gayzik1, and Ashley A. Weaver1

1. Wake Forest School of Medicine, Department of Biomedical Engineering Corresponding Author: James P. Gaewsky: [email protected]

INTRODUCTION Changes in posture, such as sitting down or lying supine induce alterations of the skeleton and soft tissue that impact the morphology and position of organs within the abdominal region [1]. Understanding the extent of these postural changes on thoracoabdominal organs is crucial in the design of implantable medical devices and in device evaluation with computational human body modeling [2,3]. This study investigates postural changes to of thoracoabdominal organ volume and morphology through development and examination of 3D models of the 5th, 50th and 95th percentile male subjects in both the supine and seated postures. METHODOLOGY Medical images of the three males (5th, 50th, 95th percentile) were obtained in the form of supine and quasi-seated thoracic CT scans and both supine and seated (fully upright) thoracic MRI scans. The CT scan data was utilized to segment skeletal structures and then manually registered to the supine and seated MRI scan. The lungs, heart, kidneys, liver, and spleen were segmented in the MRI scans and the stereolithography (STL) structures were post-processed. This process created six 3D anatomical models (three subjects in supine and seated postures). Volumes of each organ were calculated from, while morphological changes were quantified by using a best fit alignment and 3D comparison of the reference object (supine organ) to the test object (seated organ), as shown in Figure 1a. Organ morphology changes were quantified by normalizing deviation results with organ volume. The normalized deviation value was calculated using the root mean square error (RMS) of the deviation between supine and seated organs according to Equation 1:

RMS/(Supine Organ Volume)1/3 (Equation 1) RESULTS The volumetric thoracoabdominal results indicated that there is no statistically significant change in volume

(p>0.05) between the supine and seated positioning among the 5th, 50th and 95th percentile males. The liver experienced the most significant change in morphology given its volume while the kidneys experienced the smallest change in morphology (Figure 1b).

(a) (b)

Figure 1: (a) Example of best-fit aligned supine and upright liver. (b) Normalized morphological deformation resulting

from posture change of five thoracoabdominal organs. CONCLUSIONS Quantifying the movement and morphology of the heart, lungs, and other soft tissue organs in relation to the skeletal structures in a seated versus supine posture has important implications in the design of medical devices such as implantable cardioverter defibrillators or pacemakers which require placement of leads within the heart chambers. Anatomical variation within the population must also be considered when designing devices for individuals of different sizes and shapes (i.e. 5th, 50th, versus 95th percentile). The results obtained suggest that anatomical variations along with postural changes and the corresponding organ morphology changes should be considered in future device designs and computational human body models. REFERENCES [1] Howes MK. Ann Adv Automot Med. (2013) 57: 209-224. [2] Lafon Y. J Biomech. (2010) 43: 1269-1278. [3] Hayes AR. Ann Adv Automot Med. (2013) 111-121.



A COMPUTATIONAL FLUID DYNAMICS MODEL OF THE INSECT RESPIRATORY SYSTEM

Joel Garrett1, Rafael Davalos1, Jake Socha1

1. Virginia Tech, Biomedical Engineering and Mechanics Corresponding Author: Joel Garrett, Email: [email protected]

INTRODUCTION Like all animals, insects depend on the internal movement of fluids to sustain life. Despite their small size, they use complex internal networks to effectively transport gases, liquids, and food through their bodies. Previously, we studied respiratory patterns in the Madagascar hissing cockroach (G. portentosa) to understand how abdominal pumping, tracheal compression, and spiracular valving are coordinated to produce airflows. Our prior work using simulations explored how these behaviors are used to regulate internal flows using a computational fluid dynamics simulation, and identified two key parameters for effectively driving unidirectional flow—valve phasing and valve duty cycle. This study continues to develop our understanding of respiratory airflow production in insects by introducing multi-phase actuation of the internal structures into the model. We also used a similar methodology to investigate flow creation in a simplified model, a channel subject only to external pumping induced via fluid-structure interaction. In addition to improving our knowledge about how the insect respiratory system produces bulk unidirectional flow, we aim to apply the results of this study toward developing low-power, small-footprint microfluidic systems for new engineered devices. METHODOLOGY We used COMSOL computational fluid dynamics software to develop a model of the insect respiratory system to investigate the effects of valve timing, valve duty cycle, actuation timing, and actuation phasing on the creation of bulk unidirectional flow. We varied these parameters through a range of values determined from previous animal experiments as well as purely theoretical states, and assessed the network performance by its ability to sustain net unidirectional flow. Additionally, we investigated the effects of fluid-structure interaction using the same software. A simple channel of dimensions similar to those found in the insect system was actuated using various pressures and timing schema, and we assessed flow creation from the simulation results.

RESULTS In a simplified insect tracheal network with single-phase actuation, we were unable to produce bulk unidirectional flow with any combination of parameters that did not include valves. In contrast, introducing a valve that was in phase with the actuation cycle produced unidirectional flow from anterior to posterior.

Figure 1: With no valves, a delayed-phase actuation produced net unidirectional flow over several cycles before reversing. Positive values are posterior flow.

In the simplified channel with fluid-structure interaction, we were able to produce very low unidirectional flow rates (5.2 mm/min) over several actuation cycles. This system is much less efficient than one that incorporates valves. However, a tapered channel design slightly improved flow rates. CONCLUSIONS Using these simulations in concert with what is known about the insect system in vivo, we have been able to confirm several of the fluid dynamic paradigms that work to drive unidirectional flow in the insect system, and other fluid networks of similar scale. We are currently using these simulations to develop a physical model so that our findings can be experimentally validated and applied toward microfluidic engineering projects. ACKNOWLEDGMENTS Funded by NSF 0938047 and 1558052



CHARACTERIZATION OF ELEVATED HEAD IMPACT EXPOSURE BETWEEN INDIVIDUAL YOUTH

FOOTBALL PLAYERS

Ryan A. Gellner1, Eamon T. Campolettano

1, Eric Smith

2, and Steven Rowson

1

1. Virginia Tech, Biomedical Engineering and Mechanics

2. Virginia Tech, Department of Statistics

Corresponding Author: Ryan Gellner, Email: [email protected]

INTRODUCTION

Football is among the most popular sports in the United

States at all ages, with the majority of its participants

being at the youth level. This team sport is also

associated with the highest incidence of concussion

among participants [1]. Head impact exposure varies in

magnitude and frequency between individual players

because of differences in position, amount of playtime,

athleticism, and level of play. Previous studies have used

aggregate analyses to characterize head impact exposure

in youth football players [2]. The objective of this study

was to characterize differences in head impact exposure

between individuals and identify characteristics

associated with elevated head impact exposure.

METHODOLOGY

Head impact data from 45 male youth football

participants (age 10.7 ± 1.1) from two recreational league

teams, Junior (age 9-11) and Senior (age 11-13), were

collected during a single season. Helmets of subjects

were instrumented with the Head Impact Telemetry (HIT)

System. For the purposes of this study, all accelerations

above 40 G were defined as high magnitude. All high

magnitude impacts were visually confirmed and

characterized during review of practice and game footage.

All statistical comparisons were made in either SAS or

Minitab. Significance was determined for p < 0.05.

RESULTS

Factors of team and position were found to be significant

(p ≤ 0.007) using the mixed procedure in SAS. Three

players were identified as having elevated head impact

exposure relative to their peers in this study. These

players were all Backs and played on the older team.

Overall, these three players (7%) accounted for over 194

impacts (31%) in practice alone (Figure 1). These players

exhibited similar elevated exposure across contact

practice drills and in games. Number of impacts caused

per practice directly correlated to number of impacts

received with a nearly one to one correlation (p < 0.0005).

Figure 1: Distributions of high magnitude accelerations

received and caused in practices by team and position. B

= Backs, L = Linemen, P = Perimeter. The large variance

in Senior Backs was due mainly to the three outliers.

CONCLUSIONS

Head impact exposure varied in this cohort of 45 youth

football players. This variance can be partially explained

by a player’s team and position, but a small number of

players still exhibited a greater head impact exposure than

their teammates, even of similar position. In this dataset,

players causing a majority of high magnitude head

impacts in practices also received a majority of head

impacts themselves. Coaching of proper technique should

target all players, even those who seem to be able to make

tackles without much coaching.

ACKNOWLEDGMENTS

The authors would like to thank the NIH-NINDS for

supporting this work under award number R01NS094410,

and the Blacksburg Recreational Football League players.

REFERENCES

[1] Lincoln, A.E. et al., Amer Jrl of Sports Med, 39:958-963,

2011.

[2] Cobb, B. R. et al., Ann Biomed Eng, 41:2463-2473, 2013.

49 Tissue Engineering Poster A: Latham B, 10:45


OPTIMIZATION OF HYDROGEL-BASED BIOINK PRINTABILITY USING RHEOLOGICAL PARAMETERS:

A SYSTEMATIC APPROACH

Gregory J. Gillispie1,2, Teng Gao2, Josh Copus2, James Yoo1,2, Anthony Atala1,2, and Sang Jin Lee1,2

1. Virginia Tech-Wake Forest, School for Biomedical Engineering Sciences 2. Wake Forest University, Wake Forest Institute for Regenerative Medicine

Corresponding Author: Greg Gillispie [email protected] INTRODUCTION Bioprinting is a promising technique in tissue engineering, but the dearth of suitable bioinks is frequently cited as a major limiting factor for the advancement of this technology.1 It is well known that the viscosity of a bioink has a direct impact on its printability. Highly viscous materials maintain their structure better, but also have decreased cell viability due to the high forces which are required for extrusion.1 However, complex viscosity is comprised of two discrete components, storage modulus (G’) and loss modulus (G”)

and their individual contributions to printability are unknown. METHODOLOGY For this study, gelatin and alginate were mixed at various concentrations to obtain hydrogels with a wide range of storage and loss moduli. These hydrogels were then evaluated for the quantitatively defined values of extrudability, structural integrity, and extrusion uniformity. Extrudability was defined by the pressure required to extrude the material and a mathematical model relating the G’ and G” to the required extrusion pressure was derived based on our data. Structural integrity was defined as the ability of the hydrogel to maintain its height as a printed tubular structure. Extrusion uniformity was defined as the straightness and smoothness of the individual lines of extrusion. RESULTS Increasing either the loss or storage modulus, and thereby the viscosity, increased the pressure required to extrude the bioink. Extrudability data was best fit to a first-order interactive model with two independent variables:

Pressure = 26.6 + 0.05G’ + 0.07G” – 0.0000035G’G” While neither loss nor storage moduli alone were excellent predictors of printability, a lower loss tangent (G”/G’) typically correlated with increased structural

integrity while a higher loss tangent correlated with increased extrusion uniformity. Hydrogels with a loss

tangent in the range of 0.3 to 0.6 exhibited an excellent compromise between structural integrity and extrusion uniformity.

Figure 1: Structural stability (left) and extrusion uniformity (right) as loss tangent increases from A-F.

CONCLUSIONS By making a simple measurement of the rheological properties (G’ and G”), the extrudability, structural

integrity, and extrusion uniformity of a bioink can be inferred. Using this approach, a variety of different formulations can be quickly and accurately evaluated for printability. Immediate future work will incorporate cell viability studies, further define printability with additional parameters, and expand the methodology to other hydrogels in order to determine the generalizability of these evaluation techniques. ACKNOWLEDGMENTS Funding provided by Wake Forest Innovations & NIH REFERENCES 1. Chimene, D. et al. (2016). Advanced Bioinks for 3D Printing: A Materials Science Perspective. Ann Biomed Eng, 44(6), 2090-2102.

Poster B: Latham B, 11:15 Biomaterials 50


MECHANICAL CHARACTERIZATION OF EMULSIFICATION POLYMERIZED KERATIN MICROPARTICLES

USING VARIED CROSSLINKING AGENTS

Aaron Giuffre’1, Marc Thompson

2, Mark Van Dyke

2

1. Virginia Tech, Electrical and Computer Engineering


Corresponding Author: Name, Email: [email protected]

INTRODUCTION

The application of microparticles in tissue engineering are

a well-documented and cost efficient method of

increasing the efficacy of drug delivery in the body.

Keratin as a building block for these materials is

advantageous due to its natural abundance in the body,

decreasing the likelihood of rejection. Emulsion

polymerization with a chemical cross-linker achieves a

fixed, spherical shape, increasing the particle surface area

and increasing the treatment’s loading capacity. The

successful application of loaded microparticles depends

largely on interactions within the body, hence their

mechanical and chemical properties become important

This study seeks to measure the effect of polymer and

cross-linker concentration on size, viscoelastic, and

degradation properties of keratin microparticles.

METHODOLOGY

Keratose (KOS) was extracted from human hair, via an

oxidation reaction. Paracetic acid breaches the hair

cuticle, which is then a followed by Tris base that

removes all protein within the strand. The KOS is purified

by washing samples encapsulated in dialysis tubing with

buffer solution to remove low molecular weight chains.

This sample is then manufactured into a dried network by

concentrating, freezing, and lyophilizing. This material is

made into solutions of varying concentrations either by

using water or phosphate buffer. Microparticles are

created using an oil emulsion process. A nonpolar oil

phase is stirred for a number of hours with a polar phase

of keratin solution along with a cross-linker of varying

concentration. This polymerizes the keratin solution into

spherical shape. A lyophilizing step stabilizes the

microparticle samples. Average particle size, expansion

rates in varying degrees of water and ethanol, gel

rheological properties, and rates of degradation via

enzymes and phosphate buffer were quantified across

microparticles produced with varying polymer and cross-

linker concentrations and pH. Size was quantified using

both scanning electron microscopy (SEM) and light

microscopy. Surface topography was observed via SEM.

Viscoelastic properties of microparticle gels were

measured by a rheometer. Degradation was quantified by

fluorescence read by a plate reader via loaded bovine

serum albumin fluorescein isothiocyanate (BSA-FITC).

RESULTS

Particle size, behavior in solution, and viscoelastic

properties were found to differ across production

variables like pH, polymer concentration, and cross-linker

concentration. This is unexpected and interesting, as the

various crosslinking agents used are very similar in length

and reaction chemistry.

Figure 1: Microparticle sample imaged via SEM

CONCLUSIONS

Manufacturing variables previously considered of minute

difference offer differing outcomes of product. This

expands the ability to fine tune and customize the keratin

microparticle system to various applications.

ACKNOWLEDGMENTS

The Davis Lab, The Nanoscale Fabrication and

Characterization Laboratory (NCFL).



JUMPING BEHAVIORS INCREASE GAP BRIDGING PERFORMANCE IN THE FLYING SNAKE CHRYSOPELEA

PARADISI

Michelle R. Graham1, Bruce Jayne2, Talia M. Weiss1, and Jake Socha2

1. Virginia Tech, Biomedical Engineering and Mechanics 2. University of Cincinnati, Biology

Corresponding Author: Michelle Graham, Email: [email protected] INTRODUCTION In arboreal habitats, the most direct route between two locations may involve spatial discontinuities. Snakes can navigate these gaps using gap-bridging behaviors, most commonly the cantilever, in which the snake extends itself into the gap, holding its body stiff. Some snakes also use dynamic lunges to increase their performance [1]. The flying snake Chrysopelea paradisi often initiates glides with a J-loop take-off [2], in which the snake forms a hanging curve with the anterior body and rapidly straightens to depart the branch. Such jumping, which is more energetic than lunging, might also be used to bridge gaps. In this experiment, our aim was to investigate how flying snakes use jumping in the context of gap bridging, and whether these behaviors increase the snake’s gap

bridging performance. METHODOLOGY

Figure 1: Snake with infrared (IR) reflective markers to

facilitate motion capture.

Six C. paradisi were marked with IR-reflective markers (Fig. 1) and recorded using a six-camera motion capture system (Vicon Motion Systems Ltd.) as they crossed gaps of increasing size between two branch-like cylinders. Video was also recorded from various perspectives. RESULTS We found that C. paradisi uses both lunging and jumping behaviors (Fig. 2), typically to cross gaps that they cannot span by cantilevering. The largest gaps were crossed exclusively by jumping.

Figure 2: Behavior used depends on gap size

The average factorial increase in crossable gap size when using dynamic behaviors was 2.10.18 times the largest gap size crossable with a cantilever alone (n=4 snakes, 196 trials). CONCLUSIONS C. paradisi do indeed use jumping behaviors in the context of gap bridging, and these behaviors enable them to cross larger gaps than they can by cantilevering. Hence, jumping in Chrysopelea may serve as a mechanism to increase locomotor effectiveness in patchy arboreal environments, and provide a locomotor rationale for jumping independent from gliding. ACKNOWLEDGMENTS Supported partially by NSF 1351322 and the New Horizons Graduate Fellowship Program. Facilities: W. Samuel Easterling Spline reconstructions: Isaac Yeaton. Experimental assistance: Corey Spohn, Adair Maynard. REFERENCES 1] Jayne and Riley, 2007, JEB. 210 (7) [2] Socha, 2006, JEB. 209 (17)



FAILED RIB REGION PREDICTION IN A HUMAN BODY MODEL DURING COLLISION EVENTS WITH

PRECRASH BRAKING

Berkan Guleyupoglu1,2

, Jeremy Schap1,2

, Matt Davis1,2


1. Wake Forest University School of Medicine

2. Virginia Tech – Wake Forest Center for Injury Biomechanics

Corresponding Author: F. Scott Gayzik, Email: [email protected]

INTRODUCTION

Road traffic injuries are a leading contributor of DALYs

(Disability Adjusted Life Years) lost [1]. Active safety

systems will play a large role in reducing the likelihood of

occupant injury but, such systems need to function in

concert with passive safety countermeasures,

underscoring the need for a method to evaluate the two

simultaneously. Human body models are ideally situated

to serve as this link. The purpose of this study is to investigate the differences in prediction between

deterministic and probabilistic methods of rib injury

prediction in the computational model.

METHODOLOGY

The GHBMC M50-O model was gravity settled in the

driver position of a generic interior equipped with an

advanced three point belt and airbag. Twenty-four

simulations were conducted with permutations for failure,

pre-crash braking system and crash severity. The

severities used were median (17 kph), severe (34 kph) and

NCAP (56.4 kph). Cases with failure enabled removed rib

cortical bone elements once 1.8% strain was exceeded.

Alternatively, a probabilistic framework found in

literature was used to predict rib failure. Both the

probabilistic and deterministic methods take into

consideration location (Anterior, Lateral, and Posterior).

The deterministic method is based on rubric that defines

rib Failed Regions (FR’s) dependent on a threshold for

contiguous failed elements. The probabilistic method

depends on age-based strain and failure functions.

RESULTS

Kinematics between both methods were similar (peak

∆Xhead = 0-17 mm; ∆Zhead = 1-4 mm; ∆Xthorax = 3-5

mm; ∆Zthorax = 1 mm). Seatbelt forces at the time of

probabilistic FR (PFR) initiation were lower than at

deterministic FR (DFR) initiation. The probabilistic

method for rib fracture predicted more failed regions in

the rib (an analog for fracture) than the deterministic

method in all but 2 cases. The FR patterns between

models are similar however there are differences that arise

due to stress let-off from element elimination that cause

other PFRs to appear where no DFR was predicted.

Figure 1. Failed region prediction counts for

probabilistic (black) and deterministic (orange). CONCLUSIONS

Both methods indicated similar trends with the addition of

precrash braking however there are tradeoffs. The DFR

method was more spatially sensitive and solved faster.

The PFR method consistently predicted higher failed

regions and has greater capabilities in post-processing.

ACKNOWLEDGMENTS

Work was supported by the Global Human Body Models

Consortium, LLC and NHSTA under GHBMC Project

No.: WFU-005. All simulations were run on the DEAC

cluster at Wake Forest University, with support provided

by Drs. David Chin and Timothy Miller.

REFERENCES

[1] Peden M. World Health Organization; 2014

53 Neuroengineering Poster A: Latham B, 10:45


MECHANOSENSITIVE RESPONSES OF ASTROCYTES TO SHOCK WAVE INSULT

Nora Hlavac1 and Pamela J. VandeVord1,2

1. Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 2. Salem Veterans Affairs Medical Center, Salem, VA

Corresponding Author: N. Hlavac, Email: [email protected] INTRODUCTION Astrocytes are the most abundant glial cell type in the brain. They serve primary support roles for neuronal survival and function while also exhibiting unique roles in neurocognitive functions1. These heterogeneous cells also play a complex role in brain injury pathologies. Much support exists to show that they are necessary for both repair mechanisms following injury but also enhancement of injury hallmarks, like neurogenic inflammation2. Astrocyte reactivity to insult is marked by both metabolic derangements and structural/morphological alterations. Despite much knowledge of the importance of astrocytes in the context of brain injury, little exists to explain the mechanisms associated with their reactivity. This is particularly true in the context of high injury rates, such as those attributed to shock wave exposure. The goal of this study is (1) to characterize astrocyte reactivity to mild severity thresholds and (2) to determine potential mechanotransduction targets for these changes. METHODOLOGY Primary astrocytes were isolated from Sprague-Dawley rat pups. Dissociated cells were cultured in monolayers in 6-well plates to 95-100% confluency before testing. Test groups were exposed to overpressure using an underwater shock wave generator. Groups were exposed to either 10 or 20 psi peak overpressure. This severity threshold is considered mild as assessed in an established animal model of blast neurotrauma3. Sham groups were prepped and treated equivalently, with exception of shock wave exposure. Post-testing, metabolic derangements were assessed up to 6 hours post exposure by quantifying total ATP production using a luciferase assay. RNA and protein were isolated using TriZol at 24 and 48 hours post exposure. RNA was used to conduct reverse transcription real-time PCR for gene targets of structural reactivity, adhesion, and inflammation. Protein analysis was conducted using Western blot to assess the parallel activation of potential mechanotransduction pathways that may ultimately influence the transcription alterations observed.

RESULTS Exposure to shock wave caused acute metabolic changes within cells that was manifest in fluctuations of total ATP production as compared to sham up to 6 hours post injury. Additionally, differential astrocyte activation occurred following exposure to 10 vs 20 psi peak overpressure. Structural reactivity included increased expression of glial fibrillary acidic protein at 48 hours post in the 20 psi group, whereas changes were not observed in the 10 psi group at either 24 or 48 hours. Moreover, there were significant changes in key molecular activators associated with mechanotransduction pathways in the 10 psi group at 24 hours with no significant difference in the 20 psi group. This suggests a potential for mechanosensitivity of astrocytes to such insults. This may also contribute to the differential expression of inflammatory and migratory genes. In particular, decreased expression of several pro-inflammatory cytokines was observed at 24 hours post exposure. Together these outcomes define a temporal scale to evaluate multiple aspects of astrocyte reactivity to shock wave. CONCLUSIONS Results indicated that astrocyte reactivity was influenced by peak overpressure, even at a mild threshold. Preliminary evidence suggests that activation of mechanotransduction pathways may be dependent on such thresholds as well. Future efforts will explore in more depth the links between mechanotransduction and the reactive hallmarks observed in this injury model. Overall, the goal is to decipher unknown mechanisms of astrocyte reactivity in order to define much needed therapeutic interventions for brain injury. REFERENCES 1. Sajja, VSSS, et al. 2016. Front Integr Neurosci, 10: 7. 2. Burda, JE, et al. 2016. Exp Neurol, 275: 305-315. 3. Hubbard, WB, et al. 2014. Biomed Sci Inst, 50: 92-99.


Figure 1: Variable Times as a function of walking speed.


QUANTIFYING LIMP USING TEMPORAL GAIT VARIABLES

Cherice Hughes-Oliver1, Daniel Schmitt2, Robin Queen1

1. Virginia Tech, Biomedical Engineering and Mechanics 2. Duke University, Department of Evolutionary Anthropology

Corresponding Author: Cherice Hughes-Oliver, Email: [email protected] INTRODUCTION Ankle osteoarthritis is a debilitating disease with patients reporting levels of impairment as high as those associated with end-stage kidney diseases, congestive heart failure, and end-stage hip arthritis [1, 2]. The objective of this study was to investigate a clinically-accessible method of identifying gait asymmetries (“limp”) and other changes

in patient gait associated with ankle osteoarthritis. We predicted that there would be differences in swing and stance time between affected and unaffected limbs. METHODOLOGY This is a secondary analysis of prospectively collected data on a group of 242 (110 men, 132 women) end-stage ankle OA patients. Only subjects with isolated unilateral involvement, no contralateral pain, and no rheumatoid arthritis diagnosis were included. Each subject completed at least four self-selected speed walking trials using an eight-camera motion capture system (Motion Analysis Corporation). Heel-strike and toe-off timings were exported from Visual3D. Stride time, swing time, stance time, and double support time were calculated in Matlab. Each variable was averaged across steps for a single trial and then across trials for each subject, and for each limb. An ANCOVA comparing sex and limb (affected and unaffected) and co-varying for walking speed was run for each variable using JMP Pro 13 (α = 0.05). RESULTS Men had higher stride, swing, and stance times than women (Fig 1), and swing time was higher on the affected limb and stance time was higher on the unaffected limb. This limb difference may function as a compensatory pattern due to ankle pain on the affected limb. Effects of walking speed were seen in stride, stance, and double support times but not in swing time. It is unclear whether the sex-specific effects observed in this study are present in healthy populations or are a result

of sex-specific pain coping compensatory mechanisms. Similarly to our results, Valderrabano et al found no inter-limb differences in stride time [3]. Nuesch, et al observed no decrease in stance time as a percent of stride time [4], which disagrees with our findings. Conversely, Shih et al found decreased stance time and increased swing time on the affected limb, which agrees with our findings [5]. Shih et al also saw an increase in double support time on the affected limb, which our results did not reflect. CONCLUSIONS It is possible that temporal variables, which are much easier to collect than 3D motion capture data, can be used to quantify limp and gait compensation; walking speed could play a large role in this quantification, along with limb-specific differences between swing and stance times. These results demonstrate the value of using these simpler variables to evaluate compensation. REFERENCES 1. Saltzman, C.L., et al. J Bone Joint Surg Am, 2006. 88(11): p. 2366-2372. 2. Glazebrook, M., et al. J Bone Joint Surg Am, 2008. 90(3): p. 499-505. 3. Valderrabano, V., et al. Clin Biomech, 2007. 22(8): p. 894-904. 4. Nuesch, C., et al. Clin Biomech (Bristol, Avon), 2012. 27(6): p. 613-8. 5. Shih, L.-Y., J.-J. Wu, and W.-H. Lo, Foot & Ankle International, 1993. 14(2): p. 97-103.


Table 1. Critical Buckling Loads

0 10 20 30 40 50 600

5

10

15

20

25

30

Displacement (mm)

Forc

e (N

)

22Gauge

24Gauge

25Gauge

27Gauge

Figure 3. Buckling Test Force-Displacement Data

Figure 2. Buckling Mode Figure 1. Testing Fixture


BUCKLING BEHAVIOR OF SPINAL ANESTHESIA NEEDLES

Tessa Hulburt1, Jessica M. Booth

2, Peter Pan

2, Philip J. Brown

1

1. Biomedical Engineering, Wake Forest Baptist Health

2. Anesthesiology, Wake Forest Baptist Health

Corresponding Author: Tessa Hulburt, Email: [email protected]

INTRODUCTION

Small gauge spinal anesthesia needles are used clinically

to reduce the most common complication of a spinal

anesthesia administration procedure, headache due to loss

of cerebral spinal fluid. Though effective in reducing

headache prevalence, use of smaller gauged needles has

increased procedural complications due to needle

buckling and fracture. While a mechanical or clinical

understanding of needle deviation and needle fracture

have been documented, needle buckling behavior is not

well understood [1, 2]. The goal of this study was to

quantify the buckling behavior of spinal anesthesia

needles with respect to the relative contribution of needle

brand, gauge, and tissue depth.

METHODOLOGY

A spinal anesthesia administration procedure was

simulated to induce buckling. In the testing fixture

(Figure 1), the needle was thread through an introducer

and gripped by the fixture. A uniaxial MTS actuator

advanced the needle into a 50mm depth ballistics gelatin

tissue surrogate to induce buckling. Force-displacement

data was measured using a 500N load cell. Buckling tests

were performed with 22, 24, 25 and 27 gauge Gertie Marx

pencil point spinal anesthesia needles (n=10).

RESULTS

Buckling test force-displacement data (Figure 3) showed

consistent results within testing groups of different needle

gauges, verifying that the testing methodology was

repeatable. The needles buckled in an “s” shape (Figure

2), referred to as second-mode buckling. This suggested

that the gelatin tissue surrogate provided some lateral

support. Overall, it was seen that the critical buckling load

(the maximum load that could be withstood by the needle

before buckling) was larger for larger diameter needles

(Table 1). The strengths of the smaller 24G, 25G and 27G

needles were more closely grouped together, producing

average buckling loads within approximately 4N of each

other. The critical buckling load of the 22G needle

surpassed the smaller gauges by approximately 10N.

Using an independent t-test, average critical buckling load

for the different needle gauges were found to be

statistically significantly different with p-values of less

than 0.0001.

CONCLUSIONS

Needle gauge contributed to needle strength as shown by

trends among measured critical buckling loads. The

contribution of tissue depth and needle brand to needle

strength, gelatin tissue surrogate ability to aid in

resistance to buckling and how the needles plastically

deform after buckling will be investigated in the future.

REFERENCES

[1] Martinello et al., Journal of Clinical Anesthesia, 2017.

[2] Sitzman et al., Anesthesia & Analgesia, 2017.

Needle

Gauge

Average Critical

Buckling Load (N)

Standard Deviation of

Critical Buckling Loads

22G 27.70 1.078

24G 17.44 0.8472

25G 13.36 0.4148

27G 9.38 0.4142



FLUID SHEAR STRESS IMPACTS OVARIAN CANCER CELL VIABILITY, SUBCELLULAR ORGANIZATION,

AND INDUCES MALIGNANT PHENOTYPES

Alexandra R. Hyler1, Nicolaas C. Baudoin2, Mark A. Stremler1, and Daniela Cimini2, Rafael V. Davalos1, Eva M. Schmelz1

1. VT-WFU School of Biomedical Engineering, Virginia Tech, Blacksburg, VA 2. Department of Biological Sciences and Biocomplexity Institute, Virginia Tech, Blacksburg, VA

Corresponding Author: Alexandra R. Hyler, Email: [email protected] INTRODUCTION All cells exist in a physiologic environment that is determined by chemical and physical factors; in concert, these factors direct tissue growth, organization and function but also can cause or contribute to diseases such as cancer. Epithelial ovarian cancer (EOC) is the fourth most deadly cancer, with a 5-year survival rate below 30% if diagnosed after the cancer has spread beyond its boundaries.1 Metastatic ovarian cancer cells exfoliated into the peritoneal cavity are exposed to continual fluid shear stress (FSS) due to gastrointestinal and diaphragm movements, abdominal pressure, gravity, and ascites build-up in advanced stages of ovarian cancer. 2

We hypothesized that relatively small values of FSS induced shear stress will differentially affect the various stages of disease. To test this hypothesis, we imposed FSS onto mouse ovarian epithelial (MOSE) cells3 to mimic physiologically relevant fluid movement of the peritoneal cavity.4 METHODOLOGY We estimated the shear stress for our system to be ~1.37-1.99 dyne/cm2 which is physiologically relevant.4 Three stages of disease were investigated: MOSE-E (benign), MOSE-L (slow-developing disease, malignant), MOSE-LTICv(fast-developing disease, malignant). Cells were seeded and placed immediately (-imm-) onto or allowed to adhere (-adh-) before placement onto a Lab Rotator. Cell viability (hemocytometer count), spheroid formation (imaging), cytoskeleton structure (indirect immunofluorescence), nuclear morphology (CREST staining) and chromosome counts (metaphase spreads) were assessed. RESULTS FSS affected cell viability differentially in MOSE cells representing different disease stage. In particular, MOSE-Eadh and MOSE-LTICv-adh cells appeared more resistant to FSS after adherence whereas all stages immediately

exposed to FSS responded with significant cell death. FSS induced spheroid formation in tumorigenic (MOSE-L and MOSE-LTICv) cells. These spheroids were free floating in both adherent and immediate MOSE-L cells, but the MOSE-LTICv-adh spheroids reattached and grew out, a capacity associated with invasiveness. We also observed FSS-induced changes in cytoskeleton organization such as indicated significant actin disorganization, and the appearance of protrusions. In conjunction with cytoskeletal changes, we observed the emergence in all cell lines of multi-lobed nuclei after FSS exposure, which was particularly drastic in benign cells. This result paralleled an observation of an increase in all cell lines of CREST-positive micronuclei suggested that FSS may cause errors in chromosome segregation, so lastly, we investigated chromosome number in MOSE-E cells. Indeed, FSS dramatically increased the fraction of benign MOSE-E cells with near-tetraploid chromosome numbers.

CONCLUSIONS Overall, our results indicate that low magnitudes of continual FSS significantly and differentially affect MOSE cells of various stages of progression. In particular, benign cells that survive under FSS display phenotypic changes (increased multi-lobed nuclei, CREST-positive micronuclei, and chromosome number) that resemble more aggressive stages of disease. Future work will employ a physiologically relevant testing platform to investigate the interaction of biomechanical and molecular interactions in ovarian cancer metastasis. ACKNOWLEDGMENTS This work was supported by NSF IGERT Grant 0966125 and seed funds from the Center for Engineered Health (ICTAS). REFERENCES

1. J. Berntsson, et al. J Ovarian Res, 2014, 7, 26. 2. D.S. Tan, et al. Lancet Oncol, 2006, 7, 925-34. 3. Roberts PC, et al. Neoplasia. Oct 2005;7(10) 944-956 4. Even-Tzur, N., et al. Biophysical J. Sept 2008;95(6) 2998-

3008.



SKULL DEFLECTION EFFECTS ON BRAIN TISSUE RESPONSE USING FINITE ELEMENT SIMULATION

Derek A. Jones1,2, Jillian E. Urban1,2,3, Ashley A. Weaver1,2, and Joel D. Stitzel1,2

1. Virginia Tech-Wake Forest University Center for Injury Biomechanics 2. Wake Forest School of Medicine

3. Clinical and Translational Science Institute Corresponding Author: Derek A. Jones, Email: [email protected]

INTRODUCTION Traumatic brain injuries (TBIs) remain a large public health concern, with an estimated 2.8 million people in the United States alone sustaining a TBI annually, of whom 56,000 die [1]. Despite the development of finite element (FE) models of the head, the implications of skull deflection on the risk of brain injury in blunt trauma is not well understood. There is currently a lack of injury metrics which quantify skull deflection; therefore, the objective of this study was to replicate experimental head impacts using the head from the Global Human Body Models Consortium 50th percentile male occupant model (GHBMC M50-O v4.5), develop a skull deflection injury metric, and evaluate the relationship between the skull deflection and tissue-based brain strain [2]. METHODOLOGY Three experimental test series were replicated using simulation techniques [3-5]. During each simulation, every brain element’s strain tensors were output at 0.1 ms

intervals. Similarly, the inner skull surface nodal displacements with respect to the head center of gravity were output at 0.1 ms intervals.

The brain elements were then grouped based on proximity to the impact site to define coup and contre-coup regions of interest (ROIs). A maximum skull deflection metric was developed for skull deflection characterization. Correlations between the skull deflection injury metric and coup ROI elemental strain measures were evaluated. Differences in the distribution of coup and contre-coup strain within single impacts were evaluated. RESULTS Nine experimental tests were simulated in this study. Input kinetic energy, impactor geometry, boundary conditions, and impact location from the respective experimental test were replicated in each simulation. Skull deflection ranged from 1.24-4.98 mm. 95th percentile coup and contre-coup maximum principal strains ranged from 0.02-0.08 and 0.008-0.048,

respectively. Coup strain was positively correlated to the skull deformation metric. There were statistically significant differences between coup and contre-coup 95th percentile maximum principal strain.

0.00

0.02

0.04

0.06

0.08

0.10

Max

imum

Prin

cipa

l Stra

in

Coup Contre-Coup

Figure 1: 95th percentile MPS in the coup and contre-

coup ROIs for matched impacts.

CONCLUSIONS Replicating cadaveric testing of heads allows for more in depth analysis into brain injury metrics that are unable to be studied from PMHS alone. Specifically, shape profiles of inner skull deformation were able to be characterized and compared to brain tissue response. A positive linear relationship was found between the skull deformation metrics and underlying brain strain, which is the likely source for focal brain injury. Thus, the skull deformation metric developed in this study will lead to a better understanding of the mechanistic relationship between skull deformation and head injury. ACKNOWLEDGMENTS Funding: National Highway Traffic Safety Administration REFERENCES [1] Taylor et al. MMWR Surveill Summ, 2017. [2] Gayzik et al. Ann Biomed Eng, 2011. [3] Allsop et al. SAE Technical Paper 0148-7191, 1991. [4] Cormier, J. Biomechanical Eng., 2011. [5] Yoganandan, J Neurotrauma, 1995.



UPPER EXTREMITY INJURIES IN SIDE-IMPACT MOTOR VEHICLE COLLISIONS

Mireille E. Kelley1,; Jennifer W. Talton2; Andrew O. Usoro3; Ashley A. Weaver1; Eric R. Barnard4; Anna N. Miller5

1. Virginia Tech-Wake Forest University, Center for Injury Biomechanics 2. Wake Forest School of Medicine, Department of Biostatistical Sciences

3. Massachusetts General Hospital, Department of Orthopedic Surgery 4. Loyola University Medical Center, Department of Orthopedic Surgery and Rehabilitation

5. Washington University School of Medicine, Department of Orthopedic Surgery Corresponding Author: Mireille E. Kelley, Email: mekelley@wakehealth,edu

INTRODUCTION Side-impact motor vehicle collisions (MVC) represent a significant burden of mortality and morbidity caused by automotive injury [1]. Upper extremity (UE) injuries can result in disability and other long-term effects on functional outcome [2]. The objective of this study was to characterize UE injuries in side-impact MVCs. METHODOLOGY Crash Injury Research and Engineering Network (CIREN) data obtained from 1998 to 2012 were used to evaluate UE injuries in side-impact crashes. Inclusion criteria were that the occupants must be at least 16 years old and first row drivers and passengers only. Those with unknown or missing crash information were excluded. Side-impact crashes were defined as a PDOF between 60° and 120° or 240° and 300°. Injuries were stratified by type, anatomic location and Abbreviated Injury Scale (AIS) severity. Occupant variables (age, height, weight, BMI) and crash variables (ΔV, CMAX, and injury source)

were included in the analyses. Statistical analysis of the data included descriptive statistics and bivariate regression analyses. RESULTS There were 917 upper extremity injuries analyzed and the most common injury type was soft tissue injury (72.3%). The majority of fractures were to the clavicle (41.5%). Clavicle fractures were associated with the lowest mean occupant BMI and significantly lower mean BMI than injuries to skin/external and to the hand/wrist (p=0.04 and p=0.04, respectively). There were significant differences in mean ΔV among injury types and locations (p=0.03 and p=0.03, respectively). There were also significant differences in mean CMAX among injury types and locations (p=0.005 and p=0.001, respectively). The door was the most common injury source for all injuries (Figure 1). The B-pillar, door, and steering

wheel/assembly resulted in significantly higher odds of an AIS 2+ injury compared to other injury sources.

0

50

100

150

200

250

300

350

Air bag Belt B-pillar Door Flyingglass

IP/kneebolster

Other Seat Steering Unknown

Num

ber o

f UE

Inju

ries

AIS 1 AIS 2 AIS 3

Figure 1: The injury sources for all UE injuries stratified

by AIS severity. CONCLUSIONS This study provides insight into the injury causation scenarios of UE injuries in MVCs. Clavicle fractures were the most common fracture type and associated with high CMAX. Due to the high number and severity of UE injuries resulting from contact to the door, we recommend further study on door structure safety. Mitigating UE injuries in MVCs will potentially improve functional outcomes and reduce the human and economic costs. ACKNOWLEDGMENTS Funding was provided by the National Highway Traffic Safety Administration under Cooperative Agreement Number DTN22-10-H-00294. Views expressed are those of the authors and do not represent the views of the sponsors. REFERENCES [1] Li et al., Accid Anal Prev. 2001. [2] Conroy et al., Injury. 2007.



HOW TEMPERATURE INFLUENCES THE VISCOSITY OF HORNWORM HEMOLYMPH

Melissa C. Kenny1, Matthew N. Giarra2, and John J. Socha1

1. Virginia Tech, Department of Biomedical Engineering and Mechanics 2. Virginia Tech, Department of Mechanical Engineering

Corresponding Author: Melissa Kenny, Email: [email protected] INTRODUCTION The primary function of the insect circulatory system is to circulate nutrients, hormones, and waste via hemolymph transport. Hemolymph is composed primarily of water with added inorganic salts, proteins, lipids, and cells [1]. Although the composition and function of hemolymph is known, many physical properties including viscosity are unknown, which are crucial to understanding the behavior of the hemolymph for circulation and flow. As ectotherms, the physiology of insects is significantly affected by environmental temperatures [2], but the influence of temperature on hemolymph viscosity has not been studied. Here, we measure the viscosity of insect hemolymph for the first time, specifically addressing the question, how does viscosity of insect hemolymph change with temperature? METHODOLOGY We tested the hemolymph of Manduca sexta larvae [3]. Measurements were taken using a cone and plate viscometer (Brookfield Engineering DV-II+ Pro) attached to a water circulator (Lauda RE206) to control temperature. To minimize oxygen-induced clotting, experiments were performed in a sealed glove box flooded with dry nitrogen gas. All experiments were performed at nearly constant shear rates of 450-460.8 s-1. Hemolymph was extracted via a small incision on the ventral surface between the 2nd and 3rd set of prolegs. Additional trials were conducted on the plasma, which was separated from the hemolymph via centrifuge (Miulab Mini Centrifuge, Mini-10k+). For each trial, the viscosity over time was recorded and data were included using a running window standard deviation (<0.05 SD) criterion to identify steady values. RESULTS The viscosities of whole hemolymph and plasma at 20°C are 2.85 ± 0.21 cP and 1.84 ± 0.12 cP, respectively. Whole hemolymph viscosity decreased with increasing temperature, showing an average decline from 11.08 to 1.83 cP from 0 °C to 45 °C (Fig. 1).

Figure 1: Viscosity vs temperature for whole

hemolymph, plasma, and water. Bars indicate standard deviation of the mean.

CONCLUSIONS Insect hemolymph has a significantly higher viscosity than water, particularly at temperatures lower than 20 °C. This difference may result from the added inorganic salts, nutrients, hemocytes, and other components [1]. Across temperatures of 0 to 45 °C, viscosity of whole hemolymph and plasma changed by factors of 6.05 and 3.38 X, respectively. Water, by contrast, only experiences a 3.01 X change over the same range. Increases in hemolymph viscosity with decreasing temperature may represent an underappreciated factor in the reduction of activity, locomotion, feeding, and other behaviors [2,3]. ACKNOWLEDGMENTS We thank Ellen Granata, Patrick Rogers, Amanda Barnes, Brittany Horton, and Katie Johnston for experimental help. Supported by NSF 1558052 and 1301037. REFERENCES [1] Chapman. “Insects: structure and function” In Print, 2013. [2] Clark & Worland. J Comp Physiol B, 178, 2008. [3] Casey. Ecology, 57(3):485-497, 1976.

Poster B: Latham B, 11:15 Tissue Engineering 60


ENGINEERING THE GUT-LIVER-BRAIN AXIS TO INVESTIGATE CHEMICAL TOXICITY

Anjaney Kothari1, Rebekah Less1 and Padma Rajagopalan1, 2, 3

1. School of Biomedical Engineering and Sciences 2. Department of Chemical Engineering

3. ICTAS Center for Systems Biology of Engineered Tissues (ISBET) Virginia Tech, Blacksburg, VA

Corresponding Author: Anjaney Kothari, Email: [email protected] INTRODUCTION Communication between the gut, liver and brain affects many physiological functions such as glucose homeostasis, inflammation and response to xenobiotics [1]. Xenobiotics get metabolized in the gut and liver, and can reach the brain systemically. We were motivated to develop an in vitro model to recapitulate the physiological response to xenobiotic toxicity. For our preliminary work, we investigated acetaminophen (APAP), the active ingredient in Tylenol®. APAP overdose causes liver failure, increased ammonia in the blood, and subsequently, brain disorders such as hepatic encephalopathy [2]. We have developed a multi-organ system to obtain insights into such phenomena. METHODOLOGY Rat jejunum explants were inverted and cultured on PDMS rods in Transwell® inserts. Primary rat hepatocytes were isolated and cultured in a collagen sandwich (CS) model. CS models and jejunum explants were integrated at 7h and treated with 20mM APAP (LC50 for rats). Conditioned media (CM) collected from treated and untreated cultures at 24h was added to DI-TNC1 rat astrocyte cultures for gut-liver-brain integration and reactive oxygen species (ROS) were visualized. RESULTS

Figure 1: Gut function, viability before/after integration

Gut explants maintained enterocyte function and viability after integration (Fig 1) and hepatocytes maintained urea production and viability (Fig 2). When rat astrocytes were cultured in CM from integrated gut-liver models treated

with 20mM APAP, increased ROS was observed (Fig 3), which may be due to increased ammonia levels.

Figure 2: CS function, viability before/after integration

Figure 3: ROS in astrocytes cultured in CM

CONCLUSIONS Integration of gut and liver does not affect their individual markers significantly. However, CM from APAP-treated integrated gut-liver cultures elicits a markedly higher toxic response in astrocytes. We were able to recapitulate the effects of APAP on the gut-liver-brain axis in vitro. ACKNOWLEDGMENTS We acknowledge the National Science Foundation (NSF: CBET1510920), Computational Tissue Engineering IGEP at Virginia Tech, and ISBET for funding. REFERENCES 1. Wang et al. Nature 452.7190 (2008): 1012-1016. 2. Graham et al. Inflammopharmacology 21.3 (2013):

201-232.



INTEGRATED IN VITRO GUT-LIVER MODEL FOR THE INVESTIGATION OF FIRST PASS METABOLISM

Rebekah Less1, Anjaney Kothari

1, Padma Rajagopalan

1, 2, 3

1. School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg VA, 24060

2. Chemical Engineering, Virginia Tech, Blacksburg VA, 24060

3. ICTAS Center for Systems Biology of Engineered Tissues, Virginia Tech, Blacksburg VA, 24060

Corresponding Author: Rebekah Less, Email: [email protected]

INTRODUCTION

Communications between the gastrointestinal (GI) and

liver modulate multiple metabolic functions,

inflammatory responses and the biotransformation of

chemicals [1]. Despite the known communications

between the GI and the liver in vivo, there have been

extremely limited efforts to integrate these organs into a

single system in vitro. In addition to understanding the

communication mechanisms between these two organs,

the effect of drug/toxicant absorption, metabolism, and

toxicity is also critical. Ethanol (EtOH) metabolism and

toxicity was investigated in these in vitro models.

EtOH-induced toxicity can have severe consequences on

the GI and the liver [2]. In the GI, increased bacterial

overgrowth has been reported along with increased gut

permeability. In the liver, excessive ethanol consumption

can lead to fibrosis.

METHODOLOGY

We describe a novel integrated GI-liver model that is

designed by integrating a primary rat ileum explant with a

primary hepatocyte liver model. Primary ileum tissues

were surgically excised from rats. These explants were

cultured in oxygenated culture medium that contained

antibiotics. EtOH was administered over 100-200mM

concentration range. These concentrations ranged from

sub-lethal to 50% lethal concentration (LC50). All models

were cultured over a 24h period.

RESULTS

Ileum explant models (Figure1A) and CS models

(Figure1B) were used as the intestine-only and liver-only

controls, respectively.

Figure 1: Pictorial representations of the in vitro cellular

models utilized to evaluate EtOH toxicity.

The Integrated model (Figure1C) was developed as the

primary model to investigate the communication and

toxicity of an integrated gut-liver system.

Protein content of the explants were monitored

throughout the culture period to ensure no degradation

occurred. Results show no statistical decrease in protein

throughout the 24h culture period (data not shown).

Figure 2: A) Hepatic protein content and B) hepatic ALP

content in integrated models

After ensuring the explants were not degrading

throughout the culture period, explants were integrated

with CS models. No detrimental effect was observed after

integration. EtOH treatment of integrated models at LC50

resulted in a 25% decrease in hepatic ALP. This is

compared to a 56% decrease in hepatic ALP of CS

models alone (Figure 2A). This could suggest a

protective effect of the intestine on hepatocytes. This

hypothesis is further supported by hepatic protein. In

integrated cultures, there is a 7% decrease in hepatic

protein after LC50 EtOH treatment, however in the CS

models, this decrease is 22% (Figure 2B).

CONCLUSIONS

Results show ileum explants can be cultured for 24h

without significant degradation. Furthermore, the

integration of the intestine with the liver in vitro could

result in a protective effect against EtOH-induced

toxicity.

REFERENCES

[1] Zeuzem, Stefan. International journal of colorectal

disease 15.2 (2000): 59-82.

[2] Stål, Per, and Rolf Hultcrantz. Journal of hepatology

17.1 (1993): 108-115.

A. B.



IRREVERSIBLE ELECTROPORATION FOR THE ABLATION OF PANCREATIC

MALIGNANCIES: A PATIENT-SPECIFIC METHODOLOGY

Melvin F. Lorenzo BS1, Eduardo L. Latouche MS1, Michael B. Sano PhD2,3, Robert C. G. Martin II MD PhD4, Rafael V. Davalos PhD1

1. Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 2. Radiation Oncology, Stanford University School of Medicine, Stanford, California

3. UNC/NCSU Joint Department of Biomedical Engineering, Chapel Hill, North Carolina 4. Surgery, Division of Surgical Oncology, University of Louisville, Louisville, Kentucky

Corresponding Author: Rafael V. Davalos, Email: [email protected] INTRODUCTION Irreversible electroporation (IRE) is a minimally invasive focal ablation technique used to nonthermally ablate soft tumor tissue [1]. Due to its nonthermal mechanism of ablation, IRE can be safely implemented in unresectable tumors located near critical vasculature [2]. Although effective, widespread use of IRE is hindered by challenges associated with treatment planning protocols, real-time feedback for monitoring lesion size, and the total duration of treatment. METHODOLOGY In order to address some of these issues, our group established a pre-treatment planning methodology for IRE procedures (Figure 1) in locally advanced pancreatic cancer (LAPC), in compliance with HIPAA and hospital IRB approval. Also, a real-time resistance measurement system is proposed to track for a change in resistance of 28 Ω, marking a clinical endpoint for IRE [3]. RESULTS

Figure 1: Patient specific 3D geometry of the pancreas (green), tumor (blue), and vasculature (red). This

geometry was reconstructed from stacked images of the

patient’s anatomy. The electric field distribution after 100 pulses is shown.

Changes in maximum temperature at the midpoint between electrode-pairs is comparable between the experimental procedure (10.3℃) and the proposed model (8.2 ℃). By implementing the proposed resistance measurement system, 210 ± 26.1 (mean ± standard deviation) fewer pulses were delivered per electrode-pair. CONCLUSIONS The proposed physics-based pre-treatment plan through finite element analysis and system for actively monitoring resistance changes can be paired to significantly reduce ablation times and risk of thermal damage during IRE procedures for LAPC. ACKNOWLEDGMENTS Virginia Center for Innovative Technology, Grant number: MF13-034-LS; CureAccelerator (Cures Within Reach), Grant number: PUJFSANY REFERENCES [1] R. V. Davalos, L. M. Mir, and B. Rubinsky,

“Tissue ablation with irreversible

electroporation,” Ann. Biomed. Eng., vol. 33, no. 2, pp. 223–231, 2005.

[2] E. Maor, A. Ivorra, J. Leor, and B. Rubinsky, “The Effect of Irreversible Electroporation on Blood Vessels,” Technol. Cancer Res. Treat., vol. 6, no. 4, pp. 307–312, 2007.

[3] E. L. Latouche, M. B. Sano, M. F. Lorenzo, R. V. Davalos, and R. C. G. Martin, “Irreversible

electroporation for the ablation of pancreatic malignancies: A patient-specific methodology,” J. Surg. Oncol., no. January, pp. 1–7, 2017.



CELL TYPE-SPECIFIC MOUSE BRAIN METHYLOMES PROFILED USING AN ULTRALOW-INPUT

MICROFLUIDIC DEVICE

Sai Ma1, Zhixiong Sun

2, Chen Sun

1, Travis W. Murphy

3, Hehuang Xie

2,4, Chang Lu

2

1. School of Biomedical Engineering and Sciences, Virginia Tech

2. Department of Biological Sciences, Virginia Tech

3. Chemical Engineering, Virginia Tech

4. Biocomplexity Institute, Virginia Tech

Corresponding Author: Chang Lu, Email: [email protected]

INTRODUCTION

Epigenetics refer to any process that alters gene activities

without changing the DNA sequence. Previous studies

have demonstrated that epigenetic regulation, such as

DNA methylation, plays a critical role in many biological

procedures, such as embryo development and learning

process. Genome-wide study of dynamics of DNA

methylation at single-base resolution provides a

comprehensive understanding of methylome confi-

guration. Bisulfite sequencing is regarded as the gold-

standard technology for analyzing DNA methylation. This

technology is based on the different consequences after

cytosine and 5-methycytosine (5-mC) treated with sodium

bisulfite. However, conventional protocols required more

than 300 ng DNA due to the significant sample loss

during bisulfite treatment (up to 96%). This limits its

application for studying precious samples and

understanding the underlying heterogeneity of clinic

samples. To broaden the applications of bisulfite

sequencing, it is necessary to develop ultrasensitive tools

for epigenomic study, particularly DNA methylation

analysis. We reported the first microfluidic DNA

methylation assay at genome-wide scale and single-base

resolution with >3 orders of magnitude higher sensitivity

than conventional protocols.

METHODOLOGY

We demonstrate a microfluidic technology, referred to as

MIcrofluidic Diffusion-based RRBS (MID-RRBS), for

low-input (down to 0.3 ng DNA) assay with high bisulfite

conversion efficiency and high coverage of CpGs. We

used a diffusion-based reagent swapping approach for

multi-step treatment of DNA on the microfluidic

platform. Our protocol preserved substantially more

amplifiable DNA than conventional bisulfite treatment

10, 24-26 while achieving high conversion rate.

RESULTS

We mapped methylomes of a cell line (GM 12878),

neurons and glia isolated from mouse cerebellums. Our

protocol yielded data that were heavy in CpGs of high

coverage (2.0-2.6 million CpGs with ≥1×, 1.3-1.8 million

CpGs with ≥10× coverage with 0.3 to 10 ng starting

DNA, respectively). MID-RRBS technology allowed

differentiation of methylomic landscapes of neurons and

glia from mouse cerebellum, generating insights into cell

type-specific features and their relationships to gene

expressions.

CONCLUSIONS

Our MID-RRBS technology offers capability for low-

input profiling of DNA methylomes on a microfluidic

platform. The diffusion-based reagent exchange method

permits loading/releasing of various small-molecule

reagents without substantial loss in the DNA amount.

Such approach facilitates conducting a complex molecular

biology treatment in a microfluidic device with a simple

structure. In principle, similar approaches can be applied

to WGBS.

ACKNOWLEDGMENTS

We thank C. Luo, J. Lucero, M.M. Behrens, and J.R.

Ecker at Salk Institute for help with the experiments and

discussion of the data; J. Ma at Carnegie Mellon

University for proofreading and comments. This work

was supported by US National Institutes of Health grants

EB017235 (C.L.), HG009256 (C.L.), and NS094574

(H.X.).



3D PRINTING OF CANCER ORGANOIDS FOR HIGH THROUGHPUT SCREENING

Andrea Mazzocchi1, Shay Soker


1,2

1. Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC

2. Comprehensive Cancer Center of Wake Forest School of Medicine, Winston-Salem, NC

Corresponding Author: Andrea Mazzocchi, Email: [email protected]

INTRODUCTION

In 2016, it was estimated that there were 1.7 million new

cases of cancer reported in the US with approximately

18% of these cases being of the digestive system.

Currently, a major clinical challenge is determining

optimal treatment to the stage and type of cancer a patient

has, which is often performed via a trial and error

approach. Current tissue culture approaches fail to

emulate the 3D microenvironment of tissue in three

primary ways: surface topography, surface stiffness, and

2D versus 3D architecture. These differences are known

to alter a cell’s phenotype and genotype which have been

linked to effective drug treatment in 2D tissue culture

models but not in 3D organoids or patient models. Many

primary cells are also unable to grow and adhere in 2D

culture further limiting treatment testing opportunities.

The proposed research is based on advanced

biofabrication techniques, such as bioprinting, that can

create environments that mimic the 3D in vivo tumor

microenvironment allows for culture of primary cell and

create a physiologically relevant model for testing.

METHODOLOGY

Cell Culture. Primary patient tumors were received

directly from surgical removal. Tumors were processed

into single cells and cultured in 25uL HyStem gel

organoids. DMEM-10 media was used for all culture.

Colon colorectal carcinoma cells (HCT 116) were also

used for additional testing and organoid density studies.

Biofabrication. Cells were combined with HyStem gel

made with 0.1% photoinitiator at 2,000 cells/uL (unless

noted). Gel was printed and immediately crosslinked

using UV light. Analysis. Primary cell live/dead images

were taken at day 17 with MTS assays. HCT 116 images

and MTS assays were taken at days 7. Each were after

48hr drug incubation.

RESULTS

HCT 116s were seeded at various densities within 25uL

organoids and grown for 5 days to improve organoid

development. At day 5, organoids of each density were

treated with 5mM 5-Fluorouracil (5FU) and controls were

kept. Treatment was carried out for 48 hours at which

time an MTS proliferation assay was carried out on

controls and treated organoids and confocal images were

taken of live/dead stain. From the confocal images, the

ratio of dead to live cells was calculated using a custom

Matlab script looking at color intensity.

Figure 1. (Left) MTS proliferation assay results showing

effects of 5FU treatment. (Right) Ratio of red to green

pixels representing dead to live cells.

CONCLUSIONS

From these initial studies using both immortalized cell

lines and patient derived primary cultures, we have been

able to show that cultures can thrive within 3D cultures

and be used for the study of predicative medicine.

Additionally, it is shown that 3D bioprinting using a

bench top device allows for printing of simple designs in

an accurate and consistent manner. We have been able to

produce micro-scale cancer models to better replicate the

in vivo microenvironment and can support growth of

tissue for over 7 days. We have also been able to show

growth and proliferation of primary cultures that have

been unable to grow using standard tissue culture methods

which in itself is a useful tool. These results show

promising drug treatment results using organoids and

allow for additional studies to further improve design.

ACKNOWLEDGMENTS

We would like to acknowledge funding from NIH R33

grant for Bioengineered Organoids and WFIRM and to

also thank Dr. Konstantinos Votanopoulos for

collaboration through Wake Forest Baptist Hospital.



HYPERTHERMIA-INDUCING NANOPARTICLES AS ADJUVANT THERAPY FOR OXALIPLATIN-BASED

CHEMOTHERAPY IN COLORECTAL CANCER

Bryce D. McCarthy1 and Nicole H. Levi-Polyachenko

1

1. Wake Forest School of Medicine, Department of Plastic and Reconstructive Surgery

Corresponding Author: Bryce D. McCarthy, Email: [email protected]

INTRODUCTION

Mild hyperthermia (35°C < T < 44°C) has been shown to

augment the toxicity profile of various chemotherapeutics. It

is postulated that hyperthermia stimulates cellular

chemotherapeutic uptake mechanisms, inhibits intracellular

damage repair mechanisms, and enhances drug reaction rate.

Heat-generating nanoparticles (NPs) have been extensively

used for their capacity for both heat-sensitization and

thermal ablation of tumors. Currently, no NP is FDA

approved as a hyperthermal therapeutic, though gold NPs

(AuNPs) are undergoing clinical trials for photothermal

ablation of solid tumors under IR. Additionally, iron oxide

NPs (Fe3O4 NPs), which can generate heat under alternating

magnetic field (AMF) or infrared radiation (IR), and silver

NPs (AgNPs), capable of generating heat under IR, are

being investigated for alternative therapeutic purposes.

Photothermal polymer NPs, Polymer Dynamic Organic

Theranostic Spheres (PolyDOTS), developed by our group

are currently being investigated for fluorescent imaging and

hyperthermic potential under IR. Here, the capacity of

AuNPs, Fe3O4 NPs, AgNPs, and PolyDOTS is investigated

for use as an adjuvant for hyperthermic sensitization of

colorectal cancer to oxaliplatin.

METHODOLOGY

Colon cancer cell lines (HT29, RKO, and HCT-116) have

been treated with varying concentrations of NPs (AuNPs,

Fe3O4 NPs, AgNPs, or PolyDOTS) + oxaliplatin (at

preestablished half-maximal inhibitory concentration [IC50-

]) + stimulant (IR or AMF [Fe3O4 NPs only]). Stimulant

was administered for 60 seconds, where IR was

administered at 800 nm and 3 W. Cell viability was

measured using MTS assay and IC50 values was determined

relative to controls of oxaliplatin alone, stimulant alone, NP

+ stimulant, and oxaliplatin + stimulant.

RESULTS

Current experimentation on isolated controls has

demonstrated varying sensitivity of colon cancer cell lines

to oxaliplatin, AgNPs, and Fe3O4 NPs (Table 1).

Table 1: Summary of Treatment IC50 Values

NP heat generation stimulated by IR was measured as a

function of NP concentration (Figure 1).

Figure 1: Summary of NP Heat Generation

CONCLUSIONS

Demonstration of unique toxicity profiles to treatments

indicates patient colorectal cancer types can be screened

for selection of ideal treatment prior to intervention.

Augmentation of sensitivity to oxaliplatin via NP

generated hyperthermia will be evaluated as we proceed

towards clinical trials.

ACKNOWLEDGMENTS

Army Grant: W81XWH-15-1-0408

REFERENCES

1. Graham, E. G., et. Al. (2013). Nano Life, 3(03),

1330002.

2. Anselmo, A. C., et. Al. (2015). The AAPS

journal, 17(5), 1041-1054.

3. Issels, R. D. (2008). European Journal of

Cancer, 44(17), 2546-2554.

Cell Line Oxaliplatin (μM) AgNP (μg/mL) Fe3O4 NP (μg/mL)

HT29 16.87 1149.27 2.47

RKO 2.63 2.13 13.11

HCT-116 N/A 46.59 6.61



AN INVESTIGATION INTO THE VALIDATION AND FUTURE USE OF FE HYBRID III, THOR, AND GHBMC

M50-OS FOR SPACEFLIGHT CONFIGURATION TESTING

Kyle P. McNamara1,2

, Derek A. Jones1,2

, James P. Gaewsky1,2





2Virginia Tech-Wake Forest University Center for Injury Biomechanics

Corresponding Author: Kyle McNamara, Email: [email protected]

INTRODUCTION

Injury assessment reference values (IARVs) posture post-

mortem human subjects in specific configurations to

determine injury risks to occupants. While historically

used in both automotive and military research, these

testing configurations may not translate directly to

spaceflight. Namely, there are differences in the loading

directions, postures, and restraint systems in spaceflight.

This study begins to addresses these differences by

validating Finite Element (FE) models of

Anthropomorphic Test Devices (ATDs) and FE Human

Body Models (HBMs) against physical dummies and

human volunteers in various loading directions. This step

is crucial for future spaceflight seat design.

METHODOLOGY

Between 1976 and 2013, a combination of Hybrid III,

THOR, and human volunteer tests were conducted using

both the Horizontal Impulse Accelerator (HIA) and

Vertical Deceleration Tower (VDT) at Wright-Patterson

Air Force Base and USAF Armstrong Laboratory [1-3].

These tests formed a matrix for FE validation. All tests

used a 5-point belt restraint system in a flat pan seat with

a vertical back [1]. The 275 tests selected comprised 49

physical test configurations with accelerations in the

frontal (X-), rear (X+), lateral (Y), and vertical (Z+)

directions. The acceleration magnitudes varied from 3-20

G and had pulse duration ranges from 20-110 ms.

Simulations were performed using the Humanetics 50th

percentile male Hybrid III, NHTSA THOR 50th Male,

and the Global Human Body Models Consortium

(GHBMC) 50th male simplified occupant (M50-OS)

models in LS_DYNA [4-6]. All simulations consisted of a

150 ms period of gravitational settling and belt

pretensioning followed by the acceleration pulse taken

from the physical test of interest.

Analysis consisted of both a visual comparison of

kinematics as well as a quantitative analysis. Simulation

signals in the head, neck, thorax, and pelvis were

compared to matched physical signals using the Gehre et

al. method (CORrelation and Analysis, or CORA, size

phase, and shape) [7].

RESULTS

Visual inspection for the 49 test configuration simulations

showed agreement with the physical test cases in regards

to the excursion magnitude and direction of the thorax

and the head. Comparison of the THOR model shows

agreement in neck flexion, translation of the back relative

to the seat back, hand position relative to the knees, and

feet position relative to the chair legs.

CONCLUSIONS

Initial validation of ATD and human body models against

physical test data is essential for building confidence in

future applications of those models. Overall the physical

and simulation results were comparable, ensuring

confidence in FE model performance in the validated

regime. The results of this study are highly applicable to

both government and commercial spaceflight and provide

confidence in FE simulation for future design.

REFERENCES

[1] C. Perry, C. Burneka, and C. Albery, "Biodynamic

Assessment of the THOR-K Manikin," DTIC Document2013.

[2] B. F. Hearon and J. W. Brinkley, Aviation, space, and

environmental medicine, vol. 57, pp. 301-12, Apr 1986.

[3] J. R. Buhrman and C. E. Perry, Aviation, space, and

environmental medicine, vol. 65, pp. 1086-90, Dec 1994.

[4] "H350 Adult Dummy Model LS-Dyna," Humanetics

Innovative Solutions, Inc.2012.

[5] J. B. Panzer, S. Giudice, and J. B. Putnam,

NHTSA/USDOT2015.

[6] D. Schwartz, B. Guleyupoglu, B. Koya, J. D. Stitzel,

and F. S. Gayzik, Traffic injury prevention, vol. 16 Suppl

1, pp. S49-56, 2015.

[7] C. Gehre, H. Gades, and P. Wernicke, in 21st International

Technical Conference on the Enhanced Safety of Vehicles

Conference (ESV), Stuttgart, Germany, June, 2009, pp. 15-18.



CHARACTERIZING HEAD IMPACT EXPOSURE IN YOUTH FEMALE SOCCER WITH A CUSTOM-

INSTRUMENTED MOUTHGUARD

Logan E. Miller1, Elizabeth Pinkerton

1, Lyndia Wu

2, Katie Fabian

1, David Camarillo

2, Joel D. Stitzel

1, and Jillian E. Urban

1

1. Department of Biomedical Engineering, Wake Forest School of Medicine

2. Department of Bioengineering, Stanford University

Corresponding Author: Logan E. Miller, Email: [email protected]

INTRODUCTION

While many research efforts have focused on the

consequences of concussion and head impact exposure at

the professional level of female soccer, there have been

few studies characterizing sub-concussive impacts in

youth female soccer. The aim of this study is to

characterize the head impact exposure for youth female

soccer players and investigate the differences in impact

sources and ball delivery methods.

METHODOLOGY

Seven athletes from a local soccer organization were

enrolled in an IRB-approved study. Polyvinyl acetate

(PVA) dental impressions were collected from the upper

dentition of each athlete. Dental molds were poured from

each PVA impression and used to create a custom-fit

instrumented mouthguard. Each mouthguard features a

tri-axial accelerometer and gyroscope embedded within a

rigid retainer material for improved coupling and

measurement of head impact kinematics. To obtain head

kinematics at the head center of gravity (CG), the raw

mouthguard output was transformed from the sensor

location using subject-specific measurements.

Detailed video analysis was conducted to identify impact

time and characteristics of head impact events that were

paired with the kinematic data. Impact characteristics

describing impact source (last contact the ball had before

the observed header) and ball delivery method (details

describing how the ball was delivered for the header)

were collected for each impact. Possible impact sources

include: bounce from ground, as well as headed, kicked,

and thrown from another athletes. Possible ball delivery

methods include: bounce from kick, short kick, long kick,

overhead throw, and underhand throw. A non-parametric

Wilcoxon test of multiple comparisons was used to assess

differences in impact source and ball delivery method in

the associated linear accelerations and rotational

velocities.

RESULTS

Head impact data was collected over 32 practices and 9

games and a total of 764 mouthguard impacts were paired

with video analysis and used to evaluate the differences in

impact source and ball delivery methods. Figure 1

presents the results. In summary, mean linear acceleration

was significantly greater for headers received from a kick

compared to those received from another header

(p<0.0001) or a throw (p=0.0010), and for headers

received from a throw compared to those from another

header (p<0.0001). Headers from a kicked ball had

significantly greater mean rotational velocity than both

headers from a thrown ball (p<0.0001) and from another

header (p<0.0001).

Figure 1: Mean and 95% confidence intervals of linear

acceleration and rotational velocity.

CONCLUSIONS

This is the first study to evaluate head impact exposure in

adolescent girls’ soccer using an instrumented

mouthguard. This study quantified differences in head

kinematics based on impact source and ball delivery

method and found that head impact exposure varies

significantly between impact sources and ball delivery

methods.

ACKNOWLEDGMENTS

This study was supported by the Childress Institute for

Pediatric Trauma at Wake Forest Baptist Medical Center.



AGENT-BASED MODELING TO PREDICT THE EFFECT OF ELECTROCHEMOTHERAPY ON TUMORS

Maryam Moarefian1, Luke Achenie

2

1. Virginia Polytechnic Institute and State University, Mechanical Engineering Department

2. Virginia Polytechnic Institute and State University, Chemical Engineering Department

Corresponding Author: Luke Achenie, Email: [email protected]

INTRODUCTION

Tumor microenvironment has a complex multiphysics and

multiscale nature. Therefore agent-based modeling

(ABM) is appropriate and convenient for studying the

system. Specifically ABM is employed to predict the

tumor cell behavior in contact with a chemical

perturbagen or drug of interest; this is essential for

personalizing cancer treatment. There is the fact that the

tumor microenvironment is very heterogeneous due to

angiogenesis, creating significant barriers for effective

drug delivery. Application of an electric field has the

potential to overcome some of these barriers. Equation-

based computational models have been developed to

study electrokinetics phenomena. However, to our

knowledge, in the open literature, an ABM has not been

used to study the effect of applied electric field on a

complex chemotherapeutic delivery system. In this paper

we discuss the development of an ABM model that would

lead to a significantly more realistic prediction of the

optimum electric field and chemotherapeutics that would

result in the maximum fraction of cell killed.

METHODOLOGY

In this study, we will employ the diffusion limiting

aggregation model from the Netlogo library to create

random tumor shape from the stem cell. Using the tumor

model from the open source Netlogo software library

(https://ccl.northwestern.edu/netlogo/) allows us to

simulate the tumor cell division or mitosis and can die via

apoptosis (programmed cell death). We also added the

drug to the environment to kill the tumor randomly in the

direction of applied electric field.

Figure 1: Agent-based conceptual model

Figure 1 shown the conceptual model of the proposed

agent-based model. In our conceptual model, we consider

the portion of the tissue. The tissue portion has several

compartments segregated by permeable blood vessels.

Each compartments contains metabolic agent such as

oxygen and carbon dioxide, red blood cells, white blood

cells, tumor cells, normal cells, and drug molecules.

Compartment can exchange certain agent such as cancer

cells which is the concept of metastasis, drug molecules,

and nutrients by certain driven force. Driven forces can be

electric fields, concentration gradient, and pressure

gradient.

RESULTS

The preliminary result is based on modeling one

compartment of the proposed conceptual model. The

preliminary results showed the tumor cells proliferation

control by their distance to nutrient molecules, drug

molecules without electric field, and drug molecules

moving with electric field.

Figure 2: Control tumor growth with. (a) Nutrition. (b)

Drug molecules w/o electric field. (c) Drug and electric

field

Figure 2 demonstrates the number of tumor cells in

certain amount of time in three different conditions.

Graphs shows the control of tumor cells proliferation by

applied electric field.

CONCLUSIONS

The result of the ABM model showed the effect of

electric field is early stage tumor is more effective.

Additionally, sinusoidal movement of drug with electric

field has more effect on tumor kill than the directional

movement. Finally, the ABM can predict the intensity and

the number of the drug to get the maximum fraction of

tumor killed. In this study, we used the experimental data

from literature to develop the computational close to in

vitro experiment. However there is a need to initialize the

parameter by experimental data from the microfluidic

device.



NOVEL DEVICE FOR PREVENTING RODENT WOUND SPLINT REMOVAL

Jade Montgomery1,2

, Linda J. Jourdan2, and Robert G. Gourdie

1,2

1. Virginia Tech, School of Biomedical Engineering and Sciences


Corresponding Author: Jade Montgomery, Email: [email protected]

INTRODUCTION

Humans are somewhat unique in the animal kingdom

when it comes to skin. Not only are we mostly hairless

due to a low density of hair follicles in most areas, but our

skin is also firmly attached to the underlying fat layer,

what is known as ‘tight skin’. With the notable exception

of pigs, the vast majority of other animal models

commonly used in research, such as rodents, have what is

known as ‘loose skin’, where the skin is not attached to

the underlying fat. Whether an animal is loose- or tight-

skinned has enormous impact on wound healing and scar

formation. Loose-skinned animals heal primarily by

wound contraction due to the relatively unrestricted

movement of the skin, while tight-skinned animals heal

primarily by the formation of granulation tissue. A wound

splint model is a well-known method of forcing excisional

wounds in loose-skinned animals to heal more similarly to

tight-skinned animals1. The wound splint prevents wound

contraction by suturing ring-shaped silicone splints

around an excisional wound, inducing a mechanical

environment in the wound like that present in tight skin.

A major challenge with the wound splint is preventing the

animal from removing the splints, through either chewing

or scratching, in the days between surgery and biopsy

collection. For this reason, most wound splint studies are

conducted over short time periods and/or only 1-2 wounds

are made high up between the shoulder blades where the

animals cannot reach. Clearly this is not ideal if one plans

to study longer-term scar formation, and a smaller number

of wounds makes controlling for individual variance more

difficult and increases the number of animals required for

any one study. To this end, this lab has developed a

simple device for preventing removal of wound splints.

METHODOLOGY

Commercial rat jackets of the appropriate size, and a yard

of the breathable lightweight fabric they are constructed

from, were obtained from Lomir Biomedical Inc. Lace

elastic was obtained from Dritz and industrial strength

sew-on velcro strips from Velcro Companies. An

approximate rectangle sizes to cover the entire dorsum

with a panel above to secure under the velcro straps of the

jacket was cut from the fabric. Two slits were cut in the

bottom edges through which lace elastic was threaded and

secured. Fabric glue was used to attach velcro and lace

elastic as shown in Figure 1, and then a sewing machine

was used to go over these pieces to ensure attachment.

Jackets and the handmade devices were secured snugly

around the animals 4 days prior to surgery in order to

allow them to adjust to the garments prior to wounding.

Jackets and devices were replaced weekly or as needed as

they became soiled or damaged, and washed with laundry

soap and allowed to dry in between uses.

Figure 1: Diagram of device design & photograph of

device and jacket properly placed on an animal.

RESULTS

Devices were 100% successful at preventing wound splint

removal by the animal for up to at least 6 weeks (the

longest time point studied). While the skin naturally

expels sutures over this time frame, with occasional

resuturing of the splints they remained firmly attached to

the outside of the wound throughout the length of the

study. The only side effect of the devices, apart from

some minor hair removal/chafing under the straps, was

actually caused by the commercial rat jacket, where some

rodents would trap their lower jaw in the threads of the

jacket and become unable to free themselves.

CONCLUSIONS

We present a highly effective, minimally distressing

method for prolonging the attachment of wound splints to

a rodent model. This device could also be employed to

prevent rodent removal of other kinds of long- or short-

term study devices/solutions on the dorsum.

REFERENCES

1.Galiano, R.D., et al. Wound Repair Regen. 12, 485–92



MITIGATING BIOFILM FORMATION WITH SURFACE TOPOGRAPHY MODIFICATION

Carolyn Y. Mottley1, Zhou Ye

2, AhRam Kim

2, and Bahareh Behkam

1,2

1. Virginia Tech, Department of Mechanical Engineering


Corresponding Author: Carolyn Mottley, Email: [email protected]

INTRODUCTION

Hospital acquired infections (HAIs) affect 1.7 million people per year, are responsible for 99,000 annual deaths and $20 billion in health care costs.

1 Many HAIs are

acquired due to patient contact with contaminated surfaces (gloves, surgical instruments, etc.).

1 Instead of

using antimicrobial-coated surfaces, surface topographical modification of materials to prevent microbial attachment could be a cheaper, more viable method in preventing surface contamination. However, the effect of surface topography on microorganism attachment and phenotypic changes is not well understood. In this study, surfaces were coated with polystyrene (PS) nanofibers to measure the resulting biofilm formation. The attachment density of Candida albicans, a HAI model organism, was quantified on 3 catheter materials using dynamic retention assays and serial dilution and plating methods. These data suggest that mechanically-based antimicrobial systems can reduce microbial attachment to surfaces.

METHODOLOGY

We have previously developed a biophysical model that relates the energetic state of a single cell on a surface to biofilm formation outcome on that surface.

2 Using this

model, optimum PS topographical feature sizes for deposition on the surfaces of latex (LA), silicone (SI), and polyurethane (PU) catheters were identified. Parallel PS nanofibers of prescribed diameter (1-1.2 µm) and spacing (2 µm) were deposited on catheters using the Spinneret-based Tunable Engineered Parameters (STEP) technique.

3

Dynamic retention assays were performed and the number of C. albicans cells attached to surfaces of catheters was measured using the serial dilution and plating technique.

RESULTS

The interactions between C. albicans and LA and SI

catheters have significantly lower work of adhesion

values (47.5, 42.1 mJ m-2

) than PS (78.3 mJ m-2

);

therefore, there was a greater number of cells attached to

them than the PU catheters. In case of the PU catheters,

the work of adhesion was slightly lower than PS (69.7 mJ

m-2

) , which assisted in decreasing cellular attachment

(Fig. 1a).

Figure 1. Normalized Cell Attachment Density (a) and

SEM of PU Catheter After 24 Hours (b). 2

The attachment density and differentiation into the

pathogenic phenotype (i.e. hyphal formation) was

examined via scanning electron microscopy (SEM) (Fig.

1b, all scale bars are 50 µm). Visual inspection showed

that bare surfaces (top of Fig. 1b) had a higher number of

hyphal cells in comparison to yeast cells. Raman

spectroscopy characterizations are ongoing for more

precise quantification.

CONCLUSIONS

Introduction of PS nanofiber coating on PU catheters, C.

albicans cell attachment by approximately 25%. Our

biophysical model was capable of predicting the outcome

of the biofilm assays performed. Overall, surface

modifications of commonly used biomedical materials can

prevent attachment of disease-causing microorganisms.

ACKNOWLEDGMENTS

We would like to thank MicroN BASE Lab members, as

well as Dr. Ryan Senger, A. Fisher and B. Carswell for

assistance with the Raman characterization study.

REFERENCES

1. Centers for Disease Control and Prevention, U. S.

Preventing Healthcare-Associated Infections. (2011).

2.Ye, Z., Kim, A. et al. A Biophysical Model for ab initio

Design of Nanofiber-Coated Surfaces for Mitigation of

C. albicans Fouling on Medical Catheters, in review.

3. A.S. Nain, et al. Macromol. Rapid Commun. 30 (2009).

71 Translational Cancer Poster A: Latham B, 10:45


THE DEVELOPMENT OF AN INTELLIGENT SURGICAL PROBE FOR

REAL-TIME MONITORING OF ELECTROPORATION BASED TREATMENTS

Timothy J. O’Brien

1, Mohammad Bonakdar

2, and Rafael V. Davalos

1


2. Virginia Tech, Mechanical Engineering

Corresponding Author: Timothy J. O’Brien, Email: [email protected]

INTRODUCTION

Irreversible Electroporation (IRE) is a new energy-based

focal ablation technique clinically used to treat patients

with unresectable tumors [1]. Motivated through the

generation of micro- second high-voltage pulses, IRE

therapy induces nanoscale structural defects in lipid bilayer

of the cells within the target region, ultimately killing cells

with sub-millimeter resolution at therapy margins. Since its

initial use as a non-thermal ablation technology in 2005,

IRE has been used in over 5500 human patients. Though,

this treatment modality is currently devoid of real-time

sensing or monitoring of the treatment effectiveness,

forcing surgical oncologists to rely on either pretreatment

planning [2] or post-operative magnetic resonance imaging

(MRI) and a small biopsy to fully understand the success of

treatment. These complications result in a longer procedure

time and inaccuracy. We have previously shown that

electrical impedance measurement could be used to give

feedback about the ablation size [3]. Here, we further

developed the technique and took advantage of a recently

developed perfused organ model for characterization of

IRE therapy [4] to monitor the IRE ablation size in a

perfused porcine liver.

METHODOLOGY

Standard microfabrication techniques were used to

fabricate the impedance micro-sensor array with a

thickness of 20 um. The impedance sensor was wrapped

around a bipolar IRE probe which was used to deliver the

pulses to the target tissue. An impedance analyzer was

connected to the impedance sensor through a multiplexer

and collected impedance spectra during and after

treatments and different points along the IRE probe. The

impedance data were then fitted to the electric circuit

model of the tissue to extract the tissue conductivity. The

treatments were performed on a freshly harvested porcine

liver which was perfused with a modified PBS solution to

keep it viable during and after completion of the treatment.

The treatment sites were sliced and stained with triphenyl

tetrazolium chloride (TTC) to visualize the ablated area.

RESULTS

The change in the tissue conductivity could be used to

determine the size of an ablation in a perfused organ model

and a live patient as shown in Figure 1.

Figure 1: (A) Shows perfused organ model setup. (B)

Magnified image of the smart probe prior tissue testing

(C) Smart probe during tissue testing (custom 3D printed

clamp to connect micro-sensor array to leads)

CONCLUSIONS

The smart probe could potentially eliminate the

overtreatment of tissue and reduce unnecessary thermal

effects. Further, this technology could provide surgeons

with a visualization of the ablation zone.

ACKNOWLEDGMENTS

Thank you to Dr. Robert Neal at Angiodynamics and Dr.

Iain McKillop and Dr. David Iannitti at Carolinas Medical

Center for their support and guidance in this work.

REFERENCES

[1] Davalos R.V. et al, Annals Biomed. Eng., 2005

[2] Latouche E.L. et al, IFMBE Proceedings, 2015

[3] Bonakdar M. et al, IEEE Trans. Biomed. Eng., 2015

[4] Bhonsle S. et al, J Vasc. Interv Radiol, 2016, In Press.



CORTICAL THINNING AND STRUCTURAL BONE CHANGES IN NON-HUMAN PRIMATES FOLLOWING

SINGLE FRACTION WHOLE CHEST RADIATION

Catherine Okoukoni, Ph.D.1,2,3, Michael Farris, M.D. 1, Emory R. McTyre, M.D.1, J. Daniel Bourland, Ph.D.1,2, J. Mark Cline, DVM Ph.D. 4, Greg Dugan DVM4, Jeffrey S. Willey, Ph.D.1,3

1. Wake Forest University, Department of Radiation Oncology 2. Wake Forest University, Department of Physics 3. Wake Forest University, Pathology Department

4. Wake Forest University School of Medicine Corresponding Author: Catherine Okoukoni, Email: [email protected]

INTRODUCTION Vertebral radiation therapy (RT), especially using stereotactic body radiation therapy (SBRT), has been associated with an increased risk of vertebral compression fracture (VCF) in cancer patients.1,2 Fractures tend to occur within the first year of SBRT.3 The purpose of this study is to describe acute RT induced changes in bone structure using a clinically applicable animal model. METHODOLOGY Sixteen male rhesus macaques non-human primates (NHPs) were analyzed after exposure to total chest RT to a dose of 10 Gy in one fraction. Ages at time of RT varied from 45 - 134 months old. Computed tomography (CT) scans were taken 1 month prior to RT and 2, 4, 6, and 8 months following RT. Bone mineral density (BMD) and cortical thickness (Ct. Th) were calculated and mapped to 3D models of the thoracic and lumbar vertebrae.3 Structural histopathology for all NHPs was assessed using hematoxylin and eosin (H&E) staining. RESULTS Significant loss of Ct.Th. at T9 occurred by 2 months post IR (p = 0.0009), and then persisted to 8 months post IR. No loss of Ct.Th. was observed in the vertebrae that were located out-of-field (L2 and L4). Significant loss of BMD was, also, observed by 4 months post-IR for T9, and by 6 months post RT for L2, and L4 (p < 0.01). Increased porosity with pronounced focal cortical thinning was observed post-RT in all thoracic and lumbar samples on H&E (figure 1).

Figure 1: Photomicrographs of sagittal sections at the

ventral aspects of the thoracic vertebral body stained with hematoxylin and eosin (H&E) illustrating lack or severe

thinning of cortical bone. CONCLUSIONS Acute and persistent BMD and Ct. Th. loss was observed as early as 3 months following high dose chest IR in a clinically applicable NHP model. REFERENCES

1. Cunha, M. V. R. et al. Vertebral compression fracture (VCF) after spine stereotactic body radiation therapy (SBRT): analysis of predictive factors. Int. J. Radiat. Oncol. Biol. Phys. 84, e343–9 (2012).

2. Rodríguez-Ruiz, M. E. et al. Pathological vertebral fracture after stereotactic body radiation therapy for lung metastases. Case report and literature review. Radiat. Oncol. 7, 50 (2012).

3. Okoukoni, C. et al. A cortical thickness and radiation dose mapping approach identifies early thinning of ribs after stereotactic body radiation therapy. Radiother. Oncol. 119, 449–453 (2016).



A FINITE ELEMENT MODEL OF A SMALL-STATURE FEMALE PEDESTRIAN

FOR SIMULATING TRAFFIC ACCIDENTS

Wansoo Pak1, Costin D. Untaroiu

1, Scott Gayzik

2

1. Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA

2. Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, NC, USA

Corresponding Author: Wansoo Pak, Email: [email protected]

INTRODUCTION

The pedestrian is one of the most vulnerable road users.

Among the road traffic deaths, the pedestrian fatalities are

comprised 22% (World), 26% (Europe), and 22% (U.S.)

reported in 2015. In the United States, 4,884 pedestrians

were killed and approximately 65,000 injured in road

traffic crashes [1]. Therefore, pedestrian protection

regulations, which involve subsystem tests in car-to-

pedestrian collisions (CPC), have been proposed in

Europe and Asia. The main goal of this study was to

develop and validate the FE model corresponding to a 5th

percentile female (F05) pedestrian.

METHODOLOGY

The model mesh was developed by morphing the Global

Human Body Models Consortium (GHBMC) 50th

percentile male (M50) pedestrian model to the

reconstructed geometry of a human subject of F05

anthropometry. The material properties of the pedestrian

model were assigned based on GHBMC M50 occupant

model. The lower extremity, shoulder joint, and upper

body of the FE model were preliminarily validated against

post mortem human surrogate (PMHS) test data recorded

in valgus bending tests and upper body blunt lateral

impact tests. Then, vehicle-pedestrian impact simulations

(Figure 1) were performed using the whole pedestrian

model and the results were compared to corresponding

PMHS tests [2].

Figure 1: The whole body CPC simulation setup

RESULTS

For the lower extremity validation, lower stiffness than

the PMHS test corridors was observed in the F05 model.

Similarly, the F05 model predicted softer response

compared to the PMHS and M50 model responses in the

upper body validation. The kinematic trajectories

predicted by the F05 model were similar at the beginning

and slightly below the corresponding PMHS test corridors

(Figure 2). The kinematic responses in vehicle-pedestrian

interaction were shown relatively similar reaction

compared to the recorded PMHS data.

Figure 2: The kinematics-marker trajectories relative to

the vehicle: FE model vs. PMHS tests. a) Head CG, b) T1

CONCLUSIONS

Overall, the results generated by the FE model showed to

be well correlated to test data. Therefore, the model could

be used to investigate various pedestrian accidents and/or

to improve safety regulations and vehicle front-end design

for pedestrian protection.

ACKNOWLEDGMENTS

Funding for this study was provided by the Global Human

Body Models Consortium (GHBMC).

REFERENCES

[1] National Highway Traffic Safety Administraion,

“2014 Data: Pedestrians,” 2014.

[2] J. R. Kerrigan, J. R. Crandall, and B. Deng,

“Pedestrian kinematic response to mid-sized

vehicle impact,” Int. J. Veh. Saf., vol. 2, no. 3, pp.

221–240, 2007.

a) b)



QUANTITATIVE ANALYSIS OF THE EPIDERMAL NECROSIS IN CUTANEOUS RADIATION INJURIES INDUCED

BY BETA-SOURCE IRRADIATION

Olga V. Pen1,2

, Peter A. Antinozzi3, Nancy D. Kock

4, J. Daniel Bourland

1,2

1. Department of Radiation Oncology, Wake Forest School of Medicine, Wake Forest University

2. Department of Biomedical Engineering, VT-WFU SBES, Wake Forest University

3. Department of Biochemistry, Wake Forest University

4. Department of Pathology and Comparative Medicine, Wake Forest School of Medicine, Wake Forest University

Corresponding Author: Olga V. Pen, Email: [email protected]

INTRODUCTION

Cutaneous radiation injury (CRI) to the skin occurs as the

patients are exposed to the large radiation doses in the

course of radiation therapy. The severity of these injuries

can vary from the light dermatitis and discoloration to

severe ulceration and skin atrophy at the treatment site.

While the benefits of undergoing the treatment often

outweigh the concerns about the probable CRI

development, finding a way to minimize the side-effects

and alleviate discomfort experienced by the patients is of

utmost importance.

With that in mind, a study has been conducted on the

progression of CRI resulting from a limited-area beta-

source irradiation. Pigs have been chosen as an animal

model accurately representing the progression of CRI in

humans. The proposed treatment alternatives for this

study included gauze dressing, SilverlonTM

dressing , and

untreated group as a control. The histological slides from

the site of injury has been harvested and digitized on the

70th

day after the initial exposure. The resulted slides have

been analyzed both by a trained histologist and

specifically developed computer algorithm that provided

quantitative description of the epidermal necrosis

severity, one of the most defining features of the

cutaneous radiation injury, for each collected histological

slide, and enabled a rigorous statistical analysis of the

possible differences in the CRI severity in groups treated

with different proposed treatment plans.

METHODOLOGY

The NDPI histological slides acquired from the wound

sites are processed and separated into RGB channels. The

area of the skin epidermis is selected by an automated

flood fill algorithm that recognizes the specific

morphological boundaries in the green channel. As the

H&E stain commonly used in histology is prone to

accumulate in the dead cell nuclei is most visible in red

(eosin) and blue (hematoxylin) channels, their

combination can provide a map of dead nuclei cells that

can later be counted through particle analysis algorithm

rigged to recognize the particles of specific size and

shape.

RESULTS

Figure 1: Analysis of the wound: histological slide

stained with H&E (top), corresponding wound (bottom

left) and epidermal necrosis quantitative description

normalized by the epidermis area (bottom right)

Clear correspondence between the observed CRI severity

and the dead nuclei count can be observed on Figure 1.

CONCLUSIONS

Proposed method provides a reliable quantitative CRI

characteristic that can be used for a statistical analysis of

CRI severity and treatment progression in three study

groups and enable us with insight into the better course of

CRI side-effect management during the cancer treatment.

ACKNOWLEDGMENTS

This study is funded in part by Argentum Medical LLC

and the Biomedical Advanced Research and Development

Authority, US Department of Health and Human

Services.



CHARACTERISTIC DIFFERENCES BETWEEN WATER DIALYZED AND BUFFER DIALYZED KERATOSE

BIOMATERIAL

Nils A. Potter1, Mark Van Dyke

1


Corresponding Author: Nils A. Potter, Email: [email protected]

INTRODUCTION

Keratin proteins are instrumental in the structural integrity

of hair follicles by providing strength and shape, and have

been used as structural proteins for biomaterials. Hair

keratins are often extracted through oxidation or reduction

of hair fibers, which results in solubilization of Keratose

(KOS) or Kerateine (KTN), respectively [1]. Purifying

keratins includes a dialysis step, and it has been

determined that excessive aggregation confounds this

process and certain buffer solutions may be better suited

for keratin purification than water. Due to these different

dialysis agents, keratin purity is affected, which can lead

to differences in intrinsic properties of keratin hydrogels.

Studying the effects different purification methods have

on these materials can lead to a deeper understanding of

how they will respond in an in vivo setting. This study

explores the effects these different purification methods

have on the characteristics of purified KOS hydrogels.

METHODOLOGY

KOS Extraction: Human hair fibers were oxidized in 2%

paracetic acid, and subjected to extraction with Tris base.

The protein solution was centrifuged, filtered, and

dialyzed against ultrapure water for one batch (WKOS)

and phosphate buffer for another batch (BKOS). The

resulting solution was lyophilized into a powder for future

use and stored at -20°C.

KOS Hydrogel Preparation and Rheology: 12 wt% KOS

and 12 wt% 1,4-butanediol diglycidyl ether (BDDE;

relative to KOS mass) were constituted in ultrapure water,

placed in silicone molds, and cured for 72 hrs at room

temperature (RT). Gels were removed, and testing was

conducted on the ARG2 rheometer (TA Instruments).

Size-Exclusion Chromatography (SEC): KOS extracts

were constituted in 10 mM Na2HPO4/100 mM NaCl at a

concentration of 0.2 mg/ml. 20 µl of sample was injected

into the injection loop, and samples were run for 20 min.

Dynamic Light Scattering (DLS): KOS extracts from both

processing methods were constituted in water and

phosphate buffer at a concentration of 1 mg/ml. Intensity,

volume, and correlation were observed from analyses.

Enzymatic Degradation: Hydrogels were made as stated

previously in a sterile manner. Gels were subjected to

sterile filtered enzyme solutions (PBS, type I collagenase,

elastase, trypsin, chymotrypsin, and keratinase) of 0.5

U/ml at a 2:1 volume ratio. Supernatant was removed and

replenished with fresh enzyme solution at predetermined

time points. Degradation quantification was carried out by

performing Lowry Assays.

RESULTS

Figure 1: Frequency sweep tests (n = 8) comparing

storage modulus (a) and phase (b) of BKOS and WKOS

hydrogels (* indicates p < 0.001. ** indicates p < 0.01).

Differences in BKOS and WKOS sizes by SEC (c).

CONCLUSIONS

BKOS hydrogels exhibited more resistance to shear and a

more elastic structure than WKOS hydrogels. BKOS

material was also found to contain a decreased low

molecular weight fraction along with displaying more

stability in a dynamic setting. WKOS hydrogels were

shown to be less susceptible to enzymatic degradation

than BKOS hydrogels. Further experiments revealed that

greater amounts of peptide fragments incorporated into

BKOS hydrogels resulted in less enzymatic susceptibility.

These results show that KOS extraction is a tunable

system, and this can be manipulated to extract KOS that

has more favorable properties depending on the specific

application.

ACKNOWLEDGMENTS

The authors acknowledge Dr. Rick Davis for generously

allowing the use of the ARG2 Rheometer. Funding was

provided by BEAM departmental and overhead funds.

REFERENCES

[1] Hill P et al Biomaterials 2010; 31(4):585-93.



3D CELL CULTURE STUDIES IN MICROFLUIDIC SYSTEMS FOR TRANSLATIONAL APPLICATIONS

Shiny Rajan1, Parker Hambright


1,3,4, and Adam R. Hall

1,2,3,4


2Wake Forest University,

3Wake

Forest Institute of Regenerative Medicine, 4Comprehensive Cancer Institute, Wake Forest

Corresponding Author: Adam R. Hall, Email: [email protected]

INTRODUCTION

3D cell culture recapitulates the physiological

microenvironment more fully than 2D models by

providing relevant physical and spatial interactions. These

factors are known to affect cellular behavior1by

influencing signaling and gene expression pathways, and

are thus crucial to accurate representation of in vivo

systems. Microfluidics can further provide powerful

control, delivery, and analytical capabilities that would

enable parallel testing of such 3D culture constructs in a

miniaturized context. We have combined adhesive

membrane-based rapid prototyping with a photopatterning

technique for producing 3D cell cultures in situ in the

chambers of an active microfluidic device. With this

platform, we initially tested the effects of

chemotherapeutic drug exposure on both the migration

and viability of colorectal cancer cells in 3D culture. We

further showed that non-passaged patient cells can be

incorporated directly into the device architecture for

personalized medicine applications. We have since

expanded the system to incorporate spheroids produced

by the hanging drop method and developed a body-on-a-

chip to study multiple organoids in series. We have also

developed a non-hydraulic valving system to manually

control the flow of culture media between organoids for

variable condition testing.

METHODOLOGY

Our devices are fabricated using a low-cost approach2 by

layering thin, patterned adhesive membranes between

microscope slides with ports for fluid delivery. Cellular

constructs are produced by photo patterning a mixture

containing hyaluronic acid (HA) hydrogel, photo initiator

and target cells/spheroids directly in the device by

exposing it to UV light through a photo-mask. After

flushing with clean buffer, discrete 3D cell cultures of

defined shape and size are left in the chamber.

RESULTS

We have demonstrated that not only cell lines but non-

passaged patient cells were viable in our devices for at

least three weeks. Drug testing in our system was able to

recapitulate the in vivo patient response. We were also

able to sustain multiple, organ-specific cell structures

(based on both cell lines and spheroids) in the platform

under common media, demonstrating true “body-on-a-

chip” capabilities.

Figure 1. a) LIVE/DEAD assay of patient tumor cell constructs

after 7 day of drug exposure. (Green indicates live cells and red

indicates dead cells), (i) control with no drug, (ii & iii) tumor

construct exposed to carboplatin/premetrexed mixture (0.1um,

10um), (iv & v) cisplatin/premetrexed mixture (0.1um, 10um).

b) Viability (live:dead ratio) of cells calculated from images. c)

LIVE/DEAD assay of spheroid and cell constructs in body-on-a-

chip platform after 14 days under co-circulation.

CONCLUSIONS

This platform has immense potential for developing 3D

tissue and disease models, parallel drug testing, and

studying cellular dynamics in vitro with efficiency and

low cost.

ACKNOWLEDGMENTS

We acknowledge funding from the Department of

Defense and thank Dylan Knutson for contributions to

this project.

REFERENCES

1. Imamura, et al. Oncol Rep 33(4):1837-43, (2015).

2. Cooksey, et al. Lab Chip14(10):1665-1668, (2014)



CHANGES IN LIMB SYMMETRY DURING A 2 MILE OUTDOOR RUN

Kristen E. Renner1, Robin M Queen

1


Corresponding Author: Kristen Renner, Email: [email protected]

INTRODUCTION

The presence of side-to-side asymmetry is known to

increase injury risk during running; fatigue has been

shown to affect loading patterns over of the course of

endurance runs1. It has been shown that gait mechanics

differ on a treadmill compared to overground running2,

including the peak value of the ground reaction foces3.

The impact that fatigue has on side-to-side asymmetry has

never been assessed in an overground running study.

Therefore, this study investigated the impact of fatig on

loading symmetry during a 2 mile run on an outdoor

course. We hypothesize that the LSI will increase during

the run as the subject begins to fatigue.

METHODOLOGY

27 subjects (16 males, 11 female) completed a 2 mile

overground run wearing single-sensor, load monitoring

insoles (pedoped, Novel Electronics). Each subject ran the

same 2 mile course in their own training shoes. The forces

from twenty-step intervals were pulled for each limb at

25%, 50%, and 75% of the run to determine change in

symmetry throughout the run. The overall and impact

peaks were identified for each step. A limb symmetry

index (LSI) was calculated for each step for both the

impact and the overall peaks and then averaged for each

time point. LSI is the absolute value of the difference

between left and right peak divided by the average.

A statistical analysis was performed on the LSI values

across time using parametric and non-parametric tests

depending on data distribution (JMP, SAS). A non-

parametric Wilcoxon signed rank test was completed to

determine differences between the LSI impact peak and

the LSI overall peak at each time point individually. For

all statistical tests, a type I error rate of α=0.05 was used

to determine statistical significance.

RESULTS

The limb symmetry indexes are reported in Figure 1.

While our LSI values are higher than what has been

reported4, previous articles considered indoor or treadmill

running which provides a consistent and predictable

environment compared to outdoor overground running.

There was no difference in overall peak load LSI across

time. Additionally, no differences in impact load LSI

existed across time (Figure 1). When the LSI values from

the impact load were compared to the overall peak load,

we found a significant difference between groups, with

the impact peak LSI begin greater (p<0.001).

Figure 1: The mean LSI value and standard deviation for

each time point (25%, 50% and 75%) of the run. The *

indicates a difference between the impact and overall LSI

values.

The lack of change in LSI across time does not support

the study hypothesis. At the end of each run, we spoke to

the participants about the difficulty of the run and their

level of fatigue. It was clear that most of the subjects were

experienced runners who were training for long distance

races. Therefore, it is likely that the 2 mile course that

was being completed was likely not fatiguing the subjects.

Future studies would need to be designed to be harder,

faster paced, or longer distanced to increase fatigue.

Additionally, future work could include a covariate for

the rate of perceived excursion at the end of a run.

CONCLUSIONS

The results of this study indicates that subjects use a

portion of the stance phase after the impact peak to alter

the loading pattern to improve their limb asymmetry by

the time they reach the peak overall load during running.

REFERENCES

1. Pappas, E. JSMS, 15, 87-92, 2012. 2. Alton, F. Clin

Biomech. 13, 434-440. 1998. 3. Riley, P. Med Sci Sports

Exerc. 40(6), 1093, 2008. 4. Zifchock, R. J of Biomech.

39(15), 2792-2797, 2005.

* * *


Poster B: Latham B Tissue Engineering 78


EFFECT OF NON-STEROIDAL ANTI-INFLAMMATORY DRUGS ON ACHILLES

TENDINOPATHY IN A MURINE MODEL

Sabah N. Rezvani1, Adam Bitterman

2, Anna Plaas

3, Jun Li

3, Vincent Wang

1


2. Northwell Health, Huntington, NY

3. Rush University Medical Center, Chicago, IL

Corresponding Author: Sabah Rezvani, Email: [email protected]

INTRODUCTION

Functional impairment of tendons (e.g., rotator cuff and

Achilles) represents a major health care problem. Patients

suffering from degenerative tendinopathy have limited

options, particularly since surgical debridement and

corticosteroid injections show poor long-term outcomes.

Non-steroidal anti-inflammatory drugs (NSAIDs) are

commonly prescribed to treat degenerative tendon

pathologies. While providing short term pain relief, not

much is known about their mechanistic effect on

tendinopathy. There has been recent interest in examining

efficacy of timing of NSAID treatments [1,2]. This study

aimed to evaluate the effects of ibuprofen on tendon

structural and mechanical properties of Achilles

tendinopathy in a murine model.

METHODOLOGY

Our previously developed murine tendinopathy model was

used for this work [3]. Briefly, C57BL/6 wild-type mice (12

weeks) received injections two days apart of 100ng rhTGF-

1 into the mid-portion of the Achilles tendon, inducing

tendinopathy. Ibuprofen was administered orally either 3 and

9 days post-injury or 9 and 15 days post-injury. Five groups

were included in the study: EarlyIB, LateIB, Naïve +

EarlyIB, Naïve + LateIB, and Untreated Injury. Following

sacrifice of the mice at 28 days post injury, Achilles tendons

were harvested, and RNA was prepared as described by

Trella et al. [4] for transcriptomic analyses using wound

healing and NfKb target gene platforms (PAMM-121A,

PAMM-225ZA Qiagen, Valencia, CA). Tendon

histopathology was assessed on paraffin embedded thin

sections using standard methods for HE and Safranin O

staining. Tensile testing consisted of preconditioning and

load to failure on an MTS Insight 10 (Eden Prairie, MN).

RESULTS

EarlyIB treatment resulted in a higher percentage of

inflammation genes upregulated relative to LateIB. Drug

administration to naïve mice showed no significant effects

on gene expression in tendons. The severity of the

inflammatory response from histologic assessment

appeared to be lessened in the late relative to EarlyIB

group.

Figure 1: Maximum stress showed no significant

differences among groups. Similarly, no differences in

structural and material properties were noted.

There were no significant differences across all groups

with regard to cross-sectional area, maximum load,

stiffness, peak stress, and elastic modulus (Figure 1).

CONCLUSIONS

Oral administration of ibuprofen during early and late

phases of murine Achilles tendinopathy leads to a

persistent activation of the inflammatory and wound

healing pathways in the affected tendons. Interestingly,

despite differences in gene expression profiles,

administration of ibuprofen leads to no significant

differences in the mechanical properties of murine

Achilles tendons.

ACKNOWLEDGMENTS

NIH AR 63144 (VMW) and Rush Arthritis Institute (AP)

REFERENCES

[1] Tan et al. J Hand Surg Am (2010) [2] Connizzo et al.

Clin Orthop Res (2014) [3] Bell et al. J Biomech (2013)

[4] Trella et al. J Orthop Res, 2017 (in press)



HIGH-FREQUENCY IRREVERSIBLE ELECTROPORATION TARGETS MALIGNANT CELLS IN OVARIAN

CANCER MODEL

Andrea Rolong1, Eva M. Schmelz

2, and Rafael V. Davalos

1

1. Virginia Tech – Wake Forest University School of Biomedical Engineering and Sciences

2. Virginia Tech, Department of Human Nutrition, Foods, and Exercise

Corresponding Author: Andrea Rolong, Email: [email protected]

INTRODUCTION

Failure to successfully treat cancer is not usually due to

the absence of initial remission or a primary response, but

rather due to tumor recurrence or relapse after therapy;

tumor-initiating cells are believed to play a major role in

this negative outcome. Tumor-initiating cells (TICs),

otherwise known as cancer stem cells (CSCs), are cells

that are able to create a new tumor with similar

characteristics to the one from which they were derived.

They present a high capacity for self-renewal,

susceptibility to differentiate into actively proliferating

tumor cells, and resistance to radiation or chemotherapy.

Irreversible electroporation (IRE) is a non-thermal

ablation technique with the capability to treat otherwise

inoperable tumors. One of the main characteristics that

sets IRE apart is its non-thermal mechanism for inducing

cell death; IRE uses a series of short, high-intensity

pulsed electric fields (PEFs) to destabilize the cellular

membrane, which in turn disrupts homeostasis and leads

to cell death [1]. Recently, the next generation platform

known as high frequency irreversible electroporation (H-

FIRE) has emerged with the potential to induce an ablated

lesion which more closely resembles the solution to the

Laplace’s equation used in the computational modeling of

these electroporation treatments [2].

The work presented here used a syngeneic murine ovarian

cancer model representative of different stages of the

disease [3] and comprises the first study to evaluate the

use of H-FIRE to treat ovarian cancer.

METHODOLOGY

Three dimensional tumor models made up of collagen I

were used to determine cell death threshold from IRE and

H-FIRE. The death region was imaged by fluorescent

microscopy where live cells express enhanced green

fluorescent protein (eGFP) and dead cells do not. Lesion

sizes were measured and compared to numerical models

developed in COMSOL Multiphysics 4.3a to correlate the

lesion size to the electric field induced in that region as

described by Arena et al [4]. The results included here

represent a sample size of n=3 for each type of treatment.

RESULTS

IRE and H-FIRE successfully killed cancer cells in the 3D

tumor constructs. The highly aggressive cells and the

chemo-resistant CSCs have similar susceptibility to IRE

and malignant tumor cells are preferentially killed over

healthy cells with H-FIRE type of pulses.

Figure 1. Comparative analysis of H-FIRE results

CONCLUSIONS

IRE, and particularly H-FIRE are shown to successfully

treat ovarian cancer. The ability of H-FIRE to

preferentially kill highly resilient TICs indicate the

potential to completely eradicate both local disease and

maybe even micrometastases, thus preventing the need for

complete organ resection which would render the patient

sterile.

ACKNOWLEDGMENTS

This work was supported by the NSF IGERT DGE-

0966125 (MultiSTEPS, now BIOTRANS)

REFERENCES

1. Davalos, R.V., et al., Ann Biomed Eng, 2005.

2. Bhonsle, S.P., et al., Biomed Eng Online, 2015.

3. Roberts, P.C., et al., Neoplasia, 2005.

4. Arena, C.B., et al., Biophys J, 2012.



PELVIC ANATOMICAL CHARACTERIZATION AND COMPARISON BY SEX AND HISTORY OF PREGNANCY

Mona Saffarzadeh1,2

, R. Caresse Hightower1,2


1. Virginia Tech-Wake Forest University Center for Injury Biomechanics,

2. Wake Forest University School of Medicine, Biomedical Engineering Department,

Corresponding Author: Ashley Weaver, Email: [email protected]

INTRODUCTION

Pelvic shape and size is different among never-pregnant,

pregnant and postpartum women. The pelvis of pregnant

women is wider anteriorly and narrower posteriorly than

that of never-pregnant women. This could cause

lumbopelvic pain during pregnancy [1]. In addition, the

female pelvis has evolved for childbirth so it is larger and

wider than the male pelvis and has a rounder pelvic inlet.

The variations in male and female pelvic anatomy could

cause difficulty in some procedures such as colorectal

surgery. Quantification of the pelvic anthropometry sex

differences can be used to develop virtual and physical

models of the anatomy for surgical planning, medical

device design testing, and diagnosis and treatment of

abnormalities that represent extremes from population

norms. The objective of this study was to generate pelvic

shape and size comparisons by sex and by girth from

existing computed tomography (CT) and magnetic

resonance (MR) images in the radiology database at Wake

Forest Baptist Medical Center.

METHODOLOGY

CT and MR scans of the pelvic region were

retrospectively obtained for 7 females and 13 males of

various sizes and pregnancy history. A semi-automated

image segmentation algorithm was used to segment the

pelvic girdle and sacrum from CT and the bladder, colon,

prostate, uterus, vagina, mesorectum, connective tissue

adjacent to the mesorectum, and the iliacus, pelvic floor,

and psoas muscles from MR (Figure 1). The

segmentations were smoothed and refined using

automated techniques to produce a high quality 3D

geometrical model of each anatomical structure. Rigid

registration that applies translation and rotation

transformations was used to register the bony structures

(pelvic girdle/sacrum) from CT to the MR coordinate

system. This produced a patient-specific composite model

containing the pelvic girdle, sacrum, and the soft tissue

structures for each of the 20 subjects.

RESULTS

This study developed detailed models of anatomy

representing pelvic variation in 10 average males, 3 obese

males, 6 females with history of pregnancy and 1 female

without history of pregnancy (Figure 1).

Figure 1: Pelvic/sacrum CT scan segmentation (left) and

the 3D virtual model (right).

CONCLUSIONS

Findings from this research could significantly contribute

to the treatment of pregnancy-related pelvic pain. Results

could be used to develop computational models (finite

element models and CAD models) of pelvic anatomy to

represent average and extreme anatomical cases in the

population. This study could also improve device design

and surgical planning for colorectal surgery by

considering sex differences. Additionally, this study could

improve device design and surgical planning for

colorectal surgery by considering sex differences. Lastly,

the image analysis pipeline can be used to develop both

general and personalized models of anatomy for disease

management including colorectal surgical procedures and

pregnancy-related lumbopelvic pain.

REFERENCES

[1]. Yamaguchi et al., “Comparison of Pelvic Alignment

among Never-Pregnant Women, Pregnant Women, and

Postpartum Women”, J. of Women’s Health Care, 2016.



EFFECTS OF FEBUXOSTAT ON SOCIAL INTERACTION AND REPETITIVE GROOMING IN AUTISM MICE

Vince Sannicalos1, Molly Accord

2, Jaegu (Richard) Yea

3, Sukyoung (Chloe) Kim

4, Jamelle Simmons

5, and Yong Woo Lee

5

1. Virginia Tech, School of Neuroscience

2. Virginia Tech, Department of Chemical Engineering (ChemE)

3. Virginia Tech, Department of Biological Systems Engineering (BSE)

4. Virginia Tech, Department of Biochemistry

5. Virginia Tech, Biomedical Engineering and Mechanics (BEAM)

Corresponding Author: Jamelle Simmons, Email: [email protected]

INTRODUCTION

Autism spectrum disorder (ASD) is a developmental

disability estimated to effect 1 in 68 children. Individuals

are affected in the areas of communication, interactions,

and behavior with symptoms developing early in

childhood [1]. Research by Zoroglu et al has found

elevated levels of xanthine oxidase (XO) in ASD patients

[2]; research in our lab has also noted elevated expression

of XO in juvenile ASD mice. We hypothesize that

treatment with febuxostat, a potent XO inhibitor, can lead

to decreases in brain damage and improvements in

behavior.

METHODOLOGY

Juvenile and adult C57BL/6J (B6) control, BTBR T+

ltpr3<tf>/J (BTBR) autism, and 129S1/SvImJ (129S1)

male mice were housed at Virginia Tech Carilion

Research Institute (VTCRI). B6 and BTBR strains (3-7

weeks of age) were housed individually while 129S1

strains (3-8 weeks of age) were housed in groups. Mice

were acclimated for 3-7 days before testing began. For

this preliminary study, a sample size of 5 mice per control

and experimental group was chosen. B6 and BTBR

control mice were dosed intraperitoneally with a vehicle

solution of PBS and 5% DMSO at a rate of 100uL/10g of

body weight for 1 week after acclimation. B6 and BTBR

experimental mice were dosed with the vehicle solution

plus febuxostat (10mg/kg) at a rate of 100uL/10g of body

weight for 1 week after acclimation. Behavioral testing

for social preference, repetitive grooming, and locomotive

impairments was conducted at the end of the dosing

period. Dihydroethidium (DHE) staining was carried out

on juvenile brain tissues to determine if the XO inhibitor

reduced oxidative stress levels.

RESULTS

Locomotive testing for sedative effects of injected

compounds, social approach analysis testing for

preference between demonstrator mice (129S1) and

empty cup, repetitive grooming analysis, and DHE

staining all showed no statistically significant differences

between mice groups in the adult and juvenile mice. It

was noted that repetitive grooming, an obsessive-

compulsive disorder (OCD) behavior, in the juvenile ASD

mice was decreased compared to the other groups. This

trend was not seen in adults (Table 1).

Table 1: Summary of Repetitive Grooming

Group Juvenile Grooming

(Sec, Mean ± SE)

Adult Grooming

(Sec, Mean ± SE)

B6_Vehicle 40.7 ± 9.87 28.5 ± 11.4

B6_Febuxostat 34.4 ± 12.8 ----

BTBR_Vehicle 58.9 ± 20.8 23.7 ± 2.56

BTBR_Febuxostat 19.69 ± 1.49 29.94 ± 9.54

CONCLUSIONS

Due to the sample size of each group for the preliminary

study statistical significance was not obtained but trends

in the data were noticed, especially with repetitive

behaviors in male juvenile mice. Repetitive grooming in

ASD mice leading to loss of hair is an OCD behavior that

has face validity to OCD in some autistic patients.

ACKNOWLEDGMENTS

We would like to thank the Virginia Tech ICTAS Center

for Engineered Health (CEH), Center for Autism

Research (VTCAR), and Dr. Alexei Morozov for

financial support and use of facilities.

REFERENCES

[1] Community Report on Autism 2016. Centers for

Disease Control and Prevention, 2016. Web.

[2] Zoroglu, S., Armutcu, F., Ozen, S., Gurel, A., et al.

(2004). Eur Arch Psychiatry Clin Neurosci, 254: 143-147.



OPTICAL FIBER BASED IMAGING OF BIOENGINEERED TISSUE CONSTRUCT

Etai Sapoznik1,2

, Guoguang Niu2, Peng Lu

3, Yu Zhou

2, Yong Xu

3, Shay Soker

1,2

1. Virginia Tech-Wake Forest Univ. School of Biomedical Engineering and Sciences

2. Wake Forest Institute for Regenerative Medicine

3. Virginia Tech, Bradley Department of Electrical and Computer Engineering

Corresponding Author: Etai Sapoznik, Email: [email protected]

INTRODUCTION

Imaging cells and tissues through opaque and turbid

media is challenging and presents a major barrier for

monitoring maturation and remodeling of bioengineered

tissues. The fiber optics based imaging system described

here uses local excitation for fluorescent cell imaging

through opaque scaffolds. The objectives of this study

included: (1) Assessing the effects of imaging system

parameters on image reconstruction outcomes (2)

Identifying the impact of physical parameters on image

outcome (3) Adapting the system for specific live cell

imaging applications

METHODOLOGY

Micro imaging channel (MIC) was embedded in

electropsun scaffolds made of Polycaprolactone (PCL)

and collagen co-polymers. The MIC was used for

insertion of single mode fiber for laser light local

excitation (blue-450nm; green-532 nm; red-660). Scaffold

were seeded with fluorescent beads and fluorescently

labeled cells and placed in an imaging chamber

containing cell culture media (DMEM). The sample stage

was shifted to allow for multiple excitation points in the

scaffold. The emitted signal was detected by EM-CCD

detector, which was used to reconstruct an image of

fluorescent emission distribution. Images were compared

with control image CCD. Initially, fluorescent beads

(green and far-red) were used to develop the

reconstruction process and to assess image reconstruction

outcomes. Image analysis was performed to identify

beads location and assessing contrast to noise ratio (CNR)

and resolution. Subsequently, fluorescently labeled

endothelial and muscle progenitor cells (MPCs) were

used to assess coverage of the scaffold’s surface and cell

differentiation, respectively. . In the third part MS1 cells

labeled with FP and muscle progenitor cells from GFP

transgenic mouse were seeded on scaffolds and imaged.

RESULTS

Imaging system parameters had a mixed impact on image

outcome. While an increase in laser power had a small

impact on the beads CNR, the reconstruction window size

had a strong influence on the CNR with increased

detection region of 1.9 mm2 best detection compared with

smaller window size. Physical parameters had a clear

impact on imaging results. Increase in thickness led to

decrease in CNR. Far-red beads gave better CNR

compared with green beads. Collagen led to slight

decrease in CNR for far-red beads, while the background

noise was stronger than the green beads signal. When

used with labeled cells, the imaging system can identify

individual cell nuclei (fig 1a) on scaffold comparable to

epifluorescent image (fig 1b). Also, it detected MPC

elongation and cell fusion (fig 1c).

Figure 1: MS1 coverage (a) epifluorescent (b) recon;

MPC (c) control and reconstructed images with time

CONCLUSIONS

Imaging system parameters could have an impact of the

image outcomes and may need to be adjusted for specific

applications. The fiber imaging platform has the potential

for imaging through scattering material layers while

considering a specific fluorescent spectra. This imaging

tool is useful for imaging individual cells in resolution of

up to 15 µm, and can identify morphological changes.



TRANSITIONAL LIVER MODELS FOR THE INVESTIGATION OF CHEMICAL AND

MECHANICAL CUES DURING THE PROGRESSION OF FIBROSIS

Scott-Eugene Saverot1, Sophia Orbach

2, Andrew Ford

2, Padmavathy Rajagopalan

1, 2, 3


2. Virginia Tech, Department of Chemical Engineering

3. Virginia Tech, ICTAS Center for Systems Biology of Engineered Tissues

Corresponding Author: Scott-Eugene Saverot, Email: [email protected]

INTRODUCTION

Hepatic fibrosis is the accumulation of scar tissue as a

result of excessive extracellular matrix (ECM) deposition

during chronic liver injury.1 Continued perturbation leads

to stiffer tissues, the distortion of hepatic architecture,

increased blood flow resistance, and ultimately organ

dysfunction. The Space of Disse (SoD) is a protein-

enriched region which separates layers of cells in the liver

and becomes transformed during fibrosis.1 The

interactions between healthy and fibrotic cell populations

as well as the altered environment regulate fibrotic

progression. Integrating gradient biomaterials with in

vitro liver models can simulate different degrees of the

fibrotic environment.

METHODOLOGY

Detachable polyelectrolyte multilayers (PEMs) were

prepared through a layer-by-layer deposition of

hyaluronic acid and type 1 collagen on poly-

tetrafluoroethylene substrates. PEMs could be modified to

contain a mechanical gradient or surface bound pro-

fibrotic proteins.

Primary hepatocytes were cultured as a monolayer upon

which a PEM was placed and non-parenchymal cells

subsequently seeded.2 This model recapitulates the liver

tissue structure and incorporates degrees of fibrosis

through the PEM’s properties (Figure 1).

Figure 1: Schematic of a transitional liver model

simulating three degrees of fibrotic transformation.

RESULTS

The activation of HSCs (principal fibrosis-associated cell

type) was investigated upon PEMs with a mechanical

gradient and presence of additional protein cues.

Increased early HSC activation was observed on the

stiffer sides of PEMs through GFAP staining, in all

conditions at 48h (Figure 2). PEMs conjugated with

laminin show an overall decrease in activation, while

HMGB1 shows comparable results to unmodified

controls. Hepatocytes in 3D cultures experienced

significant increases in apoptosis on stiff sides at 24 and

72h. In 3D co-cultures with HSCs, hepatocyte viability

was increased 4- and 3-fold at 24 and 72h, respectively.

Figure 2: 48h staining of HSC activation in co-culture

with LSECs on mechanical gradient PEMs

CONCLUSIONS

The PEM mechanical gradient was shown to affect all cell

types within the transitional liver model. Stiffer substrates

induced greater hepatocyte cell death and HSC activation.

Transitional models provide a tool to investigate the

complex cell-cell interactions during fibrotic progression.

REFERENCES

1. Arias, I.M., et al., The Liver: Biology and Pathology,

5th

Edition, 2009.

2. Larkin, A.L., et al., Tissue Engineering Part C:

Methods, 2013.

Poster B: Latham B, 11:15 Nanobioengineering 84


DIFFUSION MODEL ACROSS A BLOOD-BRAIN BARRIER (BBB) MIMIC FOR THE TREATMENT OF

AUTISM SPECTRUM DISORDER (ASD)

Jamelle Simmons1, Luke Achenie

2,3, and Yong W. Lee

1,3

1. Virginia Tech, Department of Biomedical Engineering and Mechanics (BEAM)

2. Virginia Tech, Department of Chemical Engineering

3. Virginia Tech Center for Autism Research (VTCAR)

Corresponding Author: Jamelle Simmons, Email: [email protected]

INTRODUCTION

Autism spectrum disorder (ASD) is a neurodevelopmental

disability estimated to effect 1 in 68 children [1]. A

majority autism cases are idiopathic (unknown cause)

with a minority being linked to genetic mutations. With

the prevalence rates for ASD rising from 1 in 150 children

and 2000 to 1 in 68 children in 2010 accompanied by the

rising healthcare costs the economic burden of the

disorder and its prevalence are only expected to worsen

[1,2].

Research by Zoroglu et al has found elevated levels of

xanthine oxidase (XO) in ASD patients [3]; research in

our lab has also noted elevated expression of XO in

juvenile ASD mice. We hypothesize that the uptake of

lipophilic XO-inhibitors, such as febuxostat, can lead to

decreases in brain damage resulting in behavioral

improvements in individuals. Currently we are

researching the diffusion of fluorescein isothiocyanate

(FITC) across the blood-brain barrier (BBB) as a model

of febuxostat transport.

METHODOLOGY

Human brain microvascular endothelial cells (HBMECs)

were cultured in multi-well dishes until confluent.

Monolayers were incubated with FITC for varying time

durations and diffusion quantified by fluorescence

measurements. Partial Differential Equation (PDE)

simulations were run to determine an effective diffusion

(Deff) constant that yielded results similar to in vitro

experimental data. A portion of the in vitro data was used

to construct the computational model (calibration set) and

the model was validated against the remaining data

(validation set).

The simulated HBMEC monolayer thickness was held

constant at 1 micron and the effective diffusion constant

was varied across the range of 1 x 10(-21)

cm2/sec to 1 x

10(-19)

cm2/sec. A t-Test was used to compare the

experimental and simulated results to determine plausible

combinations of variables returning non-significant p-

values.

RESULTS

The results of the simulation (table 1) show that a

plausible effective diffusion constant could be found

between 1 x 10(-21)

cm2/sec to 1 x 10

(-20) cm

2/sec for both

calibration and validation data sets.

Table 1: P-value of Simulations vs Experimental Results

1 x 10

(-21)

cm2/sec

1 x 10(-20)

cm2/sec

1 x 10(-19)

cm2/sec

Calibration

(p-value) 0.036 0.838 0.018

Validation

(p-value) 0.091 0.705 0.089

CONCLUSIONS

Working under the assumption of passive diffusion for

FITC we are able to quantify the amount of tracer that

was transported into the HBMEC monolayer. Additional

studies would be needed to determine if passive diffusion

is a valid assumption but if true, this model could be used

to run predictive simulations of febuxostat transport

across the BBB.

ACKNOWLEDGMENTS

Virginia Tech Center for Autism Research (VTCAR)

REFERENCES

[1] Community Report on Autism 2016. Centers for

Disease Control and Prevention, 2016. Web.

[2] Lavelle, T., Weinstein, M., Newhouse, J., Munir, K.,

Kuhlthau, K., & Prosser, L. (2014). Pediactrics, E520-9.

[3] Zoroglu, S., Armutcu, F., Ozen, S., Gurel, A., et al.

(2004). Eur Arch Psychiatry Clin Neurosci, 254: 143-147.



A SIMPLE TARGETED METHOD FOR THE REMOVAL OF FREE HEMOGLOBIN

Kelli N. Simms1, Martin Guthold

2, Daniel B. Kim-Shapiro

2, Elaheh Rahbar

1

1. Department of Biomedical Engineering, Wake Forest School of Medicine, Winston Salem, NC

2. Department of Physics, Wake Forest University, Winston Salem, NC

Corresponding Author: Elaheh Rahbar, Email: [email protected]

INTRODUCTION

Over 14 million blood transfusions occur in the US each

year, with red blood cell (RBC) transfusions being the

most common.1 Despite significant improvements in

blood banking, several studies have revealed a decline in

morphological and functional changes of RBCs with

prolonged storage. Mechanisms for this decline include

hemolysis, storage lesions, bacterial contamination, and

apoptosis.2

Elevated levels of RBC hemolysis results in

the increase of free hemoglobin (Hb) which can cause

adverse reactions and has been associated with poor

patient outcomes. Free Hb is known to activate platelets,

both in vitro and in vivo, as well as scavenge nitric

oxide.3,4

Therefore there is a need for an effective method

to remove hemolysis from bagged blood products prior to

transfusion, especially in older RBCs where hemolysis

and storage lesions are more prevalent. Herein, we

propose a quick, targeted method to remove free Hb using

magnetic agarose beads.

METHODOLOGY

Hemolysate preparation: Packed RBCs were washed with

phosphate-buffered saline (PBS) three times by

centrifugation. Washed RBCs were then vortexed and

frozen at -80°C to lyse the cells. This solution was then

centrifuged at 17,211g to create a pellet of the cell

membranes. Bead Preparation: Magnetic Agarose beads

were purchased from ThermoFisher Scientific (cat. No.

78609). Beads were washed with PBS and then incubated

with anti-hemoglobin antibody (ab116628) for one hour

at room temperature under gentle rocking. Hemolysis

Removal: Labeled beads were then incubated with 0.01-

1mM hemolysate solution for one hour at room

temperature under gentle rocking. The bead complex was

then removed by applying a magnetic field. The

concentration of hemolysate before and after incubation

was determined using a ThermoFisher Scientific

NanoDrop 2000c Spectrophotometer. The concentration

of free hemoglobin was obtained from the absorbance

peak at 414nm, as well as the hemoglobin curve at 500-

600nm.

RESULTS

Magnetic agarose beads were effective in removing small

amounts of free hemoglobin from solution, producing up

to 59% hemoglobin removal in a 100μl of 0.25 mM

hemolysate solution (Figure 1).

CONCLUSIONS

Anti-Hb labeled magnetic agarose beads were shown to

effectively remove Hb from small volumes of hemolysate.

Future work is needed to adapt this method for large

volume removal and to ensure that labeled beads do not

interfere with RBCs.

ACKNOWLEDGMENTS

I would like to acknowledge funding from Dr. Rahbar’s

start-up funds and Dr. Kim-Shapiro’s NIH grant R01

HL098032 for supporting this work.

REFERENCES

1. Centers for Disease Control and Prevention, 2011.

2. Tuo WW et al. PLoS ONE. 2014, 9(8):e105692.

3. Donadee C et al. Circulation. 2011, 124:465-76.

4. Helms CC et al. J Thromb Haemo. 2013, 11: 2148-54.

0

0.5

1

1.5

300 400 500 600

No beads

0.001mL

0.002mL

Figure 1. Removal of Hb with magnetic agarose

beads. A 32% Hb removal was observed with 1μl

of bead slurry, and 59% with 2μl of bead slurry.



USING VIDEOTAPED MOTION CODING TO IMPROVE UNDERSTAND OF F-NIRS SIGNAL CHANGES

Ben Stephens1, Amnah Eltahir

2, Stephen LaConte

3, and Stephanie DeLuca

3

1. Virginia Tech Carilion School of Medicine

2. Virginia Tech, Biomedical Engineering

3. Virginia Tech Carilion Research Insitute

Corresponding Author: Ben Stephens, VTCSOM Email: [email protected]

INTRODUCTION

Functional near-infrared spectroscopy (f-NIRS) is a non-

invasive neuroimaging technique that has application in

the pediatric population due to its safety and ease of use.

However, questions remain about the technology with

regard to its validity and reliability in accurately

measuring neural signals in the presence of motion

(targeted and non-targeted). Video coding of motion

events during scanning may provide new insights into f-

NIRS signals and help interrogate usable signals.

METHODOLOGY

Six children (mean age 14 months) participated in

videotaped f-NIRS sessions that included the collection of

resting-state and motor-task data. Video sessions were

coded for upper-extremity movements that were

translated into a time-in-motion outcome measure. These

were then compared to corresponding f-NIRS signals

across 5-second time blocks with a goal of identifying

segments of high and low signal variance.

RESULTS

Correlations between upper extremity time in motion and

signal variance for corresponding 5 second blocks ranged

from 0.0898 to 0.258 (p<0.01). F-NIRS signal responses

in high-motion blocks appeared to result in decreased

signal quality, while f-NIRS signal response in low-

motion blocks were marked by appropriate hemodynamic

response and negative correlation between oxy- and

deoxyhemoglobin signals.

CONCLUSIONS

Video coding behavior offers new possibilities for

interpreting f-NIRS signals during f-NIRS recordings

with infants. Further study is required to analyze the

validity of our findings and explore other motion events,

both targeted and non-targeted, on f-NIRS signal

characteristics.

ACKNOWLEDGMENTS

VTCRI Neuromotor Research Clinic

The LaConte Lab Team at VTCRI

REFERENCES

Cristia, A., Dupoux, E., Hakune, Y., Lloyd-Fox, S.,

Schuetze, M., Kivits, J., & Minagawa-Kawai, Y. (2013).

An online database of infant functional near infrared

specstroscopy studies: a community-augmented

systematic review. PloS one 8(3), e58906.

Goodwin, J.R, Cannaday, A.E., Palmeri, H.G., Di

Constanzo, A., Emberson, L.L., Aslin, R.N., & Berger,

A.J. (2016). Methodology for high-yield acquisition of

functional near-infrared spectroscopy data from alert,

upright infants. Neurophotonics, 3(3), 031415-031415.

Nishiyori, R. (2016). fNIRS: An emergent method to

document functional cortical activity during infant

movements. Frontiers in psychology, 7.



CALCULATION OF THE DIFFUSIVE PERMABILITY OF CELL MEMBRANES TO PROPIDIUM

Daniel C. Sweeney1, James C. Weaver

2, Rafael V. Davalos

1

1. Virginia Tech, Dpeartment of Biomedical Engineering and Mechanics

2. MIT, Harvard-MIT Division of Health Sciences and Technology

Corresponding Author: Daniel C. Sweeney, Email: [email protected]

INTRODUCTION

Electroporation has become a staple technology in

biomedical sciences in recent years. It is used to deliver

drugs and genetic information to cells in research and

clinical settings and for processing of food and water in the

agricultural industry. However, the mechanisms

underpinning electroporation have not been thuroughly

investigaed through experimentation and there exists a gap

between computational models [4] and experimental results

[1,2]. Here, we aim to provide experimental estimates of

the net diffusive permeability of the cell membrane to

normally impermeant propidium ions following insult with

an electrical pulse [3]. Our analysis shows that the diffusive

permeability stabilizes to a non-zero value. We intend these

results to be widely applicable to the validation of

computational models and further enhance the current

understanding of electroporation.

METHODOLOGY

The mean fluorescence intensity of the nuclei of CHO-K1

cells inside a microfluidic chamber containing 5 μg/ml

propidium in one of three different mediums was

measured. Cells were exposed to electrical pulses of

widths 0, 1, 10, 100, and 1000 μs that generated electric

field intensities of 175, 250, 325, and 400 kV/m. Each

image sequence contained a pre-treatment control image

and immediately following treatment and with one image

acquired every minute for 30 minutes thereafter.

RESULTS

Figure 1: Parameter space of diffusive permeability of

propidium ions through the cell membranes of CHO-K1

cells (a.) and the final permeability different electric fields

(b.).

The CHO-K1 cells seeded in the microfluidic chamber

had a surface area of 1738.22 ± 1071.02 μm2 and volume

of 1804.83 ± 571.09 μm3. This allowed the calculation of

the diffusive permeabilities of propidium showing in

Figure 1.

Table 1: Electroporation Media Properties

Medium Osmolarity

(mOsm)

Conductivity

(S/m) pH

PBS 278 1.01 7.2

SFDF 306 0.93 7.2

HEPES 310 0.08 7.2

The net diffusive permeability propidium of cells

immersed in PBS, SFDF, and HEPES. The analysis

indicates that the diffusive permeability stabilizes at a

value that depends on the applied pulse width and local

electric field intensity in the minutes following

electroporation treatment.

CONCLUSIONS

We show that the diffusive permeability of propidium

ions through the cell membrane can be estimated using

calibrated fluorescence microscopy and that it stabilizes

following electroporation treatment at non-zero values.

ACKNOWLEDGMENTS

The authors would like to acknowledge the NSF

CAREER Award CBET-1055913 for support for this

work.

REFERENCES

[1] SM Kennedy et al., Biophys J (2008).

[2] PJ Canatella et al., Biophys J (2001).

[3] KC Smith, et al., Bioelectrochemistry (2013).

[4] DC Sweeney, et al., Biochim Biophys Acta -

Biomembr (2016).



REAR IMPACT CRASHES IN THE UNITED STATES: HOW DANGEROUS ARE THEY?

Whitney M. Tatem1 and H. Clay Gabler

1


Corresponding Author: Whitney Tatem, Email: [email protected]

INTRODUCTION

One of the most common crash modes on roadways

world-wide are rear end collisions. The National Highway

Traffic Safety Administration (NHTSA) has reported that

approximately 2 million rear end crashes occurred in the

U.S. in 2014 (NHTSA 2016). Despite this large number

of crash occurrences, rear impact crashes are generally

viewed as a benign crash mode with property damage

only and at most minor injuries. However, in 2015, there

were almost 1000 fatalities in cars and light trucks that

were struck in the rear. The question becomes, if rear

impacts are indeed a benign crash mode, what is leading

to these fatalities?

The objective of this study is to investigate the

characteristics of serious-to-fatal rear impact crashes and

to identify the underlying crash features that may lead to

serious or fatal injury for occupants seated in rear-

impacted vehicles.

METHODOLOGY

The analysis examined fatal rear crashes extracted from

the Fatality Analysis Reporting System (FARS) 2011-

2015 and serious-to-fatally injured occupants in the

National Automotive Sampling System/Crashworthiness

Data System (NASS/CDS) data from case years 2000-

2015. The FARS analysis first investigated all crashes in

which a passenger vehicle was rear struck. A follow-on

analysis was then conducted limiting the dataset to model

year 2000 and greater passenger vehicles to focus the

analysis on vehicles which were more likely to have been

designed for the new Federal Motor Vehicle Safety

Standard (FMVSS) 301, Fuel System Integrity - a

structural integrity test in the rear impact crash mode.

To better understand the nature of the fatalities studied in

FARS, detailed case reviews were conducted of all fatally

to seriously injured rear-struck occupants in the

NASS/CDS data. Our analysis examined seriously injured

occupants, as our hypothesis was that the factors which

led to fatal injury might also have been present at lower

injury severity crashes in which the occupant survived the

impact.

RESULTS

There appear to be three mechanisms leading to serious-

to-fatal injury: (1) catastrophic collapse of the occupant

compartment, (2) impacts with hard vehicle interior

components, e.g. the B-Pillar, and (3) thoracic loading

from the seat, especially on older occupants. All three

injury mechanisms present themselves in each injury

severity category, both fatal, severe, and serious. There

appears to be a continuum where compartment collapse is

most often associated with fatal injuries, direct head

contact produces predominantly severe injuries, and

thoracic loading appears more related to serious injuries.

This study is the first step in a research effort to explore

the factors that lead to a higher injury risk in rear impact

crashes. The next steps will be to expand this study to a

more comprehensive analysis of rear structural response

and seat performance to gain a fuller understanding of the

injury mechanics in rear crashes, and to determine the

priority for countermeasure development.

CONCLUSIONS

This study has investigated the factors associated with

serious-to-fatal rear crashes. Despite the perception that

rear crashes are benign, over 1000 rear-struck occupants

were fatally injured in 2015. Compartmental collapse

appears to be a major risk factor in rear impact crashes,

particularly for occupants seated in the rear seats. The

vast majority of fatal crashes appeared to involve

compartmental collapse although other injury

mechanisms such as direct head contact to rigid interior

vehicle structures and thoracic loading from the seat

should not be disregarded.

REFERENCES

NHTSA. Traffic Safety Facts 2014: A Compilation of

Motor Vehicle Crash Data From the Fatality Analysis

Reporting System and the General Estimation

System.Washington, DC: NHTSA, U.S. Department of

Transportation; 2016. Report No. DOT HS 812 261



A MECHANISTIC EVALUATION OF INTRINSIC CROSSLINKING PROPERTIES AND SYNTHESIS

PROCEDURES FOR KERATIN-BASED MICROPARTICLES

Marc Thompson1, Aaron Giuffre’

2, Mark Van Dyke

1

1. Virginia Tech. Blacksburg, VA, Biomedical Engineering and Mechanics

2. Virginia Tech. Blacksburg, VA, Electrical and Computer Engineering

Corresponding Author: Marc Thompson, Email: [email protected]

INTRODUCTION

Emulsion polymerizations are a long-standing and widely

supported method of synthesizing microparticles from

several material sources. As common practice, the

hydrophobic and hydrophilic nature of a material is

utilized during mixing or agitation to form a stable

colloidal suspension consisting of an immiscible solution

that is later isolated and processed in the form of

microparticles that can then have numerous uses and

applications. This technique is touted for its simplicity,

ease of scalability and relative inexpensiveness. However,

the physical and chemical relationships within the

immiscible liquid itself and between the immiscible liquid

and emulsifier are often not considered or considered

inconsequential due to the assumed simplicity of this

reaction. In this study, we delve further into the physical

and chemical components of microparticle synthesis that

determine key product parameters such as size, shape,

surface topography and mechanical properties for keratin-

based microparticles formed by emulsion polymerization.

METHODOLOGY

Soluble keratose (KOS), derived from human hair (HH)

and wool, were isolated via an oxidation reaction initiated

by paracetic acid and later extracted using a Tris base

solution. The KOS was purified via tangential flow

ultrafiltration against buffer, concentrated, frozen and

lyophilized. The dried powder was reconstituted into

solution and used as the immiscible liquid component for

emulsion polymerization. KOS microparticles were

synthesized under variable solution concentrations, pH’s,

solvents and polymerization crosslinking agents. Physical

examinations of surface topography and microparticle

size were determined with Scanning Electron Microscopy

(SEM) and atomic force microscopy (AFM). Rheological

properties and degradation rates were also measured.

Correlations between material characteristics and

synthesis procedures was obtained.

RESULTS

Keratin microparticles were successfully synthesized

under variable conditions. Intrinsic self-crosslinking

capabilities, solvents, as well as chemical crosslinkers

vary critical properties of microparticles such as size. This

is notable because the difference in length of various

crosslinking agents is small, and would be expected to

give rise to similar length of the crosslinks themselves.

Moreover, all crosslinking agents used have the same

reaction chemistry, and react with the same functional

groups along the protein chain, thereby giving rise to

network structures with similar molecular chain lengths

between crosslinks.

Figure 1: Particle Size analysis of HH KOS synthesized

under various solution conditions.

CONCLUSIONS

Synthesis procedures for emulsion polymerizations that

may have originally been considered minute or

inconsequential are proving to have substantial impacts

on the properties of their products. Such changes can

greatly affect the efficiency and overall usefulness of a

microparticle construct.

ACKNOWLEDGMENTS

The Davis Lab, The Staley Lab, The author acknowledges

the Cunningham Fellowship for funding support.



CELL-SUBSTRATE INTERACTIONS ON CHARACTERIZED KERATIN COATING FOR PERCUTANEOUS

PROSTHETIC APPLICATIONS

Alexis Trent¹, Mark Van Dyke2

¹Department of Material Science and Engineering, Virginia Tech, Blacksburg, VA 2 Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA

Corresponding Author: Mark Van Dyke, Email: [email protected]

INTRODUCTION

Percutaneous osseointegrated prosthetic (POP) consists of

a bone anchored titanium post that extrudes through the

skin and attaches to an external prosthetic. Compared to

the traditional socket interface, POPs offer better stability,

restored limb functionality, and ossieoperception1.

Although the POP surgery technique is well established

the main disadvantage to this technology remains between

the titanium (Ti) - skin interface, some complications that

can arise include epithelial down-growth, mechanical

tearing, and infection2. It is ideal to mimic a junction

similar to the fingernail-skin interface, which is infection-

free and mechanically stable, as a template for the Ti-skin

connection. Using keratin, a protein found in skin, hair,

and nails, we demonstrate keratin on silanized Ti provides

a suitable coating to translate into the Ti-skin interface

intended for POP application.

METHODOLOGY

Both reduced keratin, kerateine (KTN), and oxidized

keratin, keratose (KOS), various silanes (3-

Aminopropyltriethoxysilane (APTES), Glycidoxypropyl-

trimethoxysilane (GPTES), 3-Mercaptoproyltriethox-

ysilane (MPTES), 3- Isocyanatopropyltriethoxysilane

(ICPTES)), and fibronectin (FN) were used in this study.

Surface Characterization: Atomic Force Microscopy

(AFM), X-ray Photoelectron Spectroscopy (XPS), and

Contact Angle were used to analyzed the surface coating

and protein features. Substrate Durability: Substrates

were exposed to several enzymes at 0.15U/mL at 37°C for

various time points. Focal Adhesions and Involucrin:

HaCaT cells were used in cell adhesion studies and were

stained for the involucrin antibody to observe terminal

differentiation. Cellular Motif Detection: Fluorescence

beads were passively attached to integrins α4β1 and αIIbβ3

which were used to label cellular motifs.

RESULTS

Figure 1. HaCaT’s focal adhesion (Columns A-C) were

stained for actin fibers (red), vinculin (green) and the

nucleus (blue). In column D, an involucrin antibody

(green) was observed at 3 hours and nucleus (blue).

CONCLUSIONS

In this study, we can postulate that keratin nanomaterials

can create coatings for percutaneous titanium implants

that are enzymatically stable and maintain biological

function, thus resembling the ideal fingernail-skin

interface.

ACKNOWLEDGMENTS

We would like to thank Sujee Jeyapalina, PhD and Brian

Bennett from the University of Utah for ongoing help.

REFERENCES

[1]A.F. von Recum, Applications and failure modes of

percutaneous devices: a review, J. Biomed. Mater. Res.

18 (1984) 323–336; [2]M. Gerritsen, Problems associated

with subcutaneously implanted glucose sensors, Diabetes

Care. (2000).

91 Biomechanics Poster A: Latham B, 1045


ANALYSIS OF BILIARY STENT HINGES USING ABAQUS

Aaron R. Van Gorkom1, Greg J. Gillispie

1, Clifford Howard Jr

2, Philip J. Brown

1

1. Biomedical Engineering, Wake Forest Baptist Health

2. Wake Forest University Baptist Medical Center

INTRODUCTION

Biliary stents are commonly deployed to open up an

obstruction which limits the drainage of bile into the

duodenum. [1] A common form of failure in roughly 17%

of the cases is stent migration, or the movement of a stent

from its original deployed location [2]. It is important,

then, to design a stent which helps to prevent migration as

well as addressing several other means of failure such as

tissue in growth and over growth. This projects goal was

to expand on previous work done by Wake Forest

Innovations in developing a non-migrating biliary stent,

[3] by performing finite element analysis and

optimization on several hinge designs to hit plastic

deformation strain and stress targets the stent material.

These hinges are involved in the out of plane bending of

hooks located on the distal ends of the stent. The hooks

engage with the surrounding tissue to prevent migration.

METHODOLOGY

In order to optimize the design of the stent hinge, several

profiles were created; these can be seen in Fig. 1. These

designs are intended to distribute the out of plane bending

stress as a flexture mechanism while providing adequate

rigidity over the lifetime of the stent. A naming

convention was used to allow for an iterative testing

process where specific dimensions were varied allowing

for optimization of each hinge based on target criteria. An

example of this is shown in Table 1.

Figure 1: Hinge Designs

Table 1: Naming Convention for Model Simulations

Islet Radius(mm)

Islet Thickness(mm) A=0.04 B=0.05 C=0.06

A=0.02 AA AB AC

B=0.03 BA BB BC

C=0.04 CA CB CC

The hinge models were created using Dassault Systemes’

SolidWorks 2015 and then imported into Simlia’s

Abaqus/CAE version 6.14.2 to run finite element

simulations. A fixed wall boundary condition was applied

to one end of the hinge to simulate a cantilever beam while

a 0.1N force was applied to the opposite end for duration of

2 seconds. The goal of the analysis was to mimic the 55

degree bend angle demonstrated in a previous full stent

model deployment simulation while reaching a target

stress. This target is a stress halfway between the ultimate

and yield stresses of the material. An elasto-plastic

material model based off of stainless steel 316 was used

with the following parameters: Density = 8000 kg/m3;

Young’s Modulus = 193 GPa; Poisson’s Ratio = 0.27;

Yield Strength = 193 MPa. During the simulation, stresses,

strains and displacements were recorded to allow for full

analysis and comparison on hinge performance.

RESULTS

The results of the simulations demonstrated stress

concentrations at the focal bending point of the hinge as

seen in Fig. 2. This aspect of the hinge design allows for

precise control of bending locations.

Figure 2: Barbell Slot and S Hinge Design Results

CONCLUSIONS

This project was able to provide detailed results for several

stent hinge designs, aiding in the overall function and

progression of the Wake Forest Innovations Biliary Stent

model. Detailed stress and strain quantification is underway.

REFERENCES

[1] Dodds et al. Motility of the Biliary System.

[2] Dumonceau et al. Biliary stenting: indications, choice

of stents and results

[3] Mitchell et al. Finite Element Analysis of a Novel

Design for a Non-Migrating Biliary Stent using Abaqus.



LASER INDUCED PRECISION HEATING FOR IMPROVED BACTERIAL DESTRUCTION WITH GENTAMICIN

Kenneth A. Vogel1, Anila Pullagura

1, Nicole Levi-Polyachenko

1

1. Wake Forest University (School of Medicine, Plastic and Reconstructive Surgery)

Corresponding Author: Kenneth A. Vogel, Email: [email protected]

INTRODUCTION

Infections are a significant public health problem, killing

approximately 23,000 annually.1 Some bacterial strains,

such as Methicillin Resistant Staphylococcus Aureus, are

invulnerable to current antibiotics. Therefore, treatments

for increasing the efficacy of antibiotics are desirable.

Previous research has shown that bacterial cultures treated

with antibiotics then heated to 45°C undergo a decrease in

viable bacteria compared to controls which remained at

body temperature.2 However, this required 12 hours of

elevated hyperthermia. It would be beneficial to medical

science to better determine the effects of temperature on

antibiotic killing as well as find a faster heating method.

We propose that the use of a laser to precision heat

bacteria in the presence of the antibiotic gentamicin will

increase bacterial cell death with increasing temperature.

METHODOLOGY

An overnight culture of S. Aureus was produced and

treated with IC50 gentamicin (0.0115 mg/mL). The

samples were incubated for 10 minutes at 37°C before

being treated with k-laser at 5W, 800 nm for 30, 60, and

90 seconds in order to raise the temperature of the

samples to 40°C, 42°C, 44°C respectively before being

incubated at 37°C for 2 hours, serial diluted, and plated

onto agar for overnight incubation followed by counting

colonies.

RESULTS

0

100

200

300

400

500

CFU

/We

ll

No Laser (37°C)

30 s (40°C)

60 s (42°C)

90 s (44°C)

Figure 1: Treatment of S. Aureus with laser irradiation in

absence of gentamicin

0

20

40

60

80

100

120

CFU

/Wel

l

No Laser (37°C)

30 s (40°C)

60 s (42°C)

90 s (44°C)

Figure 2: Decrease in viable S. Aureus with laser

irradiation with gentamicin

CONCLUSIONS

Due to the increased risk of antibiotic resistant bacteria, it

is imperative that new treatments be found to improve

antibiotic effectiveness. We demonstrate that heating

with a laser at 5W and 800 nm can destroy bacterial

populations in a stepwise manner with increasing laser

application time and hence temperature increase.

ACKNOWLEDGMENTS

We would like to thank the Department of Plastic and

Reconstructive Surgery at the Wake Forest University

School of Medicine for their funding of this work.

REFERENCES

1. Sharma, VK, et al. “A review of treatment

strategies on antibiotic resistant bacteria and

antibiotic resistant genes.” Chemosphere.

2016 May;150:702-14

2. Sturtevant, Rachael A. et al. “Thermal

Augmentation of Vancomycin against

Staphylococcal Biofilms.” Shock 2015. 44(2)

121-127.



SHIFTS IN CIRCULATING POLYUNSATURATED FATTY ACID LEVELS IN CHILDREN WITH TRAUMATIC

BRAIN INJURY

Charlotte Mae K. Waits1, Steven C. Kosmach

2, Susan Sergeant

3, Floyd H. Chilton

4, Charles S. Cox, Jr

2, and Elaheh Rahbar

1

1. Department of Biomedical Engineering, Wake Forest School of Medicine

2. Department of Pediatric Surgery, McGovern Medical School at the University of Texas Health Sciences Center at Houston

3. Department of Biochemistry, Wake Forest School of Medicine

4. Department of Physiology and Pharmacology, Wake Forest School of Medicine

Corresponding Author: Elaheh Rahbar, Email: [email protected]

INTRODUCTION

Traumatic brain injury (TBI) is the leading cause of

pediatric death and disability.1,2

Hence, there is a need for

improved TBI treatments. Recent animal studies suggest

omega-3 (n-3) polyunsaturated fatty acid (PUFA)

supplements containing docosahexaenoic acid (DHA) are

neuroprotective and have the potential to facilitate TBI

recovery.1-3

Human studies, however, have yielded mixed

results and there is continued debate over PUFA

supplementation. In this study, our goal was to quantitate

circulating PUFA levels over time following TBI to better

understand the role of n-3 PUFAs in pediatric TBI.

METHODOLOGY

Leveraging on Phase II Clinical Trial (NCT01851083),

plasma was obtained from 9 pediatric TBI patients at 0, 3,

5 and 180 days post-enrollment. Fatty acid levels were

determined as methyl esters using gas chromatography

with flame ionization detection (GC-FID) or separated

into lipid classes by thin layer chromatography before

GC-FID. Inflammatory cytokines, IL-4, IL-6, IL-10 and

IFNg were quantified using ELISAs. Statistical tests were

used to evaluate associations between PUFAs, cytokines

and patient outcomes.

RESULTS

Children with TBI displayed significantly reduced DHA

plasma levels relative to omega-6 (n-6) PUFA

arachidonic acid (ARA), resulting in lower DHA/ARA

ratios (Figure 1) and greater imbalances in plasma n-3 and

n-6 PUFAs across all time points. Interestingly,

circulating ARA levels and DHA/ARA ratio correlated

strongly with IL-4, which in turn associated with longer

hospital stays. Shifts in complex lipid pools, particularly

from free fatty acids to cholesterol esters and triglycerides

were observed over time and were associated with injury

resolution.

Figure 1: Reduced plasma DHA/ARA ratios in pediatric TBI

patients compared to healthy values (dashed line) from the

literature.4 Bars represent mean±SEM.

CONCLUSIONS

Children with TBI demonstrated significant changes in

circulating PUFAs as well as shifts in complex lipid pools

that were associated with TBI recovery. The association

between DHA/ARA ratio and IL-4 provides a potential

therapeutic mechanism for n-3 PUFAs in pediatric TBI

recovery. Larger studies are needed to determine how n-3

PUFAs mitigate inflammation and facilitate neuronal

tissue repair.

ACKNOWLEDGMENTS

Special thanks to Barbara Kim, Leslie Miller, and Edward

Kirby, Jr. who assisted with PUFA analysis. We also

acknowledge funding from NIH grants: R01NS077963,

P50AT002782, R01AT008621 and Dr. Rahbar’s startup

funds for supporting this project.

REFERENCES

1. Schober ME, et al. J Neurotrauma. 2016;33(4):390-402.

2. Barrett EC, et al. Adv Nutr. 2014;5(3):268-277.

3. Hasadsri L, et al. J Neurotrauma. 2013;30(11):897-906.

4. Steer CD, et al. Hum Mol Genet. 2012;21(7):1504-1512.



HIGHLY SPECIFIC AND MODULAR AFFINITY LABELING OF EPIGENETIC MODIFICATIONS

Fanny Wang1, Osama K. Zahid

1, Brandi E. Swaibe

2, and Adam R. Hall

1,3

1. Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences

2. Wake Forest University, Department of Physics

3. Wake Forest University School of Medicine, Comprehensive Cancer Center

Corresponding Author: Adam R. Hall, Email: [email protected]

INTRODUCTION

DNA epigenetics play an important role in the

development and progression of a variety of diseases.

These base modifications are dynamic, occurring in

response to chemical exposure and other environmental

cues, but do not result in a change in the genetic

sequence, and thus can be difficult to assess. Here, we

present a modular affinity labeling method for epigenetic

modifications based on the DNA repair mechanisms

found in normal cells. With this procedure, it is possible

to tag specific epigenetic modifications with an affinity

label at single base resolution for enrichment or detection.

METHODOLOGY

Synthetic double-stranded DNA oligos containing a single

modified base and end-labeled with a fluorescent tag

(FAM) were used. For these experiments, three different

modifications were targeted: uracil, 8-oxoguanine, and

thymine-guanine mismatch. Each construct was incubated

for 1 hour at 37°C in the presence of modification-

specific glycosylase and an endonuclease to excise the

epigenetic modification. Subsequently, molecules were

incubated for 30 minutes at room temperature in the

presence of DNA polymerase and a single type of

biotinylated nucleotide appropriate for the modification.

Labeled molecules were then incubated in the presence of

monovalent streptavidin for 10 minutes at room

temperature to induce specific binding. Solid-state (SS-)

nanopore measurements were performed using a 8 nm

diameter nanopore and across a range of applied voltages.

RESULTS

The ability of the DNA repair enzymes to replace

epigenetic modifications with a biotinylated nucleotide

was demonstrated with the three modifications being

studied (Figure 1). SS-nanopore measurements showed

selective detection of labeled molecules due to steric

hindrance with the pore and demonstrated direct

quantification and high sensitivity.

Figure 1: Denaturing gels demonstrating biotin labeling

of three epigenetic distinct modifications. The first

column in each set is the initial material, the second the

material after incubation with glycosylase, and the third

the material after incubation with DNA polymerase.

CONCLUSIONS

This research demonstrates the viability of using DNA

repair enzymes to label epigenetic modifications in DNA.

Our approach can be extended to a wide variety of

additional modification types based on enzyme

specificity. In addition to SS-nanopore analysis, labeled

material could also be isolated/enriched with streptavidin

beads for quantification, sequencing, and other analysis.

ACKNOWLEDGMENTS

We thank M. Howarth (Oxford), D. Parsonage (Wake

Forest University), and T. Hollis (WFU) for providing

materials and J. Ruzicka (High Point University) for

contributions to this project.

REFERENCES

1. Ashkenazi R., doi:10.1593/neo.08572

2. Burrows C.J., doi: 10.1038/ncomms9807

3. Ciccia A., doi:10.1016/j.molcel.2010.09.019

4. Dekker C., doi:10.1038/nnano.2007.27, 2007



FABRICATING AND TUNING AN ELASTOMERIC BLOOD VESSEL FOR USE

IN CORONARY ARTERY BYPASS SURGERIES

Harleigh J. Warner1 and William D. Wagner

1.

1. Plastic and Reconstructive Surgery and School of Biomedical Engineering and Sciences, Wake Forest University

School of Medicine, Winston-Salem, NC

Corresponding Author: Harleigh Warner, Email: [email protected]

INTRODUCTION

Autologous saphenous vein is the standard material for

bypassing small diameter (<6mm) coronary arteries, but is

subject to intimal hyperplasia, thrombosis, and

accelerated atherosclerosis. To date, no biomaterial

functions as a substitute for vein graft. We have recently

developed an endovascular biomaterial, PFC, composed

of electrospun poly-(glycerol sebacate), silk fibroin, and

type 1 collagen. The hypothesis is that PFC can be

improved through conditioning by cell deposited matrix

and bioactive molecules.

METHODOLOGY

Preparation of PFC materials: PFC materials were

fabricated by electrospinning a 10% w/v ratio of 1:4.5:4.5

PGS: Silk Fibroin: Type 1 collagen in 1,1,1,3,3,3,

hexafluoroisopropanol. PFC mats were subsequently heat

treated at 120°C for 48 hours and gluteraldehyde vapor

treated for 24 hours to cure PGS and crosslink collagen

fibers, respectively. Fabrication of PFC/ECM materials:

NIH3T3 fibroblasts were cultured on the PFC treated with

fibronectin for 7 days at a density of 5x105 cells/cm

2.

Materials were subsequently decellularized with 0.25%

Triton X-100, 10mM NH4OH, and 50 U/mL DNase.

Fabrication of a porous PFC material: A more porous

PFC material was fabricated by co-electrospinning

sacrificial poly (ethylene oxide) (PEO) fibers (PFC:PEO

50:50) and altering the post-electrospinning protocol to

allow leaching of PEO fibers.

RESULTS

Light microscopic and SEM images of the PFC/ECM

material showed evidence of ECM accretion on PFC

materials after decellularization (Fig 1A). DNA removal

was confirmed by PicoGreen assay (n=3) (Cell 11.4 ±

4.16 ng DNA, Decell 2.68 ± 1.95 ng DNA, No Cell

1.55±0.77 ng DNA) and protein accretion was shown by

BCA assay (n=3) (Cell 5.75 ± 1.01 μg protein, Decell

2.71± 0.24 μg protein, No cell 1.98± .58 μg protein).

HUVEC cells cultured on PFC/ECM mats showed

significantly greater proliferation than cells grown on

PFC alone (Fig. 1B). Porous PFC showed less dense fiber

morphology in SEM images (Fig. 1 C, D). PFC and

porous PFC had identical fiber morphology.

A B

C D

Figure 1. A) SEM image of PFC with cell deposited

ECM (PFC/ECM) B) Cellular proliferation as measured

by MTS assay of HUVEC cells cultured on Tissue culture

plastic (TCP) PFC, PFC exposed to decellularization

protocol (PFC Decell) and PFC with cell derived

extracellular matrix (PFC ECM), C) PFC material, D)

Porous PFC material after PEO fibers were leached.

CONCLUSIONS

A tuned artery material with ECM from NIH3T3 cells

was fabricated in order to provide improved mechanical

and functional properties. These studies exhibit that a

PFC material with variable pore size can be fabricated.

ACKNOWLEDGMENTS

Research was funded by Harold S. Geneen Charitable

Trust Awards Program For Coronary Heart Disease and

The Department of Plastic and Reconstructive Surgery

Research at Wake Forest University Medical School.

0.0

0.2

0.4

0.6

TCP PFC PFCDecell

PFCECM

OD

Day 2Day 5



A RAT MODEL OF SEVERE OSTEOPOROSIS FOR TESTING BONE REGENERATION CONSTRUCTS

Michele Waters1, Nils Potter

1, Marc Thompson

1, Alexis Trent

2, Pamela VandeVord

1 and Mark Van Dyke

1 1. Virginia Tech, Biomedical Engineering and Mechanics

2. Virginia Tech, Materials Science and Engineering

Corresponding Author: Michele Waters, Email: [email protected]

INTRODUCTION

Osteoporosis is an imbalance in the normal state of bone,

which is marked by bone loss. Although previous

research in this field has focused on prevention and

treatment of osteoporosis, fractures and poor healing of

bone still occur at high rates. Brittle bones cause patients

to be more prone to fracture, which may result in reduced

quality of life. Falls are the most prevalent cause of injury

deaths and non-fatal injuries among older Americans.

Many preclinical studies employing regenerative

approaches to bone regeneration in osteoporosis models

use ovariectomy (OVX) to induce hormonal deficiency

that results in changes in bone characteristics. However,

investigators have generally used a time period between

OVX and bone defect (e.g. fracture or critical size defect)

creation ranging from as little as 3 weeks to 4 months,

which is too short to induce the same changes seen in the

clinical population. In this study, an OVX induction

protocol was used to maximize the severity of

osteoporosis. Biomaterial scaffolds containing growth

factors were used to investigate the healing potential for a

critical size segmental femur defect.

METHODOLOGY

All procedures were performed under protocols approved

by the IACUC. 48 female Lewis rats underwent OVX at

24 weeks of age and were held for an additional 8 weeks

by the vendor. At 32 weeks of age, the rats were

transferred to Virginia Tech and held for a minimum of

62 additional weeks before rat femur defect surgery.

Femur defects (excision of 8mm segments) were created

using our previously published surgery protocol.[1]

Following successful surgeries, animals were maintained

on the study for up to 16 weeks to monitor bone

regeneration, using CT. In cases of failed surgery, animals

were immediately euthanized.

RESULTS

A total of 19 of 48 surgeries were unsuccessful (39.6%).

Complications were largely related to the extremely

brittle nature of the bone. Long-term fixation was

achieved in only 4 animals. In these rats, bone

regeneration had occurred, but the tissue was badly

misshapen and of poor quality. The bone volume to total

volume ratio (BV/TV), connectivity, inner bone

perimeter, and average cross-sectional area were

significantly decreased in osteoporotic contralateral and

injured rat femurs compared to normal bones, (Figure 1).

Figure 1: a) CT Images and b) Bone Connectivity

CONCLUSIONS

Our approach resulted in a model that more accurately

reflects one of the most challenging scenarios for which

bone tissue engineering technologies are being developed.

The severity of the osteoporosis was profound, and it

created extreme bone brittleness as well as other

complications. While many studies use juvenile rats, the

rats in this study were hormone deficient for a minimum

of 15 months (~2 years old at the end of the study). In the

future, we plan to explore the possibility of using a defect

model involving a non-weight bearing bone (e.g. skull) to

evaluate the potential of biomaterial scaffolds to facilitate

wound healing in a model of severe osteoporosis.

ACKNOWLEDGMENTS

We would like to acknowledge the NIH for funding this

study.

REFERENCES

[1] de Guzman RC, Saul JM, Ellenburg MD, Merrill MR,

Coan HB, Smith TL, Van Dyke ME. Bone regeneration

with BMP-2 delivered from keratose scaffolds.

Biomaterials 2013;34(6):1644-56



NON-INVASIVE DETECTION OF RESPIRATION AND HEART RATE WITH A VEHICLE SEAT WEIGHT

SENSOR: A FEASIBILITY STUDY

Grace C. Wusk1 and Hampton C. Gabler

1

1. Virginia Tech, Biomedical Engineering

Corresponding Author: Grace C. Wusk, Email: [email protected]

INTRODUCTION

Advanced Automatic Collision Notifications (AACN)

have great potential for reducing mortality risk in car

crashes. AACN however, relies exclusively on vehicle-

based measures of crash severity from which occupant

crash response can only be estimated [1, 2]. Non-invasive

physiological monitoring of an occupant could prove

extremely valuable in improving occupant safety for both

post-crash emergency response and crash prevention.

Relaying vital signs of the occupants after a crash to the

first responders could help prepare the appropriate

response for transport as well as medical triage. The

purpose of this study was to assess the feasibility of seat

weight sensors in production passenger vehicles to

monitor occupant breathing rate and heart rate.

METHODOLOGY

The seat used in this study was a Ford Mustang front

passenger seat. The weight sensor, which consists of a

fluid filled bladder connected to a solid state pressure

transducer, was connected to a National Instruments

cDAQ-9172 data acquisition system. Benchmark

respiration and pulse measurements were collected with

NeuLog instrumentation. All of the data channels were

sampled at 100 Hz. With the approval of the Institutional

Review Board (IRB), pilot data samples were collected

from four preliminary subjects, two male and two female,

of various weights and heights. The pressure signals were

processed with simple time domain filtering and

frequency domain Fourier analysis to yield respiration

and heart rate. Various peak detection and smoothing

techniques including the windowed peak-to-peak

deviation (WPPD) were also used. The physiological rate

calculations were performed multiple ways for

comparison of average and instantaneous measures.

RESULTS

Figure 1 shows example data in blue from one of the

subjects for one minute of data collection. The breaths are

visible in the raw voltage data in the top row, and the

heart beats are detectable in the bottom row after the data

is filtered and the WPPD is calculated. We have overlaid

the benchmark pulse signal (in arbitrary normalized units)

from the NeuLog pulse sensor in red on the filtered and

WPPD data for comparison. The data was aggregated

across the four preliminary subjects and compared to the

reference measurements, showing good agreement.

Figure 1: Sample raw and filtered data with respiration

rate and heart rate.

CONCLUSIONS

Overall, this study demonstrates the feasibility of using a

seat weight sensor from a production passenger vehicle to

measure occupant respiration and heart rate. This pilot

data provides for initial validation of the non-invasive seat

sensor that may be used in future studies to

physiologically monitor and assess an occupant.

REFERENCES

[1] Kusano, K. and Gabler, H. C. “Comparison and

validation of injury risk classifiers for advanced

automated crash notification systems.” Traffic Inj. Prev.,

vol. 15, pp.126-133, 2014.

[2] Kusano, K. and Gabler, H. C. “Automated crash

notification: Evaluation of in-vehicle principal direction

of force estimations.” Transportation Research Part C

Emerging Technologies, vol. 32, pp. 116-128, July 2013.



INVESTIGATION OF MLL3 COMPLEX IN DNA REPAIR MECHANISM IN LUNG ADENOCARCINOMA

Ted G. Xiao1, Wei Zhang

2

1. Wake Forest School of Medicine, Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences

2. Wake Forest School of Medicine, Department of Cancer Biology

Corresponding Author: Ted Xiao, Email: [email protected]

INTRODUCTION

Increasing efforts have been put forth in exploring post-

transcriptional and translational modifications. Histone

modification is in the center of this increased effort.

MLL3 is a chromatin modifier that facilitates the

deposition of histone 3 lysine 4 mono- and dimethylation

(H3K4me1/me2). MLL3/4 assembles as a complex,

leading to modifications to histone methylation.

A recent study demonstrates a direct connection between

Forkhead box protein A1 (FOXA1) and MLL31. The

results indicate that FOXA1 transcription factor recruits

MLL3 to mono-methylate H3K4 sites at the enhancer. In

another recent study, FOXA1 is reported to associate

DNA repair complexes and DNA demethylation2.

There is a study in Arabidopsis that showed histone

acetyltransferase regulating DNA demethylation3. Given

the frequent occurrences of MLL3 mutation in lung

adenocarcinoma patients4, we hypothesize that histone

methyltransferase protein MLL3/4 plays a crucial role in

FOXA1-associated DNA repair.

METHODOLOGY

Lung Cancer Cell Lines

Three (NCI-H1975, NCI-H522, HCC827) lines have no

MLL3/4 mutations. One line (NCI-H2342) has MLL3

mutation and the other (NCI-H2135) has MLL4 mutation.

The non-mutated lines require RPMI-1640 medium and the

mutant lines require DMEM-F12 medium with supplements.

All cell lines are cultured in standard cell culture conditions.

Cisplatin Treatment and Protein Extraction

Add cisplatin (5mM) to medium at 1:50. Mix the solution

and apply to cell lines. Incubate the cells at 37C for 30-45

minutes. Wash with iced PBS. Make sure to dish is as dry

as possible. Transfer the cell culture dishes onto ice. Add

cell lysis solution and wait 30 minutes at 4C. Scrape off

the lysate and transfer into a microfuge tube. Sonicate at

40% amplitude. Spin in centrifuge at 4C and 15,000 rpm.

Isolate the protein lysate. Store at -80C.

Western Blot

Heat for 5 minutes at 100C and load protein lysates into

pre-cast gel (40μg). Run gel electrophoresis at 60V for 20

minutes and turn up the voltage to 120V for 40-60

minutes. Transfer gel into transfer cassette with PVDF

membrane. Place cassette into transfer box and turn

voltage to 20V at 4C overnight. Use 5% milk for blocking

at 4C on a shaker at 20rpm for >1hr. Add primary

antibody and place on shaker at 20rpm at 4C overnight.

Add corresponding secondary antibody for 1hr. Expose

with Supersignal Chemiluminiscent Substrate.

Transfection

Seed cells onto 6-well culture dish at 60-80% confluency.

Dilute Lipofectamine RNAiMAX Reagent in Opti-MEM

Medium. Dilute siRNA in Opti-MEM Medium. Mix the

two solutions at 1:1 ratio. Incubate at room temperature

for 5 minutes. Add siRNA-lipid complex to cells.

Incubate cells for 1-3 days at 37C before examination.

RESULTS

The expected result based on literatures is a positive

correlation between MLL3/4 expression and DNA repair

activation. If true, the western blot results should show

DNA repair protein expression based on the presence of

MLL3/4. If MLL3/4 are knocked down via siRNA, DNA

repair protein expression is expected to be decreased

compared to control.

ACKNOWLEDGMENTS

The author would like to thank the members of the Zhang

Lab for their help.

REFERENCES

1. Jozwik, K., Chernukhin, I., Serandour, A. (2016). Cell

Reports 17, 2715-2723.

2. Zhang, Y., Zhang, D., Li, Q. (2016). Nature Genetics

48, 1003-1013.

3. Qian, W., Miki, D., Zhang, H. (2012). Science 336, 1445-1448.

4. TCGA data analysis performed in Zhang Lab.



DEVELOPMENT AND VALIDATION OF A GÖTTINGEN MINIATURE PIG FINITE ELEMENT MODEL TO

INVESTIGATE INJURY SCALING TECHNIQUES

Keegan M. Yates1, Costin D. Untaroiu

1

1. Virginia Tech, Center for Injury Biomechanics

Corresponding Author: Keegan Yates, Email: [email protected]

INTRODUCTION

Every year, approximately 1.7 million people in the

United States receive a traumatic brain injury (TBI). In

order to better prevent or mitigate these injuries, several

kinematic injury risk metrics have been developed. The

development of these metrics is dependent on animal

studies because many types of brain injury can only be

seen in living tissue. This presents a challenge, as any

animal data must be scaled to apply to a human brain.

Current methods rely on scaling based solely on the

masses of the brains. Utilizing finite element (FE)

analysis, impacts can be simulated on an animal model,

and injury can be correlated with mesh based factors,

which can then be used as a target to direct an optimized

scaling method.

METHODOLOGY

Prior to this study, Göttingen mini-pigs were given mild

TBIs in an impact device, and the motion of markers

implanted in the interior of the brain was recorded via

biplanar x-ray [1]. An FE model of a pig head was created

by meshing MRI (brain) and CT (skull) scans of a pig.

The pig impacts were recreated with the FE model, and

the in vivo marker data was used to validate the model.

Next, scaling was investigated with the pig model and an

established human brain FE model (GHBMC). First, two

mesh based injury metrics were established. The first was

the cumulative strain damage measure (CSDM), which

was a volume fraction of elements receiving a strain over

2% throughout the duration of the impact. The second

was a volume fraction of elements experiencing a

pressure over 10 kPa. Next, mass based kinematic scaling

[2] was applied to obtain a baseline scaled impact to the

human model. Finally, the scaling factors for linear and

angular motion were adjusted such that the injury metrics

in the scaled human impact matched the pig impact.

RESULTS

It was seen that the baseline mass based scaling greatly

over-predicted the strain to the human brain, while

pressure was slightly below or equal to what was

predicted. Through adjusting the scaling factors, the

injury metrics in the scaled human impact were made

much closer to the pig impact (Figure 1).

CONCLUSIONS

The results have shown that mass based scaling alone can

either over or under-predict certain injury types. While

mesh based injury metrics have not been well established

for this type of mild TBI, this study has shown as a proof

of concept that an FE method can be used to refine injury

scaling. This scaling can be tailored to specific injury

types or loading types, and therefore it has the possibility

of improving prediction of injury in humans.

ACKNOWLEDGMENTS

This research was sponsored by the Takata Corporation.

The experimental data used to construct the pig model

were obtained by Elizabeth Fievisohn.

REFERENCES

[1] E. M. Fievisohn et al., “Evaluation of Impact-

Induced Traumatic Brain Injury in the Göttingen Minipig

Using Two Input Modes,” Traffic Inj. Prev., vol. 15, no.

sup1, pp. S81–S87, 2014.

[2] A. Petitjean et al., “Normalization and scaling

for human response corridors and development of injury

risk curves,” in Accidental Injury, Springer, 2015, pp.

769–792.

Figure 1. Strain (a) and pressure (b) response of

scaled human model compared to the pig model.

a b



NUMERICAL INVESTIGATION OF LOWER EXTREMITY INJURIES IN FRONTAL CRASH RECONSTRUCTION

Xin Ye1,2

, James Gaewsky1,2

, Derek Jones1,2

, Logan Miller1,2

, Mireille Kelly1,2

, Jeff Suhey1,2

, Bharath Koya1,2

,Ashley

Weaver1,2

and Joel Stitzel1,2

1. Wake Forest University School of Medicine

Virginia Tech-Wake Forest University Center for Injury Biomechanics

Corresponding Author: Xin Ye, Email: [email protected]

INTRODUCTION

Lower extremity injuries are the most frequent

Abbreviated Injury Scale (AIS) 2 injury for drivers in

frontal crashes [1]. The objective was to reconstruct

eleven real-world motor vehicle crashes (two with AIS 2+

distal lower extremity injury and nine without lower

extremity injury) to analyze the vehicle parameters and

driver attributes that affect injury risk.

METHODOLOGY

Eleven frontal crashes were reconstructed with a finite

element simplified vehicle model (SVM) using a semi-

automated optimization method. The SVM was tuned to

each corresponding vehicle and the Total HUman Model

for Safety (THUMS) v4.01 was scaled and positioned in a

baseline configuration to mimic the documented pre-crash

driver posture. The event data recorder crash pulse was

applied as the boundary condition for each case.

Additionally, for each of the eleven cases, 120 simulations

to quantify the uncertainty and response variation were

performed varying the following parameters using a Latin

Hypercube design of experiments (DOE): seat track

position, seatback angle, steering column angle, steering

column position, and D-ring height. Injury metrics

implemented within THUMS were calculated from the

femur, tibia, and ankle, and cross-compared among the

eleven baseline cases using tibia index and multiple injury

risk functions. Kinetic and kinematic data from the 120

simulation DOE were analyzed and fit to regression models

to examine causal relationships between occupant

positioning and lower extremity injury risks.

RESULTS

Of the eleven real-world crashes, both cases with lower

extremity injuries resulted in elevated tibia axial forces and

resultant bending moments, compared to the nine cases

without lower extremity injury. The average tibia index of

the two cases with distal lower extremity injury (left: 1.79;

right: 1.19) was higher than the nine cases without lower

extremity injury (left: 1.16, p=0.024; right: 0.82, p= 0.024).

An increased risk of AIS 2+ tibia shaft (33.6%), distal tibia

(20.0%), and ankle (14.5%) fracture was also observed for

the injured compared to the non-injured cases. Rearward

seat track position, reclined seat back angle and reduced

seat height were correlated with elevated tibia axial force

and increased tibia index, imposing additional lower

extremity injury risk (Figure 1).

Figure 1: Linear regression of lower left tibia index

versus seat track position for Camry DOE. Red circle

indicated the baseline case.

CONCLUSIONS

This study provides a computational framework for assessing

lower extremity injuries, and elucidates the effect of pre-

crash driver posture on lower extremity injury risk while

accounting for vehicle parameters and driver attributes.

Results from the study aid in the evaluation of real-world

injury data, the understanding of factors contributing to

injury risk and the prevention of lower extremity injuries.

ACKNOWLEDGMENTS

Funding for this project was provided by Toyota’s

Collaborative Safety Research Center.

REFERENCES

[1]Ye X. et al., Accident Analysis& Prevention. 2015, 83:37-46.

101 Cardiovascular Engineering Poster A: Latham B, 10:45

Figure 1: Pre-sorting, brightfield and red-

fluorescence (left) and after-sorting, brightfield and

red-fluorescence (right) (10X).

Figure 2: Primitive vessel formation in a collagen

matrix (left, 20X) in basic 2D co-culture (Right, 10X)


PERICYTE CELL LINE ISOLATION, VALIDATION AND APPLICATIONS

Huaning Zhao1, John C. Chappell

1,2

1. School of Biomedical Engineering and Science

2. Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute

Corresponding Author: John C. Chappell, Email: [email protected]

INTRODUCTION

Pericytes, also known as perivascular or mural cells,

envelope the outer surface of vascular endothelial cells

and play a key role in microvessel homeostasis. Pericyte

functionality in healthy and pathological conditions has

recently gained significant attention, as numerous studies

have found that pericyte dysfunction or loss of pericytes

indicate the beginning of vascular diseases, such as in

diabetic retinopathy and neurodegenerative conditions.

However, isolation and validation of a pericyte cell line

has remained a challenge since no specific genetic marker

exists. In my research, I have isolated an enriched

population of pericytes from mouse embryos. I validated

this cell line using several expression and functional

assays, and applied these cells in experiments of basic

vessel development. I found that these cells displayed

similar functions as endogenous pericytes, and they

appear to uniquely contribute to vessel development.

METHODOLOGY

A pericyte cell line was isolated from NG2:DsRed

transgenic mouse embryos at embryonic day 13.5 (E13.5),

using Fluorescence Activated Cell Sorting (FACS). These

cells were cultured in Pericyte Media for expansion, and

stored in liquid nitrogen at passage 2 (p2). As a primary

cell line, this cell line was validated to maintain normal

proliferation and morphological features until p10. In

subsequent experiments, we used cells between p3-6.

RESULTS

From images taken before and after FACS, we found that

both the density of cells with DsRed fluorescence and the

intensity of the DsRed signal were higher after FACS (Fig

1). From quantitative analysis of cell density, the

concentration of pericytes was found to increase almost

three fold after FACS.

In validation experiments, I compared the morphology

and gene expression of these cells with a related but

distinct cell type, mouse embryonic fibroblasts (MEFs).

Several lines of evidence suggest that these cell lines are

indeed distinct cell types. In addition, I applied these

exogenous pericytes to vessels forming in differentiated

mouse embryoid bodies, mouse embryonic back skin

(E13.5) and compared them with endogenous pericytes.

Our results suggest that our pericyte cell line displays

similar morphology and function features in embryoid

body-derived blood vessel development as endogenous

pericytes. They also readily engage developing blood

vessels and are morphologically similar to endogenous

pericytes on a tissue level (embryonic back skin E13.5). I

cultured these cells with Human Umbilical Vein

Endothelial Cells (HUVECs) and found unique aspects to

their contribution to primitive vessel development (Fig 2).

CONCLUSIONS

This pericyte cell line has been validated, and can be used

to better understand embryonic vessel development, as

well as pericyte dysfunction in different pathology-related

culture conditions (e.g. hypoxia, hyperglycemia, etc.).

ACKNOWLEDGMENTS

Members of the Chappell Lab, and my mentor, Dr. John

Chappell.

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