Sickle Cell Hemoglobin

Lisa Ho & Praise AustinDr. Robin W. Briehl

Albert Einstein College of Medicine

Red Blood Cell Round disc shape Transports oxygen

Sickle Cell Trait Sickle Cell Disease

Abnormal sickle shape Rigidity Cell Damage & Cell-Cell

Adhesion Hemolysis & Anemia

Background

Glutamic Acid Valine Deoxygenation Hydrophobic Interaction Polymerization into Stiff

Fibers Distorts shape & rigidifies

cells Induces Vaso-Occlusion

Fibers

Sickling

http://www.dailymotion.com/video/xacdyf_sickling-and-unsickling

Video camera Zeiss light microscope DIC Optics Epi-illumination light source

for photolysis of HbCO Potassium Phosphate buffer

(pH 7.2 at 0.1 M concentration)

Blood or Hb solution sample Gel sample

Methods

Fiber Visualization using 546nm light source

Differential Interference Contrast Microscopy

Can visualize objects smaller than diffraction limitation size

Splits the light into two different light beams

Wollaston prism The phase image facilitates

visualization of the fibers.

DIC Microscopy

VCR

Image Processor

Video Camera

Barrier Filter

Analyzer

546nm observation

436nm photolysis

Dichroic mirror

Hg arc

Field Diaphragm

Exciter Filter

CO

Hg arc

Wollaston prism

SlideWollaston prism Polarizer

I. The epi-illumination light source was activated

II. The light Intensity was altered to produce desired amount of deoxygenation and therefore of polymerization.

Mechanism

COHbS + hv HbS + CO

ProcedureEpi - illumination

Homogeneous Nucleation and Growth of Sickle Fibers

http://www.dailymotion.com/video/xacduc_copy-of-homogrow

Heterogeneous Nucleation and Fiber Growth

http://www.dailymotion.com/video/xacdss_heterogeneous-nucleation_school

Mechanism of DepolymerizationEnd - Depolymerization

http://www.dailymotion.com/video/xacdwi_endmelt

Help decipher how polymers grow and dissolve

Aim:Inhibit growthFacilitate dissolution

Implications

Increase the delay time Conduct Rheological tests on Lab

grown Gels Clinical Studies on various

therapeutic treatments

Future

Enbury, S. H., Hebbel, R. P., Mohandas, N. & Steinberg, M. H. (1994). Sickle cell disease: basic principles and clinical practice. New York: Raven Press Ltd.

Dickerson, R. E. & Geis, I. (1983). Hemoglobin. California: The Benjamin/ Cummings Plublishing Company, Inc.

Wang, J. C., Turner, M. S., Agarwal, G., Kwong, S., Josephs, R., Ferrone, F. A. & Breihl, R. W. (2002). Micromechanics of isolated sickle cell hemoglobin fibers: bending moduli and persistence lengths. Journal of Molecular Biology, 315, 601-612.

Agarwal, G., Wang, J. C., Kwong, S., Cohen, S. M., Ferrone, F. A., Josephs, R. & Breihl, R. W. Sickle hemoglobin fibers: mechanisms of depolymerization. Journal of Molecular Biology, 322, 395-412.

Ferrone, F. A. (2004). Polymerization and sickle cell disease: a molecular view. Microcirculation, 11:2, 115-128

Breihl, R. W. (1997). Sickle cell hemoglobin. Encyclopedia of human biology, (Second Edition, Vol. 8, pp. 1-20). New York, Academic Press Inc.

Anfinsen, C. B., Edsall, J. T., Richards, F. M. & Eisenberg, D. S. (1987). Advances in protein chemistry. New York, Academic Press Inc.

References

Professor Robin W. Briehl, MD

Jiang Cheng Wang

Suzanna Kwong

Albert Einstein College of Medicine &

Staff

Dr. Sat Bhattacharya

Harlem Children Society

The audience

Acknowledgements

Any questions?

Thank you