AB

ST

RA

CT

S

Abstracts of ISHR Auckland Workshop

Investigating Image Processing Techniques for MeasuringSarcomere Length in Isolated Cardiac Trabeculae

Alex Anderson, Poul Nielsen, Andrew Taberner

Auckland Bioengineering Institute, The University of Auckland,Auckland, New Zealand

An investigation was performed into the viability offrequency-domain image processing techniques for

application to bright-field images of isolated cardiac tra-beculae. Real-time, hardware-based data processing wasused to compute the average sarcomere length in a cardiactrabecula undergoing stretch to and beyond the nor-mal physiological limit of 2.4 �m. The average sarcomerelength was estimated; its standard error was found to betypically approximately 10 nm.

STIU. We show that myocardial enthalpy change (ener-getically equivalent to VO2) is linearly correlated withboth SLA (= U + W) and STIU + STIW, with comparablecorrelation coefficients. Since only measurement of stressis required, (STIU + STIW) is an attractive alternative forassessing myocardial energetics.

http://dx.doi.org/10.1016/j.hlc.2012.08.011

Proteomic Analysis of Aortae from Human Lipoprotein(a)Transgenic Mice

S.P.A. McCormick

Department of Biochemistry, Otago School of Medical Sciences,University of Otago, Dunedin

http://dx.doi.org/10.1016/j.hlc.2012.08.010

Proportionality Between Components of Stress-LengthArea and Components of Stress-Time Integral

J.-C. Han 1, A.J. Taberner 1,3, K. Tran 1, D.P. Nickerson 1,M.P. Nash 1,3, P.M.F. Nielsen 1,3, E.J. Crampin 1,3, D.S.Loiselle 1,2

Elevated low density lipoprotein [LDL] and lipopro-tein(a) [Lp(a)] levels are independent risk factors for thedevelopment of coronary artery disease (CAD). We used aproteomic approach to investigate the expression of arte-rial proteins in transgenic mice containing both humanLDL and Lp(a) in circulation compared to wildtype mice.Plasma lipoprotein analysis indicated that the transgenicmice had elevated LDL and HDL cholesterol compared towildtype mice. Histological analysis of aortae revealed an

1 Auckland Bioengineering Institute, The University of Auck-land, Auckland, New Zealand2

accumulation of Lp(a) in the transgenic mice but no lipidaccumulation or foam cells, leaving the arteries essentiallyatherosclerosis free. Comparative proteomics using two-

Departments of Physiology, The University of Auckland,

Auckland, New Zealand3 Engineering Science, The University of Auckland, Auckland,New Zealand

Myocardial stress-length area (SLA), and its 3-dimensional equivalent (pressure-volume area, PVA),consist of two components: external work (W) and poten-tial energy (U), where U lies to the left of W. Underconditions of various preloads and afterloads, SLA (andPVA) have been shown to be linearly correlated with oxy-gen consumption (VO2). But, the linear relation itself isindependent of preload and afterload, making SLA a valu-able mechanical probe to assess myocardial energetics.We have found a simplified version of SLA. Instead ofsimultaneous measurement of both muscle twitch stressand length, our analysis requires only measurement ofmuscle twitch stress, based on our findings that W andU are proportional to components of stress-time integral(STI); U is proportional to the area under the twitch-time profile (STIU), whereas W is proportional to thearea bound by the relaxation limbs of the ejecting con-traction and isometric contraction (STIW), to the right of

dimensional gel electrophoresis and MALDI-TOF/TOFmass spectrometry identified 34 proteins with significantlyaltered abundance (p < 0.05) in the aortae of transgenicmice compared to wildtype including 17 with a ≥ 2 fold dif-ference. Some of these proteins showed a similarly alteredabundance at the transcript level. These changes collec-tively indicated an initial metabolic response that includeda down-regulation in energy, redox and lipid metabolismproteins, as well as changes in structural proteins. Ourstudy reveals that a pro-atherogenic lipoprotein profilepromotes metabolic disturbances that precede the devel-opment of atherosclerosis in mice.

http://dx.doi.org/10.1016/j.hlc.2012.08.012

1443-9506/04/$36.00http://dx.doi.org/10.1016/j.hlc.2012.08.009