Floor plan - 2013 Annual Meeting - American Association for Hand ...

ASRM POSTERS PRESENTATIONS
Concentration of NO in the Postischemic Muscle under Different Levels of Oxygen Free
Radicals
Institution where the work was prepared: Plastic Surgery Charité Campus Mitte Humboldt University, Berlin,
Germany
Rolf Buettemeyer, MD, PhD1; Felix Stoffels1; Moritz Beisenhirtz2; Fred Lisdat, PhD3; (1)Charité, Humboldt University,
(2)University of Potsdam, (3)Wildau University of Applied Sciences
Reperfusion of ischemic skeletal muscle is associated with an alteration of the concentrations of 02- and N0. In this study, the influence
of EGCG, a known radical scavenger, on the balance of 02- and NO has been measured on-line in the skeletal muscle of wistar rats.
The hind limb of 14 male rats had been exposed to ischemic stress for 2 h. 7 rats received an infusion of 1,5 µmol EGCG/kg 5 min.
before reperfusion. 02-, NO and temperature were measured during reperfusion. The concentration of 02- declined under the influence
of EGCG from 156.5 nmol/l to 72.2 nmol/l (p=0.01). The level of NO was found to decrease; this decrease was not significantly
changed by EGCG (-175 nmol/l vs. – 227 nmol/l; p=0.33). Thus the different superoxide concentrations did not correspond to different
levels of NO and the interaction of both radicals is not the only reason for the concentration decrease of NO in the reperfusion period.
We conclude that EGCG protects skeletal muscle from I/R-injury without influencing the NO concentration profile to a large extent.
Gene Expression Analysis and Biomarker Discovery in a Rat Model of Free Flap Failure
Institution where the work was prepared: R Adams Cowley Shock Trauma Center, Baltimore, MD, USA
Suhail Mithani; Rachel Bluebond-Langner; Eduardo D. Rodriguez; Johns Hopkins School of Medicine
BACKGROUND:
Free tissue transfer is a potent tool in reconstructive surgery, but has a failure rate of up to 10%. Identification of failure relies on clinical
assessment of flap viability which lacks sensitivity for early failure. Flap failure is likely preceded by altered gene expression; however,
use of a broad based genome wide approach to identify potential biomarkers and therapeutic targets has not been described. In this
study, an RNA expression microarray identified genes whose expression is altered in a rat model of free flap failure.
METHODS:
A well described rat model of free tissue transfer, with a pedicle based upon the inferior epigastric artery and microvascular anastomosis
of the femoral vessels, was utilized. To model early failure, the venous pedicle was occluded with a vessel loop after anastomosis to
simulate the most common cause of flap failure. After 6 hours a portion of the flap was excised from both early failure and control groups
and RNA extracted. Gene expression of 3 samples in each of the experimental groups was assessed with the Affymetrix GeneChip Rat
230 v2.0 microarray, yielding expression data for over 28,000 genes. Quantitative reverse transcription polymerase chain reaction (qRT-
PCR) was performed on genes identified by microarray analysis on RNA extracted from all harvested tissue.
RESULTS:
890 genes had greater than twofold expression differences between the early failure and control groups. Student's t-test and ANOVA
filtering identified 53 genes with statistically significant expression differences. Hierarchical clustering by gene ontology identified 4
genes with likely involvement in the pathogenesis of flap failure. These are RT1 class II, locus Bb (RT2Bb,58.64 fold upregulation), secreted
frizzled-related protein 1 (SFRP1, 2.06 fold upregulation), platelet/endothelial cell adhesion molecule (PECAM, 2.67 fold downregulation),
Claudin 5 (CLDN5, 3.42 fold downregulation). Validation was performed by qRT-PCR on separate control and early failure animals
(n=7 in each arm). RT2Bb, PECAM, CLDN5 had statistically significant alterations of expression in the early failure group. Utilizing
expression thresholds for test positivity of these genes, venous occlusion was predicted with 100% sensitivity and 86% specificity.
CONCLUSIONS:
Using a genome wide expression tool, 3 novel genes were identified with altered expression in an animal model of early free flap failure.
Expression levels of these genes predict early flap failure with high sensitivity and specificity. This pilot study validates this method,
and identifies 3 genes which warrant further study as potential diagnostic and therapeutic targets in free flap failure.
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