[[Systemic genotoxic effect caused by ischemia-/reperfusion-/surgical trauma of the lower extremity--detection of DNA chain breaks in leukocytes with the Comet Assay]].

Ischemia-reperfusion-injury (IRI) represents a fundamental common pathway of tissue damage in a wide variety of disease processes, i.e. myocardial infarction, septic or hemorrhagic shock, multiple organ failure, trauma and organ transplantation. IRI is said to be initiated by leukocyte accumulation and adhesion to vascular endothelium as well as oxygen free radicals (OFR) playing a pivotal role in the pathogenesis of ischemia-reperfusion-injury. However, only few data exist for measuring influence of toxic OFR on DNA in humans. To assess the potential genotoxicity the single-cell gel electrophoresis (COMET assay) of white blood cells was used in BTB-operated humans before and after 0, 5, 15, 30 and 120 min of tourniquet-ischemia of the lower limb (n = 20). We show that tourniquet-ischemia (60-170 min) significantly increased the tailmoment measuring the DNA-damage in the operated limb to 173.4% (median in % baseline (bl); Q0.35: 149.9%; Q0.75: 214.5%; p < 0.01 vs bl) and in the systemic circulation to 157.8% (Median in % bl; Q0.25: 136.8%; Q0.75: 174.8%; p < 0.01 vs bl). These results indicate that the IRI induces a local and systemic oxidative damage in white blood cells resulting in DNA strand breaks indicating an overwhelming of the antioxidative barrier of circulating human leucocytes.