Search for: [Abstract = "The thrombin – mediated conversion of plasma fibrinogeninto fibrin and the formation of clots relatively resistant to fibrinolysis are the final steps in the blood coagulation. Abalance between clot formation and fibrinolysis largely determines clot stability. A fibrin clot composed of compact fibrin fiber networks, resistant to fibrinolysis, predisposes to arterial and venous thrombotic events. Reduced fibrin clot permeability and impaired fibrinolysis have been reported in patients with myocardial infarction, ischemic stroke, but also in patients with venous thromboembolism. Retinal vein occlusion \(RVO\) is the most common primary retinal vascular disease. Its pathogenesis is not fully understood. Depending on thrombus location, there are two main types of RVO\: branch retinal vein occlusion \(BRVO\) and central retinal vein occlusion \(CRVO\). The data on the association between known thrombophilic factors and RVO are inconsistent. The aim of this study was to evaluate ex vivo structure and properties of plasma fibrin clots in patients who experienced RVO. We enrolled 59 consecutive patients with diagnosed RVO \(26 females, 33 males, aged 54.95 ± 11.04 years\) and 59 control subjects matched forage, sex, body mass index \(BMI\), medications, and cardiovascular risk factors. A mean time from the diagnosis to enrolment was 14.4 ± 9.9 months \(range, 5–36 months\).The diagnosis of RVO was based on the presence of typical findings in the fundus of the eye documented in digital photography, fluorescein angiography, and opticalcoherence tomography.The University Bioethical Committee approved the study \(KBET\/114\/B\/2008\). In all patients complete ophthalmology examination was performed and we measured lipid profile, glucose, alanine aminotransferase \(AlAT\), creatinine, total homocysteine, Creactive protein \(CRP\), fibrinogen, tissue plasminogen activator antigen \(tPA\), plasminogen activator inhibitor\-1antigen \(PAI\-1\), activated partial thromboplastin time \(APTT\), and prothrombin time \(PT\). In RVO patients thrombophilia screening was done. Moreover, ex vivo fibrin clots obtained from citrate plasma samples were used for the measurement of clot permeation, expressed as the permeability coefficient, Ks \(Darcy constant\). Turbidity offibrin clot formation, reflected by the lag phase of theturbidity curve and maximum absorbency at plateau\(ΔAbmax\), tPA – induced fibrinolysis characterized bymaximum rates of increase in D\-dimer levels \(D\-Drate\) andmaximum D\-dimer concentrations \(D\-Dmax\) wereevaluated. The time required for 50% decrease in maximumclot absorbency \(t50%\) was chosen as an additional markerof the clot susceptibility to fibrinolysis after simultaneous addition of thrombin and recombinant tPA to plasma."]

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