3414 Free radicals are produced in the retina during ischemia-in vivo electron spin resonance study in the rabbit

A poor anticoagulant response to activated protein C (APC r&stance) induced hy the ArglGln8g8 mutation of the Factor V gene is, in ssversl countries, the most oommon genetic defect sssootatsd with thmmbophilic disorders. Frequencies of APC resistance between 2050% have teen observed in pstients with deep venous thrombosis, SugQedinQ the importance of the Pmtein C System acttvity. Also, in other thrombotic sttusttons ss myoomtQsl infarction or thrombosis of cerebral vessels, APC resistsncs has been occasionally referred. In s previous study, we have found s prevalence of 1.5% (QS%IC 0.31 _ 4.32) for APC resistance. in the genersl portuguese Csucsstsn population. PurposeThe aim of the present study is to evstoste the prevslenco of APC resistance in one group of patients with retinal vein occlusion (FrVO) where the contribution of the Protein C system is controversial end the mls of APC resistance not yet estsbtitied. Methods: In all psttents, APC ratio (Chromogenix COATEST APC resistance M in s bioM&iewc Hemotab msgulometer) and Fsotw V gene mutation (PCR and Ynll digestion) were determined aocotiing to the reoommended fvotocols. The cut off point of 2.5 for APC ratio achieves the best agreement between phenotypic and QetIOtypiC data. We have studied 52 consecutive unrelated patieots wtth en history of RVO deftned by Hsyreh’s ortterta. Resuk: None of the observed pstients canted the mutation and the APC rstio meanrSD wss of 4.12 f 0.83 However, one patient had so APC ratio of 1,7. Conclusions: The frequencies found in the studied group sre identical to those of the general population. In this wsy APC msNtsnce. Uoes not play s major role in the possible thrombophilic component in RVO.