CONTROL OF BLOOD ACTIVATION DURING OPEN HEART SURGERY

血液与伤口和体外循环(CPB)系统生物材料的接触会激活五个血浆蛋白系统和五个血细胞，产生细胞毒素、血管活性化学物质和酶，从而介导心脏直视手术(OHS)的出血、血栓和炎症并发症。这一建议的基本原理是，了解CPB和OHS期间血液蛋白质和细胞反应的机制，确定在CPB期间暂时抑制的特定酶和激活的细胞靶点。选择潜在的抑制剂的特定假设是基于这种机制的知识。我们使用模拟体外循环(SECC)对从生化特性分析中选择的潜在抑制剂进行初步测试。体外灌流回路由0.4m2螺旋线圈膜氧合器、滚柱泵和储存袋组成，用于在通常37℃的温度下使新鲜的肝素化人类血液再循环2-6小时。我们还使用了一个正在修改的狒狒模型，其中包括一个皮下隧道来模拟伤口。之所以选择狒狒，是因为大约90%的人类抗体与狒狒蛋白和细胞发生交叉反应；因此，该模型既健壮又高效。我们和其他人之前的工作已经证明了这种方法在纤溶药物使用中的原理，并建议使用Etibatide来保护血小板(见进展报告)。该项目的重点是抑制凝血酶原酶复合体的形成，补体激活以及中性粒细胞、单核细胞和血小板的激活。其中一个目标是抑制凝血酶的形成。先前的研究表明，抑制凝血酶原酶复合体的形成是必要的。我们计划单独或联合研究一种紧密结合的新的凝血因子Xa抑制剂、凝血因子IXAI抑制剂和重组组织因子途径抑制剂。抑制中性粒细胞和单核细胞活化的主要途径是环磷酸腺苷、环磷酸鸟苷和特异性磷酸二酯酶抑制剂(PDE)。我们还将研究使用合成肽抑制中性粒细胞和单核细胞Mac-1受体的结合，以努力抑制细胞激活。最后，我们计划研究两种潜在的补体激活抑制剂，它们通过不同的方法防止C3的裂解。由于CPB和OHS期间的血液反应通常是相互依赖的，我们计划研究我们认为将发挥协同作用的抑制剂的组合。

Blood contact with the wound and biomaterials of the cardiopulmonary bypass (CPB) system activates five plasma protein systems and five blood cells to produce cytotoxins and vasoactive chemicals and enzymes that mediate the bleeding, thrombotic and inflammatory complications of open heart surgery (OHS). The rationale of this proposal is that under- standing mechanisms of blood protein and cellular reactions during CPB and OHS identifies specific enzyme and activated cellular targets for temporary inhibition during the period of CPB. A specific hypotheses for selection of potential inhibitors is based on this knowledge of mechanisms. We use simulated extracorporeal circulation (SECC) for initial testing of potential inhibitors chosen from analysis of biochemical properties. The in vitro perfusion circuit consists of a 0.4M2 spiral coil membrane oxygenator, roller pump and reservoir bag to recirculate fresh heparinized human blood for 2-6 hours usually at 37 degrees C. We also use a baboon model that is being modified to include a subcutaneous tunnel to simulate a wound. The baboon is chosen since approximately 90 percent of human antibodies cross-react with baboon proteins and cells; thus the model that both robust and efficient. Previous work by ourselves and others have demonstrated the rationale of this approach in the use of fibrinolytics and proposed use of eptibatide for protecting platelets (see Progress Report). This project focuses on suppressing formation of the prothrombinase complex, complement activation and activation of neutrophils, monocytes and platelets. One goal is to inhibit thrombin formation. Prior studies indicate that inhibiting formation of the prothrombinase complex is necessary. We plan to study a tight binding new inhibitor of factor Xa, a factor IXai inhibitor and recombinant tissue factor pathway inhibitor individually and in combination. Suppression of neutrophil and monocyte activation focuses on cyclic AMP, cyclic GMP and specific phosphodiesterase inhibitors (PDEs). We will also study inhibition of neutrophil and monocyte Mac-1 receptor binding using synthesized peptides in an effort to inhibit cellular activation. Lastly we plan to study two potential inhibitors of complement activation that prevent cleavage of C3 by different means. Because blood reactions during CPB and OHS are often mutually interdependent, we plan to study combinations of inhibitors that we believe will act synergistically.