Tobacco Documents Online

THE COUNCIL FOR TOBACCO RESEARCH-U.S.A., INC. 000 1'HIRD AVENUE NEW YORK. N.Y. 10022 Memorandum To: Dr. J.F.Glenn and Staff From D.H.Ford Re: Site visit with Dr. J. Jes,t~,~`,SUNY, Stony Brook,N.Y. ,,~,y ..: June 9, 1989. Grant No.2255R1 entixled "Plasma inhibitors of Factor X activation." Goals:To isolate the plasma inhibitor of the tissue factor (TF)-factor VIIa complex.Recent advances by others on this problem have led Dr. Jrsty to alter his focus to concentrate on the plasma kinetics of TF action. Results: At the time of my last visit Dr. Jesty was making rather slow progress, because none of the various clotting factors were available comercially, and he was having to synthesize them himself. Since that visit he has purified or made crude factor XIa, factor IX, IXa,X, Xa and von Willebrand factor.He also has prepared semi-pure factor VII and thrombin. Further, he has prepared an acetylated factor X with properties that make it a major tool in the study of its activation. A major problem in this:,study of the activation of factor X is that the product he measures (Xa) activates the enzyme which forms it. Thus, in the intrinsic pathway the enzyme is a complex of factor IXa and factor VIII and it is the factor VIII which is activated by factor Xa. In the extrinsic pathway the enzyme is the TF-VII complex, and it is the factor VII which is activated. Thus, if a reaction is started with an unactivated enzyme and a low rate of factor X activation, the formation of Xa then changes the kinetics of activation. Therefore, Dr. Jesty finds it is impossible to measure factor X activation without interference by positive feedback. He feels that their newly synthe-sized acetyl- acted factor X will help solve this problem. See attached figure: illustrates the complexity of the feedbacks in this system. Dr, Jesty has recently started making primary cultures of human umbilcal vein endothelial cells. With his newly prepared acetylated factor X and factor VII he is preparing to measure the kinetic effect on both the rates of factor X activation by IXa-VIIIa and TF-VIIa, and their effect on the kinetics of feedback activation of factors VII and VIII. His immediate goal is to focus on the kinetics of factor X activ- ation via the intrinsic pathway and to determine the effect of plasma and endothelial cells on the activation. Dr. Jesty will be presenting a poster at one of the Gordon Conferences this summer concerning his newly prepared acetylated factor X.His preliminary observationis that Ac-X liberates studies of the kinetics of factor VII activation from the normal compexities associated with positive feedbacks

2 Comment: After a rather slow start, due to the unavailability of various substrates and factors, Dr. Jesty now appears to be making progress toward increasing our understanding of how these various factors interact with multiple feedback interactions in the process of clottring. Thus, it would appear that this study continues to be relevent to the interests of CTR in cardiovascular research. DHF

SURFACE PREKALLIKREIN HMW-KININOGEN XII Xlia ? XI -30-Xla Co Ca /007F IX-^0 -IXa Vlla VII Vltl Ca Co TF 1 XXa ~n c2 e~se vu ,o„c~ V Ca ~C7'>~ISrC r~ THROM6IN ~ PROTHROMBIN - Xiila-E XIII I CROSS-LINKED ~ FIBRIN r FIBRIN 1 FIBRINOGEN FIBRIN [MONOMER~