Showing papers by "Richard J. Ulevitch published in 1977"

Complement-dependent hemodynamic and hematologic changes in the rabbit.

Abstract: The intravenous injection of the anticomplementary protein from cobra venom, cobra factor (CoF), induces decreases in mean arterial blood pressure and circulating platelets in rabbits. The changes are rapidly reversed. Both changes require the presence of C3 and occur in rabbits genetically deficient in the sixth component of complement. The hypotensive effects of CoF were blocked by the histamine H2-receptor antagonist burimamide. An acute C3-dependent change in blood pressure and circulating platelets also was demonstrated following the intravenous injection ofS. marcescens endotoxin. However, abrogation of these acute changes by C3 depletion did not alter the extent of a second, prolonged fall in blood pressure and platelets induced byS. marcescens endotoxin occurring after 60–90 min. C3 depletion also did not alter the lethal effects of theS. marcescens endotoxin.

The Chemistry and Biology of the Proteins of the Hageman Factor-Activated Pathways

Abstract: The initiation of the intrinsic clotting system, the formation of bradykinin, and one pathway of plasminogen activation all require the activation of Hageman factor (factor XII). These pathways are shown schematically in Figure 1. Activation of Hageman factor, prekallikrein plasma thromboplastin antecedent (factor XI), and the plasminogen activator are all characterized by the conversion of a zymogen to an enzymatically active protease. This singular biochemical event, activation of zymogen, can produce rapid and diverse alterations in both humoral and cellular-based mediation systems.