The effect of plasma and Cohn's fraction I on the Duke and Ivy bleeding times in von Willebrand's disease

Historical perspective and future directions in platelet research

Platelets are a remarkable mammalian adaptation that are required for human survival by virtue of their ability to prevent and arrest bleeding. Ironically, however, in the past century, the platelets' hemostatic activity became maladaptive for the increasingly large percentage of individuals who develop age-dependent progressive atherosclerosis. As a result, platelets also make a major contribution to ischemic thrombotic vascular disease, the leading cause of death worldwide. In this brief review, I provide historical descriptions of a highly selected group of topics to provide a framework for understanding our current knowledge and the trends that are likely to continue into the future of platelet research. For convenience, I separate the eras of platelet research into the "Descriptive Period" extending from ~1880-1960 and the "Mechanistic Period" encompassing the past ~50 years since 1960. We currently are reaching yet another inflection point, as there is a major shift from a focus on traditional biochemistry and cell and molecular biology to an era of single molecule biophysics, single cell biology, single cell molecular biology, structural biology, computational simulations, and the high-throughput, data-dense techniques collectively named with the "omics postfix". Given the progress made in understanding, diagnosing, and treating many rare and common platelet disorders during the past 50 years, I think it appropriate to consider it a Golden Age of Platelet Research and to recognize all of the investigators who have made important contributions to this remarkable achievement..

Studies on the prolonged bleeding time in von Willebrand's disease

Ten studies of the effect of cryoprecipitate infusion in four patients with von Willebrand's Disease (vWD) are reported. The doses studied (4, 8 and in one case 10 bags of cryoprecipitate) were based on previous reports of correction of the bleeding time (BT) with such doses. A modest shortening of the BT was observed in only 2 studies and complete correction of the BT at 1 and 4 hours was observed in only one study. This latter result could not be reproduced in a subsequent study of the same patient. In all cases, the von Willebrand factor antigen (vWF:Ag) multimer patterns were normal in the infused cryoprecipitate and in the recipients' plasma post infusion with the presence of high molecular weight multimers demonstrated in all samples. These results contradict earlier reports of the effect on the BT of similar doses of cryoprecipitate and suggest that the presence of the high molecular weight forms of vWF:Ag does not necessarily correlate with the presence of the factor which corrects the bleeding time.