BACKGROUND Most cell types, including blood--and vascular cells, produce microparticles upon activation. Since cellular microparticles are known to be elevated in thromboembolic diseases, we hypothesized a role for microparticles in the pathogenesis of thrombosis in essential thrombocythemia. DESIGN AND METHODS In plasma samples from 21 patients with essential thrombocythemia and ten healthy ...

The present studies were undertaken to determine whether factor VIII/von Willebrand factor (vWF) present in the vessel wall (in addition to that in plasma) may mediate the attachment of platelets to subendothelium. Subendothelium from everted rabbit aorta was exposed to human citrated blood flowing through an annular perfusion chamber at 40 mL/min (wall shear rate of 2,600 s-1 for five minutes)...

Mice lacking both of the best-known platelet ligands, von Willebrand factor and fibrinogen, can still form occlusive thrombi in injured arterioles. The platelets of these animals accumulate excessive amounts of fibronectin (FN). These observations led us to examine the contribution of plasma FN (pFN) to thrombus formation. Inactivation of the FN gene in FN conditional knockout mice reduced pFN ...

Von Willebrand disease is an inherited condition characterized by deficiency of von Willebrand factor, which is essential in hemostasis. The National Heart, Lung, and Blood Institute has released new evidence-based guidelines for the diagnosis and management of the disease. There are three major subtypes of von Willebrand disease, classified as partial quantitative deficiency (low levels) of vo...

Treatment of von Willebrand disease typically requires multiple infusions of von Willebrand factor (VWF)/factor VIII (FVIII) concentrate. Accumulation of FVIII is a clinical concern due to potential risk for thromboembolism. This study sought to determine whether VWF/FVIII concentrate of high VWF:FVIII ratio can prevent FVIII accumulation. VWF-deficient knockout mice received four 150 IU/kg VWF...

OBJECTIVE Thrombosis occurs at sites of vascular injury when platelets adhere to subendothelial matrix proteins and to each other. Platelets express many surface receptor proteins, the function of several of these remains poorly characterized. Cadherin 6 is expressed on the platelet surface and contains an arginine-glycine-aspartic acid motif, suggesting that it might have a supportive role in ...

Plasma drawn from 22 patients with a broad range of von Willebrand factor (vWF) levels, including one patient with rare, severe type III von Willebrand's disease, was used to investigate the adaptability of the Bio/Data Corp. vW Factor Assay, a ristocetin cofactor-based kit developed for use with a platelet aggregometer, to a macroscopic platelet agglutination technique. The results were compar...

Objective: Transmyocardial laser revascularization (TMLR) has been widely evaluated as a treatment for ischemic myocardium. However, its mechanism remains unclear. One mechanism is angiogenesis. This study examines the relationship between TMLR and angiogenesis from the viewpoint of matrix metalloproteinases and platelet-derived endothelial cell growth factor. Methods: The left anterior descend...

Patients with acquired von Willebrand disease may present with severe bleeding, which is usually difficult to manage. Adequate haemostasis in acquired von Willebrand disease may be achieved with the infusion of factor VIII/von Willebrand factor concentrates or with the administration of desmopressin. We report a case of acquired von Willebrand disease with severe postoperative bleeding, respond...

Previous procedures for measuring von Willebrand factor (vWF) in human plasma have usually utilized ristocetin and platelet-rich plasma or washed platelets. In this study. we describe a new approach for determination of vWF utilizing two new reagents. One is venom coagglutinin. a recently recognized component of Bothrops and other venoms. which aggregates platelets in the presence of vWF. The o...