Ristocetin will induce the agglutination of platelets in the presence of von Willebrand factor. In previous studies, an electrostatic mechanism was proposed for this phenomenon wherein first the platelet's surface charge is reduced by the binding of ristocetin and then the von Willebrand factor acts as a bridge between platelets. To test this hypothesis, the effects of ristocetin and von Willeb...

Type Vicenza variant of von Willebrand disease (VWD) is characterized by a low plasma von Willebrand factor (VWF) level and supranormal VWF multimers. Two candidate mutations, G2470A and G3864A at exons 17 and 27, respectively, of the VWF gene were recently reported to be present in this disorder. Four additional families, originating from northeast Italy, with both mutations of type Vicenza VW...

This study prospectively evaluated the rate of biologic response to desmopressin (DDAVP) in 66 patients with type 1 or 2 von Willebrand disease (VWD), each of whom had, on the basis of available records, a clinically significant bleeding history and at least one of the following laboratory abnormalities: bleeding time (BT) longer than 15 minutes, ristocetin cofactor activity (VWF:RCo) less than...

Up until recently, von Willebrand Factor (VWF) structure-function relationships have only been studied through in vitro approaches. A powerful technique known as hydrodynamic gene transfer, which allows transient expression of a transgene by mouse hepatocytes, has led to an important shift in VWF research. Indeed this approach has now enabled us to transiently express a number of VWF mutants in...

Two versions of conformation sensitive gel electrophoresis, fluorescent (F-CSGE) and manual (M-CSGE) techniques, were compared for mutation analysis of the von Willebrand factor gene. 56 PCRs were used to amplify all 52 exons of the gene in seven type 1 von Willebrand disease cases, plus a healthy control. One hundred and ninety-two samples were analyzed on each F-CSGE gel, compared with 40 on ...

Cultured human endothelial cells synthesize and secrete a protein(s) which has Factor VIII antigen but which lacks Factor VIII clot-promoting activity (J. Clin. Invest. 52, 2757-2764, 1973). Von Willebrand factor activity has been identified in medium from cultured human endothelial cells. This activity was demonstrated by the ability to correct the defect in platelet adhesiveness of blood obta...

von Willebrand disease (VWD) was first described nearly a century ago in 1924 by Erik Adolf von Willebrand. Diagnostic testing at the time was very limited and it was not until the mid to late 1900s that more tests became available to assist with the diagnosis and classification of VWD. Two of these tests are based on ristocetin, one being ristocetin-induced platelet aggregation (RIPA) and the ...

Up until recently, von Willebrand Factor (VWF) structure only been studied through in vitro transfer, which allows transient expression of a transgene by mouse hepatocy important shift in VWF research. Indeed this approach has now enabled us to transiently express a number of VWF mutants in VWF residues in different aspects of VWF biolo reproducing various types of von Willebrand disease have b...

A family with a platelet release abnormality (PRA) is described. The only son also showed a reduced rate of platelet aggregation in response to ristocetin, markedly reduced levels of von Willebrand's factor (vWf, ristocetin cofactor), and increased mobility of factor VIII-like antigen, features which were suggestive of von Willebrand's disease (vWd). No inhibition of vWf was found in his plasma...

In classic von Willebrand's disease (vWd), assignment of the heterozygous genotype for genetic studies and diagnosis for clinical purposes (which are not exactly the same) are formidable problems. We have pointed out in the first report in this series that almost 50% of the members of two large kindred who transmitted this disease, and were therefore heterozygous, were scored as normal by the u...