OBJECTIVE To determine whether canine plasma von Willebrand factor (vWf) varies between and within individuals over time and with different blood sample collection and processing procedures. ANIMALS 26 adult dogs and 6 pups. PROCEDURE Blood was obtained from the jugular or cephalic vein daily for 8 to 19 days and weekly for 9 to 23 weeks in adult dogs and periodically up to 180 days of age ...

von Willebrand factor (vWf) can bind to glycoprotein (GP) lIb/Illa on activated platelets. The significance of this interaction is unclear, however. because it has not been possible to detect vWf binding to GPIIb/llla on platelets stimulated in plasma. We have developed an indirect. flow cytometry assay that uses fluorescein-labeled antibodies to detect vWf and fibrinogen on platelets. Using th...

Von Willebrand factor (VWF) is a pivotal haemostatic protein mediating platelet adhesion to injured endothelium and carrying coagulation factor VIII (FVIII) in the circulation to protect it from premature clearance. Apart from the roles in haemostasis, VWF drives the formation of the endothelial cell specific Weibel-Palade bodies (WPBs), which serve as a regulated storage of VWF and other throm...

The essential event in platelet adhesion to the injured blood vessel wall is the binding to subendothelial collagen of plasma von Willebrand factor (VWF), a protein that interacts transiently with platelet glycoprotein Ibalpha (GPIbalpha), slowing circulating platelets to facilitate firm adhesion through collagen receptors, including integrin alpha2beta1 and GpVI. To locate the site in collagen...

von Willebrand factor (vWf) can bind to glycoprotein (GP) lIb/Illa on activated platelets. The significance of this interaction is unclear, however. because it has not been possible to detect vWf binding to GPIIb/llla on platelets stimulated in plasma. We have developed an indirect. flow cytometry assay that uses fluorescein-labeled antibodies to detect vWf and fibrinogen on platelets. Using th...

Glycoprotein (GP) Ib , a member of the leucine-rich repeat (LRR) protein family, mediates platelet adhesion to immobilized von Willebrand factor (VWF). We investigated the role in VWF binding of charged residues in the LRR region of GP Ib that are conserved in human, canine, and murine proteins. Substitution of His86 with either Ala or Glu resulted in a gain of VWF-binding function as judged by...

Von Willebrand Disease (VWD) is the most common inherited bleeding disorder, caused by a deficiency or abnormality of the Von Willebrand Factor (VWF). The mainstays of treatment are therapy with Desmopressin (DDAVP) and replacement therapy with Factor VIII-containing VWF product (FVIII/VWF). Therapy with FVIII/VWF can be administered as Long-term prophylaxis (LTP) in the more severe forms of th...

Normal hemostasis is maintained by well-balanced performance of many factors in plasma, blood cells, and vascular wall cells. von Willebrand factor (VWF) is one of the plasma proteins that is involved in platelet adhesion and aggregation 1). VWF is synthesized in vascular endothelial cells and megakaryocytes, starting with a 350-kDa precursor. This polypeptide dimerizes in the endoplasmic retic...

The major part of von Willebrand factor (vWf) synthesized in cultured endothelial cells is secreted constitutively without stimulation and consists of all multimeric forms of vWf. In contrast, stimulation with secretagogues such as thrombin results in the release of vWf from the storage pool, the Weibel-Palade bodies which contain only the largest, most biologically potent multimeric forms of v...

We report the identification of a new mutation of von Willebrand Factor (VWF) gene within exon 30 occurring in two related patients (mother and daughter) with a hemorrhagic syndrome. A T-->A transvertion at nucleotide 5441 was found changing the serine 968 to threonine of the mature VWF subunit (S1731T of the preproVWF). The Ser968Thr mutation is located within the VWF A3 domain which interacts...