Antibodies against factor VIII coagulant activity can appear in haemophiliacs who are treated with factor VIII preparations but also spontaneously in non-haemophiliacs. The Bethesda assay is the most commonly used method to detect these antibodies, but it lacks specificity especially in the lower range resulting in unreliable data. Two modifications are proposed and tested to resolve the imperf...

A coagulation test abnormality, termed activated protein C (APC) resistance, involving poor anticoagulant response to APC is currently the most common laboratory finding among venous thrombophilic patients. Because the anticoagulant activity of APC involves inactivation of factors Va and Vllla, studies were made to assess the presence of abnormal factors V or VIII. Diluted aliquots of plasma fr...

Concentration of factor VIII from fresh plasma by cryoprecipitation remains the basis for preparation of products used to treat haemophilia A. This paper describes the preparation of a factor VIII concentrate from small plasma pools in transfusion centres with drying facilities. The dried concentrate from one litre of plasma dissolves very well in 50 or 100 ml of distilled water and contains ar...

INTRODUCTION Patients with severe hemophilia A often develop inhibitors (antibodies) against transfused factor VIII. MATERIAL/METHODS One hundred thirteen Polish patients with severe hemophilia A, who had been treated on demand with cryoprecipitate until 1992 and exclusively with factor VIII concentrates after 1995, were examined for intron 22 inversion by Southern blotting and the presence a...

The cofactor function of human Factor VIII in Factor X activation was investigated by an initial-rate assay of 3H-Factor X activation in the presence of human factor IXa, Ca2+, and either phospholipid or fresh washed human platelets. Purified Factor VIII that has not been activated by thrombin or Factor Xa supports Factor X activation after a lag of several minutes. A specific inhibitor of Fact...

Factor VIII is tightly noncovalently linked to von Willebrand factor (vWF) in plasma with a stoichiometry of 1:50, and vWF deficiency results in secondary factor VIII deficiency, with accelerated clearance of factor VIII from the circulation. We used a murine model of severe von Willebrand disease (vWF knockout mice) to study the effect of a recombinant vWF/pro-vWF preparation (rpvWF) on factor...

Ristocetin was used to study platelet aggregation in platelet-rich plasma and to assay the von Willebrand factor activity of factor VIII (VIII-VWF). Ristocetin-induced platelet aggregation (RIPA) was decreased in 13 of 18 patients with von Willebrand's disease (VWD) who had decreased plasma levels of VIII-VWF. The five patients with normal RIPA appeared to have mild VWD but did not constitute a...

The efficacy of using promptly frozen plasma samples in the diagnosis of the carrier state for hemophilia A was evaluated by simultaneous measurement of factor VIII acitivity and antigen in 20 normal women and 20 obligate carriers. Factor VIII antigen was measured by two methods, electroimmunoassay and immunoradiometric assay. When the factor VIII activity and antigen data were evaluated by reg...

background: haemophilia a (ha) is an x-linked bleeding disorder caused by the absence or reduced activity of coagulation factor viii (fviii). coagulation factors are a group of related proteins that are essential for the formation of blood clots. the aim of this study was to genotype the coagulation factor viii gene mutations using inverse shifting pcr (is-pcr) in an iranian family with severe ...