Factor XI deficiency, an injury-related bleeding disorder, is rare worldwide but common in Jews in whom 2 mutations, Glu117Stop (type II) and Phe283Leu (type III), prevail. Mean factor XI activities in homozygotes for Glu117Stop and for Phe283Leu are 1 and 10 U/dL, respectively. Inhibitors to factor XI in patients with severe factor XI deficiency have been reported in a small number of instance...

Factor XI deficiency, an injury-related bleeding disorder, is rare worldwide but common in Jews in whom 2 mutations, Glu117Stop (type II) and Phe283Leu (type III), prevail. Mean factor XI activities in homozygotes for Glu117Stop and for Phe283Leu are 1 and 10 U/dL, respectively. Inhibitors to factor XI in patients with severe factor XI deficiency have been reported in a small number of instance...

We report here the effect of activated human platelets on the activation of human factor IX by human factor XIa. Factor IXa formed during activation was determined via its ability to activate bovine factor X. To increase sensitivity, phospholipids and bovine factor VIIIa were present in the assay. The kinetic parameters of the factor IX activation were determined in the presence of 10 mmol/L Ca...

OBJECTIVE Poor prognosis of sepsis is associated with bacterial lipopolysaccharide (LPS)-induced intravascular inflammation, microvascular thrombosis, thrombocytopenia, and disseminated intravascular coagulation. Platelets are critical for thrombosis, and there has been increasing evidence of the importance of platelets in endotoxemia. The platelet adhesion receptor, the glycoprotein Ib-IX comp...

Introduction Haemophilia B is an X-linked disorder resulting in coagulation factor IX (FIX) deficiency that is treated with the administration of exogenous FIX obtained from plasma of healthy donors or by a DNA recombinant technique1. The development of an inhibitor antibody against exogenous FIX is a serious complication and occurs in 1-3% of patients with haemophilia B and in 25-30% of patien...

Inhibitors of clotting factors occuring in humans are often antibody molecules synthesized in response to exogeneous proteins used in replacement therapy. Extensive studies of inhibitors to factor VIII indicate such antibodies may be monoclonal or polyclonal in nature. To date, only one factor IX inhibitor has been subjected to detailed immunochemical analysis and it appears to be a monoclonal ...

Recent investigations have suggested that the activation of factor IX by factor VII/tissue factor may be an important alternative route to the generation of factor Xa. Accordingly, we have compared the tissue factor-dependent activation of tritium-labeled factor IX and factor X in a human plasma system and have studied the role of proteases known to stimulate factor VII activity. Plasma was def...

To probe the molecular interactions of factor Xl we have prepared two monoclonal antibodies (MoAbs; 5F7 and 3C1 ), each of which binds the heavy chain of reduced and alkylated factor Xla. Competitive solid phase radioimmunoassay (RIA) binding studies revealed that 5F7 and 3C1 are directed against different epitopes within factor Xl. One antibody (5F7) blocked the surface-mediated proteolytic ac...

Background: Hemophilia B is an X-linked recessive coagulation disorder caused by factor IX deficiency.  Analysis of factor IX gene polymorphisms is considered the best approach for prenatal diagnosis and carrier detection of hemophilia B where the identification of gene mutation is not easily possible. Objective: To study the frequency of three factor IX-linked restriction fragment length polym...

A procedure is presented for the purification of Factor IX from human plasma. The final product is homogeneous as judged by disc gel electrophoresis and sodium dodecyl sulfate gel electrophoresis. Furthermore, it is completely free of other coagulation component activities. Factor IX is converted to its enzymatically active form by the addition of small quantities of Factor IXa in the presence ...