The majority of cases of human hemophilia B are the result of missense mutations in the coagulation factor IX gene and defective circulating factor IX is detectable in most patients. The available mouse factor IX knockout models of hemophilia B (FIXKO mouse) reproduce the bleeding phenotype of human hemophilia B, but because the models produce no factor IX they fail to reproduce the dominant hu...

Context:  The major motivation for the preparation of the plasma derived biological medicine was the treatment of casualties from the Second World War.  Due to the high expenses for preparation of plasma derived products, achievement of self-sufficiency in human plasma biotechnological industry is an important goal for developing countries.Evidence Acquisition:  The complexity of the bloo...

lmmunoassays with a monoclonal antibody (A-i ) detect a prevalent dimorphism in plasma coagulation factor IX. The antibody was shown to react with a dimorphic segment of the normal factor IX sequence as follows. First. A-i bound to isolated activation peptide (residues 146 through 180) prepared from activated factor IX from a normal plasma pool. Second, binding of recombinant factor lXs with A-...

Bq II. L. NO55EL T MECHANISMS, the extrinsic and the intrinsic, have been defined whereby in vitro blood coagulation may be initiated. The extrinsic system is initiated by tissue thromboplastin which, in the presence of Factor VII and calcium, activates Factor X (Stuart-Prower factor).’5 The intrinsic system is initiated by foreign surface contact which results in sequential activation of Facto...

Bq II. L. NO55EL T MECHANISMS, the extrinsic and the intrinsic, have been defined whereby in vitro blood coagulation may be initiated. The extrinsic system is initiated by tissue thromboplastin which, in the presence of Factor VII and calcium, activates Factor X (Stuart-Prower factor).’5 The intrinsic system is initiated by foreign surface contact which results in sequential activation of Facto...

Coagulation factor IX is a vitamin K-dependent glycoprotein that circulates in blood as a precursor of a serine protease. Incubation of human factor IX with human alpha-thrombin resulted in a time and enzyme concentration-dependent cleavage of factor IX yielding a molecule composed of a heavy chain (mol wt 50,000) and a doublet light chain (mol wt 10,000). The proteolysis of factor IX by thromb...

Human coagulation factor XI (FXI) is a plasma serine protease composed of 2 identical 80-kd polypeptides connected by a disulfide bond. This dimeric structure is unique among blood coagulation enzymes. The hypothesis was tested that dimeric conformation is required for normal FXI function by generating a monomeric version of FXI (FXI/PKA4) and comparing it to wild-type FXI in assays requiring f...

Acquired inhibitors to coagulation factors other than factor VIII are extremely rare. We describe a case of a 59-year-old woman with abnormal bleeding, diagnosed with concurrent inhibitor antibodies to factor VIII and IX by Bethesda testing. We demonstrate that anti-FVIII antibodies of a very high titre are capable of disturbing the aPTT-based Bethesda assay, resulting in falsely-positive antib...