A 37-yr-old hemophiliac with factor IX antibody in high titer required operation for a pseudotumor growing invasively into the bone in his left elbow. Exchange plasma-pheresis was not feasible, mainly because of possible stimulation of factor IX inhibitor. In addition, the patient had antibodies against tissue antigens. The factor IX antibodies were of IgG type and adsorbable to protein-A-agaro...

To determine the functional role of the metal-dependent conformational changes in Factor IX, two populations of conformation-specific anti-Factor IX antibodies were prepared. Anti-Factor IX X Mg(II) antibodies bind to Factor IX in the presence of Mg(II) and other metal ions, but not in the absence of metal ions. Anti-Factor IX X Ca(II)-specific antibodies bind to Factor IX in the presence of Ca...

Human plasma-derived factor IX (pdFIX) concentrates are routinely used to treat patients with hemophilia B, an X-linked bleeding disorder that affects 1 in 30 000 males, but concerns remain regarding transmission of blood-borne pathogens. Therefore, the safety and efficacy of recombinant human factor IX (rFIX) were evaluated. A 20-center international trial was conducted in previously treated p...

This review focuses on selected areas that should interest both the scientist and the clinician alike: polymorphisms within the factor VIII and factor IX genes, their linkage, and their ethnic variation; a general assessment of mutations within both genes and a detailed inspection of the molecular pathology of certain mutations to illustrate the diverse cause-effect relations that exist; a summ...

Tissue factor is the major initiator of coagulation. Both factor IX and factor X are activated by the complex of factor VIIa and tissue factor (VIIa/TF). The goal of this study was to determine the specific roles of factors IXa and Xa in initiating coagulation. We used a model system of in vitro coagulation initiated by VIIa/TF and that included unactivated platelets and plasma concentrations o...

The platelet von Willebrand factor (vWF) receptor, glycoprotein Ib-IX (GPIb-IX), mediates platelet adhesion and induces signaling leading to integrin activation. Phosphoinositol 3-kinase (PI3K) is important in GPIb-IX-mediated signaling. PI3K-dependent signaling mechanisms, however, are unclear. We show that GPIb-IX-induced platelet aggregation and stable adhesion under flow were impaired in mo...

Immunologic methods were employed in an attempt to identify a potent procoagulant present in homogenates of human skin fibroblasts cultured in vitro. The activity of this procoagulant was restricted to the early stages of coagulation and was heretofore considered to be due to tissue factor (tissue thromboplastin, factor Ill) either alone or in combination with one or more of the first-stage coa...