Development of inhibitory antibodies is a serious complication of treatment with repeated factor IX infusions in a minority of patients with hemophilia B. Such antibodies detected in 8 patients have been characterized. Typing studies revealed that patients' immune response toward factor IX is highly heterogeneous and involves immunoglobulin G (IgG) antibodies, preferentially IgG1 and IgG4. The ...

Hemophilia Bm is characterized by a strikingly prolonged plasma ox brain prothrombin time. In an attempt to find an explanation for this phenomenon we have analyzed various aspects of the Bm variants factor IX Deventer, factor IX Milano, factor IX Novara, and factor IX Bergamo. Proteolytic cleavage by factor XIa was normal in two Bm variants, but absent at the Arg180-Val bond in the other two. ...

Factor IX Chicago-2 and prothrombin Madrid were purified from patients with hemophilia B and congenital dysprothrombinemia. respectively. Each protein displays defects in zymogen activation secondary to the failure to cleave one of the sessile bonds whose cleavage is necessary for full coagulant activity. These proteins were isolated by immunoaffinity chromatography using conformation-specific ...

In aiming to develop a gene therapy approach for hemophilia B, we expressed and characterized human factor IX in rat capillary endothelial cells (CECs). Moloney murine leukemia virus-derived retrovirus vectors that contain human factor IX cDNA linked to heterologous promoters and the neomycin-resistant gene were constructed and employed to prepare recombinant retroviruses. Rat CECs and NIH 3T3 ...

hemophilia b is factor ix deficiency and is inherited as x-linked recessive disorder. the subject of carrier detection in hemophilias has received new impetus in the last several years. analysis of factor ix gene polymorphisms is considered the best approach for prenatal diagnosis and hemophilia b carrier detection, if the identification of the gene mutation is possible. allele frequencies of t...

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

Two structurally different forms of activated human Factor IX (Factor IXaa and IXa8) have been previously reported to have essentially identical clotting activity in vitro. Although it has been shown that activated Factor IXChapel Hills an abnormal Factor IX isolated from the plasma of a patient with mild hemophilia B, and normal Factor IXaa are structurally very similar, the clotting activity ...

Background: Hemophilia B is a bleeding disorder with a recessive X-linked inheritance pattern, in which the infected individuals have low levels of factor IX in their plasma. Affected individuals may have bleeding episodes after trauma or spontaneously considering the plasma level of factor IX. In order to prevent these episodes and to control bleeding, they should use coagulation factor concen...

Factor IX deficiency was associated with a hemorrhagic disorder in a woman who previously had experienced postpartum hypotension resulting in Sheehan’s syndrome. There was no family history of Christmas disease, and other known causes of factor IX deficiency were excluded. Plasma levels of factor IX were partially corrected by therapy with thyroid hormones and completely restored to normal by t...