A coupled amidolytic assay for factor VII (VII) has been developed that when used with a clotting assay for VII enables detection of activated VII. In the assay, VII in a test material determines generation of factor Xa in a mixture of purified factor X, tissue factor, and calcium; factor Xa is measured with a chromogenic substrate. Factor VII activity in the coupled amidolytic assay (VIIam) co...

Several recent studies have reported conflicting results on the effectiveness of danazol, an attenuated androgen, in raising plasma levels of clotting factors VIII and IX in patients with hemophilia. We undertook a randomized, double-blind cross-over trial using 8 weeks' administration of danazol (D), 600 mg/d, and 8 weeks' administration of placebo (P) separated by 2 weeks of rest in 12 patien...

Tissue factor (TF), the initiator of coagulation, continuously circulates in the plasma, and the clotting system "idles," generating very low levels of active clotting enzymes, clotting products, and by-products. Given the enormous amplification potential of the clotting cascade, rigorous control is required to ensure that such low-level stimulation does not cause massive system amplification a...

Hemophilia is a rare X-linkated bleeding disorder which causes spontaneous or secondary bleeding. This used to be treated with plasma cryoprecipitate, but since clotting factor precipitates became available these have become standard of treatment.

BACKGROUND AND OBJECTIVE The bleeding manifestations frequently observed in patients with immunoglobulin light chain amyloidosis (AL) have been attributed to different pathogenetic factors: amyloid deposits in several organs and systems leading to failures of these latter, the affinity of amyloid for some clotting factors, and the presence of plasma components interfering with fibrin formation ...

We have studied the effects of both impaired prothrombin activation and direct inhibition of thrombin on the platelet release reaction in clotting blood to determine the role of thrombin in this process. In blood from two patients with congenital Factor V deficiency, prothrombin activation during spontaneous in vitro clotting was delayed and decreased. Secretion of platelet Factor 4 was also de...

Circulating anticoagulants against antihemophilic factor (AHF, factor VIII) sometimes seem to inactivate other clotting factors as well. Measurements of the concentration of clotting factors in highly diluted plasma, or after neutralization of the anticoagulant with purified AHF, have demonstrated the specific nature of the anticoagulant in a patient under treatment with diphenylhydantoin. A se...

C OAGULATION DEFECTS due to the lack of a single blood clotting factor are almost exclusively congenital and symptoms appear in early life. Acquired defects other than iatrogenic are usually the result of liver dysfunction and in such cases more than one clotting factor is depressed. A case of selective factor X deficiency developing in middle life and associated with extensive amyloidosis has ...

The blood coagulation scheme for the puffer fish, Fugu rubripes, has been reconstructed on the basis of orthologs of genes for mammalian blood clotting factors being present in its genome. As expected, clotting follows the same fundamental pattern as has been observed in other vertebrates, even though genes for some clotting factors found in mammals are absent and some others are present in mor...