The effects of factor IX concentrate therapy on hemostasis in hemophilia patients were studied by means of the radiometric factor IXa assay, the coupled amidolytic assay for factor VIIa, and coagulant assays for factors II, IX, and X, and antithrombin III. Both activated and unactivated concentrates contained factors VIIa and IXa, with the highest levels in the activated concentrates. Factors V...

We investigated the kinetics of the inhibitory action of antithrombin III and antithrombin III plus heparin during the activation of factor X by factor IXa. Generation and inactivation curves were fitted to a three-parameter two-exponentional model to determine the pseudo first-order rate constants of inhibition of factor IXa and factor Xa by antithrombin III/heparin. In the absence of heparin,...

A new variant of antithrombin (Rouen-VI, 187 Asn-->Asp) with increased heparin affinity was shown to have normal inhibitory activity which decreased slowly at 4 degrees C and rapidly at 41 degrees C. On electrophoresis the freshly isolated variant had an anodal shift relative to native antithrombin due to the mutation. A further anodal transition occurred after either prolonged storage at 4 deg...

To clarify the action of dextran sulphate, a heparin analogue, in the clotting of fibrinogen by thrombin, determinations were carried out on the clotting activity, the release of fibrinopeptides from fibrinogen, and the hydrolytic activity of thrombin against a peptide chromogenic substrate in the absence or presence of antithrombin III (heparin cofactor). It was shown that dextran sulphate its...

The fifteenth quarterly clinicopathological conference was held at the Royal College of Physicians of London on 29 July 1976. The conference was chaired by Professor Sheila Sherlock (1). She began by introducing Professor Jean-Pierre Benhamou (2), professor of gastroenterology at the Beaujon-Clichy Hospital, University of Paris, who was to open the discussion of the case. Professor Sherlock emp...

Oligosaccharides of well-defined molecular size were prepared from heparin by nitrous acid depolymerization, affinity chromatography on immobilized antithrombin III (see footnote on Nomenclature) and gel chromatography on Sephadex G-50. High affinity (for antithrombin III) octa-, deca-, dodeca-, tetradeca-, hexadeca- and octadeca-saccharides were prepared, as well as oligosaccharides of larger ...