[en] Activation of Factor IX and Factor X was studied by adding ¹²⁵I-Factor IX or ¹²⁵I-Factor X to reaction mixtures and quantitating cleavage products by reduced sodium dodecylsulfate gel electrophoresis. Thrombin failed to activate Factors IX or X; Factor Xsub(a) produced insignificant amounts of cleavage products of both factors. In contrast, the reaction product of tissue factor and Factor VII cleaved large amounts of both Factor IX and Factor X in purified systems and in plasma. In incubation mixtures of plasma containing added ¹²⁵I-Factor IX or ¹²⁵I-Factor X, tissue factor and Ca²⁺ions, the percentage of total radioactivity in the heavy chain peak of ¹²⁵I-IXsub(a) and the heavy chain of ¹²⁵I-Xsub(a) increased at a similar rate. When the tissue factor was diluted, similar curves were obtained for percent cleavage of ¹²⁵I-Factor IX and percent cleavage of ¹²⁵I-Factor X plotted against tissue factor concentration. These findings support the hypothesis that activation of Factor IX by the tissue factor-Factor VII reaction product represents a physiologically significant step in normal haemostasis. (author)

[en] A contrast reaction to the intravenous injection of the non-ionic contrast medium iohexol (Omnipaque) is reported. The symptoms developed several hours after the injection and at first were not recognised as being due to the contrast. The reaction could be reproduced under controlled conditions and was associated with a significant rise in thromboplastin synthesis in circulating monocytes, a sign of marked cellular activation. (orig.)