No abstract available

[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] In a radioimmunoassay method for determining the concentration of fibrinopeptide A in plasma, a sample of blood is collected, a thrombin inhibitor is added and plasma is separated. The plasma is contacted under radioimmunoassay competitive binding conditions with a sufficient amount of an antibody to fibrinopeptide A and radioactively labelled fibrinoepetide A. The antibody bound fibrinopeptide A is separated from the unbound fibrinopeptide A and the radioactivity measured. An improvement comprises using D-Phe-Pro-ArgCh²Cl or its hydrocloric, hydroflouric, acetic, or citric acid addition salts as the thrombin inhibitor. The reagent may also include a chelating agent and an antiproteolytic agent

[en] The prostanoid status was assessed in 138 patients with coronary atherosclerosis and clinical signs of stable angina. Plasma prostaglandin F_2α and E₁, and stable prostacyclin and thromboxane metabolites were measured radioimmunologically, using standard kits. A relationship is demonstrated between the severity of clinical manifestations, and pattern and magnitude of change in individual prostanoids

[en] The authors goal is to study idiotypic immunoregulation of inhibitors to clotting factor VIII:C. To this end, they used monoclonal antibodies (MoAbs) against VIII:C: Synbiotics, C7F7, and C5, directed against epitopes on the C terminal fragment of VIII:C; C2, C6, C8 directed against epitopes on the N terminal fragment of VIII:C; C10, directed against a non-functional epitope; IB3, Chemicon and Hybritech, to undetermined epitopes. Anti-idiotypic antibodies against C7F7, C8, Synbiotics and Hybritech were produced in rabbits. Competitive radioimmunoassays (RIA) tested cross-reactivity between each immunogen and the other MoAbs. Synbiotics cross-reacted with Chemicon and IB3, indicating they were directed against the same epitope on the C terminal fragment of VIII:C. They did not cross-react with Hybritech, C7F7, C2, C5, C6, C8, or C10. C7F7 showed no cross-reactivities. C8 cross-reacted with C6 but not with C2, C5, C10, C7F7, Synbiotics, or Hybritech. Hybritech did not did not cross-react with any of the other MoAbs. In conclusion, with four anti-idiotypic antibodies and ten MoAbs to VIII:C, they defined at least five functional epitopes and one non-functional epitope on the factor VIII:C molecule to which inhibitors may develop: C2, C6-C8 (N terminal), C7F7, C5, Synbiotics (C terminal), Hybritech (undetermined epitope) and C10 (non-functional)

No abstract available

[en] Haemorrhage remains the greatest threat to life on the battlefield, accounting for half of all deaths. Over the past decade the US army has widely studied new technologies for stopping sever haemorrhages and has introduced an effective zeolite based haemostatic agent. In this paper the bio-stimulatory effect of burned radioactive lantern mantles powder as well as two minerals; bentonite and zeolite are presented. In this experimental study, 50 male Wistar rats were divided randomly into 5 groups of 10 animals each. Following anesthesia, animals' tails were cut off at a thickness of 5 mm by using a pair of surgical scissors. No intervention was made on the animals of the pk group. The second to fifth group received topical nonradioactive lantern mantle powder, radioactive lantern mantle powder, Bentonite mineral or a mixture of bentonite-zeolite minerals respectively. After treatment with above mentioned agents, the volume of blood loss was measured using a scaled test-tube. The bleeding time (BT) and clotting time (CT) were also measured using a chronometer. Analysis of variance (ANOVA) was used for comparing the means of each parameter in the 5 groups. The volume of blood loss, bleeding and clotting time in control animals were 4.39+-1.92 ml, 112.10+-39.60 sec and 94.9+-54.26 sec respectively. In the second group, in which the animals were treated with a nonradioactive lantern mantle, the volume of blood loss, bleeding and clotting time were 2.34+-0.35 ml, 54.50+-14.77 sec and 22.9+-6.54 sec, respectively. In the third group, in which the animals were treated with a radioactive lantern mantle, the volume of blood loss, bleeding and clotting time were 1.50+-0.58 ml, 37.10+-7.81 sec and 33.5+-15.76 sec respectively. In the 4th group, in which the animals were treated with bentonite mineral, the volume of blood loss, bleeding and clotting time were 1.81+-0.62 ml, 55.70+-16.73 sec and 45.9+-32.17 sec, respectively. In the fifth group, in which the animals were treated with a mixture of bentonite-zeolite minerals, the volume of blood loss, bleeding and clotting time were 1.31+-0.60 ml, 34.50+-4.65 sec and 24.2+-4.61 sec, respectively. To our knowledge, this is the first study to investigate the alterations of bleeding and clotting time following the use of lantern mantle powder as well as bentonite or the mixture of bentonite-zeolite minerals. The results obtained in this study clearly show the significant alterations in the volume of blood loss as well as the bleeding or clotting time following the topical use of the mixture of bentonite-zeolite minerals. Controlling the generation of heat was a great achievement in development of the novel haemostatic agent produced in this study. (author)

[en] β-thromboglobulin (β-TG) and the anti-heparin activity platelet factor 4 (PF4) were simultaneously assayed by a radioimmune method in 108 subjects, most of whom had already be studied for platelet kinetics. The following data were obtained: while there was no technical cross-reaction, the two assays correlated closely, which indicates that they explore the same physiological phenomena; when controls were chosen at random in a population of wide age range considerable differences were observed in the results, with values that could be considered excessive in a large percentage of cases, particularly among old, 'normal' individuals; there was no correlations between β-TG and PF4 values on the one hand and platelet destruction rate on the other; plasma levels of β-TG and PF4 were significantly higher in patients with vascular diseases and polycythaemia vera than in control but clearly overlapped with the values observed in controls of the same age group. The clinical significance of these data requires, to be assessed, a long-term prospective study aimed at determining whether patients with high β-TG and PF4 levels present a high risk of thromboembolic complications and whether this risk can be reduced by correcting the biological abnormality with agents altering platelet function

No abstract available

[en] Brief item