The effects of therapy with oestriol succinate and ethinyl oestradiol on the haemostatic mechanism in post-menopausal women.

The effects on the haemostatic mechanism of oestrogen therapy, given to prevent bone loss in post-menopausal women, have been investigated. Oestriol succinate was given orally to 10 women at a level of 2 mg/day for 1 month and for a further 3 months with incremental increase of 2 mg each month. 6 of the 10 women were subsequently treated with 25 mug/day orally of ethinyl oestradiol. Oestriol succinate therapy resulted in a small increase in the level of factor VII, a decrease in factor VIII concentration and increased sensitivity of platelets to aggregating agents. Ethinyl oestradiol treatment resulted in much more widespread changes with marked increases in coagulation factors VII, VIII, IX and X, decreased levels of antithrombin and dramatic increases in circulating plasminogen levels and euglobulin lysis activity. The data suggested that the nature of oestrogens employed therapeutically is important in determining the qualitative and quantitative effect of oestrogen therapy on components of the haemostatic mechanism.

The effects of an increase in endogenous oestrogen on the haemostatic mechanism.

The effects on the haemostatic mechanism of rises in circulating human oestrogen in a group of women being treated for infertility with pituitary hormones were studied. Despite large but brief rises in oestrogen levels no changes were found.

The haemostatic mechanism and menstruation: the role of intra-uterine contraceptive devices.

PIP: A multidisciplinary study was conducted to examine the hemostatic mechanism in the uterus during menstruation with and without an IUD in situ. The subjects were 40 female patients undergoing menstruation -- 20 with IUDs and 20 without (control group). The patients' coagulation profiles, fibrinolytic system and platelet functions were examined before and after hysterectomy. No significant differences were found in the coagulation, fibrinolytic and platelet function tests in the 2 groups, but in each group the expected changes after operation occurred. Platelet survival time, consumption and radioactivity in the tampons revealed no significant differences between the IUD and control groups. 6 patients in the IUD group had low platelet survival times. Resected uteri revealed a lack of concentration of platelets. This may have been due in part to blood loss at operation and handling of the uterus. Platelet survival time in response to the severe hemostatic challenge of menstruation was normal, but 6 patients in the IUD group showed shortening of platelet survival.^ieng

6-oxo-prostaglandin F1 alpha and thromboxane B2 in uterine vein blood--a possible role in menstrual bleeding.

The role of the haemostatic system in relation to menstrual bleeding is poorly understood. Platelet retention to glass beads and plasma concentrations of 6-oxo-PGF1 alpha and thromboxane B2 were measured in uterine and peripheral venous blood obtained from 18 women undergoing abdominal hysterectomy. Concentrations of 6-oxo-PGF1 alpha were significantly (p less than 0.01) higher in uterine (1.4 +/- 0.3 ng/ml, mean +/- SEM) than in peripheral vein blood (0.2 +/- 0.1 ng/ml) as was the level of thromboxane B2 (0.5 +/- 0.1 and 0.2 +/- 0.1 ng/ml, respectively). Platelet retention in uterine vein blood (11 +/- 4%) was significantly lower than in peripheral blood (42 +/- 4%; p less than 0.01) and the degree of platelet retention correlated inversely with the plasma concentration of 6-oxo-PGF1 alpha (r -0.43; p less than 0.01). There was a significant rank correlation between time since menstruation and concentrations of 6-oxo-PGF1 alpha in uterine (tau + 0.69; p less than 0.001) and peripheral (tau + 0.56; p less than 0.05) vein blood. The results indicate that an increased local production of prostacyclin (PGI2) relative to thromboxane A2 at the time of menstruation could contribute to the mechanism of uterine bleeding.

Effects of three cobra venoms on blood coagulation, platelet aggregation, and fibrinolysis.

The effects of the venoms of Naja melanoleuca, Naja nigricollis, and Ophiophagus hannah on blood coagulation, platelet aggregation, and fibrinolysis were studied in vitro. All three venoms were shown to be anticoagulant. This action appeared to be due to an effect on both the extrinsic and blood thromboplastin mechanisms. Platelet aggregation in Chandler's tubes and adenosine diphosphate reactivity were inhibited by the three venoms, although in the case of Ophiophagus hannah venom they were inhibited only with intermediate concentrations. The three venoms possessed proteolytic properties, but when incorporated into purified caseinolytic systems and euglobulin clot lysis systems inhibition of plasmin activity was observed.

Effect of feeding fat on fibrinolysis, stypven time, and platelet aggregation in elderly Africans.

The effects of acute fat feeding on fibrinolytic activity, platelet aggregation, and stypven time in six elderly Africans are presented. These indicate that there is no alteration in the pattern of response seen in Africans with advancing age.

Effect of feeding fat on fibrinolysis, Stypven time, and platelet aggregation in Africans, Asians, and Europeans.

The effects of acute fat feeding on fibrinolytic activity, platelet aggregation, and Stypven time in 10 Africans and 10 Asians are presented and compared with the results previously obtained in 10 Europeans. These indicated that the inhibition of fibrinolytic activity seen in Europeans does not occur in either Africans or Asians although the Stypven time was shortened in all three groups. Platelet aggregation, as measured by the Chandler's tube technique, was inhibited by fat feeding in Europeans but was unchanged in Africans and Asians. The results also indicate that the fibrinolytic activity of Africans and Asians is greater than that of Europeans.

Effects of the venom of the rhinoceros horned viper (Bitis nasicornis) on blood coagulation, platelet aggregation, and fibrinolysis.

The venom of the rhinoceros horned viper (Bitis nasicornis) has been studied in vitro and has been shown to be anticoagulant. This action appeared to be due to an effect on both the extrinsic and intrinsic blood thromboplastin mechanisms. The venom was also proteolytic and in purified caseinolytic systems activated plasminogen, enhanced the activation of plasminogen by streptokinase, and potentiated the action of plasmin. In the euglobulin clot lysis system high concentrations of venom produced inhibition. The crude venom increased platelet adhesiveness but in high concentrations delayed the snowstorm effect in the Chandler's tube system and inhibited platelet adenosine diphosphate reactivity. Passage through carboxymethylcellulose yielded six fractions. One possessed anticoagulant activity, inhibited plasmin, and increased the optical density of platelet-rich plasma. The other five fractions shortened the plasma recalcification time but had no effect on plasmin activity. Four fractions aggregated platelets and enhanced platelet adenosine diphosphate reactivity.

Changes in thrombin-stimulated platelet malondialdehyde production during the menstrual cycle.

Forty normal women had thrombin-stimulated platelet malondialdehyde (MDA) production measured during their menstrual cycle. Twenty women in this group were taking the combined oral contraceptive pill (OCP). Platelet MDA production was found to fall by 30% during normal menstruation and the week when the subjects were not taking a combined OCP, but it remained constant throughout the remainder of the cycle. No significant change in initial platelet aggregation response to stimulation by thrombin, change in plasma thrombin clotting time, plasma heparin neutralising activity (HNA), or plasma antithrombin III (AT-III) activity was seen when the platelet MDA production was reduced. The bleeding time results showed some variation throughout the menstrual cycle but these did not appear to be related to the variation in platelet MDA production.

Serum enzyme changes after intramuscular bleeding in patients with haemophilia and Christmas disease.

Serum creatine kinase, lactate dehydrogenase, aspartate and alanine transaminases, and aldolase were determined in 41 hospital inpatients with haemophilia or Christmas disease and no significant differences from the normal ranges were found.(3) Levels of these enzymes in a further 10 such patients who had sustained muscle haematomata were determined: in all of these there was a consistent rise in the level of creatine kinase, the peak occurring between 36 and 96 hours. In bleeding disorders a rise in serum creatine kinase levels may be useful as a diagnostic test for intramuscular haemorrhage.

Relationships between platelet function tests in normal and uraemic subjects.

IN TESTS OF PLATELET FUNCTION IN NORMAL SUBJECTS, THE FOLLOWING RELATIONSHIPS WERE FOUND: the greater the platelet adhesiveness the less the ability to disaggregate after challenge with adenosine diphosphate (ADP), and the greater the disaggregation after ADP, the longer the clotting time in the test for platelet factor 3 availability. Such correlations were disturbed in uraemic patients.

Effects on blood coagulation, fibrinolysis, and platelet aggregation of normal and atheronatous aortic tissue.

A comparison was made between the effects of atheromatous and normal areas of the same aorta on coagulation, fibrinolytic, and platelet aggregating systems. In the thromboplastin generation test it was found that atheromatous aorta possessed significantly greater ability to generate intrinsic prothrombin activator than did normal aortic tissue. But, by the one-stage prothrombin time technique, the content of extrinsic thromboplastin in both types of aorta was similar. Aortic preparations, consisting of intimal and medial layers only, were not found to possess fibrinolytic ability and did not contain inhibitors of the fibrinolytic system. The adhesion of platelets to ulcerated atheromatous areas of aorta was significantly greater than to normal or non-ulcerated atheromatous areas. However, homogenates of atheromatous and normal aorta did not differ in their ability to accelerate platelet aggregation and fibrin clot formation when tested by a modified Chandler's tube technique. The significance of the findings is discussed and the suggestion made that the mechanisms by which atheromatous aortic tissue might predispose towards intravascular thrombosis in vivo are the ability of such tissue to enhance intrinsic prothrombin activator formation and platelet aggregation.

Effect of normal and atheromatous aortic tissue on platelet aggregation in vitro.

An investigation was made into the platelet-aggregating ability of human aortic tissue. It was found that potent aggregating substances are present in the vascular wall but that the degree and character of platelet aggregation produced was dependent on the method employed in the preparation of the tissue for study. The supernatants of aortic tissue homogenates were found to produce potent irreversible platelet aggregation that occurred after a latent period of one to two minutes. The activity was heat labile, destroyed by collagenase, sedimented by ultracentrifugation, and was considered to be identical or similar to collagen. An extract obtained by boiling aortic tissue with saline was found to cause less powerful reversible platelet aggregation that occurred within 15 to 30 seconds' contact with platelets; the activity was not affected by heating, incubation with collagenase, or ultracentrifugation, and was considered to be due to adenosine diphosphate. Atheromatous aortic tissue when extracted by either method was found to contain less than one half of the potency of normal tissue in causing platelet aggregation.

Platelet function in hairy-cell leukaemia.

A quantitative study of various aspects of platelet function was carried out in eight patients with typical hairy-cell leukaemia (HCL). In at least two patients platelet aggregation was convincingly reduced to more than one aggregating agent (ADP, adrenaline, collagen, thrombin, and ristocetin). Granular storage capacity for {(14)C} 5-HT was reduced in five of the six patients tested. The two patients with definitely abnormal aggregation had the greatest reduction in granular storage pool and the longest bleeding times of those tested but, like the other patients, they did not have a clinical haemostatic defect. It was concluded that a granular storage pool defect (SPD) was at least partly responsible for aggregation abnormalities in HCL since the platelet release reaction in response to thrombin appeared to be normal. All our patients ran a chronic course uncomplicated by any of the factors known to predispose to a platelet SPD acquired in the circulation. Although in the one patient tested before and after splenectomy there was some improvement in platelet aggregation after operation, there was no clear general relationship between defective platelet function and either previous splenectomy or platelet count. Since a direct involvement of the megakaryocytic series in the underlying cell proliferation of HCL seems unlikely, it is concluded that the platelet defect can most reasonably be attributed to the production of abnormal platelets as a result of marrow fibrosis and/or infiltration by hairy cells.

The effect of oxygen on the fibrinolytic enzyme system in vivo.

Arterial hypoxia has been accepted as a potent stimulus to increased fibrinolytic activity in vivo. This study has shown that significant levels of arterial hypoxaemia induced in healthy volunteers by breathing a hypoxic gas mixture have failed to induce changes in the fibrinolytic enzyme system.

Effect of gaboon viper (Bitis gabonica) venom on blood coagulation, platelets, and the fibrinolytic enzyme system.

The action of the venom of the gaboon viper (Bitis gabonica) on blood coagulation, platelets, and the fibrinolytic enzyme system was studied. The results confirm that the venom of Bitis gabonica has a marked anticoagulant action in vitro. The venom appears to impair clot formation by a direct proteolytic action on fibrinogen, releasing soluble breakdown products.

Effect in vitro on platelet function of two compounds developed from the pyrimido-pyrimidines.

VK 774 and VK 744, two new compounds developed from the pyrimido-pyrimidines, have been found to be powerful inhibitors of platelet function tested in vitro. They inhibit adenosine diphosphate (ADP)-induced platelet aggregation, and the release of platelet factor 3 by kaolin, and VK 774 also reduces platelet adhesiveness and inhibits platelet aggregation (;snowstorm' effect) in the Chandler tube system. Although measured percentage whole blood clot retraction was uninfluenced by these drugs the clot produced with VK 774 was friable and soft. VK 774 appears to be the most powerful of these compounds reported so far, being active in some test systems at 10(-6)M, and, if the results of toxicity testing are satisfactory, it should be an important agent for therapeutic trial.

Aggregation of human platelets by commercial preparations of bovine and porcine antihaemophilic globulin.

Infusion of commercial preparations of porcine and bovine antihaemophilic globulin into three haemophilic patients produced transient thrombocytopenia. This platelet-aggregating activity has been shown to be present in a wide range of animal plasmas and is related to the fibrinogen fraction. The mechanism of platelet aggregation by animal fibrinogen is discussed and some inhibitors of the reaction are described.

The metabolism of dihomo-gamma-linolenic acid in man.

Orally administered dihomo-gamma-linolenic acid (DHLA) is well absorbed in man; it appears in blood after ca. 4 hr first as triglyceride ester and later as phospholipid. After sustained-dosing, DHLA penetrated membrane pools and all phospholipid components but, depending on the dosage, reached a metabolic equilibrium in 4-16 days. Intact platelets do not accumulate arachidonate following DHLA administration, and species differences occur in the capacity of animals to metabolize DHLA to arachidonic acid (AA). The rat appears to be unusual in having a very active hepatic delta5-desaturase enzyme system. Potentially antithrombotic changes in platelet function which followed the administration of DHLA to man were accompanied by a significant increase in the capacity of platelets to synthesize PGE1. Concomitant increases in PGE2 synthesis do not apparently result from an increased production of AA and suggest that DHLA, or a DHLA metabolite, interferes with the metabolism of AA. Effects on thromboxane and prostacyclin synthesis are being studied.