Sex differences in the antithrombotic effects of aspirin.

Aspirin inhibits platelet function by acetylating platelet cyclooxygenase. Recent clinical trials indicate that aspirin is a promising antithrombotic agent against both venous and arterial thrombosis, but somewhat surprisingly this protective effect appears to be limited to males. To examine the potential sex-related differences in response to aspirin, we developed an animal model for quantitating fibrin accretion into an injury-induced thrombus and used it to study the effects of aspirin on thrombus size in male and female rabbits.

Thrombogenic effect of high-dose aspirin in rabbits. Relationship to inhibition of vessel wall synthesis of prostaglandin I2-like activity.

Aspirin is a promising antithrombogenic agent. It inhibits the generation of thromboxane A(2) by acetylating platelet cyclo-oxygenase. Aspirin also inhibits vessel wall production of PGI(2) which is an inhibitor of platelet aggregation, and therefore is potentially thrombotic.

The araC promoter: transcription, mapping and interaction with the araBAD promoter.

The start sites of the araC and araBAD gene messenger of E. coli were located by transcription in vitro from short DNA fragments, by high magnification electron microscopy and by genetic mapping. Transcription for these messengers proceeds in opposite directions from the start sites that are 150 base pairs apart.

Combined use of leg scanning and impedance plethysmography in suspected venous thrombosis. An alternative to venography.

Venography is the standard method for the diagnosis of venous thrombosis but is invasive and may cause discomfort. We evaluated the combination of impedance plethysmography and 125I-fibrinogen leg scanning as an alternative to venography in 200 symptomatic patients. One or both of these less invasive tests was positive in 81 of 86 patients with positive venograms (sensitivity of 94 per cent) and both were negative in 104 of 114 patients with negative venograms (specificity of 91 per cent).

Prevention of venous thrombosis in patients with intracranial disease by intermittent pneumatic compression of the calf.

In a randomized study of 128 patients, we evaluated intermittent pneumatic compression of the calf in the prevention of leg scan-detected venous thrombosis in intracranial disease. Pneumatic compression of the calf for 5 days reduced the rate of venous thrombosis from 12 of 63 control patients (19.1 percent) to one of 65 patients (1.

Relationship between the anticoagulant and antithrombotic effects of heparin in experimental venous thrombosis.

The relationship between the antithrombotic and anticoagulant effects of heparin was assessed using venous thrombi in rabbits. Accretion of 125I-fibrinogen onto jugular vein thrombi was used to assess the antithrombotic effect of heparin, and the protamine sulfate titration test (heparin activity) and the activated partial thromboplastin time (APTT) were used to measure its anticoagulant effect. The effect of heparin on jugular vein bleeding times was also measured in a separate group of animals.

Low dose heparin prophylaxis.

Low dose heparin prophylaxis reduces the frequency of postoperative calf vein thrombosis, popliteal and femoral vein thrombosis and nonfatal pulmonary embolism in patients undergoing elective abdominal surgery. In a recent study, it produced an eight-fold reduction in the frequency of major pulmonary emboli detected at autopsy in general surgical patients. Low dose heparin prophylaxis has been less effective in reducing the incidence of venous thromboembolism in patients undergoing hip surgery; in some studies this has been associated with an increased risk of bleeding.

25-Hydroxycholecalciferol levels in bedouins in the Negev.

25-Hydroxycholecalciferol (25-HCC) levels were measured in 31 bedouin females and eight bedouin male tribesmen and compared with the levels in Jewish males and females in Beersheba. In nonpregnant bedouin women the mean 25-HCC level was 25.4 ng/ml +/- 9.