Platelet function, blood coagulability, and fibrinolysis in patients with low tension glaucoma

Platelet function in vitro and in vivo and certain measurements of blood coagulability and fibrinolysis were examined in 12 patients with low tension glaucoma and the results were compared with those obtained in 12 normal subjects matched for age, race, and sex. The data obtained seem to indicate that patients with low tension glaucoma cannot be readily distinguished from individuals of similar age and sex not afflicted with this disorder by measuring these variables. Thus, a "hypercoagulable state," ie, a thrombotic tendency, does not appear to be of major importance in the pathogenesis of this disorder.

The measurement of thrombin in clotting blood by radioimmunoassay

We have developed a radioimmunoassay for human thrombin using rabbit anti-human thrombin IgG. The assay can measure 2 ng thrombin/ml plasma, 500-fold more sensitive than clotting assays. Human prothrombin is less reactive in the assay than thrombin by at least four orders of magnitude, and there is no demonstrable cross-reactivity with human factor Xa, the clotting factor structurally most similar to thrombin. The assay does not detect thrombin bound to anthithrombin III. Using the assay, we have demonstrated that plasma from 20 normal subjects does not contain detectable thrombin. We measured thrombin generation in clotting blood in polypropylene tubes and observed that thrombin appears (approximately equal to 3 ng/ml) within 45 S-5 min after venipuncture. This material is thrombin, not intermediates of prothrombin activation, since it disappears after addition of heparin, which promotes thrombin antithrombin III complex formation. After a plateau of 2-10 min, there is further thrombin generation, which results in clotting after 15-27 min at a level of 40-50 ng thrombin/ml. The thrombin generated 9-25 min before clotting may activate factors V and VIII and stimulate platelet aggregation and release. In contrast, the cascade hypothesis assigns a role for thrombin only late in blood clotting. Radioimmunoassay of thrombin and other clotting factors will be useful for clinical and physiological studies of blood clotting especially since the assay seems specific for thrombin and is independent of other activities that affect bioassays.

The binding of 1-anilino-8-naphthalenesulfonate, heparin, salicylate and caprylate by human antithrombin III

The binding of 1-anilino-8-naphthalenesulfonate to human antithrombin III was studied by fluorescence enhancement of the fluorophor and fluorescence quenching of the protein emission. Two molecules of 1-anilino-8-naphthalenesulfonate were found to bind per antithrombin molecule with an average dissociation constant of 4.4-10(-5) M. The binding of heparin to antithrombin was studied by ultraviolet difference spectroscopy. The stoichiometry of the heparin binding indicated 1.8 binding sites with an average dissociation constant of 4.3 - 10(-6) M. Further the fluorometric competition experiments with 1-anilino-8-naphthalenesulfonate, heparin, salicylate and caprylate indicated two different classes of anion binding sites on the antithrombin molecule.

Cold activation of complement i. presence of coagulation-related activator

Determination of the complement titer in the serum and plasm of 120 patients with chronic liver diseases showed that in eight (7%) patients with cirrhosis of the liver, chronic active or chronic inactive hepatitis complement in the serum was less than half in the plasma. The dissociation of complement serum and plasma was due to cold activation of the classical pathway of complement in vitro since serum drawn from these patients at 37 degrees C lost hemolytic activity in 4 hours when transferred to a cold environment. Neither HB antigen nor cryoglobulin participated in this phenomenon. The activation of complement in the cold could be prevented by increasing the ionic strength, or by adding vitamin E or, to a lesser extent its vehicle HCO-60, while heparin, Trasylol, soybean trypsin inhibitor, or hirudin had no effect. Trans-AMCHA prevented activation in one case. It is speculated that a factor appearing as a result of blood clotting is able to activate the classical pathway of complement in the cold; it is probably not related to Hageman factor (factor XII), factor VII, thrombin, kallikrein.

Hereditary antithrombin III deficiency. Effect of antithrombin III deficiency on platelet function

Antithrombin III (AT III) is the main physiologic inhibitor of thrombin, and activated factors X and IX as well. Normal levels of AT III appear to be necessary to maintain blood fluidity and to prevent thrombosis. Four families with AT III deficiency and recurrent venous thromboembolism have been reported on. We present an additional family with AT III deficiency and a high incidence of thromboembolism. AT III levels were determined by both a functional and an immunologic assay. Results of platelet function tests, not previously reported in persons with AT III deficiency, were found to be normal. Following gel filtration, the platelets were very sensitive to thrombin. Thrombin-induced platelet aggregation appears to be dependent on a balance between the amount of thrombin and AT III present.

[Blood coagulation and fibrinolysis in women receiving estrogen, gestagen and estrogen-gestagen-contraceptives (author's transl)]

Eight femal subjects received a contraceptive with a low estrogen content (Neogynon), the estrogen component (50 mug ethinylestradiol) and consecutively the gestagen component (250 mug D-Norgestrel) of the contraceptive. Each treatment cycle was followed by a control cycle. At various times of the control and therapy cycles several coagulation and fibrinolytic parameters were investigated. Statistical analyses were performed by multivariate two-factorial analysis of variance. Plasminogen exhibities a statistically significant increase during the treatment with ethinylestradiol and the combination of this steroid with D-norgestrel. No significant changes were found for all other parameters, including partial thromboplastin time, fibriogen, factors X, IX, VIII, factor VIII-related antigen, antithrombin III and fibrin(ogen)degradation products.

Hereditary antithrombin III deficiency and thromboembolic disease

Two teenage brothers with recurrent thromboembolic disease were found to have antithrombin III deficiency. A family study spanning four generations revealed a total of 10 members with antithrombin III deficiency. Five of the 10 affected family members have had thrombotic problems. Antithrombin III deficiency was documented by coagulation assays measuring heparin cofactor, anti-Factor Xa, and progressive antithrombin activity; the level of antithrombin III antigenic material measured by immunoelectrophoresis was low in subjects with abnormal coagulation assays. The clinical features which may lead one to suspect the hereditary hypercoagulable condition of antithrombin III deficiency are reviewed.

Inherited antithrombin-III deficiency causing mesenteric venous infarction: a new clinical entity

Primary superior mesenteric venous thrombosis is sometimes preceded by peripheral thrombophlebitis. Inherited antithrombin-III deficiency is a recently recognized autosomal dominant trait, which is characterized by thrombophlebitis and pulmonary embolism. This case report illustrates many features of both entities and strongly suggest a causal relationship. While long-term therapy has yet to be established, prophylactic therapy is recommended when asymptomatic individuals with known antithrombin-III deficiency are at increased risk of thrombosis. The efficacy of heparin alone has been unreliable, whereas Coumadin has been encouraging. Antithrombin-III concentrates are being developed and theoretically should be helpful. Patients with thrombophlebitis or pulmonary embolism should be suspected of having antithrombin-III deficiency. Such individuals also represent one mechanism to explain "primary" mesenteric venous thrombosis.