Stuart clotting defect. I. Segregation of an hereditary hemorrhagic state from the heterogeneous group heretofore called stable factor (SPCA, proconvertin, factor VII) deficiency

Genetic variants of hemophilia B: detection by means of a specific PTC inhibitor

Hemophilia B can be divided into at least two mutant forms different from the mild, moderate, and severe categories previously described. In about 90% of hemophilia B patients, PTC-inhibitor-neutralizing activity is reduced in proportion to PTC clotting activity. In about 10% of the patients, PTC-inhibitor-neutralizing activity is fully effective, whereas PTC clotting activity is reduced. Extensive pedigree studies indicate that the presence or absence of inhibitor-neutralizing activity is genetically determined. It is suggested that those hemophilia B mutants with decreased inhibitor-neutralizing material produce decreased amounts of PTC-protein. It is further suggested that those with normal levels of inhibitor-neutralizing material produce normal amounts of PTC-protein, which is structurally altered so as to lose procoagulant activity but which retains inhibitor-neutralizing activity. The latter group may be analogous to CRM(+) mutants described in bacteria and Neurospora.

The anticoagulant activity of lysosomal cationic proteins from polymorphonuclear leukocytes

A cationic protein fraction from rabbit polymorphonuclear leukocyte lysosomes has been shown to exert a potent anticoagulant effect on human blood in vitro. The anticoagulant activity is detectable in the whole blood clotting time, the recalcification time of platelet-rich plasma, the prothrombin time, the partial thromboplastin time, and the thromboplastin generation test. The lysosomal cationic proteins do not inhibit any of the known specific procoagulants. They appear to inhibit clotting by blocking the formation of intrinsic thromboplastin possibly by interfering with the role of phospholipids in the reaction involving Factors V and X and calcium.

AN INVESTIGATION OF THE HEMORRHAGIC DIATHESIS IN PATIENTS RECEIVING COUMARIN AND INDANEDIONE ANTICOAGULANTS

Coagulation studies were carried out on 10 patients who bled during anticoagulant therapy, in whom no other underlying cause for bleeding could be demonstrated, and 10 patients with similar degrees of hypoprothrombinemia who were not bleeding. The average age and sex distribution of the two groups was similar, and no association was noted between the occurrence of hemorrhage and the type of anticoagulant used, the duration of treatment or the nature of the underlying disease. Comparison of the results revealed no differences in the levels of factors II, VII, IX and X or in the glass and silicone (Siliclad) clotting time, the thromboplastin generation test and Thrombotest. It was concluded that all patients on anticoagulant drugs whose prothrombin time is in the therapeutic range or longer are potential bleeders and that one cannot necessarily predict those who will bleed on the basis of coagulation studies.

INACTIVATION OF PURIFIED AUTOPROTHROMBIN I WITH ANTITHROMBIN

Autoprothrombin Ic was obtained by activating prothrombin preparations with autoprothrombin C. Autoprothrombin Ip was obtained by activating prothrombin with the use of calcium ions and purified platelet factor 3. Both of these prothrombin derivatives were found to be inactivated by plasma and serum. Autoprothrombin Ic was studied most extensively and was found to be inactivated by purified antithrombin. When antithrombin was first combined to capacity with purified thrombin the power to neutralize autoprothrombin I was almost eliminated. Autoprothrombin II was not destroyed by antithrombin and was found in serum as the main procoagulant. Most likely it is not in plasma. Autoprothrombin Ic, autoprothrombin Ip, autoprothrombin C, and thrombin all have reactive groups that combine with antithrombin. The activity in 1 mg of purified autoprothrombin Ic was neutralized by 50 ml plasma. One milligram of autoprothrombin C was neutralized by 5 ml plasma, and 7 ml plasma was sufficient to neutralize 1 mg of thrombin. Antithrombin IV is regarded as a kinetic effect and not as a substance. From a review of the literature it is concluded that there is no adequate evidence for appreciable quantities of factor VII in serum, or that it occurs in plasma independent of prothrombin.

THE SEPARATION OF AUTOPROTHROMBIN IcFROM BOVINE PROTHROMBIN PREPARATIONS

Autoprothrombin Icis a degradation product of purified prothrombin which is obtained when the enzyme autoprothrombin C is used for activation. A quantitative method was developed for the assay of autoprothrombin Ic. Conditions were found for activating purified prothrombin so as to obtain the maximum yield of autoprothrombin Ic. Isolation procedures were developed for obtaining a single component. The specific activity was in the range 32,000 to 34,000 units/mg tyrosine or 1440 U./mg. The yield was about 4 mg from 6 liters of plasma. By contrast with autoprothrombin C it did not by itself alter prothrombin activity. In the presence of lipids, calcium ions, and Ac-globulin it was found to be a powerful procoagulant. Plasma and serum contain a substance that destroys the activity. The activity was also destroyed by reduced glutathione, iodoacetate, and ascorbic acid, but it was relatively resistant to SH blocking agents. In the prothrombin utilization test purified autoprothrombin Icgave prothrombin consumption with Stuart plasma and with factor VII deficient plasma. With 0.5 μg in the test mixture (0.3 ml) the prothrombin time of Stuart plasma was completely corrected. With 60 μg the clotting time was 8 seconds.

PURIFICATION AND SOME PROPERTIES OF AUTOPROTHROMBIN C

Methods were developed for the isolation of autoprothrombin C, which is the second enzyme obtained from purified bovine prothrombin. In the presence of lipids and standardized conditions 0.35 μg of the purified autoprothrombin C were sufficient for clotting recalcified plasma in 15 seconds. Some physicochemical properties are as follows: S20, w is 2.27S, the diffusion constant 8.4 × 10−7 cm2/second, and the partial specific volume 0.695. The molecular weight from physicochemical measurements was 21,500. All amino acids were found, but only 1 molecule of methionine. On the basis of amino acid composition the molecular weight was found to be 27,000, giving an average of 24,200 for our two determinations. Prothrombin contains sufficient of each amino acid residue to supply autoprothrombin C and thrombin. Autoprothrombin II, however, has only sufficient amino acids for either autoprothrombin C or thrombin, but not both. The purified autoprothrombin C contained 7% carbohydrate (orcinol) and 3.8% hexosamine. It was stable at pH 7.2 for more than a week at room temperature, and longer in subzero glycerol solution. Autoprothrombin C was used to obtain a single precipitin band in agar diffusion plates with antibody to prothrombin. The band also identified with a single plasma antibody.

PURIFICATION AND SOME PROPERTIES OF AUTOPROTHROMBIN C

Methods were developed for the isolation of autoprothrombin C, which is the second enzyme obtained from purified bovine prothrombin. In the presence of lipids and standardized conditions 0.35 μg of the purified autoprothrombin C were sufficient for clotting recalcified plasma in 15 seconds. Some physicochemical properties are as follows: S20, w is 2.27S, the diffusion constant 8.4 × 10−7 cm2/second, and the partial specific volume 0.695. The molecular weight from physicochemical measurements was 21,500. All amino acids were found, but only 1 molecule of methionine. On the basis of amino acid composition the molecular weight was found to be 27,000, giving an average of 24,200 for our two determinations. Prothrombin contains sufficient of each amino acid residue to supply autoprothrombin C and thrombin. Autoprothrombin II, however, has only sufficient amino acids for either autoprothrombin C or thrombin, but not both. The purified autoprothrombin C contained 7% carbohydrate (orcinol) and 3.8% hexosamine. It was stable at pH 7.2 for more than a week at room temperature, and longer in subzero glycerol solution. Autoprothrombin C was used to obtain a single precipitin band in agar diffusion plates with antibody to prothrombin. The band also identified with a single plasma antibody.