Heparin and blood coagulation.
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Biomedical subjects
Publications and source records attributed to G Sas.
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Antithrombin III (AT-III) was studied in a thrombophilic family with an abnormal AT-III molecule (antithrombin III Budapest) using a modified crossed immunoelectrophoresis technique, gel filtration, 'rocket' immunoelectrophoresis and a heparin cofactor assay. When agarose was applied in the first phase of the crossed immunoelectrophoresis, the normal and the pathological AT-III revealed identical electrophoretic mobility. However, when heparin was mixed with agarose in the first phase of electrophoresis, the propositus' plasma displayed a different AT-III pattern from normal plasma. His plasma contained the first component of the normal plasma (Immune Antithrombin III1, IAT-III) in a concentration of only 5% of normal, and a protein in high concentration which although immunoreactive to AT-III antisera, had an electrophoretic mobility similar (but not identical to that of IAT-III2. This abnormal protein had no heparin cofactor activity and a molecular size greater than normal plasma AT-III. Unlike AT-III, the addition of heparin did not change the molecular size of the pathogic AT-III molecule significantly. The abnormal protein was present in lower concentrations in the patient's children and at the time of study they had no clinical or laboratory evidence of intravascular coagulation.
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Studies on antithrombin III (AT-III) were made by a modification of the two dimensional crossed immunoelectrophoresis technique and gel filtration. Mixing various quantities of heparin with agarose in the first phase of electrophoresis, AT-III from normal human plasma and serum revealed a heterogeneity which depended on the heparin concentration in the agarose gel. At heparin concentrations higher than 16 u/ml, AT-III displayed three components with different electrophoretic mobilities. The component with the highest mobility (designated immunoantithrombin III1 : IAT-III1) dominated in plasma. In normal serum, however, the quantity of this component was decreased and the two other peaks with a slower electrophoretic mobility (IAT-III2 and IAT-III3) became more evident. Normal human plasma and serum were filtered on Sephadex G-200 and the AT-III concentration measured in the fractions by rocket immunoelectrophoresis. The peaks of AT-111 were found in the same fractions for both plasma and serum and were coincident with the albumin peak of the plasma proteins. However, in the case of serum the AT-III concentration decreased less sharply in those fractions with higher molecular weight than in the corresponding plasma fractions. Analysis of these fractions by crossed immunoelectrophoresis revealed that the two components with slower electrophoretic mobility (IAT-III2 and IAT-III3) had higher molecular size than IAT-III1, that the concentration of IAT-III2 and IAT-III3 was significantly higher in serum, and that the high molecular weight components in plasma and serum were qualitatively identical. It is concluded that high molecular weight complexes between AT-III and activated coagulation factors may be present in normally circulating blood and that their detection and possibly quantitation can be achieved using the heparin/agarose crossed immunoelectrophoresis system.
A series of in vitro studies designed to ascertain the potential in vivo thrombogenicity of human factor IX-containing concentrates is described. Using concentrates obtained from several different Centres the fibrinogen clotting time with some preparations was less than 6 h and/or the recalcification time of normal plasma was shortened. In some preparations, however, the plasma recalcification time was lengthened. Further studies revealed that all diluted factor-IX concentrates generated thrombin after recalcification, and that the rate of thrombin generation appeared to be characteristic of a particular preparation. This characteristic has been designated the TGt50, which is the incubation period in minutes, after recalcification, required to obtain a 50 s clotting time of a fibrinogen substrate. The TGt50 was found to correlate most strongly with recalcification time of celite exhausted plasma (P less than 0.001), but no correlation was observed between it and the immunological antithrombin III or factor-VIII antigen levels. Evidence is presented which suggests that the thrombin generation test and recalcification time of celite exhausted plasma may represent suitable in vitro quality control assays for factor-IX concentrates.
A family with a high incidence of spontaneous thromboembolism has been investigated and those members affected were found to have significantly depressed levels of plasma and serum heparin cofactor activity; i.e., antithrombin III and anti-Xa activity. Further studies revealed that despite a marked diminution of antithrombin III activity in these patients measurement of antithrombin III by immunological techniques showed the levels to be normal. It is concluded that this anomaly represents a defect in the synthesis of the antithrombin III molecule. The abnormality appeared to be inherited but the mode of inheritance could not be determined with the available data.
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