PubMed · 692557
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C Hougie. 1978-10-05. "Passovoy defect".. https://doi.org/10.1056/nejm197810052991417
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The inhibitory capacity of the natural protein C (PC)/protein S (PS) system was evaluated measuring both the functional activity and the antigen level of both these inhibitors in 30 uremic patients before and after a dialytic treatment and in 30 healthy normal volunteers. PC functional activity was determined by two methods, one clotting and one chromogenic. PS antigen level was measured both as free protein and as total content. Unlike previous authors, we found that PC functional activity and the antigen level were normal in patients before dialysis, with a significant increase after. PS functional activity and free and total antigen levels were all normal before dialysis, and all except free antigen showed a significant post-treatment rise.
The purpose of this study was to purify and identify the proteinase-like substance previously recognized as responsible for the Na+/K(+)-ATPase stimulating property of plasma from insulin-dependent diabetic subjects. Anion-exchange chromatography followed by two-step heparin affinity chromatography resulted in a fraction highly enriched in both potent Na+/K(+)-ATPase stimulating activity and potent proteolytic activity. Approx. 400 micrograms of purified protein was isolated from 62 mg of starting plasma proteins. When analyzed on sodium dodecyl sulfate gels the active fraction consisted mainly of one polypeptide band with an apparent molecular mass of 66 kDa under either reducing or nonreducing conditions. The proteinase-like properties of the purified fraction were further revealed by its ability to clot plasma, split fibrinogen with production of fibrinopeptide A and induce shape change in human platelets and irreversible platelet aggregation in the presence of the stable analogue of endoperoxides U46619. Its additional capacity to affect platelet phosphoinositol metabolism was shown by the stimulation of protein kinase C-dependent phosphorylation of 47 kDa platelet membrane protein. In designing an identification protocol for the purified fraction, it was postulated that plasma proteinases are probably bound to their inhibitors, to form a stable covalently linked complex. The possibility that a proteinase-proteinase inhibitor complex was purified instead of single proteinase(s) was investigated. Neither trypsin nor neutrophil elastase were present in the active fraction whereas, among the possible plasma proteinase inhibitors tested, immunoreactivity was observed only in the presence of alpha 1-antitrypsin (alpha 1 AT) antiserum. Double immunodiffusion showed that control human alpha 1 AT and the plasma-purified fraction shared common antigens. Furthermore, both isoelectric focusing and amino acid composition analysis showed that the two substances were similar. The results obtained indicate that alpha 1 AT is apparently the only active component of the purified fraction from the plasma of insulin-dependent diabetics, thus suggesting that an altered form of the inhibitor is responsible for the broad range of proteinase-like effects elicited by the plasma-purified fraction.
The plasminogen activator activity of 31 human brain tumor samples was assessed and the results correlated with clinical parameters and the postoperative occurrence of venous thrombosis. A significant negative correlation was found between plasminogen activator activity and venous thrombosis (P = 0.02), while positive correlations were observed between plasminogen activator activity and peritumoral brain edema (P = 0.03) and alpha 2 antiplasmin measured in the systemic circulation (P = 0.01). Tissue plasminogen activator was found in higher concentrations in meningioma tissue but did not correlate significantly with the occurrence of venous thrombosis. The results of this study suggest a local enzymatic degradation effect of plasminogen activator on thrombogenic substances present in the brain tumor and/or its environment.