PubMed · 14958284
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A FIEHRER. 1952. [Coagulating factors].. https://pubmed.ncbi.nlm.nih.gov/14958284/
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INTRODUCTION: Cell surface tissue factor (TF) is normally encrypted, but can be activated by various cellular perturbations. Exposure of TF bearing cells to calcium ionophore has been reported to increase TF activity, de-encrypt TF, by phosphatidylserine (PS)-dependent and -independent mechanisms. Our aim has been to examine at the single cell level, if increased cell surface PS coincided with increased cell surface TF antigen, and cell death (necrosis, 7-AAD-intercalation), and relate this to monocyte- and microparticle (MP)-associated procoagulant activity. MATERIALS AND METHODS: We exposed lipopolysaccharide-stimulated, human, elutriation-purified, cryopreserved TF bearing monocytes to increasing concentrations of calcium ionophore (A23187) and measured procoagulant activity in cells and supernatants. These measurements were compared with quantification of cell surface TF and PS (Annexin V) and of cell necrosis (7-AAD) by flow cytometry, and complemented by confocal microscopy. RESULTS: We observed that calcium ionophore increased cellular and MP-associated TF activity, but not cell surface TF antigen. The discrepancy between TF activity and TF antigen coincided with a dose-dependent increase in the number of cells expressing PS. These cells were to a large extent necrotic and many of them also expressed TF. CONCLUSIONS: We suggest such TF positive dying cells to contribute to the discordance between TF activity and TF expression. Calcium ionophore also increased MP-associated TF activity and release of MPs may be a way to disseminate procoagulant activity. Our findings emphasize the importance of adequately assessing cell death and taking into consideration its possible role in experiments with calcium ionophore.
Thrombophilia is the increased tendency to thrombosis. Inherited and acquired factors may determine thrombophilia. Some physiologic conditions, such as pregnancy are themselves "thrombophilic". In pregnancy, in fact, there is a decrease of all natural anticoagulant systems, such as antithrombin, protein C and protein S that are partially compensated by an increased fibrinolysis. It has been well established that women with thrombophilic disorders are at greater risk of venous thromboembolism in pregnancy and puerperium. It has also been observed that those women have higher prevalence of those obstetric complications in which microplacental thrombosis may play a pathogenetic role, such as placental abruption, preeclampsia, intrauterine growth restriction, intrauterine fetal death, repeated spontaneous miscarriage. Given that those complications are not always associated with maternal thrombophilia, controversy still exists on the exact impact of the disorders with the adverse pregnancy outcomes. While we are convinced that thrombophilias are extensively implicated in pregnancy complications, we feel that there has not been completely elucidated the role of the different factors, the gestational age at which those factors may intervene, nor has been given enough relevance to the weight of fetal thrombophilias in the origin of some specific form of those obstetric complications. We should bear in mind that some thrombophilias may be inherited from the mother, the father or both. Our hypothesis is that maternal thrombophilias may be responsible for venous thromboembolism, preeclampsia HELLP and eclampsia, whereas fetal thrombophilia, may account for IUGR or stillbirth. This last would also explain some stillbirth or repeated late (>10 gestational weeks) miscarriage observed in non-thrombophilic mothers. The two sides of thrombophilia may, of course, concur, resulting in the more severe clinical presentations.
The tunable in vitro blood clotting activity of high-surface-area hemostatic bioactive glass is evaluated by Thromboelastograph, a clinical instrument for quantifying changes in blood during coagulation. The hemostatic trends associated with hemostatic bioactive glass and a new preparation of spherical hemostatic bioactive glass, along with similar Si- and Ca-containing oxides, are described and related to Si:Ca ratios, Ca2+ availability and coordination environment, porosity, DeltaHHydration, and surface area. Hemostatic bioactive glass is a new material with an excellent efficacy for inducing hemostasis and is chemically distinct from the traditional bioglass employed for bone growth.