Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gram-negative sepsis is oftentimes complicated by activation of coagulation with disseminated intravascular coagulation and microthrombosis. This may contribute to the associated morbidity, multiple organ failure and death. Recent studies have established that the tissue factor-dependent pathway of blood coagulation has a significant participatory role in the initial endotoxin-induced activation of coagulation. Tissue factor (TF), expressed on the surface of activated monocytes and endothelial cells forms cell surface complexes with free circulating factors VII and VIIa. The latter complex proteolytically activates factors X and IX. Recent in vivo experiments have shown that a rapidly neutralizing TF monoclonal antibody prevents and arrests the endotoxin-induced activation of coagulation and similar studies have shown to reduce mortality in baboons. In this study we describe the preparation of a factor VII/VIIa neutralizing monoclonal Fab fragment and characterize its effect on in vivo activation of coagulation during experimental endotoxemia in chimpanzees. Four chimpanzees received a bolus intravenous injection of 4 ng/kg endotoxin in combination with Fab fragments of a factor VII/VIIa neutralizing murine monoclonal antibody (12D10) at a dose of either 50 micrograms/kg (n = 2) or 100 micrograms/kg (n = 2). Four control animals received a bolus injection of endotoxin alone. Administration of the 12D10 Fab fragments, immediately preceding the endotoxin bolus injection, effectively blocked the endotoxin-induced activation of coagulation. Plasma levels of products of in vivo activation, namely F1 + 2, TAT complexes and FpA remained at baseline values. The administration of 12D10 resulted in a rapid decline in factor VII/VIIa antigen levels which remained below 5 ng/ml for 180-240 min, followed by a rapid return to baseline levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Complete inhibition of endotoxin-induced coagulation activation in chimpanzees with a monoclonal Fab fragment against factor VII/VIIa. 779 34

This study investigated whether the pre-surgical plasma levels of TAT and F1 + 2 of patients undergoing major surgery for localized tumours could identify patients at higher risk of thrombosis, and how heparin prophylaxis affected in vivo coagulation after cancer surgery. We measured the pre- and post-operative levels of TAT, F1 + 2, total factor VII (FVIIt) and zymogen FVII (FVIIz) in 117 cancer patients, with and without heparin prophylaxis. The end points of this study were DVT, initially detected by 125I-fibrinogen uptake test and confirmed by ascending venography. Pre-operative [TAT] and [F1 + 2] of the cancer patients were significantly higher than those of age-matched control subjects (n = 50) (P < 0.005 and P < 0.05, respectively); pre-operative [FVII] was not significantly different. One of the 83 patients receiving prophylaxis, and 8/34 not receiving prophylaxis developed post-operative DVT. Of the parameters evaluated, only the pre-operative [TAT] > 3.5 ng/ml identified patients at higher risk for post-operative DVT. Heparin reduced plasma TAT levels and FVII consumption following surgery, suggesting that heparin modulates coagulation associated with cancer surgery. The results of this study also suggest that the pre-operative [TAT] may identify patients with higher risk for post-operative DVT.
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PMID:Preliminary study to identify cancer patients at high risk of venous thrombosis following major surgery. 791 39

Severely burned patients often present a hypercoagulability situation. However, its magnitude, time course, and relationship with organ failure and outcome remains to be established. Forty-three patients were studied on the first and seventh day after burn for hypercoagulability and fibrinolysis parameters. A hypercoagulability and hyperfibrinolysis state was found the first day after burn demonstrated by high levels of activated factor VII (VIIa, p<0.01), thrombin-antithrombin III complex (TAT, p<0.01), tissue plasminogen activator (t-PA, p<0.001) and D dimer (DD, p<0.01) and low levels of antithrombin III (ATIII, p<0.01), protein C (PC, p<0.01), plasminogen (PG, p<0.001) and alpha2 antiplasmin (AP, p<0.001). A paradoxical coexisting hypofibrinolysis was found as suggested by a low global fibrinolytic activity in the euglobulin plasma fraction fibrin plate assay (FA, p<0.01) and high levels of tissue plasminogen activator inhibitor type 1 (PAI-1, p<0.01). On day 7, a less marked hypercoagulability situation was found, with low ATIII (p<0.01) and PC (p<0.01), persisting the hypofibrinolytic situation observed on the first day. Non-survivors (NS) showed higher levels of VIIa (p<0.01), TAT (p<0.05) and t-PA (p<0.05), and lower levels of ATIII (p<0.05), PC (p<0.05) and AP (p<0.001) than survivors (S) on the first day. Also, there was a positive correlation of Marshall organ failure score with ATIII, (r2=0.49, p<0.001), PC, (r2=0.14, p<0.045) and PG levels, (r2=0.41, p<0.0003). Severely burned patients show a state of transient disseminated intravascular coagulation, related to the development of organ failure and outcome.
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PMID:Degree of hypercoagulability and hyperfibrinolysis is related to organ failure and prognosis after burn trauma. 963 Mar 8

Monocyte tissue factor expression is supposed to play an important role in the hypercoagulability of blood in cancer patients. The relation between coagulation parameters and the expression of monocyte membrane proteins involved in hemostasis or monocyte activation was studied in 21 patients with a disseminated malignancy and 21 age- and sex-matched healthy controls. In the cancer patient group no increase of monocyte tissue factor expression was found (8. 4% vs. 7.8%; P = 0.83), but a significant increase of monocyte-bound activated protein C (APC) (28.8% vs. 13.4%; P = 0.009) and monocyte CD16 expression (34.5% vs. 27.0%; P = 0.007) was observed. There was also a significant increase of D-dimers (2.0 vs. 0.2 microg/ml; P = 0.001), a decrease of antithrombin (83.5% vs. 102.0%; P = 0.004), but no increase of TAT complexes (1.7 vs. 1.5 microg/l; P = 0.38) or factor VII(a) (68.5% vs. 75.0%; P = 0.52). The increase of D-dimers was significantly correlated with the monocyte APC (R = 0.60; P = 0. 005), but not with monocyte tissue factor levels (R = -0.22; P = 0. 35) or TAT complexes (R = 0.12; P = 0.60). These results reflect a local rather than systemic thrombin and fibrin formation. It is suggested that the APC formed locally enters the circulation and binds to peripheral blood monocytes. APC bound on monocytes is known to inhibit monocyte cytokine production and might therefore be involved in regulatory responses of monocytes in cancer patients.
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PMID:Increased D-dimer levels correlate with binding of activated protein C, but not tissue factor expression, on peripheral blood monocytes in cancer patients. 1091 81

The administration of menaquinone-4 (MK-4), one of subclasses of vitamin K2, significantly reduces bone loss in postmenopausal osteoporotic women. However, concerns have been raised about whether vitamin K administration alters the hemostatic balance by inducing a thrombotic tendency. We investigated were whether the administration of vitamin K in the form of MK-4 induced a thrombotic tendency in 29 elderly patients with osteoporosis (5 men, 24 women; age range 78.7+/-5.1 years). Patients were administered 45 mg/day (three times a day, 30 min after each meal) of MK-4 for 12 weeks. Blood samples were obtained from the patients at 0, 4 and 12 weeks after the start of MK-4 administration. A number of hemostatic parameters remained stable under the markedly increased plasma levels of MK-4. However, in patients with suspected vitamin K deficiency, whose plasma levels of vitamin K or factor VII were low, vitamin-K-dependent clotting factors such as factor VII and prothrombin were gradually increased after administration of MK-4. No changes in the sensitive molecular markers such as TAT and F1+2, which reflect the amount of thrombin generated in the blood stream, were observed, even in those patients with suspected vitamin K deficiency. These results indicate that MK-4 can be administered safely, with regard to maintaining the hemostatic balance, to osteoporotic patients receiving no anticoagulant therapy.
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PMID:Vitamin K administration to elderly patients with osteoporosis induces no hemostatic activation, even in those with suspected vitamin K deficiency. 1184 34

Epidemiologic studies have shown that exposure to particulate air pollution is associated with short-term increases in cardiovascular morbidity and mortality. These adverse effects of inhaled particulate matter (PM*) may be the indirect result of a PM-induced increase in blood coagulability. This explanation is biologically plausible because prospective studies have shown that increases in blood coagulation parameters are significantly associated with risk of adverse cardiovascular events. We examined the hypothesis that acute exposure to elevated levels of PM causes prothrombotic changes in blood coagulation parameters. Rats with indwelling jugular vein catheters were exposed for 6 hours to filtered air or concentrated ambient PM in New York City air (n = 9 per group per experiment). PM less than 2.5 microm in mass median aerodynamic diameter (PM2.5) was concentrated for animal exposures using a centrifugal concentrator. Blood samples were taken at four time points: before and immediately after exposure and at 12 and 24 hours after the start of exposure. At each time point, six coagulation parameters (platelet count, fibrinogen level, factor VII activity, thrombin-antithrombin complex [TAT] level, tissue plasminogen activator [tPA] activity, and plasminogen activator inhibitor [PAI] activity) were measured as well as all standard blood count parameters. Five concentrated-PM exposure experiments were performed over a period of 8 weeks in the summer of 1999. PM exposure concentrations ranged from 95 to 341 microg/m3. Statistical significance was determined by two-way analysis of variance (ANOVA) on the postexposure data with time and exposure status as main effects. There were no consistent exposure-related effects on any of the end points across the five experiments and no indication of any dose-dependent effects. Most of the statistically significant differences that were observed do not represent adverse effects. Therefore, the results of this study do not indicate that exposure to concentrated ambient PM causes adverse effects on blood coagulation in healthy rats.
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PMID:Effect of concentrated ambient particulate matter on blood coagulation parameters in rats. 1250 39