Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

TF antigen and activity are found in abundance in human atherosclerotic plaques, particularly in the lipid-rich core. TF is also readily induced in the arterial wall by balloon injury and accumulates in the resulting neointima. In chronic atherosclerosis, the macrophage is likely to be the major source of TF within the plaque. TF accumulates as an early event associated with the migration of monocytes to the vessel wall in response to chemoattractants, such as MCP-1, and their differentiation into macrophages. As SMC become activated in the developing plaque, they provide a second source of TF. Macrophages and SMC accumulate lipid and become foam cells, ultimately degenerating into a necrotic core rich in TF. Spontaneous plaque rupture or acute interventions expose active TF in the core to circulating blood, triggering thrombosis. In acute arterial injury, SMC appear to be the chief source of TF. In normal vessels, the induction of TF in the medial SMC is not sufficient to generate fibrin, presumably because the TF is not readily accessible on the luminal surface. In contrast, endothelial denudation of previously injured arteries may expose intimal TF to circulating blood, resulting in rapid fibrin deposition. In advanced human atherosclerosis, it is likely that even in areas that do not contain "unstable" or "stable" plaques, the vessel wall is not normal and more closely resembles that of a previously injured artery possessing an active intima. Interventions, such as balloon angioplasty, coronary atherectomy, or stent placement may expose intimal TF, leading to fibrin deposition. As the initiator of coagulation, TF is a potential target for inhibiting the thrombotic complications of atherosclerosis. TFPI (reviewed in 52) is currently under clinical investigation as an anticoagulant and its effects on intimal hyperplasia in animal models are being studied. Direct factor Xa inhibitors, such as tick anticoagulant peptide (TAP) and leech anticoagulant peptide (ATS), are also under investigation (53-54). Finally, the recent crystallization of TF (55) and the TF:VIIa (56) should provide important new insights into the design of molecules for directly inhibiting TF.
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PMID:Tissue factor in the pathogenesis of atherosclerosis. 919 53

Studies of antistasin, a potent factor Xa inhibitor with anticoagulant properties, were performed wherein the properties of the full-length antistasin polypeptide (ATS-119) were compared with the properties of forms of antistasin truncated at residue 116 (ATS-116) and residue 112 (ATS-112). ATS-119 was 40-fold more potent than ATS-112 in prolonging the activated partial thromboplastin time (APTT), whereas ATS-119 inhibited factor Xa 2.2-fold less avidly and about 5-fold more slowly than did ATS-112. The decreased reactivity of ATS-119 suggests that the carboxyl-terminal domain of ATS-119 stabilizes an ATS conformation with a reduced reactivity toward factor Xa. The observation that calcium ion increases the reactivity of ATS-119 but not that of ATS-112 suggests that calcium ion may disrupt interactions involving the carboxyl terminus of ATS-119. Interestingly, ATS-119 inhibited factor Xa in the prothrombinase complex 2-6-fold more potently and 2-3-fold faster than ATS-112. These differences in affinity and reactivity might well account for the greater effectiveness of ATS-119 in prolonging the APTT and suggest that the carboxyl-terminal domain of ATS-119 disrupts interactions involving phospholipid, factor Va, and prothrombin in the prothrombinase complex. The peptide RPKRKLIPRLS, corresponding to the carboxyl domain of ATS-119 prolonged the APTT and inhibited prothrombinase-catalyzed processing of prothrombin, but it failed to inhibit the catalytic activity of isolated factor Xa. Thus, this novel inhibitor appears to exert its inhibitory effects at a site removed from the active site of factor Xa.
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PMID:Selective inhibition of factor Xa in the prothrombinase complex by the carboxyl-terminal domain of antistasin. 980 61

A series of low molecular weight peptide inhibitors of Factor Xa, fragment analogues of ATS and GLS, was designed and synthesized by the SPPS method. The new analogues included different basic amino acids in 109 position. In order to investigate the role of these factors, the newly synthesized peptides were tested for anticoagulant activity. To investigate the change in anticoagulant activity, new peptides were synthesized by replacement of the C-terminal COOH function with CONH2. The biological activity of all compounds was measured in respect to APTT (activated partial thromboplastin time) and IC50 values (the concentrations for doubling APTT clotting times of human plasma) were determined.
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PMID:Design, synthesis and structure-activity relationship of a series of fragment analogues of antistasin (ATS) and ghilantens (GLS). 1608 83

Patients who receive prosthetic heart valve (PHV) implants require mandatory anticoagulation medication after implantation due to the thrombogenic potential of the valve. Optimization of PHV designs may facilitate reduction of flow-induced thrombogenicity and reduce or eliminate the need for post-implant anticoagulants. We present a methodology entitled Device Thrombogenicty Emulator (DTE) for optimizing the thrombo-resistance performance of PHV by combining numerical and experimental approaches. Two bileaflet mechanical heart valves (MHV) designs, St. Jude Medical (SJM) and ATS, were investigated by studying the effect of distinct flow phases on platelet activation. Transient turbulent and direct numerical simulations (DNS) were conducted, and stress loading histories experienced by the platelets were calculated along flow trajectories. The numerical simulations indicated distinct design dependent differences between the two valves. The stress loading waveforms extracted from the numerical simulations were programmed into a hemodynamic shearing device (HSD), emulating the flow conditions past the valves in distinct 'hot-spot' flow regions that are implicated in MHV thrombogenicity. The resultant platelet activity was measured with a modified prothrombinase assay, and was found to be significantly higher in the SJM valve, mostly during the regurgitation phase. The experimental results were in excellent agreement with the calculated platelet activation potential. This establishes the utility of the DTE methodology for serving as a test bed for evaluating design modifications for achieving better thrombogenic performance for such devices.
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PMID:Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs. 2048 11