Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein C inhibitor (PCI) is a heparin binding serine protease inhibitor in plasma, which exerts procoagulant activity by inhibiting thrombomodulin-bound thrombin or activated protein C (APC). Since the role of PCI in vivo is largely unknown we generated genetically modified mice with expression of human PCI mRNA in hepatocytes only. Three transgenic lines have been characterized. Transgenic mice did not show gross developmental abnormalities. Two lines showed a pericentral and one line showed a periportal expression pattern of human PCI mRNA in the liver. Genetically modified mice secreted a functional transgenic protein into the circulation (3-5 microg/ml plasma in heterozygous mice and 10 microg/ml in homozygous mice), which inhibited human APC activity in the presence of heparin. Interestingly, transgenic mice in which human PCI was expressed periportally in the liver had the highest specific activity. Endogenous mouse PCI mRNA could only be detected in the male and female reproductive system, but not in the liver, indicating that endogenous PCI levels in the circulation are low or even absent in mice. These results demonstrate that the human PCI transgenic mice are a suitable model for studying the in vivo role of PCI in blood coagulation.
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PMID:Characterization of transgenic mice that secrete functional human protein C inhibitor into the circulation. 1066 61

Hemostatic abnormalities were examined in 55 patients during maintenance hemodialysis (HD). Before HD, plasma protein C and protein S antigens were almost within the normal range, while plasma thrombin-antithrombin III complex (TAT III) and plasmin-plasmin inhibitor complex (PPIC) levels in HD patients were increased slightly, and plasminogen activator inhibitor 1 level was significantly increased, compared to that in normal volunteers. Plasma activated protein C (APC) and protein C inhibitor (PCI) complex and APC alpha 1 antitrypsin (alpha 1AT) complex were not detected in normal volunteers; however, plasma APC-PCI complex was increased in 36 of the patients and plasma APC-alpha 1AT complex was increased in 25 patients. Plasma PCI levels in these patients before HD were significantly decreased. Plasma TAT, PPIC, and tissue type plasminogen activator levels were significantly higher before HD than after 1 hour HD and at the end of HD, while the changes in plasma protein C antigen, protein S antigen, PCI antigen, APC-PCI complex, and APC-alpha 1AT complex were not significant after 1 hour of HD or at the end of HD compared to levels before HD. Plasma PCI levels were correlated with APC-PCI complex, suggesting that decreased PCI levels might be caused by the activation of protein C.
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PMID:Increased activated protein C: protein C inhibitor complex and decreased protein C inhibitor levels in patients with chronic renal failure on maintenance hemodialysis. 1072 91

Protein C inhibitor (PCI) regulates the anticoagulant protein C pathway by neutralizing activated protein C and thrombin-thrombomodulin complex in the human hemostatic system. In this study, we cloned a full-length bovine PCI cDNA encoding a putative 19-residue signal peptide and a 385-residue mature protein; this showed 70.6%, 70.6%, 57.5% and 59.6% amino acid sequence homology with the human, rhesus monkey, rat and mouse PCIs, respectively. Bovine PCI mRNA (2.1 kb in size) was expressed strongly in the liver, and moderately in the kidney and testis, but not in other tissues tested. Bovine PCI has a putative reactive site peptide bond, Lys-Ser, that is different from the reactive site sequence (Arg-Ser) of other species' PCI. We found that bovine PCI transiently inhibits bovine plasmin, but not human plasmin. Western blot analysis showed that the reactive site of bovine PCI is cleaved during the course of complex formation with bovine plasmin; degraded PCI is released from the complex gradually concomitant with the recovery of plasmin activity. These findings suggest that bovine PCI plays a role not only in the protein C pathway but also in the fibrinolytic activity of bovine hemostatic system.
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PMID:Bovine protein C inhibitor has a unique reactive site and can transiently inhibit plasmin. 1073 84

alpha-Thrombin stimulation of human platelets initiates inside-out signaling to integrin alpha(IIb)beta(3) (glycoprotein IIb/IIIa), resulting in the exposure of ligand binding sites. In the present study, the regulation of alpha(IIb)beta(3) via protein kinases was investigated in platelets permeabilized with streptolysin O by introducing peptides that interfere with these enzymes and with possible regulatory domains in the cytosolic tail of the beta(3) subunit. Compared with intact platelets, the permeabilized platelets preserved >80% of the aggregation, secretion, and alpha(IIb)beta(3) ligand binding capacity. The peptide YIYGSFK, a substrate for Src kinases, inhibited alpha-thrombin-induced ligand binding to alpha(IIb)beta(3), but a reversed peptide with Y-->F substitutions (KFSGFIF) had no effect. Ligand binding to alpha(IIb)beta(3) was also inhibited by the peptide RKRCLRRL, which binds irreversibly to the catalytic domain of protein kinase C. Peptides corresponding to parts of the protein C inhibitor and beta(2)-glycoprotein I were used as negative controls and failed to interfere with ligand binding. Possible target domains for protein kinases are present in the cytoplasmic tail of the beta(3) subunit. The LLITIHDR peptide, matching the membrane-proximal domain of beta(3) (residues 717 to 724), had no effect, but NNPLYKEA (residues 743 to 750), EATSTFTN (residues 749 to 756), and TNITYRGT (residues 755 to 762), which mimicked overlapping domains of the carboxy-terminal part of beta(3), reduced alpha-thrombin-induced ligand binding by 60+/-4%, 97+/-1%, and 97+/-2% (n=3) at 500 micromol/L peptide, respectively. These observations indicate that Src kinases and protein kinase C take part in inside-out signaling to integrin alpha(IIb)beta(3) and identify target domains in beta(3) that contribute to the regulation of this integrin.
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PMID:Inhibition of platelet integrin alpha(IIb)beta(3) by peptides that interfere with protein kinases and the beta(3) tail. 1084 85

The use of oral contraceptives (OC) causes disturbances of the procoagulant, anticoagulant and fibrinolytic pathways of blood coagulation which may contribute to the increased risk of venous thrombosis associated with OC therapy. Here we report the results of a cycle-controlled randomized cross-over study, in which we determined the effects of so-called second and third generation OC's on a number of anticoagulant parameters. In this study, 28 non-OC using women were randomly prescribed either a second generation (150 microg levonorgestrel/30 microg ethinylestradiol) or a third generation OC (150 microg desogestrel/30 microg ethinylestradiol) and who switched to the other OC after a two month wash out period. The anticoagulant parameters determined were: antithrombin (AT), alpha2-macroglobulin (alpha2-M), alpha1-antitrypsin, protein C inhibitor (PCI), protein C, total and free protein S and activated protein C sensitivity ratios (APC-sr) measured with two functional APC resistance tests which quantify the effect of APC on either the activated partial thromboplastin time (aPTT) or on the endogenous thrombin potential (ETP). During the use of desogestrel-containing OC the plasma levels of alpha2-M, alpha1-antitrypsin, PCI and protein C significantly increased, whereas AT and protein S significantly decreased. Similar trends were observed with levonorgestrel-containing OC, although on this kind of OC the changes in AT, PCI and protein S (which was even slightly increased) did not reach significance. Compared with levonorgestrel, desogestrel-containing OC caused a significant decrease of total (p <0.005) as well as free protein S (p <0.0001) and more pronounced APC resistance in both the aPTT (p = 0.02) and ETP-based (p <0.0001) APC resistance tests. These observations indicate that the activity of the anticoagulant pathways in plasma from users of desogestrel-containing OC is more extensively impaired than in plasma from users of levonorgestrel-containing OC.
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PMID:A randomized cross-over study on the effects of levonorgestrel- and desogestrel-containing oral contraceptives on the anticoagulant pathways. 1092 60

The effect of urinary protein C inhibitor (uPCI) on disseminated intravascular coagulation (DIC) was investigated using an experimental DIC in rats. uPCI (0.5 and 1.0 mg/kg) was continuously administrated into the left femoral vein of the rats with lipopolysaccharide (50 mg/kg)-induced DIC. In all doses, uPCI significantly prevented the drastic changes in the parameters such as fibrinogen concentration, activated partial thromboplastin time (APTT), prothrombin time (PT), fibrin/fibrinogen degradation products (FDP) level, aspartate amino-transferase (AST) level and alanine aminotransferase (ALT) level. Furthermore, uPCI significantly inhibited the increase in the levels of plasma kallikrein and thrombin which act not only as the procoagulant proteases but also as the chemotactic factors to neutrophils and monocytes. These results show that uPCI may prevent hypercoagulation, the induction of secondary fibrinolysis and organ failure in the DIC model. Therefore, uPCI may be a useful agent for the clinical treatment of DIC.
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PMID:Effect of urinary protein C inhibitor on lipopolysaccharide-induced disseminated intravascular coagulation in rats. 1092 70

Plasma levels of activated protein C (APC)-protein C inhibitor (PCI) were significantly increased in patients with disseminated intravascular coagulation (DIC), thrombotic thrombocytopenic purpura (TTP), acute myocardial infarction (AMI), pulmonary embolism (PE), or deep vein thrombosis (DVT) and in patients undergoing hemodialysis (HD). Plasma levels of APC-alpha(1)-antitrypsin (AT) complex were significantly increased in patients with DIC and in those with TTP. Plasma levels of PCI were significantly decreased in patients with DIC, non-DIC, or TTP and in those undergoing HD. In the pre-DIC stage, the plasma levels of APC-PCI complex were significantly increased but not those of APC-alpha(1)-AT complex. These data suggest that measurements of APC-PCI complex and APC-alpha(1)-AT complex may be useful for the diagnosis of DIC. After treatment of DIC, the plasma levels of APC-PCI complex and APC-alpha(1)-AT complex were significantly decreased, but not those of PCI. Plasma levels of thrombin-antithrombin complex (TAT), plasmin-alpha(2)-plasmin complex (PPIC), D-dimer, and soluble fibrin monomer (SFM) were markedly increased in patients with DIC or pre-DIC and were moderately increased in patients with non-DIC, TTP, AMI, PE, or DVT and in those undergoing HD. The receiving operating characteristic (ROC) analysis showed that SFM and the APC-PCT complex are useful markers for diagnosis of DIC. The specificity of plasma TAT and PPIC levels was low. The positive rate of APC-PCI complex was higher than 90% with DIC, TTP, AMI, PE, and it was higher than 60% with DVT and HD. Since the APC-PCI complex was elevated not only in patients with venous thrombosis but also in those with arterial thrombosis, components of the protein C pathway might be useful markers for the diagnosis of arterial thrombosis.
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PMID:Plasma levels of activated protein C-protein C inhibitor complex in patients with hypercoagulable states. 1093 61

We compared urinary protein C inhibitor (uPCI) with low molecular weight heparin (LMWH) in terms of the effect on the pathophysiology of disseminated intravascular coagulation (DIC), such as hypercoagulation, induction of secondary fibrinolysis and organ failure, using lipopolysaccharide (LPS)-induced DIC in rats. The uPCI (0.5 and 1.0 mg/kg) administration significantly inhibited both the decrease in fibrinogen level and the increase in fibrin/fibrinogen degradation products (FDP) level, and the effects compared favorably with those of LMWH (100 and 200 IU/kg). Both uPCI (0.5 and 1.0 mg/kg) and a low dose of LMWH also inhibited the increases in the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), thrombin, and plasma kallikrein equally, but a high dose of LMWH did not inhibit the changes in those parameters. Furthermore, uPCI dose-dependently prevented the prolongation of activated partial thromboplastin time (APTT), while LMWH excessively prolonged APTT at a high dose. These results suggest that the preventive effect of uPCI on the pathophysiology of DIC compares favorably with that of LMWH, including the lack of a hemorrhagic reaction in contrast to LMWH.
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PMID:Urinary protein C inhibitor as a therapeutic agent to disseminated intravascular coagulation (DIC): a comparison with low molecular weight heparin in rats with lipopolysaccharide-induced DIC. 1099 2

Chronic renal failure (CRF) courses with both systemic inflammatory reaction and haemostatic activation. We explored the relationship of these processes with plasma levels of free, activated protein C (APC) and complexes of APC with its inhibitors in patients with CRF under conservative treatment. Plasma concentrations of inflammatory cytokines [tumour necrosis factor alpha (TNFalpha) and interleukin 8], acute-phase proteins (C-reactive protein, fibrinogen, alpha1-anti-trypsin and von Willebrand factor), and markers of haemostatic activation (thrombin-anti-thrombin complexes, plasmin-anti-plasmin complexes, and fibrin and fibrinogen degradation products) were higher in patients than in controls. Inflammatory and haemostatic markers were significantly and positively correlated. Total plasma APC and APC:alpha1-anti-trypsin (alpha1AT) complexes were 44% and 75% higher in patients than in controls (P = 0.0001), whereas free APC was 20% lower (P < 0.015). No significant difference was observed in APC:protein C inhibitor (PCI) complexes between both groups. The free/total APC ratio was significantly lower in patients than in controls (P < 0.0001). Total plasma APC and APC:alpha1AT were positively correlated with activation markers of haemostasis and acute-phase proteins, whereas free APC was inversely correlated with plasma levels of creatinine, acute-phase proteins and fibrin degradation products (FnDP). Systemic inflammation and activation of haemostasis are interrelated processes in CRF. APC generation was increased in response to elevated thrombin production, but the inflammatory reaction, associated with increased synthesis of alpha1AT, reduced its anticoagulant effect. Lower free plasma APC in CRF may be pathogenically associated with atherothrombosis, a major cause of death in this disease.
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PMID:Increased activation of protein C, but lower plasma levels of free, activated protein C in uraemic patients: relationship with systemic inflammation and haemostatic activation. 1144 82

We investigated the relationship between the procoagulant protease-inhibitory activity and the N-glycan structures in urinary protein C inhibitor (uPCI) by sequential exoglycosidase digestions based on the N-glycan structures elucidated in this report. uPCI was glycosylated on the three potential N-glycosylation sites, asparagines 230, 243 and 319 (N230, N243 and N319) in the molecule and had four biantennary complex type sugar chains. The inhibitory activities of uPCI toward thrombin and plasma kallikrein were little changed by the sequential removal of N-acetylneuraminic acid and galactose residues from the termini and N-acetylglucosamine residues from the branches of the N-glycans. However, the inhibitory activities were markedly decreased by further removing alpha-mannose residues from the trimannosyl cores of the N-glycans. These results suggest that the trimannosyl cores of N-glycans are important for uPCI to inhibit the procoagulant protease.
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PMID:The trimannosyl cores of N-glycans are important for the procoagulant protease-inhibitory activity of urinary protein C inhibitor. 1158 40


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