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)

Aprotinin reduces blood loss after cardiac surgery, particularly in patients taking aspirin. This study was performed to evaluate whether the reduction of contact phase activation by aprotinin is related to decreased complement activation during blood activation. Two hundred patients were prospectively operated on for coronary artery bypass. Aprotinin was used in the cardiopulmonary bypass (CPB) prime if aspirin was not discontinued 10 days before surgery and in patients undergoing second operation (n = 102). Blood loss was significantly reduced in patients receiving aprotinin (596 +/- 309 ml vs 754 +/- 329 ml without aprotinin; p = 0.0001), as was the need for transfusion (13% vs 34% without aprotinin; p = 0.0001) after surgery. Blood activation has been studied in 60 patients. Multivariate analysis showed that contact phase activation, as assessed by maximum values of C1 inhibitor/kallikrein complexes, was reduced by aprotinin treatment (p < 0.0001). Fibrinolytic activity decreased with aprotinin treatment, as reflected by lower values of D-dimers at the end of CPB (p < 0.0001). In addition, thrombin generation, as assessed by F1 + 2 scission peptide, was reduced by aprotinin (p = 0.01). However, the stepwise regression model emphasized that activation of the alternative and classic complement pathways, as reflected by C3b/c and C4b/c levels, was not affected by aprotinin; neither was leukocyte activation, as reflected by elastase release. These results suggest that aprotinin does not combine the reduction of complement activation with the reduced activation of the contact phase, fibrinolysis, or coagulation during CPB for coronary artery surgery.
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PMID:Reduction of blood activation in patients receiving aprotinin during cardiopulmonary bypass for coronary artery surgery. 894 19

Cirrhosis is associated with compromised hemostasis and coagulopathy during orthotopic liver transplantation (OLT). It has been suggested that hemostasis is better preserved during OLT in primary biliary cirrhosis (PBC) than other cirrhotic states. The aim of this study was to compare coagulation and fibrinolysis in 15 patients with PBC with 31 patients with other liver disease before and during OLT. Preoperatively, both groups had subnormal mean levels of prekallikrein, factor XIIa, antithrombin III (ATIII), plasminogen, and alpha2-antiplasmin. C1 esterase inhibitor and kallikrein inhibition in PBC was higher than the normal range (P < .01), but not in non-PBC. Non-PBC had lower median fibrinogen levels and shorter euglobulin clot lysis times (ECLT) (P < .05). Tissue plasminogen activator (tPA) antigen levels did not differ between groups but were elevated from the normal range, as were median thrombin-antithrombin complexes (TAT). Plasminogen activator inhibitor (PAI) activity was significantly higher in PBC (0.0041). Perioperatively in the PBC group during the early anhepatic phase of OLT, there was more thrombin generation, as evidenced by higher TAT levels (P = .0455) and less hyperfibrinolysis with longer ECLTs. We hypothesize that there is a preserved capacity to generate thrombin and less fibrinolytic activation during the anhepatic phase of OLT, and we suggest that, in PBC, the use of antifibrinolytic agents may have an adverse effect.
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PMID:Coagulation and fibrinolysis in primary biliary cirrhosis compared with other liver disease and during orthotopic liver transplantation. 904 19

Heparin-coated systems for extracorporeal lung-assist (ECLA) were developed to reduce hemorrhagic risk by lowering the systemic heparinization, monitored by global tests, e.g. activated coagulation time (ACT) and activated partial thromboplastin time (APTT). Since this strategy gives no insight into procoagulant states, five ARDS patients receiving ECLA with heparin-coated systems were investivated for changes in coagulation using both global and extended tests. During ECLA onset the APTT and ACT were within or near normal ranges, platelets decreased 76.5% within 48 h, fibrinogen decreased 28.7%, thrombin-antithrombin-III complexes were elevated before ECLA (53 micrograms/L), but demonstrated an additional peak (238 micrograms/L), plasminogen-activator-inhibitor-1 increased 12-fold, and the C1-inhibitor dropped 14.1%. In conclusion, after the onset of ECLA from a previous prethrombotic state, the precoagulant, anticoagulant, fibrinolytic and complement systems were activated in a similar way to that reported for non-heparinized systems with high-dose heparin. This was however only monitored by an extended test panel which was unable to predict thromboembolic events during ECLA.
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PMID:Global and extended coagulation monitoring during extracorporeal lung assist with heparin-coated systems in ARDS patients. 906 29

Activation of the contact and complement systems in C1-inhibitor deficiencies is thought to contribute to the pathogenesis of angioedema attacks by releasing kinins. Trigger stimuli of attacks may also activate coagulation. This is particularly important because experimental data suggest that thrombin, the main enzyme of the coagulation cascade, increases vascular permeability and can thus influence edema formation. We have studied 19 patients with hereditary angioedema (HAE) during remission, 5 HAE patients during acute attacks, and 6 patients with acquired angioedema (AAE) during remission and during seven attacks. Thirty normal subjects, matched for sex and age, served as controls. Generation of thrombin was measured by enzyme-linked immunosorbent assay (ELISA) as plasma levels of the prothrombin fragment 1 + 2 (F1 + 2); the initiators of the tissue factor and contact coagulation pathways were investigated by measuring plasma levels of activated factor VII (FVIIa) coagulometrically and activated factor XII (FXIIa) by ELISA. Cleavage of high molecular weight kininogen (HK) was evaluated by immunoblotting analysis. F1 + 2 was slightly increased during remission and further significantly increased during attacks in both HAE (P = .0115) and AAE. FVIIa and FXIIa, normal during remission, increased strikingly during attacks in both HAE (P = .0022 and P = .0044) and AAE. During remission, cleaved HK was normal in HAE and high in AAE; during attacks it increased in HAE (P = .0008) and remained elevated in AAE. Our data indicate that in C1-inhibitor deficient patients there is increased generation of thrombin during attacks, with signs of activation of both the contact and tissue factor coagulation pathways. In conclusion, C1-inhibitor deficiency, whether hereditary or acquired, has demonstrable activation of the coagulation and kinin-forming cascades during attacks and that thrombin should be considered a possible contributing factor in the pathogenesis of edema in HAE and AAE.
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PMID:Activation of the coagulation cascade in C1-inhibitor deficiencies. 912 25

Very-low-density lipoprotein receptor (VLDLR) and alpha2-macroglobulin receptor/low-density-lipoprotein-receptor-related protein (alpha2MR/LRP) are multifunctional endocytosis receptors of the low-density lipoprotein receptor family. Both have been shown to mediate endocytosis and degradation of complex between plasminogen activators and type-1 plasminogen-activator inhibitor (PAI-1) by cultured cells. We have now studied the specificity of binding and endocytosis by VLDLR and alpha2MR/LRP among a variety of serine proteinase/serpin complexes, including various combinations of the serine proteinases urokinase-type and tissue-type plasminogen activators, plasmin, thrombin, human leukocyte elastase, cathepsin G, and plasma kallikrein with the serpins PAI-1, horse leukocyte elastase inhibitor, protein C inhibitor, C1-inhibitor, alpha2-antiplasmin, alpha1-proteinase inhibitor, alpha1-antichymotrypsin, protease nexin-1, heparin cofactor II, and antithrombin III. Binding was estimated with radiolabelled ligands in ligand blotting analysis and microtiter well assays. Endocytosis was estimated by measuring receptor-associated protein (RAP)-sensitive degradation of radiolabelled complexes by Chinese hamster ovary cells transfected with VLDLR cDNA and by COS-1 cells, which have a high endogenous expression of alpha2MR/LRP. We found that the receptors bind with high affinity to some, but not all, combinations of plasminogen activators and thrombin with PAI-1, protease nexin-1, protein C inhibitor, and antithrombin III, while complexes of many serine proteinases with their primary inhibitor, i.e. plasmin/alpha2-antiplasmin complex, do not bind, or bind with a very low affinity. Both the serine proteinase and the serpin moieties contribute to the binding specificity. The binding specificities of VLDLR and alpha2MR/LRP are overlapping, but not identical. The results suggest that VLDLR and alpha2MR/LRP have different biological functions by having different binding specificities as well as by being expressed by different cell types.
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PMID:Specificity of serine proteinase/serpin complex binding to very-low-density lipoprotein receptor and alpha2-macroglobulin receptor/low-density-lipoprotein-receptor-related protein. 934 78

We have shown that the contact (kallikrein-kinin) system is involved in the pathogenesis of experimental enterocolitis. We now investigate activation of the contact and coagulation pathways, platelets, and neutrophils in active and inactive ulcerative colitis patients as compared to normal controls. In active ulcerative colitis patients, a significant decrease of plasma prekallikrein, high molecular weight kininogen, and C1 inhibitor levels was observed as compared with controls, as well as prekallikrein activation on western blots. Significant elevation of prothrombin fragment (F1 + 2), which indicates thrombin generation, and elastase-alpha 1-antitrypsin complexes, reflecting neutrophil activation, were found in patients with active disease. Plasma beta-thromboglobulin, a marker of platelet activation, was elevated in both active and inactive disease and appears to be a feature of ulcerative colitis. Activation of contact and coagulation pathways, as well as neutrophils, may mediate inflammation in the active phase of ulcerative colitis.
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PMID:Activation of plasma contact and coagulation systems and neutrophils in the active phase of ulcerative colitis. 939 17

Thrombolytic therapy in acute myocardial infarction (AMI) is hampered by a considerable reocclusion rate. Thrombin activity is enhanced, and contact-system activation via plasminemia might be possible. Prospectively we examined the contact phase and the kallikrein-kinin system and additional molecular markers of hemostasis and fibrinolysis in AMI. In 22 patients with AMI, blood sampling was performed at admission and < or =10 days afterward. Eleven patients received 1.5 Mio U streptokinase (group A) and were compared with 11 AMI patients without thrombolytic therapy (group B). All patients had systemic heparinization (5,000 IU bolus, i.v.; 1,000 IU/h, i.v.). In group A (vs. group B), the kallikrein-factor XII system was significantly activated (3 h after start of therapy): kallikrein activity 140 +/- 41 (vs. 43 +/- 8) U/L (p < 0.05); kallikrein inhibition 87 +/- 9 (vs. 113 +/- 7%; p < 0.05), and factor XII 70 +/- 14 (vs. 94 +/- 6%). C1 inhibitor and factor XII inhibition were decreased. High-molecular-weight kininogen consumption indicating bradykinin generation was enhanced (p < 0.01). In group A, thrombin activity (TAT) was increased, and a hypercoagulative state with increased fibrin degradation products (d-dimer) was found. Plasmin activation in group A was reflected by decreased plasminogen and antiplasmin levels (p < 0.01). The findings indicate that streptokinase induces activation of the contact phase-kinin system in vivo associated with a consecutive increase of thrombin and bradykinin generation. Activation of this pathway might substantially contribute to reocclusion after initially successful thrombolytic therapy and to hypotensive reactions observed after streptokinase.
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PMID:Streptokinase-induced activation of the kallikrein-kinin system and of the contact phase in patients with acute myocardial infarction. 959 77

Localized edema of the larynx and pharynx leading to death from asphyxia has long been recognized as a characteristic symptom of hereditary angioneurotic edema (HANE). Long-term follow-up of younger HANE patients has revealed that transient localized acute attacks of edema affect tissues where the microcirculation maintains the blood supply. However, with aging, HANE attacks precipitate disseminated intravascular coagulation (DIC) or multiple organ failure (MOF). Substitution with a C1-inhibitor (C1-INH) has resulted in a fulminant lethal end with a rapid and profound decrease in antithrombin-III (AT-III) activity. A possible mechanism is as follows: Exogenous stimuli activate plasma proteinase systems with the generation of plasma kallikrein that activates the tissue factor pathway (TF) and liberates bradykinin (BK). In younger patients, BK enhances vascular permeability. In the elderly, activated TF is controlled by tissue factor pathway inhibitor (TFPI) and generates thrombin, which is the target enzyme of AT-III and precipitates DIC or MOF. In elderly patients, the characteristic symptom of HANE is hypercoagulation by age-related changes in the biosynthesis of AT-III or TFPI.
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PMID:Hereditary angioneurotic edema and thromboembolic diseases: I: How symptoms of acute attacks change with aging. 965 97

Recombinant human gamma interferon was used to treat 10 atopic dermatitis patients. Recombinant gamma interferon was administered weekly for three consecutive days at 50 microg/M2 SQ for four weeks. All patients' dermatitis improved with recombinant gamma interferon therapy and plasma tumor necrosis factor-alpha levels rose with treatment. Recombinant gamma interferon treatment positively correlated with reduced total plasma fibrinolysis as measured by the fibrin lysis plate, plasmin-alpha2antiplasmin complexes, and tissue type plasminogen activator levels. Accordingly, plasminogen activator inhibitor levels increased. Treatment also was associated with a transient increase in thrombin-antithrombin III complexes. Recombinant gamma interferon resulted in a significant increase in C1 inhibitor antigen but not activity. Plasma prekallikrein, high molecular weight kininogen, and factor XII levels were not decreased. However, 5 of the 10 atopic dermatitis patients before therapy had circulating cleaved plasma high molecular weight kininogen detected on immunoblot, indicating prior kallikrein formation. The cleaved, circulating plasma high molecular weight kininogen disappeared in four out of the five original patients who were reexamined at one year after treatment. These combined data indicated that recombinant gamma interferon treatment reduced total plasma fibrinolysis. In untreated atopic dermatitis, circulating cleaved high molecular weight kininogen also may be a presenting manifestation.
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PMID:Gamma interferon administration to patients with atopic dermatitis inhibits fibrinolysis and elevates C1 inhibitor. 966 47

Cardiopulmonary bypass causes hemorrhagic complications, and initiates a chemical and cellular inflammatory response. Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, complement, and contact systems. Despite the fact that cardiopulmonary bypass is carried out in the presence of high doses of heparin, there is significant activation of both platelets and neutrophils. Thrombin is protected on cell and fibrin surfaces from antithrombin, even in the presence of high doses of heparin (approximately 5 U/ml). We therefore studied the effect of a small (Mr = 497), highly effective (Ki = 41 pM), reversible tripeptide inhibitor of thrombin, DUP 714 (1 microM), in a well characterized model of simulated extracorporeal circulation. In the absence of DUP 714, platelet counts decreased by 75% 5 min after the start of extracorporeal bypass and increased to 48% at 120 min of recirculation. DUP 714 significantly preserved platelet counts, decreased plasma levels of platelet beta-thromboglobulin levels, but did not prevent a decrease in sensitivity of platelets to adenosine diphosphate. Kallikrein-C1-inhibitor and C1-C1-inhibitor complexes increased progressively from 0.32 U/ml to 0.67 U/ml and from 4.45 U/ml to 7.25 U/ml, respectively, during 120 min of recirculation without DUP 714. Addition of DUP 714 significantly inhibited kallikrein-C1-inhibitor complex formation but did not affect C1-C1-inhibitor complexes. In the absence of DUP 714, human neutrophil elastase levels rose from a baseline of 0.01 +/- 0.00 microg/ml to 1.18 +/- 0.21 microg/ml during 120 min of recirculation. Human neutrophil elastase release at 120 min was significantly inhibited in the presence of DUP 714 to 37% of the value with heparin alone. These results indicated that addition of this novel thrombin (and kallikrein) inhibitor to heparin preserved platelet counts, decreased platelet secretion, and provided the additional benefit of partially blocking neutrophil activation during simulated extracorporeal circulation.
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PMID:Thrombin and human plasma kallikrein inhibition during simulated extracorporeal circulation block platelet and neutrophil activation. 979 91


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