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)

The multiple cholinesterase activities in canine platelets have been investigated. Platelets were homogenized by rapid decompression under nitrogen, glass tube/Teflon pestle, and glycerol lysis techniques. Rapid decompression under nitrogen technique was found to be the most efficient and gentle method for cell disruption. Homogenates were subfractionated using sodium diatrizoate density gradients. Marker enzyme assays and pulse labeling experiments with 5-hydroxyl[14C] tryptamine and [125I] thrombin on prepared subcellular fractions confirmed that the soluble, plasma membrane and the granule-1 fractions were all in reasonably pure form. Furthermore, labeling of the plasma membrane with [125I] thrombin is cited as the first successful attempt at attaining significantly bound marker for this structure. Cholinesterase activity distributions measured in these fractions indicated that about 30% of the activity was present in the plasma membrane, 50% in granule-1 and 5% in soluble fractions. Kinetic data of cholinesterase activities obtained from intact platelets, plasma membrane preparations and platelet release supernatants indicated that they are strikingly similar.
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PMID:The subcellular distribution and partial characterization of cholinesterase activities of canine platelets. 0 47

For comparative studies on the esterase activities of thrombin and trypsin N(alpha)-arylsulfonyl-L-arginine methyl esters were synthetised containing in aromatic ring substituents of different polar nature, size and hydrophobicity. The kinetics of their hydrolysis by thrombin and trypsin were measured. Values of Km and kcat in steady-state conditions were determined. It was shown, that thrombin-catalysed hydrolysis was more sensitive than that of trypsin to the nature of substituents of arylsulfonyl group and determined by their polar and steric effects. A line correlation between specificity constants (kcat/Km) and sigma and Es of substituents were demonstrated. The difference in reactivity of compounds under investigation is suggested to depend on alterations of stability of hydrogen bond between arylsulfonylamide nitrogen atom of substrate and the active center of the enzyme due to changes in the acidity of the arylsulfonylamide group affected by substituent of the benzene ring.
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PMID:[Dependence of thrombin- and trypsin-catalyzed hydrolysis of N-alpha-arylsulfonyl-L-arginine methyl esters on the structure of acylamide part of substrates]. 2 Sep 97

The effects of HES and HES + DMSO used as cryoprotective media for storage of human platelets in liquid nitrogen and vapor phase of liquid nitrogen were studied. Solution of 6% and 15% HES with molecular weight ranging from 65,000 to 250,000, and 10% DMSO were used. The criteria accepted for evaluation of the efficiency of these cryoprotective media were: 1. platelet counts, 2. participation of platelets in the processes of hemostasis measured in vitro by the ability of platelets to release adenine nucleotides (ATP + ADP) after thrombin stimulation. It was found that 15% HES is a more effective cryoprotective medium than 6% HES. The use of 15% HES + 10% DMSO gave similar results as the use of 10% DMSO alone.
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PMID:[Use of hydroxyethyl starch as a cryoprotective medium during platelet storage at low temperatures]. 5 81

The effects of three widely spaced levels of bacterial contamination of reagent water on several chemistry, radioimmunoassay, and coagulation procedures were studied. These included determinations of lactate dehydrogenase, creatine kinase, aspartate transaminase, alkaline phosphatase, blood urea nitrogen, total protein, thyroid-stimulating hormone, digoxin, thrombin time, activated partial thromboplastin time, and prothrombin time. Statistical analyses included calculations of means and coefficients of variation, and analysis of variance, as well as correlation coefficients for test results versus logarithm of bacterial contamination. Statistically and clinically significant differences occurred together only for an elevated level of creatine kinase.
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PMID:Effects of bacterial contamination of reagent water on selected laboratory tests. 43 36

A series of 62 diarylamidine derivatives was evaluated for their antiproteolytic activity. In all but two of the compounds one or both of the amidino-substituted aryl moieties was either an indole or an indole-like ring. The latter included indene, benzimidazole, benzofuran, benzol[beta]thiophene, and several other related nitrogen-containing heterocycles. Several of the compounds exhibited considerable inhibitory potency against thrombin, trypsin, and pancreatic kallikrein. An outstanding inhibitor of trypsin was found in bis(5-amidino-2-benzimidazolyl)methane (compound 42) with a Ki value of 1.7 X 10(-8) M(pH. 8.1, 37 degrees C). Another derivative, 1,2-di(4-amidino-2-benzofuranyl)ethane (compound 21), proved to be a highly effective inhibitor of the overall blood clotting process. From a general structure-activity standpoint these compounds demonstrate that minor structural variations of low-molecular-weight inhibitors can result in significant changes in specificity and potency with regard to antiproteolytic activity.
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PMID:Diarylamidine derivatives with one or both of the aryl moieties consisting of an indole or indole-like ring. Inhibitors of arginine-specific esteroproteases. 67 60

All the thrombolytic agents currently in clinical use act as plasminogen activators. In this study evidence is presented that also oxidants of the phagocyte type are of fibrinolytic efficiency in vivo. Activated phagocytes participate in physiologic fibrinolysis. The cells generate plasminogen activators and reactive oxidants of the nitrogen-chlorine type. Experimental mimicry of this oxidative inflammatory response induces selective thrombolysis in a rabbit jugular vein model. Intravenous bolus administration of sub-millimolar blood concentrations of chloramine-T resulted in thrombolysis after about 30 min without notable systemic toxicity; the coagulation parameters activated partial thromboplastin time (aPTT), thrombin time, fibrinogen, and alpha-2-antiplasmin were not influenced. Control experiments with 2000 IU of urokinase/kg induced thrombolysis after about 90 min with systemic changes of the hemostatic system. The fibrinolysis promoting effect of the oxidants of the phagocyte type could be inhibited by quenchers of singlet molecular oxygen and was not affected at all by inhibitors of oxygen radicals. The data gives evidence that nonradical excited oxygen species (NEOS) act as powerful pro-fibrinolytic and anti-coagulant agents in vivo. It might be suggested that NEOS could represent a novel class of regulators of the fibrinolytic system. The long lived and hydrophilic chloramine derivatives can either accumulate or diffuse far from their site of generation. Therefore, on the one hand oxidants in high (local) concentrations might be considered as direct pro-fibrinolytic agents due to their powerful protein modulating efficacy. On the other hand, oxidants at low concentrations may act as indirect pro-fibrinolytic compounds, i.e. as chemoattractants to concentrate phagocytes to the site of a thrombus. In this case the oxidants would play the role of signal elements faraway from the thrombus, a self amplifying mechanism possibly mediated by oxidation of blood arachidonat/lipid metabolites.
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PMID:Nonradical excited oxygen species induce selective thrombolysis in vivo. 171 80

A clinically lethal strain of Pseudomonas aeruginosa was tested and its growth patterns in normal plasma and in normal whole blood clotted with thrombin were compared. Two stock cultures were used; one was maintained in liquid nitrogen and one was passed from plate to plate 24 times on blood agar plates at room temperature. The results showed that plasma alone and whole blood controlled the growth of a clinically pathogenic strain of P. aeruginosa consistently and uniquely for each donor, dependent on size of inoculum, length of incubation, and means by which the culture was maintained. The changing virulence of an organism and its unique growth patterns in different individuals' plasma and whole blood may explain why patients exposed to the same organisms within the same environment vary in susceptibility to clinical infection.
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PMID:Bacterial virulence and host selection: bacteria "select" patients to infect. 190 77

The effects of soman poisoning on hematological (counts of red blood cells (RBC), white blood cells (WBC), and platelets and measurement of hematocrit) and coagulation parameters (prothrombin time, activated partial thromboplastin time, thrombin time and concentrations of fibrinogen, factor V, factor VII, and factor XI) and serum biochemistry (concentration of albumin, protein, calcium, cholesterol, triglycerides, blood urea nitrogen (BUN), magnesium, and creatinine and activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, cholinesterase, creatinine phosphokinase (CPK), hydroxybutyrate dehydrogenase, and amylase) were determined at 1, 2, 4, 24, and 48 hours after poisoning of rabbits. There were significant (p less than 0.05) decreases in the RBC counts in all treatment groups that were measured initially at 4 hours and were reflected by parallel decreases in the hematocrit values. These changes were probably due to an increase in the hemolysis of the RBC rather than a decrease in the production of RBC. There were minor changes in the coagulation parameters. Generally, the fibrinogen content increased. The activated partial thromboplastin time decreased significantly (p less than 0.05) 24 and 48 hours after soman (50 micrograms/kg) poisoning. Blood cholinesterase values were significantly reduced in all treatment groups at all time periods. The CPK activity was increased after 4 and 24 hours in the 20 and 50 micrograms/kg soman groups. There were minor changes in the other biochemistry values, but none that showed a dose-response relationship; thus, they were considered to be of limited significance with regard to the toxic manifestations of soman exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of soman poisoning on hematology and coagulation parameters and serum biochemistry in rabbits. 212 98

The crystallographic structure of a recombinant hirudin-thrombin complex has been solved at 2.3 angstrom (A) resolution. Hirudin consists of an NH2-terminal globular domain and a long (39 A) COOH-terminal extended domain. Residues Ile1 to Tyr3 of hirudin form a parallel beta-strand with Ser214 to Glu217 of thrombin with the nitrogen atom of Ile1 making a hydrogen bond with Ser195 O gamma atom of the catalytic site, but the specificity pocket of thrombin is not involved in the interaction. The COOH-terminal segment makes numerous electrostatic interactions with an anion-binding exosite of thrombin, whereas the last five residues are in a helical loop that forms many hydrophobic contacts. In all, 27 of the 65 residues of hirudin have contacts less than 4.0 A with thrombin (10 ion pairs and 23 hydrogen bonds). Such abundant interactions may account for the high affinity and specificity of hirudin.
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PMID:The structure of a complex of recombinant hirudin and human alpha-thrombin. 237 26

During a recent outbreak of Rhodesian sleeping sickness in the Lambwe Valley no asymptomatic Rhodesian sleeping sickness patients were found although 54% of the primary patients had mild symptoms and 9% were stuporous or comatose at presentation. The duration of symptoms was three months or less in 90% of the patients. Headache, weakness, joint and back pains and weight loss were claimed by at least 75% of the patients, while 82% of the females reported amenorrhoea and 70% of the males claimed impotency. Physical examination revealed lymphadenopathy in 86% but fever in only 36% of the patients, while chancres were found in only 16%. Patients had significantly lower levels of haemoglobin and thrombocytes than controls and their erythrocyte sedimentation rates were elevated. A comparison of both blood group and haemoglobin type between patients and controls yielded no significant differences. Fifty-seven per cent of the primary patients reporting mild symptoms had abnormal levels of leucocytes in their CSF. All relapse patients had abnormal CSF parameters. Levels of serum urea nitrogen were significantly elevated in patients, but SGOT, SGPT and total bilirubin were not. Levels of albumin and beta-globulin in patients were significantly lower than controls while gamma-globulin was elevated. Mean serum IgM levels in patients were elevated to nearly three-fold those of controls, but 35% of the individual patient values fell within the 95% range of control values. Some patients had extended prothrombin and thrombin times while fibrinogen levels were significantly elevated. No patients reported haemorrhage, and none was seen.
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PMID:Presenting features of Rhodesian sleeping sickness patients in the Lambwe Valley, Kenya. 261 98


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