Expression of cDNA for batroxobin, a thrombin-like snake venom enzyme.
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The cloned cDNA for batroxobin has been expressed in E. coli. Batroxobin could only be obtained as intracellular aggregates of fusion proteins, fused with a small peptide. To obtain the mature batroxobin, the recognition sequence for thrombin was inserted between the peptide and the mature batroxobin. This fusion protein accumulated in an insoluble form and could easily be purified. After site-specific cleavage of the fusion protein with thrombin, recombinant batroxobin was isolated by preparative electrophoresis. Batroxobin with enzymatic activity was obtained by the refolding of recombinant batroxobin. (+info)
Fibrinogen variant BbetaD432A has normal polymerization but does not bind knob "B".
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Engineering fibrin matrices: the engagement of polymerization pockets through fibrin knob technology for the delivery and retention of therapeutic proteins.
(19/50)
A new congenital abnormal fibrinogen Ise characterized by the replacement of B beta glycine-15 by cysteine.
(20/50)
A new case of heterozygous dysfibrinogenemia characterized by the replacement of NH2-terminal amino acid of fibrin beta-chain was found in a 50-year-old man. Despite a prolonged thrombin time, the propositus' fibrinogen had a normal reptilase time with the normal release of fibrinopeptide A. Release of fibrinopeptide B by thrombin was strongly affected, but a very high concentration of thrombin almost completely released fibrinopeptide B with a normal elution pattern on reversed-phase high performance liquid chromatography (HPLC). Lysylendopeptidase-cleavage of purified B beta-chains analyzed on HPLC showed the decrease of one peptide compared with the normal and the appearance of an abnormal peptide peak. These peptides were treated with thrombin and further separated on HPLC. Amino acid sequence analysis of the abnormal peptide demonstrated that B beta glycine-15, NH2-terminus of the fibrin beta-chain, was replaced by cysteine. These findings will be of particular importance because they strongly support the hypothesis that the NH2-terminal portion of the fibrin beta-chain is involved in the polymerization reaction by thrombin. The propositus' daughter and two sisters had the same abnormal fibrinogen. This unique inherited abnormal fibrinogen was designated as fibrinogen Ise. During these studies, we found that a very high concentration of thrombin cleaves not only the A alpha Arg19-Val20 bond but also the COOH-terminal region of alpha-chains, which results in the generation of further degraded alpha-chains with apparent molecular weights of 44,000 or less. (+info)
A multicenter, phase III trial of hemocoagulase Agkistrodon: hemostasis, coagulation, and safety in patients undergoing abdominal surgery.
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BACKGROUND: Hemocoagulase Agkistrodon for injection is a single component thrombin which has passed phases I and II clinical trials. The purpose of this phase III clinical trial was to evaluate the effect of Hemocoagulase Agkistrodon on hemostasis and coagulation in abdominal skin and subcutaneous incisions and to assess the safety of this agent in surgical patients. METHODS: This is a phase III, prospective, randomized, double-blind, and controlled multicenter clinical trial including 432 consecutive patients randomized into either a study group (injected with hemocoagulase Agkistrodon at 2 U, n = 324) or a control group (injected with hemocoagulase Atrox, n = 108). The hemostatic time, hemorrhagic volume, hemorrhagic volume per unit area, blood coagulation, and adverse events were measured and compared between the two groups. RESULTS: The mean hemostatic time in the study group was (36.8 +/- 18.7) seconds; the hemorrhagic volume was (3.77 +/- 3.93) g; and the hemorrhagic volume per unit area was (0.091 +/- 0.125) g/cm(2). In the control group, the corresponding values were (38.1 +/- 19.7) seconds, (4.00 +/- 4.75) g, and (0.095 +/- 0.101) g/cm(2), respectively. No significant difference in values existed between the two groups (P > 0.05). Blood coagulation results and hepatic and renal function were also similar between the two groups. Adverse events were reported in two cases, but were deemed non-drug-related. CONCLUSIONS: Hemocoagulase Agkistrodon has good hemostatic and coagulative function and is safe for the use of arresting capillary hemorrhage that occurs while incising the abdomen during surgery. (+info)
Percutaneous injection of hemostatic agents for active liver hemorrhage.
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BACKGROUND: Active hemorrhage arising from hepatic injury can be life-threatening and require immediate attention. At present, nonoperative management of abdominal solid organ injuries has become the usual method of care. The purpose of this study was to determine whether hemocoagulase injection alone guided by contrast-enhanced ultrasonography (CEUS) could control active bleeding in rabbit liver. METHODS: The livers of 30 rabbits were punctured with an 18-gauge semiautomatic biopsy needle to create an active bleeding liver model, which was confirmed with CEUS. The animals were randomly divided into two groups: a treatment group (n=15) and a control group (n=15). In the treatment group, hemocoagulase was injected into the bleeding site under CEUS guidance. In the control group, the active bleeding site was treated with normal saline. When these treatment procedures had been performed, lactated Ringer's solution was given to both groups to maintain the mean arterial pressure at 70 mmHg for 1 hour. The intraperitoneal blood loss, hematocrit, mean heart rate, and macroscopic and microscopic examinations were analyzed at the end of the study. RESULTS: CEUS showed hypoechoic and anechoic perfusion defects in active bleeding liver models. Macroscopic and microscopic examinations also supported the results. After the hemocoagulase injection, the former bleeding site appeared on CEUS as an area devoid of contrast. The blood loss was lower in the treatment group than in the control group (38.0+/-16.6 ml versus 107.9+/-20.8 ml; t=10.172, P<0.05). The mean hematocrit value and the heart rate were higher in the treatment group than in the control group (hematocrit: 23.9+/-3.8% versus 18.8+/-4.1%; t=3.541, P<0.05; heart rate: 250+/-18 versus 223+/-15; t=4.551, P<0.01). CONCLUSION: Hemocoagulase injection alone under the guidance of CEUS is a simple and quick method to control blood loss in active liver bleeding. (+info)
The polymerization and thrombin-binding properties of des-(B beta 1-42)-fibrin.
(23/50)
Multiple factors affect the thrombin-catalyzed conversion of fibrinogen to fibrin, including: fibrinopeptide (FPA and FPB) release leading to exposure of two types of polymerization domains ("A" and "B," respectively) in the central portion of the molecule, and exposure of a noncatalytic "secondary" thrombin-binding site in fibrin. Fibrinogen containing the FPA sequence but lacking the B beta 1-42 sequence ("des-(B beta 1-42)-fibrinogen"), was compared to native fibrinogen (containing both FPA and FPB) to investigate the role played by B beta 1-42 in the polymerization of alpha-fibrin (i.e. fibrin lacking FPA), to compare reptilase and thrombin cleavage of FPA from fibrinogen, and to explore the location and function of the secondary thrombin-binding site. Electron microscopy of evolving polymer structures (mu, 0.14; pH 7.4) plus turbidity measurements, showed that early thin fibril formation as well as subsequent lateral fibril associations were impaired in des-(B beta 1-42)-alpha-fibrin, thus indicating that the B beta 1-42 sequence contributes to the A polymerization site. Reptilase-activated des-(B beta 1-42)-alpha-fibrin polymerized even more slowly than thrombin-activated des-(B beta 1-42)-alpha-fibrin, differences that disappeared when repolymerization of preformed fibrin monomers was carried out. Since existing data indicate that thrombin releases FPA in a concerted manner, resulting in relatively rapid evolution of fully functional divalent alpha-fibrin monomers, it can be inferred that delayed fibrin assembly of reptilase fibrin is due to slower formation of divalent alpha-fibrin monomers. Thrombin-activated des-(B beta 1-42)-alpha-fibrin polymerized more rapidly at low ionic strength (mu, 0.04) than did native alpha,beta-fibrin, a reversal of their behavior at physiological ionic strength (mu, 0.14). Concomitant measurement of FPA release revealed modest slowing of release at low ionic strength from des-(B beta 1-42)-fibrinogen (t1/2, 36.5 versus 21.5 min) and marked slowing from native fibrinogen (t1/2, 138 versus 22.2 min). This behavior correlated with increased thrombin binding to native alpha,beta-fibrin at low ionic strength, coupled with weak thrombin binding to des-(B beta 1-42)-alpha-fibrin, and indicates that secondary thrombin binding plays an important role in regulating thrombin diffusion and catalytic activity. Des-(B beta 1-42)-fibrinogen lacks or has a markedly defective secondary thrombin-binding site, from which we conclude that the B beta 15-42 sequence in fibrin plays a major role in forming or providing this site. (+info)
Comparison of the effect of calcium gluconate and batroxobin on the release of transforming growth factor beta 1 in canine platelet concentrates.
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