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Blood Dec 1993The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well...
The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well established. The present study compared the efficacy of thrombin or ancrod, a venom-derived enzyme that clots fibrinogen, to induce fibrin formation in rabbits with elevated PAI-1 levels. One set of male New Zealand rabbits received intravenous endotoxin to increase endogenous PAI-1 activity followed by a 1-hour infusion of ancrod or thrombin; another set of normal rabbits received intravenous human recombinant PAI-1 (rPAI-1) during an infusion of ancrod or thrombin. Thirty minutes after the end of the infusion, renal fibrin deposition was assessed by histopathology. Animals receiving endotoxin, rPAI-1, ancrod, or thrombin alone did not develop renal thrombi. All endotoxin-treated rabbits developed fibrin deposition when infused with ancrod (n = 4) or thrombin (n = 6). Fibrin deposition occurred in 7 of 7 rabbits receiving both rPAI-1 and ancrod and in only 1 of 6 receiving rPAI-1 and thrombin (P < .01). In vitro, thrombin but not ancrod was inactivated by normal rabbit plasma and by purified antithrombin III or thrombomodulin. The data indicate that elevated levels of PAI-1 promote fibrin deposition in rabbits infused with ancrod but not with thrombin. In endotoxin-treated rabbits, fibrin deposition that occurs with thrombin infusion may be caused by decreased inhibition of procoagulant activity and not increased PAI-1 activity.
Topics: Ancrod; Animals; Endotoxins; Fibrin; Humans; Infusions, Intravenous; Kinetics; Male; Plasminogen Activator Inhibitor 1; Rabbits; Recombinant Proteins; Thrombin; Time Factors; Tissue Plasminogen Activator
PubMed: 8260701
DOI: No ID Found -
Kidney International Nov 1976Defibrination with ancrod in nephrotoxic nephritis in rabbits. In rabbits with nephrotoxic nephritis, defibrination with ancrod provided protection when administered...
Defibrination with ancrod in nephrotoxic nephritis in rabbits. In rabbits with nephrotoxic nephritis, defibrination with ancrod provided protection when administered during the autologous phase, after extensive glomerular fibrin deposition had occurred and crescents and renal failure were developing. When further glomerular fibrin deposition was prevented by defibrination, deposited fibrin was rapidly removed, indicating that glomerular fibrin-clearing mechanisms are retained in crescentic nephritis. Defibrination had no effect on the extent of glomerular C3 deposition or on the amount of proteinuria.
Topics: Ancrod; Animals; Basement Membrane; Complement C3; Creatinine; Disease Models, Animal; Endopeptidases; Fibrin; Fibrinolysis; Fluorescent Antibody Technique; Immune Sera; Immunoglobulin G; Kidney Glomerulus; Male; Nephritis; Rabbits
PubMed: 794557
DOI: 10.1038/ki.1976.120 -
The Journal of Clinical Investigation Aug 1979A quantitative primate model of arterial thromboembolism has been characterized with respect to mechanism and usefulness in evaluating modifying variables. The model...
A quantitative primate model of arterial thromboembolism has been characterized with respect to mechanism and usefulness in evaluating modifying variables. The model involved the kinetic measurements of (51)Cr-platelets and (125)I-fibrinogen consumption by femoral arteriovenous cannulae in chaired baboons. Cannula platelet consumption correlated directly with exposed cannular area for irradiated Silastic and polyurethane (correlation coefficients of 0.940 and 0.901, respectively; P < 0.001) and remained steady state for months. Nonirradiated Silastic was only minimally reactive with platelets. Despite increased rates of platelet consumption circulating fibrinogen was not measurably destroyed by any of the cannulae tested. Cannula platelet consumption was independent of cannula flow rate, platelet count, heparin anti-coagulation, and ancrod defibrinogenation.(111)In-platelet imaging of irradiated Silastic cannulae demonstrated luminal accumulation and subsequent embolization of irregular platelet masses. When irradiated Silastic cannulae were inserted as extension segments in the renal arteries of four animals the glomerular vessels became progressively occluded with nonfibrin-containing platelet thromboemboli. Nonirradiated Silastic cannulae in control arteries produced no significant vascular occlusion. Because the survival of platelets from animals with consumptive cannulae was not shortened in normal recipient animals we concluded that platelets were either irreversibly removed through thromboembolic consumption or unaffected in their viability. Oral administration of dipyridamole and sulfinpyrazone decreased cannula platelet consumption in a dose-dependent manner with complete interruption at 20 and 250 mumol/kg body wt per d (in three divided doses), respectively, whereas oral acetylsalicylic acid (10-330 mumol/kg per d) had no measurable effect on cannula platelet consumption. We conclude that this primate model simulates arterial thrombotic processes in man and that this model is suitable for the in vivo evaluation of biomaterials and of drugs that modify platelet behavior.
Topics: Animals; Arteriovenous Shunt, Surgical; Aspirin; Blood Platelets; Blood Transfusion; Dipyridamole; Disease Models, Animal; Femoral Artery; Femoral Vein; Fibrinogen; Haplorhini; Heparin; Kidney; Male; Papio; Platelet Adhesiveness; Polyurethanes; Regional Blood Flow; Silicone Elastomers; Sulfinpyrazone; Thromboembolism
PubMed: 110835
DOI: 10.1172/JCI109494 -
British Journal of Experimental... Aug 1986The effect of fibrinolysis with Streptokinase and defibrination with Ancrod on the progression of established fibrin-related glomerular injury was assessed in rabbits... (Comparative Study)
Comparative Study
The effect of fibrinolysis with Streptokinase and defibrination with Ancrod on the progression of established fibrin-related glomerular injury was assessed in rabbits developing anti-glomerular basement membrane antibody-induced glomerulonephritis. Untreated rabbits developed renal failure and a severe crescentic nephritis with prominent fibrin deposition after 5 days. Rabbits with established injury and glomerular fibrin deposition were treated with Streptokinase or Ancrod over the last 4 days of this model. Both treatments resulted in significant protection from loss of renal function and reduced crescent formation by day 5. Glomerular fibrin deposition was also significantly reduced by both agents, although Streptokinase produced a greater reduction than Ancrod. Two further groups of rabbits with advanced disease, were treated over the last two days of this model. Although treatment reduced glomerular fibrin deposition, no protection from loss of renal function was observed. These studies indicate that both treatments were effective, if used early, in preserving renal function in established fibrin related glomerulonephritis, but they did not effect the outcome of more advanced disease. Both agents prevented further glomerular fibrin deposition, although only early treatment with Streptokinase reduced glomerular fibrin to below pre-treatment levels.
Topics: Ancrod; Animals; Complement C3; Creatinine; Fibrin; Fibrinogen; Glomerulonephritis; Immunoglobulin G; Kidney Glomerulus; Rabbits; Streptokinase
PubMed: 3741774
DOI: No ID Found -
The Journal of Biological Chemistry Apr 1978The potential cross-link acceptor sites of fibrin were specifically labeled with the fluorescent, substitute cross-link donor monodansyl cadaverine (MDC). Several...
The potential cross-link acceptor sites of fibrin were specifically labeled with the fluorescent, substitute cross-link donor monodansyl cadaverine (MDC). Several fluorescent alpha-chain peptides generated from enzymatic and cyanogen bromide (CNBr) cleavage of the labeled fibrin were identified by sodium dodecyl sulfate disc gel electrophoresis; they were isolated and then characterized by amino acid analysis, NH2-terminal sequence analysis, and chromatographic and electrophoretic analyses of their digestion products. Ancrod cleavage of MDC-labeled fibrin produced a series of six alpha-chain peptides of molecular weights 34,000 to 12,000, each of which contained an MDC-labeled acceptor site, and an NH2-terminal alpha-chain derivative of molecular weight 37,500. The latter remains disulfide bound in the residual fibrin and has two MDC-labeled sit-s which are separable by CNBr cleavage. Mild plasmin digestion of MDC-labeled fibrin generated fluorescent alpha-chain peptides of molecular weights 45,000, 42,000, 35,000, 23,000, 21,000, and 2,500 in the supernatant and a nonfluorescent NH2-terminal alpha-chain derivative of molecular weight 25,000 which remained in the insoluble residual fibrin. The alignment of these plasmic supernatant peptides was determined from NH2-terminal sequence analyses which indicated that an MDC acceptor site was located at approximately residue 255 of the Aalpha-chain. Cleavage of the MDC-labeled alpha-chain by CNBr, however, localized most of its fluorescence (approximately 80%) to a fragment of molecular weight 29,000 which had the same NH2-terminal sequence as the labeled plasmic peptide of molecular weight 21,000. Both peptides were cleaved by ancrod into two acceptor site-containing peptides of approximately equal fluorescence. The preliminary NH2-terminal sequence analyses of these peptides, when combined with the above findings, indicated that these two other cross-link acceptor sites are in a peptide segment which comprises the middle 17% of the Aalpha-chain.
Topics: Amino Acids; Binding Sites; Cadaverine; Dansyl Compounds; Fibrin; Fibrinogen; Humans; Macromolecular Substances; Molecular Weight; Protein Binding
PubMed: 632262
DOI: No ID Found -
Laboratory Investigation; a Journal of... Nov 2004A novel model to induce occlusive thrombus formation was developed in mice in vivo. Mice were simultaneously treated with ligation and cuff placement at the left carotid...
A novel model to induce occlusive thrombus formation was developed in mice in vivo. Mice were simultaneously treated with ligation and cuff placement at the left carotid artery. At 7 days after the treatment, occlusive thrombus was observed at the intracuff region, but not in the distal and proximal regions of the cuff, and not induced by a single treatment of ligation or cuff placement. The plasma levels of von Willebrand factor (vWF), which represent the endothelial status, were significantly increased in combined treatment of ligation and cuff placement 1 day after the operation. Whereas no significant changes in plasma vWF were observed in either single treatment of ligation or cuff placement. The expression of vWF, considered to be the endothelial marker, was detected on the luminal surface distal and proximal to the cuff and the carotid artery in the single treatment groups treated with either ligation or cuff placement, but was not detected in the intracuff region. Furthermore, the binding of Griffolia Simplicifolia Lectin-I (GSL-I) and endothelial nitric oxide synthase (eNOS) expression indicating the endothelial integrity was not detected in the intracuff region. Intermittent injections of ancrod, which decreases the plasma fibrinogen, inhibited occlusive thrombus formation in the intracuff region. The expression of eNOS was detected at the distal and proximal but not the intracuff region of the carotid artery treated with ancrod. Daily administration of aspirin significantly suppressed the thrombus formation in this model. These results indicate that occlusive thrombus formation accompanied by endothelial damage or dysfunction is induced by the combined application of ligation and cuff placement at the carotid artery, and suggest that this endothelial damage or dysfunction may be one pathogenesis of thrombogenesis in this model.
Topics: Animals; Arterial Occlusive Diseases; Aspirin; Carotid Artery Diseases; Carotid Artery, Common; Disease Models, Animal; Endothelium, Vascular; Fibrinolytic Agents; Ligation; Male; Mice; Mice, Inbred C57BL; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Thrombosis; von Willebrand Factor
PubMed: 15334091
DOI: 10.1038/labinvest.3700171 -
Proceedings of the National Academy of... Apr 2004In multiple sclerosis, in which brain tissue becomes permeable to blood proteins, extravascular fibrin deposition correlates with sites of inflammatory demyelination and...
In multiple sclerosis, in which brain tissue becomes permeable to blood proteins, extravascular fibrin deposition correlates with sites of inflammatory demyelination and axonal damage. To examine the role of fibrin in neuroinflammatory demyelination, we depleted fibrin in two tumor necrosis factor transgenic mouse models of multiple sclerosis, transgenic lines TgK21 and Tg6074. In a genetic analysis, we crossed TgK21 mice into a fibrin-deficient background. TgK21fib(-/-) mice had decreased inflammation and expression of major histocompatibility complex class I antigens, reduced demyelination, and a lengthened lifespan compared with TgK21 mice. In a pharmacologic analysis, fibrin depletion, by using the snake venom ancrod, in Tg6074 mice also delayed the onset of inflammatory demyelination. Overall, these results indicate that fibrin regulates the inflammatory response in neuroinflammatory diseases. Design of therapeutic strategies based on fibrin depletion could potentially benefit the clinical course of demyelinating diseases such as multiple sclerosis.
Topics: Animals; Cell Line; Demyelinating Diseases; Fibrin; Inflammation; Macrophage Activation; Mice; Mice, Transgenic; Multiple Sclerosis; Plasminogen Activators; Tumor Necrosis Factor-alpha; Up-Regulation
PubMed: 15096619
DOI: 10.1073/pnas.0303859101 -
British Journal of Cancer Oct 1991Flavone acetic acid (FAA) is a novel antitumour agent that has a profound effect on the vasculature in murine tumour models. Previously we have shown that FAA induces a...
Flavone acetic acid (FAA) is a novel antitumour agent that has a profound effect on the vasculature in murine tumour models. Previously we have shown that FAA induces a coagulopathy and thrombocytopaenia in tumour-bearing mice, and the purpose of the present study was to determine the significance of the FAA-induced intravascular coagulation in the antitumour action of FAA. Several anticoagulant agents were tested for their effectiveness in altering ex vivo coagulation of murine plasma; heparin and ancrod were found to be most effective. These agents were administered to tumour-bearing mice prior to FAA and TNF treatment with little effect on the induced regrowth delay. However: the FAA-induced consumption of platelets in tumour-bearing mice was not blocked by anticoagulant treatment. These data suggest that platelet consumption occurs independently of the normal coagulation pathway, and further that fibrin deposition may not be a major factor in the antitumour action of FAA.
Topics: Adenocarcinoma; Animals; Anticoagulants; Antineoplastic Agents; Blood Coagulation; Flavonoids; Male; Mice; Mice, Inbred CBA; Platelet Count; Prothrombin Time
PubMed: 1911218
DOI: 10.1038/bjc.1991.382 -
Blood Sep 1982Plasma fibronectin (FN) binds fibrin in vitro by both noncovalent and covalent bonds and is decreased in DIC. In rabbits, conventionally purified 125I-FN had a complex...
Plasma fibronectin (FN) binds fibrin in vitro by both noncovalent and covalent bonds and is decreased in DIC. In rabbits, conventionally purified 125I-FN had a complex blood clearance with a late t1/2 of 71 hr. A large portion was apparently altered, as evinced by rapid clearance and an intravascular/total body ratio (C1) of 0.28-0.51. 3H-labeled FN, made in vivo by injection of 3H amino acids, had a t1/2 of 73 hr. Crosstransfusion of 131I-FN and 3H-FN into a second set of animals gave similar t1/2s and C1s of 0.74-0.82, indicating the altered 125I-FN was biologically screened in the first animals. Other animals were given 125I-fibrinogen and "screened" 131I-FN. Intravenous thrombin (50-60 U/kg/1 hr) caused a 25%-50% decrease in both 125I-fibrinogen and 131I-FN. Ancrod injection reduced fibrinogen by greater than 90% but had no effect on 131I-FN. 131I-FN levels did not change when thrombin was given after ancrod. No cross-linked FN-fibrinogen alpha-chain was found in the plasma, nor was the thrombin-induced fall in FN affected by spermidine blockade. These experiments demonstrate that FN and fibrin bind in vivo during defibrination and are rapidly cleared from the blood. The abnormal fibrin resulting from ancrod either does not bind FN in vivo or does so reversibly.
Topics: Ancrod; Animals; Cross-Linking Reagents; Disseminated Intravascular Coagulation; Fibrinogen; Fibronectins; Half-Life; Iodine Radioisotopes; Male; Molecular Weight; Rabbits; Spermidine; Thrombin
PubMed: 7104486
DOI: No ID Found -
Thorax Mar 1971Intravenous administration of ancrod produces hypofibrinogenaemia, which may be prolonged by further doses. Hypofibrinogenaemia, maintained for a week, was used to...
Intravenous administration of ancrod produces hypofibrinogenaemia, which may be prolonged by further doses. Hypofibrinogenaemia, maintained for a week, was used to prevent thrombosis on prosthetic heart valves in the calf. Thirteen calves were used in the study. Three of these were used to determine dose schedules and to test antibody formation. The calf was found to have hyperactive fibrinogenesis, and doses higher than previously reported were required to maintain prolonged hypofibrinogenaemia. Antibodies were detected in the calves treated for prolonged periods and the phenomenon was probably related to the massive dosage required. In 10 calves, the tricuspid valve was replaced with a polypropylene valve, using cardiopulmonary bypass. Two of these calves, used as controls and not treated with ancrod, showed massive thrombus formation on the valves. The remaining eight calves were treated with ancrod on different dose schedules. In four calves consistent low fibrinogen levels were not achieved. In the other four, treated by a continuous infusion of ancrod, 8-10 units/kg of body weight per day supplemented further by twice daily intravenous injections of 8ยท0 units/kg, it was possible to maintain sufficiently low fibrinogen levels and to prevent thrombus formation on the valves. In man, hypofibrinogenaemia is more easily maintained and antibody formation is less likely with the small dosage needed.
Topics: Animals; Antibody Formation; Anticoagulants; Cattle; Fibrinogen; Heart Valve Prosthesis; Injections, Intravenous; Postoperative Complications; Thrombosis; Venoms
PubMed: 5576533
DOI: 10.1136/thx.26.2.167