The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Wolf-dieter Schleuning - One of the best experts on this subject based on the ideXlab platform.
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Vampire Bat plasminogen activator dspa alpha 1 desmoteplase a thrombolytic drug optimized by natural selection
Pathophysiology of Haemostasis and Thrombosis, 2001Co-Authors: Wolf-dieter SchleuningAbstract:Plasminogen activators are enzymes found in all vertebrate species investigated so far. Their physiological function is the generation of localized proteolysis in the context of tissue remodeling, wound healing and neuronal plasticity. The common Vampire Bat (Desmodus rotundus) is a New World species that feeds exclusively on blood. Its saliva contains highly potent plasminogen activators, specialized in rapid lysis of fresh blood clots. Biochemical and pharmacological evidence indicates that these plasminogen activators represent a new class of thrombolytics with pharmacological and toxicological properties superior to human tissue-type plasminogen activator, the clot dissolving agent now most frequently used in medicine. A form of the enzyme produced by recombinant DNA technology is currently employed to test this hypothesis in clinical studies.
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fibrin selectivity of the isolated protease domains of tissue type and Vampire Bat salivary gland plasminogen activators
FEBS Journal, 1998Co-Authors: Luisella Toschi, Peter Donner, Peter Bringmann, Thomas Petri, Wolf-dieter SchleuningAbstract:The activity of Vampire Bat (Desmodus rotundus) salivary plasminogen activator (D. rotundus PA alpha1) and to a much lesser extent of tissue-type plasminogen activator (t-PA) is stimulated by the presence of fibrin. This cofactor requirement has in the past intuitively been attributed to fibrin binding. We have previously shown that elements of the non-protease domain of D. rotundus PA alpha1 could contribute to fibrin stimulation irrespective of fibrin binding. We now demonstrate that the protease domain of D. rotundus PA alpha1 by itself exhibits fibrin selectivity, i.e. it is 32-fold stimulated by fibrin but only 1.5-fold by fibrinogen. To a lesser extent this fibrin selectivity is also shared by the protease domain of t-PA. Our findings indicate that protein-protein interactions apart from fibrin binding affect the stimulatory mechanism of fibrin on D. rotundus PA alpha1 and t-PA.
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structural features mediating fibrin selectivity of Vampire Bat plasminogen activators
Journal of Biological Chemistry, 1995Co-Authors: Peter Bringmann, Wolf-dieter Schleuning, Daniel Gruber, Alexandra Liese, Luisella Toschi, Jorn Kratzschmar, Peter DonnerAbstract:The distinguishing characteristic of Vampire Bat (Desmodus rotundus) salivary plasminogen activators (DSPAs) is their strict requirement for fibrin as a cofactor. DSPAs consist of structural modules known from urokinase (u-PA) and tissue-type plasminogen activator (t-PA) such as finger (F), epidermal growth factor (E), kringle (K), and protease (P), combining to four genetically and biochemically distinct isoenzymes, exhibiting the formulas FEKP (DSPAα1 and α2) and EKP and KP (DSPAβ and DSPAγ). Only DSPAα1 and α2 bind to fibrin. All DSPAs are single-chain molecules, displaying substantial amidolytic activity. In a plasminogen activation assay, all four DSPAs are almost inactive in the absence of fibrin but strongly stimulated by fibrin addition. The catalytic efficiency (kcat/Km) of DSPAα1 increases 105-fold, whereas the corresponding value of t-PA is only 550. The ratio of the bimolecular rate constants of plasminogen activation in the presence of fibrin versus fibrinogen (fibrin selectivity) of DSPAα1, α2, β, γ, and t-PA was found to be 13,000, 6500, 250, 90, and 72, respectively. Whereas all DSPAs are therefore more fibrin dependent and fibrin selective than t-PA, the extent depends on the respective presence of the various domains. The introduction of a plasmin-sensitive cleavage site in a position akin to the one in t-PA partially obliterates fibrin cofactor requirement. Fibrin dependence and fibrin selectivity of DSPAs are accordingly mediated by fibrin binding, which involves the F domain, as yet undefined determinants within the K and P domains, and by the absence of a plasmin-sensitive activation site. These findings transcend the current understanding of fibrin-mediated stimulation of plasminogen activation: in addition to fibrin binding, specific protein-protein interactions come into play, which stabilize the enzyme in its active conformation.
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thrombolytic properties of desmodus rotundus Vampire Bat salivary plasminogen activator in experimental pulmonary embolism in rats
Blood, 1992Co-Authors: Werner Witt, Peter Bringmann, Peter Donner, Berthold Baldus, Linda Cashion, Wolf-dieter SchleuningAbstract:rDSPA alpha 1 (recombinant Desmodus salivary plasminogen activator alpha 1) is a recombinant protein corresponding to a natural plasminogen activator from the Vampire Bat Desmodus rotundus. The thrombolytic properties of rDSPA alpha 1 and tissue-type plasminogen activator (t-PA) were compared in a rat model of pulmonary embolism. Whole blood clots, produced in vitro and labeled with 125I-fibrinogen, were embolized into the lungs of anesthetized rats. Thrombolysis was calculated from the difference between initial clot radioactivity and that remaining in the lungs at 60 minutes. Blood was sampled for gamma counting, measurement of hemostatic factors, and plasminogen activator antigen levels. Thrombolysis at 3, 10, 30, and 100 nmol/kg intravenously (10% bolus, 90% over 60 minutes) amounted to 30% +/- 2%, 51% +/- 4%, 85% +/- 4%, 98% +/- 0% for rDSPA alpha 1 and 30% +/- 3%, 41% +/- 3%, 57% +/- 6%, 93% +/- 2% for t-PA (controls: 29% +/- 2%; mean +/- SEM, n greater than or equal to 6). t-PA at 100 nmol/kg significantly decreased fibrinogen, plasminogen, and alpha 2-antiplasmin levels by 33% +/- 7%, 38% +/- 8%, and 61% +/- 9%, whereas rDSPA alpha 1 at 100 nmol/kg only lowered alpha 2-antiplasmin significantly (by 29% +/- 6%). Compared with t-PA, rDSPA alpha 1 is the more potent and more clot selective (fibrin specific) thrombolytic agent. These results suggest that rDSPA alpha 1 may be safer and more efficacious than currently used thrombolytics.
Peter Donner - One of the best experts on this subject based on the ideXlab platform.
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fibrin selectivity of the isolated protease domains of tissue type and Vampire Bat salivary gland plasminogen activators
FEBS Journal, 1998Co-Authors: Luisella Toschi, Peter Donner, Peter Bringmann, Thomas Petri, Wolf-dieter SchleuningAbstract:The activity of Vampire Bat (Desmodus rotundus) salivary plasminogen activator (D. rotundus PA alpha1) and to a much lesser extent of tissue-type plasminogen activator (t-PA) is stimulated by the presence of fibrin. This cofactor requirement has in the past intuitively been attributed to fibrin binding. We have previously shown that elements of the non-protease domain of D. rotundus PA alpha1 could contribute to fibrin stimulation irrespective of fibrin binding. We now demonstrate that the protease domain of D. rotundus PA alpha1 by itself exhibits fibrin selectivity, i.e. it is 32-fold stimulated by fibrin but only 1.5-fold by fibrinogen. To a lesser extent this fibrin selectivity is also shared by the protease domain of t-PA. Our findings indicate that protein-protein interactions apart from fibrin binding affect the stimulatory mechanism of fibrin on D. rotundus PA alpha1 and t-PA.
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Catalytic domain structure of Vampire Bat plasminogen activator: a molecular paradigm for proteolysis without activation cleavage.
Biochemistry, 1997Co-Authors: Martin Renatus, Peter Bringmann, Peter Donner, Milton T. Stubbs, Robert Huber, Wolfram BodeAbstract:The saliva of the blood-eating Vampire Bat Desmodus rotundus contains plasminogen activators (PAs) that maintain the fluidity of the prey's blood by activating plasminogen and dissolving developing fibrin clots. D. rotundus salivary PAs (DSPAs) are composed of evolutionarily conserved domains reminiscent of human tissue-type PA (tPA), but their catalytic domain lacks a plasmin-sensitive “activation cleavage site”. Despite this, all DSPAs are intrinsically active and enormously stimulated in the presence of fibrin. The recombinant catalytic domain of DSPAα1 has been crystallized in a covalent complex with Glu-Gly-Arg-chloromethyl ketone and its structure solved at 2.9 A resolution. The structure is similar to that of activated two-chain human tPA. Despite its single-chain status, the activation domain is observed in an enzymatically active conformation, with a functional substrate binding site and active site accommodating the peptidylmethylene inhibitor. The activation pocket, which normally receives the ...
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structural features mediating fibrin selectivity of Vampire Bat plasminogen activators
Journal of Biological Chemistry, 1995Co-Authors: Peter Bringmann, Wolf-dieter Schleuning, Daniel Gruber, Alexandra Liese, Luisella Toschi, Jorn Kratzschmar, Peter DonnerAbstract:The distinguishing characteristic of Vampire Bat (Desmodus rotundus) salivary plasminogen activators (DSPAs) is their strict requirement for fibrin as a cofactor. DSPAs consist of structural modules known from urokinase (u-PA) and tissue-type plasminogen activator (t-PA) such as finger (F), epidermal growth factor (E), kringle (K), and protease (P), combining to four genetically and biochemically distinct isoenzymes, exhibiting the formulas FEKP (DSPAα1 and α2) and EKP and KP (DSPAβ and DSPAγ). Only DSPAα1 and α2 bind to fibrin. All DSPAs are single-chain molecules, displaying substantial amidolytic activity. In a plasminogen activation assay, all four DSPAs are almost inactive in the absence of fibrin but strongly stimulated by fibrin addition. The catalytic efficiency (kcat/Km) of DSPAα1 increases 105-fold, whereas the corresponding value of t-PA is only 550. The ratio of the bimolecular rate constants of plasminogen activation in the presence of fibrin versus fibrinogen (fibrin selectivity) of DSPAα1, α2, β, γ, and t-PA was found to be 13,000, 6500, 250, 90, and 72, respectively. Whereas all DSPAs are therefore more fibrin dependent and fibrin selective than t-PA, the extent depends on the respective presence of the various domains. The introduction of a plasmin-sensitive cleavage site in a position akin to the one in t-PA partially obliterates fibrin cofactor requirement. Fibrin dependence and fibrin selectivity of DSPAs are accordingly mediated by fibrin binding, which involves the F domain, as yet undefined determinants within the K and P domains, and by the absence of a plasmin-sensitive activation site. These findings transcend the current understanding of fibrin-mediated stimulation of plasminogen activation: in addition to fibrin binding, specific protein-protein interactions come into play, which stabilize the enzyme in its active conformation.
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thrombolytic properties of desmodus rotundus Vampire Bat salivary plasminogen activator in experimental pulmonary embolism in rats
Blood, 1992Co-Authors: Werner Witt, Peter Bringmann, Peter Donner, Berthold Baldus, Linda Cashion, Wolf-dieter SchleuningAbstract:rDSPA alpha 1 (recombinant Desmodus salivary plasminogen activator alpha 1) is a recombinant protein corresponding to a natural plasminogen activator from the Vampire Bat Desmodus rotundus. The thrombolytic properties of rDSPA alpha 1 and tissue-type plasminogen activator (t-PA) were compared in a rat model of pulmonary embolism. Whole blood clots, produced in vitro and labeled with 125I-fibrinogen, were embolized into the lungs of anesthetized rats. Thrombolysis was calculated from the difference between initial clot radioactivity and that remaining in the lungs at 60 minutes. Blood was sampled for gamma counting, measurement of hemostatic factors, and plasminogen activator antigen levels. Thrombolysis at 3, 10, 30, and 100 nmol/kg intravenously (10% bolus, 90% over 60 minutes) amounted to 30% +/- 2%, 51% +/- 4%, 85% +/- 4%, 98% +/- 0% for rDSPA alpha 1 and 30% +/- 3%, 41% +/- 3%, 57% +/- 6%, 93% +/- 2% for t-PA (controls: 29% +/- 2%; mean +/- SEM, n greater than or equal to 6). t-PA at 100 nmol/kg significantly decreased fibrinogen, plasminogen, and alpha 2-antiplasmin levels by 33% +/- 7%, 38% +/- 8%, and 61% +/- 9%, whereas rDSPA alpha 1 at 100 nmol/kg only lowered alpha 2-antiplasmin significantly (by 29% +/- 6%). Compared with t-PA, rDSPA alpha 1 is the more potent and more clot selective (fibrin specific) thrombolytic agent. These results suggest that rDSPA alpha 1 may be safer and more efficacious than currently used thrombolytics.
Peter Bringmann - One of the best experts on this subject based on the ideXlab platform.
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fibrin selectivity of the isolated protease domains of tissue type and Vampire Bat salivary gland plasminogen activators
FEBS Journal, 1998Co-Authors: Luisella Toschi, Peter Donner, Peter Bringmann, Thomas Petri, Wolf-dieter SchleuningAbstract:The activity of Vampire Bat (Desmodus rotundus) salivary plasminogen activator (D. rotundus PA alpha1) and to a much lesser extent of tissue-type plasminogen activator (t-PA) is stimulated by the presence of fibrin. This cofactor requirement has in the past intuitively been attributed to fibrin binding. We have previously shown that elements of the non-protease domain of D. rotundus PA alpha1 could contribute to fibrin stimulation irrespective of fibrin binding. We now demonstrate that the protease domain of D. rotundus PA alpha1 by itself exhibits fibrin selectivity, i.e. it is 32-fold stimulated by fibrin but only 1.5-fold by fibrinogen. To a lesser extent this fibrin selectivity is also shared by the protease domain of t-PA. Our findings indicate that protein-protein interactions apart from fibrin binding affect the stimulatory mechanism of fibrin on D. rotundus PA alpha1 and t-PA.
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Catalytic domain structure of Vampire Bat plasminogen activator: a molecular paradigm for proteolysis without activation cleavage.
Biochemistry, 1997Co-Authors: Martin Renatus, Peter Bringmann, Peter Donner, Milton T. Stubbs, Robert Huber, Wolfram BodeAbstract:The saliva of the blood-eating Vampire Bat Desmodus rotundus contains plasminogen activators (PAs) that maintain the fluidity of the prey's blood by activating plasminogen and dissolving developing fibrin clots. D. rotundus salivary PAs (DSPAs) are composed of evolutionarily conserved domains reminiscent of human tissue-type PA (tPA), but their catalytic domain lacks a plasmin-sensitive “activation cleavage site”. Despite this, all DSPAs are intrinsically active and enormously stimulated in the presence of fibrin. The recombinant catalytic domain of DSPAα1 has been crystallized in a covalent complex with Glu-Gly-Arg-chloromethyl ketone and its structure solved at 2.9 A resolution. The structure is similar to that of activated two-chain human tPA. Despite its single-chain status, the activation domain is observed in an enzymatically active conformation, with a functional substrate binding site and active site accommodating the peptidylmethylene inhibitor. The activation pocket, which normally receives the ...
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structural features mediating fibrin selectivity of Vampire Bat plasminogen activators
Journal of Biological Chemistry, 1995Co-Authors: Peter Bringmann, Wolf-dieter Schleuning, Daniel Gruber, Alexandra Liese, Luisella Toschi, Jorn Kratzschmar, Peter DonnerAbstract:The distinguishing characteristic of Vampire Bat (Desmodus rotundus) salivary plasminogen activators (DSPAs) is their strict requirement for fibrin as a cofactor. DSPAs consist of structural modules known from urokinase (u-PA) and tissue-type plasminogen activator (t-PA) such as finger (F), epidermal growth factor (E), kringle (K), and protease (P), combining to four genetically and biochemically distinct isoenzymes, exhibiting the formulas FEKP (DSPAα1 and α2) and EKP and KP (DSPAβ and DSPAγ). Only DSPAα1 and α2 bind to fibrin. All DSPAs are single-chain molecules, displaying substantial amidolytic activity. In a plasminogen activation assay, all four DSPAs are almost inactive in the absence of fibrin but strongly stimulated by fibrin addition. The catalytic efficiency (kcat/Km) of DSPAα1 increases 105-fold, whereas the corresponding value of t-PA is only 550. The ratio of the bimolecular rate constants of plasminogen activation in the presence of fibrin versus fibrinogen (fibrin selectivity) of DSPAα1, α2, β, γ, and t-PA was found to be 13,000, 6500, 250, 90, and 72, respectively. Whereas all DSPAs are therefore more fibrin dependent and fibrin selective than t-PA, the extent depends on the respective presence of the various domains. The introduction of a plasmin-sensitive cleavage site in a position akin to the one in t-PA partially obliterates fibrin cofactor requirement. Fibrin dependence and fibrin selectivity of DSPAs are accordingly mediated by fibrin binding, which involves the F domain, as yet undefined determinants within the K and P domains, and by the absence of a plasmin-sensitive activation site. These findings transcend the current understanding of fibrin-mediated stimulation of plasminogen activation: in addition to fibrin binding, specific protein-protein interactions come into play, which stabilize the enzyme in its active conformation.
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thrombolytic properties of desmodus rotundus Vampire Bat salivary plasminogen activator in experimental pulmonary embolism in rats
Blood, 1992Co-Authors: Werner Witt, Peter Bringmann, Peter Donner, Berthold Baldus, Linda Cashion, Wolf-dieter SchleuningAbstract:rDSPA alpha 1 (recombinant Desmodus salivary plasminogen activator alpha 1) is a recombinant protein corresponding to a natural plasminogen activator from the Vampire Bat Desmodus rotundus. The thrombolytic properties of rDSPA alpha 1 and tissue-type plasminogen activator (t-PA) were compared in a rat model of pulmonary embolism. Whole blood clots, produced in vitro and labeled with 125I-fibrinogen, were embolized into the lungs of anesthetized rats. Thrombolysis was calculated from the difference between initial clot radioactivity and that remaining in the lungs at 60 minutes. Blood was sampled for gamma counting, measurement of hemostatic factors, and plasminogen activator antigen levels. Thrombolysis at 3, 10, 30, and 100 nmol/kg intravenously (10% bolus, 90% over 60 minutes) amounted to 30% +/- 2%, 51% +/- 4%, 85% +/- 4%, 98% +/- 0% for rDSPA alpha 1 and 30% +/- 3%, 41% +/- 3%, 57% +/- 6%, 93% +/- 2% for t-PA (controls: 29% +/- 2%; mean +/- SEM, n greater than or equal to 6). t-PA at 100 nmol/kg significantly decreased fibrinogen, plasminogen, and alpha 2-antiplasmin levels by 33% +/- 7%, 38% +/- 8%, and 61% +/- 9%, whereas rDSPA alpha 1 at 100 nmol/kg only lowered alpha 2-antiplasmin significantly (by 29% +/- 6%). Compared with t-PA, rDSPA alpha 1 is the more potent and more clot selective (fibrin specific) thrombolytic agent. These results suggest that rDSPA alpha 1 may be safer and more efficacious than currently used thrombolytics.
Vincent Lacoste - One of the best experts on this subject based on the ideXlab platform.
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how social structure drives the population dynamics of the common Vampire Bat desmodus rotundus phyllostomidae
Journal of Heredity, 2018Co-Authors: Mailis Huguin, Vincent Lacoste, Nidia Arechigaceballos, Marguerite Delaval, Amandine Guidez, Isai Jorge De Castro, Arielle Salmier, Alvaro Aguilar Setien, Claudia Regina Silva, Anne LavergneAbstract:Social systems are major drivers of population structure and gene flow, with important effects on dynamics and dispersal of associated populations of parasites. Among Bats, the common Vampire Bat (Desmodus rotundus) has likely one of the most complex social structures. Using autosomal and mitochondrial markers on Vampires from Mexico, French Guiana, and North Brazil, from both roosting and foraging areas, we observed an isolation by distance at the wider scale and lower but significant differentiation between closer populations (<50 km). All populations had a low level of relatedness and showed deviations from Hardy-Weinberg equilibrium and a low but significant inbreeding coefficient. The associated heterozygote deficiency was likely related to a Wahlund effect and to cryptic structures, reflecting social groups living in syntopy, both in roosting and foraging areas, with only limited admixture. Discrepancy between mitochondrial and nuclear markers suggests female philopatry and higher dispersal rates in males, associated with peripheral positions in the groups. Vampires are also the main neotropical reservoir for rabies virus, one of the main lethal pathogens for humans. Female social behaviors and trophallaxis may favor a rapid spread of virus to related and unrelated offspring and females. The high dispersal capacity of males may explain the wider circulation of viruses and the inefficacy of Bat population controls. In such opportunistic species, gene connectivity should be considered for management decision making. Strategies such as culling could induce immigration of Bats from neighboring colonies to fill vacant roosts and feeding areas, associated with the dispersal of viral strains.
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Development of molecular and cellular tools to decipher the type I IFN pathway of the common Vampire Bat.
Developmental and comparative immunology, 2017Co-Authors: Sarkis Sarkis, Marie-claude Lise, Edith Darcissac, Stéphanie Dabo, Marcel Falk, Laura Chaulet, Christine Neuveut, Eliane Meurs, Anne Lavergne, Vincent LacosteAbstract:Abstract Though the common Vampire Bat, Desmodus rotundus, is known as the main rabies virus reservoir in Latin America, no tools are available to investigate its antiviral innate immune system. To characterize the IFN-I pathway, we established an immortalized cell line from a D. rotundus fetal lung named FLuDero. Then we molecularly characterized some of the Toll-like receptors (TLR3, 7, 8 and 9), the three RIG-I-like receptor members, as well as IFNα1 and IFNβ. Challenging the FLuDero cell line with poly (I:C) resulted in an up-regulation of both IFNα1 and IFNβ and the induction of expression of the different pattern recognition receptors characterized. These findings provide evidence of the intact dsRNA recognition machinery and the IFN-I signaling pathway in our cellular model. Herein, we generated a sum of insightful specific molecular and cellular tools that will serve as a useful model to study virus–host interactions of the common Vampire Bat.
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Complete Genome Sequence of a Vampire Bat Rabies Virus from French Guiana.
Genome Announcements, 2016Co-Authors: Anne Lavergne, Edith Darcissac, Hervé Bourhy, Sourakhata Tirera, Benoît De Thoisy, Vincent LacosteAbstract:A rabies virus was detected in a common Vampire Bat (Desmodus rotundus) in French Guiana. Its genomic sequence was obtained and found to be closely related to other hematophagous Bat-related viruses that widely circulate in the northern Amazon region. This virus is named AT6.
Victor J Marder - One of the best experts on this subject based on the ideXlab platform.
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comparison of the bleeding potential of Vampire Bat salivary plasminogen activator versus tissue plasminogen activator in an experimental rabbit model
Circulation, 1995Co-Authors: Michelle Montoney, Stephen J Gardell, Victor J MarderAbstract:Background Vampire Bat salivary plasminogen activator (Bat-PA) has significantly greater fibrin specificity than any of the fibrinolytic agents currently in clinical use. This study tests the hypothesis that avoiding fibrinogen depletion may protect against the hemorrhage induced by plasminogen activator treatment. Methods and Results Bat-PA was compared with tissue-type plasminogen activator (TPA) in a randomized, prospective, and blinded study using a rabbit ear puncture model of fibrinolytic bleeding. The two agents were used at equimolar dosages (42 nmol/kg) that yielded similar thrombolytic efficacies in a rabbit femoral artery thrombosis model. Both Bat-PA and TPA prolong primary bleeding to double the baseline values, from between 2.1 and 2.3 minutes to between 4.8 and 5.2 minutes. Rebleeding from hemostatically stable sites during the 3-hour observation period occurred equally often with Bat-PA and TPA, 31% from preinjection sites and 23% to 25% from postinjection sites. The lag time between the t...
