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Blood, Vol. 94 No. 8 (October 15), 1999:
pp. 2735-2743
By
From the Hamilton Civic Hospitals Research Centre and McMaster
University, Hamilton, Ontario, Canada.
Achieving early, complete, and sustained reperfusion after acute
myocardial infarction does not occur in approximately 50% of patients,
even with the most potent established thrombolytic therapy. Bleeding is
observed with increased concentrations of thrombolytics as well as with
adjunctive antithrombotic and antiplatelet agents. A novel approach to
enhance thrombolytic therapy is to inhibit the activated form of
thrombin-activatable fibrinolysis inhibitor (TAFI), which attenuates
fibrinolysis in clots formed from human plasma. Identification of TAFI
in rabbit plasma facilitated the development of a rabbit arterial
thrombolysis model to compare the thrombolytic efficacy of
tissue-plasminogen activator (tPA) alone or with an inhibitor, isolated
from the potato tuber (PTI), of activated TAFI (TAFIa). Efficacy was
assessed by determining the time to patency, the time the vessel
remained patent, the maximal blood flow achieved during therapy, the
percentage of the original thrombus, which lysed, the percentage change
in clot weight, the net clot accreted, and the release of radioactive fibrin degradation products into the circulation. The results indicate
that coadministration of PTI and tPA significantly improved tPA-induced
thrombolysis without adversely affecting blood pressure, activated
partial thromboplastin time, thrombin clotting time, fibrinogen, or
ACUTE MYOCARDIAL infarction is triggered
by rupture of an atherosclerotic plaque and superimposed
thrombus.1 Although thrombolytic therapy increases survival
of patients with acute myocardial infarction, rapid and sustained
reperfusion of the infarct-related artery is achieved in approximately
50% of patients.2-4 Development of better thrombolytic
agents or more effective adjunctive antithrombotic therapy5
has improved overall efficacy of coronary thrombolysis
marginally.6,7 There are minimally 2 possible explanations
for these disappointing results. First, rethrombosis may be induced by
the procoagulant state that accompanies the thrombolytic process.
Second, coronary thrombi may be inherently resistant to
thrombolysis.8-10 Although thrombin generated during fibrinolysis may contribute to rethrombosis by inducing clot accretion, it may also contribute to the production of inherently more resistant thrombi by activating an inhibitor of fibrinolysis, referred to as
thrombin-activatable fibrinolysis inhibitor (TAFI). This would necessarily decrease the efficacy of fibrinolytic agents in vivo. Potentially, inactivation of thrombin or activated TAFI (TAFIa) during
thrombolysis would improve outcome.
Antithrombotics most widely used potentiate inhibition of thrombin by
antithrombin III. The limitations of antithrombin III-dependent thrombin inhibitors, such as heparin and its derivatives, have been
attributed to their inability to completely inhibit activation of
prothrombin and inhibit thrombin bound to fibrin.11
Thrombin bound to fibrin may represent a pool that may be active,
protected from inhibition, and released to stimulate and amplify its
own generation by activating platelets,12 factors V and
VIII,13 and factor XI.10 To circumvent
limitations associated with indirect inhibitors, efforts have been
directed towards developing new direct thrombin inhibitors, including
hirudin and its derivatives.14,15 The high concentrations
of these agents required for efficacy is associated with increase in
spontaneous bleeding complications.16-18 A novel
alternative to inhibition of thrombin or its generation as adjunctive
thrombolytic therapy may be to reduce the inherent resistance of a
thrombus to tissue-plasminogen activator (tPA)-induced thrombolysis by
inhibiting TAFIa.10,19 In contrast to adjuvants comprising
anticoagulants, this approach would preserve both thrombin's activity
and the ability to generate thrombin distal to the target thrombus
potentially overcoming safety issues.
The zymogen TAFI, also known as plasma procarboxypeptidase B, is found
in human plasma and circulates as a precursor of an exopeptidase with
carboxypeptidase B-like specificity.20,21 TAFI is also
referred to as procarboxypeptidase U21a; however, this
remains unproven. It is activated by thrombin alone, although thrombomodulin enhances the rate of thrombin catalyzed activation of
TAFI by 1,250-fold.22-26 TAFIa is inhibited by a
carboxypeptidase inhibitor isolated from the potato tuber
(PTI).22,26,27 This 39 amino acid peptide is a specific
inhibitor of both the carboxypeptidase A and B family of
proteases.28,29 It has been postulated that PTI potentiates
fibrinolysis by inhibiting TAFIa-dependent removal of C-terminal lysine
residues exposed on fibrin partially degraded by
plasmin.26,30,31 These C-terminal lysine residues are
considered to be potent cofactors in tPA-mediated activation of
plasminogen.32,33 Presumably, C-terminal lysines increase
the efficacy of tPA to activate plasminogen and induce thrombolysis by
facilitating both colocalization of the components and stabilization of
the ternary complex comprising tPA-fibrin-plasminogen.34 In
view of this mechanistic advantage, we designed experiments to
determine whether administration of PTI would improve tPA-induced
thrombolysis in vivo and, therefore, could be used as an adjunct with
tPA. We first established the presence of TAFI in rabbit plasma and
subsequently developed a rabbit arterial thrombolysis model, a modified
rat model,35 that permits assessment of both thrombolysis
and net thrombus accreted during tPA-induced thrombolysis. Using this model, we compared the relative effects of tPA alone or tPA in combination with PTI on lysis of the original thrombus, thrombus growth
(net clot accreted), and vessel patency.
Reagents
Surgery
Thrombus and Stenosis Generation
Treatment Groups In group I SAL/SAL (n = 6), equivalent volumes (1.0 mL) of saline were
administered in place of tPA or PTI where appropriate. In group
IItPA/SAL (n = 4), an IV bolus of 0.25 mg/kg tPA and an infusion of
0.25 mg/kg tPA per 60 minutes were administered. In group IIISAL/PTI
(n = 5) , and IV bolus of 0.5 mg/rabbit PTI was administered. In group
IVtPA/PTI (n = 4), IV boluses of 0.5 mg/rabbit PTI and 0.25 mg/kg tPA
followed by IV infusions of 0.25 mg/kg per 60 minutes were
administered. Harvard apparatus (pump 44, model 4200-005; Harvard
Apparatus Inc, South Natick, MA) was used for the infusion of treatments.
Blood Collection Blood (1.8 mL) was collected into 0.2 mL of 3.8% sodium citrate immediately before clot induction (0 minute), postinjection of PTI (30 minutes), postadministration of a bolus and initiation of an infusion of tPA (35 minutes), and at 45, 60, 75, and 90 minutes. A schematic diagram of the procedure is shown in Fig 2. Blood samples were centrifuged at 1,700g for 15 minutes in an eppendorf centrifuge (Netheler & Hinz GmbH, Hamburg, Germany), and the plasma was stored on ice until the end of each experiment. They were subsequently stored at 70°C for later analysis of activated partial thromboplastin
time (APTT), thrombin clotting time (TCT),  -2 antiplasmin, and
fibrinogen concentrations and determination of ex vivo lysis time using
a turbidometric fibrinolysis assay.
Endpoints Thrombolysis in vivo.
(1) The percentage change in clot weight (PCCW) is the net result of
clot lysis and net accretion calculated from the clot weight (in
milligrams) generated in tubes before treatment and clot weight (in
milligrams) explanted from the aorta at 90 minutes after clot formation
as follows: PCCW = ([explanted clot weight/tube clot weight] × 100)
Flow.
(1) Time to aortic patency (TP; in minutes) is the time required to
achieve aortic blood flow of
Coagulation and Fibrinolytic Parameters APTT was determined according to the method of Proctor and Rapaport,37 TCT was determined according to Seegers and Smith,38 fibrinogen concentrations were determined using the method of Clauss,39 and-2 antiplasmin
concentrations were determined using the method of Teger-Nilsson et
al.40 These parameters were determined for each plasma
sample at each time interval by the Hemostasis Reference Laboratory
(HCHRC, Hamilton, Ontario, Canada).
Fibrinolysis Assay (In Vitro) Quantification of fibrinolysis was performed according to methodology previously described for clots formed from human plasma.41 Briefly, citrated rabbit plasma was diluted one third with HBS. Diluted plasma (95 µL) was added to the wells of a microtiter plate containing 2 µL of 0.3 µmol/L thrombin dissolved in 0.5 mol/L Ca2+, HBS, and 0.01% Tween 80 in the presence or absence of 3 µL of 0.5 µg/mL tPA dissolved in HBS/0.01% Tween 80. Turbidity was monitored at 405 nm and 37°C for 5 hours at 2-minute intervals using a SpetraMAX Plus (Molecular Devices, Sunnyvale, CA). Duplicate lysis time determinations were calculated for each time point by identifying the time required to achieve the half-maximal absorbance observed during the dissolution of the turbid fibrin clot. Additionally, the absolute effect of PTI on lysis time in vitro was assessed for the 0 time point only, for each rabbit, by determining the lysis time in the absence and presence of a saturating concentration of PTI (10 µg/mL). Comparison of lysis times of clots formed from plasma withdrawn from the rabbit at later time points during treatment was the basis for the determination of the presence of PTI infused into the rabbit. In instances after the infusion of tPA lysis, time was too short, due to the excess of infused tPA, to unequivocally assess the presence/absence of PTI functionally in the rabbit.Gel Electrophoresis and Western Blotting Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed as described by Neville42 and Western blotting was performed as indicated by Towbin et al.43 Briefly, reduced samples were subjected to electrophoresis on a 5% to 15% gradient gel and subsequently transferred to nitrocellulose and blocked with 5% nonfat dry milk in HBS/0.05% Tween 20. Antigen was probed for 2 hours with 1.0 µg/mL horseradish peroxidase-conjugated goat anti-TAFI polyclonal antibody (Affinity Biologicals Inc, Hamilton, Ontario, Canada) dissolved in HBS/Tween 20 and detected using chemiluminescence ECL reagents (Amersham Life Sciences, Oakville, Ontario, Canada) and X-Omat film (Kodak Scientific Imaging, Amersham).Statistical Analysis The data are expressed as the mean ± SEM. Significance (P < .03) was assessed using the Student's t-test for data within the treatment groups and a 2-tailed ANOVA test for data between treatment groups.
Presence of TAFI in Rabbit Plasma PTI specifically potentiates tPA-induced fibrinolysis in clots of human plasma. Similarly, PTI reduced the lysis time of clots formed from rabbit plasma by a factor of 5.6 at saturating concentrations. In the absence of PTI, lysis time was 140 minutes and was saturably reduced to approximately 25 minutes with 0.25 µg/mL PTI (Fig 3A). Because PTI was homogeneous, as assessed by SDS-PAGE, and lysis time increased, marginally, upon subsequent addition of PTI to 200 µg/mL, it is concluded that PTI neither contains an inhibitor of fibrinolysis as a contaminant nor inhibits fibrinolysis at the concentrations used. The data also provide indirect evidence for the presence of TAFI in rabbit plasma. The presence of TAFI in rabbit plasma is further evidenced by a Western blot of rabbit plasma (Fig 3A, inset), which indicates that a polyclonal antibody, raised against human TAFI, cross-reacts with a protein of similar molecular mass in rabbit plasma. Additionally, inhibition of thrombin formation during fibrinolysis, using factor Xa inhibitor from the tick (Tick anticoagulant peptide [TAP]), also shortened lysis time from 150 to 30 minutes at saturating concentrations (>2 µmol/L; Fig 3B). Inclusion of a saturating concentration of PTI did not appreciably shorten lysis time further. These results are consistent with the requirement for the generation of high concentrations of thrombin during fibrinolysis to activate rabbit TAFI. Furthermore, because PTI is unable to shorten lysis time any further than TAP alone, the effect of PTI on lysis time is solely mediated through the inhibition of TAFI. Therefore, rabbit plasma contains an inhibitor of fibrinolysis that requires activation by thrombin, is inhibited by PTI, and whose zymogen comigrates with human TAFI and is recognized by antibodies directed at human TAFI.
Pharmacokinetics of PTI Because PTI inhibits TAFIa-dependent prolongation of lysis of clots formed from rabbit plasma in vitro, we wished to determine whether PTI potentiates fibrinolysis in vivo. As a first step, the pharmacokinetics of PTI were determined both by monitoring I125-labeled PTI (I125-PTI) and by assessing function through the use of an ex vivo clot lysis assay. The half-life of both the labeled I125-PTI and the functional presence of infused PTI is approximately 25 minutes (Fig 4). High counts, associated with I125-PTI, were measured in urine after infusion, indicating that clearance may be mediated by the kidney. Because 0.5 mg of PTI was infused into the rabbits, the calculated initial plasma concentration of PTI is 4.9 µg/mL. After 3 half-lives (75 minutes), the expected concentration of 0.6 µg/mL is near, but exceeds, the concentration of PTI needed to maximally inhibit TAFI-dependent prolongation of lysis time (Fig 3A). Therefore, PTI would be present and able to completely inhibit TAFI-dependent prolongation of lysis time for the duration of 60 minutes of treatment in an experiment in vivo. This is supported by the functional data, shown in Fig 4, in which lysis time was observed to become prolonged only after 60 minutes subsequent to the IV injection of PTI.
Ex Vivo Fibrinolysis Compliance with the treatment protocol from experiments performed in vivo was assessed using an ex vivo clot lysis assay. As indicated in Materials and Methods, a turbidometric fibrinolysis assay was used to demonstrate the presence of both PTI and tPA. Plasma clots were formed in duplicate, both in the presence and absence of exogenously added tPA to the wells of the microtiter plate, and lysis times were determined (Fig 5). In the presence of exogenously added tPA, clots from the plasma of rabbits receiving PTI alone reduced the average lysis time from 160 to 30 minutes. Furthermore, PTI activity was observed for the duration of the experiment, because the ex vivo rates of fibrinolysis were still enhanced significantly (160 to 50 minutes) at the final time point. Infusion of tPA reduced ex vivo
lysis time to approximately 10 minutes and was apparently unaffected by
coadministration of PTI.
Efficacy of Treatment Clot lysis, perhaps the most important endpoint, was calculated as the percentage difference between I125-Fibrin in the control and residual I125-Fibrin remaining in the thrombus after treatment. This measurement is indicative of lysis of the initial clot, where counts are proportional to initial clot mass. PTI significantly potentiated tPA-induced clot lysis, achieving 89% degradation of the initial clot (Table 1). In contrast, only 54% of the clot had lysed with tPA alone. Although tPA induced 15% greater lysis than the endogenous thrombolysis observed with Sal/Sal treatment, this value does not approach significance. Endogenous plasminogen activators appear to induce spontaneous clot lysis and account for approximately 39% clot degradation, which was only slightly elevated in the presence of PTI (44%). Release of I125-FDPs into the blood exhibited a similar trend when compared with clot lysis produced with each treatment. However, only treatment with both tPA and PTI achieved a significant elevation of the blood concentration of I125-FDPs released from the initial clot. Although quantification of released I125-FDPs is not a particularly sensitive method to demonstrate clot lysis, it appears to confirm clot lysis determinations. A second parameter, percentage change in clot weight, is composed of at least 3 components and indicates the net result of an increase in weight due to clot accretion and a decrease in clot weight due to lysis of both the accreted clot and the original radiolabeled clot. Only treatment comprising both tPA and PTI was able to reduce the endpoint clot mass compared with the original clot mass. In contrast, a 21% increase in endpoint clot mass was observed with tPA treatment alone, even though 54% of the original clot was lysed. However, tPA alone reduced the percentage change in clot weight by at least a factor of 2 when compared with either Sal/Sal (increase of 49.7%) or Sal/PTI (increase of 54.7%). Therefore, compared with tPA alone, coadministration of PTI significantly enhanced the efficacy of tPA-induced thrombolysis.
Effect of PTI on APTT, TCT, Both Fibrinogen and Antiplasmin Concentrations, and Blood Pressure PTI alone does not affect APTT (22.5 ± 0.7 seconds), TCT (8.3 ± 0.1 seconds), fibrinogen concentration (2.45 ± 0.04 g/L), or antiplasmin concentrations (0.97 ± 0.02 U/mL) when compared with Sal/Sal treatment (23.8 ± 0.5 seconds, 8.1 ± 0.1 seconds, 2.45 ± 0.05 g/L, and 1.06 ± 0.02 U/mL, respectively), where mean values are expressed ± SEM for all 42 samples, which represents all time points for all 6 rabbits. In contrast, tPA induces an initial 50% increase in APTT at 35 minutes over that observed with Sal/Sal, which returns to baseline by 45 minutes, and an initial 500% increase in TCT, over that observed with Sal/Sal, which decreases by 45 minutes to a sustained 300% increase for the remainder of the experiment. Administration of both PTI and tPA did not exacerbate the pronounced prolongation of either APTT or TCT induced by tPA. Both tPA and tPA with PTI significantly decreased the concentrations of both fibrinogen and antiplasmin to a similar extent (~80% of initial concentration), which indicates that PTI does not potentiate tPA-induced consumption of these components. Furthermore, mean blood pressure (~46 mmHg), measured in the carotid artery, was not affected during the full 90 minutes of the experiment for any treatment group. These data, although limited, indicate that an inhibitor of TAFIa, such as PTI, does not affect either the production of thrombin or the actions of thrombin to form a clot or to induce any significant potentiation of tPA-induced fibrinogenolysis.
In our study, we compared the efficacy of tPA-induced lysis in both the absence and presence of an inhibitor of TAFIa in a rabbit arterial thrombolysis model. We attempt to assess the clinical relevance of a TAFIa inhibitor on thrombolysis and indirectly establish the (patho)physiological role of TAFIa in this process. To date, TAFI has been isolated only from human plasma.20,22 However, TAFI has been inferred to be present in the plasma of other mammalian species.44-46 Before initiation of in vivo experimentation using a rabbit model, we confirmed the presence of TAFI in rabbit plasma using an antibody raised against human TAFI and Western blotting (Fig 3). The presence of TAFI was also demonstrated functionally in 3 ways. First, TAP (an inhibitor of factor Xa that inhibits prothrombin activation47,48) enhances lysis time, demonstrating that thrombin production during fibrinolysis prolongs lysis time (Fig 3), providing evidence for the existence of an inhibitor of fibrinolysis that was activated by thrombin. Second, PTI shortened lysis time in ex vivo fibrinolysis assay, but only when thrombin is produced during fibrinolysis (Fig 3). Thus, rabbit TAFI is similar in these respects to human TAFI.
The authors thank Dr G. Klement for statistical analyses, Dr S. Krisnaswamy for kindly providing rTAP, Dr M.E. Nesheim for providing human thrombin, and Vicky Miller for technical assistance.
Submitted January 14, 1999; accepted June 15, 1999.
Supported by Grants No. NA-3568 and T-3644 from the Heart and Stroke Foundation of Ontario. L.B. is a Research Scholar of the Heart and Stroke Foundation of Canada.
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. section 1734 solely to indicate this fact.
Address reprint requests to Laszlo Bajzar, PhD, McMaster University and the Hamilton Civic Hospitals Research Centre, 711 Concession St, Hamilton, Ontario, Canada L8V 1C3; e-mail: lbajzar{at}thrombosis.hhscr.org.
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  M. E. Meltzer, C. J.M. Doggen, P. G. de Groot, J. C.M. Meijers, F. R. Rosendaal, and T. Lisman Low thrombin activatable fibrinolysis inhibitor activity levels are associated with an increased risk of a first myocardial infarction in men Haematologica, June 1, 2009; 94(6): 811 - 818. [Abstract] [Full Text] [PDF]
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 C. Wu, P. Y. Kim, R. Manuel, M. Seto, M. Whitlow, M. Nagashima, J. Morser, A. Gils, P. Declerck, and M. E. Nesheim The Roles of Selected Arginine and Lysine Residues of TAFI (Pro-CPU) in Its Activation to TAFIa by the Thrombin-Thrombomodulin Complex J. Biol. Chem., March 13, 2009; 284(11): 7059 - 7067. [Abstract] [Full Text] [PDF]
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 J. I. Weitz, J. Hirsh, and M. M. Samama New Antithrombotic Drugs: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) Chest, June 1, 2008; 133(6_suppl): 234S - 256S. [Abstract] [Full Text] [PDF]
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 A. H.C. Guimaraes, N. Laurens, E. M. Weijers, P. Koolwijk, V. W.M. van Hinsbergh, and D. C. Rijken TAFI and Pancreatic Carboxypeptidase B Modulate In Vitro Capillary Tube Formation by Human Microvascular Endothelial Cells Arterioscler. Thromb. Vasc. Biol., October 1, 2007; 27(10): 2157 - 2162. [Abstract] [Full Text] [PDF]
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L. O. Mosnier and B. N. Bouma Regulation of Fibrinolysis by Thrombin Activatable Fibrinolysis Inhibitor, an Unstable Carboxypeptidase B That Unites the Pathways of Coagulation and Fibrinolysis Arterioscler. Thromb. Vasc. Biol., November 1, 2006; 26(11): 2445 - 2453. [Abstract] [Full Text] [PDF]
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 O. Kaftan, O. S. Balcik, H. Cipil, G. Ozet, N. Bavbek, A. Kosar, and S. Dagdas Plasma Levels of Thrombin-Activatable Fibrinolysis Inhibitor in Primary and Secondary Thrombocytosis Clinical and Applied Thrombosis/Hemostasis, October 1, 2005; 11(4): 449 - 454. [Abstract] [PDF]
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J. L. Arolas, J. Lorenzo, A. Rovira, J. Castella, F. X. Aviles, and C. P. Sommerhoff A Carboxypeptidase Inhibitor from the Tick Rhipicephalus bursa: ISOLATION, cDNA CLONING, RECOMBINANT EXPRESSION, AND CHARACTERIZATION J. Biol. Chem., February 4, 2005; 280(5): 3441 - 3448. [Abstract] [Full Text] [PDF]
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 A. C. Parker, L. V. Mundada, A. H. Schmaier, and W. P. Fay Factor VLeiden Inhibits Fibrinolysis In Vivo Circulation, December 7, 2004; 110(23): 3594 - 3598. [Abstract] [Full Text] [PDF]
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J. I. Weitz, J. Hirsh, and M. M. Samama New Anticoagulant Drugs: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy Chest, September 1, 2004; 126(3_suppl): 265S - 286S. [Abstract] [Full Text] [PDF]
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 K. Suzuki, Y. Muto, K. Fushihara, K.-i. Kanemoto, H. Iida, E. Sato, C. Kikuchi, T. Matsushima, E. Kato, M. Nomoto, et al. J. Pharmacol. Exp. Ther., May 1, 2004; 309(2): 607 - 615. [Abstract] [Full Text] [PDF]
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 M. Colucci, B. M. Binetti, A. Tripodi, V. Chantarangkul, and N. Semeraro Hyperprothrombinemia associated with prothrombin G20210A mutation inhibits plasma fibrinolysis through a TAFI-mediated mechanism Blood, March 15, 2004; 103(6): 2157 - 2161. [Abstract] [Full Text] [PDF]
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J. B. Walker, B. Hughes, I. James, P. Haddock, C. Kluft, and L. Bajzar Stabilization Versus Inhibition of TAFIa by Competitive Inhibitors in Vitro J. Biol. Chem., March 7, 2003; 278(11): 8913 - 8921. [Abstract] [Full Text] [PDF]
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A. K.C. Chan, J. Rak, L. Berry, P. Liao, M. Vlasin, J. Weitz, and P. Klement Antithrombin-Heparin Covalent Complex: A Possible Alternative to Heparin for Arterial Thrombosis Prevention Circulation, July 9, 2002; 106(2): 261 - 265. [Abstract] [Full Text] [PDF]
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I. Juhan-Vague, P.E. Morange, H. Aubert, M. Henry, M.F. Aillaud, M.C. Alessi, A. Samnegard, E. Hawe, J. Yudkin, M. Margaglione, et al. Plasma Thrombin-Activatable Fibrinolysis Inhibitor Antigen Concentration and Genotype in Relation to Myocardial Infarction in the North and South of Europe Arterioscler. Thromb. Vasc. Biol., May 1, 2002; 22(5): 867 - 873. [Abstract] [Full Text] [PDF]
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 T. Hryszko, J. Malyszko, J. S. Malyszko, S. Brzosko, K. Pawlak, and M. Mysliwiec A possible role of thrombin-activatable fibrinolysis inhibitor in disturbances of fibrinolytic system in renal transplant recipients Nephrol. Dial. Transplant., August 1, 2001; 16(8): 1692 - 1696. [Abstract] [Full Text] [PDF]
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J. I. Weitz and J. Hirsh New Anticoagulant Drugs Chest, January 1, 2001; 119(1_suppl): 95S - 107S. [Full Text] [PDF]
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L. Bajzar Thrombin Activatable Fibrinolysis Inhibitor and an Antifibrinolytic Pathway Arterioscler. Thromb. Vasc. Biol., December 1, 2000; 20(12): 2511 - 2518. [Abstract] [Full Text] [PDF]
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M. C. Minnema, R. J. G. Peters, R. de Winter, Y. P. T. Lubbers, S. Barzegar, K. A. Bauer, R. D. Rosenberg, C. E. Hack, and H. t. Cate Activation of Clotting Factors XI and IX in Patients With Acute Myocardial Infarction Arterioscler. Thromb. Vasc. Biol., November 1, 2000; 20(11): 2489 - 2493. [Abstract] [Full Text] [PDF]
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I. Juhan-Vague, J. F. Renucci, M. Grimaux, P. E. Morange, J. Gouvernet, Y. Gourmelin, and M. C. Alessi Thrombin-Activatable Fibrinolysis Inhibitor Antigen Levels and Cardiovascular Risk Factors Arterioscler. Thromb. Vasc. Biol., September 1, 2000; 20(9): 2156 - 2161. [Abstract] [Full Text] [PDF]
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 J. E. Ansell, J. I. Weitz, and A. J. Comerota Advances in Therapy and the Management of Antithrombotic Drugs for Venous Thromboembolism Hematology, January 1, 2000; 2000(1): 266 - 284. [Abstract] [Full Text] [PDF]
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G. Venhudova, F. Canals, E. Querol, and F. X. Aviles Mutations in the N- and C-terminal Tails of Potato Carboxypeptidase Inhibitor Influence Its Oxidative Refolding Process at the Reshuffling Stage J. Biol. Chem., April 6, 2001; 276(15): 11683 - 11690. [Abstract] [Full Text] [PDF]
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TOP
ABSTRACT
INTRODUCTION
-2-antiplasmin concentrations. The data indicate that inhibitors of
TAFIa may comprise novel and very effective adjuncts to tPA and improve
thrombolytic therapy to achieve both clot lysis and vessel patency.
0.2 mL/min. Aortic blood flow was
measured using the Transonic Blood Flow Monitoring System, which
consisted of 2 transonic flow probes (model no. 2.5SB232) connected to
the CH-10 extension cables and an AT 206 Medical Flowmeter, dual
channel (Transonic Systems Inc, Ithaca, NY). Results from 1 rabbit in
group IV were excluded due to flow probe malfunction.
of patent intervals during 60 minutes in the aorta (min)/60 minutes] × 100), where 60 minutes
of patency is 100% and 
) or presence (
) of 5 µg/mL
PTI. Indicated values are the average from 2 experiments, in which the
range did not exceed 5% of the mean. These data indicate that rabbit
plasma contains TAFI, which, when activated by thrombin, is able to
prolong lysis time and is inhibited by the carboxypeptidase inhibitor
PTI.
), 5 rabbits treated with Sal/PTI (
), 4 rabbits
treated with tPA/Sal (