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Verkleij C, van Zaane B, Squizzato A, Brandjes D, Büller H, Meijers J, Gerdes V, Stuijver D. Thrombin-activatable fibrinolysis inhibitor in hypothyroidism and hyperthyroxinaemia. Thromb Haemost 2017. [DOI: 10.1160/th12-07-0525] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SummaryEndocrine disorders affect both the coagulation and fibrinolytic systems, and have been associated with the development of cardiovascular diseases. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a link between coagulation and the fibrinolytic system. The aim of this study was to determine the effect of thyroid hormone excess and deficiency on TAFI levels and function. The effect of hyperthyroxinemia on TAFI was studied in healthy volunteers who were randomised to receive levothyroxine or no medication for 14 days in a crossover design. The effect of hypothyroidism on TAFI was studied in a multicentre observational cohort study. Blood was drawn before treatment of patients with newly diagnosed hypothyroidism and when euthyroidism was achieved. Plasma clot-lysis times, activated TAFI (TAFIa)-dependent prolongation of clot-lysis and TAFI levels were measured. Thyroid hormone excess resulted in a hypofibrinolytic condition and in an enhanced TAFIa-dependent prolongation of clot lysis. A trend towards decreased plasma TAFI levels was observed in healthy volunteers who used levothyroxine. Hypothyroidism resulted in hyperfibrinolysis and a reduced TAFIa-dependent prolongation of clot lysis. In conclusion, alterations of TAFIa-dependent prolongation of clot lysis in patients with thyroid disorders may cause an impaired haemostatic balance. The disturbed haemostatic balance in patients with hyperthyroidism might make them prone to thrombosis, while the risk for bleeding may increase in patients with hypothyroidism.
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Lin JHH, Novakovic D, Rizzo CM, Zagorac B, Garand M, Filipieva A, Koschinsky ML, Boffa MB. The mRNA encoding TAFI is alternatively spliced in different cell types and produces intracellular forms of the protein lacking TAFIa activity. Thromb Haemost 2017; 109:1033-44. [DOI: 10.1160/th12-09-0668] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 02/27/2013] [Indexed: 11/05/2022]
Abstract
SummaryTAFI (thrombin-activatable fibrinolysis inhibitor) is a pro-carboxypeptidase, encoded by the CPB2 gene in humans that links the coagulation cascade to fibrinolysis and inflammation. The liver is the main source for plasma TAFI, and TAFI expression has been documented in platelets and monocyte-derived macrophages. A recent study reported an alternatively spliced CPB2 mRNA variant lacking exon 7 (Δ7) in HepG2 cells and liver. Another study identified a CPB2 mRNA variant lacking exon 7 and a 52 bp deletion in exon 11 (Δ7+11) in human hippocampus. We have examined alternative splicing of CPB2 mRNA in various cell types by RT-PCR and have assessed the functional properties of TAFI variants encoded by these transcripts by recombinant expression in mammalian cells. We identified the Δ7 exon skipping event in liver, Dami megakaryoblasts, THP-1-derived macrophages, peripheral blood mononuclear cells, platelets, testis, cerebellum, and SH-SY5Y neuroblastoma cells. The Δ11 alternative splicing event was notably absent in liver cells. We also detected a novel exon Δ7+8 skipping event in liver and megakaryocytes. Of note, we detected non-alternatively spliced CPB2 transcripts in brain tissues, suggesting the expression of full-length TAFI in brain. Experiments using cultured mammalian cells transfected with wild-type CPB2-, Δ7-, Δ7+11 -, and_Δ11 -cDNA revealed that alternatively spliced TAFI is stored inside the cells, cannot be activated by thrombin-thrombomodulin, and does not have TAFIa activity. The alternative splicing events clearly do not give rise to a secreted protein with basic carboxy-peptidase activity, but the intracellular forms may possess novel functions related to intracellular proteolysis.
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Reduced thrombin activatable fibrinolysis inhibitor and enhanced proinflammatory cytokines in acute coronary syndrome. Med Intensiva 2016; 41:475-482. [PMID: 28038785 DOI: 10.1016/j.medin.2016.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/09/2016] [Accepted: 10/11/2016] [Indexed: 11/22/2022]
Abstract
OBJECTIVE A study was made of the changes in the serum levels of thrombin activatable fibrinolysis inhibitor (TAFI), proinflammatory cytokines and acute phase proteins in the acute stage of acute coronary syndrome (ACS), in order to explore the possibility of using TAFI as a biomarker for ACS risk assessment. METHODS A total of 211 patients with ACS were enrolled, and healthy subjects were used as controls. Blood samples were taken within 24h after admission. Serum TAFI levels were determined by immunoturbidimetry. Serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were determined by enzyme linked immunosorbent assay (ELISA). Procalcitonin (PCT) and C-reactive protein (CRP) levels were measured by gold-immunochromatographic assay. RESULTS Serum TAFI levels in ACS patients were significantly decreased versus the controls. The IL-1β, IL-6, TNF-α, PCT and CRP levels were markedly higher in the ACS patients than in the controls. Correlation analysis revealed a strong negative correlation between TAFI concentration and the IL-1β, IL-6, TNF-а, PCT and CRP levels in ACS patients and in controls. Multivariate logistic regression analysis suggested decreased serum TAFI to be an independent risk factor for ACS (OR 9.459; 95% CI 2.306-38.793; P=0.002). The area under the receiver operating characteristic (ROC) curve for TAFI was 0.872 (95% CI 0.787-0.909; P<0.001). The optimum TAFI cutoff point for the prediction of ACS was 24μg/ml, with a sensitivity of 75.83% and a specificity of 72.57%. CONCLUSION These findings suggest that TAFI can be useful as a potential biomarker for ACS risk assessment.
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Mook-Kanamori BB, Valls Serón M, Geldhoff M, Havik SR, van der Ende A, Baas F, van der Poll T, Meijers JCM, P Morgan B, Brouwer MC, van de Beek D. Thrombin-activatable fibrinolysis inhibitor influences disease severity in humans and mice with pneumococcal meningitis. J Thromb Haemost 2015; 13:2076-86. [PMID: 26340319 DOI: 10.1111/jth.13132] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 08/16/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mortality and morbidity in patients with bacterial meningitis result from the proinflammatory response and dysregulation of coagulation and fibrinolysis. Thrombin-activatable fibrinolysis inhibitor (TAFI) is activated by free thrombin or thrombin in complex with thrombomodulin, and plays an antifibrinolytic role during fibrin clot degradation, but also has an anti-inflammatory role by inactivating proinflammatory mediators, such as complement activation products. OBJECTIVE To assess the role of TAFI in pneumococcal meningitis. METHODS We performed a prospective nationwide genetic association study in patients with bacterial meningitis, determined TAFI and complement levels in cerebrospinal fluid (CSF), and assessed the function of TAFI in a pneumococcal meningitis mouse model by using Cpb2 (TAFI) knockout mice. RESULTS Polymorphisms (reference sequences: rs1926447 and rs3742264) in the CPB2 gene, coding for TAFI, were related to the development of systemic complications in patients with pneumococcal meningitis. Higher protein levels of TAFI in CSF were significantly associated with CSF complement levels (C3a, iC3b, and C5b-9) and with more systemic complications in patients with bacterial meningitis. The risk allele of rs1926447 (TT) was associated with higher levels of TAFI in CSF. In the murine model, consistent with the human data, Cpb2-deficient mice had decreased disease severity, as reflected by lower mortality, and attenuated cytokine levels and bacterial outgrowth in the systemic compartment during disease, without differences in the brain compartment, as compared with wild-type mice. CONCLUSIONS These findings suggest that TAFI plays an important role during pneumococcal meningitis, which is likely to be mediated through inhibition of the complement system, and influences the occurrence of systemic complications and inflammation.
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MESH Headings
- Adult
- Aged
- Animals
- Brain Damage, Chronic/etiology
- Carboxypeptidase B2/cerebrospinal fluid
- Carboxypeptidase B2/deficiency
- Carboxypeptidase B2/genetics
- Carboxypeptidase B2/physiology
- Cerebral Hemorrhage/etiology
- Community-Acquired Infections/blood
- Community-Acquired Infections/cerebrospinal fluid
- Community-Acquired Infections/complications
- Community-Acquired Infections/genetics
- Complement C3a/cerebrospinal fluid
- Complement C3b/cerebrospinal fluid
- Complement Membrane Attack Complex/cerebrospinal fluid
- Cytokines/blood
- Female
- Fibrinolysis
- Humans
- Male
- Meningitis, Meningococcal/blood
- Meningitis, Meningococcal/cerebrospinal fluid
- Meningitis, Meningococcal/complications
- Meningitis, Meningococcal/genetics
- Meningitis, Pneumococcal/blood
- Meningitis, Pneumococcal/cerebrospinal fluid
- Meningitis, Pneumococcal/complications
- Meningitis, Pneumococcal/genetics
- Mice
- Mice, Inbred C57BL
- Middle Aged
- Polymorphism, Single Nucleotide
- Respiratory Insufficiency/etiology
- Shock, Septic/etiology
- Treatment Outcome
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Affiliation(s)
- B B Mook-Kanamori
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - M Valls Serón
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - M Geldhoff
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - S R Havik
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - A van der Ende
- Medical Microbiology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
- Netherlands Reference Laboratory for Bacterial Meningitis, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - F Baas
- Laboratory for Genome Analysis, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - T van der Poll
- Center for Experimental and Molecular Medicine, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - J C M Meijers
- Department of Experimental Vascular Medicine, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
- Department of Vascular Medicine, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - B P Morgan
- Institute of Infection and Immunity, Cardiff University School of Medicine, Cardiff, UK
| | - M C Brouwer
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
| | - D van de Beek
- Departments of Neurology, Academic Medical Center, Center of Infection and Immunity Amsterdam (CINIMA), Amsterdam, the Netherlands
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Plug T, Marquart JA, Marx PF, Meijers JCM. Selective modulation of thrombin-activatable fibrinolysis inhibitor (TAFI) activation by thrombin or the thrombin-thrombomodulin complex using TAFI-derived peptides. J Thromb Haemost 2015; 13:2093-101. [PMID: 26341360 DOI: 10.1111/jth.13133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) is a risk factor for coronary heart disease. TAFI is proteolytically activated by thrombin, the thrombin-thrombomodulin complex and plasmin. Once active, it dampens fibrinolysis and inflammation. The aim of this study was to generate TAFI-derived peptides that specifically modulate TAFI activation and activity. METHODS Thirty-four overlapping TAFI peptides, and modifications thereof, were synthesized. The effects of these peptides on TAFI activation and TAFIa activity were determined. In addition, the binding of the peptides to thrombin were determined. RESULTS Four peptides (peptides 2, 18, 19 and 34) inhibited TAFI activation and two peptides (peptides 14 and 24) inhibited TAFIa activity directly. Peptide 2 (Arg12-Glu28) and peptide 34 (Cys383-Val401) inhibited TAFI activation by the thrombin-thrombomodulin complex with IC50 values of 7.3 ± 1.8 and 6.1 ± 0.9 μm, respectively. However, no inhibition was observed in the absence of thrombomodulin. This suggests that the regions Arg12-Glu28 and Cys383-Val401 in TAFI are involved in thrombomodulin-mediated TAFI activation. Peptide 18 (Gly205-Ser221) and peptide 19 (Arg214-Asp232) inhibited TAFI activation by thrombin and the thrombin-thrombomodulin complex. Furthermore, these peptides bound to thrombin (KD : 1.5 ± 0.4 and 0.52 ± 0.07 μm for peptides 18 and 19, respectively), suggesting that Gly205-Asp232 of TAFI is involved in binding to thrombin. Peptide 14 (His159-His175) inhibited TAFIa activity. The inhibition was TAFIa specific, because no effect on the homologous enzyme carboxypeptidase B was observed. CONCLUSIONS Thrombin-activatable fibrinolysis inhibitor-derived peptides show promise as new tools to modulate TAFI activation and TAFIa activity. Furthermore, these peptides revealed potential binding sites on TAFI for thrombin and the thrombin-thrombomodulin complex.
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Affiliation(s)
- T Plug
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - J A Marquart
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- Department of Plasma Proteins, Sanquin Research, Amsterdam, the Netherlands
| | - P F Marx
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - J C M Meijers
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- Department of Plasma Proteins, Sanquin Research, Amsterdam, the Netherlands
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Gailani D, Bane CE, Gruber A. Factor XI and contact activation as targets for antithrombotic therapy. J Thromb Haemost 2015; 13:1383-95. [PMID: 25976012 PMCID: PMC4516614 DOI: 10.1111/jth.13005] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/01/2015] [Indexed: 11/26/2022]
Abstract
The most commonly used anticoagulants produce therapeutic antithrombotic effects either by inhibiting thrombin or factor Xa (FXa) or by lowering the plasma levels of the precursors of these key enzymes, prothrombin and FX. These drugs do not distinguish between thrombin generation contributing to thrombosis from thrombin generation required for hemostasis. Thus, anticoagulants increase bleeding risk, and many patients who would benefit from therapy go untreated because of comorbidities that place them at unacceptable risk for hemorrhage. Studies in animals demonstrate that components of the plasma contact activation system contribute to experimentally induced thrombosis, despite playing little or no role in hemostasis. Attention has focused on FXII, the zymogen of a protease (FXIIa) that initiates contact activation when blood is exposed to foreign surfaces, and FXI, the zymogen of the protease FXIa, which links contact activation to the thrombin generation mechanism. In the case of FXI, epidemiologic data indicate this protein contributes to stroke and venous thromboembolism, and perhaps myocardial infarction, in humans. A phase 2 trial showing that reduction of FXI may be more effective than low molecular weight heparin at preventing venous thrombosis during knee replacement surgery provides proof of concept for the premise that an antithrombotic effect can be uncoupled from an anticoagulant effect in humans by targeting components of contact activation. Here, we review data on the role of FXI and FXII in thrombosis and results of preclinical and human trials for therapies targeting these proteins.
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Affiliation(s)
- David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, USA
| | - Charles E. Bane
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, USA
| | - Andras Gruber
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR
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An SSA, Greenfield RS. Alternative Mechanism of Aspirin in Anti-Thrombotic Therapy: Inhibition of Thrombin Activatable Fibrinolysis Inhibitor. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.9.3048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Regulation of the mouse gene encoding TAFI by TNFα: Role of NFκB binding site. Cytokine 2012; 57:389-97. [DOI: 10.1016/j.cyto.2011.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/29/2011] [Accepted: 11/30/2011] [Indexed: 11/18/2022]
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Verkleij CJN, Roelofs JJTH, Havik SR, Meijers JCM, Marx PF. The role of thrombin-activatable fibrinolysis inhibitor in diabetic wound healing. Thromb Res 2010; 126:442-6. [PMID: 20828799 DOI: 10.1016/j.thromres.2010.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 07/12/2010] [Accepted: 08/13/2010] [Indexed: 11/17/2022]
Abstract
INTRODUCTION One of the major complications in patients with diabetes mellitus is impaired wound healing. The fibrinolytic system is involved in parts of the wound healing process and deficiency of thrombin-activatable fibrinolysis inhibitor (TAFI) results in delayed wound closure. Moreover, levels of TAFI are affected by diabetes mellitus. The aim of this study was to elucidate the effect of hyperglycaemia on TAFI and to determine the effect of deficiency of TAFI on wound healing under hyperglycaemic conditions. MATERIALS AND METHODS Hyperglycaemia was induced with streptozotocin (STZ) and used as a model for diabetes mellitus. TAFI plasma levels and TAFI gene expression in the liver were determined. Incisional and excisional wound healing were studied in non-treated and STZ-treated wild-type and TAFI-deficient mice. Wound closure was scored daily as open or closed. RESULTS Mice treated with STZ showed hyperglycaemia, and TAFI plasma levels and TAFI gene expression were increased in diabetic mice. TAFI-deficient mice and diabetic wild-type and diabetic TAFI-deficient mice showed delayed wound healing of incisional wounds. No differences were observed between diabetic and non-diabetic TAFI-deficient mice and between diabetic wild-type and diabetic TAFI-deficient mice. CONCLUSIONS This study illustrated that TAFI was affected by hyperglycaemia and confirmed that TAFI is involved in wound healing. No additional effect was observed under hyperglycaemic conditions, indicating that deficiency of TAFI did not have an additive or synergistic effect in diabetic wound healing. Further research has to elucidate if TAFI and hyperglycemia affect wound healing via similar mechanisms.
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Affiliation(s)
- Chantal J N Verkleij
- Department of Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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Sanglas L, Arolas JL, Valnickova Z, Aviles FX, Enghild JJ, Gomis-Rüth FX. Insights into the molecular inactivation mechanism of human activated thrombin-activatable fibrinolysis inhibitor. J Thromb Haemost 2010; 8:1056-65. [PMID: 20088943 DOI: 10.1111/j.1538-7836.2010.03740.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SUMMARY BACKGROUND Thrombin-activatable fibrinolysis inhibitor (TAFI) is a validated target for thrombotic diseases. TAFI is converted in vivo to activated TAFI (TAFIa) by removal of its pro-domain. Whereas TAFI is stable and persists in the circulation, possibly in complex with plasminogen, TAFIa is unstable and poorly soluble, with a half-life of minutes. OBJECTIVES In order to study the molecular determinants of this instability, we studied the influence of protein inhibitors on human TAFIa. RESULTS We found that protein inhibitors significantly reduced the instability and insolubility of TAFIa. In addition, we solved the 2.5-A resolution crystal structure of human TAFIa in complex with a potent protein inhibitor, tick-derived carboxypeptidase inhibitor, which gives rise to a stable and soluble TAFIa species. The structure revealed a significant reduction in the flexibility of dynamic segments when compared with the structures of bovine and human TAFI. We also identified two latent hotspots, loop Lbeta2beta3 and segment alpha5-Lalpha5beta7-beta7, where conformational destabilization may begin. These hotspots are also present in TAFI, but the pro-domain may provide sufficient stabilization and solubility to guarantee protein persistence in vivo. When the pro-domain is removed, the free TAFIa moiety becomes unstable, its activity is suppressed, and the molecule becomes insoluble. CONCLUSIONS The present study corroborates the function of protein inhibitors in stabilizing human TAFIa and it provides a rigid and high-resolution mold for the design of small molecule inhibitors of this enzyme, thus paving the way for novel therapy for thrombotic disorders.
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Affiliation(s)
- L Sanglas
- Departament de Bioquímica i Biologia Molecular, Facultat de Ciències, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
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