Dr. Tracy received her Ph.D. in Biology, with an emphasis in Biochemistry, from Syracuse University in 1977. Her current interests in how platelets regulate blood clotting reactions developed as a result of her 5 years of post-doctoral training in the Special Coagulation Laboratory, Division of Hematology at the Mayo Clinic in Rochester, MN. Her first university appointment was made in 1983 as an Assistant Professor of Pathology at the University of Rochester, Rochester, NY. In 1985, she moved to the University of Vermont as a Research Assistant Professor of Medicine and Biochemistry and member of the Thrombosis Research Center. She became a tenured Professor of Biochemistry in 1995, and in July 2005, accepted the position of Interim Chairperson of the department. In addition to her research activities and pre- and post-doctoral training activities, Dr. Tracy also has assumed a significant teaching role in the graduate and medical schools. She is a strong proponent of academia and thus spends her time between administration, research, teaching and mentoring her students. As a result of her research and training endeavors, Dr. Tracy serves on the editorial board of several journals related to hemostasis and thrombosis, was a member of the National Institutes of Health Hematology Study Section for eight years and served as Chairperson of several highly specialized meetings, such as the Gordon Research Conference on Hemostasis in 1996, the FASEB Summer Research Conference on Proteases in Vascular Biology, and most recently shared the responsibility for the 22nd Annual Meeting of the International Society of Thrombosis and Haemostasis in Boston, MA, July 2009.
1976-1977 Syracuse University Senate Research Fellowship
1977 Alexander Gourevitch Award for Meritorious Achievements in Research, Syracuse University
1982 Edward C. Kendall Award for Meritorious Research, Mayo Clinic
1987-1992 Established Investigator, American Heart Association
1994 Vice-chair, Gordon Conference on Hemostasis
1996 Chair, Gordon Conference on Hemostasis
2001 AHA Council on Arteriosclerosis, Thrombosis and Vascular Biology, Special Recognition Award
2003 University Scholar 2003-2004, University of Vermont
2004 University Scholar, University of Vermont
2005 American Medical Women's Association, "Gender Equity Award," UVM Chapter
2007-2009 Chairperson (Basic Sciences), Program Committee, 22nd Congress of the International Society on Thrombosis and Haemostasis, July 11-16, 2009, Boston, MA
Councillor, International Society on Thrombosis and Haemostasis 2010-2016
Silverman JB, Babiarz PS, Mahajan KP, Buschek J and Fondy TP: 1-Halo-analogs of dihydroxyacetone-3-phosphate. The effects of the flouroanalog on cytosolic glycerol-3-phosphate dehydrogenase and triosephosphate isomerase (1975). Biochemistry 14:2252-2258.
Pero RW, Babiarz PB and Fondy TP: Synthesis of 1-fluoro-3-hydroxyacetone, some esters and ethers. Effects in BDF1 mice (1977). J. Med. Chem. 20:644-647.
Dunham P, Babiarz-Tracy P, Israel A, Zerial A and Weissman G: Membrane fusion: studies employing a calcium-sensitive dye, arsenazo III, in liposomes (1977). Proc. Natl. Acad. Sci., USA 74:1580-1584.
Kornbluth R, Tracy PB and Fondy TP: Isoenzyme forms of NAD-linked glycerol-3-phosphate dehydrogenase from rabbit brain (1979). Biochem. Biophys. Acta 568:273-286.
Tracy PB, McCarthy D, Simon P, Burlingham WJ and Fondy TP: Esters of chlorohydroxyacetone in chemotherapy of murine tumors (1980). Cancer Res. 40:3274-3280.
Tracy PB, Peterson JM, Nesheim ME, McDuffie FC and Mann KG: Interaction of coagulation Factor V and Factor Va with platelets (1979). J. Biol. Chem. 254:10354-10361
Tracy PB, Nesheim ME and Mann KG: Coordinate binding of Factor Va and Factor Xa to the unstimulated platelet (1981). J. Biol. Chem. 256:743-751.
Mann KG, Nesheim ME and Tracy PB: The molecular weight of undegraded plasma Factor V (1981). Biochemistry 20:28-33.
Giles AR, Nesheim ME, Hoogendorn H, Tracy PB and Mann KG: Stroma free human platelet lysates potentiate the in vivo thrombogenicity of Factor Xa by the provision of coagulant active phospholipid (1982). Br. J. Haematol. 51:457-568.
Giles AR, Nesheim ME, Hoogendoorn H, Tracy PB and Mann KG: The coagulant-active phospholipid content is a major determinant of the in vivo thrombogenicity of prothrombin complex (Factor IX) concentrates in rabbits (1982). Blood 59:401-407.
Tracy PB, Eide LL, Bowie EJW and Mann KG: Radioimmunoassay of Factor V in human plasma and platelets (1982). Blood 60:59-63.
Tracy PB, Nesheim ME and Mann KG: Proteolytic alterations of Factor Va bound to platelets (1983). J. Biol. Chem. 258:662-669.
Tracy PB and Mann KG: Prothrombinase complex assembly on the platelet surface is mediated through the 74,000 dalton component of Factor Va (1983). Proc. Natl. Acad. Sci., USA 80:2380-2384.
Tracy PB, Rohrbach MS and Mann KG: Functional prothrombinase complex assembly on isolated monocytes and lymphocytes (1983). J. Biol. Chem. 258:7264-7267.
Rohrbach MS, Rolstad RA, Tracy PB and Russell JA: Platelet 5-hydroxytryptamine release and aggregation promoted by cotton bracts tannin (1984). J. Lab. Clin. Med. 103:152-160.
Bern MM, K Suzuki K, Mann KG, Tracy P, Hoyer L, Jensen W, Gallivan M, Arkin C and Davis G: Response of protein C and protein C inhibitor to warfarin therapy in patients with combined deficiency of factors V and VIII (1984). Thrombosis Research 36:485-495.
Tracy PB, Giles AR, Mann KG and Rivard G: Factor V (Quebec): A bleeding diathesis associated with a qualitative platelet Factor V deficiency (1984). J. Clin. Invest. 74:1221-1228.
Tracy, PB, Eide LL and Mann KG: Human prothrombinase complex assembly and function on isolated peripheral blood cell populations (1985). J. Biol. Chem. 260:2119-2124.
Van De Water L, Tracy PB, Aronson D, Mann KG and Dvorak HF: Tumor cell generation of thrombin via functional prothrombinase assembly (1985). Cancer Res. 45:5521-5525.
Viskup RW, Tracy PB and Mann KG: The isolation of human platelet factor V (1987). Blood 69:1188-1195.
Visser MR, Tracy PB, Vercellotti GM, Goodman JL and Jacob HS: Enhanced thrombin generation and platelet adhesion on Herpes Simplex Virus-infected endothelium (1988). Proc. Natl. Acad. Sci., USA 85:8227-8230.
Solymoss S, Tucker MM and Tracy PB: Kinetics of inactivation of membrane-bound factor Va by activated protein C: Protein S modulates factor Xa protection (1988). J. Biol. Chem. 263:14884-14890.
Monkovic DD and Tracy PB: Activation of human factor V by factor Xa and thrombin (1990). Biochemistry29:1118-1128.
Monkovic DD and Tracy PB: Functional characterization and activation of human platelet released factor V by factor Xa and thrombin (1990). J. Biol. Chem.265:17132-17140.
Branda RF and Tracy PB: Effects of nutritional folate deficiency on the adhesive properties of murine melanoma cells (1990). Cancer Letts. 55:95-102.
Mulhare PE, Tracy PB, Golden EA, Branda RF and Bovill EG: A case of acquired factor X deficiency with "in vivo" and "in vitro" evidence of inhibitor activity directed against factor X (1991). Am. J. Clin. Path.96:196-200.
Robinson RA, Worfolk L and Tracy PB: Endotoxin enhances the expression of monocyte prothrombinase activity (1992). Blood 79:406-416.
Leong L, Henriksen RA, Kermode JC, Rittenhouse SE and Tracy PB: The thrombin high-affinity binding site on platelets is a negative regulator of thrombin-induced platelet activation. Structure-function studies using two mutant thrombins, Quick I and Quick II (1992). Biochemistry 31:2567-2575.
Worfolk LA, Robinson RA and Tracy PB: Factor Xa interacts with two sites on monocytes with different functional activities (1992). Blood 80:1989-1997.
Swords NA, Tracy PB and Mann KG: Intact platelet membranes, not platelet-released microvesicles, support the procoagulant activity of adherent platelets (1993). Arteriosclerosis & Thrombosis 13:1613-1622.
Hemric ME, Tracy PB and Haeberle JR: Caldesmon enhances the binding of myosin to the cytoskeleton during platelet activation (1994). J. Biol. Chem. 269:4125-4128.
Hayes KL, Leong L, Henriksen RA, Bouchard BA, Ouellette L, Church WR and Tracy PB: -Thrombin-induced human platelet activation results solely from formation of a specific enzyme substrate complex (1994). J. Biol. Chem. 269:28606-28612.
Allen DH and Tracy PB: Human coagulation factor V is activated to the functional cofactor by elastase and cathepsin G expressed at the monocyte membrane surface (1995). J. Biol. Chem. 270:1408-1415.
Camire RM, Kalafatis M, Cushman M, Tracy RP, Mann KG, and Tracy PB: The mechanism of inactivation of human platelet factor Va from normal and APC-resistant individuals (1995). J. Biol. Chem. 270:20794-20800.
Janeway CM, Rivard GE, Tracy PB and Mann KG: Factor V Revisited (1996). Blood87:3571-3578.
Bajzar L, Nesheim ME and Tracy PB: The profibrinolytic effect of activated protein C in clots formed from plasma is TAFI-dependent (1996). Blood 88:2093-2100.
Bajzar L, Kalafatis M, Simioni P and Tracy PB: An antifibrinolytic mechanism describing the prothrombotic effect associated with factor V Leiden (1996). J. Biol. Chem. 271:22949-22952.
Bouchard BA, Shatos MA and Tracy PB: Human brain pericytes differentially regulate the expression of procoagulant enzyme complexes comprising the extrinsic pathway of blood coagulation (1997). Arterioscler. Thromb. Vasc. Biol. 17: 1-9.
Bouchard BA, Catcher CS, Thrash BR, Adida C and Tracy PB: Effector cell protease receptor-1 (EPR-1), a platelet activation-dependent membrane protein regulates prothrombinase-catalyzed thrombin generation (1997). J. Biol. Chem., 272:9244-9251.
Tracy RP, Rubin DZ, Mann KG, Bovill EG, Rand M, Geffken D and Tracy PB: Thrombolytic therapy and proteolysis of factor V (1997). J. Am. Clin. Cardiol. 30: 716-724.
Schneider DJ, Tracy PB, Mann KG and Sobel BE: Differential effects of anticoagulants on the activation of platelets ex vivo and their implications for treatment (1997). Circulation 96:2877-2883.
Henriksen RA, Samokhin GP and Tracy PB: Thrombin-induced thromboxane synthesis by human platelets: Properties of an anion binding exosite I - independent receptor (1997). Arterioscler. Thromb. Vasc. Biol.17:3519-3526.
Bajzar L, Nesheim ME, and Tracy PB: Both cellular and soluble forms of thrombomodulin inhibit fibrinolysis by potentiating the activation of thrombin-activable fibrinolysis inhibitor (1998). J. Biol. Chem. 273:2792-2798.
Moyer MP, Tracy RP, Tracy PB, van’t Veer C, Sparks CE, and Mann, KG: Plasma lipoproteins support prothrombinase and other procoagulant enzymatic complexes (1998). Arterioscler. Thromb. Vasc. Biol., 18:458-465.
Camire RM, Kalafatis M, Simioni P, Girolami A, and Tracy PB: Platelet-derived factor Va and factor VaLeiden cofactor activity are sustained on the surface of activated platelets despite the presence of activated protein C (1998). Blood 91:2818-2829.
Larson PJ, Camire RM, Stanley TB, Wong D, Fasano NC, Monroe DM, Stafford DW, Tracy PB and High KA: Structure/function analyses of recombinant variants of human factor Xa: factor Xa incorporation into prothrombinase on the activated platelet surface is not mimicked by synthetic phospholipid vesicles (1998). Biochemistry, 37:5029-5038.
Larson PJ, Camire RM, Stanley TB, Wong D, Fasano NC, Monroe DM, Stafford DW, Tracy PB and High KA: Structure/function analyses of recombinant variants of human factor Xa: factor Xa incorporation into prothrombinase on the activated platelet surface is not mimicked by synthetic phospholipid vesicles (1998). Biochemistry, 37:5029-5038.
Camire RM, Kalafatis M and Tracy PB: Proteolysis of factor V by cathepsin G and elastase indicates that cleavage at Arg1545 optimizes cofactor function by facilitating factor Xa binding (1988). Biochemistry 37:11896-11906.
Camire RM, Pollak ES, Kaushansky K and Tracy PB: Secretable human platelet-derived factor V originates from the plasma pool (1998). Blood 92:3035-3041.
Hayes KL, and Tracy PB: The platelet high affinity binding site for thrombin mimics hirudin, modulates thrombin-induce platelet activation and is distinct from the glycoprotein Ib-IX-V complex (1999). J. Biol. Chem. 274:972-980.
Bouchard BA, Silveira JR and Tracy PB: On the role of EPR-1 or an EPR-1-like molecule in regulating factor Xa incorporation into Prothrombinase (2001). Thromb Haemost. 86:1133-1134.
Silveira JR, Kalafatis M and Tracy PB: Carbohydrate moieties on the procofactor factor V, but not the derived cofactor factor Va, regulate its inactivation by activated protein C (2002). Biochemistry 41:1672-1680.
Tracy PB: Role of platelets and leukocytes in coagulation. In: Hemostasis and Thrombosis: Basic Principles and Clinical Practice, 4th edition. RW Colman, J Hirsh, VJ Marder, AW Clowes and JN George, eds. Lippincott-Raven Publishers, Philadelphia, PA, pp 576-596 (2001)
Bouchard BA, Williams JL, Meisler NT, Long MW and Tracy PB: Endocytosis of plasma factor V by megakaryocytes occurs via a clathrin-dependent, receptor-mediated event. (2003) Submitted to J. Cell Biol
Gould WR, Simioni P, Silveira JR, Luni S and Tracy PB: Megakaryocytes endocytose and subsequently modify plasma-derived factor V to form the entire platelet-derived cofactor pool. (2003) Submitted to J Clin Invest.
Gould WR, Krishnaswamy S and Tracy PB: Intrinsic platelet prothrombinase is a unique protease that cannot be mimicked by kodel systems containing synthetic vesicles or plasma-derived factor Va. For submission to Biochemistry.
Sallam R, Bouchard BA and Tracy PB: Thrombin binds to a platelet membrane protein that is unique to protease activated receptor-1 and glycoprotein Ib. For submission to J Thromb Hemosta.
Invited Papers
Tracy PB, Peterson JM, Nesheim ME, McDuffie FC and Mann KG: Platelet interaction with bovine coagulation Factor V and Factor Va. In: The Regulation of Coagulation, Kenneth G. Mann and Fletcher B. Taylor, Jr., eds., Elsevier North-Holland, NY (1979), pp. 237-243.
Nesheim ME, Bloom JW, Tracy PB and Mann KG: The influence of bovine coagulation Factors V and Va on the function of "prothrombinase". Eighth Steenbock Symposium - Biosynthesis and Function of Vitamin K-dependent Proteins, University of Wisconsin, Madison, WI (1979).
Nesheim ME, Hibbard LS, Tracy PB, Bloom JW, Myrmel KH and Mann KG: Participation of Factor Va in prothrombinase. In: The Regulation of Coagulation, Kenneth G. Mann and Fletcher B. Taylor, Jr., eds., Elsevier North-Holland, NY (1979), pp. 145-159.
Mann KG, Nesheim ME, Hibbard LS and Tracy PB: The role of Factor V in the assembly of the prothrombinase complex. In: Annals of the NY Academy of Science, Vol. 370, Contributions to Hemostasis, Daniel A. Walz and Lowell E. McCoy, eds., New York Academy of Sciences, NY (1981), pp. 378-388.
Mann KG, Nesheim ME, Tracy PB, Hibbard LS and Bloom JW: Assembly of the prothrombinase complex (1982). Biophys. J. 37:106-107.
Mann KG, Tracy PB, and Nesheim ME: Assembly and function of the prothrominbase complex on synthetic and natural membranes. In: Interaction of platelets with the vessel wall (1985). American Physiological Society Reviews pp. 47-57.
Tracy PB, Eide LL and Mann KG: Abnormal formation of the prothrombinase complex - factor V deficiency and related disorders. In: Human Pathology, Part I, "Hemostasis: cellular and molecular pathology" J. Hawiger, ed. (1987) Vol. 18:162-169.
Tracy PB: Cellular involvement in coagulation. Workshop Report In: Proteases in Biological Control and Biotechnology, D.D. Cunningham and G.L. Long, eds., Alan R. Liss, Inc., New York (1987), pp. 249-253.
Mann KG, Odegaard BH, Krishnaswamy S, Tracy PB and Nesheim ME: Expression of blood clotting enzymes on natural and synthetic membranes. In: Proteases in Biological Control and Biotechnology, D.D. Cunningham and G.L. Long, eds., Alan R. Liss, Inc., New York (1987), pp. 235-248.
Mann KG, Tracy PB, Krishnaswamy S, Jenny RJ, Odegaard BH and Nesheim ME: Platelets and coagulation. In: Thrombosis and Hemastasis 1987, M. Verstraete, J. Vermylen, R. Lijnen and J. Arnout, eds., Leuven University Press, Leuven, Belgium (1987), pp. 505-523.
Tracy PB: Regulation of thrombin generation at cell surfaces (1988). Thromb. and Haemostasis 14:227-233.
Tracy PB, Allen DH, Worfolk LA, and Robinson-Lawler RA: Monocyte/macrophage regulation of coagulant events (1996). Hemostasis 26 (suppl 1):6-11.
Tracy RP and Tracy PB: Editorial: New views on the relationship of plasma lipids to cardiovascular disease (1997). Circulation 95:1347-1348.
Schneider DJ, Tracy PB and Sobel BE: Acute coronary syndromes: 1. The platelet’s role (1998). Hosp. Prac. 33(3):171-185.
Schneider DJ, Tracy PB and Sobel BE: Acute coronary syndromes: 2. Antiplatelet agents (1998). Hosp. Prac. 33(5):107-124.
Bouchard BA and Tracy PB: Platelets, leukocytes and coagulation (Review) (2001). Curr. Opin. Hematol. 8:263-269.
Bouchard BA and Tracy PB: Platelet regulation of thrombin generation in cardiovascular disease (Review) (2001). Ital. Heart J. 2:819-823.
Bouchard BA and Tracy PB: The participation of leukocytes in coagulant reactions (Review) (2003). J. Thromb. Haemost. 1:464-469.
Book Chapters
Nesheim ME, Katzmann JA, Tracy PB and Mann KG: Factor V (1982). Methods Enzymol. 80:249-274.
Tracy PB and Mann KG: A model for assembly of coagulation factor complexes on cell surfaces: Prothrombin activation on platelets. In: The Biology of Platelets, D.R. Phillips and M.A. Shuman, eds., Academic Press, New York, (1986) pp. 296-318.
Tracy PB and Mann KG: Platelet involvement in coagulation. In: Platelet Function and Metabolism, Vol. I, Holmsen, H., ed., CRC Press, Inc., New York (1986), pp. 297-324.
Mann KG, Nesheim ME and Tracy PB: Non-enzymatic cofactors: factor V. In: New Comprehensive Biochemistry, Vol. 13, "Blood Coagulation" R.F.A. Zwaal and H.C. Hemker, eds., Elsevier, New York (1986), pp. 15-34.
Tracy PB: The role of endothelium in the expression of procoagulant activity (1991). Coronary Artery Dis. 2:146-151.
Tracy PB, Nesheim ME, and Mann KG: The Platelet Factor Xa Receptor (1992). Methods Enzymol. 215:329-360.
Nesheim ME, Tracy RP, Tracy PB, Boskovic DS and Mann KG: Mathematical simulation of prothrombinase (1992). Methods Enzymol. 215:316-328.
Tracy PB, Robinson RA, Worfolk L and Allen DH: Procoagulant activities expressed by peripheral blood mononuclear cells (1993). Methods Enzymol. 222:281-299.
Jenny RJ, Tracy PB and Mann KG: The biochemistry and physiology of factor V. In: Haemostasis and Thrombosis, 3rd ed., A.L. Bloom, C.D. Forbes, D.P. Thomas and E.G.D. Tuddenham, eds., Churchill Livingstone, Edinburgh, UK (1993).
Tracy PB: Role of platelets and leukocytes in coagulation. In: Hemostasis and Thrombosis: Basic Principles and Clinical Practice, 4th edition. RW Colman, J Hirsh, VJ Marder, AW Clowes and JN George, eds. Lippincott-Raven Publishers, Philadelphia, PA , pp 576-596 (2001).
Bouchard BA, Butenas S, Mann KG and Tracy PB: Interactions between platelets and the coagulation system. In: Platelets. Michelson AD, ed. Academic Press, San Diego, CA, pp 229-253 (2002).
Gould WR, Silveira J and Tracy PB: Unique in vivo modifications of coagulation factor V produce a physically and functionally distinct platelet-derived cofactor: Characterization of purified platelet-derived factor V/Va (2003). J. Biol. Chem. In Press
Bouchard BA and Tracy PB: The participation of leukocytes in coagulant reactions (Review) (2003). J. Thromb. Haemost. 1:464-469.
Bouchard BA, Meisler NT, Nesheim ME, Liu C-X, Strickland DK and Tracy PB. (2008). A unique function for low-density lipoprotein receptor related protein-1 (LRP-1): A component of a two-receptor system mediating specific endocytosis of plasma-derived factor V by megakaryocytes. J Thromb Haemost. 6:638-644.
All Tracy Publications
Bouchard BA, Williams JL, Meisler NT, Long MW, Tracy PB. (2005). Endocytosis of plasma-derived factor V by megakaryocytes occurs via a clathrin-dependent, specific membrane binding event. J Thromb Haemost. 3:541-51.
Gould WR, Simioni P, Silveira JR, Tormene D, Kalafatis M, Tracy PB. (2005). Megakaryocytes endocytose and subsequently modify human factor V in vivo to form the entire pool of a unique platelet-derived cofactor. J Thromb Haemost. 3:450-6.
Gould WR, Silveira JR, Tracy PB. (2004). Unique in vivo modifications of coagulation factor V produce a physically and functionally distinct platelet-derived cofactor: characterization of purified platelet-derived factor V/Va. J Biol Chem. 279(4):2383-93.
Kleiman NS, Freedman J, Tracy PB, Furie BC, Bray PF, Phillips DR, Storey RF, Rusconi CP, French PA, Steinbuhl SR, and Becker RC (2008). Platelets: Developmental biology, physiology and translatable platforms for preclinical investigation and drug development. Platelets 19(4):239-251.
Ayombil F, Abdalla S, Tracy PB, Bouchard BA (2013) Proteolysis of plasma-derived factor V following its endocytosis by megakaryocytes forms the platelet-derived factor V/Va pool. J Thromb Haemost 11(8): 1532-9
Haynes LM, Bouchard BA, Tracy PB, Mann KG (2012) Prothrombin activation by platelet-associated prothrombinase proceeds through the prethrombin-2 pathway via a concerted mechanism. J Biol Chem 287(46): 38647-55.
Wood JP, Silveira JR, Maille NM, Haynes LM, Tracy PB (2011) Prothrombin activation on the activated platelet surface optimizes expression of procoagulant activity. Blood 117(5): 1710-8.
Fager AM, Wood JP, Bouchard BA, Feng P, Tracy PB (2010) Properties of procoagulant platelets: defining and characterizing the subpopulation binding a functional prothrombinase. Arterioscler Thromb Vasc Biol 30(12): 2400-7.
Kleiman NS, Freedman JE, Tracy PB, Furie BC, Bray PF, Rao SV, Phillips DR, Storey RF, Rusconi CP, French PA, Steinhubl SR, Becker RC (2008) Platelets: developmental biology, physiology, and translatable platforms for preclinical investigation and drug development. Platelets 19(4): 239-51.
Bouchard BA, Meisler NT, Nesheim ME, Liu CX, Strickland DK, Tracy PB (2008) A unique function for LRP-1: a component of a two-receptor system mediating specific endocytosis of plasma-derived factor V by megakaryocytes. J Thromb Haemost 6(4): 638-44.
Bouchard BA, Williams JL, Meisler NT, Long MW, Tracy PB (2005) Endocytosis of plasma-derived factor V by megakaryocytes occurs via a clathrin-dependent, specific membrane binding event. J Thromb Haemost 3(3): 541-51.
Gould WR, Simioni P, Silveira JR, Tormene D, Kalafatis M, Tracy PB. (2005) Megakaryocytes endocytose and subsequently modify human factor V in vivo to form the entire pool of a unique platelet-derived cofactor. J Thromb Haemost. 3:450-6.