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Gurbel PA, Becker RC, Mann KG, Steinhubl SR, Michelson AD. Platelet Function Monitoring in Patients With Coronary Artery Disease. J Am Coll Cardiol 2007; 50:1822-34. [PMID: 17980247 DOI: 10.1016/j.jacc.2007.07.051] [Citation(s) in RCA: 338] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 07/24/2007] [Accepted: 07/31/2007] [Indexed: 02/07/2023]
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Erdogan E, Bukys MA, Orfeo T, Mann KG, Kalafatis M. Identification of an inactivating cleavage site for alpha-thrombin on the heavy chain of factor Va. Thromb Haemost 2007; 98:998-1006. [PMID: 18000604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Previous studies of factor (F)Va inactivation on human umbilical vein endothelial cells have shown that alpha-thrombin cleaves the heavy chain near the COOH-terminus to produce a M(r) 97,000 fragment containing the NH(2)-terminal portion of the heavy chain and a M(r) 8,000 peptide containing the rest of the molecule. The alpha-thrombin cleavage appeared to occur between amino acid residues 586 and 654 of FV. This region contains a consensus sequence for alpha-thrombin cleavage located at residues 640-644 (S-S-P-R-S). To test the hypothesis that alpha-thrombin cleaves the FVa heavy chain at Arg(643) and to evaluate the functional importance of this cleavage for FVa inactivation, site-directed mutagenesis was used to create recombinant FV molecules with mutations R(643) --> Q (FV(R643Q)) and R(643) --> A (FV(R643A)). All recombinant molecules were purified to homogeneity and assayed for activity following extended activation with alpha-thrombin. Under similar experimental conditions, appearance of the M(r) 97,000 heavy chain fragment in the plasma and wild-type FVa molecules correlated with partial loss of cofactor activity, while following extended incubation of FV(R643Q) and FV(R643A) with alpha-thrombin no cleavage of the heavy chain at Arg(643) was detected and no presence of the M(r) 97,000 heavy-chain fragment was noticed. Further, no loss in cofactor activity was observed using these mutant recombinant FVa molecules. Our data demonstrate that cleavage of FVa at Arg(643) by alpha-thrombin results in a partially inactive cofactor molecule and provides for an activated protein C (APC)-independent anticoagulant effect of alpha-thrombin.
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Mann KG, Whelihan MF, Butenas S, Orfeo T. Citrate anticoagulation and the dynamics of thrombin generation. J Thromb Haemost 2007; 5:2055-61. [PMID: 17883701 DOI: 10.1111/j.1538-7836.2007.02710.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Sodium citrate has been used as an anticoagulant to stabilize blood and blood products for over 100 years, presumably by sequestering Ca(++) ions in vitro. Anticoagulation of blood without chelation can be achieved by inhibition of the contact pathway by corn trypsin inhibitor (CTI). OBJECTIVE To evaluate the influence of citrate anticoagulation on the performance of blood, platelet-rich and platelet-poor plasma assays. METHODS Blood was anticoagulated in three ways: by collection into citrate, CTI and citrate with CTI. Plasma was prepared using each anticoagulation regimen. Functional analyses included calibrated automated thrombography, thromboelastography, plasma clotting, the synthetic coagulation proteome and platelet aggregation. Coagulation reactions were initiated with tissue factor-phospholipid and Ca(++) (when indicated). RESULTS In all cases, citrate anticoagulation resulted in reaction dynamics significantly altered relative to blood or plasma stabilized with CTI alone. Subsequent experiments showed that calcium citrate itself impairs coagulation dynamics. CONCLUSION Coagulation analyses using blood that has been exposed to citrate and recalcified do not yield reliable depictions of the natural dynamics of blood coagulation processes.
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Butenas S, Mann KG. Caution in the interpretation of continuous thrombin generation assays. J Thromb Haemost 2007; 5:1084-5; author reply 1085-7. [PMID: 17355574 DOI: 10.1111/j.1538-7836.2007.02512.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Orfeo T, Butenas S, Brummel‐Ziedins KE, Mann KG. Predicting pharmacologic efficacy of anticoagulants. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a631-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Undas A, Brummel-Ziedins KE, Mann KG. Antithrombotic properties of aspirin and resistance to aspirin: beyond strictly antiplatelet actions. Blood 2007; 109:2285-92. [PMID: 17148593 PMCID: PMC1852201 DOI: 10.1182/blood-2006-01-010645] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Accepted: 04/27/2006] [Indexed: 12/19/2022] Open
Abstract
Aspirin is effective in the prevention of cardiovascular events in high-risk patients. The primary established effect of aspirin on hemostasis is to impair platelet aggregation via inhibition of platelet thromboxane A(2) synthesis, thus reducing thrombus formation on the surface of the damaged arterial wall. Growing evidence also indicates that aspirin exerts additional antithrombotic effects, which appear to some extent unrelated to platelet thromboxane A(2) production. Aspirin can reduce thrombin generation with the subsequent attenuation of thrombin-mediated coagulant reactions such as factor XIII activation. Aspirin also acetylates lysine residues in fibrinogen resulting in increased fibrin clot permeability and enhanced clot lysis as well as directly promoting fibrinolysis with high-dose aspirin. The variable effectiveness of aspirin in terms of clinical outcomes and laboratory findings, which has been termed aspirin resistance, may be related to these additional antithrombotic effects that are altered when associated with common genetic polymorphisms such as the Leu33Pro beta(3)-integrin or Val34Leu factor XIII mutations. However, the clinical relevance of these observations is still unclear. Elucidation of the actual impacts of aspirin other than antiaggregation effects could be important in view of the widespread use of this drug in the prevention of thrombotic manifestations of atherosclerosis.
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Afshar-Kharghan V, Agah R, Andrews RK, Aster RH, Atkinson B, Awtry EH, Bahou WF, Barnard MR, Bavry AA, Bayer AS, Becker RC, Bergmeier W, Berndt MC, Bhatt DL, Bizzaro N, Blajchman MA, Bouchard BA, Brass LF, Bray PF, Briggs C, Brill A, Bussel JB, Butenas S, Cattaneo M, Chong BH, Clemetson KJ, Clemetson JM, Coller BS, Crawford LE, de Groot PG, del Zoppo GJ, Dubois C, Eisert WG, FitzGerald GA, Francis JL, Freedman JE, Freedman J, Frelinger III A, Fries S, Furie BC, Furie B, Furman MI, García-Alonso Á, Goldschmidt PJ, Grosser T, Gurguis GN, Harrison P, Hartwig JH, Ike da YU, Israels SJ, Italiano JE, Jennings LK, Kaplan C, Karpatkin S, Keeling DM, Kimura Y, Kurkjian CD, Kuter DJ, Lambert MP, Lee DH, Levin J, Li QX, Li Z, Lind SE, Linden MD, Lopes NH, López JA, Loscalzo J, Ma YQ, Machin SJ, Mann KG, Mannucci PM, Maron BA, Masters CL, McCrae KR, McEver RP, Menart B, Michelson AD, Moake J, Murray N, Nardi MA, Newman DK, Newman PJ, Nierodzik ML, Nieuwland R, Novinska M, Nurden AT, Nurden P, Perrotta PL, Pesho MM, Plow EF, Poncz M, Poon MC, Prévost N, Rao AK, Rathore V, Reed GL, Rex S, Rinder CS, Rinder HM, Roberts I, Ruggeri ZM, Savage B, Savion N, Senis Y, Shattil SJ, Sixma JJ, Smith BR, Snyder EL, Sobel M, Stalker TJ, Steinhubl SR, Stratmann B, Sturk A, Sudo T, Tef feri AL, Tomlinson MG, Topol EJ, Tracy PB, Tschoepe D, Varon D, Vijayan KV, Wagner DD, Watson SP, White, II GC, White JG, McCabe White M, Wilcox DA, Woulfe DS, Yeaman MR, Zhu L. Contributors. Platelets 2007. [DOI: 10.1016/b978-012369367-9/50760-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brummel-Ziedins K, Whelihan MF, Ziedins EG, Mann KG. The Resuscitative Fluid You Choose May Potentiate Bleeding. ACTA ACUST UNITED AC 2006; 61:1350-8. [PMID: 17159676 DOI: 10.1097/01.ta.0000235525.64176.01] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Trauma is the leading cause of death in the younger population in the United States, frequently from the development of hemorrhagic shock. Controversy exists over the type of volume resuscitation for restoring hemodynamic stability that should be used in hemorrhagic shock. Little is known about how various resuscitative paradigms affect the coagulation cascade, which is essential to controlling hemorrhagic shock. METHODS We studied the effect of various resuscitative formulas on blood coagulation using a new model of whole blood in a controlled setting with corn trypsin inhibitor and a 5-pM stimulus of tissue factor. We investigated thrombin generation, fibrin formation, and platelet activation with four diluents: 0.9% NaCl (NS), lactated Ringer's solution (LR), 6% hydroxyethyl starch (HES), and 3% NaCl (HS), each from 0% to 75% blood dilution. Thrombin generation was measured periodically during a time course of 20 minutes in its complex with antithrombin III. Platelet activation and fibrinopeptide A (FPA) release were monitored in serum at a 20-minute time point. Fibrin clots were collected and weighed. RESULTS The coagulation markers (thrombin generation, platelet activation, and FPA release) were significantly different by dilution (p < 0.001 in all) and diluent by dilution (p < 0.001 in all). Thrombin generation, platelet activation, and FPA release decreased the least with the diluents NS and LR. LR caused the least amount of variation in thrombin generation over the dilution course. HS produced the most dramatic change in all of the markers; no coagulation was seen between 30% to 75% dilution (p < 0.05). HES produced greater decreases in thrombin generation and FPA release than NS and LR. Fibrin clot mass decreased with a 10% to 20% dilution for NS and LR, whereas stable fibrin mass did not decrease with the diluents HES and HS at 10% to 20% dilutions. At >30% dilutions, HS produced no stable clots and HES dramatically decreased clot formation by 61% and maintained this level. CONCLUSIONS LR and NS had the least effect on thrombin generation, clot formation, and platelet activation at various concentrations compared with HES and HS. This observational data suggests that volume expanders such as HES and HS may be detrimental in treatment of hemorrhagic shock.
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Undas A, Brummel-Ziedins KE, Potaczek DP, Stobierska-Dzierzek B, Bryniarski L, Szczeklik A, Mann KG. Atorvastatin and quinapril inhibit blood coagulation in patients with coronary artery disease following 28 days of therapy. J Thromb Haemost 2006; 4:2397-404. [PMID: 16907931 DOI: 10.1111/j.1538-7836.2006.02165.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND We evaluated the antithrombotic effects of statins and angiotensin-converting enzyme inhibitor (ACEI) drugs in patients with coronary artery disease (CAD). METHODS AND RESULTS Blood coagulation at the site of microvascular injury was assessed in 26 males with CAD before and after treatment with quinapril (10 mg day-1; n=13) or atorvastatin (40 mg day-1; n=13) for 4 weeks and an additional 4 weeks of combined therapy (quinapril+atorvastatin). Rates of prothrombin and factor V activation (FVa), fibrinogen (Fbg) cleavage and FVa inactivation showed that both quinapril and atorvastatin decreased the rates of: formation of thrombin B-chain (by 30.6%, P=0.007; and by 34.3%, P=0.003), formation of thrombin-antithrombin complexes (by 30.4%, P=0.0002; and by 40%, P=0.001), FV activation (by 19.1%, P=0.03; and by 21.8%, P=0.005) and Fbg depletion (by 29.2%, P=0.004; and by 32.7%, P=0.001). Atorvastatin alone accelerated FVa inactivation (P=0.005). A further 4 weeks of combined therapy enhanced most anticoagulant effects only when atorvastatin was added to quinapril. CONCLUSIONS In CAD patients, atorvastatin and quinapril slowed blood clotting at the site of microvascular injury after 28 days of therapy. Addition of atorvastatin to quinapril, but not quinapril to the statin, enhanced the anticoagulant effects. Our findings might help explain the reduced risk of myocardial infarction or stroke in patients treated with statins and/or ACEIs and the lack of clinical benefits from ACEI added to prior statin therapy in patients at cardiovascular risk.
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Butenas S, Orfeo T, Kalafatis M, Mann KG. Peptidomimetic inhibitors for activated protein C: implications for hemophilia management. J Thromb Haemost 2006; 4:2411-6. [PMID: 17059471 DOI: 10.1111/j.1538-7836.2006.02226.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Several clinical studies and experiments with transgenic mice have suggested that the severity of the bleeding phenotype in hemophilic patients is substantially reduced in association with impaired inactivation of factor (F) Va by activated protein C (APC) in the presence of the FV Leiden mutation. Experiments using a synthetic coagulation proteome model showed that the presence of FV Leiden significantly increased thrombin generation in the absence of FVIII or FIX. OBJECTIVE To test the effect of APC inhibition on thrombin generation in hemophilia. METHODS Prothrombinase and a synthetic coagulation proteome model of tissue factor-triggered thrombin generation were used. RESULTS Peptide-based APC inhibitors, which mimic the P4-P4' residues surrounding the APC cleavage site at Arg306 of FVa, were synthesized. These compounds are specific and reversible inhibitors of APC, with Ki values as low as 1-2 microM; most have insignificant affinity for FXa or thrombin. The affinity for APC is dependent upon the location and character of the protecting groups. Representatives of this group of compounds inhibit FVa inactivation by APC and prolong FVa functional activity in the prothrombinase complex. When evaluated in a synthetic coagulation proteome model, one inhibitor partially compensated for the absence of FVIII. CONCLUSIONS Synthetic APC inhibitors may be useful as adjuvants for hemophilia treatment.
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Abstract
The large number of conflicting reports on the presence and concentration of circulating tissue factor (TF) in blood generates uncertainties regarding its relevance to hemostasis and association with specific diseases. We believe that the source of these controversies lies in part in the assays used for TF quantitation. We have developed a highly sensitive and specific double monoclonal antibody fluorescence-based immunoassay and integrated it into the Luminex Multi-Analyte Platform. This assay, which uses physiologically relevant standard and appropriate specificity controls, measures TF antigen in recombinant products and natural sources including placenta, plasma, cell lysates and cell membranes. Comparisons of reactivity patterns of various full-length and truncated TFs on an equimolar basis revealed quantitative differences in the immune recognition of TFs by our antibodies in the order of TF 1-263 > 1-242 > 1-218 > placental TF. Despite this differential recognition, all TF species are quantifiable at concentrations < or = 2 pM. Using a calibration curve constructed with recombinant TF 1-263 and plasma from healthy individuals (n = 91), we observed the concentration of TF antigen in plasma to be substantially lower than that generally reported in the literature: TF antigen in plasma of 72 individuals (79%) was below 2 pM (quantitative limit of our assay); TF antigen levels between 2.0 and 5.0 pM could be detected in six individuals (7%); and in 14% (13 plasmas), the non-specific signal was higher than the specific signal, and thus TF levels could not be determined. These differential recognition patterns affect TF quantitation in plasma and should be considered when evaluating plasma TF-like antigen concentrations.
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Orfeo T, Brummel‐Ziedins KE, Butenas S, Mann KG. Simulating blood coagulation: the contribution of α2‐macroglobulin and α1‐antitrypsin. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a64-c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Mann KG, Brummel-Ziedins K, Orfeo T, Butenas S. Models of blood coagulation. Blood Cells Mol Dis 2006; 36:108-17. [PMID: 16500122 DOI: 10.1016/j.bcmd.2005.12.034] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 12/19/2005] [Indexed: 11/23/2022]
Abstract
Our research aims to provide quantitatively transparent, biologically realistic descriptions of the processes involved in hemostasis which will permit predictions of the behavior of the coagulation system in normal and pathologic states. We use four models of coagulation: (1) numerical approximations of the tissue factor (Tf) pathway of thrombin generation based upon mechanism and dynamics; (2) Tf activation of the "blood coagulation proteome" from isolated cells and proteins; (3) Tf activated contact pathway inhibited whole blood in vitro; and (4) blood shed from standardized microvascular wounds in vivo. The results from these models are integrated in interactive assessments aimed at achieving convergence of biochemical rigor and biological authenticity. Microvascular injury is the most biologically secure but least accessible to mechanistic study. Numerical models while quantitatively transparent are biologically limited. By the integrated analyses of all four models, we establish observations which require inclusion or discovery of new parameters to achieve mechanistically interpretable biological reality. Discoveries made in this fashion have included thrombin's role in the initiation phase, TFPI/ATIII/APC synergy interactions, rfVIIa in fVII deficiency, the roles of fVIII and fIX in the Tf reaction, and the cleavage of fIX by fXa membrane. Ideally, our results will provide descriptions which predict the behavior of the biological blood coagulation system under normal and pathologic conditions.
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Orfeo T, Butenas S, Brummel-Ziedins KE, Mann KG. The tissue factor requirement in blood coagulation. J Biol Chem 2005; 280:42887-96. [PMID: 16215234 PMCID: PMC1369052 DOI: 10.1074/jbc.m505506200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Formation of thrombin is triggered when membrane-localized tissue factor (TF) is exposed to blood. In closed models of this process, thrombin formation displays an initiation phase (low rates of thrombin production cause platelet activation and fibrinogen clotting), a propagation phase (>95% of thrombin production occurs), and a termination phase (prothrombin activation ceases and free thrombin is inactivated). A current controversy centers on whether the TF stimulus requires supplementation from a circulating pool of blood TF to sustain an adequate procoagulant response. We have evaluated the requirement for TF during the progress of the blood coagulation reaction and have extended these analyses to assess the requirement for TF during resupply ("flow replacement"). Elimination of TF activity at various times during the initiation phase indicated: a period of absolute dependence (<10 s); a transitional period in which the dependence on TF is partial and decreases as the reaction proceeds (10-240 s); and a period in which the progress of the reaction is TF independent (>240 s). Resupply of reactions late during the termination phase with fresh reactants, but no TF, yielded immediate bursts of thrombin formation similar in magnitude to the original propagation phases. Our data show that independence from the initial TF stimulus is achieved by the onset of the propagation phase and that the ensemble of coagulation products and intermediates that yield this TF independence maintain their prothrombin activating potential for considerable time. These observations support the hypothesis that the transient, localized expression of TF is sufficient to sustain a TF-independent procoagulant response as long as flow persists.
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Key Words
- at-iii, antithrombin iii
- edta, (ethylene-dinitrilo) tetraacetic acid
- fprck, d-phe-pro-argch2cl
- hepes, n-[2-hydroxyethyl]piperazine-n′-2—ethanesulfonic acid
- hbs, 20 mm hepes, 150 mm nacl, ph 7.4
- hspg, heparan sulfate proteoglycans pc, 1,2-dioleoyl-sn-glycero-3-phosphocholine
- ps, 1,2-dioleoyl-sn-3-glycero-3-[phospho-l-serine]
- pcps vesicles, single bilayer phospholipid vesicles composed of 75%pc and 25% ps
- peg, polyethylene glycol, average molecular weight = 8000
- tfpi, tissue factor pathway inhibitor
- tat, thrombin-antithrombin iii complex
- tf, tissue factor
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Undas A, Celinska-Löwenhoff M, Brummel-Ziedins KE, Brozek J, Szczeklik A, Mann KG. Simvastatin given for 3 days can inhibit thrombin generation and activation of factor V and enhance factor Va inactivation in hypercholesterolemic patients. Arterioscler Thromb Vasc Biol 2005; 25:1524-5. [PMID: 15980269 PMCID: PMC1298245 DOI: 10.1161/01.atv.0000168913.25278.38] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Rivard GE, Brummel-Ziedins KE, Mann KG, Fan L, Hofer A, Cohen E. Evaluation of the profile of thrombin generation during the process of whole blood clotting as assessed by thrombelastography. J Thromb Haemost 2005; 3:2039-43. [PMID: 16102110 PMCID: PMC1410193 DOI: 10.1111/j.1538-7836.2005.01513.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The objective of this study was to evaluate the possibility of linking the tracing of whole blood clotting in a thrombelastograph (TEG) hemostasis system with the generation of thrombin assessed by thrombin/antithrombin complex (TAT). Citrated whole blood containing corn trypsin inhibitor from volunteers was clotted in the presence of CaCl2 and tissue factor. Clotting was monitored with the eight channels of a TEG system. At different time points, the whole blood TEG reaction cups were kept in a cold quenching solution, centrifuged, and the supernatants were kept at -80 degrees C until assayed for TAT by ELISA. The total thrombus generation (TTG) was calculated from the first derivative of the TEG waveform and was compared with thrombin generation measured by TAT. The two vector values--the TAT thrombin generation data and the corresponding TEG TTG--were analyzed using Pearson correlation coefficients (r) and linear, non-linear and natural log (ln) transformation of TAT values for least-squares goodness-of-fit curves. The best least-squares fit is an exponential curve. Linearizing using the ln of the TAT thrombin generation variable produces the same r (0.94) as of the exponential curve. The prediction equation is y = 8.0465 + 0.0005x (P < or = 0.0001), where y is the TAT thrombin generation variable in the ln transformation and x is the TEG TTG variable. The high magnitude of r and the high significance of the prediction equation demonstrate the high efficacy of the prediction of TAT thrombin generation by the use of TEG TTG.
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Undas A, Brzezinska-Kolarz B, Brummel K, Musial J, Szczeklik A, Mann KG. Factor XIII Val34Leu polymorphism and gamma-chain cross-linking at the site of microvascular injury in healthy and coumadin-treated subjects. J Thromb Haemost 2005; 3:2015-21. [PMID: 16102108 PMCID: PMC1307169 DOI: 10.1111/j.1538-7836.2005.01509.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Fibrin (Fn) cross-linking by activated factor (F) XIII is essential for clot stability. In vitro, a common Leu34 polymorphism of the FXIIIA-subunit increases the rate of thrombin-mediated FXIII activation, but not cross-linking activity upon complete FXIII activation. The effect of FXIII Val34Leu polymorphism on fibrin(ogen) cross-linking in vivo when vascular injury triggers the blood coagulation has not been studied yet. Using quantitative immunoblotting with antibodies raised against FXIIIA-subunits, fibrinogen, and gamma-gamma-dimers, the rates of FXIIIA cleavage and fibrin(ogen) cross-link formation in the fluid phase of 30-s blood samples collected at the site of microvascular injury were compared in the Leu34-positive and -negative healthy individuals and patients on long-term oral anticoagulation. In addition to accelerated FXIII activation, in healthy subjects the presence of FXIII Leu34 allele was associated with increased soluble gamma-gamma-dimer formation by 40% (1355 +/- 17 microg L(-1) for Leu34 carriers vs. 804.3 +/- 17 microg L(-1) for Leu34 non-carriers; P = 0.028) at the site of microvascular injury. This solution phase effect was abolished in coumadin-treated patients (369.4 +/- 75.9 microg L(-1) for Leu34 carriers vs. 290.5 +/- 35.9 microg L(-1) for Leu34 non-carriers; P > 0.05). The present study indicates that the Leu34 allele affects soluble gamma-gamma-dimer formation in untreated individuals, but not in those receiving acenocoumarol. Our data may help elucidate the impact of the FXIII Val34Leu polymorphism on Fn cross-linking in vivo and its modulation by oral anticoagulants.
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Egorina EM, Sovershaev MA, Bjørkøy G, Gruber FXE, Olsen JO, Parhami-Seren B, Mann KG, Østerud B. Intracellular and surface distribution of monocyte tissue factor: application to intersubject variability. Arterioscler Thromb Vasc Biol 2005; 25:1493-8. [PMID: 15860742 PMCID: PMC1410195 DOI: 10.1161/01.atv.0000168413.29874.d7] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The high and low responder phenomenon describes individual differences in lipopolysaccharide (LPS)-induced monocyte tissue factor (TF) activity. We characterized patterns of intracellular accumulation, externalization, and shedding of TF in response to LPS in mononuclear cells (MNCs) from high responders (HRs) and low responders (LRs). METHODS AND RESULTS After 2 hours of LPS stimulation of whole blood, flow cytometry analyses revealed a larger population of TF-positive monocytes in HRs (32.0+/-3.5%) versus LRs (11.2+/-1.2%; P< or =0.05), along with a stronger mean fluorescence intensity of TF signal in HRs (7.1+/-0.5 arbitrary units [AU]) compared with LRs (5.4+/-0.4 AU; P< or =0.05). The LPS-treated blood of the HR group contained 2-fold more TF-positive microparticles than LRs. In-cell Western assay demonstrated higher intracellular accumulation of TF in mononuclear cells (MNCs) from LRs because LPS induced a 3.7-fold increase of total TF levels in LRs versus a 1.5-fold increase in HRs. In contrast, in response to LPS stimulation, MNCs from HRs exhibited a 4-fold induction of surface TF, whereas MNCs from LRs only had a minor increase in surface TF levels. CONCLUSIONS The higher availability of surface TF antigen on MNCs from HRs and TF-containing microparticles might make these individuals more susceptible to hypercoagulation.
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Abstract
The 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) reductase inhibitors (statins) have been shown to exhibit several vascular protective effects, including antithrombotic properties, that are not related to changes in lipid profile. There is growing evidence that treatment with statins can lead to a significant downregulation of the blood coagulation cascade, most probably as a result of decreased tissue factor expression, which leads to reduced thrombin generation. Accordingly, statin use has been associated with impairment of several coagulant reactions catalyzed by this enzyme. Moreover, evidence indicates that statins, via increased thrombomodulin expression on endothelial cells, may enhance the activity of the protein C anticoagulant pathway. Most of the antithrombotic effects of statins are attributed to the inhibition of isoprenylation of signaling proteins. These novel properties of statins, suggesting that these drugs might act as mild anticoagulants, may explain, at least in part, the therapeutic benefits observed in a wide spectrum of patients with varying cholesterol levels, including subjects with acute coronary events. The HMG-CoA reductase inhibitors (statins) have been shown to exhibit several vascular protective effects, including antithrombotic properties, that are not related to changes in lipid profile. Treatment with statins can lead to a significant downregulation of the blood coagulation cascade, most probably as a result of decreased tissue factor expression, which leads to reduced thrombin generation.
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Butenas S, Bouchard BA, Brummel-Ziedins KE, Parhami-Seren B, Mann KG. Tissue factor activity in whole blood. Blood 2004; 105:2764-70. [PMID: 15604222 DOI: 10.1182/blood-2004-09-3567] [Citation(s) in RCA: 214] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tissue factor (TF) is an integral membrane protein essential for hemostasis. During the past several years, a number of studies have suggested that physiologically active TF circulates in blood at concentrations greater than 30 pM either as a component of blood cells and microparticles or as a soluble plasma protein. In our studies using contact pathway-inhibited blood or plasma containing activated platelets, typically no clot is observed for 20 minutes in the absence of exogenous TF. An inhibitory anti-TF antibody also has no effect on the clotting time in the absence of exogenous TF. The addition of TF to whole blood at a concentration as low as 16 to 20 fM results in pronounced acceleration of clot formation. The presence of potential platelet TF activity was evaluated using ionophore-treated platelets and employing functional and immunoassays. No detectable TF activity or antigen was observed on quiescent or ionophore-stimulated platelets. Similarly, no TF antigen was detected on mononuclear cells in nonstimulated whole blood, whereas in lipopolysaccharide (LPS)-stimulated blood a significant fraction of monocytes express TF. Our data indicate that the concentration of physiologically active TF in non-cytokine-stimulated blood from healthy individuals cannot exceed and is probably lower than 20 fM.
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