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Pryzdial ELG, Meixner SC, Talbot K, Eltringham-Smith LJ, Baylis JR, Lee FMH, Kastrup CJ, Sheffield WP. Thrombolysis by chemically modified coagulation factor Xa. J Thromb Haemost 2016; 14:1844-54. [PMID: 27359348 PMCID: PMC5576980 DOI: 10.1111/jth.13402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 06/15/2016] [Indexed: 12/22/2022]
Abstract
UNLABELLED Essentials Factor Xa (FXa) acquires cleavage-mediated tissue plasminogen activator (tPA) cofactor activity. Recombinant (r) tPA is the predominant thrombolytic drug, but it may cause systemic side effects. Chemically modified, non-enzymatic FXa was produced (Xai-K), which rapidly lysed thrombi in mice. Unlike rtPA, Xai-K had no systemic fibrinolysis activation markers, indicating improved safety. SUMMARY Background Enzymatic thrombolysis carries the risk of hemorrhage and re-occlusion must be evaded by co-administration with an anticoagulant. Toward further improving these shortcomings, we report a novel dual-functioning molecule, Xai-K, which is both a non-enzymatic thrombolytic agent and an anticoagulant. Xai-K is based on clotting factor Xa, whose sequential plasmin-mediated fragments, FXaβ and Xa33/13, accelerate the principal thrombolytic agent, tissue plasminogen activator (tPA), but only when localized to anionic phospholipid. Methods The effect of Xai-K on fibrinolysis was measured in vitro by turbidity, thromboelastography and chromogenic assays, and measured in a murine model of occlusive carotid thrombosis by Doppler ultrasound. The anticoagulant properties of Xai-K were evaluated by normal plasma clotting assays, and in murine liver laceration and tail amputation hemostatic models. Results Xa33/13, which participates in fibrinolysis of purified fibrin, was rapidly inhibited in plasma. Cleavage was blocked at FXaβ by modifying residues at the active site. The resultant Xai-K (1 nm) enhanced plasma clot dissolution by ~7-fold in vitro and was dependent on tPA. Xai-K alone (2.0 μg g(-1) body weight) achieved therapeutic patency in mice. The minimum primary dose of the tPA variant, Tenecteplase (TNK; 17 μg g(-1) ), could be reduced by > 30-fold to restore blood flow with adjunctive Xai-K (0.5 μg g(-1) ). TNK-induced systemic markers of fibrinolysis were not detected with Xai-K (2.0 μg g(-1) ). Xai-K had anticoagulant activity that was somewhat attenuated compared with a previously reported analogue. Conclusion These results suggest that Xai-K may ameliorate the safety profile of therapeutic thrombolysis, either as a primary or tPA/TNK-adjunctive agent.
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Affiliation(s)
- E L G Pryzdial
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada.
| | - S C Meixner
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - K Talbot
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - L J Eltringham-Smith
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - J R Baylis
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - F M H Lee
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
| | - C J Kastrup
- Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - W P Sheffield
- Centre for Innovation, Canadian Blood Services, Ottawa, ON, Canada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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Pearson K, Jensen H, Kander T, Schött U. Desmopressinin vitroeffects on platelet function, monitored with Multiplate, ROTEM and Sonoclot. Scand J Clin Lab Invest 2016; 76:282-90. [DOI: 10.3109/00365513.2016.1149615] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Lehmann M, Wallbank AM, Dennis KA, Wufsus AR, Davis KM, Rana K, Neeves KB. On-chip recalcification of citrated whole blood using a microfluidic herringbone mixer. BIOMICROFLUIDICS 2015; 9:064106. [PMID: 26634014 PMCID: PMC4654733 DOI: 10.1063/1.4935863] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/02/2015] [Indexed: 05/20/2023]
Abstract
In vitro assays of platelet function and coagulation are typically performed in the presence of an anticoagulant. The divalent cation chelator sodium citrate is among the most common because its effect on coagulation is reversible upon reintroduction of divalent cations. Adding divalent cations into citrated blood by batch mixing leads to platelet activation and initiation of coagulation after several minutes, thus limiting the time blood can be used before spontaneously clotting. In this work, we describe a herringbone microfluidic mixer to continuously introduce divalent cations into citrated blood. The mixing ratio, defined as the ratio of the volumetric flow rates of citrated blood and recalcification buffer, can be adjusted by changing the relative inlet pressures of these two solutions. This feature is useful in whole blood assays in order to account for differences in hematocrit, and thus viscosity. The recalcification process in the herringbone mixer does not activate platelets. The advantage of this continuous mixing approach is demonstrated in microfluidic vascular injury model in which platelets and fibrin accumulate on a collagen-tissue factor surface under flow. Continuous recalcification with the herringbone mixer allowed for flow assay times of up to 30 min, more than three times longer than the time achieved by batch recalcification. This continuous mixer allows for measurements of thrombus formation, remodeling, and fibrinolysis in vitro over time scales that are relevant to these physiological processes.
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Affiliation(s)
- Marcus Lehmann
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Alison M Wallbank
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Kimberly A Dennis
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Adam R Wufsus
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Kara M Davis
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Kuldeepsinh Rana
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
| | - Keith B Neeves
- Chemical and Biological Engineering Department, Colorado School of Mines , Golden, Colorado 80401, USA
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Ragni MV, DiMichele DM, Hay CM, Malec LM, Seaman CD, Li J, Yabes JG, Butenas S, Brummel-Ziedins K. Thrombin generation and bleeding in haemophilia inhibitor patients during immune tolerance induction. Haemophilia 2015; 22:240-247. [PMID: 26517283 DOI: 10.1111/hae.12830] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/09/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND Inhibitor formation complicates haemophilia treatment and requires immune tolerance induction to rid inhibitors over 5 BU. In the prospective, randomized International Immune Tolerance Study, immune tolerance induction was equally effective with high-dose (HD) (200 IU kg-1 day-1 ) and low-dose (LD) (50 IU kg-1 3× per week) factor VIII, but haemorrhages were twofold higher in the LD arm. This finding was unexpected as inhibitors neutralize FVIII activity. We hypothesized that the thrombin generation assay (TGA), a global measure of clot formation, might predict bleeding better than FVIII levels. METHODS We evaluated TGA using relipidated tissue factor (TF) on 83 thawed, recalcified corn trypsin inhibitor/citrate plasma samples from 31 subjects (17 HD, 14 LD) who participated on the ITI study, and who had sufficient sample available and appropriate informed consent. RESULTS There were no significant differences in peak thrombin, estimated thrombin potential, maximum rate or lag time between HD and LD arms; between pre-, during and post-ITI time points, or after FVIII spiking. In 19 subjects (12 HD, 7 LD) with anti-FVIII<1.0 BU, the prevalence of non-neutralizing antibody (NNA) and neutralizing antibody (NA) was 89.5% (17/19), and the latter strongly correlated with anti-VIII titer, r = 0.73 [95% CI: 0.55, 0.88]. CONCLUSION In haemophilia inhibitor patients, thrombin generation is present, but does not predict bleeding risk. Following tolerance induction, NNA remains detectable in the majority.
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Affiliation(s)
- M V Ragni
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,Hemophilia Center of Western Pennsylvania, Pittsburgh, PA, USA
| | - D M DiMichele
- Division of Blood Diseases and Resources, National Heart Blood Lung Institute, Bethesda, MD, USA
| | - C M Hay
- Department of Hematology, Manchester University Royal Infirmary, Manchester, UK
| | - L M Malec
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - C D Seaman
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,Hemophilia Center of Western Pennsylvania, Pittsburgh, PA, USA
| | - J Li
- Department of Health Policy and Management, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - J G Yabes
- Center for Research on Health Care Data Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - S Butenas
- Department of Biochemistry, University of Vermont, Colchester, VT, USA
| | - K Brummel-Ziedins
- Department of Biochemistry, University of Vermont, Colchester, VT, USA
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Spronk HM, Cannegieter S, Morange P, Hackeng T, Huisman M, Nagler M, Posthuma J, Ninivaggi M, Zwaveling S, van der Hulle T, Scheres LJ, van Mens TE, Mackman N. Theme 2: Epidemiology, Biomarkers, and Imaging of Venous Thromboembolism (and postthrombotic syndrome). Thromb Res 2015; 136 Suppl 1:S8-S12. [DOI: 10.1016/j.thromres.2015.07.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Erber M, Lee G. Cryopellets based on amorphous organic calcium salts: Production, characterization and their usage in coagulation diagnostics. POWDER TECHNOL 2015. [DOI: 10.1016/j.powtec.2015.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Butenas S, Mann KG. The effect of corn trypsin inhibitor and inhibiting antibodies for FXIa and FXIIa on coagulation of plasma and whole blood: comment. J Thromb Haemost 2015; 13:487-8. [PMID: 25523109 PMCID: PMC4348199 DOI: 10.1111/jth.12812] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/04/2014] [Indexed: 11/30/2022]
Affiliation(s)
- S Butenas
- Department of Biochemistry, University of Vermont, Colchester, VT, USA
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Abstract
PURPOSE OF REVIEW There exists an imbalance between our understanding of the physiology of the blood coagulation process and the translation of this understanding into useful assays for clinical application. As technology advances, the capabilities for merging the two areas have become more attainable. Global assays have advanced our understanding of the dynamics of the blood coagulation process beyond end point assays and are at the forefront of implementation in the clinic. RECENT FINDINGS We will review recent advances in the main global assays with a focus on thrombin generation that have potential for clinical utility. These assays include direct (thrombogram, whole blood, purified systems) and indirect empirical measures of thrombin generation (thromboelastography) and mechanism-based computational models that use plasma composition data from individuals to generate thrombin generation profiles. SUMMARY Empirical thrombin generation assays (direct and indirect) and computational modeling of thrombin generation have greatly advanced our understanding of the hemostatic balance. Implementation of these types of assays and visualization approaches in the clinic will potentially provide a basis for the development of individualized patient care. Advances in both empirical and computational global assays have made the goal of predicting precrisis changes in an individual's hemostatic state one step closer.
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Response: the whole is greater than the sum of its parts: hemostatic profiles of whole-blood variants. J Trauma Acute Care Surg 2015; 77:1003-4. [PMID: 25423545 DOI: 10.1097/ta.0000000000000475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Hansson KM, Björkqvist J, Deinum J. The effect of recombinant and plasma-derived prothrombin on prothrombin time in human plasma. Int J Lab Hematol 2014; 37:357-64. [PMID: 25212252 DOI: 10.1111/ijlh.12293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 08/11/2014] [Indexed: 11/28/2022]
Abstract
INTRODUCTION When investigating coagulation assays to measure the effect of infused prothrombin (FII) in in vivo coagulopathy models, we found that addition of FII, plasma-derived human FII (pd-hFII) or recombinant human FII (r-hFII), to normal plasma resulted in a concentration-dependent increase in prothrombin time (PT) initiated with Innovin(®) . METHODS The effect on PT by addition to plasma of either pd-hFII or r-hFII, using different commercial PT reagents, was studied both by turbidimetry and viscometry. RESULT Addition of FII to plasma resulted in increased PT when initiated with Innovin(®) : PT increased with 20% by doubling the concentration. The prolongation of PT became more pronounced with 2-6000 times diluted Innovin(®) . However, by adjustment of the final free Ca(2+) concentration in the assay with diluted Innovin(®) from 8.3 to 1.3 mmol/L, no FII-dependent increase in PT was found. In contrast, no prolongation of PT was found with other commercial PT reagents. A KM = 3 nmol/L was obtained with pd-hFII, respectively, r-hFII with FII-depleted plasma using Thromborel(®) to initiate PT. CONCLUSION At normal plasma concentration of FII, addition of FII should not have an effect on PT. The prolonged PT with Innovin(®) , but not with other PT reagents, at supranormal FII concentration is an artefact.
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Affiliation(s)
- K M Hansson
- Department of Bioscience, CVMD iMED, AstraZeneca R&D Mölndal, Mölndal, Sweden
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Yan R, Colantonio D, Wong PY, Chen Y. Suitability of Becton Dickinson Vacutainer rapid serum tube for collecting and storing blood samples for antibiotic and anticonvulsant drug monitoring. J Clin Pathol 2014; 67:807-10. [DOI: 10.1136/jclinpath-2014-202466] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AimsTo investigate the suitability of newly developed Becton Dickinson Vacutainer rapid serum tube (RST) for therapeutic drug monitoring of antibiotics and anticonvulsants.MethodsTwo pools of citrated whole blood were created by spiking high and low concentrations of gentamicin, vancomycin, phenytoin, lamotrigine and carbamazepine. After recalcification with 15 mmol/L calcium chloride, spiked whole blood was added into four different Becton Dickinson blood collection tubes: RST, serum separator tube, red top tube and polyethylene plain tube. Serum aliquots were collected at baseline (0 h), 2 h, 24 h, day 3 and day 7. Drug concentrations were measured in batch by HPLC and the Architect c8000.ResultsGentamicin and vancomycin concentrations were stable up to 7 days in all 4 blood collection tubes. Anticonvulsants results for the RST were stable and did not deviate substantially from those of the red top and plain tubes, and demonstrated better performance than the serum separator tubes that showed significant (≥10% bias, p<0.05) decrease in phenytoin and carbamazepine levels after 3 days of storage.ConclusionsThe RST provides acceptable drug stability over the course of 7 days for gentamicin, vancomycin, phenytoin and lamotrigine and over 3 days for carbamazepine.
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Global Thrombosis Test (GTT) can detect major determinants of haemostasis including platelet reactivity, endogenous fibrinolytic and thrombin generating potential. Thromb Res 2014; 133:919-26. [PMID: 24613697 DOI: 10.1016/j.thromres.2014.02.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 12/09/2013] [Accepted: 02/19/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND Detection of both thrombosis and bleeding risk are essential in clinical cardiology. Thrombin generated by activated platelets and from the extrinsic coagulation pathway is the major determinant of thrombogenesis and hemostasis. Although novel oral anticoagulants further increase the bleeding risk of antiplatelet drugs, platelet function tests do not reliably predict hemorrhagic complications. It seems that in addition to platelet aggregation, true assessment of bleeding risks requires the measurement of both platelet and plasma derived thrombin activity. OBJECTIVE To adapt a novel, near-patient test for the assessment of both antithrombotic and anticoagulant effects of oral thrombin inhibitors. METHODS The point-of-care Global Thrombosis Test (GTT), which measures platelet reactivity to shear-activation in native blood, was used. Thrombin, generated from activated platelets (procoagulant activity) plays a pivotal role in GTT measurement. In order to assess endogenous thrombin potential, in a separate blood sample thrombin generation was induced by microparticles formed during hypotonic hemolysis. Thus two blood samples were tested to measure simultaneously platelet reactivity (occlusion time, OT) and hemolysis (microparticles)-induced endogenous thrombin potential (OT-H). RESULTS In healthy subjects (n=32), OT measured in native blood was reduced in hemolysed blood (100% vs. 43 ± 4%; OT vs. OT-H respectively). Shortening of OT in hemolysed blood (OT-H) was dose-dependently inhibited by the in vitro added thrombin inhibitor argatroban. In patients receiving dabigatran (n=27), OT and, to a lesser extent, OT-H was prolonged, compared to healthy volunteers. Intra-assay variation of OT-H was low (4.5%), but interindividual variation was great, both in healthy subjects (61%) and in patients on dabigatran (65%). Thrombin inhibitors argatroban, heparin (in vitro) and dabigatran (in vivo) all prolonged both OT and OT-H. There was no correlation between the measured OT and OT-H data. CONCLUSIONS Microparticles shed from erythrocytes during hypotonic lysis of native blood considerably shortened OT. In a direct proportion to the applied concentrations, various thrombin inhibitors prolonged both OT (antithrombotic effect) and to a lesser extent, OT-H (anticoagulant effect). Further large studies are required to evaluate the usefulness of this technique in a clinical setting, in assessing the anticoagulant and antithrombotic effects of medication and relating GTT results with observed thrombotic and bleeding events.
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A calcium-containing electrolyte-balanced hydroxyethyl starch (HES) solution is associated with higher factor VIII activity than is a non-balanced HES solution, but does not affect von Willebrand factor function or thromboelastometric measurements--results of a model of in vitro haemodilution. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2013; 12:260-8. [PMID: 24333074 DOI: 10.2450/2013.0096-13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 06/18/2013] [Indexed: 11/21/2022]
Abstract
BACKGROUND Hydroxyethyl starch (HES) is known to impair blood coagulation. The impact of calcium-containing, balanced carrier solutions of HES on coagulation is controversial. We investigated the effects of increasing degrees of haemodilution with modern 6%, electrolyte-balanced HES vs non-balanced HES on coagulation in vitro, and compared the balanced HES to a balanced crystalloid solution for an internal control. MATERIALS AND METHODS Blood samples from ten healthy volunteers were diluted in vitro by 20%, 40% and 60% with either calcium-containing balanced 130/0.42 HES, non-balanced 130/0.4 HES or balanced crystalloid. In all samples, blood counts, prothrombin time ratio, activated partial thromboplastin time, ionized calcium, factor VIII activity, von Willebrand factor antigen, von Willebrand factor collagen binding activity, and von Willebrand factor activity were determined, and activated rotational thromboelastometry (EXTEM and FIBTEM assays) was performed. RESULTS Haemodilution impaired coagulation in a dilution-dependent manner as determined by both conventional laboratory assays and thromboelastometry. Ionized calcium increased with balanced HES (p≤0.004), but decreased with non-balanced HES (p≤0.004). Prothrombin time ratio (p≤0.002) and factor VIII levels (p=0.001) were better preserved with balanced HES than with non-balanced HES in dilutions ≥40%. Thromboelastometry showed no differences between values in blood diluted with the balanced or non-balanced HES. DISCUSSION In vitro, a balanced calcium-containing carrier solution of 6% HES 130/0.42 preserved coagulation better than did non-balanced HES 130/0.4 as quantified by conventional coagulation assays, but not in activated thromboelastometry. One explanation could be the increased ionized calcium levels after dilution with calcium-containing carrier solutions.
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Kusch M, Grundmann C, Keitel S, König H. Factor VIII assay mimicking in vivo coagulation conditions. Haemophilia 2013; 20:e164-70. [PMID: 24286249 DOI: 10.1111/hae.12333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2013] [Indexed: 11/30/2022]
Abstract
Under certain circumstances, the determination of coagulation factor VIII (FVIII) is hampered by assay discrepancies between clotting and chromogenic approaches. These are observed in certain patients' plasma as well as in certain concentrates. We intended to develop a novel assay for the quantification of coagulation FVIII which reflects the physiological situation better than the established assays. It is based on plasma without chelation of divalent cations and simultaneously minimizes the generation of activated factors which could function as uncontrolled triggers of coagulation. FVIII deficient plasma is prepared with the aid of biotinylated antibodies against FVIII from normal plasma in presence of inhibitors of contact activation. To start the assay only tiny amounts of activated FIX serve as trigger. The FVIII determination is performed in a kinetic experiment and is based on the cleavage of a fluorogenic substrate for activated FX. FVIII concentrations between 0.01 and 1 IU mL(-1) are easily determined. Plasma-derived and recombinant FVIII concentrates were compared. All plasma-derived concentrates were found to contain FVIII activities within the specification of the manufacturer. Recombinant concentrates yielded only 35-50% of the claimed potency. The novel in vivo-like assay avoids the undue advantage or disadvantage of certain product characteristics by eliminating unphysiological assay conditions. Its usefulness could turn out in future experiments with plasma from haemophilia A patients.
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Affiliation(s)
- M Kusch
- Department of Haematology and Transfusion Medicine, Paul Ehrlich Institute, Langen, Germany
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Nwose EU, Richards RS, Digban K, Bwititi PT, Ennis G, Yee KC, Oguoma VM, Liberato S. Cardiovascular risk assessment in prediabetes and undiagnosed diabetes mellitus study: international collaboration research overview. NORTH AMERICAN JOURNAL OF MEDICAL SCIENCES 2013; 5:625-30. [PMID: 24404539 PMCID: PMC3877434 DOI: 10.4103/1947-2714.122303] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The study aims to develop a screening protocol for the risk of future cardiovascular disease and diabetes mellitus in people with prediabetes and undiagnosed diabetes; and to establish a framework for early identification and intervention of prediabetes including strategies for holistic management and monitoring of progression. The first phase is to identify prediabetes and undiagnosed diabetes in volunteers who are ≥18-years-old for 5 years. Point-of-care testing and questionnaire will be used to screen for prediabetes and cardiovascular disease. We anticipate screening more than 2000 individuals of both genders by the end of first phase. The second and third phases which shall run for 5-10 years will be longitudinal study involving participants identified in the first phase as having prediabetes without dyslipidaemia, or clinically established cardiovascular disease. The second phase shall focus on preventive management of risk of progress to diabetes with explicit diagnosis of cardiovascular disease. Oxidative stress measurements will be performed cum evaluation of the use of antioxidants, exercise, and nutrition. The third phase will include probing the development of diabetes and cardiovascular disease. Binomial logistic regression would be performed to generate and propose a model chart for the assessment of cardiovascular disease risk in prediabetes.
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Affiliation(s)
| | | | - Kester Digban
- Public Health Department, Novena University, Ogume, Delta State, Nigeria
| | | | | | | | | | - Selma Liberato
- Menzies School of Health Research, Charles Darwin University, Darwin NT, Australia
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Nwose EU, Bwititi PT, Chalada MJ. Reactive nitrogen and oxygen species in anticoagulated blood of healthy sheep. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2013; 7:427-33. [PMID: 23805984 DOI: 10.1517/17530059.2013.808187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Little or no study has been done to compare the indices of 'nitrosative' and 'oxidative' stresses, especially in terms of correlation and the possible differential effects of the chelating agents. OBJECTIVE This preliminary study investigated possible correlations between the indices of reactive nitrogen species (RNS) and reactive oxygen species (ROS) in blood, effect of anticoagulated-blood tubes, and impact of blood-clotting pathways. METHODS Thirty blood samples from sheep were collected into ethylenediamine tetraacetic acid (EDTA) and citrate tubes at the Berrima Veterinary Laboratory using their standard protocol. Nitrosative and oxidative stress indices were then measured and correlation analyses performed. RESULTS The ROS and RNS indices were weakly correlated (r > 0.2; p < 0.05) with each other from the EDTA sample, but not from citrated blood. None of the nitrosative or oxidative stress biomarkers was significantly associated with changes in the prothrombin time. The activated partial thromboplastin time showed statistically significant association with some oxidative stress indices (catalase and malondialdehyde), but with none of the nitrosative stress indices. Further, all measured parameters were higher in EDTA than in citrate blood (p < 0.0001). CONCLUSION The choice of anticoagulated blood tube could affect the measures of nitrosative stress indices and may impact on the potential correlations between nitrosative versus oxidative stress biomarkers. Perhaps the suggestion that EDTA is better than citrate for hematological anticoagulant studies should be considered for nitrosative and oxidative stress studies.
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Affiliation(s)
- Ezekiel Uba Nwose
- Charles Darwin University, School of Psychological & Clinical Sciences, Darwin 0909, Australia.
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Whelihan MF, Mann KG. The role of the red cell membrane in thrombin generation. Thromb Res 2013; 131:377-82. [DOI: 10.1016/j.thromres.2013.01.023] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 11/30/2022]
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Ko RH, Ji L, Young G. A novel approach for detecting hypercoagulability utilizing thromboelastography. Thromb Res 2013; 131:352-6. [PMID: 23419411 DOI: 10.1016/j.thromres.2013.01.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/25/2012] [Accepted: 01/24/2013] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The thromboelastograph is a point-of-care, global hemostasis assay that measures the dynamics of clot formation, including physical properties, over time and is licensed for use in monitoring coagulation during complex surgical procedures. It has more recently been used as a research tool to investigate various bleeding and clotting disorders. Although attempts have been made to use thromboelastography to detect hypercoagulable states, thus far a consistent, reliable approach has not been discovered. The objective of this study was to develop a novel approach utilizing thromboelastography that is sensitive for detecting hypercoagulability. MATERIALS AND METHODS Healthy, adult volunteers provided blood samples that were subjected to pre-analytic modifications from standard thromboelastography methods with the goal of prolonging clot initiation and propagation times. The methods which resulted in the desired changes in a consistent and reliable manner utilized corn trypsin inhibitor, a contact pathway inhibitor, on unactivated blood samples. To demonstrate that these methods are sensitive to detecting hypercoagulability, increasing concentrations of recombinant human thrombin were added as a surrogate for hypercoagulability. RESULTS Our methods were able to consistently and statistically significantly change the baseline TEG parameters of R time, K time, and angle in the desired fashion. Additionally, these methods were able to detect increasing concentrations of thrombin. CONCLUSIONS We describe a novel approach in which thromboelastography is highly sensitive to detecting increasing concentrations of thrombin in vitro. Further studies are underway to determine if these methods will be sensitive for detecting hypercoagulable states in vivo.
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Affiliation(s)
- Richard H Ko
- Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, CA 90027, United States.
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69
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Neeves KB, Onasoga AA, Hansen RR, Lilly JJ, Venckunaite D, Sumner MB, Irish AT, Brodsky G, Manco-Johnson MJ, Di Paola JA. Sources of variability in platelet accumulation on type 1 fibrillar collagen in microfluidic flow assays. PLoS One 2013; 8:e54680. [PMID: 23355889 PMCID: PMC3552855 DOI: 10.1371/journal.pone.0054680] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/13/2012] [Indexed: 12/22/2022] Open
Abstract
Microfluidic flow assays (MFA) that measure shear dependent platelet function have potential clinical applications in the diagnosis and treatment of bleeding and thrombotic disorders. As a step towards clinical application, the objective of this study was to measure how phenotypic and genetic factors, as well as experimental conditions, affect the variability of platelet accumulation on type 1 collagen within a MFA. Whole blood was perfused over type 1 fibrillar collagen at wall shear rates of 150, 300, 750 and 1500 s−1 through four independent channels with a height of 50 µm and a width of 500 µm. The accumulation of platelets was characterized by the lag time to 1% platelet surface coverage (LagT), the rate of platelet accumulation (VPLT), and platelet surface coverage (SC). A cohort of normal donors was tested and the results were correlated to plasma von Willebrand factor (VWF) levels, platelet count, hematocrit, sex, and collagen receptors genotypes. VWF levels were the strongest determinant of platelet accumulation. VWF levels were positively correlated to VPLT and SC at all wall shear rates. A longer LagT for platelet accumulation at arterial shear rates compared to venous shear rates was attributed to the time required for plasma proteins to adsorb to collagen. There was no association between platelet accumulation and hematocrit or platelet count. Individuals with the AG genotype of the GP6 gene had lower platelet accumulation than individuals with the AA genotype at 150 s−1 and 300 s−1. Recalcified blood collected into sodium citrate and corn trypsin inhibitor (CTI) resulted in diminished platelet accumulation compared to CTI alone, suggesting that citrate irreversibly diminishes platelet function. This study the largest association study of MFA in healthy donors (n = 104) and will likely set up the basis for the determination of the normal range of platelet responses in this type of assay.
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Affiliation(s)
- Keith B. Neeves
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
- * E-mail: (KBN); (JADP)
| | - Abimbola A. Onasoga
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
| | - Ryan R. Hansen
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
| | - Jessica J. Lilly
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Diana Venckunaite
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Meghan B. Sumner
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Andrew T. Irish
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, United States of America
| | - Gary Brodsky
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Marilyn J. Manco-Johnson
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Jorge A. Di Paola
- Department of Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Aurora, Colorado, United States of America
- * E-mail: (KBN); (JADP)
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70
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Larsen OH, Stentoft J, Radia D, Ingerslev J, Sørensen B. Combination of recombinant factor VIIa and fibrinogen corrects clot formation in primary immune thrombocytopenia at very low platelet counts. Br J Haematol 2012; 160:228-36. [DOI: 10.1111/bjh.12118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 09/12/2012] [Indexed: 11/26/2022]
Affiliation(s)
| | - Jesper Stentoft
- Department of Haematology; Aarhus University Hospital; Aarhus; Denmark
| | - Deepti Radia
- Department of Haematology; Guy's and St Thomas' NHS Foundation Trust; London; UK
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71
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Prothrombin activation in blood coagulation: the erythrocyte contribution to thrombin generation. Blood 2012; 120:3837-45. [PMID: 22968460 DOI: 10.1182/blood-2012-05-427856] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prothrombin activation can proceed through the intermediates meizothrombin or prethrombin-2. To assess the contributions that these 2 intermediates make to prothrombin activation in tissue factor (Tf)-activated blood, immunoassays were developed that measure the meizothrombin antithrombin (mTAT) and α-thrombin antithrombin (αTAT) complexes. We determined that Tf-activated blood produced both αTAT and mTAT. The presence of mTAT suggested that nonplatelet surfaces were contributing to approximately 35% of prothrombin activation. Corn trypsin inhibitor-treated blood was fractionated to yield red blood cells (RBCs), platelet-rich plasma (PRP), platelet-poor plasma (PPP), and buffy coat. Compared with blood, PRP reconstituted with PPP to a physiologic platelet concentration showed a 2-fold prolongation in the initiation phase and a marked decrease in the rate and extent of αTAT formation. Only the addition of RBCs to PRP was capable of normalizing αTAT generation. FACS on glycophorin A-positive cells showed that approximately 0.6% of the RBC population expresses phosphatidylserine and binds prothrombinase (FITC Xa·factor Va). These data indicate that RBCs participate in thrombin generation in Tf-activated blood, producing a membrane that supports prothrombin activation through the meizothrombin pathway.
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72
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Gissel M, Orfeo T, Foley JH, Butenas S. Effect of BAX499 aptamer on tissue factor pathway inhibitor function and thrombin generation in models of hemophilia. Thromb Res 2012; 130:948-55. [PMID: 22951415 DOI: 10.1016/j.thromres.2012.08.299] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 08/02/2012] [Accepted: 08/14/2012] [Indexed: 11/26/2022]
Abstract
INTRODUCTION In hemophilia, thrombin generation is significantly suppressed due to decreased factor (F)X activation. Clinical studies and experiments with transgenic mice have suggested that the severity of hemophilia is substantially reduced by tissue factor pathway inhibitor (TFPI) deficiency. METHODS We evaluated the effect of TFPI antagonist aptamer BAX499 (formerly ARC19499) on TFPI function in purified systems and on thrombin generation and clot formation in plasma and blood. RESULTS BAX499 effectively neutralized TFPI inhibition of FXa and FXa dependent inhibition of TF/FVIIa by TFPI. BAX499 did not inhibit FXa or TF/FVIIa when used up to 500 nM. In the synthetic coagulation proteome with TFPI at its mean physiologic concentration, BAX499 at 1 - 10nM increased thrombin generation triggered with 5 pM relipidated TF in a concentration-dependent manner. In severe hemophilia A or B models using the synthetic coagulation proteome, the addition of BAX499 at 5 nM increased thrombin generation to the levels observed in normal control. Thrombin generation measured in induced hemophilia B plasma required ~100nM BAX499 to restore thrombin levels to those seen in untreated plasma. In induced hemophilia B whole blood, BAX499 repaired the clotting time but failed to appreciably impact the propagation phase of thrombin generation. CONCLUSION These data suggest that inhibition of TFPI by BAX499 may have potential for hemophilia treatment but requires further study in blood-based hemophilia systems.
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Affiliation(s)
- Matthew Gissel
- Department of Biochemistry, University of Vermont, Colchester, Vermont 05446, United States
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73
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McLean KC, Bernstein IM, Brummel-Ziedins KE. Tissue factor-dependent thrombin generation across pregnancy. Am J Obstet Gynecol 2012; 207:135.e1-6. [PMID: 22840726 DOI: 10.1016/j.ajog.2012.05.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 05/16/2012] [Accepted: 05/30/2012] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Normal pregnancy results in a prothrombotic state. Studies that have investigated the capacity of pregnant women to generate thrombin are limited. Our aim was to evaluate thrombin generation longitudinally from the preconception period, through pregnancy, and after pregnancy. STUDY DESIGN We evaluated young, healthy nulligravid women (n = 20) at 4 time points and compared the data with 10 control women at 2 time points. Coagulation was initiated with tissue factor in contact pathway inhibited plasma, and thrombin generation was determined in the presence of a fluorogenic substrate. RESULTS The maximum level and rate of thrombin generation increased during pregnancy; the highest level and rate occurred in late pregnancy compared with prepregnancy (P < .001). Subsequently, thrombin generation decreased in the postpregnancy samples that included maximum level, rate, and area under the curve (P < .001). CONCLUSION Our data provide evidence for an increase in tissue factor-dependent thrombin generation with pregnancy progression, followed by a return to prepregnancy thrombin levels.
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Affiliation(s)
- Kelley C McLean
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Fletcher Allen Health Care/University of Vermont, Burlington, USA
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74
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Gorczyca ME, Nair SC, Jilma B, Priya S, Male C, Reitter S, Knoebl P, Gilbert JC, Schaub RG, Dockal M, McGinness KE, Pabinger I, Srivastava A. Inhibition of tissue factor pathway inhibitor by the aptamer BAX499 improves clotting of hemophilic blood and plasma. J Thromb Haemost 2012; 10:1581-90. [PMID: 22632032 DOI: 10.1111/j.1538-7836.2012.04790.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Tissue factor pathway inhibitor (TFPI) is the major inhibitor of tissue factor-initiated coagulation, making it an interesting and novel therapeutic target in hemophilia treatment. The aptamer BAX499 (formerly ARC19499) is designed to improve hemostasis by specifically inhibiting TFPI. OBJECTIVES The aim of the study was to examine the concentration-dependent augmentation of clotting by BAX499. METHODS Whole blood clot formation was quantified by rotational thromboelastometry and thromboelastography, and thrombin generation in platelet-poor plasma was assessed with the calibrated automated thrombogram, in samples from patients with congenital hemophilia A (N=55) and B (N=11), patients with acquired hemophilia A (N=1), and healthy controls (N=37). RESULTS BAX499 significantly improved clotting of samples from hemophilic patients in a concentration-dependent manner, resulting in clotting profiles in samples from patients with severe hemophilia that were similar to those of healthy controls. CONCLUSION BAX499 improved ex vivo clotting parameters in blood and plasma from patients with hemophilia A and B with different severity of disease, and also in a patient with acquired hemophilia. These results further support the contention that anti TFPI strategies may be an effective treatment for hemophilic patients.
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Affiliation(s)
- M E Gorczyca
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
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75
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Affiliation(s)
- K G Mann
- Department of Biochemistry, University of Vermont, Colchester, VT 05446, USA.
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76
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Foley JH, Butenas S, Mann KG, Brummel-Ziedins KE. Measuring the mechanical properties of blood clots formed via the tissue factor pathway of coagulation. Anal Biochem 2012; 422:46-51. [PMID: 22266209 DOI: 10.1016/j.ab.2011.12.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 12/22/2011] [Accepted: 12/23/2011] [Indexed: 11/28/2022]
Abstract
Thrombelastography (TEG) is a method that is used to conduct global assays that monitor fibrin formation and fibrinolysis and platelet aggregation in whole blood. The purpose of this study was to use a well-characterized tissue factor (Tf) reagent and contact pathway inhibitor (corn trypsin inhibitor, CTI) to develop a reproducible thrombelastography assay. In this study, blood was collected from 5 male subjects (three times). Clot formation was initiated in whole blood with 5 pM Tf in the presence of CTI, and fibrinolysis was induced by adding tissue plasminogen activator (tPA). Changes in viscoelasticity were then monitored by TEG. In quality control assays, our Tf reagent, when used at 5 pM, induced coagulation in whole blood in 3.93 ± 0.23 min and in plasma in 5.12 ± 0.23 min (n=3). In TEG assays, tPA significantly decreased clot strength (maximum amplitude, MA) in all individuals but had no effect on clot time (R time). The intraassay variability (CVa<10%) for R time, angle, and MA suggests that these parameters reliably describe the dynamics of fibrin formation and degradation in whole blood. Our Tf reagent reproducibly induces coagulation, making it an ideal tool to quantify the processes that contribute to mechanical clot strength in whole blood.
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Affiliation(s)
- J H Foley
- Department of Biochemistry, University of Vermont, Burlington, Colchester, VT 05446, USA
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77
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Buys AV, Pretorius E. Comparing different preparation methods to study human fibrin fibers and platelets using TEM. Microsc Res Tech 2011; 75:801-6. [PMID: 22213217 DOI: 10.1002/jemt.21129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 10/31/2011] [Indexed: 11/08/2022]
Abstract
For the study of cellular ultrastructure, the sample needs to be stabilized by fixation, with the ultimate aim to preserve the native tissue organization and to protect the tissue against later stages of preparation. Chemical and freezing fixation are most used, and chemical fixation employs agents that permeate tissues and cells by diffusion and covalently bind with their major biochemical constituents to fix them. Most widely used chemical fixatives are aldehydes, e.g., formaldehyde and glutaraldehyde, which are noncoagulating, crosslinking agents. Cryofixation methods for ultrastructural studies are also popular, and high-pressure freezing immobilizes all cell constituents and arrests biological activity by removing the thermal energy from the system. In the current research, we used platelet-rich plasma (PRP) to study expansive fibrin fibers and platelet ultrastructure to compare the two fixation techniques. We also used thrombin and calcium chloride as a clotting agent to determine the technique most suitable for the formation of extensive fibrin networks. Chemically fixated fibrin fibers were more compact and condensed and also showed a banding pattern on longitudinal sections. High-pressure frozen samples were more dispersed while platelets fixated showed better preserved cellular membranes and organelle structure. PRP coagulated by addition of CaCl(2) showed blood platelets that are noticeably more activated compared with PRP; however, with thrombin, a sharp ultrastructure was seen. We conclude that PRP mixed with thrombin, and freeze substituted, is the most suitable method for the study of extensive fibrin fibers as well as platelets.
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Affiliation(s)
- Antoinette V Buys
- Unit of Microscopy and Microanalysis, University of Pretoria, Arcadia, South Africa
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78
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Brummel-Ziedins KE, Whelihan MF, Rivard GE, Butenas S. Activated protein C inhibitor for correction of thrombin generation in hemophilia A blood and plasma1. J Thromb Haemost 2011; 9:2262-7. [PMID: 21920012 DOI: 10.1111/j.1538-7836.2011.04504.x] [Citation(s) in RCA: 14] [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 Replacement therapy for hemophilic patient treatment is costly, because of the high price of pharmacologic products, and is not affordable for the majority of patients in developing countries. OBJECTIVE To generate and evaluate low molecular weight agents that could be useful for hemophilia treatment. METHODS Potential agents were generated by synthesizing specific inhibitors [6-(Lys-Lys-Thr-[homo]Arg)amino-2-(Lys[carbobenzoxy]-Lys[carbobenzoxy]-O-benzyl)naphthalenesulfonamide] (PNASN-1)] for activated protein C (APC) and tested in plasma and fresh blood from hemophilia A patients. RESULTS In the activated partial thromboplastin time-based APC resistance assay, PNASN-1 partially neutralized the effect of APC. In calibrated automated thrombography, PNASN-1 neutralized the effect of APC on thrombin generation in normal and congenital factor VIII-deficient plasma (FVIII:C < 1%). The addition of PNASN-1 to tissue factor-triggered (5 pm) contact pathway-inhibited fresh blood from 15 hemophilia A patients with various degrees of FVIII deficiency (FVIII:C < 1-51%) increased the maximum level of thrombin generated from 78 to 162 nm, which approached that observed in blood from a healthy individual (201 nm). PNASN-1 also caused a 47% increase in clot weight in hemophilia A blood. CONCLUSIONS Specific APC inhibitors compensate to a significant extent for FVIII deficiency, and could be used for hemophilia treatment.
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Mitrophanov AY, Reifman J. Kinetic modeling sheds light on the mode of action of recombinant factor VIIa on thrombin generation. Thromb Res 2011; 128:381-90. [DOI: 10.1016/j.thromres.2011.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 05/05/2011] [Accepted: 05/10/2011] [Indexed: 11/29/2022]
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Ragni MV. Rationale for a randomized controlled trial comparing two prophylaxis regimens in adults with severe hemophilia A: the Hemophilia Adult Prophylaxis Trial. Expert Rev Hematol 2011; 4:495-507. [PMID: 21939418 DOI: 10.1586/ehm.11.52] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A major goal of comprehensive hemophilia care is to prevent occurrence of bleeds by prophylaxis or regular preventive factor, one or more times weekly. Although prophylaxis is effective in reducing bleeding and joint damage in children, whether it is necessary to continue into adulthood is not known. The purpose of this article is to describe a Phase III randomized controlled trial to evaluate prophylaxis comparing two dose regimens in adults with severe hemophilia A. I hypothesize that adults with mature cartilage and joints are less susceptible to joint bleeds and joint damage, and that once-weekly recombinant factor VIII prophylaxis, with up to two rescue doses per week, is as effective as thrice-weekly prophylaxis in reducing bleeding frequency, but less costly and more acceptable, with higher quality of life. The ultimate goal of this project is to determine whether once-weekly prophylaxis is any worse than thrice-weekly prophylaxis in reducing joint bleeding frequency, while potentially utilizing less factor, at lower cost, leading to a better quality of life. This is an innovative concept, as it challenges the current paradigm of thrice-weekly prophylaxis in adults, which is based on dosing in children. Furthermore, this trial will assess interdose thrombin generation, a novel tissue factor-based assay of hemostasis, to determine if individualized thrombin generation can predict more individualized prophylaxis dosing, which would be practice changing.
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Affiliation(s)
- Margaret V Ragni
- University of Pittsburgh Medical Center, Department of Medicine, Division Hematology/Oncology, and Hemophilia Center of Western Pennsylvania, Pittsburgh, PA, USA.
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Koukos G, Sevigny L, Zhang P, Covic L, Kuliopulos A. Serine and metalloprotease signaling through PAR1 in arterial thrombosis and vascular injury. IUBMB Life 2011; 63:412-8. [PMID: 21557445 DOI: 10.1002/iub.465] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 03/10/2011] [Indexed: 12/22/2022]
Abstract
Thrombin-dependent platelet activation has been shown to be important in the setting of angioplasty and stenting, which may cause ischemic complications including acute myocardial infarction and death. Inhibitors of the high-affinity thrombin receptor, protease-activated receptor 1 (PAR1), are now being evaluated in clinical trials for safety and efficacy in patients with atherothrombotic disease. However, it is unknown whether chronic inhibition of PAR1 in these large patient populations will have beneficial or possibly adverse effects on other biologic processes involved in blood vessel homeostasis and the response to vascular injury. Most recently, PAR1 was found to be cleaved at a distinct site by matrix metalloprotease-1 (MMP-1) to create a longer tethered ligand, which activates a distinct spectrum of G protein pathways in platelets. The differential activation by serine proteases such as thrombin and the metalloprotease MMP-1, places the protease receptor PAR1 at the junction of two major protease classes critically involved in thrombosis, matrix remodeling, and the response to vascular injury.
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Affiliation(s)
- Georgios Koukos
- Hemostasis and Thrombosis Laboratory, Molecular Oncology Research Institute, Tufts Medical Center, Boston, MA 02111, USA
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82
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McMichael MA, Smith SA. Viscoelastic coagulation testing: technology, applications, and limitations. Vet Clin Pathol 2011; 40:140-53. [PMID: 21446994 DOI: 10.1111/j.1939-165x.2011.00302.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Use of viscoelastic point-of-care (POC) coagulation instrumentation is relatively new to veterinary medicine. In human medicine, this technology has recently undergone resurgence owing to its capacity to detect hypercoagulability. The lack of sensitive tests for detecting hypercoagulable states, along with our current understanding of in vivo coagulation, highlights the deficiencies of standard coagulation tests, such as prothrombin and partial thromboplastin times, which are performed on platelet-poor plasma. Viscoelastic coagulation analyzers can provide an assessment of global coagulation, from the beginning of clot formation to fibrinolysis, utilizing whole blood. In people, use of this technology has been reported to improve management of hemostasis during surgery and decrease usage of blood products and is being used as a rapid screen for hypercoagulability. In veterinary medicine, clinical use of viscoelastic technology has been reported in dogs, cats, foals, and adult horses. This article will provide an overview of the technology, reagents and assays, applications in human and veterinary medicine, and limitations of the 3 viscoelastic POC analyzers in clinical use.
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Affiliation(s)
- Maureen A McMichael
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
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83
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Thrombocytopenia affects plasmatic coagulation as measured by thrombelastography. Blood Coagul Fibrinolysis 2011; 21:389-97. [PMID: 20410815 DOI: 10.1097/mbc.0b013e328335d0e4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Thrombelastography (TEG) is used as a point-of-care test of hemostasis. Different components of the test tracing are considered to reflect various parts of the hemostatic system and to distinguish low platelet count, platelet dysfunction or both from lack of plasmatic coagulation factors. To analyze the influence of one single element of the coagulation system, namely the platelet count, we used TEG serially in patients with well documented transient thrombocytopenia. A total of 189 TEG analyses were performed from 16 patients with a hematological malignancy in remission, receiving consolidation courses of chemotherapy. TEG outcomes using unmanipulated and citrated blood samples at a median of 11 times (range 1-17) in the same patients during the decrease of platelet count in response to chemotherapy were compared with outcomes in 120 healthy adults from various age categories. We found a correlation (r = 0.7, P < 0.001) between TEG clot strength (maximum amplitude) and platelet count. Moreover, platelet count was correlated respectively with the initial rate of clot formation (reaction time and clotting time), the rate of clot growth (alpha angle), and also with maximum thrombus generation, time to maximum thrombus generation and total thrombus generation. We conclude that platelet count not only affects the strength of clot formation, as was expected, but also all other phases of plasmatic coagulation. Citration of the blood sample, aiming at easy storage of the material, masked some of the important biological parameters of coagulation.
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84
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Carrieri C, Galasso R, Semeraro F, Ammollo CT, Semeraro N, Colucci M. The role of thrombin activatable fibrinolysis inhibitor and factor XI in platelet-mediated fibrinolysis resistance: a thromboelastographic study in whole blood. J Thromb Haemost 2011; 9:154-62. [PMID: 20961395 DOI: 10.1111/j.1538-7836.2010.04120.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The resistance of platelet-rich thrombi to fibrinolysis is generally attributed to clot retraction and platelet PAI-1 release. The role of TAFI in platelet-mediated resistance to lysis is unclear. OBJECTIVE We investigated the contribution of TAFI to the antifibrinolytic effect of platelets in whole blood by thromboelastography. METHODS Platelet-poor (PP-WB, < 40 × 10(3) μL(-1) ) and platelet-rich (PR-WB, > 400 × 10(3) μL(-1) ) blood samples were obtained from normal human blood (N-WB, 150-220 × 10(3) μL(-1) ). Clot lysis time was measured by thromboelastography in recalcified blood supplemented with t-PA (100 ng mL(-1) ) and tissue factor (1:1000 Recombiplastin). RESULTS t-PA-induced lysis time increased in parallel with platelet concentration (up to 3-fold). Neutralization of TAFI, but not of PAI-1, shortened the lysis time by ∼ 50% in PR-WB and by < 10% in PP-WB. Accordingly, prothrombin F1+2 and TAFIa accumulation was greater in PR-WB than in PP-WB. A similar TAFI-dependent inhibition of fibrinolysis was observed when clot retraction was prevented by cytochalasin D or abciximab, or when platelet membranes were tested. Moreover, in blood with an intact contact system, platelet-mediated fibrinolysis resistance was attenuated by an anti-FXI but not by an anti F-XII antibody. Finally, platelets made the clots resistant to the profibrinolytic effect of heparin concentrations displaying a strong anticoagulant activity. CONCLUSIONS Our data indicate that TAFI activation is one major mechanism whereby platelets make clots resistant to fibrinolysis and underscore the importance of TAFI inhibitors as new antithrombotic agents.
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Affiliation(s)
- C Carrieri
- Department of Biomedical Sciences and Human Oncology, Section of General and Experimental Pathology, Aldo Moro University, Bari, Italy
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Dudek MM, Harris LF, Killard AJ. Evaluation of activated partial thromboplastin time (aPTT) reagents for application in biomedical diagnostic device development. Int J Lab Hematol 2010; 33:272-80. [PMID: 21118388 DOI: 10.1111/j.1751-553x.2010.01283.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The most commonly used test for monitoring heparin therapy is the activated partial thromboplastin time (aPTT). The response of available aPTT reagents to heparin varies significantly. The aim of this study was to highlight the differences between aPTT reagents stored in a dried format to select the most suitable formulations to be used for the development of point-of-care diagnostic devices used for monitoring of unfractionated heparin dose response. METHODS Ten reagents were analysed in terms of their performance in liquid and in dried form after storage for 24 h and 14 days. Performance was assessed by measurement of the clotting time (CT) as evidenced by the onset of thrombin formation using a chromogenic thrombin substrate in plasma samples activated with these formulations. RESULTS Reagents in all of the three forms tested (liquid, 24 h and 14 days) resulted in significant shortening of CTs in comparison with the nonactivated plasma CT. Liquids returned more rapid CTs in comparison with dried reagents. Most of the reagents were more sensitive to heparin in dried, rather than in liquid form. Dried reagents based on kaolin as a surface activator were notably more effective in achieving short CT than others, while dried reagents composed of silica and synthetic phospholipids were the most sensitive to heparin. CONCLUSION Two reagents, namely aPTT-SP and SynthASIL both of which are based on synthetic phospholipids and silica, were identified as promising candidates for incorporation into point-of-care diagnostic device platforms as dried reagents.
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Affiliation(s)
- M M Dudek
- Biomedical Diagnostics Institute, National Centre for Sensor Research, Dublin City University, Dublin, Ireland
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86
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Dunkel B, Chan D, Boston R, Monreal L. Association between Hypercoagulability and Decreased Survival in Horses with Ischemic or Inflammatory Gastrointestinal Disease. J Vet Intern Med 2010; 24:1467-74. [DOI: 10.1111/j.1939-1676.2010.0620.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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87
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Clot formation in canine whole blood as measured by rotational thromboelastometry is influenced by sample handling and coagulation activator. Blood Coagul Fibrinolysis 2010; 21:692-702. [DOI: 10.1097/mbc.0b013e32833e9c47] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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88
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Chatterjee MS, Denney WS, Jing H, Diamond SL. Systems biology of coagulation initiation: kinetics of thrombin generation in resting and activated human blood. PLoS Comput Biol 2010; 6. [PMID: 20941387 PMCID: PMC2947981 DOI: 10.1371/journal.pcbi.1000950] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 09/03/2010] [Indexed: 01/28/2023] Open
Abstract
Blood function defines bleeding and clotting risks and dictates approaches for clinical intervention. Independent of adding exogenous tissue factor (TF), human blood treated in vitro with corn trypsin inhibitor (CTI, to block Factor XIIa) will generate thrombin after an initiation time (Ti) of 1 to 2 hours (depending on donor), while activation of platelets with the GPVI-activator convulxin reduces Ti to ∼20 minutes. Since current kinetic models fail to generate thrombin in the absence of added TF, we implemented a Platelet-Plasma ODE model accounting for: the Hockin-Mann protease reaction network, thrombin-dependent display of platelet phosphatidylserine, VIIa function on activated platelets, XIIa and XIa generation and function, competitive thrombin substrates (fluorogenic detector and fibrinogen), and thrombin consumption during fibrin polymerization. The kinetic model consisting of 76 ordinary differential equations (76 species, 57 reactions, 105 kinetic parameters) predicted the clotting of resting and convulxin-activated human blood as well as predicted Ti of human blood under 50 different initial conditions that titrated increasing levels of TF, Xa, Va, XIa, IXa, and VIIa. Experiments with combined anti-XI and anti-XII antibodies prevented thrombin production, demonstrating that a leak of XIIa past saturating amounts of CTI (and not “blood-borne TF” alone) was responsible for in vitro initiation without added TF. Clotting was not blocked by antibodies used individually against TF, VII/VIIa, P-selectin, GPIb, protein disulfide isomerase, cathepsin G, nor blocked by the ribosome inhibitor puromycin, the Clk1 kinase inhibitor Tg003, or inhibited VIIa (VIIai). This is the first model to predict the observed behavior of CTI-treated human blood, either resting or stimulated with platelet activators. CTI-treated human blood will clot in vitro due to the combined activity of XIIa and XIa, a process enhanced by platelet activators and which proceeds in the absence of any evidence for kinetically significant blood borne tissue factor. Clotting of blood involves a series of reactions wherein at each step an inactive zymogen is converted to an active enzyme by the product of the previous step, sometimes in plasma and usually on efficient catalytic surfaces provided by the activating platelet. The protein Tissue Factor (TF) initiates this cascade when blood vessels are disrupted, but how this cascade is triggered in the absence of exogenous TF remains the subject of much debate. First, we validated a high throughput experimental system that allowed the noninvasive quantification of thrombin generation dynamics. Next, we showed that “contact activation,” despite use of the best available inhibitor (CTI) to prevent it, builds up enough autocatalytic strength to trigger coagulation without exogenous TF, particularly upon activated platelets. Further, we build an ODE based model to predict the stability of blood resulting from multiple perturbations with active enzymes at various physiologically realizable concentrations. Unlike existing models, we consider the dynamics of platelet activation on reaction rates due to phosphatiylserine exposure. The “Platelet-Plasma” model lays the groundwork for integration of coagulation reaction kinetics and donor specific descriptions of platelet function.
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Affiliation(s)
- Manash S. Chatterjee
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania. Philadelphia, Pennslyvania, United States of America
| | - William S. Denney
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania. Philadelphia, Pennslyvania, United States of America
| | - Huiyan Jing
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania. Philadelphia, Pennslyvania, United States of America
| | - Scott L. Diamond
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania. Philadelphia, Pennslyvania, United States of America
- * E-mail:
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89
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Evaluation of coagulation kinetics using thromboelastometry—methodologic influence of activator and test medium. Ann Hematol 2010; 89:1155-61. [DOI: 10.1007/s00277-010-0982-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 04/29/2010] [Indexed: 10/19/2022]
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90
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Maurissen LFA, Castoldi E, Simioni P, Rosing J, Hackeng TM. Thrombin generation-based assays to measure the activity of the TFPI-protein S pathway in plasma from normal and protein S-deficient individuals. J Thromb Haemost 2010; 8:750-8. [PMID: 20088940 DOI: 10.1111/j.1538-7836.2010.03743.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Protein S acts as a cofactor for full-length tissue factor pathway inhibitor (TFPI) in the downregulation of thrombin formation. OBJECTIVE To develop a functional test to measure the activity of the TFPI-protein S system in plasma. METHODS/PATIENTS Using calibrated automated thrombography, we quantified the activity of the TFPI-protein S system in plasma by measuring thrombin generation in the absence and presence of neutralizing antibodies against protein S or TFPI. Moreover, we designed an enzyme-linked immunosorbent assay (ELISA) to determine the level of full-length TFPI in plasma. The performance of these assays was examined in plasma from 85 normal individuals and from 35 members of protein S-deficient families. RESULTS The ratio of thrombin peaks determined in the absence and presence of anti-protein S antibodies (protein S ratio = 0.5 in normal plasma) is a measure of the TFPI cofactor activity of protein S, whereas the ratio of thrombin peaks determined in the absence and presence of anti-TFPI antibodies (TFPI ratio = 0.25 in normal plasma) is a measure of the overall activity of the TFPI-protein S system. Protein S and TFPI ratios were elevated in protein S-deficient individuals, indicating an impairment of the TFPI-protein S system. Both ratios correlated well with full-length TFPI levels, which were significantly lower in protein S-deficient patients than in normal family members. CONCLUSIONS Functional assays for the TFPI-protein S system and an ELISA for full-length TFPI were developed. These assays show that the activity of the TFPI-protein S anticoagulant pathway is impaired in individuals with congenital protein S deficiency.
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Affiliation(s)
- L F A Maurissen
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, the Netherlands
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91
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Can MM, Tanboğa İH, Türkyılmaz E, Karabay CY, Akgun T, Koca F, Tokgoz HC, Keles N, Ozkan A, Bezgin T, Ozveren O, Sonmez K, Sağlam M, Ozdemir N, Kaymaz C. The risk of false results in the assessment of platelet function in the absence of antiplatelet medication: Comparision of the PFA-100, multiplate electrical impedance aggregometry and verify now assays. Thromb Res 2010; 125:e132-7. [DOI: 10.1016/j.thromres.2009.11.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 10/22/2009] [Accepted: 11/06/2009] [Indexed: 11/16/2022]
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92
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Roeloffzen WWH, Kluin-Nelemans HC, Mulder AB, Veeger NJGM, Bosman L, de Wolf JTM. In Normal Controls, Both Age and Gender Affect Coagulability as Measured by Thrombelastography. Anesth Analg 2010; 110:987-94. [DOI: 10.1213/ane.0b013e3181d31e91] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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93
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Larsen OH, Ezban M, Persson E, Ingerslev J, Sørensen B. Artificial contact pathway activation masks the haemostatic potential of rFVIIa and NN1731 in thrombocytopenic whole blood. Br J Haematol 2010; 150:124-7. [DOI: 10.1111/j.1365-2141.2010.08170.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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94
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Olsson C, Olsson P, Rådegran K, Owall A. Intraoperative blood salvage and retransfusion from citrate treated wounds is safe and feasible. SCAND CARDIOVASC J 2010; 44:177-82. [PMID: 20141340 DOI: 10.3109/14017430903524904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Allogenic blood transfusions are associated with increased morbidity and mortality in surgical patients. The study objective was to investigate the feasibility and safety of intraoperative autotransfusion of unwashed shed whole blood using a novel method. DESIGN Twenty pigs were randomised to autotransfusion or crystalloid volume replacement. In two separate surgical wounds, the surfaces and 400 ml of shed blood were treated in situ with citrate, delivered with an equipment transforming suction to positive pressure. Central haemodynamics were monitored with a pulmonary artery catheter. Effects on oxygen-carrying capacity, formed blood elements, haemolysis, inflammation, metabolism, and coagulation were evaluated with biochemical analyses. RESULTS No clinically relevant adverse effects on haemodynamics were encountered, apart from a decrease in cardiac output and mixed venous saturation similar to that in control animals. Haemoglobin level was better preserved in the autotransfused group (97 vs. 86 g/L, p=0.0007). There were no major differences in biochemical variables and no macroscopic clot formation precluding autotransfusion. CONCLUSIONS The technique was safe and feasible for intraoperative blood salvage and autotransfusion. Haemodynamics and biochemical variables were similar to controls. The technique warrants further studies in humans, as it may contribute towards a reduction of allogenic blood transfusions.
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Affiliation(s)
- Christian Olsson
- Cardiothoracic Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
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95
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Bolliger D, Seeberger MD, Tanaka KA, Dell-Kuster S, Gregor M, Zenklusen U, Grapow M, Tsakiris DA, Filipovic M. Pre-analytical effects of pneumatic tube transport on impedance platelet aggregometry. Platelets 2009; 20:458-65. [DOI: 10.3109/09537100903236462] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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96
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Jüttner B, Brock J, Weissig A, Becker T, Studzinski A, Osthaus WA, Bornscheuer A, Scheinichen D. Dependence of platelet function on underlying liver disease in orthotopic liver transplantation. Thromb Res 2009; 124:433-8. [PMID: 19616824 DOI: 10.1016/j.thromres.2009.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 05/29/2009] [Accepted: 06/15/2009] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The purpose of the present study was to explore the platelet function during the perioperative period of orthotopic liver transplantation (OLT) due to the underlying liver disease. METHODS The blood coagulation parameters, platelet surface markers and the determination of platelet aggregation were analyzed in 34 patients who underwent OLT. Blood samples were drawn preoperatively, anhepatic, 10 min and 1 hour after reperfusion, 1 day, 3 and 7 days postoperatively. Conventional coagulation screens, thrombopoietin (TPO) serum levels, P-selectin, GPIIb/IIIa and GPIb binding sites on the surface of platelets as evaluated by flow cytometry and platelet aggregation response were measured. RESULTS Coagulation factors, maximum aggregation and rate of aggregation were significantly different before transplantation due to the underlying liver disease. Further we found a markedly depressed GPIIb/IIIa and P-selectin expression and a reduced rate of aggregation in all patients throughout the study. In contrast maximum aggregation of platelets was restored on the third day after reperfusion without intergroup differences and almost comparable to healthy controls. An inverse correlation was found between peripheral platelet count pre-transplantation and peak TPO concentrations one weak post-transplantation. CONCLUSIONS In the entire process of OLT, coagulation factors, maximum aggregation and rate of platelet aggregation depend on the surgical phases during transplantation and on the underlying liver disease. The data obtained in this study might contribute to a better understanding of the pathophysiology and assessment of bleeding risk in OLT.
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Affiliation(s)
- Björn Jüttner
- Department of Anesthesiology, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, Germany.
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97
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Brummel-Ziedins KE, Orfeo T, Rosendaal FR, Undas A, Rivard GE, Butenas S, Mann KG. Empirical and theoretical phenotypic discrimination. J Thromb Haemost 2009; 7 Suppl 1:181-6. [PMID: 19630796 PMCID: PMC3395063 DOI: 10.1111/j.1538-7836.2009.03426.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed an integrated approach that combines empirical and computational methodologies to define an individual's thrombin phenotype. We have evaluated the process of thrombin generation in healthy individuals and individuals with defined pathologies in order to develop general criteria relevant to assess an individual's propensity for hemorrhage or thrombosis. Three complementary hypotheses have emerged from our work: (i) compensation by the ensemble of other coagulation proteins in individuals with specific factor deficiencies can 'normalize' an individual's thrombin generation process and represents a rationale for their unexpected phenotype; (ii) individuals with clinically unremarkable factor levels may present thrombin generation profiles typical of individuals with hemostatic complications; and (iii) in some hemostatic disorders a specific pattern of expression of a small ensemble of coagulation factors may be sufficient to explain the overall phenotype.
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Affiliation(s)
- K E Brummel-Ziedins
- Department of Biochemistry, University of Vermont, Colchester, VT 05446, USA.
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98
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Fenger-Eriksen C, Tønnesen E, Ingerslev J, Sørensen B. Mechanisms of hydroxyethyl starch-induced dilutional coagulopathy. J Thromb Haemost 2009; 7:1099-105. [PMID: 19422451 DOI: 10.1111/j.1538-7836.2009.03460.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The biochemical mechanisms causing dilutional coagulopathy following infusion of hydroxyethyl starch 130/0.4 (HES) are not known in detail. OBJECTIVES To give a detailed biochemical description of the mechanism of coagulopathy following 30%in vivo dilution with HES, to present a systematic ex vivo test of various hemostatic agents, and to investigate the hypothesis that acquired fibrinogen deficiency constitutes the most important determinant of the coagulopathy. METHODS Dynamic whole blood clot formation assessed by thromboelastometry, platelet count, thrombin generation, and the activities of von Willebrand factor, coagulation factor II, FVII, FVIII, FIX, FX and FXIII were measured in 20 bleeding patients enrolled in a prospective clinical study investigating in vivo substitution of blood loss with HES up to a target level of 30%. Thromboelastometry parameters were further evaluated after ex vivo spiking experiments with fibrinogen, prothrombin complex concentrate (PCC), FXIII, activated recombinant FVIIa (rFVIIa), fresh frozen plasma, and platelets. RESULTS Hemodilution reduced maximum clot firmness (MCF), whereas whole blood clotting time (CT) and maximum velocity remained unaffected. All coagulation factor activities were reduced. Fibrinogen, FII, FXIII and FX activities decreased significantly below the levels expected from dilution. The endogenous thrombin potential was unchanged. Ex vivo addition of fibrinogen normalized the reduced MCF and increased the maximum velocity, whereas PCC, rFVIIa and platelets shortened the CT but showed no effect on the reduced MCF. CONCLUSIONS Acquired fibrinogen deficiency seems to be the leading determinant in dilutional coagulopathy, and ex vivo addition corrected the coagulopathy completely.
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Affiliation(s)
- C Fenger-Eriksen
- Department of Anaesthesiology, Centre for Haemophilia and Thrombosis, Aarhus University Hospital, Aarhus, Denmark.
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99
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Brummel-Ziedins KE, Whelihan MF, Gissel M, Mann KG, Rivard GE. Thrombin generation and bleeding in haemophilia A. Haemophilia 2009; 15:1118-25. [PMID: 19563500 DOI: 10.1111/j.1365-2516.2009.01994.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Haemophilia A displays phenotypic heterogeneity with respect to clinical severity. The aim of this study was to determine if tissue factor (TF)-initiated thrombin generation profiles in whole blood in the presence of corn trypsin inhibitor (CTI) are predictive of bleeding risk in haemophilia A. We studied factor(F) VIII deficient individuals (11 mild, 4 moderate and 12 severe) with a well-characterized 5-year bleeding history that included haemarthrosis, soft tissue haematoma and annual FVIII concentrate usage. This clinical information was used to generate a bleeding score. The bleeding scores (range 0-32) were separated into three groups (bleeding score groupings: 0, 0 and < or = 9.6, >9.6), with the higher bleeding tendency having a higher score. Whole blood collected by phlebotomy and contact pathway suppressed by 100 microg mL(-1) CTI was stimulated to react by the addition of 5 pM TF. Reactions were quenched at 20 min by inhibitors. Thrombin generation, determined by enzyme-linked immunosorbent assay for thrombin-antithrombin was evaluated in terms of clot time (CT), maximum level (MaxL) and maximum rate (MaxR) and compared to the bleeding score. Data are shown as the mean+/-SD. MaxL was significantly different (P < 0.001) between the groups: 504 +/- 114, 315 +/- 117 and 194 +/- 91 nM; with higher thrombin concentrations in the groups with lower bleeding scores. MaxR was higher in the groups with a lower bleeding score; 97 +/- 51, 86 +/- 60 and 39 +/- 16 nM min(-1) (P = 0.09). No significant difference was detected in CT among the groups, 5.6 +/- 1.3, 4.7 +/- 0.7 and 5.6 +/- 1.3 min. Our empirical study in CTI-inhibited whole blood shows that the MaxL of thrombin generation appears to correlate with the bleeding phenotype of haemophilia A.
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Affiliation(s)
- K E Brummel-Ziedins
- Department of Biochemistry, University of Vermont, College of Medicine, Colchester, VT 05446, USA.
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Trivedi V, Boire A, Tchernychev B, Kaneider NC, Leger AJ, O'Callaghan K, Covic L, Kuliopulos A. Platelet matrix metalloprotease-1 mediates thrombogenesis by activating PAR1 at a cryptic ligand site. Cell 2009; 137:332-43. [PMID: 19379698 DOI: 10.1016/j.cell.2009.02.018] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 12/01/2008] [Accepted: 02/05/2009] [Indexed: 11/19/2022]
Abstract
Matrix metalloproteases (MMPs) play important roles in normal and pathological remodeling processes including atherothrombotic disease, inflammation, angiogenesis, and cancer. MMPs have been viewed as matrix-degrading enzymes, but recent studies have shown that they possess direct signaling capabilities. Platelets harbor several MMPs that modulate hemostatic function and platelet survival; however their mode of action remains unknown. We show that platelet MMP-1 activates protease-activated receptor-1 (PAR1) on the surface of platelets. Exposure of platelets to fibrillar collagen converts the surface-bound proMMP-1 zymogen to active MMP-1, which promotes aggregation through PAR1. Unexpectedly, MMP-1 cleaves PAR1 at a distinct site that strongly activates Rho-GTP pathways, cell shape change and motility, and MAPK signaling. Blockade of MMP1-PAR1 curtails thrombogenesis under arterial flow conditions and inhibits thrombosis in animals. These studies provide a link between matrix-dependent activation of metalloproteases and platelet-G protein signaling and identify MMP1-PAR1 as a potential target for the prevention of arterial thrombosis.
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Affiliation(s)
- Vishal Trivedi
- Department of Medicine, Tufts University School of Medicine, Molecular Oncology Research Institute, Tufts Medical Center, 800 Washington Street, Boston, MA 02111, USA
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