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Eptifibatide, an Older Therapeutic Peptide with New Indications: From Clinical Pharmacology to Everyday Clinical Practice. Int J Mol Sci 2023; 24:ijms24065446. [PMID: 36982519 PMCID: PMC10049647 DOI: 10.3390/ijms24065446] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023] Open
Abstract
Therapeutic peptides are oligomers or short polymers of amino acids used for various medical purposes. Peptide-based treatments have evolved considerably due to new technologies, stimulating new research interests. They have been shown to be beneficial in a variety of therapeutic applications, notably in the treatment of cardiovascular disorders such as acute coronary syndrome (ACS). ACS is characterized by coronary artery wall damage and consequent formation of an intraluminal thrombus obstructing one or more coronary arteries, leading to unstable angina, non-ST elevated myocardial infarction, and ST-elevated myocardial infarction. One of the promising peptide drugs in the treatment of these pathologies is eptifibatide, a synthetic heptapeptide derived from rattlesnake venom. Eptifibatide is a glycoprotein IIb/IIIa inhibitor that blocks different pathways in platelet activation and aggregation. In this narrative review, we summarized the current evidence on the mechanism of action, clinical pharmacology, and applications of eptifibatide in cardiology. Additionally, we illustrated its possible broader usage with new indications, including ischemic stroke, carotid stenting, intracranial aneurysm stenting, and septic shock. Further research is, however, required to fully evaluate the role of eptifibatide in these pathologies, independently and in comparison to other medications.
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Jiang S, Liu S, Lau S, Li J. Hemostatic biomaterials to halt non-compressible hemorrhage. J Mater Chem B 2022; 10:7239-7259. [DOI: 10.1039/d2tb00546h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Non-compressible hemorrhage is an unmet clinical challenge, which occurs in inaccessible sites in the body where compression cannot be applied to stop bleeding. Current treatments reliant on blood transfusion are...
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Nielsen VG, Wagner MT, Frank N. Mechanisms Responsible for the Anticoagulant Properties of Neurotoxic Dendroaspis Venoms: A Viscoelastic Analysis. Int J Mol Sci 2020; 21:ijms21062082. [PMID: 32197368 PMCID: PMC7139654 DOI: 10.3390/ijms21062082] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 03/13/2020] [Accepted: 03/16/2020] [Indexed: 12/12/2022] Open
Abstract
Using thrombelastography to gain mechanistic insights, recent investigations have identified enzymes and compounds in Naja and Crotalus species' neurotoxic venoms that are anticoagulant in nature. The neurotoxic venoms of the four extant species of Dendroaspis (the Black and green mambas) were noted to be anticoagulant in nature in human blood, but the mechanisms underlying these observations have never been explored. The venom proteomes of these venoms are unique, primarily composed of three finger toxins (3-FTx), Kunitz-type serine protease inhibitors (Kunitz-type SPI) and <7% metalloproteinases. The anticoagulant potency of the four mamba venoms available were determined in human plasma via thrombelastography; vulnerability to inhibition of anticoagulant activity to ethylenediaminetetraacetic acid (EDTA) was assessed, and inhibition of anticoagulant activity after exposure to a ruthenium (Ru)-based carbon monoxide releasing molecule (CORM-2) was quantified. Black mamba venom was the least potent by more than two orders of magnitude compared to the green mamba venoms tested; further, Black Mamba venom anticoagulant activity was not inhibited by either EDTA or CORM-2. In contrast, the anticoagulant activities of the green mamba venoms were all inhibited by EDTA to a greater or lesser extent, and all had anticoagulation inhibited with CORM-2. Critically, CORM-2-mediated inhibition was independent of carbon monoxide release, but was dependent on a putative Ru-based species formed from CORM-2. In conclusion, there was great species-specific variation in potency and mechanism(s) responsible for the anticoagulant activity of Dendroaspis venom, with perhaps all three protein classes-3-FTx, Kunitz-type SPI and metalloproteinases-playing a role in the venoms characterized.
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Affiliation(s)
- Vance G. Nielsen
- Department of Anesthesiology, University of Arizona College of Medicine, Tucson, AZ 85719, USA;
- Correspondence:
| | - Michael T. Wagner
- Department of Anesthesiology, University of Arizona College of Medicine, Tucson, AZ 85719, USA;
| | - Nathaniel Frank
- MToxins Venom lab LLC, 717 Oregon Street, Oshkosh, WI 54902, USA;
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Structure-guided design of pure orthosteric inhibitors of αIIbβ3 that prevent thrombosis but preserve hemostasis. Nat Commun 2020; 11:398. [PMID: 31964886 PMCID: PMC6972956 DOI: 10.1038/s41467-019-13928-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 12/06/2019] [Indexed: 02/07/2023] Open
Abstract
A prevailing dogma is that inhibition of vascular thrombosis by antagonizing platelet integrin αIIbβ3 cannot be achieved without compromising hemostasis, thus causing serious bleeding and increased morbidity and mortality. It is speculated that these adverse outcomes result from drug-induced activating conformational changes in αIIbβ3 but direct proof is lacking. Here, we report the structure-guided design of peptide Hr10 and a modified form of the partial agonist drug tirofiban that act as "pure" antagonists of αIIbβ3, i.e., they no longer induce the conformational changes in αIIbβ3. Both agents inhibit human platelet aggregation but preserve clot retraction. Hr10 and modified tirofiban are as effective as partial agonist drugs in inhibiting vascular thrombosis in humanized mice, but neither causes serious bleeding, establishing a causal link between partial agonism and impaired hemostasis. Pure orthosteric inhibitors of αIIbβ3 may thus provide safer alternatives for human therapy, and valuable tools to probe structure-activity relationships in integrins.
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Hong JK, Gao L, Singh J, Goh T, Ruhoff AM, Neto C, Waterhouse A. Evaluating medical device and material thrombosis under flow: current and emerging technologies. Biomater Sci 2020; 8:5824-5845. [DOI: 10.1039/d0bm01284j] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review highlights the importance of flow in medical device thrombosis and explores current and emerging technologies to evaluate dynamic biomaterial Thrombosis in vitro.
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Affiliation(s)
- Jun Ki Hong
- School of Chemistry
- The University of Sydney
- Australia
- School of Medical Sciences
- Faculty of Medicine and Health
| | - Lingzi Gao
- Heart Research Institute
- Newtown
- Australia
- The University of Sydney Nano Institute
- The University of Sydney
| | - Jasneil Singh
- Heart Research Institute
- Newtown
- Australia
- The Charles Perkins Centre
- The University of Sydney
| | - Tiffany Goh
- Heart Research Institute
- Newtown
- Australia
- The Charles Perkins Centre
- The University of Sydney
| | - Alexander M. Ruhoff
- Heart Research Institute
- Newtown
- Australia
- The Charles Perkins Centre
- The University of Sydney
| | - Chiara Neto
- School of Chemistry
- The University of Sydney
- Australia
- The University of Sydney Nano Institute
- The University of Sydney
| | - Anna Waterhouse
- School of Medical Sciences
- Faculty of Medicine and Health
- The University of Sydney
- Australia
- Heart Research Institute
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Dias JD, Lopez-Espina CG, Bliden K, Gurbel P, Hartmann J, Achneck HE. TEG®6s system measures the contributions of both platelet count and platelet function to clot formation at the site-of-care. Platelets 2019; 31:932-938. [PMID: 31878831 DOI: 10.1080/09537104.2019.1704713] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Knowledge of platelet count and function is key to ensuring appropriate hemostatic management. We hypothesized that the novel, portable TEG®6s coagulation assessment system could evaluate the contribution of both platelet count and function to clot formation. Whole-blood samples with variable platelet counts were prepared from healthy volunteers. Platelet function was adjusted using seven concentrations of abciximab and evaluated by light transmission aggregometry (LTA) with TRAP agonist. Maximum amplitude (MA), reaction time (R) and activated clotting time (ACT) were assessed in citrated kaolin (CK), CK with heparinase (CKH), citrated RapidTEG® (CRT), and citrated functional fibrinogen (CFF) assays. Positive correlations were observed between platelet count and CK.MA, CKH.MA, and CRT.MA (p < .0001), and CK.R, CKH.R, and CRT.ACT (p < .05). Platelet count could be accurately quantified in the range 28-91 k/μL, 28-86 k/μL and 28-74 k/μL for CK.MA, CKH.MA, and CRT.MA, respectively. CK.MA, CKH.MA, and CRT.MA showed significant negative relationships with abciximab concentration (p < .001). Platelet function inhibition was detected by all three assays at >68% measured by LTA and quantified in the range 68.4-82% (CK), 69.4-88% (CKH), and 69.7-76% (CRT). This demonstrates the TEG®6s analyzer can accurately evaluate platelet count and function at the site-of-care.
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Affiliation(s)
- Joao D Dias
- Clinical Development and Medical Affairs, Haemonetics Corporation , Signy, Switzerland
| | - Carlos G Lopez-Espina
- Clinical Development and Medical Affairs, Haemonetics Corporation , Rosemont, IL, USA
| | - Kevin Bliden
- Sinai Center for Thrombosis Research Sinai Hospital, 2401 W. Belvedere Ave, Baltimore MD 21215
| | - Paul Gurbel
- Sinai Center for Thrombosis Research Sinai Hospital, 2401 W. Belvedere Ave, Baltimore MD 21215
| | - Jan Hartmann
- Clinical Development and Medical Affairs, Haemonetics Corporation , Braintree, MA, USA
| | - Hardean E Achneck
- Clinical Development and Medical Affairs, Haemonetics Corporation , Braintree, MA, USA
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Chan V, Sarkari M, Sunderland R, St John AE, White NJ, Kastrup CJ. Platelets loaded with liposome-encapsulated thrombin have increased coagulability. J Thromb Haemost 2018; 16:1226-1235. [PMID: 29573326 DOI: 10.1111/jth.14006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Indexed: 02/02/2023]
Abstract
Essentials Platelet transfusions can have limited efficacy during hemorrhage associated with coagulopathy. Thrombin can be shielded by encapsulation into nanoliposomes and delivered to platelets ex vivo. Loading platelets with liposomal thrombin improved several aspects of platelet coagulability. Platelets loaded with liposomal thrombin can overcome some coagulopathic deficiencies in vitro. SUMMARY Background Platelets are integral to clot formation and are often transfused to stop or prevent bleeding. However, transfusions of platelets are not always effective, particularly in the most severe cases of hemorrhage. Nanoparticle systems have been developed to mimic platelets but inherently lack important aspects of platelet function, which limits their potential effectiveness. Objectives Increasing the natural coagulability of transfusable platelets could increase their efficacy during treatment of severe hemorrhage. Thrombin is a potent platelet agonist that currently cannot be used intravenously because of the risk of thrombosis. We hypothesized that delivery of thrombin to ex vivo platelets via liposomal encapsulation would enable transfusable platelets to become more coagulable in response to platelet agonists. Methods Thrombin was encapsulated into nanoliposomes and delivered to platelets ex vivo. Platelet coagulability was measured by monitoring platelet activation, clot contraction, clot time and clot stability in several in vitro assays. These parameters were also measured under conditions where coagulation is compromised, including during acidosis, antiplatelet drugs, hemophilia A and trauma-induced coagulopathy. Results Liposomal thrombin was endocytosed and used by platelets ex vivo but was not secreted upon activation. These modified platelets became more sensitive and responsive to agonists and improved clotting time even under conditions that normally cause platelet dysfunction or have impaired coagulation. Conclusions Several aspects of platelet function were enhanced by ex vivo delivery of liposomal thrombin.
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Affiliation(s)
- V Chan
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - M Sarkari
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - R Sunderland
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - A E St John
- Department of Emergency Medicine, University of Washington, Seattle, WA, USA
| | - N J White
- Department of Emergency Medicine, University of Washington, Seattle, WA, USA
| | - C J Kastrup
- Michael Smith Laboratories, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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Fluorinated Analog NMR s of Organosulfur Compounds from Garlic (Allium sativum): Synthesis, Chemistry and Anti-Angiogenesis and Antithrombotic Studies. Molecules 2017; 22:molecules22122081. [PMID: 29182588 PMCID: PMC6149718 DOI: 10.3390/molecules22122081] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 11/24/2017] [Indexed: 01/25/2023] Open
Abstract
We describe the synthesis, reactivity, and antithrombotic and anti-angiogenesis activity of difluoroallicin (S-(2-fluoroallyl) 2-fluoroprop-2-ene-1-sulfinothioate) and S-2-fluoro-2-propenyl-l-cysteine, both easily prepared from commercially available 3-chloro-2-fluoroprop-1-ene, as well as the synthesis of 1,2-bis(2-fluoroallyl)disulfane, 5-fluoro-3-(1-fluorovinyl)-3,4-dihydro-1,2-dithiin, trifluoroajoene ((E,Z)-1-(2-fluoro-3-((2-fluoroallyl)sulfinyl)prop-1-en-1-yl)-2-(2-fluoroallyl)disulfane), and a bis(2-fluoroallyl)polysulfane mixture. All tested organosulfur compounds demonstrated effective inhibition of either FGF or VEG-mediated angiogenesis (anti-angiogenesis activity) in the chick chorioallantoic membrane (CAM) or the mouse Matrigel® models. No embryo mortality was observed. Difluoroallicin demonstrated greater inhibition (p < 0.01) versus organosulfur compounds tested. Difluoroallicin demonstrated dose-dependent inhibition of angiogenesis in the mouse Matrigel® model, with maximal inhibition at 0.01 mg/implant. Allicin and difluoroallicin showed an effective antiplatelet effect in suppressing platelet aggregation compared to other organosulfur compounds tested. In platelet/fibrin clotting (anti-coagulant activity), difluoroallicin showed concentration-dependent inhibition of clot strength compared to allicin and the other organosulfur compounds tested.
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9
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Nielsen VG. Crotalus atrox
Venom Exposed to Carbon Monoxide Has Decreased Fibrinogenolytic Activity In Vivo
in Rabbits. Basic Clin Pharmacol Toxicol 2017; 122:82-86. [DOI: 10.1111/bcpt.12846] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 07/05/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Vance G. Nielsen
- Department of Anesthesiology; University of Arizona College of Medicine; Tucson AZ USA
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10
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Nielsen VG, Sánchez EE, Redford DT. Characterization of the Rabbit as an In Vitro and In Vivo Model to Assess the Effects of Fibrinogenolytic Activity of Snake Venom on Coagulation. Basic Clin Pharmacol Toxicol 2017; 122:157-164. [PMID: 28696521 DOI: 10.1111/bcpt.12848] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/05/2017] [Indexed: 12/16/2022]
Abstract
Several in vitro investigations have demonstrated that anticoagulant effects of fibrinogenolytic snake venom metalloproteinases have been abrogated in human plasma by modifying fibrinogen with iron (Fe) and carbon monoxide (CO) to prevent catalysis or by directly inhibiting these enzymes with CO. To translate these findings, we chose to assess the rabbit as a model of envenomation with Crotalus atrox venom. It was determined with thrombelastography that 15 times the concentration of venom noted to compromise coagulation in plasma in vitro was required to cause coagulopathy in vivo, likely secondary to venom binding to blood cells and being cleared from the circulation rapidly. Unlike human plasma, rabbit plasma pre-treated with Fe/CO was not protected from fibrinogenolysis by venom. Consequently, the administration of purified human fibrinogen (with or without Fe/CO) would be required before venom administration to rabbits. Of greater interest, venom exposed to CO had complete loss of fibrinogenolytic effect in rabbit plasma and partial loss of activity in whole blood, indicative of unbinding of CO from venom and binding to haemoglobin. Thus, venom exposed to CO could remain partially or completely inhibited in whole blood long enough for clearance from the circulation, allowing rabbits to be a useful model to test the efficacy of regional CO administration to the bite site. Future investigations are planned to test these novel approaches to attenuate venom-mediated coagulopathy in the rabbit.
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Affiliation(s)
- Vance G Nielsen
- The Department of Anesthesiology, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Elda E Sánchez
- National Natural Toxins Research Center and the Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, USA
| | - Daniel T Redford
- The Department of Anesthesiology, University of Arizona College of Medicine, Tucson, AZ, USA
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11
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Shore-Lesserson L. Evidence Based Coagulation Monitors: Heparin Monitoring, Thromboelastography, and Platelet Function. Semin Cardiothorac Vasc Anesth 2016; 9:41-52. [PMID: 15735843 DOI: 10.1177/108925320500900105] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The hemostatic management of patients undergoing cardiac surgery is a unique challenge. Since its inception, cardiopulmonary bypass (CPB) has required meticulous attention to maintaining adequate anticoagulation. New anticoagulants and alternative monitoring techniques present an opportunity to investigate potential advances in the area of anticoagulation for CPB. Hemostasis after CPB is still a vexing problem, and the addition of antiplatelet medication to the platelet defect already incurred during CPB has led to hemorrhagic complications in cardiac surgery. The two opposing processes of anticoagulation and hemostasis must be managed carefully and modified with respect to the patient's hematologic status and desired hemostatic outcome. Cardiac surgical patients consume a much larger fraction of perioperative blood transfusions than the percentage of the surgical population they represent. Thus, during CPB, careful attention must be paid to optimal anticoagulation, platelet quiescence, biocompatible circuitry and interventions, and to monitoring hemostasis. The multifactorial etiology of the CPB-induced hemostatic defect requires a multimodal approach to blood conservation and hemostasis monitoring, including heparin maintenance and sophisticated point-of-care hemostasis monitoring. Each technology has its own attributes and each may be suitable for different populations based upon the expected defects being measured. This article reviews the evidence supporting the use of point-of-care monitors in coagulation and hemostasis management in cardiac surgical patients.
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12
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Muralidharan-Chari V, Kim J, Abuawad A, Naeem M, Cui H, Mousa SA. Thymoquinone Modulates Blood Coagulation in Vitro via Its Effects on Inflammatory and Coagulation Pathways. Int J Mol Sci 2016; 17:474. [PMID: 27043539 PMCID: PMC4848930 DOI: 10.3390/ijms17040474] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 03/18/2016] [Accepted: 03/25/2016] [Indexed: 12/26/2022] Open
Abstract
Thymoquinone (THQ) is a major component of black seeds. Given that both THQ and black seeds exhibit anti-cancer and anti-inflammatory activities, we hypothesized that THQ will affect cancer-associated thrombosis (CAT), which is primarily triggered by tissue factor (TF) and inflammation. The effect of both black seed-extracted and purchased (“pure”) THQ on normal blood coagulation was tested with in vitro thromboelastography (TEG) and activated partial thromboplastin time (aPTT) coagulation assays. The effect of pure THQ on CAT was tested with aPTT assay using pancreatic cancer cell lines that are either positive or negative for TF, and with TEG assay using lipopolysaccharide as an inflammatory trigger. Additionally, the direct effect of THQ on the inactivation of factors IIa and Xa was assessed. Since TNF-α facilitates crosstalk between inflammation and thrombosis by triggering the NF-κB pathway, we tested THQ’s ability to interfere with this communication with a luciferase assay. Both extracted and pure THQ had minimal effects on normal blood coagulation. Pure THQ reversed CAT initiated by both TF and inflammation to basal levels (p < 0.001). Mechanistically, while THQ had minimal to no effect on factor IIa and Xa inactivation, it strongly reduced the effects of TNF-α on NF-κB elements (p < 0.001). THQ has a minimal effect on basal coagulation and can reverse CAT in vitro, possibly by interfering with the crosstalk between inflammation and coagulation. This study suggests the utility of THQ as a preventative anticoagulant and/or as a supplement to existing chemotherapies and anticoagulant therapies.
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Affiliation(s)
- Vandhana Muralidharan-Chari
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
| | - Jaehan Kim
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
| | - Ahlam Abuawad
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
| | - Mubeena Naeem
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
| | - Huadong Cui
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
| | - Shaker A Mousa
- The Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, 1 Discovery Drive, Rennselaer, NY 12144, USA.
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Hall CA, Lydon HL, Dalton CH, Chipman JK, Graham JS, Chilcott RP. Development of haemostatic decontaminants for the treatment of wounds contaminated with chemical warfare agents. 1: Evaluation ofin vitroclotting efficacy in the presence of certain contaminants. J Appl Toxicol 2014; 35:536-42. [DOI: 10.1002/jat.3019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/21/2014] [Accepted: 03/22/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Charlotte A. Hall
- CBRN & Chemical Toxicological Research Group, Centre for Radiation; Chemical and Environmental Hazards, Health Protection Agency; Chilton UK
- School of Biosciences; University of Birmingham; Birmingham UK
| | - Helen L. Lydon
- CBRN & Chemical Toxicological Research Group, Centre for Radiation; Chemical and Environmental Hazards, Health Protection Agency; Chilton UK
- School of Biosciences; University of Birmingham; Birmingham UK
| | - Christopher H. Dalton
- School of Biosciences; University of Birmingham; Birmingham UK
- Biomedical Sciences; Dstl Porton Down; Salisbury UK
| | - J. K. Chipman
- School of Biosciences; University of Birmingham; Birmingham UK
| | - John S. Graham
- Medical Toxicology Branch Analytical Toxicology Division; US Army Medical Research Institute of Chemical Defense; Aberdeen Proving Ground MD 21010 USA
| | - Robert P. Chilcott
- CBRN & Chemical Toxicological Research Group, Centre for Radiation; Chemical and Environmental Hazards, Health Protection Agency; Chilton UK
- Department of Pharmacy; University of Hertfordshire; Hatfield UK
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14
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Tran R, Myers DR, Ciciliano J, Trybus Hardy EL, Sakurai Y, Ahn B, Qiu Y, Mannino RG, Fay ME, Lam WA. Biomechanics of haemostasis and thrombosis in health and disease: from the macro- to molecular scale. J Cell Mol Med 2013; 17:579-96. [PMID: 23490277 PMCID: PMC3822810 DOI: 10.1111/jcmm.12041] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/24/2013] [Indexed: 11/28/2022] Open
Abstract
Although the processes of haemostasis and thrombosis have been studied extensively in the past several decades, much of the effort has been spent characterizing the biological and biochemical aspects of clotting. More recently, researchers have discovered that the function and physiology of blood cells and plasma proteins relevant in haematologic processes are mechanically, as well as biologically, regulated. This is not entirely surprising considering the extremely dynamic fluidic environment that these blood components exist in. Other cells in the body such as fibroblasts and endothelial cells have been found to biologically respond to their physical and mechanical environments, affecting aspects of cellular physiology as diverse as cytoskeletal architecture to gene expression to alterations of vital signalling pathways. In the circulation, blood cells and plasma proteins are constantly exposed to forces while they, in turn, also exert forces to regulate clot formation. These mechanical factors lead to biochemical and biomechanical changes on the macro- to molecular scale. Likewise, biochemical and biomechanical alterations in the microenvironment can ultimately impact the mechanical regulation of clot formation. The ways in which these factors all balance each other can be the difference between haemostasis and thrombosis. Here, we review how the biomechanics of blood cells intimately interact with the cellular and molecular biology to regulate haemostasis and thrombosis in the context of health and disease from the macro- to molecular scale. We will also show how these biomechanical forces in the context of haemostasis and thrombosis have been replicated or measured in vitro.
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Affiliation(s)
- Reginald Tran
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - David R Myers
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Jordan Ciciliano
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Parker H. Petit Institute of Bioengineering & Bioscience, Georgia Institute of TechnologyAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Elaissa L Trybus Hardy
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Yumiko Sakurai
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Byungwook Ahn
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Yongzhi Qiu
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
| | - Robert G Mannino
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
| | - Meredith E Fay
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
| | - Wilbur A Lam
- Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of MedicineAtlanta, Georgia, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory UniversityAtlanta, Georgia, USA
- Parker H. Petit Institute of Bioengineering & Bioscience, Georgia Institute of TechnologyAtlanta, Georgia, USA
- Winship Cancer Institute of Emory UniversityAtlanta, Georgia, USA
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15
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Kemp MM, Kumar A, Mousa S, Park TJ, Ajayan P, Kubotera N, Mousa SA, Linhardt RJ. Synthesis of gold and silver nanoparticles stabilized with glycosaminoglycans having distinctive biological activities. Biomacromolecules 2010; 10:589-95. [PMID: 19226107 DOI: 10.1021/bm801266t] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metal nanoparticles have been studied for their anticoagulant and anti-inflammatory efficacy in various models. Specifically, gold and silver nanoparticles exhibit properties that make these ideal candidates for biological applications. The typical synthesis of gold and silver nanoparticles incorporates contaminants that could pose further problems. Here we demonstrate a clean method of synthesizing gold and silver nanoparticles that exhibit biological functions. These nanoparticles were prepared by reducing AuCl(4) and AgNO(3) using heparin and hyaluronan as both reducing and stabilizing agents. The particles show stability under physiological conditions and narrow size distributions for heparin particles and wider distribution for hyaluronan particles. Studies show that the heparin nanoparticles exhibit anticoagulant properties. Additionally, either gold- or silver-heparin nanoparticles exhibit local anti-inflammatory properties without any significant effect on systemic hemostasis upon administration in carrageenan-induced paw edema models. In conclusion, gold and silver nanoparticles complexed with heparin demonstrated effective anticoagulant and anti-inflammatory efficacy, having potential in various local applications.
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Affiliation(s)
- Melissa M Kemp
- Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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16
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Barua RS, Sy F, Srikanth S, Huang G, Javed U, Buhari C, Margosan D, Aftab W, Ambrose JA. Acute cigarette smoke exposure reduces clot lysis--association between altered fibrin architecture and the response to t-PA. Thromb Res 2010; 126:426-30. [PMID: 20813396 DOI: 10.1016/j.thromres.2010.07.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 06/08/2010] [Accepted: 07/26/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND Enhanced thrombolysis is a proposed mechanism for reduced mortality in cigarette smokers with STEMI ("smoker's paradox"). The mechanisms remain unclear but studies suggest fibrin architecture (FA) may affect thrombolysis. Our group has previously shown that acute cigarette smoke exposure (CSE) alters FA. This study was done to evaluate the association between FA, thrombolysis and CSE. METHODS AND RESULTS Otherwise healthy smokers (n=22) were studied before and after smoking two cigarettes. Non-smokers (n=22) served as controls. Two ex-vivo models were used to evaluate clot lysis of venous blood and these data were compared to FA as determined by SEM. In the first model, clot lysis in a glass tube at 60minutes after addition of t-PA was measured. The second model quantified lysis utilizing thromboelastography. With the latter, after a clot reached maximum strength, t-PA was added and clot lysis at 60min was noted. SEM studies were performed on platelet poor plasma mixed with thrombin and FA was examined at 20K. Clot lysis was similar in both groups except that post-smoking, TEG showed a significantly lower lysis compared to pre- and non-smoking clots. SEM analysis showed significantly thinner fibers and denser clots post-smoking. CONCLUSIONS Venous clots from smokers failed to show an enhanced lysis when exposed to t-PA. In fact, acute CSE was associated with changes in FA and increased resistance to thrombolysis. These findings in part may explain enhanced thrombogenicity but suggest that mechanisms other than enhanced fibrinolysis are likely to be responsible for "smoker's paradox."
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Affiliation(s)
- Rajat S Barua
- Division of Cardiovascular Medicine, University of California San Francisco, Fresno, CA 93721, USA
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17
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Konishi N, Hiroe K, Kawamura M. Synergistic effect of a factor Xa inhibitor, TAK-442, and antiplatelet agents on whole blood coagulation and arterial thrombosis in rats. Thromb Res 2010; 126:124-9. [PMID: 20452654 DOI: 10.1016/j.thromres.2010.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/19/2010] [Accepted: 04/07/2010] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Activated platelets facilitate blood coagulation by providing factor V and a procoagulant surface for prothrombinase. Here, we investigated the potential synergy of a potent factor Xa/prothrombinase inhibitor, TAK-442, plus aspirin or clopidogrel in preventing arterial thrombosis and whole blood coagulation. METHODS Thrombus formation was initiated by FeCl(3)-induced rat carotid injury. Bleeding time was evaluated with the rat tail transection model. Whole blood coagulation was assessed by thromboelastographic examination (TEG) for which blood obtained from control, aspirin-, or clopidogrel-treated rats was transferred to a TEG analyzer containing, collagen or adenosine diphosphate (ADP), and TAK-442 or vehicle. RESULTS TAK-442 (3mg/kg, po), aspirin (100mg/kg, po) or clopidogrel (3mg/kg, po) alone had no significant effect on thrombus formation, whereas the combination of TAK-442 with aspirin and clopidogrel remarkably prolonged the time to thrombus formation without additional significant prolongation of bleeding time. TEG demonstrated that the onset of collagen-induced blood coagulation were slightly longer in aspirin-treated rats than control; however, when the blood from aspirin-treated rats was subsequently treated in vitro with 100 nM TAK-442, the onset of clotting was significantly prolonged. In contrast, only marginal prolongation was observed with TAK-442 treatment of blood from control animals. The onset time of ADP-induced blood coagulation was slightly longer in clopidogrel-treated rats compared with control, and it was further extended by TAK-442 treatment. CONCLUSION These results demonstrate that blood coagulation can be markedly delayed by the addition of TAK-442 to antiplatelets treatment which could contribute to synergistic antithrombotic efficacy in these settings.
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Affiliation(s)
- Noriko Konishi
- Pharmacology Research Laboratories, Takeda Pharmaceutical Company Ltd., Osaka, Japan
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18
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Abstract
Platelets play a crucial role in primary hemostasis by forming hemostatic plugs at sites of vascular injury. There is abundant evidence that platelets also play a pivotal role in the pathogenesis of arterial thrombotic disorders, including unstable angina (UA), myocardial infarction (MI), and stroke. The underlying pathophysiological mechanism of these processes has been recognized as the disruption or erosion of a vulnerable atherosclerotic plaque, leading to local platelet adhesion and subsequent formation of partially or completely occlusive platelet thrombi. A variety of methods have been used to assess platelet aggregation, blood coagulation, and the ex vivo and/or in vitro efficacy of platelet antagonists, anticoagulants, and thrombolytics.
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Affiliation(s)
- Shaker A Mousa
- Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, Rensselaer, NY, USA
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19
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Suwan J, Zhang Z, Li B, Vongchan P, Meepowpan P, Zhang F, Mousa SA, Mousa S, Premanode B, Kongtawelert P, Linhardt RJ. Sulfonation of papain-treated chitosan and its mechanism for anticoagulant activity. Carbohydr Res 2009; 344:1190-6. [PMID: 19476923 DOI: 10.1016/j.carres.2009.04.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 04/10/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
Abstract
The novel low-molecular-weight chitosan polysulfate (MW 5120-26,200 Da) was prepared using the depolymerization of chitosan with papain (EC. 3.4.22.2). The sulfonation of depolymerized products was performed using chlorosulfonic acid in N,N-dimethylformamide under semi-heterogeneous conditions. The structures of the products were characterized by FTIR, (13)C NMR, and (1)H NMR (1D, 2D NMR) spectroscopy. The present study sheds light on the mechanism of anticoagulant activity of chitosan polysulfate. Anticoagulant activity was investigated by an activated partial thromboplastin assay, a thrombin time assay, a prothrombin time assay, and thrombelastography. Surface plasmon resonance also provided valuable data for understanding the relationship between the molecular binding of sulfated chitosan to two important blood clotting regulators, antithrombin III and heparin cofactor II. These results show that the principal mechanism by which this chitosan polysulfate exhibits anticoagulant activity is mediated through heparin cofactor II and is dependent on polysaccharide molecular weight.
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Affiliation(s)
- Jiraporn Suwan
- Thailand Excellence Center for Tissue Engineering, Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
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20
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Razmara M, Hjemdahl P, Ostenson CG, Li N. Platelet hyperprocoagulant activity in Type 2 diabetes mellitus: attenuation by glycoprotein IIb/IIIa inhibition. J Thromb Haemost 2008; 6:2186-92. [PMID: 18983513 DOI: 10.1111/j.1538-7836.2008.03185.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Platelets are hyperactive in Type 2 diabetes mellitus (T2DM), and antiplatelet treatment with glycoprotein (GP) IIb/IIIa inhibitors provides better thrombotic protection in DM than in non-diabetic subjects. OBJECTIVE We hypothesized that diabetic platelets are hyperprocoagulant, and that this hyperactivity can be inhibited by GPIIb/IIIa blockade. METHODS Patients with T2DM and gender/age/body mass index-matched non-diabetic controls were recruited (n = 12 for both) to study the effect of GPIIb/IIIa blockade on platelet procoagulant activity. Platelet phosphotidylserine (PS), factor (F) Va expression, and platelet-derived microparticle (PDMP) generation were measured by whole blood flow cytometry. Platelet-dependent thrombin generation and plasma clotting time were monitored in recalcified platelet-rich plasma. RESULTS Compared to controls, basal platelet activation was similar, while thrombin receptor activating peptide stimulated activation was enhanced in patients with T2DM. Diabetic platelets also displayed more profound elevations of platelet PS exposure, FVa binding, and PDMP generation upon stimulation. These alterations resulted in a hyperprocoagulant state, as evidenced by a marked increase in the platelet procoagulant index, enhanced thrombin generation, and a shortened plasma clotting time. GPIIb/IIIa blockade by c7E3 or SR121566 decreased platelet PS exposure and FVa binding, and diminished platelet procoagulant activity in patients with T2DM. CONCLUSIONS Platelets have increased procoagulant activity in patients with T2DM. The hyperprocoagulant activity is counteracted by GPIIb/IIIa blockade.
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Affiliation(s)
- M Razmara
- Department of Medicine, Clinical Pharmacology Unit, Karolinska University Hospital, Solna, Stockholm, Sweden
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21
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Schols SEM, Feijge MAH, Lancé MD, Hamulyák K, ten Cate H, Heemskerk JWM, van Pampus ECM. Effects of plasma dilution on tissue-factor-induced thrombin generation and thromboelastography: partly compensating role of platelets. Transfusion 2008; 48:2384-94. [PMID: 18673348 DOI: 10.1111/j.1537-2995.2008.01872.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Bleeding upon major surgery or severe trauma is treated by transfusion with crystalloids, colloids, or plasma. This treatment, however, can lead to dilutional coagulopathy and impaired hemostasis. We investigated the suitability of two integrative coagulation tests to measure the hemostatic activity of diluted plasma. STUDY DESIGN AND METHODS Plasma from healthy donors was diluted in vitro with saline or colloid (venofundin or gelofusin). Coagulant activity in response to tissue factor was monitored by calibrated automated thrombin (CAT) generation and rotational thromboelastography (TEG), detecting formation of elastic fibrin clots. Plasma from patients receiving fluid infusion during coronary artery bypass grafting (CABG) was analyzed with the same assays. RESULTS Optimal activity of CAT and TEG assays required the presence of 10 pmol per L tissue factor and 4 micromol per L phospholipid vesicles or 100 x 10(9) platelets (PLTs) per L. Strikingly, thrombin generation and clot formation became impaired at a higher extent of dilution with PLTs present (< or =40% plasma) than with phospholipid vesicles present (< or =60% plasma). Colloids aggravated the dilution effect on clot formation, but FFP antagonized the dilution effect on thrombin and clot formation. In contrast, fibrinogen and Factor (F)XIII only restored the impaired clot formation. In plasma samples from patients undergoing CABG, CAT and TEG assay variables were altered to an extent corresponding with the volume of fluid infusion. CONCLUSION Thrombin generation and clot formation are reduced at a plasma dilution of more than 40 percent. In either process, PLTs can partly compensate for the dilution effect. In vitro dilution with colloids impaired fibrin clot elasticity compared to saline.
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Affiliation(s)
- Saskia E M Schols
- Department of Biochemistry, Maastricht University and University Hospital, Maastricht, The Netherlands
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22
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Azma T, Matsubara Y, Kinoshita H, Hidaka I, Shiraishi S, Nakao M, Kawamoto M, Yuge O, Hatano Y. Prothrombotic roles of substance-P, neurokinin-1 receptors and leukocytes in the platelet-dependent clot formation in whole blood. J Thromb Thrombolysis 2008; 27:280-6. [PMID: 18363037 DOI: 10.1007/s11239-008-0215-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Accepted: 03/17/2008] [Indexed: 11/30/2022]
Abstract
A number of types of non-neuronal cells including leukocytes have been confirmed to possess substance-P and its specific neurokinin-1 receptor (NK1R), while the pathophysiological roles of substance-P in these cells remain to be established. Effects of substance-P through NK1R on platelet-dependent clot formation were evaluated by using an oscillating-probe viscoelastometer. The clot signal, indicative of the clot strength in blood-derived samples, was measured after the stimulation with celite and Ca(2+). Substance-P (10 nM) increased the clot signal of whole blood obtained from healthy volunteers, especially modulating the platelet-dependent distinctive peak in traces of the signal. A NK1R antagonist Spantide (500 nM) blocked such substance-P derived change, suggesting the involvement of platelets in the action of substance-P. In contrast, substance-P did not increase the clot signal of platelet-containing but leukocyte-removed plasma. From these, we conclude that substance-P promotes platelet-dependent clot formation through NK1R, in which leukocytes appear to be involved.
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Affiliation(s)
- Toshiharu Azma
- Department of Anesthesiology, Faculty of Medicine, Saitama Medical University, Iruma, Saitama, Japan.
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23
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Mousa SA, Ahmad S. Platelet GPIIb/IIIa antagonist, XV459, in heparin-induced thrombocytopenia. Am J Hematol 2007; 82:276-82. [PMID: 17039513 DOI: 10.1002/ajh.20801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is a serious, immune-related complication of heparin therapy. One of the most severe manifestations of HIT is the development of thromboembolic events, which is based on platelet activation and aggregation caused by HIT-associated antibodies. Therapeutic options for patients with HIT are limited despite advancement toward the development of alternative (nonheparin) anticoagulants, such as direct thrombin inhibitors and indirect anti-factor Xa agents. Platelet GPIIb/IIIa receptor antagonists have been shown to be the final common pathway for platelet aggregation regardless of the use of activator or anticoagulant. In this study, the ability of a novel platelet GPIIb/IIIa antagonist, a free acid form of roxifiban (XV459), to block platelet activation/aggregation in response to highly characterized heparin-PF4 antibody-positive plasma/heparin was examined using light transmittance aggregometry, serotonin release, and (125)I-fibrinogen binding assays to human platelets. XV459 at 20 nM maximally inhibited (P < 0.001) the platelet-activation/aggregation responses as mediated by the HIT antibody-positive plasma (in the presence of therapeutic heparin concentrations). Compared with controls, both HIT antibodies/heparin and TEAC (a mixture of thrombin [0.1 IU/ml], epinephrine [1 microg/ml], arachidonate [0.1 mM], and collagen [10 microml]) resulted in significantly higher levels of fibrinogen binding to human platelets (5-7-fold increase; P < 0.001). Concentration-dependent profiles of XV459 on the mean percent inhibition of (125)I-fibrinogen binding in the presence of HIT antibodies and TEAC were achieved ( approximately 50% inhibition at 10 nM XV459). The platelet GPIIb/IIIa receptor antagonist (XV459) might be of potential benefit in the management of thrombotic thrombocytopenia produced by heparin and/or related glycosaminoglycans.
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Affiliation(s)
- Shaker A Mousa
- Pharmaceutical Research Institute, Albany College of Pharmacy, Albany, New York 12208, USA.
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24
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Hobson AR, Agarwala RA, Swallow RA, Dawkins KD, Curzen NP. Thrombelastography: current clinical applications and its potential role in interventional cardiology. Platelets 2007; 17:509-18. [PMID: 17127479 DOI: 10.1080/09537100600935259] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Thrombelastography is a bedside blood test used to assess patients' haemostatic status. It has a well-established role in hepatobiliary and cardiac surgery and is also used in obstetrics and trauma medicine to assess coagulation and identify the causes of post-operative bleeding. It is not routinely used in the diagnosis or treatment of thrombosis although recently it has been shown to predict thrombotic events post-operatively and after percutaneous intervention (PCI). In cardiovascular medicine the importance of the platelet in the pathophysiology of vascular events is increasingly apparent. As a result antiplatelet therapy is a cornerstone of the treatment for coronary disease, particularly in the setting of acute coronary syndromes. The increasing utilization of stents, particularly drug-eluting devices, in PCI has also necessitated widespread use of antiplatelet agents to minimize the risk of stent thrombosis. A quick, accurate and reliable test to measure the effect of platelet inhibition by antiplatelet agents on clotting in an individual patient would be of profound clinical value. The results from such a test could provide prognostic information, allow treatment with antiplatelet agents to be tailored to the individual and identify resistance to one or more of these agents. Optimization and tailoring of anti-platelet therapy in patients with cardiovascular disease, particularly those undergoing PCI, using such a test may reduce morbidity and mortality from thrombotic and haemorrhagic complications. Current methods of assessing platelet activity measure platelet count and function in isolation. Optical aggregation is the most widely used method for assessing platelet function but it is relatively time consuming, measures platelet function in isolation rather than in the context of clot formation and is not a bedside test. By contrast the modified thrombelastograph platelet mapping kit marketed by Haemoscope can be used to assess the effects of antiplatelet agents on ex vivo blood clotting, thus giving a measurement more relevant to in vivo responses. This represents a potentially powerful tool to assess response of individual patients to antiplatelet therapy, particularly in the context of PCI.
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Affiliation(s)
- A R Hobson
- Southampton University Hospital, Wessex Cardiac Unit, Southampton, UK
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25
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Mousa SA. In-vitro efficacy of different platelet glycoprotein IIb/IIIa antagonists and thrombolytics on platelet/fibrin-mediated clot dynamics in human whole blood using thrombelastography. Blood Coagul Fibrinolysis 2007; 18:55-60. [PMID: 17179828 DOI: 10.1097/mbc.0b013e3280116c36] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Suppressing platelet activation improves efficacy of thrombolytic therapy for stroke and acute myocardial infarction. Combination treatment with recombinant tissue plasminogen activator (r-tPA) and glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitor that binds with high affinity to platelets may therefore improve the efficacy of thrombolytic therapy. The effect of platelet GPIIb/IIIa antagonists and/or r-tPA on the dynamics of platelet/fibrin clot formation, strength, and lysis was determined using thrombelastography in human blood under thrombin or tissue factor stimulation. The study utilized platelet GPIIb/IIIa antagonists with high affinity and slow off-rate (Class I) from resting and activated platelets in comparison with Class II antagonists (lower affinity and fast off-rate from platelet GPIIb/IIIa receptors). The combination of the active form of roxifiban (XV459; Class I) or the active form of orbofiban (Class II) with a subeffective concentration of r-tPA resulted in a synergistic effect in clot lysis with roxifiban active form XV459 but not with that of orbofiban at therapeutically achievable concentrations that inhibit human platelet aggregation. These data indicate differential enhanced thrombolysis of low levels of r-tPA with high-affinity Class I but not with low-affinity Class II GPIIb/IIIa antagonists in the absence of anticoagulants.
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Affiliation(s)
- Shaker A Mousa
- The Pharmaceutical Research Institute at Albany College of Pharmacy, Albany, New York 12208, USA.
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26
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Abstract
Monitoring hemostasis is now possible by different modalities, of which the point of care devices seem most helpful to the clinician in the operating room. Most of these monitors are being used in the cardiac population, and their significance in other fields remains to be assessed.
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Affiliation(s)
- Antoine G Rochon
- Department of Anesthesiology, Montreal Heart Institute, 5000 Belanger Street, Montreal, Canada HIT IC8.
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27
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Viswanathan G, Murugesan S, Pushparaj V, Nalamasu O, Ajayan PM, Linhardt RJ. Preparation of biopolymer fibers by electrospinning from room temperature ionic liquids. Biomacromolecules 2006; 7:415-8. [PMID: 16471910 PMCID: PMC4777308 DOI: 10.1021/bm050837s] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electrospinning is a versatile process used to prepare micro- and nano- sized fibers from various polymers dissolved in volatile solvents. In this report, cellulose and cellulose-heparin composite fibers are prepared from nonvolatile room temperature ionic liquid (RTIL) solvents by electrospinning. RTILs are extracted from the biopolymer fiber after the fiber formation using a cosolvent. Micron to nanometer sized, branched fibers were obtained from 10% (w/w) concentration of polysaccharide biopolymer in RTIL solution with an applied voltage of 15-20 kV. Cellulose-heparin composite fibers showed anticoagulant activity, demonstrating that the bioactivity of heparin remained unaffected even on exposure to a high voltage involved in electrospinning.
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28
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Rivard GE, Brummel-Ziedins KE, Mann KG, Fan L, Hofer A, Cohen E. Evaluation of the profile of thrombin generation during the process of whole blood clotting as assessed by thrombelastography. J Thromb Haemost 2005; 3:2039-43. [PMID: 16102110 PMCID: PMC1410193 DOI: 10.1111/j.1538-7836.2005.01513.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The objective of this study was to evaluate the possibility of linking the tracing of whole blood clotting in a thrombelastograph (TEG) hemostasis system with the generation of thrombin assessed by thrombin/antithrombin complex (TAT). Citrated whole blood containing corn trypsin inhibitor from volunteers was clotted in the presence of CaCl2 and tissue factor. Clotting was monitored with the eight channels of a TEG system. At different time points, the whole blood TEG reaction cups were kept in a cold quenching solution, centrifuged, and the supernatants were kept at -80 degrees C until assayed for TAT by ELISA. The total thrombus generation (TTG) was calculated from the first derivative of the TEG waveform and was compared with thrombin generation measured by TAT. The two vector values--the TAT thrombin generation data and the corresponding TEG TTG--were analyzed using Pearson correlation coefficients (r) and linear, non-linear and natural log (ln) transformation of TAT values for least-squares goodness-of-fit curves. The best least-squares fit is an exponential curve. Linearizing using the ln of the TAT thrombin generation variable produces the same r (0.94) as of the exponential curve. The prediction equation is y = 8.0465 + 0.0005x (P < or = 0.0001), where y is the TAT thrombin generation variable in the ln transformation and x is the TEG TTG variable. The high magnitude of r and the high significance of the prediction equation demonstrate the high efficacy of the prediction of TAT thrombin generation by the use of TEG TTG.
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Affiliation(s)
- G E Rivard
- Sainte-Justine Hospital, Montreal, QC, Canada.
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29
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Mousa SA, Bozarth JM, Seiffert D, Feuerstein GZ. Using thrombelastography to determine the efficacy of the platelet glycoprotein IIb/IIIa antagonist, roxifiban, on platelet/fibrin-mediated clot dynamics in humans. Blood Coagul Fibrinolysis 2005; 16:165-71. [PMID: 15795533 DOI: 10.1097/01.mbc.0000164423.90545.a0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The effect of platelet glycoprotein IIb/IIIa antagonists on the dynamics of platelet/fibrin clot formation and strength was determined using thrombelastography (TEG) under conditions of recalcification or tissue factor addition. In the present investigation, the effect of roxifiban (class I) on ex vivo clot dynamics using recalcified blood was tested in normal, healthy volunteers (n = 7) dosed with 1 mg BID roxifiban for 9 days. Roxifiban inhibited platelet aggregation induced by 20 mumol/l adenosine diphosphate by 60-90% but did not significantly affect any of the TEG parameters either at peak, trough, or subtrough drug levels. Addition of 30 nmol/l roxifiban free acid (XV459; which is ineffective by itself to modify TEG parameters) to human blood obtained from roxifiban-treated subjects resulted in 45-60% (P < 0.01) inhibition of clot strength (maximum amplitude), 90-100% (P < 0.01) inhibition of initial kinetic of clot development (angle alpha), and 50-70% (P < 0.01) inhibition of early clot initiation (K). These data suggest that a subthreshold blood level of 40-50 nmol/l roxifiban active form was achieved in those subjects, as estimated from an in vitro calibration with XV459. These data indicate (not studied) that roxifiban, at a targeted clinical dosing regimen, failed to achieve sufficient exposure to modulate platelet-mediated clot retraction.
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Affiliation(s)
- Shaker A Mousa
- Pharmaceutical Research Institute and Albany College of Pharmacy, 106 New Scotland Avenue, Albany, NY 12208-3492, USA.
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30
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Katori N, Szlam F, Levy JH, Tanaka KA. A novel method to assess platelet inhibition by eptifibatide with thrombelastograph. Anesth Analg 2004; 99:1794-1799. [PMID: 15562073 DOI: 10.1213/01.ane.0000136476.82598.88] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We examined a novel method to detect platelet inhibition with thrombelastography (TEG). We hypothesized that this method would be suitable for monitoring the antiplatelet effects of eptifibatide (Integrilin). Whole blood from healthy volunteers was anticoagulated with 3.2% citrate or unfractionated heparin (7 IU/mL). For the platelet aggregation test, both citrate and heparinized samples were spiked with increasing concentrations of eptifibatide (0, 0.2, 0.4, 0.8, 1.6, and 4 microg/mL). Conventional kaolin TEG was performed with citrated samples, and batroxobin-modified TEG was performed with heparinized samples, which were spiked with eptifibatide at concentrations of 0, 0.4, 0.8, 1.6, 4, 8, and 24 microg/mL. Adenosine 5'-diphosphate-induced platelet aggregation was reduced to 6.4% +/- 2.9% (citrate) and 10.3% +/- 4.8% (heparin) with eptifibatide at the concentration of 4 mug/mL. The kaolin TEG showed a decrease in maximum amplitude (MA) only at the eptifibatide concentration of 24 mug/mL and no change in alpha angle, whereas with the batroxobin-based TEG, the difference in MA and alpha angle was observed at concentrations >/=0.8 microg/mL. Additionally, the time to achieve maximum MA was much shorter for batroxobin TEG than for kaolin TEG. We conclude that the batroxobin-modified TEG is a sensitive method that detects platelet inhibition induced by eptifibatide.
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Affiliation(s)
- Nobuyuki Katori
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia
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Sy SKB, Levenstadt AL. A perspective on the toxicological mechanisms possibly contributing to the failure of oral glycoprotein IIb/IIIa antagonists in the clinic. Am J Cardiovasc Drugs 2004; 4:1-10. [PMID: 14967061 DOI: 10.2165/00129784-200404010-00001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In clinical trials in patients with acute or unstable coronary syndromes and/or undergoing percutaneous coronary intervention, oral glycoprotein (GP) IIb/IIIa antagonists did not show therapeutic benefit over aspirin during long-term administration. Moreover, high-dose oral administration of these agents was associated with greater fatality risk compared with that of lower doses. This article postulates that continuous exposure of the GP IIb/IIIa receptor (integrin alpha(IIb)beta(3)) to these agents may result in some form of resistance or activation of other biological systems. These toxicological mechanisms may help explain some factors that could potentially contribute to the failure of these agents in clinical trials. Several hypotheses are presented: (i) modulation of platelet response because of long-term exposure to GP IIb/IIIa antagonists; (ii) role of related integrins and associated proteins to compensate for the loss of platelet activity because of dysfunctional GP IIb/IIIa receptors occupied by inhibitors; (iii) effects of the GP IIb/IIIa antagonists on other cellular systems such as the caspase and procaspase enzymes in apoptosis and possibly the ryanodine receptor involved in sarcoplasmic reticulum calcium release. These toxicological mechanisms could potentially limit the utility of these oral agents in long-term administration.
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Affiliation(s)
- Sherwin K B Sy
- Centre for Nonlinear Dynamics in Physiology and Medicine, Department of Physiology, McGill University, McIntyre Medical Sciences Building, Montreal, Quebec, Canada H3G 1Y6.
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Affiliation(s)
- Bruce D Spiess
- Department of Anesthesiology, Evanston Northwestern Healthcare, IL 60201, USA
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33
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Cannon CP. Oral platelet glycoprotein IIb/IIIa receptor inhibitors--part II. Clin Cardiol 2003; 26:401-6. [PMID: 14524594 PMCID: PMC6654522 DOI: 10.1002/clc.4960260903] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Accepted: 11/22/2002] [Indexed: 11/06/2022] Open
Abstract
Although the hypothesis of benefit from prolonged oral IIb/IIIa inhibition was appealing, the large Phase III trials have uniformly shown there was no improvement in outcome. In addition, there was an increased mortality seen in patients treated with the oral IIb/IIIa inhibitor. This latter finding is not adequately explained, but is likely a multifactorial problem of this strategy of platelet inhibition. The trials found that, even with no improvement in efficacy, there was increased bleeding, meaning that for chronic therapy with IIb/IIIa inhibition there does not appear to be a therapeutic window. Accordingly, chronic oral IIb/IIIa inhibition appears to have been well tested but has not worked. Fortunately, there are several other oral antiplatelet agents available that have shown beneficial results, including clopidogrel. In addition, other newer classes of antiplatelet agents are in earlier stages of development. Thus, agents targeted more "upstream" in platelet activation pathways may offer a more tolerable and efficacious approach to long-term antiplatelet therapy.
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Affiliation(s)
- Christopher P Cannon
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
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Hu H, Zhang W, Li N. Glycoprotein IIb/IIIa inhibition attenuates platelet-activating factor-induced platelet activation by reducing protein kinase C activity. J Thromb Haemost 2003; 1:1805-12. [PMID: 12911597 DOI: 10.1046/j.1538-7836.2003.00324.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycoprotein (GP)IIb/IIIa inhibition may abolish activated leukocyte-induced platelet activation, in which leukocyte-released platelet-activating factor (PAF) is a major mediator. The present study thus investigated if and how GPIIb/IIIa inhibitors interfere with PAF-induced platelet activation. Platelet and leukocyte activation were monitored by flow cytometry and immunoblotting. GPIIb/IIIa inhibitors (c7E3, non-peptide SR121566, and MAb RFGP56) attenuated PAF-induced, but not adenosine diphosphate (ADP)- or thrombin receptor activating peptide (TRAP)-induced platelet P-selectin expression in whole blood. GPIIb/IIIa blockade enhanced ADP- or TRAP-induced leukocyte CD11b expression, but not the response to PAF. GPIIb/IIIa blockade attenuated PAF-induced, but enhanced ADP- or TRAP-induced platelet-leukocyte aggregation. Under the present experimental conditions, thromboxane A2 receptor antagonism did not significantly influence PAF-induced platelet activation, and GPIIb/IIIa inhibition did not interfere with calcium mobilization/influx in platelets. Protein kinase C (PKC) blockade inhibited PAF-induced platelet P-selectin expression, and PAF-induced PKC activity was reduced by GPIIb/IIIa inhibition. PAF (=1 micro m) did not induce MEK 1/2 or ERK 1/2 phosphorylation, whilst thrombin induced marked responses, which were enhanced by GPIIb/IIIa blockade. Thus, GPIIb/IIIa inhibition attenuates PAF-induced platelet activation via inhibiting PKC activity. GPIIb/IIIa blockade enhances thrombin-induced platelet MEK 1/2 and ERK 1/2 activation, and augments ADP- and TRAP-induced leukocyte activation by enhancing platelet-leukocyte aggregation.
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Affiliation(s)
- H Hu
- Department of Medicine, Karolinska Hospital, Karolinska Institute, Stockholm, Sweden
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35
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Murphy J, Wright RS, Gussak I, Williams B, Daly RN, Cain VA, Pieniaszek HJ, Sy SKB, Ebling W, Simonson K, Wilcox RA, Kopecky SL. The use of roxifiban (DMP754), a novel oral platelet glycoprotein IIb/IIIa receptor inhibitor, in patients with stable coronary artery disease. Am J Cardiovasc Drugs 2003; 3:101-12. [PMID: 14727937 DOI: 10.2165/00129784-200303020-00004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Intravenous platelet glycoprotein (GP) IIb/IIIa receptor inhibitors have a significant beneficial impact on the outcomes of patients undergoing high-risk coronary interventions and in the stabilization of patients with unstable angina pectoris refractory to conventional medical treatment. The role of long-term treatment with oral platelet GP IIb/IIIa receptor inhibitors in patients with coronary artery disease is unproven. This study examined the dose-response effect on inhibition of platelet aggregation by roxifiban (DMP754), a novel oral platelet GP IIb/IIIa receptor inhibitor, and its safety and tolerability in patients with a history of chronic stable angina pectoris. METHODS Ninety-eight patients were randomized to receive either a placebo or 1 of 8 oral dosages of roxifiban. Twenty-two patients were enrolled in multiple-dose regimens, bringing the total study population to 120. The oral dosages were 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, or 2.5 mg/day for up to 30 days. RESULTS Pharmacodynamic response of roxifiban was clearly dose-dependent. Platelet aggregation inhibition in response to 10 micromol/L slope adenosine diphosphate was sustained throughout the study period (up to 1 month). No serious adverse events, including significant major bleeding events, were associated with roxifiban treatment. Minor bleeding was reported in 5% of participants in the placebo group (1 of 21 cases) versus 26% in the study group (26 of 99 cases). Incidence of minor bleeding associated with roxifiban 2 and 2.5 mg/day was significantly (p < or = 0.05) greater than that with placebo. Adverse events, including gastrointestinal disorders, platelet and clotting disorders, and urinary tract disorders, were observed in 1 of 21 cases (5%) in the placebo group and in 12 of 99 cases (12%) in the study group. Reversible thrombocytopenia without other complications developed in two patients. CONCLUSIONS Roxifiban-induced inhibition of platelet aggregation was dose-dependent and sustained throughout the study period: higher drug dosages correlated with higher levels of platelet inhibition and higher incidence of minor bleeding events. No serious adverse events were observed at any dosage. Thus, roxifiban appears to be a potent oral platelet GP IIb/IIIa receptor inhibitor that is clinically well-tolerated and deserves further study as a new treatment strategy in patients with chronic stable angina pectoris.
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Affiliation(s)
- Joseph Murphy
- Mayo Alliance for Clinical Trials and Division of Cardiology, Mayo Clinic and Mayo Foundation, Rochester, USA
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36
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Wang X, Dorsam RT, Lauver A, Wang H, Barbera FA, Gibbs S, Varon D, Savion N, Friedman SM, Feuerstein GZ. Comparative analysis of various platelet glycoprotein IIb/IIIa antagonists on shear-induced platelet activation and adhesion. J Pharmacol Exp Ther 2002; 303:1114-20. [PMID: 12438534 DOI: 10.1124/jpet.102.038513] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Platelet accretion into arterial thrombus in stenotic arterial vessels involves shear-induced platelet activation and adhesion. The Cone and Plate(let) Analyzer (CPA) is designed to simulate such conditions in vitro under a rotating high shear rate in whole blood. In the present study, we evaluated various experimental conditions (including aspirin, temperature, and calcium concentration) and investigated the effects of small molecules along with peptide glycoprotein IIb/IIIa antagonists on platelet adhesion using the CPA system. Concentration-dependent effect of glycoprotein IIb/IIIa antagonists on shear-induced platelet adhesion showed marked differences in potencies: IC50 = 34, 35, 91, 438, and 606 nM for DPC802 (a specific glycoprotein IIb/IIIa antagonist), roxifiban, sibrafiban, lotrafiban, and orbofiban (free acid forms), respectively, and IC50 values of 43, 430, and 5781 nM for abciximab, tirofiban, and eptifibatide, respectively. Parallel study was also conducted to evaluate the effect of glycoprotein IIb/IIIa inhibitors using optical aggregometry. The potency of fibans in blocking shear-induced platelet adhesion correlated well with their binding affinity to the resting and activated glycoprotein IIb/IIIa receptors, as well as their "off-rates". Nevertheless, none of these fibans was able to effectively block shear-induced platelet adhesion at targeted clinical dosing regimens except for abciximab. These data suggest that glycoprotein IIb/IIIa antagonists that show similar efficacy in the inhibition of platelet aggregation in a static in vitro assay may differ substantially in a shear-based system of platelet adhesion. The clinical significance of this phenomenon awaits further investigation.
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Affiliation(s)
- Xinkang Wang
- Department of Cardiovascular Sciences, Bristol-Myers Squibb Company, Experimental Station, Wilmington, Delaware 19880-0400, USA.
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Seiffert D, Pedicord DL, Kieras CJ, He B, Stern AM, Billheimer JT. Regulation of clot retraction by glycoprotein IIb/IIIa antagonists. Thromb Res 2002; 108:181-9. [PMID: 12590956 DOI: 10.1016/s0049-3848(02)00395-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Binding of fibrinogen to platelet glycoprotein (GP) IIb/IIIa induces clot retraction. Significant differences among GP IIb/IIIa antagonists were previously noted to inhibit thromboelastography in whole blood specimens. The relationship between efficacy of these agents and inhibition of clot retraction is unclear. Here, we use a plasma-free clot retraction assay to evaluate potency of GP IIb/IIIa antagonists to inhibit clot retraction and modulate platelet signaling, and to address whether these effects are realized in the clinically relevant dose range. The potencies for inhibition of clot retraction and aggregation are similar for antagonists with high affinity for resting platelets and slow off-rates, whereas lower affinity and fast off-rate antagonists are disproportionately less effective in blocking clot retraction. A positive correlation is observed between inhibition of clot retraction and inhibition of tyrosine dephosphorylation across a number of GP IIb/IIIa antagonist pharmacophores. For lower affinity and fast off-rate antagonists, the concentrations required for inhibition of clot retraction clearly exceed the clinical dose range. Site occupancy studies combined with clot retraction experiments addressed whether high affinity and slow off-rate compounds can alter clot retraction during the dosing interval. Binding studies using [3H] Roxifiban, a high affinity GP IIb/IIIa antagonist, indicate that occupancy of >95% of GP IIb/IIIa sites is required to inhibit clot retraction. This level of occupancy is not routinely achieved in the clinic and is not tolerated, at least for chronic therapy. These results suggest that inhibition of clot retraction is not necessary for efficacy of GP IIb/IIIa antagonists.
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Affiliation(s)
- Dietmar Seiffert
- Chemical Enzymology, Experimental Station E400/3255, Bristol-Myers Squibb Company, P.O. Box 80400, Wilmington, DE 19880, USA.
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38
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Billheimer JT, He B, Spitz SM, Stern AM, Seiffert D. Effects of glycoprotein IIb/IIIa antagonists on platelet activation: development of a transfer method to mimic peak to trough receptor occupancy. Thromb Res 2002; 107:303-17. [PMID: 12565717 DOI: 10.1016/s0049-3848(02)00336-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Several oral glycoprotein (GP) IIb/IIIa antagonists, Sibrafiban, Orbofiban and Lotrafiban, have been studied in large phase III trials; each has failed to provide efficacy and has been associated with increased mortality. Roxifiban has pharmacokinetic and pharmacodynamic properties believed to be more favorable than the earlier oral agents. Here, we revisit the controversial hypothesis of platelet activation liabilities of GP IIb/IIIa antagonists. The effects of site occupancy by four fibans (Roxifiban, Sibrafiban, Orbofiban and Lotrafiban) on platelet activation was assessed using P-selectin expression, fibrinogen binding and microaggregate formation. All four fibans inhibited ADP and TRAP-stimulated fibrinogen binding and microaggregate formation in a concentration-dependent manner, whereas P-selectin expression was relatively unaltered. To more vigorously test for activation liabilities, the effects of transition from peak to trough receptor occupancy upon platelet stimulation was analyzed. The high affinity of Roxifiban for resting platelets precluded reduction of site occupancy by dialysis or gel filtration. A method was developed that takes advantage of the rapid equilibrium of Roxifiban between platelets and soluble GPIIb/IIIa. The platelet occupancy is controlled by the ratio of platelet GPIIb/IIIa to soluble GPIIb/IIIa. This method allows in vitro investigation of peak/trough transitions on platelet activation. A decrease in site occupancy from peak to trough of Roxifiban or Sibrafiban did not result in increased activation of platelets. The loss of platelet-bound antagonist upon incubation with purified soluble GPIIb/IIIa returned fibrinogen binding/microaggregate formation to no drug levels. In conclusion, these studies do not provide evidence for an activation liability of GPIIb/IIIa antagonists in vitro.
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Affiliation(s)
- Jeffrey T Billheimer
- Bristol-Myers Squibb Company, Experimental Station E400/3253, Wilmington, DE 19880-0400, USA
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39
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Caron A, Théorêt JF, Mousa SA, Merhi Y. Anti-platelet effects of GPIIb/IIIa and P-selectin antagonism, platelet activation, and binding to neutrophils. J Cardiovasc Pharmacol 2002; 40:296-306. [PMID: 12131559 DOI: 10.1097/00005344-200208000-00015] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Platelet activation with GPIIb/IIIa binding to fibrinogen, aggregation and interaction with leukocytes constitute the principal mediator of thrombosis. Although the clinical benefits of GPIIb/IIIa antagonists have been documented, the relationship between their anti-platelet properties, platelet activation and binding to leukocytes is still debated. We investigated the effects of abciximab, tirofiban, roxifiban, and an anti-P-selectin blocking monoclonal antibody (Mab) on isolated human platelet aggregation using optical aggregometer, and on platelet P-selectin and GPIIb/IIIa expression, and platelet-neutrophil binding using flow cytometry. Thrombin at 0.025 U/ml induced maximal platelet aggregation (76.3 +/- 2.6%), P-selectin expression (88.5 +/- 4%), GPIIb/IIIa activation (PAC-1 binding, 86.2 +/- 8.9%) and platelet-neutrophil binding (58.0 +/- 6.4%). The GPIIb/IIIa antagonists inhibited in a concentration-dependent manner platelet aggregation (IC50 of 100 nM for abciximab and tirofiban and 50 nM for roxifiban) and PAC-1 binding, without any effect on P-selectin. None of these agents affected significantly platelet-neutrophil binding, whereas an anti-P-selectin Mab abolished this binding and amplified the effect of abciximab on platelet aggregation. These results indicate that the effects of these GPIIb/IIIa antagonists on platelet aggregation are not related to inhibition of platelet activation, as P-selectin levels and platelet-neutrophil binding remained unaffected, and highlight the participation of P-selectin with GPIIb/IIIa in platelet aggregation.
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Affiliation(s)
- Alexandre Caron
- Laboratory of Experimental Pathology, Montreal Heart Institute and the University of Montreal, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada
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40
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Pieniaszek HJ, Sy SKB, Ebling W, Fossler MJ, Cain VA, Mondick JT, Ma S, Kornhauser DM. Safety, tolerability, pharmacokinetics, and time course of pharmacologic response of the active metabolite of roxifiban, XV459, a glycoprotein IIb/IIIa antagonist, following oral administration in healthy volunteers. J Clin Pharmacol 2002; 42:738-53. [PMID: 12092741 DOI: 10.1177/009127002401102687] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Roxifiban is an esterprodrug that is hydrolyzed, after oral administration, to the active glycoprotein (GP) IIb/IIIa antagonist, XV459. The objectives of the study were to investigate the safety, tolerability, pharmacokinetics, and the time course of the pharmacologic response of XV459 in escalating doses of roxifiban and to assess the effect of age, loading dose of roxifiban, and aspirin pretreatment on XV459 pharmacokinetics, pharmacologic response, and safety profile in a five-part double-blind, placebo-controlled study. Healthy male volunteers (ages 18-46 years) received 7 (0.75-1.5 mg; n = 20) and 10 (0.75-1.0 mg; n = 8) multiple, oral, qd doses of roxifiban or placebo (n = 5). Healthy older male and female volunteers (ages 47-75 years) received roxifiban qd doses (0.5-0.75 mg; n = 8) or placebo (n = 3) for 7 days. Healthy male subjects (ages 18-46 years; n = 16) received a 1.5 or 1.0 mg loading dose either with or without pretreatment of 325 mg aspirin once daily for 3 days followed by single daily doses of 1.0 mg roxifiban for 6 days. Measurable plasma concentrations of XV459 appeared rapidly and were sustained throughout the dosing interval of 24 hours. The pharmacokinetics of XV459 were nonlinear. Systemic exposure of XV459 plateaued at the 1-mg dose level; plasma concentrations approached steady state in 4 to 6 days for doses greater than 1.0 mg. The time course of pharmacologic response as measured by the inhibition of platelet aggregation in response to an ex vivo 10 microM adenosine 5'-diphosphate (ADP) agonist correlated closely to the plasma concentration of XV459. Potent inhibition of ADP-induced platelet aggregation (IPA) persisted over the entire dosing interval. A clear dose response was achieved with roxifiban doses of 0.5 and 1.0 mg. For doses greater than 1.0 mg, a dose-proportional increase in IPA was not observed. Both the pharmacokinetics and pharmacologic response of XV459 exhibited low intraindividual variability (coefficient of variation [CV] < 15%) and higher interindividual variability (CV < 30%). Pretreatment with aspirin and/or a loading dose of 1.5 mg roxifiban had no significant effect on the pharmacokinetics and pharmacologic response of XV459. A dose-related increase in template bleeding time was observed at 1.25- and 1.5-mg doses of roxifiban, as compared to placebo. However, these bleeding time increases in the 1.25- and 1.5-mg dose groups were not significantly different from those at the lower dose groups. Overall, once-daily oral administration of roxifiban was fairly well tolerated and provided sustained systemic drug exposure and pharmacologic response over the entire administration interval.
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Affiliation(s)
- Henry J Pieniaszek
- Drug Metabolism and Pharmacokinetics, Bristol-Myers Squibb Pharma Company, Newark, Delaware, USA
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41
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Newby LK, Califf RM, White HD, Harrington RA, Van de Werf F, Granger CB, Simes RJ, Hasselblad V, Armstrong PW. The failure of orally administered glycoprotein IIb/IIIa inhibitors to prevent recurrent cardiac events. Am J Med 2002; 112:647-58. [PMID: 12034415 DOI: 10.1016/s0002-9343(02)01106-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE Despite the success of intravenous glycoprotein IIb/IIIa antagonists, oral formulations have failed to show benefit and have been associated with increased mortality. To understand these findings, we performed a meta-analysis of results from four phase 3 trials. SUBJECTS AND METHODS Trials were identified by MEDLINE search; review of abstracts from American College of Cardiology, European Society of Cardiology, and American Heart Association scientific sessions; or querying investigators in the field. Published, phase 3, randomized, placebo-controlled trials involving more than 1000 patients with coronary artery disease that compared an oral glycoprotein IIb/IIIa antagonist with or without background aspirin versus aspirin, and that had a planned follow-up of > or =30 days, were included. Four trials met these criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were generated from results, and combined using an empirical Bayes random-effects model. RESULTS Among 33,326 patients, oral glycoprotein IIb/IIIa agents were associated with 31% increased mortality (OR = 1.31; 95% CI: 1.12 to 1.53; P= 0.0001). Results were similar whether the agent was added to (OR = 1.38; 95% CI: 1.15 to 1.67) or substituted for (OR = 1.37; 95% CI: 1.00 to 1.86) aspirin. Ischemic events or sudden death (OR = 1.22; 95% CI: 0.91 to 1.63) were also more common. Among patients with acute coronary syndromes, the incidence of myocardial infarction was increased (OR = 1.16; 95% CI: 1.03 to 1.29). CONCLUSION Oral glycoprotein IIb/IIIa inhibitor therapy is associated with increased mortality and myocardial infarction. No single explanation for these findings is satisfactory; the problem is likely to be multifactorial.
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Affiliation(s)
- L Kristin Newby
- Duke Clinical Research Institute, Durham, North Carolina 27707, USA
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42
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Mousa SA, Forsythe MS, Bozarth JM. Differential efficacy of different platelet glycoprotein IIb/IIIa antagonists on platelet/fibrin-mediated clot dynamics under different conditions using thrombelastography: the critical need for anticoagulant. Coron Artery Dis 2002; 13:243-8. [PMID: 12193852 DOI: 10.1097/00019501-200206000-00007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Intravenous GpIIb/IIIa antagonists demonstrate various significant clinical benefits depending on the agent used. In contrast, oral delivery of GpIIb/IIIa antagonists failed in achieving clinical benefits. This raises the question about the differences among different GpII/IIIa antagonists. METHODS The effect of various platelet glycoprotein (GP) IIb/IIIa antagonists on the dynamics of platelet/fibrin clot formation and strength was determined using thrombelastography under different conditions. RESULTS GPIIb/IIIa antagonists with high affinity for resting and activated platelets and with slow rates of dissociation from GPIIb/IIIa (Class I antagonists) demonstrated potent and comparable inhibition of platelet aggregation and platelet-mediated clot strength under different conditions. In contrast to antagonists that dissociate rapidly from GPIIb/IIIa (class II antagonists). Class I antagonists such as the free acid form of roxifiban inhibited platelet-mediated clot strength, with the inhibiting concentration required for 50% effect (IC50) = 70 n mol/l, whereas the IC50 of the class II antagonists such as the free acid forms of orbofiban, sibrafiban, lotrafiban, integrilin or aggrastat ranged from 1 to 15 micromol/l. The IC50s for class II antagonists in inhibiting platelet/fibrin clot formation and strength were substantially greater (10-15 fold) than their clinically achievable concentrations. The limited efficacy for class II antagonists in inhibiting platelet-mediated clot dynamics was enhanced by the combination with heparin. CONCLUSIONS Thus, these data indicated that there are differences in the efficacy of various GPIIb/IIIa antagonists in inhibiting platelet/fibrin clot formation and strength, which might be corrected by heparin. Data also suggest that inhibition of platelet aggregation may not be the sole determinant for the in-vivo efficacy of various GPIIb/IIIa antagonists.
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44
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Collet JP, Montalescot G, Lesty C, Weisel JW. A structural and dynamic investigation of the facilitating effect of glycoprotein IIb/IIIa inhibitors in dissolving platelet-rich clots. Circ Res 2002; 90:428-34. [PMID: 11884372 DOI: 10.1161/hh0402.105095] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors were shown recently to facilitate the rate and the extent of pharmacological thrombolysis. However, their synergistic potential with rtPA in dissolving thrombotic vaso-occlusions is not fully understood. We have therefore developed a dynamic and structural approach for analysis of fibrinolysis to assess the inhibiting effect of platelets and the facilitating effect of GPIIb/IIIa inhibitors in dissolving platelet-rich clots (PRCs). Fluorescent rtPA was used to study the architecture of PRCs, to follow the progression of the rtPA binding front, and to measure the lysis-front velocity using confocal microscopy. Fibrinolysis resistance of PRCs was related to a reduction of both rtPA binding and lysis-front velocities of platelet-rich areas compared with platelet-poor areas (2.4 +/- 0.2 versus 3.5 +/- 0.4 microm/min for rtPA binding velocity, P=0.04, and 1.2 +/- 0.6 versus 2.8 +/- 0.2 microm/min for lysis-front velocity, P=0.008, in platelet-rich and platelet-poor areas, respectively). Fibrinolysis appeared heterogeneous, leaving platelet-rich areas un-lysed. Adding pharmacological concentrations of abciximab (0.068 micromol/L) or eptifibatide (1 micromol/L) before clotting decreased the average surface of platelet-rich areas by 64% (P=0.0005) and 72% (P=0.0007), respectively. The resulting equalization of rtPA binding rate and rtPA binding-front velocity between platelet-rich and platelet-poor areas led to a 3-fold increase of the lysis-front velocity in platelet-rich areas of either abciximab-PRC (P=0.006) or eptifibatide-PRC (P=0.03). The overall lysis rate of treated-PRC was increased by 74% compared with control-PRC (P<0.01). These results demonstrate that fibrinolysis resistance of PRCs is related primarily to the heterogeneity in the clot structure between platelet-rich and platelet-poor areas. GP IIb/IIIa inhibitors facilitate the rate and the extent of fibrinolysis by improving rtPA binding velocity and, subsequently, the lysis rate in platelet-rich areas. These findings provide new insights on the synergistic potential of GP IIb/IIIa inhibitors and fibrinolytic agents.
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Affiliation(s)
- J Ph Collet
- Department of Cardiology, Pitié-Salpêtrière Hospital, Paris, France.
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45
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Shore-Lesserson L. Point-of-care coagulation monitoring for cardiovascular patients: past and present. J Cardiothorac Vasc Anesth 2002; 16:99-106. [PMID: 11854887 DOI: 10.1053/jcan.2002.29692] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Mousa SA, Forsythe MS. Comparison of the effect of different platelet GPIIb/IIa antagonists on the dynamics of platelet/fibrin-mediated clot strength induced using thromboelastography. Thromb Res 2001; 104:49-56. [PMID: 11583738 DOI: 10.1016/s0049-3848(01)00336-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of various platelet glycoprotein IIb/IIIa (GPIIb/IIIa) antagonists on the dynamics of platelet-fibrin clot formation and strength induced by various stimuli was measured by thromboelastography (TEG). GPIIb/IIIa antagonists with high affinity for resting and activated platelets and with slow rates of dissociation from GPIIb/IIIa (Class I antagonists) demonstrated potent and comparable inhibition of platelet aggregation and tissue factor (TF), lipopolysaccharide (LPS), Factor Xa, and thrombin-induced clot strength, in contrast to antagonists that dissociate rapidly from GPIIb/IIIa (Class II antagonists). For example, the Class I antagonist XV459 (the free acid form of roxifiban) inhibited TF, endotoxin, Factor Xa, and thrombin-induced maximal clot strength and platelet aggregation with an IC(50)=30-70 nM, whereas the IC(50) of the Class II antagonist YZ211 (the free acid form of sibrafiban) for altering clot formation and strength was 0.3-4.7 microM. Moreover, the IC(50)'s of sibrafiban, and another Class II antagonist, orbofiban, for inhibiting platelet-fibrin clot formation and strength were substantially greater than their clinically achievable concentrations. Further, although aspirin treatment improved the efficacy of all GPIIb/IIIa antagonists, it did not alter the differences between Classes I and II antagonists. Thus, these data indicate that there are differences in the efficacy of various GPIIb/IIIa antagonists in inhibiting platelet-fibrin clot formation and strength. They also suggest that inhibiting platelet aggregation may not be the sole determinant for the in vivo efficacy of various GPIIb/IIIa antagonists.
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Affiliation(s)
- S A Mousa
- Du Pont Pharmaceuticals Company, 141 & Henry Clay Road, Experimental Station, E400/3470, Wilmington, DE 19880-0400, USA.
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Catella-Lawson F, Kapoor S, Moretti D, De Marco S, Vigilante GJ, Cucchiara AJ, Ramsey KE, Combe S, Rocca B, Theroux P, FitzGerald GA. Oral glycoprotein IIb/IIIa antagonism in patients with coronary artery disease. Am J Cardiol 2001; 88:236-42. [PMID: 11472700 DOI: 10.1016/s0002-9149(01)01632-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Dose-finding studies and trials of interaction of oral glycoprotein IIb/IIIa antagonists with other antiplatelet agents have been limited. We hypothesized that these detailed assessments could be first performed in patients with stable coronary artery disease (CAD) and then extrapolated to the target population. To this end, we performed 2 sequential studies. The first study examined the dose-related effects on indexes of platelet and vascular function induced by the oral inhibitor RPR 109891, when given alone and in combination with aspirin, in patients (n = 100) with stable CAD. The second study (the Antagonism of the FIbrinogen Receptor after Myocardial Events trial) assessed the pharmacodynamics and safety of derived regimens in patients (n = 320) with unstable coronary syndromes. In patients with stable CAD, platelet aggregation was dose dependently inhibited by RPR 109891, and the dose-response relation was shifted to the right by the concomitant administration of aspirin (p = 0.0001). The degree of platelet inhibition induced by 3 doses of RPR 109891 (plus aspirin) was lower in patients with unstable than stable CAD. No drug-related major bleeding occurred in either study. RPR 109891 treatment was associated with acute and delayed thrombocytopenia. In conclusion, chronic treatment with an oral glycoprotein IIb/IIIa antagonist (1) induces antiplatelet effects that are potentiated by concomitant administration of aspirin, (2) may require dose adjustment in syndromes of platelet activation, (3) is associated with a low rate of clinically significant bleeding when doses inducing incomplete inhibition of platelet aggregation are used, and (4) requires frequent monitoring of platelet count unless reliable predictors of delayed thrombocytopenia become available.
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Affiliation(s)
- F Catella-Lawson
- EUPenn Group of Investigators at the Center for Experimental Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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Abstract
Platelet function tests measure different aspects of platelet function, which include adherence, activation, aggregation and secretion. Clinically, the goal of platelet function testing is to provide information about the platelet contribution to the risk of thrombotic or haemorrhagic events and the optimisation of antiplatelet therapy. The important clinical questions are whether an antiplatelet agent is having the desired effect on platelet inhibition (effectiveness) and whether the patient has sufficient residual platelet function to avoid bleeding (safety). The role of aspirin (acetylsalicylic acid) and thienopyridines is well established in the management of patients with coronary artery disease and in the setting of coronary interventions. The last several years have demonstrated the unequivocal effectiveness of intravenously administered platelet glycoprotein (GP) IIb/IIIa antagonists in the management of acute coronary syndromes and in the setting of percutaneous coronary interventions. With the increasing use of these GPIIb/IIIa antagonists, it is becoming more important clinically to measure platelet inhibition with these agents. This paper reviews major techniques and instrumentation for platelet monitoring and discusses the goals of the best method.
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Affiliation(s)
- D Mukherjee
- Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA
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Chapter 10. Antiplatelet therapies. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2000. [DOI: 10.1016/s0065-7743(00)35011-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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