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Athanasiou C, Cournia Z. From Computers to Bedside: Computational Chemistry Contributing to FDA Approval. BIOMOLECULAR SIMULATIONS IN STRUCTURE-BASED DRUG DISCOVERY 2018. [DOI: 10.1002/9783527806836.ch7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Christina Athanasiou
- Biomedical Research Foundation; Academy of Athens; 4 Soranou Ephessiou 11527 Athens Greece
| | - Zoe Cournia
- Biomedical Research Foundation; Academy of Athens; 4 Soranou Ephessiou 11527 Athens Greece
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2
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Abstract
The development of specific inhibitors of blood coagulation enzymes has led to a number of new anticoagulant/antithrombotic agents that could be useful for prophylaxis and/or treatment of thromboembolic disorders. Because thrombin is the central bioregulatory enzyme in hemostasis, blocking of the active site of the enzyme by a fast reaction with an inhibitor may effectively prevent intravascular coagulation as well as other important biological effects of thrombin. For the direct inactivation of thrombin, several classes of compounds have been developed and characterized in vitro and in vivo as potential antithrombotic agents including naturally occurring as well as synthetic thrombin inhibitors such as hirudin, hirulog, arginine (argatroban), and benzamidine (NAPAP) derivatives as well as tripeptide-type inhibitors (efegatran, D-Phe-Pro-Arg-CH2Cl, boroarginine derivatives). Experimental findings suggest that directly acting thrombin inhibitors may be effective in a wide range of arterial and venous thrombotic events. The important role of factor Xa in the coagulation cascade at the stage of the conversion of extrinsic and intrinsic pathways and the amplification of its procoagulant action by prothrombinase complex formation makes factor Xa a promising target also for antithrombotic drugs. Experimental studies on highly effective and selective factor Xa inhibitors (antistasin, tick anticoagulant peptide, yagin, DX-9065a) showed that inhibition of coagulation at a relatively early stage is a very effective way for the prevention of thrombotic processes. Furthermore, it is assumed that factor Xa inhibitors selectively inhibit thrombus formation without compromising hemostasis. In conclusion, both thrombin and factor Xa inhibitors are promising drugs for the management of thrombotic disorders. However, besides the strong inhibitory potency against the target enzyme, other pharmacological aspects such as pharmacodynamics, pharmacokinetics, and toxic side effects must be included in the evaluation of the potential usefulness of thrombin and factor Xa inhibitors for clinical indications. Key Words: Anticoagulants—Antithrombotics—Factor Xa inhibitors—Thrombin inhibitors.
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Affiliation(s)
- Brigitte Kaiser
- Friedrich Schiller University Jena, Faculty of Medicine, Center for Vascular Biology and Medicine Erfurt, Erfurt, Germany
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3
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Chen M, Ye X, Ming X, Chen Y, Wang Y, Su X, Su W, Kong Y. A Novel Direct Factor Xa Inhibitory Peptide with Anti-Platelet Aggregation Activity from Agkistrodon acutus Venom Hydrolysates. Sci Rep 2015; 5:10846. [PMID: 26035670 PMCID: PMC4451689 DOI: 10.1038/srep10846] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/05/2015] [Indexed: 11/15/2022] Open
Abstract
Snake venom is a natural substance that contains numerous bioactive proteins and peptides, nearly all of which have been identified over the last several decades. In this study, we subjected snake venom to enzymatic hydrolysis to identify previously unreported bioactive peptides. The novel peptide ACH-11 with the sequence LTFPRIVFVLG was identified with both FXa inhibition and anti-platelet aggregation activities. ACH-11 inhibited the catalytic function of FXa towards its substrate S-2222 via a mixed model with a Ki value of 9.02 μM and inhibited platelet aggregation induced by ADP and U46619 in a dose-dependent manner. Furthermore, ACH-11 exhibited potent antithrombotic activity in vivo. It reduced paralysis and death in an acute pulmonary thrombosis model by 90% and attenuated thrombosis weight in an arterio-venous shunt thrombosis model by 57.91%, both at a dose of 3 mg/kg. Additionally, a tail cutting bleeding time assay revealed that ACH-11 did not prolong bleeding time in mice at a dose of 3 mg/kg. Together, our results reveal that ACH-11 is a novel antithrombotic peptide exhibiting both FXa inhibition and anti-platelet aggregation activities, with a low bleeding risk. We believe that it could be a candidate or lead compound for new antithrombotic drug development.
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Affiliation(s)
- Meimei Chen
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Xiaohui Ye
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Xin Ming
- Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yahui Chen
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Ying Wang
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Xingli Su
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Wen Su
- School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China
| | - Yi Kong
- 1] School of Life Science &Technology, China Pharmaceutical University, 24 Tong Jia Street, Nanjing 210009, PR China [2] State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, PR China
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Tatterton M, Wilshaw SP, Ingham E, Homer-Vanniasinkam S. The use of antithrombotic therapies in reducing synthetic small-diameter vascular graft thrombosis. Vasc Endovascular Surg 2012; 46:212-22. [PMID: 22308212 DOI: 10.1177/1538574411433299] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Thrombosis of synthetic small-diameter bypass grafts remains a major problem. The aim of this article is to review the antithrombotic strategies that have been used in an attempt to reduce graft thrombogenicity. METHODS A PubMed/MEDLINE search was performed using the search terms "vascular graft thrombosis," "small-diameter graft thrombosis," "synthetic graft thrombosis" combined with "antithrombotic," "antiplatelet," "anticoagulant," "Dacron," "PTFE," and "polyurethane." RESULTS The majority of studies on antithrombotic therapies have used either in vitro models or in vivo animal experiments. Many of the therapies used in these settings do show antithrombotic efficacy against synthetic graft materials. There is however, a distinct lack of human in vivo studies to further delineate the performance and limitations of therapies displaying good antithrombotic characteristics. CONCLUSION Very few antithrombotic therapies have translated into clinical use. More human in vivo studies are required to assess the efficacy and safety of such therapies.
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Affiliation(s)
- Mark Tatterton
- Leeds Vascular Institute, Leeds General Infirmary, Leeds, Yorkshire, UK.
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5
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Zhang P, Huang W, Wang L, Bao L, Jia ZJ, Bauer SM, Goldman EA, Probst GD, Song Y, Su T, Fan J, Wu Y, Li W, Woolfrey J, Sinha U, Wong PW, Edwards ST, Arfsten AE, Clizbe LA, Kanter J, Pandey A, Park G, Hutchaleelaha A, Lambing JL, Hollenbach SJ, Scarborough RM, Zhu BY. Discovery of betrixaban (PRT054021), N-(5-chloropyridin-2-yl)-2-(4-(N,N-dimethylcarbamimidoyl)benzamido)-5-methoxybenzamide, a highly potent, selective, and orally efficacious factor Xa inhibitor. Bioorg Med Chem Lett 2009; 19:2179-85. [DOI: 10.1016/j.bmcl.2009.02.111] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
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6
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Zhang P, Bao L, Fan J, Jia ZJ, Sinha U, Wong PW, Park G, Hutchaleelaha A, Scarborough RM, Zhu BY. Anthranilamide-based N,N-dialkylbenzamidines as potent and orally bioavailable factor Xa inhibitors: P4 SAR. Bioorg Med Chem Lett 2009; 19:2186-9. [DOI: 10.1016/j.bmcl.2009.02.114] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 11/29/2022]
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7
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Rezaie AR. Heparin chain-length dependence of factor Xa inhibition by antithrombin in plasma. Thromb Res 2006; 119:481-8. [PMID: 16515805 DOI: 10.1016/j.thromres.2006.01.009] [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] [Received: 11/30/2005] [Revised: 11/30/2005] [Accepted: 01/23/2006] [Indexed: 11/30/2022]
Abstract
Heparin anticoagulants function by enhancing the inhibition of coagulation proteases by the serpin antithrombin (AT). A direct evaluation of the specific anti-factor Xa (fXa) activity of therapeutic heparins in the physiologically relevant plasma-based clotting assays has not been feasible since thrombin, the final protease of the cascade, is the primary target for inhibition by AT in the presence of heparin. To circumvent this problem, we developed an assay in which the native AT in plasma was replaced with an AT mutant which exhibits identical affinity for heparin and near normal reactivity for fXa, but does not react with thrombin and other coagulation proteases in either the absence or presence of heparin. This assay was used to distinguish the anti-fXa activity of different molecular weight heparins from their anti-thrombin activity in clotting assays which were initiated by the triggers of either the extrinsic or intrinsic coagulation pathway. The results suggest that the acceleration of fXa inhibition by AT exhibits a marked heparin chain-length dependence, with fondaparinux (a pentasaccharide) having the lowest and unfractionated heparin having the highest effect. Interestingly, comparative studies revealed that the fondaparinux-catalyzed acceleration of thrombin inhibition by AT also contributes to the prolongation of the clotting time, possibly suggesting that the anticoagulant function of the therapeutic pentasaccharide is mediated though the inhibition of both fXa and thrombin.
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Affiliation(s)
- Alireza R Rezaie
- Edward A Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO 63104, USA.
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8
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Faria F, Junqueira-de-Azevedo IDLM, Ho PL, Sampaio MU, Chudzinski-Tavassi AM. Gene expression in the salivary complexes from Haementeria depressa leech through the generation of expressed sequence tags. Gene 2005; 349:173-85. [PMID: 15777719 DOI: 10.1016/j.gene.2004.12.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 11/15/2004] [Accepted: 12/15/2004] [Indexed: 10/25/2022]
Abstract
A survey of the transcriptional profile of Haementeria depressa Ringuelet, 1972 (Annelida, Hirudinea) salivary complexes was produced through expressed sequence tag (EST). Sequences from 898 independent clones were assembled in 555 clusters, representing the transcript profile of this tissue. The repertoire of possible proteins involved in feeding and host interaction processes of the leech corresponded to 10.6% of all identified transcripts (67 clusters), being the carbonic anhydrases (30%), several coagulation inhibitors (25%) and hemerythrin-like molecules (19%), the major components. Among the 387 clusters matching cellular proteins, the majority represents molecules involved in gene and protein expression, reflecting a high specialization of this tissue for protein synthesis. Our H. depressa dbEST was also compared to those from other blood-feeding organisms, providing evidences that among the secreted proteins, the coagulation inhibitors present a profile very characteristic of this animal class.
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Affiliation(s)
- Fernanda Faria
- Laboratório de Bioquímica e Biofísica, Instituto Butantan, Av. Vital Brazil, 1500, CEP: 05503-900, São Paulo, Brazil
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Hirayama F, Koshio H, Katayama N, Kurihara H, Taniuchi Y, Sato K, Hisamichi N, Sakai-Moritani Y, Kawasaki T, Matsumoto Y, Yanagisawa I. The discovery of YM-60828: a potent, selective and orally-bioavailable factor Xa inhibitor. Bioorg Med Chem 2002; 10:1509-23. [PMID: 11886813 DOI: 10.1016/s0968-0896(01)00418-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Since Factor Xa (FXa) is well known to play a central role in thrombosis and hemostasis, inhibition of FXa is an attractive target for antithrombotic strategies. As a part of our investigation of a non-peptide, orally available FXa inhibitor, we found that a series of N-[(7-amidino-2-naphthyl)methyl]aniline derivatives possessed potent and selective inhibitory activities. Structure--activity relationship (SAR) of the substituent (R(1)) on the central aniline moiety suggested that increasing lipophilicity caused a detrimental effect on anticoagulant activity (prothrombin time assay) in plasma. Several compounds bearing a hydrophilic substituent in R(1) showed not only potent FXa inhibitory activities but also high anticoagulant activities. The best compound in this series was sulfamoylacetic acid derivative (YM-60828) which was a potent, selective and orally bioavailable FXa inhibitor and was chosen for clinical development.
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Affiliation(s)
- Fukushi Hirayama
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., 21Miyukigaoka, Tsukuba, Ibaraki 305-8585, Japan.
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10
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Abstract
The normal hemostatic process is initiated by disruption in the vascular continuity and exposure of the subendothelial components. Platelets adhere to subendothelium-bound von Willebrand factor via glycoprotein (GP) Ib complex. This initial interaction per se and the release of platelet agonists transduce signals that lead to the rise in intracellular Ca(2+). The rise in Ca(2+) induces shape change, prostaglandin synthesis, release of granular contents and conformational changes in platelet Gp IIb-IIIa. Gp IIb-IIIa in activated platelets becomes competent to bind fibrinogen and other adhesive proteins and mediates platelet cohesion (primary hemostatic plug). Furthermore, the activated platelet surface provides an efficient catalytic surface for the coagulation reactions, ultimately resulting in the formation of fibrin (secondary hemostasis). Normally the hemostatic process plays a delicate balance between keeping the blood in the fluid state to maintain flow and rapidly forming an occluding plug following vessel injury. Thrombosis occurs because of alteration in this delicate balance. Consequences of thrombosis are a major cause of morbidity and mortality in industrialized countries. Arterial thrombosis occurs in the setting of previous vessel wall injury mostly because of atherosclerosis, while venous thrombosis occurs in areas of stasis. The recent advances in our understanding of the hemostatic process have led to a better elucidation of the mechanism of action of many antithrombotic drugs and identification of new targets for drug development. The molecular target of the well known antiplatelet drug ticlopidine has been identified. Large numbers of IIb-IIIa inhibitors have been developed based on the crystal structure of a potent antagonist echistatin. The mechanism of action of heparin has been defined at the molecular level. As a result a synthetic pentasaccharide, based on antithrombin-binding domain of heparin, has been developed and tested successfully in clinical trials. New generation direct thrombin inhibitors are being developed based on the crystal structure of thrombin. Factor Xa has a critical position at the convergence of intrinsic and extrinsic pathway ways. The clinical tolerability and the efficacy of low molecular weight heparins led to the concept that inhibition of further thrombin generation, by blocking factor Xa alone, can be an effective way of preventing thrombus growth without inactivating thrombin. A large number of specific factor Xa inhibitors are under development. Some of these drugs have already undergone preliminary clinical trials and appear to be promising. Future clinical trials will determine whether these new drugs will provide better risk-benefit ratio in treatment of thrombotic disorders.
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Affiliation(s)
- Perumal Thiagarajan
- Department of Pathology and Medicine (Thrombosis Research), Baylor College of Medicine, Houston, Texas 77030, USA.
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Sakariassen KS, Hanson SR, Cadroy Y. Methods and models to evaluate shear-dependent and surface reactivity-dependent antithrombotic efficacy. Thromb Res 2001; 104:149-74. [PMID: 11672758 DOI: 10.1016/s0049-3848(01)00344-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The purpose of the present communication is to evaluate the importance of blood flow and surface reactivity for measurement of antithrombotic drug activity or efficacy in selected model systems of thrombus formation. Such information is essential for proper evaluation of antithrombotic drug profiles. The continuous development of flow-dependent thrombosis models for in vitro (anticoagulated blood) and ex vivo (native blood) studies and their application in in vivo animal models from the early 1970s and onwards are briefly considered. Central to this process was the development of various types of perfusion chambers in which a thrombogenic surface is exposed to flowing blood. Such perfusion chambers have been inserted into arteriovenous (AV) shunts in baboon, pig, dog, and rabbit. These approaches have allowed reproducible testing of traditional and novel experimental antithrombotic drugs, and studies on novel drug strategies under well-defined shear conditions and surface reactivity. Shear-dependent antithrombotic efficacy in these models is observed with anticoagulants such as unfractionated heparin, low-molecular weight heparins, or selective inhibitors of thrombin, Factor Xa, or Factor VIIa. However, the degree of shear dependency depends on the nature of the thrombogenic surface, e.g., the inhibition is more pronounced on a tissue factor (TF)-rich surface than on a collagen-rich surface, particularly at venous or low arterial shear. Platelet antagonists such as the COX-1 inhibitor aspirin, inhibitors of thromboxane A2 (TxA2) synthetase, the TxA2 platelet receptor, and of von Willebrand factor (vWf) are shear dependent also, being more efficient at high arterial shear. In contrast, the platelet ADP antagonist clopidogrel, or antagonists to the active platelet membrane glycoprotein IIb-IIIa complex (GPIIb-IIIa) are shear independent. At extremely high arterial shear, which activates platelets and elicit aggregates of circulating platelets, aspirin looses its antithrombotic effect, whereas ADP and GPIIb-IIIa antagonists still interrupt thrombus formation. In general, results obtained with these models mimic and predict antithrombotic efficacy in man when comparison is possible. Information on antithrombotic efficacy in flow devices with various thrombogenic surfaces is now sufficiently available to suggest recommendations for experimental conditions, particularly with regard to blood flow and reactive surfaces.
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Affiliation(s)
- K S Sakariassen
- Department of Lead Pharmacology, Pharmacia Corporation, Uppsala and Stockholm, Sweden.
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12
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Abstract
The complementary roles of platelets and thrombin in the pathophysiology of acute coronary syndromes suggests that for treatment to be effective, both mediators must be targeted. Although great strides have been made in the development of antiplatelet therapies, attempts to inhibit thrombin have been less successful. Unfractionated heparin is limited by a number of pharmacologic shortcomings as well as an inability to meaningfully suppress thrombin generation. The low molecular weight heparins have yielded encouraging results in large-scale clinical trials, but it remains unclear whether their benefit stems from a superior pharmacologic profile to unfractionated heparin or is determined by an enhanced ability to suppress thrombin generation (by virtue of a direct anti-Xa effect). Regardless, investigators have become increasingly interested in factor Xa as a potential target for antithrombotic therapy. A number of naturally occurring Xa antagonists have been identified. Work with recombinant forms of these proteins confirms that factor Xa inhibition can suppress thrombin generation in a variety of animal thrombosis models. Accordingly, a number of synthetic direct and indirect Xa antagonists are under development for the prevention and treatment of thrombotic disorders. The following review summarizes the evolution of factor Xa antagonists.
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Affiliation(s)
- F A Spencer
- Cardiovascular Thrombosis Research Center, UMass Memorial Medical Center, 55 Lake Avenue North, Worcester, MA 01655, USA
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13
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Rebello SS, Blank HS, Lucchesi BR. Antithrombotic efficacy of single subcutaneous administration of a recombinant nematode anticoagulant peptide (rNAP5) in a canine model of coronary artery thrombolysis. Thromb Res 2000; 98:531-40. [PMID: 10899352 DOI: 10.1016/s0049-3848(00)00210-3] [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: 11/24/2022]
Abstract
We examined the adjunctive benefit of recombinant nematode anticoagulant peptide (rNAP5), a factor Xa inhibitor, in a canine model of recombinant (rt)-PA-induced thrombolysis. In anesthetized dogs, a stable occlusive thrombus was formed by electrolytic injury of the vessel wall, after which the animals were administered rt-PA (1.44 mg/kg, i.v.) and rNAP5 (0.1 mg/kg, s.c.: n=13), or rt-PA plus vehicle (1-2 ml, s.c.; n=13). Hemodynamic and coagulation parameters were monitored for 360 minutes. Single subcutaneous administration of rNAP5 resulted in a prolonged and sustained increase in the activated partial thromboplastin time (>100-fold), whereas prothrombin time was unchanged. The template bleeding time was not altered significantly throughout the protocol (maximum 1.4-fold). The incidence of reperfusion was similar in the two groups with a trend toward faster reperfusion in the rNAP5 group (34+/-4 minutes) compared to the vehicle group (63+/-15 minutes; p=0.07). After reperfusion, 80% of the vessels in the vehicle group reoccluded, whereas only 14% of vessels reoccluded in the rNAP5-treated group. Times to reocclusion were 65+/-21 minutes and 221+/-28 minutes, respectively (p<0.05). Single subcutaneous administration of rNAP5 sustained the coronary artery blood flow after reperfusion, such that at the end of protocol the flow was 47% of the preocclusion value as compared to the vehicle group in which the flow was 11% (p<0.05). Cyclic flow reductions were most prominent during rt-PA-induced reperfusion and were similar in both groups. The results indicate that a single subcutaneous administration of rNAP5 provides a sustained antithrombotic effect in maintaining the coronary artery patency during rt-PA-induced thrombolysis.
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Affiliation(s)
- S S Rebello
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, USA.
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14
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Wiley MR, Weir LC, Briggs S, Bryan NA, Buben J, Campbell C, Chirgadze NY, Conrad RC, Craft TJ, Ficorilli JV, Franciskovich JB, Froelich LL, Gifford-Moore DS, Goodson T, Herron DK, Klimkowski VJ, Kurz KD, Kyle JA, Masters JJ, Ratz AM, Milot G, Shuman RT, Smith T, Smith GF, Tebbe AL, Tinsley JM. Structure-based design of potent, amidine-derived inhibitors of factor Xa: evaluation of selectivity, anticoagulant activity, and antithrombotic activity. J Med Chem 2000; 43:883-99. [PMID: 10715155 DOI: 10.1021/jm9903287] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To enhance the potency of 1,2-dibenzamidobenzene-derived inhibitors of factor Xa (fXa), an amidine substituent was incorporated on one of the benzoyl side chains to interact with Asp189 in the S1 specificity pocket. Lead molecule 1 was docked into the active site of fXa to facilitate inhibitor design. Subsequently, iterative SAR studies and molecular modeling led to a 1000-fold increase in fXa affinity and a refined model of the new inhibitors in the fXa active site. Strong support for the computational model was achieved through the acquisition of an X-ray crystal structure using thrombin as a surrogate protein. The amidines in this series show high levels of selectivity for the inhibition of fXa relative to other trypsin-like serine proteases. Furthermore, the fXa affinity of compounds in this series (K(ass) = 50-500 x 10(6) L/mol) translates effectively into both anticoagulant activity in vitro and antithrombotic activity in vivo.
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Affiliation(s)
- M R Wiley
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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15
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Leadley RJ, Morgan SR, Bentley R, Bostwick JS, Kasiewski CJ, Heran C, Chu V, Brown K, Moxey P, Ewing WR, Pauls H, Spada AP, Perrone MH, Dunwiddie CT. Pharmacodynamic activity and antithrombotic efficacy of RPR120844, a novel inhibitor of coagulation factor Xa. J Cardiovasc Pharmacol 1999; 34:791-9. [PMID: 10598121 DOI: 10.1097/00005344-199912000-00004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
These studies were designed to examine the pharmacodynamic profile and antithrombotic efficacy of RPR120844, a competitive inhibitor of coagulation factor Xa, with a K(i) of 7 nM against human factor Xa. In vitro, RPR120844 doubled activated partial thromboplastin time (APTT) at concentrations of 1.54, 1.48, and 0.74 microM in plasma obtained from humans, dogs, and rats, respectively. Intravenous bolus administration of RPR 120844 at 0.3, 1, and 3 mg/kg to rats resulted in maximal increases in APTT of 1.8-, 2.6-, and 8.4-fold over baseline, respectively. The effect on prothrombin time (PT) was less pronounced, resulting in a 4.4-fold increase at 3 mg/kg. These effects were rapidly reversible; APTT and PT returned to control values by 30 min after dosing. Intragastric administration to rats at 50, 100, and 200 mg/kg resulted in modest increases in APTT and PT of 1.5- and 1.3-fold over baseline at the highest dose. Plasma levels were estimated by anti-Xa activity by using an amidolytic, chromogenic assay. Plasma levels were 0.65, 1.29, and 2.45 microM at 30 min after dosing at 50, 100, and 200 mg/kg, respectively. Intravenous administration to dogs at 0.1 and 0.3 mg/kg produced maximal increases in APTT of 1.7- and 2.4-fold over baseline, respectively. Intragastric administration to dogs at 50 mg/kg resulted in maximal increases in APTT and PT of 1.7- and 1.1-fold over baseline, with peak plasma levels of 3.9 microM observed at 15 min after dosing. In a rat model of FeCl2-induced carotid artery thrombosis, RPR120844 (3 mg/kg, i.v. bolus + 300 microg/kg/min constant infusion; n = 4) significantly increased time-to-occlusion from 18+/-1 min (vehicle, n = 4) to 60 min (maximal observation time) and reduced thrombus mass from 5.5 +/- 0.2 mg (vehicle) to 1.4 +/- 0.2 mg. These results indicate that RPR120844 is a potent, selective inhibitor of Xa that exhibits oral activity and is efficacious in a standard model of arterial thrombosis.
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Affiliation(s)
- R J Leadley
- Cardiovascular Drug Discovery, Rhône-Poulenc Rorer International, Collegeville, Pennsylvania 19426, USA.
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Scarborough RM. Coagulation factor Xa: the prothrombinase complex as an emerging therapeutic target for small molecule inhibitors. JOURNAL OF ENZYME INHIBITION 1999; 14:15-25. [PMID: 10520757 DOI: 10.3109/14756369809036543] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- R M Scarborough
- Medicinal Chemistry Research, COR Therapeutics Inc., South San Francisco, CA 94080, USA.
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Sato K, Kaku S, Hirayama F, Koshio H, Matsumoto Y, Kawasaki T, Iizumi Y. Antithrombotic effect of YM-75466 is separated from its effect on bleeding time and coagulation time. Eur J Pharmacol 1998; 352:59-63. [PMID: 9718268 DOI: 10.1016/s0014-2999(98)00339-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The antithrombotic effects of YM-75466 ([N-[4-[(1-acetimidoyl-4-piperidyl)oxy]phenyl]-N-[(7-amidino-2-nap hthyl)methyl]sulfamoyl]acetic acid monomethane sulfonate), a novel orally-active factor Xa inhibitor, and its effects on bleeding time and coagulation time were studied in rats and compared with those of warfarin. Both agents were orally administered. In the venous thrombosis model, YM-75466 and warfarin inhibited thrombus formation dose-dependently, with ID50 values of 3.3 and 0.56 mg/kg, respectively. Ex vivo study showed that both YM-75466 and warfarin prolonged prothrombin time dose-dependently, with doses, causing a two-fold prolongation of prothrombin time in the control group, of 89 and 0.38 mg/kg, respectively. In bleeding time studies, YM-75466 and warfarin prolonged bleeding time dose-dependently, with doses, causing a two-fold prolongation of bleeding time in the control group, of > 100 and 0.43 mg/kg, respectively. These results show that the antithrombotic effects of YM-75466 are markedly separate from its effects on bleeding time and coagulation time compared with warfarin.
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Affiliation(s)
- K Sato
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical, Tsukuba, Ibaraki, Japan.
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Abstract
This paper reviews the importance of blood flow phenomena in models of experimental thrombosis used for measuring antithrombotic drug efficacy. The characteristics of these systems and their application for studies with human blood and in animal models are considered. Central to these investigations has been the development of various types of perfusion chambers in which a thrombogenic test surface is exposed to flowing blood under well-defined conditions of blood flow and device geometry. Such perfusion chambers, which have been used in vitro, ex vivo, and in vivo by insertion into arteriovenous shunts in various animal species, have allowed reproducible testing of both conventional and experimental agents. Shear-dependent antithrombotic effects have been observed with anticoagulants such as heparin and with selective inhibitors of thrombin, factor Xa, and factor VIIa. However, the degree of shear dependency depends on the chemical composition of the thrombogenic surface; for example, anticoagulant effects may be more pronounced on a tissue factor-rich surface than on a collagen-rich surface, particularly at venous or low arterial shear rates. Platelet inhibitors such as aspirin, thromboxane antagonists, or inhibitors of von Willebrand factor platelet interactions are also shear dependent, being more efficient at high shear rates. In contrast, inhibitors of adenosine diphosphate-dependent platelet reactions or antagonists of the platelet membrane glycoprotein IIb/IIIa complex are shear rate independent. At very high shear rates characteristic of severely stenotic arteries, aspirin loses its direct antithrombotic effect, whereas adenosine diphosphate pathway inhibitors and GP IIb/IIIa antagonists are still beneficial. In general, results obtained with many of these models have predicted antithrombotic efficacy in human beings when comparisons were possible. Therefore shear-dependent models of experimental thrombosis are routinely used in the evaluation of antithrombotic pharmacologic agents, both preclinically and clinically.
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Affiliation(s)
- S R Hanson
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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Sato K, Kawasaki T, Hisamichi N, Taniuchi Y, Hirayama F, Koshio H, Matsumoto Y. Antithrombotic effects of YM-60828, a newly synthesized factor Xa inhibitor, in rat thrombosis models and its effects on bleeding time. Br J Pharmacol 1998; 123:92-6. [PMID: 9484858 PMCID: PMC1565130 DOI: 10.1038/sj.bjp.0701566] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. The effects of YM-60828, a newly synthesized factor Xa inhibitor, were investigated to analyse the relationship between its antithrombotic effects and its prolongation of template bleeding time in rats. YM-60828 was compared with argatroban, heparin and dalteparin. All agents were intravenously administered as a bolus. 2. In ex vivo studies, YM-60828 and argatroban prolonged both prothrombin time and activated partial thromboplastin time in a dose-dependent manner, while heparin and dalteparin prolonged only activated partial thromboplastin time. 3. In a venous thrombosis model, all agents exerted antithrombotic effects in a dose-dependent manner. The ID50 values of YM-60828, argatroban, heparin and dalteparin were 0.0081 mg kg(-1), 0.011 mg kg(-1), 6.3 iu kg(-1) and 4.7 iu kg(-1), respectively. 4. In an arterio-venous shunt model, all agents exerted antithrombotic effects in a dose-dependent manner. The ID50 values of YM-60828, argatroban, heparin and dalteparin were 0.010 mg kg(-1), 0.011 mg kg(-1), 10 iu kg(-1) and 4.2 iu kg(-1), respectively. 5. In bleeding time studies, all agents prolonged template bleeding time in a dose-dependent manner. ED2 values, the doses causing a 2 fold prolongation of bleeding time in the saline group, of YM-60828, argatroban, heparin and dalteparin were 0.76 mg kg(-1), 0.081 mg kg(-1), 18 iu kg(-1) and 25 iu kg(-1), respectively. 6. The ratio (ED2/ID50) of YM-60828 was more than 30 fold greater than that of heparin and more than 10 fold greater than those of argatroban and dalteparin. 7. These data show that YM-60828 can exert its antithrombotic effects with little prolongation of bleeding time compared with the other currently used anticoagulant agents.
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Affiliation(s)
- K Sato
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co. Ltd, Tsukuba, Ibaraki, Japan
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Sato K, Kawasaki T, Taniuchi Y, Hirayama F, Koshio H, Matsumoto Y. YM-60828, a novel factor Xa inhibitor: separation of its antithrombotic effects from its prolongation of bleeding time. Eur J Pharmacol 1997; 339:141-6. [PMID: 9473127 DOI: 10.1016/s0014-2999(97)01389-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The antithrombotic effects of intravenous infusions of YM-60828 ([N-[4-[(1-acetimidoyl-4-piperidyl)oxy]phenyl]-N-[(7-amidino-2-nap hthyl)methyl]sulfamoyl]acetic acid dihydrochloride), a novel factor Xa inhibitor, argatroban, heparin and dalteparin in an arterio-venous shunt model were studied in comparison with their effects on template bleeding time. In an arterio-venous shunt model, all agents exerted antithrombotic effects in a dose-dependent manner. ID50 values of YM-60828, argatroban, heparin and dalteparin were 0.0087 mg/kg/h. 0.027 mg/kg/h, 22 IU/kg/h and 11 IU/kg/h, respectively. In bleeding time studies, all agents prolonged bleeding time in a dose-dependent manner. Doses (ED2) of YM-60828, argatroban, heparin and dalteparin, which caused 2-fold prolongation of bleeding time in the saline group, were 3.0 mg/kg/h, 0.25 mg/kg/h, 18 IU/kg/h and 26 IU/kg/h. respectively. The risk-benefit ratio (ED2/ID50) of YM-60828 was much greater than that of the other agents. These data suggest that the antithrombotic effect of YM-60828 is separate from its prolongation of bleeding time and that YM-60828 is much safer than conventional anticoagulant agents.
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Affiliation(s)
- K Sato
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Tsukuba, Ibaraki, Japan.
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Rubin BG, Toursarkissian B, Petrinec D, Yang LY, Eisenberg PR, Abendschein DR. Preincubation of Dacron grafts with recombinant tissue factor pathway inhibitor decreases their thrombogenicity in vivo. J Vasc Surg 1996; 24:865-70. [PMID: 8918335 DOI: 10.1016/s0741-5214(96)70024-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND We have previously shown that preincubation of whole blood clots with recombinants tissue factor pathway inhibitor (rTFPI) attenuates clot-associated procoagulant activity assessed ex vivo. This study was undertaken to determine whether a single local application of rTFPI induces similar attenuation of the procoagulant activity on preclotted Dacron grafts implanted in an artery in vivo. METHODS Dacron grafts (4 mm x 4 cm long) were preclotted in porcine blood and incubated with either rTFPI (5 mg/ml) or arginine-phosphate buffer for 15 minutes. Grafts were implanted end-to-end in the femoral arteries of 10 pigs, with one rTFPI-treated and one buffer-treated graft implanted in each animal. Animals did not undergo anticoagulation either before or after graft implantation. Radiolabeled porcine fibrinogen was injected intravenously, and the grafts underwent perfusion for 1 hour. A subgroup of animals (n = 7) also had infusion of radiolabeled autologous platelets at the time of administration of radiolabeled fibrinogen. RESULTS Fibrin(ogen) deposition was decreased in rTFPI-treated grafts by 36% +/- 7% (mean +/- SEM) compared with buffer-treated grafts (p = 0.001). Platelet deposition was also reduced in the rTFPI-treated grafts by 31% +/- 15%, although the reduction did not reach statistical significance (p = 0.10). The extent of rTFPI-mediated attenuation of fibrin(ogen) versus platelet deposition varied independently among animals. CONCLUSIONS Clot-directed anticoagulant effects of rTFPI appear to be useful for substantially decreasing the thrombogenicity of Dacron grafts immediately after their implantation. Chronic studies to determine whether the decreases in thrombogenicity result in improved long-term graft patency appear warranted.
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Affiliation(s)
- B G Rubin
- Department of Surgery, Washington University, St Louis, MO 63110, USA
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Abstract
Platelet activation plays a critical role in thromboembolic disorders, and aspirin remains a keystone in preventive strategies. This remarkable efficacy is rather unexpected, as aspirin selectively inhibits platelet aggregation mediated through activation of the arachidonic-thromboxane pathway, but not platelet aggregation induced by adenosine diphosphate (ADP), collagen and low levels of thrombin. This apparent paradox has stimulated investigations on the effect of aspirin on eicosanoid-independent effects of aspirin on cellular signalling. It has also fostered the search for antiplatelet drugs inhibiting platelet aggregation at other levels than the acetylation of platelet cyclo-oxygenase, such as thromboxane synthase inhibitors and thromboxane receptor antagonists. The final step of all platelet agonists is the functional expression of glycoprotein (GP) IIb/IIIa on the platelet surface, which ligates fibrinogen to link platelets together as part of the aggregation process. Agents that interact between GPIIb/IIIa and fibrinogen have been developed, which block GPIIb/IIIa, such as monoclonal antibodies to GPIIb/IIIa, and natural and synthetic peptides (disintegrins) containing the Arg-Gly-Asp (RGD) recognition sequence in fibrinogen and other adhesion macromolecules. Also, some non-peptide RGD mimetics have been developed which are orally active prodrugs. Stable analogues of prostacyclin, some of which are orally active, are also available. Thrombin has a pivotal role in both platelet activation and fibrin generation. In addition to natural and recombinant human antithrombin III, direct antithrombin III-independent thrombin inhibitors have been developed as recombinant hirudin, hirulog, argatroban, boroarginine derivatives and single stranded DNA oligonucleotides (aptanes). Direct thrombin inhibitors do not affect thrombin generation and may leave some 'escaping' thrombin molecules unaffected. Inhibition of factor Xa can prevent thrombin generation and disrupt the thrombin feedback loop that amplifies thrombin production.
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Affiliation(s)
- M Verstraete
- Center for Molecular and Vascular Biology, University of Leuven, Belgium
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Ripka W, Brunck T, Stanssens P, LaRoche Y, Lauwereys M, Lambeir AM, Lasters I, DeMaeyer M, Vlasuk G, Levy O, Miller T, Webb T, Tamura S, Pearson D. Strategies in the Design of Inhibitors of Serine Proteases of the Coagulation Cascade - Factor Xa. Eur J Med Chem 1995. [DOI: 10.1016/s0223-5234(23)00116-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Kaiser B, Hauptmann J. Factor Xa Inhibitors as Novel Antithrombotic Agents: Facts and Perspectives. ACTA ACUST UNITED AC 1994. [DOI: 10.1111/j.1527-3466.1994.tb00207.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Söllner C, Mentele R, Eckerskorn C, Fritz H, Sommerhoff CP. Isolation and characterization of hirustasin, an antistasin-type serine-proteinase inhibitor from the medical leech Hirudo medicinalis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:937-43. [PMID: 8112345 DOI: 10.1111/j.1432-1033.1994.tb18575.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Antistasin, a potent inhibitor of the blood coagulation factor Xa, is the prototype of a novel family of serine-proteinase inhibitors. We have now isolated, sequenced and characterized an antistasin-type inhibitor from the medical leech Hirudo medicinalis. Hirustasin (Hirudo antistasin) was purified to apparent homogeneity by cation-exchange and affinity chromatography. Amino acid sequencing of the 55 amino acid protein (M(r) 5866) revealed that hirustasin is the only antistasin-type protein known to consist of one domain only; 27% and 32% sequence identity was found to the first and second domains of antistasin, respectively, and a nearly exact conservation of the spacing of the ten cysteine residues. Hirustasin is the first inhibitor of tissue kallikrein identified in leeches, and is also a tight-binding inhibitor of trypsin, chymotrypsin and neutrophil cathepsin G. However, despite the high similarity to antistasin, particularly in the vicinity of the putative reactive-site peptide bond, hirustasin neither inhibits blood coagulation in vitro nor amidolytic activity of isolated factor Xa. Thus, structural elements other than the reactive site sequence significantly influence the specificity of antistasin-type proteinase inhibitors.
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Affiliation(s)
- C Söllner
- Abteilung für Klinische Chemie und Klinische Biochemie, Klinikum Innenstadt, Ludwig-Maximilians-Universität, München, Germany
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Hauptmann J, Kaiser B. Anticoagulant and antithrombotic action of the factor Xa inhibitor antistasin (ATS). Thromb Res 1993; 71:169-74. [PMID: 8362380 DOI: 10.1016/0049-3848(93)90183-o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J Hauptmann
- Institute of Pharmacology and Toxicology, Erfurt Medical School, FRG
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