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Abstract
Generation of plasmin in the vicinity of a blood clot has proven to be an effective approach for treating thrombotic disorders, particularly myocardial infarction. Conceptually, the ideal thrombolytic agent would initiate the formation of plasmin, primarily in association with fibrin incorporated into the occlusive thrombus. Thus, thrombolytic agents that exhibit relative fibrin specificity and, thus, presumably clot selectivity (e.g., tissue plasminogen activator) were expected to have a marked clinical benefit compared to agents that do not display affinity for fibrin (e.g., streptokinase). However, results obtained recently from clinical trials indicate that these 2 agents essentially were equally effective in treating myocardial infarction. With these findings in mind, efforts are being made to develop novel thrombolytic agents that might achieve more rapid and specific thrombolysis than that achieved by presently available agents and, thus, could be administered earlier because of an improved margin of safety. The available data suggest that tissue-type PA (tPA) mutants possessing resistance to endogenous inhibitors, altered fibrin affinity, and/or slower rates of clearance may prove beneficial in this regard. In addition, adjunctive therapies (i.e., anti-platelet and anti-thrombin compounds) have been found to decrease the time necessary to achieve reperfusion and have reduced rates of reocclusion. These efforts are expected to yield therapeutic agents in the 1990s and beyond that, when administered in combination, would exhibit increased efficacy in the treatment of myocardial infarction and other thrombotic disorders.
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Affiliation(s)
- Laurence A. Erickson
- Cardiovascular Diseases and Molecular Biology Research, Upjohn Laboratories, Kalamazoo, Michigan
| | - Keith R. Marotti
- Cardiovascular Diseases and Molecular Biology Research, Upjohn Laboratories, Kalamazoo, Michigan
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2
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May K, Planterose DN, Browne MJ, Perkins RM. Development of a Novel Marker Gene Based Assay System for Detection and Evaluation of Antiviral Agents with Activity against Papillomaviruses. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/095632029100200605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A novel assay system has been developed in which expression of a human tissue-plasminogen activator (t-PA) gene, carried on a recombinant papillomavirus vector, is used as a marker for the presence of bovine papillomavirus type 1 (BPV-1) within transformed mouse C127 cells. This provides a relatively quick and simple means of identifying and evaluating agents with anti-papillomavirus activity. Using this system the antiviral activity and cytotoxicity of interferon and retinoic acid, have been investigated. After seven subcultures in the presence of 200 Units ml−1 mouse α and β interferon, t-PA expression was completely inhibited, with a concurrent alteration in cellular morphology, and restoration of contact inhibition. In accordance with the problems encountered with interferon therapy of human papillomavirus infections, these effects were dependent on the continued presence of interferon, its removal leading to a rapid return of t-PA expression, and reversion of cells to the transformed phenotype. In comparison, 2.0 μg ml−1 retinoic acid partially reduced t-PA expression (this effect was largely maintained even after removal of the inhibiting compound) but did not affect the transformed cell phenotype. These results are discussed in relation to other in vitro studies and also to the clinical treatment of human papillomavirus (HPV) disease.
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Affiliation(s)
- K. May
- SmithKline Beecham Pharmaceuticals Research Division, Epsom, Surrey, KT18 5XQ, UK
| | - D. N. Planterose
- SmithKline Beecham Pharmaceuticals Research Division, Epsom, Surrey, KT18 5XQ, UK
| | - M. J. Browne
- SmithKline Beecham Pharmaceuticals Research Division, Epsom, Surrey, KT18 5XQ, UK
| | - R. M. Perkins
- SmithKline Beecham Pharmaceuticals Research Division, Epsom, Surrey, KT18 5XQ, UK
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3
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Absar S, Gupta N, Nahar K, Ahsan F. Engineering of plasminogen activators for targeting to thrombus and heightening thrombolytic efficacy. J Thromb Haemost 2015; 13:1545-56. [PMID: 26074048 DOI: 10.1111/jth.13033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/29/2015] [Indexed: 01/02/2023]
Abstract
Thrombotic occlusion of the coronary artery, which triggers acute myocardial infarction, is one of the major causes of death in the USA. Currently, arterial occlusions are treated with intravenous plasminogen activators (PAs), which dissolve the clot by activating plasminogen. However, PAs indiscriminately generate plasmin, which depletes critical clotting factors (fibrinogen, factor V, and factor VIII), precipitates a lytic state in the blood, and produces bleeding complications in a large patient population. PAs have been extensively investigated to achieve thrombus specificity, to attenuate the bleeding risk, and to widen their clinical applications. In this review, we discuss various strategies that have been pursued since the beginning of thrombolytic therapy. We review the biotechnological approaches that have been used to develop mutant and chimeric PAs for thrombus selectivity, including the use of specific antibodies for targeting thrombi. We discuss particulate carrier-based systems and triggered-release concepts. We propose new hypotheses and strategies to spur future studies in this research arena. Overall, we describe the approaches and accomplishments in the development of patient-friendly and workable delivery systems for thrombolytic drugs.
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Affiliation(s)
- S Absar
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - N Gupta
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - K Nahar
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - F Ahsan
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
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4
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Flemmig M, Melzig MF. Serine-proteases as plasminogen activators in terms of fibrinolysis. ACTA ACUST UNITED AC 2012; 64:1025-39. [PMID: 22775207 DOI: 10.1111/j.2042-7158.2012.01457.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES This review should give an overview about the natural human plasminogen activators and their various modified variants as well as similar substances isolated from animals, microorganisms and plants. When a blood clot is formed in a blood vessel, it avoids the oxygen supply of the surrounding tissue. A fast fibrinolytic therapy should redissolve the blood vessel and reduce the degradation of the tissue. All proteases that are part of the human blood coagulation and fibrinolytic system belong to the serine protease family. t-PA (tissue plasminogen activator) and u-PA (urokinase plasminogen activator) are the naturally occurring fibrinolytic agents that are also used in therapy. KEY FINDINGS Despite many years of research, t-PA is still the gold standard in fibrinolytic therapy. But it has to be given as an infusion, which needs time. Modified fibrinolytic substances are, were, or perhaps will be in the market. They have different advantages over t-PA, but often the disadvantages predominate. CONCLUSION Many substances have been developed but an optimal fibrinolytic agent combined with a simple administration is not in therapeutic use to date.
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Affiliation(s)
- Martin Flemmig
- Institute of Pharmacy, Freie Universität Berlin, Berlin, Germany
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Lohray BB. Medical biotechnology in India. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2003; 85:215-81. [PMID: 12930097 DOI: 10.1007/3-540-36466-8_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
The potential of biotechnology has just began to emerge in the 20th century. After the full knowledge of human genomes is available, biotechnology is going to play a major role in shaping the concept of future drug discovery, drug delivery, diagnostic methodology, clinical trials, and to a great extent the major lifestyle of the human society. This article is a comprehensive review of the major impact of biotechnology in diagnostics, antibiotics, r-proteins, vaccines, and antibodies production. It also highlights the future aspects of gene therapy in the management of healthcare. A comprehensive list of biotech products in healthcare management has been given. Also, the growth of biotechnology throughout the world at large and in the Indian industries in particular has been highlighted. Constraints, concerns and difficulties in biotechnology in India have been addressed mainly related to human resources, training institutions in India, funding in biotechnology, patent-related issues and regulatory hurdles. Like in information technology, India has great potential in bioinformatics as well. Some of the recent information on bioinformatics centers in India has been summarized. Indian biotechnology industries have the potential to use the modern discoveries in life sciences to reach an enviable position in the world of biotechnology.
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Affiliation(s)
- Braj B Lohray
- Zydus Research Center, Cadila Healthcare Ltd., Sarkhej-Bavla Highway, Moraiya, Ahmedabad-382 213, India.
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6
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Abstract
Evolution of eukaryotes is mediated by sexual recombination of parental genomes. Crossovers occur in random, but homologous, positions at a frequency that depends on DNA length. As exons occupy only 1% of the human genome and introns about 24%, by far most of the crossovers occur between exons, rather than inside. The natural process of creating new combinations of exons by intronic recombination is called exon shuffling. Our group is developing in vitro formats for exon shuffling and applying these to the directed evolution of proteins. Based on the splice frame junctions, nine classes of exons and three classes of introns can be distinguished. Splice frame diagrams of natural genes show how the splice frame rules govern exon shuffling. Here, we review various approaches to constructing libraries of exon-shuffled genes. For example, exon shuffling of human pharmaceutical proteins can generate libraries in which all of the sequences are fully human, without the point mutations that raise concerns about immunogenicity.
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Affiliation(s)
- J A Kolkman
- Maxygen Inc., 515 Galveston Drive, Redwood City, CA 94063, USA
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7
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Abstract
Current thrombolytic therapy fails to induce early, complete, and sustained reperfusion in +/-50% of the patients with ST-segment elevation acute coronary syndromes. There are two complementary approaches to improve thrombolytic therapy: the development of new fibrinolytics with enhanced fibrin specificity and/or reduced plasma clearance and the coadministration of new antithrombotic agents. The results obtained so far suggest that single-bolus fibrinolytic therapy is likely to replace the current infusions in the near future. This may result in a significantly earlier (prehospital) treatment of patients. The concomitant intravenous administration of a glycoprotein IIb/IIIa receptor antagonist (in combination with a reduced dose of a fibrinolytic) appears to be able to further enhance the efficacy for clot lysis without increasing the risk for bleeding complications.
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Affiliation(s)
- F Van de Werf
- Department of Cardiology, Gasthuisberg University Hospital, Leuven, Belgium
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8
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Coombs GS, Corey DR. Site-Directed Mutagenesis and Protein Engineering. Proteins 1998. [DOI: 10.1016/b978-012058785-8/50006-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Biessen EA, van Teijlingen M, Vietsch H, Barrett-Bergshoeff MM, Bijsterbosch MK, Rijken DC, van Berkel TJ, Kuiper J. Antagonists of the mannose receptor and the LDL receptor-related protein dramatically delay the clearance of tissue plasminogen activator. Circulation 1997; 95:46-52. [PMID: 8994415 DOI: 10.1161/01.cir.95.1.46] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Clinical application of tissue plasminogen activator (TPA) as a fibrinolytic agent is complicated by its rapid clearance from the bloodstream, which is caused by TPA liver uptake. The mannose receptor on endothelial liver cells and the LDL receptor-related protein (LRP) on parenchymal liver cells were reported to contribute to liver uptake. METHODS AND RESULTS In this study, we addressed whether TPA clearance can be delayed by inhibiting receptor-mediated endocytosis of TPA. A series of cluster mannosides was synthesized, and their affinity for the mannose receptor was determined. A cluster mannoside carrying six mannose groups (M6L5) displayed a subnanomolar affinity for the mannose receptor (Ki = 0.41 +/- 0.09 nmol/L). Preinjection of M6L5 (1.2 mg/kg) reduced the clearance of 125I-TPA in rats by 60% because of specific inhibition of the endothelial cell uptake. The low toxicity of M6L5, combined with its accessible synthesis and high specificity for the mannose receptor, makes it a promising agent to improve the pharmacokinetics of TPA. Blockade of LRP by 39-kD receptor-associated protein (GST-RAP) also inhibited TPA clearance by 60%. Finally, combined preinjection of M6L5 and GST-RAP almost completely abolished reduced liver uptake of TPA and delayed its clearance by a factor of 10. CONCLUSIONS It can be concluded that (1) the mannose receptor and LRP appear to be the sole major receptors responsible for TPA clearance and (2) therapeutic levels of TPA can be maintained for a prolonged time span by coadministration of the aforementioned receptor antagonists.
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Affiliation(s)
- E A Biessen
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, The Netherlands
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10
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Runge MS, Harker LA, Bode C, Ruef J, Kelly AB, Marzec UM, Allen E, Caban R, Shaw SY, Haber E, Hanson SR. Enhanced thrombolytic and antithrombotic potency of a fibrin-targeted plasminogen activator in baboons. Circulation 1996; 94:1412-22. [PMID: 8823001 DOI: 10.1161/01.cir.94.6.1412] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Thrombolytic therapy reduces mortality in patients with acute myocardial infarction, but significant limitations exist with the use of currently available agents. In the present report, we describe the thrombolytic and antithrombotic potencies of a hybrid recombinant plasminogen activator consisting of an antifibrin antibody 59D8 (AFA) and low-molecular-weight single-chain urokinase-type plasminogen activator (scuPA). METHODS AND RESULTS A thrombolysis model in which thrombi are preformed in vivo in juvenile baboons was developed to compare the potencies of AFA-scuPA, recombinant tissue plasminogen activator (rTPA), and recombinant scuPA (rscuPA) in lysing nonocclusive 111In-labeled platelet-rich arterial-type thrombi and 125I-labeled fibrin-rich venous-type thrombi. Systemic infusion of 1.89 nmol/kg AFA-scuPA produced thrombolysis that was comparable to that obtained with much higher doses of TPA (14.2 nmol/kg) and rscuPA (28.5 nmol/kg). When steady-state plasma concentrations are normalized, AFA-scuPA lyses thrombi sixfold more rapidly than scuPA and TPA (P < .001) and reduces the rate of formation more than comparable doses of rscuPA (P < .0001). At equivalent thrombolytic doses, AFA-scuPA produced fewer antihemostatic effects than either rTPA or rscuPA. Template bleeding time measurements were shorter (3.5 +/- 0.12 minutes for AFA-scuPA versus 5.3 +/- 0.36 and 5.2 +/- 0.04 minutes for rTPA and rscuPA, respectively; P < .05), alpha 2-antiplasmin consumption was less (P < .05), and D-dimer generation was lower (P < .05). CONCLUSIONS We conclude that antibody targeting of scuPA to fibrin increases thrombolytic and antithrombotic potencies with less impairment of hemostasis compared with rTPA and rscuPA.
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Affiliation(s)
- M S Runge
- Cardiology Division, University of Texas Medical Branch, Galveston 77555-0553, USA
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11
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Smith JW, Tachias K, Madison EL. Protein loop grafting to construct a variant of tissue-type plasminogen activator that binds platelet integrin alpha IIb beta 3. J Biol Chem 1995; 270:30486-90. [PMID: 8530479 DOI: 10.1074/jbc.270.51.30486] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Protein-protein interactions can be guided by contacts between surface loops within proteins. We therefore investigated the hypothesis that novel protein-protein interactions could be created using a strategy of "loop grafting" in which the amino acid sequence of a biologically active, flexible loop on one protein is used to replace a surface loop present on an unrelated protein. To test this hypothesis we replaced a surface loop within an epidermal growth factor module with the complementarity-determining region of a monoclonal antibody. Specifically, the HCDR3 from Fab-9, an antibody selected to bind the beta 3-integrins with nanomolar affinity (Smith, J. W., Hu, D., Satterthwait, A., Pinz-Sweeney, S., and Barbas, C. F., III (1994) J. Biol. Chem. 269, 32788-32795), was grafted into the epidermal growth factor-like module of human tissue-type plasminogen activator (t-PA). The resulting variant of t-PA bound to the platelet integrin alpha IIb beta 3 with nanomolar affinity, retained full enzymatic activity, and was stimulated normally by the physiological co-factor fibrin. Binding of the novel variant of t-PA to integrin alpha IIb beta 3 was dependent on the presence of divalent cations and was inhibited by an RGD-containing peptide, demonstrating that, like the donor antibody, the novel t-PA binds specifically to the ligand-binding site of the integrin. These findings suggest that surface loops within protein modules can, at least in some cases, be interchangeable and that phage display can be combined with loop grafting to direct proteins, at high affinity, to selected targets. In principle, these targets could include not only other proteins but also peptides, nucleic acids, carbohydrates, lipids, or even uncharacterized markers of specific cell types, tissues, or viruses.
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Affiliation(s)
- J W Smith
- Department of Vascular Biology, Scripps Research Institute, La Jolla, California 92037, USA
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12
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Camani C, Kruithof EK. The role of the finger and growth factor domains in the clearance of tissue-type plasminogen activator by hepatocytes. J Biol Chem 1995; 270:26053-6. [PMID: 7592802 DOI: 10.1074/jbc.270.44.26053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The relative contribution of the finger/growth factor domains of tissue-type plasminogen activator (t-PA) and of the other t-PA domains to the clearance of t-PA by hepatocytes was investigated. A recombinant finger/growth factor construct inhibited t-PA and t-PA/plasminogen activator inhibitor type-1 degradation with an IC50 of 1800 nM, whereas a t-PA mutant lacking the finger and growth factor domains inhibited degradation with an estimated IC50 of 1200 nM. In comparison the IC50 of t-PA was found to be approximately 10 nM. Clearance of t-PA by human or rat hepatoma cells was not inhibited by high concentrations of fucose (50 mM), which suggests that the fucose on Thr-61 is not involved in clearance by these cells. These results suggest that the binding of t-PA involves several low affinity binding sites located on distinct domains of the t-PA molecule.
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Affiliation(s)
- C Camani
- Division of Hematology, University Hospital, Lausanne, Switzerland
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13
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Abstract
Over the past decade, the existence of cell-surface receptors for components of the plasminogen system, t-PA, u-PA, plasminogen and plasmin, has been demonstrated. Plasminogen receptors have been detected on virtually all cell types tested, and occupancy has also been demonstrated in biological settings. Characteristic features of plasminogen receptors include their relatively low affinity and their extraordinarily high density on many cells. These receptors recognize the lysine binding sites associated with the kringles of plasminogen. Plasminogen receptors include proteins with carboxyl-terminal lysine residues (enolase and annexin II are representatives) and nonproteins, such as gangliosides. Plasminogen binding to cells enhances plasmin activity by augmenting plasminogen activation, increasing the enzymatic activity of plasmin, and protecting plasmin for inactivation by inhibitors. t-PA receptors serve two major functions, clearance and cell-surface localization. The liver is the main organ for t-PA clearance; parenchymal, endothelial and Kupffer cells are all capable of t-PA uptake. Clearance receptors on these cells are heterogeneous and include ones which recognize the carbohydrate side chains of t-PA and ones which take up t-PA: PAI-1 complexes. Receptors which recognize free t-PA also mediate liver clearance, and alpha 2-MR/LRP is a representative of this latter category. Receptors that localize t-PA on cell surfaces serve a profibrinolytic function. Vascular endothelial cells are rich in such receptors, and annexin II is a representative of these t-PA binding sites. Circulating blood cells also bind t-PA, and some of the sites on these cells are shared with plasminogen. Cells of neuronal origin are capable of binding t-PA with high affinity; and amphoterin, a protein involved in neurite outgrowth, may be a neuronal t-PA receptor. Overall, the plasminogen system is one of the most widely distributed and versatile of the cell surface-proteinase systems. By activating bound plasminogen by cell-bound plasminogen activators, the cell harnesses the broad proteolytic activity of plasmin. Cells can then utilize this activity to perform functions such as assisting in cell migration.
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Affiliation(s)
- A Redlitz
- Department of Molecular Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA
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14
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Mutant and hybrid protein derivatives for the experimental therapy with plasminogen activators (review). Pharm Chem J 1994. [DOI: 10.1007/bf02218422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Pfeiffer G, Strube KH, Schmidt M, Geyer R. Glycosylation of two recombinant human uterine tissue plasminogen activator variants carrying an additional N-glycosylation site in the epidermal-growth-factor-like domain. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:331-48. [PMID: 8307000 DOI: 10.1111/j.1432-1033.1994.tb19945.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recombinant human uterine tissue plasminogen activator (tPA) glycosylation mutants carrying an additional N-glycosylation site in the epidermal-growth-factor-like domain due to the replacement of either Tyr67 by Asn (YN-tPA) or Gly60 by Ser (GS-tPA) were expressed in mouse epithelial cells (C127) in the presence of [6-3H]glucosamine. Glycopeptides comprising individual glycosylation sites were isolated and oligosaccharides attached were liberated by treatment with endo-beta-N-acetylglucosaminidase H or peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F. Oligosaccharide alditols obtained after reduction were either directly characterized by high-pH anion-exchange chromatography (high-mannose and hybrid-type glycans) or preparatively subfractionated after enzymic desialylation and separation from sulphated asialooligosaccharides (complex-type sugar chains). Individual (sub)fractions of glucans were studied by methylation analysis, liquid secondary-ion mass spectrometry and, in part, by exoglycosidase digestion, whereas corresponding deglycosylated peptides were identified by amino acid analysis and N-terminal amino acid sequencing. The results revealed that Asn117 of YN-tPA carried exclusively high-mannose-type glycans with five to nine mannose residues similar to wild-type tPA expressed in this cell line [Pfeiffer, G., Schmidt, M., Strube, K.-H. & Geyer, R. (1989) Eur. J. Biochem. 186, 273-286]. In contrast, Asn117 of GS-tPA carried only small amounts (about 25%) of high-mannose and hybrid-type species and predominantly complex-type sugar chains (about 75%) which were partially incomplete and mostly devoid of fucose. Newly introduced N-glycosylation sites at Asn67 (YN-tPA) or Asn58 (GS-tPA) as well as those at Asn184 and Asn448 were solely substituted by complex-type glycans. Each carbohydrate attachment site displayed a peculiar oligosaccharide pattern with regard to branching and substitution by Gal alpha 3-residues, sulphate groups, intersecting GlcNAc and lactosamine repeats. Our study clearly demonstrates that creation of a new glycosylation site at Asn58 influenced the oligosaccharide processing and, hence, the glycosylation pattern at Asn117, whereas introduction of a new site at Asn67 did not. The relative amounts of complex-type glycans at Asn117 of GS-tPA correlated with the degree of carbohydrate substitution of Asn58. Therefore, it can be concluded that the presence of a sugar chain at the position and not the Gly to Ser mutation itself is responsible for the observed alteration of GS-tPA glycosylation.
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Affiliation(s)
- G Pfeiffer
- Biochemisches Institut am Klinikum, Universität, Giessen, Germany
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16
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Madison E. Probing structure-function relationships of tissue-type plasminogen activator by site-specific mutagenesis. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0268-9499(94)90720-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Susceptibility of mutant, recombinant plasminogen activators to proteolytic breakdown: Removal of the F domain by plasmin. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0268-9499(93)90131-e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Madison EL, Sambrook JE. Probing structure-function relationships of tissue-type plasminogen activator by oligonucleotide-mediated site-specific mutagenesis. Methods Enzymol 1993; 223:249-71. [PMID: 8271957 DOI: 10.1016/0076-6879(93)23050-w] [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: 01/29/2023]
Affiliation(s)
- E L Madison
- Department of Vascular Biology, Scripps Research Institute, La Jolla, California 92037
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19
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Otter M, Kuiper J, van Berkel TJ, Rijken DC. Mechanisms of tissue-type plasminogen activator (tPA) clearance by the liver. Ann N Y Acad Sci 1992; 667:431-42. [PMID: 1339243 DOI: 10.1111/j.1749-6632.1992.tb51645.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- M Otter
- Gaubius Laboratory, IVVO-TNO, Leiden, The Netherlands
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20
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Bos R, Nieuwenhuizen W. The potential improvement of thrombolytic therapy by targeting with bispecific monoclonal antibodies: why they are used and how they are made. BIOTHERAPY (DORDRECHT, NETHERLANDS) 1992; 5:187-99. [PMID: 1419466 DOI: 10.1007/bf02171051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The generation of the proteolytic enzyme plasmin from its inactive precursor plasminogen, mediated by so called plasminogen activators, is the essential step in thrombolytic therapy. Plasmin is responsible for the degradation of the insoluble fibrin, the major component of a thrombus, to soluble fibrin degradation products. So far, the use of the more recently developed thrombolytic agents single-chain urokinase-type plasminogen activator (scu-PA) and tissue-type plasminogen activator (t-PA) were disappointing, mainly due to some of their negative properties in vivo, i.e., rapid inhibition and/or hepatic clearance. Besides some background information on the haemostatic balance; t-PA and scu-PA structure; and mechanisms of action, we here review some reported attempts to improve on these agents for thrombolytic therapy following various strategies. One of the more potential strategies, antibody-targeted thrombolytic therapy using bispecific monoclonal antibodies, is discussed somewhat more extensively, as are the several procedures that can be followed for bispecific antibody preparation.
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Affiliation(s)
- R Bos
- IVVO-TNO, Gaubius Laboratory, Leiden, The Netherlands
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21
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Dodd I, Mitchell DL, Chapman CG, Smith RA. The use of bovine fibrin-streptokinase films for the determination of recombinant human plasminogen. Biologicals 1992; 20:197-202. [PMID: 1457105 DOI: 10.1016/s1045-1056(05)80038-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Plasminogen is a key component of the haemostatic system in man and the plasma-derived protein molecule has been actively investigated. Within the last few years cDNA and the gene encoding plasminogen have been cloned and the protein has been expressed in a number of eukaryotic or prokaryotic systems. Yields of expressed plasminogen are frequently low. Currently available assays for plasminogen generally rely on the determination of antigen or utilize tripeptide substrates for measuring functional activity, and they have certain limitations. Assays employing relevant protein substrates offer an alternative way to measure function and overcome the drawbacks associated with the other tests. The use of fibrin films for the assay of low levels of recombinant plasminogen has not been described fully before. The two fibrin film-based assays described in this paper are significant additions to the array of assays available for plasminogen molecules.
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Affiliation(s)
- I Dodd
- Department of Biotechnology, SmithKline Beecham Pharmaceuticals, Epsom, Surrey, U.K
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22
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Robinson JH, Browne MJ, Carey JE, Chamberlain PD, Chapman CG, Cronk DW, Dodd I, Entwisle C, Esmail AF, Kalindjian SB. A recombinant, chimeric enzyme with a novel mechanism of action leading to greater potency and selectivity than tissue-type plasminogen activator. Circulation 1992; 86:548-52. [PMID: 1638720 DOI: 10.1161/01.cir.86.2.548] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Early intervention with thrombolytic agents has been shown unequivocally to reduce mortality after acute myocardial infarction. Presently used agents have disadvantages such as short half-life, immunogenicity, hypotension, and bleeding complications. Therefore, there is a need to develop improved thrombolytic drugs with novel mechanisms of action leading to improved properties. METHODS AND RESULTS Hybrid plasminogen/tissue-type plasminogen activator (t-PA) complementary DNA was constructed and expressed in Chinese hamster ovary cells. The chimeric protein, comprising the fibrin-binding domains of plasminogen covalently linked to the catalytic domain of t-PA, was purified and evaluated in vitro and in vivo. The hybrid was inhibited rapidly in human and animal plasmas. The mediator of this rapid inhibition was shown to be alpha 2-antiplasmin. The active center of the hybrid could be protected by reversible active center acylation with a novel inverse acylating agent, 4'-amidinophenyl-4-chloroanthranilic acid (AP-CLAN). An acylated (CLAN-) hybrid was cleared from the bloodstream of guinea pigs at 0.35 +/- 0.02 ml/min.kg-1 compared with a clearance rate of 36 +/- 4 ml/min.kg-1 for t-PA. The CLAN-plasminogen/t-PA hybrid was evaluated in a quantitative, "humanized" guinea pig pulmonary embolism model and shown to be approximately threefold more potent when given by bolus than an infusion of t-PA. Furthermore, the acylated hybrid was more fibrin selective than t-PA as determined by the relation between clot lysis and fibrinogen degradation. CONCLUSIONS An acylated, recombinant plasminogen/t-PA hybrid has sufficiently slow clearance to be administered by bolus and is more potent and fibrin selective than t-PA in vivo.
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Affiliation(s)
- J H Robinson
- Department of Biotechnology, SmithKline Beecham Pharmaceuticals, Surrey, England, UK
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23
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Bassel-Duby R, Jiang N, Bittick T, Madison E, McGookey D, Orth K, Shohet R, Sambrook J, Gething M. Tyrosine 67 in the epidermal growth factor-like domain of tissue-type plasminogen activator is important for clearance by a specific hepatic receptor. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50142-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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24
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Pharmacological and pharmacokinetic properties of a deglycosylated mutant of the tissue-type plasminogen activator expressed in CHO cells. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0268-9499(92)90070-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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25
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Nguyen G, Self S, Camani C, Kruithof E. Demonstration of a specific clearance receptor for tissue-type plasminogen activator on rat Novikoff hepatoma cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42688-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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26
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Liu DT. Glycoprotein pharmaceuticals: scientific and regulatory considerations, and the US Orphan Drug Act. Trends Biotechnol 1992; 10:114-20. [PMID: 1368096 DOI: 10.1016/0167-7799(92)90192-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- D T Liu
- Division of Biochemistry and Biophysics, Department of Health and Human Services, Food and Drug Administration, Bethesda, MD 20892
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27
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Browne M, Chapman C, Dodd I, Carey J, Lawrence G, Mitchell D, Robinson J. Expression of recombinant human plasminogen and aglycoplasminogen in hela cells. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0268-9499(91)90010-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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28
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Collen D, Lu HR, Lijnen HR, Nelles L, Stassen JM. Thrombolytic and pharmacokinetic properties of chimeric tissue-type and urokinase-type plasminogen activators. Circulation 1991; 84:1216-34. [PMID: 1909220 DOI: 10.1161/01.cir.84.3.1216] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Chimeric molecules comprising the A-chain of tissue-type plasminogen activator (t-PA) and the catalytic domain of urokinase-type plasminogen activator (u-PA) have intact enzymatic characteristics of u-PA, partial fibrin-binding properties of t-PA, and thrombolytic properties in animal models comparable with but not superior to those of single-chain u-PA (scu-PA). Deletion of the finger and growth factor domains (t-PA-delta FE/scu-PA-e) in such chimeras further reduces their affinity for fibrin. METHODS AND RESULTS A detailed investigation of the thrombolytic potency and the pharmacokinetics of t-PA and u-PA chimeras was performed in quantitative animal models for thrombolysis. In hamsters with pulmonary embolism, in rabbits with jugular vein thrombosis, and in baboons with femoral vein thrombosis, the thrombolytic potency (percent lysis per milligram of compound administered per kilogram of body weight) of t-PA-delta FE/scu-PA-e was significantly higher than that of recombinant scu-PA (rscu-PA, Saruplase) as shown by a maximal rate of 720 +/- 170% versus 45 +/- 5% lysis per milligram of compound per kilogram of body weight (mean +/- SEM, p less than 0.01) in hamsters, 210 +/- 18% versus 49 +/- 3% lysis per milligram of compound per kilogram of body weight (mean +/- SEM, p less than 0.01) in rabbits, and 310 +/- 73% versus 90 +/- 0.3% lysis per milligram of compound per kilogram of body weight (p less than 0.01) in baboons. However, the specific thrombolytic activity (percent lysis per microgram per milliliter steady-state plasma antigen level) of t-PA-delta FE/scu-PA-e was not significantly different from that of rscu-PA in hamsters (210 +/- 57% versus 160 +/- 27% lysis per microgram per milliliter antigen level) and was lower than that of rscu-PA in rabbits (37 +/- 4% versus 130 +/- 5% lysis per microgram per milliliter antigen level; p less than 0.01). In dogs with a combined femoral vein blood clot and a platelet-rich femoral arterial eversion graft thrombosis, 0.25 mg/kg body wt bolus injections of t-PA-delta FE/scu-PA-e produced significantly more venous clot lysis (90 +/- 5%, n = 10) than 0.25 mg/kg rscu-PA (26 +/- 3%, n = 10) (p less than 0.001) and, at the arterial side, more frequent (10 of 10 dogs versus three of 10 dogs) and more persistent (six of 10 dogs versus none of 10 dogs) recanalization (p = 0.002). After bolus injection in hamsters, rabbits, or baboons, t-PA-delta FE/scu-PA-e had a fourfold to sixfold longer initial half-life than rscu-PA and a slower plasma clearance of sixfold in hamsters, 10-fold in rabbits, and more than 10-fold in baboons. CONCLUSIONS These results indicate that t-PA-delta FE/scu-PA-e has a markedly enhanced thrombolytic potency toward venous and arterial thrombi caused by a delayed in vivo clearance with relatively maintained specific thrombolytic activity. These properties suggest that the chimera may be clinically useful for thrombolytic therapy by bolus administration in patients with thromboembolic disease.
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Affiliation(s)
- D Collen
- Center for Thrombosis and Vascular Research, University of Leuven, Belgium
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29
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Affiliation(s)
- D Collen
- Center for Thrombosis and Vascular Research, University of Leuven, Belgium
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30
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Affiliation(s)
- J Henkin
- Abbott Laboratories, Thrombolytics Venture Discovery Group, Abbott Park, IL 60064-3500
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31
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Bennett WF, Paoni NF, Keyt BA, Botstein D, Jones AJ, Presta L, Wurm FM, Zoller MJ. High resolution analysis of functional determinants on human tissue-type plasminogen activator. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67773-2] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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32
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Abstract
Inherited defects of antithrombin III, protein C, protein S, heparin cofactor II, plasminogen and the fibrinogens are thought to be responsible for between 10 and 15% of all patients presenting with recurrent venous thrombosis. The structure, function and expression of these genes and the nature of the gene lesions underlying the deficiency states are reviewed in detail.
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Affiliation(s)
- D N Cooper
- Molecular Genetics Section, Thrombosis Research Institute, Chelsea, London, UK
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33
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Affiliation(s)
- H R Lijnen
- Center for Thrombosis and Vascular Research, K.U.L., Campus Gasthuisberg, Leuven, Belgium
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34
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Wikström K, Mattsson C, Sterky C, Pohl G. Tissue plasminogen activator mutants lacking the growth factor domain and the first kringle domain: II. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0268-9499(91)90075-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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35
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36
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Collen D, Bennett WF. Recombinant tissue-type plasminogen activator. BIOTECHNOLOGY (READING, MASS.) 1991; 19:197-223. [PMID: 1786472 DOI: 10.1016/b978-0-7506-9120-8.50015-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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37
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Madison EL, Goldsmith EJ, Gething MJ, Sambrook JF, Gerard RD. Restoration of serine protease-inhibitor interaction by protein engineering. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45753-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Determinants of clearance of tissue-type plasminogen activator and their pharmacologic implications. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0268-9499(90)90015-c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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39
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Affiliation(s)
- J Loscalzo
- Department of Medicine, Harvard Medical School, Boston, MA 02115
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40
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Abstract
The increasing incidence of thromboembolic diseases has sustained the search for new agents able to stimulate the natural fibrinolytic system. The first generation of antithrombotic agents include bacterial streptokinase and human urine urokinase. Because these molecules lack specificity for the fibrin clot, important efforts have been made to produce, using recombinant DNA technology, agents presenting higher fibrin clot selectivity such as t-PA (tissue-type plasminogen activator) and scu-PA (single chain urokinase-type plasminogen activator). In parallel, several laboratories are presently attempting to create mutants and hybrids plasminogen activators displaying improved thrombolytic properties with respect to the natural molecules. In this paper, we describe briefly the mechanisms of fibrinolysis and the role of the different natural thrombolytic agents. In addition, we review the possibilities of genetic engineering for the production of natural and novel plasminogen activators.
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Affiliation(s)
- L Piérard
- Service de Génétique Appliquée, Université Libre de Bruxelles, Nivelles, Belgium
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41
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Morton P, Owensby D, Wun T, Billadello J, Schwartz A. Identification of determinants involved in binding of tissue-type plasminogen activator-plasminogen activator inhibitor type 1 complexes to HepG2 cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)77272-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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42
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Browne MJ, Chapman CG, Dodd I, Esmail AF, Robinson JH. Deletion of a tripeptide sequence from the growth-factor domain of tissue-type plasminogen activator prolongs in vivo circulation. Thromb Res 1990; 59:687-92. [PMID: 2122547 DOI: 10.1016/0049-3848(90)90429-g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M J Browne
- Department of Biotechnology, Smith Kline Beecham, Epsom, Surrey, United Kingdom
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43
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Trill J, Fong KL, Shebuski R, McDevitt P, Rosa M, Johanson K, Williams D, Boyle K, Sellers T, Reff M. Expression and characterisation of finger protease (FP); a mutant tissue-type plasminogen activator (t-PA) with improved pharmacokinetics. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0268-9499(05)80044-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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44
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Ahern TJ, Morris GE, Barone KM, Horgan PG, Timony GA, Angus LB, Henson KS, Stoudemire JB, Langer-Safer PR, Larsen GR. Site-directed mutagenesis in human tissue-plasminogen activator. Distinguishing sites in the amino-terminal region required for full fibrinolytic activity and rapid clearance from the circulation. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39394-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Efficacy and selectivity of tissue-type and urokinase-type plasminogen activators in a humanised pulmonary embolism model. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0268-9499(90)90003-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Stassen J, Vanlinthout I, Lijnen H, Collen D. A hamster pulmonary embolism model for the evaluation of the thrombolytic and pharmacokinetic properties of thrombolytic agents. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0268-9499(90)90349-o] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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47
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Browne M, Chapman C, Dodd I, Reavy B, Esmail A, Robinson J. The role of tissue-type plasminogen activator A-chain domains in plasma clearance. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0268-9499(89)90048-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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48
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Abstract
Thrombolytic therapy for the removal of intravascular thrombi was introduced when streptokinase was first given to humans 40 years ago, the same year the American College of Cardiology was founded. Streptokinase was first administered to patients with acute myocardial infarction in 1959. Today, thrombolytic therapy has been established to offer significant benefits to patients with acute myocardial infarction provided they are brought to medical attention early enough after the onset of symptoms. The two major agents, streptokinase and recombinant tissue-type plasminogen activator (rt-PA), have been shown to result in reperfusion of infarct-related arteries, to salvage ischemic myocardium, to improve myocardial performance and to reduce mortality. In spite of these impressive gains, this novel therapy has shortcomings. The interval from the start of thrombolytic treatment to coronary reperfusion varies significantly from patient to patient and may, at times, be too long to produce a real benefit in terms of salvage of ischemic myocardium. The rate of reocclusion lies somewhere between 10% and 20% and appears not to be influenced by concomitant heparin anticoagulation. The rate of bleeding complications even with the "fibrin-specific" rt-PA is higher than anticipated and may range from 10% to 30%. As a consequence, intensive efforts are being directed at the development of improved thrombolytic agents and for adjunctive therapy evaluating better anticoagulants than heparin and better antiplatelet agents than aspirin. This review is a status report summarizing where we are in thrombolytic therapy in acute myocardial infarction, where we need to improve treatment results and what is being done mainly at the preclinical level to bring about such improvements.
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Affiliation(s)
- N U Bang
- Lilly Laboratory for Clinical Research, Eli Lilly and Company, Indianapolis, Indiana
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49
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Hiramatsu R, Kasai S, Amatsuji Y, Kawai T, Hirose M, Morita M, Tanabe T, Kawabe H, Arimura H, Yokoyama K. Effect of deletion of epidermal growth factor-like domain on plasma clearance of pro-urokinase. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0268-9499(89)90012-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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50
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Dodd I, Carr K. Effect of harvest medium composition on yield and chain nature of recombinant tissue-type plasminogen activator species. Thromb Res 1989; 55:79-85. [PMID: 2506663 DOI: 10.1016/0049-3848(89)90458-1] [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: 01/01/2023]
Abstract
The effect of harvest medium composition on yield and quality of two recombinant tissue type plasminogen activators (t-PA) has been examined. Protein hydrolysates increased the yield of native t-PA up to 3-fold compared to control cultures. In marked contrast, the yield of a growth-factor deleted t-PA mutant was adversely affected by the use of these additives. Partially purified t-PA that had been harvested in the presence of protein hydrolysates had higher fibrin plate activity: amidolytic activity ratios. In addition Western blotting showed these preparations contained less degraded material. These observations suggest that protein hydrolysates have opposite effects on two closely related recombinant cell lines and that they can affect quality as well as yield of secreted proteins.
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Affiliation(s)
- I Dodd
- Department of Biotechnology, Biosciences Research Centre, Epsom, Surrey U.K
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