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Immunological characterization of plasminogen activator activities in human tissues and body fluids.The Journal of Laboratory and Clinical... Apr 1981Human plasminogen activators were compared immunologically in both a double-diffusion technique and quenching experiments on the fibrinolytic activities of the... (Comparative Study)
Comparative Study
Human plasminogen activators were compared immunologically in both a double-diffusion technique and quenching experiments on the fibrinolytic activities of the activators. Antisera against HMW and LMW urokinase and an antiserum against highly purified tissue plasminogen activator from human uterus were used. It was found that uterine tissue plasminogen activator and urokinase are two immunologically distinct plasminogen activators. The occurrence of the two kinds of plasminogen activators in human tissues and body fluids was studied on the basis of the quenching of the activities by antibodies. In tissue extracts, mainly tissue plasminogen activator was found. Seminal plasma exhibited a high plasminogen activator activity, consisting of both urokinase and tissue plasminogen activator-related activators. Urine contained a small amount of tissue plasminogen activator-related activator in addition to urokinase. The low plasminogen activator activities of saliva and tears were completely attributed to activators related to tissue plasminogen activator.
Topics: Animals; Body Fluids; Female; Humans; Immune Sera; Immunodiffusion; Male; Plasminogen; Plasminogen Activators; Rabbits; Semen; Tissue Distribution; Urokinase-Type Plasminogen Activator; Uterus
PubMed: 6782183
DOI: No ID Found -
Thrombosis and Haemostasis May 1979The assay of plasminogen activator activities on fibrin plates was re-evaluated with special reference to fibrinolysis inhibitors present in samples and in fibrin...
Interfering factors in the assay of plasminogen activators by the fibrin plate method. Occurrence of different inhibitors against tissue plasminogen activator and urokinase.
The assay of plasminogen activator activities on fibrin plates was re-evaluated with special reference to fibrinolysis inhibitors present in samples and in fibrin plates. The nature, action and stability of inhibiting material were studied in tissue with considerable differences in activator and inhibitor contents: human lung, liver and placenta. Extracts were tested for inhibitory capacity against purified human uterine tissue plasminogen activator, urokinase and plasmin of fibrin plates prepared from different grades of fibrinogen and fibrin. The tissue extracts inhibited fibrinolysis on fibrin plates to varying degrees, dependent on the sample medium, the type of fibrin plate and the kind of plasminogen activator. The influence of inhibitors in the sample and in the fibrin plate was partly abolished by the presence of 2 M KSCN in the sample. The procedure for preparing the samples as described by Astrup and Albrechtsen did not completely eliminate the inhibitory action against the added plasminogen activators. Comparison of urokinase inhibition with tissue activator inhibition by the tissue extracts as to the degree of denaturation in the Astrup and Albrechtsen procedure showed that they have much in common. Nevertheless, some differences were found which indicated the possible existence of separate urokinase and tissue activator inhibitors or of different inhibition mechanisms for these plasminogen activators.
Topics: Antifibrinolytic Agents; Fibrin; Humans; Liver; Lung; Placenta; Plasminogen Activators; Plasminogen Inactivators; Protease Inhibitors; Tissue Extracts; Urokinase-Type Plasminogen Activator
PubMed: 111368
DOI: No ID Found -
Biochimie Dec 1985Considerable interest in plasminogen activators as human thrombolytic drugs has stimulated rapid biotechnologic progresses. These enzymes have been classified in two... (Review)
Review
Considerable interest in plasminogen activators as human thrombolytic drugs has stimulated rapid biotechnologic progresses. These enzymes have been classified in two immunochemically distinct groups: "urokinase-like" activators or u-PA which do not interact with fibrin and "tissue activator-like" activators or t-PA which interact with fibrin. Plasminogen activators are widely distributed in normal and malignant tissues and they are implicated in various physiological and pathological processes. They maintain the functional integrity of the vascular system and their presence may be of importance in tissue remodeling and cell migration. Urokinase and streptokinase are used in human thrombolytic therapy. However, the properties displayed by t-PA suggest that this enzyme may be a superior fibrinolytic agent. The primary structures of urokinase and t-PA are known; both enzymes have been synthesized by DNA technology. In order to produce t-PA in large quantities by gene cloning, intensive studies are conducted by pharmaceutical industries. Clinical trials using t-PA for dissolving thrombi in coronary heart disease, strokes and pulmonary embolism are in progress. This review presents the molecular and structural properties of plasminogen activators, as well as related physiological, pathological and therapeutic aspects.
Topics: Animals; Fibrin; Fibrinolysis; Humans; Models, Molecular; Molecular Weight; Neoplasms; Plasminogen Activators; Protein Conformation; Substrate Specificity; Tissue Distribution; Urokinase-Type Plasminogen Activator
PubMed: 3913465
DOI: 10.1016/s0300-9084(85)80129-2 -
Methods in Enzymology 1993
Comparative Study
Topics: Amino Acid Sequence; Animals; Chiroptera; Chromatography, Affinity; Chromatography, Ion Exchange; Electrophoresis, Polyacrylamide Gel; Fibrinolysis; Humans; Indicators and Reagents; Kinetics; Models, Structural; Molecular Sequence Data; Plasminogen Activator Inhibitor 1; Plasminogen Activators; Protein Conformation; Saliva; Salivary Glands; Sequence Homology, Amino Acid; Spectrophotometry; Tissue Plasminogen Activator
PubMed: 8271956
DOI: 10.1016/0076-6879(93)23049-s -
Circulation Sep 1997Intimal smooth muscle cell proliferation is an underlying pathogenetic mechanism for neointimal hyperplasia and consequent vein graft failure. This study characterizes...
BACKGROUND
Intimal smooth muscle cell proliferation is an underlying pathogenetic mechanism for neointimal hyperplasia and consequent vein graft failure. This study characterizes the expression of tissue-type plasminogen activator (TPA), urokinase-type plasminogen activator (UPA), and plasminogen activator inhibitor-1 (PAI-1) in hyperplastic vein grafts and normal venous tissue.
METHODS AND RESULTS
Failing graft and control vein specimens from 14 donors were homogenized, and TPA and PAI-1 were quantified with ELISA. The amount of PAI-1 was seven times higher (4.2+/-2.1 versus 0.6+/-0.6 ng/mg protein, P<.005), but the TPA antigen content was markedly lower (3.1+/-2.1 versus 8.1+/-3.7 ng/mg protein, P<.005) in the stenosed grafts compared with the control veins. Strong immunohistochemical PAI-1 reactivity and in situ hybridization signals for PAI-1 and UPA mRNA were associated with the smooth muscle cells of the thickened intima of the grafts. Functional assays of the graft specimens showed an increased UPA/TPA ratio and a decreased total fibrinolytic activity in comparison with normal veins.
CONCLUSIONS
Upregulation of PAI-1 mRNA expression and markedly increased amounts of PAI-1 antigen were detected in the vein grafts after the development of neointima. Furthermore, augmented UPA activity was found in the graft wall, but TPA was clearly depleted. Altogether, our findings imply decreased fibrinolytic potential in the stenosed graft, which may contribute to the graft occlusion.
Topics: Fibrin; Fibrinolytic Agents; Graft Survival; Humans; Immunoenzyme Techniques; Immunohistochemistry; In Situ Hybridization; Plasminogen Activator Inhibitor 1; Plasminogen Activators; RNA, Messenger; Serine Proteinase Inhibitors; Tissue Plasminogen Activator; Tunica Intima; Urokinase-Type Plasminogen Activator; Veins
PubMed: 9323062
DOI: 10.1161/01.cir.96.6.1783 -
World Journal of Surgery 1990A major advance in the treatment of thrombosis has been the development of thrombolytic agents. Streptokinase and urokinase have been the standard agents available for... (Review)
Review
A major advance in the treatment of thrombosis has been the development of thrombolytic agents. Streptokinase and urokinase have been the standard agents available for many years, but in recent years the most exciting change in the field has been the development of a new generation of plasminogen activators, the principal one being tissue plasminogen activator. The first generation of plasminogen activators--streptokinase and urokinase--do not have fibrin specificity and predictably induce plasma proteolysis when administered systemically in doses which introduce thrombolysis. The second generation of plasminogen activators are much more fibrin-specific and offer a promise of fewer complications. In a number of major randomized studies, these thrombolytic agents have proved effective clinically. The major complication of thrombolytic therapy, however, is hemorrhage. The risk of hemorrhage increases with the length of infusion and occurs most often from sites of vascular invasion such as needle punctures or cutdown sites from surgical wounds. This can be treated by applying pressure over the wound and discontinuing the thrombolytic agent whose half-life is measured in hours. It is believed that as more experience is acquired with the second-generation plasminogen activators, better control of these drugs will result in fewer complications and more effective and wider application of therapy.
Topics: Hemorrhage; Humans; Plasminogen Activators; Pulmonary Embolism; Thrombophlebitis
PubMed: 2238671
DOI: 10.1007/BF01658826 -
Thrombosis Research Apr 1983The thrombolytic activity and elimination rate in vivo of a plasminogen activator purified from a melanoma cell line was examined in a rabbit thrombus model. Following... (Comparative Study)
Comparative Study
The thrombolytic activity and elimination rate in vivo of a plasminogen activator purified from a melanoma cell line was examined in a rabbit thrombus model. Following an intravenous injection of 125I labelled plasminogen activator, its biological activity disappeared very rapidly from the plasma (t1/2 = 1.5 min) and radioactivity immediately accumulated in the liver. After a two-hour infusion with a total amount of 0.5 mg plasminogen activator a 60 per cent reduction in the weight of partially occluding thrombi was noted. No significant thrombolysis was seen in totally occluded vessels. Treatment with 0.5 mg plasminogen activator caused no depletion of fibrinogen or alpha 2-antiplasmin. No significant thrombolysis occurred after infusion of 0.5 mg streptokinase, but total lysis of occluding and non-occluding thrombi was obtained after a two-hour infusion of 1 mg streptokinase, without any reduction of fibrinogen. A marked reduction of alpha 2-antiplasmin was seen after both 0.5 and 1 mg of streptokinase treatment but were not seen in rabbits infused with plasminogen activator.
Topics: Animals; Cell Line; Female; Fibrinolysis; Half-Life; Humans; Male; Melanoma; Plasminogen Activators; Rabbits; Streptokinase; Thrombosis
PubMed: 6683005
DOI: 10.1016/0049-3848(83)90400-0 -
The American Journal of Cardiology Dec 1996The initial work on thrombolytic therapy for acute myocardial infarction (AMI) focused on intracoronary administration of streptokinase. Continuing research has given... (Comparative Study)
Comparative Study Review
The initial work on thrombolytic therapy for acute myocardial infarction (AMI) focused on intracoronary administration of streptokinase. Continuing research has given rise to the development of both second- and third-generation agents and consequent refinements in thrombolytic regimens. Intravenous recombinant tissue plasminogen activator (t-PA, or alteplase) proved superior to both intracoronary and intravenous streptokinase with regard to reperfusion efficacy and impact on survival. An accelerated dosage regimen was later devised to allow the administration of t-PA over a shorter period of time. Unfortunately, t-PA failed to lessen the risk of bleeding complications that had plagued the use of streptokinase. The wild-type t-PA molecule has since been modified in an attempt to achieve improved lytic characteristics with less bleeding risk. Among these third-generation agents is reteplase (r-PA); compared with alteplase, reteplase has a prolonged half-life and seems to offer more rapid thrombolysis. Promising results have been obtained in large, randomized trials of reteplase. Another new agent is the TNK mutant of t-PA, which also has a prolonged half-life and seems to produce more rapid and complete thrombolysis, as well as less risk of intracranial bleeding than with alteplase in animal models. Although large, randomized trials have not yet been conducted, encouraging results have emerged from preliminary dose-ranging trials with TNK. A third new agent, n-PA, has an even longer half-life and has shown improved lytic activity in animal models. A dose-ranging trial of n-PA is currently under way. Despite the fact that each of the third-generation drugs has shown considerable potential with regard to improving the efficacy of thrombolytic therapy, the risk of intracranial bleeding remains problematic and will need to be assessed in large, randomized trials.
Topics: Animals; Cerebral Hemorrhage; Disease Models, Animal; Drug Administration Schedule; Drug Design; Half-Life; Hemorrhage; Humans; Molecular Biology; Myocardial Infarction; Myocardial Reperfusion; Plasminogen Activators; Point Mutation; Recombinant Proteins; Risk Factors; Streptokinase; Survival Rate; Thrombolytic Therapy; Tissue Plasminogen Activator
PubMed: 8990404
DOI: 10.1016/s0002-9149(96)00736-9 -
Enzyme 1988Plasminogen activators convert the proenzyme plasminogen to the active serine protease plasmin by hydrolysis of the Arg560-Val561 peptide bond. Physiological plasminogen... (Review)
Review
Plasminogen activators convert the proenzyme plasminogen to the active serine protease plasmin by hydrolysis of the Arg560-Val561 peptide bond. Physiological plasminogen activation is however regulated by several additional molecular interactions resulting in fibrin-specific clot lysis. Tissue-type plasminogen activator (t-PA) binds to fibrin and thereby acquires a high affinity for plasminogen, resulting in efficient plasmin generation at the fibrin surface. Single-chain urokinase-type plasminogen activator (scu-PA) activates plasminogen directly but with a catalytic efficiency which is about 20 times lower than that of urokinase. In plasma, however, it is inactive in the absence of fibrin. Chimeric plasminogen activators consisting of the NH2-terminal region of t-PA (containing the fibrin-binding domains) and the COOH-terminal region of scu-PA (containing the active site), combine the mechanisms of fibrin specificity of both plasminogen activators. Combination of t-PA and scu-PA infusion in animal models of thrombosis and in patients with coronary artery thrombosis results in a synergic effect on thrombolysis, allowing a reduction of the therapeutic dose and elimination of side effects on the hemostatic system.
Topics: Animals; Drug Synergism; Humans; Kinetics; Plasminogen Activators; Tissue Plasminogen Activator; Urokinase-Type Plasminogen Activator
PubMed: 3139404
DOI: 10.1159/000469150 -
Biochimica Et Biophysica Acta Feb 1980The vascular tree of the legs of human corpses was perfused with 0.15 M NaCl, and eluted with 2 M KSCN and finally with 0.15 M NaCl. The average total activity of human...
The vascular tree of the legs of human corpses was perfused with 0.15 M NaCl, and eluted with 2 M KSCN and finally with 0.15 M NaCl. The average total activity of human vascular plasminogen activator and protein eluted per leg was 29 800 Ploug units and 8.3 g respectively. Fibrin-Sepharose adsorbed the plasminogen activator activity, which could be eluted with 2 M KSCN. A small column containing from 0.5--1.9 ml of phenyl-Sepharose, normally coupled directly to the outlet of the fibrin-Sepharose column, adsorbed all the plasminogen activator activity. Elution of this hydrophobic matrix yielded a plasminogen activator preparation 17% pure judging from sodium dodecyl sulphate polyacrylamide gel electrophoresis. By this method human vascular plasminogen activator was found to have an Mr of 60 000. Upon reduction, two bands of Mr 30 000 and 31 000 were estimated. Human vascular plasminogen activator could be inhibited by diisopropylfluorophosphate. Isoelectric focusing yielded four major bands with the isoelectric points of 6.9, 7.4, 8.0 and 8.6. Human vascular plasminogen activator was found to be a relatively stable protein in purified form.
Topics: Chromatography, Affinity; Drug Stability; Femoral Artery; Femoral Vein; Humans; Isoelectric Point; Isoflurophate; Mercaptoethanol; Molecular Weight; Plasminogen Activators; Potassium; Thiocyanates
PubMed: 7188733
DOI: 10.1016/0005-2795(80)90176-2