Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.68 (tissue plasminogen activator)
 11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Significant current interest has focused on the possible value of fibrin-selective thrombolytic agents in acute stroke. Acute thrombosis contributes to carotid and vertebrobasilar arterial occlusions in the majority of acute stroke patients. Hence, fibrin(ogen)olytic agents may produce arterial recanalization and clinical benefit in thrombotic stroke. There are, however, unique features of cerebral tissue that suggest caution with the use of fibrin-selective agents in cerebral ischemia. The specific vascular anatomy and collateral flow suggest that salvage of the "ischemic penumbra" following vascular recanalization in focal ischemia is more likely to be successful than attempts in global ischemia. Recanalization may be associated with reperfusion injury and, more importantly, the risk of hemorrhagic transformation. There is little concrete information regarding the relative contribution of either event to post-thrombolysis cerebral injury. Early studies with exogenous fibrinolytic agents (urokinase, streptokinase) in completed stroke were regarded as inconclusive, demonstrating only an increased risk of intracerebral hemorrhage. Subsequent pilot studies in carotid and in vertebrobasilar territory thrombotic stroke have demonstrated that recanalization can result when exogenous agents are infused just proximal to the cerebral artery occlusion by interventional neuroradiological techniques. This experience and the advent of fibrin-selective agents (tissue plasminogen activator [tPA] and single-chain urokinase plasminogen activator) have led to the development of a multicenter prospective safety/dose-ranging study of tPA in acute (less than eight hours from symptom onset) thrombotic stroke. Following initial clinical assessment, computed tomography scan, and angiography, each patient with a documented cerebral artery occlusion appropriate to the clinical syndrome receives a preassigned intravenous dose of tPA over 60 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Investigational use of tPA in acute stroke. 314 17

After describing the mechanism of action, results and local and general complications of classical thrombolytic agents (streptokinase and urokinase) administered systemically, locally and peroperatively, then of modern thrombolytic agents (acyl enzyme, tPA and scuPA), the future perspectives of arterial fibrinolysis are discussed. These are based upon: analysis of the comparative efficacy of the different thrombolytic agents in the light of results seen, not only in peripheral arterial pathology but also in other indications, as in coronary pathology; discussion of the methods of administration of the thrombolytic agent in such a way as to obtain an optimal local concentration and at the same time reduced systemic fibrinolysis. better definition of the indications of thrombolysis in acute ischemia of the limbs in comparison with other therapeutic approaches, in particular surgery, taking into account the degree of ischemia, of etiological mechanism and the site of the arterial obstruction.
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PMID:[Arterial thrombolysis. Review and future prospects]. 314 94

We have given an overview of the management of the acute myocardial infarction patient utilizing the aggressive reperfusion techniques available today. Anatomic reperfusion rates have been over 95% with the combined methods described. The remaining problems technically are those of earlier reperfusion, methods to enhance myocardial recovery after ischemia, and prevention of restenosis or reocclusion. The use of laser methodology, coronary sinus retroperfusion, partial left heart bypass, and other innovative strategies may improve these results. The introduction of tissue plasminogen activator will affect our approach and will profoundly alter society's expectations of therapeutic success. Still, patients will die from acute myocardial infarction and its complications. The search for a prevention must, therefore, not be overshadowed by our current enthusiasm for reperfusion techniques. Hopefully, our current approach will become a historical footnote as breakthroughs in preventive strategies occur.
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PMID:Newer emergency reperfusion techniques in acute myocardial infarction. 328 52

Investigators have tried to limit ischemic cerebral infarct size by pharmacologic and surgical means with mixed results. Thrombolytic (fibrinolytic) therapy has been used in the past with unfavorable outcome. With advances in clinical and radiologic assessment and new knowledge of the pathophysiology of brain ischemia, thrombolytic therapy has now become a feasible pharmacologic intervention in acute stroke. Central nervous system hemorrhage, the most dreaded complication of fibrinolytic therapy, is rare in patients with acute myocardial infarction favorably treated with these agents. Risk of hemorrhagic transformation of ischemic cerebral infarcts is related to size, location, and age of patient. Anticoagulation therapy may increase its size, but not its likelihood. The development of clot-specific agents, such as tissue-type plasminogen activator, and careful patient selection make fibrinolytic therapy safe and potentially effective in acute stroke.
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PMID:Thrombolysis and stroke. Past and future. 329 8

Conventional activators of the fibrinolytic system used for coronary thrombolysis entail unavoidable delay, risk of bleeding, or both in contrast to tissue-type plasminogen activator (t-PA). Because the potential benefit of coronary thrombolysis is inversely related to the duration of antecedent ischemia, this study was performed to develop an approach for facilitated absorption of intramuscularly injected t-PA potentially adaptable for prompt, self-medication. In rabbits, absorption was markedly potentiated by hydroxylamine hydrochloride and electrical stimulation at the injection site. Intramuscular administration of t-PA in doses of 1 mg/kg of body weight, comparable to amounts given intravenously to patients (0.5-0.75 mg/kg), elicited peak blood levels of 431 +/- 52 (SEM) ng/ml 5 min after injection, well within the therapeutic range. In dogs, absorption facilitated by hydroxylamine promptly elicited angiographically documented coronary thrombolysis as well. The approach developed should ultimately permit prompt coronary thrombolysis and enhanced salvage of jeopardized ischemic myocardium in patients with life-threatening coronary thrombi.
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PMID:Coronary thrombolysis with facilitated absorption of intramuscularly injected tissue-type plasminogen activator. 385 78

In infective endocarditis vegetations are stabilized by fibrin. To learn if fibrin digestion would be therapeutic, experimental endocarditis was induced in rabbits by inoculation with a platelet-aggregating strain (Agg+) of Streptococcus sanguis and treated with recombinant tissue plasminogen activator (rt-PA), rt-PA with penicillin, or penicillin alone. Control rabbits were inoculated with saline. All treatments of Agg+ endocarditis reduced the mass of valvular vegetations and clinical signs of endocarditis, including the frequency of left axis deviation and heart ischemia. rt-PA with penicillin was more effective than penicillin or rt-PA alone, reducing the mass of vegetations and clinical signs to that of saline controls. Within 50 min, rt-PA cleared 5-fold more 111Indium-labelled platelets from the heart than untreated rabbits and 1.4-fold more after 3 days. Combined with penicillin, thrombolytic therapy for human endocarditis should be reconsidered.
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PMID:Therapeutic advantage of recombinant human plasminogen activator in endocarditis: evidence from experiments in rabbits. 749 78

The authors carried out an investigation on the "short" and "middle-term" effect of the prostanoid derivate iloprost on some molecular haemostatic markers in a group of peripheral vasculopathic patients with critical limb ischemia. The series consists of 10 patients (6 males, 4 females, age 52 +/- 5) suffering from peripheral obstructive vasculopathy at the III-IV stage by Fontaine. After overnight fasting, each patient was given an intravenous infusion of iloprost lasting six hours at the rate of 2 ng/kg/min and reaching approximately the global dosage of 50 gamma; before and after the infusion a venous blood sample was withdrawn; the experiment was repeated under the same conditions after a four week treatment with the drug administered daily at the same dosage. For each sample the plasma levels of betathromboglobulin (BTG) fibrinopeptide A (FPA), tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-I) and D-dimer (D-D) (ELISA, methods, kits Boehringer) were measured. The basal values of BTG, FPA, tPA, PAI-I and D-D were significantly increased compared to those of a control group; after the iloprost infusion (acute effect) significant changes of the BTG, FPA, tPA and PAI-I were not found; D-D only showed a marked reduction (p < 0.05); after the four week treatment with infusion the basal values of BTG, FPA, tPA and PAI-I resulted almost unchanged; D-D only showed a marked reduction (p < 0.05) both as regards the basal value and those after the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasma prothrombotic markers after a short- and middle term treatment with iloprost in arteriopathic patients with critical limb ischemia. 753 Mar 56

Ischemic electrocardiographic changes were recorded within 2 hours of admission using a 12-lead electrocardiographic continuous monitor with a 20-second scanning interval and an alarm mode for asymptomatic events. Blood samples were obtained at admission and at the moment of asymptomatic events (group A). In the other patients who did not develop ischemia, a second blood sample was taken 12 hours later (group B). We determined prothrombin time, activated partial thromboplastin time, clotting factor VIII activity, tissue plasminogen activator activity, tissue plasminogen activator inhibitor-1, cross-linked fibrin degradation product, and thrombin-antithrombin III complexes. There was a statistically significant difference between group A and B patients when the basal samples were analyzed for thrombin-antithrombin III (p = 0.046) and d-Dimer (p = 0.005). Prothrombin fragment 1 + 2 were significantly reduced, and d-Dimer was elevated when basal blood samples were compared with the second sample in patients who developed silent events (p = 0.008 and 0.055, respectively). A plasma concentration of thrombin-antithrombin III complex was also significantly decreased when sample 2 was compared with the basal blood sample (p = 0.039). Five recurrent episodes of angina and 2 nonfatal infarctions occurred, and 4 urgent revascularization procedures were performed in group A. In group B, there was only 1 nonfatal infarction (p = 0.01). The results of the present study suggest that a time-dependent thrombotic process is detectable in the blood stream as a cyclic movement. Further studies are needed to determine if some other factors, such as intensive shear stress in the vessel wall, may activate plaque instability during asymptomatic episodes.
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PMID:Time significance of acute thrombotic reactant markers in patients with and without silent myocardial ischemia and overt unstable angina pectoris. 761 Nov 44

Adjunctive therapy for acute myocardial infarction should include aspirin, beta-adrenergic blocking agents, and, in most patients, consideration of the use of angiotensin-converting enzyme inhibitors, especially if left ventricular function is reduced. Heparin has an important adjunctive role in enhancing early vessel patency in patients who receive tissue-type plasminogen activator and in decreasing the frequency of reocclusion of an infarct-related artery during any thrombolytic therapy. Heparin must also be administered to all patients who undergo primary angioplasty. Intravenously administered nitroglycerin and orally administered nitrates are probably most effective in patients with symptomatic ischemia. Calcium channel blockers and prophylactic antiarrhythmic agents are not indicated for most patients with acute myocardial infarction. Currently, insufficient evidence is available to recommend the widespread use of intravenously administered magnesium sulfate in the setting of acute myocardial infarction. In patients with ischemic pain, judicious intravenous administration of morphine can provide relief. Use of warfarin sodium should be reserved for patients at risk for left ventricular mural thrombus. Although the use of lipid-lowering agents after myocardial infarction has been controversial, recent studies have demonstrated the importance of such therapy for secondary prevention of death and morbidity.
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PMID:Adjunctive therapy in the management of patients with acute myocardial infarction. 773 Dec 56

The introduction of thrombolysis has reduced the mortality of acute myocardial infarction (MI) by 25%. Large-scale studies have revealed that especially patients over 65 benefit from this therapy. Nevertheless, many centers apply an age limit for thrombolytic therapy due to the higher risk of stroke or bleeding in elderly patients. In 1993 181 patients suffering from acute MI were admitted to the intensive care unit of the University Clinic of Internal Medicine, Graz, and 54 (29.4%) of them were treated with fibrinolytic drugs. In this paper we report on the successful thrombolytic management of acute MI in two male patients (87 and 88 years old) who were treated with 100 mg recombinant tissue-type plasminogen activator complex. As a sign of successful reperfusion a rapid increase in plasma creatinine kinase levels and fast amelioration of the ischemia-related ECG changes were observed. In the follow-up examination after four months the first patients showed only minimal exertional dyspnea and was otherwise well. The second patient died one month after MI following a laparotomy for ileus. We draw the conclusion that patients of advanced age also benefit from thrombolytic treatment of acute myocardial infarction, but the indications and contraindications have to be carefully observed.
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PMID:[Thrombolytic therapy of acute myocardial infarct in advanced age (based on 2 case reports)]. 773 94


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