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)

This paper describes the case of a 32-year-old man presenting with dense right hemiplegia and global aphasia caused by an acute left middle cerebral artery infarct that underwent successful endovascular therapy after being determined ineligible for intravenous tissue plasminogen activator. Clot transversion and balloon disruption followed by intra-arterial Alteplase resulted in successful re-canalization of his middle cerebral artery at 7 h 30 min. At 3 months post stroke, the patient had moderately severe expressive dysphasia but was mobilizing independently with normal right upper and lower limb strength. In conclusion, the 3 month outcome suggests that the therapeutic time window for endovascular therapy might exceed 6 h post stroke.
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PMID:Endovascular treatment of an acute left middle cerebral artery >6 h post stroke in a patient presenting with dysphasia and dense right hemiplegia. 1825 34

Thrombolytic agents activate plasminogen and induce a systemic fibrinolytic and anticoagulant state. Two thrombolytic drugs are used frequently in practice: streptokinase (SK) and alteplase (t-PA). Streptokinase mainly undergoes renal elimination with a half-life of 11-17 min, while alteplase is eliminating by the liver with a half-life of 4-6 min. Our goal was to examine whether renal and hepatic function influence the elimination and metabolism of thrombolytics and the efficacy of percutaneous coronary intervention (PCI) after using alteplase or streptokinase. 416 patients with myocardial infarction (MI) were treated from January 2001 to December 2003 (228 male and 189 female). Alteplase was used in 9 men and 6 women (mean age: 53.88 +/- 9.61 vs. 65.33 +/- 9.87 years, p = 0.07). Patients who underwent rescue PCI after administration of alteplase had slightly higher hepatic enzyme levels/alanine transaminase (ALT): 47.85 vs. 41.4 U/l; gamma-glutamyl transpeptidase (GGT): 69.5 vs. 44.8 U/l/. All patients treated with alteplase survived, rescue PCI was done in 8 cases. Streptokinase was used in 36 men and 28 women (mean age: 63.33 +/- 10.51 vs. 63 +/- 12.03 years, p = 0.9). We did not find a difference between serum creatinine levels of patients who received streptokinase and underwent PCI as compared to those who had not. Rescue PCI was done in 16 cases. 12 patients died in this group. In conclusion we have not found a significant correlation between the use of the thrombolytics and hepatic or renal function; this could indicate that such a slight impairment of liver and renal function does not influence pharmacokinetic properties of thrombolytics.
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PMID:Does impairment of renal and hepatic function influence the metabolism of thrombolytics in patients with myocardial infarction? 1844 16

In Japan, the intravenous tissue plasminogen activator (t-PA) Alteplase (0.6 mg/kg) administration of the within 3 h of the onset of acute ischemic stroke was approved for therapeutic use in the year 2006. t-PA induces thrombolysis in patients with acute ischemic stroke, and this method has gradually gained recognition among physicians and the general population. However, the number of patients who were treated using Alteplase is low (4,000-5,000 patients/year), and this figure accounts for only 2-3% of the annual number of cases of ischemic stroke. There is little doubt that Alteplase treatment is a potentially effective modality for some patients with acute ischemic stroke. The post-marketing surveillance of 4,749 Japanese patients treated using Alteplase showed that 33% of the patients had modified Rankin scale (mRS) scores of 0-1, 17% of patiens died and 4.5% presented with symptomatic intracerebral hemorrhage (ICH); these results were comparable to those from other countries. The expansion of the therapeutic time window has been a matter of concern. The investigators of the European Cooperative Acute Stroke Study (ECASS) have reported that there was significant improvement in the clinical outcomes of patients with acute ischemie stroke when Alteplase was administered 3-4.5 h after the onset of the symptoms. Mismatches in perfusion- and diffusion-weighted (DW) magnetic resonance imaging (MRI) images have been used for selecting patients 3 h after the onset of symptoms, and the findings from MRI, dwimages (DWI) and MR angiography are practical predictors of t-PA therapy within 3 h of onset. The Middle Cerebral Artery Embolism Local Fibrinolytic Intervention Trial (MELT) Japan study showed that local intra-arterial fibrinolysis is effective in patients with embolic MCA occlusion within 6 h of the onset of symptoms. Combining the initiation of intravenous t-PA administration with further intra-arterial fibrinolysis or mechanical thrombolectomy may improve the recanalization rate. Thrombolysis in combination with ultrasound-enhanced clot lysis is another attractive therapy. In Japan the neuroprotective agent edaravone (radical scavenger) is commonly used in combination with t-PA, and it is expected to decrease the hemorrhagic transformation after t-PA administration. Acute cerebral ischemic symptoms may occasionally precede thoracic aortic dissection. Thoracic aortic dissection after t-PA administration may prove to be fatal, and it is an important disorder that must be differentially diagnosed.
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PMID:[Thrombolysis by intravenous tissue plasminogen activator (t-PA)--current status and future direction]. 1917 6

Radioimmunotherapy (RIT) using radiolabeled antibodies or its fragments holds great promise for cancer therapy. However, its clinical potential is often limited by the undesirable radiation exposure to normal organs such as liver, kidney, and bone marrow. It is important to develop new strategies in RIT that enable protection of vital organs from radiation exposure while maintaining therapeutic radiation dose to the cancer. One way to achieve this is to clear radiometal rapidly from the circulation after accumulation of radioimmunoconjugates (RIC) in the tumor. Our strategy is to place a highly efficient and specific cleavable linker between radiometal chelate and the tumor targeting agent. Such linker must be resistant to cleavage by enzymes present in the plasma and tumor. After radiotargeting agents have accumulated in the tumor, a cleaving agent (protease) can be administered to the patient "on demand" to cleave the specific linker, resulting in the release of radiometal from the circulating RIC, in a form that can be cleared rapidly by the kidneys. TNKase, a serine protease tissue plasminogen activator and thrombolytic agent, which has been approved for clinical use in patient with acute myocardial infarction, was selected as an on-demand cleaving agent in our model. TNKase specific on-demand cleavable (ODC) linkers were identified through screening random internally quenched fluorescent resonance energy transfer (FRET) "one-bead-one-compound" (OBOC) combinatorial peptide libraries. FRET-OBOC peptide libraries containing L-amino acid(s) in the center of the random linear peptide and D-amino acids flanking both sides of the L-amino acid(s) were used for screening. Peptide beads susceptible to TNKase but resistant to plasma and tumor-associated protease cleavage were isolated for sequence analysis. The focus of this chapter is on the methods that have been used to identify and characterize ODC linkers and protease-specific substrates.
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PMID:On-demand cleavable linkers for radioimmunotherapy. 1937 73

The US Food and Drug Administration (FDA) approved the use of intravenous (IV) recombinant tissue plasminogen activator (rt-PA) in 1996, on the basis of the results of the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Study. IV rt-PA therapy at a dose of 0.9 mg/kg has been approved internationally for the treatment of hyperacute ischemic stroke. After a dose comparison study using duteplase and a multicenter study using a single dose of alteplase (Japan Alteplase Clinical Trial: J-ACT), the administration of IV rt-PA therapy at a dose of 0.6 mg/kg was approved in Japan in 2005. Immediately after the approval, the Japan Stroke Society published the Japanese guidelines for this low-dose therapy. Two years after the approval in Japan, the outcome of IV rt-PA therapy in Japan was observed to be comparable to that of NINDS rt-PA therapy and to those published in studies based in Western nations. Several trials have reported predictors of unfavorable outcome for IV rt-PA therapy. Patients with severe strokes (higher NIHSS score, coma), higher age at disease onset, aortic arch dissection, higher blood pressure, higher blood sugar, occlusion of the internal carotid artery (ICA) or tandem lesion of the left ICA and right middle cerebral artery (MCA), or the presence of major early ischemic changes as observed upon computed tomography (CT) or magnetic resonance imaging (MRI), showed a greater probability for unfavorable response to treatment. The results of the randomised 2008 trial conducted by the third European Cooperative Acute Stroke Study (ECASS III) suggested that treatment with IV rt-PA administered 3-4.5 hours after symptom onset can still induce significant improvement in clinical outcomes after an acute ischemic stroke as opposed to a placebo. MRI-based thrombolysis might be safer than standard CT-based thrombolysis. A combination of reperfusion therapies, IV rt-PA and sonothrombolysis, neuroprotective agents or antiplatelet agents may be effective. However, currently available data do not provide conclusive evidence for the safety or efficacy of these combination therapies. Patients having ICA occlusion may require alternatives including a higher dose of alteplase, combined IV/IA thrombolysis, or possibly mechanical thrombectomy by using a thrombus-removal device.
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PMID:[Prospects of thrombolytic therapy for acute ischemic stroke]. 1980 99

After the success of the 1995 National Institutes of Neurological Disorders and Stroke (NINDS) study using intravenous (i.v.) recombinant tissue plasminogen activator (rt-PA, alteplase) within 3 hours in acute stroke, this therapy was approved worldwide and has been a standard therapy for acute stroke patients. In Japan, IV alteplase at a dose of 0.6 mg/kg was approved in 2005 after a multicenter study using this low dose of alteplase (Japan Alteplase Clinical Trial [J-ACT]). IV rt-PA can drastically improve stroke outcomes. However, more than half of treated patients are not independent in the chronic stage. In addition, the therapeutic time window was so limited that many stroke patients do not have a chance to receive the therapy. In 2008, European Cooperative Acute Stroke Study III showed that IV rt-PA administered between 3 and 4.5 hours after stroke onset significantly improved clinical outcomes in stroke patients; the success resulted in the renewal of recommendation in guidelines in Europe, Canada, and the United States. Several therapeutic strategies, including endovascular therapy, sonothrombolysis, and neuroprotective therapy, may improve the efficacy of IV rt-PA.
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PMID:[Intravenous rt-PA therapy for acute ischemic stroke: efficacy and limitations]. 2003 Feb 14

Alteplase (tissue plasminogen activator, tPA) is currently the only FDA-approved treatment that can be given to acute ischemic stroke (AIS) patients if patients present within 3 h of an ischemic stroke. After 14 years of alteplase clinical research, evidence now suggests that the therapeutic treatment window can be expanded 4.5 h, but this is not formally approved by the FDA. Even though there remains a significant risk of intracerebral hemorrhage associated with alteplase administration, there is an increased chance of favorable outcome with tPA treatment. Over the last 30 years, the use of preclinical models has assisted with the search for new effective treatments for stroke, but there has been difficulty with the translation of efficacy from animals to humans. Current research focuses on the development of new and potentially useful thrombolytics, neuroprotective agents, and devices which are also being tested for efficacy in preclinical and clinical trials. One model in particular, the rabbit small clot embolic stroke model (RSCEM) which was developed to test tPA for efficacy, remains the only preclinical model used to gain FDA approval of a therapeutic for stroke. Correlative analyses from existing preclinical translational studies and clinical trials indicate that there is a therapeutic window ratio (ARR) of 2.43-3 between the RSCEM and AIS patients. In conclusion, the RSCEM can be used as an effective translational tool to gauge the clinical potential of new treatments.
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PMID:Translational stroke research using a rabbit embolic stroke model: a correlative analysis hypothesis for novel therapy development. 2053 48

Alteplase is the only drug licensed for acute ischemic stroke, and in this formulation, the thrombolytic agent recombinant tissue plasminogen activator (rtPA) is stabilized in a solution of L-arginine. Improved functional outcomes after alteplase administration have been shown in clinical trials, along with improved histological and behavioral measures in experimental models of embolic stroke. However, in animal models of mechanically induced ischemia, alteplase can exacerbate ischemic damage. We have systematically reviewed the literature of both rtPA and L-arginine administration in mechanical focal ischemia. The rtPA worsens ischemic damage under certain conditions, whereas L-arginine can have both beneficial and deleterious effects dependent on the time of administration. The interaction between rtPA and L-arginine may be leading to the production of nitric oxide, which can cause direct neurotoxicity, altered cerebral blood flow, and disruption of the neurovascular unit. We suggest that alternative formulations of rtPA, in the absence of L-arginine, would provide new insight into rtPA neurotoxicity, and have the potential to offer more efficacious thrombolytic therapy for ischemic stroke patients.
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PMID:The contribution of L-arginine to the neurotoxicity of recombinant tissue plasminogen activator following cerebral ischemia: a review of rtPA neurotoxicity. 2073 61

Thrombotic occlusion of a prosthetic valve continues to be an uncommon but life threatening complication of mechanical valves. However, recurrent prosthetic valve thrombosis is yet a rare complication. Urokinase and tissue plasminogen activator (tPA) have previously been used with success in cases of recurrent thrombus formation and/or failure of streptokinaSe treatment. We report the first three cases of recurrent prosthetic mitral valve thrombosis in Pakistan which were treated with Reteplase that resulted in re-establishment of adequate blood flow across the valve with reduction of mean gradient to normal.
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PMID:Thrombolysis with reteplase for recurrent mechanical heartvalve thrombosis. 2137 77

Recombinant tissue-type plasminogen activator (rt-PA) has been produced in different hosts. In this research, transgenic tobacco was selected for production of human rt-PA. Transgenic plants were analyzed by polymerase chain reaction (PCR) and reverse-transcription (RT)-PCR. The protein was extracted by Lysine Sepharose chromatography column and was further purified by HiTrap desalting column. The function of eluted protein was analyzed on zymography gel. The results showed that the 1.7-kb cDNA of tissue-type plasminogen activator (t-PA) (as well as a shortened 650-bp transcript of t-PA) has been expressed in transgenic plants. The anticipated 63-kD protein band and an additional 53-kD protein were observed in transgenic plants. Finally, zymography assay revealed that the purified rt-PA has anticipated appropriate activity comparable to a positive control drug (Alteplase). On the whole, we can say that transgenic tobacco is a good alternative host for production of t-PA.
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PMID:Expression analysis and purification of human recombinant tissue type plasminogen activator (rt-PA) from transgenic tobacco plants. 2144 53


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