Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dysfunction in the vascular endothelium disturbs blood flow and predisposes individuals to atherosclerosis. Deteriorated fibrinolysis may further enhance the risk for atherothrombosis. We investigated 14 healthy volunteers and 24 patients with coronary heart disease. Endothelium-dependent (acetylcholine- and ischemia-induced) and endothelium-independent (nitroprusside-induced) vasodilatation in the forearm vasculature were studied using strain-gauge plethysmography, and the fibrinolytic system measured as the response of tissue plasminogen activator (t-PA) to provocation testing (20 min venous occlusion; VOT). When acetylcholine-induced vasodilatation was measured, endothelium-dependent vasodilatation differed between groups: those with coronary heart disease had a median value of 8.5 ml/min per 100 g tissue (25th to 75th percentile 4.8-10.3), compared with 11.6 ml/min per 100 g tissue (7.3-15.5) among healthy volunteers (P = 0.03). However, ischemia-induced vasodilatation showed no difference between the groups [26.8 (22.7-35.0) versus 29.1 (25.6-30.7) ml/min per 100 g tissue, respectively, NS]. Levels of t-PA after VOT also showed no difference between the groups [21.5 (16.5-31.9) versus 20.4 (11.8-31.5) ng/ml, respectively, NS]. Results of ischemia tests and levels of t-PA after VOT correlated only in patients with coronary heart disease (r = 0.5, P = 0.015), and not in healthy volunteers. We observed a positive correlation between endothelium-dependent vasodilatation function and endothelial release of t-PA. This indicates that the same mechanism that results in defective ischemia-induced endothelial relaxation in patients with coronary heart disease may also result in suppressed fibrinolytic capacity, thus making such patients more prone to atherothrombosis.
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PMID:Endothelial release of tissue-type plasminogen activator and ischemia-induced vasodilatation are linked in patients with coronary heart disease. 1039 Jan 17

The tissue type plasminogen activator (t-PA) is a serine protease that is involved in neuronal plasticity and cell death induced by excitotoxins and ischemia in the brain. t-PA activity in the central nervous system is regulated through the activation of serine protease inhibitors (serpins) such as the plasminogen activator inhibitor (PAI-1), the protease nexin-1 (PN-1), and neuroserpin (NSP). Recently we demonstrated in vitro that PAI-1 produced by astrocytes mediates the neuroprotective effect of the transforming growth factor-beta1 (TGF-beta1) in NMDA-induced neuronal cell death. To investigate whether serpins may be involved in neuronal cell death after cerebral ischemia, we determined, by using semiquantitative RT-PCR and in situ hybridization, that focal cerebral ischemia in mice induced a dramatic overexpression of PAI-1 without any effect on PN-1, NSP, or t-PA. Then we showed that although the expression of PAI-1 is restricted to astrocytes, PN-1, NSP, and t-PA are expressed in both neurons and astrocytes. Moreover, by using semiquantitative RT-PCR and Western blotting, we observed that only the expression of PAI-1 was modulated by TGF-beta1 treatment via a TGF-beta-inducible element contained in the PAI-1 promoter (CAGA box). Finally, we compared the specificity of TGF-beta1 action with other members of the TGF-beta family by using luciferase reporter genes. These data show that TGF-beta and activin were able to induce the overexpression of PAI-1 in astrocytes, but that bone morphogenetic proteins, glial cell line-derived neutrophic factor, and neurturin did not. These results provide new insights into the regulation of the serpins/t-PA axis and the mechanism by which TGF-beta may be neuroprotective.
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PMID:Transforming growth factor-beta1 as a regulator of the serpins/t-PA axis in cerebral ischemia. 1042 56

The changes of t-PA, PAI-1 gene expression and t-PA activity were investigated in coronary arteries of Acute Myocardial Infarction (AMI) rat by nucleic acid molecular hybridization and spectrophotometric assay. The effect of preconditioning on t-PA and PAI-1 was observed in this model. The results indicated that: (1) Tissue t-PA activity in ischemia was significantly decreased than that in control (P < 0.01). t-PA activity was obviously increased in preconditioning group (P < 0.01 compared with ischemia group). (2) t-PA and PAI-1 mRNA expression in ischemia were higher than that in control, especially PAI-1 4.6 times higher than that in control), while PAI-1 expression lower in preconditioning rat. (3) In situ hybridization showed t-PA and PAI-1 were primarily expressed by endothelial cells in vessels of rat heart. These data suggested that abnormal expression of PAI-1 and t-PA was involved in AMI. This fibrinolytic depress was associated with high PAI-1 expression. Preconditioning may be effective to protect myocardium through decreasing PAI-1 mRNA expression.
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PMID:[Changes in t-PA, PAI-1 gene expression of coronary arteries with preconditioning in acute myocardial infarction rat]. 1045 14

Increased fibrinolytic activity and consumption coagulopathy are common consequences of liver transplantation and are a major cause of morbidity and death. In the present investigation the effects of hepatic ischemia on the coagulation mechanism were studied in the stump-tail monkey. The results suggest that, although fibrinolytic activity is induced by both major intraabdominal operations as well as one hour of hepatic ischemia, consumption coagulopathy, presumably due to intravascular clotting, is enhanced by the revascularization of the ischemic liver, possibly because of clotting within the liver itself. Release of a plasminogen activator from the liver due to hepatic ischemia alone is not demonstrated by these studies. It is believed that the first phase of intravascular coagulation after liver transplantation is due to release of tissue activators from vascular endothelium, which may be minimized by the action of ganglionic blocking agents. The severity of fibrinolysis in this stage is aggravated by the "liverless state," in which no clearance of plasminogen activators occurs. The degree of liver injury directly affects the ability of the liver to control hypercoagulability in the second phase. Thrombus formation which we believe occurs during this phase may be minimized by use of continuous controlled heparinization.
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PMID:Effects of hepatic ischemia on coagulation in primates. Application to liver transplantation. 1048 79

Cardiac rupture is a fatal complication of acute myocardial infarction lacking treatment. Here, acute myocardial infarction resulted in rupture in wild-type mice and in mice lacking tissue-type plasminogen activator, urokinase receptor, matrix metalloproteinase stromelysin-1 or metalloelastase. Instead, deficiency of urokinase-type plasminogen activator (u-PA-/-) completely protected against rupture, whereas lack of gelatinase-B partially protected against rupture. However, u-PA-/- mice showed impaired scar formation and infarct revascularization, even after treatment with vascular endothelial growth factor, and died of cardiac failure due to depressed contractility, arrhythmias and ischemia. Temporary administration of PA inhibitor-1 or the matrix metalloproteinase-inhibitor TIMP-1 completely protected wild-type mice against rupture but did not abort infarct healing, thus constituting a new approach to prevent cardiac rupture after acute myocardial infarction.
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PMID:Inhibition of plasminogen activators or matrix metalloproteinases prevents cardiac rupture but impairs therapeutic angiogenesis and causes cardiac failure. 1050 7

The effects of the phospholipase activator melittin on amino acid and free fatty acid release from the rat cerebral cortex were monitored and compared with those of a secretory PLA(2), using a cortical cup technique with topical application of these agents in artificial cerebrospinal fluid. Melittin (10 microg/ml; 3.5 microM) elicited a rapid increase in the levels of superfusate amino acids; aspartate, glutamate, GABA, glycine, taurine, glutamine, phosphoethanolamine, alanine, serine and the free fatty acids arachidonic, linoleic, palmitic and oleic acid. PLA(2) (25 microg/ml) also enhanced amino acid efflux but its effects were significantly slower to develop than those of melittin. The results confirm previous indications of an ability of phospholipases to augment extracellular levels of several amino acids, including the excitotoxins glutamate and aspartate, and further implicate phospholipase activation as a significant contributor to cerebral ischemic injury. Melittin has the potential to be a useful tool with which to evaluate the role of phospholipases in ischemia injury.
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PMID:Melittin enhances amino acid and free fatty acid release from the in vivo cerebral cortex. 1057 97

Tissue type plasminogen activator (tPA) can be effective therapy for embolic stroke by restoring cerebral perfusion. However, a recent experimental study showed that tPA increased infarct size in a mouse model of transient focal ischemia, suggesting a possible adverse effect of tPA on ischemic tissue per se. In this report, the effects of tPA in two rat models of cerebral ischemia were compared. In experiment 1, rats were subjected to focal ischemia via injection of autologous clots into the middle cerebral artery territory. Two hours after clot injection, rats were treated with 10 mg/kg tPA or normal saline. Perfusion-sensitive computed tomography scanning showed that tPA restored cerebral perfusion in this thromboembolic model. Treatment with tPA significantly reduced ischemic lesion volumes measured at 24 hours by >60%. In experiment 2, three groups of rats were subjected to focal ischemia via a mechanical approach in which a silicon-coated filament was used intraluminally to occlude the origin of the middle cerebral artery. In two groups, the filament was withdrawn after 2 hours to allow for reperfusion, and then rats were randomly treated with 10 mg/kg tPA or normal saline. In the third group, rats were not treated and the filament was not withdrawn so that permanent focal ischemia was present. In this experiment, tPA did not significantly alter lesion volumes after 2 hours of transient focal ischemia. In contrast, permanent ischemia significantly increased lesion volumes by 55% compared with transient ischemia. These results indicate that in these rat models of focal cerebral ischemia, tPA did not have detectable negative effects. Other potentially negative effects of tPA may be dependent on choice of animal species and model systems.
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PMID:Effects of tissue type plasminogen activator in embolic versus mechanical models of focal cerebral ischemia in rats. 1059 35

Thrombolytic therapy has become a standard treatment for selected patients with acute myocardial infarction (MI). Various thrombolytic agents have been shown to decrease mortality. However, current thrombolytic agents still suffer significant shortcomings, such as a low optimal reperfusion rate delayed reperfusion. and incomplete myocardial perfusion. Furthermore, cyclic flow variations and reocclu.sions remain a significant cause of late morbidity and mortality. In thrombolysis with tissue plasminogen activator (t-PA), heparin seems to play an important role. However, it has several features that suggest that it may not be the optimal adjunct to thrombolytics, including weak and indirect action on thrombin, little access to clot-bound thrombin, inhibition by acute-phase plasma proteins, and its direct stimulation of platelet aggregation. Argatroban (NOVASTAN(R)), a small-molecule, synthetic, direct thrombin inhibitor, has several potential advantages over heparin, and prior studies suggest superior thrombin inhibition with favorable pharmacokinetic and pharmacodynamic properties warranting further investigation The Myocardial Infarction using NOVASTAN (R) and t-PA (MINT) study is a phase II, single-blind, angiographic trial directly comparing heparin versus two doses of argatroban in 120 patients with ST-elevation MI who present within 6 hours of symptom onset. The primary objective of the MINT trial is to assess the TIMI grade 3 flow and TIMI Frame Count at 90 minutes after the initiation of t-PA. This trial will also evaluate the safety of the combination of t-PA, argatroban, and aspirin. The incidence of clinical or silent ischemia, will be monitored. All patients will be followed up to 30 days for the composite endpoint of death, nonfatal recurrent myocardial infarction, coronary artery bypass surgery, PTCA, recurrent ischemia, and shock/new-onset heart failure.
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PMID:A Randomized, Blinded Study of Two Doses of Novastan(R) (Brand of Argatroban) Versus Heparin as Adjunctive Therapy to Recombinant Tissue Plasminogen Activator (Accelerated Administration) in Acute Myocardial Infarction: Rationale and Design of the Myocardial Infarction using Novastan(R) and T-PA (MINT) Study. 1060 50

Tumor necrosis factor-alpha (TNF-alpha) level, tissue-typed plasminogen activator(t-PA) activity and PA inhibitor (PAI) activity were determined in three groups: (1) 25 NIDDM patients with silent myocardial ischemia (SMI) or silent cerebral ischemia (SCI); (2) 18NIDDM patients without SMI or SCI; (3) 20 age-matched normal controls. Diagnosis of SMI or SCI was based on the finding of ischemic evidence by SPECT of myocardiotomograph or cerebrotomograph. All patients ECG and blood pressure were normal, and they had no history of clinical symptoms and signs of MI or CI. The result showed that the TNF-alpha level and PAI activity in the ischemia group were the highest and the t-PA activity in the ischemia group was the lowest, as compared with those in the other two groups respectively. It suggests that in NIDDM patients who have high TNF-alpha, high PAI activity, low t-PA, and even no symptoms and signs of MI or CI, anticoagulant therapy might be useful to prevent the progression of diabetic macroangiopathies.
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PMID:[Changes of serum TNF-alpha level, t-PA activivty and PAI activity in patients with silent myocardial ischemia or silent cerebral ischemia]. 1068 70

The angiopoietin/Tie receptor system may contribute to angiogenesis and vascular remodeling by mediating interactions of endothelial cells with smooth muscle cells and pericytes. The temporal expression of angiopoietin-1 (Angpo-1), angiopoietin-2 (Angpo-2), Tie-1, and Tie-2 mRNA was studied in a focal cerebral ischemia model in rats. The cDNA fragments obtained from reverse transcription polymerase chain reaction amplification were cloned and used as a probe to detect individual genes. Northern blot analysis showed a delayed increase of a 4.4-kb Angpo-1 transcript for up to 2 weeks after ischemia, eightfold higher than the values of the sham-operated controls. A biphasic expression of a 2.4-kb Angpo-2 transcript was noted, peaking at 24 hours (6.4-fold) and 2 weeks (4.6-fold) after ischemia. The expression of Tie-2 mRNA (4.3 kb), a receptor for Angpo-1, and Tie-1 mRNA (4.3 kb) also increased starting 24 hours after reperfusion and remained elevated for up to 2 weeks after ischemia. The temporal profiles of the expression of these genes were different from those of other angiogenic genes such as basic fibrobast growth factor/fibroblast growth factor receptor and vascular endothelial growth factor/vascular endothelial growth factor receptor and proteolytic enzymes (tissue-type plasminogen activator and urokinase plasminogen activator) and their inhibitors (plasminogen activator inhibitor-1). The expression patterns of these genes could be related to progressive tissue liquefaction and neovascularization after ischemia in this stroke model. Differential expression of these angiogenesis genes suggests the involvement of complex regulatory mechanisms that remain to be characterized.
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PMID:Induction of angiopoietin and Tie receptor mRNA expression after cerebral ischemia-reperfusion. 1069 77


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