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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebral ischemia induces a complex series of molecular pathways involving signaling mechanisms, gene transcription, and protein formation. The proteases and free radicals involved are important, both individually and in concert, at each of the steps in the injury cascade. Matrix metalloproteinases (MMPs) and serine proteases are essential in the breakdown of the extracellular matrix around cerebral blood vessels and neurons, and their action leads to opening of the blood-brain barrier, brain edema, hemorrhage, and cell death. Reactive oxygen and nitrogen species affect the signaling pathways that induce the enzymes, the stability of the mRNA, and their activation processes. Mice that either lack MMP genes or overexpress free radical-removing genes exhibit diminished cerebral damage after stroke. Drugs that block MMP activity, or are free radical scavengers, significantly reduce ischemic damage. Understanding the relationship between proteases and free radicals in cerebral ischemia is critical for the design of therapeutic agents aimed at controlling cell death in ischemic tissues.
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PMID:Matrix metalloproteinases and free radicals in cerebral ischemia. 1592 79

Several neurological disorders such as stroke, amyotrophic lateral sclerosis and epilepsy result from excitotoxic events and are accompanied by neuronal cell death. These processes engage multiple signalling pathways and recruit numerous molecular components, in particular several families of protein kinases and protein phosphatases. While many investigations have examined the importance of protein kinases in excitotoxicity, protein phosphatases have not been well studied in this context. However, recent advances in understanding the functions of protein phosphatases have suggested that they may play a neuroprotective role. In this review, we summarize some of the recent findings that illustrate the pleiotropic and complex functions of tyrosine and serine/threonine protein phosphatases in the cascade of events leading to neuronal cell death, and highlight their potential intervention in limiting the extent of neuronal death.
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PMID:Protein phosphatases and their potential implications in neuroprotective processes. 1592 6

Neurological disturbances frequently emerge in antiphospholipid syndrome (APS). One hundred and twenty four patients (100 women, 24 men, mean age 37.5 +/- 11.3 years) with primary APS (PAPS), including 76 patients with Sneddon's syndrome and positive antibodies to phospholipids (aPL), have been studied. A structure of neurological disturbances was as follows: ischemic lesions of cerebral blood flow (LCBF) which comprised stroke and transient LCBF (91%); thrombosis of brain venous sinuses (3%); epileptic seizures (24%); headache (65%); chorea (15%); visual neuropathy (9%); peripheral neuropathy (6%); multiple-sclerosis-like syndrome (10%); myasthenia syndrome (1%); syndrome of parkinsonism of non-vascular genesis (1%) and psychotic disorders (2%). 84% patients had main systemic APS symptoms (fetal loss, thrombosis), which preceded neurological appearances in 78% cases. All the patients had aPL: aPL to cardiolipin (aCL) and/or lupus coagulant (LC) and/or aPL to phosphatidyl serine, phosphatidyl inositol, phosphatidyl ethanolamine. In some patients, aCL titres ranged from positive to negative values and LC was not consistently detected. Thus, the presence of clinical symptoms of PAPS including neurological disturbances demands an investigation of different aPL types as well as a replicate study for immunological confirmation of PAPS.
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PMID:[Neurological appearances of primary antiphospholipid syndrome]. 1598 22

Neuroserpin is a member of the serpin family of serine protease inhibitors. Tissue distribution analysis reveals a predominantly neuronal expression during the late stages of neurogenesis and, in the adult brain, in areas where synaptic changes are associated with learning and memory (synaptic plasticity). In vitro studies revealed complex formation between neuroserpin and different serine proteases, i.e. tPA, uPA, and plasmin. The neuroserpin-target complex has so far not been characterized in vivo. However, some investigations help to understand the functional role of this serpin. Neuroserpin was shown to be involved in the regulation of the morphology of neuroendocrine cells in culture, possibly by modulating the degradation of the extracellular matrix by proteolytic enzymes such as tPA. Moreover, a role of neuroserpin in mood regulation has been deduced from the over- and underexpression of neuroserpin in genetically modified mice, which showed increased anxiety and novelty-induced hypo-locomotion. In pathological conditions of the central nervous system (i.e. stroke and seizures), neuroserpin plays a neuroprotective role, probably by blocking the deleterious effects of tPA. A familial form of a neurodegenerative disease, termed familial encephalopathy with neuroserpin inclusion bodies, is caused by point mutations in the neuroserpin gene. This condition is characterized by the intracellular polymerization and accumulation of mutated neuroserpin, leading to neuronal death and dementia.
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PMID:Neuroserpin. 1614 12

Tissue kallikrein is a serine proteinase capable of cleaving kininogen substrate to produce the potent vasodilator kinin peptide. Kinin mediates a complex set of physiological actions through its receptor signaling. Systemic delivery of the kallikrein gene in an adenoviral vector significantly reduced stroke-induced mortality rate, blood pressure elevation, and aortic hypertrophy in hypertensive Dahl-salt sensitive rats fed a high salt diet. Using a focal cerebral ischemic rat model induced by middle cerebral artery occlusion, intravenous or intracerebroventricular kallikrein gene delivery significantly reduced ischemia/repefusion (I/R)-induced neurological deficits, cerebral infarction, neuronal and glial cell apoptosis, and inflammatory cell infiltration, while promoting angiogenesis and neurogenesis in the ischemic brain. A continuous infusion of a sub-depressor dose of tissue kallikrein protein through implanted minipump decreased I/R-induced neurological dysfunction and cerebral infarction, inflammation and oxidative stress independent of kallikrein's blood pressure-lowering effect. Moreover, kallikrein offered neuroprotection even when delivered at one day after the onset of stroke. Kallikrein's protective effects were blocked by the kinin B2 receptor antagonist icatibant. The role of the kinin B2 receptor in mediating the protective effect against ischemic brain injury was further confirmed by increases in mortality rate and post-ischemic brain injury in kinin B2 receptor-deficient mice. Taken together, these results suggest a novel function of kallikrein as an anti-inflammatory and anti-oxidative agent in protecting the brain against ischemic stroke-induced injuries. These findings also raise the possibility that tissue kallikrein may have value in the treatment of acute ischemic stroke.
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PMID:Experimental therapy with tissue kallikrein against cerebral ischemia. 1636 19

Cerebrovascular deposits of beta-amyloid (Abeta) peptides are found in Alzheimer's disease and cerebral amyloid angiopathy with stroke or dementia. Dysregulations of angiogenesis, the blood-brain barrier and other critical endothelial cell (EC) functions have been implicated in aggravating chronic hypoperfusion in AD brain. We have used cultured ECs to model the effects of beta-amyloid on the activated phosphorylation states of multifunctional serine/threonine kinases since these are differentially involved in the survival, proliferation and migration aspects of angiogenesis. Serum-starved EC cultures containing amyloid-beta peptides underwent a 2- to 3-fold increase in nuclear pyknosis. Under growth conditions with sublethal doses of beta-amyloid, loss of cell membrane integrity and inhibition of cell proliferation were observed. By contrast, cell migration was the most sensitive to Abeta since inhibition was significant already at 1 muM (P = 0.01, migration vs. proliferation). In previous work, intracellular Abeta accumulation was shown toxic to ECs and Akt function. Here, extracellular Abeta peptides do not alter Akt activation, resulting instead in proportionate decreases in the phosphorylations of the MAPKs: ERK1/2 and p38 (starting at 1 microM). This inhibitory action occurs proximal to MEK1/2 activation, possibly through interference with growth factor receptor coupling. Levels of phospho-JNK remained unchanged. Addition of PD98059, but not LY294002, resulted in a similar decrease in activated ERK1/2 levels and inhibition of EC migration. Transfection of ERK1/2 into Abeta-poisoned ECs functionally rescued migration. The marked effect of extracellular Abeta on the migration component of angiogenesis is associated with inhibition of MAPK signaling, while Akt-dependent cell survival appears more affected by cellular Abeta.
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PMID:Dissociation of ERK and Akt signaling in endothelial cell angiogenic responses to beta-amyloid. 1642 23

Antiphospholipid syndrome is characterized by arterial or venous thrombosis, and the presence of antiphospholipid antibodies (aPL). APL are considered to be a cause of an acquired hypercoagulable state leading to stroke and transient ischemic attack (TIA). We examined the causes in 50 young patients with ischemic stroke. The most prevalent cause was atherosclerosis and the incidence of APS was 12.5%. APL comprise a heterogeneous group of autoantibodies, such as beta2-glycoprotein I dependent anticardiolipin antibody (beta2-GPIaCL), lupus anticoagulant (LA), and other antiphospholid-protein antibodies. We examined the incidence and the pathogenic role of antiphospholipid protein antibodies. The subjects comprised 250 patients (155 male, 95 females) with ischemic stroke, aged 26 to 92 years (mean 72 years). We measured beta2-GPI aCL, IgG aCL, LA, phosphatidyserine dependent antiprothrtombin antibody (PS-PT), antiphosphatidyl-serine antibody (PS), antiphosphatidyl-inositol antibody (PI) in each patient. The incidence of beta2-GPI aCL, IgG aCL, LA, phosphatidyserine, PS-PT, PS, and PI was 2.8%, 12%, 9.2%, 7.2%, 9.6%, and 8.8%, respectively. The incidence of young stroke patients under 50 years was 5.2%. Among 13 young stroke patients, 5 had SLE. Among 23 patients with LA., 18 (78%) patients had PS-PT. Anti-PS-PT antibody is closely related to LA. Antinuclear antibody was detected in 79% of the patients with aPS and/or aPI. We compared the carotid ultrasonographic findings in positive aPI or aPS patients with those in negative ones. Increased IMT, plaque score and carotid stenosis were more common in aPI and aPS-positive patients than in negative ones Three of 5 patients who showed positive beta2-GPI, aCL and LA, simulataneously, had sysyemic lupus erythematosus as an immulological background. Two of 3 patients with PI and/or PS and beta2-GPI and/or LA were patients with SLE. Antiphospholipid antibody was considered to be a risk factor of stroke, especially in SLE and/or young female patients. The incidence of lupus anticoagulant is more common than beta2-GPI aCL in ischemic stroke. In SLE patients with stroke, multi-antiphospholipid-protein antibodies was inclined to be present. LA is closely related to ant-PS-PT and aPI and aPS are associated with anti-nuclear antibody and precipitation of atherosclerosis.
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PMID:[Antiphospholipid syndrome and stroke]. 1644 44

Rho-associated kinases (ROCKs), the immediate downstream targets of RhoA, are ubiquitously expressed serine-threonine protein kinases that are involved in diverse cellular functions, including smooth muscle contraction, actin cytoskeleton organization, cell adhesion and motility, and gene expression. Recent studies have shown that ROCKs may play a pivotal role in cardiovascular diseases such as vasospastic angina, ischemic stroke, and heart failure. Indeed, inhibition of ROCKs by statins or other selective inhibitors leads to the upregulation and activation of endothelial nitric oxide synthase (eNOS) and reduction of vascular inflammation and atherosclerosis. Thus inhibition of ROCKs may contribute to some of the cholesterol-independent beneficial effects of statin therapy. Currently, two ROCK isoforms have been identified, ROCK1 and ROCK2. Because ROCK inhibitors are nonselective with respect to ROCK1 and ROCK2 and also, in some cases, may be nonspecific with respect to other ROCK-related kinases such as myristolated alanine-rich C kinase substrate (MARCKS), protein kinase A, and protein kinase C, the precise role of ROCKs in cardiovascular disease remains unknown. However, with the recent development of ROCK1- and ROCK2-knockout mice, further dissection of ROCK signaling pathways is now possible. Herein we review what is known about the physiological role of ROCKs in the cardiovascular system and speculate about how inhibition of ROCKs could provide cardiovascular benefits.
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PMID:Physiological role of ROCKs in the cardiovascular system. 1646 61

Through a series of successive, cascade-like proteinase activation and amplification steps, any vascular injury triggers a rapid burst of alpha-thrombin, a trypsin-like serine proteinase. Thrombin, the main executioner of the coagulation cascade, has procoagulant as well as anticoagulant and antifibrinolytic properties. It exhibits quite diverse physiological functions, but also gives rise to several thrombotic disorders, such as thromboembolism, myocardial infarction, and stroke, thus making it an attractive target for antithrombotic agents. Thrombin interacts specifically with several protein substrates, receptors, cofactors, inhibitors, carbohydrates, and modulators. It cleaves fibrinogen, factors XI (FXI) and FXIII, cofactors V and VIII, and the thrombin receptors; uses thrombomodulin to activate protein C and thrombin-activatable-fibrinolysis inhibitor; is inhibited by heparin cofactor II and antithrombin III with the help of acidic carbohydrates; and its activity/specificity is modulated by sodium ions. A large number of crystal structures of alpha-thrombin in complexes with synthetic polypeptides and protein inhibitors, substrate fragments, cofactors, and carbohydrates have displayed extended recognition sites on the thrombin surface, reflecting the versatility and multifunctional specificity of this remarkable proteinase. These structures essentially show that the thrombin surface can be subdivided into several functional regions, which recognize different chemical moieties. By using different combinations of these surface elements, thrombin can interact with a variety of molecules with high specificity, accounting for its multifunctional properties.
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PMID:The structure of thrombin: a janus-headed proteinase. 1667 63

Mitochondrial encephalopathy lactic acidosis stroke like episodes (MELAS) is a progressive neurodegenerative disorder with varying age of onset. It is a clinically and genetically heterogeneous disease. Molecular etiology of MELAS is not known in several cases. We have identified a unique individual with late onset MELAS at the age of 55 years. We have analyzed the complete mitochondrial genome of the tissue and blood samples of the patient. One novel heteroplasmic mutation (C13565A) in NADH dehydrogenase 5 subunit (ND5) gene was found only in the tissue sample but not in the blood. This mutation is missense causing a change of amino acid serine to tyrosine at position 410. This mutation was found neither in controls nor in world populations. This study has also confirmed ND5 as a hotspot for the mitochondrial diseases. This will be of great help for the clinicians in the diagnosis of MELAS.
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PMID:Clinical and genetic uniqueness in an individual with MELAS. 1674 38


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