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

Epidemiological and experimental studies have correlated hyperhomocysteinemia to a range of neurodegenerative conditions, including Alzheimer's disease, stroke, and Parkinson's disease. Although homocysteine-induced apoptosis in neurons has been extensively studied, little information is available regarding the effect of homocysteine on microglia. In this report, we demonstrated that homocysteine promoted proliferation and up-regulated the expression of CD11b (a marker of microglial activation). Consistent with our in vitro results, a significant increase in the number of CD11b-positive microglia was also observed in brain sections of mice with hyperhomocysteinemia. Homocysteine promoted the activity of NAD(P)H oxidases, resulting in the generation of reactive oxygen species. Up-regulation of NAD(P)H oxidase activity by homocysteine appears to be due to its ability to induce the phosphorylation of p47phox through the p38 MAPK pathway. Furthermore, inhibition of reactive oxygen species significantly blocked cellular proliferation and activation in microglia. Since microglial proliferation and activation play an important role in the development of several neurodegenerative disorders, our results reveal a novel role of homocysteine in the pathogenesis of neurodegenerative diseases.
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PMID:Homocysteine promotes proliferation and activation of microglia. 1913 Nov 43

The underlying pathogenesis of stroke is mediated by a variety of environmental risk factors as well as genetic ones. Thus, we have to evaluate the environmental factors precisely to identify the stroke-related gene polymorphisms. The Hisayama study, an epidemiological study of cardiovascular diseases, was established in 1961 in Hisayama, Japan. In 2002, a screening survey for the genetic study was performed in Hisayama. The Fukuoka Stroke Registry (FSR) is a hospital-based registration of stroke patients. Stroke specialists from eight medical centers in southern Japan have participated in FSR. In the present study, control and case subjects were recruited from the Hisayama study and FSR, respectively. We performed a genome-wide case-control study and found that a nonsynonymous SNP in PRKCH encoding a member of protein kinase C (PKCC eta) was significantly associated with brain infarction. As a candidate gene analysis, we investigated the role of NAD (P) H oxidase C242T polymorphism in the development of brain infarction. The C242T polymorphism was not associated with lacunar and atherothrombotic infarction; however, the presence of T-allele may have a protective role in the occurrence of atrial fibrillation and cardioembolic brain infarction. These studies may provide important information for the development of the therapeutic strategies against stroke.
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PMID:[Molecular epidemiology of cerebrovascular diseases; the Hisayama study and the Fukuoka Stroke Registry (FSR)]. 1919 8

Neurons require large amounts of energy to support their survival and function, and are therefore susceptible to excitotoxicity, a form of cell death involving bioenergetic stress that may occur in several neurological disorders including stroke and Alzheimer's disease. Here we studied the roles of NAD(+) bioenergetic state, and the NAD(+)-dependent enzymes SIRT1 and PARP-1, in excitotoxic neuronal death in cultured neurons and in a mouse model of focal ischemic stroke. Excitotoxic activation of NMDA receptors induced a rapid decrease of cellular NAD(P)H levels and mitochondrial membrane potential. Decreased NAD(+) levels and poly (ADP-ribose) polymer (PAR) accumulation in nuclei were relatively early events (<4 h) that preceded the appearance of propidium iodide- and TUNEL-positive cells (markers of necrotic cell death and DNA strand breakage, respectively) which became evident by 6 h. Nicotinamide, an NAD(+) precursor and an inhibitor of SIRT1 and PARP1, inhibited SIRT1 deacetylase activity without affecting SIRT1 protein levels. NAD(+) levels were preserved and PAR accumulation and neuronal death induced by excitotoxic insults were attenuated in nicotinamide-treated cells. Treatment of neurons with the SIRT1 activator resveratrol did not protect them from glutamate/NMDA-induced NAD(+) depletion and death. In a mouse model of focal cerebral ischemic stroke, NAD(+) levels were decreased in both the contralateral and ipsilateral cortex 6 h after the onset of ischemia. Stroke resulted in dynamic changes of SIRT1 protein and activity levels which varied among brain regions. Administration of nicotinamide (200 mg/kg, i.p.) up to 1 h after the onset of ischemia elevated brain NAD(+) levels and reduced ischemic infarct size. Our findings demonstrate that the NAD(+) bioenergetic state is critical in determining whether neurons live or die in excitotoxic and ischemic conditions, and suggest a potential therapeutic benefit in stroke of agents that preserve cellular NAD(+) levels. Our data further suggest that, SIRT1 is linked to bioenergetic state and stress responses in neurons, and that under conditions of reduced cellular energy levels SIRT1 enzyme activity may consume sufficient NAD(+) to nullify any cell survival-promoting effects of its deacetylase action on protein substrates.
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PMID:Nicotinamide prevents NAD+ depletion and protects neurons against excitotoxicity and cerebral ischemia: NAD+ consumption by SIRT1 may endanger energetically compromised neurons. 1928 25

Poly(ADP-ribose) polymerases (PARPs) are defined as cell signaling enzymes that catalyze the transfer of ADP-ribose units from NAD(+) to a number of acceptor proteins. PARP-1, the best characterized member of the PARP family, which currently comprises 18 members, is an abundant nuclear enzyme implicated in cellular responses to DNA injury provoked by genotoxic stress. PARP is involved in DNA repair and transcriptional regulation and is now recognized as a key regulator of cell survival and cell death as well as a master component of a number of transcription factors involved in tumor development and inflammation. PARP-1 is essential to the repair of DNA single-strand breaks via the base excision repair pathway. Inhibitors of PARP-1 have been shown to enhance the cytotoxic effects of ionizing radiation and DNA-damaging chemotherapy agents, such as the methylating agents and topoisomerase I inhibitors. There are currently at least five PARP inhibitors in clinical trial development. Recent in vitro and in vivo evidence suggests that PARP inhibitors could be used not only as chemo/radiotherapy sensitizers, but also as single agents to selectively kill cancers defective in DNA repair, specifically cancers with mutations in the breast cancer-associated genes (BRCA1 and BRCA2). PARP becomes activated in response to oxidative DNA damage and depletes cellular energy pools, thus leading to cellular dysfunction in various tissues. The activation of PARP may also induce various cell death processes and promotes an inflammatory response associated with multiple organ failure. Inhibition of PARP activity is protective in a wide range of inflammatory and ischemia-reperfusion-associated diseases, including cardiovascular diseases, diabetes, rheumatoid arthritis, endotoxic shock, and stroke. The aim of this review is to overview the emerging data in the literature showing the role of PARP in the pathogenesis of cancer and inflammatory diseases and unravel the solid body of literature that supports the view that PARP is an important target for therapeutic intervention in critical illness.
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PMID:PARP inhibitors: new partners in the therapy of cancer and inflammatory diseases. 1936 86

Apoptotic cell death contributes to neuronal loss in the penumbral region of brain infarction. Activated caspase-3 (ACA-3) cleaves proteins including poly(ADP-ribose) polymerase-1 (PARP-1) important in DNA repair, thus promoting apoptosis. Overactivation of PARP-1 depletes NAD(+) and ATP, resulting in necrosis. These cell death phenomena have been investigated mostly in experimental animals. We studied an autopsy cohort of 13 fatal ischemic stroke cases (symptoms 15 h to 18 days) and 2 controls by immunohistochemical techniques. The number of PARP-1 immunoreactive neurons was highest in the periinfarct area. Nuclear PARP-1 correlated with increasing neuronal necrosis (P = 0.013). Cytoplasmic PARP-1 correlated with TUNEL in periinfarct and core areas (P = 0.01). Cytoplasmic cleaved PARP-1 was inversely correlated with increasing necrotic damage (P = 0.001). PAR-polymers were detected in neurons confirming enzymatic activity of PARP-1. Cytoplasmic ACA-3 correlated with death receptor Fas (r (s) = 0.48; P = 0.005). In conclusion, the confirmation of the same pathways of cell death than previously described in experimental animal models encourages neuroprotective treatments acting on these mediators also in human stroke.
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PMID:Neuronal caspase-3 and PARP-1 correlate differentially with apoptosis and necrosis in ischemic human stroke. 1952 48

Reactive oxygen species (ROS) are produced at low levels in mammalian cells by various metabolic processes, such as oxidative phosphorylation by the mitochondrial respiratory chain, NAD(P)H oxidases, and arachidonic acid oxidative metabolism. To maintain physiological redox balance, cells have endogenous antioxidant defenses regulated at the transcriptional level by Nrf2/ARE. Oxidative stress results when ROS production exceeds the cell's ability to detoxify ROS. Overproduction of ROS damages cellular components, including lipids, leading to decline in physiological function and cell death. Reaction of ROS with lipids produces oxidized phospholipids, which give rise to 4-hydroxynonenal, 4-oxo-2-nonenal, and acrolein. The brain is susceptible to oxidative damage due to its high lipid content and oxygen consumption. Neurodegenerative diseases (AD, ALS, bipolar disorder, epilepsy, Friedreich's ataxia, HD, MS, NBIA, NPC, PD, peroxisomal disorders, schizophrenia, Wallerian degeneration, Zellweger syndrome) and CNS traumas (stroke, TBI, SCI) are problems of vast clinical importance. Free iron can react with H(2)O(2) via the Fenton reaction, a primary cause of lipid peroxidation, and may be of particular importance for these CNS injuries and disorders. Cholesterol is an important regulator of lipid organization and the precursor for neurosteroid biosynthesis. Atherosclerosis, the major risk factor for ischemic stroke, involves accumulation of oxidized LDL in the arteries, leading to foam cell formation and plaque development. This review will discuss the role of lipid oxidation/peroxidation in various CNS injuries/disorders.
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PMID:Lipid oxidation and peroxidation in CNS health and disease: from molecular mechanisms to therapeutic opportunities. 1962 72

Protective effects of estrogen against experimental stroke and neuronal ischemic insult are well-documented, but it is not known whether estrogen prevents ischemic injury to brain endothelium, a key component of the neurovascular unit. Increasing evidence indicates that estrogen exerts protective effects through mitochondrial mechanisms. We previously found 17beta-estradiol (E2) to improve mitochondrial efficiency and reduce mitochondrial superoxide in brain blood vessels and endothelial cells. Thus we hypothesized E2 will preserve mitochondrial function and protect brain endothelial cells against ischemic damage. To test this, an in vitro ischemic model, oxygen-glucose deprivation (OGD)/reperfusion, was applied to immortalized mouse brain endothelial cells (bEnd.3). OGD/reperfusion-induced cell death was prevented by long-term (24, 48 h), but not short-term (0.5, 12 h), pretreatment with 10 nmol/L E2. Protective effects of E2 on endothelial cell viability were mimicked by an estrogen-receptor (ER) agonist selective for ERalpha (PPT), but not by one selective for ERbeta (DPN). In addition, E2 significantly decreased mitochondrial superoxide and preserved mitochondrial membrane potential and ATP levels in early stages of OGD/reperfusion. All of the E2 effects were blocked by the ER antagonist, ICI-182,780. These findings indicate that E2 can preserve endothelial mitochondrial function and provide protection against ischemic injury through ER-mediated mechanisms.
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PMID:Estrogen-receptor-mediated protection of cerebral endothelial cell viability and mitochondrial function after ischemic insult in vitro. 1986 73

Oxidative stress in the rostral ventrolateral medulla (RVLM) increases sympathetic nervous system activity (SNA). Oral treatment with atorvastatin decreases SNA through antioxidant effects in the RVLM of stroke-prone spontaneously hypertensive rats (SHRSP). We aimed to examine whether centrally administered atorvastain reduces SNA in SHRSP and, if so, to determine whether it is associated with the reduction of oxidative stress induced by alteration of activities of nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase and superoxide dismutase (SOD) in the RVLM of SHRSP. SHRSP received atorvastatin (S-ATOR) or vehicle (S-VEH) by continuous intracerebroventricular infusion for 14 days. Mean blood pressure, heart rate, and SNA were significantly lower in S-ATOR than in S-VEH. Oxidative stress, Rac1 activity, NAD(P)H oxidase activity, Rac1, gp91(phox) and p22(phox) expression in the membrane fraction, and p47(phox) and p40(phox) expression in the cytosolic fraction in the RVLM were significantly lower in S-ATOR than in S-VEH. Rac1 expression in the cytosolic fraction and Mn-SOD activity, however, were significantly higher in S-ATOR than in S-VEH. Our findings suggest that centrally administered atorvastatin decreases SNA and is associated with decreasing NAD(P)H oxidase activity and upregulation of Mn-SOD activity in the RVLM of SHRSP, leading to suppressing oxidative stress.
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PMID:Sympathoinhibition induced by centrally administered atorvastatin is associated with alteration of NAD(P)H and Mn superoxide dismutase activity in rostral ventrolateral medulla of stroke-prone spontaneously hypertensive rats. 2004 Aug 88

C-reactive protein (CRP) has been demonstrated to induce blood-brain barrier disruption (BBB) involving NAD(P)H-oxidase dependent oxidative stress. It is unclear why CRP affects the BBB and not other vascular beds following stroke. Therefore we examined CRP receptor and NAD(P)H-oxidase expression levels in bovine brain- (BEC) and aortic endothelial cells. Dichlorodihydrofluorescein measurements revealed significantly higher CRP-induced reactive oxygen species (ROS) levels in BEC. Protein expression of the CRP-receptors CD16, CD32 and of the NAD(P)H-oxidase subunit p22phox were also significantly higher in BEC. In conclusion BEC show a higher vulnerability to CRP due to increased levels of CRP receptors and the NAD(P)H-oxidase.
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PMID:CRP-induced levels of oxidative stress are higher in brain than aortic endothelial cells. 2020 60

The study designed to estimate the state of the homeostatic system, levels of NAD and NAD-dependent dehydrogenases included 90 patients with complicated hypertensive disease and coronary heart disease following ischemic stroke. Hypercoagulation and enhanced platelet aggregation occurred throughout the entire follow-up period. Acute stage of ischemic stroke was associated with marked changes in bioenergetic and plastic processes.
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PMID:[The state of hemostatic system and platelet metabolism in patients with complicated hypertensive disease]. 2060 61


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