Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ischemic tolerance in the brain, in which sub-threshold insults increase resistance to subsequent injurious ischemia, is a powerful adaptive defense that involves an endogenous program of neuroprotection. Emerging evidence from genomic studies suggests diverse stimuli that trigger preconditioning achieve neuroprotection through a common process which depends on a fundamental reprogramming of the response to injury. Such reprogramming of the genomic response to injury leads to the induction of novel neuroprotective pathways not ordinarily found in the setting of ischemia. Genomic studies also indicate that the nature of the preconditioning stimulus (eg, brief ischemia or endotoxin [lipopolysaccharide]) dictates the phenotype of neuroprotection, a phenotype that parallels protective adaptations also found in certain physiological conditions where the preconditioning stimulus exists at levels that can induce injury. The idea that preconditioning leads to a fundamental reprogramming event that confers neuroprotection is a novel and important concept in the field of ischemic tolerance. Moreover, the view that distinct preconditioning stimuli confer neuroprotection via effectors that differ according to the nature of the preconditioning stimulus offers promise that multiple, nonoverlapping pathways may be discovered as novel neuroprotective therapies.
Stroke 2007 Feb
PMID:Preconditioning reprograms the response to ischemic injury and primes the emergence of unique endogenous neuroprotective phenotypes: a speculative synthesis. 1726 15

Curcumin, a member of the curcuminoid family of compounds, is a yellow colored phenolic pigment obtained from powdered rhizome of C. longa Linn. Recent studies have demonstrated that curcumin has protective effects against cerebral ischemia/reperfusion injury. However, little is known about its mechanism. Disruption of the blood-brain barrier occurs after stroke. Protection of the blood-brain barrier has become an important target of stroke interventions in experimental therapeutic. The objective of the present study was to determine whether curcumin prevents cerebral ischemia/reperfusion injury by protecting blood-brain barrier integrity. We report that a single injection of curcumin (1 and 2 mg/kg, i.v.) 30 min after focal cerebral ischemia/reperfusion in rats significantly diminished infarct volume, improved neurological deficit, decreased mortality, reduced the water content of the brain and the extravasation of Evans blue dye in ipsilateral hemisphere in a dose-dependent manner. In cultured astrocytes, curcumin significantly inhibited inducible nitric oxide synthase (iNOS) expression and NO(x) (Nitrites/nitrates contents) production induced by lipopolysaccharide (LPS)/tumor necrosis factor alpha (TNF(alpha)). Furthermore, curcumin prevented ONOO(-) donor SIN-1-induced cerebral capillaries endothelial cells damage. We concluded that curcumin ameliorates cerebral ischemia/reperfusion injury by preventing ONOO(-) mediated blood-brain barrier damage.
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PMID:Neuroprotective effect of curcumin on focal cerebral ischemic rats by preventing blood-brain barrier damage. 1730 17

Systemic inflammatory stimuli, such as infection, increase the risk of stroke and are associated with poorer clinical outcome. The mechanisms underlying the impact of systemic inflammatory stimuli on stroke are not well defined. We investigated the impact of systemic inflammation on experimental stroke and potential mechanisms involved. Focal cerebral ischemia was induced by intraluminal filament occlusion of the middle cerebral artery (MCAo). Brain damage and neurological deficit 24 h after MCAo were exacerbated by systemic lipopolysaccharide (LPS) administration. This exacerbation was critically dependent on interleukin (IL)-1, because coadministration of IL-1 receptor antagonist abolished the effect of LPS on brain damage. Systemic administration of IL-1 increased ischemic damage to a similar extent as LPS and also exacerbated brain edema. IL-1 markedly potentiated circulating levels of the acute phase proteins, serum amyloid A and IL-6, and the neutrophil-selective CXC chemokines, KC and macrophage inflammatory protein-2. Neutrophil mobilization and cortical neutrophil infiltration were aggravated by IL-1 before changes in ischemic damage. Neutropenia abolished the damaging effects of systemic IL-1. These data show for the first time that an acute systemic inflammatory stimulus is detrimental to outcome after experimental stroke and highlight IL-1 as a critical mediator in this paradigm. Our data suggest IL-1-induced potentiation of neutrophil mobilization via CXC chemokine induction is a putative mechanism underlying this effect. Our results may help to explain the poorer outcome in stroke patients presenting with infection and may have implications for neurodegenerative diseases involving neurovascular alterations, such as Alzheimer's disease, in which systemic inflammation can modulate disease progression.
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PMID:Systemic inflammatory stimulus potentiates the acute phase and CXC chemokine responses to experimental stroke and exacerbates brain damage via interleukin-1- and neutrophil-dependent mechanisms. 1744 25

1. Cerebral vessels express oestrogen receptors (ER) in both the smooth muscle and endothelial cell layers of cerebral blood vessels. Levels of ERalpha are higher in female rats chronically exposed to oestrogen, either endogenous or exogenous. 2. Chronic exposure to oestrogen, either endogenous (normally cycling females) or exogenous (ovariectomized with oestrogen replacement), results in cerebral arteries that are more dilated than arteries from ovariectomized counterparts when studied in vitro. This effect is primarily mediated by an increase in the production of vasodilator factors, including nitric oxide (NO) and prostacylin. In contrast, oestrogen appears to suppress the production of endothelial-derived hyperpolarizing factor. Oestrogen treatment increases cerebrovascular levels of endothelial nitric oxide synthase (eNOS), cyclo-oxygenase (COX)-1 and prostacyclin synthase. In addition, via activation of the phosphatidylinositol 3-kinase/Akt pathway, both acute and chronic oestrogen exposure increases eNOS phosphorylation, increasing NO production. 3. Oestrogen receptors have also been localized to cerebrovascular mitochondria and exposure to oestrogen increases the efficiency of energy production while simultaneously reducing mitochondrial production of reactive oxygen species. Oestrogen increases the production of mitochondrial proteins encoded by both mitochondrial and nuclear DNA, including cytochrome c, subunits I and IV of complex IV and Mn-superoxide dismutase. Oestrogen treatment increases the activity of citrate synthase and complex IV and decreases mitochondrial production of H(2)O(2). 4. Oestrogen also has potent anti-inflammatory effects in the cerebral circulation that may have important implications for the incidence and severity of cerebrovascular disease. Administration of lipopolysaccharide or interleukin-1beta to ovariectomized female rats induces cerebrovascular COX-2 and inducible nitric oxide synthase (iNOS) protein expression and increases prostaglandin E(2) expression. Levels of COX-2 and iNOS expression vary with the stage of the oestrous cycle, and the cerebrovascular inflammatory response is suppressed in ovariectomized animals treated with oestrogen. Interleukin-1beta induction of COX-2 protein is prevented by treatment with a nuclear factor (NF)-kappaB inhibitor, and oestrogen treatment reduces cerebrovascular NF-kappaB activity. 5. Cerebrovascular dysfunction and pathology contribute to the pathogenesis of stroke, brain trauma, oedema and dementias, such as Alzheimer's disease. A better understanding of the action of oestrogen on cerebrovascular function holds promise for the development of new therapeutic entities that could be useful in preventing or treating a wide variety of cerebrovascular diseases.
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PMID:Cerebrovascular effects of oestrogen: multiplicity of action. 1760 May 62

Peroxynitrite (ONOO-), formed from a reaction of superoxide and nitric oxide, is one of the most potent cytotoxic species known to oxidize cellular constituents including essential proteins, lipids, and DNA. ONOO- induces cellular and tissue injury, resulting in several human diseases such as Alzheimer's disease, atherosclerosis, and stroke. Due to the lack of endogenous enzymes responsible for ONOO- scavenging activity, finding a specific ONOO- scavenger is of considerable importance. In this study, the ability of trypsin inhibitor (TI), isolated from sweet potato storage roots (SPTI), to scavenge *ON and ONOO- was investigated. The data obtained show that TI generated a dose-dependent inhibition on production of nitrite and superoxide radicals. The IC50 value of TI on superoxide radical was 143.2 +/- 4.29 microg/mL. SOD activity staining was used to confirm SOD activity of SPTI. SPTI also caused a dose-dependent inhibition of the oxidation of dihydrorhodamine 123 (DHR) by peroxynitrite. A calculated IC50 value of 809.1 +/- 32.36 microg/mL was obtained on the inhibition of peroxynitrite radical. Spectrophotometric analyses revealed that TI suppressed the formation of ONOO--mediated tyrosine nitration through an electron donation mechanism. In further studies, TI also showed a significant ability to inhibit nitration of bovine serum albumin (BSA) in a dose-dependent manner. In vivo TI inhibited lipopolysaccharide-induced nitrite production in macrophages in a concentration-dependent manner with an IC50 value of 932.8 +/- 29.85 microg/mL. The present study suggested that TI had an efficient reactive nitrogen species scavenging ability. TI might be a potential effective NO and ONOO- scavenger useful for the prevention of NO- and ONOO--involved diseases.
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PMID:Inhibition of reactive nitrogen species in vitro and ex vivo by trypsin inhibitor from sweet potato 'Tainong 57' storage roots. 1760 66

Ischemic stroke induces drastic alterations of the functions of the neurogliovascular unit with dramatic consequences on the well-being of the patients in terms of cognitive and motor handicap. Nowadays, only very few therapeutics are available as a treatment of ischemic stroke. Ischemia is a multifactorial pathology involving different cerebral cellular components such as neurons, astrocytes and vessels working as a functional unit. Recent experimental strategy investigation involving different agents with antioxidant properties (dt-BC, stobadine) or pleiotropic effects (lipopolysaccharide, LPS) has been developed to evaluate whether the vascular wall could be considered as a potential target in neuroprotection concept.
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PMID:Neurogliovascular unit after cerebral ischemia: is the vascular wall a pharmacological target. 1762 44

Nitric oxide produced by the inducible nitric oxide synthase (iNOS) is believed to participate in the pathogenic events after cerebral ischemia. In this study, we examined the expression of iNOS in the brain after transient focal cerebral ischemia in mice. We detected differential expression of exons 2 and 3 of iNOS mRNA (16-fold upregulation at 24 to 72 h after middle cerebral artery occlusion, MCAO) compared with exons 6 to 8, 12 to 14, 21 to 22, and 26 to 27 (2- to 5-fold upregulation after 72 and 96 h), which would be compatible with alternative splicing. Expression levels of iNOS mRNA were too low for detection by the Northern blot analysis. Using specific antibodies, we did not detect any iNOS immunoreactivity in the mouse brain 1 to 5 days after MCAO, although we detected iNOS immunoreactivity in the lungs of mice with stroke-associated pneumonia, and in mouse and rat dura mater after lipopolysaccharide administration. In chimeric iNOS-deficient mice transplanted with wild-type bone marrow (BM) cells expressing the green fluorescent protein (GFP) or in wild-type mice transplanted with GFP(+) iNOS-deficient BM cells, no expression of iNOS was detected in GFP(+) leukocytes invading the ischemic brain or in resident brain cells. Moreover, both experimental groups did not show any differences in infarct size. Analysis of three different strains of iNOS-deficient mice and wild-type controls confirmed that infarct size was independent of iNOS deletion, but strongly confounded by the genetic background of mouse strains. In conclusion, our data suggest that iNOS is not a universal mediator of brain damage after cerebral ischemia.
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PMID:Inducible nitric oxide synthase does not mediate brain damage after transient focal cerebral ischemia in mice. 1785 54

Infection is a risk factor for adult stroke and neonatal encephalopathy. We investigated whether exposure to bacterial endotoxin increases hypoxia-induced brain cell death and impairs cerebral metabolic compensatory responses to hypoxia. Prehatching chicken embryos (incubation day 19) were exposed to bacterial lipopolysaccharide (LPS) (3 mg Salmonella typhimurium LPS per egg) or hypoxia (4% ambient O(2) for 1 h), alone or in combination with LPS, followed 4 h later by hypoxia. Cerebral cell death and glial activation were assessed histologically. Further, chicken embryo brains were studied by magnetic resonance imaging (MRI) and spectroscopy (MRS) to assess haemodynamic and metabolic responses. In most brain areas, combined LPS/hypoxia resulted in a 30- to 100-fold increase in terminal deoxynucleotidyl transferase dUTP nick end labelling -positive cells, compared to control and single-insult groups. Glial activation correlated with the severity of cell death and was significantly greater in the combined-insult group (P<0.05). Hypoxia was associated with a 10-fold increase in lactate/N-acetyl-aspartate (NAA), an approximately 20% increase in total creatine/NAA, rapid decreases in T2 and T2(*), and a reduction in direction-averaged brain-water diffusion (D(av)) by approximately 15%. Liposaccharide pretreatment did not alter the magnitude or timing of these responses, but engendered baseline shifts (increased Cho/NAA, Cr/NAA, and Dav, and reduced T2(*)). In conclusion, LPS greatly increased hypoxia-induced brain damage in this model and induced changes in baseline haemodynamics and metabolism but did not affect the magnitude of the glycolytic response to hypoxia. The damage-enhancing effects of LPS are not because of additional energy depletion but because of a synergistic toxic component.
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PMID:Greater hypoxia-induced cell death in prenatal brain after bacterial-endotoxin pretreatment is not because of enhanced cerebral energy depletion: a chicken embryo model of the intrapartum response to hypoxia and infection. 1803 Mar 3

Neural stem cell (NSC) transplantation has been investigated as a means to reconstitute the damaged brain after stroke. In this study, however, we investigated the effect on acute cerebral and peripheral inflammation after intracerebral haemorrhage (ICH). NSCs (H1 clone) from fetal human brain were injected intravenously (NSCs-iv, 5 million cells) or intracerebrally (NSCs-ic, 1 million cells) at 2 or 24 h after collagenase-induced ICH in a rat model. Only NSCs-iv-2 h resulted in fewer initial neurologic deteriorations and reduced brain oedema formation, inflammatory infiltrations (OX-42, myeloperoxidase) and apoptosis (activated caspase-3, TUNEL) compared to the vehicle-injected control animals. Rat neurosphere-iv-2 h, but not human fibroblast-iv-2 h, also reduced the brain oedema and the initial neurologic deficits. Human NSCs-iv-2 h also attenuated both cerebral and splenic activations of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and nuclear factor-kappa B (NF-kappaB). However, we observed only a few stem cells in brain sections of the NSCs-iv-2 h group; in the main, they were detected in marginal zone of spleens. To investigate whether NSCs interact with spleen to reduce cerebral inflammation, we performed a splenectomy prior to ICH induction, which eliminated the effect of NSCs-iv-2 h transplantation on brain water content and inflammatory infiltrations. NSCs also inhibited in vitro macrophage activations after lipopolysaccharide stimulation in a cell-to-cell contact dependent manner. In summary, early intravenous NSC injection displayed anti-inflammatory functionality that promoted neuroprotection, mainly by interrupting splenic inflammatory responses after ICH.
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PMID:Anti-inflammatory mechanism of intravascular neural stem cell transplantation in haemorrhagic stroke. 1866 89

After an ischemic stroke, neurons in the core are rapidly committed to die, whereas neuron death in the slowly developing penumbra is more amenable to therapeutic intervention. Microglia activation contributes to delayed inflammation, but because neurotoxic mechanisms in the penumbra are not well understood, we developed an in vitro model of microglia activation and propagated neuron killing. To recapitulate inflammatory triggers in the core, microglia were exposed to oxygen glucose-deprived neurons and astrocytes. To model the developing penumbra, the microglia were washed and allowed to interact with healthy naive neurons and astrocytes. We found that oxygen-glucose deprivation (OGD)-stressed neurons released glutamate, which activated microglia through their group II metabotropic glutamate receptors (mGluRs). Microglia activation involved nuclear factor kappaB (NF-kappaB), a transcription factor that promotes their proinflammatory functions. The activated microglia became neurotoxic, killing naive neurons through an apoptotic mechanism that was mediated by tumor necrosis factor-alpha (TNF-alpha), and involved activation of both caspase-8 and caspase-3. In contrast to some earlier models (e.g., microglia activation by lipopolysaccharide), neurotoxicity was not decreased by an inducible nitric oxide synthase (iNOS) inhibitor (S-methylisothiourea) or a peroxynitrite scavenger [5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphinato iron (III) chloride], and did not require p38 mitogen-activated protein kinase (MAPK) activation. The same microglia neurotoxic behavior was evoked without exposure to OGD-stressed neurons, by directly activating microglial group II mGluRs with (2S,2'R,3'R)-2-(2'3'-dicarboxycyclopropyl) glycine or glutamate, which stimulated production of TNF-alpha (not nitric oxide) and mediated TNF-alpha-dependent neurotoxicity through activation of NF-kappaB (not p38 MAPK). Together, these results support potential therapeutic strategies that target microglial group II mGluRs, TNFalpha overproduction, and NF-kappaB activation to reduce neuron death in the ischemic penumbra.
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PMID:Mechanisms of microglia-mediated neurotoxicity in a new model of the stroke penumbra. 1857 26


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