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)

Ischemia-reperfusion (IR) lung injury occurs after various clinical procedures, including cardiopulmonary bypass. It is not clear whether endogenous nitric oxide (NO) is protective or injurious in lungs subjected to IR. Thus, in this study we examined the contribution of endogenous NO to IR injury in isolated, blood-perfused rat lungs. Lungs of male Wistar rats (300 g) were subjected to 30 min ischemia and 180 min reperfusion (I30R180). Lungs were sampled for inducible nitric oxide synthase (i-NOS) mRNA expression (each n = 3) and NOS enzyme activity (each n = 4) at different time points. NOS inhibitors NG-nitro-L-arginine-methyl ester (10[-4] M) and aminoguanidine (10[-4] M) were used to study the contribution of NO to IR injury in lungs subjected to I30R30 and I30R180. The contribution of i-NOS to IR lung injury was studied by inducing i-NOS enzyme with Salmonella lipopolysaccharide, followed by I30R30. We found that ischemia-reperfusion alone can upregulate i-NOS mRNA and i-NOS enzyme activity (p < 0.05, ANOVA), but downregulate constitutive NOS enzyme activity over 180 min reperfusion. Endogenously produced NO is protective against lung injury in I30R180 in normal rats and lung injury in I30R30 in septic rats. NO is also pivotal in maintaining pulmonary vascular homeostasis in septic rat lungs undergoing IR.
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PMID:The role of endogenous nitric oxide in modulating ischemia-reperfusion injury in the isolated, blood-perfused rat lung. 944 9

The purpose of this experimental study was to investigate whether enteral nutrition-induced postprandial intestinal hyperemia has a beneficial effect on the splanchnic ischemia due to sepsis. Fourteen dogs, after exposure to Escherichia coli endotoxin via portal vein administration were grouped according to whether they were fed enterally via a jejunostomy or given a placebo. Systemic hemodynamics; portal vein, hepatic, and superior mesenteric artery blood flow; hepatic and intestinal microcirculation; hepatic tissue PO2; intestinal pHi; and hepatic energy charge were assessed before, during, and after endotoxin infusion as well as during and after enteral or placebo feeding. All splanchnic hemodynamic parameters revealed a statistically significant decline (p = 0.001) during the endotoxin shock period relative to the baseline. After enteral feeding all parameters exhibited a statistically significant increase (p = 0.001) relative to the placebo group. The results of this study led us to suggest that enteral nutrition reverses the lipopolysaccharide infusion-induced splanchnic ischemia.
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PMID:Influence of enteral nutrition-induced splanchnic hyperemia on the septic origin of splanchnic ischemia. 946 54

Ischaemia in wounds may modulate the expression of tumour necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The release of these and other cytokines by stimulated macrophages influences wound healing. Our aim was to examine the separate and combined effects of hypoxia and glucose deprivation on TNF-alpha and GM-CSF mRNA levels in human monocytes isolated from peripheral blood by density gradient centrifugation and purified by adherence. Cells were incubated for a 16-hour period in a hypoxic (3% O2) or normoxic (21% O2) environment in the presence or absence of glucose followed by a further 4 h under normoxic conditions in the presence or absence of lipopolysaccharide (LPS, 100 pg/ml). These different incubation conditions had no effect on cell viability, cell number, lactate dehydrogenase release or superoxide anion generation (n = 5, p > 0.05, paired t test). However, Northern hybridisation showed that hypoxia decreased the expression of GM-CSF mRNA in LPS-stimulated human monocytes by 46% (n = 9, p < 0.05, paired t test) and increased the expression of TNF-alpha by 102% (n = 7, p < 0.05, paired t test). The increase in the level of immunoreactive TNF-alpha in the cell supernatants paralleled the increase in TNF-alpha mRNA. The combination of glucose deprivation and hypoxia decreased the expression of both GM-CSF and TNF-alpha mRNA in LPS-stimulated human monocytes. Similarly, a decrease in the level of TNF-alpha in the cell supernatants was observed (n = 3-5, p < 0.05, two-way ANOVA). These data suggest that incubation conditions simulating ischaemia reduce LPS-induced cytokine expression.
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PMID:Influence of hypoxia and glucose deprivation on tumour necrosis factor-alpha and granulocyte-macrophage colony-stimulating factor expression in human cultured monocytes. 954 21

Septic shock is an increasingly important clinical condition, characterized by systemic hypotension, ischemia, and ultimately organ failure. In Gram negative infection, the bacterial cell wall component, lipopolysaccharide (endotoxin, LPS), has been strongly linked to the pathophysiological responses that result in septic shock. LPS is bound in plasma to a protein called LPS-binding protein (LBP), which facilitates the binding of LPS to a cell surface receptor, CD14. Binding to CD14 stimulates cell signaling mechanisms that result in the production of inflammatory cytokines. However, the events which follow LPS binding to CD14 and which lead to the production of cytokines remain unclear. It has recently become evident that a number of phosphorylation cascades including MAP kinase pathways and NF-kappaB activation pathway are initiated by exposure of cells to LPS. These cascades act at both the transcriptional and translational levels to regulate cytokine production. This review will focus on the signaling pathways that are initiated by LPS and the cellular effects of the signaling pathways.
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PMID:Cellular activation mechanisms in septic shock. 956 Mar 58

Brain prostanoid levels are normally low but can increase after ischemia and during inflammatory and infectious diseases. High prostanoid levels can affect brain function in several ways. In particular, prostaglandin E2 (PGE2) might exert both immunodepressive and proinflammatory actions. The present short review focuses on the regulation of prostanoid synthesis in microglial cultures and on the possible role of PGE2 in the down-regulation of microglial activation induced by lipopolysaccharide (LPS). Our studies were carried out using purified mouse or rat microglial cultures. LPS induced a dose-dependent expression of the inducible isoform of cyclooxygenase (COX-2), both in neonatal and adult microglial cultures. In the latter, the inducibility of COX-2 increased with time in culture, paralleling the acquisition of a more 'activated' microglial phenotype, and appeared to account for the time-dependent increase in the PGE2/TXB2 production ratio. The LPS-induced COX-2 expression and prostanoid production were down-regulated by potentially neurotoxic agents, such as nitric oxide (NO), the proinflammatory cytokine IFN-gamma (which acted both directly and indirectly, through its NO-inducing activity) and the HIV regulatory protein tat. On the other hand, COX-2 expression was up-regulated by the macrophage-deactivating cytokine TGF-beta 1, by exogenous PGE2 itself, which acted through EP2 receptors linked to cyclic AMP generation, and by non steroidal anti-inflammatory drugs. Interestingly, PGE2 utilized the same EP2 receptor-mediated signal transduction mechanism to down-regulate the expression of the inducible NO synthase and the production of NO. Largely, but not exclusively, through its effect on cyclic AMP, PGE2 can also: i) depress the expression of major histocompatibility complex class II antigens and of the costimulatory molecule B7-2; ii) down-regulate TNF and up-regulate IL-10 microglial production; iii) inhibit microglial IL-12 secretion. These observations, together with literature data on in vivo models of central nervous system (CNS) diseases, suggest a neuroprotective role of PGE2 in pathological conditions.
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PMID:Regulation of prostanoid synthesis in microglial cells and effects of prostaglandin E2 on microglial functions. 989 49

The importance of melanocortin peptides to host responses was recognized with the observation of the antipyretic effect of centrally administered alpha-melanocyte stimulating hormone (alpha-MSH). It is now clear that this neuropeptide also exerts remarkable antiinflammatory activity via direct actions on peripheral host cells, descending neurogenic antiinflammatory pathways stemming from CNS melanocortin receptors, and local actions on receptors that control inflammation within the brain. Recent studies of the latter influence indicate that alpha-MSH inhibits brain tumor necrosis factor-alpha (TNF-alpha), previously linked to human neurodegenerative diseases, induced by local injection of lipopolysaccharide. Ischemia/reperfusion of the brain, a model of stroke, induces inflammation marked by disturbance of CNS function. alpha-MSH given systemically modulates disturbances of auditory evoked potentials induced by ischemia/reperfusion in the posterior circulation. Such influences of the peptide may occur through inhibition of inflammatory agents produced by glia: alpha-MSH 1-13 and 11-13 modulate TNF-alpha and nitric oxide produced by activated murine microglia, and TNF-alpha produced by human astrocytes. Because glia can secrete alpha-MSH and express melanocortin receptors, they may, like peripheral macrophages, contain autocrine regulatory circuits based on the peptide. alpha-MSH thus modulates both fever and inflammation in the brain by acting on local melanocortin receptors.
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PMID:Peptide modulation of fever and inflammation within the brain. 991 65

Melatonin, the chief secretory product of the pineal gland, is a direct free radical scavenger and indirect antioxidant. In terms of its scavenging activity, melatonin has been shown to quench the hydroxyl radical, superoxide anion radical, singlet oxygen, peroxyl radical, and the peroxynitrite anion. Additionally, melatonin's antioxidant actions probably derive from its stimulatory effect on superoxide dismutase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase and its inhibitory action on nitric oxide synthase. Finally, melatonin acts to stabilize cell membranes, thereby making them more resistant to oxidative attack. Melatonin is devoid of prooxidant actions. In models of oxidative stress, melatonin has been shown to resist lipid peroxidation induced by paraquat, lipopolysaccharide, ischemia-reperfusion, L-cysteine, potassium cyanide, cadmium chloride, glutathione depletion, alloxan, and alcohol ingestion. Likewise, free radical damage to DNA induced by ionizing radiation, the chemical carcinogen safrole, lipopolysaccharide, and kainic acid are inhibited by melatonin. These findings illustrate that melatonin, due to its high lipid solubility and modest aqueous solubility, is able to protect macromolecules in all parts of the cell from oxidative damage. Melatonin also prevents the inhibitory action of ruthenium red at the level of the mitochondria, thereby promoting ATP production. In humans, the total antioxidative capacity of serum is related to melatonin levels. Thus, the reduction in melatonin with age may be a factor in increased oxidative damage in the elderly.
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PMID:Reactive oxygen intermediates, molecular damage, and aging. Relation to melatonin. 992 48

Products of enteric bacteria, including endotoxin [lipopolysaccharide (LPS)], have been implicated in the acute inflammatory responses elicited by ischemia and reperfusion (I/R) of the small intestine. The objective of this study was to assess the contribution of LPS to the increased E-selectin expression observed in the intestinal vasculature after I/R. The dual radiolabeled monoclonal antibody technique was used in LPS-sensitive (C3HeB/FeJ) and LPS-insensitive (C3H/HeJ) mice that were exposed to either exogenous LPS or to gut I/R (45 min ischemia, 5 h reperfusion). LPS elicited a dose-dependent (0.5-50 microgram LPS/animal) increase in E-selectin expression (at 3 h) in LPS-sensitive mice, whereas LPS-insensitive mice were largely unresponsive. E-selectin expression was increased fivefold by I/R in the small bowel of both LPS-sensitive and -insensitive mice. These results indicate that, although exogenous LPS is capable of eliciting profound dose-dependent increases in E-selectin expression, endogenous LPS does not contribute significantly to I/R-induced expression of this endothelial cell adhesion molecule.
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PMID:Role of endotoxin in intestinal reperfusion-induced expression of E-selectin. 995 Aug 22

The aim of this study was to investigate the distribution pattern of Ca2+- and Mg2+-dependent ecto-ATPases on the surface of rat brain capillary endothelial cells (ECs) in control and lipopolysaccharide (LPS)-treated animals. Ecto-ATPases in the membrane of vascular endothelial cells are suggested to play a crucial role in thromboregulation. Loss of this enzyme activity after oxidative stress and upregulation of the enzyme chain hydrolyzing extracellular ATP after transient forebrain ischemia have also been reported. We used histochemistry to localize the activities of this enzyme on ECs and found pH- and cation-dependent changes in the localization of enzyme activity both in control and in LPS-treated animals. These findings suggest the presence of more than one ecto-ATPase enzyme on the surface of rat capillary ECs. The different behavior of ECs after LPS treatment is the target of further investigations. The increased ecto-nucleotidase activity might play a role in nucleotide-mediated cellular responses after bacterial infections.
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PMID:Lipopolysaccharide treatment modifies pH- and cation-dependent ecto-ATPase activity of endothelial cells. 1002 41

Previous studies have proposed that endogenous antioxidants play a protective role against cardiac ischemia-reperfusion injury in endotoxin pretreatment. However, the mechanism underlying this effect remains elusive. We therefore evaluated the role of endogenous antioxidants in delayed myocardial protection after different doses of endotoxin administration using cultured rat neonatal cardiomyocytes. Myocytes were treated with normal saline (control) or lipopolysaccharide (Escherichia coli, serotype O111) at doses of 40 and 80 microg/ml (ET40 and ET80). Also, antisense oligodeoxyribonucleotide (1.5 micromol/L) to manganese superoxide dismutase (Mn-SOD) and 3-amino-1,2,4-triazole (25 mg/ml) were added along with a 40 or 80 microg/ml endotoxin pretreatment in the IET40 and IET80 groups. Twenty-four hours later, Cells were subjected to hypoxia (pO2 < 1 kPa, 3 h) and reoxygenation (pO2: 19 kPa, 1 h). Compared with controls, cell viability enhanced significantly (65.3 +/- 5.9, 63.8 +/- 4.6, and 69.7 +/- 5.2% vs 47.2 +/- 4.3%, P < 0.05) and creatine kinase release decreased (7.34 +/- 1.76, 7.11 +/- 1.49, and 6.27 +/- 1.24 U/mg protein vs 11.23 +/- 2.49 U/mg protein, P < 0. 05) in ET40, IET40, and ET80 groups following reoxygenation. No statistically significant difference was found between the control and the IET80 groups. Furthermore, the levels of Mn-SOD (1.12 +/- 0. 31 vs 0.75 +/- 0.15 U/mg. protein, P < 0.05) and catalase activity (1265 +/- 109 vs 996 +/- 85 U/mg. protein, P < 0.05) were higher only in the ET80 group. The results suggest that at a dose of 40 microg/ml, cells were protected by mechanisms other than the augmentation of endogenous antioxidant activity which were more evident at a dose of 80 microg/ml. It seems that different doses of endotoxin pretreatment may induce delayed myocardial protection through various mechanisms.
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PMID:Different role of antioxidants in endotoxin-induced late myocardial protection. 1009 Aug 28


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