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)

This study examines the generation of superoxide anion by the perfused rat liver after ethanol intoxication and acute endotoxemia to assess the potential importance of oxygen-derived free radicals in the ethanol-induced hepatic pathological condition. Hepatic superoxide anion production of 0.65 +/- 0.06 nmol/min/gm liver weight was measured 1 hr after ethanol infusion; it reached a peak value of 0.8 +/- 0.07 at 3 hr and was reduced to 0.11 +/- 0.01 by 7 hr. In a group of animals, 4-methylpyrazole was injected 5 min before the administration of ethanol to determine whether the metabolism of ethanol moiety is necessary for the observed effects. However, no significant inhibition of superoxide production was observed after 4-methylpyrazole administration. Introduction of ibuprofen into the perfused liver abolished superoxide anion production, suggesting that arachidonic acid metabolites may play an important role in superoxide generation under these conditions. Endotoxin, a potent activator of macrophages, has also been associated with increased superoxide release by the liver. Therefore the combined impact of ethanol and endotoxin on superoxide production by the liver was also examined. Acute ethanol intoxication inhibited the endotoxin-mediated superoxide anion generation by the perfused liver. These data indicate that the ethanol-mediated superoxide production and the ethanol-induced inhibition of the lipopolysaccharide-enhanced free-radical generation by the liver may have a pathophysiological significance in tissue injury and in resistance to infection.
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PMID:Acute ethanol intoxication stimulates superoxide anion production by in situ perfused rat liver. 131 71

Dithiocarbamates and iron chelators were recently considered for the treatment of AIDS and neurodegenerative diseases. In this study, we show that dithiocarbamates and metal chelators can potently block the activation of nuclear factor kappa B (NF-kappa B), a transcription factor involved in human immunodeficiency virus type 1 (HIV-1) expression, signaling, and immediate early gene activation during inflammatory processes. Using cell cultures, the pyrrolidine derivative of dithiocarbamate (PDTC) was investigated in detail. Micromolar amounts of PDTC reversibly suppressed the release of the inhibitory subunit I kappa B from the latent cytoplasmic form of NF-kappa B in cells treated with phorbol ester, interleukin 1, and tumor necrosis factor alpha. Other DNA binding activities and the induction of AP-1 by phorbol ester were not affected. The antioxidant PDTC also blocked the activation of NF-kappa B by bacterial lipopolysaccharide (LPS), suggesting a role of oxygen radicals in the intracellular signaling of LPS. This idea was supported by demonstrating that treatment of pre-B and B cells with LPS induced the production of O2- and H2O2. PDTC prevented specifically the kappa B-dependent transactivation of reporter genes under the control of the HIV-1 long terminal repeat and simian virus 40 enhancer. The results from this study lend further support to the idea that oxygen radicals play an important role in the activation of NF-kappa B and HIV-1.
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PMID:Dithiocarbamates as potent inhibitors of nuclear factor kappa B activation in intact cells. 131 83

Neutrophil (PMN) contributions to the acute inflammatory process and host defense include generation of bioreactive oxygen metabolites and secretion of granule enzymes. We assessed equine PMN secretion using several PMN stimuli, singly and in combination with bacterial lipopolysaccharide (LPS). LPS avidly associated with equine PMN, as shown by strong PMN labeling with FITC-conjugated LPS. LPS alone (1 or 10 micrograms ml-1) was a weak stimulus for PMN superoxide anion (O2-) generation, but preincubation with LPS followed by phorbol ester (PMA, 10 ng ml-1) significantly augmented (P less than 0.01) secretion of O2- (19.38 nmol O2- per 2 x 10(6) PMN per 5 min) over the amount generated by PMA stimulation alone (13.75 nmol O2-). A qualitatively similar, but smaller O2(-)-generation response occurred when either opsonized zymosan or recombinant human C5a was used as the PMN stimulus. Arachidonic acid (ArA; 50-200 microM) was a potent stimulus, with secreted O2- levels similar to those from PMA-stimulated PMN. Preincubation of PMN with either the formyl peptide, fMLP, or platelet-activating factor before stimulation with ArA did not significantly increase O2- generation over levels obtained using ArA alone. Release of PMN granule enzymes was also quantitated. A small amount of lysozyme secretion resulted when PMN were exposed to LPS alone (8.20% of total cell content), and PMA stimulation caused marked release of PMN lysozyme (44.45%). Non-specific proteolytic activity in PMN supernatants, assessed by cleavage of a collagen-rich substrate, was minimal with LPS as a sole stimulus (5.08%). There was significant proteolytic activity (P less than 0.01) in supernatants from PMA-stimulated PMN (27.21%), and preincubation with LPS followed by PMA stimulation slightly enhanced (P less than 0.05) the release of PMN proteases (34.62%). The activities of beta-glucuronidase, acid phosphatase, and alkaline phosphatase were minimal in PMN supernatants when using LPS and PMA as stimuli. The activity of PMN granule enzymes was found to be sensitive to the presence of normal equine serum, and proteolytic activity was markedly reduced (80.13% reduction) in the presence of 10% pooled serum.
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PMID:Secretory activity of equine polymorphonuclear leukocytes: stimulus specificity and priming effects of bacterial lipopolysaccharide. 131 72

Oxygen radicals have been implicated in the pathogenesis of acute lung injury associated with clinical and experimental sepsis. With the use of endotoxin infusion as an in vivo model of sepsis we studied the effect of recombinant-human superoxide dismutase (r-hSOD; 4,200 U/mg), an enzyme that catalyzes the dismutation of superoxide anion, on both the physiologic and biochemical lung changes in awake sheep. Sheep (n = 11) were prepared for chronic measurement of pulmonary hemodynamics and lung fluid balance. Paired experiments were performed in seven of the animals in which they received either endotoxin (1 microgram/kg) alone or in combination with r-hSOD in random order. An additional four sheep received r-hSOD without the lipopolysaccharide. Intravenous infusion of r-hSOD (a loading dose of 12,600 U/kg followed by a maintenance dose of 14,700 U/kg/h for 7 h) resulted in substantial SOD activity, measured by electron spin resonance spectrometry, both in plasma and in lung lymph, and attenuated the expected changes in pulmonary arterial pressure and lung lymph flow after administration of endotoxin. When administered without endotoxin, r-hSOD produced no perceptible change in pulmonary hemodynamics and lung fluid balance. These data suggest that superoxide anion plays an important role in endotoxin-induced lung injury in sheep.
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PMID:Recombinant-human superoxide dismutase attenuates endotoxin-induced lung injury in awake sheep. 131 93

Intravenous lipopolysaccharide, 30 mg/kg, results in rapid systemic hypotension in anesthetized rats. Interaction of lipopolysaccharide with the vascular endothelium and blood borne cells results in the elaboration of cytokines and oxygen-derived free radicals, all of which can be injurious to normal endothelial function. To evaluate endothelial function, superior mesenteric artery rings were isolated from endotoxemic rats just prior to death. Endotoxemia significantly blunted superior mesenteric artery ring vasorelaxations to acetylcholine and to A23187 but not to NaNO2. Contraction of superior mesenteric artery rings from endotoxemic rats induced by U46619 was not altered. Treatment with human superoxide dismutase or U74006F, an aminosteroid, significantly preserved vasorelaxation to acetylcholine and A23187. However, the hydroxyl radical scavenger N-(2-mercaptopropionyl)-glycine did not protect the endothelium. Thus, intravenous lipopolysaccharide can induce endothelial dysfunction in superior mesenteric artery rings. Furthermore, because superoxide dismutase but not N-(2-mercaptopropionyl)-glycine preserves endothelial function, it is likely that superoxide radicals mediate the endothelial dysfunction observed in endotoxemic rats.
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PMID:Splanchnic vascular endothelial dysfunction in rat endotoxemia: role of superoxide radicals. 131 8

Endothelial cells and macrophages are located within the hepatic sinusoids. These two cell types play an important role in the clearance of bacterially derived lipopolysaccharide from the portal circulation. Our laboratory has previously demonstrated that treatment of rats with lipopolysaccharide results in the accumulation of macrophages in the liver that display properties of activated mononuclear phagocytes. This study was designed to analyze the effects of lipopolysaccharide on hepatic endothelial cells. Female Sprague-Dawley rats were treated with 5 mg/kg of lipopolysaccharide. Macrophages and endothelial cells were isolated from the rats 48 hr later by in situ perfusion of the liver with collagenase and pronase followed by differential centrifugation and centrifugal elutriation. We found that lipopolysaccharide treatment of rats resulted in an increase in the number of both macrophages and endothelial cells recovered from the liver. Using specific monoclonal antibodies and flow cytometry, both macrophages and endothelial cells were found to express cell surface markers for Ia antigen, leukocyte common antigen, CD4 and the macrophage antigen, ED2. Macrophages expressed greater levels of these markers than endothelial cells. Flow cytometric analysis also revealed considerable subpopulation heterogeneity in the endothelial cells in antigen expression, physical characteristics and functional activity. Treatment of rats with lipopolysaccharide decreased expression of cell surface markers on the macrophages but not on the endothelial cells. This may be due to the distinct origin of these cells. To determine whether endothelial cells, like macrophages, were activated by lipopolysaccharide, we examined their ability to produce reactive oxygen intermediates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lipopolysaccharide treatment of rats alters antigen expression and oxidative metabolism in hepatic macrophages and endothelial cells. 131 50

To further define the role of Pasteurella haemolytica A1 leukotoxin in the pathogenesis of bovine pneumonic pasteurellosis, its in vitro effects on bovine neutrophils were investigated. Leukotoxin-containing culture supernatant, from P. haemolytica, stimulated a neutrophil respiratory burst as measured by the generation of oxygen-derived free radicals O2- and H2O2. This effect was immediate because preincubation of neutrophils with the culture supernatant for 5 min or longer substantially suppressed this respiratory burst. This suppression was due to cytolysis of the neutrophils. Prolonged incubation of neutrophils with the same culture supernatant caused further cytolysis and degranulation. Heat-inactivated P. haemolytica culture supernatant that had lost its cytotoxic properties failed to stimulate respiratory burst by neutrophils. Furthermore, the respiratory burst, cytolysis and degranulation were abrogated only by leukotoxin-neutralizing monoclonal and polyclonal antibodies, but not by antibodies against the lipopolysaccharide. These studies show that the leukotoxin component in the culture supernatant was responsible for the generation of oxygen-derived free radicals and proteolytic enzymes from neutrophils which may participate in direct lung injury.
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PMID:Effects of Pasteurella haemolytica A1 leukotoxin on bovine neutrophils: degranulation and generation of oxygen-derived free radicals. 132 32

The metabolism and synthesis of cysteinyl leukotrienes by the isolated perfused pig kidney has been investigated. Kidneys were maintained for up to six hours in a recirculating perfusion system by using an oxygenated Krebs-Henseleit buffer containing albumin and the perfluorinated oxygen carrier, FC-43. Perfusion pressure was maintained at 12-13.5 kPa, with perfusion flow rates of 150-250 ml/min resulting in a urine output of between 20-180 ml/hr. Infusion of 3H-LTC4 into the renal artery resulted in rapid and complete metabolism, with the major urinary metabolites comprising LTE4, omega-hydroxy-LTE4, omega-carboxy-LTE4 and N-acetyl-omega-hydroxy-LTE4. The capacity of the isolated kidney to synthesize cysteinyl leukotrienes was monitored by measuring urinary LTE4 excretion; there was a basal urinary excretion of LTE4 (median 43 pg/min, range 8-470 pg/min). Neither lipopolysaccharide or human recombinant tumor necrosis factor alpha had any effect on basal excretion. Treatment with the calcium ionophore A23187, however, resulted in a 38.1 +/- 9.6-fold increase in urinary LTE4 excretion. We conclude that the isolated pig kidney, in the absence of circulating cells, can synthesize cysteinyl leukotrienes in the absence of circulating cells, which can then undergo extensive oxidative metabolism.
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PMID:Synthesis and metabolism of cysteinyl leukotrienes by the isolated pig kidney. 132 26

Corynebacterium parvum-treated mice produce large amounts of circulating nitrogen oxides and develop a severe liver injury in response to lipopolysaccharide (LPS). Concurrent administration of NG-monomethyl-L-arginine not only suppresses nitric oxide synthesis in these animals but also profoundly increases the hepatic damage following LPS. In this report, we present evidence that the increased hepatic damage from inhibition of nitric oxide synthesis is mediated in part by superoxide and hydroxyl radicals. The hepatic damage induced by suppressing nitric oxide production during endotoxemia could be reduced by treating mice with superoxide dismutase and deferoxamine, scavengers of superoxide and hydroxyl radicals, respectively. This damage could also be prevented by treating mice with the anticoagulant heparin sodium. The results suggest that nitric oxide synthesis during endotoxemia is important in preventing hepatic damage by reducing oxygen radical-mediated hepatic injury and preventing intravascular thrombosis.
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PMID:Inhibition of nitric oxide synthesis during endotoxemia promotes intrahepatic thrombosis and an oxygen radical-mediated hepatic injury. 132 40

Macrophages activated by exposure to cytokines and/or to endotoxin produce nitric oxide (NO.), a free radical that is a mediator of the host response to infection. Activation induces the expression of nitric oxide synthase, the enzyme that catalyzes formation of NO. from L-arginine and molecular oxygen. We report the cloning of a cDNA encoding the inducible nitric oxide synthase from a murine macrophage cell line, RAW264.7, exposed to interferon-gamma and lipopolysaccharide. Oocytes injected with mRNA transcribed from this cDNA demonstrate arginine-dependent production of nitrite, a stable metabolite of NO.. Nitric production is blocked by the enzyme inhibitor, NG-monomethylarginine, and is independent of calcium/calmodulin. RAW264.7 cells demonstrate rapid accumulation of the nitric oxide synthase-encoding mRNAs upon activation. Comparison of the deduced amino acid sequence to the calcium/calmodulin-dependent nitric oxide synthase previously purified (Bredt, D. S., and Synder, S.H. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 682-685) and cloned (Bredt, D. S., Hwang, P. M., Glatt, C. E., Lowenstein, C., Reed, R. R., and Synder, S. H. (1991) nature 351, 714-718) from rat brain identifies shared binding sites for the cofactors NADPH and flavins in the C-terminal half of both proteins and an additional conserved region near the N terminus that may recognize L-arginine and/or contribute to the active site.
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PMID:Molecular cloning and functional expression of an inducible nitric oxide synthase from a murine macrophage cell line. 137 7


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