UNIPROT:P43026 - FACTA Search

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Query: UNIPROT:P43026 (lipopolysaccharide)
62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The ability of 2-amino-4-methylpyridine to inhibit the catalytic activity of the inducible NO synthase (NOS II) enzyme was characterized in vitro and in vivo. 2. In vitro, 2-amino-4-methylpyridine inhibited NOS II activity derived from mouse RAW 264.7 cells with an IC50 of 6 nM. Enzyme kinetic studies indicated that inhibition is competitive with respect to arginine. 2-Amino-4-methylpyridine was less potent on human recombinant NOS II (IC50 = 40 nM) and was still less potent on human recombinant NOS I and NOS III (IC50 = 100 nM). NG-monomethyl-L-arginine (L-NMMA), N6-iminoethyl-L-lysine (L-NIL) and aminoguanidine were much weaker inhibitors of murine NOS II than 2-amino-4-methylpyridine but, unlike 2-amino-4-methylpyridine, retained similar activity on human recombinant NOS II. L-NMMA inhibited all three NOS isoforms with similar potency (IC50S 3-7 microM). In contrast, compared to activity on human recombinant NOS III, L-NIL displayed 10 x selectivity for murine NOS II and 11 x selectivity for human recombinant NOS II while aminoguanidine displayed 7.3 x selectivity for murine NOS II and 3.7 x selectivity for human recombinant NOS II. 3. Mouse RAW 264.7 macrophages produced high levels of nitrite when cultured overnight in the presence of lipopolysaccharide (LPS) and interferon-gamma. Addition of 2-amino-4-methylpyridine at the same time as the LPS and IFN-gamma, dose-dependently reduced the levels of nitrite (IC50 = 1.5 microM) without affecting the induction of NOS II protein. Increasing the extracellular concentration of arginine decreased the potency of 2-amino-4-methylpyridine but at concentrations up to 10 microM, 2-amino-4-methylpyridine did not inhibit the uptake of [3H]-arginine into the cell. Addition of 2-amino-4-methylpyridine after the enzyme was induced also dose-dependently inhibited nitrite production. Together, these data suggest that 2-amino-4-methylpyridine reduces cellular production of NO by competitive inhibition of the catalytic activity of NOS II, in agreement with results obtained from in vitro enzyme kinetic studies. 4. When infused i.v. in conscious unrestrained rats, 2-amino-4-methylpyridine inhibited the rise in plasma nitrate produced in response to intraperitoneal injection of LPS (ID50 = 0.009 mg kg-1 min-1). Larger doses of 2-amino-4-methylpyridine were required to raise mean arterial pressure in untreated conscious rats (ED50 = 0.060 mg kg-1 min-1) indicating 6.9 x selectivity for NOS II over NOS III in vivo. Under the same conditions, L-NMMA was nonselective while L-NIL and aminoguanidine displayed 5.2 x and 8.6 x selectivity respectively. All of these compounds caused significant increases in mean arterial pressure at doses above the ID50 for inhibition of NOS II activity in vivo. 5. 2-Amino-4-methylpyridine also inhibited LPS-induced elevation in plasma nitrate after either subcutaneous (ID50 = 0.3 mg kg-1) or oral (ID50 = 20.8 mg kg-1) administration. 6. These data indicate that 2-amino-4-methylpyridine is a potent inhibitor of NOS II activity in vitro and in vivo with a similar degree of isozyme selectivity to that of L-NIL and aminoguanidine in rodents.
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PMID:2-Amino-4-methylpyridine as a potent inhibitor of inducible NO synthase activity in vitro and in vivo. 893 11

Sensitivities to polycationic peptides and EDTA were compared in Yersinia enterocolitica pathogenic and environmental biogroups. As shown by changes in permeability to the fluorescent hydrophobic probe N-phenylnaphthylamine (NPN), the outer membranes (OMs) of pathogenic and environmental strains grown at 26 degrees C in standard broth were more resistant to poly-L-lysine, poly-L-ornithine, melittin, cecropin P1, polymyxin B, and EDTA than Escherichia coli OMs. At 37 degrees C, OMs of pathogenic biogroups were resistant to EDTA and polycations and OMs of environmental strains were resistant to EDTA whereas E. coli OMs were sensitive to both EDTA and polycations. Similar results were found when testing deoxycholate sensitivity after polycation exposure or when isogenic pairs with or without virulence plasmid pYV were compared. With bacteria grown without Ca++ available, OM permeability to NPN was drastically increased in pathogenic but not in environmental strains or E. coli. Under these conditions, OMs of pYV+ and pYV- cells showed small differences in NPN permeability but differences in polycation sensitivity could not be detected by fluorimetry. O:1,6 (environmental type) lipopolysaccharide (LPS), but not O:3 or O:8 LPS, was markedly rough at 37 degrees C, and this could explain the differences in polycation sensitivity. LPSs from serotypes O:3 and O:8 grown at 37 degrees C were more permeable to NPN than O:1,6 LPS, and O:8 LPS was resistant to polycation-induced permeabilization. These data suggest that LPSs relate to some but not all the OM differences described. It is hypothesized that the different OM properties of environmental and pathogenic biogroups reflect the adaptation of the latter biogroups to pathogenicity.
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PMID:Outer membrane differences between pathogenic and environmental Yersinia enterocolitica biogroups probed with hydrophobic permeants and polycationic peptides. 894 23

A 2 x 4 factorial arrangement of treatments was used in a randomized complete block designed study to determine the effects of chromium level and source on growth and immune response of stressed and non-stressed 3-wk-old crossbred weanling pigs (BW was 6.35 kg). Factors included 1) immune stress or control and 2) no supplemental Cr or .2 ppm of supplemental Cr from either CrCl3, Cr-picolinate, or Cr-nicotinic acid complex. The basal diet was a corn-soybean meal-whey diet containing 1.2% lysine. Escherichia coli lipopolysaccharide (LPS) was the stress-inducing agent and was injected on d 7, 10, and 13 of the experiment. Immune challenge with LPS resulted in reduced gain (P < .05) and feed intake (P < .10). Supplementation with Cr was not effective in alleviating the depression in growth due to LPS. However, supplementation of control pigs with Cr tended to improve (P < .10) gain and feed intake. In vitro cellular immune response as measured by a lymphocyte blastogenesis assay was increased (P < .10) in pigs fed supplemental Cr from CrCl3, or Cr-picolinate. Antibody response to sheep red blood cells tended to be increased (P < .10) in pigs supplemented with Cr-nicotinic acid, but antibody response to ovalbumin was decreased (P < .05) in pigs supplemented with organic forms of Cr. At the end of the study, effects of Cr supplementation on lymphocyte proliferative response were investigated before and after ACTH administration. Injections of ACTH resulted in increased (P < .001) serum cortisol levels and increased lymphocyte proliferation. Supplementation of Cr did not affect lymphocyte blastogenic response before or after ACTH injection (P > .10). These data suggest that Cr supplementation was not beneficial during immune stress in pigs.
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PMID:Immune response and growth of stressed weanling pigs fed diets supplemented with organic or inorganic forms of chromium. 905 63

Transglutaminase (TGase) activities were measured in rat tissues 1-7 days after intraperitoneal injection of saline or lipopolysaccharide (LPS) and in the cells and media from pre-confluent human fibroblasts cultured for two days in the presence or absence of LPS. epsilon (gamma-Glutamyl)lysine and [3H]putrescine-labelled gamma-glutamyl derivatives in extracellular and cellular fibroblast proteins were also measured. Three effects of LPS were observed. Firstly, total TGase activity is greater in the tissues from the LPS-injected animals, with the maximum increase occurring at 1 day in dermis, epidermis and liver, at 5 days in the aorta and, after a decrease at 2-5 days, at 7 days in the panniculus muscle. Secondly, the fraction of the total activity which is buffer-extractable is greater on days 1 and/or 2 in all the tissues from the LPS-injected rats. Thirdly, in cultures of human fibroblasts, LPS increases that fraction of bound [3H]putrescine and of TGase and its gamma-glutamylamine products which occurs in the extracellular medium. In addition, a higher concentration of TGase-derived crosslinks was found in extracellular as opposed to intracellular proteins. In conjunction with previous findings in skin wound healing and in atherosclerosis these results support the concept of an extracellular function for tissue TGase and indicate that there is a widespread association of increases in TGase and its extracellular products with inflammation and the healing or fibrotic processes which follow it.
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PMID:Increase in transglutaminase and its extracellular products in response to an inflammatory stimulus by lipopolysaccharide. 908 43

Certain cytokines and lipopolysaccharide stimulate expression of inducible nitric oxide synthase (iNOS) in vascular smooth muscle, an event that is regulated at the transcriptional level and appears to involve several transcription factors, including nuclear factor kappa B (NF-kappa B). Since proteases play an essential role in NF-kappa B activation, experiments were designed to clarify, in both cultured rat aortic smooth muscle cells (SMCs) and isolated rat aortas, whether protease inhibitors affect the interleukin-1 beta (IL-1 beta)-elicited expression of iNOS. The formation of NO was assessed by nitrite release in cultured SMCs and the attenuation of phenylephrine-induced contraction in aortic rings, the expression of iNOS by Western blot analysis and reverse transcription-polymerase chain reaction, and NF-kappa B activity in nuclear extracts by gel electrophoretic mobility shift assya. Exposure of cultured SMCs to IL-1 beta increased NF-kappa B binding activity within 30 minutes and was associated with nitrite accumulation and the appearance of iNOS protein 24 hours later. These responses were abolished in cells that had been exposed to the cytokine in the presence of the protease inhibitor N-alpha-tosyl-L-lysine chloromethylketone. Aprotinin and p-toluenesulfonyl-L-arginine methyl ester, two other protease inhibitors, also reduced the cytokine-stimulated release of nitrite and the level of iNOS protein. Exposure of rat aortic segments without endothelium to IL-1 beta activated NF-kappa B within 30 minutes and was associated with the appearance of iNOS mRNA and an attenuation of phenylephrine-induced contraction 6 hours later. These responses were blunted when the segments were incubated with the cytokine and N-alpha-tosyl-L-lysine chloromethyl ketone. The present observations indicate that protease inhibitors prevent iNOS expression in both cultured and native vascular SMCs by blocking the activation of NF-kappa B.
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PMID:N-alpha-tosyl-L-lysine chloromethylketone prevents expression of iNOS in vascular smooth muscle by blocking activation of NF-kappa B. 910 79

Sugar analysis and 1H- and 13C-NMR spectroscopic studies showed that various strains of Proteus mirabilis OXK used as antigens in the Weil-Felix test for serodiagnosis of rickettsiosis (scrub typhus) produce lipopolysaccharides (LPSs) with the same O-specific polysaccharide chain having the following structure: [formula: see text] where GlcA and GalA are glucuronic and galacturonic acids, respectively. This polysaccharide which defines the O3 specificity of Proteus and has been found earlier in an unclassified P. mirabilis strain S1959, contains an amide of D-galacturonic acid with L-lysine which plays an important role in manifesting the immunospecificity. A cross-reaction was observed in ELISA between sera from patients with scrub typhus, caused by the bacterium Orientia (Rickettsia) tsutsugamushi, and purified LPS of P. mirabilis OXK, thus suggesting that the common epitope involved in the Weil-Felix test is located on P. mirabilis OXK LPS. Rabbit anti-P. mirabilis OXK antibodies did not cross-react with LPS-lacking O. tsutsugamushi strain Gilliam in dot-blotting and Western blotting, and the nature of the rickettsial antigen responsible for the Weil-Felix reaction remains unknown.
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PMID:Structural and serological studies of the O-antigen of the bacterium Proteus mirabilis OXK (serogroup O3) used in the Weil-Felix test. 911 25

The murine macrophage cell line RAW 264.7 expresses inducible nitric-oxide synthase (iNOS) activity upon stimulation with interferon (IFN)-gamma and/or bacterial lipopolysaccharide. We have studied the mechanisms by which the synthetic glucocorticoid dexamethasone suppresses IFN-gamma-stimulated iNOS expression in RAW 264.7 cells. Treatment of cells with dexamethasone reduces the formation of nitrite, one of the stable end products of NO production measured in culture supernatants with an IC50 of 9 nM. The reduction of iNOS activity is caused by decreased iNOS protein levels as assessed by immunoblotting using a specific anti-iNOS antibody. Dexamethasone treatment also reduces the formation of iNOS mRNA steady state levels to about 50% in IFN-gamma-stimulated cells. This is due to decreased iNOS gene transcription and iNOS mRNA stability. More importantly, dexamethasone reduces the amount of iNOS protein by two additional mechanisms: reduction of the translation of iNOS mRNA and increased degradation of the iNOS protein. Using a specific protease inhibitor for the cysteine protease calpain I, N-acetyl-Leu-Leu-norleucinal (calpain inhibitor I), the enhanced proteolysis of the iNOS protein can efficiently be blocked, whereas other protease inhibitors such as tosyl-L-lysine chloromethyl ketone have no effect. Dexamethasone does not significantly alter calpain gene expression. Northern blot analyses reveal that calpain mRNA steady state levels are virtually not affected upon incubation of the cells with IFN-gamma and dexamethasone. Immunoprecipitation using a polyclonal anti-calpain antibody reveals that calpain protein levels are also not affected by the glucocorticoid. This is the first evidence that the iNOS protein is a molecular target for the cysteine protease calpain.
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PMID:Mechanisms of suppression of inducible nitric-oxide synthase (iNOS) expression in interferon (IFN)-gamma-stimulated RAW 264.7 cells by dexamethasone. Evidence for glucocorticoid-induced degradation of iNOS protein by calpain as a key step in post-transcriptional regulation. 919 84

Excess NO generation plays a major role in the hypotension and systemic vasodilatation characteristic of sepsis. Yet the kidney response to sepsis is characterized by vasoconstriction resulting in renal dysfunction. We have examined the roles of inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) on the renal effects of lipopolysaccharide administration by comparing the effects of specific iNOS inhibition, -N6-(1-iminoethyl)lysine (L-NIL), and 2,4-diamino6-hydroxy-pyrimidine vs. nonspecific NOS inhibitors (nitro- -arginine-methylester). cGMP responses to carbamylcholine (CCh) (stimulated, basal) and sodium nitroprusside in isolated glomeruli were used as indices of eNOS and guanylate cyclase (GC) activity, respectively. LPS significantly decreased blood pressure and GFR (112+/-4 vs. 83+/-4 mmHg; 2.66+/-0.29 vs. 0. 96+/-0.22 ml/min, P < 0.05) and inhibited the cGMP response to CCh. GC activity was reciprocally increased. L-NIL and 2, 4-diamino-6-hydroxy-pyrimidine administration prevented the decrease in GFR (2.71+/-0.28 and 3.16+/-0.18 ml/min, respectively), restored the normal response to CCh, and GC activity was normalized. In vitro application of L-NIL also restored CCh responses in LPS glomeruli. Neuronal NOS inhibitors verified that CCh responses reflected eNOS activity. L-NAME, a nonspecific inhibitor, worsened GFR (0.41+/-0.15 ml/min), a reduction that was functional and not related to glomerular thrombosis, and eliminated the CCh response. No differences were observed in eNOS mRNA expression among the experimental groups. Selective iNOS inhibition prevents reductions in GFR, whereas nonselective inhibition of NOS further decreases GFR. These findings suggest that the decrease in GFR after LPS is due to local inhibition of eNOS by iNOS, possibly via NO autoinhibition.
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PMID:Inhibition of constitutive nitric oxide synthase (NOS) by nitric oxide generated by inducible NOS after lipopolysaccharide administration provokes renal dysfunction in rats. 921 22

Osteopontin is a secreted phosphoprotein that is expressed in the normal kidney and induced during various pathologic conditions associated with tubulointerstitial injury. However, the exact cellular location of osteopontin in the kidney has been a matter of controversy, and little is known about the role of osteopontin in the kidney. The purpose of this study was to establish the cellular and intracellular distribution of osteopontin in the rat kidney under normal conditions and after injection of a bacterial endotoxin lipopolysaccharide (LPS). Animals received injections of LPS or vehicle at different time intervals from 4 to 20 h before sacrifice. Kidneys were preserved by in vivo perfusion with paraformaldehyde-lysine-periodate (PLP) and processed for light and electron microscope immunocytochemistry using monoclonal antibodies to rat osteopontin. By light microscopy, immunostaining was observed in the descending thin limb and the papillary surface epithelium of both control and LPS-treated animals. After injection of LPS, osteopontin immunostaining was observed throughout the distal nephron and was also present in segments of the proximal tubule, where it was distributed in a punctate pattern. Staining was already present 4 h after injection of LPS and was maximal 6 h after injection. Electron microscopy revealed that osteopontin immunoreactivity in the descending thin limb and distal tubule cells was located in the Golgi apparatus and in small cytoplasmic vesicles, whereas in the proximal tubule labeling was observed in the vacuolar-lysosomal system. Western blot analysis demonstrated a band at approximately 70 kD and confirmed the increase in osteopontin expression after administration of LPS. These results demonstrate that osteopontin is constitutively expressed in cells of the descending thin limb and papillary surface epithelium and is induced throughout the distal tubule after administration of LPS.
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PMID:Ultrastructural localization of osteopontin in the kidney: induction by lipopolysaccharide. 921 53

We report here evaluation of a competitive enzyme-linked immunosorbent assay (c-ELISA) for detection of Salmonella spp. in chicken organs and faeces. The c-ELISA used a monoclonal antibody (MAb), specific for a genus-specific epitope of the outer core oligosaccharide of salmonellae. Salmonella lipopolysaccharide (LPS) in samples competed with Salmonella LPS coated on microtitre plates, for binding to the MAb. Competition reduced binding of the MAb to the LPS on the plate and of the secondary antibody to the MAb hence reducing the chromogenic signal. Stable coating and minimal false positive were achieved by conjugating LPS to poly-L-lysine. The c-ELISA was compared with motility enrichment culture using modified semisolid Rappaport Vassiliadis (MSRV) medium, which detected less than 10(2) CFU/g, and did not allow migration of non-salmonella species. The c-ELISA detected 10(6) CFU of enriched culture or 10(2)-10(3) CFU of Salmonella/g of faeces. Its limit of detection was thus higher than that of MSRV culture and it had a sensitivity of 92.9% and a specificity of 96.7%.
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PMID:Comparison of an LPS-specific competitive ELISA with a motility enrichment culture method (MSRV) for detection of Salmonella typhimurium and S. enteritidis in chickens. 922 84

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