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

Outer membrane proteins were derived from one rough and four smooth strains of Brucella abortus by sequential extraction of physically disrupted cells with N-lauroylsarcosinate and dipolar ionic detergent. Extraction of outer membrane proteins was ineffective, however, without predigestion with lysozyme. Three groups of proteins were present and could be separated in their native state by sequential anion-exchange chromatography and gel filtration. Membrane proteins contained substantial quantities of tightly adherent lipopolysaccharide which could be reduced but not eliminated by extraction of cells with trichloroacetic acid before disruption. Group 2 proteins, apparently trimers in their native state, gave rise to 43,000- and 41,000-molecular-weight bands after complete denaturation in sodium dodecyl sulfate. They were antigenically identical among all the strains, showed close resemblance in amino acid composition to each other and a general similarity to OmpF of Escherichia coli, and are proposed to be the porins of B. abortus. Group 3 proteins occurred as 30,000-molecular-weight bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, although additional bands were frequently observed in this region. In none of the strains did group 3 proteins manifest heat-modifiable characteristics. Proteins of different strains bore a high degree of similarity to each other in amino acid composition, except in methionine, isoleucine, tyrosine, and histidine. Differences occurred consistently in amino acid composition between group 2 and 3 proteins, and some of these correspond to differences between OmpF and OmpA. Group 2 and 3 proteins were antigenically distinct from each other, but the principal group 3 antigens were shared among all the strains. Despite the lack of heat modifiability, perhaps influenced by adherent lipopolysaccharide, group 3 proteins are proposed as counterparts to OmpA. Most of the group 1 proteins, minor components, were physically associated with those of group 3 unless in sodium dodecyl sulfate. Group 1 proteins produced a major band at 94,000 and exhibited heat modifiability. No evidence was found of a low-molecular-weight lipoprotein in the outer membrane of B. abortus, but this is not taken to exclude its occurrence.
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PMID:Outer membrane proteins of Brucella abortus: isolation and characterization. 680 64

Biochemical measures have provided insight into the biomass and community structure of sedimentary microbiota without the requirement of selection by growth or quantitative removal from the sediment grains. This study used the assay of the hydroxy fatty acids released from the lipid A of the lipopolysaccharide in sediments to provide an estimate of the gram-negative bacteria. The method was sensitive to picomolar amounts of hydroxy fatty acids. The recovery of lipopolysaccharide hydroxy fatty acids from organisms added to sediments was quantitative. The lipids were extracted from the sediments with single-phase chloroform-methanol extraction. The lipid-extraction residue was hydrolyzed in 1 N HCl, and the hydroxy fatty acids of the lipopolysaccharide were recovered in chloroform for analysis by gas-liquid chromatography. This method proved to be about fivefold more sensitive than the classical phenol-water or trichloroacetic acid methods when applied to marine sediments. By examination of the patterns of hydroxy fatty acids, it was also possible to help define the community structure of the sedimentary gram-negative bacteria.
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PMID:Sensitive assay, based on hydroxy fatty acids from lipopolysaccharide lipid A, for Gram-negative bacteria in sediments. 681 12

Microglia are the only immunocompetent cells resident in the central nervous system which are capable of protecting the brain from infection and tumors. These resident macrophages possess a vast array of mechanisms for the destruction of bacteria and tumor cells. One of these mechanisms involves the generation of nitric oxide which can kill cells by inhibition of glycolysis, the TCA cycle and DNA synthesis. In this regard, we demonstrate, for the first time, that the inducible form of nitric oxide synthase (NOS) in microglia involves both cytosolic and membrane bound pools. Both pools of NOS were potently and stereo-specifically inhibited by NOS inhibitors. In addition, while these pools were unaffected by Ca2+, they were partially inhibited by calmodulin antagonists. These data would suggest that inducible NOS in lipopolysaccharide (LPS) treated microglia, constitutes two major compartments and may involve a novel isoform which is membrane associated. With regard to the possible physiological relevance for the membrane-bound NOS, we speculate that this presents an efficient means of supplying nitric oxide to the extracellular environment where it could gain rapid access to tumors and bacteria. This would result in inhibition of cellular function in these invading cells while limiting access of nitric oxide to the intracellular environment of microglia where NO could lead to depressed microglial function.
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PMID:Inducible microglial nitric oxide synthase: a large membrane pool. 752 Mar

The effect of staphylococcal enterotoxin B (SEB)-elicited inducible nitric oxide synthase (iNOS) in mouse endothelial cells was investigated. Results showed that SEB stimulated the same level of NO production in gamma interferon (IFN-gamma)-primed cells as did trichloroacetic acid-extracted lipopolysaccharide. The kinetics of induced NO production and expression of mRNA for iNOS differed markedly in endothelial and macrophage cells. Induced endothelial nitrite production was transient and was 15 to 20% of that generated by macrophage cells; mRNA levels peaked by 2 h and then steadily declined, whereas macrophage message levels continually increased. The ability of endothelial cells to produce SEB-induced NO depended on priming with IFN-gamma, although detectable mRNA could be elicited by SEB alone. Induction of endothelial iNOS mRNA was inhibited by cycloheximide, which indicated a requirement for de novo protein synthesis. Niacinamide and interleukin-10 significantly reduced SEB-induced endothelial NO production. Both are reported to affect IFN-gamma-induced class II major histocompatibility complex (MHC) expression on antigen-presenting cells. Niacinamide reduced iNOS mRNA levels and markedly reduced IFN-gamma induction of endothelial class II MHC surface antigen. Interleukin-10 did not consistently reduce iNOS mRNA expression and had no effect on IFN-gamma induction of endothelial class II MHC surface antigen. These results suggest that SEB interacts with IFN-gamma-primed endothelial cells to elicit induced NO and that this induction can be effectively modulated at the receptor or transcriptional level.
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PMID:Regulation of staphylococcal enterotoxin B-elicited nitric oxide production by endothelial cells. 752 48

In rats treated i.v. with heat-killed Propionibacterium acnes (100 mg/kg body wt), followed 5 days later by an i.v. dose of Escherichia coli lipopolysaccharide (LPS, 1 mg/kg body wt), acute hepatic cell necrosis was accompanied by significant induction of nitric oxide (NO) synthase activity in the liver. Endogenous nitrosation of thiazolidine 4-carboxylic acid (TCA, 50 mumol/rat) administered by three different routes (i.v., i.p. and p.o.) 5 h after LPS injection to the P. acnes-treated rats was assessed by analysing its nitrosated product (NTCA) excreted in 24 h urine. The amounts of NTCA formed in vivo after i.v., i.p. and p.o. administration of TCA were 4.07 +/- 1.00, 5.79 +/- 2.15 and 58.3 +/- 20.7 nmol/rat (n = 5-10) respectively, which were about 5-, 10- and 8-fold greater than those excreted by rats which had not been treated with P.acnes and LPS but received TCA by the same route. Nitrate concentration in plasma and NO synthase activity in the liver started to increase within 2.5 h after LPS injection, reached a maximum at 7.5 h and remained at high levels for several further hours. Levels of nitrite and nitrate in gastric contents were also increased significantly after LPS administration. The co-administration of N omega-nitro-L-arginine (an inhibitor of NO synthase) and LPS resulted in a marked reduction of urinary levels of nitrate and NTCA, indicating that nitrosation is mediated by NO synthase. These results together suggest that induction of NO synthase by infection with bacteria, parasite and viruses could result in increased endogenous nitrosation not only in the infected tissues but also in the stomach, where nitrosamines would be formed more rapidly under acidic conditions.
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PMID:Increased endogenous N-nitrosamine and nitrate formation by induction of nitric oxide synthase in rats with acute hepatic injury caused by Propionibacterium acnes and lipopolysaccharide administration. 767 86

A naturally occurring hemagglutinin was detected in the serum of the hermit crab Diogenes affinis, and its erythrocyte (RBC) binding activities, physicochemical properties, and carbohydrate binding specificity were characterized. Both the hemagglutination profile and the pattern of cross-reactivity of the serum with different RBC types in cross-adsorption tests suggested a strong affinity of the serum agglutinin for rat RBC. Further analysis revealed that the agglutinin was specifically dependent on Ca2+ for its hemagglutinating activity and reversibly sensitive to EDTA. The activity was found to be stable between pH 6.0 and 7.5, heat-labile, and completely precipitable by ammonium sulphate or TCA, suggesting the proteinaceous nature of the serum agglutinin. In hemagglutination-inhibition assays, the serum agglutinin of D. affinis showed a distinct and unique specificity for acetyl group-containing carbohydrates and glycoprotein. Furthermore, the hemagglutinating activity of the serum agglutinin was also inhibited by lipopolysaccharide from Salmonella abortus equi, which might indicate a significant role of humoral agglutinin in the immune response of crustaceans against bacterial infection.
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PMID:A lipopolysaccharide-binding hemagglutinin with specificity for acetylated aminosugars in the serum of the hermit crab Diogenes affinis (Henderson). 780 93

A new simple, reproducible and sensitive ELISA that uses trichloroacetic acid (TCA) for the coating of lipooligosaccharide (LOS), smooth lipopolysaccharide (LPS) or lipid A to the solid phase has been developed. The experimental parameters (temperature of coating, time of coating, antigen concentration and TCA concentration) were evaluated by a complete factorial design (2(4)). As a result of the evaluation, two main coating procedures were developed. In one, LOS was shown to coat efficiently in 0.2% TCA, at 37 degrees C, when incubated for only 30 min. In the other procedure, LOS in 0.2% TCA was coated at 37 degrees C for 16 h. The slower procedure proved, as expected, to be even more efficient than the former. The new ELISA was compared to three previously reported ELISAs, and showed the greatest sensitivity, probably, as a consequence of the higher coating efficiency of LOS to plates. The biologic activity of LOS was not modified by the low TCA concentration used, as proven by retention of its biological activity in the induction of procoagulant activity in blood mononuclear cells. We conclude that small amounts of biologically active LOS/LPS or lipid A can be coated on solid surfaces by this approach to achieve a rapid and economical assay procedure.
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PMID:Enhanced ELISA sensitivity using TCA for efficient coating of biologically active lipopolysaccharides or lipid A to the solid phase. 796 89

Five representative, taxonomically and serologically defined clinical isolates of Acinetobacter baumannii and genospecies 3, and A. baumannii strain ATCC 19606 were examined for immunogenicity in rabbits following experimental bacteremia. All rabbits seroconverted as determined with the aid of the tube O-agglutination, indirect hemagglutination, and enzyme-linked immunosorbent assay (ELISA) procedures. Immunoblots detected over twenty immunogenic, proteinase-K-degradable polypeptide antigens in trichloroacetic acid extracts, outer membrane protein fractions, and mechanically disrupted (type MM2 mixer drill) cell preparations. Sodium periodate-susceptible phenol-water and phenol-chloroform-light petroleum lipopolysaccharide (LPS) extracts proved to be immunogenic for the rabbits as well. Convalescent sera from two patients with documented bacteremia due to genospecies 3, serovar 4, likewise revealed numerous anti-polypeptide and anti-LPS antibodies comprising the immunoglobulin G (IgG) and the IgM class.
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PMID:Immunobiology of Acinetobacter baumannii and genospecies 3. 821 96

Cultural filtrates (CF) of avirulent Salmonella virchow and Salmonella dublin have been studied for their influence on the delayed type hypersensitivity (DTH) to test-antigen in mice. It is found that i.p. injection of CF inhibits DTH in mice. The immunosuppressive activity is indicated in lipid fraction of CF and it may be removed from CF by the O-specific immunosorbent. It is heat-stable and disappears after phenol or trichloroacetic acid treatment. Gel filtration data evidence for high molecular weight of the active factor. These facts indicate to the connection of immunosuppressive activity with native lipopolysaccharide of avirulent Salmonella.
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PMID:[The immunosuppressive activity of filtrates of the culture broth from nonvirulent salmonellae]. 922 Oct 61

Malonaldehyde (MDA), a product of lipid peroxidation, is a presumptive marker for the development of oxidative stress in tissues and plasmas. In this study we report the photodiode array detection of the 2,4-dinitrophenylhydrazine (DNPH) derivatives of MDA using HPLC. Oxidative stress was produced by injecting (i.p.) bacterial lipopolysaccharide (LPS) into rats at a dose of 100 micrograms/kg, or i.v. into rabbits (1 microgram/kg), or added to freshly drawn human blood (200 ng/ml). Blood was collected at several time points up to 5 h, centrifuged, and equal volumes of 20% TCA were used to precipitate proteins from the plasma. The supernatants were derivatized with DNPH, and the aldehyde-DNPHs were extracted with pentane. After evaporation, aliquots of 10 microliters in acetonitrile were injected onto a Beckman Ultrasphere C18 (3 microns) column, chromatographed with an acetonitrile-water-acetic acid gradient mobile phase and scanned using Waters 996 photodiode array detector. Peak identification and homogeneity was determined by comparing the experimental peaks and UV scans with those of authentic standards. A significant increase in the DNPH derivative of malonaldehyde (MDA-DNPH), but not of the other aldehyde-DNPH derivatives of formaldehyde (FDA), acetaldehyde (ADA), acetone and propionaldehyde (PDA) was seen over the first hour after LPS administration in anesthetized rats, while in conscious rabbits this trend lasted up to 3 h. The retention times as well as the UV scans of the derivatized aldehydes matched the authentic standards. Thus, photodiode array detection has proved valuable in establishing this HPLC method for estimating oxidative stress. This technique could accurately measure pmol amounts of MDA-DNPH indicating the usefulness of photodiode array detection method for estimating small changes in the oxidative stress.
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PMID:High-performance liquid chromatographic peak identification of 2,4-dinitrophenylhydrazine derivatives of lipid peroxidation aldehydes by photodiode array detection. 954 33


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