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

The interactions of polycationic antibiotics with lipopolysaccharide (LPS) isolated from parental and polymyxin-resistant strains of Salmonella typhimurium and Escherichia coli were measured by using a cationic spin probe. Electron spin resonance spectra indicated that increasing concentrations of cations competitively displaced probe from LPS aggregates. Polymyxin B and other cations displaced less probe from LPS of polymyxin-resistant strains than from LPS of the parental strains, whereas the same amount or more probe was displaced from isolates of the mutants by the structurally similar antibiotic, EM 49 (octapeptin). In general, the differential affinities of these antibiotics for LPS correlated with their antibiotic activity in vivo, suggesting that resistance results from a decrease in antibiotic permeability across the outer membrane due to alterations in the LPS which affect antibiotic binding. The alterations in the structure of LPS from the polymyxin-resistant mutants of E. coli were characterized using 31P nuclear magnetic resonance spectroscopy. The results suggested that esterification of the core-lipid A phosphates is responsible for increased resistance to polymyxin B and that this alteration is different from that previously proposed for the S. typhimurium strains. In both cases, however, resistance was the result of modifications that result in a less acidic lipid A.
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PMID:Decreased binding of antibiotics to lipopolysaccharides from polymyxin-resistant strains of Escherichia coli and Salmonella typhimurium. 303 93

Murine peritoneal thioglycollate-elicited macrophages were cultured for 3 days in the presence or absence of highly purified human macrophage colony stimulating factor (CSF-1). The cells were then challenged with vesicular stomatitis virus (VSV) for 24 hr. Ability to resist viral infection was measured in two ways. First, macrophage viability after infection with VSV was measured by washing to remove dead cells, staining the remaining cells with crystal violet, and reading absorbance. Second, a yield reduction assay was used to measure viral replication in the macrophage cultures. Cells treated with CSF-1 (500 to 2000 U/ml) and infected with VSV looked similar microscopically to uninfected cells and had absorbance values twofold to threefold higher than those of infected cultures not treated with CSF-1. The CSF-1-treated cultures also had a virus titer one log lower than that of the untreated cultures. Treatment with partially purified murine CSF-1 induced a similar reduction in virus titer, whereas other murine CSF tested (purified murine GM-CSF, lung-conditioned medium that contains GM-CSF and G-CSF, and WEHI-3B-conditioned medium as a source of IL 3) had little to no effect on virus titer. Antibody to murine IFN-alpha/beta added to the macrophage cultures inhibited the protective effect of CSF-1, indicating that the CSF-1 effect was due to induction of endogenous IFN. Treatment with lipopolysaccharide (1 ng/ml) had some protective effect, which was blocked with polymyxin B. Polymyxin B did not inhibit the effect of CSF-1.
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PMID:CSF-1-induced resistance to viral infection in murine macrophages. 303 81

An Interleukin 3 (IL 3) activity was found in the supernatants of mouse spleen cells stimulated by lipopolysaccharide (LPS). The IL 3 activity was maximum in the supernatants of 5 to 7 days cultures. IL 3 activity was assessed by the capacity of the spleen cell supernatants to allow the growth of the FDC-P2 cell line, a strictly IL 3 dependent cell line. Polymyxin B could inhibit the IL 3 induction by LPS.
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PMID:Presence of interleukin 3-like activity in the supernatants of lipopolysaccharide-stimulated mouse splenocytes. 309 23

The factors responsible for blood-brain barrier (BBB) injury during bacterial meningitis are incompletely defined. We evaluated the role of Haemophilus influenzae type b (Hib) lipopolysaccharide (LPS) in the alteration of blood-brain barrier permeability (BBBP) in an adult, normal and leukopenic, rat model of meningitis. Intracisternal inoculation of Hib LPS resulted in (a) dose-dependent increases in BBBP from 2 pg to 20 ng, with significant attenuation in the peak response after challenge with 500 ng and 1 microgram; (b) time-dependent increases in BBBP, with a delayed onset of at least 2 h, maximum alteration at 4 h, and complete reversal at 18 h; (c) greater BBBP than after challenge with the live parent strain; (d) and a close correlation (r = 0.86) between CSF pleocytosis and BBBP at 4 h. The LPS effect was significantly inhibited by preincubation with Polymyxin B and neutrophil acyloxyacyl hydrolase, however two different oligosaccharide-specific monoclonal antibodies did not inhibit activity. No change in BBBP after inoculation with Hib LPS occurred in leukopenic rats. Hib LPS, in the setting of an intact leukocyte response, exerts profound effects on BBBP.
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PMID:Haemophilus influenzae lipopolysaccharide-induced blood brain barrier permeability during experimental meningitis in the rat. 326 27

Bactericidal activity and binding of a 57,000-dalton cationic antimicrobial neutrophil granule protein (CAP57) are determined by the presence on bacteria of O-antigen polysaccharide chains and the availability of negatively charged groups in the lipid A region, the inner core region, or both regions of lipopolysaccharide. Polymyxin B (PMB)-resistant mutants with well-defined alterations in lipid A structure and charge (pmrA) are also more resistant to CAP57. We used biologically active radioiodinated CAP57 to study the characteristics and kinetics of binding to a sensitive Rb lipopolysaccharide chemotype, Salmonella typhimurium SH9178, and the relatively resistant pmrA mutant strain SH7426. Binding occurred rapidly and was specific and saturable. Because CAP57 appears to be bound in a manner similar to that of PMB, competition binding studies were performed. Excess PMB did compete with CAP57 for binding to SH9178. Nonapeptide, a polycationic derivative of PMB that has lost its hydrophobic portions, demonstrated a marked decrease in ability to compete for binding with CAP57 compared with PMB. This demonstrated the importance of hydrophobic binding in the interaction of CAP57 with the microbial surface. Thus, we have shown that binding of CAP57 to SH9178 is specific, saturable, and similar to binding of PMB. Both hydrophobic and ionic properties of CAP57 appear to be necessary for binding.
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PMID:Lipopolysaccharide structure determines ionic and hydrophobic binding of a cationic antimicrobial neutrophil granule protein. 328

Root planing has been advocated to render periodontally involved root surfaces 'biologically compatible' with the surrounding soft tissues and thus promote healing. However, recent work has shown that only small amounts of cytotoxic material are likely to be incorporated within the root surfaces, thereby questioning the rationale for the traditional emphasis that is placed upon the removal of 'diseased cementum'. This investigation assessed by limulus amoebocyte lysate (LAL) assay and Polymyxin B affinity chromatography the extent of residual lipopolysaccharide (LPS) following root surface instrumentation in vitro. A conservative regime was carried out, consisting of 15 instrument strokes per surface designed to ensure complete overlapping of the strokes. This harvested varying amounts of LPS from 18 single-rooted teeth while leaving behind less than 0.24 ng of LPS per tooth in the majority (72%) of cases. This finding endorses the growing belief that extensive root planing may not be warranted.
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PMID:Root surface debridement--an in vitro assessment. 329 94

A new approach has been developed to circumvent the problems of false positive reactions in the Limulus Amoebocyte Lysate (LAL) assay for lipopolysaccharide (LPS) in root surface materials. These LAL-reactive materials include thrombin, thromboplastin, ribonuclease, ribonucleic acid, lipoteichoic acid and peptidoglycan fragments. In the present study, hot phenol/water extraction of these substances followed by ultracentrifugation of the resulting aqueous phases reduced their concentrations to very low levels. Furthermore, the application of Polymyxin B/Sepharose 4B affinity chromatography to these extracts enabled their intrinsic LAL-activity to be determined. Use of these techniques to assay root surface materials has identified LPS as being the major LAL-reactive material present. The mean LPS yield for the periodontally involved teeth was 4.13 micrograms/tooth, representing 2.82 micrograms/root. In contrast, the mean yield of LPS for the periodontally uninvolved teeth was 3.12 ng/tooth.
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PMID:Identity of limulus amoebocyte lysate-active root surface materials from periodontally involved teeth. 346 18

In order to obtain specific tools for studying the alterations of the immunochemical structure of Yersinia enterocolitica lipopolysaccharide in various conditions, we have produced monoclonal antibodies reacting with core and O-polysaccharide chains of Yersinia enterocolitica O:3 LPS. Immunizations were made with whole bacterial cells and outer membrane preparation, respectively. Monoclonal antibody 2B5 reacted in enzyme immunoassay with purified core-lipid A complex, and its binding was not inhibited by Polymyxin B, suggesting that the target determinant is in the outer core. 2B5 recognized 100% of all tested Y. enterocolitica O:3 strains (n = 152) and reacted to some extent also with many other gram-negative bacteria. In immunoblotting with 2B5, a band corresponding to core-lipid A complex was visualized both with Y. enterocolitica, Brucella abortus and Haemophilus influenzae. In immunofluorescence assay, the only positive reaction was seen with Y. enterocolitica. Monoclonal antibody A6 reacted in enzyme immunoassay with purified O-polysaccharide chains, recognized 100% of tested Y. enterocolitica O:3 strains, and showed no cross-reactions with other bacteria. A typical ladder pattern was not seen in the immunoblotting analysis with A6. This suggests that the O-chain of Y. enterocolitica O:3 may be different from those in other gram-negative bacteria. These two antibodies will make it possible to study the structural variations of Yersinia enterocolitica LPS more precisely than described before, because of their fine specificity against important immunogenic components of LPS. They will also be useful in serology measuring the immune response against the target determinants of these antibodies.
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PMID:Monoclonal antibodies reacting selectively with core and O-polysaccharide of Yersinia enterocolitica O:3 lipopolysaccharide. 355 94

Cultured normal human pulmonary alveolar macrophages and peripheral blood monocyte-derived macrophages were studied for their capacity to metabolize [3H]25-hydroxyvitamin D3 (25OHD3). Incubation of macrophages with bacterial lipopolysaccharide (LPS) resulted in the conversion of [3H]25OHD3 to a more polar vitamin D3 metabolite (up to 15 pmol/10(6) cells). Untreated macrophages did not synthesize this metabolite. Several findings suggested that the metabolite was the biologically active form of vitamin D3, namely 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. (1) The metabolite comigrated with chemically synthesized 1,25-(OH)2D3 on four different high performance liquid chromatographic systems. (2) The metabolite had the same affinity for the chick intestinal 1,25-(OH)2D3 receptor as authentic 1,25-(OH)2D3. (3) The biological activity of the macrophage metabolite in vivo (stimulation of intestinal calcium absorption and bone calcium mobilization in rachitic chicks) was identical to the activity of chemically synthesized 1,25-(OH)2D3. The LPS-stimulated synthesis of the 1,25-(OH)2D3-like compound by macrophages was dose dependent in a linear fashion; a half-maximal response was typically found with 100-200 ng LPS/10(6) cells. Polymyxin B abolished the effects of LPS on 25OHD3 metabolism in macrophages. Our data suggest that LPS-stimulated macrophages can modulate, on a local level, the function of 1,25-(OH)2D3-responsive cells by releasing the 1,25-(OH)2D3-like metabolite.
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PMID:25-Hydroxyvitamin D3 metabolism by lipopolysaccharide-stimulated normal human macrophages. 378 26

The acrA mutation in Escherichia coli led to a substantial increase of the acriflavine-binding capacity of the cell, whereas the related mutations acrB (gyrB) and arcC did not. Metal ions such as Na+, K+, Mg2+, Ca2+ and Al3+ effectively released the bound acriflavine, in proportion to their ionic strengths. The presence of cations, in fact, increased the survival fraction of the cells in the acriflavine-containing medium. Polymyxin B, an antibiotic which binds to membrane phospholipid, competed with acriflavine for binding sites. Cell wall digestion by treatment with lysozyme and EDTA slightly decreased the acriflavine-binding capacity. Almost no difference was observed in acriflavine-binding capacity between intact cells and cells from which lipopolysaccharide has been extracted (46.9% removed from the acrA cells and 47.4% from the acrA+ cells). Acriflavine bound to the cells was most effectively extracted by ethanol containing 1% HCl or by 2% (w/v) SDS. The difference in the acriflavine-binding capacity between the acrA and acrA+ cells was also observed in the spheroplasts. These facts indicate a relationship between the acrA gene product and the acriflavine-binding capacity of the cells.
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PMID:Acriflavine-binding capacity controlled by the acrA gene of Escherichia coli. 390 Feb 82


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