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)

The possibility of endotoxin transfer across haemodialysis membranes remains a controversial issue. Additional concern has arisen because of the recent introduction in clinical practice of highly permeable, synthetic dialysis membranes and of bacteria-contaminated bicarbonate concentrate with potential short-term and long-term hazards for haemodialysis (HD) patients. Therefore, we performed experiments in an in-vitro dialysis recirculation system using three different types of HD membranes, namely standard regenerated cellulose (Cuprophan, CU), polyacrylonitrile AN-69 (PAN), and polysulphone F-60 (PS). When radiolabelled lipopolysaccharide (125I M-LPS) from E. coli, together with 10 micrograms/ml unlabelled LPS, was added to the recirculating solution in the dialysis compartment, radioactivity could be detected in the blood compartment after 15 min and increased progressively with time up to respectively 6.7% (CU), 10.3% (PAN), and 10.3% (PS) of initial activity on the dialysate side. The addition of albumin to the solution on the blood side led to a decreased permeability of radioactivity (7.3% vs 10.3%), compared to the absence of albumin (tested only for PS membrane). Furthermore, 73% of 125I M-LPS transferred across the PS membrane in the presence of albumin was TCA-precipitable. In contrast, free iodine (Na 125I) incubated in an albumin-containing solution did not precipitate with albumin after the addition of TCA (precipitation of only 0.6%). Moreover, kinetics of transmembranous transfer of Na-125I were strikingly different from that of 125I M-LPS. Analysis by the method of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the blood side solution, after LPS addition in the dialysis solution and 30 min of back-filtration, revealed the presence of several silver-stainable and autoradiographic bands of low-molecular-weight range, probably LPS fragments. Finally, the presence of LPS in the dialysate compartment led to a moderate increase in interleukin 1 (IL-1) and tumour necrosis factor alpha (TNF) concentrations in plasma as well as in monocyte culture supernatants after isolation from recirculating normal human whole blood exposed to CU, PAN, or PS membrane. In conclusion, our study provides evidence for the permeation of low-molecular-weight LPS subunits across cellulosic and non-cellulosic HD membranes. The clinical significance, if any, of such a transfer has, however, still to be demonstrated.
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PMID:Permeability of cellulosic and non-cellulosic membranes to endotoxin subunits and cytokine production during in-vitro haemodialysis. 131 77

A study recently conducted across Canada showed that 64 of 2,503 clinical isolates of Haemophilus influenzae were resistant to beta-lactams without production of a beta-lactamase (L. D. Tremblay, J. L'Ecuyer, P. Provencher, M. G. Bergeron, and Canadian Study Group, Can. Med. Assoc. J. 143:895-900, 1990). The beta-lactamase-negative strains formed three distinct groups, with ampicillin MICs of 0.5 to 1, 2 to 4, and greater than or equal to 8 micrograms/ml for groups I, II, and III, respectively. We have investigated the mechanisms of resistance for eight strains originating from different infections and geographic areas. These strains were representative of groups I to III. Five strains were nontypeable, two were type B, and one was non-B. Chromosomal DNA extracted from each strain was used to transform the laboratory strain Rd. Transformants were selected on beta-lactam-containing plates and showed the same level of resistance to ampicillin as the donor strains. Differences in outer membrane proteins, porins, and lipopolysaccharide profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not change with resistance. Functional analyses of purified porins in artificial lipid bilayer experiments did not explain resistance. Peptidoglycan synthesis was measured by incorporation of [14C]alanine into trichloroacetic acid-insoluble cell wall material in the presence of chloramphenicol. The growth rate and the rate of peptidoglycan synthesis observed for the transformants of the isogenic set did not correlate with resistance. Whole-cell labeling with 125I-penicillin revealed modifications in penicillin-binding proteins (PBPs) among the transformants. In particular, PBPs 3A and 3B (65 and 63 kDa, respectively) showed a decrease in affinity for beta-lactams in all transformants (groups I, II, and III) and correlated with an increased MIC except in the transformant of group III, which showed higher levels of resistance. Partial purification and proteolytic digestion of 125I-penicillin-labeled PBP 3B led to two types of CnBr peptide profiles on SDS-PAGE, the profiles of the transformed strains from groups I and II being different from those of the control group and group III. Finally, electron microscopy revealed a distinct cell filamentation for the group III transformants. These data clearly indicate that changes in PBPs are a common mechanism that results in a significant level of non-beta-lactamase-mediated beta-lactam resistance in H. influenzae despite serotype, origin of isolation, or geographic distribution.
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PMID:Molecular basis of the non-beta-lactamase-mediated resistance to beta-lactam antibiotics in strains of Haemophilus influenzae isolated in Canada. 151 Apr 47

It has been proposed that tumor necrosis factor (TNF) is a direct regulator of postinjury hepatic protein synthesis. To test this hypothesis we investigated the total protein and specific acute phase protein synthesis response of murine hepatocytes to stimulation with mu-rTNF-alpha in vivo and in vitro. Total hepatocyte secretory protein synthesis was assessed by incorporation of [35-S] methionine into TCA-precipitated protein; and acute phase protein synthesis was assessed by induction of a 23-kD acute phase protein marker and by suppression of albumin synthesis determined by SDS-PAGE and autoradiography. We found that rTNF in vivo (8,000 units, IP injection) was associated with reduced total hepatocyte secretory protein synthesis (29 +/- 10%), increased synthesis of the 23-kD acute phase reactant (4.1 +/- 1.6-fold), and decreased albumin synthesis (0.68 +/- 0.2-fold) compared to saline-injected control animals. The in vitro stimulation of cultured murine hepatocytes directly with rTNF failed to demonstrate changes in total secretory protein synthesis or 23-kD protein; however, it did result in significant suppression of albumin synthesis (0.82 +/- 0.1-fold). In additional experiments, hepatocytes:nonparenchymal cell co-cultures stimulated with lipopolysaccharide (LPS) demonstrated protein synthesis changes similar to the in vivo TNF response including increased 23-kD protein and decreased albumin synthesis. These co-cultures demonstrated TNF production; however, addition of TNF antiserum during LPS stimulation had no effect on either 23-kD protein or albumin synthesis, despite the complete neutralization of TNF activity in the co-culture supernatants.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic acute phase protein synthesis is indirectly regulated by tumor necrosis factor. 169 90

The effect of a bacteriolytic enzyme, the endo-beta-N-acetylglucosaminidase excreted by Staphylococcus aureus (SaG) on the response of human lymphocytes to mitogens and on the immune response in mice has been studied. SaG inhibited incorporation of [3H]thymidine into TCA-precipitable material by human peripheral lymphocytes stimulated either by phytohemagglutinin or by concanavalin A, as well as formation of cytoplasmic immunoglobulin-containing cells by B lymphocytes treated with pokeweed mitogen. In all cases the level of inhibition first increased with the SaG concentrations reaching values of over 80% at an enzyme concentration of 100 micrograms/ml, and then decreased. Heat-inactivated SaG as well as SaG treated with both polyclonal and monoclonal specific antibodies or enzyme inhibitors such as chitotriose or hydrolyzed peptidoglycan had no effect on lymphocyte response to mitogens. In mice, SaG at a dose of 300 micrograms per mouse was found to cause a fourfold decrease in the anti-BSA antibody titer and an approximately 70-75% reduction in the immunoglobulin-containing cells in the spleens of mice injected with sheep red blood cells. SaG also completely abolished the enhancing effect of adjuvants such as muramyldipeptide, Freund's complete adjuvant, and Escherichia coli lipopolysaccharide. When SaG was injected into mice together with S. aureus peptidoglycan hydrolyzed either by SaG or by human lysozyme, the inhibitory effect on both production of anti-BSA circulating antibodies and appearance of Igc cells in the spleens of mice injected with sheep red blood cells was enhanced. As we know that (a) human tissues contain endo-beta-N-acetylglucosaminidases; (b) other human hexosaminidases (lysozymes) have previously been shown to interfere with the functions of immunocompetent cells; and (c) products of hexosaminidase hydrolysis of peptidoglycan (muropeptides) known to modulate immune response are ordinarily found in the urine of healthy persons, the possibility that hexosaminidases play a major role in the regulation of the immune response is raised and discussed.
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PMID:Staphylococcal endo-beta-N-acetylglucosaminidase inhibits response of human lymphocytes to mitogens and interferes with production of antibodies in mice. 190 69

Extraction of whole cells of Salmonella typhimurium and Escherichia coli with 1 M NaCl released 8 to 13% of their total cellular polyamines (putrescine, cadaverine, and spermidine). This extraction did not cause significant cell lysis, release of outer membrane (OM) constituents, or leakage of periplasmic beta-lactamase. The extraction released nearly equal amounts of polyamines from mdo (membrane-derived oligosaccharide) mutants and wild type. These findings suggest that the released polyamines are apparently bound to the cell envelope. NaCl (1 M) was as effective as trichloroacetic acid in releasing polyamines from isolated OM and lipopolysaccharide (LPS). Isolated OM contained four times more polyamines than the cytoplasmic membrane. The increased binding to the OM is apparently due to the association of polyamines with the polyanionic LPS. Nearly identical amounts of polyamines were found in the OM and LPS preparations (as quantified per milligram of LPS). These amounts are equal to those released from the intact cells by 1 M NaCl (quantitation as above). However, redistribution of polyamines took place after cell disruption, because the relative proportions of different polyamines varied in the OM and LPS preparations. These results indicate that polyamines released from intact cells during 1 M NaCl extraction are preferentially derived from the OM.
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PMID:Polyamines as constituents of the outer membranes of Escherichia coli and Salmonella typhimurium. 205 Jun 29

Specific binding sites for human pancreatic secretory trypsin inhibitor (PSTI) on 3T3 Swiss albino cells were studied using radioiodinated recombinant PSTI. Some ion species, pH, and temperature significantly influenced the binding of 125I-PSTI. Kinetic studies showed that the binding of 125I-PSTI to 3T3 Swiss albino cells reached the maximum level within 120 min at 4 degrees C, with a slow dissociation rate. The half-maximal inhibition (ID50) of 125I-PSTI binding by unlabeled PSTI occurred at 1.0 x 10(-10) M. On Scatchard analysis of the competitive binding data, linear plots indicated a single class of receptors with high affinity (Kd = 5.3 x 10(-10) M) on 3T3 Swiss albino cells, the number of receptors being 5,400 per cell. Treatment of surface-bound radiolabeled PSTI with a chemical crosslinker (disuccinimidyl suberate) led to the identification of a membrane polypeptide of Mr 140,000 to which PSTI was crosslinked. The formation was inhibited by an excess amount of unlabeled PSTI in a dose-dependent manner. The binding of 125I-PSTI to 3T3 Swiss albino cells was competitively inhibited by unlabeled PSTI but not by other peptide hormones, such as epidermal growth factor (EGF), bovine fibroblast growth factor, insulin-like growth factor, transforming growth factor alpha, platelet-derived growth factor, and tumor necrosis factor, indicating the presence of receptors specific for PSTI. Various protease inhibitors had no or only a little effect, and mercaptoethanol and dithiothreitol strongly decreased the binding of 125I-PSTI. Incubation at 37 degrees C resulted in rapid internalization of cell-bound 125I-PSTI, followed by the appearance of trichloroacetic acid-soluble 125I-radioactivity in the culture medium, due to degradation of internalized PSTI. In addition, PSTI stimulated [3H]thymidine incorporation into DNA on 3T3 Swiss albino cells in a dose-dependent manner. The combined addition of PSTI and EGF stimulated [3H]thymidine incorporation to an extent greater than that seen with either agent alone. These results indicated that the biological effect of PSTI was mediated by high affinity plasma membrane receptors, which were not a cell-surface proteinase(s). Specific binding of 125I-PSTI was noted with the following cells: WI-38, 3T3 Swiss albino, HUVE, BDC-1, and H4-II-E-C3.
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PMID:Identification and characterization of receptors specific for human pancreatic secretory trypsin inhibitor. 217 May 60

Tumor necrosis factor (TNF) has been proposed as a primary inflammatory mediator of septic shock. In vitro and in vivo studies indicate that endotoxin- or lipopolysaccharide (LPS)-activated macrophages are a principle source of TNF; however, membrane signal transduction and intracellular pathways by which LPS triggers TNF production in macrophages are unclear. Recent evidence indicates that specific protein phosphorylation via activation of protein kinase C (PKC) is an early, critical step in the signaling of macrophage TNF production by phorbol esters. We hypothesize that PKC activation is also required in LPS-signaled Kupffer cell (KC) TNF production. Murine KCs were obtained by liver perfusion and digestion and then stimulated with LPS (Escherichia coli O111:B4) or LPS in the presence of H-7, a selective PKC inhibitor. Conditioned media was collected at 3 hr for assay of TNF utilizing the L929 cytolysis bioassay standardized to murine-rTNF-alpha. We found that H-7 inhibited significantly LPS signaled TNF release at a concentration of 10 microM, while H-8 (a cyclic nucleotide specific inhibitor) had no effect. The effect of H-7 was dose dependent and present at varying concentrations of LPS. Down regulation of PKC activity by preincubation of KCs with phorbol myristate acetate (PMA, a direct activator of PKC) also resulted in significantly reduced TNF release after LPS stimulation. The inhibitor H-7 (10 microM) also significantly inhibited LPS signaled prostaglandin E2 release in Kupffer cells. Total and specific intracellular protein phosphorylation was determined by trichloroacetic acid precipitation and SDS-polyacrylamide gel electrophoresis after labeling stimulated Kupffer cells with 32Pi. Total protein phosphorylation was not significantly altered by LPS stimulation; however, autoradiograms from PMA- and LPS-stimulated KCs demonstrate enhanced phosphorylation of a 40-kDa protein (2.7 +/- 0.9-fold) and a 33-kDa protein (3.1 +/- 1.0-fold) which were inhibited by H-7. We conclude that activation of PKC and protein phosphorylation are required steps in the signal transduction pathway of LPS-stimulated TNF production in Kupffer cells.
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PMID:Tumor necrosis factor production by Kupffer cells requires protein kinase C activation. 220 49

Rabbits reconvalescent from experimental septicemia due to serologically defined strains of Serratia marcescens were examined for the diversity of their humoral antibody response with traditional serological procedures and the Western blot (immunoblotting) technique. Trichloracetic acid (TCA)-whole cell extracts of the homologous and heterologous O-antigen reference strains served as the antigen for the latter procedure. Reconvalescent rabbit sera contained antibodies against the homologous lipopolysaccharide (LPS) moiety (molecular weight (MW) range = 45-31 kilodaltons (= k] and antibodies against numerous heat-modifiable, cross-reactive proteins, in particular 7 proteins characterized by MWs of 117 k, 95 k, 91 k, 71 k, 68 k, 38 k, and 33 k in TCA-whole cell extracts from the homologous as well as from 11 heterologous S. marcescens O-antigen reference strains. Rabbits, which had been actively immunized with TCA-whole cell extracts from representative S. marcescens strains, mounted a humoral antibody response remarkably similar to that of rabbits which had recovered from septicemia, except that the sera from the actively immunized animals interacted somewhat more strongly with an additional cross-reactive protein (MW = 47 k). Conversely, conventional anti-O and anti-H rabbit immune sera revealed antibodies directed predominantly against the homologous LPS moiety (MW range = greater than or equal to 200 k - less than or equal to 15 k). It was concluded that numerous proteinaceous cellular constituents of S. marcescens accounted for immunoblot cross-reactivity.
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PMID:Humoral antibody response of rabbits against experimental Serratia marcescens septicemia. 224 83

The molecular heterogeneity of S. sonnei lipopolysaccharide (LPS), reflecting the size of lateral O-specific polysaccharide chains, has been established by the method of electrophoresis in acrylamide gel in the presence of sodium dodecyl sulfate and urea. The dominating components fall into three types, viz. those with 0-3, 10-16 and 35-40 repeating structures, the remaining components being minor ones. The electrophoretic profile of S. sonnei LPS considerably differs from the profiles of Escherichia coli and S. flexneri LPS, but coincides with the LPS profiles of other strains with different virulence. The preparations of LPS obtained by extraction with trichloroacetic acid have the same electrophoretic profiles as LPS obtained by the method of aqueous phenol extraction. The domination of certain molecular variants reflects, seemingly, specific features of the biosynthesis of LPS, characteristic of a given strain. The mechanisms of the preferable synthesis of lateral O-specific chains of the definite size and the importance of the molecular parameters of lateral chains for the biological properties of LPS require further study.
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PMID:[The molecular heterogeneity of Shigella sonnei lipopolysaccharide based on polyacrylamide gel electrophoretic data]. 225 81

The aerobactin iron-uptake system of plasmid ColV-K30, genetically isolated from other plasmid determinants by molecular cloning, was sufficient to restore full virulence in a mouse peritonitis model to a clinical Escherichia coli isolate, D551 (O78:H-), whose resident aerobactin-encoding ColV plasmid had been lost by curing. Antiserum was raised in rabbits against live E. coli K12 cells expressing the outer-membrane aerobactin receptor protein and absorbed with an isogenic strain lacking the receptor. This antiserum inhibited binding of aerobactin, cloacin DF13 and bacteriophage B74K to the native protein in whole E. coli K12 bacteria expressing the receptor, or in membranes prepared from such organisms. However, it did not react with the native receptor protein in several wild strains unless lipopolysaccharide was first removed by treatment with trichloroacetic acid, nor did it protect mice in experimental infections with strain D551. Antisera raised in rabbits against partially or fully denatured forms of the aerobactin receptor reacted only in assays involving denatured protein; they showed no inhibition of the biological activities of the native receptor.
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PMID:Inhibition of biological activities of the aerobactin receptor protein in rough strains of Escherichia coli by polyclonal antiserum raised against native protein. 269 45

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