Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have recently found that bacterial lipopolysaccharide (LPS) at minute doses inhibits the secretion of gastric acid and pepsin in rats. The present study was performed to examine the mechanism by which LPS exerts its antisecretory action. The i.p. injection of LPS resulted in a dose-dependent (40-4000 ng/kg) decrease in gastric acid output in pylorus-ligated rats. However, preinjection of indomethacin (2-10 mg/kg s.c.), an inhibitor of prostaglandin biosynthesis, prevented the LPS-induced inhibition of gastric secretion in a dose-related manner, while these concentrations of indomethacin by themselves did not affect gastric acid output. These results suggest that LPS requires an intact prostaglandin system to exhibit its inhibitory action on gastric secretion.
 ...
PMID:The gastric antisecretory action of lipopolysaccharide is blocked by indomethacin. 160 Oct 59

We have recently found that bacterial lipopolysaccharide (LPS) or endotoxin at minute doses inhibits the secretion of gastric acid and pepsin in rats. The present study was performed to determine whether this antisecretory action of LPS was a reversible biological response or a result of the destruction of gastric parietal cells by endotoxin. The intraperitoneal injection of LPS into pylorus-ligated rats resulted in a dose-related (40-4000 ng/kg) decrease in gastric acid secretion, with maximal inhibition being observed at a dose of 4000 ng/kg. The stomach then was examined both macroscopically and microscopically for the presence or absence of mucosal lesions or damaged gastric parietal cells. No morphological changes in the gastric mucosal structure including parietal cells were observed even in the rats injected with 4000 ng/kg of LPS. Next, basal gastric acid output was compared in the rats that had received LPS (4000 ng/kg, intraperitoneal) or saline alone 24 hr before. There was no significant difference in gastric acid secretion between the saline- and LPS-pretreated groups, indicating that the secretory capacity of gastric parietal cells returned to the control level at 24 hr after the injection of a maximal antisecretory dose of LPS. These results clearly suggest that the LPS-induced inhibition of gastric secretion results not from its toxic or destructive effect on the gastric secretory mechanism but from its reversible biological effect on gastric physiology.
 ...
PMID:Evidence that gastric antisecretory action of lipopolysaccharide is not due to a toxic effect on gastric parietal cells. 161 51

We used male Wistar rats to determine the effects of lipopolysaccharide (LPS) on gastric secretion. After pylorus ligation, 24-h fasted rats received i.p. injections of different doses of LPS dissolved in sterile saline. The amounts of gastric acid and pepsin secreted were determined 2, 4 or 8 h after injection. Small doses of LPS (10-1000 ng/rat) significantly inhibited the release of both gastric secretants as compared with control animals, and this inhibitory effect of LPS on gastric secretion was dose-related. The gastric antisecretory effect of LPS was still evident 8 h after injection, indicating that this action of LPS was long-lasting. These results suggest that LPS might be involved in the regulation of gastric secretion under certain pathophysiological conditions such as acute bacterial infections.
 ...
PMID:Lipopolysaccharide-induced inhibition of gastric acid and pepsin secretion in rats. 211 40

In an effort to elucidate the reason that fever in patients with severe bacterial infections subsided in some cases after the administration of human immunoglobulin preparations for intravenous use (IGIVs), we focused our attention on the antipyretic activity of IGIVs by investigating experimentally produced pyrexia in rabbits with Escherichia coli-derived lipopolysaccharide (LPS). Although little difference in antibody titers against the antigens composing molecules of LPS was found among the IGIVs that were used, IGIVs treated at pH 4 were demonstrated to inhibit a strongly LPS-induced second-phase febrile response, whereas the inhibitory effect of sulfonated and pepsin-treated IGIVs was weak. In vitro experiments on interleukin-1 production by rabbit macrophages stimulated with LPS, silica gel or latex beads and on rosette formation showed that these functions of the cells were also inhibited by IGIVs. The in vivo antipyretic activity and the results of the two in vitro experiments correlated closely. The inhibitory potency decreased in the following order: immunoglobulin G (IgG) treated at pH4, sulfonated IgG, and pepsin-treated IgG. Thus, it is possible that the subsidence of LPS-induced fever by IGIVs was mediated by inhibition of interleukin 1 production by means of binding of IgG to macrophages via an Fc receptor. Results of this study also indicated the importance of the structural integrity of the Fc portion of the IgG contained in the IGIVs to bind with its receptor on the macrophage so as to influence the various functions carried out by the cell.
 ...
PMID:Antipyretic activity of a human immunoglobulin preparation for intravenous use in an experimental model of fever in rabbits. 349 19

The mechanism of metallothionein (MT) induction by lipopolysaccharide (LPS) was studied using an in vitro system. Rat peritoneal macrophages were incubated with or without LPS, after which the incubation medium was overlaid on human hepatic (Chang) cells. MT synthesis was induced in Chang cells treated with the macrophage medium incubated with LPS. No induction was observed when LPS was added directly to the Chang cell medium or when Chang cells were treated with the macrophage medium incubated without LPS. These results suggest that induction of MT by LPS is mediated by a factor released from macrophages. The factor is different from the known primary inducers of MT, such as heavy metals, glucocorticoid hormones, interleukin 1, and interferon. The factor is heat stable, nondialyzable, and stable at pH 2. Although its activity is lost by pepsin and trichloroacetic acid, it is resistant to trypsin.
 ...
PMID:Induction of metallothionein by a macrophage factor and the partial characterization of the factor. 349 6

Previous work from this laboratory has demonstrated the persistence of Bacteroides intermedius in the livers of mice receiving an intraperitoneal inoculum of B. intermedius and Fusobacterium necrophorum. This study was undertaken to determine whether F. necrophorum enhanced the in vitro growth of B. intermedius. Tryptose phosphate broth did not support the growth of B. intermedius alone, but the bacterium did survive in a tryptose phosphate broth culture of F. necrophorum. B. intermedius cultured in F. necrophorum-conditioned tryptose phosphate broth grew impressively, reaching maximal absorbance at 24 h after inoculation. The growth of B. intermedius in F. necrophorum-conditioned tryptose phosphate broth was proportional to the amount of conditioned medium present. The B. intermedius growth-stimulating factor was detectable in conditioned medium 8 h after inoculation with F. necrophorum and could be detected throughout the 96-h incubation period. Growth-factor-active fractions eluted from a Sephadex G-100 column did not absorb at 280 nm and were retained on the column until 4 column volumes were eluted. The growth factor was nondialyzable and stable to boiling, lyophilization, extraction with hot aqueous phenol, and trypsin digestion. The factor was inactivated by exposure to pH 2.0 in the pepsin digestion protocol. Significant amounts of hexose, methyl pentose, and 2-keto-3-deoxyoctonate were detected in pooled growth-factor-active fractions eluted from the Sephadex column. This pool was also active in the Limulus lysate endotoxin assay. These results suggest that the B. intermedius growth-stimulating factor produced by F. necrophorum is a lipopolysaccharide.
 ...
PMID:Enhancement of Bacteroides intermedius growth by Fusobacterium necrophorum. 370 Jun 5

The binding of C1q to the human macrophage cell line U937 has been studied. Fluorescence microscopy with fluorescein-conjugated F(ab')2 anti-C1q antibody showed that 100% of the cell population is able to bind exogenous C1q. Monomeric C1q binding to U937 cells is very weak at normal ionic strength (I0.15) and was therefore investigated at I0.07, conditions which stabilize the binding. However, aggregation of C1q on dextran sulphate or a lipid A-rich lipopolysaccharide allowed a firm, binding at I0.15. Quantitative binding studies with monomeric 125I-C1q showed a concentration-dependent, saturable, specific and reversible binding involving specific membrane receptors. Scatchard plots of C1q binding indicated [1.6 +/- 0.7 (1 S.D.)] X 10(6) sites per cell with an equilibrium constant of (2.9 +/- 1.8) X 10(7) M-1 at I0.07. The location of the molecule region mediating C1q binding was established with collagen-like fragments prepared by partial pepsin digestion, confirming earlier results obtained by inhibition studies.
 ...
PMID:Characterization of the C1q receptor on a human macrophage cell line, U937. 637 Feb 41

Prior absorption of normal human serum (NHS) or C2-deficient human serum (C2D) with zymosan at 0 degrees C results in diminished consumption of C3 and factor B during subsequent incubation of the sera in Mg-EGTA buffer with zymosan at 37 degrees C for 30 min. An acid eluate from the zymosan restores the defect of absorbed NHS and C2D, and also enhances C3 and factor B utilization in hypogammaglobulinemic serum (H gamma S) in a dose-dependent fashion. The activity is specific in that the eluate from zymosan fails to enhance C3 and B depletion in H gamma S or absorbed NHS by lipopolysaccharide or Sepharose. The active component of th zymosan eluate emerges from both Sepharose 4B and Sephacryl S-200 in the region of molecules with m.w. of 150,000. Absorption with protein A-Sepharose removes the activity, demonstrating that it is IgG. Digestion of the IgG with pepsin fails to diminish activity, indicating that the Fc region is not required for activity; reduction to monovalent Fab' fragments, however, abrogates activity. When IgG antibody is bound to Protein A-Sepharose, it fails to enhance C3 depletion in H gamma S by Sepharose, indicating that binding of IgG antibody by the Fab region is necessary for enhancement of alternative pathway activity in human serum.
 ...
PMID:The role of immunoglobulins in alternative complement pathway activation by zymosan. I. Human IgG with specificity for Zymosan enhances alternative pathway activation by zymosan. 677 18

The modulating effect of bovine milk casein components and their digests on the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells induced or not induced by mitogens has been studied with a colorimetric assay using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. All the casein components and their digests tested had little mitogenic effect on the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells. Intact kappa-casein significantly inhibited the proliferative responses of mouse spleen lymphocytes and Peyer's patch cells induced by mitogens such as lipopolysaccharide from Salmonella typhimurium, concanavalin A, phytohaemagglutinin and pokeweed mitogen. In contrast, intact alpha s1-casein and beta-casein had little effect. kappa-Casein had an inhibitory effect after digestion by pancreatin or trypsin, but not after pepsin or chymotrypsin digestion. Both pancreatin and trypsin digests of alpha s1-casein and beta-casein significantly inhibited the proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells induced by mitogens, whereas pepsin and chymotrypsin digests of both caseins were without effect. Moreover, the trypsin digest of each casein component had an inhibitory effect on mouse spleen lymphocyte proliferation in the absence of mitogen. Since trypsin is a major proteinase in pancreatin, the substrate specificity of trypsin seems to be important for the formation of the inhibitory peptides from casein components. These observations suggest that intact kappa-casein and some peptides formed from milk casein components by the action of trypsin may suppress the immune responsiveness of neonates.
 ...
PMID:Inhibition of proliferative responses of mouse spleen lymphocytes and rabbit Peyer's patch cells by bovine milk caseins and their digests. 760 78

The immunogenicity of several Brucella melitensis cell-wall (CW) fractions was tested in BALB/c mice. These CW fractions were smooth lipopolysaccharide (S-LPS) fraction from smooth (S) B. melitensis strain 16M, sodium dodecyl sulphate-insoluble (SDS-I) CW fraction from B. melitensis strain 16M (S) undigested or digested with pepsin, and SDS-I CW fraction from rough (R) B. melitensis strain H38. The B. melitensis SDS-I CW fraction contained two major outer-membrane proteins (OMPs) of 25-27 kDa and 31-34 kDa, peptidoglycan (PG) and a small quantity (1.5%) of LPS. One month after immunisation, mice were challenged with virulent B. melitensis strain H38 (S) and Brucella spleen counts were recorded on days 28 and 49 after challenge. Before challenge, as measured by ELISA, the highest antibody responses to S-LPS were observed in mice immunised with SDS-I CW fraction from B. melitensis strain 16M (S), whether digested with pepsin or undigested. All immunised mice, except those immunised with the SDS-I CW fraction from the R strain, showed higher IgG1 than IgG2a antibody responses to S-LPS (IgG1:IgG2a ratio 3.64-7.71). Antibody responses to the 25-27-kDa OMP were very low, with the highest responses in the mice immunised with the SDS-I CW fraction from the R strain. These results indicated that, in BALB/c mice, these CW fractions probably induced Th2-dependent more than Th1-dependent antibody responses.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Immunogenic properties of Brucella melitensis cell-wall fractions in BALB/c mice. 788 2


1 2 3 4 Next >>