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)

Interleukin-8 (IL-8) is a key mediator in the migration of neutrophils from the circulation to the site of inflammation in the tissue. IL-8 is secreted by many cell types in response to proinflammatory stimuli such as interleukin 1, tumor necrosis factor, and lipopolysaccharide and is a potent chemoattractant and activator of neutrophils. Neutrophil activating peptide-2 (NAP-2) and melanoma growth-stimulatory activity (MGSA/GRO) are structurally and functionally related to IL-8 and, like IL-8, bind to specific G protein-coupled receptors on neutrophils. In the present study two closely related cloned IL-8 receptor subtypes are characterized by expression of the cDNA clones in monkey kidney cells (COS-7) or chinese hamster ovary cells and analysis of their ligand binding profiles. Both receptor subtypes bind 125I-labeled IL-8 with similar high affinity, however, the F3R receptor binds IL-8 exclusively, while the 4Ab receptor binds both IL-8 and MGSA/GRO with high affinity and NAP-2 with lesser affinity. Furthermore, we demonstrate with the use of intersubtype chimeric receptors that the specificity of ligand binding to both IL-8 receptor subtypes is dictated by the heterogeneous NH2-terminal domain. The F3R receptor is representative of a restricted IL-8 receptor subtype, and 4Ab represents a nonrestricted receptor subtype. It is proposed that these subtypes be named IL-8 receptors alpha and beta, respectively.
 ...
PMID:Amino terminus of the interleukin-8 receptor is a major determinant of receptor subtype specificity. 128 Nov 58

The cytosol fraction of J774-1 murine macrophages activated with lipopolysaccharide (LPS) + interferon-gamma (IFN-gamma) was found to nitrosate a wide range of secondary and tertiary amines. The reaction was dependent on L-arginine and NADPH. The optimal pH for nitrosation was 7.2-7.3. Nitrosation was inhibited by arginine derivatives such as NG-monomethyl-L-arginine and NG-nitro-L-arginine, well-known inhibitors of nitric oxide (NO) synthase. These results indicate that nitrosation is mediated by NO synthase, which catalyzes formation of NO and L-citrulline from L-arginine. Nitrosamine formation also required oxygen and was inversely correlated with the basicity of nitrosatable amines. The nitrosation was inhibited by oxyhemoglobin, an NO trapping agent, and enhanced by superoxide dismutase, which stabilizes NO. LPS + IFN-gamma induced approximately 500-600 times greater nitrosation activity than that of non-activated macrophages. Macrophages treated with LPS alone exhibited 3-4 times greater nitrosation activity than untreated macrophages, whereas macrophages treated with IFN-gamma alone did not show enhanced nitrosation activity. A combination of the cytosols from macrophages treated with LPS alone and IFN-gamma alone did not nitrosate morpholine as rapidly as the cytosol of macrophages treated with both compounds together. The activity for forming L-citrulline and nitrite/nitrate from L-arginine was markedly induced by treatment with either LPS alone or LPS + IFN-gamma but not with IFN-gamma. Those results suggest that some other factor(s) in addition to NO synthase is involved for efficient nitrosation by the macrophage cytosol. This factor(s) was not induced in macrophages by either LPS- or IFN-gamma alone, but was induced only in the presence of the two compounds.
 ...
PMID:L-arginine-dependent formation of N-nitrosamines by the cytosol of macrophages activated with lipopolysaccharide and interferon-gamma. 171 76

Monoclonal antibody (mAb) probes were used to investigate the expression of lipopolysaccharide (LPS) on four Escherichia coli strains, grown under a variety of conditions in batch culture which mimicked some of the in vivo environmental conditions of an infected host. Techniques of silver staining, immunoblotting, whole cell ELISA and flow cytometry were all used to monitor the expression of LPS on the bacteria and the binding of the anti-LPS mAbs. Growth in heat-inactivated sheep serum and magnesium-depleted conditions demonstrated increased expression of LPS core and subsequent increased binding of anti-core mAbs. Magnesium-depleted conditions also resulted in decreased production of O-polysaccharide material. Iron-depleted bacteria showed only minor changes in LPS expression, although increased binding of anti-core mAbs was observed. Nitrogen-deficient/high-carbon conditions, chosen to promote capsule production, resulted in increased expression of O-polysaccharide and decreased binding of anti-core mAbs.
 ...
PMID:Monoclonal antibodies as probes for detecting lipopolysaccharide expression on Escherichia coli from different growth conditions. 172 64

The present in vitro investigations on amantadine (AmTd) and its isomer 2-aminoadamantane (2-NH2-Adam), and the corresponding analogs, 1-nitroadamantane (1-NO2-Adam) and 2-nitroadamantane (2-NO2-Adam), were undertaken to gain information about molecular features that might have a dominant role in inhibiting T lymphocyte proliferation and to determine whether all, or a subpopulation of thymic-dependent (T) lymphocytes might be impacted by these drugs. Studies were done using lymphocytes from untreated normal mice as well as cloned murine cytotoxic T lymphocytes, CTLL cells. T lymphocytes were defined by their proliferative response to concanavalin A (Con A), and thymic-independent (B) lymphocytes by their proliferative response lipopolysaccharide (LPS). Proliferation of CTLL cells was induced by supplementing the culture medium with lymphokine-containing medium or by adding recombinant interleukin (IL)-2. Proliferation was assessed by quantifying cellular incorporation of tritiated thymidine. The data show that the aminoadamantanes, AmTd and 2-NH2-Adam, impacted on Lyt-2+ T lymphocytes while sparing L3T4+ T lymphocytes. In addition, the data show that the location of the substituent group on the adamantane ring altered the molecule's capacity to modulate lymphocyte activity. And finally, results of studies comparing the inhibitory activity of AmTd and 1-NO2-Adam suggest a non-lysosomal mechanism of action. Possible implications of these findings are discussed.
 ...
PMID:Inhibition of lymphocyte proliferation by amantadine and its isomer, 2-aminoadamantane; impact on Lyt-2+ T cells while sparing L3T4+ T cells. 186 Jul 84

Pseudomonas aeruginosa elastase is a zinc metalloproteinase which is released during P. aeruginosa infections. Pseudomonas keratitis, which occurs following contact lens-induced corneal trauma, can lead to rapid, liquefactive necrosis of the cornea. This destruction has been attributed to the release of both host-derived enzymes and the bacterial products P. aeruginosa elastase, alkaline protease, exotoxin A, and lipopolysaccharide endotoxin. A synthetic metalloproteinase inhibitor, HSCH2 (DL)CH[CH2CH(CH3)2]CO-Phe-Ala-NH2, which we previously showed to be a potent inhibitor of corneal collagenase and alkali-induced corneal ulceration, was tested as a potential inhibitor of P. aeruginosa elastase. Inhibition constants (Kis) for the resolved diastereomers were determined with the chromogenic substrate furylacryloyl-glycyl-L-leucyl-L-alanine. One isomer had a Ki of 0.3 microM, while the other had a Ki of 0.4 microM. The more potent diastereomer was evaluated in vivo in experimentally induced Pseudomonas keratitis in rabbits. Following inoculation of one cornea of each rabbit, topical treatment with a 1 mM solution of the inhibitor significantly delayed the onset of corneal melting and perforation, as compared with the results for the control and gentamicin-treated groups. This protective effect suggests that the inhibitor may have a therapeutic application by delaying the progression of corneal destruction in Pseudomonas keratitis.
 ...
PMID:Inhibition of Pseudomonas aeruginosa elastase and Pseudomonas keratitis using a thiol-based peptide. 212 41

Insects synthesize several types of hemolymph proteins in response to bacterial infection. The objective of this study was to characterize a 48,000 dalton hemolymph protein induced in larvae of Manduca sexta after injection of bacteria. The protein, isolated by cation exchange and gel filtration chromatography from hemolymph of larvae injected with Micrococcus lysodeikticus, was found to be a glycoprotein with pI = 8.4. The molecular weight, isoelectric point, amino acid composition, and NH2 terminal sequence of the protein are similar to bacteria-induced protein P4 from Hyalophora cecropia, and the M. sexta protein is also designated P4. The hemolymph concentration of M. sexta P4 (35 +/- 7 micrograms/ml in day 3 fifth instar larvae) increases 30- to 45-fold by 48 h after injection of bacteria, but it does not increase in response to injection of distilled water. Lower levels of induction occur after injection of peptidoglycan fragments, zymosan, and lipopolysaccharide. The properties of M. sexta P4 are very similar to those of a previously characterized M. sexta hemolymph protein known as postlarval protein, and antibodies against P4 bind to post-larval protein.
 ...
PMID:Isolation and characterization of bacteria-induced protein P4 from hemolymph of Manduca sexta. 213 20

Ammonia-induced cell envelope injury was examined in pure cultures of Escherichia coli and Enterobacter aerogenes. Cell injury, as determined by the ratio of colony-forming units on m-T7 agar to colony-forming units on m-Endo agar, increased with exposure to increasing concentrations of ammonia. Cell envelopes appeared to be the site of injury as indicated by increasing susceptibility to lysozyme with increasing ammonia concentration. Cells exposed to ammonia also exhibited more cellular leakage than control cells. Leakage from cells exposed to ammonia included proteins, and all leaked substances increased in concentration as ammonia concentrations increased. The concentration of 2-keto-3-deoxyoctonate (KDO) in the outer membrane of E. coli increased with ammonia exposure, while KDO concentration in the outer membrane of E. aerogenes decreased. The results suggest that exposure of E. coli cells to high concentrations of ammonia disrupts the outer membrane and lipopolysaccharide-associated proteins, while E. aerogenes cells are affected through the disruption of bonds between KDO and the outer membrane.
 ...
PMID:Ammonia-induced cell envelope injury in Escherichia coli and Enterobacter aerogenes. 224 77

The 2-deoxy analogue of 3-deoxy-beta-D-manno-2-octulopyranosonic acid (2-deoxy-beta-KDO, 2) is a potent inhibitor of the enzyme 3-deoxy-D-manno-octulosonate cytidylyltransferase, which is involved in the biosynthesis of lipopolysaccharide, an essential component of the outer membrane of Gram-negative bacteria. Since compound 2 lacks antibacterial activity, a series of 8-substituted derivatives of 2 has been synthesized in an attempt to find enzyme inhibitors suitable for modification as antibacterials. Compounds 9, 11, and 13, in which the 8-hydroxy group of 2 is replaced by F, H, and NH2, respectively, were as potent inhibitors of the enzyme as 2, but were devoid of antibacterial activity, with the exception of the amino acid 13, which showed weak activity against some strains of Salmonella typhimurium.
 ...
PMID:Synthesis of 8-substituted derivatives of the 2-deoxy analogue of 3-deoxy-beta-D-manno-2-octulopyranosonic acid (2-deoxy-beta-KDO) as inhibitors of 3-deoxy-D-manno-octulosonate cytidylyltransferase. 254 Mar 31

The human mannose-binding protein (MBP) is a multimeric serum protein that is divided into three domains, a cysteine-rich NH2-terminal domain that stabilizes the collagen alpha helix of the second domain and a third COOH-terminal carbohydrate recognition domain. Previous studies have shown that both native and recombinant human MBP bind to wild-type virulent Salmonella montevideo that expresses a mannose-rich lipopolysaccharide. Interaction with MBP results in opsonization and killing by phagocytes. In this report we show that low concentration of MBP (less than 10 micrograms/ml) markedly enhance complement deposition via the alternative complement pathway on S. montevideo. Despite structural similarities between MBP and the C1q subcomponent of the first complement component, MBP did not restore classical pathway activity to C1q-deficient serum, nor did it activate C1s when added to a mixture of C1r and C1s. In the presence of MBP the C3 bound to S. montevideo during incubation in serum was in the form of C3b and iC3b at a ratio of 1:2. Presensitization of S. montevideo with MBP rendered this normally serum resistant organism susceptible to complement-mediated killing. These results emphasize that MBP and complement cooperate in first line defense of the nonimmune host.
 ...
PMID:Human mannose-binding protein activates the alternative complement pathway and enhances serum bactericidal activity on a mannose-rich isolate of Salmonella. 259 61

Lipopolysaccharide from Escherichia coli C interacts with polyvalent cations at low ionic strength at more than one site. The first site has high affinity with a KD value of 10(-8) M for Ca2+ and even stronger binding for [(NH3)5CoNH2Co(NH3)5]5+ and La3+. The high-affinity site for the latter cations is beyond the sensitivity of the assay method. The second, low-affinity, site for bivalent cations has a Km of 10(-3) M, whereas, for tervalent and quinquevalent metal cations and spermine and hexacyclen (1,4,7,10,13,16-hexa-azacyclo-octadecane), this constant has a value of 10(-5) M. Binding of cations to the high-affinity site does not alter the aggregation state of the lipopolysaccharide, but combination with the low-affinity site gives particles twice the size of those of the sodium salt. Very high Ca2+ concentrations (30 mM) give particles eight times the size of those of the sodium salt.
 ...
PMID:The interaction of cations with lipopolysaccharide from Escherichia coli C as shown by measurement of binding constants and aggregation reactions. 268 35


1 2 3 4 5 6 7 8 9 10 Next >>