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

Primary astrocyte cultures, C6 glioma cells, and N18 neuroblastoma cells were assayed for nitric oxide synthase (NOS) activity with a bioassay of cyclic GMP production in RFL-6 fibroblasts. Treatment of astrocyte cultures for 16-18 h with lipopolysaccharide (LPS) induced NOS-like activity that was L-arginine and NADPH dependent, Ca2+ independent, and potentiated by superoxide dismutase. Induction was evident after 4 h, was dependent on the dose of LPS, and required protein synthesis. Treatment of astrocyte cultures with leucine methyl ester reduced microglial cell contamination from 7 to 1%, with a loss of 44% of NOS-like activity. C6 cells treated with LPS also showed Ca(2+)-independent and L-arginine-dependent NOS-like activity. N18 cells demonstrated constitutive Ca(2+)-dependent NOS-like activity that was not enhanced by LPS induction. These data indicate that NOS-like activity can be induced in microglia, astrocytes, and a related glioma cell line as it can in numerous other cell types, but not in neuron-like N18 cells.
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PMID:Induction of nitric oxide synthase in glial cells. 137 33

Given the pivotal role suggested for IFN-gamma in immune diseases of the vascular wall, we investigated the effects of IFN-gamma on nitric oxide (NO) and endothelin-1 (ET-1) expression in bovine aortic endothelial cells (BAEC). We have previously reported that TNF-alpha enhanced NO synthase activity in BAEC as assessed by quantifying release of bioactive NO with reporter monolayers and measuring conversion of L-[14C]arginine to L-[14C] citrulline. In murine macrophages IFN-gamma synergizes with TNF-alpha or lipopolysaccharide to induce robust increases in calcium-independent NO synthase activity. In this study we have found that IFN-gamma alone failed to have a significant effect on NO synthase activity in BAEC. In contrast to murine macrophages, IFN-gamma inhibited TNF-alpha-stimulated induction of endothelial NO synthase activity in a concentration-dependent manner. This observation suggests that there is major difference in the response of BAEC and murine macrophages to IFN-gamma. A second major aim of this study was to determine the effect of IFN-gamma on preproET-1 mRNA expression and ET-1 secretion rates in BAEC. IFN-gamma alone had little or no effect on ET-1 mRNA levels and basal ET release when measured for 8 h. However, cotreatment with IFN-gamma potentiated the stimulatory effect of TNF-alpha on BAEC ET-1 mRNA transcript levels and ET release. In contrast, pretreatment of cells with IFN-gamma for 16-24 h blunted the stimulatory effect of TNF-alpha. These findings suggest that endothelial cell expression of vasoactive mediators is modified by the temporal interplay of at least two immune mediators, IFN-gamma and TNF-alpha.
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PMID:Effects of interferon-gamma on nitric oxide synthase activity and endothelin-1 production by vascular endothelial cells. 138 25

In the skin, wounding initiates a complex array of physiological processes mediated by growth factors and inflammatory mediators which stimulate tissue repair and protect against infection. We report that primary cultures of human keratinocytes and a mouse keratinocyte cell line respond to the inflammatory stimuli gamma-interferon and lipopolysaccharide or tumor necrosis factor-alpha by producing nitric oxide and hydrogen peroxide, two reactive mediators that are important in nonspecific host defense. Nitric oxide is produced by the l-arginine- and NADPH-dependent enzyme, nitric oxide synthase. In murine keratinocytes, optimal enzymatic activity was found to be dependent on Ca2+ and calmodulin as well as on glutathione. Inflammatory mediators were also found to inhibit the growth of keratinocytes, an effect that could be reversed by a nitric oxide synthase inhibitor. Epidermal growth factor (EGF), which promotes wound healing by stimulating cellular proliferation, was found to be a potent antagonist of reactive nitrogen and reactive oxygen intermediate production by keratinocytes. EGF also reversed the growth inhibitory actions of the inflammatory mediators. These data suggest that nitric oxide produced by keratinocytes is important in the control of cellular proliferation during wound healing. Our findings that EGF effectively regulates the production of free radicals by keratinocytes may represent an important pathway by which this growth factor not only stimulates epidermal cell proliferation but also facilitates the resolution of inflammation following wounding.
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PMID:Epidermal growth factor suppresses nitric oxide and hydrogen peroxide production by keratinocytes. Potential role for nitric oxide in the regulation of wound healing. 138 21

The effect of LPSw (a lipopolysaccharide from wheat flour) on the bone resorption of 18-d chick embryonic calvaria was examined in an organ culture following the method of Raisz. Bone was prelabeled in culture medium containing 45Ca and chased in a cold medium. On addition of test samples, labeled calcium was released indicating the grade of bone resorption. LPSw (10-100 ng/ml) stimulated bone resorption, showing an effect comparable to parathyroid hormone (PTH) (1 U/ml). PTH at 1 U/ml decreased the total amount of calcium and phosphorus, while LPSw did not. LPSw is thus assumed to stimulate bone resorption more actively than PTH.
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PMID:Homeostasis as regulated by activated macrophage. VIII. LPSw (a lipopolysaccharide from wheat flour) can regulate bone resorption of chick embryo. 139 47

A procedure was developed to culture rainbow trout macrophages (M phi) on supported glass coverslips. Using this method and a variety of well-characterized Aeromonas salmonicida strains with normal or altered cell surfaces, we investigated the role of this unusual bacterial surface in the bacterium-M phi interaction. An intact crystalline protein array, the A-layer, mediated adherence of A. salmonicida cells to M phi even in the absence of opsonins. In contrast, unopsonized cells of an A-layer-negative (A-) mutant with a smooth lipopolysaccharide (LPS) layer were unable to interact with M phi. However, this ability was recovered when the A-layer was reconstituted onto the smooth LPS surface of these A- LPS+ cells. Two A. salmonicida mutants possessing the A-layer in different disorganized states had a reduced ability to interact with M phi. A+ cells grown under calcium limitation produced A-layers locked into an alternative conformation which mediated the highest levels of M phi association in the absence of opsonins or any other surface coating. Coating A+ cells with hemin greatly increased their levels of M phi association, and bacterial cells grown on trout blood agar plates also had a dramatic increase in their ability to interact with M phi. Only A+ A. salmonicida cells were highly cytotoxic to trout M phi, especially after being coated with hemin, presumably due to a more focused targeting of the bacterial cell onto the M phi surface and/or into the intracellular regions of the M phi.
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PMID:Interaction of the fish pathogen Aeromonas salmonicida with rainbow trout macrophages. 139 75

The outer membrane of gram-negative bacteria provides the cell with an effective permeability barrier against external noxious agents, including antibiotics, but is itself a target for antibacterial agents such as polycations and chelators. Both groups of agents weaken the molecular interactions of the lipopolysaccharide constituent of the outer membrane. Various polycations are able, at least under certain conditions, to bind to the anionic sites of lipopolysaccharide. Many of these disorganize and cross the outer membrane and render it permeable to drugs which permeate the intact membrane very poorly. These polycations include polymyxins and their derivatives, protamine, polymers of basic amino acids, compound 48/80, insect cecropins, reptilian magainins, various cationic leukocyte peptides (defensins, bactenecins, bactericidal/permeability-increasing protein, and others), aminoglycosides, and many more. However, the cationic character is not the sole determinant required for the permeabilizing activity, and therefore some of the agents are much more effective permeabilizers than others. They are useful tools in studies in which the poor permeability of the outer membrane poses problems. Some of them undoubtedly have a role as natural antibiotic substances, and they or their derivatives might have some potential as pharmaceutical agents in antibacterial therapy as well. Also, chelators (such as EDTA, nitrilotriacetic acid, and sodium hexametaphosphate), which disintegrate the outer membrane by removing Mg2+ and Ca2+, are effective and valuable permeabilizers.
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PMID:Agents that increase the permeability of the outer membrane. 140 89

The stimulating activity of several preparations isolated from a membrane proteoglycan of a nonencapsulated smooth strain of Klebsiella pneumoniae (Kp-MPG) on the oxidative burst of human blood monocytes was assessed by luminol-enhanced chemiluminescence (CL). Five Kp derivatives were studied: a 34-kd acylpoly(1,3)galactoside (APG), obtained by drastic alkaline hydrolysis and purified by chromatography; an APG preparation subjected to acid hydrolysis that removed the core part and all fatty acids, leaving intact the galactose chain of APG (GC-APG); an APG preparation subjected to mild oxidation (ox APG); a preparation obtained by mild alkaline hydrolysis of Kp-MPG, containing additional ester-linked C14 and C16 fatty acids bound to the APG molecule (EFA-APG); and a polymer of the latter compound, APG pol. EFA-APG directly stimulated monocyte CL, whereas Kp-MPG, APG pol, and the whole bacterial cells had little or no activity. APG itself and ox APG induced a weaker response than EFA-APG. Polymyxin B sulfate completely inhibited the CL response to bacterial lipopolysaccharide (LPS) but not to EFA-APG. The stimulating action of EFA-APG on blood monocytes was dependent on the extracellular levels of both calcium and magnesium. Preincubation of monocytes with monoclonal antibody anti-Mac-1 directed against CD11b, the alpha chain of complement receptor type 3 (CR3; CD11b/CD18), strongly inhibited CL activation by EFA-APG and to a lesser extent CL activation by unopsonized zymosan and rough LPS. Altogether, these findings provide indirect evidence for the contribution of the CD11b/CD18 integrin in the functional interaction of EFA-APG with monocyte membranes. They demonstrate the role of fatty acids in the triggering of monocyte oxidative burst, while the polysaccharide chain itself does not contribute to induction of the CL response in this model. In keeping with the effects of EFA-APG and APG, we show that the monocyte CL response was triggered by bacterial LPS from the rough strain of Salmonella minnesota Re 595 and its lipid A, but not by LPS from smooth strains, again suggesting a critical role for the lipid moiety.
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PMID:Activation of human monocyte chemiluminescence response by acylpoly(1,3)galactosides derived from Klebsiella pneumoniae. 143 64

The proliferative responses of Peyer's patch (PP) T cells from aged BALB/c mice to concanavalin A (Con A) are considerably reduced, as compared to those of the young (P < 0.001). This reduced reactivity of aged T cells could be partly, but not entirely, corrected by interleukin 2 (IL-2) (P < 0.001). PP T cells from aged mice responded synergistically to a protein kinase C (PKC) activator, phorbol myristate acetate (PHA), plus a calcium ionophore, ionomycin, at much lower concentrations than to Con A (P < 0.001); however, the maximal proliferative response still remained nearly at 8/10th of the young (P < 0.01) and higher levels of PMA (but not of ionomycin) were required (P < 0.001). Addition of IL-2 restored the diminished response to the levels of the young T cells (P < 0.05), but that of Con A did not (P > 0.05). The proliferative responses of PP B cells to lipopolysaccharide (LPS) do not differ from those of the young (P > 0.05), but the spontaneous proliferation of aged (unstimulated) B cells is enhanced nearly twofold versus that of the young (P < 0.001). Like the PP T cells, PP B cells from aged mice also responded synergistically to PMA plus ionomycin but to a lesser degree than those of the young under the same stimulation (P < 0.01). Their maximal proliferation required higher levels of PMA, but not of ionomycin and was also diminished (P < 0.01), compared to that of the young. B cell stimulatory co-factors, IL-4 and IL-6, failed to affect the response of aged and young B cells to PMA plus ionomycin (P > 0.05), whereas LPS remediates the reduced response of aged B cells to PMA plus ionomycin. Thus, T and B cells from senescent PP demonstrate an impaired proliferative responsiveness via the Ca-dependent PKC pathway. A T cell mitogen and B cell stimulatory cytokines did not alter this activation pathway, once optimally stimulated. Whereas, T cell stimulatory cytokine IL-2 and B cell mitogen LPS could restore the age-associated decline of the corresponding lymphocyte subsets, T and B cells, in activation of the Ca-dependent pathway. The altered transmembrane signal transduction appears to be intrinsically defective in these aged PP T and B cells.
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PMID:Effects of phorbol myristate and ionomycin on in vitro growth of aged Peyer's patch T and B cells. 143 53

In this study, the effect of bacterial endotoxin (lipopolysaccharide; LPS) and of LPS priming on the in vitro release of PGE2 from human placental explants was investigated. Both LPS and the calcium ionophore A23187 significantly stimulated PGE2 release (P less than 0.05). Simultaneous exposure of placental explants to both LPS and A23187 revealed no additive or synergistic stimulation of PGE2 release. LPS priming of placental tissue significantly increased A23187-stimulated PGE2 release when compared to non-LPS-primed tissues. The addition of exogenous arachidonic acid (the substrate for PGE2 synthesis) also significantly (P less than 0.05) stimulated PGE2 release. There was, however, no significant further stimulation of PGE2 release following LPS priming in arachidonic acid treated explants. These data suggest that LPS not only increases basal PGE2 release in human placentae, but also potentiates agonist-stimulated PGE2 release, possibly by increasing tissue capacity for endogenous arachidonic acid liberation.
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PMID:Lipopolysaccharide priming potentiates calcium ionophore stimulated human placental prostaglandin E2 release in vitro. 144 19

We established a method for measuring procoagulant action on human umbilical vein endothelial cells (HUVEC). HUVEC (2.5 x 10(4)/well) were stimulated with 1 microgram/ml endotoxin (lipopolysaccharide: LPS) for 6 hours at 37 degrees C in 5% CO2. After washing, the HUVEC were incubated with assay buffer containing Proplex ST 1 unit (factor VII)/ml, S2222 0.6 mg/ml and CaCl2 6.6 mM, for 30 minutes at 37 degrees C. The procoagulant activity was determined by measuring the supernatant at OD405. Calphobindin I, II and III (CPB I, CPB II and CPB III) are the calcium dependent phospholipid binding proteins that exhibit anticoagulant activity in vitro. In this study, we investigated the effects of CPB I, CPB II and CPB III on procoagulant activity (PCA) expressed on HUVEC. The results are as follows 1) CPBI inhibits the procoagulant activity on HUVEC in a dose-dependent manner (IC 50% less than 0.4 microM). The same doses (0.4 microM) of CPBII and CPBIII decreased the procoagulant activity to 28.1% (CPBII), and to 84.6% (CPB III). CPB anticoagulant activities were, CPBII greater than CPBI greater than CPBIII, in that order. 2) When 0.05% H2O2 was added to the cell culture medium wells, concentrations of CPBI in supernatants increased in a time-dependent manner, and they reached to the maximum after 8 hours. CPBI in supernatants after 24 hours were not detected without H2O2, but concentrations of 4.88 ng/ml/10(4) cells with 0.01% H2O2, and 9.60 ng/ml/10(4) cells with 0.05% H2O2 were detected.
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PMID:[Effect of coagulation inhibitor proteins (Calphobindins) on tissue factor expression of endothelial cells]. 145 41


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