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)

The effects of endotoxin on the activities of the major Na(+)-independent amino acid transporters in rat liver (Systems n, asc, L, bo,+, and y+) were studied using using hepatic plasma membrane vesicles (HPMVs). Rats were treated with a single dose of Escherichia coli endotoxin (E. coli lipopolysaccharide 0127:B8 (LPS), 7.5, 15, or 30 mg/kg BW) and HPMVs were prepared by Percoll density gradient centrifugation at various timepoints after LPS administration. Vesicle purity and integrity was established by assay of enzyme markers and identical equilibrium uptakes. The activities of the Na(+)-independent amino acid transport systems y+ and bo,+ (arginine), asc (alanine and cysteine), L (leucine), and n (glutamine) were evaluated by measuring the uptake of radiolabeled amino acids using a rapid mixing/filtration technique. Amino acid uptake by HPMVs consisted of saturable and nonsaturable components. Prior treatment with endotoxin did not alter the activities of Systems n, asc, or L but resulted in a time- and dose-dependent stimulation of saturable arginine transport. Arginine transport increased within 2 h of LPS administration and exhibited a return towards basal levels by 24 h. Nonsaturable uptake (diffusion) in HPMVs was unaltered by LPS treatment. Kinetic analysis of arginine transport demonstrated the presence of both a high affinity and a low affinity carrier. Treatment with LPS resulted in a 73% increase in the Vmax of the high affinity carrier (System y+) and a 25% increase in the Vmax of the low affinity transporter (System bo,+). The data indicate selective stimulation of Na(+)-independent arginine transport in the liver during endotoxemia which may serve to support important arginine-dependent pathways during sepsis.
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PMID:Hepatic Na(+)-independent amino acid transport in endotoxemic rats: evidence for selective stimulation of arginine transport. 774 45

It has been found that the rate of hepatocyte protein synthesis depends on the functional state of nonparenchymal liver cells (NPC), of Kupffer cells, in particular. When Kupffer cells were stimulated by intravenously injected lipopolysaccharide (LPS), zymosan or dextran sulfate, the rate of [14C]leucine incorporation into hepatic proteins increased 1.5-2-fold. Similar effects were observed in hepatocytes cocultured with NPC isolated from LPS-stimulated rats as well as in hepatocytes cultured in a conditioned medium from NPC treated with LPS, high density lipoproteins (HDL) and hydrocortisone. It is proposed that apoproteins of HDL resecreted by Kupffer cells may participate in the regulation of hepatocyte gene expression during stimulation of resident macrophages.
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PMID:[The role of nonparenchymal liver cells in activating protein synthesis in hepatocytes upon stimulating the mononuclear phagocyte system with lipopolysaccharide]. 777 77

We investigated the effect of several opioid peptides on the activation of murine peritoneal exudate macrophages (M phi) in vitro. M phi were treated with interferon (IFN) as a priming agent and bacterial lipopolysaccharide (LPS) as a triggering agent in the presence or absence of opioid peptides. M phi activation was assessed by their tumoricidal activity. When treatment with IFN and LPS resulted in a high level activation of M phi, dynorphin-A exerted no further enhancing effect. When treatment induced only weak activation, however, dynorphin-A augmented the M phi activation. Leucine-enkephalin, methionine-enkephalin, and also beta-endorphin had augmenting effects. An opioid receptor antagonist, naloxone, reduced the effect of dynorphin-A and beta-endorphin. When M phi were treated sequentially with IFN and LPS, beta-endorphin operated in combination with LPS only. Moreover, beta-endorphin was effective for already activated M phi. These results indicate that opioid peptides act on M phi via classical opioid receptors, and that responsiveness to opioid peptides is induced in the triggering stage of M phi activation.
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PMID:Augmenting effect of opioid peptides on murine macrophage activation. 790 88

The cytokine interleukin-10 (IL-10) has been implicated in the pathogenesis of a number of disease states, including Epstein-Barr virus and human immunodeficiency virus (HIV-1) infections. In the acquired immunodeficiency syndrome (AIDS), it has been suggested that IL-10 may have a deleterious effect by suppressing cell-mediated immunity. However, there are few data on its direct effects on HIV-1 replication. In the present study, we have found that recombinant human IL-10 (rhIL-10), present during days 0 through 2, potently inhibits HIV production in elutriated monocyte/macrophage (M/M) cultures with a 50% inhibitory concentration (IC50) of approximately 0.03 U/mL. This effect did not appear to be caused by toxicity to M/M because there was no change in cell viability, ability to phagocytose latex beads, or protein synthesis as measured by [3H]-leucine incorporation, at doses of rhIL-10 that inhibit viral replication. In addition, lipopolysaccharide-induced production of IL-1 beta, IL-6, or tumor necrosis factor-alpha was not affected at these doses, nor were human mononuclear cell proliferative responses to phytohemagglutinin, OKT3 antibody, or tetanus toxoid. HIV-1 replication was similarly decreased by rhIL-10 in the monocytoid line U937 without signs of cellular toxicity. However, these effects required much higher concentrations of rhIL-10, and viral production was only partially suppressed. rhIL-10 also slightly inhibited HIV-induced cytopathicity in ATH-8, a tetanus toxoid-specific, retrovirally immortalized T-cell line, but had no effect on HIV replication in the H9 and MOLT-4 T cell lines. Thus, rhIL-10 appears to inhibit HIV replication predominantly in cells of the M/M lineage. This effect may serve to reduce viral production in patients with AIDS. However, additional studies will be needed to more precisely define its physiologic role in this disease.
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PMID:Interleukin-10 suppresses human immunodeficiency virus-1 replication in vitro in cells of the monocyte/macrophage lineage. 791 40

To better understand the effects of freezing on various immunocompetent cell functions, the interleukin-6 (IL-6)-producing activities of frozen peripheral blood mononuclear cells (PBMCs) from healthy subjects were determined. Frozen, lipopolysaccharide (LPS)-activated PBMCs produced significantly larger quantities of IL-6 than fresh cells. Although elimination of radiosensitive, CD8+ suppressor T cells had no significant effect on PHA-induced IL-6 production by T cells, elimination of CD4+ Leu-8+ suppressor T cell subsets resulted in a significantly enhanced IL-6 secretion. Exogenous addition of prostaglandin E-2 to frozen PBMCs and monocytes inhibited LPS-induced IL-6 production. The results suggest that functional inactivation of a subset of cryosensitive, PGE-2-secreting monocytes is associated with an increase in IL-6 production by the other subset. They also indicate that a subset of CD4+ Leu-8+ T cells might be involved in feedback inhibition of PHA-induced T cell-mediated IL-6 production. The results provide further evidence that the presence of larger quantities of IL-6 in conjunction with increased amounts of IL-1 and IL-2 secreted by the frozen cells may be responsible for the previously reported enhanced immunoglobulin-producing abilities of frozen cells from clinically healthy subjects and from patients with lung cancer.
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PMID:Effects of cryopreservation on immune responses: VII. Freezing induced enhancement of IL-6 production in human peripheral blood mononuclear cells. 798 56

Oct2-isoform expression in splenic B cells stimulated with lipopolysaccharide or lipopolysaccharide plus phorbol-di-butyrate was analysed by cDNA cloning. The frequency of Oct2-positive clones was 1/15,000 in both libraries. Two new isoforms were found that generate novel amino- or carboxy-terminal sequences. An isoform lacking exon 11 destroyed the carboxy-terminal leucin-zipper region and introduced a frame shift creating a novel, proline-rich carboxy terminus. A new exon containing a highly basic region (4c) was characterized, between exons 4 and 5. This exon was inserted between glutamine-rich regions 2 and 3, carboxy terminal of a tentative leucine-zipper structure. In addition, a new combination isoform containing Oct2a's amino terminal insert (exon 7a) and Oct2b's carboxy terminal insert (exon 13) was found that created a novel large isoform, Oct2ab. More frequent use of the classical Oct2a and Oct2b isoforms was observed in the lipopolysaccharide-stimulated B cells, while a preference for the Oct2ab and Oct2ba isoforms was observed in lipopolysaccharide plus phorbol-di-butyrate-treated cells.
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PMID:Analysis of Oct2-isoform expression in lipopolysaccharide-stimulated B lymphocytes. 800 71

Hepatocytes from control and endotoxemic rats were cultured for 40 hours in 96-well dishes in medium containing 0-5 micrograms/ml of lipopolysaccharide in the presence or absence of 50 U/ml IFN gamma. Nitric oxide production was quantified by the accumulation of nitrite in the culture medium by the Greiss reaction. Hepatocyte proliferation and protein synthesis were measured by (3H)thymidine (TdR) and (3H)leucine (Leu) incorporation, respectively. Results are the mean +/- standard error of triplicate wells from four experiments.
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PMID:Role of nitric oxide in hepatic injury following acute endotoxemia. 808 Feb 2

Secretory leukocyte inhibitor (SLPI) is a potent inhibitor of serine proteinases, but sensitive to oxidative inactivation due to a methionine residue in the active centre of the inhibitor. We compared the potency of an oxidation-resistant mutant of recombinant SLPI with native recombinant SLPI in lipopolysaccharide (LPS)-induced emphysema in the hamster. Application of this oxidation-resistant mutant reduced the induced emphysema by 70 and 85% in two separate series of experiments. In contrast, an equal amount of native rSLPI resulted in significantly lower inhibition, 30 and 23%, respectively (P = 0.002). To demonstrate the effect of oxygen radicals upon a single LPS instillation in the lungs, we measured anti-neutrophil elastase activity in lung lavage fluid at 10 and 24 h after the instillation of a mixture of LPS and native rSLPI. We found that residual native rSLPI was only 70 and 55% active, respectively. The rSLPI-mutant remained 93% active in a similar experiment. The native and mutant inhibitor showed equal potency against proteinases in a granule extract of hamster neutrophils. We conclude that the replacement of methionine by leucine in the inhibitory centre of rSLPI results in a decreased sensitivity to oxidative inactivation and that this alone is sufficient to explain the greater efficiency of the rSLPI-mutant in reducing the extent of LPS-induced emphysema.
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PMID:Potency of an oxidation-resistant mutant of secretory leukocyte proteinase inhibitor in lipopolysaccharide-induced emphysema in hamsters. 809 18

Using a rat lung organ culture system, we analyzed the role of monocyte chemoattractant protein 1 (MCP 1) in leukocyte to lung adhesive interactions and monocyte-mediated lung injury. Quantitative leukocyte to lung adhesive interactions were examined using an adaptation of the Woodruff-Stamper frozen section binding assay. Pretreatment of organ cultures with recombinant human tumor necrosis factor (rhTNF alpha) resulted in a protein synthesis-dependent increase in the adhesiveness of lung tissue for peripheral blood monocytes. Adhesion of monocytes to lung tissue was not increased above baseline after 7 hours but increased more than twofold by 24 hours and persisted through 48 hours. Binding of monocyte to lung tissue was further increased when recombinant rat MCP 1 was added to monocyte suspensions immediately before being layered onto lung sections derived from either TNF alpha-treated or untreated organ cultures. Addition of antibody directed against rat CD11b/c resulted in a moderate reduction in monocyte binding. TNF or lipopolysaccharide-induced activation of mononuclear cells in the presence of [3H]leucine-labeled organ cultures resulted in lung injury as assessed by radioisotope release. Mononuclear cell-mediated organ culture injury could be partially inhibited with anti-rat MCP 1 antibody, anti-rat CD11b/c antibody, or antioxidants including catalase and deferoxamine. Anti-MCP 1 and anti-CD11b/c increased the absolute numbers of monocytes that could be retrieved from monocyte-lung co-cultures while catalase and deferoxamine did not. In vitro studies revealed that isolated rat peripheral blood monocytes produce O2- in response to MCP 1. These data provide a functional correlate for recent in vitro studies which suggest that MCP 1 may mediate leukocyte adhesive processes by up-regulating beta 2 integrin expression on monocytes. This study provides evidence that monocytes activated by MCP 1 can damage lung tissue through an oxidant-mediated mechanism. Monocyte chemoattractant protein 1 may participate in the pathogenesis of monocyte-mediated lung injury by modulating inflammatory cell adhesion as well as through monocyte activation.
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PMID:Analysis of monocyte chemoattractant protein 1-mediated lung injury using rat lung organ cultures. 810 96

Newborn infants have an increased morbidity and mortality from infection caused in part by diminished polymorphonuclear leukocyte (PMN) function and impaired recruitment of PMN to sites of inflammation. Recent studies in our laboratory and others have demonstrated the in vitro expression of several cytokines, including IL-1-beta, in adult human peripheral blood PMN. Because newborn infants have an impaired inflammatory response, we sought to compare the synthetic capability and regulation of cytokine expression in neonatal and adult PMN. In our present studies, we found that tumor necrosis factor-alpha and lipopolysaccharide could induce IL-1-beta expression in both neonatal and adult PMN and that neonatal PMN produced significantly more IL-1-beta when compared with adult PMN. The PMN chemotactic peptide fMet-Leu-Phe did not induce IL-1-beta expression in either adult or neonatal PMN. Elevated cytokine expression by neonatal PMN may play an important role in the regulation of the immune and inflammatory systems at sites of injury and infection in neonates.
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PMID:Elevated interleukin-1 expression in human neonatal neutrophils. 813 63


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