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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previously we reported that immunostimulated astrocytes were highly vulnerable to glucose deprivation. The augmented death was mimicked by the peroxynitrite (ONOO--producing reagent 3-morpholinosydnonimine (SIN-1). Here we show that glucose deprivation and ONOO- synergistically deplete intracellular reduced glutathione (GSH) and augment the death of astrocytes via formation of cyclosporin A-sensitive mitochondrial permeability transition (MPT) pore. Astrocytic GSH levels were only slightly decreased by glucose deprivation or SIN-1 (200 μM) alone. In contrast, a rapid and large depletion of GSH was observed in glucose-deprived/SIN-1-treated astrocytes. The depletion of GSH occurred before a significant release of lactate dehydrogenase (a marker of cell death). Superoxide dismutase and ONOO- scavengers completely blocked the augmented death, indicating that the reaction of nitric oxide with superoxide to form ONOO- was implicated. Furthermore, nitrotyrosine immunoreactivity (a marker of ONOO-) was markedly enhanced in glucose-deprived/SIN-1-treated astrocytes. Mitochondrial transmembrane potential (MTP) was synergistically decreased in glucose-deprived/SIN-1-treated astrocytes. The glutathione synthase inhibitor L-buthionine-(S,R)-sulfoximine markedly decreased the MTP and increased lactate dehydrogenase (LDH) releases in SIN-1-treated astrocytes. Cyclosporin A, an MPT pore blocker, completely prevented the MTP depolarization as well as the enhanced LDH releases in glucose-deprived/SIN-1-treated astrocytes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background.  Helicobacter pylori stimulates nuclear factor-kappa B (NF-κB) activation and chemokine interleukin-8 (IL-8) expression in gastric epithelial cells. Ecabet sodium (ecabet), a locally acting antiulcer drug, is known to have anti-H. pylori activity. However, there is little understanding of how ecabet induces anti-inflammatory activity in gastric epithelial cells infected with H. pylori. The aim of this study was to investigate the effects of ecabet on IL-8 gene expression and NF-κB activation in human gastric epithelial cells infected with H. pylori.Materials and Methods.  After Hs746T, MKN-45, or SNU-5 gastric epithelial cell lines had been infected with cagA+cytotoxin+H. pylori in the presence of ecabet, IL-8 mRNA expression was assessed by quantitative reverse transcription–polymerase chain reaction, and IL-8 secretion was measured by enzyme-linked immunosorbent assay. NF-κB and inhibitory kappa B-alpha (IκBα) signals were assayed by electrophoretic mobility shift assay and Western blot, respectively. The activation of NF-κB and IL-8 reporter genes was determined by luciferase assay.Results.  Ecabet showed no antimicrobial activiy against Gram-positive or -negative bacteria. However, ecabet inhibited transcription of the IL-8 gene and secretion of IL-8 by gastric epithelial cells infected with H. pylori at a concentration of 5 µg/ml. Moreover, ecabet inhibited the activation of NF-κB and the degradation of IκBα in gastric epithelial cells in response to H. pylori infection. In addition, the NF-κB signal inhibited by ecabet was comprised predominantly of heterodimers of p65/p50.Conclusions.  Ecabet inhibited H. pylori-induced IL-8 gene transcription and secretion by suppressing the NF-κB signal. This inhibition might be one pathway by which ecabet exerts its anti-inflammatory effect on H. pylori-induced gastric inflammation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 14 (1997), S. 1203-1209 
    ISSN: 1573-904X
    Keywords: intracellular drug delivery ; drug carriers ; liposomes ; probenecid-sensitive anion transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Drug carriers such as liposomes may enhance the intracellular delivery of therapeutic agents for infectious or neoplastic diseases. However, the mechanisms affecting cellular retention of liposome contents are understood poorly. We tested the hypothesis that retention of anionic compounds may be modulated by a nonspecific probenecid-sensitive anion transport mechanism, and that liposome composition may determine the impact of such transporters on drug retention by cells. Methods. The fluorescent anionic dye hydroxy-pyrene-[ 1,3,6]-trisulfonate (HPTS) was transferred to the cytoplasm of cultured CV-1 or J774 cells by direct needle-microinjection or by ATP-induced permeabilization of the plasma membrane, respectively, to investigate whether the cells have anion transport mechanisms capable of extruding HPTS from the cytoplasm. Cellular retention of dye was monitored in the presence and absence of the anion transport inhibitors probenecid or sulfinpyrazone. Liposomes containing HPTS were co-labeled with tetramethylrhodamine-labeled phosphatidylethanolamine (Rho-PE) as a marker of liposome membrane fate, and uptake was investigated using J774 cells. Results. Needle-injected HPTS underwent both sequestration in early endocytic vesicles and rapid extrusion into the extracellular medium. Probenecid or sulfinpyrazone reduced the extrusion of HPTS. Thus HPTS is a substrate for a probenecid-sensitive anion transporter in J774 and CV1 cells. After delivery via fluid liposomes composed of phosphatidylglycerol: phosphatidylcholine: cholesterol (3:7:5 mole ratio) and co-labeled with Rho-PE, cell-associated HPTS declined more rapidly than did Rho-PE. Exposure of cells to 5 mM probenecid doubled the quantity of HPTS retained by cells, without changing the retention of the Rho-PE membrane marker. In contrast, the effect of probenecid was negligible when gel-phase liposomes of distearoylphosphatidyl-glycerol:cholesterol (10:5 mole ratio) were used. Conclusions. Probenecid-sensitive nonspecific anion transporters can mediate the extrusion of model anions delivered via liposomes. However, liposome composition modulates the amount of material subject to extrusion from cells, possibly by altering the endocytic compartment in which liposomes release their contents.
    Type of Medium: Electronic Resource
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