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  • 1995-1999  (4)
  • 1990-1994
  • 1997  (4)
  • 1
    Electronic Resource
    Electronic Resource
    NSAIDs upregulate β2-integrin expression on human neutrophils through a calcium-dependent pathway (1997)
    Oxford UK : Blackwell Science Ltd.
    Alimentary pharmacology & therapeutics 11 (1997), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Margination of circulating neutrophils (PMN) into the gastric microcirculation is an early and critical event in the pathogenesis of non-steroidal antinflammatory drug (NSAID)-induced gastropathy. This effect is mediated through the upregulation of β2 integrins on the PMN surface.〈section xml:id="abs1-2"〉〈title type="main"〉Aims:To investigate whether indomethacin modulates: (1) Mac-1 expression; (2) Ca2+ mobilization ([Ca2+]i), protein kinase C and nitric oxide accumulation; and (3) mitogen-associated protein kinase phosphorylation in human PMN.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:Human PMN were isolated by centrifugation through a double Ficoll gradient. [Ca2+]i was measured in PMN loaded with fura-2 and Mac-1 expression by flow cytometry.〈section xml:id="abs1-4"〉〈title type="main"〉Results:Indomethacin caused a concentration- and time-dependent upregulation of CD11b and CD18 expression and PMN adhesion to endothelial cells. Maximal upregulation of Mac-1 expression (40–50%) occurred after a 30-min incubation with 0.1 mM indomethacin. The effect was prevented by removing the Ca2+. Ionomycin and thapsigargin caused a 7–10-fold increase in [Ca2+]i and a 2–4-fold increase in Mac-1 expression. Indomethacin induced a concentration-dependent phosphorylation of a 41-kDa mitogen-associated protein kinase. Tyrosine kinase inhibitors prevented the effect of indomethacin on Mac-1 expression and Ca2+ mobilization. Indomethacin and ionomycin increased superoxide generation, myeloperoxidase secretion and PMN adherence to endothelial cells and stimulated nitric oxide production. Indomethacin-induced Mac-1 upregulation was prevented by a nitric oxide synthase inhibitor.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:Indomethacin-induced upregulation of Mac-1 is mediated by changes in [Ca2+]i and nitric oxide. Phosphorylation of the 41-kDa mitogen-associated protein isoform is a previously unreported target of NSAID action. These effects might help to explain the ability of indomethacin to cause gastric neutrophil margination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.1997.00190.x
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of a K+-ATPase from Lactobacillus helveticus ATCC 15009 (1997)
    Springer
    Archives of microbiology 168 (1997), S. 205-209 
    Details
    ISSN: 1432-072X
    Keywords: Key words K+-ATPase ; Lactobacilli ; Potassium pump ; 2 ; 3-Butanedione ; Enzyme-phosphate complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lactobacillus helveticus ATCC 15009 (wild-type) membrane preparations hydrolyzed Mg2+-ATP as a function of K+ concentration (2–200 mM). Mg2+-ATP hydrolysis by L. helveticus membranes was strongly inhibited in the absence of exogenous K+, while it amounted to 6 nmol ATP hydrolyzed min–1 (mg membrane protein)–1 at 50 mM KCl (saturating conditions) and pH 7.2. The K+-dependent ATPase of L. helveticus displayed a relatively high affinity for potassium ions (K m = 800 μM) and was not affected by pretreatment of membranes with N,N’-dicyclohexylcarbodiimide. Membrane preparations were subjected to hypotonic shock to obtain a maximum yield of open profiles. The formation of a maximum level of enzyme-phosphate complex with a molecular mass of approximately 82 kDa was induced upon treatment of L. helveticus membrane preparations with low concentrations of [γ-32P]ATP in the presence of K+ and La3+ ions and was visualized by acidic SDS-PAGE. It was concluded that L. helveticus membranes contain an inwardly directed K+ pump whose presence is discussed in terms of its putative role in cytoplasmic pH regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050489
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  • 3
    Electronic Resource
    Electronic Resource
    Epixenosomes, peculiar epibionts of the ciliateEuplotidium itoi: Involvement of membrane receptors and the adenylate cyclase-cyclic AMP system in the ejecting process (1997)
    Springer
    Protoplasma 197 (1997), S. 57-63 
    Details
    ISSN: 1615-6102
    Keywords: Adrenalin ; Cyclic AMP ; Ejecting process ; Epixenosomes ; Membrane receptors ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The extrusive apparatus is the most prominent and complex structure of epixenosomes. In the present paper the mechanisms activating its ejecting process were investigated by means of in vivo treatments and cytochemical procedures at the ultrastructural level. The results obtained clearly demonstrated that the ejecting process in epixenosomes is triggered by the detection of external signals through membrane receptors and the consequent activation of the adenylate cyclase-cyclic AMP system as a transduction mechanism. The membrane receptors coming into play have an affinity for soybean agglutinin and have a precise localization at the top of the organism, just where a membrane interruption appears as a first step in the whole process. The factors that trigger ejection in nature are still unknown. In the laboratory, ejection was obtained in the presence of adrenalin, which has been proved to bind to the same receptors shown to have affinity for soybean agglutinin. So epixenosomes appear to possess specific binding molecules for a mammalian hormone in the appropriate location, i.e., in the plasma membrane, and this hormone induces a precise biological response. These results are particularly interesting if we consider that epixenosomes are enigmatic organisms in which prokaryotic and eukaryotic characteristics appear to coexist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279884
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  • 4
    Electronic Resource
    Electronic Resource
    Ca2+-ATPase Pump Forms and an Endogenous Inhibitor in Bovine Brain Synaptosomes (1997)
    Springer
    Neurochemical research 22 (1997), S. 297-304 
    Details
    ISSN: 1573-6903
    Keywords: Ca2+-ATPase ; synaptosomes ; calcium ; neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two forms of Ca2+-pump were identified in bovine brain synaptic membranes as aspartylphosphate intermediates and were characterized. The 140 kDa and 97 kDa phosphoproteins were digested by calpain, producing two phosphorylated fragments, of M.W. 124 and 80 kDa respectively, not inhibited by thapsigargin, and displayed a trypsin digestion pattern with the formation of one phosphorylatable fragment of about 80 kDa. These results suggest that both pumps belong to the Plasma Membrane-type of Ca2+ ATPases, differing from the Sarco- or Endoplasmic Reticulum kind. A plasma membrane Ca2+-ATPase proteinaceous inhibitor with molecular weight between 6,000 and 10,000 Da was resolved from synaptic terminal cytosol, where it is enriched by fourfold with respect to frontal cortex brain cytosol. Such enrichment is already evident in the correspondent crude fractions. The presence of calcium pump and its proteinaceous inhibitor inside the synaptic terminals from bovine brain is discussed in terms of free calcium level regulation in neuron synaptoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022442906246
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