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  • 1
    Electronic Resource
    Electronic Resource
    Interleukin-10 Down-Regulates Oxidative Metabolism and Antibody-Dependent Cellular Cytotoxicity of Human Neutrophils (1997)
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 45 (1997), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The authors investigated the ability of interleukin-10 (IL-10) to modulate some constitutive or interferon-γ (IFN-γ)-enhanced activities of human neutrophils. An 18 h culture of neutrophils with IL-10 dose-dependently down-regulated their capacity to produce O2− and lucigenin-amplified chemiluminescence in response to n-formyl-methionyl-leucylphenyl-alanine (FMLP). Furthermore, treatment of neutrophils with IL-10 decreased in a dose-dependent fashion, their capacity to lyse antibody-coated sheep erythrocytes. Membrane expression of FcγRI, FcγRII, FcγRIII, CR1, CR3 and FcγR- and CR-mediated phagocytosis were not modified by the cytokine. Culture of neutrophils with IFN-γ (100 U/ml) did not modify their FcγR- and CR-mediated phagocytosis, but significantly up-regulated FcγRI and CR3 membrane expression as well as their oxidative metabolism and antibody-dependent cellular cytotoxicity (ADCC). When IL-10 and IFN-γ were added simultaneously to neutrophil culture, IL-10 dose-dependently reduced IFN-γ-induced increase of CR3 expression, O2− production (in response to both FMLP and phorbol 12-myristate 13-acetate, or PMA) and ADCC, but did not change FcγRI expression on phagocytes. These results demonstrate that IL-10 is a significant neutrophil deactivator and provide new information on the role of IL-10 in the regulation of neutrophil-mediated inflammatory processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.1997.d01-393.x
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  • 2
    Electronic Resource
    Electronic Resource
    Enhancement of catalytic activity of the ammonium/potassium salt of 12-molybdophosphoric acid by iron ion addition for the oxidation of isobutane to methacrylic acid (1995)
    Springer
    Catalysis letters 32 (1995), S. 215-226 
    Details
    ISSN: 1572-879X
    Keywords: heteropoly compounds ; isobutane oxidation ; methacrylic acid ; methacrolein ; iron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of isobutane to methacrolein and methacrylic acid was carried out over potassium/ammonium salts of 12-molybdophosphoric acid (Keggin-type heteropoly compounds), with overall selectivity to the desired products higher than 50%. The addition of iron to the catalyst composition led to a substantial enhancement of the catalytic activity, with an increase in the yield to the desired products, even though the selectivity decreased. The catalysts all have a secondary cubic structure, and are stable in the reaction environment. No trace of structural decomposition was found in spent catalysts. It was found that the addition of iron led to a substantial increase in the catalyst acidity and it is proposed that the Lewis acidity might play a role in the activation of the paraffin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806116
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  • 3
    Electronic Resource
    Electronic Resource
    On the influence of the acid-base character of catalysts on the oxidative dehydrogenation of alkanes (1996)
    Springer
    Topics in catalysis 3 (1996), S. 451-460 
    Details
    ISSN: 1572-9028
    Keywords: MgO-, Mg-Al mixed oxide ; Al2O3-supported vanadium oxide ; VAPO-5 ; MgVAPO-5 ; oxidative dehydrogenation of ethane, propane,n-butane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Vanadium oxides supported on metal oxide, i.e. Al2O3, MgO and Mg-Al mixed oxide, and V-containing microporous materials (VAPO-5 and MgVAPO-5) have been tested in the oxidative dehydrogenation of C2-C4 alkanes. In all cases, tetrahedral vanadium species (isolated and/or associated) were mainly observed from51V-NMR and diffuse reflectance spectroscopies. The reducibility of V5+-species, determined from the onset-reduction temperature, decreases as follows: VOx/AL 〉 VAPO-5 〉 MgVAPO-5 =VOx/MG 〉 VOx/MG + AL. The acid character of catalysts, determined from the FTIR spectra of pyridine adsorbed, decreases as: MgVAPO-5 〉 VOx/AL 〉 VAPO-5 〉 VOx/MG + AL 〉 VOx/MG. A similar trend between V-reducibility of the catalyst and its catalytic activity for the alkane conversion was observed. However, the selectivity to olefins depends on the acid-base character of catalyst and the alkane fed. In the ODH ofn-butane, the higher the acid character of the catalyst the lower the selectivity to C4-olefins, while in the ODH of ethane an opposite trend between the catalyst acidity and the selectivity to ethene was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02113867
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of potassium on the selective oxidation ofn-butane and ethane over Al2O3-supported vanadia catalysts (1995)
    Springer
    Catalysis letters 34 (1995), S. 51-58 
    Details
    ISSN: 1572-879X
    Keywords: undoped and potassium-doped alumina-supported vanadia catalysts ; oxidative dehydrogenation of ethane andn-butane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The catalytic properties of undoped and K-doped (K/V atomic ratio of 0.5) Al2O3-supported vanadia catalysts (∼4.5 wt% of V2O5) for the oxidation ofn-butane and ethane were studied. Isolated tetrahedral V5+ species are mainly observed in both undoped and K-doped samples. The incorporation of potassium decreases both the reducibility of surface vanadium species and the number of surface acid sites. Potassium-free vanadium catalysts show a high selectivity during the oxidative dehydrogenation (ODH) of ethane but a low selectivity during the ODH ofn-butane. However, the presence of potassium on the vanadium catalysts strongly influences their catalytic properties, increasing the selectivity to C4-olefins fromn-butane and decreasing the selectivity to ethene from ethane. The role of the acid-base characteristics of catalysts on selectivity to ODH reactions is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808321
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  • 5
    Electronic Resource
    Electronic Resource
    Inhibition of the M r 70,000 S6 kinase pathway by rapamycin results in chromosome malsegregation in yeast and mammalian cells (1998)
    Springer
    Chromosoma 107 (1998), S. 498-506 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The antifungal and immunosuppressive drug rapamycin arrests the cell cycle in G1-phase in both yeast and mammalian cells. In mammalian cells, rapamycin selectively inhibits phosphorylation and activation of p70 S6 kinase (p70S6K), a protein involved in the translation of a subset of mRNAs, without affecting other known kinases. We now report that rapamycin causes chromosome malsegregation in mammalian and yeast cells. Chromosome malsegregation was determined by metaphase chromosome analysis of human lymphocytes and lymphoblasts, detection of CREST-positive micronuclei in human lymphoblasts and Chinese hamster embryonic fibroblast (CHEF) cells, and selection of doubly prototrophic cells in a specially constructed yeast strain. The number of ana-telophases with displaced chromosomes and interphase and mitotic cells with an irregular number of centrosomes was also determined in CHEF cells. In quiescent mammalian cells (human lymphocytes and CHEF cells) induced with growth factor to re-enter the cell cycle, rapamycin was effective when cells were exposed at the time of p70S6K activation. In yeast, rapamycin was more effective when treatment was started in G1- than in G2-synchronized cells. Cells from ataxia telangiectasia (A-T) patients are characterized by chromosome instability and have recently been found to be resistant to the growth-inhibiting effect of rapamycin. We found that an A-T lymphoblastoid cell line was also resistant to the induction of chromosome malsegregation by rapamycin, but the level of spontaneous aneuploidy was higher than in normal cells. In yeast, the induction of chromosome malsegregation was dependent on the presence of a wild-type TUB2 gene, encoding the β-subunit of tubulin. The finding that rapamycin acts in different cell types and organisms suggests that the drug affects a conserved step important for proper segregation of chromosomes. One or more proteins required for chromosome segregation could be under the control of the rapamycin-sensitive pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050335
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  • 6
    Electronic Resource
    Electronic Resource
    Regeneration of fertile plants from isolated zygotes of rice (Oryza sativa) (1999)
    Springer
    Plant cell reports 19 (1999), S. 128-132 
    Details
    ISSN: 1432-203X
    Keywords: Key words Zygote ; Egg cell ; Plant regeneration ; Individual culture ; Rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple mechanical method has been developed which allows the routine isolation of unfertilized and fertilized egg cells from ovules of Japonica and Indica rice varieties. In the experiments described, the majority of the egg cells and zygotes survived the isolation procedure when the donor plants were in a vigorous state. About 40% of the surviving zygotes underwent sustained development when cultured in Millicell inserts with a non-morphogenic rice feeder-cell culture. Nearly all zygote-derived callus cultures regenerated multiple shoots, which could be subsequently rooted with high efficiency. Zygote-derived plantlets matured to fertile plants when transplanted to soil. So far, about 80 independent plants each from the Japonica variety 'Taipei309' and the Indica variety 'IR58' have been regenerated. The potential of this single-cell regeneration system for marker gene-free transformation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050722
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  • 7
    Electronic Resource
    Electronic Resource
    Functional role of low-voltage-activated dihydropyridine-sensitive Ca channels during the action potential in adult rat sensory neurones (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 954-963 
    Details
    ISSN: 1432-2013
    Keywords: Ionic channels ; Patch-clamp ; Electrophysiology ; Calcium ions ; Dorsal root ganglia ; Action potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal cell firing is crucial to nerve-nerve communication. The ability to produce consecutive action potentials is related to the activation of inward currents after each upstroke. If fast Na current is indeed responsible for the overshoot, it is still unclear which current drives membrane voltage to the Na threshold. In this study we present evidence that in adult rat sensory neurones a dihydropyridine-sensitive Ca channel exists in addition to the well characterized L-type, or high-threshold Ca channel. During stimulated action potential trains, L-type Ca channels open during the excitation wave, whereas activity of the other dihydropyridine-sensitive Ca channel was observed primarily between action potentials. This second Ca pathway shows remarkably long openings at negative potentials after a series of positive prepulses. The nerve action potential and the repetitive firing work as a physiological Ca channel facilitation mechanism. Therefore, we suggest that this novel Ca conductance provides inward current, between two consecutive action potentials, able to modulate the frequency of neuronal bursts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02332183
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  • 8
    Electronic Resource
    Electronic Resource
    Functional role of low-voltage-activated dihydropyridine-sensitive Ca channels during the action potential in adult rat sensory neurones (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 954-963 
    Details
    ISSN: 1432-2013
    Keywords: Key words Ionic channels ; Patch-clamp ; Electrophysiology ; Calcium ions ; Dorsal root ganglia ; Action potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal cell firing is crucial to nerve-nerve communication. The ability to produce consecutive action potentials is related to the activation of inward currents after each upstroke. If fast Na current is indeed responsible for the overshoot, it is still unclear which current drives membrane voltage to the Na threshold. In this study we present evidence that in adult rat sensory neurones a dihydropyridine-sensitive Ca channel exists in addition to the well characterized L-type, or high-threshold Ca channel. During stimulated action potential trains, L-type Ca channels open during the excitation wave, whereas activity of the other dihydropyridine-sensitive Ca channel was observed primarily between action potentials. This second Ca pathway shows remarkably long openings at negative potentials after a series of positive prepulses. The nerve action potential and the repetitive firing work as a physiological Ca channel facilitation mechanism. Therefore, we suggest that this novel Ca conductance provides inward current, between two consecutive action potentials, able to modulate the frequency of neuronal bursts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050091
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  • 9
    Electronic Resource
    Electronic Resource
    Resonant frequencies and quality factors in lossy NRD cylindrical resonators (1995)
    Springer
    International journal of infrared and millimeter waves 16 (1995), S. 675-688 
    Details
    ISSN: 1572-9559
    Keywords: Dielectric Resonators ; Non-Radiative Dielectric (NRD) devices ; Resonant frequencies ; Quality factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper the fundamental effects of losses on resonant parameters (frequencies and quality factors) are analyzed for circular-cylindrical dielectric resonators inserted between metal plates, in the configuration also called NRD (Non-Radiative Dielectric). Power dissipations are considered both in the dielectric and in the conductors. Complex resonant frequencies and closed-form expressions for the relevant quality factors are derived rigorously for arbitrary resonant modes, even without circular symmetry. Numerical results are presented and discussed, making also use of experimental data obtained by means of a suitable NRD set-up. The present analysis accurately provides the basic information for a more realistic design of up-to-date millimeter-wave frequency-selective devices in NRD circuitry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02066892
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclodextrin derivatives in GC separation of racemic mixtures of volatiles. Part IX. The influence of the different polysiloxanes as diluting phase for 2,3-di-O-acetyl-6-O-t-butyldimethylsilyl-β-cyclodextrin on the separation of some racemates (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 327-336 
    Details
    ISSN: 1040-7685
    Keywords: Enantioselective GC ; 2,3-di-O-acetyl-6-O-t-butyldimethylsilyl-β-cyclodextrin ; diluting stationary phases (PS-086, OV-1701) ; retention parameters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results of a series of experiments concerning the GC enantioseparation of some racemates on columns coated with 2,3-di-O-acetyl-6-O-t-butyldimethylsilyl-β-cyclodextrin diluted in two different polysiloxanes (PS-086 and OV-1701) are reported. The investigation is centered on the influence of the diluting phase on the separations of the racemates investigated [δ-heptalactone, linalyl acetate, and an homologous series of cis-2-(2-alkyl-cyclopropyl)-ethanol (alkyl from ethyl to heptyl)] because one of the two polysiloxanes separated them, whereas the other did not. Column retention and efficiency characteristics were investigated as a function of the diluting phase. Retention increase (RI) and Gibbs-Helmholtz parameter (ΔR,SΔG) were determined for each of the above racemates, analyzed by different mixtures of the CDD selector with the two diluting phases. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220070405
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