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  • 1
    Electronic Resource
    Electronic Resource
    Intracellular localization, vesicular accumulation and kinetics of daunorubicin in sensitive and multidrug-resistant gastric carcinoma EPG85-257 cells (1995)
    Springer
    Virchows Archiv 426 (1995), S. 249-256 
    Details
    ISSN: 1432-2307
    Keywords: P-Glycoprotein ; Multidrug resistance ; Vesicle formation ; Daunorubicin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the human gastric carcinoma cell line EPG85-257P (parent) induction of resistance to daunorubicin (DAU) was achieved by selection with stepwise increased concentrations of the drug. The new vairant was named EPG85-257DAU and was shown to overexpress the mdr1 gene product 170 kDa P-glycoprotein (P-Gp) as demonstrated by immunocytochemistry and mdr1-specific RT-PCR. To investigate the intracellular pathway of DAU the subcellular distribution of this autofluorescent drug was studied in the resistant cells and compared to its chemosensitive counterpart EPG85-257P. When sensitive cells were exposed to DAU the drug rapidly accumulated in the nucleus until cell death. No redistribution of DAU to the cytoplasm was observed. In resistant cells exposed to the drug DAU also accumulated in the nucleus but to a lesser extent than in parent cells. Following exposure, nuclear fluorescence was observed to decrease over a time period of up to 48 h. Six hours after DAU exposure formation of fluorescent vesicle formation started in the perinuclear region and increased continously. After 48 h nuclear fluorescence was no longer detectable and DAU was located exclusively in vesicles. During this period the vesicles moved from the region of origin to the cell periphery. A pulse chase experiment showed, that vesicles may contain DAU derived from the nucleus. Treatment of EPG85-257DAU cells with DAU in conjunction with the chemosensitizer cyclosporin A (CsA) increased nuclear fluorescence without impairing vesicle formation. Disruption of microtubules by nocodazole led to an accumulation of vesicles in the perinuclear region indicating that microtubules are involved in vesicular transport. Treatment of EPG85-257DAU cells with the actin disruptor cytochalasin B led to accumulation of vesicles in the cell periphery indicating that actin may be involved in exocytosis. Uptake and efflux of DAU and rhodamin (RH) were determined in sensitive and resistant cells using a fluorescence activated cell sorter. Uptake of both compounds was distinctly lower in resistant than in sensitive cells. When resistant cells preloaded for 2 h with RH subsequently were incubated in drug free medium the substance was rapidly released indicating transmembrane transport by P-Gp. In contrast, despite expression of P-Gp in resistant cells no considerable release of DAU was observed for up to 2 h under the same experimental protocol. This indicates that in resistant cells intracellular DAU at least in part may be inaccessible for P-Gp and that vesicular drug transport appears to contribute to DAU resistance by removing intracellular DAU via exocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191362
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  • 2
    Electronic Resource
    Electronic Resource
    Untersuchungen zu den Sondeneigenschaften von 7-Hydroxy-cumarinen in micellarer Cetyl-triethyl-ammoniumbromid-Lösung - Hilfsmittel zur Beschreibung von micellaren Systemen (1986)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 558-566 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigation on Probe Properties of 7-Hydroxy-coumarines in Micellar Cetyl-triethyl-ammoniumbromide Solution - Means for Characterization of Micellar SystemsAnions of 3-substituted 7-hydroxy-coumarines (1a-c) as fluorescence probes have been studied in this work. Acid-base equilibria in water and micellar solution of cetyl-triethylammoniumbromide (cmc = 0,72 mmol l-1), fluorescence properties and fluorescence quenching by octacyano-molybdate-IV have been investigated. It has been confirmed that probe and quencher are completely micellized. Fluorescence life times and quenching constants per one quencher molecule in the micell of about 108 s-1 have been determined. The kinetics of saponification of the probe 3-acetyl-7-hydroxy-coumarine at pH = 12 in micellar solution has been followed by probe fluorescence.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19863280415
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  • 3
    Electronic Resource
    Electronic Resource
    Conjugation reactions of polyaromatic quinones to mono- and bisglutathionyl adducts: Direct analysis by fast atom bombardment mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 329-332 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conjugation products of several reactive quinones with glutathione have been identified by fast atom bombardment mass spectrometry. Appropriate conditions have been developed which enabled the direct, dynamic mass spectral analysis of spontaneous, as well as glutathione transferase catalysed conjugation reactions. Applications to a series of quinones provided the direct detection and differentiation of the formation of mono- and bisglutathionyl adducts between regioisomeric quinone substrates in that only 1,4-quinones yielded bisglutathionyl adducts, which were not observed for the 1,2-isomers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150605
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  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen an elektronenleitenden Oxidsystemen. XXI. Stabile spinelle ZnzNiMn2-zO4 und Vergleich mit Spinellen MgzNiMn2-zO4 (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 608 (1992), S. 166-172 
    Details
    ISSN: 0044-2313
    Keywords: Spinel ; zinc, nickel manganite spinel ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Electronically Conducting Oxide Systems. XXI [1] Stable Spinels ZnzNiMn2-zO4 and Comparison with Spinels MgzNiMn2-zO4Stable spinels are obtained in the result of substitution of ZnII for manganese in the series ZnzII NiIIMnzIVMn2-2zIIIO4 (O ≤ z ≤1). Different from spinels MgzII NiIIMnzIVMn2-2zIIIO4 (O ≤ z ≤1)they don't be submitted to decomposition in air during slow cooling at medium temperatures. ZnNiMnO4 (z=1) could not be prepared in a mono-phase state which is indicated by the composition of ZnNiMnO3.96 deduced from analysis by oxidimetric titration. The comparably small variation of the specific electrical conductivity and of the activation energy observed in the range O ≤ z ≤ 2/3 for ZnzNiMn2-z is discussed in relation to larger alterations in the series MgzNiMn2-zO4. Structural interpretation is proposed based on the comparison of the molar volume of spinels M Mn2O4 (M: Mn, Fe, Co, Ni, Cu, Zn, Mg).
    Notes: Die Substitution von ZnII anstelle von Mangan in der reihe ZnzII NiIIMnzIVMn2-2zIIIO4 (O ≤ z ≤1)ergibt stabile Spinelle, die im Unterschied zu Spinellen MgzIINiIIMnzIVMn2-2zIIIO4 (O ≤ z ≤1) beim langsamen Abkühlen im mittleren Temperaturbereich nicht dem Zerfall unter Sauerstoffaufnahme unterliegen. ZnNiMnO4 (z=1) konnte nach Bestimmung der mittleren Oxydationsstufe des Mangans nur in der Zusammensetzung ZnNiMnO3,96 und damit nicht völlig phasenrein erhalten werden. Die im Bereich O ≤ z ≤ 2/3 relativ geringe Änderung der spezifischen Leitfähigkeit und der Aktivierungsenergie wird im Vergleich mit einer stärkeren Variation der Eigenschaften in der Substitutionsreihe MgzNiMn2-zO4 diskutiert und im Zusammenhang mit einer Betrachtung der Molvolumina von M Mn2O4-Spinellen (M:Mn, fe, Co, Ni, Cu, Zn, Mg) strukturchemisch interpretiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926080225
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Wirkung kationischer Tenside auf das Spektrale Verhalten des sauren Triphenylmethanfarbstoffs Pentachrom Azurblau2″,6″-Dichlor-3,3′-dimethyl-4′-hydroxy-fuchson-5,5′-dicarbonsäure und seiner Metall-(III)-Komplexe - Micelleffekt oder ternäre Komplexbildung?Herrn Prof. Dr. Dr. h. c. H. G. O. Becker zum 60. Geburtstag gewidmet (1982)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 324 (1982), S. 299-308 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Effect of Cationic Detergents on the Spectral Properties of Pontachrome Azur blue and its Metal(III)-complexes - Micell Effect or Ternary Complex Formation?The results of studies of the metachromasy effect of pontachrome azur blue and its lakes, preferably with aluminium, and hexadecyl-, tetradecyl-, dodecyl- and decyltriethyl-ammonium-bromide, respectively can be explained on the basis of ternary complex formation. The surfactants can be applied at concentrations far below its critical micelle concentrations thus excluding micelle effects.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19823240214
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