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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 284 (1974), S. 195-206 
    ISSN: 1432-1912
    Keywords: Diazepam ; Tyrosine Hydroxylase ; Isoproterenol ; Reserpine ; 6-Hydroxydopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The increase in in vitro adrenal tyrosine hydroxylase (TH) activity caused by drugs which produce an increase in preganglionic nerve activity as a result of actions outside the central nervous system was increased by the administration of diazepam. However, other central nervous system depressants such as pentobarbital, phenobarbital and diphenylhydantion were not found to share this property. Adrenal enzyme induction provoked by isoproterenol and 6-hydroxydopamine was increased by diazepam administration, whereas that produced by reserpine or insulin was not altered. The enhanced adrenal TH activity produced by diazepam pretreatment and isoproterenol administration could not be attributed to an increase in intensity or to an altered body temperature. Administration of 5-hydroxytryptophan can antagonize the induction of adrenal TH produced by isoproterenol, however, it did not block the TH induction produced by concurrent administration of diazepam and isoproterenol. The effect of diazepam on adrenal TH induction may be the result of its ability to interfere with central nervous system amine containing nerve functions which modulate preganglionic nerve activity, but the particular neurotransmitter system involved has not been determined.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Key words Calcium ; Contraction ; Electrophysiology ; Guinea-pig ; pH ; Potassium ; Ureter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Guinea-pig ureteric smooth muscle is unusual in that intracellular acidification increases and alkalinization decreases force production. To help elucidate the mechanism underlying these effects on force we have investigated the effects of changing intracellular pH on both calcium and potassium currents in single cells isolated from the guinea-pig ureter to determine their possible role in force development. Depolarization to +40 mV resulted in a fast transient outward current which was inhibited by 4-aminopyridine but not tetraethylammonium. Intracellular alkalinization (20 mM trimethylamine) increased this current to 179 ± 24% of the control and resulted in the development of a slowly activating large outward current which was inhibited by tetraethylammonium and washout. Acidification (40 mM sodium butyrate) decreased the fast transient outward current to 58 ± 3% of the control and did not produce a slowly activating current. When potassium was replaced by caesium in the pipette solution, depolarization to 0 mV resulted in an inward calcium current which was abolished by nifedipine. Intracellular alkalinization increased this current to 126 ± 11% of the control whereas acidification had the opposite effect, decreasing it to 55 ± 10%. Furthermore, current-clamp experiments showed that intracellular alkalinization inhibited the amplitude of the action potential, therefore decreasing excitability of the cell. From our results, we suggest that the predominant effects of intracellular pH on force production in the guinea-pig ureter are mediated via the modulation of outward potassium currents (thereby reducing excitability of the tissue) rather than the effects on the inward calcium current.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylidendicarbonitril (Vinylidencyanid) zeigt bei radikalisch gestarteter Copolymerisation eine viel stärkere Neigung zur Bildung von alternierend aufgebauten 1:1-Copolymeren als Acrylnitril. Während Polyvinylidencyanid trotz der molekularen Symmetrie nicht kristallisiert, sind alternierende Copolymere, vor allem mit Butadien, Isopren, Isobutylen und Vinylidenchlorid, leicht kristallisierbar. Aus höherschmelzenden Copolymeren wurden Fasern hergestellt und auf ihre physikalischen Eigenschaften geprüft. Besonders Fasern aus den Copolymeren mit Vinylacetat und Vinylchlorid zeigen im nassen und im trockenen Zustand ein hervorragendes elastisches Verhalten. Die Faser aus dem alternierend aufgebauten Copolymeren von Vinylidencyanid und Vinylacetat (Darvan®-Nytrilfaser) ist nur mäßig orientiert und zeichnet sich durch Weichheit, gute elastische Erholung und Sprungelastizität im trockenen und nassen Zustand aus.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0570-0833
    Keywords: Copolymers ; Fibers ; Vinylidenedicarbonitrile ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyldendicarbonitrile (Vinylidene cyanide) on free redical catalyzed copolymerization shows a much stronger tendency to form 1:1 alternating copolymers than acrylonitrile. While bulk poly(vinylidene cyanide) fails to crystallize, despite its molecular symmetry, several alternating copolymers are readily crystallizable, notably those containing butadiene, isoprene, isobutylene, or vinylidene chloride. Fibers have been prepared from a number of the higher melting copolymers and examined for physical properties. Fibers from the vinyl acetate and vinyl chloride copolymers show expectional elastic behavior both when dry and wet. The fiber from the vinylidene cyanide |vinyl acetate alternating copolymer (Darvan® nytril fiber) is only moderately oriented and is characterized by exceptional softness and excellent elastic recovery and resilience, both when dry and wet.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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