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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 555 (1979), S. 460-471 
    ISSN: 0005-2736
    Keywords: (Fluorescence polarization) ; Acetylcholine receptor ; Chromaffin cell ; Lipid bilayer fluidity ; Membrane depolarization
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 466 (1977), S. 373-378 
    ISSN: 0005-2736
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Changes in plasma membrane potential of isolated bovine adrenal chromaffin cells were measured independently by two chemical probe methods and related to corresponding effects on catecholamine secretion. The lipophilic cation tetraphenylphosphonium (TPP+) and the carbocyanine dye 3,3′-dipropylthiadicarbocyanine [DiS-C3-(5)] were used. The necessity of evaluating the subcellular distribution of TPP+ among cytoplasmic, mitochondrial, secretory granule, and bound compartments was demonstrated and the resting plasma membrane potential determined to be – 55 mV. The relationship between membrane potential and catecholamine secretion was determined in response to variations in extracellular K+ and to the presence of several secretagogues including cholinergic receptor ligands, veratridine, and ionophores for Na+ and K+. The dependence of potential on K+ concentration fit the Goldman constant field equation with a Na/K permeability ratio of 0.1. The dependence of both K+ - and veratridine-evoked catecholamine secretion on membrane potential exhibited a potential threshold of about – 40 mV before a significant rise in secretion occurred. This is likely related to the threshold for opening of voltage-sensitive Ca2+ channels. Acetylcholine and nicotine evoked a large secretory response without a sufficiently sustained depolarization to be detectable by the relatively slow potential sensitive chemical probes. Decamethonium induced a detectable depolarization of the chromaffin cells. Veratridine and gramicidin evoked both membrane depolarization and catecholamine release. By contrast the K ionophore valinomycin evoked significant levels of secretion without any depolarization. This is consistent with its utilization of an intracellular source of Ca2+ and the independence of its measured secretory response on extracellular Ca2+
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0014-5793
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Radiation and environmental biophysics 26 (1987), S. 189-195 
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary 125I incorporated in DNA is known to be exceptionally toxic. Values of D0 range from about 40 to about 90 decays for survival of mammalian cells. The effectiveness of125I in DNA with respect to the induction of breaks of the DNA strands, however, appears to be comparatively low. The numbers of strand breaks per energy deposited in subnuclear cellular structures such as DNA is smaller for a disintegration of125I than forγ-rays. The difference in effectiveness diminishes with increasing mass of the considered sensitive volume. The apparent inefficiency of125I-decay may, on one hand, result from a waste of local energy deposition. On the other hand, it may be caused by a multitude of local strand breaks (clusters) induced by125I-decay which are measured as one break only by the conventionally applied techniques of strand break measurement. The apparent inefficiency of125I may be evidence furthermore for the importance of considering not only the DNA as the sensitive target but with equal pertinence the gross sensitive volume, i.e. the whole cell nucleus [12]. Further, for drawing meaningful comparisons, it may be necessary to take into consideration the microdosimetric event size distributions for the critical targets [1].
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Radiation and environmental biophysics 7 (1970), S. 40-46 
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Description / Table of Contents: Zusammenfassung Die von anderen Autoren berichtete Verbesserung der Reparatur vonγ-Strahlenschäden an Tieren und Pflanzen durch Procainhydrochlorid (p-Aminobenzoesäure-β-diäthylaminoäthylester) konnte anE. coli nicht bestätigt werden. Alle Dosiswirkungskurven im Bereich bis zu 30 krad zeigten mit und ohne Procainhydrochlorid in Konzentrationen von 0,01–10 mM/l Agar gleiche Überlebensraten. Bei Konzentrationen von mehr als 1 mM/l Agar ergab sich eine mit der Konzentration zunehmende Wachstumshemmung, die sich jedoch auf die Überlebenschancen nach derγ-Bestrahlung nicht auswirkte. Procainhydrochlorid im Bestrahlungsmedium übte ebenfalls keinen Einfluß auf den Strahlenschaden aus. Insgesamt wurden über 200.000 Bakterienkolonien ausgezählt, um eine gute statistische Auswertung zu sichern.
    Notes: Summary The improved repair ofγ-ray damage in animals and plants which was reported by other authors who had applied procaine hydrochloride, could not be confirmed on bacteriaE. coli. All survival curves up toγ-ray doses of 30 krad, showed equal survival chances with or without addition of procaine hydrochloride in concentrations of 0.01–10 mmoles/l agar. Concentrations of more than 1 mmole cause growth inhibition, although this does not influence at all the surviving number of bacteria. Also the presence of procaine during irradiation in the phosphate buffer suspension has no effect on survival chances. The research was carried out with a total of more than 200000 registrated colonies to assure good statistics.
    Type of Medium: Electronic Resource
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