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  • 1
    ISSN: 1432-0878
    Keywords: Key words Calcium antagonists ; Calcium channel blocker ; Cochlea ; Electron energy-loss spectroscopy (EELS) ; Electron spectroscopic imaging (ESI) ; Hair cells ; Signal transduction ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Calcium ions were precipitated with potassium antimonate after injection of the inorganic calcium channel blocker MnCl2 or the inorganic potassium channel blockers BaCl2 or CsCl into the perilymph of the scala vestibuli of the guinea pig. The spatial distribution of the formed histochemical reaction products within the organ of Corti was studied by energy-filtering transmission-electron microscopy. Compared with untreated control ears, the number of the formed precipitates drastically increased at the extracellular side of the lamina reticularis after application of the various inorganic channel blockers. The apical side of the outer hair cells and the intervening Deiter cells were covered by a thick layer of calcium precipitates, whereas the number of histochemical reaction products was clearly reduced in the nearby acellular tectorial membrane. The high calcium content within the formed reaction products at the lamina reticularis could be demonstrated by elemental mapping and by electron energy-loss spectroscopy. To ascertain the alterations in the amounts of the calcium precipitates within the tectorial membrane after application of the various inorganic channel blockers, the precipitate densities were determined semiquantitatively by an image processing system and the values obtained compared with those of untreated control specimens. The observed histochemical results are in good agreement with published electrophysiological findings concerning the spatial distribution of ion channels located at the apical outer hair cell membrane. The detected alterations in the spatial distribution of calcium precipitates might correspond to calcium-dependent processes involved in outer hair cell modulation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1618-2650
    Keywords: Trenn. von Seltenen Erden von Uran ; Photometrie ; Chromatographie, Dünnschicht ; Diäthyläther/Tetrahydrofuran/Bis-(2-äthylhexylphosphat)/HNO3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mit dem Laufmittel Diäthyläther/Bis-(2-äthylhexylphosphat) (HDEHP)/Salpetersäure (100∶1∶3,5) können alle Seltenen Erden (S.E.) dünnschicht-chromatographisch (DC-Trennung) getrennt werden. Durch Variation von HDEHP und HNO3 ist es möglich, entweder die Rf-Werte der schweren oder leichten S.E. auseinander zu ziehen. Eine weitere DC-Trennung der S.E. gelingt mit dem Laufmittel Diäthyläther/Tetrahydrofuran/HDEHP/ HNO3. Nach der DC-Trennung werden die einzelnen S.E. auf zwei Wegen quantitativ bestimmt: a) Durch Auswertung der Fleckengröße, b) photometrisch nach Abkratzen der Flecken mit Neothorin. Als Analysen-Beispiel wird die Bestimmung von S.E. im ppm-Bereich in Spilitischem Schalstein gezeigt. Die relativen Standardabweichungen sind befriedigend.
    Notes: Summary All rare earths can be separated by TLC with the eluent diethyl ether/bis-(2-ethylhexylphosphate) (HDEHP)/nitric acid (100∶1∶3.5). It is possible to increase the R f-differences between either the heavy or the light rare earths by variation of HDEHP and HNO3. A further separation can be obtained by using diethyl ether/THF/HDEHP/HNO3 as an eluent. After TLC separation the rare earths can be determined quantitatively in two ways: (a) by evaluation of spot area, (b) by photometry with Neothorin as indicator after scraping the spots. The determination of rare earths in the ppm range in spilites is shown as an example. The relative standard deviations are satisfactory.
    Type of Medium: Electronic Resource
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