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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Members of the mytilus inhibitory peptide (MIP) family play an important role in the modulation of many physiological processes in molluscs. The signal transduction pathways affected by the MIP effect have not, however, been elucidated. Application of guanosine 5′-[γ-thio]triphosphate tetralithium salt (GTPγS), guanosine 5′-[β-thio]diphosphate trilithium salt (GDPβS), the G-protein inhibitor suramin and pertussis toxin (PTX) demonstrated the involvement of the PTX-insensitive G-protein in the signal transduction pathway mediating MIP effects. Both G-protein αi and βγ subunits were identified in D-neurons of Helix pomatia by immunoblotting. Their role in signal transduction was shown in electrophysiological experiments, which supported the notion that, in addition to the Gα subunit, the βγ dimer also participates in the neuropeptide-induced activation of K-channels in snail neurons. Finally, neuropeptide-activated responses were inhibited by the activation of adenylyl cyclase and by blockers of the phospholipase pathway. We suggest that bifurcation of the signal transduction takes place at the level of G-protein subunits. The α subunit may have a direct effect on adenylyl cyclase, while the βγ subunit may have a direct effect on phospholipase enzymes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 399 (1983), S. 302-308 
    ISSN: 1432-2013
    Keywords: Neuroblastoma cell ; Patch clamp ; Single sodium channel ; Multiple open states
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Single sodium channel currents were studied in mouse neuroblastoma cells. Channel conductance (γ) was 11.6±3.4 pS at 6–8°C. Unitary current amplitudes and channel activity increased with increasing temperature. The Arrhenius plot of the conductance was linear between 5 and 35°C with an activation enthalpy of 27.1 kJ/mole (Q 10 =1.28). Amplitude distributions were fitted by the sum of two Gaussian functions indicating the presence of two different single channel amplitudes: smalleri 1 and largeri 2. The relative probability of appearance ofi 1, which has a shorter mean open time, was higher during the early phase of depolarization (t〈16 ms). The open time histograms, inactivating phase of macroscopic currents and delay time histograms were fitted by the sum of two exponentials. The distinct kinetic and steady-state parameters reflect two open states of sodium channels.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 64 (1975), S. 471-476 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The advantages of the employment of an ethanolamine medium for the carrying-out of chelatometric titrations with catalytic-thermometric endpoint indication are shown. The direct titration of DCTA, EDTA and NTA with manganese(II) sulfate, the inverse titration of manganese(II) against these chelate-formers, and likewise the determination of a series of metal ions (alkaline earths, Zn2+, Cd2+, Mn2+, Pb2+, Hg2+, Tl3+, Al3+, Ga4+, Cu2+, In3+, Th4+) by backtitration of an excess of DCTA or EDTA with manganese(II)-standard solution is described. The catalytic decomposition of hydrogen peroxide by manganese (II) may be employed more effectively as indicator reaction in ethanolamine medium than in water or in dimethylsulfoxide. The above-named ions can be determined in milligram- and microgram range with satisfactory accuracy.
    Abstract: Résumé Les avantages de l'application du milieu éthanolaminique pour les titrages chélatométriques et pour la détection catalytique-thermométrique du point final sont indiqués. Les titrages directs des DCTA, EDTA et NTA avec le manganèse(II), les titrages inverses du manganèse(II) avec ces complexeurs ainsi que le dosage de plusieurs ions métalliques (alcalino-terreux, Zn2+, Cd2+, Mn2+, Pb2+, Hg2+, Tl3+, Tl+, Al3+, Ga4+, Cu2+, In3+, Th4+) par les titrages en retour de l'excès de DCTA et d'EDTA avec la solution standard de manganèse(II) sont décrites. La décomposition du peroxyde d'hydrogène catalysée par le manganèse(II) peut être utilisée comme réaction indicatrice dans ce solvant plus efficacement que dans l'eau ou dans le diméthylsulfoxyde. Les ions mentionnés peuvent être dosés soit dans le domaine des milligrammes soit dans celui des microgrammes avec une précision raisonnable.
    Notes: Zusammenfassung Die Vorteile der Anwendung eines Äthanolamin-Mediums zur Ausführung chelatometrischer Titrationen mit katalytisch-thermometrischer Endpunktindikationen werden aufgezeigt. Die direkte Titration von DCTA, ÄDTA und NTA mit Mangan(II), die inverse Titration von Mangan(II) gegen diese Chelatbildner wie auch die Bestimmung einer Reihe von Metallionen (Erdalkalien, Zn2+, Cd2+, Mn2+, Pb2+, Hg2+, Tl3+, Tl+, Al3+, Ga4+, Cu2+, In3+, Th4+) durch Rücktitration eines Überschusses an DCTA oder ÄDTA mit Mangan (II)-Maßlösung werden beschrieben. Als Indikatorreaktion konnte in diesem Medium die von Mangan(II) katalysierte Zersetzung von Wasserstoffperoxid effektiver angewandt werden als in Wasser oder in Dimethylsulfoxid. Die obengenannten Ionen können im Milligramm- und Mikrogrammbereich mit befriedigender Genauigkeit bestimmt werden.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The formation of a complex prevents the iodide oxidation by Cu(II) in the presence of ammonia, sodium tartrate, citrate, or oxalate. Hence mercury(II) for instance, can be masked against potassium iodide in the presence of these complex formers, and Cu(II) can be determined by direct titration with EDTA in the presence of murexide, pyrocatechol violet, chromazurol, PAN or PAR as indicator.
    Notes: Zusammenfassung Die Jodidoxydation durch Cu(II) wird in Anwesenheit von Ammoniak, Natriumtartrat, citrat oder -oxalat infolge Komplexbildung verhindert. Daher kann man z. B. Quecksüber(II) in Anwesenheit der genannten Komplexbildner mit Kaliumjodid maskieren und Kupfer(II) durch direkte Titration mit ÄDTA gegen Murexid, Brenzcatechinviolett, Chromazurol S, PAN oder PAR als Indikator bestimmen.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The application of several oxidation reactions with hydrogen peroxide as exothermic indication reactions to catalytic thermometric end-point detection of chelatometric titrations is described. This time the oxidations of resorcinol and catechol, both catalyzed by copper(II), as well as the oxidations of hydroquinone and dimethyl-p-phenylenediamine, both catalyzed by copper(II) and iron(III), have been used as indicator systems. The titrations of EDTA, DCTA and NTA with copper(II) and iron(III), the invers titration of these metals, as well as the determination of a number of metal ions (alkaline earth metals, Cu2+, Ni2+, Co2+, Zn2+, Sn2+, Fe3+, A13+, Cr3+, Sb3+, In3+, Ga3+ and Th4+) by backand substitution titrations have been developed. The ions mentioned can thus be determined in the milligram and in the microgram range with reasonable accuracy.
    Notes: Zusammenfassung Die Anwendung einiger Wasserstoffperoxid-Oxydationen als exotherme Indikatorreaktionen bei der katalytisch-thermometrischen Endpunktanzeige chelatometrischer Bestimmungen wird gezeigt. Diesmal wurden die durch Kupfer(II) katalysierten Oxydationen von Resorcin und Brenzcatechin, wie auch die durch Kupfer(II) und Eisen(III) katalysierbaren Oxydationsprozesse von Hydrochinon und Dimethyl-p-phenylendiamin herangezogen. Die direkte Titration von ÄDTA, DCTA und NTA mit Kupfer(II) und Eisen (III), die inverse Titration dieser Metalle sowie die Bestimmungen einer Reihe von Metallionen [Erdalkalien, Cu2+, Ni2+, Co2+, Zn2+, Sn(II)2+, Fe3+, A13+, Cr3+, Sb3+, In3+, Ga3+, Th(IV)4+] durch Substitutionsund Rücktitrationen wird beschrieben. Die genannten Ionen können im Milligrammund Mikrogrammbereich mit befriedigender Genauigkeit bestimmt werden.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 56 (1968), S. 1102-1105 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A macro- and micro-titrimetric method has been developed for the determination of magnesium with EDTA in 60% ethanolic solution using methylthymol blue as indicator. The use of ethanol sharpens the color change, the blocking of the indicator by traces of copper is eliminated, and the results improved.
    Notes: Zusammenfassung Eine makro- und mikrotitrimetrische Methode zur Bestimmung von Magnesium mit ÄDTA in 60%iger äthanolischer Lösung gegen Methylthymolblau wurde ausgearbeitet. Durch Anwendung von Äthanol wird der Farbwechsel verschärft, die Indikatorblockierung durch Spuren von Kupfer(II) beseitigt und die Ergebnisse verbessert.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The application of the decomposition of hydrogen peroxide as exothermic indicator reaction catalyzed by lead(II) and copper(II), to catalytic thermometric endpoint detection of chelatometric titrations is described. The catalytic action of lead(II) is applied in ammonia-ammonium tartrate solution (pH 12), the action of copper(II) in ammonium carbonate (pH 8.8), sodium hydroxide-sodium carbonate (pH 10) and in ammoniacal medium (pH 12). The direct titration of EDTA, DCTA and NTA with copper(II) and lead(II), the invers titration of this metals, as well as the determination of several ions (Zn2+, Cd2+, Cu2+, Ni2+, Pb2+, Bi3+, In3+, Th4+) by backtitration has been developed. The ions mentioned can be determined in the milligram and in the microgram range with reasonable accuracy.
    Notes: Zusammenfassung Die Anwendung der durch Blei(II) und Kupfer(II) katalysierten Zersetzung von Wasserstoffperoxid als exotherme Indikatorreaktion bei katalytisch-thermometrischer Endpunktindikation chelatometrischer Bestimmungen wird gezeigt. Die katalytische Wirkung von Blei(II) wird in ammoniak-ammoniumtartrathaltiger Lösung (pH 12) und die Wirkung von Kupfer(II) in ammoniumcarbonathaltigem (pH 8,8), natriumhydroxid-natriumcarbonathaltigem (pH 10) und in ammoniakalischem Medium herangezogen. Die direkte Titration von ÄDTA, DCTA und NTA mit Kupfer(II) und Blei(II), die inverse Titration dieser Metalle, wie auch die Bestimmung einiger Metallionen (Zn2+, Cd2+, Cu2+, Ni2+, Pb2+, Bi3+, In3+, Th4+) durch Rücktitration wird beschrieben. Die genannten Ionen können im Milligramm- und Mikrogrammbereich mit befriedigender Genauigkeit bestimmt werden.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 14 (1994), S. 781-789 
    ISSN: 1573-6830
    Keywords: excitable membrane ; ionic channel ; heavy metal ; metal ion-induced current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The paper summarizes the effects of the metal ions Cu2+, Pb2+, Ag+, Hg2+, Zn2+, and Cd2+ applied externally or internally to the surface membrane of different excitable cells. 2. Conductance changes induced by metal ions, and metal ion-activated current, are compared with respect to their ion and voltage dependence. 3. It is suggested that metal ion-induced effects can be realized through special structures of the cell membrane, the metal ion “receptors,” although other mechanisms, as, for example, competition for Ca-binding sites in the channel forming proteins, cannot be excluded.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Complexometric methods have been developed for determining zinc in the presence of palladium(II). In these procedures, Pa(II) is masked with potassium cyanide and the zinc content is titrated either at pH 5.8 or after demasking with chloralhydrate is titrated with EDTA at pH 10 in the presence of methylthymol blue. This zinc determination may also be conducted in the presence of a mixture of palladium(II), copper(II), nickel(II),and cobalt(II).
    Notes: Zusammenfassung Komplexometrische Methoden zur Bestimmung von Zink in Gegenwart von Palladium(II) wurden ausgearbeitet. Dabei wird Palladium(II) mit Kaliumcyanid getarnt und der Zinkgehalt entweder bei pH 5,8 oder nach Demaskierung mit Chloralhydrat bei pH 10 mit ÄDTA gegen Methylthymolblau titriert. Diese Zinkbestimmung läßt sich auch in Anwesenheit einer Mischung von Palladium(II), Kupfer(II), Nickel und Kobalt(II) durchführen.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 208 (1965), S. 334-337 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The “deblocking” of metal indicators in chelometric titrations in the presence of organic solvents has been studied. As examples the titrations of cobalt, iron(III), copper, nickel and aluminium have been performed in the presence of the organic solvents mentioned in the table. The sample solution was mixed with an excess of EDTA solution and backtitrated with Eriochrome Black T as an indicator. It has been tried to elucidate the effect of the organic solvents on the titration.
    Notes: Zusammenfassung Eine Studie über die Deblockierung von Metallindicatoren bei chelometrischen Titrationen in Gegenwart von organischen Lösungsmitteln wurde unternommen. Als Beispiele dienten die Bestimmungen von Kobalt, Eisen(III), Kupfer, Mckel und Aluminium in Gegenwart der in der Tabelle angegebenen organischen Lösungsmittel. Dazu versetzte man mit überschüssiger ÄDTA-Lösung und titrierte gegen Eriochromschwarz T als Indicator zurück. Eine Erklärung des Einflusses der organischen Lösungsmittel auf den Titrationsverlauf wurde versucht.
    Type of Medium: Electronic Resource
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