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  • Articles: DFG German National Licenses  (7)
  • 2000-2004  (4)
  • 1965-1969  (3)
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  • Articles: DFG German National Licenses  (7)
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  • 1
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The recently discovered connexin29 (Cx29) was reported to be present in the central and peripheral nervous systems (CNS and PNS), and its mRNA was found in particular abundance in peripheral nerve. The expression and localization of Cx29 protein in sciatic nerve were investigated using an antibody against Cx29. The antibody recognized Cx29 in HeLa cells transfected with Cx29 cDNA, while nontransfected HeLa cells were devoid of Cx29. Immunoblotting of sciatic nerve homogenate revealed monomeric and possibly higher molecular weight forms of Cx29. These were distinguished from connexin32 (Cx32), which also is expressed in peripheral nerve. Double immunofluorescence labelling for Cx29 and Cx32 revealed only partial colocalization of the two connexins, with codistribution at intermittent, conical-shaped striations along nerve fibers. By freeze-fracture replica immunogold labelling (FRIL), Cx32 was found in gap junctions in the outermost layers of myelin, whereas Cx29-immunogold labelling was found only in the innermost layer of myelin in close association with hexagonally arranged intramembrane particle (IMP) ‘rosettes’ and gap junction-like clusters of IMPs. Although both Cx32 and Cx29 were detected in myelin of normal mice, only Cx29 was present in Schwann cell membranes in Cx32 knockout mice. The results confirm that Cx29 is a second connexin expressed in Schwann cells of sciatic nerve. In addition, Cx29 is present in distinctive IMP arrays in the inner most layer of myelin, adjacent to internodal axonal plasma membranes, where this connexin may have previously unrecognized functions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of hypoxia and phosphatase inhibitors on connexin43 (Cx43) phosphorylation state, gap junctional intercellular communication (GJIC) and immunolabelling with anti-Cx43 antibodies were investigated in cultured astrocytes. Astrocytes contained predominantly phosphorylated forms of Cx43 and these underwent dephosphorylation 30 min after hypoxia. This was preceded by a 77% reduction in GJIC 15 min after hypoxia, indicating that reduced GJIC occurs prior to Cx43 dephosphorylation. Hypoxia caused a reduction in punctate immunostaining (epitope masking) at cell–cell contacts with one anti-Cx43 antibody, and increased labelling with another antibody (13–8300) that detects only a dephosphorylated form of Cx43. Inhibition of protein phosphatase (PP)-1 and PP-2A with okadaic acid or calyculin A had little effect on hypoxia-induced Cx43 dephosphorylation. Inhibition of PP-2B (calcineurin) with cyclosporin A or FK506 reduced Cx43 dephosphorylation and junctional uncoupling seen after hypoxia. These results demonstrate that responses of astrocytic Cx43 to hypoxia in vitro are similar to those seen after ischaemia in vivo, and that inhibition of protein phosphatase protects astrocytes from hypoxia-induced Cx43 dephosphorylation and junctional uncoupling. In addition, calcineurin may play a direct role in the regulation of astrocytic GJIC and Cx43 phosphorylation state.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Brain slices prepared from adult rats and maintained for up to 3 h in vitro were used to investigate the effects of pharmacological treatments on the phosphorylation state, immunolabelling characteristics and ultrastructural localization of astrocytic gap junctions and connexin43 (Cx43). Slices deprived of glucose/oxygen to mimic ischemia or those exposed to 1 mm glutamate for 1 h exhibited Cx43 dephosphorylation, epitope masking and gap junction internalization as revealed by Western blotting and Cx43 immunolocalization with various antibodies. Treatment with 15 mm K+ caused Cx43 dephosphorylation without junction internalization. The effects of glutamate and K+ were completely blocked by the N-methyl-d-aspartate (NMDA) glutamate receptor antagonist 2-amino-5-phosphonovalerate (APV), which acts largely on neuronal NMDA receptors, suggesting neuronal mediation of glial gap junction responses to these treatments. Astrocytes contained a dephosphorylated form of Cx43 with a typical migration profile at 41 kDa as well as novel, apparently dephosphorylated or partially phosphorylated, forms migrating at 43 kDa. These results indicate that slices prepared from adult brain can serve as a convenient model to investigate the molecular basis and receptor-mediated mechanisms underlying astrocytic Cx43 responses that have been observed in vivo following cerebral ischemia or neural activation. These processes can be related in part to neuronal regulation of astrocytic gap junctional coupling state, which is also amenable to analysis in brain slices.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of legal medicine 61 (1967), S. 95-102 
    ISSN: 1437-1596
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Summary The alteration of the retina had been examined by the authors in chronic experiments at dogs. The dogs received subcutaneously a dose of 5 mg. of Nicotine per day for 18 months. The eyes and other organs of the animals were examined. The fundus of the eyes had been examined several times within the 18 months. Grave alterations were developed of fundus of the eye with little doses of Nicotine in these experiments. The most conspicuous alterations were the atrophy of retina, the smudgy of the laminas and reduction of the cellular elements of retina. Alterations were found — beside the lesions of the retina — in other organs, first of all in the blood vessels. The conclusion can be drown, that the alterations of the eyes are secondary, and are connected with disturbance of the blood supply.
    Notes: Zusammenfassung Es wurden die Veränderungen der Retina bei chronischer Nicotinvergiftung untersucht. Wir haben fünf Hunden über 18 Monate täglich 10 mg Nicotin subcutan gespritzt. Nach Tötung der Tiere wurden die Augen und auch andere Organe histologisch verarbeitet. Der Fundus wurde während der 18 Monate mehrfach untersucht. Es gelang uns, in den berichteten Experimenten mit verhältnismäßig kleinen Nicotindosen hochgradige Fundusveränderungen zu erzeugen. Die Atrophie der Retina, die Verwaschenheit ihrer Schichtung sowie die zahlenmäßige Reduktion der zelligen Elemente waren die auffallendsten Erscheinungen. Nebst den Veränderungen der Augen verdienen in anderen Organen vor allem diejenigen des vasculären Systems Erwähnung. Diese generellen Befunde lassen es vermuten, daß die schweren Veränderungen auch am Auge sekundärer Natur und durch primäre Störung der Blutversorgung bedingt sind.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 347 (1966), S. 191-198 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dielectric measurements on trimethylvinyl, allyl, and butenyl silane have shown that the vinyl silane has a structure being similar with that of trimethylphenyl silane. Where as in the latter compound, however, six electrons are on a seven-centric molecular term, the two π-electrons of the vinyl compound are on a three-centric one. In both cases the Si atom exhibites +I inductive and -M mesomeric action. The reactivity of allyl silane is due the strong M and E effect resulting from CH2 hyperconjugation and the +I effect of Si.
    Notes: Dielektrische Untersuchungen an Trimethyl-vinyl, Allyl- und Butenyl-silan zeigten, daß Vinyl-trimethyl-silan eine ähnliche Struktur wie Phenyl-trimethyl-silan besitzt mit dem Unterschied, daß die zwei π-Elektronen bei der Vinylverbindung auf ein trizentrisches, hingegen bei der Phenylverbindung sechs Elektronen auf ein heptazentrisches Molekülniveau gelangen. In beiden Fällen übt das Silicium eine +induktive (+I) und -mesomere (-M) Wirkung aus. Die Reaktionsfähigkeit der Allylverbindung ist dem stark erhöhten M- und E-Effekt zuzuschreiben, der durch den Hyperkonjugationseffekt der CH2-Gruppe und den +I-Effekt des Siliciums hervorgerufen wird.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 367 (1969), S. 293-302 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: For a general investigation on the Si—N bond N-substituted (silyl)-pyrrole derivatives have been prepared by means of already known, and new, methods. The dipole moments of these compounds were determined and their UV spectra recorded. From these data it is concluded that the Si—N bond has partial double bond, dπ-pπ, character. The lone electron pair on the nitrogen is however, displaced towards the silicon only to a small extent, owing to the stronger electron attracting effect of the pyrrole ring. These conclusions are by quantumchemical estimations.
    Notes: Für Untersuchungen über die Si—N-Bindung wurden N-substituierte Pyrrolderivate teilweise nach bekannten, z. T. nach neuen Methoden hergestellt. Es wurden Dipolmomente dieser Verbindungen nach HEDESTRAND ermittelt sowie ihre UV-Spektren aufgenommen.Dabei ergab sich, daß die Si—N-Bindung den Charakter einer partiellen Doppelbindung besitzt. Das einsame Elektronenpaar am Stickstoff ist aber nur geringfügig in Richtung der d-Bahn des Siliciumatoms verschoben; es tritt nur eine schwache dπ-pπ-Bindung auf, woraus folgt, daß der Pyrrolring wesentlich stärker elektronenanziehend wirkt als das Siliciumatom. Diese Folgerungen werden durch quantenchemische Berechnungen gestützt.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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