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  • 1
    Electronic Resource
    Electronic Resource
    Reticular facilitation of cat visual cortical responses is mediated by nicotinic and muscarinic cholinergic mechanisms (1983)
    Springer
    Experimental brain research 96 (1983), S. 1-7 
    Details
    ISSN: 1432-1106
    Keywords: Acetylcholine ; Receptor antagonists ; Area 17 ; Mesencephalic reticular formation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stimulation of the mesencephalic reticular formation facilitates responses in the visual cortex elicited from the optic radiation. Using intraveneous administration of cholinergic antagonists we investigated in adult cats and two kittens whether this effect is mediated by cholinergic mechanisms. When administered alone the muscarinic antagonists atropine and scopolamine and the nicotinic antagonist mecamylamine failed to block reticular facilitation and sometimes even enhanced the effects of reticular stimulation. However, when administered in combination muscarinic and nicotinic antagonists eliminated or significantly reduced the facilitation. This was even true when the two antagonists were administered with a time lag of several hours. These results support the notion that reticular facilitation of cortical responses is mediated by cholinergic mechanisms and suggest that this effect is mediated either by a receptor with a mixed pharmacological property or by two independent pathways acting via nicotinic and muscarinic receptors. This hypothesis is discussed in the context of recent evidence on cholinergic transmission and earlier data on the pharmacology of reticular arousal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230433
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Structures mediating cholinergic reticular facilitation of cortical responses in the cat: effects of lesions in immunocytochemically characterized projections (1983)
    Springer
    Experimental brain research 96 (1983), S. 8-18 
    Details
    ISSN: 1432-1106
    Keywords: Excitotoxin lesion ; Basal forebrain ; Area 17 ; Mesencephalic reticular formation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cholinergic afferents to the neocortex controlled by the mesencephalic reticular formation (MRF) are known to transiently facilitate cortical excitability. In an attempt to identify the pathway mediating this effect in the cat visual cortex we combined retrograde tracing techniques with immunocytochemical methods to visualize the acetylcholine-synthesizing enzyme choline acetyltransferase (ChAT). In addition we examined, in acute electrophysiological experiments, whether local neurotoxin injections into nuclei of the basal forebrain interfered with the reticular facilitation of cortical evoked potentials. Cholinergic projections to area 17 originate from different centers in the homolateral substantia innominata/internal capsule, the septal nuclei, and the nuclei of the diagonal band of Broca. No direct cholinergic projection from the MRF to the visual cortex was observed. Retrogradely labelled cells intermingled with ChAT-positive neurons in the brainstem generally revealed immunopositivity for catecholaminergic markers. Local injections of neurotoxins in the substantia innominata blocked reticular facilitation, whereas local lesions of the septal nuclei and the nuclei of the diagonal band had no effect on MRF-induced facilitation. The blockage of the reticular facilitation of cortical evoked responses after unilateral lesions of the substantia innominata was bilateral, suggesting a cooperative interaction between basal forebrain structures of the two hemispheres. The anatomical and physiological data are discussed with respect to possible mechanisms of transient brainstem influences on cortical excitability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230434
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sequential proton saturation for the heteronuclear 1D NOE experiment (1992)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 30 (1992), S. 466-475 
    Details
    ISSN: 0749-1581
    Keywords: Heteronuclear NOE ; Selective pulses ; Shaped pulses ; Sequential excitation ; Improved data accumulation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved 1D pulse sequence for detecting heteronuclear NOEs on a qualitative level is described and demonstrated. It makes use of shaped selective pulses and takes advantage of sequential perturbation of several proton resonances during one experiment and correspondingly more efficient data accumulation schemes. The method is particularly suitable for assigning quaternary carbons and for establishing connectivities between assigned molecular fragments bound to these quaternary centres.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260300603
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Low-temperature study of dynamic effects in tetramethyllimonene (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 205-211 
    Details
    ISSN: 0749-1581
    Keywords: Tetramethyllimonene ; Assignments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dynamic effects of tetramethyllimonene were studied at low temperatures. Nuclear Overhauser effects measured under optimized conditions at 223 K and the results of 2D correlation experiments allowed the identification of two conformers and the assignment of all the proton and carbon resonances. For the determination of exchange and relaxation rates the method of saturation transfer was applied. At temperatures below 223 K further dynamic effects were recognized. Structural information obtained experimentally was compared with the results of Allinger force field calculations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260280303
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational analysis of cembrenenol: Application of 1H and 13C NMR spectroscopy and of computational methods (1991)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 834-847 
    Details
    ISSN: 0749-1581
    Keywords: Cembrenenol ; Cyclic diterpene ; Conformational analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution structure of the cyclic diterpene cembrenenol was investigated. A strategy for conformational analysis is proposed which is based on computational methods and experiments to determine the structure-relevant NMR parameters. Computed and experimentally determined steady-state NOEs were compared in a first step, which served to sort out a few probable conformers. The detailed analysis of homo- and hetero-nuclear coupling information together with NOE data defining local geometries allowed, in a second step, the selection of the most probable conformation. The structure corresponds to the lowest energy structure proposed by computational methods alone. Its ring structure is in excellent agreement with the x-ray ring structure of the closely related cembrenene.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260290815
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    Paper (German National Licenses)
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