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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 777 (1996), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: Neurochemical and behavioral studies have elucidated extensive interactions between dopaminergic and cholinergic systems in brain areas associated with movement and cognition. The initial goal of these studies was to evaluate the effect of the anti-Parkinson drug dihydrexidine (DHX), a dopamine D1 full-efficacy agonist, on brain acetylcholine (ACh) release using in vivo microdialysis techniques. Moderate doses of DHX (3 and 10 mg/kg) produced approximately a 50% increase in striatal ACh release that was blocked by the D1 agonist SCH23390 (0.3 mg/kg). A higher dose of DHX (17.5 mg/kg) was less effective in raising striatal ACh, possibly due to D2 receptor activation. In frontal cortex, DHX (10 mg/kg) evoked a more robust increase in ACh release (+ 200%) that was blocked by SCH23390 (0.3 mg/kg). Since elevations in brain ACh are associated with cognitive improvement, the effectiveness of DHX in a passive avoidance model of learning and memory was also evaluated. These studies revealed a significant improvement in performance by 0.3 mg/kg DHX in scopolamine-induced amnestic rats. These results provided support for the hypothesis that DHX improves cognitive performance as a consequence of ACh release in relevant brain regions. Further, D1 agonists may have novel therapeutic potential in the treatment of dementia.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: [Disodium(2 +)][1,2-Diselena-diboranate(2 -)] ; [Tetraphenylphosphonium(1 +)][μ2-Selena-(diboranyl)boranate(1 -)] ; preparation ; SCF calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Vibrational Spectroscopic Investigation of [H3B—Se—Se—BH3]2- and [H3B-μ2-Se(B2H5)]- Crystal Structure and Theoretical Investigation of the Molecular Structure of [H3B-μ2-Se(B2H5)]-M2[H3B—Se—Se—BH3] 1 is produced by the reaction between elemental selenium and MBH4 (1 : 1) in triglyme (diglyme), under dehydrogenation. 1 reacts with an excess of B2H6 to give M[H3B-μ2-Se(B2H5)] 2 which is also formed in the reaction of THF · BH3 with 1. These reactions proceed under cleavage of the Se—Se bond and hydrogen evolution. [(C6H5)4]Br reacts with Na · 2 to form [(C6H5)4P] · 2 which crystallizes in the tetragonal space group I4 (Nr. 82). An X-ray structure determination failed because of disordering of the cation and anion. 11B, 77Se NMR shifts and 1J(11B1H) coupling constants as well as IR- and Raman spectroscopic investigations convey further structural information. Structural data of 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of Se with B3H8-, or as a bridge substituted selena derivative of B2H6.
    Notes: Bei der Reaktion zwischen elementarem Selen und MBH4 (1 : 1) (M = Na, Li) in Triglyme (Diglyme) entsteht unter Wasserstoffabspaltung M2[H3B—Se—Se—BH3] 1. Bei der Behandlung von 1 mit überschüssigem B2H6 oder THF · BH3 wird die Se—Se-Bindung gespalten und es entsteht unter erneuter Wasserstoffabspaltung M[H3B-μ2-Se(B2H5)] 2. Aus Na · 2 und [(C6H5)4P]Br entsteht [(C6H5)4P] · 2, welches tetragonal in der Raumgruppe I4 (Nr. 82) kristallisiert. Kation und Anion sind im Kristall fehlgeordnet. Strukturinformationen konnten aus den 11B-, 77Se- und 1J(11B1H)-Daten einerseits und den IR- und Raman-spektroskopischen Untersuchungen andererseits erhalten werden. Aus SCF-Rechnungen erhielten wir die Strukturparameter für das Anion 2. 2 kann sowohl als Addukt von Se an B3H8- als auch als brückensubstituiertes Selena-Derivat des B2H6 aufgefaßt werden.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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