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  • Polymer and Materials Science  (37)
  • Life and Medical Sciences  (26)
  • Chemical Engineering  (13)
  • Inorganic Chemistry  (12)
  • General Chemistry  (9)
  • Organic Chemistry  (5)
  • brain  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 2 (1982), S. 193-204 
    ISSN: 1573-6830
    Keywords: adenosine ; catecholamines ; neurotransmission ; calcium ; brain ; striatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Adenosine analogues inhibit calcium-dependent K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical and hippocampal vesicular preparations. Inhibition requires high concentrations (100µM) of the adenosine analogues and is abolished in the presence of high concentrations (2 mM) of calcium ions. The inhibitory effect of 2-chloroadenosine is blocked by theophylline. The structure activity profile (N 6-d-phenylisopropyladenosine ≥N 6-l-phenylisopropyladenosine ≥ 2-chloroadenosine 〉N 6-cyclohexyladenosine, adenosine 5′-cyclopropylcar-boxamide) is not that expected of either A1 (high-affinity) or A2 (low-affinity) adenosine receptors. 2. Calcium-dependent K+-evoked release of [3H]dopamine from guinea pig striatal vesicular preparations is inhibited by apomorphine. However, only 2-chloroadenoine causes an inhibition of K+-evoked release of [3H]dopamine. Other adenosine analogues such asd- andl-phenylisopropyladenosine and adenosine 5′-cyclopropylcar-boxamide cause a facilitation of K+-evoked release. The facilitation is abolished or reduced in the presence of high concentrations (2 mM) of calcium ions. The sites of action of adenosine analogues do not appear to have structural requirements identical to those expected of A1 (high-affinity) or A2 (low-affinity) adenosine receptors. 3. The results indicate that adenosine analogues can have either inhibitory or facilitory effects on K+-evoked release of catecholamines from central synaptic terminals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6830
    Keywords: adenylate cyclase ; catecholamines ; adrenergic receptors ; cyclic AMP ; phosphodiesterase ; neurotransmission ; calcium ; brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The calcium-dependent K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical vesicular preparations is inhibited by norepinephrine, clonidine, and epinephrine. Isoproterenol has no effect and phentolamine prevents the inhibition by norepinephrine. The results indicate that anα-adrenergic receptor mediates an inhibitory input to the calcium-dependent release process. The inhibition by norepinephrine is prevented by high concentrations (3.0 mM) of calcium ions. 2. A cyclic AMP phosphodiesterase inhibitor, ZK 62771, slightly elevates [3H]cyclic AMP levels in the guinea pig cerebral cortical preparation and potentiates the marked elevation of [3H]cyclic AMP elicited by the adenylate cyclase activator, forskolin. 3. Neither ZK 62771 nor forskolin alone has significant effects on K+-evoked release of [3H]norepinephrine from the cerebral cortical vesicular preparation; however, a combination of ZK 62771 and forskolin inhibits K+-evoked release by as much as 60%. The inhibition is reversed by high concentrations (2.0 mM) of calcium ions. The results suggest that a marked accumulation of cyclic AMP elicited via both activation of adenylate cyclase and inhibition of phosphodiesterase can be inhibitory to neurotransmitter release from central synaptic terminals.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 2 (1982), S. 205-213 
    ISSN: 1573-6830
    Keywords: calcium ; catecholamines ; neurotransmission ; brain ; striatum ; calcium antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The calcium antagonists D-600 (1–10µM) and diltiazem (10–25µM) inhibit K+-evoked release of [3H]norepinephrine from guinea pig cerebral cortical vesicular preparations. The inhibition of release is partially reversed by increasing concentrations of calcium to 2 mM. Diltiazem at 100µM has no effect on K+-evoked release of [3H]norepinephrine at 0.15 mM calcium but does inhibit release at 2.0 mM calcium. 2. The calcium antagonist nifedipine and dantrolene, an agent purported to antagonize release of calcium from intracellular storage sites, have no effect on K+-evoked release of [3H]norepinephrine. 3. The calcium antagonists D-600 (1µM) and diltiazem (10µM) inhibit K+-evoked release of [3H]dopamine from guinea pig striatal vesicular preparations. Higher concentrations of drug, namely, 10µM for D-600 and 100µM for diltiazem, cause a potentiation rather than an inhibition of K+-evoked release. The potentiation is reduced in magnitude upon raising the extracellular calcium to 2.0 mM. Indeed, 10µM D-600 then inhibits K+-evoked release of [3H]dopamine. 4. The results indicate that putative calcium antagonists can have both inhibitory and facilitory effects on calcium-dependent K+-evoked release of catecholamines from central synaptic endings. Furthermore, certain peripheral calcium antagonists such as nifedipine and dantrolene may prove ineffective in central systems.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 1743-1751 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some benzobarrelenes were studied by photoelectron (PE.) spectroscopy. The results can be interpreted by considering dominant through-space interaction of the π-molecular fragments in a Möbius-fashion, Some chemical features of the substrates are rationalized on the basis of these findings.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2085-2090 
    ISSN: 0009-2940
    Keywords: 5H-Dibenz[c,e]azepines ; Imidates ; alkyl ; heterocyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocycles with an Azaallyl System, 4.  -  5H-Dibenz[c,e]azepines with Donor Groups at the 7-Position5H-Dibenz[c,e]azepines substituted with a methoxy (1) or methylthio group (10) at the 7-position have been synthesized from 6,7-dihydro-5H-dibenz[c,e]azepin-5-one (5) by regioselective O- or S-alkylation with methyl trifluoromethansulfonate and subsequent NH-deprotonation. According to the spectroscopic properties the semicyclic 7-membered alkyl imidates exist exclusively in the benzenoid 5H structure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 8 (1925), S. 490-500 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rearrangements of 4′-methoxy-N-methyl- and N-methyl-4′-nitro-diatzoaminobenzene have been studied in 20% acetonitrile/aqueous buffers. The reactions are specifically acid catalyzed and involve pre-equilibrium formation of amine and diazonium salt followed by rate-limiting attack of the diazonium ion at a C-atom (C-coupling) to give the corresponding aminoazo compounds. There is no evidence to suggest that, under the present conditions, mechanisms other than the established Friswell-Green mechanism occur. The traditional two-stage synthesis of aminoazo compounds via isolated diazoamino compounds can therefore be replaced by a one stage process for amines which undergo initial attack at a N-atom by diazonium ion (N-coupling).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 407-415 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transport processes in plasticized PVC membranes containing the H+ chromoionophore ETH 5294 and additional tetraphenylborate-type mobile sites were analyzed by employing the potential-step method. Using chronoamperometry, impedance spectroscopy, and UV/VIS absorbance measurements, it is shown that the ionophore behaves as a carrier for protons, when the membranes are immersed between two aqueous solutions. It was possible to document the changes in the concentration profiles of both free ionophores and ionic species in some of the membranes. There is no evidence of proton hopping between the ionophores.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 81-87 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Chemistry of Isoindoles and Isoindolenines, XXVII. - 2-Alkyl-2H-dibenz[e,g]isoindoles; Synthesis, Properties, ReactionsThe tetracyclic hetarenes 6 are easily accessible via the N-oxide route starting with 9,10-bis(bromomethyl)phenanthrene (3) in a three-step procedure. The twofold annelation reduces the diene reactivity of the central 2H-isoindole system. Cycloaddition occurs as well with activated alkynes as with arynes. The hetarenes 6 can be protonated with trifluoroacetic acid and substituted by reaction with arenediazonium tetrafluoroborates.
    Notes: Die tetracyclischen Hetarene 6 sind nach dem N-Oxid-Verfahren einfach aus 9,10-Bis(brommethyl)phenanthren (3) präparativ dreistufig zugänglich. Durch die zweifache Anellierung wird die Reaktivität des zentralen 2H-Isoindol-Systems abgeschwächt. Cycloaddition tritt sowohl mit aktivierten Alkinen als auch mit Arinen ein. Die Hetarene 6 sind mit Trifluoressigsäure protonierbar und durch SE-Reaktion mit Arendiazonium-tetrafluoroboraten substituierbar.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 243-252 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Chemistry of Isoindoles and Isoindolenines, XXVIII.  -  3-Alkoxy-1H-isoindoles, Syntheses and Properties3-Alkoxy-1H-isoindoles 1 bearing substituents at the carbocyclic moiety have been synthesized from substituted 2,3-dihydro-1H-isoindol-1-ones 4 by regiospecific O-alkylation to 5 with trialkyloxonium tetrafluoroborates or methyl trifluoromethanesulfonate and subsequent NH deprotonation. According to the spectroscopic properties the semicyclic alkyl imidates 1 exist exclusively in the benzenoid 1H structure; the tautomeric o-quinonoid 2H structure 2 cannot be detected by spectroscopic means.
    Notes: 3-Alkoxy-1H-isoindole 1 mit Substituenten am carbocyclischen Teil wurden aus substituierten 2,3-Dihydro-1H-isoindol-1-onen 4 durch regiospezifische O-Alkylierung mit Trialkyloxonium-tetrafluoroboraten oder Trifluormethansulfonsäure-methylester zu 5 und nachfolgende NH-Deprotonierung synthetisiert. Aufgrund der spektroskopischen Befunde existieren die semicyclischen Imidsäure-alkylester 1 ausschließlich in der benzoiden 1H-Form; die tautomere 2H-Form 2 mit o-chinoider Struktur ist spektroskopisch nicht nachweisbar.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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