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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of high specific activity (+)- and (-)-6-[18F]fluoronorepinephrine via the nucleophilic aromatic substitution reaction (1991)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 34 (1991), S. 767-771 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00106a043
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanistic Positron Emission Tomography Studies of 6-[18F]Fluorodopamine in Living Baboon Heart: Selective Imaging and Control of Radiotracer Metabolism Using the Deuterium Isotope Effect (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Mechanistic positron emission tomography (PET) studies using the deuterium isotope effect and specific pharmacological intervention were undertaken to examine the behavior of 6-[18F]fluorodopamine (6-[18F]FDA; 1) and (−)-6-[18F]fluoronorepinephrine {(−)-6-[18F]FNE; 2} in the baboon heart. Two regiospecifically deuterated derivatives of 6-[18F]FDA [α,α-D2(3) and β,β-D2 (4)] were used to assess the contributions of monoamine oxidase (MAO) and dopamine β-hydroxylase, respectively, to the clearance kinetics of 6-[18F]FDA. Compound 3 showed a reduced rate of clearance, consistent with MAO-catalyzed cleavage of the α C-D bond, whereas compound 4 showed no change, indicating that cleavage of the β C-D bond is not a rate-limiting step. Pretreatment with pargyline, an MAO inhibitor, also decreased the rate of clearance. Desipramine and tomoxetine [norepinephrine (NE) uptake inhibitors], but not GBR-12909 (a dopamine uptake inhibitor), blocked the uptake of both (−)-6-[18F]FNE and 6-[18F]FDA, with (−)-6-[18F]FNE showing a higher degree of blockade. Chiral HPLC demonstrated that 6-[18F]FDA is stereoselectively converted to (−)-6-[18F]FNE in vivo in the rat heart. These studies demonstrate that (a) the more rapid clearance of 6-[18F]FDA relative to (−)-6-[18F]FNE can be largely accounted for by metabolism by MAO; (b) selective deuterium substitution can be used to protect a radiotracer from metabolism in vivo and to favor a particular pathway; (c) 6-[18F]FDA and (−)-6-[18F]FNE share the NE transporter; (d) 6-[18F]FDA is stereoselectively converted to (−)-6-[18F]FNE in vivo; and (e) the profile of radioactivity in the heart for 6-[18F]FDA is complex, probably including labeled metabolites as well as neuronal and nonneuronal uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.65020682.x
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  • 3
    Electronic Resource
    Electronic Resource
    Dopamine Receptor-Mediated Regulation of Striatal Cholinergic Activity (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 74 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Large numbers of in vitro studies and microdialysisstudies suggest that dopaminergic regulation of striatal acetylcholine (ACh)output is via inhibitory dopamine D2 receptors and stimulatorydopamine D1 receptors. Questions remain as to the relativepredominance of dopamine D2 versus D1 receptormodulation of striatal ACh output under physiological conditions.Using positron emission tomography, we first demonstrate thatnorchloro[18F]fluoroepibatidine ([18F]NFEP), a selectivenicotinic ACh receptor (nAChR) ligand, was sensitive to changes of striatalACh concentration. We then examined the effect of quinpirole (D2agonist), raclopride (D2 antagonist), SKF38393 (D1agonist), and SCH23390 (D1 antagonist) on striatal binding of[18F]NFEP in the baboon. Pretreatment with quinpirole increased thestriatum (ST) to cerebellum (CB) ratio by 26 ± 6%, whereas pretreatmentwith raclopride decreased the ST/CB ratio by 22 ± 2%. The ratio of thedistribution volume of [18F]NFEP in striatum to that in cerebellum,which corresponds to (Bmax/KD) + 1(index for nAChR availability), also showed a significant increase (29 and20%; n = 2) and decrease (20 ± 3%; n = 3) after pretreatment withquinpirole and raclopride, respectively. However, both the D1agonist and antagonist had no significant effect. This suggests that underphysiological conditions the predominant influence of endogenousdopamine on striatal ACh output is dopamine D2, not D1, receptor-mediated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0741514.x
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative evaluation of positron emission tomography radiotracers for imaging the norepinephrine transporter: (S,S) and (R,R) enantiomers of reboxetine analogs ([11C]methylreboxetine, 3-Cl-[11C]methylreboxetine and [18F]fluororeboxetine), (R)-[11C]nisoxetine, [11C]oxaprotiline and [11C]lortalamine (2005)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 94 (2005), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have synthesized and evaluated several new ligands for imaging the norepinephrine transporter (NET) system in baboons with positron emission tomography (PET). Ligands possessing high brain penetration, high affinity and selectivity, appropriate lipophilicity (log P = 1.0–3.5), high plasma free fraction and reasonable stability in plasma were selected for further studies. Based on our characterization studies in baboons, including 11C-labeled (R)-nisoxetine (Nis), oxaprotiline (Oxap), lortalamine (Lort) and new analogs of methylreboxetine (MRB), in conjunction with our earlier evaluation of 11C and 18F derivatives of reboxetine, MRB and their individual (R,R) and (S,S) enantiomers, we have identified the superiority of (S,S)-[11C]MRB and the suitability of MRB analogs [(S,S)-[11C]MRB 〉 (S,S)-[11C]3-Cl-MRB 〉 (S,S)-[18F]fluororeboxetine] as potential NET ligands for PET. In contrast, Nis, Oxap and Lort displayed high uptake in striatum (higher than in thalamus). The use of these ligands is further limited by high non-specific binding and relatively low specific signal, as is characteristic of many earlier NET ligands. Thus, to our knowledge (S,S)-[11C]MRB remains by far the most promising NET ligand for PET studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2005.03202.x
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of high specific activity 6-[18F]fluorodopamine for positron emission tomography studies of sympathetic nervous tissue (1991)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 34 (1991), S. 861-863 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00106a055
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  • 6
    Electronic Resource
    Electronic Resource
    Dopamine-transporter occupancy after intravenous doses of cocaine and methylphenidate in mice and humans (1999)
    Springer
    Psychopharmacology 146 (1999), S. 93-100 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Methylphenidate ; Dopamine transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objectives: Recent studies using positron emission tomography (PET) have established the relationship between an intravenous dose of cocaine and the percentage occupancy of the dopamine transporter in humans, and have documented the requirement of more than 50% occupancy for perception of the ”high”. The present experiments were conducted to examine dose–occupancy and dose–effect relationships in mice for cocaine and also for methylphenidate, a dopamine uptake blocker used in pediatric psychiatry. Methods: Percentage occupancies of the dopamine transporter by cocaine and methylphenidate were estimated after intravenous injection in mice from the displacement of in vivo binding of [3H]cocaine from the striatum. Locomotor activity was measured in a photocell apparatus. Results: The relationship between drug doses (milligrams of hydrochloride salt per kilogram body weight) and percentage occupancy of the dopamine transporter was indistinguishable for cocaine and methylphenidate, and corresponded to about 50% occupancy at 0.25 mg/kg and about 80% at 1 mg/kg. This was similar to the relationship between drug dose and transporter occupancy, previously measured in human and baboons using [11C]cocaine or [11C]d-threo-methylphenidate and PET. Methylphenidate increased locomotor activity in the mice substantially more than cocaine at the same dose and the same degree of dopamine-transporter receptor occupancy. Conclusions: The range of dopamine-transporter occupancy required for behavioral activation in the mice was thus similar to that previously reported for experience of a cocaine- or methylphenidate-induced ”high” in human subjects. Our results are consistent with other studies in which both cocaine and methylphenidate were evaluated in animal behavioral assays and were found to have very similar psychopharmacological properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130051093
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical studies of proteins that degrade pheromones (1988)
    Springer
    Journal of chemical ecology 14 (1988), S. 2033-2046 
    Details
    ISSN: 1573-1561
    Keywords: Cyclopropanation ; cyclopropanol ; enzyme inhibitor ; pheromone analog ; vinyl ketone ; Heliothis virescens ; Plutella xylostella ; α-fluoroaldehyde ; (Z)-11-hexadecenal ; (Z)-9-tetradecenal ; Lepidoptera ; Noctuidae ; Plutellidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Aldehyde components of lepidopterous pheromones are converted to carboxylic acids by aldehyde oxidizing enzymes (AOEs) that are present at high levels in antennal tissues of adult moths. The AOEs may include O2-requiring aldehyde oxidases as well as nucleotide-cofactor-requiring aldehyde dehydrogenases. Three classes of inhibitors were synthesized and examined in vitro for AOE inhibition usingHeliothis virescens antennae: (1) cyclopropanols, (2) α-fluorinated aldehydes, and (3) α,β-unsaturated carbonyls. First, cyclopropanated analogs of (Z)-11-hexadecenal (Z11–16∶A1), a common unsaturated aldehyde component of many species' pheromone blends, were synthesized as isosteric pheromone analogs and as potential inhibitors of the moth AOEs. NMR assignments are reported for thecis- andtrans-cyclopropanols. Cyclopropanols appear to act as oxidase-activated AOE inhibitors, perhaps via the unstable cyclopropanones. Second, α-fluoro and α,α-difluoro substituted analogs ofZ9–14∶A1 were synthesized and shown to be modest inhibitors of both the alcohol oxidase and AOE activities. Finally, the most potent inhibitors were α,β-unsaturated carbonyl mimics of theZ11–16∶A1. The α-methylene aldehyde was 1000-fold less effective than the vinyl ketoneZ1,11–16∶3-oxo. This inhibition appears irreversible and is postulated to involve electrophilic modification of an active site sulfur nucleophile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01014248
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  • 8
    Electronic Resource
    Electronic Resource
    Metabolic transformation of tritium-labeled pheromone by tissues ofHeliothis virescens moths (1986)
    Springer
    Journal of chemical ecology 12 (1986), S. 411-429 
    Details
    ISSN: 1573-1561
    Keywords: Pheromone metabolism ; tritium-labeling ; acetate esterase ; alcohol oxidase ; aldehyde dehydrogenase ; Heliothis virescens ; Lepidoptera ; Noctuidae ; sensory biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Unsaturated aliphatic pheromones ofH. virescens were prepared at high specific activity (3H, 58 Ci/mmol) and were employed to study tissue specificity of acetate esterase, alcohol oxidase, and aldehyde dehydrogenase in male and femaleHeliothis virescens. Thus, [9,10-3H2]Z9-14:Ac was synthesized by partial tritiation of the corresponding alkyne and was converted to the labeledZ9-14∶OH andZ9-14∶Al for metabolic studies. Soluble and membrane-associated enzyme activities were determined by radio-TLC assays. Esterase activity is highest in legs of both sexes, but also occurs in antennal and glandular tissues. Oxidase activity requires O2 and is highest in female pheromone gland tissues, but it is also high in the male hairpencils. Aldehyde dehydrogenase activity was uniformly high in all tissues, but highest in antennal tissues of both males and females.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020564
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