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  • 1
    Electronic Resource
    Electronic Resource
    Rat Brain Slices Produce and Liberate Kynurenic Acid upon Exposure to l-Kynurenine (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 52 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The incorporation of l-kynurenine (L-KYN) into kynurenic acid (KYNA) was examined in rat brain slices. KYNA was measured in the slices and in the incubation medium after purification by ion-exchange and HPLC chromatography. In pilot experiments, the formation of KYNA was confirmed by gas chromatography. KYNA was produced stereoselectively from l-KYN, and ∼90% of the newly synthesized KYNA was recovered from the incubation medium. Intracellular KYNA was not actively retained by the tissue and was lost from the cells upon repeated washes. Thus, regulation of the levels of extracellular KYNA appears to occur at the level of l-KYN uptake and/or kynurenine transaminase, the biosynthetic enzyme of KYNA. KYNA production from l-KYN was linear up to 4 h and reached a plateau at a l-KYN concentration of 250 γM. The process was effectively inhibited by the transaminase inhibitor aminooxyacetic acid (IC50, ∼25 γM), and showed pronounced regional distribution (hippocampus 〉 cortical areas 〉 thalamus ± cerebellum). The conversion of l-KYN to KYNA was dependent on oxygenation and on the presence of glucose in the incubation medium. Neither deletion of Ca2+ or Mg2+ nor addition of 20 mM Mg2+ had any effect. However, KYNA production was significantly attenuated in the absence of Cl− or in the presence of 50 mM K+ in the incubation medium. In Na+-free medium, the production of KYNA from l-KYN was increased by 30%. Experiments with ibotenate-lesioned striatal slices demonstrated a small neuronal component of the process, but indicated that the majority of KYNA in the brain is produced in and liberated from glial cells. The processes described here are suggested to underlie the role of KYNA as a neuromodulator and possible endogenous neuroprotective agent and anticonvulsant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb09218.x
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  • 2
    Electronic Resource
    Electronic Resource
    Pseudo-molecular ions in ion trap detector electron impact mass spectra: practical consequences (1989)
    s.l. : American Chemical Society
    Analytical chemistry 61 (1989), S. 1983-1984 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00192a041
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  • 3
    Electronic Resource
    Electronic Resource
    Routine gas chromatographic/mass spectrometric analysis of fatty acid methyl esters using the ion trap detector (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 1016-1022 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: About 60 long-chain fatty acids occur naturally in lipids of biological tissues and fluids, oils, fats and waxes. The ion trap detector (ITD) offers a convenient but powerful means for the routine analysis by gas chromatography/mass spectrometry of such fatty acids as their methyl esters (FAMES). Enhanced [M + 1]+ ions may be formed at higher sample levels of 50 ng or more. However, spectra still retain a predominantly electron impact (EI) character. Using the classical mass spectral performance test compound methyl stearate as an example, good library comparisons were obtained for spectra run over a dynamic range of 2 pg to 225 ng, when a mid-range ITD spectrum run on 7.5 ng was used as a reference. Almost equally good spectral comparisons were found with literature reference spectra run on both quadrupole and sector conventional mass spectrometers. Using human plasma phospholipid FAMES as an example, along with an ITD-generated EI spectral library of FAMES standards, it was seen that for most of the components present the mass spectral library comparison was good enough to permit identification based on mass spectrometry alone. For all components, a combination of gas chromatographic retention index and mass spectral information permitted an unequivocal identification.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200181111
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  • 4
    Electronic Resource
    Electronic Resource
    Gas chromatographic separation of triglycerides according to their degree of unsaturation on glass capillary columnsHT wishes to dedicate this publication to Prof. K. Kratzl, University of Vienna, Austria, on the occasion of his 65th birthday. (1981)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 109-114 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; On-column injection ; Triglycerides ; Separation according to degree of unsaturation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triglycerides are separated according to their molecular weight and their degree of unsaturation on glass capillary columns by use of the on-column injection technique. The columns employed are silylated SE-30 columns of 4.5, 8, and 10m length with a film thickness of ca. 0.15 μm. The paper gives several examples of chromatograms of natural and hydrogenated triglycerides as well as of mixtures of pure, known triglycerides before and after interesterification.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240040304
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  • 5
    Electronic Resource
    Electronic Resource
    GC-MS; Simultaneous quantification and identification by column effluent splitting (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 197-198 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Mass spectrometry ; Ion trap detector ; Simultaneous FID/MS detection ; Quantification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130315
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  • 6
    Electronic Resource
    Electronic Resource
    Untersuchungen über das Verhalten der Säurechloride von o-Carbonylverbindungen der Benzoesäure und Phenoxyameisensäure in Friedel-Crafts-Reaktionen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 2601-2606 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Behaviour of the Chlorides of o-Carbonyl Compounds of Benzoic and Phenoxyformic Acids in Friedel Crafts ReactionsFriedel Crafts reaction of o-acetylbenzoyl chloride (1b) with reactive arenes and aromatic heterocycles in the presence of stannic chloride yields 3-aryl-3-methylphthalides (2d-f,5). Treatment of o-hydroxyacetophenone (8a) with phosgene does not lead to chloroformic 2-acetylphenyl ester (8b) but to 4-methylene-4H-1,3-benzodioxin-2-one (7). Friedel Crafts reaction of 7 with resorcinol dimethyl ether (3) results in elimination of CO2 and formation of 2-[1-(2,4-dimethoxyphenyl)-vinyl]phenol (9a). o-Acetonylbenzoic acid (11) did not give the acyl chloride with thionyl chloride, nor did it react with active arenes under Friedel Crafts conditions. In all cases only 3-methylisocoumarine (12) was formed.
    Notes: Die Friedel-Crafts-Reaktion von o-Acetylbenzolylchlorid (1b) mit reaktionsfähigen Aromaten und aromatischen Heterocyclen führt in Gegenwart von Zinn(IV)-chlorid zu 3-Aryl-3-methylphthaliden (2d-f,5). Bei der Umsetzung von o-Hydroxyacetophenon (8a) mit Phosgen entsteht nicht Chlorameisensäure-(2-acetylphenylester) (8b), sondern 4-Methylen-4H-1,3-benzodioxin-2-on (7). Dieses reagiert mit Resorcin-dimethylether (3) unter Friedel-Crafts-Bedingungen unter CO2-Eliminierung zu 2-[1-(2,4-Dimethoxyphenyl)vinyl]phenol (9a). Im Falle der o-Acetonylbenzoesäure (11) erhielt man weder mit Thionylchlorid das Säurechlorid, noch eine Friedel-Crafts-Reaktion mit reaktiven Aromaten, sondern in allen Fällen entstand lediglich 3-Methylisocumarin (12).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100718
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