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  • 1
    ISSN: 1438-2199
    Schlagwort(e): Amino acids ; Homocysteine ; Plasma ; Reference values ; Circadian variations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The purpose of this study was to investigate H(e) concentration in plasma from 80 healthy donors in relation to age (6 newborns are also included), sex, daily variation (9, 11 a.m.; 2, 6, 12 p.m.) and a period of 5 subsequent months. A significant correlation (r = 0.63, p 〈 0.001) was observed between plasma H(e) and age and a statistical difference (p 〈 0.05) was found between female and male. No circadian rhythm or significant variations over 5 months were found.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-6903
    Schlagwort(e): Cerebral cortex ; ATP-ases ; synaptic plasma membranes ; naloxone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Naloxone is a specific competitive antagonist of morphine, acting on opiate receptors, located on neuronal membranes. The effects of in vivo administration of naloxone on energy-consuming non-mitochondrial ATP-ases were studied in two different types of synaptic plasma membranes from rat cerebral cortex, known to contain a high density of opiate receptors. The enzyme activities of Na+, K+-ATP-ase, Ca2+, Mg2+-ATP-ase and Mg2+-ATP-ase and of acetylcholinesterase (AChE) were evaluated on synaptic plasma membranes obtained from control and treated animals with effective dose of naloxone (12μg · kg−1 i.m. 30 minutes). In control (vehicle-treated) animals specific enzyme activities assayed on these two types of synaptic plasma membranes are different, being higher on synaptic plasma membranes of II type than of I type, because the first fraction is more enriched in synaptic plasma membranes. The acute treatment with naloxone produced a significant decrease in Ca2+,Mg2+-ATP-ase activity and an increase in AChE activity, only in synaptic plasma membranes of II type. The decrease of Ca2+,Mg2+-ATP-ase enzymatic activity and the increased AChE activity are related to the interference of the drug on Ca2+ homeostasis in synaptosoplasm, that leads to the activation of calcium-dependent processes, i.e. the extrusion of neurotransmitter. These findings give further evidence that pharmacodynamic characteristics of naloxone are also related to increase [Ca2+] i , interfering with enzyme systems (Ca2+,Mg2+-ATP-ase) and that this drug increases acetylcholine catabolism in synaptic plasma membranes of cerebral cortex.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Neurochemical research 23 (1998), S. 1485-1491 
    ISSN: 1573-6903
    Schlagwort(e): Cerebral cortex ; energy metabolism ; enzymes ; L-acetylcarnitine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The maximum rate (Vmax) of some mitochondrial enzymatic activities related to the energy transduction (citrate synthase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, cytochrome oxidase) and amino acid metabolism (glutamate dehydrogenase, glutamate-pyruvate-transaminase, glutamate-oxaloacetate-transaminase) was evaluated in non-synaptic (free) and intra-synaptic mitochondria from rat brain cerebral cortex. Three types of mitochondria were isolated from rats subjected to i.p. treatment with L-acetylcarnitine at two different doses (30 and 60 mg·kg−1, 28 days, 5 days/week). In control (vehicle-treated) animals, enzyme activities are differently expressed in non-synaptic mitochondria respect to intra-synaptic “light” and “heavy” ones. In fact, α-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, glutamate-pyruvate-transaminase and glutamate-oxaloacetate-transaminase are lower, while citrate synthase, cytochrome oxidase and glutamate dehydrogenase are higher in intra-synaptic mitochondria than in non-synaptic ones. This confirms that in various types of brain mitochondria a different metabolic machinery exists, due to their location in vivo. Treatment with L-acetylcarnitine decreased citrate synthase and glutamate dehydrogenase activities, while increased cytochrome oxidase and α-ketoglutarate dehydrogenase activities only in intra-synaptic mitochondria. Therefore in vivo administration of L-acetylcarnitine mainly affects some specific enzyme activities, suggesting a specific molecular trigger mode of action and only of the intra-synaptic mitochondria, suggesting a specific subcellular trigger site of action.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Ft Charge distribution ; 21.10.-k Properties of nuclei; nuclear energy levels ; 21.65.+f Nuclear matter ; 29.40.Mc Scintillation detectors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract. We report the results of an experimental search for spontaneous transition of nuclei from ordinary to superdense state in NaI(Tl). New limits on the superdense-state parameters are presented.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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