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  • 1
    Electronic Resource
    Electronic Resource
    INTERACTION OF CATECHOLAMINE AND AMINO ACID METABOLISM IN BRAIN: EFFECT OF PARGYLINE AND l-DOPA (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 23 (1974), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The combination of l-DOPA and pargyline caused a decrease in level of aspartate and an increase in that of glutamine in vivo in cerebral cortex, cerebellum, brain stem, hypothalamus, neostriatum and cervical cord of rat. There was also a decreased incorporation of radioactivity from [1-14C]acetate into amino acids in vivo, most notably in cerebellum and brain stem. The labelling of glutamine was especially affected. In addition, cortical slices were prepared from guinea pigs which had been pretreated with pargyline. These slices were incubated with and without 1 mm l-DOPA in media containing [1-14C]acetate. Pargyline alone caused a stimulation of the labelling of glutamate and aspartate but not glutamine and GABA; the levels of aspartate and GABA were greater than in control slices. The addition of l-DOPA to slices from pargylinized animals caused a severe decrease in glutamine labelling but not in that of glutamate or aspartate; the level of glutamine was increased while that of glutamate was decreased. The results are discussed in terms of the known biochemical and morphological compartmentation of amino acids in brain. It is suggested that catecholamines, in the process of functioning as transmitters, may also function as metabolic regulators of other transmitters, e.g. amino acids, as well as of the energy required for balanced neuronal function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1974.tb06929.x
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  • 2
    Electronic Resource
    Electronic Resource
    COMPARTMENTATION OF CITRIC ACID CYCLE METABOLISM IN BRAIN: LABELLING OF GLUTAMATE, GLUTAMINE, ASPARTATE AND GABA BY SEVERAL RADIOACTIVE TRACER METABOLITES (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 17 (1970), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —(1) Compartmentation of the metabolism of amino acids in brain has been studied in slices of cerebral cortex incubated with sodium [1-14C]acetate, sodium [1-14C]-bicarbonate, [1-14C]GABA or l-[1-14C]glutamate and in samples of brain after injection in vivo of [1-14C]- or [3H]acetate.(2) The method of treatment of the slices (a) maintained in ice-cold medium prior to incubation; (b) preincubation at 37°C and transfer to fresh medium affected the metabolism of the added, labelled substrate, particularly its labelling of glutamine.(3) The specific activity of glutamine labelled from the above metabolites was greater than that of glutamic acid in experiments of 10–30 minutes duration, whether or not subjected to pretreatment in the cold.(4) Incubation in medium containing 27 mm-K+ was associated with a decrease in the relative specific activity (RSA) of glutamine, except for the increase when l-[1-14C]glutamate was the precursor.(5) The data have been discussed in terms of metabolic compartmentation and their consistency with the concept of the presence in brain of more than one citric acid cycle, one containing the relatively smaller pools of intermediates and associated with synthetic processes; the other containing the relatively larger pools of intermediates and functioning as a homeostatic buffer for energy metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1970.tb02254.x
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  • 3
    Electronic Resource
    Electronic Resource
    QUANTITATIVE ASPECTS OF CO2 FIXATION IN MAMMALIAN BRAIN IN VIVO (1964)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 11 (1964), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1964.tb06117.x
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidative Metabolism of 4-Aminobutyrate by Rat Brain Mitochondria: Inhibition by Branched-chain Fatty Acid (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 34 (1980), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The oxidation of 4-aminobutyric acid (GABA) by nonsynaptosomal mitochondria isolated from rat forebrain and the inhibition of this metabolism by the branched-chain fatty acids 2-methyl-2-ethyl caproate (MEC) and 2, 2-dimethyl valerate (DMV) were studied. The rate of GABA oxidation, as measured by O2 uptake, was determined in medium containing either 5 or 100 mM-[K+]. The apparent Km for GABA was 1.16 ± 0.19 mM and the Vmax in state 3 was 23.8 ± 5.5 ng-atoms O2. min−1. mg protein−1 in 5 mM-[K+]. In a medium with 100 mM-[K+] the apparent Km was 1.11 ± 0.17 mM and Vmax was 47.4 ± 5.7 ng-atoms O2. min−1. mg protein−1. The Km for MEC was determined to be 0.58 ± 0.24 or 0.32 ± 0.08 mM, in 5 or 100 mM-[K+], respectively. For DMV, the Ki was 0.28 ± 0.05 or 0.34 ± 0.06 mM, in 5 or 100 mM-[K+] medium, respectively. The O2 uptake of the mitochondria in the presence of GABA was coupled to the formation of glutamate and aspartate; the ratio of oxygen uptake to the rate of amino acid formation was close to the theoretical value of 3. Neither the [K2] nor any of the above inhibitors had any effect on this ratio. The metabolism of exogenous succinic semialdehyde (SSA) by these same mitochondria was also examined. The Vmax for utilization of oxygen in the presence of SSA was much greater than that found with exogenously added GABA, indicating that the capacity for GABA oxidation by these mitochondria is not limited by SSA dehydrogenase. In addition, the branched-chain fatty acids did not inhibit the metabolism of exogenously added SSA. Thus, the inhibitors examined apparently act by competitively inhibiting the GABA transaminase system of the mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1980.tb04640.x
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  • 5
    Electronic Resource
    Electronic Resource
    COMPARTMENTATION OF CITRIC ACID CYCLE METABOLISM IN BRAIN: EFFECT OF AMINOOXYACETIC ACID, OUABAIN AND Ca2+ ON THE LABELLING OF GLUTAMATE, GLUTAMINE, ASPARTATE AND GABA BY [1-14C]ACETATE, [U-14C]GLUTAMATE AND [U-14C] ASPARTATE (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 17 (1970), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —(1) The effects of aminooxyacetic acid, ouabain and Ca2+ on the compartmentation of amino acid metabolism have been studied in slices of brain incubated with sodium-[1-14C]acetate, l-[U-14C]glutamate and l-[U-14C]aspartate as tracer metabolites.(2) Aminooxyacetic acid (10-3 m) inhibited the labelling of aspartate from [14C]acetate and [14C]glutamate, as well as the incorporation of label from [14C]aspartate into glutamate and glutamine. It also inhibited the labelling of GABA from all three radioactive precursors, as would be anticipated if there was inhibition of several transaminases as well as glutamate decarboxylase. The RSA of glutamine labelled from [1-14C]acetate was increased. This finding indicated that the glutamate pool which is utilized for glutamine formation is associated with glutamate dehydrogenase, and this enzyme appears to be related to the ‘synthetic tricarboxylic acid cycle’. AOAA exerted its major inhibitory effects on the citric acid‘energy cycle’with which transaminases are associated.(3) Ouabain (10-5 m) inhibited the labelling of glutamine to a much greater extent than the labelling of glutamate from [1-14C]acetate. It also caused leakage of amino acids from the tissue into the medium. Its effect on the glutamate–glutamine system was interpreted to be a selective inhibition of the 'synthetic’citric acid cycle.(4) The omission of Ca2+ from the incubation medium was associated with formation of glutamine with RSA less than 1·0 when labelled from [U-14C]glutamate, [U-14C]aspartate and lower than normal when labelled from [1-14C]acetate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1970.tb02253.x
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  • 6
    Electronic Resource
    Electronic Resource
    A RELATIONSHIP OF N-ACETYLASPARTATE BIOSYNTHESIS TO NEURONAL PROTEIN SYNTHESIS (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 24 (1975), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A detailed time study of the incorporation of label from sodium-[1-14C]acetate, [1-14C]ethanol, and [2-14C]glucose into the aspartyl moiety of N-acetylaspartic acid (NAA) was conducted. As expected the specific activity of aspartate increased rapidly with time and peaked within 15-20 min after which it fell sharply; but significantly, that of the aspartyl moiety of NAA rose very slowly even after the specific activity of aspartate had fallen to less than 1 per cent of the peak values.A rat brain microsomal free supernatant preparation was shown enzymatically to incorporate label from sodium-[1-14C]acetate into the t-RNA fraction from which was isolated N-[1-14C]acetylaspartic acid. From these observations we were inclined to speculate that NAA-t-RNA may serve as an initiator of neuronal protein synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1975.tb07665.x
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  • 7
    Electronic Resource
    Electronic Resource
    DECARBOXYLATION STUDIES OF GLUTAMATE, GLUTAMINE, AND ASPARTATE FROM BRAIN LABELLED WITH [1-14C] ACETATE, l-[U-14C]-ASPARTATE, AND l-[U-14C]GLUTAMATE (1969)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 16 (1969), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Studies in vivo and in vitro of the distribution of label in C-1 of glutamate and glutamine and C-4 of aspartate in the free amino acids of brain were carried out. [1-14C]-Acetate was used both in vivo and in vitro and l-[U-14C]aspartate and l-[U-14C]glutamate were used in vitro.〈list xml:id="l1" style="custom"〉1The results obtained with labelled acetate and aspartate suggest that CO2 and a 3-carbon acid may exchange at different rates on a COa-fixing enzyme.2The apparent cycling times of both glutamate and glutamine show fast components measured in minutes and slow components measured in hours.3With [1-14C]acetate in vitro glutamine is more rapidly labelled in C-1 than is glutamate at early time points; the curves cross over at about 7 min.4The results support and extend the concept of metabolic compartmentation of amino acid metabolism in brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1969.tb06854.x
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  • 8
    Electronic Resource
    Electronic Resource
    COMPARTMENTATION OF GLUTAMIC ACID METABOLISM IN BRAIN SLICES (1968)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 15 (1968), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —(1) Compartmentation of glutamate metabolism in brain cortex previously observed only in vivo, has now been demonstrated in vitro.This was shown by using [U-14C]aspartate and [U-14C]glutamate as tracer substrates.(2) Preparation and maintenance of the slices at 0° resulted in reversible inhibition of glutamine synthesis. Preincubation at 37° for 10 min or preparation of the slices at room temperature partially overcame this inhibition.(3) Transfer to fresh medium after preincubation had an added stimulatory effect on glutamine synthesis.(4) Incubation in high K+ medium (27 mm) altered the relative specific activity of glutamine.(5) The data are in keeping with the postulate of the existence of at least two different pools of citric acid cycle intermediates in the cerebral cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1968.tb06184.x
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  • 9
    Electronic Resource
    Electronic Resource
    Resistance to Erysiphe fischeri in two populations of Senecio vulgaris (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 42 (1993), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The frequency and distribution of different specific phenotypes for resistance to Erysiphe fischeri was studied in two populations of the annual weed Senecio vulgaris (groundsel) one located in Glasgow, Scotland the other located about 480 km south at Wellesbourne, England. Progeny of individual plants from the two host populations were tested for their response to up to 10 different isolates of E. fischeri, five from each location; each isolate had a different specific virulence phenotype. Most plants in each sample were susceptible to all 10 isolates. The proportion of plants whose progeny were resistant to a particular isolate ranged from 1% to 10% with the exception of resistance to one isolate that occurred with a frequency of 37% at Wellesbourne. Overall, resistance to one or more of the 10 isolates appeared to be more common in the plant population sampled at Wellesbourne than at Glasgow. Of the total number of groundsel line/isolate combinations tested, 10% involving Wellesbourne plants and 2% involving Glasgow plants were incompatible, i.e. resistant/avirulent. Both groundsel populations tended to be dominated by one or two resistance phenotypes but they were nevertheless highly heterogeneous when less frequent resistance phenotypes were considered. This was particularly evident at Wellesbourne where 10 different resistance phenotypes were recorded amongst a total of 75 plants growing within an area of 1 m2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1993.tb01544.x
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  • 10
    Electronic Resource
    Electronic Resource
    Diversity and variation in expression of resistance to Erysiphe fischeri in Senecio vulgaris (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 42 (1993), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The reactions of 20 inbred lines of Senecio vulgaris (groundsel) to inoculation with up to 10 isolates of Erysiphe fischeri (powdery mildew) were investigated in a number of repeat experiments. There was considerable variation among isolate/plant line reaction phenotypes with examples of both isolate-specific complete resistance and isolate-specific partial resistance. Some plant lines possessed high levels of partial resistance to all isolates tested. Incubation temperature and plant age influenced the infection types of some isolate/plant line combinations. In this pathosystem, complete and partial resistance, together with age-dependent and temperature-dependent resistance, appear to have evolved to facilitate a defence strategy based on a complex mosaic of interacting factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1993.tb01545.x
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