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  • 1970-1974  (9)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 22 (1974), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The accumulation of calcium ions by brain mitochondria and microsomes and by fractions containing neuronal or glial cells has been studied in vitro with techniques involving 45Ca and ultramicro-flame photometry. ATP and substrate-supported calcium accumulation by brain mitochondria was of the same magnitude as for mitochondria from other organs. Brain microsomes accumulated calcium approximately 15 times less than brain mitochondria. Variations in Na+/K+ ratios and in ATP/ADP ratios had a more marked influence on microsomal uptake than on mitochondrial uptake. The passive Ca2+ binding by glial cells was higher than neuronal perikarya and synaptosomes. Also the calcium accumulation ability in cell suspensions was slightly higher for glial cells as compared to neuronal perikarya. The calcium uptake by glial cells was stimulated by high external K+ concentration, which also was the case for nerve endings. The uptake in neuronal perikarya was unaffected by variations in K+ concentration. A comparison between neuronal and glial mitochondria showed that both reach a steady state level of similar magnitude, but that the rate of initial accumulation was greater for glial mitochondria. A high glial calcium accumulation was also observed for the microsomal fraction.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Fractions enriched in neuronal cell bodies and in glial cells were isolated from rabbit cerebral cortex by discontinuous gradient centrifugation. The ratio of total lipid to protein was approx. 50 per cent higher in the glial fraction than in the neuronal fraction. The fatty acid composition for the major phosphoglycerides was with few exceptions, similar for neurons and glia. The ganglioside concentration was very low for both cell types, but was approx. twice as high in the glial cells as in the neurons. The pattern of individual gangliosides was, however, very similar for the glial and neuronal fractions and did not differ from that of unfractionated cerebral cortex, synaptosomes and mitochondria. The latter results are discussed in relation to the estimated amounts of plasma membrane in the neuronal and glial fractions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 19 (1972), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Ethanol administered in vivo or in vitro during incubation of brain slices was studied with respect to its effect on brain protein synthesis.In the in vivo series the rats were given a single intraperitoneal injection of ethanol 3 h before death. Slices of cerebral cortex and liver were incubated in isotonic saline media containing [3H]leucine. Amounts of free and protein-bound radioactivity were determined. Subcellular fractions and fractions enriched in neuronal perikarya and in glial cells were prepared from cortical slices subsequent to incubation, and the specific radioactivity determined for each cell type.The incorporation of [3H]leucine into brain proteins was inhibited while incorporation into liver proteins was stimulated in ethanol-treated rats. The levels of TCA-soluble radio-activity, however, did not differ between the ethanol group and the controls. In the fractionated material from cerebral cortex, the specific radioactivity in the neuronal fraction was unaffected by ethanol, while the radioactivity in the glial fraction was significantly depressed. In vitro administration of ethanol induced a non-linear response in both brain and liver, with depression of leucine incorporation into proteins of cerebral cortex at all concentrations used. When brain slices were exposed to ethanol in vitro, in concentrations corresponding to the in vivo experiments, a similar reduction of the leucine incorporation into the glial fraction was obtained. Incorporation of leucine into subcellular fractions from whole brain cortex was also investigated. The specific sensitivity of the glial fraction to ethanol is discussed in relation to the involvement of the different cell types with transport processes in the brain.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Neuronal and glial cell enriched fractions were prepared by density gradient centrifugation of suspensions from rabbit cerebral cortex. The two cell types were incubated separately in media of extracellular ionic composition. The potassium accumulation was determined from analysis of potassium content of the cells by ultramicro flame photometry. Both neuronal and glial cells were capable of active potassium transport which was inhibited by ouabain (2 × 10−4m). The glial cells could accumulate potassium up to four to five times the concentration of the incubation medium and neurons up to one and a half to two times the medium concentration. The respiration in low potassium media was stimulated 15 per cent for neurons and 85 per cent for glia when potassium was added to a final concentration of 50 mm. The uptake by both neurons and glia showed temperature and sodium dependence. There was a definite magnesium requirement for the potassium uptake, particularly demonstrable for glial cells. Calcium inhibited potassium uptake by glia but stimulated slightly that by neurons.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The calcium-dependent incorporation of L-[3-14C]serine and [1,2−14C]ethanolamine into the phospholipid of isolated neuronal and glial cells from rabbit brain was studied, and the distribution of the enzymic system among the correspondent subfractions was examined. The neuronal cell-enriched fraction was found to possess a much higher rate of exchange of both bases than the glial cell-enriched fraction. Among the sub-fractions isolated from the neuronal and glial cells, those corresponding to neuronal plasma membranes and microsomes showed a noticeably higher exchange of serine and ethanolamine compared to the corresponding subfractions from glia. Neuronal/glial ratios of about 6–8 were found for the exchange activity in both plasma membrane-enriched fraction and in microsomes. Synaptosomes and synaptosomal subfractions contained low activities. It is concluded that the calcium-dependent enzymic system for the exchange of serine, ethanolamine and other nitrogenous bases with endogenous phospholipid is concentrated mostly in the neuronal perikaryal membranes, and could be used as a neuronal marker.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Rabbit cortex slices were incubated in a medium containing [3H]-uridine for various periods of time. Following incubation, neuronal and glial cell fractions were prepared on a discontinuous Ficoll-sucrose gradient. RNA was extracted from neurons and glia with a tris-sodium dodecyl sulphate-phenol solution and fractionated on a composite agarose-polyacrylamide gel. The stained gel showed major bands corresponding to 28 s, 18 s, 5 s and 4 s fractions and additional minor bands at the position of 24 s, 21 s and 13 s. Neuronal and glial RNA had the same general RNA pattern but the 5 s fraction was more pronounced in neuronal RNA and 4 s more pronounced in glial RNA. After 30 min labelling both neuronal and glial RNA had maximum activities in fractions higher than 28 s with a peak corresponding to 45 s. In the lower mol. wt. region the labelling was essentially poly-disperse. With increasing incubation time, peaks corresponding to 38 s and 32 s appeared as well as to ribosomal and soluble fractions. Incorporation of activity into total RNA expressed as d.p.m/μg of nucleic acids, showed similar labelling in neurons and glia after 30 and 60 min and a 3-4 times higher incorporation into neuronal RNA after 180 min. The possible implications of these results are discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 17 (1970), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Slices of rabbit cerebral cortex were incubated in the presence of labelled amino acids. Following incubation, neuron- and gliaenriched fractions were obtained by density gradient centrifugation and the TCA-insoluble radioactivity determined. The protein-bound radioactivity was five to six times higher in the neuronal-enriched fraction than in the glial-enriched fraction after incubation with tritiated leucine. The neuronal fraction incorporated also a number of other amino acids to a higher extent than the glial fraction (neuron/glia ratio 2·5-6). A definite dependence of incorporation on the rate of oxygenation was demonstrated. The suppression of amino acid incorporation was more marked for the neuronal fraction than for the glial fraction during incubation in relative hypoxia. An increase of potassium concentration in the incubation medium enhanced the amino acid incorporation in both fractions. Low sodium levels decreased the incorporation. Puromycin inhibited incorporation to approximately 30 per cent of control for both fractions. Addition of cycloheximide and dinitrophenol resulted in greater inhibition of incorporation in the neuronal fraction than in the neuroglial fraction. Actinomycin D did not markedly affect the incorporation in any fraction. These results are discussed in relation to in vivo and in in vitro differences for transport and incorporation of amino acids.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The distribution of protein-bound radioactivity among subcellular organelles of cerebral cortex was followed after intravenous administration of [3H]leucine and after incubation of brain slices in the presence of [3H]leucine. Neuronal and glial cell-enriched fractions were prepared by discontinuous sucroseFicol1 gradient centrifugation of cerebral cortex cell suspensions. Subcellular fractions were obtained from each of the cell prepara- tions and the protein-bound radioactivity determined after in uiuo and in vitro incorporation of [3H]leucine. The unfractionated neuronal material had a considerably higher level of protein-bound radioactivity than the glial material. The most marked neuronal-glial dif- ferences were observed in microsomes and soluble proteins, while the radioactive labelling of the nuclear and mitochondria1 fractions was similar for the two cell types.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 18 (1971), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Soluble proteins were studied in preparations from rabbit brain cortex enriched in neuronal or glial cells and in subcellular cortical fractions. Analytical polyacrylamide gels were used for acidic (pH 9-5) and basic (pH 4-3) proteins and qualitative and quantitative differences are described. The isozymes of lactic dehydrogenase, brain specific proteins and radioactive labelling patterns were used to characterize some soluble proteins.
    Type of Medium: Electronic Resource
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