Steven P. R. Rose

Bio: Steven P. R. Rose is an academic researcher. The author has contributed to research in topics: Neuron & Ficoll. The author has an hindex of 1, co-authored 1 publications receiving 204 citations.

Preparation of enriched fractions from cerebral cortex containing isolated, metabolically active neuronal and glial cells.

Abstract: 1. A procedure has been developed for the separation of intact metabolically active neuronal and glial cells in bulk from rat cerebral cortex. Separation depended on dispersion of the tissue in a Ficoll medium followed by centrifugation on a discontinuous Ficoll gradient. Up to 1·5×107 neuronal cells could be collected from 12 brains within 3hr. The morphological appearance of these cells seemed good, and the fraction was 8·5-fold purified in terms of dry weight. Average dry weight per neuron was 2300μμg. Maximum glial contamination of the neuronal fraction was 11% as determined by carbonic anhydrase measurements. The glial fraction was free from neurons but contained various subcellular contaminants. 2. Concentrations of nucleic acids, phospholipid, protein and phosphoprotein were determined in the separated fractions. The neuronal fraction was richer than the glial in all except phospholipid. Succinate dehydrogenase was equally distributed between neurons and glia but the neuronal fraction was 1·8-fold enriched in cytochrome oxidase. 3. Measurement of respiration by the cells showed an endogenous uptake of 117mμmoles of oxygen/mg./hr. in neurons, and 173mμmoles of oxygen/mg./hr. in glia. Addition of substrate at 10mm stimulated uptake to similar values in both fractions. With glucose it was 390, with pyruvate 355, and with glutamate 215mμmoles of oxygen/mg./hr. This represented a larger stimulation of neuronal than of glial respiration compared with the basal level. 4. Respiration in cell suspensions was 70–80% of that of slices, whereas fractionated tissue homogenates had respiratory rates of only one-third those of the cell suspensions. Lactate dehydrogenase content of cell suspensions was maintained during gradient centrifugation and washing. 5. The possible uses of isolated cell preparations are discussed.

Isolation and some chemical properties of oligodendroglia from calf brain.

Abstract: — The method of Norton and Poduslo (1970) for isolating brain cells has been adapted for the isolation of oligodendroglia from the white matter of calf brain. The cells were obtained in greater than 90 per cent purity, and in a yield of 11 × 106 cells/g of white matter. This number of cells represented a recovery of 11 per cent of the total cells in the tissue and therefore a considerably higher recovery of the original number of oligodendroglia. The average cell contained 5, 2 pg of DNA, 2–0 pg of RNA and 6, 7 pg of lipid. The lipid comprised cholesterol, galactolipid (both cerebroside and sulphatide) and phospholipid in the molar ratio of 1:0, 45:2, 3. Gangliosides were present in a concentration similar to that found in isolated rat neurons, The myelin-specific enzyme, 2′, 3′-cyclic nucleotide 3′-phosphohydrolase, was present at a level nearly equal to that in myelin, and eight-fold higher than the levels in rat neurons or astrocytes. The isolated oligodendroglia differed considerably from isolated astrocytes in size, morphology and chemical composition.

Protein turnover in cell-enriched fractions from rabbit brain.

Abstract: — A modification of the available methods was used for preparation of nerve and glia cell-enriched fractions from rabbit brain and spinal cord. The rate of incorporation of tritiated leucine and the turnover rates of protein during 10 days was studied in the bulkprepared cell fractions. The rate of incorporation into the nerve cell fraction was approximately three times greater than in the glia fraction. The nerve cells had one rapid and one slow phase in decline of radioactivity, while the glial cells were characterized by a more uniform decline. The soluble radioactivity was followed in whole tissue of brain and spinal cord and certain differences between the two were observed.

Composition of gangliosides and phospholipids of neuronal and glial cell enriched fractions.

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.