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R Beale

Publications and source records attributed to R Beale.

26 records · Page 2Linked to original sources
PubMed1983

Selective uptake of tritiated glycine, GABA and D-aspartate by retinal cells in culture: a study using autoradiography and simultaneous immunofluorescence.

Autoradiographic studies on the uptake of 3 tritiated amino acids by cell cultures of rat retina are reported. At 0.2 microM [3H]-GABA is taken up with great selectivity by a minority of medium to large multipolar cells. At 2 microM [3H]glycine is taken up with slightly less selectivity by a similar proportion of multipolar cells; the proportions of cells labeled by either amino acid are additive which indicates that they are separate populations. In simultaneous autoradiographical and indirect immunofluorescence experiments, both of these cell classes were found to bind tetanus toxin and are therefore presumably neurons. At 0.4 microM [3H]D-aspartate is preferentially taken up by virtually all small spheroid cells which lack long processes (putative immature photoreceptors), as well as by a minority of larger multipolar cells. All 3 tritiated amino acids also label flattened cells which include retinal glia. The results are discussed in relation to similar experiments performed on undissociated retina and we conclude that these experiments allow us to identify and quantify immature photoreceptors and certain sub-types of amacrine cells in these cultures.

Animals↗
PubMed1982

The binding of tetanus toxin to retinal cells.

An indirect immunofluorescence assay demonstrated intense binding of tetanus toxin to a minority of cells cultured from neonatal rat retina. These labelled cells were typically spheroid cells bearing long processes. Flat cells and smaller spheroid cells without long processes were essentially unlabelled. A similar assay performed on frozen sections of rat retina showed that tetanus toxin bound intensely to the inner plexiform layer, moderately to the outer plexiform and inner nuclear layers, and only very slightly to the outer nuclear layer. The localization of tetanus toxin bound to frozen sections was confirmed by autoradiography of [125I]tetanus toxin binding. In contrast, the monoclonal antibody A4 bound to all layers of the retina (except that of the outer segments). In cell cultures the monoclonal antibody Ran-2 bound to the flat cells but to neither class of spheroid cells. These data imply that tetanus toxin binds more intensely to retinal neurones than to photoreceptors and other retinal cell types. By assisting identification of cells dissociated from retina, assays of tetanus toxin binding should prove useful in the isolation of specific retinal cell-types.

Animals↗
PubMed1982

The effect of memantine on various neurobiological processes.

Experiments are reported which show that 1,3-dimethyl-5-aminoadamantane (DMAA, D-145, memantine, Memantine) does not influence the binding capacity of a variety of tritiated ligands to rat brain membranes thus suggesting that the drug does not interact with dopamine, opioid, GABA, alpha 1- and alpha 2-adrenergic receptors, but can influence with low potency 5-HT1 receptors. Autoradiographical studies also show that memantine does not interfere with the specific uptake mechanism of various transmitter substances nor is 3H-memantine taken up by any neuronal elements. Memantine at high concentrations was shown to release 3H-monoamines which had previously been taken up by nervous tissue but the release process is independent of calcium ions and is not dose-dependent. The latter effect could be explained by CNS culture studies which show memantine to produce morphological changes in neurones and glia when present at concentrations greater than 50 mumol/l.

Amantadine↗
PubMed1981

Potassium-stimulated, calcium-dependent release of [3H]GABA from neuron- and glia-enriched cultures of cells dissociated from rat cerebellum.

The release of [3H]GABA from cultures of cells dissociated from the rat cerebellum was investigated. The culture system contained a population of neurons (stellate and basket cells) which were capable of accumulating [3H]GABA and releasing it in a calcium-dependent manner in response to 50 mM potassium. In addition, the release of [3H]GABA for cultured astrocytes was found to be insensitive to potassium depolarization.

Animals↗