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Biomedical subjects

E Roberts

Publications and source records attributed to E Roberts.

At least 235 records · Page 13Linked to original sources
PubMed1978

Actin filaments in human skin fibroblasts are similar in normal persons and patients with Huntington's disease.

Actin filaments in skin fibroblasts from patients with Huntington's disease (HD) were examined using immunofluorescent methods. Actin filaments were seen along the axis of cell elongation (stress or sheath filaments) as well as in areas of membrane ruffling (lattice filaments). In some cases, filaments appeared to radiate from foci within the cell. Bundles of these filaments radiated in various directions at different depths within a cell. These structures are similar, in cells from both normal individuals and HD patients, to actin filaments observed in other cell types. The higher-than-normal confluent densities achieved in culture by fibroblasts from patients with Huntington's chorea do not involve alterations in the ultrastructure of actin filaments.

Actins↗
PubMed1978

Blood lead levels in sheep exposed to automotive emissions.

The lead content of whole blood of 62 sheep grazed continuously for 6 months near a major highway was compared with 38 sheep from a nearby uncontaminated area. Mean values of 0.90 and 0.20 microgram/ml were obtained. Four sheep from the contaminated area were placed in an uncontaminated paddock and the lead content of the blood decreased rapidly during the first 10 days and thereafter more slowly. After 185 days, blood lead levels had still not quite reached normal levels. Animal from an uncontaminated area showed an immediate rise in the blood lead levels when placed near a major highway. Sheep placed in a concrete pen away from motor vehicle exhaust emissions showed a rise in lead levels when fed with forage cut from the verges of a busy highway. Sheep placed near a highway and fed with forage from an uncontaminated area showed an increase of lead levels in the blood, comparable to that of the previous experiment. It was concluded that lead uptake by ingestion of polluted forage and by inhalation of airborne particulates are both mechanisms responsible for enhanced lead levels in ovine blood.

Animals↗
PubMed1977

Glutamate decarboxylase localization in neurons of the olfactory bulb.

Glutamate decarboxylase (GAD), the enzyme that synthesizes the neurotransmitter gamma-aminobutyric acid (GABA), has been localized in the rat olfactory bulb by immunocytochemical methods with both light and electron microscopy. The light microscopic results demonstrated GAD-positive puncta concentrated in the external plexiform layer and in the glomeruli of the glomerular layer. In addition, GAD-positive reaction product stained the dentrites and somata of granule and periglomerular cells. The electron microscopic observations confirmed the presence of GAD-positive reaction product within granule and periglomerular somata and dendrites. In electron micrographs of the external plexiform layer, the gemmules which arise from the distal dentrites of granule cells were also observed to be filled with reaction product, and these structures corresponded in size and location to the puncta observed in light microscopic preparations. The gemmules were observed to form reciprocal dendrodentritic synaptic junctions with mitral cell dentrites which lacked reaction product. In the glomeruli, GAD-positive reaction product was observed in the dentritic shafts and gemmules of periglomerular cells which also formed reciprocal dendrodentritic synaptic contacts with mitral/tufted cell dentrites. The localization of GAD in known inhibitory neurons of the olfactory bulb supports the case that these local circuit neurons use GABA as their neurotransmitter. The present study demonstrates that GAD molecules located within certain neuronal somata and dentrites can be visualized with antisera prepared against GAD that was purified from synaptosomal fractions of mouse brains. This finding suggests that the lack of GAD staining within somata and dentrites of GABA-ergic neurons noted in previous studies of the cerebellum and spinal cord was probably due to low GAD concentrations, rather than to antigenic differences among GAD molecules located in different portions of the neuron. A striking differences among GAD molecules located in different portions of the neuron. A striking difference between the granule and periglomerular neurons of the olfactory bulb and the neurons of the cerebellum and spinal cord is that the former have presynaptic dentrites while the latter do not. Since GAD-positive reaction product can be detected in the somata and dentrites of GABA-ergic neurons which have presynaptic dentrites, it is suggested that these neurons may differ from other GABA-ergic neurons with respect to either transport or metabolism of GAD.

Animals↗
PubMed1976

Immunocytochemical localization of glutamate decarboxylase in rat substantia nigra.

L-Glutamate decarboxylase (GAD, EC 4.1.1.15), the enzyme which catalyzes the alpha-decarboxylation of L-glutamate to form gamma-aminobutyric acid (GABA), was localized both light and electron microscopically in rat substantia nigra by an immunoperoxidase method. Large amounts of GAD-positive reaction produce were seen throughout the substantia nigra in light microscopic preparations, and it appeared to be localized in punctate structures that were apposed to dendrites and somata. Electron microscopic studies revealed that most of the axon terminals in the substantia nigra were filled with GAD-positive reaction product and formed both axodendritic and axosomatic synapses. Many dendrites were extensively surrounded by GAD-positive terminals which most commonly formed symmetric synaptic junctions, although some formed asymmetric synpatic junctions. The results of this investigation are consistent with biochemical, pharmacological and physiological data which have indicated that neurons of the neostriatum and globus pallidus exert a GABA-mediated, postsynaptic inhibition upon the neurons of the substantia nigra. These findings provide another example in the vertebrate central nervous system where Golgi I projection neurons are inhibitory and use GABA as their neurotransmitter.

Animals↗