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Biomedical subjects

R G Wilson

Publications and source records attributed to R G Wilson.

At least 127 records · Page 7Linked to original sources
PubMed1979

Effects of stimulation and rest on the ultrastructure of the excitatory neuromuscular junctions of Locusta migratoria L.

The terminals of the fast axon on extensor tibiae muscle fibres of Locusta were examined in untreated nerve-muscle preparations and in preparations stimulated electrically at frequencies varying from 0.5 to 100 Hz. The ultrastructure of the terminals in preparations stimulated at the lower range of these frequencies, which induce twitch contractions of the muscles, is similar to that of the controls. Stimulation at the higher frequencies induced tetanic muscle responses and rapid fatigue of the muscles after which they would not respond again to high frequency stimulation for about 1 h. This loss and recovery of the responses of the muscles is correlated with changes in the ultrastructural appearance of the terminals, in particular in the number and shape of the synaptic vesicles. The ultrastructure of these "recovering" axon terminals closely resembles that of the controls.

Animals↗
PubMed1979

Changes in the distribution and size of synaptic vesicles in neuromuscular junctions of Locusta migratoria after stimulation and rest.

The distribution and size of synaptic vesicles in excitatory terminals of the extensor tibiae muscle were determined after stimulation at frequencies varying from 0.5 to 100 Hz and after subsequent rest. Only in preparations stimulated at the higher frequencies do these parameters differ from those in the controls. The synaptic vesicles in the nonsynaptic areas of these terminals are depleted in number, and the remaining vesicles are reduced in size. These effects are reversed after a 1 h rest.

Animals↗
PubMed1979

Glutamate uptake after stimulation-induced depletion of vesicle numbers in neuromuscular junctions of Locusta migratoria L.

The distribution of radioactivity at branches and terminals of the fast axon in extensor tibiae muscle incubated in the radiolabelled putative neurotransmitter L-glutamate was determined by electron microscopic autoradiography. Quantitative analysis of the distribution of silver grains at the axon branches and terminals in preparations stimulated at a low frequency shows that most of the radioactivity is present in the glial cells. In preparations stimulated to the point of fatigue substantial radioactivity is present in both the glial cells and the axoplasm of the terminals. It is suggested that the uptake of L-glutamate into the axoplasm of the terminals is correlated with the depletion and recovery of vesicle numbers after stimulation.

Animals↗
PubMed1979

Factors influencing the assessment of anticoccidial activity in cell culture.

A comparative study has been made of the factors influencing the assessment of anticoccidial potency in vitro against Eimeria tenella using established anticoccidials and arprinocid and some of its analogues. Drugs whose potency depended upon medium composition were amprolium, lasalocid and halofuginone. There was a difference in strain sensitivity with robenidine. Host cell type had an important effect on potency of monensin, decoquinate, arprinocid and its analogues. Arprinocid was active in chick liver cell systems but totally inactive in chick kidney cell systems, although its N-oxide was active in both cell types. Arprinocid-containing medium, conditioned by supporting the growth of chick embryo liver cell cultures, had an anticoccidial effect on E. tenella growing in chick kidney cells. It is deduced that the anticoccidial activity of arprinocid in the chick is due to a metabolite.

Adenine↗
PubMed1978

Biochemical mechanisms causing tick resistance.

Three general biochemical mechanisms can cause ticks to be resistant to acaricides: an alteration in the properties of the site of action, a change in the rate of transportation and a change in the rate of metabolism. The first mechanism enables increased concentrations of acaricide at the site of action to be tolerated, while the last two mechanisms result in a decreased concentration and/or persistence of the acaricide at the site of action. These mechanisms are discussed in detail with reference to a range or acaricides, particular emphasis being given to blue tick strains occurring in Southern Africa.

Animals↗
PubMed1977

Serum pyridoxal concentrations in children with diabetes mellitus.

Serum pyridoxal concentrations were measured in 63 children with diabetes mellitus and compared with those in healthy children of the same age. Twenty-four per cent of diabetic children had concentrations below the limit of normal for age and sex. Diabetic children, as a group, had lower serum pyridoxal concentrations than healthy children.

Adolescent↗