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Biomedical subjects

R J Thomas

Publications and source records attributed to R J Thomas.

At least 127 records · Page 7Linked to original sources
PubMed1985

Hydatid disease: the alveolar variety in Australia. A case report with comment on the toxicity of mebendazole.

The alveolar form of hydatid disease, caused by the larval stage of the cestode Echinococcus multilocularis, is virtually confined geographically to the northern hemisphere. It produces clinically malignant multivesicular infiltrating lesions most often in the liver, and is quite different from the usual cystic variety caused by E. granulosus. We present a case report of a patient with alveolar hydatid disease, whose treatment with mebendazole was brief due to side effects of alopecia and granulocytopenia; and review the features of this disease which, with increasing international migration, may be encountered more frequently in Australia.

Agranulocytosis↗
PubMed1984

Lumbar spine: pretest predictability of CT findings.

Demographic and symptomatic data gathered from 460 patients referred for lumbosacral CT examinations were analyzed to determine if the prescan probability of normal or abnormal findings could be predicted accurately. We were unable to predict the presence of herniated disk on the basis of patient-supplied data alone. Age was the single most significant predictor of an abnormality and was sharply related to degenerative disease and spinal stenosis.

Adult↗
PubMed1983

Endogenous auxin and ethylene in pellia (bryophyta).

The occurrence of endogenous indole-3-acetic acid and ethylene in bryophyte tissue was tentatively demonstrated using gas chromatography, high performance liquid chromatography, and double-standard isotope dilution techniques. Rapidly elongating stalks (or setae) of Pellia epiphylla (L.) Corda sporophytes contain approximately 2.5 to 2.9 micrograms per gram fresh weight of putative free IAA. Ethylene released by setae increases during growth from 0.027 to 0.035 nanoliter per seta per hour. Application of 5 microliters per liter ethylene inhibits auxin-stimulated elongation growth of this tissue, a result which suggests that both endogenously produced compounds act in tandem as natural growth modulators.

Journal Article↗
PubMed1983

Arrested development of Nematodirus species in grazing lambs.

Spring born lambs grazing in initially clean pasture for two successive years acquired low levels of Nematodirus species infection which showed a progressive increase in the level of arrested development, reaching 70 to 90 per cent of the total worm burden in lambs slaughtered in November. Similar levels were recorded in worm free tracer lambs allowed only one month access to contaminated pastures. Results suggested that both seasonal environmental conditions and host age may play an important role in larval inhibition for this genus and that this phenomenon was not density dependent, nor associated with host immunity.

Age Factors↗
PubMed1982

Influence of Nitrate and Ammonia on Photosynthetic Characteristics and Leaf Anatomy of Moricandia arvensis.

The leaf anatomy and certain photosynthetic properties of nitrate- and ammonia-grown plants of Moricandia arvensis (L.) DC., a species previously reported to be a C(3)-C(4) intermediate, were investigated. Nitrate-grown plants had a high level of malate in the leaves while ammonia-grown plants had low levels of malate. In young leaves of nitrate-grown plants, there was a diurnal fluctuation of malate content, increasing during the day and decreasing during the night. Titratable acidity remained low in leaves of both nitrate- and ammonia-grown plants.In nitrate-grown plants, the activity of phosphoenolpyruvate (PEP) carboxylase was about 2-fold higher than in ammonia-grown plants, the latter having activity typical of C(3) species. Also, in nitrate-grown plants, the ratio of activities of ribulose 1,5-bisphosphate (RuBP) carboxylase/PEP carboxylase was lower than in ammonia-grown plants. Nitrate reductase activities were higher in nitrate- than in ammonia-grown plants and the greatest activity was found in younger leaves.With nitrate-grown plants, during a pulse-chase experiment the label in malate, as a percentage of the total labeled products, increased from about 7% after a 10-second pulse with (14)CO(2) up to 17% during a 5-minute chase with (12)CO(2). The pattern of (14)C labeling in various metabolites suggests the primary carboxylation is through RuBP carboxylase with a secondary carboxylation through PEP carboxylase. In similar experiments, with ammonia-grown plants, the percentage label in malate was only 0% to 4% with no increase in malate labeling during the chase period. The CO(2) compensation point was lower in nitrate-grown than ammonia-grown plants.There was no evidence of Kranz-like anatomy in either the nitrate or ammonia-grown plants. Mitochondria of bundle-sheath cells were strikingly positioned along the inner tangential wall. This might allow the chloroplasts of these cells to fix the mitochondrial photorespired CO(2) more effectively and contribute to the low CO(2) compensation point in the species. Chloroplasts of bundle-sheath cells and contiguous mesophyll cells were similar in size and structure in plants grown on different media, although chloroplast thylakoids and stromata of the ammonia-grown plants stained more intensely than those of nitrate-grown plants. In addition, irregular clusters of phytoferritin particles occurred in the chloroplasts of the ammonia-grown plants.The results indicate that the substantial activity of PEP carboxylase, incorporation of CO(2) into malate, the high malate content, and in part the relatively low CO(2) compensation point in Moricandia arvensis may be accounted for by metabolism of nitrate rather than by a state of C(3)-C(4) intermediacy.

Journal Article↗