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Biomedical subjects

D Lewis

Publications and source records attributed to D Lewis.

At least 307 records · Page 17Linked to original sources
PubMed1982

Role of copper in collagen cross-linking and its influence on selected mechanical properties of chick bone and tendon.

Day-old White Leghorn cockerels were fed skim-milk-based diets containing 0, 2, 4, 8, or 16 ppm added copper as CuSO4 for 21 days. Lysyl oxidase was extracted from bone and tendon. The recovery of activity from the extracts was linearly correlated with dietary copper (r greater than 0.90). Tests of the mechanical properties of tendon and bone indicated that tendon viscoelasticity (as measured by stress--relaxation) may not be significantly influenced by copper, whereas the ultimate torsional strength of bone is markedly decreased when the dietary copper level is below 1 ppm. Furthermore the torsional fracture characteristics of bone from copper-deficient birds demonstrated a lack of plastic deformation prior to failure that was normally seen in bone from control birds. The change in the mechanical properties of bone from copper-deficient birds appeared to be related to a decrease in the amounts of dihydroxylysinonorleucine and other lysine-derived cross-linking amino acids in bone collagen. The data indicate that the requirement for optimal growth of chicks fed skim-milk-based diets is 6--8 ppm copper, however, the requirement for normal cross-link formation in bone is less than 2 ppm copper.

Amino Acid Oxidoreductases↗
PubMed1982

Changes in the mean corpuscular red cell volume in women with beta-thalassaemia trait during pregnancy.

Thirty-eight women with beta-thalassaemia trait and thirty-five normal Asian women were studied retrospectively during normal pregnancies. The red cell size increased in both groups, with a mean increase of 2.3 fl (SD 2.3) in the women with beta-thalassaemia trait and a significantly higher increase of 4.3 fl (SD 2.1) in the normal Asian women. The rise in red cell size during pregnancy which is a physiological change, is thus impaired by defective globin-chain synthesis as well as by iron deficiency.

Erythrocyte Count↗
PubMed1981

Quinuronium sulphate for the treatment of Babesia divergens infections of splenectomised calves.

Quinuronium sulphate was inoculated into splenectomised calves at various times in relation to artificial infection of the calves with Babesia divergens. When the drug was given one day before the parasites it had no effect on the course of the infection. However, when it was given at the time of onset of fever or haemoglobinuria, development of the infection was arrested. Two weeks after therapy, recrudescences of parasites invariably occurred. In the case of animals treated at onset of fever these recrudescences were accompanied by increasing anaemia. Treated animals resisted subsequent challenge but remained as carriers of the parasite.

Animals↗
PubMed1981

DNA polymerase of a basidiomycete fungus, Coprinus cinereus.

DNA polymerase activity was studied in Coprinus cinereus, a basidiomycete fungus. Only one from of the enzyme could be demonstrated, whether by affinity or ion-exchange chromatography; this enzyme had a molecular weight of 185000 on Sephadex G-200, and was inhibited by mercaptoethanol. Coprinus, a representative of the most advanced type of the filamentous fungi, resembles other eukaryotic micro-organisms in its lack of a mammalian beta-type DNA polymerase. The properties of the polymerase are compared with those of two other fungi, and found to resemble most closely the yeast polymerase A in Mg2+ requirements and template preference.

Agaricales↗
PubMed1981

Field use of an irradiated blood vaccine to protect cattle against redwater (Babesia divergens infection) on a farm in Dorset.

A field trial was conducted in Dorset to determine whether calves could be protected against babesiosis by the prior inoculation of irradiated blood infected with Babesia divergens. The trial involved 99 Friesian heifers. Forty were inoculated with infected blood from a donor calf after the blood had been irradiated to a dose of 28 kilorads, 31 were immune animals which had grazed on the infected site the previous year and 28 were susceptible animals. After exposure on a hillside where there was a high risk of contracting the disease, 21 of 28 susceptible animals became clinically affected by redwater and required treatment whereas no animals in the other two groups were affected. It was shown that there was a 100 per cent risk of disease at the site and serological and haematological evidence corroborated the clinical results in demonstrating total protection of the vaccinated animals. Vaccination against redwater appears preferable to therapy, since vaccination before exposure on an infected pasture can replace frequent monitoring of the animals and subsequent therapy late in the course of the disease.

Animals↗
PubMed1981

Neurophysiological and biochemical properties of the goldfish optic tectum maintained in vitro.

The physiology and biochemistry of the in vitro goldfish optic tectum are examined. Following surgical removal of the intact optic tectum by severing its connectives, the tectal explant is maintained in a brain slice chamber in a specified medium for up to 24 hours. Electrophysiological studies show that the in vitro tectum displays the same response properties to optic nerve stimulation as does an in vivo tectum. Concurrent biochemical studies that RNA and protein synthesis is actively maintained for at least 17 hrs in vitro. Thus both biochemical and electrophysiological measurements indicate that the integrity of the tectal explant can be maintained in vitro making it a suitable model system for investigations of a variety of neurobiological questions.

Animals↗
PubMed1981

Investigations on a Babesia isolated from Scottish sheep.

The pathognomic, serologic and morphometric identity of a Babesia sp. recently isolated from sheep in Argyllshire was studied. Initially, problems were encountered due to the occurrence of Eperythrozoon ovis as a contaminant of the isolate and treatment with neoarsphenamine failed to remove it. Finally, a combination of oxytetracycline therapy and rapid passage allowed isolation of the Babesia sp. and its preservation in the form of a glycerolized, infected blood stabilate. Inoculation of the stabilate into splenectomized sheep produced a mile non-pyrogenic disease. Serologically the parasite was seen to have no affinity with either of the two Babesia recognized as parasitizing sheep, but some affinity with the cattle parasite B. divergens. Morphometrically it was seen to have affinity with the deer parasite B. capreoli and with the Babesia sp. isolated from red deer in Scotland, and the low number of budding forms of the parasite seen suggested that the parasite might be reproducing slowly in an alien host. It was concluded that the parasite was likely to be B. capreoli derived from red deer via the tick Ixodes ricinus.

Animals↗
PubMed1981

Case report. Atypical findings in adrenoleukodystrophy.

Computed tomography (CT) in a child with typical clinical and biochemical features of adrenoleukodystrophy (ALD) revealed striking pathologic enhancement in the centra semiovalia, posterior corpus callosum, and corticospinal tracts within the internal capsules, cerebral peduncles, and basis pontis. Central calcifications were detected within otherwise typical symmetrical low attenuation lesions in the periatrial white matter. These findings further expand the spectrum of CT abnormalities in ALD and may represent a link between the recently described Type 1 and Type 11 CT patterns.

Adrenal Glands↗
PubMed1981

Primary polycythaemia presenting with chorea.

A case of primary polycythaemia presenting with severe chorea is reported and compared with previous cases. The aetiological factors of the chorea are discussed and the importance of early diagnosis stressed.

Chorea↗
PubMed1981

Bilateral optic nerve hypoplasia.

In the past 10 years, 15 children with bilateral optic nerve hypoplasia have been studied at the Royal Alexandra Hospital for Children. There were 5 boys and 10 girls. Nine were first-born and they presented at a mean age of 5 months (range: 4 days to 25 months). Five presented with suspected blindness and 7 with abnormal eye movements (nystagmus or less commonly squint). The other 3 presented because of fits or developmental delay. Eight showed evidence of neural damage--microcephaly, seizures and/or abnormalities of tone. Four appeared to be of normal or near normal intelligence, 6 were mildly retarded and 5 severely so. Two patients had already died, one suddenly. Six of the 7 cases investigated in detail had evidence of hypothalamic pituitary dysfunction. Another one had a minimal hypothalamic abnormality. Four were severely growth retarded and 2 were receiving growth hormone replacement. Two males had micropenis and a girl had precocious puberty with partial diabetes insipidus. Neuroradiological investigations showed an absent septum pellucidum in only 5 cases. Five patients had other major CNS malformations. Five patients had normal CT scans; 3 of these 5 appeared of normal intelligence and all 5 had normal neurological examinations. Bilateral optic nerve hypoplasia is frequently associated with serious brain and endocrine abnormalities.

Brain↗
PubMed1981

Babesia divergens: combination of dead and live parasites in an irradiated vaccine.

Two experiments were carried out to investigate the hypothesis that the protective effect of an irradiated Babesia divergens vaccine was due to the combined inoculation of large numbers of dead parasites and small number of live ones. In the first experiment it was demonstrated that animals receiving 10(8) parasites irradiated at 25 kilorads had more severe B divergens reactions than animals in a previous experiment which had received 10(10) parasites irradiated at 24, 28 or 32 kilorads. In the second experiment it was shown that the simultaneous inoculation of 10(10) parasites killed by irradiation at 50 kilorads and 10(8) parasites irradiated at 25 kilorads resulted in the suppression of the relatively severe reactions induced by inoculation of the 25 kilorad-irradiated parasites alone. It was also shown that the simultaneous inoculation of 10(10) parasites irradiated at 50 kilorads and 10(4) live parasites similarly suppressed the anticipated reactions of the calves. These results indicated that the hypothesis was correct under the conditions of the experiment.

Animals↗