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Biomedical subjects

T G Taylor

Publications and source records attributed to T G Taylor.

At least 19 recordsLinked to original sources
PubMed1991

The effects of dietary levels of inorganic phosphorus, calcium and cholecalciferol on the digestibility of phytate-P by the chick.

Male broiler chicks (1-d-old; Ross one) were given either a control diet containing recommended levels of phosphorus, calcium and cholecalciferol or experimental diets low in P and with variable levels of Ca (normal and low) and cholecalciferol (normal or high). The low-P diet with normal levels of Ca and cholecalciferol induced a hypophosphataemia and a hypercalcaemia which was reflected in reduced tibia length and weight and in reduced Ca, P and magnesium contents of tibia. The phytate digestibility remained normal while the retention of P and Ca fell significantly. The lowering of Ca alone elevated phytate digestibility and restored P and Ca retention. The hypercalcaemia and hypophosphataemia remained and tibia mineralization remained impaired. The raising of cholecalciferol alone dramatically increased phytate digestibility and the retention of Ca and P. While this remedied the hypercalcaemia, the hypophosphataemia persisted as did the diminution of tibia weight. The simultaneous lowering of dietary Ca and elevation of cholecalciferol on low-P diets restored all variables to the levels for the control diet. Circulating levels of 1,25-dihydroxycholecalciferol were significantly elevated by low-P diets, more so with high cholecalciferol intakes. However, Ca did not influence 1,25-dihydroxycholecalciferol levels in plasma.

Animals↗
PubMed1979

The metabolism of cholecalciferol in the liver of Japanese quail (Coturnix coturnix japonica) with particular reference to the effects of oestrogen.

1. Studies were carried out in vitro with the livers of Japanese quail that had been fed from hatching on diets supplying their full requirements for vitamin D. 2. 25-Hydroxycholecalciferol was the major metabolite when liver homogenates of egg-laying female and oestrogen-treated quail of both sexes were incubated with [3H]cholecalciferol. 3. Very little 25-hydroxycholecalciferol was generated from liver homogenates of adult male and immature quail. Instead the cholecalciferol was converted into one or more compounds less polar than 25-hydroxycholecalciferol and into a number of highly polar metabolites, some of which were water-soluble. 4. Oestrogen not only stimulated the 25-hydroxylation of cholecalciferol but also protected both cholecalciferol and 25-hydroxycholecalciferol from degradation by the enzymic pathways active in immature and male birds. 5. These actions of oestrogen may be of physiological significance in relation to the high requirements of laying birds for 1,25-dihydroxycholecalciferol to support the intense metabolism of calcium associated with egg-shell calcification.

Aging↗
PubMed1979

Hair chromium concentrations in adult insulin-treated diabetics.

Hair chromium concentrations have been measured in age- and sex-matched groups of insulin-treated diabetics and normal controls. Average concentration (+/- S.E.M.) was reduced in female (2.9 +/- 0.5 compared with 5.1 +/- 0.7 nmol/g) but not in male diabetics.

Adolescent↗
PubMed1979

A comparative study of the absorption of calcium and the availability of phytate-phosphorus in the golden hamster (Mesocricetus auratus) and the laboratory rat.

1. Balance studies were carried out with rats and golden hamsters (Mesocricetus auratus) given diets high and low in calcium (10.8 and 5.1-5.2 g Ca/kg respectively) and high and low in phytate (3.4 and 1.6 g phytate-phosphorus/kg respectively) in a 2 X 2 factorial experiment. 2. Values for Ca absorption and phytate availability (relative to the amount ingested) and for urinary excretion of Ca and P were significantly higher in the hamster than in the rat for all four diets. 3. Phytate availability was significantly greater on the low-Ca than on the high-Ca diets with both species. 4. Ca absorption was greater on the low-phytate than on the high-phytate diets but the differences were significant only for the hamster. 5. Absorption of both Ca and P was poorly controlled in the hamster compared to the rat.

Animals↗
PubMed1979

The relationship between protein turnover and energy balance in lean and genetically obese (ob/ob) mice.

1. Groups of lean and genetically obese (ob/ob) mice were adapted to varying energy intakes and the rates of total protein turnover in liver, gut and kidney were measured. 2. Lean mice gained less weight when fed above maintenance and lost less weight when fed below maintance than obese mice. 3. Hepatic protein turnover (mg/d) was sigmoidally related to digestible energy intake in lean mice but showed no significant changes with dietary intake in obese mice. 4. The changes in protein turnover resulted from changes in both the half-lives of protein synthesis and catabolism and in tissue protein content. 5. In the lean mice, protein turnover in kidney and gut was not significantly changed with increasing energy intake until the highest level was reached. 6. The findings suggest that protein turnover may be an important cycle for the regulation of energy balance in mice and that this cycle is impaired in the genetically obese (ob/ob) mice.

Animals↗
PubMed1979

Concentration of zinc in the hair of schoolchildren.

The concentration of zinc in the hair of 219 schoolchildren aged between 10 and 11 years was measured and related to height, weight, estimates of consumption of zinc-rich foods, number of children living at home, and rank in family. None of the correlation coefficients between hair zinc and the other variables was significant. Mean concentration of zinc was higher (P less than 0.001) in the girls (146 microgram/g; 2.23 mumol/g) than in the boys (118 microgram/g; 1.81 mumol/g). Eight children (3.7% of the total) had less than 75 microgram/g (less than 1.15 mumol/g) zinc in their hair but only one of them was below the 10th centile for height or weight--a girl with coeliac disease.

Birth Order↗
PubMed1978

Platelet aggregation in rats in relation to hyperuricaemia induced by dietary single-cell protein and to protein deficiency.

A major limitation to single-cell protein (SCP) as a human food is its high nucleic acid content, the purine moiety of which is metabolised to uric acid. Rats given a Fusarium mould as a source of SCP in diets containing oxonate, a uricase inhibitor, showed elevated plasma and kidney uric acid concentrations after 21 d, which were related to the level of dietary mould. ADP-induced and thrombin-induced platelet aggregation was greater in the hyperuricaemic rats than in controls and a progressive increase in aggregation with increasing levels of dietary mould was observed. Furthermore a time-lag, exceeding the life-span of rat platelets, was observed between the development of hyperuricaemia and the increase in aggregation. A similar time-lag was observed between the lowering of the hyperuricaemia and the reduction of platelet aggregation when oxonate was removed from the diet. If human platelets react to uric acid in the same manner as rat platelets this might explain the link that has been suggested between hyperuricaemia and ischaemic heart disease. In that event diets high in nucleic acids might be contra-indicated in people at risk from ischaemic heart disease. In rats given a low protein diet (50 g casein/kg) for 21 d ADP-induced and thrombin-induced platelet aggregation and whole blood platelet count were reduced compared with control animals receiving 200 g casein/kg diet but not in rats given 90 or 130 g casein/kg diet. A study of the time course on this effect indicated that the reduction both in aggregation tendency and in whole blood platelet count occurred after 4 d of feeding the low protein diet. These values were further reduced with time.

Animals↗
PubMed1978

A new technique for measuring protein turnover in the gut, liver and kidneys of lean and obese mice with [3H] glutamic acid.

1. We have measured the incorporation of an intraperitoneal injection of [3H] glutamate into the protein of the gut, liver and kidney of lean and obese siblings of the genetically obese mouse. 2. Recycling of the 3H was minimized by using glutamate labelled at the C-2 position. Loss of label from the amino acid pool by transamination and deamination was rapid, with a half-life of 4 h. 3. In tissue protein the amino acid showing the highest 3H radioactivity was glutamate. 4. The half-lives for protein synthesis and catabolism were calculated from the decay curves of both specific and total radioactivity of [3H] glutamate in tissue protein. No significant differences were found between kidney, liver and gut in lean and obese mice.

Animals↗
PubMed1977

An improved method for the microbiological assay of available amino acids in proteins using Tetrahymena pyriformis.

1. A standard microbiological procedure for the assay of available amino acids in proteins using Tetrahymena pyriformis has been modified by evaluating cell growth from the tetrahymanol content of the cultures by gas-liquid chromatography (GLC). 2. This modification improves the precision of the method compared with cell-counting techniques and provided automatic injection facilities are available for the GLC, the procedure is not excessively time-consuming. 3. It has been confirmed that enzymic predigestion is essential for all except the most soluble proteins and a satisfactory method using pronase has been incorporated into the microbiological procedure. 4. After enzymic digestion of the sample, growth of Tetrahymena with many proteins can be measured turbidimetrically, but particulate matter still persists with a proportion of samples, particularly those of plant origin, and the GLC method is therefore more widely applicable. It is also more precise. 5. Good agreement has been obtained between a chick bioassay and the modified Tetrahymena assay for available lysine in eight different proteins, including heat-damaged fish meals. 6. The modified procedure appeared to give good results for available tryptophan and methionine. 7. When cystine was omitted from the standard culture medium it was possible to test for available methionine plus cystine, but further work is required to assess the reliability of this particular assay.

Amino Acids↗
PubMed1977

The effects of ergosterol on the response of female chicks to oral oestrogens and progestogens.

The chick-oviduct assay was used to investigate the effects of dietary ergosterol on the response to oral progestogens and oestrogens. 2. Progestogens alone had no effect on the oviduct but the hypertrophy due to oestrogen was greatly enhanced by simultaneous treatment with progestogen at all dose levels tested. 3. Ergosterol had no effect on any of the responses of the oviduct studied.

Animals↗