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Biomedical subjects

J Blahos

Publications and source records attributed to J Blahos.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effect of low calcium and low phosphorus diets on duodenal and ileal absorption of phosphate in chick.

The duodenal and ileal absorption of 32P was studied by an in vivo method in control chicks and in chicks fed for 2 weeks a diet deficient in calcium or phosphorus. The results showed a highly significant increase in duodenal and ileal phosphate absorption in chicks fed a low calcium diet and a smaller, though also significant increase in duodenal but not ileal phosphate absorption in chicks fed a low phosphorus diet. The adaptation phenomenon concerning intestinal phosphorus absorption is presumably due in part to a compensatory increase in 1,25-dihydroxy-vitamin D3 in both deficient diets. However, much higher renal l-hydroxylase activity was found in chicks fed the low calcium diet than in chicks fed the low phosphorus diet. The results indicate that duodenal and ileal absorption of phosphate is a vitamin D mediated process, but the adaptation to a low phosphorus diet tends to be less efficient than that to a low calcium diet, especially in the ileum.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1985

The time sequence of adaptive changes to dietary phosphorus deficiency in the chick.

Ten-day old chicks were divided into 6 groups which were fed a low phosphorus (P) diet for periods of 0, 0.5, 1, 3, 7 or 11 days before killing at 3 weeks old. Labelled calcium (47Ca) was injected intraperitoneally into some birds 18 hours before killing. A marked fall in growth rate, plasma phosphorus level, plasma growth hormone level and renal 24-hydroxylase activity levels had occurred by 12 hours after the experimental diet had started. After one day on the diet, the rate of duodenal Ca absorption had risen and continued to rise up to the 11th day. During this period, the renal 25-hydroxyvitamin D-1-hydroxylase activity rose slightly while the 24-hydroxylase activity rose towards the control level. At 24 hours, the 47Ca level in the bone was markedly lower than in the control group and remained low. It was concluded that the first adaptive response of the chick to dietary P insufficiency was to suppress growth. Subsequent adaptive responses were to increase the rate of Ca and P absorption from the gut and mobilisation from the bone but despite these measures, the growth rate only recovered slightly and the plasma P level continued to fall.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1983

Verapamil increases adrenocortical secretory reserve.

The authors investigated the effect of commonly used therapeutic doses of calcium antagonist verapamil on the resting cortisol level and on the adrenocortical secretory reserve assessed from the response of cortisol blood level to stimulation with ACTH in 20 healthy subjects. Verapamil increased significantly the adrenocortical secretory reserve. The resting cortisol blood levels were not affected by the investigated substance. The authors discuss the possible practical impact of the assembled findings.

Adrenal Cortex↗
PubMed1983

The effect of betamethasone on duodenal calcium absorption and 1,25-dihydroxy vitamin D3 production in the chick.

Duodenal absorption of calcium, renal 25-hydroxycholecalciferol-1-hydroxylase activity, percentage bone ash, growth rate and plasma levels of Ca and P were all measured in chicks which had been treated with the synthetic glucocorticoid, betamethasone, at the therapeutic dose level of 25 microgram/kg daily. It was found that treatment for 2-3 weeks resulted in a significant reduction in Ca absorption rate, renal 1-hydroxylase activity and growth rate but an increase in bone ash and plasma Ca. If betamethasone was administered for 10 days and then stopped 4-13 days before these parameters were measured, a compensatory increase was found in 1-hydroxylase activity while the Ca absorption rate attained control values in all but the 4 day group in which it was still significantly depressed. It was concluded that a therapeutic dose level of betamethasone depresses both duodenal Ca absorption and renal 1-hydroxylase activity although there may be no direct causal relationship between these two parameters. Recovery was complete in 5-7 days after cessation of treatment.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1983

The effects of betamethasone, low calcium and low phosphorus diets on growth in chicks.

The effects of oral betamethasone (25 micrograms/kg/d), low calcium (1 g/kg), and low phosphorus (2,5 g/kg) diets on weight gain were investigated in 513 growing chicks. The chicks were divided according to initial weight into a lower weight group (less than 100 g each) and a higher group (more than 100 g each). The increases in weight were recorded after periods of 7, 14 and 21 days. The increases in weight in the older chicks (high weight group) were less than in the younger chicks. There was a greater reduction in rate of growth in chicks fed the low phosphorus diet than in those fed the low calcium diet, particularly in the older birds. Betamethasone administration also reduced the rate of growth but this was not additive to the effect of a low calcium diet. In contrast, the greatest reduction in growth rate was observed in the chicks fed the low phosphorus diet and given betamethasone.

Aging↗
PubMed1982

Effect of calcium antagonists on thyrotropin and thyroid hormone secretion.

The authors investigated the effect of one-week administration of verapamil in daily therapeutic doses of 4 X 40 mg by the oral route and the effect of nifedipine in daily therapeutic doses of 3 X 20 mg by the oral route. Verapamil and nifedipine did not affect significantly the levels of thyrotropin, triiodothyronine and thyroxine nor their response after stimulation with TRH. The theoretical and practical impact of this finding is discussed in particular with regard to possible side-effects of calcium antagonists during their therapeutic use in clinical cardiology.

Adolescent↗