An electron-microscope study of plasticized nitrocellulose

Ames, J.; Sampson, Avis M. D.

doi:10.1002/jbt.2570010803

Cited by 1 publication

(1 citation statement)

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“…Phosphorus analysis, by the method of Ames (1966), was done on the supernatant obtained by centrifugation (10OOOg for 10min) after precipitation of the plasma with 12.5 % (w/v) trichloroacetic acid. Typically 20,u1 of supernatant was used for phosphorus analysis.…”

Section: Calcium Andphosphorus Assaysmentioning

confidence: 99%

Vitamin D metabolism and expression in rats fed on low-calcium and low-phosphorus diets

Edelstein

Noff

et al. 1978

Biochemical Journal

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1. Cholecalciferol, radioactively labelled with both (14)C and (3)H, was administered weekly for 7 weeks to rats that had been depleted of vitamin D for 4 weeks before repletion with the radioactive vitamin. This permitted measurement of the steady-state effect on vitamin D metabolism of low-calcium and low-phosphorus regimens, as compared with a normal mineral intake. These dietary manoeuvres were carried out during the last 3 weeks of repletion. Cholecalciferol, 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol were determined in plasma, intestine, kidney and bone. Ca(2+)-binding-protein content was measured in intestine and kidneys of comparable animals. 2. In rats on the low-calcium diets, 1,25-dihydroxycholecalciferol concentration was elevated in plasma, bone, kidney and intestine, and intestinal Ca(2+)-binding protein was increased to over twice the concentration found in the control animals. 3. The low-phosphorus regimens led to a decrease in plasma phosphate and 1,25-dihydroxycholecalciferol in all tissues studied, for the latter to the point where it was undetectable in plasma and bone. Intestinal and renal concentrations of Ca(2+)-binding protein were unchanged in the low-phosphate-intake group and decreased in the very-low-phosphate-intake group. 4. It is concluded that in the rat, unlike in the chick, hypophosphataemia is not associated with a stimulation of the production of 1,25-dihydroxycholecalciferol or its expression in the synthesis of Ca(2+)-binding protein. Therefore the plasma phosphate concentration does not appear to be directly involved in the regulation of the functional metabolism of vitamin D.

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Section: Calcium Andphosphorus Assaysmentioning

confidence: 99%