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Biomedical subjects

R H Wasserman

Publications and source records attributed to R H Wasserman.

At least 73 records · Page 4Linked to original sources
PubMed1979

Calcium absorption and intestinal calcium-binding protein: quantitative relationship.

The concentration of the vitamin D-induced calcium-binding protein (CaBP) and calcium absorption from the duodenum were investigated in chicks with an in vivo ligated-loop technique. The relation between CaBP and calcium absorption was dependent on a) source of vitamin D activity (either vitamin D3 or 1,25-dihydroxycholecalciferol); b) dosage of vitamin D3; c) time after administration of vitamin D3 to rachitic animals. To aid in the interpretation of these results, a phenomenological model was developed in which CaBP was viewed as being linearly related to a portion of calcium absorption. The model, when applied to the data, suggests that there is a "nonfunctional" pool of CaBP the size of which is determined by the vitamin D status of the animal. After correction for this nonfunctional pool, the proportionality between CaBP and calcium absorption is independent of the vitamin D status of the animal.

Animals↗
PubMed1979

Intestinal calcium-binding protein and calcium absorption in cortisol-treated chicks: effects of vitamin D3 and 1,25-dihydroxyvitamin D3.

Vitamin D3 in rachitic chicks stimulates calcium absorption and induces the synthesis of two pools of intestinal calcium-binding protein (CaBP), one soluble and the other membrane bound. Cortisol acetate caused a decrease in calcium absorption which was accompanied by a decrease in soluble CaBP. Cortisol was similarly effective in 1,25-dihydroxyvitamin D3-dosed chicks, suggesting that the glucocorticoid effect was not entirely due to the defective synthesis of this metabolite. Ca absorption was directly correlated with soluble CaBP and alkaline phosphatase and inversely related to the ratio of bound to soluble CaBP. It was further observed that the slope of the Ca absorption vs. soluble CaBP regression line was greater in chicks given 1,25-dihyroxyvitamin D3 compared to those given vitamin D3, and this is interpreted to mean that another factor or condition, in addition to assayed concentrations of soluble CaBP, determines the degree of calcium absorption.

Alkaline Phosphatase↗
PubMed1979

Intestinal calcium absorption and bone morphology in magnesium deficient chicks.

Calcium absorption was measured by 47Ca disappearance from ligated duodenal loops and 47Ca uptake by tibiae in chicks fed diets containing one of four levels of Mg for two weeks. The diets, otherwise identical, contained 88 (group 1), 150 (group 2), 200 (group 3) and 1000 (group 4) ppm Mg. There were no statistically significant differences in 47Ca absorption. Mucosal CaBP and intestinal alkaline phosphatase were slightly, but not significantly, elevated in the Mg depleted chicks in groups 1 and 2 compared to groups 3 and 4. Microscopic examination of the tibiae showed marked alterations in morphology in chicks fed the 88 ppm Mg diet. The thickness of the epiphyseal plate was reduced, and the morphologic signs of osteolysis and chondrolysis, normally observed in the metaphysis, appeared to be absent. The mid-diaphysis was thickened and showed marked reduction in both osteoblast and osteocytie activity. Blood calcium levels were significantly reduced in the Mg deficient chicks. It was concluded that Mg depletion in chicks altered Ca homeostasis primarily by changing bone structure and function.

Alkaline Phosphatase↗
PubMed1978

Evidence for a membrane-bound fraction of chick intestinal calcium-binding protein.

After homogenization of intestinal mucosa from vitamin D-replete chicks and high speed centrifugation, the major proportion of the vitamin D-induced calcium-binding protein is present in the supernatant fraction. However, the centrifugate, after repeated washing, contains significant amounts of bound calcium-binding protein that can be solubilized by Triton X-100. The bound calcium-binding protein is identical to soluble calcium-binding protein by the criteria of immunological identity, electrophoretic mobility, and molecular size, as determined by gel filtration chromatography. The bound calcium-binding protein is only partially released by sonication, osmotic shock or by ribonuclease treatment. Bound and soluble calcium-binding protein are not present in rachitic chick intestine. The addition of calcium-binding protein to rachitic mucosa prior to homogenization does not yield a Triton X-100 solubilizable form, indicating that bound calcium-binding protein in vitamin D-replete intestine is not due to adsorption or vesicular entrapment of soluble calcium-binding protein. The overall evidence suggests that part of the intestinal calcium-binding protein is membrane-bound.

Animals↗
PubMed1978

Stimulatory effect of 1,25-dihydroxycholecalciferol-like substances from Solanum malacoxylon and Cestrum diurnum on phosphate transport in chick jejunum.

Extracts of the calcinogenic plants Solanum malocoxylon and Cestrum diurnum stimulate phosphate absorption by the jejunum of vitamin D-deficient chicks, as determined by everted gut sac technique. Their action on cellular pathways of transepithelial phosphate transport is indistinguishable thereby from that of cholecalciferol. Increased net absorption from the lumen was due to enhanced uptake of phosphate from the luminal side, while leakage of tissue phosphate in the opposite direction was apparently unaffected. Steep serosa/mucosa concentration gradients were observed as consequence of enhanced levels of transepithelial phosphate flux in the mucosa-to-serosa direction. With respect to their stimulatory action on phosphate absorption, the calcinogenic plant factors retained their biological activity when phosphate transport was depressed by a high strontium diet. Their action in overcoming the strontium inhibition of phosphate absorption, calcium-binding protein synthesis, and alkaline phosphatase activity, was comparable to the effect of 1,25-dihydroxycholecalciferol. On the basis of these biological responses, the action of the plant factors from Solanum malacoxylon and Cestrum diurnum provides further evidence for their close resemblance to the hormonally active sterol.

Animals↗
PubMed1978

Bone changes induced by diphenylhydantoin in chicks on a controlled vitamin D intake.

Florid rickets developed in chicks receiving doses of diphenylhydantoin analogous to doses used in humans as anticonvulsants, vitamin D3 being given in amounts sufficient for normal bone mineralization in controls. The changes in the bones were directly related to the dose of diphenylhydantoin and inversely related to the dose of vitamin D3. Bone mineralization was assessed by roentgenography, histological examination, microradiography, and measurement of bone ash. Of these methods, roentgenography was the least sensitive. Rachitic changes were detectable by light microscopy and microradiography in chicks whose skeletons appeared normal roentgenographically. Roentgenographic evidence of rickets became detectable only when the rickets was far advanced. Rickets developed at serum levels of diphenylhydantoin similar to those found in patients taking anticonvulsant medication.

Animals↗
PubMed1977

Effect of vitamin D3 and 1,25-dihydroxyvitamin D3 on intestinal transport of phosphate.

Dietary variations (low calcium, low calcium, low phosphorus, or high strontium) change phosphate transport by the jejunum according to their respective ability to increase or block the synthesis of 1,25-dihydroxyvitamin D3, suggesting that the action of this active sterol underlies the response of intestinal phosphate absorption to vitamin D. 1,25-(OH)2D3 stimulates the active entry of Pi at the mucosal border by its action on protein synthesis. It is attractive to speculate that 1,25-(OH)2D3 might induce the synthesis of a "phosphate carrier" protein in the plasma membrane. The interpretation that the enhancement of the maximal velocity of the "phosphate pump" by vitamin D is due to the creation of new pump sites would be consistent with this hypothesis.

Anaerobiosis↗