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Your search keyword '"Bolt, Merry J.G."' showing total 11 results
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11 results on '"Bolt, Merry J.G."'

1. Critical role of vitamin D in sulfate homeostasis: regulationof the sodium-sulfate cotransporter by 1,25-dihydroxyvitamin [D.sub.3]

Author

Bolt, Merry J.G., Liu, Wenhua, Qiao, Guilin, Kong, Juan, Zheng, Wei, Krausz, Thomas, Cs-Szabo, Gabriella, Sitrin, Michael D., and Li, Yan Chun

Subjects
Vitamin D -- Research, Homeostasis -- Research, Alfacalcidol -- Research, Calcifediol -- Research, Biological sciences
Abstract

Critical role of vitamin D in sulfate homeostasis: regulation of the sodium-sulfate cotransporter by 1,25-dihydroxyvitamin [D.sub.3]. Am J Physiol Endocrinol Metab 287: E744-E749, 2004. First published May 27, 2004; 10.1152/ajpendo.00151.2004.--As the fourth most abundant anion in the body, sulfate plays an essential role in numerous physiological processes. One key protein involved in transcellular transport of sulfate is the sodium-sulfate cotransporter NaSi-1, and previous studies suggest that vitamin D modulates sulfate homeostasis by regulating NaSi-1 expression. In the present study, we found that, in mice lacking the vitamin D receptor (VDR), NaSi-1 expression in the kidney was reduced by 72% but intestinal NaSi-1 levels remained unchanged. In connection with these findings, urinary sulfate excretion was increased by 42% whereas serum sulfate concentration was reduced by 50% in VDR knockout mice. Moreover, levels of hepatic glutathione and skeletal sulfated proteoglycans were also reduced by 18 and 45%, respectively, in the mutant mice. Similar results were observed in VDR knockout mice after their blood ionized calcium levels and rachitic bone phenotype were normalized by dietary means, indicating that vitamin D regulation of NaSi-1 expression and sulfate metabolism is independent of its role in calcium metabolism. Treatment of wild-type mice with 1,25-dihydroxyvitamin [D.sub.3] or vitamin D analog markedly stimulated renal NaSi-1 mRNA expression. These data provide strong in vivo evidence that vitamin D plays a critical rote in sulfate homeostasis. However, the observation that serum sulfate and skeletal proteoglycan levels in normoealcemic VDR knockout mice remained low in the absence of rickets and osteomalacia suggests that the contribution of sulfate deficiency to development of rickets and osteomalacia is minimal. vitamin D receptor; sulfate

Published
2004

3. Intestinal absorption of cholecalciferol and 25-hydroxycholecalciferol in patients with both Crohn's disease and intestinal resection

Author

Leichtmann, Georges A., Bengoa, Jose M., Bolt, Merry J.G., and Sitrin, Michael D.

Subjects
Intestinal absorption -- Evaluation, Crohn's disease -- Health aspects, Vitamin D deficiency -- Causes of, Food/cooking/nutrition, Health
Abstract

Crohn's disease causes inflammation in the small intestine and colon, and can impair the absorption of dietary nutrients in the intestines. Vitamin D deficiency is a common nutritional problem in patients with this disease. A study was performed to compare the intestinal absorption of two different forms of vitamin D, cholecalciferol and 25-hydroxycholecalciferol, in patients with Crohn's disease who also had bowel resections. The study included 12 patients with Crohn's disease and four healthy volunteers. Patients with Crohn's disease were divided into three groups (short, intermediate and long) based on the amount of intestine that was removed during the bowel resection. Each subject was given a beverage containing one of the two forms of vitamin D. Both forms of vitamin D were labeled with tritium (radioactive hydrogen); the amount of vitamin D absorbed in the intestines was determined by measuring the amount of radioactive vitamin D in the blood. Overall, the absorption of vitamin D was less in patients with Crohn's disease than in the healthy volunteers. In the patients with Crohn's disease, more 25-hydroxycholecalciferol was absorbed than cholecalciferol. Also, the amount of vitamin D absorbed decreased as the size of the bowel resection increased. These findings indicate that vitamin D absorption is impaired in patients with Crohn's disease and that the degree of malabsorption correlates with the amount of intestine removed during bowel resection. Vitamin D supplements in the form of 25-hydroxycholecalciferol may be preferred for patients with the larger bowel resections. (Consumer Summary produced by Reliance Medical Information, Inc.)

Published
1991

9. Effects of vitamin D receptor inactivation on the expression of calbindins and calcium metabolism.

Author

Yan Chun Li, Bolt, Merry J.G., Li-Ping Cao, and Sitrin, Michael D.

Subjects
*VITAMIN D, *CALCIUM metabolism
Abstract

Investigates the effects of vitamin D receptor (VDR) inactivation on the expression of calbindins and calcium metabolism. Effect of VDR inactivation on expression of CaBP in intestine and kidney; Effect of age on expression of CaBP in VDR(-/-) and wild-type mice.

Published
2001

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