Showing papers by "Rajesh Kumar published in 1984"
TL;DR: It is concluded that an impaired ability of the aging kidney to synthesize 1,25(OH)2D could contribute to the pathogenesis of senile osteoporosis.
Abstract: Calcium absorption decreases with aging, particularly after age 70 yr. We investigated the possibility that this was due to abnormal vitamin D metabolism by studying 10 normal premenopausal women (group A), 8 normal postmenopausal women within 20 yr of menopause (group B), 10 normal elderly women (group C), and 8 elderly women with hip fracture (group D) whose ages (mean +/- SD) were 37 +/- 4, 61 +/- 6, 78 +/- 4, and 78 +/- 4 yr, respectively. For all subjects, serum 25-hydroxyvitamin D [25(OH)D] did not decrease with age, but serum 1,25-dihydroxyvitamin D [1,25(OH)2D], the physiologically active vitamin D metabolite, was lower (P = 0.01) in the elderly (groups C and D; 20 +/- 3 pg/ml) than in the nonelderly (groups A and B; 35 +/- 4 pg/ml). The increase of serum 1,25(OH)D after a 24-h infusion of bovine parathyroid hormone fragment 1-34, a tropic agent for the enzyme 25(OH)D 1 alpha-hydroxylase, correlated inversely with age (r = -0.58; P less than 0.001) and directly with glomerular filtration rate (r = 0.64; P less than 0.001). The response was more blunted (P = 0.01) in elderly patients with hip fracture (13 +/- 3 pg/ml) than in elderly controls (25 +/- 3 pg/ml). We conclude that an impaired ability of the aging kidney to synthesize 1,25(OH)2D could contribute to the pathogenesis of senile osteoporosis.
342 citations
01 Jan 1984
TL;DR: In this article, the authors investigated the possibility that abnormal vitamin D deficiency was due to abnormal deficiency of the enzyme 1,25-dihydroxyvitamin D (1,25(OH)2D), the phys- iologically active vitamin D metabolite, was lower (P = 0.58; P < 0.001) with age.
Abstract: Calcium absorption decreases with aging, particularly after age 70 yr. We investigated the possibility that this was due to abnormal vitamin D me- tabolism by studying 10 normal premenopausal women (group A), 8 normal postmenopausal women within 20 yr of menopause (group B), 10 normal elderly women (group C), and 8 elderly women with hip fracture (group D) whose ages (mean±SD) were 37±4, 61±6, 78±4, and 78±4 yr, respectively. For all subjects, serum 25-hydroxy- vitamin D (25(OH)D) did not decrease with age, but serum 1,25-dihydroxyvitamin D (1 ,25(OH)2D), the phys- iologically active vitamin D metabolite, was lower (P = 0.01) in the elderly (groupsC and D; 20±3 pg/ml) than in the nonelderly (groups A and B; 35±4 pg/ml). The increase of serum 1,25(OH)D after a 24-h infusion of bovine parathyroid hormone fragment 1-34, a tropic agent for the enzyme 25(OH)D la-hydroxylase, correlated in- versely with age (r = -0.58; P < 0.001) and directly with glomerular filtration rate (r = 0.64; P < 0.001). The re- sponse was more blunted (P = 0.01) in elderly patients with hip fracture (13±3 pg/ml) than in elderly controls (25±3 pg/ml). We conclude that an impaired ability of the aging kidney to synthesize 1,25(OH)2D could con- tribute to the pathogenesis of senile osteoporosis.
69 citations
TL;DR: A number of solid complexes of theophylline with CH 3 Hg 11, Hg11, as well as both CH 3Hg 11 and Hg 12, have been isolated from aqueous solution as the result of the reactions of theophiline and mercury-containing species at the appropriate pH and mole ratios of reactants.
24 citations
TL;DR: In this paper, the reaction of 8-thioguanosine (8-thioGuoH2) with methylmercury(II) has been shown to give rise to 1:1 (neutral and cationic), 1:2 and 1:3 (cationic) complexes, depending upon the reactant stoichiometry and pH.
22 citations
TL;DR: The influence of C-ring substituents on the biologic activity and protein binding properties of vitamin D3 has not been systematically investigated and dehydrogenated cholesta-5,7-dien-3 beta-ol to the 5,7,9(11)-triene to find that vitamin 8 increased calcium transport but failed to increase bone calcium mobilization at a dose as high as 50 000 pmol/rat.
Abstract: The influence of C-ring substituents on the biologic activity and protein binding properties of vitamin D3 has not been systematically investigated. To this end, we dehydrogenated cholesta-5,7-dien-3 beta-ol (1) to the 5,7,9(11)-triene. After protection of the 5,7-diene with a 4-phenyl-1,2,4- triazoline -3,5-dione Diels -Alder adduct, oxidation of the unprotected 9(11)-olefin gave epoxide 5. Reverse Diels -Alder and reductive ring opening of epoxide 5 gave cholesta-5,7-diene-3 beta, 11 alpha-diol (6). Photolysis of 6 to the previtamin followed by thermal rearrangement resulted in 11 alpha-hydroxyvitamin D3 (8). We found that vitamin 8 increased calcium transport at a dose of 500 pmol/rat but failed to increase bone calcium mobilization at a dose as high as 50 000 pmol/rat. Under the same conditions, corresponding doses of vitamin D3 and 25-hydroxyvitamin D3 increased bone calcium mobilization and intestinal calcium transport. The new vitamin analogue, 8, was slightly less efficient (B-50 = 6.8 X 10(-8) M) than 25-hydroxyvitamin D3, 24(R),25-dihydroxyvitamin D3, and 25-(S), 26-dihydroxyvitamin D3 (7.1 X 10(-9) M, 7.7 X 10(-9) M, and 7.9 X 10(-9) M, respectively) in displacing radiolabeled 25-hydroxyvitamin D3 from rat plasma vitamin D binding protein. On the other hand, vitamin analogue 8 showed significantly greater binding efficiency than 1 alpha-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, and vitamin D3 (B-50 = 2.5 X 10(-6) M, 9.84 X 10(-8) M, and 5.46 X 10(-7) M, respectively), under these same conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
19 citations
TL;DR: In this article, the interaction of MeHg(II) with xanthosine (Xanth H2, 1) in aqueous medium has been found to lead to several methylmercurated complexes depending on the reactant stoichiometries and the pH.
17 citations
TL;DR: Mesure de la susceptibilite magnetique d'amides par la methode de Gouy and a partir de calculs theoriques dans le but d'analyser les environnements structuraux and d'etablir une relation de χM avec les facteurs structuralaux χm s of ces molecules as mentioned in this paper.
Abstract: Mesure de la susceptibilite magnetique d'amides par la methode de Gouy et a partir de calculs theoriques dans le but d'analyser les environnements structuraux et d'etablir une relation de χM avec les facteurs structuraux χM s de ces molecules
13 citations
TL;DR: Observation chez un enfant de 14 ans qui s'etait fait une fracture du bras gauche en jouant au football.
Abstract: Observation chez un enfant de 14 ans qui s'etait fait une fracture du bras gauche en jouant au football
12 citations
TL;DR: In this paper, the reaction of mercuric acetate with N3-methylmercurated uridine, [CH3Hg(Uri), yielded a polymeric, dimethyl sulfoxide-soluble compound possessing a regular CHg-N bond system.
9 citations
TL;DR: Les results indiquent que les deplacements chimiques sont caracteristiques a la fois de la nature and de la structure du coordinat lie a Hg as discussed by the authors.
5 citations