The Effect of DDT on Vitamin D Metabolism and Calcium Binding Activity in the Chick

1977 ◽  
pp. 313-314
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Binding Activity ◽  
Vitamin D Metabolism

scholarly journals Vitamin D metabolism and its possible role in the developing chick embryo

1981 ◽  
Vol 194 (1) ◽  
pp. 103-109 ◽  
Author(s):  
M Kubota ◽  
E Abe ◽  
T Shinki ◽  
T Suda
Keyword(s):  
Vitamin D ◽  
Chick Embryo ◽  
Bone Formation ◽  
Calcium Binding ◽  
Calcium Absorption ◽  
Chorioallantoic Membrane ◽  
Calcium Content ◽  
Binding Activity ◽  
Vitamin D Metabolism ◽  
Osteoblastic Activity

The relationship between bone formation and vitamin D metabolism was investigated in the developing chick embryo. Fertilized White Leghorn eggs were incubated at 38 degrees C in an incubator for 21 days. The fresh weight and calcium content of embryonic tibiae began to increase at day 12 and attained maximal values at day 19. Bone alkaline phosphatase and citrate decarboxylation activities, both of which represent osteoblastic activity, also began to increase at days 10-12, reached maximal values at day 19 and sharply declined thereafter. Both bone enzyme activities were highly correlated with CA2+-binding activity in the chorioallantoic membrane measured by the Chelex 100 assay. When mesonephric and metanephric homogenates were incubated with 25-hydroxy[3H]cholecalciferol, a marked and concomitant increase occurred in the metanephric 1 alpha- and 24-hydroxylase activity after day 14. The production of 1 alpha, 25-dihydroxycholecalciferol attained a maximal value at day 19 and decreased thereafter, whereas that of 24,25-dihydroxycholecalciferol continued to increase until hatching. The production rate of 1 alpha, 25-dihydroxycholecalciferol by the metanephros coincided with the changes in Ca2+-binding activity in the chorioallantoic membrane and osteoblastic activity. Since both intestinal calcium absorption and bone mineral mobilization do not occur in embryonic life, these results support the idea that 1 alpha, 25-dihydroxycholecalciferol may be involved directly in bone formation or induction of a calcium-binding protein in the chorioallantoic membrane.

Vitamin D-dependent, particulate calcium-binding activity and intestinal calcium transport

1975 ◽  
Vol 229 (5) ◽  
pp. 1198-1204 ◽  
Author(s):  
S Kowarski ◽  
D Schachter
Keyword(s):  
Vitamin D ◽  
Brush Border ◽  
Calcium Binding ◽  
Protein Complexes ◽  
Gel Filtration ◽  
Binding Activity ◽  
Particulate Fraction ◽  
Small Intestinal Mucosa ◽  
Mucosal Cells ◽  
Triton X

A vitamin D-dependent calcium-binding activity of relatively high molecular weight has been identified in the particulate fraction of rat small intestinal mucosa. The Ca-binding activity is sedimented at 140,000 X g after treatment of the mucosal particulate fraction with Triton X-114. Intestinal brush-border suspensions can also be used as starting material. The Ca-binding component is inactivated by heat and repeated freeze-thawing and consists of one or more protein complexes in the range of 0.5-1.0 million mol wt as indicated by gel filtration. The Ca-binding activity correlates positively with known features of the intestinal Ca transport mechanism, as demonstrated by studies of the distribution in the small intestine and the effects of vitamin D, dietary Ca, cycloheximide treatment, and rat age. It is suggested that the component might function in the transit of Ca across the brush-border surface to the cytosol of intestinal mucosal cells.

scholarly journals Calcium-binding protein and vitamin D metabolism in experimental protein malnutrition

1974 ◽  
Vol 32 (3) ◽  
pp. 569-578 ◽  
Author(s):  
W. J. Kalk ◽  
B. L. Pimstone
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Protein Deprivation ◽  
Vitamin D Metabolism ◽  
Renal Metabolism ◽  
Acid Substrate ◽  
Amino Acid Substrate ◽  
25 Hydroxycholecalciferol

1. Intestinal and renal vitamin D-dependent calcium-binding protein (CaBP) activity and cholecalciferol metabolism were investigated in the protein-deficient rat (40 g casein/kg diet) and in control animals (200 g casein/kg diet). Compared to control animals, 3 weeks of protein deprivation resulted in consistently reduced intestinal CaBP activity, while renal CaBP activity was not significantly altered.2. Intestinal CaBP activity was greatly reduced in rats fed on diets deficient in both protein and vitamin D. CaBP activity was doubled by cholecalciferol administration, but did not reach control values. The rate of conversion of intravenously injected [3H]cholecalciferol to 25-hydroxycholecalciferol (25-HCC) and the disappearance rates of plasma 25-HCC were similar in the two groups of animals.3. It is concluded that in the protein-deficient rat: (a) intestinal CaBP activity is reduced; (b) coexistent vitamin D deficiency reduces intestinal CaBP activity still further, but the intestinal mucosa retains the potential to respond to administered cholecalciferol: (c) hepatic and probably renal metabolism of cholecalciferol appear to be normal; (d) reduced CaBP is likely to be the result of reduced CaBP synthesis as a consequence of deficient amino acid substrate.

scholarly journals Vitamin D metabolism and mechanisms of calcium transport.

1990 ◽  
Vol 1 (1) ◽  
pp. 30-42
Author(s):  
R Kumar
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Active Form ◽  
Biologically Active ◽  
Vitamin D Metabolism ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Magnesium Atpase ◽  
Liver And Kidney ◽  
Calcium Magnesium

Vitamin D3 undergoes sequential hydroxylations in the liver and kidney to form 1,25-dihydroxyvitamin D3, the biologically active form of the vitamin. 1,25-dihydroxyvitamin D3 is metabolized by several processes in various target tissues that decrease the biological activity of the sterol. In addition, 1,25-dihydroxyvitamin D3 is excreted in the bile as polar metabolites, such as glucuronides and, possibly sulfates and neutral polar steroids. These compounds undergo an enterohepatic recirculation in both man and experimental animals. 1,25-dihydroxyvitamin D3 increases the absorption of calcium in the intestine and the reabsorption of calcium in the kidney. It induces the synthesis of several proteins, the most notable of which is calcium binding protein that is thought to play a role in the absorption of calcium. The vitamin D-dependent calcium binding proteins and the calcium-magnesium ATPase calcium pump are co-localized in several tissues that play a role in the absorption of calcium.

Novel Mineral Regulatory Pathways in Ovine Pregnancy: II. Calcium Binding Proteins, Calcium Transporters, and Vitamin D Signaling

2021 ◽  
Author(s):  
Claire Stenhouse ◽  
Katherine M Halloran ◽  
Makenzie G Newton ◽  
Dana Gaddy ◽  
Larry J Suva ◽  
...  
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Potential Role ◽  
Allantoic Fluid ◽  
Vitamin D Metabolism ◽  
Regulatory Pathways ◽  
Placental Transport ◽  
Mechanistic Investigation ◽  
Vitamin D Signaling

Abstract Mineralization of the fetal mammalian skeleton requires a hypercalcemic gradient across the placenta from mother to fetus. However, the mechanisms responsible for maintaining the placental transport of calcium remain poorly understood. This study aimed to identify calcium and vitamin D regulatory pathway components in ovine endometria and placentae across gestation. Suffolk ewes were bred with fertile rams upon detection of estrus (Day 0). On Days 9, 12, 17, 30, 70, 90, 110, and 125 of pregnancy (n = 3–14/Day), ewes were euthanized and hysterectomized. Calcium abundance was influenced by gestational day in uterine flushings and allantoic fluid (P < 0.05). The expression of S100G, S100A9, S100A12, ATP2B3, ATP2B4, TRPV5, TRPV6, CYP11A1, CYP2R1, CYP24, and VDR mRNAs known to be involved in calcium binding, calcium transport, and vitamin D metabolism were quantified by qPCR. Mediators of calcium and vitamin D signaling were expressed by Day 17 conceptus tissue, and endometria and placentae across gestation. Gestational day influenced the expression of S100G, S100A9, S100A12, TRPV6, VDR, and CYP24 mRNAs in endometria and placentae (P < 0.05). Gestational day influenced endometrial expression of ATP2B3, and placental expression of TRPV5, ATP2B4, and CYP11A1 (P < 0.05). VDR protein localized to the endoderm and trophectoderm (Day 17 conceptus) and was expressed in endometria and placentae throughout gestation. The observed spatiotemporal profile suggests a potential role of calcium and vitamin D in the establishment of pregnancy and regulation of fetal and placental growth, providing a platform for further mechanistic investigation.

Persistent HCV-infection and liver damage change vitamin-D-metabolism

2012 ◽  
Vol 50 (01) ◽  
Author(s):  
A Amanzada ◽  
A Lindhorst ◽  
F Moriconi ◽  
M Blaschke ◽  
T Suermann ◽  
...  
Keyword(s):  
Vitamin D ◽  
Liver Damage ◽  
Hcv Infection ◽  
Vitamin D Metabolism
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