Action non classique des androgenes (pTHrP et cancer de la prostate)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Effets des métabolites de la vitamine D 3

International audienc

Signaling Networks From Gbeta1 subunit to Transcription Factors and Actin Remodeling Via a Membrane-Located ERbeta-Related Protein in the Rapid Action of Daidzein in Osteoblasts

International audienc

Changes in plasma 1,25 and 24,25-dihydroxyvitamin D after renal transplantation in children

Changes in plasma 1,25- and 24,25-dihydroxyvitamin D after renal transplantation in children. The purpose of this investigation is to analyze changes in plasma 1,25-(OH)2D and 24,25-(OH)2D after successful renal transplantation in 20 children and young adults. Studies were performed on 8 subjects between the 1st and 10th month and on 12 others between the 20th and 30th to 36th month. Samples were assayed for plasma and urinary calcium, inorganic phosphate, creatinine, plasma bicarbonate, immunoreactive parathyroid hormone, 25-(OH)D, 24, 25-(OH)2D, and 1,25-(OH)2D concentrations. Results showed the following: (1) All subjects had normal or high plasma levels of dihydroxy-vitamin D metabolites. (2) In subjects with normal GFR's there was a significant inverse correlation between plasma 1,25 -(OH)2D and phosphate concentrations and between plasma 1,25-(OH)2D concentrations and tubular reabsorption of phosphorus. (3) These correlations were not found in subjects with subnormal creatinine clearances (50 to 100 ml/ min/1.73m2) even though plasma 1,25-(OH)2D concentrations in these subjects were similar to those with normal creatinine clearances. (4) In subjects with subnormal creatinine clearances, an increase in plasma 1,25-(OH)2D concentrations to very high levels was observed during the first months following renal transplantation.Evolution des concentrations plasmatiques de 1,25- et 24,25-dihydroxy-vitamine D après transplantation rénale chez l'enfant. Le but de ce travail a été d'analyser l'évolution des concentrations plasmatiques de 1,25-(OH)2D et de 24,25-(OH)2D après une transplantation rénale réussie chez 20 enfants et adultes jeunes. Huit sujets ont été étudiés entre le 1er et le 10e mois et 12 autres entre le 20è et le 30 à 36è mois. Les déterminations suivantes ont été obtenues: calcium plasmatique et urinaire, phosphate inorganique, créatinine, bicarbonate plasmatique, hormone parathyroïdienne immuno-réactive, concentration plasmatique de 25-(OH)D, 24,25-(OH)2D, et 1,25-(OH)2D. Les résultats ont montré que: (1) Tous les sujets avaient des concentrations plasmatiques normales ou élevées de métabolites dihydroxylés de la vitamine D. (2) Chez les sujets ayant des GFR's normaux il existait une corrélation inverse entre les concentrations plasmatiques de 1,25-(OH)2D et de phosphate et entre la concentration plasmatique de 1,25-(OH)2D et la réabsorption tubulaire du phosphate. (3) Ces corrélations n'ont pas été observées chez les sujets dont les clairances de la créatinine étaient inférieures à la normale (50 à 100 ml/min/1,73m2) bien que les concentrations plasmatiques de 1,25-(OH)2D de ces sujets étaient semblables celles des sujets dont les clairances de la créatinine étaient normales. (4) Chez les sujets dont les clairances de la créatinine étaient inférieures à la normale une augmentation très importante de la concentration plasmatique de 1,25-(OH)2D a été observée au cours des premiers mois consécutifs à la transplantation

In vivo and ex vivo effects of an isoflavone-rich diet on bone formation in growing pigs

National audienc

Dietary isoflavones act on bone marrow osteoprogenitor cells and stimulate ovary development before influencing bone mass in pre-pubertal piglets

International audienceFood containing soybeans provide isoflavone phytoestrogens that can preserve bone mass in postmenopausal women, and prevent bone loss in ovariectomized rats. But their effects on bone remain unclear, particularly on bone formation during growth. Two groups of eight pre-pubertal piglets were fed a basal or an isoflavone-enriched (S800) diet for 6 weeks. The S800 diet contained 800 mg SoyLife (TM) /kg, providing 2.8 mg isoflavones/kg body weight/day. Several bones were collected and tested for bone strength and density. Bone marrow was collected from humeri together with blood samples and genital tracts. The plasma concentrations of isoflavones were increased in the pigs fed S800, but growth rate, body weight, plasma bone markers, bone mineral density, and strength were all unaffected. In contrast, cultured stromal cells from S800 pigs had more alkaline phosphatase-rich cells and mineralized nodules, secreted more osteocalcin, osteoprotegerin and RANK-L, synthesized more osteoprotegerin, and RANK-L. Cultured mononucleated nonadherent bone marrow cells from S800 pigs developed fewer tartrate-resistant acid phosphatase mononucleated cells (osteoclast progenitors) when cultured with 1,25(OH)(2)D-3, and resorbed a smaller area of dentine slices. Freshly isolated bone marrow osteoclast progenitors from S800 pigs had more caspase-3 cleavage activity, and synthesized less RANK. Both osteoclast and osteoblast progenitors had ER alpha and ERP, whose syntheses were stimulated by the S800 diet. The S800 piglets had heavier ovaries with more follicles, but their uterus weight was unaffected. We conclude that dietary isoflavones have no detectable effect on the bone mass of growing female piglets, but act on bone marrow osteoprogenitors via ERs - mainly ER beta and stimulate ovary development