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Active Vitamin D (active + vitamin_d)
Selected AbstractsErgocalciferol promotes in vivo differentiation of keratinocytes and reduces photodamage caused by ultraviolet irradiation in hairless micePHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2004Hiroaki Mitani Background: Ergocalciferol (VD2) is usually administered orally and it is metabolized to produce its biologically active metabolites in the liver and kidney. Active vitamin D is a well-known potent regulator of cell growth and differentiation. Purpose: Active vitamin D such as 1,25-dihydroxyvitamin D3 (1,,25(OH)2D3) prevents photodamage, including wrinkles and morphologic alterations. However, its clinical and cosmetic use is limited because of its potent, associated effect on calcium metabolism. We examined the efficacy of vitamin D analogues with few adverse effects for preventing skin photodamage. Method: Topical application of VD2 to hairless mouse dorsal skin, and exposure to solar-simulating ultraviolet (UV) radiation at a dose of 10.8 J/cm2 (UVA) were performed for 15 weeks, five times a week on weekdays. At the end of the final irradiation, histological and analytical studies were performed. Results: Topical application of VD2 significantly prevented wrinkle formation and abnormal accumulation of extracellular matrix components. In addition, VD2 suppressed excessive secretion of IL-6 induced by UV irradiation in cultured human normal keratinocytes, in a dose-dependent manner. Conclusion: VD2 promoted keratinocytes differentiation in the epidermis and showed diverse physiological effects, the same as the active form of VD3. The results suggested that the suppression of skin photodamage involved the promotion of keratinocytes differentiation and suppression of IL-6 secretion induced by exposure to UV. Topical application of VD2 may become an effective means to suppress solar UV-induced human skin damage. [source] Vitamin D Hormone Inhibits Osteoclastogenesis In Vivo by Decreasing the Pool of Osteoclast Precursors in Bone MarrowJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2002Takeshi Shibata Abstract Previous observations that vitamin D hormone induces the expression of the receptor activator of nuclear factor ,B (NF-,B) ligand (RANKL), thereby stimulating osteoclastogenesis in vitro, led to the widespread belief that 1,,25-dihydroxyvitamin D3 [1,,25(OH)2D3] is a bone-resorbing hormone. Here, we show that alfacalcidol, a prodrug metabolized to 1,,25(OH)2D3, suppresses bone resorption at pharmacologic doses that maintain normocalcemia in an ovariectomized (OVX) mouse model of osteoporosis. Treatment of OVX mice with pharmacologic doses of alfacalcidol does not increase RANKL expression, whereas toxic doses that cause hypercalcemia markedly reduce the expression of RANKL. When bone marrow (BM) cells from OVX mice were cultured with sufficient amounts of macrophage colony-stimulating factor (M-CSF) and RANKL, osteoclastogenic activity was higher than in sham mice. Marrow cultures from alfacalcidol- or estrogen-treated OVX mice showed significantly less osteoclastogenic potential compared with those from vehicle-treated OVX mice, suggesting that the pool of osteoclast progenitors in the marrow of vitamin D-treated mice as well as estrogen-treated mice was decreased. Frequency analysis showed that the number of osteoclast progenitors in bone marrow was increased by OVX and decreased by in vivo treatment with alfacalcidol or estrogen. We conclude that the pharmacologic action of active vitamin D in vivo is to decrease the pool of osteoclast progenitors in BM, thereby inhibiting bone resorption. Because of its unusual activity of maintaining bone formation while suppressing bone resorption, in contrast to estrogens that depress both processes, vitamin D hormone and its bone-selective analogs may be useful for the management of osteoporosis. [source] Cost of renal replacement therapy in TurkeyNEPHROLOGY, Issue 1 2004EKREM EREK SUMMARY: Background and Results: By the end 2000, 22 224 patients were on renal replacement therapy (RRT) in Turkey. We investigated the cost of RRT in three medical faculties and one private dialysis centre. Yearly expenses were US$22 759 for haemodialysis (HD), US$22 350 for continuous ambulatory peritoneal dialysis (CAPD), and US$23 393 and US$10 028, respectively, for the first and second years of transplantation (Tx). In the first year, renal Tx was significantly more expensive than CAPD. However, after the first year of renal transplantation, Tx became significantly more economical than both CAPD and HD. The sum of all yearly RRT expenses for the country was US$488 958 709, which corresponds to nearly 5.5% of Turkey's total health expenditure. Conclusion: Measures such as early construction of vascular access, promoting home dialysis and the reuse of the dialysers, strict control of the use of some expensive drugs like erythropoietin and active vitamin D, and also increasing the number of transplantations, especially if pre-emptive transplantation is possible, should be taken into account in order to reduce these expenses. [source] PODOCYTE INJURY IS SUPPRESSED BY 1,25-DIHYDROXYVITAMIN D3 VIA MODULATION OF TRANSFORMING GROWTH FACTOR-,1/BONE MORPHOGENETIC PROTEIN-7 SIGNALLING IN PUROMYCIN AMINONUCLEOSIDE NEPHROPATHY RATSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2009Hou-Qin Xiao SUMMARY 1Accumulating evidence suggests that vitamin D and its analogues are renoprotective. However, the precise mechanisms and the molecular targets by which active vitamin D exerts its beneficial effects remain obscure. The objective of the present study was to evaluate the effect of active vitamin D on rats with puromycin aminonucleoside (PAN) nephropathy, a model that is characterized by predominant podocyte injury. 2The PAN nephropathy rats were created by a single intravenous injection of 100 mg/kg PAN. Changes in renal pathology and podocyte numbers were observed. Real-time polymerase chain reaction (PCR) was performed to examine mRNA expression of nephrin, transforming growth factor (TGF)-,1 and bone morphogenetic protein (BMP)-7. Protein expression of nephrin, TGF-,1, BMP-7 and p-Smad2/3 and p-Smad1/5/8 was examined by immunofluorescence, immunohistochemistry and western blotting, respectively. Rats were treated with 1,25(OH)2D3 by gastric gavage at a dose of 2.5 µg/kg per day, starting 2 days before PAN injection and continuing throughout the experiment. 3A single injection of PAN induced massive proteinuria and elevated serum creatinine on Day 7, both of which were significantly suppressed by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Immunofluorescence and real-time PCR of the podocyte-associated protein nephrin revealed reduced and discontinuous staining and this change was reversed by 1,25(OH)2D3. In PAN nephropathy rats, TGF-,1 and p-Smad2/3 expression was upregulated, whereas that of BMP-7 and p-Smad1/5/8 was downregulated. Treatment with 1,25(OH)2D3 significantly restored BMP-7/Smad signalling while suppressing TGF-,1/Smad signalling. 4In conclusion, 1,25(OH)2D3 can ameliorate podocyte damage and proteinuria induced by PAN. The beneficial effects of 1,25(OH)2D3 on podocytes may be attributable, in part, to direct modulation of TGF-,1/BMP-7 signalling. 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