Página 1 dos resultados de 9344 itens digitais encontrados em 0.074 segundos

‣ Treatment of vitamin D deficiency increases lower limb muscle strength in institutionalized older people independently of regular physical activity: a randomized double-blind controlled trial

Moreira-Pfrimer, Linda D. F.; Pedrosa, Marcia A. C.; Teixeira, Luzimar; Lazarettu-Castro, Marise
Fonte: KARGER Publicador: KARGER
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
77.217485%
Aims: To investigate the effects of a 6-month supplementation with calcium and cholecalciferol on biochemical parameters and muscle strength of institutionalized elderly. Methods: This prospective, double-blind, placebo-controlled, randomized trial included Brazilian institutionalized people 6 60 years of age receiving a 6-month supplementation ( December to May) of daily calcium plus monthly placebo (calcium/placebo group) or daily calcium plus oral cholecalciferol (150,000 IU once a month during the first 2 months, followed by 90,000 IU once a month for the last 4 months; calcium/vitamin D group). Fasting blood samples for 25-(OH) D, PTH and calcium determination were collected (n = 56) and muscle tests were performed ( n = 46) to measure the strength of hip flexors (SHF) and knee extensors (SKE) before ( baseline) and after the 6-month intervention ( 6 months). Results: Due to seasonal variations, serum 25( OH) D significantly enhanced in both groups after treatment, but the calcium/vitamin D group had significantly higher 25-(OH) D levels than the calcium/placebo group (84 vs. 33%, respectively; p < 0.0001). No cases of hypercalcemia were observed. While the calcium/placebo group showed no improvement in SHF and SKE at 6 months (p = 0.93 and p = 0.61...

‣ Vitamin D status in a sunny country: Where has the sun gone?

UNGER, Marianna D.; CUPPARI, Lilian; TITAN, Silvia M.; MAGALHAES, Maria Claudia T.; SASSAKI, Ana L.; REIS, Luciene M. dos; JORGETTI, Vanda; MOYSES, Rosa Maria Affonso
Fonte: CHURCHILL LIVINGSTONE; AMSTERDAM Publicador: CHURCHILL LIVINGSTONE; AMSTERDAM
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
77.107964%
Background & aims: Hypovitaminosis D [serum 25 vitamin D < 30 ng/ml] is related to the development of metabolic bone disease and greater risk of chronic illnesses. However, it is frequently under-diagnosed, mainly in countries where UV radiation is abundant. We prospectively determined the prevalence and the predictors of serum 25 vitamin D (s25(OH)D) in a healthy Brazilian population after the winter and after the summer. Methods: 603 (118M and 485F) healthy Brazilian volunteers aged 18-90 years from a universitary hospital were selected after the winter of 2006. From the initial sample, 209 volunteers (31M and 178F) accepted to participate in a second health check after the subsequent summer. Results: After the winter, median s25(OH)D was 21.4 ng/mL and 77.4% of the population presented hypovitaminosis D. s25(OH)D was significantly related to age, BMI, PTH and race. In multivariate linear regression analysis, s25(OH)D was significantly and independently dependent on age, glycemia and skin color. Significant increase in s25(OH)D was verified after summer [10.6 (3.7-19.3 ng/ml); p < 0.001] and this improvement was dependent on age. We also observed a significant decrease in hyperparathyroidism prevalence (20.8% vs. 4.9%; P < 0.0001). Conclusion: In Sao Paulo...

‣ Juvenile onset systemic lupus erythematosus: a possible role for vitamin D in disease status and bone health

Casella, C. B.; Seguro, L. P. C.; Takayama, L.; Medeiros, D.; Bonfa, E.; Pereira, R. M. R.
Fonte: SAGE PUBLICATIONS LTD; LONDON Publicador: SAGE PUBLICATIONS LTD; LONDON
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
77.30921%
Purpose: In juvenile onset systemic lupus erythematosus (JoSLE), evidence for the association between vitamin D status, lupus activity, and bone health is very limited and not conclusive. The aim of this study was, therefore, to assess in JoSLE patients the possible relevance of vitamin D deficiency in disease and bone parameters. Methods: Fifty-seven JoSLE patients were initially compared to 37 age, race and body mass index (BMI) -matched healthy controls. The serum concentration of 25 hydroxyvitamin D (25OHD) was determined by radioimmunoassay. Patients with 25OHD deficiency (acurrency sign20 ng/mL) were compared to those with levels > 20 ng/mL. Disease activity was evaluated by SLE Disease Activity Index (SLEDAI). Bone mineral density (BMD) and body composition (BC) were measured using dual-energy X-ray absorptiometry (DXA). Results: 25OHD levels were similar in patients and controls (21.44 +/- 7.91 vs 22.54 +/- 8.25 ng/mL, p = 0.519), regardless of supplementation (65% of patients and none in controls). Thirty-one patients with 25OHD deficiency (acurrency sign20 ng/mL) were further compared to the 26 JoSLE patients with levels > 20 ng/mL. These two groups were well-balanced regarding vitamin D confounding variables: age (p = 0.100)...

‣ The influence of breakfast and dairy products on dietary calcium and vitamin D intake in postpubertal adolescents and young adults

Peters, B. S. E.; Verly, E.; Marchioni, D. M. L.; Fisberg, M.; Martini, L. A.
Fonte: WILEY-BLACKWELL; MALDEN Publicador: WILEY-BLACKWELL; MALDEN
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
77.353525%
Background: Given the importance of both calcium and vitamin D for bone health and the high prevalence of vitamin D from around the world, the present study aimed to evaluate calcium and vitamin D intake in a group of healthy Brazilian adolescents and young adults and to examine the influence of breakfast and dairy products in the total intake of these nutrients. Methods: One hundred and sixty adolescents and young adults, aged 1620 years old, from a public school, participated in the present study. Three-day dietary records were used to assess calcium and vitamin D intakes. Serum 25(OH) D levels were measured using a radioimmunoassay kit. The results were expressed as the mean (SD). Results: Only 3.8% of the subjects met the daily adequate intake recommendation for calcium, and none for vitamin D [682.2 (132.2) mg day(-1) and 124.0 (28.0) IU day(-1), respectively]. 25(OH) D serum levels were insufficient in 51.5% and deficient in 9.7% of the individuals [72.5 (22.3) nmol L(-1)]. There was a significant positive correlation between dairy product intake with both calcium and vitamin D (r = 0.597 and r = 0.561, respectively; P = 0.000). Adolescents who ate breakfast had a significant higher mean calcium, vitamin D and dairy product intake than adolescents who did not report this meal. Conclusions: The majority of adolescents and young adults did not consume recommended intakes of calcium and vitamin D and also presented 25(OH) D insufficiency. The results indicate that a regular breakfast and the consumption of dairy products represent important strategies in improving calcium and vitamin D intake in the diet.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [04/15312-9...

‣ Vitamina D em adolescentes: ingestão, nível sérico e associação com adiposidade e pressão arterial; Vitamin D in adolescents: dietary intake, serum levels and association with adiposity and blood pressure

Peters, Barbara Santarosa Emo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 09/03/2009 Português
Relevância na Pesquisa
67.42576%
Introdução - Atualmente, vários estudos epidemiológicos têm se direcionado à população de adolescentes, devido aos seus hábitos alimentares que, quando inadequados, podem favorecer o aparecimento de diversas doenças crônicas não transmissíveis na vida adulta. A vitamina D é um nutriente de fundamental importância durante os diversos ciclos de vida, porém sua determinação é inadequada através dos questionários/recordatórios alimentares. Níveis séricos reduzidos de vitamina D estão relacionados à patogênese de diversas doenças crônicas não transmissíveis. Objetivo - Objetivou-se investigar a ingestão e os níveis séricos de vitamina D em adolescentes saudáveis, assim como quais fatores influenciam a adequação da vitamina D e a associação entre o estado nutricional da vitamina D com a adiposidade e a pressão arterial. Métodos - Trata-se de estudo transversal, onde foram avaliados 205 adolescentes, sendo 106 meninos e 99 meninas, com média de idade de 18,25 (0,07). Avaliou-se a ingestão alimentar (diário alimentar de 3 dias), o estado nutricional (peso, altura, IMC, gordura corporal e massa magra pela bioimpedância elétrica), o nível de atividade física (questionário de atividade física...

‣ The role of vitamers and dietary-based metabolites of vitamin D in prevention of vitamin D deficiency

Cashman, Kevin D.
Fonte: Co-Action Publishing Publicador: Co-Action Publishing
Tipo: Artigo de Revista Científica
Publicado em 02/04/2012 Português
Relevância na Pesquisa
67.415464%
There is little doubt that vitamin D deficiency across all age groups in Europe is a problem. Low vitamin D status arises due to limited, if any, dermal synthesis during the winter months at latitudes above 40°N, putting increased importance on dietary supply of the vitamin. However, dietary intakes by most populations are low due to the limited supply of vitamin D-rich foods in the food chain. Thus strategies that effectively address this public health issue are urgently required. It has been emphasized and re-emphasized that there are only a limited number of public health strategies available to correct low dietary vitamin D intake: (1) improving intake of naturally occurring vitamin D-rich foods, (2) vitamin D fortification (mandatory or voluntarily) of food, and (3) vitamin D supplementation. Recent evidence suggests that the levels of vitamin D added to food would need to be high so as to ensure dietary requirements are met and health outcomes optimized. In addition, knowledge of the most effective forms of vitamin D to use in some of these preventative approaches is important. There is still uncertainty in relation to the relative efficacy of vitamin D2 versus D3, the two main food derived forms and those used in vitamin D supplements. The major metabolite of vitamin D with biological activity is 1...

‣ Transcriptional Sygernism Between Vitamin D-Rsponsive Elements in the Rat 25-Hyroxyvitamin D-3 24-Hydroxylase (CYP24) Promotor

Kerry, D.; Dwivedi, P.; Morris, H.; Omdahl, J.; May, B.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Artigo de Revista Científica
Publicado em //1996 Português
Relevância na Pesquisa
77.115815%
Transcription of the CYP24 gene is induced by 1,25-(OH)2D3 through a vitamin D receptor-dependent process. The functional activities of three possible vitamin D response elements (VDREs), located on the antisense strand of the rat CYP24 promoter, were investigated by transient expression of native and mutant promoter constructs in COS-1, JTC-12, and ROS 17/2.8 cells. A putative VDRE with a half-site spacing of 6 base pairs at -249/-232 (VDRE-3) did not contribute to 1,25-(OH)2D3 induced expression in the native promoter, although activity has been reported when the element was fused to the heterologous thymidine kinase promoter. Two VDREs with half-site spacings of 3 base pairs at -150/-136 and -258/-244 (VDRE-1 and VDRE-2, respectively), showed transcriptional synergism in COS-1 cells when treated with 1,25-(OH)2D3 (10(-7) to 10(-11) M). The contribution of both VDREs was hormone-concentration dependent from 10(-10) to 10(-12) M, with VDRE-1 demonstrating greatest sensitivity to 1,25-(OH)2D3. Transactivation by VDRE-1 was always greater than VDRE-2, but the converse was observed for the binding of vitamin D receptor-retinoid X receptor complex by each VDRE in gel mobility shift assays. The synergy observed between VDRE-1 and VDRE-2 may have important implications in cellular responses to different circulating levels of 1...

‣ Vitamin D and fractures in people with intellectual disability

Vanlint, S.; Nugent, M.
Fonte: Blackwell Science Ltd Publicador: Blackwell Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2006 Português
Relevância na Pesquisa
67.437666%
Background : People with intellectual disability (ID) are thought to be at an increased risk of fractures. The extent of this increase in risk has been incompletely documented in the literature, and the underlying reasons remain to be elucidated. Methods : The aims of our study were to document the vitamin D status and fracture incidence in an intellectually disabled population, to test for associations between vitamin D status and possible risk factors for reduced vitamin D levels, and to determine the efficacy of oral vitamin D supplementation in restoring appropriate vitamin D levels in those found to be vitamin D insufficient. A 5-year retrospective audit of fractures in 337 individuals with ID receiving health care at a residential facility was performed. Data analysed included age, gender, mobility, dietary status, incident fractures, medications and 25-hydroxyvitamin D levels. Vitamin D insufficient individuals received oral vitamin D supplementation, and had repeat testing to assess treatment efficacy. Results : In total, 57% of individuals tested were found to be vitamin D insufficient. Vitamin D insufficiency was strongly correlated with reduced mobility (P < 0.001) and difficulty with consuming solids (P < 0.001). However...

‣ Does Vitamin D modulate asymmetric dimethylarginine and C-reactive protein concentrations?

Ngo, D.; Sverdlov, A.; McNeil, J.; Horowitz, J.
Fonte: Excerpta Medica Inc Publicador: Excerpta Medica Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
77.08557%
BACKGROUND: Vitamin D deficiency is associated with significant increases in the incidence of cardiovascular risk factors and mortality. However, the mechanisms underlying this association remain unclear. The current study evaluated the possible relationships among vitamin D status, endothelial dysfunction, and inflammation. METHODS: Plasma concentrations of 25-hydroxyvitamin D(3) were determined by radioimmunoassay in a normal population cohort (n=253) aged 51 to 77 years (mean 63.4+/-6 years). Asymmetric dimethylarginine, a marker/mediator of endothelial dysfunction, was assayed by high-performance liquid chromatography. High-sensitivity C-reactive protein levels were used as a marker of inflammatory activation. RESULTS: On univariate analyses, low 25-hydroxyvitamin D(3) levels were inversely correlated with asymmetric dimethylarginine concentrations, high-sensitivity C-reactive protein levels, and body mass index. Seasonal fluctuations in 25-hydroxyvitamin D(3) levels were associated with reciprocal asymmetric dimethylarginine concentration fluctuations. Hypertension and treatment with an angiotensin-converting enzyme inhibitor/angiotensin receptor blocker also were associated with low 25-hydroxyvitamin D(3) levels. On multiple linear analysis...

‣ Novel targets of vitamin D activity in bone: action of the vitamin D receptor in osteoblasts, osteocytes and osteoclasts

Ryan, J.; Reinke, D.; Kogawa, M.; Turner, A.; Atkins, G.; Anderson, P.; Morris, H.
Fonte: Bentham Science Publishers Ltd. Publicador: Bentham Science Publishers Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
77.3254%
The active form of vitamin D, 1,25-dihydroxyvitamin D3, carries out its diverse range of biological activities by binding to the nuclear vitamin D receptor, present in almost every cell of the body. It is well established that adequate serum 25-hydroxyvitamin D levels correlate with a reduction in the incidence of osteoporosis; however, the physiological basis for this relationship remains elusive. Although, the endocrine actions of vitamin D are thoroughly appreciated, the effect of vitamin D on bone tissue and bone cells is yet to be completely understood. There exists a wealth of literature that suggests the VDR within the three major bone cell types, osteoblasts, osteocytes and osteoclasts, is responsible for the regulation of bone homeostasis. The circumstances, under which the action of 1,25-dihydroxyvitamin D3 elicits an anabolic or catabolic role have not been elucidated. However, it would seem that vitamin D can evoke both of these effects and that this is partly mediated by calcium homeostasis. This raises the possibility that dietary calcium intake and vitamin D metabolism act concomitantly at the kidney, intestine and the bone in a coordinated response. Thus, to maintain adequate bone homeostasis and reduce the risk of metabolic bone disease via the diet...

‣ Asthma and genes encoding components of the vitamin D pathway

Bosse, Y.; Lemire, M.; Poon, A.; Daly, D.; He, J.; Stanford, A.; White, J.; James, A.; Musk, A.; Palmer, L.; Raby, B.; Weiss, S.; Kozyrskyj, A.; Becker, A.; Hudson, T.; Laprise, C.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
77.21546%
Background: Genetic variants at the vitamin D receptor (VDR) locus are associated with asthma and atopy. We hypothesized that polymorphisms in other genes of the vitamin D pathway are associated with asthma or atopy. Methods: Eleven candidate genes were chosen for this study, five of which code for proteins in the vitamin D metabolism pathway (CYP27A1, CYP27B1, CYP2R1, CYP24A1, GC) and six that are known to be transcriptionally regulated by vitamin D (IL10, IL1RL1, CD28, CD86, IL8, SKIIP). For each gene, we selected a maximally informative set of common SNPs (tagSNPs) using the European-derived (CEU) HapMap dataset. A total of 87 SNPs were genotyped in a French-Canadian family sample ascertained through asthmatic probands (388 nuclear families, 1064 individuals) and evaluated using the Family Based Association Test (FBAT) program. We then sought to replicate the positive findings in four independent samples: two from Western Canada, one from Australia and one from the USA (CAMP). Results: A number of SNPs in the IL10, CYP24A1, CYP2R1, IL1RL1 and CD86 genes were modestly associated with asthma and atopy (p < 0.05). Two-gene models testing for both main effects and the interaction were then performed using conditional logistic regression. Two-gene models implicating functional variants in the IL10 and VDR genes as well as in the IL10 and IL1RL1 genes were associated with asthma (p < 0.0002). In the replicate samples...

‣ Vitamin D levels in an Australian population.

Gill, T.K.; Hill, C.L.; Shanahan, E.M.; Taylor, A.W.; Appleton, S.L.; Grant, J.F.; Shi, Z.; Grande, E.D.; Price, K.; Adams, R.J.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
77.35772%
Background: Levels of vitamin D in the population have come under increasing scrutiny, however there are only a few studies in Australia which measure levels in the general population. The aim of this study was to measure the levels of vitamin D within a large population cohort and examine the association with seasons and selected demographic and health risk factors. Methods: A longitudinal cohort study of 2413 participants in the northwest suburbs of Adelaide, South Australia conducted between 2008 and 2010 was used to examine serum levels of 25-hydroxy vitamin D (25(OH)D) in relation to demographic characteristics (age, sex, income, education and country of birth), seasons, the use of vitamin D supplements and selected health risk factors (physical activity, body mass index and smoking). Both unadjusted and adjusted mean levels of serum 25(OH)D were examined, as were the factors associated with the unadjusted and adjusted prevalence of serum 25(OH)D levels below 50 and 75 nmol/L. Results: Overall, the mean level of serum 25(OH)D was 69.2 nmol/L with 22.7% of the population having a serum 25(OH)D level below 50 nmol/L, the level which is generally recognised as vitamin D deficiency. There were significantly higher levels of 25(OH)D among males compared to females (t = 4.65...

‣ L-arginine and vitamin D adjunctive therapies in pulmonary tuberculosis: a randomised, double-blind, placebo-controlled trial

Ralph, A.P.; Waramori, G.; Pontororing, G.J.; Kenangalem, E.; Wiguna, A.; Tjitra, E.; Sandjaja; Lolong, D.B.; Yeo, T.W.; Chatfield, M.D.; Soemanto, R.K.; Bastian, I.; Lumb, R.; Maguire, G.P.; Eisman, J.; Price, R.N.; Morris, P.S.; Kelly, P.M.; Anstey, N.M
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
77.13621%
BACKGROUND: Vitamin D (vitD) and L-arginine have important antimycobacterial effects in humans. Adjunctive therapy with these agents has the potential to improve outcomes in active tuberculosis (TB). METHODS: In a 4-arm randomised, double-blind, placebo-controlled factorial trial in adults with smear-positive pulmonary tuberculosis (PTB) in Timika, Indonesia, we tested the effect of oral adjunctive vitD 50,000 IU 4-weekly or matching placebo, and L-arginine 6.0 g daily or matching placebo, for 8 weeks, on proportions of participants with negative 4-week sputum culture, and on an 8-week clinical score (weight, FEV1, cough, sputum, haemoptysis). All participants with available endpoints were included in analyses according to the study arm to which they were originally assigned. Adults with new smear-positive PTB were eligible. The trial was registered at ClinicalTrials.gov NCT00677339. RESULTS: 200 participants were enrolled, less than the intended sample size: 50 received L-arginine + active vitD, 49 received L-arginine + placebo vit D, 51 received placebo L-arginine + active vitD and 50 received placebo L-arginine + placebo vitD. According to the factorial model, 99 people received arginine, 101 placebo arginine, 101 vitamin D, 99 placebo vitamin D. Results for the primary endpoints were available in 155 (4-week culture) and 167 (clinical score) participants. Sputum culture conversion was achieved by week 4 in 48/76 (63%) participants in the active L-arginine versus 48/79 (61%) in placebo L-arginine arms (risk difference -3%...

‣ L-arginine and vitamin D adjunctive therapies in pulmonary tuberculosis: a randomised, double-blind, placebo-controlled trial

Ralph, Anna P; Waramori, Govert; Pontororing, Gysje J; Kenangalem, Enny; Wiguna, Andri; Tjitra, Emiliana; Sandjaja, null; Lolong, Dina B; Yeo, Tsin W; Chatfield, Mark D; Soemanto, Retno K; Bastian, Ivan; Lumb, Richard; Maguire, Graeme P; Eisman, John; Pri
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 12 pages
Português
Relevância na Pesquisa
77.115815%
BACKGROUND Vitamin D (vitD) and L-arginine have important antimycobacterial effects in humans. Adjunctive therapy with these agents has the potential to improve outcomes in active tuberculosis (TB). METHODS In a 4-arm randomised, double-blind, placebo-controlled factorial trial in adults with smear-positive pulmonary tuberculosis (PTB) in Timika, Indonesia, we tested the effect of oral adjunctive vitD 50,000 IU 4-weekly or matching placebo, and L-arginine 6.0 g daily or matching placebo, for 8 weeks, on proportions of participants with negative 4-week sputum culture, and on an 8-week clinical score (weight, FEV1, cough, sputum, haemoptysis). All participants with available endpoints were included in analyses according to the study arm to which they were originally assigned. Adults with new smear-positive PTB were eligible. The trial was registered at ClinicalTrials.gov NCT00677339. RESULTS 200 participants were enrolled, less than the intended sample size: 50 received L-arginine + active vitD, 49 received L-arginine + placebo vit D, 51 received placebo L-arginine + active vitD and 50 received placebo L-arginine + placebo vitD. According to the factorial model, 99 people received arginine, 101 placebo arginine, 101 vitamin D, 99 placebo vitamin D. Results for the primary endpoints were available in 155 (4-week culture) and 167 (clinical score) participants. Sputum culture conversion was achieved by week 4 in 48/76 (63%) participants in the active L-arginine versus 48/79 (61%) in placebo L-arginine arms (risk difference -3%...

‣ Relationship between Serum 25-hydroxyvitamin D and bone resorption markers in vitamin D insufficiency

Jesudason, D.; Need, A.; Horowitz, M.; O'Loughlin, P.; Morris, H.; Nordin, B.
Fonte: Elsevier Science Inc Publicador: Elsevier Science Inc
Tipo: Artigo de Revista Científica
Publicado em //2002 Português
Relevância na Pesquisa
77.107964%
It is known that nursing-home patients with vitamin D insufficiency have elevated serum parathyroid hormone (PTH) as well as raised serum alkaline phosphatase (ALP). Although it is well known that vitamin D insufficiency and secondary hyperparathyroidism are common among the elderly in western countries, there is continuing controversy over the level of serum 25-hydroxyvitamin D [25(OH)D] necessary for bone health. We approached this issue by examining the relationships between serum 25(OH)D, ionized calcium, PTH, and ALP and the urinary bone resorption markers hydroxyproline, pyridinoline, and deoxypyridinoline, corrected for creatinine (OHPr/Cr, Pyd/Cr, and Dpd/Cr, respectively), in 486 postmenopausal women of mean age 63 (SD 9.5) years, who were referred to our osteoporosis and menopause clinics for investigation. When the patients were divided into two groups with 25(OH)D above and below 20 nmol/L, 30 nmol/L, 40 nmol/L, 50 nmol/L, 60 nmol/L, or 70 nmol/L, the most significant differences between the two groups thus derived was found at a serum 25(OH)D level of 60 nmol/L (P < 0.001 for all markers). The most significant difference between groups for serum PTH was found when the patients were divided at a serum 25(OH)D of 50 nmol/L. PTH...

‣ Determinants of insulin responsiveness in young women: Impact of polycystic ovarian syndrome, nitric oxide, and vitamin D

Ngo, D.; Chan, W.; Rajendran, S.; Heresztyn, T.; Amarasekera, A.; Sverdlov, A.; O'Loughlin, P.; Morris, H.; Chirkov, Y.; Norman, R.; Horowitz, J.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
77.057476%
BACKGROUND: Polycystic ovary syndrome (PCOS) is associated with incremental risk of atherosclerosis and possibly of cardiovascular events. Insulin resistance (IR) occurs frequently in PCOS subjects, which might be one of the mechanisms involved in engendering such risk. We sought to evaluate whether the impact of other factors potentially associated both with PCOS and with IR might differentially modulate degree of IR in women with and without PCOS. METHODS AND RESULTS: We measured body mass index (BMI), hs-CRP, plasma concentrations of asymmetric dimethylarginine (ADMA), vitamin D (25(OH)D3) levels and platelet responsiveness to nitric oxide donor sodium nitroprusside (NO responsiveness) in 47 young women (n=27 with PCOS and n=20 weight-matched controls) without metabolic syndrome, hypertension or overt cardiovascular disease. We performed univariate and multivariate regression analyses to establish correlates of the quantitative insulin-sensitivity check index (QUICKI), as a marker of IR. On univariate analysis, plasma 25(OH)D3 levels and low NO responsiveness tended to be direct correlates with QUICKI in the entire subject group. BMI, hs-CRP, and ADMA levels were significant inverse correlates of QUICKI in PCOS subjects, but not in subjects without PCOS. On multivariate analysis...

‣ Analysis of vitamin D metabolism gene expression in human bone: evidence for autocrine control of bone remodelling

Ormsby, R.; Findlay, D.; Kogawa, M.; Anderson, P.; Morris, H.; Atkins, G.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
77.046167%
The metabolism of 25-hydroxyvitamin D (25D) to active 1α,25-dihydroxyvitamin D (1,25D) by endogenous expression of 25D 1-α hydroxylase (CYP27B1) in bone cells appears to have functional effects in both osteoclasts and osteoblasts. To examine relationships between CYP27B1 expression in bone and its potential function in vivo, we examined the expression of vitamin D metabolism genes (CYP27B1, CYP24A1, VDR) in human trabecular bone samples and compared them by linear regression analysis with the expression of osteoclast (TRAP, CA2, CATK, NFATC1), osteoblast (TNAP, COL1A1, OCN, MEPE, BRIL), osteocyte (DMP1, SOST, PHEX, MEPE, FGF23)-related gene markers, genes associated with osteoblast/osteocyte control of osteoclastogenesis (RANKL, M-CSF, OPG, IL-8, TWEAK) and transcription factors (NFATC1, RUNX2, OSX, MSX2, HIF1A). This revealed multiple significant gene expression relationships between CYP27B1 and the transcription factors RUNX2, NFATC1, consistent with the coordinated expression of this gene by both osteoblast and osteoclast-lineage cells, and with MSX2 and the hypoxia-inducible transcription factor, HIF1A. CYP27B1 expression associated mainly with gene markers of bone resorption. VDR mRNA expression was also associated with resorption-related genes. Against expectations...

‣ The role of vitamin D receptor in osteoblasts and bone mineralisation.

Lam, Nga Ngoc
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013 Português
Relevância na Pesquisa
67.43932%
Age-related bone loss is associated with a change in bone remodelling characterised by decreased bone formation relative to bone resorption. It is well described that age-related bone loss is accelerated as a consequence of vitamin D deficiency, a process which can be replicated in rodent studies. While vitamin D has been shown to play important roles for adequate bone mineralisation and the prevention of osteoporosis, the exact mechanisms remain controversial. It is clear that vitamin D is necessary for the stimulation of intestinal calcium and phosphate absorption, maintenance of calcium homeostasis and supply of calcium and phosphate for bone mineralisation. However, vitamin D has also been shown to directly act on bone cells to promote mineralisation as well as regulate bone resorption. The question of the essential nature of the in vivo role for the direct actions of vitamin D on bone has proven to be difficult to resolve. The only published mouse model which addresses the direct actions of vitamin D in osteoblasts is the osteoblast-specific vitamin D receptor transgenic mouse, or OSVDR mouse. Using this transgenic mouse model, it has been reported that the enhanced vitamin D activity in osteoblasts promotes bone formation and mediates reduction in bone resorption most likely through reduced RANKL signalling of osteoclastogenesis. The reported overall bone phenotype of the OSVDR was increased vertebral trabecular bone as well as increased cortical bone volume leading to increased bone strength. In contrast to the findings in OSVDR mice...

‣ Metabolism of vitamin D₃ in human osteoblasts: Evidence for autocrine and paracrine activities of 1α,25-dihydroxyvitamin D₃; Metabolism of vitamin D(3) in human osteoblasts: Evidence for autocrine and paracrine activities of 1alpha,25-dihydroxyvitamin D(3)

Atkins, G.; Anderson, P.; Findlay, D.; Welldon, K.; Vincent, C.; Zannettino, A.; O'Loughlin, P.; Morris, H.
Fonte: Elsevier Science Inc Publicador: Elsevier Science Inc
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
Relevância na Pesquisa
77.285283%
Circulating 1 alpha,25-dihydroxyvitamin D(3) (1,25D) derives from renal conversion of 25-hydroxyvitamin D(3) (25D), by the 25D 1 alpha-hydroxylase (CYP27B1). Blood 25D levels, but not 1,25D levels, are the best indicator of vitamin D status and predict fracture risk in the elderly. We examined the extent to which osteoblasts can metabolize 25D. Well-characterized human primary osteoblasts and osteosarcoma (OS) cell lines were examined for the expression and regulation of genes associated with vitamin D metabolism, using real-time PCR. Primary osteoblasts and OS cell lines were found to express CYP27B1 mRNA and secreted detectable 1,25D in response to 25D. Of the OS cell lines tested, HOS expressed the most CYP27B1 mRNA and secreted the highest levels of 1,25D. All osteoblastic cells examined up-regulated expression of the catabolic regulator of 1,25D, the 25-hydroxyvitamin D-24-hydroxylase (CYP24), when incubated with either 1,25D or 25D. Exposure to physiological levels of 25D resulted in up-regulated transcription of the 1,25D responsive genes, osteocalcin (OCN), osteopontin (OPN) and RANKL. Specific knockdown of CYP27B1 in HOS cells using siRNA resulted in up to 80% reduction in both 1,25D secretion and the transcription of OCN and CYP24...

‣ The Importance of Body Weight for the Dose Response Relationship of Oral Vitamin D Supplementation and Serum 25-Hydroxyvitamin D in Healthy Volunteers

Ekwaru, John Paul; Zwicker, Jennifer D.; Holick, Michael F.; Giovannucci, Edward; Veugelers, Paul J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
77.37665%
Unlike vitamin D recommendations by the Institute of Medicine, the Clinical Practice Guidelines by the Endocrine Society acknowledge body weight differentials and recommend obese subjects be given two to three times more vitamin D to satisfy their body's vitamin D requirement. However, the Endocrine Society also acknowledges that there are no good studies that clearly justify this. In this study we examined the combined effect of vitamin D supplementation and body weight on serum 25-hydroxyvitamin (25(OH)D) and serum calcium in healthy volunteers. We analyzed 22,214 recordings of vitamin D supplement use and serum 25(OH)D from 17,614 healthy adult volunteers participating in a preventive health program. This program encourages the use of vitamin D supplementation and monitors its use and serum 25(OH)D and serum calcium levels. Participants reported vitamin D supplementation ranging from 0 to 55,000 IU per day and had serum 25(OH)D levels ranging from 10.1 to 394 nmol/L. The dose response relationship between vitamin D supplementation and serum 25(OH)D followed an exponential curve. On average, serum 25(OH)D increased by 12.0 nmol/L per 1,000 IU in the supplementation interval of 0 to 1,000 IU per day and by 1.1 nmol/L per 1,000 IU in the supplementation interval of 15...