939 resultados para 1,25-dihidroxivitamina D
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Low vitamin D status is common in Europe. The major source of vitamin D in humans is ultraviolet B (UVB)-induced dermal synthesis of cholecalciferol, whereas food sources are believed to play a lesser role. Our objectives were to assess UVB availability (Jm−2) across several European locations ranging from 35° N to 69° N, and compare these UVB data with representative population serum 25-hydroxyvitamin D (25(OH)D) data from Ireland (51–54° N), Iceland (64° N) and Norway (69° N), as exemplars. Vitamin D-effective UVB availability was modelled for nine European countries/regions using a validated UV irradiance model. Standardized serum 25(OH)D data was accessed from the EC-funded ODIN project. The results showed that UVB availability decreased with increasing latitude (from 35° N to 69° N), while all locations exhibited significant seasonal variation in UVB. The UVB data suggested that the duration of vitamin D winters ranged from none (at 35° N) to eight months (at 69° N). The large seasonal fluctuations in serum 25(OH)D in Irish adults was much dampened in Norwegian and Icelandic adults, despite considerably lower UVB availability at these northern latitudes but with much higher vitamin D intakes. In conclusion, increasing the vitamin D intake can ameliorate the impact of low UVB availability on serum 25(OH)D status in Europe.
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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Scale 1:25,000.
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"Map information as of 1970."
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"Map information as of 1970."
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Objective: To assess serum levels of 25-hydroxyvitamin D [25(OH)D] in the first trimester and to determine the factors affecting deficiency levels and its association with pregnancy outcomes. Methods: Serum 25(OH)D concentrations were measured at 11-14 weeks’ gestation in 229 singleton pregnancies using liquid chromatography-tandem mass spectrometry. Results: The median serum 25(OH)D concentration was 10.8 ng/mL and 45.9% of women had severe vitamin D deficiency with concentrations of <10 ng/mL. Logistic regression analysis revealed that covered dressing style, lack of multivitamin intake, season of blood sampling (November-April) were factors associated with 25(OH)D deficiency. There was a negative correlation between 25(OH)D levels and gestational age at sampling. Low 25(OH)D levels were not associated with adverse pregnancy outcomes. Higher rate of cesarean section (CS) was noted in women with 25(OH)D ≥10 ng/mL compared to those with 25(OH)D < 10mg/ml ( p= 0.01). Conclusion: A high prevalence of vitamin D deficiency was observed in early pregnancy which was related to dress code, use of multi-vitamins and season at sampling. Low 25(OH)D levels were not related with adverse pregnancy outcomes. Women with severe vitamin D deficiency were more likely to deliver vaginally.
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Vitamin D insufficiency and deficiency have been associated with an increased risk of adverse pregnancy outcomes. Controversy remains as findings have been inconsistent between disparate populations. The aim of this study was to investigate the relationship between vitamin D status and pregnancy outcomes in a large, prospective pregnancy cohort. 25-Hydroxyvitamin D concentration was analysed in serum samples collected at 15 weeks of gestation from 1710 New Zealand women participating in a large, observational study. Associations between vitamin D status and pre-eclampsia, preterm birth, small for gestational age (SGA) and gestational diabetes were investigated. The mean 25-hydroxyvitamin D concentration was 72·9 nmol/l. In all, 23 % had 25-hydroxyvitamin D concentrations <50 nmol/l, and 5 % of participants had concentrations <25 nmol/l. Women with 25-hydroxyvitamin D concentrations <75 nmol/l at 15 weeks of gestation were more likely to develop gestational diabetes mellitus than those with concentrations >75 nmol/l (OR 2·3; 95 % CI 1·1, 5·1). However, this effect was not significant when adjustments were made for BMI and ethnicity (OR 1·8; 95 % CI 0·8, 4·2). 25-Hydroxyvitamin D concentration at 15 weeks was not associated with development of pre-eclampsia, spontaneous preterm birth or SGA infants. Pregnancy complications were low in this largely vitamin D-replete population.
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A bimonthly literary magazine edited by Zhou Shoujuan 周瘦鵑, featuring fiction, topical articles, and entertainment features, published from September 1921 through November 1925.
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A bimonthly literary magazine edited by Zhou Shoujuan 周瘦鵑, featuring fiction, topical articles, and entertainment features, published from September 1921 through November 1925.