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The role of vitamers and dietary-based metabolites of vitamin D in prevention of vitamin D deficiency
Kevin D. Cashman
Food & Nutrition Research , 2012, DOI: 10.3402/fnr.v56i0.5383
Abstract: 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 1,25(OH)2D; however, this is usually used for pharmacological purposes and is not typically used in normal, healthy people. The other major metabolite, 25(OH)D, which has also been used for pharmacological purposes is present in certain foods such as meat and meat products (particularly offal) as well as eggs. This metabolite may have the potential to boost vitamin D status up to five times more effectively that native vitamin D3 in foods. However, the exact bioactivity of this compound needs to be established.
Vitamin D Requirements for the Future—Lessons Learned and Charting a Path Forward
Kevin D. Cashman
- , 2018, DOI: 10.3390/nu10050533
Abstract: Estimates of dietary requirements for vitamin D or Dietary Reference Values (DRV) are crucial from a public health perspective in providing a framework for prevention of vitamin D deficiency and optimizing vitamin D status of individuals. While these important public health policy instruments were developed with the evidence-base and data available at the time, there are some issues that need to be clarified or considered in future iterations of DRV for vitamin D. This is important as it will allow for more fine-tuned and truer estimates of the dietary requirements for vitamin D and thus provide for more population protection. The present review will overview some of the confusion that has arisen in relation to the application and/or interpretation of the definitions of the Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA). It will also highlight some of the clarifications needed and, in particular, how utilization of a new approach in terms of using individual participant-level data (IPD), over and beyond aggregated data, from randomised controlled trials with vitamin D may have a key role in generating these more fine-tuned and truer estimates, which is of importance as we move towards the next iteration of vitamin D DRVs
Improved Dietary Guidelines for Vitamin D: Application of Individual Participant Data (IPD)-Level Meta-Regression Analyses
Christian Ritz,Kevin D. Cashman,Mairead Kiely,ODIN Collaborators
- , 2017, DOI: 10.3390/nu9050469
Abstract: Dietary Reference Values (DRVs) for vitamin D have a key role in the prevention of vitamin D deficiency. However, despite adopting similar risk assessment protocols, estimates from authoritative agencies over the last 6 years have been diverse. This may have arisen from diverse approaches to data analysis. Modelling strategies for pooling of individual subject data from cognate vitamin D randomized controlled trials (RCTs) are likely to provide the most appropriate DRV estimates. Thus, the objective of the present work was to undertake the first-ever individual participant data (IPD)-level meta-regression, which is increasingly recognized as best practice, from seven winter-based RCTs (with 882 participants ranging in age from 4 to 90 years) of the vitamin D intake–serum 25-hydroxyvitamin D (25(OH)D) dose-response. Our IPD-derived estimates of vitamin D intakes required to maintain 97.5% of 25(OH)D concentrations >25, 30, and 50 nmol/L across the population are 10, 13, and 26 μg/day, respectively. In contrast, standard meta-regression analyses with aggregate data (as used by several agencies in recent years) from the same RCTs estimated that a vitamin D intake requirement of 14 μg/day would maintain 97.5% of 25(OH)D >50 nmol/L. These first IPD-derived estimates offer improved dietary recommendations for vitamin D because the underpinning modeling captures the between-person variability in response of serum 25(OH)D to vitamin D intake
Human Engineered Cardiac Tissues Created Using Induced Pluripotent Stem Cells Reveal Functional Characteristics of BRAF-Mediated Hypertrophic Cardiomyopathy
Bruce D. Gelb,Bryce V. Johnson,Kevin D. Costa,Rebecca Josowitz,Timothy J. Cashman
- , 2016, DOI: 10.1371/journal.pone.0146697
Abstract:
Interactions between Vitamin D Status, Calcium Intake and Parathyroid Hormone Concentrations in Healthy White-Skinned Pregnant Women at Northern Latitude
Andrea Hemmingway,George L. J. Hull,Karen M. O’Callaghan,Kevin D. Cashman,Mairead E. Kiely,áine Hennessy
- , 2018, DOI: 10.3390/nu10070916
Abstract: Adverse effects of low vitamin D status and calcium intakes in pregnancy may be mediated through functional effects on the calcium metabolic system. Little explored in pregnancy, we aimed to examine the relative importance of serum 25-hydroxyvitamin D (25(OH)D) and calcium intake on parathyroid hormone (PTH) concentrations in healthy white-skinned pregnant women. This cross-sectional analysis included 142 participants (14 ± 2 weeks’ gestation) at baseline of a vitamin D intervention trial at 51.9 °N. Serum 25(OH)D, PTH, and albumin-corrected calcium were quantified biochemically. Total vitamin D and calcium intakes (diet and supplements) were estimated using a validated food frequency questionnaire. The mean ± SD vitamin D intake was 10.7 ± 5.2 μg/day. With a mean ± SD serum 25(OH)D of 54.9 ± 22.6 nmol/L, 44% of women were <50 nmol/L and 13% <30 nmol/L. Calcium intakes (mean ± SD) were 1182 ± 488 mg/day and 23% of participants consumed <800 mg/day. The mean ± SD serum albumin-adjusted calcium was 2.2 ± 0.1 mmol/L and geometric mean (95% CI) PTH was 9.2 (8.4, 10.2) pg/mL. PTH was inversely correlated with serum 25(OH)D (r = ?0.311, p < 0.001), but not with calcium intake or serum calcium (r = ?0.087 and 0.057, respectively, both p > 0.05). Analysis of variance showed that while serum 25(OH)D (dichotomised at 50 nmol/L) had a significant effect on PTH (p = 0.025), calcium intake (<800, 800–1000, ≥1000 mg/day) had no effect (p = 0.822). There was no 25(OH)D-calcium intake interaction effect on PTH (p = 0.941). In this group of white-skinned women with largely sufficient calcium intakes, serum 25(OH)D was important for maintaining normal PTH concentration
25-Hydroxyvitamin D as a Biomarker of Vitamin D Status and Its Modeling to Inform Strategies for Prevention of Vitamin D Deficiency within the Population
Damien P Prévéraud,Ellen GHM van den Heuvel,Helen M Macdonald,Jayashree Arcot,Kevin D Cashman,Ruud JW Schoemaker
- , 2017, DOI: 10.3945/an.117.015578
Abstract:
Seasonal Changes in Vitamin D-Effective UVB Availability in Europe and Associations with Population Serum 25-Hydroxyvitamin D
Andreas Kazantzidis,Ann R. Webb,Christopher T. Sempos,Colette M. O’Neill,Gudny Eiriksdottir,Guri Grimnes,Kevin D. Cashman,Mairead Kiely,Mary Frances Cotch,Mary J. Ryan,Niamh Barber,Ramon A. Durazo-Arvizu,Rolf Jorde,Vilmundur Gudnason
- , 2016, DOI: 10.3390/nu8090533
Abstract: 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
Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data
Gudny Eiríksdottir,Guri Grimnes,Kevin D. Cashman,Lars Rejnmark,Lise Sofie Bislev,Mairead Kiely,Martin Gaksch,Martin Grübler,Natasja M. van Schoor,Paul Lips,Rolf Jorde,Stefan Pilz,Vilmundur Gudnason
- , 2017, DOI: 10.1371/journal.pone.0180512
Abstract:
The Magnetic Field of Cloud 3 in L204
Lauren R. Cashman,D. P. Clemens
Physics , 2014, DOI: 10.1088/0004-637X/793/2/126
Abstract: The L204 dark cloud complex is a nearby filamentary structure in Ophiuchus North that has no signs of active star formation. Past studies show that L204 is interacting with the nearby runaway O star, $\zeta$ Oph, and hosts a magnetic field that is coherent across parsec-length scales. Near-infrared $H$-band (1.6$\mu$m) linear polarization measurements were obtained for 3,896 background stars across a $1\deg \times 1.5\deg$ region centered on the dense Cloud 3 in L204, using the Mimir near-infrared instrument on the 1.8m Perkins Telescope. Analysis of these observations reveals both large-scale properties and small-scale changes in the magnetic field direction in Cloud 3. In the northern and western $\zeta$ Oph facing regions of the cloud, the magnetic field appears to be pushed up against the face of the cloud. This may indicate that the UV flux from $\zeta$ Oph has compressed the magnetic field on the western edge of L204. The plane-of-sky magnetic field strength is estimated to be $\sim 11 - 26$ $\mu$G using the Chandrasekhar-Fermi method. The polarimetry data also reveal that the polarization efficiency (PE $\equiv P_{\rm H}/A_{\rm V}$) steadily decreases with distance from $\zeta$ Oph ($-0.09 \pm 0.03 \% \, {\rm mag}^{-1} \, {\rm pc}^{-1}$). Additionally, power-law fits of PE versus $A_{\rm V}$ for localized samples of probe stars show steeper negative indices with distance from $\zeta$ Oph. Both findings highlight the importance of external illumination, here from $\zeta$ Oph, in aligning dust grains to embedded magnetic fields.
Near-infrared polarimetry of a normal spiral galaxy viewed through the Taurus Molecular Cloud Complex
Dan P. Clemens,M. D. Pavel,L. R. Cashman
Physics , 2013, DOI: 10.1088/0004-6256/145/3/74
Abstract: Few normal galaxies have been probed using near-infrared polarimetry, even though it reveals magnetic fields in the cool interstellar medium better than either optical or radio polarimetry. Deep H-band (1.6um) linear imaging polarimetry toward Taurus serendipitously included the galaxy 2MASX J04412715+2433110 with adequate sensitivity and resolution to map polarization across nearly its full extent. The observations revealed the galaxy to be a steeply inclined (~75 deg) disk type with a diameter, encompassing 90% of the Petrosian flux, of 4.2 kpc at a distance of 53 Mpc. Because the sight line passes through the Taurus Molecular Cloud complex, the foreground polarization needed to be measured and removed. The foreground extinction Av of 2.00+/-0.10 mag and reddening E(H-K) of 0.125 +/- 0.009 mag were also assessed and removed, based on analysis of 2MASS, UKIDSS, Spitzer, and WISE photometry using the NICE, NICER, and RJCE methods. Corrected for the polarized foreground, the galaxy polarization values range from zero to 3%. The polarizations are dominated by a disk-parallel magnetic field geometry, especially to the northeast, while either a vertical field or single scattering of bulge light produces disk-normal polarizations to the southwest. The multi-kpc coherence of the magnetic field revealed by the infrared polarimetry is in close agreement with short wavelength radio synchrotron observations of edge-on galaxies, indicating that both cool and warm interstellar media of disk galaxies may be threaded by common magnetic fields.
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