BACKGROUND & AIMS: Oral supplementation with vitamin D is recommended for older adults to maintain a sufficient 25-hydroxyvitamin D (25(OH)D) status throughout the year. While supplementation with vitamin D2 or D3 is most common, alternative treatment regimens exist which require further investigation with respect to increasing 25(OH)D concentration. We investigated the dose-response effects of supplementation with calcifediol compared to vitamin D3 and assessed the dose which results in mean serum 25(OH)D3 concentrations between 75 and 100 nmol/L.METHODS: This randomized, double-blind intervention study included men and women aged ≥65 years (n = 59). Participants received either 5, 10 or 15 μg calcifediol or 20 μg vitamin D3 per day, for a period of 24 weeks. Blood samples were collected every four weeks to assess response profiles of vitamin D related metabolites; serum vitamin D3, 25(OH)D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3). Further, serum calcium, plasma parathyroid hormone, and urinary calcium were evaluated.RESULTS: Supplementation with 20 μg vitamin D3 increased 25(OH)D3 concentrations towards 70 nmol/L within 16 weeks. Supplementation with 10 or 15 μg calcifediol increased 25(OH)D3 levels >75 nmol/L in 8 and 4 weeks, respectively. Steady state was achieved from week 12 onwards with serum 25(OH)D3 levels stabilizing between 84 and 89 nmol/L in the 10 μg calcifediol group. A significant association was observed between the changes in 25(OH)D3 and 24,25(OH)2D3 (R2 = 0.83, P < 0.01), but not between 25(OH)D3 and 1,25(OH)2D3 (R2 = 0.04, P = 0.18). No cases of hypercalcemia occurred in any treatment during the study period.CONCLUSIONS: Calcifediol supplementation rapidly and safely elevates serum 25(OH)D3 concentrations to improve vitamin D status in older adults. A daily dose of 10 μg calcifediol allows serum 25(OH)D3 concentrations to be maintained between 75 and 100 nmol/L.TRIAL REGISTRATION NUMBER: NCT01868945.
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Although stressors are frequently linked to several negative health outcomes, experiencing stressors may be necessary for enhancing performance. At present, the literature is lacking a unified, comprehensive framework that accounts for both positive and negative outcomes following stressors. Therefore, we introduce the framework of hormesis, which has been applied in biological research for decades. According to hormesis, small-to-medium doses of a stressor can stimulate an organism's response, while large doses cause detrimental effects. In this article, we argue that these dose-response dynamics can be found in various domains of performance psychology (i.e., eustress and distress, psychological momentum, emotions, motivation, confidence, cognitive performance, training, skill acquisition, adversity, and trauma). Furthermore, hormesis also accounts for the inter- and intra-individual variability commonly found in responses to stressors. Finally, from an applied perspective, leveraging hormesis may stimulate new psychological interventions that mimic the well-known effects of (toxic) vaccinations at the level of behavior.
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Abstract gepubliceerd in Elsevier: Introduction: Recent research has identified the issue of ‘dose creep’ in diagnostic radiography and claims it is due to the introduction of CR and DR technology. More recently radiographers have reported that they do not regularly manipulate exposure factors for different sized patients and rely on pre-set exposures. The aim of the study was to identify any variation in knowledge and radiographic practice across Europe when imaging the chest, abdomen and pelvis using digital imaging. Methods: A random selection of 50% of educational institutes (n ¼ 17) which were affiliated members of the European Federation of Radiographer Societies (EFRS) were contacted via their contact details supplied on the EFRS website. Each of these institutes identified appropriate radiographic staff in their clinical network to complete an online survey via SurveyMonkey. Data was collected on exposures used for 3 common x-ray examinations using CR/DR, range of equipment in use, staff educational training and awareness of DRL. Descriptive statistics were performed with the aid of Excel and SPSS version 21. Results: A response rate of 70% was achieved from the affiliated educational members of EFRS and a rate of 55% from the individual hospitals in 12 countries across Europe. Variation was identified in practice when imaging the chest, abdomen and pelvis using both CR and DR digital systems. There is wide variation in radiographer training/education across countries.
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