University of Iceland

About: University of Iceland is a education organization based out in Reykjavik, Suðurnes, Iceland. It is known for research contribution in the topics: Population & Genome-wide association study. The organization has 5423 authors who have published 16199 publications receiving 694762 citations. The organization is also known as: Háskóli Íslands.

Vitamin D a systematic literature - review for the 5th edition of the Nordic Nutrition Recommendations

Abstract: Background : The present literature review is part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004. Objectives : The overall aim was to review recent scientific data on the requirements and health effects of vitamin D and to report it to the NNR5 Working Group, who is responsible for updating the current dietary reference values valid in the Nordic countries. Methods : The electronic databases MEDLINE and Swemed were searched. We formulated eight questions which were used for the search. The search terms related to vitamin D status and intake and different health outcomes as well as to the effect of different vitamin D sources on vitamin D status. The search was done in two batches, the first covering January 2000 March 2010 and the second March 2009 February 2011. In the first search, we focused only on systematic literature reviews (SLRs) and in the second on SLRs and randomized control trials (RCTs) published after March 2009. Furthermore, we used snowballing for SLRs and IRCTs published between February 2011 and May 2012. The abstracts as well as the selected full-text papers were evaluated in pairs. Results : We found 1,706 studies in the two searches of which 28 studies were included in our review. We found 7 more by snowballing, thus 35 papers were included in total. Of these studies, 31 were SLRs and 4 were RCTs. The SLRs were generally of good or fair quality, whereas that of the included studies varied from good to poor. The heterogeneity of the studies included in the SLRs was large which made it difficult to interpret the results and provide single summary statements. One factor increasing the heterogeneity is the large variation in the assays used for assessing 25-hydroxyvitamin D concentration [25(OH)D], the marker of vitamin D status. The SLRs we have reviewed conclude that the evidence for a protective effect of vitamin D is only conclusive concerning bone health, total mortality and the risk of falling. Moreover, the effect was often only seen in persons with low basal 25(OH)D concentrations. In addition, most intervention studies leading to these conclusions report that intervention with vitamin D combined with calcium and not vitamin D alone gives these benefits. It was difficult to establish an optimal 25(OH)D concentration or vitamin D intake based on the SLRs, but there are evidence that a concentration of ≥50 nmol/l could be optimal. The doseresponse studies relating vitamin D intake (fortification and supplementation) to S-25(OH)D suggested that an intake of 1-2.5 μg/day will increase the serum concentration by 1-2 nmol/l but this is dependent on the basal concentration with a response being greater when the basal concentration is low. Conclusion : Data show that a S-25(OH)D concentration of 50 nmol/l would reflect a sufficient vitamin D status. Results from this review support that the recommendation in NNR 2004 needs to be re-evaluated and increased for all age groups beyond 2 years of age. We refer to the total intake from food as well as supplements, given minimal sun exposure. Limited sunshine, however, does not reflect the situation for the majority of the Nordic population in the summertime. It should also be emphasized that there are large differences in results depending on assay methods and laboratories measuring 25(OH)D, adding to the uncertainty of determining an appropriate target concentration. Moreover, the doseresponse of vitamin D on serum 25(OH)D-concentrations is not well established and is dependent on the basal concentrations, sunshine exposure and dietary intake. We advise that these uncertainties should be taken into account when setting the final Nordic recommendations. Keywords : vitamin D; vitamin D requirements; systematic review; bone health; health outcomes (Published: 3 October 2013) Citation: Food & Nutrition Research 2013. 57 : 22671 - http://dx.doi.org/10.3402/fnr.v57i0.22671 Access the Appendices to this article – see Supplementary material under Article Tools online. Special Issue: This paper is part of the Nordic Nutrition Recommendations - The NNR5 project . More papers from this issue can be found at http://www.foodandnutritionresearch.net

Variable temperature effects of Open Top Chambers at polar and alpine sites explained by irradiance and snow depth

Abstract: Environmental manipulation studies are integral to determining biological consequences of climate warming. Open Top Chambers (OTCs) have been widely used to assess summer warming effects on terrest ...

Common genetic variants associated with open-angle glaucoma

Abstract: Open-angle glaucoma (glaucoma) is a major eye disorder characterized by optic disc pathology. Recent genome-wide association studies identified new loci associated with clinically relevant optic disc parameters, such as the optic disc area and vertical cup-disc ratio (VCDR). We examined to what extent these loci are involved in glaucoma. The loci studied include ATOH7, CDC7/TGFBR3 and SALL1 for optic disc area, and CDKN2B, SIX1, SCYL1/LTBP3, CHEK2, ATOH7 and DCLK1 for VCDR. We performed a meta-analysis using data from six independent studies including: the Rotterdam Study (n= 5736), Genetic Research in Isolated Populations combined with Erasmus Rucphen Family study (n= 1750), Amsterdam Glaucoma Study (n= 296) and cohorts from Erlangen and Tubingen (n= 1363), Southampton (n= 702) and deCODE (n= 36 151) resulting in a total of 3161 glaucoma cases and 42 837 controls. Of the eight loci, we found significant evidence (P= 1.41 × 10(-8)) for the association of CDKN2B with glaucoma [odds ratio (OR) for those homozygous for the risk allele: 0.76; 95% confidence interval (CI): 0.70-0.84], for the role of ATOH7 (OR: 1.28; 95% CI: 1.12-1.47) and for SIX1 (OR: 1.20; 95% CI: 1.10-1.31) when adjusting for the number of tested loci. Furthermore, there was a borderline significant association of CDC7/TGFBR3 and SALL1 (both P= 0.04) with glaucoma. In conclusion, we found consistent evidence for three common variants (CDKN2B, ATOH7 and SIX1) significantly associated with glaucoma. These findings may shed new light on the pathophysiological protein pathways leading to glaucoma, and point to pathways involved in the growth and development of the optic nerve.

Four novel Loci (19q13, 6q24, 12q24, and 5q14) influence the microcirculation in vivo.

Abstract: There is increasing evidence that the microcirculation plays an important role in the pathogenesis of cardiovascular diseases. Changes in retinal vascular caliber reflect early microvascular disease and predict incident cardiovascular events. We performed a genome-wide association study to identify genetic variants associated with retinal vascular caliber. We analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). All participants had retinal photography and retinal arteriolar and venular caliber measured from computer software. In the discovery cohorts, 179 single nucleotide polymorphisms (SNP) spread across five loci were significantly associated (p<5.0×10-8) with retinal venular caliber, but none showed association with arteriolar caliber. Collectively, these five loci explain 1.0%-3.2% of the variation in retinal venular caliber. Four out of these five loci were confirmed in independent replication samples. In the combined analyses, the top SNPs at each locus were: rs2287921 (19q13; p = 1.61×10-25, within the RASIP1 locus), rs225717 (6q24; p = 1.25×10-16, adjacent to the VTA1 and NMBR loci), rs10774625 (12q24; p = 2.15×10-13, in the region of ATXN2,SH2B3 and PTPN11 loci), and rs17421627 (5q14; p = 7.32×10-16, adjacent to the MEF2C locus). In two independent samples, locus 12q24 was also associated with coronary heart disease and hypertension. Our population-based genome-wide association study demonstrates four novel loci associated with retinal venular caliber, an endophenotype of the microcirculation associated with clinical cardiovascular disease. These data provide further insights into the contribution and biological mechanisms of microcirculatory changes that underlie cardiovascular disease.

Crustal structure above the Iceland mantle plume imaged by the ICEMELT refraction profile

Abstract: We thank Rob Staples for assistance and many helpful discussions. This work is funded by the Natural Environment Research Council (NERC) and National Science Foundation research grants; FD is supported by NERC. Instruments were loaned by the University of Cambridge, the University of Iceland, the NERC Geophysical Equipment Pool, the PASSCAL instrument pool, the Lamont-Doherty Earth Observatory, the Nordic Volcanological Institute, the University of Oregon and St Louis University. We thank Josef Holmjarn (shotmaster) and all who assisted in the field: Rob Staples and Mark Muller (Cambridge); Rob Dunn (Oregon); Yang Shen (Woods Hole); Arnar Hjartarson and Olafur Rognvaldsson (Orkustofnun); Hrappur Magnusson (independent), Randy and Adriana Kuehnel (The Carnegie Institute of Washington, DTM); also Einar Kjartansson (independent) and Bob Busby (PASSCAL). Thanks to the wardens of the mountain huts at Nýidalur and Laugafell, and special thanks to Magnus Oskarsson and his family at the farm Solvanes for looking after us and allowing us to store equipment at the farm. We thank Clare Enright for invaluable assistance with code and with data processing, and Helgi Torfason for supplying unpublished geological maps. Department of Earth Sciences, Cambridge, contribution number 5208.