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- Strawbridge, Rona J., et al.
(författare)
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Identification of a novel proinsulin-associated SNP and demonstration that proinsulin is unlikely to be a causal factor in subclinical vascular remodelling using Mendelian randomisation
- 2017
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Ingår i: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 266, s. 196-204
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Increased proinsulin relative to insulin levels have been associated with subclinical atherosclerosis (measured by carotid intima-media thickness (cIMT)) and are predictive of future cardiovascular disease (CVD), independently of established risk factors. The mechanisms linking proinsulin to atherosclerosis and CVD are unclear. A genome-wide meta-analysis has identified nine loci associated with circulating proinsulin levels. Using proinsulin-associated SNPs, we set out to use a Mendelian randomisation approach to test the hypothesis that proinsulin plays a causal role in subclinical vascular remodelling.Methods: We studied the high CVD-risk IMPROVE cohort (n = 3345), which has detailed biochemical phenotyping and repeated, state-of-the-art, high-resolution carotid ultrasound examinations. Genotyping was performed using Illumina Cardio-Metabo and Immuno arrays, which include reported proinsulin-associated loci. Participants with type 2 diabetes (n = 904) were omitted from the analysis. Linear regression was used to identify proinsulin-associated genetic variants.Results: We identified a proinsulin locus on chromosome 15 (rs8029765) and replicated it in data from 20,003 additional individuals. An 11-SNP score, including the previously identified and the chromosome 15 proinsulin-associated loci, was significantly and negatively associated with baseline IMTmean and IMTmax (the primary cIMT phenotypes) but not with progression measures. However, MR-Eggers refuted any significant effect of the proinsulin-associated 11-SNP score, and a non-pleiotropic SNP score of three variants (including rs8029765) demonstrated no effect on baseline or progression cIMT measures.Conclusions: We identified a novel proinsulin-associated locus and demonstrated that whilst proinsulin levels are associated with cIMT measures, proinsulin per se is unlikely to have a causative effect on cIMT.
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| 64. |
- Vimaleswaran, Karani S, et al.
(författare)
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Association of vitamin D status with arterial blood pressure and hypertension risk: a mendelian randomisation study.
- 2014
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Ingår i: The lancet. Diabetes & endocrinology. - 2213-8595 .- 2213-8587. ; 2:9, s. 719-29
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Tidskriftsartikel (refereegranskat)abstract
- Background Low plasma 25-hydroxyvitamin D (25[OH]D) concentration is associated with high arterial blood pressure and hypertension risk, but whether this association is causal is unknown. We used a mendelian randomisation approach to test whether 25(OH)D concentration is causally associated with blood pressure and hypertension risk. Methods In this mendelian randomisation study, we generated an allele score (25[OH]D synthesis score) based on variants of genes that affect 25(OH)D synthesis or substrate availability (CYP2R1 and DHCR7), which we used as a proxy for 25(OH)D concentration. We meta-analysed data for up to 108173 individuals from 35 studies in the D-CarDia collaboration to investigate associations between the allele score and blood pressure measurements. We complemented these analyses with previously published summary statistics from the International Consortium on Blood Pressure (ICBP), the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and the Global Blood Pressure Genetics (Global BPGen) consortium. Findings In phenotypic analyses (up to n=49363), increased 25(OH)D concentration was associated with decreased systolic blood pressure (β per 10% increase, −0·12 mm Hg, 95% CI −0·20 to −0·04; p=0·003) and reduced odds of hypertension (odds ratio [OR] 0·98, 95% CI 0·97–0·99; p=0·0003), but not with decreased diastolic blood pressure (β per 10% increase, −0·02 mm Hg, −0·08 to 0·03; p=0·37). In meta-analyses in which we combined data from D-CarDia and the ICBP (n=146581, after exclusion of overlapping studies), each 25(OH)D-increasing allele of the synthesis score was associated with a change of −0·10 mm Hg in systolic blood pressure (−0·21 to −0·0001; p=0·0498) and a change of −0·08 mm Hg in diastolic blood pressure (−0·15 to −0·02; p=0·01). When D-CarDia and consortia data for hypertension were meta-analysed together (n=142255), the synthesis score was associated with a reduced odds of hypertension (OR per allele, 0·98, 0·96–0·99; p=0·001). In instrumental variable analysis, each 10% increase in genetically instrumented 25(OH)D concentration was associated with a change of −0·29 mm Hg in diastolic blood pressure (−0·52 to −0·07; p=0·01), a change of −0·37 mm Hg in systolic blood pressure (−0·73 to 0·003; p=0·052), and an 8·1% decreased odds of hypertension (OR 0·92, 0·87–0·97; p=0·002). Interpretation Increased plasma concentrations of 25(OH)D might reduce the risk of hypertension. This finding warrants further investigation in an independent, similarly powered study.
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- Punkkinen, M. P. J., et al.
(författare)
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Thermodynamics of the pseudobinary GaAs1-xBix (0 ≤ x ≤ 1) alloys studied by different exchange-correlation functionals, special quasi-random structures and Monte Carlo simulations
- 2015
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Ingår i: Computational Condensed Matter. - : Elsevier. - 2352-2143. ; 5, s. 7-13
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Tidskriftsartikel (refereegranskat)abstract
- GaAs1-xBix alloys have useful properties for many optoelectronic applications. Although the crystal growth by molecular beam epitaxy is influenced by kinetics, it is also important to understand the thermodynamics of the alloys. The Gibbs formation energies and the immiscibility curve of the totally disordered GaAs1-xBix (0 ≤ x ≤ 1) are determined using special quasi-random structures (SQS) of different sizes, different exchange-correlation functionals and Monte Carlo simulations. The local density approximation gives slightly larger mixing enthalpies and smaller Bi solubilities than the generalized gradient approximation for the GaAs1-xBix alloys, if the semiconducting GaAs and metallic Ga and Bi are reference states. The 64 and 512 atom SQS give similar mixing enthalpies, except at x = 0.5, where as eight atom SQS overestimate the mixing enthalpy significantly. The disordered alloys are more stable than the most stable ordered phases except at very low temperatures. The spinodal transformation temperature corresponds approximately to the latest experimental results, if the separated systems can conform to their own lattice constants. The spinodal transformation temperature is decreased very significantly, if the decomposing phases are constrained to maintain lattice coherence with the substrate. The strain energies of the alloys and decomposing phases are large also at the surfaces.
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