Mendelian randomization analysis does not support causal associations of birth weight with hypertension risk and blood pressure in adulthood

Epidemiology studies suggested that low birthweight was associated with a higher risk of hypertension in later life. However, little is known about the causality of such associations. In our study, we evaluated the causal association of low birthweight with adulthood hypertension following a standard analytic protocol using the study-level data of 183,433 participants from 60 studies (CHARGE-BIG consortium), as well as that with blood pressure using publicly available summary-level genome-wide association data from EGG consortium of 153,781 participants, ICBP consortium and UK Biobank cohort together of 757,601 participants. We used seven SNPs as the instrumental variable in the study-level analysis and 47 SNPs in the summary-level analysis. In the study-level analyses, decreased birthweight was associated with a higher risk of hypertension in adults (the odds ratio per 1 standard deviation (SD) lower birthweight, 1.22; 95% CI 1.16 to 1.28), while no association was found between genetically instrumented birthweight and hypertension risk (instrumental odds ratio for causal effect per 1 SD lower birthweight, 0.97; 95% CI 0.68 to 1.41). Such results were consistent with that from the summary-level analyses, where the genetically determined low birthweight was not associated with blood pressure measurements either. One SD lower genetically determined birthweight was not associated with systolic blood pressure (β = − 0.76, 95% CI − 2.45 to 1.08 mmHg), 0.06 mmHg lower diastolic blood pressure (β = − 0.06, 95% CI − 0.93 to 0.87 mmHg), or pulse pressure (β = − 0.65, 95% CI − 1.38 to 0.69 mmHg, all p > 0.05). Our findings suggest that the inverse association of birthweight with hypertension risk from observational studies was not supported by large Mendelian randomization analyses

Evolution of impurity incorporation during ammonothermal growth of GaN

Ammonothermally grown GaN is a promising substrate for high-power optoelectronics and electronics thanks to its scalability and high structural perfection. Despite extensive research, ammonothermal GaN still suffers from significant concentrations of impurities. This article discusses the evolution of impurity incorporation during growth of basic ammonothermal GaN, in specific whether the impurity concentration changes temporally along the growth direction and how the autoclave influences the impurity concentration. The effect of the impurities on the structural, electrical and optical properties of the grown crystal is also discussed. The chemical analysis is carried out by time of flight secondary ion mass spectroscopy (ToF-SIMS) and laser-ablation inductively-coupled plasma mass spectroscopy (LA-ICP-MS). Strain and dislocation generation caused by impurity concentration gradients and steps are studied by synchrotron radiation x-ray topography (SR-XRT). Fourier transform infrared (FTIR) reflectivity is used to determine the effect of the impurities on the free carrier concentration, and the luminescent properties are studied by low temperature photoluminescence (PL). The influence of the autoclave is studied by growing a single boule in multiple steps in several autoclaves. LA-ICP-MS and ToF-SIMS ion intensities indicate that the impurity concentrations of several species vary between different autoclaves by over an order of magnitude. SR-XRT measurements reveal strain at the growth interfaces due to impurity concentration gradients and steps. Oxygen is determined to be the most abundant impurity species, resulting in a high free carrier concentration, as determined by FTIR. The large variation in Mn concentration dramatically affects PL intensity

Political Learning among Youth: Exploring Patterns of Students' First Political Awakening

This article focuses on students’ first political learning and explores the research question, what dynamic patterns of political learning can be explored among a selection of young, diverse Danish students’ first political interests? The authors use theories of learning in their analytical approach to students´ stories. A group of 10 young students who claim a certain political interest and attend a social studies course in Danish upper secondary school were selected to interview. A “life story approach” is used in the interviews and in the analytical approach. Findings: contrary to many “single agent studies in the tradition” of political socialization, the authors find that all students display a complex pattern of political influence. The influence from various agents like school, family, media and peers is also rather complex. Students are not passive recipients of influence, but are active constructors of their political life. Their emotions and social environment are highly important for their political orientation. It is recommended that further research focus on dynamic learning and on arenas for political learning rather than on “single agent studies.” Recommendations for teaching are made

Association of alcohol consumption with allergic disease and asthma: A multi-centre Mendelian randomization analysis.

Aims To use the rs1229984 variant associated with alcohol consumption as an instrument for alcohol consumption to test the causality of the association of alcohol consumption with hay fever, asthma, allergic sensitization and serum total immunoglobulin (Ig) E. Design Observational and Mendelian randomization analyses using genetic variants as unbiased markers of exposure to estimate causal effects, subject to certain assumptions. Setting Europe. Participants We included a total of 466 434 people aged 15-82 years from 17 population-based studies conducted from 1997 to 2015. Measurements The rs1229984 (ADH1B) was genotyped; alcohol consumption, hay fever and asthma were selfreported. Specific and total IgE were measured from serum samples. Findings Observational analyses showed that ever-drinking versus non-drinking, but not amount of alcohol intake, was positively associatedwith hay fever and inversely associated with asthma but not with allergic sensitization or serum total immunoglobulin (Ig) E. However, Mendelian randomization analyses did not suggest that the observational associations are causal. The causal odds ratio (OR) per genetically assessed unit of alcohol/week was an OR = 0.907 [ 95% confidence interval (CI) = 0.806, 1.019; P = 0.101] for hay fever, an OR = 0.897 (95% CI = 0.790, 1.019; P = 0.095) for asthma, an OR = 0.971 (95% CI = 0.804, 1.174; P = 0.763) for allergic sensitization and a 4.7% change (95% CI = -5.5%, 14.9%; P = 0.366) for total IgE. Conclusions In observational analyses, ever-drinking versus not drinking was positively associated with hay fever and negatively associated with asthma. However, the Mendelian randomization results were not consistent with these associations being causal