Sample Of Twins Research Articles

Shared genetic influences between eating disorders and gastrointestinal disease in a large, population-based sample of adult women and men.

Some preliminary research suggests higher rates of gastrointestinal disease in individuals with eating disorders (EDs). However, research is limited, and it remains unknown what etiologic factors account for observed associations. This was the first study to examine how EDs and dimensional ED symptoms (e.g. body dissatisfaction, binge eating) are phenotypically and etiologically associated with gastrointestinal disease in a large, population-based twin sample. Adult female (N = 2980) and male (N = 2903) twins from the Michigan State University Twin Registry reported whether they had a lifetime ED (anorexia nervosa, bulimia nervosa, or binge-eating disorder) and completed a measure of dimensional ED symptoms. We coded the presence/absence of lifetime gastrointestinal disease (e.g. inflammatory bowel disease) based on responses to questions regarding chronic illnesses and medications. We first examined whether twins with gastrointestinal disease had higher rates of EDs and ED symptoms, then used correlated factors twin models to investigate genetic and environmental contributions to the overlap between disorders. Twins with gastrointestinal disease had significantly greater dimensional ED symptoms (β = 0.21, p < 0.001) and odds of a lifetime ED (OR 2.90, p = 0.001), regardless of sex. Shared genetic factors fully accounted for the overlap between disorders, with no significant sex differences in etiologic associations. Comorbidity between EDs and gastrointestinal disease may be explained by overlap in genetic influences, potentially including inflammatory genes implicated in both types of disorders. Screening for gastrointestinal disease in people with EDs, and EDs in those with gastrointestinal disease, is warranted.

Hypothalamic-pituitary-adrenal axis responsivity during adolescence in relation to psychopathic personality traits later in life

Psychopathic personality traits have been linked to low physiological arousal, particularly among high risk and forensic samples. A core indicator of physiological arousal is the activity of the hypothalamic-pituitary-adrenal (HPA) axis; however, findings of a link between HPA axis functioning and psychopathic personality traits have been inconsistent. Furthermore, given sex differences in both HPA axis responsivity and psychopathic personality traits, the association may be expected to differ between men and women. The aim of this study was to investigate the association between HPA axis responsivity in mid-adolescence and psychopathic personality traits in early adulthood and determine whether the association was moderated by sex. We examined this link in a general population sample of twins (N = 556). Adolescents participated in a psychosocial stress task during which samples of salivary cortisol were collected (11–15 years) and reported psychopathic personality traits using the Triarchic Psychopathy Measure (19–20 years). Multilevel linear regression models were estimated in which psychopathic personality traits (boldness, meanness and disinhibition), and their interactions with sex, were regressed on HPA axis responsivity. The study was pre-registered on the Open Science Framework (osf.io/gs2a8). Preliminary analyses showed that cortisol levels did not increase significantly during the stressor task but decreased during recovery. Results showed that there was no association between HPA axis responsivity in mid-adolescence and psychopathic personality traits in early adulthood. The associations were not moderated by sex. Findings suggest that HPA axis responsivity in mid-adolescence did not serve as a biological marker for psychopathic personality traits among young adults from the general population.

Heritability of amygdala reactivity to angry faces and its replicable association with the schizophrenia risk locus of miR-137.

Among healthy participants, the interindividual variability of brain response to facial emotions is associated with genetic variation, including common risk variants for schizophrenia, a heritable brain disorder characterized by anomalies in emotion processing. We aimed to identify genetic variants associated with heritable brain activity during processing of facial emotions among healthy participants and to explore the impact of these identified variants among patients with schizophrenia. We conducted a data-driven stepwise study including samples of healthy twins, unrelated healthy participants and patients with schizophrenia. Participants approached or avoided pictures of faces with negative emotional valence during functional magnetic resonance imaging (fMRI). We investigated 3 samples of healthy participants - including 28 healthy twin pairs, 289 unrelated healthy participants (genome-wide association study [GWAS] discovery sample) and 90 unrelated healthy participants (replication sample) - and 1 sample of 48 patients with schizophrenia. Among healthy twins, we identified the amygdala as the brain region with the highest heritability during processing of angry faces (heritability estimate 0.54, p < 0.001). Subsequent GWAS in both discovery and replication samples of healthy non-twins indicated that amygdala activity was associated with a polymorphism in the miR-137 locus (rs1198575), a micro-RNA strongly involved in risk for schizophrenia. A significant effect in the same direction was found among patients with schizophrenia (p = 0.03). The limited sample size available for GWAS analyses may require further replication of results. Our data-driven approach shows preliminary evidence that amygdala activity, as evaluated with our task, is heritable. Our genetic associations preliminarily suggest a role for miR-137 in brain activity during explicit processing of facial emotions among healthy participants and patients with schizophrenia, pointing to the amygdala as a brain region whose activity is related to miR-137.

The Missing Link: Testing Galactic Chemical Evolution Models with the First Multi-isotopic Abundances in Solar Twin Stars

We present the first isotopic abundances of both 13CO and C18O in solar twin stars and test the results against several galactic chemical evolution (GCE) models with different nucleosynthesis prescriptions. First, we compare M-band spectra from IRTF/iSHELL to synthetic spectra generated from custom solar atmosphere models using the PHOENIX atmosphere code. Next, we compare our calculated abundances to GCE models that consider isotopic yields from massive stars, asymptotic giant branch stars, and fast-rotating stars. The 12C/13C ratios determined for this sample of solar twins are consistent with predictions from the selected GCE models; however, the 16O/18O ratios tentatively contradict these predictions. This project constitutes the first in a stellar chemical abundance series seeking to (1) support the James Webb Space Telescope as it characterizes exoplanet atmospheres, interiors, and biosignatures by providing host star abundances; (2) identify how unexplored stellar abundances reveal the process of galactic chemical evolution and correlate with star formation, interior, age, metallicity, and activity; and (3) provide improved stellar ages using stellar abundance measurements. By measuring elemental and isotopic abundances in a variety of stars, we not only supply refined host star parameters, but also provide the necessary foundations for complementary exoplanet characterization studies—and ultimately contribute to the exploration of galactic, stellar, and planetary origins and evolution.

CmVCall: An automated and adjustable nanopore analysis pipeline for heteroplasmy detection of the control region in human mitochondrial genome

Genetic associations between human mitochondrial DNA (mtDNA) heteroplasmy and mitochondrial diseases, aging, and cancer have been elaborated, contributing a lot to the further understanding of mtDNA polymorphic spectrum in anthropology, population, and forensic genetics. In the past decade, heteroplasmy detection using Sanger sequencing and next generation sequencing (NGS) was hampered by the former’s inefficiency and the latter’s inherent bias due to amplification and mapping of short reads, respectively. Nanopore sequencing stands out for its ability to yield long contiguous segments of DNA, providing a new insight into heterogeneity authentication. In addition to MinION from Oxford Nanopore Technologies, an alternative nanopore sequencer QNome (Qitan Technology) has also been applied to various biological research and the forensic applicability of this platform has been proved recently. In this study, we evaluated the performance of four commonly used variant callers in the heterogeneity authentication of the control region of human mtDNA based on simulations of different ratios generated by mixing QNome nanopore sequencing reads of two synthetic sequences. Then, an open-source and python-based nanopore analytics pipeline, CmVCall was developed and incorporated multiple programs including reads filtering, removal of nuclear mitochondrial sequences (NUMTs), alignment, optional ‘Correction’ mode, and heterogeneity identification. CmVCall can achieve high precision, accuracy, and recall of 100%, 99.9%, and 92.3% with a 5% heteroplasmy level in ‘Correction’ mode. Moreover, blood, saliva, and hair shaft samples from monozygotic (MZ) twins were used for heterogeneity evaluation and comparison with the NGS data. Results of MZ twin samples showed that CmVCall could identify more point heteroplasmy sites, revealing significant levels of inter- and intra-individual mtDNA polymorphism. In conclusion, we believe that this analysis pipeline will lay a solid foundation for the development of a comprehensive nanopore analysis pipeline targeting the whole mitochondrial genome.

GENETIC STUDY OF KRABBE LYSOSOME METABOLIC DISEASE

We studied blood samples of identical twins who are girls suspicious of the lysosome metabolic disease. For diagnostics goal we used New Generation Sequencing – NGS method and diagnostic amplicon panel. Diagnostic panel represents primers for the following diseases: Krabbe disease, mucopolysaccharidosis Type II (Hanter disease), Niemann-Pick disease, mucopolysaccharidosis Type IV (Morquio disease), Fabry disease, multiple sulfatase deficit, Gaucher disease, gangliosidase, mucopolysaccharidosis Type 1 (Gurler disease), mucopolysaccharidosis Type VII (Leya disease), and juvenile Parkinson disease. In studied material when analyzing GALC gene with molecular-genetic methods there was substitution of one nucleotide fragment GTCAG of c.1834 in intron 15 with another nucleotide fragment AGTCAC and that was identified (c.1834 GTCAG&gt;AGTCAC). There is no information about this mutation in the world scientific literature. This is for the first time that this mutation of GALC gene was found in Azerbaijani children.

Associations between socioeconomic factors and depression in Sri Lanka: The role of gene-environment interplay

BackgroundLow socioeconomic status is a risk factor for depression. The nature and magnitude of associations can differ cross-culturally and is influenced by a range of contextual factors. We examined the aetiology of socioeconomic indicators and depression symptoms and investigated whether socioeconomic indicators moderate genetic and environmental influences on depression symptoms in a Sri Lankan population. MethodsData were from a population-based sample of twins (N = 2934) and singletons (N = 1035) in Colombo, Sri Lanka. Standard of living, educational attainment, and financial strain were used to index socioeconomic status. Depression symptoms were assessed using the Revised Beck Depression Inventory. Structural equation modelling explored genetic and environmental influences on socioeconomic indicators and depression symptoms and moderation of aetiological influences on depression symptoms by socioeconomic status. ResultsDepression symptoms were associated with lower standard of living, lower educational attainment, and financial strain. Sex differences were evident in the aetiology of standard of living, with a small contribution of genetic influences in females. Educational attainment was moderately heritable in both males and females. Total variance in depression was greater among less socioeconomically advantaged individuals. Modest evidence of moderation of the aetiology of depression by standard of living and education was observed. LimitationsWhile the sample is representative of individuals living in Colombo District, it may not be representative of different regions of Sri Lanka. ConclusionsThe aetiology of depression varies across socioeconomic contexts, suggesting a potential mechanism through which socioeconomic disadvantage increases the risk for depression in Sri Lanka. Findings have implications for cross-cultural investigations of the role of socioeconomic factors in depression and for identifying targets for social interventions.

Chorionicity-associated variation in metabolic phenotype of cord blood in twin

BackgroundMonochorionic (MC) twins present a higher incidence of unfavorable clinical perinatal outcomes than dichorionic (DC) twins, often in association with placental vascular anastomosis. In this study, we profiled the umbilical cord plasma metabolomes of uncomplicated MC and DC twin pregnancies and related these to several offspring outcomes, previously associated with birthweight.MethodsUmbilical vein blood samples were collected at birth from 25 pairs of uncomplicated MC twins and 24 pairs of uncomplicated DC twins. The samples were subjected to gas chromatography-mass spectrometry-based metabolomics. 152 metabolites were identified from the cord plasma samples of MC and DC twins. Partial least squares discriminant analysis and pathway analysis were performed to compare within DC/MC twin pairs and between DC and MC twins. A generalized estimating equation (GEE) model was utilized to explore the correlation between metabolic differences and birthweight discordance within and between twin pairs.ResultsOur study revealed clear differences between the metabolite profiles of umbilical cord plasma of MC and DC twins. Metabolite profiles in MC within twin pairs and DC within twin pairs were characterized by the differences in 2 − hydroxyglutaramic acid levels and nicotinamide levels, respectively. The metabolic pathways of GSH, tryptophan, and fatty acid metabolism, were significantly downregulated in MC twins compared to DC twins. In addition, the concentration of caffeine and decamethyl-cyclopentasiloxane (D5) was positively correlated with birthweight in MC and DC twins.ConclusionThis study demonstrated that the altered metabolites in umbilical plasma made contributions to the different chorionicities between uncomplicated MC twins and DC twins. The chorionicity of twins seems to affect the metabolic cross-talk between co-twin pairs and be related to birthweight discordance of twins.

Management of twin reversed arterial perfusion sequence: eight cases over 13 years.

Twin reversed arterial perfusion (TRAP) sequence is a rare condition that affects primarily monozygotic monochorionic twin pregnancies in which a normal twin acts as a pump (donor) for an acardiac recipient (perfuse) twin. We report our experience over the last 13 years at a tertiary health care center. Descriptive, retrospective case series SETTING: Tertiary health care center PATIENTS AND METHODS: All TRAP cases managed between the years 2009 and 2022 at our Fetal Diagnosis and Therapy Center were included. Data recorded included demographic and clinical information which was used to generate descriptive data. Patients were managed by a multidisciplinary team with variable interventions. Survival of normal twin SAMPLE SIZE: Eight RESULTS: Eight pregnant women with TRAP syndrome were managed at our center during that period. One was monozygotic monochorionic and the others were monochorionic diamniotic. Median maternal age at presentation was 27 years and median gestational age at diagnosis was 23 weeks. All were diagnosed with ultrasound (US) imaging. Three were managed with bipolar ligation of the cord of the acardiac twin under general anesthesia, one US-guided (single port) and 2 fetoscopic (2 ports) with a median operative time of 39 minutes. The last five cases were managed with US-guided radiofrequency ablation (RFA) under local anesthesia, one needed 2 sessions, 1 week apart. The median duration of the RFA procedure was 23 minutes. There were no complications and all had viable normal babies born at a median of 32 weeks of gestation (6 C-section, 2 spontaneous membrane rupture). Acardiac twin cord ligation and RFA are feasible and safe options with excellent outcome for TRAP syndrome. RFA may be preferable owing to its less invasiveness under local anesthesia. None, given the rarity of the disease and the study design. None.

Associations of broad eating disorder symptoms with later alcohol problems in Finnish adult twins: A nationwide 10-year follow-up.

Eating disorders are associated with subsequent alcohol problems, but it is not known whether this association also extends to broader eating disorder symptoms not captured by clinical diagnoses. We assessed the longitudinal association of broad eating disorder symptoms with alcohol problems in a nationwide twin sample (FinnTwin16). Finnish women (N = 1905) and men (N = 1449) self-reported their eating disorder symptoms using the Eating Disorder Inventory-2 Bulimia, Drive for Thinness, and Body Dissatisfaction subscales at the mean age of 24.4 years in 2000-2003. A subsample of participants also completed items on drive for muscularity, height dissatisfaction, and muscle-enhancing supplement use. Alcohol problems were assessed 10 years later at the age of 34.1 in 2010-2012 with the Rutgers Alcohol Problem Index. Eating disorder symptoms were associated with later alcohol problems (odds ratio per point increase 1.02-1.18). Bulimia showed stronger associations among men than women (p for interaction .012). Drive for muscularity and height dissatisfaction were also associated with later alcohol problems, but supplement use was not. When accounting for baseline alcohol problems, only Bulimia (among women and men) and Drive for Thinness (among men) were significantly associated with later alcohol problems. Bulimia was also significantly associated with later alcohol problems in within-twin-pair analyses among dizygotic twins, but not among monozygotic twins. In a longitudinal setting, eating disorder symptoms were associated with later alcohol problems. Bulimic symptoms were a stronger risk factor for men than women. These associations may be attributable to baseline alcohol problems, childhood environment and genetic liability. This study found that both young adult women and men with broad eating disorder symptoms are at a higher risk of alcohol-related problems than those without such symptoms. Men with bulimic symptoms were at a particularly high risk. These findings emphasize the need for better prevention and treatment of disordered eating, body image concerns and alcohol problems for both young adult women and men.

The latent structure of emerging cognitive abilities: An infant twin study

It is well known that genetic factors account for up to 70% of variability in cognition from childhood to adulthood. However, less is known about the first year of life. This study investigated the etiological factors influencing individual variability in different domains of emerging cognitive and motor abilities in early infancy, and to what extent genetic and environmental influences are unique or shared across different domains. We compared multivariate twin models built on scores from the five scales of the Mullen Scales of Early Learning (MSEL) in a community sample of monozygotic and dizygotic twins at 5 months of age (n=567). The results indicated a hierarchical etiological structure whereby a general genetic latent factor accounted for 54% of variance underlying the different domains of emerging cognitive and motor abilities (A=0.54, confidence interval CI=[0; 0.82]). We also found additional genetic influences that were specific to early motor and language development. Unlike previous findings on older children, we did not find significant influences of shared environment on the shared factor (C=0, CI=[0, 0.57]), or any specific scale. Furthermore, influences of unique environment, which include measurement error, were moderate and statistically significant (E=0.46, CI=0.18; 0.81]). This study provides strong evidence for a unitary hierarchical structure across different domains of emerging cognition. Evidence that a single common etiological factor, which we term infant g, contributes to a range of different abilities supports the view that in young infants, intrinsic and general neurodevelopmental processes are key drivers of observable behavioural differences in specific domains.

Co-twin design in brain imaging-review on biomarkers of Alzheimer's disease.

Twin samples allow to conduct a quasi-experimental co-twin case-control approach that can control for genetic and environmental confounding in brain-cognition associations, being more informative on causality compared with studies in unrelated individuals. We conducted a review of studies that have utilized discordant co-twin design to investigate the associations of brain imaging markers of Alzheimer's disease and cognition. Inclusion criteria encompassed twin pairs discordant for cognition or Alzheimer's disease imaging markers and reporting of within-twin pair comparison on the association between cognition and brain measures. Our PubMed search (2022 April 23, updated 2023 March 9) resulted in 18 studies matching these criteria. Alzheimer's disease imaging markers have been addressed only by few studies, most with small sample size. Structural magnetic resonance imaging studies have indicated greater hippocampal volume and thicker cortex in co-twins with better cognitive performance compared with their co-twins with poorer cognitive performance. No studies have looked at cortical surface area. Positron emission tomography imaging studies have suggested that lower cortical glucose metabolism rate and higher cortical neuroinflammation, amyloid, and tau accumulations are related to poorer episodic memory in within-twin pair comparisons. Thus far, only cross-sectional within-twin pair associations of cortical amyloid and hippocampal volume with cognition have been replicated.

Prevalence and heritability of alcohol use disorders in 18-year old Swedish twins.

Background: Heritability of alcohol use disorders (AUDs) varies widely, with reported estimates of 30-78% in twin studies. This variation might be due to methodological differences (e.g., using different thresholds for AUDs, age differences between samples). Aim: To investigate the heritability of AUDs in a nation-wide sample of male and female twins in late adolescence (18 years). Participants: The study is based on data from 8,330 18-year-old Swedish monozygotic (MZ) and dizygotic (DZ) twins from the Child and Adolescent Twin Study (Sweden). Method: Univariate sex-limitation twin analyses were performed using (a) total AUDIT score, (b) different AUDIT cut-offs (AUDIT-10: potentially harmful alcohol use and most likely alcohol dependent ; AUDIT-C: potential hazardous alcohol consumption/active alcohol use disorders), and (c) a risk-group classification for alcohol dependence based on AUDIT total score. Results: Prevalence of potential hazardous alcohol consumption/active alcohol use was 57.1%, and for potentially harmful alcohol use prevalence was 26.5%. Prevalence was higher among females (59.0% and 31.1% respectively) than males (54.4% and 20.0% respectively). Overall, the results of the univariate model fitting indicated that there were qualitative sex differences in the genetic and environmental influences on AUDs, with generally moderate heritability estimates ranging between 0.37 and 0.50. Discussion: At odds with previous research, a harmful/hazardous drinking pattern was more common in this age group among females than a low-risk drinking pattern (where males were overrepresented). Heritability estimates were moderate throughout all measures and cut-offs, with equally high contributions from shared and non-shared environment. Sex-limitation models revealed qualitative sex differences for AUDs, suggesting that different genetic and/or environmental factors influence variation in AUDs in males and females.

DNA methylome profiling of blood to identify individuals in a pair of monozygotic twins

BackgroundShort tandem repeat (STR) markers cannot be used to distinguish between genetically identical monozygotic (MZ) twins, causing problems in a case with an MZ twin as a suspect. Many studies have shown that in older MZ twins, there are significant differences in overall content and genomic distribution of methylation.ObjectiveIn this study, we analyzed the DNA methylome profile of blood to identify recurrent differentially methylated CpG sites (DMCs) to discriminate between MZ twins.MethodsBlood samples were collected from 47 paired MZ twins. We performed the DNA methylation profiling using the HumanMethylation EPIC BeadChip platform and identified recurrent DMCs between MZ twins. Then, Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and motif enrichment analyses were performed to reveal the biological functions of recurrent DMCs. We collected DNA methylome data from the Gene Expression Omnibus (GEO) public database to verify the recurrent DMCs between MZ twins.ResultsWe identified recurrent DMCs between MZ twin samples and observed that they were enriched in immune-related genes. In addition, we verified our DMCs in a public dataset.ConclusionOur results suggest that the methylation level at recurrent DMCs between MZ twins may serve as a valuable biomarker for identification of individuals in a pair of MZ twins.

Genetic and environmental contributions to the subjective burden of social isolation during the COVID-19 pandemic

BackgroundFeelings of loneliness and the burden of social isolation were among the most striking consequences of widespread containment measures, such as “social distancing”, during the COVID-19 pandemic. Because of the potential impact on people’s health, there has been increased interest in understanding the mechanisms and factors that contributed to feelings of loneliness and the burdens of social isolation. However, in this context, genetic predisposition has been largely ignored as an important factor. This is problematic because some of the phenotypic associations observed to date may in fact be genetic. The aim of this study is, therefore, to examine the genetic and environmental contributions to the burden of social isolation at two time points during the pandemic. In addition, we examine whether risk factors identified in previous studies explain genetic or environmental contributions to the burden of social isolation.MethodsThe present study is based on a genetically sensitive design using data from the TwinLife panel study, which surveyed a large sample of adolescent and young adult twins during the first (N = 798) and the second (N = 2520) lockdown in Germany.ResultsWe find no substantive differences in genetic and environmental contributions to social isolation burden over the course of the pandemic. However, we find the determinants highlighted as important in previous studies can explain only a small proportion of the observed variance in the burden of social isolation and mainly explained genetic contributions.ConclusionsWhile some of the observed associations appear to be genetic, our findings underscore the need for further research, as the causes of individual differences in burden of social isolation remain unclear.

Exploring rare differences in mitochondrial genome between MZ twins using Ion Torrent semiconductor sequencing

Monozygotic (MZ) twins are considered to be genetically identical in that they have the same genomic DNA sequences in theory, and thus cannot be differentiated using forensic standard STR-based DNA profiling. However, a recent study employed deep sequencing to explore extremely rare mutations in the nuclear genome and reported that the mutation analysis could be applied to differentiate between MZ twins. Compared with the nuclear genome, the mitochondrial DNA (mtDNA) exhibits higher mutation rates due to fewer DNA repair mechanisms in the mitochondrial genome (mtGenome) and the lack of proofreading capability of the mtDNA polymerase. In a previous study, we used Illumina ultra-deep sequencing to describe point heteroplasmy (PHP) and nucleotide variant of the mtGenomes in venous blood samples of MZ twins. In the present study, we characterized minor differences of the mtGenomes in three tissue samples from seven sets of MZ twins using Ion Torrent semiconductor sequencing (Thermo Fisher Ion S5 XL system) and commercialized mtGenome sequencing kit (Precision ID mtDNA Whole Genome Panel). PHP was observed in blood samples from one set of MZ twins and in saliva samples from two sets of twins, but it presented in hair shaft samples from all seven sets of MZ twins. Overall, the coding region of the mtGenome exhibits more PHPs than the control region. The results of this study have further attested the competence of mtGenome sequencing in differentiating between MZ twins, and that among the three kinds of samples tested, hair shaft is more likely to accumulate minor differences in the mtGenomes of MZ twins.

Infrared ellipsometry study of the charge dynamics in K3p -terphenyl

We report an infrared ellipsometry study of the charge carrier dynamics in polycrystalline ${\mathrm{K}}_{x}p$-terphenyl samples with nominal $x=3$, for which signatures of high-temperature superconductivity were previously reported. The infrared spectra are dominated by two Lorentzian bands with maxima around 4000 and $12 000 {\mathrm{cm}}^{\ensuremath{-}1}$ which, from a comparison with calculations based on a H\"uckel model, are assigned to intramolecular excitations of $\ensuremath{\pi}$ electrons of the anionic $p$-terphenyl molecules. The intermolecular electronic excitations are much weaker and give rise to a Drude peak and a similarly weak Lorentzian band around $220 {\mathrm{cm}}^{\ensuremath{-}1}$. A dc resistivity of about $0.3 \mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$ at $300\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ is deduced from the IR data, comparable to values measured by electrical resistivity on a twin sample. The analysis of the temperature dependence of the low-frequency response reveals a gradual decrease of the plasma frequency and the scattering rate of the Drude peak below $300\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ that gets anomalously enhanced below $90\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The corresponding missing spectral weight of the Drude peak appears blueshifted towards the Lorentz band at $220 {\mathrm{cm}}^{\ensuremath{-}1}$. This characteristic blueshift signifies an enhanced localization of the charge carriers at low temperatures and contrasts the behavior expected for a bulk superconducting state for which the missing spectral weight would be redshifted to a delta function at zero frequency that accounts for the loss-free response of the superconducting condensate. Our data might still be compatible with a filamentary superconducting state with a volume fraction well below the percolation limit for which the spatial confinement of the condensate can result in a plasmonic resonance at finite frequency.

Genetically identical twin-pair difference models support the amyloid cascade hypothesis.

The amyloid cascade hypothesis has strongly impacted the Alzheimer's disease research agenda and clinical trial designs over the past decades, but precisely how amyloid-β pathology initiates the aggregation of neocortical tau remains unclear. We cannot exclude the possibility of a shared upstream process driving both amyloid-β and tau in an independent manner instead of there being a causal relationship between amyloid-β and tau. Here, we tested the premise that if a causal relationship exists, then exposure should be associated with outcome both at the individual level as well as within identical twin-pairs, who are strongly matched on genetic, demographic and shared environmental background. Specifically, we tested associations between longitudinal amyloid-β PET and cross-sectional tau PET, neurodegeneration and cognitive decline using genetically identical twin-pair difference models, which provide the unique opportunity of ruling out genetic and shared environmental effects as potential confounders in an association. We included 78 cognitively unimpaired identical twins with [18F]flutemetamol (amyloid-β)-PET, [18F]flortaucipir (tau)-PET, MRI (hippocampal volume) and cognitive data (composite memory). Associations between each modality were tested at the individual level using generalized estimating equation models, and within identical twin-pairs using within-pair difference models. Mediation analyses were performed to test for directionality in the associations as suggested by the amyloid cascade hypothesis. At the individual level, we observed moderate-to-strong associations between amyloid-β, tau, neurodegeneration and cognition. The within-pair difference models replicated results observed at the individual level with comparably strong effect sizes. Within-pair differences in amyloid-β were strongly associated with within-pair differences in tau (β = 0.68, P < 0.001), and moderately associated with within-pair differences in hippocampal volume (β = -0.37, P = 0.03) and memory functioning (β = -0.57, P < 0.001). Within-pair differences in tau were moderately associated with within-pair differences in hippocampal volume (β = -0.53, P < 0.001) and strongly associated with within-pair differences in memory functioning (β = -0.68, P < 0.001). Mediation analyses showed that of the total twin-difference effect of amyloid-β on memory functioning, the proportion mediated through pathways including tau and hippocampal volume was 69.9%, which was largely attributable to the pathway leading from amyloid-β to tau to memory functioning (proportion mediated, 51.6%). Our results indicate that associations between amyloid-β, tau, neurodegeneration and cognition are unbiased by (genetic) confounding. Furthermore, effects of amyloid-β on neurodegeneration and cognitive decline were fully mediated by tau. These novel findings in this unique sample of identical twins are compatible with the amyloid cascade hypothesis and thereby provide important new knowledge for clinical trial designs.

Sexual-orientation differences in risk of health-related impaired ability to work and to remain in the paid workforce: a prospective population-based twin study

BackgroundStudies consistently show an increased risk of poor health among sexual minorities (i.e., those identifying as lesbian, gay, bisexual [LGB] or other non-heterosexuals individuals), as compared to those identifying as heterosexual. It is largely unknown whether the increased risk of mental and physical health problems among sexual minorities is also reflected in an increased risk of health-related impaired ability to work, in terms of sickness absence (SA) and disability pension (DP), or successfully remain in the paid workforce. This study made use of a large sample of Swedish twins with self-reported information about sexual behavior in young adulthood to examine sexual orientation difference in SA and DP during a 12-year follow-up period.MethodData from the Swedish Twin project of Disability pension and Sickness absence (STODS), including Swedish twins born 1959–1985 was used (N = 17,539; n = 1,238 sexual minority). Self-report survey data on sexual behavior was linked to information about SA and DP benefits from the MicroData for Analysis of the Social Insurance database (MiDAS), the National Social Insurance Agency. Sexual orientation differences in SA and DP between 2006 and 2018 was analyzed, as well as, the influence of sociodemographic, social stress exposure (i.e., victimization, discrimination), mental health treatment, and family confounding on these differences.ResultsCompared to heterosexuals, sexual minorities were more likely to having experienced SA and having been granted DP. The odds were highest for DP, where sexual minorities were 58% more likely to having been granted DP compared to heterosexuals. The higher odds for SA due to any diagnosis could largely be explained by sociodemographic factors. The higher odds of SA due to mental diagnosis could partially be explained by increased risk of being exposed to discrimination and victimization, and partially by having received treatment with antidepressant medication. The higher odds of being granted DP could also partially be explain by increased risk of being exposed to social stress and treatment with antidepressant medication.ConclusionTo our knowledge, this is the first study to report on sexual orientation differences in risk of SA and DP in a population-based sample. We found higher period prevalence of both SA and DP among sexual minorities as compared to heterosexuals. The higher odds of SA and DP could partially or fully be explained by sexual orientation differences in sociodemographic factors, exposure to social stress, and antidepressant treatment for depression. Future studies can extend these findings by continuing to investigate risk factors for SA and DP among sexual minorities and how such factors can be reduced.

Application of 3D Scanning Method to Assess Mounting Holes’ Shape Instability of Pinewood

Swelling and shrinkage anisotropy affect the susceptibility to an assembly of wooden elements by changing designed clearances or interference fits. This work described the new method to measure mounting holes' moisture-induced shape instability and its verification using three sets of twin samples made of Scots pinewood. Each set of samples contained a pair with different grain patterns. All samples were conditioned under reference conditions (relative air humidity-RH = 60% and temperature 20 °C), and their moisture content (MC) reached equilibrium (10.7 ± 0.1%). On the side of each sample, the seven mounting holes of 12 mm in diameter were drilled. Immediately after drilling, Set 1 was used to measure the effective hole diameter with 15 cylindrical plug-gauges with diameters of 0.05 mm step, while Set 2 and Set 3 were separately re-seasoned by six months in two extreme conditions. Set 2 was conditioned with air at 85% RH (reached an equilibrium MC of 16.6 ± 0.5%), while Set 3 was exposed to air at 35% RH (reached an equilibrium MC of 7.6 ± 0.1%). Results of the plug gauge tests highlighted that holes in the samples subjected to swelling (Set 2) increased an effective diameter in the range of 12.2-12.3 mm (1.7-2.5%), while samples subjected to shrinking (Set 3) reduced the effective diameter to 11.9-11.95 mm (0.8-0.4%). To accurately reproduce the complex shape of the deformation, gypsum casts of holes were made. The 3D optical scanning method was used to read the gypsum casts' shape and dimensions. The 3D surface map of deviations analysis provided more detailed information than the plug-gauge test results. Both the shrinking and swelling of the samples changed the shapes and sizes of the holes, but shrinking reduced the effective diameter of the hole more than swelling increased it. The moisture-induced changes in the shape of holes are complex: the holes ovalized with a different range, depending on the wood grain pattern and hole depth, and were slightly extended in diameter at the bottom. Our study provides a new way to measure 3D hole initial shape changes in wooden elements during desorption and absorption.