Heritability of daytime cortisol levels in children

INTRODUCTION Cortisol is a steroid hormone secreted by the outer cortex of the adrenal gland. Its secretion is stimulated by ACTH (adrenocorticotrophic hormone), produced in the pituitary in response to corticotropin-releasing hormone (CRH), a product from neurons in the paraventricular nucleus of the hypothalamus.After its release, the major part of cortisol binds to the plasma proteins corticosteroid binding globulin (CBG, or transcortin) and albumin, which prevents the hormone from penetrating the membranes of their target cells. About 3--5% of the total cortisol is the unbound, biologically active fraction. This active fraction has permissive, suppressive, stimulatory, and preparative action effects in the realms of cardiovascular function, fluid volume and hemorrhage, immunity and inflammation, metabolism, neurobiology, and reproductive physiology (Sapolsky, Romero, and Munck, 2000). Although cortisol is mainly known for its pivotal role in generating an adequate response to phy

Resemblances of Parents and Twins in Sport Participation and Heart Rate

A model to analyze resemblances of twins and parents using LISREL is outlined and applied to sports participation and heart-rate data. Sports participation and heart rate were measured in 44 monozygotic and 46 dizygotic adolescent twin pairs and in their parents. Genetic factors influence variation in both sports behavior and heart rate, while there is no evidence for transmission from parental environment to offspring environment. For sports participation the data support a model in which there is a high positive correlation between environments of spouses and between environments of female twins. This correlation is absent for male twins and negative for opposite sex twins. For heart rate, a positive correlation between environmental influences was observed for all twins; there is no evidence for assortative mating. The proposed model can also handle data sets where parents and twins have been measured on more than one variable. This is illustrated by an application to the observed association of sports participation and heart rate

Diagnostic yield of CT thorax angiography in patients suspected of pulmonary embolism: independent predictors and protocol adherence

OBJECTIVES: To determine the diagnostic yield of computed tomography scanning of the pulmonary arteries (CTPA) in our centre and factors associated with it. Differences between specialties as well as adherence to protocol were investigated. METHODS: All patients receiving a first CTPA for pulmonary embolism (PE) in 2010 were included. Data about relevant clinical information and the requesting specialty were retrospectively obtained. Differences in diagnostic yield were tested using a chi-squared test. Independent predictors were identified with multivariate logistic regression. RESULTS: PE on CTPA was found in 224 of the 974 patients (23 %). Between specialties, diagnostic yield varied from 19.5 to 23.9 % (p = 0.20). Independent predictors of diagnostic yield were: age, sex, D-dimer, cough, dyspnea, cardiac history, chronic obstructive pulmonary disease (COPD), atelectasis/consolidation, intrapulmonary mass and/or interstitial pulmonary disease on CT. Wells scores were poorly documented (n = 127, 13.0 %). Poor adherence to protocol was also shown by a high amount of unnecessary D-dimer values with a high Wells-score (35 of 58; 58.6 %). CONCLUSIONS: The diagnostic yield of CTPA in this study was relatively high in comparison with other studies (6.7–31 %). Better adherence to protocol might improve the diagnostic yield further. A prospective study could confirm the independent predictors found in this study. TEACHING POINTS: • Pulmonary embolism is potentially life-threatening and requires quick and reliable diagnosis. • Computed tomography of the pulmonary arteries (CTPA) provides this reliable diagnosis. • Several independent predictors of diagnostic yield of CTPA for pulmonary embolism were identified. • Diagnostic yield of CTPA did not differ between requesting specialties in our Hospital. • Better protocol adherence could improve the diagnostic yield of CTPA for pulmonary embolism

Heritability of Stroop and flanker performance in 12-year old children

BACKGROUND: There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks. RESULTS: In the Stroop task we found high heritabilities of overall reaction time and – more important – Stroop interference (h(2 )= nearly 50 %). In contrast, we found little evidence of heritability on flanker performance. For both tasks no effects of sex on performance variation were found. CONCLUSIONS: These results suggest that normal variation in Stroop performance is influenced by underlying genetic variation. Given that Stroop performance is often hampered not only in people suffering from frontal dysfunction, but also in their unaffected relatives, we conclude that this variable may constitute a suitable endophenotype for future genetic studies. We discuss several reasons for the absence of genetic effects on the flanker task

Genetic and environmental contributions to loneliness in adults: the Netherlands Twin Register study

Heritability estimates based on two small studies in children indicate that the genetic contribution to individual differences in loneliness is approximately 50%. Heritability estimates of complex traits such as loneliness may change across the lifespan, however, as the frequency, duration, and range of exposure to environmental influences accrues, or as the expression of genetic factors changes. We examined data on loneliness from 8,387 young adult and adult Dutch twins who had participated in longitudinal survey studies. A measure of loneliness was developed based on factor analyses of items of the YASR (Achenbach, (1990) The Young Adult Self Report, University of Vermont, Department of Psychiatry, Burlington, VT). Variation in loneliness was analyzed with genetic structural equation models. The estimate of genetic contributions to variation in loneliness in adults was 48%, which is similar to the heritability estimates found previously in children. There was no evidence for sex or age differences in genetic architecture. Sex differences in prevalence were significant, but we did not see an association with age or birth cohort. All resemblance between twin relatives was explained by shared genes, without any suggestion of a contribution of shared environmental factors. ©2005 Springer Science+Business Media, Inc

The relations between DISC-IV DSM diagnoses of ADHD and multi-informant CBCL-AP syndrome scores

Background: Previous studies have examined the relation between attention problems (APs) obtained with the Child Behavior Checklist (CBCL) and attention deficit hyperactivity disorder (ADHD) assessed with the Diagnostic and Statistical Manual of Mental Disorders (DSM). We will examine this relation across sex using multi-informant data. Methods: Parents of 12 538 twins, aged 7, 10, and 12 years, and teachers of twins, aged 10 years, completed the questionnaires. The mothers of a sample of 283 boys and 291 girls who scored either low or high on longitudinal maternal CBCL-AP were interviewed. Results: Children with a low AP score obtained a negative ADHD diagnosis in 96% of cases. Children with a high AP score obtained a positive diagnosis in 36% (girls) and 59% (boys) of cases. The association between paternal and maternal AP ratings and ADHD was the same, whereas the association between teacher AP ratings and ADHD was low. Conclusions: The association between AP and ADHD is higher in boys than girls, possibly because of a bias toward the male manifestation of ADHD. © 2006 Elsevier Inc. All rights reserved

Hydrostatic models for the rotation of extra-planar gas in disk galaxies

We show that fluid stationary models are able to reproduce the observed, negative vertical gradient of the rotation velocity of the extra-planar gas in spiral galaxies. We have constructed models based on the simple condition that the pressure of the medium does not depend on density alone (baroclinic instead of barotropic solutions: isodensity and isothermal surfaces do not coincide). As an illustration, we have successfully applied our method to reproduce the observed velocity gradient of the lagging gaseous halo of NGC 891. The fluid stationary models discussed here can describe a hot homogeneous medium as well as a "gas" made of discrete, cold HI clouds with an isotropic velocity dispersion distribution. Although the method presented here generates a density and velocity field consistent with observational constraints, the stability of these configurations remains an open question.Comment: 12 pages, 9 figures. Accepted for publication in Astronomy and Astrophysic

Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study

Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose due to different metal artefacts. The O-MAR algorithm deploys an iterative loop where the metal sinogram is identified, extracted, and subsequently serves as a mask to correct the measured sinogram. Main goal of this study is to quantify the ability of the O-MAR technique to correct deviation in medullary bone attenuation caused by streak artefacts from the large-head MoM THA embedded in a phantom. Secondary goal is to evaluate the influence of O-MAR on CNR. Methods: The phantom was designed as a Perspex box (PMMA) containing water and a supplementary MOM THA surrounded by Perspex columns comprising calibrated calcium pellets. Each column contains 200 mg of hydroxyapatite/calcium carbonate to simulate healthy bone tissue. Scans were obtained with and without a MoM THA at different dose levels. Different reconstructions were made with filter A, iDose(4) level 5 and with and without O-MAR. The scans without the prosthesis were used as the baseline. Information about the attenuation in Hounsfield units, image noise in standard deviation within the ROI's were extracted and the CNR was calculated. Results: Pellet L0 and R0 (proximal of the MoM THA) were defined as reference, lacking any disturbance by metal artefacts; L5, L6 and L8 were respectively visually categorized as 'light' 'medium' and 'heavy disturbance'. Significant improvements in attenuation deviation caused by metal artefact were 43, 68 and 32 %, for respectively pellet L5, L6 and L8 (p <0.001). Significant CNR improvements were present for L5 and L6 and were respectively 72 and 52 % (p <0.001). O-MAR showed no improvement on CNR for L8. Conclusion: This phantom study significantly increases image quality by the use of O-MAR in the presence of metal artefacts by significantly reducing metal artefacts subsequently and increasing CNR on a 64 slice CT system in light and medium disturbance of the imag