The use of fixed effect models and mixed models to estimate single gene associated effects on polygenic traits

International audienc

Computer tomographic investigation of subcutaneous adipose tissue as an indicator of body composition

<p>Abstract</p> <p>Background</p> <p>Modern computer tomography (CT) equipment can be used to acquire whole-body data from large animals such as pigs in minutes or less. In some circumstances, computer assisted analysis of the resulting image data can identify and measure anatomical features. The thickness of subcutaneous adipose tissue at a specific site measured by ultrasound, is used in the pig industry to assess adiposity and inform management decisions that have an impact on reproduction, food conversion performance and sow longevity. The measurement site, called "P2", is used throughout the industry. We propose that CT can be used to measure subcutaneous adipose tissue thickness and identify novel measurement sites that can be used as predictors of general adiposity.</p> <p>Methods</p> <p>Growing pigs (<it>N </it>= 12), were each CT scanned on three occasions. From these data the total volume of adipose tissue was determined and expressed as a proportion of total volume (fat-index). A computer algorithm was used to determined 10,201 subcutaneous adipose thickness measurements in each pig for each scan. From these data, sites were selected where correlation with fat-index was optimal.</p> <p>Results</p> <p>Image analysis correctly identified the limits of the relevant tissues and automated measurements were successfully generated. Two sites on the animal were identified where there was optimal correlation with fat-index. The first of these was located 4 intercostal spaces cranial to the caudal extremity of the last rib, the other, a further 5 intercostal spaces cranially.</p> <p>Conclusion</p> <p>The approach to image analysis reported permits the creation of various maps showing adipose thickness or correlation of thickness with other variables by location on the surface of the pig. The method identified novel adipose thickness measurement positions that are superior (as predictors of adiposity) to the site which is in current use. A similar approach could be used in other situations to quantify potential links between subcutaneous adiposity and disease or production traits.</p

Maternal, dominance and additive genetic effects in Nile tilapia; influence on growth, fillet yield and body size traits

There are only few studies of dominance effects in non-inbred aquaculture species, since commonly used mating designs often have low power to separate dominance, maternal and common environmental effects. Here, a factorial design with reciprocal cross, common rearing of eggs and subsequent lifecycle stages and pedigree assignment using DNA microsatellites was used to separate these effects and estimate dominance (d2) and maternal (m2) ratios in Nile tilapia for six commercial traits. The study included observations on 2524 offspring from 155 full-sib families. Substantial contributions of dominance were observed (P < 0.05) for body depth (BD) and body weight at harvest (BWH) with estimates of d2 = 0.27 (s.e. 0.09) and 0.23 (s.e. 0.09), respectively in the current breeding population. In addition the study found maternal variance (P < 0.05) for BD, BWH, body thickness and fillet weight explaining ~10% of the observed phenotypic variance. For fillet yield (FY) and body length (BL), no evidence was found for either maternal or dominance variance. For traits exhibiting maternal variance, including this effect in evaluations caused substantial re-ranking of selection candidates, but the impact of including dominance effects was notably less. Breeding schemes may benefit from utilising maternal variance in increasing accuracy of evaluations, reducing bias, and developing new lines, but the utilisation of the dominance variance may require further refinement of parameter estimates.publishedVersio

Effects of a COPD self-management support intervention: a randomized controlled trial

Heidi B Bringsvor,1,2 Eva Langeland,3 Bj&oslash;rg Fr&oslash;ysland Oftedal,2 Knut Skaug,1 J&ouml;rg Assmus,4 Signe Berit Bentsen5 1Department of Research and Innovation, Helse Fonna HF, Haugesund, Norway; 2Department of Quality and Health Technology, Faculty of Health Sciences, University of Stavanger, Stavanger, Norway; 3Department of Health and Caring Sciences, Western Norway University of Applied Sciences, Bergen, Norway; 4Center for Clinical Research, Department of Reserach and Innovation, Haukeland University Hospital, Bergen, Norway; 5SHARE-Centre for Resilience in Health Care, Department of Quality and Health Technology, Faculty of Health Sciences, University of Stavanger, Stavanger, Norway Background: This study examines the effects of the COPD-specific health promoting self-management intervention &ldquo;Better living with COPD&rdquo; on different self-management-related domains, self-efficacy, and sense of coherence (SOC). Methods: In a randomized controlled design, 182 people with COPD were allocated to either an intervention group (offered Better living with COPD in addition to usual care) or a control group (usual care). Self-management-related domains were measured by the Health Education Impact Questionnaire (heiQ) before and after intervention. Self-efficacy was measured by the General Self-Efficacy Scale (GSE) and SOC was measured by the 13-item Sense of Coherence Scale (SOC-13). Effects were assessed by ANCOVA, using intention-to-treat (ITT) analysis and per-protocol analysis (PPA). Results: The PPA and the ITT analysis showed significant positive changes on Constructive attitudes and approaches (heiQ) (ITT: P=0.0069; PPA:&nbsp;P=0.0021) and Skill and technique acquisition (heiQ) (ITT:&nbsp;P=0.0405; PPA:&nbsp;P=0.0356). Self-monitoring and insight (heiQ) showed significant positive change in the PPA (P=0.0494). No significant changes were found on the other self-management domains (heiQ), self-efficacy (GSE), or SOC (SOC-13). Conclusion: Better living with COPD had a significant positive short-term effect on some self-management-related domains, and could be an intervention contributing to the support of self-management in people with COPD. However, further work is needed to establish the clinical relevance of the findings and to evaluate the long-term effects. Keywords: constructive attitudes and approaches, Health Education Impact Questionnaire (heiQ), self-efficacy, self-monitoring and insight, sense of coherence, skill and technique acquisitio

Symptom burden and self-management in persons with chronic obstructive pulmonary disease

Heidi B Bringsvor,1,2 Knut Skaug,1 Eva Langeland,3 Bj&oslash;rg Fr&oslash;ysland Oftedal,2 J&ouml;rg Assmus,4 Doris Gundersen,1 Richard H Osborne,5 Signe Berit Bentsen2 1Department of Research and Innovation, Helse Fonna HF, Haugesund, 2Department of Quality and Health Technology, University of Stavanger, Stavanger, 3Department of Nursing, Western Norway University of Applied Sciences, 4Center for Clinical Research, Haukeland University Hospital, Bergen, Norway; 5Health Systems Improvement Unit, School of Health and Social Development, Centre For Population Health Research, Deakin University, Burwood, Victoria, Australia Purpose: Self-management is crucial for effective COPD management. This study aimed at identifying associations between self-management and sociodemographic characteristics, clinical characteristics, and symptom burden in people with COPD. Patients and methods: In this cross-sectional study with 225 participants diagnosed with COPD grades II&ndash;IV, multiple linear regression analysis was conducted, using sociodemographic and clinical characteristics and symptom burden (COPD Assessment Test) as the independent variables and the eight self-management domains of the Health Education Impact Questionnaire (heiQ) as the outcome variables. Results: Higher symptom burden was significantly associated with worse scores in all self-management domains (p&lt;0.003), except for self-monitoring and insight (p=0.012). Higher disease severity (p=0.004) and numbers of comorbidities (p&lt;0.001) were associated with more emotional distress, and women scored higher than men on positive and active engagement in life (p=0.001). Higher score in pack-years smoking was associated with lower score in health-directed activities (p=0.006) and self-monitoring and insight (p&lt;0.001), and participation in organized physical training was associated with higher score in health-directed activities (p&lt;0.001). The final models explained 3.7%&ndash;31.7% of variance (adjusted R2) across the eight heiQ scales. Conclusion: A notable finding of this study was that higher symptom burden was associated with worse scores in all self-management domains, except for self-monitoring and insight. In addition, sex, disease severity, comorbidity, pack-years smoking, and participation in organized physical training were associated with one or two self-management domains. The study contributes to improved understanding of self-management in COPD. However, the explained variance levels indicate that more research needs to be done to uncover what else explains self-management domains in COPD. Keywords: COPD, Health Education Impact Questionnaire, COPD Assessment Test, self-management, symptoms, chronic diseas