9,565 research outputs found

    Approximate restricted maximum likelihood and approximate prediction error variance of the Mendelian sampling effect

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    In an Expectation-Maximization type Restricted Maximum Likelihood (REML) procedure, the estimation of a genetic (co-)variance component involves the trace of the product of the inverse of the coefficient matrix by the inverse of the relationship matrix. Computation of this trace is usually the limiting factor of this procedure. In this paper, a method is presented to approximate this trace in the case of an animal model, by using an equivalent model based on the Mendelian sampling effect and by simplifying its coefficient matrix and its inversion. This approximation appeared very accurate for low heritabilities but was downwards biased when the heritability was high. Implemented in a REML procedure, this approximation reduced dramatically the amount of computation, but provided downwards biased estimates of genetic variances. Several examples are presented to illustrate the method.Dans certaines procédures de Maximum de Vraisemblance Restreint (REML), l’estimation des composantes de (co)variance génétique implique le calcul de la trace du produit de l’inverse de la matrice des coefficients par l’inverse de la matrice de parentés, calcul qui constitue généralement le facteur limitant de ce type de procédure. Nous présentons dans cet article une méthode visant à obtenir une valeur approchée de cette trace dans le cadre d’un modèle animal, en utilisant un modèle équivalent basé sur l’aléa de méiose, en simplifiant sa matrice des coefficients et en en calculant une inverse approchée. Cette approximation est très précise lorsque l’héritabilité du caractère est faible mais elle tend à sous-estimer la trace vraie lorsque l’héritabilité est élevée. Intégrée dans une procédure de REML, cette méthode en réduit considérablement le coût mais fournit en général des valeurs sous-estimées de variance génétique. Divers exemples sont présentés à titre d'illustratio

    Adalimumab in refractory cystoid macular edema associated with birdshot chorioretinopathy

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    Purpose To report the clinical outcomes of adalimumab therapy in cases of birdshot chorioretinitis (BCR) with cystoid macular edema (CME) refractory to conventional immunotherapy. Methods This is a retrospective case series of three BCR patients treated with adalimumab for refractory CME. The main outcome measure was central subfield thickness (CST) on optical coherence tomography. Any patients treated with local steroids and/or receiving systemic steroids higher than 40 mg prednisolone daily during adalimumab therapy were excluded. Results At baseline, all patients were receiving systemic corticosteroids and two second-line immunosuppressive agents. The mean duration of treatment with adalimumab was 31.2 months (range 17.2–52). The mean CST was 327 ± 112.7 μm (mean ± SD) at baseline and 256.2 ± 39.7 μm at 6 months and 235.5 ± 32.5 μm at 12 months. Adalimumab permitted cessation or reduction in the daily dose of oral prednisolone plus withdrawal of a second-line agent in all patients. Conclusions In these patients, adalimumab was effective in the treatment of refractory CME

    A modeling investigation of canopy-air oxygen isotopic exchange of water vapor and carbon dioxide in a soybean field

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    The oxygen isotopes of CO2 and H2O ( 18O-CO2 and 18O-H2O) provide unique information regarding the contribution of terrestrial vegetation to the global CO2 and H2O cycles. In this paper, a simple isotopic land surface model was used to investigate processes controlling the isotopic exchange of 18O-H2O and 18O-CO2 between a soybean ecosystem and the atmosphere. We included in a standard land surface model a nonsteady state theory of leaf water isotopic composition, a canopy kinetic fractionation factor, and a big-leaf parameterization of the 18O-CO2 isoforcing on the atmosphere. Our model simulations showed that the Pclet effect was less important than the nonsteady state effect on the temporal dynamics of the water isotopic exchange. The model reproduced the highly significant and negative correlation between relative humidity and the ecosystem-scale 18O-CO2 isoforcing measured with eddy covariance. But the model-predicted isoforcing was biased high in comparison to the observations. Model sensitivity analysis suggested that the CO2 hydration efficiency must have been much lower in the leaves of soybean in field conditions than previously reported. Understanding environmental controls on the hydration efficiency and the scaling from the leaf to the canopy represents an area in need of more research. Copyright 2010 by the American Geophysical Union

    Depressed Adolescents’ Pupillary Response to Peer Acceptance and Rejection: The Role of Rumination

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    Heightened emotional reactivity to peer feedback is predictive of adolescents’ depression risk. Examining variation in emotional reactivity within currently depressed adolescents may identify subgroups that struggle the most with these daily interactions. We tested whether trait rumination, which amplifies emotional reactions, explained variance in depressed adolescents’ physiological reactivity to peer feedback, hypothesizing that rumination would be associated with greater pupillary response to peer rejection and diminished response to peer acceptance. Twenty currently depressed adolescents (12–17) completed a virtual peer interaction paradigm where they received fictitious rejection and acceptance feedback. Pupillary response provided a time-sensitive index of physiological arousal. Rumination was associated with greater initial pupil dilation to both peer rejection and acceptance, and diminished late pupillary response to peer acceptance trials only. Results indicate that depressed adolescents high on trait rumination are more reactive to social feedback regardless of valence, but fail to sustain cognitive-affective load on positive feedback

    Clinical guidelines for the management of craniofacial fibrous dysplasia

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    Fibrous dysplasia (FD) is a non-malignant condition caused by post-zygotic, activating mutations of the GNAS gene that results in inhibition of the differentiation and proliferation of bone-forming stromal cells and leads to the replacement of normal bone and marrow by fibrous tissue and woven bone. The phenotype is variable and may be isolated to a single skeletal site or multiple sites and sometimes is associated with extraskeletal manifestations in the skin and/or endocrine organs (McCune-Albright syndrome). The clinical behavior and progression of FD may also vary, thereby making the management of this condition difficult with few established clinical guidelines. This paper provides a clinically-focused comprehensive description of craniofacial FD, its natural progression, the components of the diagnostic evaluation and the multi-disciplinary management, and considerations for future research

    Implications of sperm banking for health-related quality of life up to 1 year after cancer diagnosis.

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    Sperm banking is recommended for all men diagnosed with cancer where treatment is associated with risk of long-term gonadatoxicity, to offer the opportunity of fatherhood and improved quality of life. However, uptake of sperm banking is lower than expected and little is known about why men refuse. Our aims were to determine: (i) demographic and medical variables associated with decisions about banking and (ii) differences in quality of life between bankers and non-bankers at diagnosis (Time 1 (T1)) and 1 year later (Time 2 (T2))

    Community-based randomised controlled trial evaluating falls and osteoporosis risk management strategies

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    <p>Abstract</p> <p>Background</p> <p>Osteoporosis-related fractures are a significant public health concern. Interventions that increase detection and treatment of osteoporosis, as well as prevention of fractures and falls, are substantially underutilized. This paper outlines the protocol for a pragmatic randomised trial of a multifaceted community-based care program aimed at optimizing the evidence-based management of falls and fractures in patients at risk.</p> <p>Design</p> <p>6-month randomised controlled study.</p> <p>Methods</p> <p>This population-based study was completed in the Algoma District of Ontario, Canada a geographically vast area with Sault Ste Marie (population 78 000) as its main city. Eligible patients were allocated to an immediate intervention protocol (IP) group, or a delayed intervention protocol (DP) group. The DP group received usual care for 6 months and then was crossed over to receive the interventions. Components of the intervention were directed at the physicians and their patients and included patient-specific recommendations for osteoporosis therapy as outlined by the clinical practice guidelines developed by Osteoporosis Canada, and falls risk assessment and treatment. Two primary outcomes were measured including implementation of appropriate osteoporosis and falls risk management. Secondary outcomes included quality of life and the number of falls, fractures, and hospital admissions over a twelve-month period. The patient is the unit of allocation and analysis. Analyses will be performed on an intention to treat basis.</p> <p>Discussion</p> <p>This paper outlines the protocol for a pragmatic randomised trial of a multi-faceted, community-based intervention to optimize the implementation of evidence based management for patients at risk for falls and osteoporosis.</p> <p>Trial Registration</p> <p>This trial has been registered with clinicaltrials.gov (ID: NCT00465387)</p
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