Fast Bias Field Correction for 9.4 Tesla Magnetic Resonance Imaging

In this paper the problem of intensity inhomogeneity athigh magnetic field on magnetic resonance images isaddressed. Specifically, rat brain images at 9.4Tacquired with a surface coil are bias corrected. Wepropose a low- pass frequency model that takes intoaccount not only background-object contours but alsoother important contours inside the image. Twopre-processing filters are proposed: first, to create avolume of interest without contours, and second, toextrapolate the image values of such masked area to thewhole image. Results are assessed quantitatively andvisually in comparison to standard low pass filterapproach, and they show as expected better accuracy inenhancing image intensity.

Detecting, quantifying and adjusting for publication bias in meta-analyses: protocol of a systematic review on methods.

BACKGROUND: Health professionals and policymakers aspire to make healthcare decisions based on the entire relevant research evidence. This, however, can rarely be achieved because a considerable amount of research findings are not published, especially in case of 'negative' results - a phenomenon widely recognized as publication bias. Different methods of detecting, quantifying and adjusting for publication bias in meta-analyses have been described in the literature, such as graphical approaches and formal statistical tests to detect publication bias, and statistical approaches to modify effect sizes to adjust a pooled estimate when the presence of publication bias is suspected. An up-to-date systematic review of the existing methods is lacking. METHODS/DESIGN: The objectives of this systematic review are as follows:âeuro¢ To systematically review methodological articles which focus on non-publication of studies and to describe methods of detecting and/or quantifying and/or adjusting for publication bias in meta-analyses.âeuro¢ To appraise strengths and weaknesses of methods, the resources they require, and the conditions under which the method could be used, based on findings of included studies.We will systematically search Web of Science, Medline, and the Cochrane Library for methodological articles that describe at least one method of detecting and/or quantifying and/or adjusting for publication bias in meta-analyses. A dedicated data extraction form is developed and pilot-tested. Working in teams of two, we will independently extract relevant information from each eligible article. As this will be a qualitative systematic review, data reporting will involve a descriptive summary. DISCUSSION: Results are expected to be publicly available in mid 2013. This systematic review together with the results of other systematic reviews of the OPEN project (To Overcome Failure to Publish Negative Findings) will serve as a basis for the development of future policies and guidelines regarding the assessment and handling of publication bias in meta-analyses.

Directives pratiques de la Société européenne d'hypertension sur la mesure de la pression artérielle à domicile [Practice guidelines of the European Society of Hypertension for home blood pressure measurement].

Self-measurement of blood pressure at home is increasingly used in the diagnostic and therapeutic approach of hypertension. This technique allows multiple measurements of blood pressure away from the clinical setting, making it possible to improve the evaluation of cardiovascular risk. Recently new guidelines on the use of self-measured blood pressure have been made available by the European Society of Hypertension, as summarized in the present paper.

Defining publication bias: protocol for a systematic review of highly cited articles and proposal for a new framework.

BACKGROUND: Selective publication of studies, which is commonly called publication bias, is widely recognized. Over the years a new nomenclature for other types of bias related to non-publication or distortion related to the dissemination of research findings has been developed. However, several of these different biases are often still summarized by the term 'publication bias'. METHODS/DESIGN: As part of the OPEN Project (To Overcome failure to Publish nEgative fiNdings) we will conduct a systematic review with the following objectives:- To systematically review highly cited articles that focus on non-publication of studies and to present the various definitions of biases related to the dissemination of research findings contained in the articles identified.- To develop and discuss a new framework on nomenclature of various aspects of distortion in the dissemination process that leads to public availability of research findings in an international group of experts in the context of the OPEN Project.We will systematically search Web of Knowledge for highly cited articles that provide a definition of biases related to the dissemination of research findings. A specifically designed data extraction form will be developed and pilot-tested. Working in teams of two, we will independently extract relevant information from each eligible article.For the development of a new framework we will construct an initial table listing different levels and different hazards en route to making research findings public. An international group of experts will iteratively review the table and reflect on its content until no new insights emerge and consensus has been reached. DISCUSSION: Results are expected to be publicly available in mid-2013. This systematic review together with the results of other systematic reviews of the OPEN project will serve as a basis for the development of future policies and guidelines regarding the assessment and prevention of publication bias.

Need for informed consent in substance use studies--harm of bias?

OBJECTIVE: The aim of this study was to examine the differences between those who gave informed consent to a study on substance use and those who did not, and to analyze whether differences changed with varying nonconsent rates. METHOD: Cross-sectional questionnaire data on demographics, alcohol, smoking, and cannabis use were obtained for 6,099 French- and 5,720 German-speaking 20-year-old Swiss men. Enrollment took place over 11 months for the Cohort Study on Substance Use Risk Factors (C-SURF). Consenters and nonconsenters were asked to complete a short questionnaire. Data for nearly the entire population were available because 94% responded. Weekly differences in consent rates were analyzed. Regressions examined the associations of substance use with consent giving and consent rates and the interaction between the two. RESULTS: Nonconsenters had higher substance use patterns, although they were more often alcohol abstainers; differences were small and not always significant and did not decrease as consent rates increased. CONCLUSIONS: Substance use currently is a minor sensitive topic among young men, resulting in small differences between nonconsenters and consenters. As consent rates increase, additional individuals are similar to those observed at lower consent rates. Estimates of analytical studies looking at associations of substance use with other variables will not differ at reasonable consent rates of 50%-80%. Descriptive prevalence studies may be biased, but only at very low rates of consent.

Correcting for the bias due to expression specificity improves the estimation of constrained evolution of expression between mouse and human.

MOTIVATION: Comparative analyses of gene expression data from different species have become an important component of the study of molecular evolution. Thus methods are needed to estimate evolutionary distances between expression profiles, as well as a neutral reference to estimate selective pressure. Divergence between expression profiles of homologous genes is often calculated with Pearson's or Euclidean distance. Neutral divergence is usually inferred from randomized data. Despite being widely used, neither of these two steps has been well studied. Here, we analyze these methods formally and on real data, highlight their limitations and propose improvements. RESULTS: It has been demonstrated that Pearson's distance, in contrast to Euclidean distance, leads to underestimation of the expression similarity between homologous genes with a conserved uniform pattern of expression. Here, we first extend this study to genes with conserved, but specific pattern of expression. Surprisingly, we find that both Pearson's and Euclidean distances used as a measure of expression similarity between genes depend on the expression specificity of those genes. We also show that the Euclidean distance depends strongly on data normalization. Next, we show that the randomization procedure that is widely used to estimate the rate of neutral evolution is biased when broadly expressed genes are abundant in the data. To overcome this problem, we propose a novel randomization procedure that is unbiased with respect to expression profiles present in the datasets. Applying our method to the mouse and human gene expression data suggests significant gene expression conservation between these species. CONTACT: marc.robinson-rechavi@unil.ch; sven.bergmann@unil.ch SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Increasing prehospital emergency medical service interventions for nursing home residents.

QUESTION: In the ageing European population, the proportion of interventions by the emergency medical services (EMS) for elderly patients is increasing, but little is known about the recent trend of EMS interventions in nursing homes. The aim of this analysis was to describe the evolution of the incidence of requests for prehospital EMS interventions for nursing home residents aged 65 years and over between 2004 and 2013. METHODS: A prospective population-based register of routinely collected data for each EMS intervention in the Canton of Vaud. Linear time trends of incidence of requests to the EMS in nursing homes were calculated and stratified by age categories. RESULTS: The number of ambulance interventions in nursing homes for people aged 65 years and over (65+) increased by 68.9% (1124‒1898) between 2004 and 2013. A significant linear increase of the annual incidence of requests to EMS per 1,000 nursing home residents was found for people aged 65-79 (10.2, 95% confidence interval [CI] 6.2-14.2), 80-89 (16.5, 95% CI 14.0-19.0) and over 90 (12.1, 95% CI 5.8-18.4). EMS interventions in nursing home residents who required an emergency physician increased during the same period by 205.6% (from 106 to 324), representing an increase from 2% to 7% of all emergency physician interventions in the Canton. CONCLUSIONS: Our results confirmed an important increase in the incidence of EMS interventions in nursing homes during the last decade, far exceeding the actual increase of the nursing home population during the same period. This evolution represents an important opportunity to reconsider the EMS missions in the context of an ageing society.

Extension des prestations de type "équipe mobile" aux foyers socio-éducatifs: projet pilote dans le canton de Vaud [Extension of mobile team services to socio-educational home: pilot project in the Vaud canton].

L'objectif principal de ce projet d'extension des prestations, de type Antenne d'intervention dans le milieu pour enfants et adolescents (AIMEA) aux foyers socio-éducatifs pour l'ensemble du canton de Vaud, vise à décloisonner les champs socio-éducatifs et pédopsychiatriques. 64 patients ont fait l'objet d'une évaluation au cours de la phase pilote (après une année de fonctionnement). De plus, une enquête de satisfaction a été effectuée soit à la fin du suivi, soit à la fin de la phase pilote de ce projet (au 31.12.2012). Cette expérience très positive, relevée par une grande majorité des acteurs impliqués dans la prise en charge socio-éducative et pédopsychiatrique des mineurs, suscite un désir d'extension des prestations de type équipe mobile à d'autres structures ou à d'autres types de situations. The main objective of this project about mobile team service extension to the socio-educational home of the whole Vaud canton targets to decompartmentalize the socio-educational and youth-psychiatry domains. 64 patient were assessed during this pilot phase (after one-year functioning). In addition, a satisfaction survey was done either at the end of the follow up or at the end of the pilot phase of the project (31.12.2012). This experience was very positive as highlighted by the vast majority of the person involved in the socio-educational and youth-psychiatric domains taking care of youth. A desire of extension of mobile team service to other institutional structure or other situations was expressed.

[Place of volunteers in home care setting for taking care of individuals with Alzheimer's disease related dementia: Qualitative survey in a specialized unit] Place du bénévolat en EHPAD dans la prise en charge des personnes atteintes de la maladie d'Alzheimer ou démences apparentées : enquête qualitative dans une unité protégée.

Objectifs En EHPAD, selon les recommandations de la Haute Autorité de santé (HAS), la prise en charge non médicamenteuse des troubles psychocomportementaux associés à la maladie d'Alzheimer ou aux syndromes apparentés, implique une réorganisation, une formation spécifique du personnel et du temps. Se pose ici la question du rôle des bénévoles dans cette prise en charge. Matériels et méthodes Enquête descriptive à partir de questionnaires distribués aux différents intervenants (bénévoles, professionnels de santé et aidants familiaux) d'une unité protégée de l'EHPAD de la clinique du Diaconat (Colmar, France) et spécifiquement élaborés pour évaluer leur vécu de l'expérience de bénévolat dans la prise en charge des résidents souffrant d'une maladie d'Alzheimer ou d'un syndrome apparenté. Résultats Sur les 101 questionnaires qui ont été remplis, 85,7 % des aidants, 60 % des bénévoles et 42,1 % des professionnels constataient des bénéfices pour eux-mêmes. Les professionnels et les aidants avaient confiance dans l'intervention des bénévoles. Cependant, les bénévoles semblaient manquer de compétence pour le soutien des aidants et dans les techniques de communication avec les résidents. Les points essentiels pour permettre un fonctionnement harmonieux entre les différents intervenants étaient de bien définir préalablement le rôle de bénévoles et d'en informer les autres intervenants, de former les bénévoles à ce rôle et de favoriser la communication entre les bénévoles et les professionnels. Conclusion Cette enquête montre que les bénévoles ont une place aux côtés des équipes soignantes pour participer à la prise en charge non médicamenteuse des personnes atteintes de maladie d'Alzheimer ou syndromes apparentés. Ils ont une position singulière et jouent un rôle complémentaire de celui des soignants et des aidants. Objectives According to the recommendation of the French High Authority of Health (HAS), the non-pharmaceutical management of psycho-behavioural disorders associated with Alzheimer's disease or related disorders in a nursing home, involves reorganization an specific training for staff members and time. This raises the question of the role of volunteering in this approach. Materials and methods A descriptive survey using questionnaires distributed to various stakeholders (volunteers, healthcare professionals and caregivers) of a protected unit of the nursing home of the Diaconat clinic (Colmar, France) and specifically designed to assess their experience of the volunteering in supporting residents suffering from Alzheimer's diseases or related disorders. Results Of the 101 questionnaires that were filled in, 85.7% of caregivers, 60% of volunteers and 42.1% of professionals recorded benefits for themselves. Professionals and informal carers had confidence in the intervention of volunteers. However, volunteers seemed to lack skills to support informal caregivers and specific knowledge about the technique of communicating with residents. The key points to favor harmonious collaborations between the different stakeholders were: to properly define the role of volunteers and to inform other stakeholders about this role previously, and to specifically educate themselves in this task and to promote communication between volunteers and all other professionals. Conclusion This study shows that volunteers have a place alongside medical teams to participate in the non-pharmaceutical treatment for people with Alzheimer's disease or related syndromes. They have a unique position and play a complementary role to that of carers and informal caregivers.

Effect Estimation of an Innovative Nursing Intervention to Improve Delirium among Home-Dwelling Older Adults: A Randomized Controlled Pilot Trial.

AIMS: Estimating the effect of a nursing intervention in home-dwelling older adults on the occurrence and course of delirium and concomitant cognitive and functional impairment. METHODS: A randomized clinical pilot trial using a before/after design was conducted with older patients discharged from hospital who had a medical prescription to receive home care. A total of 51 patients were randomized into the experimental group (EG) and 52 patients into the control group (CG). Besides usual home care, nursing interventions were offered by a geriatric nurse specialist to the EG at 48 h, 72 h, 7 days, 14 days, and 21 days after discharge. All patients were monitored for symptoms of delirium using the Confusion Assessment Method. Cognitive and functional statuses were measured with the Mini-Mental State Examination and the Katz and Lawton Index. RESULTS: No statistical differences with regard to symptoms of delirium (p = 0.085), cognitive impairment (p = 0.151), and functional status (p = 0.235) were found between the EG and CG at study entry and at 1 month. After adjustment, statistical differences were found in favor of the EG for symptoms of delirium (p = 0.046), cognitive impairment (p = 0.015), and functional status (p = 0.033). CONCLUSION: Nursing interventions to detect delirium at home are feasible and accepted. The nursing interventions produced a promising effect to improve delirium.

Mapping Bias Overestimates Reference Allele Frequencies at the HLA Genes in the 1000 Genomes Project Phase I Data.

Next-generation sequencing (NGS) technologies have become the standard for data generation in studies of population genomics, as the 1000 Genomes Project (1000G). However, these techniques are known to be problematic when applied to highly polymorphic genomic regions, such as the human leukocyte antigen (HLA) genes. Because accurate genotype calls and allele frequency estimations are crucial to population genomics analyses, it is important to assess the reliability of NGS data. Here, we evaluate the reliability of genotype calls and allele frequency estimates of the single-nucleotide polymorphisms (SNPs) reported by 1000G (phase I) at five HLA genes (HLA-A, -B, -C, -DRB1, and -DQB1). We take advantage of the availability of HLA Sanger sequencing of 930 of the 1092 1000G samples and use this as a gold standard to benchmark the 1000G data. We document that 18.6% of SNP genotype calls in HLA genes are incorrect and that allele frequencies are estimated with an error greater than ±0.1 at approximately 25% of the SNPs in HLA genes. We found a bias toward overestimation of reference allele frequency for the 1000G data, indicating mapping bias is an important cause of error in frequency estimation in this dataset. We provide a list of sites that have poor allele frequency estimates and discuss the outcomes of including those sites in different kinds of analyses. Because the HLA region is the most polymorphic in the human genome, our results provide insights into the challenges of using of NGS data at other genomic regions of high diversity.

Sex differences in brain plasticity: a new hypothesis for sex ratio bias in autism.

Several observations support the hypothesis that differences in synaptic and regional cerebral plasticity between the sexes account for the high ratio of males to females in autism. First, males are more susceptible than females to perturbations in genes involved in synaptic plasticity. Second, sex-related differences in non-autistic brain structure and function are observed in highly variable regions, namely, the heteromodal associative cortices, and overlap with structural particularities and enhanced activity of perceptual associative regions in autistic individuals. Finally, functional cortical reallocations following brain lesions in non-autistic adults (for example, traumatic brain injury, multiple sclerosis) are sex-dependent. Interactions between genetic sex and hormones may therefore result in higher synaptic and consecutively regional plasticity in perceptual brain areas in males than in females. The onset of autism may largely involve mutations altering synaptic plasticity that create a plastic reaction affecting the most variable and sexually dimorphic brain regions. The sex ratio bias in autism may arise because males have a lower threshold than females for the development of this plastic reaction following a genetic or environmental event.