From discrete to continuum models of three-dimensional deformations in epithelial sheets

International audienceEpithelial tissue, in which cells adhere tightly to each other and to theunderlying substrate, is one of the four major tissue types in adultorganisms. In embryos, epithelial sheets serve as versatile substratesduring the formation of developing organs. Some aspects of epithelialmorphogenesis can be adequately described using vertex models, in which thetwo-dimensional arrangement of epithelial cells is approximated by apolygonal lattice with an energy that has contributions reflecting theproperties of individual cells and their interactions. Previous studieswith such models have largely focused on dynamics confined to two spatialdimensions and analyzed them numerically. We show how these models can beextended to account for three-dimensional deformations and studiedanalytically. Starting from the extended model, we derive a continuumplate description of cell sheets, in which the effective tissue properties,such as bending rigidity, are related explicitly to the parameters of thevertex model. To derive the continuum plate model, we duly take intoaccount a microscopic shift between the two sublattices of the hexagonalnetwork, which has been ignored in previous work. As an application of thecontinuum model, we analyze tissue buckling by a line tension applied alonga circular contour, a simplified set-up relevant to several situations inthe developmental context. The buckling thresholds predicted by thecontinuum description are in good agreement with the results of directstability calculations based on the vertex model. Our results establish adirect connection between discrete and continuum descriptions of cellsheets and can be used to probe a wide range of morphogenetic processes inepithelial tissues

Bias in dissemination of clinical research findings: Structured OPEN framework of what, who and why, based on literature review and expert consensus

Objective: The aim of this study is to review highly cited articles that focus on non-publication of studies, and to develop a consistent and comprehensive approach to defining (non-) dissemination of research findings. Setting: We performed a scoping review of definitions of the term 'publication bias' in highly cited publications. Participants: Ideas and experiences of a core group of authors were collected in a draft document, which was complemented by the findings from our literature search. Interventions: The draft document including findings from the literature search was circulated to an international group of experts and revised until no additional ideas emerged and consensus was reached. Primary outcomes: We propose a new approach to the comprehensive conceptualisation of (non-) dissemination of research. Secondary outcomes: Our 'What, Who and Why?' approach includes issues that need to be considered when disseminating research findings (What?), the different players who should assume responsibility during the various stages of conducting a clinical trial and disseminating clinical trial documents (Who?), and motivations that might lead the various players to disseminate findings selectively, thereby introducing bias in the dissemination process (Why?). Conclusions: Our comprehensive framework of (non-) dissemination of research findings, based on the results of a scoping literature search and expert consensus will facilitate the development of future policies and guidelines regarding the multifaceted issue of selective publication, historically referred to as 'publication bias'

Overweight and obesity in 16 European countries

Purpose: In Europe, only a few population-based studies have been conducted on obesity in different countries at the same time using homogeneous methodologies. We provide updated information on\ua0the prevalence of overweight and obesity in Europe, using data from a pan-European survey. Methods: We considered data from a representative cross-sectional study conducted in 2010 in 16 European countries (i.e., Albania, Austria, Bulgaria, Czech Republic, Croatia, England, Finland, France, Hungary, Ireland, Italy, Latvia, Poland, Romania, Spain, and Sweden), using a uniform protocol and comparable methods, on a total of 14,685 adults (aged 6518\ua0years) providing information on self-reported height and weight. Results: Almost half of the interviewed European adults\ua0(47.6 %) were overweight or obese (54.5\ua0% in men and 40.8\ua0% in women), and 12.8\ua0% (14.0\ua0% in men and 11.5\ua0% in women) were obese. Obesity prevalence was lower in Western/Southern (11.1\ua0%) than in Central/Eastern (12.4\ua0%) and Northern European countries (18.0\ua0%). It ranged from 7.6\ua0% in Italy to more than 20\ua0% in Croatia (21.5\ua0%) and England (20.1\ua0%). Prevalence of obesity significantly increased with age and decreased with level of education. As compared to never smokers, obesity was less frequent in current smokers and more frequent in male, but not female, ex-smokers. Conclusions: The lowest prevalence of obesity was observed in Mediterranean countries, particularly in Italy and France. Intervention to control obesity in Europe should focus on subgroups with higher prevalence of obesity, including adults\ua0of lower socioeconomic status and male ex-smokers

Patterns of Smoking Prevalence among the Elderly in Europe

Scant information is available on determinants of smoking prevalence in the vulnerable population of the elderly, particularly in Europe. Therefore, we analyzed smoking patterns among older adults ( 6565 years old), using data from a representative survey based on 3,071 elderly, conducted in 17 European countries in 2010, within the Pricing Policies And Control of Tobacco in Europe (PPACTE) project. Overall smoking prevalence in 17 European countries was 11.5% (15.3% in men and 8.6% in women). An inverse relation with level of education was observed among men, while no specific pattern was evident among women. Smoking prevalence was highest in eastern/central Europe for men (20.3%) and northern Europe for women (13.1%). In both sexes combined, smokers were more frequent in countries with low implementation of tobacco control activities (14.9%). Anti-tobacco campaigns and smoking cessation interventions specifically targeted to the elderly are urgently needed in Europe