Adaptation in a heterogeneous environment II: To be three or not to be

We propose a model to describe the adaptation of a phenotypically structured population in a $H$-patch environment connected by migration, with each patch associated with a different phenotypic optimum, and we perform a rigorous mathematical analysis of this model. We show that the large-time behaviour of the solution (persistence or extinction) depends on the sign of a principal eigenvalue, $\lambda_H$, and we study the dependency of $\lambda_H$ with respect to $H$. This analysis sheds new light on the effect of increasing the number of patches on the persistence of a population, which has implications in agroecology and for understanding zoonoses; in such cases we consider a pathogenic population and the patches correspond to different host species. The occurrence of a springboard effect, where the addition of a patch contributes to persistence, or on the contrary the emergence of a detrimental effect by increasing the number of patches on the persistence, depends in a rather complex way on the respective positions in the phenotypic space of the optimal phenotypes associated with each patch. From a mathematical point of view, an important part of the difficulty in dealing with $H\ge 3$, compared to $H=1$ or $H=2$, comes from the lack of symmetry. Our results, which are based on a fixed point theorem, comparison principles, integral estimates, variational arguments, rearrangement techniques, and numerical simulations, provide a better understanding of these dependencies. In particular, we propose a precise characterisation of the situations where the addition of a third patch increases or decreases the chances of persistence, compared to a situation with only two patches

Does one size fit all? An update on chronic ventilatory support in different respiratory illnesses

Home noninvasive ventilation (HNIV) improves outcomes in different disease categories. In this article, we discuss indications for when and how to initiate HNIV in COPD, obesity hypoventilation syndrome (OHS) and neuromuscular disorders (NMD). While in COPD, significant diurnal hypercapnia and high-intensity HNIV are essential ingredients for success, in NMD and OHS, early respiratory changes are best detected during sleep through oxy-capnography associated (or not) with respiratory polygraphy. In COPD and OHS, it is crucial to consider the coexistence of obstructive sleep apnoea because treatment with continuous positive airway pressure may be the simplest and most effective treatment that should be proposed even in hypercapnic patients as first-line therapy. In NMD, the need for continuous HNIV and eventual switching to tracheostomy ventilation makes this group’s management more challenging. Achieving successful HNIV by improving quality of sleep, quality of life and keeping a good adherence to the therapy is a challenge, above all in COPD patients. In OHS patients, on top of HNIV, initiation of other interventions such as weight loss management is crucial. More resources should be invested in improving all these aspects. Telemonitoring represents a promising method to improve titration and follow-up of HNIV

Organic livestock farming systems in the Massif Central: evolution (2008-2011) and analysis of the technical and economic performances and drivers

The “Organic Farming Massif Central” hub and fifteen partners lead a program on sustainability and on the technical and economic operation of OF livestock systems in the Massif Central. This systemic and multi-year study (2008-2011) is based on data from a constant sample over four years, from 56 farms comprising four types of products: cattle and sheep, dairy and meat. Over 4 years, the technical and economic results are quite stable, and at a good level, but with great variability inter-farms. With lower labor productivity, but with a more diversified crop rotation, a good food self-sufficiency and good technical skills, the farms with the highest income get an income more than four times higher than the farms with the lowest income

Bilan de la productivité des petits ruminants dans la région de Kaolack de juillet 95 juin 97 et restitution auprès des éleveurs

Menée dans le cadre des activités du Projet de Développement des Espèces à Cycles Courts (PRODEC), cette mission a pour but de fournir une aide à la décision dans le choix de programmes d'amélioration de la productivité animale dans la région de Kaolack (Sénégal). La collecte et l'analyse des données relatives aux troupeaux (taille et structure des troupeaux, paramètres de reproduction, mortalité et taux d'exploitation) montrent que les élevages de l'Agropov ne sont pas semi-intensifs. Les performances zootechniques sont similaires à celles du projet villageois. La différence entre ces deux systèmes ne tient qu'à la production arachidière, à la taille des effectifs des troupeaux et à la spéculation sur les brebis Tabaski. L'intensificatio n de la conduite des troupeaux nécessite une meilleure maîtrise de l'alimentation, le contrôle et la synchronisation des chaleurs et enfin, la conception d'un plan sanitaire d'élevage. L'Agropov peut être le point de départ de l'organisation de la filière ovine au Sénégal. La commission de commercialisation doit trouver des débouchés pour la vente des animaux de boucherie alors que le vétérinaire doit conforter la production en assurant un suivi zootechnique et sanitaire régulie

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia:a systematic review and individual participant data meta-analysis

BACKGROUND: The optimal interface for the delivery of home non-invasive ventilation (NIV) to treat chronic respiratory failure has not yet been determined. The aim of this individual participant data (IPD) meta-analysis was to compare the effect of nasal and oronasal masks on treatment efficacy and adherence in patients with COPD and obesity hypoventilation syndrome (OHS). METHODS: We searched Medline and Cochrane Central Register of Controlled Trials for prospective randomised controlled trials (RCTs) of at least 1 month's duration, published between January 1994 and April 2019, that assessed NIV efficacy in patients with OHS and COPD. The main outcomes were diurnal PaCO2, PaO2 and NIV adherence (PROSPERO CRD42019132398). FINDINGS: Of 1576 articles identified, 34 RCTs met the inclusion criteria and IPD were obtained for 18. Ten RCTs were excluded because only one type of mask was used, or mask data were missing. Data from 8 RCTs, including 290 IPD, underwent meta-analysis. Oronasal masks were used in 86% of cases. There were no differences between oronasal and nasal masks for PaCO2 (0.61 mm Hg (95% CI -2.15 to 3.38); p=0.68), PaO2 (-0.00 mm Hg (95% CI -4.59 to 4.58); p=1) or NIV adherence (0·29 hour/day (95% CI -0.74 to 1.32); p=0.58). There was no interaction between the underlying pathology and the effect of mask type on any outcome. INTERPRETATION: Oronasal masks are the most used interface for the delivery of home NIV in patients with OHS and COPD; however, there is no difference in the efficacy or tolerance of oronasal or nasal masks

Effect of genetic testing for risk of type 2 diabetes mellitus on health behaviors and outcomes: study rationale, development and design

<p>Abstract</p> <p>Background</p> <p>Type 2 diabetes is a prevalent chronic condition globally that results in extensive morbidity, decreased quality of life, and increased health services utilization. Lifestyle changes can prevent the development of diabetes, but require patient engagement. Genetic risk testing might represent a new tool to increase patients' motivation for lifestyle changes. Here we describe the rationale, development, and design of a randomized controlled trial (RCT) assessing the clinical and personal utility of incorporating type 2 diabetes genetic risk testing into comprehensive diabetes risk assessments performed in a primary care setting.</p> <p>Methods/Design</p> <p>Patients are recruited in the laboratory waiting areas of two primary care clinics and enrolled into one of three study arms. Those interested in genetic risk testing are randomized to receive <it>either </it>a standard risk assessment (SRA) for type 2 diabetes incorporating conventional risk factors plus upfront disclosure of the results of genetic risk testing ("SRA+G" arm), <it>or </it>the SRA alone ("SRA" arm). Participants not interested in genetic risk testing will not receive the test, but will receive SRA (forming a third, "no-test" arm). Risk counseling is provided by clinic staff (not study staff external to the clinic). Fasting plasma glucose, insulin levels, body mass index (BMI), and waist circumference are measured at baseline and 12 months, as are patients' self-reported behavioral and emotional responses to diabetes risk information. Primary outcomes are changes in insulin resistance and BMI after 12 months; secondary outcomes include changes in diet patterns, physical activity, waist circumference, and perceived risk of developing diabetes.</p> <p>Discussion</p> <p>The utility, feasibility, and efficacy of providing patients with genetic risk information for common chronic diseases in primary care remain unknown. The study described here will help to establish whether providing type 2 diabetes genetic risk information in a primary care setting can help improve patients' clinical outcomes, risk perceptions, and/or their engagement in healthy behavior change. In addition, study design features such as the use of existing clinic personnel for risk counseling could inform the future development and implementation of care models for the use of individual genetic risk information in primary care.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00849563">NCT00849563</a></p

Assessing the utility of autofluorescence-based pulmonary optical endomicroscopy to predict the malignant potential of solitary pulmonary nodules in humans

Solitary pulmonary nodules are common, often incidental findings on chest CT scans. The investigation of pulmonary nodules is time-consuming and often leads to protracted follow-up with ongoing radiological surveillance, however, clinical calculators that assess the risk of the nodule being malignant exist to help in the stratification of patients. Furthermore recent advances in interventional pulmonology include the ability to both navigate to nodules and also to perform autofluorescence endomicroscopy. In this study we assessed the efficacy of incorporating additional information from label-free fibre-based optical endomicrosopy of the nodule on assessing risk of malignancy. Using image analysis and machine learning approaches, we find that this information does not yield any gain in predictive performance in a cohort of patients. Further advances with pulmonary endomicroscopy will require the addition of molecular tracers to improve information from this procedure

Effect of Home Noninvasive Ventilation With Oxygen Therapy vs Oxygen Therapy Alone on Hospital Readmission or Death After an Acute COPD Exacerbation

Importance: Outcomes after exacerbations of chronic obstructive pulmonary disease (COPD) requiring acute noninvasive ventilation (NIV) are poor and there are few treatments to prevent hospital readmission and death. Objective: To investigate the effect of home NIV plus oxygen on time to readmission or death in patients with persistent hypercapnia after an acute COPD exacerbation. Design, Setting, and Participants: A randomized clinical trial of patients with persistent hypercapnia (Paco2 >53 mm Hg) 2 weeks to 4 weeks after resolution of respiratory acidemia, who were recruited from 13 UK centers between 2010 and 2015. Exclusion criteria included obesity (body mass index [BMI] >35), obstructive sleep apnea syndrome, or other causes of respiratory failure. Of 2021 patients screened, 124 were eligible. Interventions: There were 59 patients randomized to home oxygen alone (median oxygen flow rate, 1.0 L/min [interquartile range {IQR}, 0.5-2.0 L/min]) and 57 patients to home oxygen plus home NIV (median oxygen flow rate, 1.0 L/min [IQR, 0.5-1.5 L/min]). The median home ventilator settings were an inspiratory positive airway pressure of 24 (IQR, 22-26) cm H2O, an expiratory positive airway pressure of 4 (IQR, 4-5) cm H2O, and a backup rate of 14 (IQR, 14-16) breaths/minute. Main Outcomes and Measures: Time to readmission or death within 12 months adjusted for the number of previous COPD admissions, previous use of long-term oxygen, age, and BMI. Results: A total of 116 patients (mean [SD] age of 67 [10] years, 53% female, mean BMI of 21.6 [IQR, 18.2-26.1], mean [SD] forced expiratory volume in the first second of expiration of 0.6 L [0.2 L], and mean [SD] Paco2 while breathing room air of 59 [7] mm Hg) were randomized. Sixty-four patients (28 in home oxygen alone and 36 in home oxygen plus home NIV) completed the 12-month study period. The median time to readmission or death was 4.3 months (IQR, 1.3-13.8 months) in the home oxygen plus home NIV group vs 1.4 months (IQR, 0.5-3.9 months) in the home oxygen alone group, adjusted hazard ratio of 0.49 (95% CI, 0.31-0.77; P = .002). The 12-month risk of readmission or death was 63.4% in the home oxygen plus home NIV group vs 80.4% in the home oxygen alone group, absolute risk reduction of 17.0% (95% CI, 0.1%-34.0%). At 12 months, 16 patients had died in the home oxygen plus home NIV group vs 19 in the home oxygen alone group. Conclusions and Relevance: Among patients with persistent hypercapnia following an acute exacerbation of COPD, adding home noninvasive ventilation to home oxygen therapy prolonged the time to readmission or death within 12 months. Trial Registration: clinicaltrials.gov Identifier: NCT00990132