Implementation and assessment of a model including mixotrophs and the carbonate cycle (Eco3M_MIX-CarbOx v1.0) in a highly dynamic Mediterranean coastal environment (Bay of Marseille, France) – Part 1: Evolution of ecosystem composition under limited light and nutrient conditions

Many current biogeochemical models rely on an autotrophic versus heterotrophic food web representation. However, in recent years, an increasing number of studies have begun to challenge this approach. Several authors have highlighted the importance of protists capable of combining photoautotrophic and heterotrophic nutrition in a single cell. These mixotrophic protists are known to play an important role in the carbon cycle. Here, we present a new biogeochemical model that represents the food web using variable stoichiometry. It contains the classic compartments such as zooplankton, phytoplankton, and heterotrophic bacteria and a newly added compartment to represent two types of mixotrophic protists: non-constitutive mixotrophs (NCMs) and constitutive mixotrophs (CMs). We demonstrate that the model correctly reproduces the characteristics of NCMs and CMs and proceed to study the impact of light and nutrient limitation on planktonic ecosystem structure in a highly dynamic Mediterranean coastal area, namely the Bay of Marseille (BoM, France), paying special attention to the dynamics of mixotrophic protists in these limiting conditions. In addition, we investigate the carbon, nitrogen, and phosphorus fluxes associated with mixotrophic protists and showed the following: (i) the portion of the ecosystem in terms of the percentage of carbon biomass occupied by NCMs decreases when resources (nutrient and prey concentrations) decrease, although their mixotrophy allows them to maintain a carbon biomass almost as significant as the copepod one (129.8 and 148.7 mmol C m−3, respectively), as photosynthesis increases as a food source, and (ii) the portion of the ecosystem in terms of the percentage of carbon biomass occupied by CM increases when nutrient concentrations decrease due to their capability to ingest prey to supplement their N and P needs. In addition to providing new insights regarding the conditions that lead to the emergence of mixotrophs in the BoM, this work provides a new tool to perform long-term studies and predictions of mixotroph dynamics in coastal environments under different environmental forcings.</p

Les facteurs influençant la prescription d'antidépresseurs en médecine générale

Les d'antidépresseurs sont prescrits à 80 % par les MG. 25 à 50 % des prescriptions concernent des indications non psychiatriques. Certaines de ses indications, hors AMM, sont justifiables par les données scientifiques. Des éléments contextuels (familiaux, sociaux, professionnels) déterminent également la prescription d'antidépresseurs. L'objectif principal de cette étude est d'évaluer l'influence respective des facteurs contextuels et biomédicaux sur la prescription d'antidépresseurs en soins primaires. L'objectif secondaire est d'évaluer la faisabilité et la pertinence du questionnaire pour une étude de plus grande ampleur. Méthode : C'est une étude épidémiologique transversale. 25 médecins généralistes ont inclus tous leurs patients pendant une période d'une semaine. Un premier questionnaire a évalué la prévalence des traitements antidépresseurs, leur posologie et leur durée. Ensuite, 2 observations comprenant une prescription d'antidépresseur ont été tirées au sort et évaluées par un questionnaire face à face. Un deuxième questionnaire, élaboré à partir d'une précédente étude qualitative, a évalué les déterminants (biomédicaux, sociaux, et contextuels) de la prescription. L'influence respective de chaque facteur a été mesurée. Une évaluation qualitative des questions et de leur libellé a été effectuée par le médecin interviewé et le chercheur. Résultats : Les facteurs influençant le plus la prescription étaient les troubles psychiques dépressifs ou anxieux, mais il existait jusqu'à 3 à 4 cofacteurs associés à la prescription. Les pathologies douloureuses, en particulier neurologiques, une situation judiciaire en cours ou du stress au travail étaient des éléments encourageant fortement la prescription. Le tabagisme, les addictions, l'invalidité ne semblaient pas du tout influencer la mise sous traitement. L'évaluation qualitative a permis d'affiner le questionnaire, en particulier pour l'évaluation du contexte familial. Conclusion : Les médecins généralistes sont à l'origine de la majorité des prescriptions d'antidépresseurs. Cette étude a montré que le contexte psycho-social jouait un rôle important dans la prescription. Les pathologies psychiatriques sont, comme attendues les motifs de prescriptions les plus fréquents et les plus influents. 18% des observations concernent des diagnostics non psychiatriques, au cœur desquelles on retrouve les pathologies douloureuses

Les barrières tombent : réflexions sur le SIGB libre

National audienceA la fin de l'année 2005, un groupe de réflexion sur les SIGB libres a été créé. Il observe les évolutions en France et à l'étranger. Les freins à l'adoption du libre se desserrent. Ils ne sont plus tant sur la technique que dans les mentalités

Un cas d’acidose pyroglutamique associé à la prise concomitante de cloxacilline et d’acétaminophène

RésuméObjectif : Décrire un cas clinique d’acidose pyroglutamique qui serait causé par la prise concomitante de cloxacilline et d’acétaminophène et discuter des étiologies possibles de ce type d’acidose métabolique avec une élévation du trou anionique.Résumé du cas : Une patiente de 83 ans, souffrant d’une infection, a développé une acidose métabolique avec une élévation du trou anionique et des lactates normaux lors du traitement à la cloxacilline d’un anévrisme mycotique à Staphylococcus aureus sensible à la méthicilline. La patiente recevait également de l’acétaminophène durant son hospitalisation. En retirant les agents causaux (cloxacilline et acétaminophène) et en instaurant un traitement de soutien et un protocole de N-Acétylcystéine, la patiente a récupéré rapidement sans subir de conséquence permanente.Discussion : L’acidose pyroglutamique résulte de l’accumulation de 5-oxoproline secondaire à des anomalies du cycle gammaglutamyl et à une déplétion en glutathion. Plusieurs rapports de cas décrivent différents facteurs de risque, dont certains médicaments (acétaminophène, cloxacilline, vigabatrin) et certaines comorbidités (atteinte rénale ou hépatique, sepsis, malnutrition). Selon les algorithmes de Naranjo et DIPS, il est probable que ce cas d’acidose pyroglutamique ait été causé par la combinaison de cloxacilline et d’acétaminophène. Bien qu’une valeur d’excrétion rénale de 5-oxoproline aurait permis de confirmer le diagnostic, la suspicion clinique demeure élevée après l’exclusion des autres causes potentielles.Conclusion : L’acidose pyroglutamique est une cause rare d’acidose métabolique avec une élévation du trou anionique, et on devrait penser à une telle acidose une fois que le diagnostic différentiel a éliminé les étiologies communes d’acidose. Ce cas souligne bien le rôle du pharmacien dans la détection des effets indésirables médicamenteux rares.AbstractObjective: To describe a clinical case of pyroglutamic acidosis apparently caused by the concomitant use of cloxacillin and acetaminophen and to discuss the possible etiologies of this type of metabolic acidosis accompanied by an elevated anion gap.Case summary: An 83-year-old female patient with an infection developed metabolic acidosis with an elevated anion gap and normal lactates while being treated with cloxacillin for a methicillin-sensitive Staphylococcus aureus mycotic aneurysm. The patient also received acetaminophen during her hospital stay. Upon the withdrawal of the causal agents (cloxacillin and acetaminophen) and the initiation of supportive treatment and an N-acetylcysteine protocol, the patient experienced a rapid recovery with no permanent sequelae.Discussion: Pyroglutamic acidosis results from a build-up of 5-oxoproline secondary to gamma-glutamyl cycle abnormalities and glutathione depletion. A number of case reports describe different risk factors, among which are certain drugs (acetaminophen, cloxacillin and vigabatrin) and certain comorbidities (hepatic or renal impairment, sepsis and malnutrition). Based on the Naranjo and Drug Interaction Probability Scale algorithms, this case of pyroglutamic acidosis was probably caused by the concomitant use of cloxacillin and acetaminophen. Although the diagnosis could have been confirmed from a urinary 5-oxoproline excretion value, clinical suspicion remained strong after ruling out the other possible causes.Conclusion: Pyroglutamic acidosis is a rare cause of metabolic acidosis accompanied by an elevated anion gap and should be considered once the differential diagnosis has ruled out the common etiologies of acidosis. This case underscores the pharmacist’s role in detecting rare drug adverse effects

Les solidarités, le logement abordable et le logement partagé : entre dispositifs juridiques et modèles économiques

Compte rendu et analyses, Séminaire PUCA, 17 mai 2013, Paris La Défense

Dataset for "Disentangling mechanisms responsible for wind energy effects on European bats"

Data used in the study "Disentangling mechanisms responsible for wind energy effects on European bats". site = ID attributed to the studied site ; ID_Parc = ID attributed to the studied wind farm ; night = date of the sampling ; SM4 = ID attributed to the recorder ; NbWT_1500m = number of wind turbines in a 1500m buffer ; Dist_WT = distance to the nearest wind turbine ; Dist_water = distance to the nearest water body or water course ; Dist_forest = distance to the nearest forest ; avg_temp = average temperature of the night ; Prev_wind_mod1 = prevailing wind direction of the night ; count_prev_wind22.5 = number of hours during which the wind direction was close (± 22.5°) to the prevailing wind direction (mode) of the night ; angle = angle between the axis wind-turbine - detector and the north direction ; MES_year = year of commissioning of the nearest wind turbines ; Model = model of the nearest wind turbine ; Rotor_diameter = diameter of the rotor of the nearest wind turbine ; Hub_height = height of the hub of the nearest wind turbine ; ID_WT = ID attributed to the nearest wind turbin

HprSR is a Reactive Chlorine Species-Sensing, Two-Component System in Escherichia coli

International audienceTwo-component systems (TCS) are signalling pathways that allow bacterial cells to sense, respond and adapt to fluctuating environments. Among the classical TCS of Escherichia coli , HprSR has recently been shown to be involved in the regulation of msrPQ , which encodes the periplasmic methionine sulfoxide reductase system. In this study, we demonstrate that hypochlorous acid (HOCl) induces the expression of msrPQ in an HprSR-dependant manner, whereas H 2 O 2 , NO and paraquat (a superoxide generator) do not. Therefore, HprS appears to be an HOCl-sensing histidine kinase. Using a directed mutagenesis approach, we show that Met residues located in the periplasmic loop of HprS are important for its activity: as HOCl preferentially oxidizes Met residues, we provide evidence that HprS could be activated via the reversible oxidation of its methionine residues, meaning that MsrPQ plays a role in switching HprSR off. We propose that the activation of HprS by HOCl could occur through a Met redox switch. HprSR appears to be the first characterized TCS able to detect reactive chlorine species (RCS) in E. coli . This study represents an important step towards understanding the mechanisms of RCS resistance in prokaryotes. IMPORTANCE Understanding how bacteria respond to oxidative stress at the molecular level is crucial in the fight against pathogens. HOCl is one of the most potent industrial and physiological microbiocidal oxidants. Therefore bacteria have developed counterstrategies to survive HOCl-induced stress. Over the last decade, important insights into these bacterial protection factors have been obtained. Our work establishes HprSR as a reactive chlorine species-sensing, two-component system in Escherichia coli MG1655, which regulates the expression of MsrPQ, a repair system for HOCl-oxidized proteins. Moreover we provide evidence suggesting that HOCl could activate HprS through a methionine redox switch

Salmonella Typhimurium uses the Cpx stress response to detect N -chlorotaurine and promote the repair of oxidized proteins

International audienceThe cell envelope of gram-negative bacteria constitutes the first protective barrier between a cell and its environment. During host infection, the bacterial envelope is subjected to several stresses, including those induced by reactive oxygen species (ROS) and reactive chlorine species (RCS) produced by immune cells. Among RCS, N- chlorotaurine ( N- ChT), which results from the reaction between hypochlorous acid and taurine, is a powerful and less diffusible oxidant. Here, using a genetic approach, we demonstrate that Salmonella Typhimurium uses the CpxRA two-component system to detect N -ChT oxidative stress. Moreover, we show that periplasmic methionine sulfoxide reductase (MsrP) is part of the Cpx regulon. Our findings demonstrate that MsrP is required to cope with N -ChT stress by repairing N -ChT-oxidized proteins in the bacterial envelope. By characterizing the molecular signal that induces Cpx when S. Typhimurium is exposed to N -ChT, we show that N -ChT triggers Cpx in an NlpE-dependent manner. Thus, our work establishes a direct link between N -ChT oxidative stress and the envelope stress response