Study protocol for a pragmatic cluster randomized controlled trial to improve dietary diversity and physical fitness among older people who live at home (the “ALAPAGE study”)

Background : Diet and physical activity are key components of healthy aging. Current interventions that promote healthy eating and physical activity among the elderly have limitations and evidence of French interventions’ effectiveness is lacking. We aim to assess (i) the effectiveness of a combined diet/physical activity intervention (the “ALAPAGE” program) on older peoples’ eating behaviors, physical activity and fitness levels, quality of life, and feelings of loneliness; (ii) the intervention’s process and (iii) its cost effectiveness. Methods : We performed a pragmatic cluster randomized controlled trial with two parallel arms (2:1 ratio) among people ≥60 years old who live at home in southeastern France. A cluster consists of 10 people participating in a “workshop” (i.e., a collective intervention conducted at a local organization). We aim to include 45 workshops randomized into two groups: the intervention group (including 30 workshops) in the ALAPAGE program; and the waiting-list control group (including 15 workshops). Participants (expected total sample size: 450) will be recruited through both local organizations’ usual practices and an innovative active recruitment strategy that targets hard-to-reach people. We developed the ALAPAGE program based on existing workshops, combining a participatory and a theory-based approach. It includes a 7-week period with weekly collective sessions supported by a dietician and/or an adapted physical activity professional, followed by a 12-week period of post-session activities without professional supervision. Primary outcomes are dietary diversity (calculated using two 24-hour diet recalls and one Food Frequency Questionnaire) and lower-limb muscle strength (assessed by the 30-second chair stand test from the Senior Fitness Test battery). Secondary outcomes include consumption frequencies of main food groups and water/hot drinks, other physical fitness measures, overall level of physical activity, quality of life, and feelings of loneliness. Outcomes are assessed before the intervention, at 6 weeks and 3 months later. The process evaluation assesses the fidelity, dose, and reach of the intervention as its causal mechanisms (quantitative and qualitative data). Discussion : This study aims to improve healthy aging while limiting social inequalities. We developed and evaluated the ALAPAGE program in partnership with major healthy aging organizations, providing a unique opportunity to expand its reach

Etude des modes d'acquisition de la signature isotopique en carbone des eaux souterraines et préservation du signal environnemental lors de la recharge des aquifères

La gestion des ressources en eau souterraine consiste en partie à l estimation du temps de séjour de l eau dans l aquifère. La décroissance radioactive du 14C au cours du temps est une méthode couramment utilisée. Cependant, elle repose notamment sur l estimation de l activité 14C (A14C) initiale des eaux souterraines. L eau se minéralise en carbone lors de son transfert à travers la zone non saturée (ZNS) par interaction avec le CO2 et la matrice carbonatée, interactions qui font l objet de cette étude. Un équipement spécifique au prélèvement du gaz, de l eau et de la matrice a été mis en place sur deux sites d étude en France, les sables de Fontainebleau non carbonatés (Yvelines) et les sables astiens carbonatés (Hérault). Les mesures in-situ sont couplées à une approche numérique afin de mieux contraindre les différents facteurs à l origine de la composition isotopique du CO2 à la base de la ZNS. En l absence de carbonates, le 13C du CO2 dépend du 13C moyen du CO2 produit, des quantités de CO2 produit et du coefficient de diffusion du CO2. Les variations saisonnières du 13C du CO2 en sub-surface tendent à disparaître en profondeur. Avant 1950, l A14C du CO2 peut être considérée égale à celle du CO2 atmosphérique. Après 1950, suite aux essais nucléaires atmosphériques, elle est intermédiaire entre celle du CO2 atmosphérique et celle de la matière organique à taux de renouvellement rapide. En présence de carbonates, le 13C du CO2 augmente (l A14C diminue) avec la profondeur. Cette évolution dépend du flux de précipitation/dissolution des carbonates, des quantités de CO2 produit et du coefficient de diffusion du CO2 dans la ZNS.The management of groundwater needs the estimation of the water residence time in aquifers, that can be done through the measurement of 14C radioactive decay of the Total Dissolved Inorganic Carbon (TDIC). This approach requires the knowledge of the TDIC 14C initial activity in recharge water. The groundwater mineralisation occurs in the Unsaturated Zone (UZ), where water interacts with CO2 and carbonates (if existing). We focus here on these interactions between both CO2, TDIC and carbonates. Two UZ have been investigated in France: the carbonate-free Fontainebleau sands and the carbonated Astian sands. Each site is equipped with a specific and experimental equipment to collect groundwater, UZ water, gas and solid matrix (organic matter and carbonate). The field-data are completed by a numeric approach in order to evaluate the different factors that define the CO2 isotopic composition at the bottom of the UZ. The 13C of CO2 depends on the mean 13C of produced CO2, the amount of produced CO2 and the diffusion coefficient of CO2. Subsurface seasonal variations of 13C disappear with depth. Before 1950, the 14C activity of CO2 can be assumed equal to atmospheric 14C level. After 1950, due to the atmospheric nuclear test, it depends on 14C activity of young organic matter and atmospheric CO2. The presence of carbonates leads to a 13C-enrichment of and a 14C-depletion of CO2 with depth, depending on the carbonate precipitation/dissolution flux, the amount of produced CO2 and the diffusion coefficient of CO2.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Identification et caractérisation d'un biseau salin dans l'aquifère côtier du Bajocien-Bathonien de la région de Caen (France)

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Hydrochemical and isotopic characterisation of the Bathonian and Bajocian coastal aquifer of the Caen area (northern France)

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Le SNO Renoir : réseau français d'observation des isotopes dans les précipitations

International audienceLe SNO RENOIR est un réseau de mesures à long terme des teneurs en isotopes de la molécule d'eau (d18O et d2H) dans les précipitations (pluie, neige) à l'échelle de la France métropolitaine et ultramarine. Il est constitué de 33 stations de prélèvement des eaux de pluie réparties sur tout le territoire métropolitain et ultramarin. Cet observatoire national de la composition isotopique des précipitations a pour but de partager des données essentielles sous forme de chroniques isotopiques au pas de temps mensuel avec toute la communauté scientifique

Lake Urmia Salt lake's sedimentation and water dynamics impacts on past environmental reconstruction

International audienceIn recent decades, an overall decrease in surface water resources, even saline, especially in semi-arid and arid regions of the world, can be both a precursor to a decrease in groundwater recharge. This decrease comes either from the impact of climate change moving towards a different distribution of precipitation and evapotranspiration indices, and/or from the increasing footprint of anthropogenic activities both through inappropriate water use, extensive pumping, or even population increases in areas already under pressure for freshwater resources (e.g., Wurtsbaugh et al., 2017; Wang et al., 2018). This is particularly pregnant in salt lake basins for which water resources are vital to hydro-ecosystems and the population. But these basins are not easy to study other than by modeling, due to their very complicated structures as well as the processes they undergo (saltwater intrusion, pollution, etc.), and considering the lacustrine sedimentary deposits (degradation) to which they may or may not be connected. Here we present ongoing research on the Urmia Lake Basin (northern Iran) which is facing a drastic decrease of more than 8 m in its water level over the last 20 years, leading to soil salinization, increase in dust storms, decline in ecosystem services with the effect of losses in agricultural production and massive emigration of rural communities. In order to understand the hydrogeological behavior of the lake under anthropogenic pressures (excessive pumping) and climate change, sedimentary sequences were recovered from the recently drained western part of Urmia Salt Lake, as well as surface and groundwater samples and geological samples from the entire Shahr Chay River Basin

Salt wedges and trapped brines of low-latitude endoreic saline lakes as potential modulators of GHG emission

International audienceAbstract Large salt lakes are long-term witnesses to climatic conditions and land use in their basins. The majority are experiencing a drastic drop in water levels due to climate change and human impact. Endoreic Lake Urmia (NW Iran), the sixth largest salt lake worldwide, is a striking example of this decline. Quantification of the relative contributions of natural variability and human impact on the lake's water supply is therefore essential. Here we present isotopic and radiocarbon analyses of surface and groundwater from the Shahr Chay River catchment, entering Lake Urmia on its western shore, and radiocarbon dating of a sedimentary core. Lake Urmia behaves like a large saltwater wedge almost entirely fed by the river and shallow groundwater. This leads to trapping of residual brines and formation of CH 4 and secondary CO 2 greenhouse gases, impacting sediment geochemical records and corresponding time scales for paleoenvironmental reconstructions. We conclude that (1) salt lakes functioning like a saline wedge, allowing organic matter oxidation, could contribute to increasing methane sources or reducing carbon sinks globally, and (2) endoreic basins worldwide need to be monitored before aridification-related salinization leads to the establishment of a saline wedge precluding any possibility of return to an equilibrium state

Structural basis for substrate selectivity and nucleophilic substitution mechanisms in human adenine phosphoribosyltransferase catalyzed reaction

International audienceThe reversible adenine phosphoribosyltransferase enzyme (APRT) is essential for purine homeostasis in prokaryotes and eukaryotes. In humans, APRT (hAPRT) is the only enzyme known to produce AMP in cells from dietary adenine. APRT can also process adenine analogs, which are involved in plant development or neuronal homeostasis. However, the molecular mechanism underlying substrate specificity of APRT and catalysis in both directions of the reaction remains poorly understood. Here we present the crystal structures of hAPRT complexed to three cellular nucleotide analogs (hypoxanthine, IMP, and GMP) that we compare with the phosphate-bound enzyme. We established that binding to hAPRT is substrate shape-specific in the forward reaction, whereas it is base-specific in the reverse reaction. Furthermore , a quantum mechanics/molecular mechanics (QM/ MM) analysis suggests that the forward reaction is mainly a nucleophilic substitution of type 2 (S N 2) with a mix of S N 1-type molecular mechanism. Based on our structural analysis, a magnesium-assisted S N 2-type mechanism would be involved in the reverse reaction. These results provide a framework for understanding the molecular mechanism and substrate discrimination in both directions by APRTs. This knowledge can play an instrumental role in the design of inhibitors, such as antiparasitic agents, or adenine-based substrates

Structural Insights into the Forward and Reverse Enzymatic Reactions in Human Adenine Phosphoribosyltransferase

International audienceHighlights d Human APRT catalyzes the transformation of adenine into AMP and vice versa d Complexes with substrates in both directions of the reaction highlight key residues d The catalytic flexible loop dynamic is revealed by an in crystallo activity d Tyr105 is essential for cell growth by facilitating the forward reaction In Brief APRT is a key enzyme in the purine salvage pathway in prokaryotes and eukaryotes. Huyet et al., by using in vitro, cellular, and in crystallo enzymatic analyses, reveal that a hydroxyl group in a conserved tyrosine controls the protein dynamics and the catalytic efficiencies of the forward and reverse reactions