Catalysis of the electrochemical oxygen reduction reaction (ORR) by animal and human cells

Animal cells from the Vero lineage and MRC5 human cells were checked for their capacity to catalyse the electrochemical oxygen reduction reaction (ORR). The Vero cells needed 72 hours’ incubation to induce ORR catalysis. The cyclic voltammetry curves were clearly modified by the presence of the cells with a shift of ORR of 50 mV towards positive potentials and the appearance of a limiting current (59 μA.cm-2). The MRC5 cells induced considerable ORR catalysis after only 4 h of incubation with a potential shift of 110 mV but with large experimental deviation. A longer incubation time, of 24 h, made the results more reproducible with a potential shift of 90 mV. The presence of carbon nanotubes on the electrode surface or pre-treatment with foetal bovine serum or poly-D-lysine did not change the results. These data are the first demonstrations of the capability of animal and human cells to catalyse electrochemical ORR. The discussion of the possible mechanisms suggests that these pioneering observations could pave the way for electrochemical biosensors able to characterize the protective system of cells against oxidative stress and its sensitivity to external agents

New dating of the «mask» of La Roche-Cotard (Langeais, Indre-et-Loire, France)

Le «masque» de la Roche-Cotard a été découvert au sein d’une couche contenant une industrie lithique de technologie et typologie caractéristiques du Paléolithique moyen. Après une première datation de la couche, supérieure à 32 ka BP et deux autres datations par le 14C attribuant à la couche un âge supérieur à 40 ka, une datation sur quartz par la méthode de la luminescence (OSL) donne un âge de 75,6 ± 5,8 ka au dépôt alluvial qui contient le «masque». Ce nouveau résultat confirme que les datations 14C par Spectrométrie de Masse par Accélérateur (AMS) obtenues sur des fragments osseux de cette même couche sont au-delà de la limite de la validité de la méthode de datation par le radiocarbone. Nous exposons, en annexe, le principe de la méthode des datations OSL qui doivent être retenues pour dater l’occupation néandertalienne de La Roche Cotard II d’où provient le masque, et leurs implications.The "mask" of La Roche-Cotard was discovered in a layer containing a characteristic Middle Paleolithic lithic industry. After a first 14C result of 32 ka BP, two further 14C dates now assign the layer to more than 40 ka, but above all an OSL date obtained on quartz attributes to the layer containing the «mask» an age of 75.6 ± 5.8 ka. This new result confirms that 14C dates with Accelerator Mass Spectrometry, obtained on bones of that layer are beyond the limit of validity of the radiocarbon dating method. We present the principle of the method of luminescence dating that should be retained for the Neanderthal occupation of the Roche Cotard II level 7 and its implications.info:eu-repo/semantics/publishedVersio

Design, setup and routine operation of a water treatment system for the monitoring of low activities of tritium in water

In the TRITIUM project, an on-site monitoring system is being developed to measure tritium (H) levels in water near nuclear power plants. The quite low-energy betas emitted by H have a very short average path in water (5 μm as shown by simulations for 18 keV electrons). This path would be further reduced by impurities present in the water, resulting in a significant reduction of the detection efficiency. Therefore, one of the essential requirements of the project is the elimination of these impurities through a filtration process and the removal of salts in solution. This paper describes a water treatment system developed for the project that meets the following requirements: the water produced should be of near-pure water quality according to ISO 3696 grade 3 standard (conductivity < 10 μS/cm); the system should operate autonomously and be remotely monitored.This work was supported by the INTERREG-SUDOE EEC program through the project TRITIUM e SOE1/P4/E0214 entitled: “Dise~no, construccition y puesta a punto de estaciones automaticas para el monitoraje en tiempo real de bajos niveles radiactivos de tritio en aguas

In vivo and ex vivo percutaneous absorption of [14C]-bisphenol A in rats: a possible extrapolation to human absorption?

Bisphenol A (BPA) is a monomer used mainly in the synthesis of polycarbonates and epoxy resins. Percutaneous absorption is the second source of exposure, after inhalation, in the work environment. However, studies on this route of absorption are lacking or incomplete. In this study, percutaneous BPA absorption was measured in vivo and ex vivo in the rat, and ex vivo in humans. An approximately 12-fold difference in permeability between rat skin and human skin was found, with permeability being higher in the rat. In addition, inter- and intra-individual variability of up to tenfold was observed in humans. No accumulation of BPA in the skin was found during exposure. The skin clearance rate following exposure was estimated at 0.4 μg/cm²/h. Ex vivo and in vivo percutaneous absorption fluxes of BPA in the rat were in the same range (about 2.0 μg/cm²/h), suggesting that extrapolation to the in vivo situation in humans may be possible. The European tolerable daily intake (TDI) of BPA is 50 μg/kg body weight. However, many research projects have highlighted the significant effects of BPA in rodents at doses lower than 10 μg/kg/day. A 1-h occupational exposure over 2,000 cm² (forearms and hands) may lead to a BPA absorption of 4 μg/kg/day. This is 8% of the European TDI and is very close to the value at which effects have been observed in animals. This absorption must therefore be taken into account when evaluating risks of BPA exposure, at least until more relevant results on the toxicity of BPA in humans are available

Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism

Objectives Gut microbiota is a key component in obesity and type 2 diabetes, yet mechanisms and metabolites central to this interaction remain unclear. We examined the human gut microbiome\u27s functional composition in healthy metabolic state and the most severe states of obesity and type 2 diabetes within the MetaCardis cohort. We focused on the role of B vitamins and B7/B8 biotin for regulation of host metabolic state, as these vitamins influence both microbial function and host metabolism and inflammation. Design We performed metagenomic analyses in 1545 subjects from the MetaCardis cohorts and different murine experiments, including germ-free and antibiotic treated animals, faecal microbiota transfer, bariatric surgery and supplementation with biotin and prebiotics in mice. Results Severe obesity is associated with an absolute deficiency in bacterial biotin producers and transporters, whose abundances correlate with host metabolic and inflammatory phenotypes. We found suboptimal circulating biotin levels in severe obesity and altered expression of biotin-associated genes in human adipose tissue. In mice, the absence or depletion of gut microbiota by antibiotics confirmed the microbial contribution to host biotin levels. Bariatric surgery, which improves metabolism and inflammation, associates with increased bacterial biotin producers and improved host systemic biotin in humans and mice. Finally, supplementing high-fat diet-fed mice with fructo-oligosaccharides and biotin improves not only the microbiome diversity, but also the potential of bacterial production of biotin and B vitamins, while limiting weight gain and glycaemic deterioration. Conclusion Strategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity

Imidazole propionate is increased in diabetes and associated with dietary patterns and altered microbial ecology

Microbiota-host-diet interactions contribute to the development of metabolic diseases. Imidazole propionate is a novel microbially produced metabolite from histidine, which impairs glucose metabolism. Here, we show that subjects with prediabetes and diabetes in the MetaCardis cohort from three European countries have elevated serum imidazole propionate levels. Furthermore, imidazole propionate levels were increased in subjects with low bacterial gene richness and Bacteroides 2 enterotype, which have previously been associated with obesity. The Bacteroides 2 enterotype was also associated with increased abundance of the genes involved in imidazole propionate biosynthesis from dietary histidine. Since patients and controls did not differ in their histidine dietary intake, the elevated levels of imidazole propionate in type 2 diabetes likely reflects altered microbial metabolism of histidine, rather than histidine intake per se. Thus the microbiota may contribute to type 2 diabetes by generating imidazole propionate that can modulate host inflammation and metabolism

The SuperNEMO calorimeter

The SuperNEMO double beta decay project is a modular tracker-calorimeter experiment that will reach a sensitivity to the neutrinoless double beta decay half-life of ∼ 10(26) years, corresponding to a Majorana neutrino mass of 50-100 meV. The main calorimeter is based on 440 Optical Modules made of large volume plastic scintillators (10L) coupled with large area photomultipliers (Hamamatsu R5912-Mod). They are assembled in walls surrounding the isotope foil and the tracking volume. One of the main challenges of the SuperNEMO detector development programme was to reach an energy resolution, better than 8%(FWHM) at 1 MeV. The other challenge was to satisfy the radiopurity requirements for all the calorimeter materials. The calorimeter design of the first SuperNEMO module is presented as well as its performances and the status of its construction under way in the Modane underground laboratory