157 research outputs found

    Harmonisation and Between-Country Differences of the Lifetime of Experiences Questionnaire in Older Adults

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    Background: The Lifetime of Experiences Questionnaire (LEQ) assesses complex mental activity across the life-course and has been associated with brain and cognitive health. The different education systems and occupation classifications across countries represent a challenge for international comparisons. The objectives of this study were four-fold: to adapt and harmonise the LEQ across four European countries, assess its validity across countries, explore its association with brain and cognition and begin to investigate between-country differences in life-course mental activities. Method: The LEQ was administered to 359 cognitively unimpaired older adults (mean age and education: 71.2, 13.2 years) from IMAP and EU-funded Medit-Ageing projects. Education systems, classification of occupations and scoring guidelines were adapted to allow comparisons between France, Germany, Spain and United Kingdom. We assessed the LEQ's (i) concurrent validity with a similar instrument (cognitive activities questionnaire - CAQ) and its structural validity by testing the factors' structure across countries, (ii) we investigated its association with cognition and neuroimaging, and (iii) compared its scores between countries. Results: The LEQ showed moderate to strong positive associations with the CAQ and revealed a stable multidimensional structure across countries that was similar to the original LEQ. The LEQ was positively associated with global cognition. Between-country differences were observed in leisure activities across the life-course. Conclusions: The LEQ is a promising tool for assessing the multidimensional construct of cognitive reserve and can be used to measure socio-behavioural determinants of cognitive reserve in older adults across countries. Longitudinal studies are warranted to test further its clinical utility

    Clinical practice guideline for the management of lipids in adults with diabetic kidney disease: abbreviated summary of the Joint Association of British Clinical Diabetologists and UK Kidney Association (ABCD-UKKA) Guideline 2024

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    The contribution of chronic kidney disease (CKD) towards the risk of developing cardiovascular disease (CVD) is magnified with co-existing type 1 or type 2 diabetes. Lipids are a modifiable risk factor and good lipid management offers improved outcomes for people with diabetic kidney disease (DKD). The primary purpose of this guideline, written by the Association of British Clinical Diabetologists (ABCD) and UK Kidney Association (UKKA) working group, is to provide practical recommendations on lipid management for members of the multidisciplinary team involved in the care of adults with DKD

    Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting.

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    In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.This work was supported by the U.K. Engineering and Physical Sciences Research Council (EP/H00338X/2 to E.R. and EP/G037221/1, nanoDTC, to D.M.), the UK Biology and Biotechnological Sciences Research Council (BB/K002627/1 to A.W.R. and BB/K010220/1 to E.R.), a Marie Curie Intra-European Fellowship (PIEF-GA-2013-625034 to C.Y.L), a Marie Curie International Incoming Fellowship (PIIF-GA-2012-328085 RPSII to J.J.Z) and the CEA and the CNRS (to J.C.F.C.). A.W.R. holds a Wolfson Merit Award from the Royal Society.This is the final version of the article. It first appeared from ACS Publications via http://dx.doi.org/10.1021/jacs.5b0373

    Reactivation from the Ni-B state in [NiFe] hydrogenase of Ralstonia eutropha is controlled by reduction of the superoxidised proximal cluster

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    The tolerance towards oxic conditions of O2-tolerant [NiFe] hydrogenases has been attributed to an unusual [4Fe–3S] cluster that lies proximal to the [NiFe] active site. Upon exposure to oxygen, this cluster converts to a superoxidised (5+) state, which is believed to secure the formation of the so-called Ni–B state that is rapidly reactivated under reducing conditions. Here, the reductive reactivation of the membrane-bound [NiFe]-hydrogenase (MBH) from Ralstonia eutropha in a native-like lipid membrane was characterised and compared to a variant that instead carries a typical [4Fe–4S] proximal cluster. Reactivation from the Ni–B state was faster in the [4Fe–4S] variant, suggesting that the reactivation rate in MBH is limited by the reduction of the superoxidised [4Fe–3S] cluster. We propose that the [4Fe–3S] cluster plays a major role in protecting MBH by blocking the reversal of electron transfer to the [NiFe] active site, which would produce damaging radical oxygen species

    Enhanced oxygen-tolerance of the full heterotrimeric membrane-bound [NiFe]-hydrogenase of ralstonia eutropha.

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    Hydrogenases are oxygen-sensitive enzymes that catalyze the conversion between protons and hydrogen. Water-soluble subcomplexes of membrane-bound [NiFe]-hydrogenases (MBH) have been extensively studied for applications in hydrogen-oxygen fuel cells as they are relatively tolerant to oxygen, although even these catalysts are still inactivated in oxidative conditions. Here, the full heterotrimeric MBH of Ralstonia eutropha, including the membrane-integral cytochrome b subunit, was investigated electrochemically using electrodes modified with planar tethered bilayer lipid membranes (tBLM). Cyclic voltammetry and chronoamperometry experiments show that MBH, in equilibrium with the quinone pool in the tBLM, does not anaerobically inactivate under oxidative redox conditions. In aerobic environments, the MBH is reversibly inactivated by O2, but reactivation was found to be fast even under oxidative redox conditions. This enhanced resistance to inactivation is ascribed to the oligomeric state of MBH in the lipid membrane

    Methodologies for “Wiring” Redox Proteins/Enzymes to Electrode Surfaces

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    The immobilization of redox proteins or enzymes onto conductive surfaces has application in the analysis of biological processes, the fabrication of biosensors, and in the development of green technologies and biochemical synthetic approaches. This review evaluates the methods through which redox proteins can be attached to electrode surfaces in a “wired” configuration, that is, one that facilitates direct electron transfer. The feasibility of simple electroactive adsorption onto a range of electrode surfaces is illustrated, with a highlight on the recent advances that have been achieved in biotechnological device construction using carbon materials and metal oxides. The covalent crosslinking strategies commonly used for the modification and biofunctionalization of electrode surfaces are also evaluated. Recent innovations in harnessing chemical biology methods for electrically wiring redox biology to surfaces are emphasized

    LA COMBINAISON DES ROLES DES MEMBRES DANS LES PROCESSUS DU CONSEIL, une lecture cognitive de la gouvernance au travers de ses dynamiques stratégiques et fonctionnelles

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    The goal of this work is to open the fields of reading of corporate governance towards other horizons than the only financial focus. To achieve this, this research is based on cognitive governance and proposes a successful extension. It proposes a cadastre of the theories that can be mobilized and applied to the board of directors, notably that of professional social identity, of role theory, in their context of expression. Actor strategies resulting from the roles held by the members will be called following the revisited theory of concrete action systems.One of the richest aspects of this work lies in the approach of five different categories of practicing members, who will combine in multiple and sometimes contradictory roles, particularly in their relationship of dependence on the principal parties.The analysis that is proposed is based on the construction and implementation of a quadrupole grid containing all the theories mobilized applied to the field. In the end, it leads to a dynamic reading of the board by typology of governance.The result of this research is that areas of significant progress are identified in accordance with the behavioral expression of governance. These have consequences in the company itself if we consider that the strategy, proposed and validated in the board, requires the development of the macro-skills of the women and men who carry it and, beyond that, of the human capital who organizes the whole collective enterprise project, so the board members.La thèse a pour objectif d’ouvrir les champs de lecture de la gouvernance d’entreprise vers d’autres horizons que la seule focale financière. Pour l’atteindre, cette recherche s’appuie sur la gouvernance cognitive et en propose une extension aboutie. Elle propose un cadastre des théories mobilisables et applicables au Conseil, dont notamment celle de l’identité sociale professionnelle, de la théorie des rôles, dans leur contexte d’expression. Seront ainsi appelées les stratégies d’acteur issues des rôles tenus par les membres suivant la théorie revisitée des systèmes d’actions concrets.L’un des aspects qui fait la richesse de ce travail réside dans l’abord de cinq différentes catégories de membres en exercice, qui vont se combiner à travers des rôles multiples et parfois contradictoires, notamment dans leur relation de dépendance aux parties mandantes.L’analyse qui est proposée repose sur la construction et la mise en œuvre d’une grille quadripolaire reprenant l’ensemble des théories mobilisées appliquées au terrain. Elle conduit in fine à une lecture dynamique du Conseil par typologie de gouvernance.Il résulte de cette recherche que des zones de progrès significatives sont identifiées en ce qui concerne l’expression comportementale de la gouvernance. Celles-ci ont des conséquences dans l’entreprise elle-même si on considère que la stratégie, proposée et validée au Conseil, passe par la valorisation des macro-compétences des femmes et des hommes qui la portent et, au delà, du capital humain qui organise l'ensemble du projet collectif d'entreprise, donc les membres au Conseil

    Electrochemical investigations of H2-producing enzymes

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    Hydrogenases are a family of enzyme that catalyses the bidirectional interconversion of H+ and H2. There are two major classes of hydrogenases: the [NiFe(Se)]- and [FeFe]-hydrogenases. Both of these benefit from characteristics which would be advantageous to their use in technological devices for H2 evolution and the generation of energy. These features are explored in detail in this thesis, with a particular emphasis placed on defining the conditions that limit the activity of hydrogenases when reducing H+ to produce H2. Electrochemistry can be used as a direct measure of enzymatic activity; thus, Protein Film Electrochemistry, in which the protein is adsorbed directly onto the electrode, has been employed to probe catalysis by hydrogenases. Various characteristics of hydrogenases were probed. The catalytic bias for H2 production was interrogated and the inhibition of H2 evolution by H2 itself (a major drawback to the use of some hydrogenases in technological devices to produce H2) was quantified for a number of different hydrogenase. Aerobic inactivation of hydrogenases is also a substantial technological limitation; thus, inactivation of both H2 production and H2 oxidation by O2 was studied in detail. This was compared to inhibition of hydrogenases by CO so as to elucidate the mechanism of binding of diatomic molecules and determine the factors limiting inactivation. This allows for a preliminary proposal for the genetic redesigning of hydrogenases for biotechnological purposes to be made. Finally, preliminary investigation of the binding of formaldehyde, potentially at a site integral to proton transfer, opens the field for further research into proton transfer pathways, the structural implications thereof and their importance in catalysis.</p
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