Journal of Next-Generation Research 5.0
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Stress oxydant et glycoxydation : impact des produits avancés de glycation sur les mitochondries des cellules endothéliales dans le cadre de la pathologie diabétique
No full textThe endothelium ensures the maintenance of vascular homeostasis. It is a fundamental regulator of vascular tone, coagulation, fibrinolysis, and inflammation. Its dysfunction mediates numerous pathologies, including, among others, diabetes vascular complications, particularly cardiovascular diseases, the major cause of mortality in diabetic patients.Oxidative stress related to advanced glycation end products (AGEs), whose formation is enhanced by hyperglycemia, represents the central element of endothelial dysfunction. This stress is defined as “an imbalance between oxidants and anti-oxidants in favor of the oxidants”, and can originate from mitochondria. The objective of my thesis was to determine the effects of AGEs derived from albumin (the most abundant protein in plasma) on mitochondria of cultured endothelial cells, in parallel to an analysis of the molecular mechanisms involved in intracellular oxidative stress, and endothelial functions.Mitochondrial exploration mainly focused on the description of the respiratory states and revealed AGEs-associated phenotypes, depending on endothelial cell model and cell confluence. Furthermore, two other key results from my investigations correspond to the highlighting of: 1) the alteration of albumin antioxidant properties, as well as the acquisition of a pro-oxidant capacity after glycoxidation processes; 2) the involvement of mitochondria in oxidative stress, through a potential communication with NADPH oxidase, an enzyme that produces superoxide anions.This work brings novel insights into the redox imbalance observed in endothelial cells during diabetes, in relation to the mitochondrial aspect.L’endothélium est une barrière semi-perméable assurant le maintien de l’homéostasie vasculaire. C’est un régulateur clé du tonus vasculaire, des processus de coagulation et de fibrinolyse, et de l’inflammation. Sa dysfonction est à l’origine de nombreuses pathologies parmi lesquelles figurent les complications vasculaires liées au diabète, notamment les maladies cardiovasculaires, première cause de mortalité chez les patients diabétiques. Le stress oxydant associé aux produits avancés de glycation (AGEs), dont la formation est favorisée par l’hyperglycémie, constitue l’élément central de la dysfonction endothéliale. Ce stress correspond à un déséquilibre entre les défenses antioxydantes et les espèces prooxydantes cellulaires en faveur de ces dernières, et peut être d’origine mitochondriale. L’objectif de mon travail de thèse a été de déterminer les effets des AGEs dérivant de l’albumine (la protéine plasmatique la plus abondante) sur le fonctionnement des mitochondries de cellules endothéliales en culture, en parallèle à une analyse des mécanismes moléculaires impliqués dans le stress oxydant intracellulaire, et des fonctions endothéliales. L’étude mitochondriale s’est principalement axée sur la description des états respiratoires et a révélé des phénotypes associés aux AGEs, variant en fonction du modèle cellulaire endothélial et de la confluence. Par ailleurs, deux autres résultats phares issus de mes investigations correspondent à la mise en évidence de : 1) l’altération des propriétés antioxydantes de l’albumine, ainsi que l’acquisition d’un pouvoir pro-oxydant après glycoxydation ; 2) la contribution des mitochondries au stress oxydant, à travers une communication possible avec la NADPH oxydase, une enzyme produisant des anions superoxydes. Ce travail apporte ainsi un nouvel éclairage sur le déséquilibre redox observé chez les cellules endothéliales dans le cadre de la pathologie diabétique, en relation avec l’aspect mitochondrial
Étude et modélisation d’écoulements en convection mixte : application au désenfumage naturel de bâtiments
No full textThis thesis work presents deals with the issue of fire safety consideration in naturally ventilated buildings. The particular case of the interaction between the wind and hot smoke movement is pinpointed. In the first chapter, basics of natural ventilation mechanisms are shown. Then, the analysis of building’s regulations, relating to fire safety and thermal comfort, allows to highlight potential conflicts and normative gaps. Theses gaps and conflicts are illustrated through real buildings feedbacks. The challenge of indoor flow pattern studies for safety purpose is hence underline. In the second chapter, scientific’s barriers in relation with the transitions between existing flow pattern, when wind and buoyancy are opposed, are identified thought a literature review. A scaled experiment is proposed in the third chapter, using density difference between air and helium, to identify internal flow pattern when wind opposes buoyancy. Three stable internal flow patterns are identified. A power law characterizing the transitions between identified flow pattern, involving source Froude number and dynamic pressure ratio between source jet and wind, is found. In the fourth chapter, the identified flow pattern are observed when the tested volume is emptied, and a relation between the initial Richardson number Ri and the characteristic emptied time θ is found. Furthermore, specific behaviour of internal flow, when the volume is emptied, is quantitatively study thanks to a numerical model. In the last part of this thesis, transitions law between internal flow patterns allows to introduce a new wind dependent fire safety index. A methodology is then proposed to both analyse fire safety and thermal comfort in building. The presented method gives the opportunity to avoid conception conflicts underlined in the first chapter of the present work.Ces travaux de thèse, répondent à la problématique liée à la sécurité incendie des bâtiments ventilés naturellement, et notamment au comportement des fumées chaudes lorsqu’elles interagissent avec le vent. Le premier chapitre concerne la mise en exergue de la problématique bâtimentaire, au travers de la présentation des moteurs de la ventilation naturelle, d’une analyse règlementaire croisée sécurité incendie / confort thermique, et de multiples retours d’expériences. La nécessité d’étudier les régimes d’écoulement interne lorsque le vent interagit avec la fumée est mise en évidence. Ainsi, dans le second chapitre, les verrous scientifiques, associés à l’identification des régimes d’écoulement en convection mixte, sont soulevés à l’aide d’une analyse de la littérature. Dans le troisième chapitre, nous nous intéressons à la caractérisation des régimes d’écoulement internes lorsque le vent oppose le tirage thermique dans un volume contenant une source constante générant les forces de flottabilité. Une expérimentation densimétrique, air/hélium, à échelle réduite est proposée. Trois régimes d’écoulement internes stables sont mis en évidence. Les transitions entre ces régimes sont caractérisées par une loi puissance, mettant en jeu le nombre de Froude, relatif à la source générant les forces de flottabilité, et le rapport entre la pression dynamique de la source et celle du vent. Dans le quatrième chapitre, ces régimes sont également identifiés, expérimentalement et numériquement, lors de la vidange de fluide léger lorsque le vent oppose le tirage thermique. Une relation entre le nombre de Richardson et un temps de vidange caractéristique est identifiée. L’étude numérique nous permet d’analyser des dynamiques particulières de vidange de manière quantitative. Dans la dernière partie, les lois de transitions entre régimes d’écoulement permettent d’introduire un indicateur de sécurité dépendant des conditions de vent. Une méthode d’analyse, qui considère à la fois la sécurité et le confort, est alors proposée pour éviter les conflits mis en avant dans les retours d’expériences du chapitre 1
Distribution et Décentralisation - Vingt-sixièmes journées francophones sur les systèmes multi-agents, JFSMA 2018, Métabief, France
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Blow Your Nose, Shrimp! Unexpectedly Dense Bacterial Communities Occur on the Antennae and Antennules of Hydrothermal Vent Shrimp
No full textInternational audienceIn crustaceans, as in other animals, perception of environmental cues is of key importance for a wide range of interactions with the environment and congeners. Chemoreception involves mainly the antennae and antennules, which carry sensilla that detect water-borne chemicals. The functional importance of these as exchange surfaces in the shrimp's sensory perception requires them to remain free of any microorganism and deposit that could impair the fixation of odorant molecules on sensory neurons. We report here the occurrence of an unexpected dense bacterial colonization on surface of the antennae and antennules of four hydrothermal vent shrimp species. Microscopic observation, qPCR and 16S rRNA barcoding reveal the abundance, diversity and taxonomic composition of these bacterial communities, that are compared with those found on a related coastal shrimp. Bacterial abundances vary among species. Bacteria are almost absent in coastal shrimp, meanwhile they fully cover the antennal flagella in some hydrothermal vent species. Epsilon-and Gammaproteobacteria dominate the hydrothermal shrimp-associated communities, whereas Alphaproteobacteria and Bacteroidetes are dominant in the coastal ones. Bacteria associated with vent shrimp species are most similar to known chemoautotrophic sulfur-oxidizers. Potential roles of these bacteria on the hydrothermal shrimp antennae and antennules and on sensory functions are discussed
New insights into early and late onset subgroups of preeclampsia from longitudinal versus cross-sectional analysis of urinary inositol-phosphoglycan P-Type
No full textInternational audienceMost pre-eclampsia (PE) studies have used cross-sectional data to derive conclusions regarding the pathophysiology of the condition. This has led to the concept that there exists early (34 weeks) disease according to gestational age at diagnosis. Survival time models have predicted that if the pregnancy was to continue indefinitely, all women would develop PE. In this study we have performed a longitudinal analysis of the urinary biomarker, inositol phosphoglycan (IPG), in a cohort of women giving birth in Mauritius (n-920). We have analysed the PE data in the traditional cross-sectional manner for n = 77 women who developed PE and also then looked at the longitudinal data for 71/77 of the same women. The data allows us to use longitudinal values to calculate a date of onset (first presence of biomarker in urine) and compare that to date of clinical diagnosis (cross sectional). We find two populations for both analysis consistent with an early and late stage subgroup. The calculated date of onset had subgroups (early and late) at 28.4 ± 0.41 weeks and 35.37 ± 0.26 weeks and for clinical date of diagnosis, 32.3 ± 0.59 weeks and 37.04 ± 0.62 weeks, respectively. The presence of the same biomarker in both subgroups and its ability to predict clinical onset 2–4 weeks prior to clinical diagnosis suggest that both groups may have similar aetiology.Urinary inositol phosphoglycan PPreeclampsi
Environmental and anthropogenic factors affecting the increasing occurrence of shark-human interactions around a fast-developing Indian Ocean island (vol 8, 2018)
No full textInternational audienceUnderstanding the environmental drivers of interactions between predators and humans is critical for public safety and management purposes. In the marine environment, this issue is exemplified by shark-human interactions. The annual shark bite incidence rate (SBIR) in La Réunion (Indian Ocean) is among the highest in the world (up to 1 event per 24,000 hours of surfing) and has experienced a 23-fold increase over the 2005-2016 period. Since 1988, 86% of shark bite events on surfers involved ocean-users off the leeward coast, where 96% of surfing activities took place. We modeled the SBIR as a function of environmental variables, including benthic substrate, sea temperature and period of day. The SBIR peaked in winter, during the afternoon and dramatically increased on coral substrate since the mid-2000s. Seasonal patterns of increasing SBIR followed similar fluctuations of large coastal shark occurrences (particularly the bull shark Carcharhinus leucas), consistent with the hypothesis that higher shark presence may result in an increasing likelihood of shark bite events. Potential contributing factors and adaptation of ocean-users to the increasing shark bite hazard are discussed. This interdisciplinary research contributes to a better understanding of shark-human interactions. The modeling method is relevant for wildlife hazard management in general
Kinematic evolution of the Mbakop Pan–African granitoids (western Cameroon domain): An integrated AMS and EBSD approach
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"In Gedichten verstecke ich mich": Günter Eichs poetische Selbstentwürfe.
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ASSESSMENT OF THE ADSORPTION OF AEROMONAS HYDROPHILA ON POLYTHENE IN SODIUM HYPOCHLORITE AND HYDROGEN PEROXIDE TREATED WATER
No full textInternational audienceA study was carried out on Aeromonas hydrophila adhesion to polythene fragment at different cell growth phases in aquatic microcosm. The main purpose of this study was to assess adsorption capacity, adsorption intensity and kinetics of Aeromonas hydrophila on polythene in sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) disinfected water. The mean abundance of adhered A. hydrophila sometimes reached 28 and 111CFU.cm-2 respectively in NaOCl and H2O2 treated water. The adsorption capacities of A. hydrophila cells fluctuated between 1 and 2.12x1057 and between 1 and 2.29x1027 adhered cells.cm-2 in NaOCl and H2O2 disinfected water respectively. The adsorption intensities of this bacterium ranged from -45.81 to 3.49x1019 and from 0.16 to 2.29x1027 respectively in NaOCl and H2O2 treated water. Adsorption capacity and adsorption intensity of A. hydrophila cells on polythene in NaOCl treated water were greater than that obtained in water disinfected with H2O2. Adhesion kinetics of A. hydrophila cells oscillated between 0.001 and 0.930 adhered cell.cm-2.h-1. Adsorption kinetics seem resulted from interactions between bacterial cells and substrates, and depended both on the fragment type and bacterial species. The values of A. hydrophila surface hydrophobicity fluctuated between 65.11 and 92.74% in NaOCl disinfected water and between 63.38 and 89.41% in H2O2 treated water. The mean values of contact angle ranged from 83.1±0.6 to 85.8±0.8°.Adhesion of A. hydrophila on polythene is mediated amongst others by cell growth phases, cell surface hydrophobicity, cell kinetic adhesion, adsorption capacity and adsorption intensity