Polyethylene glycol and prevalence of colorectal adenomas : Population-based study of 1165 patients undergoing colonoscopy

Background and aim — Dietary polyethylene glycol (PEG) is extraordinarily potent in the chemoprevention of experimental colon carcinogenesis. PEG is used to treat constipation in France and in the USA. French laxatives include Forlax® (PEG4000), Movicol® and Transipeg® (PEG3350), and Idrocol® (pluronic F68). This study tests the hypothesis that use of a PEG-based laxative might reduce the prevalence of colorectal tumors. Methods — In this population-based study, consecutive patients attending for routine total colonoscopy were enrolled during four months by the gastroenterologists of Indre-et-Loire. They were asked if they had previously taken a laxative or a NSAID. Age, gender, previous polyps, family history of colorectal cancer, constipation, digestive symptoms were also recorded. Tumors found during colonoscopy were categorized histologically. Results — Records from 1165 patients fulfilled the inclusion criteria, 607 women and 498 men, mean age 58.3. Among those, 813 had no tumor, 329 had adenomas, and 23 had carcinomas. In a univariate analysis, older age, male gender, lack of digestive symptom, and previous polyps were more common in patients with colorectal tumors. In contrast, previous Forlax® intake was more common in tumor-free patients (odds ratio (OR) any use/no use, 0.52; 95% confidence interval, 0.27-0.94). More people used Forlax®, which contains a higher dose of PEG than the other PEGlaxatives, whose ORs were smaller than one, but did not reach significance. In multivariate analysis, older age and male gender were associated with higher risk, and NSAIDs use with lower risk, of colorectal tumors. Conclusion — Forlax® users had a halved risk of colorectal tumors in univariate analysis, which suggests that PEG may prevent carcinogenesis

Assessing the variability in the relationship between the particulate backscattering coefficient and the chlorophyll a concentration from a global Biogeochemical-Argo database

Characterizing phytoplankton distribution and dynamics in the world's open oceans requires in situ observations over a broad range of space and time scales. In addition to temperature/salinity measurements, Biogeochemical-Argo (BGC-Argo) profiling floats are capable of autonomously observing at high frequency bio-optical properties such as the chlorophyll fluorescence, a proxy of the chlorophyll a concentration (Chla), the particulate backscattering coefficient (bbp), a proxy of the stock of particulate organic carbon, and the light available for photosynthesis. We analyzed an unprecedented BGC-Argo database of more than 8,500 multi-variable profiles collected in various oceanic conditions, from subpolar waters to subtropical gyres. Our objective is to refine previously established Chla vs bbp relationships and gain insights into the sources of vertical, seasonal and regional variability in this relationship. Despite some nuances in the relationship considering one or another water column layer or region, a general covariation occurs at a global scale. We distinguish two main contrasted situations: (1) concomitant changes in Chla and bbp that correspond to actual variations in phytoplankton biomass, e.g. in subpolar regimes; (2) a decoupling between the two variables attributed to photoacclimation or changes in the relative abundance of non-algal particles, e.g. in subtropical regimes. The variability in the bbp:Chla ratio in the surface layer appears to be essentially influenced by the type of particles and photoacclimation processes. The dense BGC-Argo database helps identifying the spatial and temporal scales at which this ratio is predominantly driven by one or the other of these two factors

Genome-wide analysis of Brucella melitensis genes required throughout intranasal infection in mice

Brucellae are facultative intracellular Gram-negative coccobacilli that chronically infect various mammals and cause brucellosis. Human brucellosis is among the most common bacterial zoonoses and the vast majority of cases are attributed to B .melitensis .Using transposon sequencing (Tn-seq) analysis, we showed that among 3369 predicted genes of the B .melitensis genome, 861 are required for optimal growth in rich medium and 186 additional genes appeared necessary for survival of B .melitensis in RAW 264.7 macrophages in vitro .As the mucosal immune system represents the first defense against Brucella infection, we investigated the early phase of pulmonary infection in mice. In situ analysis at the single cell level indicates a succession of killing and growth phases, followed by heterogenous proliferation of B .melitensis in alveolar macrophages during the first 48 hours of infection. Tn-seq analysis identified 94 additional genes that are required for survival in the lung at 48 hours post infection. Among them, 42 genes are common to RAW 264.7 macrophages and the lung conditions, including the T4SS and purine synthesis genes. But 52 genes are not identified in RAW 264.7 macrophages, including genes implicated in lipopolysaccharide (LPS) biosynthesis, methionine transport, tryptophan synthesis as well as fatty acid and carbohydrate metabolism. Interestingly, genes implicated in LPS synthesis and β oxidation of fatty acids are no longer required in Interleukin (IL)-17RA -/- mice and asthmatic mice, respectively. This demonstrates that the immune status determines which genes are required for optimal survival and growth of B .melitensis in vivo .info:eu-repo/semantics/publishe

Bio-optical relationships in the global ocean and biogeochemical functioning of subsurface chlorophyll maxima in the Mediterranean Sea, based on measurements of the BGC-Argo profiling floats

Cette thèse a pour objectif principal de mieux appréhender la dynamique spatio-temporelle et verticale de la biomasse phytoplanctonique dans l’océan ouvert. Dans un premier temps, nous avons étudié la variabilité de la relation entre le coefficient de rétrodiffusion particulaire (bbp), un estimateur bio-optique du carbone organique particulaire, et la concentration en chlorophylle a (Chla) à l’échelle globale. Dans les régimes subpolaires, des changements concomitants de Chla et bbp correspondent à des variations de la biomasse du phytoplancton. Au contraire, dans les régimes subtropicaux oligotrophes, un découplage entre les deux variables peut être attribué aux processus de photoacclimation du phytoplancton ou à un changement de l'abondance relative des particules non algales au sein de l’assemblage particulaire. La Mer Méditerranée constitue, quant à elle, un régime intermédiaire à ces deux situations extrêmes. En utilisant le couplage entre bbp et Chla nous avons, dans un second temps, analysé la dynamique saisonnière et régionale des maxima profonds de Chla (SCMs) à l’échelle du bassin méditerranéen en développant notamment une classification des profils verticaux de Chla et de bbp. En Méditerranée orientale, des SCMs correspondant à une augmentation de la Chla intracellulaire des cellules phytoplanctoniques (photoacclimatation) ont été identifiés. Au contraire, des SCMs résultant d’une réelle augmentation de la biomasse carbonée en profondeur (SBMs) ont été observés de manière récurrente en Méditerranée occidentale. Suivant la piste d’une contribution potentiellement significative des SCMs à la production de carbone dans l’océan global, la production communautaire brute dans la couche de subsurface a été, dans un troisième temps, quantifiée. Pour cela, une méthode bio-optique d’estimation de la production basée sur le cycle diurne des propriétés bio-optiques a été utilisée dans deux régions distinctes de la Méditerranée durant la période estivale oligotrophe. Nous avons ainsi mis en évidence une importante contribution des SCMs à la production totale réalisée dans la couche productive, pouvant atteindre plus de 40% en Méditerranée occidentale.The main objective of this thesis is to improve our understanding of the spatio-temporal and vertical variability of phytoplankton biomass in the open ocean. First, we investigated the variability of the relationship between the particulate backscattering coefficient (bbp), a bio-optical proxy of the particulate organic carbon, and the chlorophyll a concentration (Chla) at a global scale. In subpolar regimes, concomitant changes in Chla and bbp correspond to variations in phytoplankton biomass. In contrast, in subtropical regimes, a decoupling between the two variables was attributed to photoacclimation processes or a change in the relative abundance of non-algal particles to the particulate assemblage. The Mediterranean Sea stands as an intermediate regime between these two end-members. Next, we analysed the seasonal and regional dynamics of subsurface Chla maxima (SCMs) in the Mediterranean basin by developing a classification of the vertical profiles of Chla and bbp. In the Eastern Mediterranean, SCMs corresponded to an increase in the intracellular Chla induced by photoacclimation of phytoplankton cells. However, in the Western basin of the Mediterranean Sea SCMs corresponded to an actual increase in carbon biomass at depth (SBMs). Lastly, we investigated the potentially significant contribution of SCMs to carbon production, by quantifying the gross community production in the subsurface layer. A method based on the diurnal cycle of bio-optical properties was used in order to estimate production in two distinct regions of the Mediterranean Sea during the oligotrophic season. Our study revealed that SCMs might contribute over 40% of the depth-integrated production in some areas, thereby suggesting the potentially important biogeochemical role of SCMs

Étude des relations bio-optiques dans l’océan global et du fonctionnement biogéochimique des maxima de subsurface de chlorophylle en Méditerranée à partir des mesures des flotteurs profileurs BGC-Argo

The main objective of this thesis is to improve our understanding of the spatio-temporal and vertical variability of phytoplankton biomass in the open ocean. First, we investigated the variability of the relationship between the particulate backscattering coefficient (bbp), a bio-optical proxy of the particulate organic carbon, and the chlorophyll a concentration (Chla) at a global scale. In subpolar regimes, concomitant changes in Chla and bbp correspond to variations in phytoplankton biomass. In contrast, in subtropical regimes, a decoupling between the two variables was attributed to photoacclimation processes or a change in the relative abundance of non-algal particles to the particulate assemblage. The Mediterranean Sea stands as an intermediate regime between these two end-members. Next, we analysed the seasonal and regional dynamics of subsurface Chla maxima (SCMs) in the Mediterranean basin by developing a classification of the vertical profiles of Chla and bbp. In the Eastern Mediterranean, SCMs corresponded to an increase in the intracellular Chla induced by photoacclimation of phytoplankton cells. However, in the Western basin of the Mediterranean Sea SCMs corresponded to an actual increase in carbon biomass at depth (SBMs). Lastly, we investigated the potentially significant contribution of SCMs to carbon production, by quantifying the gross community production in the subsurface layer. A method based on the diurnal cycle of bio-optical properties was used in order to estimate production in two distinct regions of the Mediterranean Sea during the oligotrophic season. Our study revealed that SCMs might contribute over 40% of the depth-integrated production in some areas, thereby suggesting the potentially important biogeochemical role of SCMs.Cette thèse a pour objectif principal de mieux appréhender la dynamique spatio-temporelle et verticale de la biomasse phytoplanctonique dans l’océan ouvert. Dans un premier temps, nous avons étudié la variabilité de la relation entre le coefficient de rétrodiffusion particulaire (bbp), un estimateur bio-optique du carbone organique particulaire, et la concentration en chlorophylle a (Chla) à l’échelle globale. Dans les régimes subpolaires, des changements concomitants de Chla et bbp correspondent à des variations de la biomasse du phytoplancton. Au contraire, dans les régimes subtropicaux oligotrophes, un découplage entre les deux variables peut être attribué aux processus de photoacclimation du phytoplancton ou à un changement de l'abondance relative des particules non algales au sein de l’assemblage particulaire. La Mer Méditerranée constitue, quant à elle, un régime intermédiaire à ces deux situations extrêmes. En utilisant le couplage entre bbp et Chla nous avons, dans un second temps, analysé la dynamique saisonnière et régionale des maxima profonds de Chla (SCMs) à l’échelle du bassin méditerranéen en développant notamment une classification des profils verticaux de Chla et de bbp. En Méditerranée orientale, des SCMs correspondant à une augmentation de la Chla intracellulaire des cellules phytoplanctoniques (photoacclimatation) ont été identifiés. Au contraire, des SCMs résultant d’une réelle augmentation de la biomasse carbonée en profondeur (SBMs) ont été observés de manière récurrente en Méditerranée occidentale. Suivant la piste d’une contribution potentiellement significative des SCMs à la production de carbone dans l’océan global, la production communautaire brute dans la couche de subsurface a été, dans un troisième temps, quantifiée. Pour cela, une méthode bio-optique d’estimation de la production basée sur le cycle diurne des propriétés bio-optiques a été utilisée dans deux régions distinctes de la Méditerranée durant la période estivale oligotrophe. Nous avons ainsi mis en évidence une importante contribution des SCMs à la production totale réalisée dans la couche productive, pouvant atteindre plus de 40% en Méditerranée occidentale

Increase in Soil Macroporosity managed with Winter Ploughing - a preliminary results

Measurement of soil water retention capacity by the conventional pressure plate technique always gives a substantial view of soil porosity distribution. The structural orientation is observed in the beginning (higher water retention at 9.8 to 98 hPa water head pressure indicates greater proportion of macroporosity) of the soil moisture characteristic curve obtained from the water retention measurement. Since, tillage practices generally increase soil porosity, the correlation between soil hydraulics and porosity distribution would expect to be different for different tillage systems. In general, macroporosity increase with the adoption of conservative tillage or no tillage system but the changes can be varied with the seasonal variation. In our study, winter ploughing retains more water at the range of 9.8 to 98 hPa than Strip tillage, No-till residues in and No-till residues out. So, we can conclude that there is certainly increase in macroporosity in ploughing than other conservation practices of reduced tillage and no tillage

Evaluation of soil structural changes through macroscopic and microscopic measurement

The heterogeneity of soil structure and pore size distribution are highly influenced by external factors like tillage systems and other agricultural management practices. However, changes in soil hydrodynamic behavior are not fully understood and are still under research. Also, researchers have explained the impact of tillage practices on soil hydraulic properties related to pore size distribution, connectivity and orientation are involved but the characterization of these modifications and consequences remains a challenge. Furthermore, the relation between macroscopic measurements and microscopic investigation of the soil structure remains scarce. Recently, X-ray tomography (X- μCT) has been used in order to characterize changes in soil pore size distribution in various contexts and the method is able to link microtomography information to hydrodynamic measurement. In our study, X-μCT has been used in order to characterize changes in soil pore system. Since, tomography does not count most of the micropores, Richards’ pressure plate and evaporation method was also combined to get complete range of pore size distribution. We found good match between evaporation data with X-μCT at the macropore scale and evaporation data with pressure plate method at micropore scale. X-μCT data refines retention and hydraulic curves near saturation where Richards’ data alone can lead to numerous sets of fitted parameters. On the otherhand, evaporation data (Hyprop apparatus ©) provide comparable datasets with X-μCT. Combining micro and macroscopic measurements allows us to validate X-μCT information, which is otherwise not so obvious.Soil infrastructure evolution and its effect on water transfer processes under contrasted tillage system