Chemoprevention of aberrant crypt foci in the colon of rats by dietary onion

Onion intake might reduce the risk of colorectal cancer, according to epidemiology. However, Femia showed in 2003 that diets with a 20% onion intake increase carcinogenesis in rats. We speculated this dose was too high. Prevention of initiation was thus tested in 60 rats given a 5% dried onion diet or AIN76 diet, and initiated 12 days later with azoxymethane (AOM, 1 × 20 mg/kg i.p.), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ, 2 × 200 mg/kg p.o.), or N-nitroso–N–methylurea (2 × 50 mg/kg p.o.). Prevention of promotion was tested in 38 rats given AOM, then randomised to: AIN76 diet; 5% onion diet; phytochemicals diet (supplemented with propyl-disulfide, quercetine-glycosides and oligofructose); 1% pluronic F68 diet (a potent chemopreventive PEG-like block-polymer, used as a positive control). Aberrant crypt foci (ACF) were scored 30 days (initiation) or 100 days (promotion) after carcinogen injection. The onion diet given during initiation reduced the number of AOM-induced ACF (60 versus 86, p = 0.03), and the size of IQ-induced ACF (1.33 versus 1.97, p = 0.02). Given post-initiation, the onion diet reduced the number of ACF (34 versus 59, p = 0.008) and of large ACF (6 versus 15, p = 0.02). Phytochemicals diet and pluronic diet reduced ACF growth similarly. Data show that a 5% onion diet reduced carcinogenesis during initiation and promotion stages, and suggest this chemoprevention is due to known phytochemicals

Orléans – 21 rue Saint-Étienne

Le diagnostic archéologique du 21 rue Saint-Étienne à Orléans s’est déroulé du 23 octobre au 10 novembre 2017. Deux sondages ont été ouverts au centre et à l’ouest de la parcelle prescrite. L’emprise de l’opération se situe sur le rebord du plateau calcaire orléanais, à une altitude d’environ 109,50 m NGF. Sans avoir atteint le substrat, l’occupation la plus ancienne mise au jour, entre 3,50 et 3,70 m sous le sol actuel, est datée des ier-iie s. Elle est caractérisée par un angle de bâtiment,..

Micromechanics of Surface-Grafted Hyaluronic Acid Gels

International audienceTo design models of tissue surfaces, films of soft gels of hyaluronic acid (HA) (a ubiquitous constituent of the extracellular matrix) are covalently grafted to glass substrates functionalized with aminosilane monolayers. Gelation is achieved by coupling of carboxyl groups of HA through carbodiimide. The elasticity of the gel is controlled through the HA concentration. The magnetic bead microrheometry and colloidal bead deformation field mapping techniques are applied to measure the surface viscoelastic moduli and the effective Young moduli of the HA gel as a function of the gel density. For this purpose, magnetic beads and nonmagnetic beads are coupled to the surface of the HA films. Soft homogeneous films exhibiting Young elastic moduli between 3 and 250 Pa were generated. The shear deformation field induced by tangential force pulses applied to the magnetic beads is measured and analyzed in terms of the theory of elastic deformation of half-spaces by local forces. An unconventional vortex-deformation field is observed for gel film thicknesses of several hundred micrometers, which is attributed to the nonlinear elasticity of the gels. We finally show that amoeba-like cells of the slime mold Dictyostelium discoideum spontaneously adhere to the HA film, while fibroblast adhesion can be mediated through coupling fibronectin to the surface

TALE Factors Poise Promoters for Activation by Hox Proteins

SummaryHox proteins form complexes with TALE cofactors from the Pbx and Prep/Meis families to control transcription, but it remains unclear how Hox:TALE complexes function. Examining a Hoxb1b:TALE complex that regulates zebrafish hoxb1a transcription, we find maternally deposited TALE proteins at the hoxb1a promoter already during blastula stages. These TALE factors recruit histone-modifying enzymes to promote an active chromatin profile at the hoxb1a promoter and also recruit RNA polymerase II (RNAPII) and P-TEFb. However, in the presence of TALE factors, RNAPII remains phosphorylated on serine 5 and hoxb1a transcription is inefficient. By gastrula stages, Hoxb1b binds together with TALE factors to the hoxb1a promoter. This triggers P-TEFb-mediated transitioning of RNAPII to the serine 2-phosphorylated form and efficient hoxb1a transcription. We conclude that TALE factors access promoters during early embryogenesis to poise them for activation but that Hox proteins are required to trigger efficient transcription

L'oignon protège-t-il le rat contre la concérogenèse du colon ? Effet sur les foyers des cryptes aberrantes

De nombreux aliments d'origine végétale sont associés à une diminution du risque de cancer colorectal. C'est l'oignon qui nous a intéressés dans cette étude. Après avoir présenté les données actuelles sur les relations entre l'alimentation et le cancer, puis sur les propriétés de l'oignon, et celles de certains de ses constituants, cette thèse présente une étude expérimentale. Celle-ci a permis de vérifier l'hypothèse d'un rôle protecteur de l'oignon contre la cancérogenèse colique chez le rat. Dans une première expérience, nous avons testé l'effet d'un régime à 5% de poudre d'oignon déshydraté sur l'initiation de lésions pré-cancéreuses, les foyers de cryptes aberrantes (ACF). Ce régime a fait effectivement diminuer le nombre d'ACF total et le nombre de cryptes par ACF chez les rats lors d'initiation par l'azoxyméthane. Le régime contenant de l'oignon a également fait diminuer le nombre de cryptes par ACF chez les rats lors d'initiation parla 2-amino-3-méthyl 2-amino-3-méthyl-3H-imidazo-[4,5-f]-quinoline. Dans une deuxième expérience, nous avons testé chez le rat l'effet d'un régime à 5% de poudre d'oignon déshydraté, d'un régime à 5% d'un mélange de microconstituants de l'oignon, et d'un régime à 1% de pluronic F68, un polymère protecteur, sur la promotion des ACF initiés par l'azoxyméthane. Les résultats ont été significatifs : - le nombre total d'ACF a été réduit chez les rats ayant consommé le régime à base d'oignon. - le nombre de cryptes par ACF a été réduit chez les rats ayant consommé le régime à base de pluronic. - le nombre de gros ACF, de quatre cryptes et plus, a été réduit chez les rats traités par les trois régimes (oignon, microconstituants et pluronic) par rapport aux rats témoins. L'oignon a donc bien un rôle protecteur sur les phases d'initiation et de promotion de la cancérogenèse colique chez le rat, et semble donc intéressant dans le cadre d'un régime équilibré pour prévenir le cancer du colon chez l'Homme

Making Deliberation Work: Testing Theories of Deliberation

In this project, I address three questions concerning the design and implementation of deliberative institutions in the United States. First, how do institutional choices in recruitment affect the pool of willing participants? I argue that people will express greater interest in taking part in deliberation when it is presented in a nonpartisan manner. Using a series of online experiments, I demonstrate that invitations from nonpartisan conveners illicit interest from politically diverse groups. Second, what factors affect participants' behavior during deliberative sessions? A common critique of deliberative democracy is that it cannot overcome the well-documented biases in people's information processing. I propose a theory based in motivated reasoning, arguing that reason-giving rules in deliberative session promotes accuracy-motivated reasoning over directionally-motivated reasoning. Using experimental deliberative sessions varying the reason-giving rules, I find that reason-giving results in higher discourse quality, and decreases opinion polarization. Third, how do structural factors affect spillover effects from deliberative sessions? While it is unreasonable to expect full citizenry participation in any deliberation effort, those who do not participate may experience some of the benefits through their social networks. For this portion of the project, I use data from the experimental sessions to better understand the multiplier effects from deliberative sessions. This project addresses underdeveloped areas within the political science literature, drawing upon work on participation, information processing, and discussion networks; it also provides a much needed link to deliberative practitioners, who rarely test myriad assumptions when designing and conducting deliberative institutions

Effects of substrate annealing on the gold-catalyzed growth of ZnO nanostructures

The effects of thermal substrate pretreatment on the growth of Au-catalyzed ZnO nanostructures by pulsed laser deposition are investigated. C-plane sapphire substrates are annealed prior to deposition of a thin Au layer. Subsequent ZnO growths on substrates annealed above 1,200°C resulted in a high density of nanosheets and nanowires, whereas lower temperatures led to low nanostructure densities. Separate Au film annealing experiments at 700°C showed little variation in the size and density of the Au catalyst droplets with substrate annealing temperature. The observed variation in the density of nanostructures is attributed to the number of surface nucleation sites on the substrate, leading to a competition between nucleation promoted by the Au catalyst and surface nucleation sites on the rougher surfaces annealed below 1,200°C

Anomalous permeation of the [P5W30O110 ]15- polyoxoanion in polyelectrolyte multilayer films

International audienceThe integration of polyoxoanions into functional thin films is of major interest to increase their use as catalysts or to provide new properties to the films. The incorporation of polyoxoanions in polyelectrolyte multilayer (PEM) films has been widely used for such aims. In most investigations, the polyoxoanions were used as a component of the layering process and there is only limited work investigating the interactions of polyoxoanions with preformed PEM films. Herein, we investigated the incorporation of the 30-tungsto-5-phosphate [P 5 W 30 O 110 ] 152 polyoxoanion into PEM films made from hyaluronic acid (HA) and poly(allylamine hydrochloride) (PAH) as a function of the polyoxoanion's concentration. Surprisingly, we found an increased amount of incorporated [P 5 W 30 O 110 ] 152 upon a decrease in its bulk concentration. Confocal Raman microscopy allowed us to investigate the concentration profile of the polyoxoanion across films of about 3 mm in thickness. Homogeneous distribution was only found for films fed with polyoxoanions at the lowest bulk concentration, namely 1.2 6 10 26 M, whereas the films fed with solutions at higher concentrations (1.2 6 10 24 M) showed local enrichment in POM at the film-solution interface. We explain the lower amount of incorporated polyoxoanion at high bulk concentration by the formation of a polyoxoanion-rich barrier reducing further diffusion of the anions in the deeper part of the films

Determination of structural parameters characterizing thin films by optical methods: A comparison between scanning angle reflectometry and optical waveguide lightmode spectroscopy

International audienceWe present a comparative study of the structural parameters characterizing thin macromolecular adsorbed films that are obtained from two optical techniques: optical waveguide lightmode spectroscopy ͑OWLS͒ and scanning angle reflectometry ͑SAR͒. We use polyelectrolyte multilayers and polyelectrolyte multilayers/protein films to perform this study. The comparison between the information obtained with the two methods is possible because the buildup of the polyelectrolyte multilayers is known to become substrate independent after the deposition of the first few polyelectrolyte layers. The analysis of the optical data requires usually to postulate a refractive index profile for the interface. Two profiles have been used: the homogeneous and isotropic monolayer and the bilayer profiles. When the refractive index profile of an adsorbed film is well approximated by a homogeneous and isotropic monolayer, as shown by using an analysis of the deposited films in terms of optical invariants, the two optical techniques lead to similar values for the film thickness and the optical mass. The situation is more complex in the case of the multilayers/protein films for which the calculated parameters can strongly depend upon the refractive index profile that is postulated to analyze the optical data. Whereas the optical mass and, to a lesser extent, the thickness seem fairly model independent for OWLS, they appear to be extremely sensitive to the model for SAR. For proteins deposited on top of the polyelectrolyte film, optical mass and protein thickness were found to be comparable when determined by OWLS and by SAR using the bilayer model. The data analysis of the SAR curves with the monolayer model leads to much larger and even physically unreasonable film thicknesses and optical masses. This was particularly noticeable for proteins having a large size ͑human serum albumin and fibrinogen͒, whereas both models lead to similar results for small sized proteins. By means of the different refractive index profiles, we show that great care must be taken in the physicochemical interpretation of the structural parameters determined by these optical techniques