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

Adsorption of polyelectrolytes from semi-dilute solutions on an oppositely charged surface

We propose a detailed description of the structure of the layer formed by polyelectrolyte chains adsorbed onto an oppositely charged surface in the semi-dilute regime. We combine the mean-field Poisson-Boltzmann-Edwards theory and the scaling functional theory to describe the variations of the monomer concentration, the electrostatic potential, and the local grafting density with the distance to the surface. For long polymers, we find that the effective charge of the decorated surface (surface plus adsorbed polyelectrolytes) can be much larger than the bare charge of the surface at low salt concentration, thus providing an experimental route to a "supercharging" type of effect.Comment: 14 pages, 6 figure

Low Temperature Gaseous Helium and very High Turbulence Experiments

Cryogenic gaseous helium gives access to extreme turbulent experimental conditions. The very high cooling helium flow rates available at CERN have been used to reach Reynolds numbers up to Re ~ 10**7 in a round jet experiment. First results are discussed

Polyelectrolyte Multilayering on a Charged Planar Surface

The adsorption of highly \textit{oppositely} charged flexible polyelectrolytes (PEs) on a charged planar substrate is investigated by means of Monte Carlo (MC) simulations. We study in detail the equilibrium structure of the first few PE layers. The influence of the chain length and of a (extra) non-electrostatic short range attraction between the polycations and the negatively charged substrate is considered. We show that the stability as well as the microstructure of the PE layers are especially sensitive to the strength of this latter interaction. Qualitative agreement is reached with some recent experiments.Comment: 28 pages; 11 (main) Figs - Revtex4 - Higher resolution Figs can be obtained upon request. To appear in Macromolecule

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,..

Writhing Photons and Berry Phases in Diffusive Wave Scattering

We study theoretically the polarization state of light in multiple scattering media in the limit of weak gradients in refractive index. Linearly polarized photons are randomly rotated due to the Berry phase associated with the scattering path. For circularly polarized light independent speckle patterns are found for the two helical states. The statistics of the geometric phase is related to the writhe distribution of semiflexible polymers such as DNA.Comment: 4 pages, 1 figur

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

A Cryogenic High-Reynolds Turbulence Experiment at CERN

The potential of cryogenic helium flows for studying high-Reynolds number turbulence in the laboratory has been recognised for a long time and implemented in several small-scale hydrodynamic experiments. With its large superconducting particle accelerators and detector magnets, CERN, the European Laboratory for Particle Physics, has become a major world center in helium cryogenics, with several large helium refrigerators having capacities up to 18 kW @ 4.5 K. Combining a small fraction of these resources with the expertise of three laboratories at the forefront of turbulence research, has led to the design, swift implementation, and successful operation of GReC (Grands Reynolds Cryogéniques) a large axisymmetric turbulent-jet experiment. With flow-rates up to 260 g/s of gaseous helium at ~ 5 K and atmospheric pressure, Reynolds numbers up to 107 have been achieved in a 4.6 m high, 1.4 m diameter cryostat. This paper presents the results of the first runs and describes the experimental set-up comprehensively equipped with "hot" wire micro-anemometers, acoustic scattering vorticity measurements and a large-bandwidth data acquisition system

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