In vitro effects of nanoparticles on renal cells

<p>Abstract</p> <p>Background</p> <p>The ability of nanoparticles to cross the lung-blood barrier suggests that they may translocate to blood and to targets distant from their portal of entry. Nevertheless, nanotoxicity in organs has received little attention. The purpose of this study was to evaluate nanotoxicity in renal cells using <it>in vitro </it>models. Various carbon black (CB) (FW2–13 nm, Printex60-21 nm and LB101-95 nm) and titanium dioxide (TiO₂-15 and TiO₂-50 nm) nanoparticles were characterized on size by electron microscopy. We evaluated theirs effects on glomerular mesangial (IP15) and epithelial proximal tubular (LLC-PK₁) renal cells, using light microscopy, WST-1 assay, immunofluorescence labeling and DCFH-DA for reactive oxygen species (ROS) assay.</p> <p>Results</p> <p>Nanoparticles induced a variety of cell responses. On both IP15 and LLC-PK₁cells, the smallest FW2 NP was found to be the most cytotoxic with classic dose-behavior. For the other NPs tested, different cytotoxic profiles were found, with LLC-PK₁cells being more sensitive than IP15 cells. Exposure to FW2 NPs, evidenced in our experiments as the most cytotoxic particle type, significantly enhanced production of ROS in both IP15 and LLC-PK₁cells. Immunofluorescence microscopy using latex beads indicated that depending on their size, the cells internalized particles, which accumulated in the cell cytoplasm. Additionally using transmission electronic microscope micrographs show nanoparticles inside the cells and trapped in vesicles.</p> <p>Conclusion</p> <p>The present data constitute the first step towards determining <it>in vitro </it>dose effect of manufactured CB and TiO₂NPs in renal cells. Cytotoxicological assays using epithelial tubular and glomerular mesangial cell lines rapidly provide information and demonstrated that NP materials exhibit varying degrees of cytotoxicity. It seems clear that <it>in vitro </it>cellular systems will need to be further developed, standardized and validated (relative to <it>in vivo </it>effects) in order to provide useful screening data about the relative toxicity of nanoparticles.</p

Hepatitis E Virus infection in HIV-infected patients with elevated serum transaminases levels

Increases in aminotransferases levels are frequently encountered in HIV-positive patients and often remain unexplained. The role in this setting and natural history of hepatitis E in HIV-infected patients are unknown. The aim of the study was to assess HEV infection in HIV-infected patients attending a Parisian hospital, with a current or previous cryptogenic hepatitis.191 plasma samples collected from 108 HIV-infected patients with elevated aminotransferases levels were retrospectively tested for the presence of hepatitis E virus (HEV) infection markers: anti-HEV IgM antibodies, anti-HEV IgG antibodies, anti-HEV IgG avidity index and plasma HEV RNA.One acute infection, documented by positive tests for anti-HEV IgM antibody, low anti-HEV IgG avidity index and plasma HEV RNA (genotype 3e), and three past infections were diagnosed, without any observed case of persistent infection. The acute hepatitis was benign and resolved spontaneously within two weeks. This infection was probably contracted locally. Acute HEV hepatitis can occur in HIV-infected patients but rarely explains cryptogenic hepatitis, at least in an urban HIV population, regardless geographic origin and CD4 counts

Physicochemical characteristics and bronchial epithelial cell cytotoxicity of Folpan 80 WG® and Myco 500®, two commercial forms of folpet

<p>Abstract</p> <p>Background</p> <p>Pesticides, in particular folpet, have been found in rural and urban air in France in the past few years. Folpet is a contact fungicide and has been widely used for the past 50 years in vineyards in France. Slightly water-soluble and mostly present as particles in the environment, it has been measured at average concentration of 40.1 μg/m³during its spraying, 0.16–1.2 μg/m³in rural air and around 0.01 μg/m³in urban air, potentially exposing both the workers and the general population. However, no study on its penetration by inhalation and on its respiratory toxicity has been published. The objective of this study was to determine the physicochemical characteristics of folpet particles (morphology, granulometry, stability) in its commercial forms under their typical application conditions. Moreover, the cytotoxic effect of these particles and the generation of reactive oxygen species were assessed <it>in vitro </it>on respiratory cells.</p> <p>Results</p> <p>Granulometry of two commercial forms of folpet (Folpan 80WG^®and Myco 500^®) under their typical application conditions showed that the majority of the particles (>75%) had a size under 5 μm, and therefore could be inhaled by humans. These particles were relatively stable over time: more than 75% of folpet remained in the particle suspension after 30 days under the typical application conditions. The inhibitory concentration (IC₅₀) on human bronchial epithelial cells (16HBE14o-) was found to be between 2.89 and 5.11 μg/cm²for folpet commercial products after 24 h of exposure. Folpet degradation products and vehicles of Folpan 80 WG^®did not show any cytotoxicity at tested concentrations. At non-cytotoxic and subtoxic concentrations, Folpan 80 WG^®was found to increase DCFH-DA fluorescence.</p> <p>Conclusion</p> <p>These results show that the particles of commercial forms of folpet are relatively stable over time. Particles could be easily inhaled by humans, could reach the conducting airways and are cytotoxic to respiratory cells in vitro. Folpet particles may mediate its toxicity directly or indirectly through ROS-mediated alterations. These data constitute the first step towards the risk assessment of folpet particles by inhalation for human health. This work confirms the need for further studies on the effect of environmental pesticides on the respiratory system.</p

Applications du traitement d'images développées au laboratoire Exploration de Total C.F.P. Image analysis and image treatment applications developed in the Exploration laboratories of Total C.F.P

Sellier Elisabeth. Applications du traitement d'images développées au laboratoire Exploration de Total C.F.P. Image analysis and image treatment applications developed in the Exploration laboratories of Total C.F.P. In: Sciences Géologiques. Bulletin, tome 41, n°2, 1988. Traitements d'images et objets géologiques. pp. 241-246

Impact of Electrostatics on the Adsorption of Microgels at the Interface of Pickering Emulsions

The importance of electrostatics on microgel adsorption at a liquid interface is studied, as well as its consequence on emulsion stabilization. In this work, poly(Nisopropylacrylamide) (pNIPAM) microgels bearing different numbers of charges and various distribution profiles are studied, both in solution and at the oil−water interface of emulsion drops. Charged microgels are compared to neutral ones, and electrostatic interactions are screened by adding salt to the aqueous solution. In solution, electrostatics has a significant impact on microgel swelling, as induced by the osmotic pressure exerted by mobile counterions in the gel network. At the interface of drops, microgels pack in a hexagonal array, whose lattice parameter is independent of the number of charges and range of electrostatic interactions. Microgel morphology and packing are ruled only by the adsorption of the pNIPAM chain at the interface. Conversely, decreasing the charge density of microgels by the protonation of the carboxylic groups leads to unstable emulsions, possibly as a result of the impact of hydrogen bonding on microgel deformability

Hydrogen sorption properties of magnesium particles decorated with metallic nanoparticles as catalyst

Both hydrogen absorption and desorption, in the range 200–300 and 260–330 °C, respectively, of magnesium particles decorated with metallic nanoplots elaborated by Supercritical Fluid Chemical process are studied. The absorption data are fitted using Avrami–Erofeev model to first order. Unexpectively, magnesium decorated with copper nanoparticles lead to relatively high rates of sorption (absorption rate at 300 °C and desorption rate at 330 °C of about 0.4 wt%H min−1) but its activation energy remains high (70 kJ mol−1). The presence at the interface of MgCu2, acting as a chemical link between the nanoCu and the magnesium particle could be responsible for such behavior. Palladium nanoparticles react with magnesium during cycling so that the catalytic effect is decreasing with cycling and finally does not exist anymore after 10 cycles. Finally, the best results are obtained for the nanocomposite of magnesium with nickel nanoparticles for which the sorption rates are comparable with the ones obtained for optimized BM samples with catalysts, but with a lower energy cost of the process

Modification of n-Si characteristics by annealing and cooling at different rates

he effect of annealing of the n-Si semiconductor on its characteristics in photoelectrochemical systems has been investigated. The annealing improved the dark current density vs. potential plots. The surface was improved by annealing, as manifested by SEM results. The effect of the cooling rate on preheated n-Si wafers was also investigated. It was found that the slowly cooled electrodes gave better dark current density vs. potential plots, for samples annealed at lower than 550°C. For samples annealed at higher temperatures, quenching gave better dark-current density vs. potential plots. SEM measurements showed parallel results to these findings. Enhanced surface textures were observed for slowly cooled wafers from temperatures below 550°C. Samples quenched from temperatures above 550°C showed better surfaces than slowly cooled counterparts

Water-in-Oil Emulsions Stabilized by Water-Dispersible Poly(N-isopropylacrylamide) Microgels: Understanding Anti-Finkle Behavior

Emulsions were prepared using poly(N-isopropylacrylamide) microgels as thermoresponsive stabilizers. The latter are well-known for their sensitivity to temperature: they are swollen by water below the socalled volume phase transition temperature (VPTT = 33°C) and shrink when heated above it. Most of the studies reported in the literature reveal that the corresponding emulsions are of the oil-in-water type (O/W) and undergo fast destabilization upon warming above the VPTT. In the present study, whereas O/W emulsions were obtained with a wide panel of oils of variable polarity and were all thermoresponsive, water-in-oil (W/O) emulsions were found only in the presence of fatty alcohols and did not exhibit any thermal sensitivity. To understand the peculiar behavior of emulsions based on fatty alcohols, we investigated the organization of microgels at the oil-water interface and we studied the interactions of pNIPAM microgels with octanol. By combining several microscopy methods and by exploiting the limited coalescence process, we provided evidence that W/O emulsions are stabilized by multilayers of nondeformed microgels located inside the aqueous drops. Such behavior is in contradiction with the empirical Finkle rule stating that the continuous phase of the preferred emulsion is the one in which the stabilizer is preferentially dispersed. The study of microgels in nonemulsified binary water/octanol systems revealed that octanol diffused through the aqueous phase and was incorporated in the microgels. Thus, W/O emulsions were stabilized by microgels whose properties were substantially different from the native ones. In particular, after octanol uptake, they were no longer thermoresponsive, which explained the loss of responsiveness of the corresponding W/O emulsions. Finally, we showed that the incorporation of octanol modified the interfacial properties of the microgels: the higher the octanol uptake before emulsification, the lower the amount of particles in direct contact with the interface. The multilayer arrangement was thus necessary to ensure efficient stabilization against coalescence, as it increased interface cohesiveness. We discussed the origin of this counterexample of the Finkle's rule