Utilisation des techniques dégradatives pour l'étude des interactions entre pesticides et matières organiques des sols

National audienc

Functionalization of single- and multi-walled carbon nanotubes with cationic amphiphiles for plasmid DNA complexation and transfection

International audienceThe possibility of delivering DNA effi ciently to cells represents a crucial issue for the treatment of both genetic and acquired diseases. However, even although the effi ciency of non-viral transfection systems has improved in the last decade, none have yet proven to be suffi ciently effective in vivo. We report herein our results on the functionalization of single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) by two cationic amphiphiles (lipid RPR120535 and pyrenyl polyamine), their use for the complexation of plasmid DNA, and their efficiency in transfecting cells in vitro. The experiments have shown that the efficiency of transfection is higher when using SWNT instead of MWNT, and that transfection effi ciency is similar or slightly higher when using nanoplexes (SWNT/lipid RPR120535/DNA) instead of lipoplexes (lipid RPR120535/DNA) and several orders of magnitude higher than that of naked DNA. This study therefore shows both that the transfection is better when using SWNTs and that it is dependent on the nature of the amphiphilic molecules adsorbed on the nanotubes

Isolation and analysis of the non-hydrolysable fraction of a forest soil and an arable soil (Lacadée, southwest France)

International audienceRecent studies have pointed to the occurrence in soil organic matter of an insoluble macromolecular fraction, resistant to drastic alkali and acid hydrolysis. This non-hydrolysable fraction may contribute to the stable carbon pool in the soil and thus be important for the global carbon budget. We have developed a method to isolate such chemically resistant components, whilst ensuring complete elimination of the hydrolysable constituents of the organic matter but avoiding the formation of insoluble compounds via Maillard-type condensation reactions. Maize leaves, material especially susceptible to artefact formation, were used for this optimization. Several of the treatments that we tested, including the Klason lignin protocol, proved unsuitable. The most suitable protocol, by progressive hydrolysis with trifluoroacetic and hydrochloric acid, revealed a non-hydrolysable fraction in maize leaves accounting for about 5% by weight of the leaves and corresponding chiefly to lignin and condensed tannins. The protocol was applied to a forest soil and to the soil from an adjacent plot cleared 35 years ago and since cropped continuously with maize. The abundance, chemical composition and sources of the non-hydrolysable fraction of these two soils were determined by a combination of spectroscopy, pyrolysis and electron microscopy. This fraction accounted for about 6% of the total organic carbon of both soils; it contains aliphatic moieties, black carbon, melanoidins and, we think, condensed tannin

Drug‐induced peripheral oedema: An aetiology‐based review

International audienceMany drugs are responsible, through different mechanisms, for peripheral oedema. Severity is highly variable, ranging from slight oedema of the lower limbs to anasarca pictures as in the capillary leak syndrome. Although most often noninflammatory and bilateral, some drugs are associated with peripheral oedema that is readily erythematous (eg, pemetrexed) or unilateral (eg, sirolimus). Thus, drug‐induced peripheral oedema is underrecognized and misdiagnosed, frequently leading to a prescribing cascade. Four main mechanisms are involved, namely precapillary arteriolar vasodilation (vasodilatory oedema), sodium/water retention (renal oedema), lymphatic insufficiency (lymphedema) and increased capillary permeability (permeability oedema). The underlying mechanism has significant impact on treatment efficacy. The purpose of this review is to provide a comprehensive analysis of the main causative drugs by illustrating each pathophysiological mechanism and their management through an example of a drug

Dynamics and origin of the non-hydrolysable organic fraction in a forest and a cultivated temperate soil, as determined by isotopic and microscopic studies

International audienceWe isolated the non-hydrolysable macromolecular organic fraction (insoluble fraction resistant to drastic laboratory hydrolyses) from a temperate, loamy, forest soil (Lacadée, France) and from the soil of an adjacent plot cleared 35 years ago and continuously cropped with maize. The quantitative, morphological (light, scanning and transmission electron microscopy) and isotopic (bulk δ13C, individual compound δ13C and radiocarbon dating) features of these two non-hydrolysable fractions were determined and compared. It appeared that: (i) extensive degradation of the non-hydrolysable material inherited from the forest soil occurred upon cropping, revealing that its resistance to drastic laboratory hydrolyses is not paralleled by a great resistance to natural biodegradation triggered by change in land use; (ii) only small inputs of maize-derived compounds occurred in the non-hydrolysable fraction of the cultivated soil so that, in spite of extensive degradation, the forest-inherited carbon still predominates; (iii) the non-hydrolysable fractions of both soils comprise the same components (wood debris, spores, pollen, and, predominantly, granular organic aggregates), which correlate with the previously identified chemical components (charcoal, aliphatic lipid components and melanoidin-like components); (iv) the non-hydrolysable fraction of the cropped soil shows a greater contribution of aliphatic moieties, reflecting differential degradation of the components of the non-hydrolysable material inherited from the forest soil; (v) this degradation resulted in enrichment in the oldest components; and (vi) no relationship is observed, in the two Lacadée soils, between resistance to drastic laboratory hydrolyses, on the one hand, and stability towards biodegradation in situ, on the other. These observations, added to recent ones on other types of soils, suggest that such a conspicuous uncoupling between non-hydrolysable and stable carbon is probably a general feature of organic matter in soil as opposed to sedimentary organic matter

Etude du devenir de l'atrazine dans des sols limono-argileux du Bassin parisien par la combinaison de méthodes isotopiques et pyrolytiques

National audienc

Refractory organic matter in sediments from the North-West African upwelling system: abundance, chemical structure and origin

International audienc