Lactobionamide surfactants with hydrogenated, perfluorinated or hemifluorinated tails : physical-chemical and biochemical characterization

International audienceDetergents are customarily used to solubilize cell membranes and keep membrane proteins soluble in aqueous buffers, but they often lead to irreversible protein inactivation. Hemifluorinated amphiphiles with hybrid hydrophobic chains have been specifically designed to minimize the denaturating propensity of surfactants toward membrane proteins. We have studied the physical-chemical and biochemical properties of lactobionamide surfactants bearing either a hydrogenated, a fluorinated or a hemifluorinated chain (respectively H-, F-, and HF-Lac). We show that the dual composition of the hydrophobic chain of HF-Lac endows it with unusual physical-chemical properties as regards its critical micellar concentration, interfacial area per molecule, and behavior upon reverse phase chromatography. Analytical ultracentrifugation shows that, whereas H-Lac assembles into well-defined micelles, F-Lac and HF-Lac form large and heterogeneous assemblies, whose size increases with surfactant concentration. Molecular dynamics calculations suggest that F-Lac forms cylindrical micelles. The ability of HF-Lac to keep membrane proteins soluble was examined using the cytochrome b(6) f complex from Chlamydomonas reinhardtii's chloroplast as a model protein. HF-Lac/b(6) f complexes form particles relatively homogeneous in size, in which the b(6) f complex is as stable or markedly more stable, depending on the surfactant concentration, than it is in equivalent concentrations of hydrogenated surfactants, including H-Lac

Hormones et promoteurs de croissance en productions animales : de la physiologie à l'évaluation du risque

National audienceDuring the last fifty years, considerable progress in breeding performances of domestic species has been obtained due to a better knowledge obtained in physiology and in particular nutrition, growth, reproduction and lactation. This progress has been united with that of genetic progress accomplished in the different animal species in a context of an improved control of sanitary conditions of herds and a more accurate control of the existing breeding systems. The use of hormonal substances to better control reproduction functions and growth has become decisive within this progress. However, a profound tendency that restrains their use to certain critical moments in the life of an animal has appeared in Europe these last fifteen years, obliging researchers to search for alternatives via a better control of food, genetics and breeding systems, in order to guarantee to consumers a better, a priori, quality of animal products. Physiological functions that offer possibilities of exogenous hormonal control, usable hormonal substances and animal speculations are presented. A clarification of the toxicological risks that these substances present, the control and traceability of their use and the current regulations are given. Finally, the research that will allow making progress around the question of hormone use in breeding in a context of a remodelled society is evoked.Au cours des cinquante dernières années, des progrès considérables dans les performances d’élevage des espèces domestiques ont été obtenus grâce à une meilleure connaissance acquise dans le domaine de la physiologie, en particulier en ce qui concerne la nutrition, la croissance, la reproduction et la lactation, et qui s’est conjuguée aux progrès génétiques accomplis dans les différentes espèces animales dans un contexte de meilleure maîtrise sanitaire des troupeaux et de maîtrise plus fine des systèmes d’élevage en place. Le recours aux substances hormonales pour mieux maîtriser les fonctions de reproduction et de croissance a pris une place déterminante dans ce progrès. Néanmoins, une tendance profonde consistant à restreindre leur utilisation à certains moments critiques de la vie de l’animal est apparue en Europe ces quinze dernières années, obligeant à rechercher des alternatives par le biais d’une meilleure maîtrise alimentaire, génétique et des systèmes d’élevage, ceci afin de garantir aux consommateurs une meilleure qualité définie a priori des produits animaux. Les fonctions physiologiques qui offrent des possibilités d’un contrôle hormonal exogène, les substances hormonales utilisables et les spéculations animales concernées sont présentées tour à tour. Un éclaircissement sur les risques toxicologiques que présentent ces substances, le contrôle et la traçabilité de leur utilisation et les réglementations en vigueur sont ensuite rappelés. Enfin, sont évoquées les recherches qui permettront de faire progresser sensiblement la question de l’utilisation des hormones en élevage dans un contexte sociétal renouvelé

L'utilisation des hormones en élevage : les développements zootechniques et les préocupations de santé publique

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High Risk of Anal and Rectal Cancer in Patients With Anal and/or Perianal Crohn’s Disease

International audienceBackground & AimsLittle is known about the magnitude of the risk of anal and rectal cancer in patients with anal and/or perineal Crohn’s disease. We aimed to assess the risk of anal and rectal cancer in patients with Crohn’s perianal disease followed up in the Cancers Et Surrisque Associé aux Maladies Inflammatoires Intestinales En France (CESAME) cohort.MethodsWe collected data from 19,486 patients with inflammatory bowel disease (IBD) enrolled in the observational CESAME study in France, from May 2004 through June 2005; 14.9% of participants had past or current anal and/or perianal Crohn’s disease. Subjects were followed up for a median time of 35 months (interquartile range, 29–40 mo). To identify risk factors for anal cancer in the total CESAME population, we performed a case-control study in which participants were matched for age and sex.ResultsAmong the total IBD population, 8 patients developed anal cancer and 14 patients developed rectal cancer. In the subgroup of 2911 patients with past or current anal and/or perianal Crohn’s lesions at cohort entry, 2 developed anal squamous-cell carcinoma, 3 developed perianal fistula–related adenocarcinoma, and 6 developed rectal cancer. The corresponding incidence rates were 0.26 per 1000 patient-years for anal squamous-cell carcinoma, 0.38 per 1000 patient-years for perianal fistula–related adenocarcinoma, and 0.77 per 1000 patient-years for rectal cancer. Among the 16,575 patients with ulcerative colitis or Crohn’s disease without anal or perianal lesions, the incidence rate of anal cancer was 0.08 per 1000 patient-years and of rectal cancer was 0.21 per 1000 patient-years. Among factors tested by univariate conditional regression (IBD subtype, disease duration, exposure to immune-suppressive therapy, presence of past or current anal and/or perianal lesions), the presence of past or current anal and/or perianal lesions at cohort entry was the only factor significantly associated with development of anal cancer (odds ratio, 11.2; 95% CI, 1.18-551.51; P = .03).ConclusionsIn an analysis of data from the CESAME cohort in France, patients with anal and/or perianal Crohn’s disease have a high risk of anal cancer, including perianal fistula–related cancer, and a high risk of rectal cancer