PHYSICAL AGING OF EMULSIONS CONTAINING COATED TIO2-NANOPARTICLES: INTERACTION BETWEEN NANOPARTICLES AND OTHER INGREDIENTS

International audienceTiO2-nanoparticles (NPs) are usually added to cosmetic emulsions because they procure a good UV-protection1. In this study, two natures of NPs surfaces were explored: a hydrophilic silica-coated particle and a hydrophobic one covered with a large organic coating. During emulsion aging and depending on their surfacenature and properties, NPs might interact with the formula by inducing adsorption of formula’s compounds2 or by undergoingcoatings damages. These phenomenamay change the nanoparticle surface properties, their behavior in emulsion, and finally, led to the emulsionsdestabilization. The impact of TiO2-NP surfaces on the physical aging of emulsions was here studied.For this purpose, threeemulsions were formulated differing only by the presence and type of NPs: one NP-free as blank, and two containing hydrophilic and hydrophobic commercial TiO2-NPs, respectively.The emulsification process was optimized to obtain a blank emulsion physically stable and to improve the NPs dispersions. Effects of coatings on fresh emulsions were depicted on the micro and macro scales by several physico-chemical methods.Then, emulsions physical evolutions onnormal or accelerate aging conditionswere monitored.Droplets sizes were similar between the three fresh emulsions, whereas slight differences in term of networksorganization highlighted the impact of the coating nature on the emulsion microstructure. However, initial emulsions properties looked similar by applying rheological and textural analyses. Although the blank emulsion and the one with hydrophilic NPs remained similar after the aging step, the microstructure of the emulsion with hydrophobic NPsquickly evolved: aggregates of both droplets and NPs made the formula less homogeneous. As will be illustrated, this evolution in term of colloids sizes strongly affects the functional properties, as viscosity, consistency or spreading quality of this aged emulsion. These results revealed the impact of coating nature in this kind of complex media. Afterinnovative NPs extractions3 from fresh and aged formulae, their surfaces were characterized. By an original physico-chemical approach, quick surface modifications appeared and changed the surface charges and wettability of particles. These variations might cause the differences in term of stability between emulsions.(1) Serpone, N.; Dondi, D.; Albini, A. Inorganica Chim. Acta2007, 360 (3), 794–802.(2) Rossano, M.; Hucher, N.; Picard, C.; Colleta, D.; Le Foll, F.; Grisel, M. Int. J. Pharm.2014, 461 (1-2), 89–96.(3) Rossano, M. Ph.D thesis: Utilisation des nanoparticules de dioxyde de titane dans les émulsions cosmétiques : impact sur la santé humaine et l’environnement, Université du Havre: Le Havre, 2014

Development of preservative-free nanoparticles-based emulsions: Effects of NP surface properties and sterilization process

International audienceModel emulsions were developed with or without commercial titanium dioxide nanoparticles (NP) carrying various surface treatments in order to get close physicochemical properties whatever the NP surface polarity (hydrophilic and hydrophobic). Rheology and texturometry highlighted that the macroscopic properties of the three formulated emulsions were similar. However, characterizations by optical microscopy, static light scattering and zetametry showed that their microstructures reflected the diversity of the incorporated NP surface properties. In order to use these model emulsions as tools for biological evaluations of the NP in use, they had to show the lowest initial microbiological charge and, specifically for the NP-free emulsion, the lowest bactericidal effect. Hence, formulae were developed preservative-free and a thermal sterilization step was conducted. Efficiency of the sterilization and its impact on the emulsion integrity were monitored. Results highlighted the effect of the NP surface properties: only the control emulsion and the emulsion containing hydrophilic NP fulfilled both requirements. To ensure the usability of these model emulsions as tools to evaluate the 'NP effect' on representative bacteria of the skin microflora (S. aureus and P. fluorescens), impact on the bacterial growth was measured on voluntary inoculated formulae

A Robust and Multi-Scale Modal Analysis For Sound Synthesis

International audienceThis paper presents a new approach to modal synthesis for rendering sounds of virtual objects. We propose a generic method for modal analysis that preserves sound variety across the surface of an object, at different scales of resolution and for a variety of complex geometries. The technique performs automatic voxelization of a surface model and automatic tuning of the parameters of hexahedral finite elements, based on the distribution of material in each cell. The voxelization is performed using a sparse regular grid embedding of the object, which easily permits the construction of plausible lower resolution approximations of the modal model. With our approach, we can compute the audible impulse response of a variety of objects. Our solution is robust and can handle non-manifold geometries that include both volumetric and surface parts, such as those used in games, training simulations, and other interactive virtual environment

IMPACT OF A TIO2 [NANO] COSMETICS GRADE ON THE CUTANEOUS MICROBIOTA: NANOPARTICLES BEHAVIOR IN EMULSION AND BACTERIOTOXICITY

International audienceTiO2-nanoparticles (NP) commonly used in cosmetics as physical UV-filters, are surface-modified by applying a first coating in order to quench photo-produced radicals. In addition, a second coating is sometimes added to raise their dispersibility in emulsion. Whereas European regulation mentions the obligation to demonstrate the safety of NP, very few studies took interest on their behavior in use. During formulation and storage, NP are exposed to a variety of environmental conditions which can accelerate aging and induce particles aggregation, adsorption of formula’s compounds or coatings deterioration. Consequently, a crucial question remains their safety while layered on skin and particularly their effect on the skin microflora. We will present the impact of TiO2-nanoparticles on the skin microflora in relation to their physicochemical properties in cosmetic emulsions during aging.A series of cosmetic emulsions were formulated with using conventional cosmetic ingredients, with or without Nanoparticles (NPs): one without NPs considered as blank, and two with hydrophilic and hydrophobic commercial TiO2-NPs, respectively. An emulsification process was developed and optimized to obtain a blank emulsion, physically stable, with improved NPs dispersions in emulsion. Then, emulsions were submitted to accelerate aging.Particles were extracted from the fresh/aged emulsions by original protocols allowing recovering particles with possible adsorbed compounds or cleaned surfaces.Skin bacteria growths were evaluated in emulsions or dispersions to check the toxicity of nanoparticles in use. Then, because of NP opacity, protocols were adapted to measure their effect on bacteria virulence toward skin cells.Microscopic and macroscopic characterizations revealed comparable structures and functional properties between the three fresh emulsions. Then, during aging, different behavior were registered and could be related to nanoparticle coating nature.Extracted NP from the fresh/aged formulas showed quick surface modifications in terms of chemical structures and physical properties that might be caused by adsorption or deterioration at their surfaces.For fresh emulsions, both nanoparticles did not have any impact on skin bacteria strains, S. aureus and P. fluorescens. In the case of aged emulsions, part of NPs seemed to allow the S. aureus growth, whereas others still remained with no effect on microflora. Finally, bacteria generation times and virulence toward skin cells differed depending on NPs surface treatments and exposition time.This work dealt with the impact of nanoparticles on skin microflora along cosmetic emulsion shelf-life. This new approach allows taking into account their safety when used in emulsion.First, through innovative extraction and characterization protocols, it was highlighted that chemical nature and physical properties of nanoparticle surfaces might be altered once in emulsion. These physicochemical observations were related to microbiological tests on skin representative bacteria. Effect of some of the NPs on bacteria growth and virulence evolved after aging. Finally, modification of NPs surface treatment seemed to have an effect on skin microflora

Xeroderma pigmentosum: clues to understanding cancer initiation

AbstractXeroderma pigmentosum (XP) type C is a rare autosomal recessive disorder that occurs because of inactivation of the xeroderma pigmentosum group C (XPC) protein, which is an important DNA damage recognition protein involved in DNA nucleotide excision repair (NER). This defect, which prevents removal of a wide array of direct and indirect DNA lesions, is associated with a decrease in catalase activity. As a novel photoprotective approach, lentivirus-mediated catalase overexpression in XPC human keratinocytes results in a marked decrease in sunburn cell formation, caspase-3 activation, and p53 accumulation following UVB irradiation. While not correcting the gene defect, indirect gene therapy using antioxidant enzymes may be helpful in limiting photosensitivity in XP type C, as well as in other monogenic/polygenic photosensitive disorders characterized by reactive oxygen species (ROS) accumulation. Hypoxia-inducible factor-1 (HIF-1), a major transcription factor sensitive to oxygen levels, responds to various stress factors. As a common stressor of skin, UVB induces a biphasic HIF-1a variation through ROS generation in keratinocytes. HIF-1a has an important regulator effect on the expression of XPC protein and other NER genes, indicating indirect regulation of NER by ROS. The intrinsic genomic instability arising in XP type C provides a good opportunity to investigate the complex molecular mechanisms underlying the Warburg effect (the shift of mito-chondrial metabolism towards glycolysis). Overall, the monogenic disorder XP type C is a powerful tool for studying photoprotection and cancer

Est-il besoin de savoir programmer pour comprendre les fondements de l'informatique ou utiliser les logiciels ?

National audienceCe texte collectif fait la synthèse d'échanges sur la liste de diffusion du groupe ITIC de l'association Enseignement Public et Informatique (EPI : www.epi.asso.fr), produits à la suite du partage des références : « Why everyone should learn programming » (2010), Daniel Shiffman & Mark Webster [1], et « Comment développer la culture en informatique : en l'enseignant dès le lycée » (2010), Antoine Petit [2]

Genomic imprinting mediates dosage compensation in a young plant XY system.: An article peer-reviewed and recommended by Peer Community In Evolutionary Biology (PCI Evol Biol)

This preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100044). Sex chromosomes have repeatedly evolved from a pair of autosomes. Consequently, X and Y chromosomes initially have similar gene content, but ongoing Y degeneration leads to reduced Y gene expression and eventual Y gene loss. The resulting imbalance in gene expression between Y genes and the rest of the genome is expected to reduce male fitness, especially when protein networks have components from both autosomes and sex chromosomes. A diverse set of dosage compensating mechanisms that alleviates these negative effects has been described in animals. However, the early steps in the evolution of dosage compensation remain unknown and dosage compensation is poorly understood in plants. Here we show a novel dosage compensation mechanism in the evolutionarily young XY sex determination system of the plant Silene latifolia. Genomic imprinting results in higher expression from the maternal X chromosome in both males and females. This compensates for reduced Y expression in males but results in X overexpression in females and may be detrimental. It could represent a transient early stage in the evolution of dosage compensation. Our finding has striking resemblance to the first stage proposed by Ohno for the evolution of X inactivation in mammals

In-situ observations using tagged animals

Marine mammals help gather information on some of the harshest environments on the planet, through the use of miniaturized ocean sensors glued on their fur. Since 2004, hundreds of diving marine animals, mainly Antarctic and Arctic seals, have been fitted with a new generation of Argos tags developed by the Sea Mammal Research Unit of the University of St Andrews in Scotland, UK. These tags investigate the at-sea ecology of these animals while simultaneously collecting valuable oceanographic data. Some of the study species travel thousands of kilometres continuously diving to great depths (up to 2100 m). The resulting data are now freely available to the global scientific community at http://www.meop.net. Despite great progress in their reliability and data accuracy, the current generation of loggers while approaching standard ARGO quality specifications have yet to match them. Yet, improvements are underway; they involve updating the technology, implementing a more systematic phase of calibration and taking benefit of the recently acquired knowledge on the dynamical response of sensors. Together these efforts are rapidly transforming animal tagging into one of the most important sources of oceanographic data in polar regions and in many coastal areas.Publisher PDFNon peer reviewe

Exhaustive analysis of BH4 and dopamine biosynthesis genes in patients with Dopa-responsive dystonia

Dopa-responsive dystonia is a childhood-onset dystonic disorder, characterized by a dramatic response to low dose of l-Dopa. Dopa-responsive dystonia is mostly caused by autosomal dominant mutations in the GCH1 gene (GTP cyclohydrolase1) and more rarely by autosomal recessive mutations in the TH (tyrosine hydroxylase) or SPR (sepiapterin reductase) genes. In addition, mutations in the PARK2 gene (parkin) which causes autosomal recessive juvenile parkinsonism may present as Dopa-responsive dystonia. In order to evaluate the relative frequency of the mutations in these genes, but also in the genes involved in the biosynthesis and recycling of BH4, and to evaluate the associated clinical spectrum, we have studied a large series of index patients (n = 64) with Dopa-responsive dystonia, in whom dystonia improved by at least 50% after l-Dopa treatment. Fifty seven of these patients were classified as pure Dopa-responsive dystonia and seven as Dopa-responsive dystonia-plus syndromes. All patients were screened for point mutations and large rearrangements in the GCH1 gene, followed by sequencing of the TH and SPR genes, then PTS (pyruvoyl tetrahydropterin synthase), PCBD (pterin-4a-carbinolamine dehydratase), QDPR (dihydropteridin reductase) and PARK2 (parkin) genes. We identified 34 different heterozygous point mutations in 40 patients, and six different large deletions in seven patients in the GCH1 gene. Except for one patient with mental retardation and a large deletion of 2.3 Mb encompassing 10 genes, all patients had stereotyped clinical features, characterized by pure Dopa-responsive dystonia with onset in the lower limbs and an excellent response to low doses of l-Dopa. Dystonia started in the first decade of life in 40 patients (85%) and before the age of 1 year in one patient (2.2%). Three of the 17 negative GCH1 patients had mutations in the TH gene, two in the SPR gene and one in the PARK2 gene. No mutations in the three genes involved in the biosynthesis and recycling of BH4 were identified. The clinical presentations of patients with mutations in TH and SPR genes were strikingly more complex, characterized by mental retardation, oculogyric crises and parkinsonism and they were all classified as Dopa-responsive dystonia-plus syndromes. Patient with mutation in the PARK2 gene had Dopa-responsive dystonia with a good improvement with l-Dopa, similar to Dopa-responsive dystonia secondary to GCH1 mutations. Although the yield of mutations exceeds 80% in pure Dopa-responsive dystonia and Dopa-responsive dystonia-plus syndromes groups, the genes involved are clearly different: GCH1 in the former and TH and SPR in the late

Gain-of-function human STAT1 mutations impair IL-17 immunity and underlie chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis disease (CMCD) may be caused by autosomal dominant (AD) IL-17F deficiency or autosomal recessive (AR) IL-17RA deficiency. Here, using whole-exome sequencing, we identified heterozygous germline mutations in STAT1 in 47 patients from 20 kindreds with AD CMCD. Previously described heterozygous STAT1 mutant alleles are loss-of-function and cause AD predisposition to mycobacterial disease caused by impaired STAT1-dependent cellular responses to IFN-γ. Other loss-of-function STAT1 alleles cause AR predisposition to intracellular bacterial and viral diseases, caused by impaired STAT1-dependent responses to IFN-α/β, IFN-γ, IFN-λ, and IL-27. In contrast, the 12 AD CMCD-inducing STAT1 mutant alleles described here are gain-of-function and increase STAT1-dependent cellular responses to these cytokines, and to cytokines that predominantly activate STAT3, such as IL-6 and IL-21. All of these mutations affect the coiled-coil domain and impair the nuclear dephosphorylation of activated STAT1, accounting for their gain-of-function and dominance. Stronger cellular responses to the STAT1-dependent IL-17 inhibitors IFN-α/β, IFN-γ, and IL-27, and stronger STAT1 activation in response to the STAT3-dependent IL-17 inducers IL-6 and IL-21, hinder the development of T cells producing IL-17A, IL-17F, and IL-22. Gain-of-function STAT1 alleles therefore cause AD CMCD by impairing IL-17 immunity