Experimental clues of soft glassy rheology in strained filled elastomers

International audienceTensile stress-relaxation measurements have been performed on a series of cross-linked filled elastomers. The fillers are chosen in order to investigate the effect of the filler-filler and the filler-matrix interactions on the time dependence of the tensile relaxation modulus E(t) after UP and DOWN jumps. For the carbon black filled sample (strong filler-elastomer interaction) E(t) decreases as log(t) when the strain epsilon is strictly larger than 0.2 and reached by UP jumps. For the silica filled samples in the same conditions, and for all samples after a DOWN jump including epsilon = 0.2, the experimental data can be fitted with a power law equation characterized by the exponent m. Thus, in all cases, |dE(t)⁄dt| scales as t^(-α) with α=m+1. Pertinence of the Soft Glassy Rheology (SGR) model for interpreting the present results is examined. It is shown that α could be equivalent to the effective noise temperature x and related to the polymer chain mobility

Functional analysis of enhancer elements regulating the expression of the Drosophila homeodomain transcription factor DRx by gene targeting

Background The Drosophila brain is an ideal model system to study stem cells, here called neuroblasts, and the generation of neural lineages. Many transcriptional activators are involved in formation of the brain during the development of Drosophila melanogaster. The transcription factor Drosophila Retinal homeobox (DRx), a member of the 57B homeobox gene cluster, is also one of these factors for brain development. Results In this study a detailed expression analysis of DRx in different developmental stages was conducted. We show that DRx is expressed in the embryonic brain in the protocerebrum, in the larval brain in the DM and DL lineages, the medulla and the lobula complex and in the central complex of the adult brain. We generated a DRx enhancer trap strain by gene targeting and reintegration of Gal4, which mimics the endogenous expression of DRx. With the help of eight existing enhancer-Gal4 strains and one made by our group, we mapped various enhancers necessary for the expression of DRx during all stages of brain development from the embryo to the adult. We made an analysis of some larger enhancer regions by gene targeting. Deletion of three of these enhancers showing the most prominent expression patterns in the brain resulted in specific temporal and spatial loss of DRx expression in defined brain structures. Conclusion Our data show that DRx is expressed in specific neuroblasts and defined neural lineages and suggest that DRx is another important factor for Drosophila brain development

The prominent role of the S100A8/S100A9-CD147 axis in the progression of penile cancer

Currently, no established biomarkers are recommended for the routine diagnosis of penile carcinoma (PeCa). The rising incidence of this human papillomavirus (HPV)–related cancer entity highlights the need for promising candidates. The Calprotectin subunits S100A8 and S100A9 mark myeloid-derived suppressor cells in other HPV-related entities while their receptor CD147 was discussed to identify patients with PeCa at a higher risk for poor prognoses and treatment failure. We thus examined their expression using immunohistochemistry staining of PeCa specimens from 74 patients on tissue microarrays of the tumor center, the invasion front, and lymph node metastases. Notably, whereas the tumor center was significantly more intensively stained than the invasion front, lymph node metastases were thoroughly positive for both S100 subunits. An HPV-positive status combined with an S100A8+S100A9+ profile was related with an elevated risk for metastases. We observed several PeCa specimens with S100A8+S100A9+-infiltrating immune cells overlapping with CD15 marking neutrophils. The S100A8+S100A9+CD15+ profile was associated with dedifferentiated and metastasizing PeCa, predominantly of HPV-associated subtype. These data suggest a contribution of neutrophil-derived suppressor cells to the progression of HPV-driven penile carcinogenesis. CD147 was elevated, expressed in PeCa specimens, prominently at the tumor center and in HPV-positive PeCa cell lines. CD147+HPV+ PeCa specimens were with the higher-frequency metastasizing cancers. Moreover, an elevated expression of CD147 of HPV-positive PeCa cell lines correlated negatively with the susceptibility to IgA-based neutrophil-mediated tumor cell killing. Finally, stratifying patients regarding their HPV/S100A8/S100A9/CD15/CD147 profile may help identify patients with progressing cancer and tailor immunotherapeutic treatment strategies

DKK1 inhibits canonical Wnt signaling in human papillomavirus-positive penile cancer cells

Penile squamous cell cancer (PSCC) is the most frequent penile malignant disease. Infections with human papillomaviruses (HPV) are a major etiologic driver of PSCC. However, the molecular details of the underlying carcinogenesis are understudied because of rare clinical specimens and missing cell lines. Here, we investigated if the expression of high-risk HPV16 oncogenes causes an augmentation of the Wnt pathway using unique HPV-positive penile cancer (PeCa) cell lines in monolayer and organotypic 3D raft cultures as well as tissue micro arrays containing clinical tissue specimens. The HPV oncoproteins enhanced the expression of Leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) and the HPV-positive PeCa cells expressed a signature of Wnt target and stemness-associated genes. However, the notable lack of nuclear β-catenin in vitro and in situ raised the question if the enhanced expression of Wnt pathway factors is tantamount to an active Wnt signaling. Subsequent TOP-flash reporter assays revealed Wnt signaling as absent and not inducible by respective Wnt ligands in PeCa cell lines. The HPV-positive PeCa cells and especially HPV-positive PeCa specimens of the tumor core expressed the Wnt antagonist and negative feedback-regulator Dickkopf1 (DKK1). Subsequent neutralization experiments using PeCa cell line-conditioned media demonstrated that DKK1 is capable to impair ligand-induced Wnt signaling. While gene expression analyses suggested an augmented and active canonical Wnt pathway, the respective signaling was inhibited due to the endogenous expression of the antagonist DKK1. Subsequent TMA stainings indicated Dkk1 as linked with HPV-positivity and metastatic disease progression in PeCa suggesting potential as a prognostic marker

Diffuse scattering

Diffuse neutron scattering covers a wide range of phenomena related to short range nuclear and magnetic orderings. Although it is “a priori” simple to measure, the underlying physics is often quite complex. Extracting useful and reliable information requires careful corrections and calibrations, and appropriate models of analysis, specifics for each physical case. This paper yields a partial and subjective glance on this specific subject, showing studies about chemical orderings in binary alloys and magnetic correlations in frustrated “spin ices” as examples

Intérêt des ateliers santé ville pour le médecin généraliste (exemple de l'atelier santé ville de la communauté de communes de Sens)

DIJON-BU Médecine Pharmacie (212312103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Anisotropic and heterogeneous dynamics in stretched elastomer nanocomposites

International audienc

Nanoporous carbon materials : comparison between information obtained by SAXS and WAXS and by gaz adsorption.

39 page

Investigation of the microporous texture of carbon materials by SAXS-WAXS using contrast variation

International audienc

Bioresorbable and nonresorbable macroporus thermosensitive hydrogels prepared by cryopolymerization. Role of the cross-linking agent

Macroporous poly(N-isopropylacrylamide) (pNIPA) gels (so-called cryogels), cross-linked with different bisacryliccompounds, N,N'-methylenebisacrylamide (MBAAm) and dimethacrylate-tyrosine-lysine-tyrosine (DMTLT), were prepared through free-radical polymerization at subzero temperature in dioxane/water media. DMTLT is a hydrolytically degradable cross-linker with relatively hydrophobic character. The effects of different synthesis conditions, namely the concentration of monomers, the cross-linker, and the initiator in the reaction mixture, on the structure of the pNIPA-cryogels have been studied. The equilibrium swelling ratio of the DMTLT crosslinked pNIPA cryogels at temperatures below lower critical solution temperature (LCST) of pNIPA, was over ten times higher than that of the gels synthesized at room temperature from the same feed composition. The MBAAm cross-linked pNIPA cryogels synthesized in water exhibited the highest equilibrium swelling and the fastest response. The critical transition temperature, T-c, was lower (T-c approximate to 31 degrees C) for pNIPA-cryogels synthesized in dioxane/water media or cross-linked with DMTLT as compared to MBAAm cross-linked pNIPA cryogels synthesized in water (T-c approximate to 33 degrees C). Scanning electron microscopy (SEM) revealed different porous structure and pore surface morphology depending on the cross-linker (MBAAm or DMTLT) and the solvent (water or dioxane/water) used. Gels and cryogels were also characterized by SAXS, showing that the nanostructure of the samples is related to swelling