Verres formes par les sulfures L2S3 des terres rares avec le sulfure de gallium Ga2S3

Formation of glasses in the systems L₂S₃Ga₂S₃ (L = Y and La to Er, and La to Er, except Eu). Conditions of preparation. Extent of the glassy regions as a fonction of the quenching temperatures and of the rare earth element. Crystallisation by heating: vitreous transition temperature Tg, and crystallisation temperature Tc. Mechanism of crystallisation. Preliminary study of the absorption spectra.     

Analysis by confocal scanning laser microscopy imaging of the spatial distribution of intermediate filaments in foetal and adult rat liver cells

Confocal scanning laser microscopy has been used to make three-dimensional observations of the spatial distribution of cytoskeleton intermediate filaments in rat liver hepatocytes, at various stages during foetal development and in the adult. Single and double immuno-labelling with fluorescein and Texas Red fluorescence have been used to study the intracellular spatial distribution of C18 cytokeratin and vimentin. Simultaneous confocal imaging with double-fluorescence emission requires an image processing step for the correction of ‘contamination’ effects due to the overlap between fluorescein and Texas Red emission spectra. At the pre-natal period (day 20 of gestation) each type of intermediate filament labelling is only present in a certain cellular category, C18 cytokeratin in hepatocytes and vimentin in mesenchymal cells. However, at the earliest developmental stages (day 12 of gestation), vimentin and cytokeratin seem to be found in the same type of cells, probably mesenchymal cells. Some striking developmental changes, associated with the differentiation of the liver parenchyma, are observed for both C18 cytokeratin and vimentin. In earlier foetal stages, C18 filaments are scarce, hazily labelled and randomly distributed inside the hepatocytic cytoplasm. Late during foetal development (days 18–20 of gestation), hepatocytic cytokeratin filaments are abundant, well individualized and sharply labelled. The hepatocytes are arranged in a muralium duplex architecture (two-cell-thick sheets) and the labelling intensity measured in the hepatocytic cytoplasm at the basal pole is double that measured at the sinusoidal pole, while, in the adult, hepatocytes are arranged in a muralium simplex architecture (one-cell-thick sheets) and cytokeratin filaments have a symmetrical distribution in relation to the nuclear region.     

Apolipoprotein E genotype and alpha-tocopherol modulate amyloid precursor protein metabolism and cell cycle regulation

Apolipoprotein E4 (apoE4) genotype is associated with an increased risk for Alzheimer's disease (AD). This is thought to be in part attributable to an impact of apoE genotype on the processing of the transmembrane amyloid precursor protein (APP) thereby contributing to amyloid beta peptide formation in apoE4 carriers, which is a primary patho-physiological feature of AD. As apoE and alpha-tocopherol (alpha-toc) have been shown to modulate membrane bilayer properties and hippocampal gene expression, we studied the effect of apoE genotype on APP metabolism and cell cycle regulation in response to dietary alpha-toc. ApoE3 and apoE4 transgenic mice were fed a diet low (VE) or high (+VE) in vitamin E (3 and 235 mg alpha-toc/kg diet, respectively) for 12 weeks. Cholesterol levels and membrane fluidity were not different in synaptosomal plasma membranes isolated from brains of apoE3 and apoE4 mice (-VE and +VE). Non-amyloidogenic alpha-secretase mRNA concentration and activity were significantly higher in brains of apoE3 relative to apoE4 mice irrespective of the dietary alpha-toc supply, while amyloidogenic beta-secretase and gamma-secretase remained unchanged. Relative mRNA concentration of cell cycle related proteins were modulated differentially by dietary alpha-toc supplementation in apoE3 and apoE4 mice, suggesting genotype-dependent signalling effects on cell cycle regulation.     

Development of a protocol for the isolation of Listeria monocytogenes from sludge

Given the high level of background flora in sludge, methods for detecting Listeria monocytogenes are not well established. In this study, two critical parameters for the detection of L. monocytogenes were evaluated: the concentration of Listeria sp. in a modified Fraser broth (first stage of the method) and the proportion of L. monocytogenes on Palcam agar (second stage of the method). Concentrations of Listeria sp. estimated in 118 modified Fraser enrichment broths inoculated with four types of sludge, reached 10(4) bacteria per mL for 83% of the positive enrichment broths. Proportion of L. monocytogenes on Palcam agar, which was estimated by transferring all characteristic colonies of Listeria sp. onto Rapid'L Mono agar, was highly variable regardless of the type of sludge. According to these results, we proposed a protocol that consisted of an enrichment in modified Fraser broth for 48 h at 37 degrees C, followed by plating 0.1 mL of appropriate dilutions of broth onto Palcam agar. After an incubation of 48 h at 37 degrees C, a systematic identification of characteristic colonies of Listeria sp. on Rapid'L Mono agar allowed to enhance the detection of Listeria monocytogenes.     

Synthesis of YAG:Ce/TiO2 nanocomposite films

Our work is devoted to the development of YAG:Ce³⁺ phosphor nanoparticle-based converter layer for white LEDs. To avoid losses due to scattering effects, the strategy is to control separately the down-conversion and the extraction of light instead of using micron-sized luminescent particles acting simultaneously as both converter and scatterer. YAG:Ce nanoparticles were synthesized by a glycothermal method in autoclave at low temperature (300 °C). Y₃Al₅O₁₂ garnet phase with a crystallite size of 25 nm was obtained, as verified by X-ray diffraction and electron microscopy. The quantum yield of nanoparticles is 55%. The colloidal nanoparticles are finally incorporated into a sol-gel matrix of TiO₂. The small difference in refractive index between particles and matrix and the nanosize of the particles contribute to the transparency of the converter films. The surface of these layers can be periodically patterned by soft nano-imprint lithography. The diffraction due to the obtained photonic crystal at the surface may offer the opportunity to compensate the absence of scattering to extract the converted light.     

λ³/1000 plasmonic nanocavities for biosensing fabricated by soft UV nanoimprint lithography

Arrays of plasmonic nanocavities with very low volumes, down to λ(3)/1000, have been fabricated by soft UV nanoimprint lithography. Nearly perfect omnidirectional absorption (3-70°) is demonstrated for the fundamental mode of the cavity (λ ? 1.15 μm). The second-order mode exhibits a sharper resonance with strong angular dependence and total optical absorption when the critical coupling condition is fulfilled (45-50°, λ ? 750 nm). It leads to high refractive index sensitivity (405 nm/RIU) and figure of merit (～21) and offers new perspectives for efficient biosensing experiments in ultralow volumes.     

Structure-dependent coherent acoustic vibrations of hollow gold nanospheres

Hollow gold nanospheres (HGNs) were excited with ultrashort laser pulses, and the coherent vibrational response was examined using femtosecond time-resolved transient absorption. The results indicated that HGNs support an isotropic mode, resulting in periodic modulation of the surface plasmon differential absorption. Two different categories of coherent acoustic vibrations, which depend on particle dimensions, were observed for HGNs. Further, the vibration launching mechanism was dependent upon the dimensions of the HGN. Coherent vibrations in HGNs characterized by small outer radii (<10 nm) and low cavity-radius-to-outer-shell radius aspect ratios (<0.5) were excited by a direct mechanism, whereas the vibrations observed for the larger particles (>25 nm OR) with higher aspect ratios (>0.5) resulted from an indirect mechanism. These findings may be significant for developing a predictive understanding of nanostructure optical and mechanical properties.     

Preparation and characterization of collagen/PLA,chitosan/PLA,and collagen/chitosan/PLA hybrid scaffolds for cartilage tissue engineering

In this study, three-dimensional (3D) porous scaffolds were developed for the repair of articular cartilage defects. Novel collagen/polylactide (PLA), chitosan/PLA, and collagen/chitosan/PLA hybrid scaffolds were fabricated by combining freeze-dried natural components and synthetic PLA mesh, where the 3D PLA mesh gives mechanical strength, and the natural polymers, collagen and/or chitosan, mimic the natural cartilage tissue environment of chondrocytes. In total, eight scaffold types were studied: four hybrid structures containing collagen and/or chitosan with PLA, and four parallel plain scaffolds with only collagen and/or chitosan. The potential of these types of scaffolds for cartilage tissue engineering applications were determined by the analysis of the microstructure, water uptake, mechanical strength, and the viability and attachment of adult bovine chondrocytes to the scaffolds. The manufacturing method used was found to be applicable for the manufacturing of hybrid scaffolds with highly porous 3D structures. All the hybrid scaffolds showed a highly porous structure with open pores throughout the scaffold. Collagen was found to bind water inside the structure in all collagen-containing scaffolds better than the chitosan-containing scaffolds, and the plain collagen scaffolds had the highest water absorption. The stiffness of the scaffold was improved by the hybrid structure compared to plain scaffolds. The cell viability and attachment was good in all scaffolds, however, the collagen hybrid scaffolds showed the best penetration of cells into the scaffold. Our results show that from the studied scaffolds the collagen/PLA hybrids are the most promising scaffolds from this group for cartilage tissue engineering.     

Carnobacterium maltaromaticum: Identification,isolation tools,ecology and technological aspects in dairy products

Carnobacterium species constitute a genus of Lactic Acid Bacteria (LAB) present in different ecological niches. The aim of this article is to summarize the knowledge about Carnobacterium maltaromaticum species at different microbiological levels such as taxonomy, isolation and identification, ecology, technological aspects and safety in dairy products. Works published during the last decade concerning C. maltaromaticum have shown that this non-starter LAB (NSLAB) could present major interests in dairy product technology. Four reasons can be mentioned: i) it can grow in milk during the ripening period with no competition with starter LAB, ii) this species synthesizes different flavouring compounds e.g., 3-methylbutanal, iii) it can inhibit the growth of foodborne pathogens as Listeria monocytogenes due to its ability to produce bacteriocins, iv) it has never been reported to be involved in human diseases as no cases of human infection have been directly linked to the consumption of dairy products containing this species.     

In Vitro Validation of the Therapeutic Potential of Dendrimer-Based Nanoformulations against Tumor Stem Cells

Tumor cells with stem cell properties are considered to play major roles in promoting the development and malignant behavior of aggressive cancers. Therapeutic strategies that efficiently eradicate such tumor stem cells are of highest clinical need. Herein, we performed the validation of the polycationic phosphorus dendrimer-based approach for small interfering RNAs delivery in in vitro stem-like cells as models. As a therapeutic target, we chose Lyn, a member of the Src family kinases as an example of a prominent enzyme class widely discussed as a potent anti-cancer intervention point. Our selection is guided by our discovery that Lyn mRNA expression level in glioma, a class of brain tumors, possesses significant negative clinical predictive value, promoting its potential as a therapeutic target for future molecular-targeted treatments. We then showed that anti-Lyn siRNA, delivered into Lyn-expressing glioma cell model reduces the cell viability, a fact that was not observed in a cell model that lacks Lyn-expression. Furthermore, we have found that the dendrimer itself influences various parameters of the cells such as the expression of surface markers PD-L1, TIM-3 and CD47, targets for immune recognition and other biological processes suggested to be regulating glioblastoma cell invasion. Our findings prove the potential of dendrimer-based platforms for therapeutic applications, which might help to eradicate the population of cancer cells with augmented chemotherapy resistance. Moreover, the results further promote our functional stem cell technology as suitable component in early stage drug development.