Dielectric layers with gradual properties

International audienceThis work presents results from a study of thin dielectric layers organized in a structure that behaves as an unified layer with gradual properties. A better understanding of dielectric charging phenomena is aimed at in order to control the conductive properties of the multi-layer system. We first characterize each mono-layer deposited singly on a substrate before the characterization of our multi-layer system. The presented results are for the material and electrical properties of the layers. They are obtained from different diagnostic methods. It was found that such a concept allows modulation of the conductive properties of dielectric materials

Bio-Functionalization of Silicon Carbide Nanostructures for SiC Nanowire-Based Sensors Realization

International audienceThe bio-functionalization process consisting in grafting desoxyribo nucleic acid via aminopropyltriethoxysilane is performed on several kinds of silicon carbide nanostructures. Prior, the organic layer is characterized on planar surface with fluorescence microscopy and X-ray photoelectron spectroscopy. Then, the functionalization is performed on two kinds of nanopillar arrays. One is composed of top-down SiC nanopillars with a wide pitch of 5 μm while the other one is a dense array (pitch: 200 nm) of core–shell Si–SiC nanowires obtained by carburization of silicon nanowires. Depending on both the pillar morphology and the pitch, different results in term of DNA surface coverages are obtained, as seen from fluorescence microscopy images. Particularly, in the case of the wide pitch array, it has been shown that the DNA molecules are located all along the nanopillars. To achieve a DNA sensor based on a nanowire-field effect transistor, the functionalization must be conducted on a single SiC nanowire or nanopillar that constitutes the channel of the field effect transistor. The localization of the functionalization in a small area around the nanostructures guarantees high performances to the sensor. In this aim, the functionalization process is combined with common microelectronics techniques of lithography and lift-off. The DNA immobilization is investigated by fluorescence microscopy and atomic force microscopy

Multiscale Porosity Directs Bone Regeneration in Biphasic Calcium Phosphate Scaffolds

International audienceLarge and load-bearing bone defects are challenging to treat and cause pain and disfigurement. The design of efficacious bone scaffolds for the repair of such defects involves a range of length scales from the centimeter down to the micrometer-scale. Here, we assess the influence on bone regeneration of scaffold rod spacing (>300 μm) and microporosity (<50 μm), as well as the combination of different structures and materials in the same scaffold, i.e., at the millimeter scale. We use four single-domain scaffolds, microporous (MP) or nonmicroporous (NMP) and with either a “small” or “large” rod spacing. Multidomain scaffolds combine four regions corresponding to the macro- and microarchitectures of the single-domain scaffolds. The scaffolds are implanted in pig mandibles for 3 weeks and bone regeneration is assessed by measuring the average bone volume fraction, , the bone distribution and the trabecular thickness from micro-CT data. For the single-domain scaffolds, was 45 ± 3% for MP-small, 39 ± 2% for MP-large, 25 ± 2% for NMP-small, and 25 ± 2% for NMP-large. MP scaffolds have significantly higher and a more uniform bone distribution compared to NMP, regardless of rod spacing. The average trabecular thickness is significantly larger in MP compared to NMP, and in “large” compared to “small” scaffolds. Microporosity affects trabecular thickness throughout the scaffold, while rod spacing affects it only at the scaffold periphery. In multidomain scaffolds, MP-large and NMP-large domains have similar as compared to their respective single-domain counterparts. These results suggest that combining different architectures into one scaffold conserves the properties of each domain. Hence, bone growth and morphology can be tailored by controlling scaffold architecture from the millimeter down to the micrometer level. This will allow the customization of scaffold designs for the treatment of large and load-bearing bone defects

Three-dimensional densitometry imaging of diatom cells using STIM tomography

Scanning transmission ion microscopy tomography (STIM-T) was carried out on diatom cells with the aim of displaying their 3D structure and performing density measurements on their silica skeleton. Two software packages were compared for data reduction: TomoRebuild, based on a simple filtered backprojection algorithm, and DISRA, an iterative program. Silicon carbide microfibres of known density were also analysed as reference specimens. Similar results were obtained with both algorithms, demonstrating the ability of STIM-T to provide density measurements at the cell level without requiring any standard calibration samples. This unique feature stresses the interest of STIM-T to accurately normalise X ray emission micro-tomography data from synchrotron radiation (SXRF: synchrotron radiation X-ray fluorescence) or ion beam sources (PIXE: particle induced X-ray emission). Possible enhancements of the DISRA code are discussed in order to facilitate its use for the reconstruction of future PIXE/STIM tomography data. A "nanoprobe" coupled to a Singletron® accelerator, allowing a spatial resolution of a few tens of nanometers, is going to be built in the coming months at the Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG). This new facility will bring promising applications in imaging and analysis at the sub-cellular level

Dimorphic metabolic and endocrine disorders in mice lacking the constitutive androstane receptor

International audienceMetabolic diseases such as obesity, type II diabetes and hepatic steatosis are a public health concern in developed countries. The metabolic risk is gender-dependent. The constitutive androstane receptor (CAR), which is at the crossroads between energy metabolism and endocrinology, has recently emerged as a promising therapeutic agent for the treatment of obesity and type 2 diabetes. In this study we sought to determine its role in the dimorphic regulation of energy homeostasis. We tracked male and female WT and CAR deficient (CAR-/-) mice for over a year. During aging, CAR-/- male mice developed hypercortisism, obesity, glucose intolerance, insulin insensitivity, dyslipidemia and hepatic steatosis. Remarkably, the latter modifications were absent, or minor, in female CAR-/- mice. When ovariectomized, CAR-/- female mice developed identical patterns of metabolic disorders as observed in male mice. These results highlight the importance of steroid hormones in the regulation of energy metabolism by CAR. They unveil a sexually dimorphic role of CAR in the maintenance of endocrine and metabolic homeostasis underscoring the importance of considering sex in treatment of metabolic diseases

Patterns of care and outcomes of 417 patients with METAstatic SYNovial sarcoma (METASYN): real-life data from the French Sarcoma Group (FSG)

International audienceBackground: Synovial sarcoma (SS) occurs in both adult and pediatric patients. The primary aim of this study is to describe the outcomes, prognostic factors, and treatment of patients with metastatic SS within a nationwide cohort.Patients and methods: All pediatric and adult patients with metastatic SS are registered in the French Sarcoma Group database. Data were collected from the national database https://conticabase.sarcomabcb.org/ up to March 2020. Descriptive and comparative analyses were conducted using SAS 9.4 and Stata Special Edition 16.1 software.Results: Between January 1981 and December 2019, 417 patients with metastatic SS from 17 French sarcoma centers were included, including 64 (15.3%) under the age of 26 years. Median age was 42.5 years (range 9-87 years). The metastases were synchronous (cohort 1) or metachronous (cohort 2) in 18.9% (N = 79) and 81.1% (N = 338) patients, respectively. Median overall survival (OS) from the date of metastasis was 22.3 months (95% confidence interval 19.7-24.1 months). First-line chemotherapy without ifosfamide and/or doxorubicin was unfavorable for progression-free survival and OS (P 12 months, local therapy, and ifosfamide in the first metastatic line were independent favorable prognostic factors.Conclusions: The outcome of patients with metastatic SS is influenced by local treatment, management in reference centers, and cytotoxic treatments given in the perioperative and metastatic setting

The DEAD box RNA helicase DDX42 is an intrinsic inhibitor of positive‐strand RNA viruses

Genome‐wide screens are powerful approaches to unravel regulators of viral infections. Here, a CRISPR screen identifies the RNA helicase DDX42 as an intrinsic antiviral inhibitor of HIV‐1. Depletion of endogenous DDX42 increases HIV‐1 DNA accumulation and infection in cell lines and primary cells. DDX42 overexpression inhibits HIV‐1 infection, whereas expression of a dominant‐negative mutant increases infection. Importantly, DDX42 also restricts LINE‐1 retrotransposition and infection with other retroviruses and positive‐strand RNA viruses, including CHIKV and SARS‐CoV‐2. However, DDX42 does not impact the replication of several negative‐strand RNA viruses, arguing against an unspecific effect on target cells, which is confirmed by RNA‐seq analysis. Proximity ligation assays show DDX42 in the vicinity of viral elements, and cross‐linking RNA immunoprecipitation confirms a specific interaction of DDX42 with RNAs from sensitive viruses. Moreover, recombinant DDX42 inhibits HIV‐1 reverse transcription in vitro. Together, our data strongly suggest a direct mode of action of DDX42 on viral ribonucleoprotein complexes. Our results identify DDX42 as an intrinsic viral inhibitor, opening new perspectives to target the life cycle of numerous RNA viruses

Étude pluridisciplinaire des mécanismes de contamination des hydrosystèmes continentaux et des zones rivulaires par les métaux (Cd, Zn)

Ce projet recherche du programme ACI-ECCO repose sur une étude pluridisciplinaire des mécanismes de contamination des hydrosystèmes continentaux (cours d'eau et zones rivulaires associées). Dans ce qui suit, nous rapporterons des résultats acquis sur une analyse des flux métalliques du bassin expérimental de Decazeville, sur les premières caractérisations de la spéciation chimique des métaux, de leur biodisponibilité et des impacts toxiques sur la composante biologique des hydrosystèmes. Au terme de cette étude, l'intégration des résultats permettra d'améliorer les connaissances sur les relations entre Écodynamique des métaux-traces et Écotoxicologie et de promouvoir de nouvelles méthodes d'investigation, associant des outils complémentaires à l'interface « Chimie/Géochimie/ Biologie/Écologie/Écotoxicologie »