Radiation resistant single-mode fiber with different coatings for sensing in high dose environments

A radiation resistant single-mode optical fiber has been specifically developed for distributed sensing in harsh environments associated with MGy(SiO2) dose radiation. Different types of coating have been used: acrylate, polyimide, aluminum that allow extending the range of accessible temperatures up to 400°C. Various characterizations were performed: radiation inducted attenuation (offline and online), fiber mechanical strength and coating thermal degradation post irradiation. Safe operation is demonstrated for almost all coating types up to the MGy(SiO2) range of cumulated dose

Phosphosilicate Multimode Optical Fiber for Sensing and Diagnostics at Inertial Confinement Fusion Facilities

We characterized the radiation response in the visible domain of a new multimode graded-index (GI) phosphosilicate optical fiber (GIMMF), exposed to the harsh environment (pulses of 14-MeV neutrons, X-rays, and γ -rays) associated with laser experiments at the OMEGA facility. The growth of permanent radiation-induced attenuation (RIA) was measured in situ after a series of laser shots involving a large production of 14-MeV neutrons (yields > 10^14 n per shot). RIA linearly increases with accumulated neutron fluence without recovery between shots. The obtained results allow a precise evaluation of this GIMMF vulnerability when implemented as part of laser or plasma diagnostics. Our work also reveals the potential of this class of optical fiber to serve as a radiation monitor in the radiation-rich mixed environments of megajoule class laser facilities and to provide a very fast and online estimation of the accumulated deposited dose at various locations of their experimental halls. In our experimental test configuration at OMEGA, 14-MeV neutrons are estimated to contribute to about 55% of the total deposited dose on the fibers, and the other optical losses are related to X-ray and γ -ray contributions. Those measurements could be, for example, benchmarked to the radiation maps obtained by Monte Carlo simulation tools, potentially facilitating the evaluation of the aging of diagnostics, components, and systems as well as their maintenance operations

An original phylogenetic approach identified mitochondrial haplogroup T1a1 as inversely associated with breast cancer risk in BRCA2 mutation carriers

Introduction: Individuals carrying pathogenic mutations in the BRCA1 and BRCA2 genes have a high lifetime risk of breast cancer. BRCA1 and BRCA2 are involved in DNA double-strand break repair, DNA alterations that can be caused by exposure to reactive oxygen species, a main source of which are mitochondria. Mitochondrial genome variations affect electron transport chain efficiency and reactive oxygen species production. Individuals with different mitochondrial haplogroups differ in their metabolism and sensitivity to oxidative stress. Variability in mitochondrial genetic background can alter reactive oxygen species production, leading to cancer risk. In the present study, we tested the hypothesis that mitochondrial haplogroups modify breast cancer risk in BRCA1/2 mutation carriers. Methods: We genotyped 22,214 (11,421 affected, 10,793 unaffected) mutation carriers belonging to the Consortium of Investigators of Modifiers of BRCA1/2 for 129 mitochondrial polymorphisms using the iCOGS array. Haplogroup inference and association detection were performed using a phylogenetic approach. ALTree was applied to explore the reference mitochondrial evolutionary tree and detect subclades enriched in affected or unaffected individuals. Results: We discovered that subclade T1a1 was depleted in affected BRCA2 mutation carriers compared with the rest of clade T (hazard ratio (HR) = 0.55; 95% confidence interval (CI), 0.34 to 0.88; P = 0.01). Compared with the most frequent haplogroup in the general population (that is, H and T clades), the T1a1 haplogroup has a HR of 0.62 (95% CI, 0.40 to 0.95; P = 0.03). We also identified three potential susceptibility loci, including G13708A/rs28359178, which has demonstrated an inverse association with familial breast cancer risk. Conclusions: This study illustrates how original approaches such as the phylogeny-based method we used can empower classical molecular epidemiological studies aimed at identifying association or risk modification effects.Peer reviewe

An original phylogenetic approach identified mitochondrial haplogroup T1a1 as inversely associated with breast cancer risk in BRCA2 mutation carriers

Abstract Introduction Individuals carrying pathogenic mutations in the BRCA1 and BRCA2 genes have a high lifetime risk of breast cancer. BRCA1 and BRCA2 are involved in DNA double-strand break repair, DNA alterations that can be caused by exposure to reactive oxygen species, a main source of which are mitochondria. Mitochondrial genome variations affect electron transport chain efficiency and reactive oxygen species production. Individuals with different mitochondrial haplogroups differ in their metabolism and sensitivity to oxidative stress. Variability in mitochondrial genetic background can alter reactive oxygen species production, leading to cancer risk. In the present study, we tested the hypothesis that mitochondrial haplogroups modify breast cancer risk in BRCA1/2 mutation carriers. Methods We genotyped 22,214 (11,421 affected, 10,793 unaffected) mutation carriers belonging to the Consortium of Investigators of Modifiers of BRCA1/2 for 129 mitochondrial polymorphisms using the iCOGS array. Haplogroup inference and association detection were performed using a phylogenetic approach. ALTree was applied to explore the reference mitochondrial evolutionary tree and detect subclades enriched in affected or unaffected individuals. Results We discovered that subclade T1a1 was depleted in affected BRCA2 mutation carriers compared with the rest of clade T (hazard ratio (HR) = 0.55; 95% confidence interval (CI), 0.34 to 0.88; P = 0.01). Compared with the most frequent haplogroup in the general population (that is, H and T clades), the T1a1 haplogroup has a HR of 0.62 (95% CI, 0.40 to 0.95; P = 0.03). We also identified three potential susceptibility loci, including G13708A/rs28359178, which has demonstrated an inverse association with familial breast cancer risk. Conclusions This study illustrates how original approaches such as the phylogeny-based method we used can empower classical molecular epidemiological studies aimed at identifying association or risk modification effects

Detectable clonal mosaicism and its relationship to aging and cancer

In an analysis of 31,717 cancer cases and 26,136 cancer-free controls from 13 genome-wide association studies, we observed large chromosomal abnormalities in a subset of clones in DNA obtained from blood or buccal samples. We observed mosaic abnormalities, either aneuploidy or copy-neutral loss of heterozygosity, of >2 Mb in size in autosomes of 517 individuals (0.89%), with abnormal cell proportions of between 7% and 95%. In cancer-free individuals, frequency increased with age, from 0.23% under 50 years to 1.91% between 75 and 79 years (P = 4.8 × 10(-8)). Mosaic abnormalities were more frequent in individuals with solid tumors (0.97% versus 0.74% in cancer-free individuals; odds ratio (OR) = 1.25; P = 0.016), with stronger association with cases who had DNA collected before diagnosis or treatment (OR = 1.45; P = 0.0005). Detectable mosaicism was also more common in individuals for whom DNA was collected at least 1 year before diagnosis with leukemia compared to cancer-free individuals (OR = 35.4; P = 3.8 × 10(-11)). These findings underscore the time-dependent nature of somatic events in the etiology of cancer and potentially other late-onset diseases

Surveillance of serotypes and antimicrobial susceptibility profile in group B streptococcus (GBS) in Belgium

peer reviewedBACKGROUND Today GBS vaccines for prevention of severe neonatal disease through transplacental delivery of antibodies directly from immunized mothers are in advanced stage of development. For the introduction of any GBS vaccine there are urgent needs for pre and post vaccine enhanced surveillance studies of strains isolated from both neonatal diseases and vagino-rectal colonization of pregnant women. In Belgium, surveillance of invasive isolates is regularly done by the NRC. We report in this study a surveillance of colonizing isolates of GBS. METHODS In 2012, 344 GBS isolates were obtained from a Belgian surveillance for vagino-rectal colonization among pregnant women (max. 5 isolates/lab). Capsular types were determined by agglutination (Strep-B-latex, SSI, Denmark) and MICs by using a microdilution method (Sensititre) and Etest® (EUCAST interpretive criteria). Furthermore, for the erythromycin (E) resistant (R) isolates, the inducible (iMLS), constitutive (cMLS) and M phenotypes were assessed by a double-disk diffusion test. RESULTS Serotype III was the more common (27.6%) followed by V, II, Ia, Ib, IV, IX, VII and VI (18.1%, 16.4%, 13.4%, 7%, 4.7%, 2.5%, 0.8%, 0.5%) and 8.9% were non typable. All isolates were susceptible to penicillin ; 29% were R to E with a higher rate among serotypes IV and V (p256 mg/L and 27% iMLS with E MIC50/MIC90 2/>8 mg/L. The M phenotype (R to E and S to C) was expressed by 7% of E-R isolates with E MIC50/MIC90 2/4 mg/L. CONCLUSION Compared with Belgian data relating to neonatal invasive strains (NRC reports) 1) Serotype V and II are more frequent and III less frequent among colonizing isolates 2) Prevalence of E-R is similar in percentage and phenotypes with the MLS R phenotype as major mechanism. Extended surveillance of both invasive and colonizing isolates is needed currently to prepare the follow-up in the future vaccine era

Improvement of transport condition of swabs for group B streptococcal (GBS) screening

peer reviewedBACKGROUND For the screening-based strategy for prevention of perinatal GBS disease, CDC Guidelines as many others recommend use of appropriate transport media (Amies, Stuart, e.g.) and processing of specimen as soon as possible within 1 to 4 days. False negative cultures occur for several causes including lost of GBS viability during transport. Could Lim broth, recommended for the selective enrichment, and Granada tubes be used as transport media for swab? Simulating conditions of routine practice, Lim broth and Granada tubes, were evaluated in vitro as transport media. METHODS Tubes of 3 brands of Lim broth (Becton Dickinson, bioMérieux, Copan) and Granada tubes (bioMérieux) were inoculated with low inocula of 10-100 CFU of GBS. Each type of tubes was incubated at 4°C, room T° (RT) and 35°C. GBS were enumerated from each tube by subculture on blood agar after 1, 2, 3 and 4 days of storage at the different T°. All tests were processed in triplicates with 3 strains of GBS belonging to serotype Ia, III and V. RESULTS No difference of survival was observed between the 3 strains. T° had significant impact on GBS recovery for each type of tubes. At 4°C the viability was hardly sustained along the 4 days. At RT and 35°C, an increase >6 log of the inocula was observed. The increase of GBS density was sustained at least 4 days for the 3 brands of Lim broth. For the Granada broth, such increase was also observed but at day 3 for tubes incubated at 35°C, viability decreased and for some tubes, GBS subcultures were negative at day 3 or 4. CONCLUSION To improve sensitivity of GBS screening cultures, Lim broth could be recommended as a strong transport media and the advisable storage condition would be RT to 35°C up to 4 days. In this way, initiating selective enrichment culture at the time of collection of specimen would provide higher sensitivity even for low density of colonization. Transport at 4°C should be avoided in favour with RT to 35°C. Studies in clinical setting are expected. For Granada tubes, storage at RT was fine but improvement seemed restricted in time at 35°C as there was a loss of viability after 3 days. For Granada tubes, extended evaluation and delimitation of use are needed

METERO-V experimental set-up: presentation and first results. Uniform flows through a 8x34 PWR-type rod bundle with mixing grids at Reynolds number ranging from 800 to 70000: pressure loss measurements

International audienceWe present the METERO-V set-up and preliminary results from the first set of experiments performed. METERO-V is a closed loop, equipped with a test section made of two halves of PWR-type rod bundles (8x34 rods) at full scale. The set up allows independent injection of different flow rates and temperatures at the inlet of each half of rod bundles. METERO-V experimental program focuses on IBLOCA (Intermediate Break Loss of Coolant Accident), SBLOCA (Small Break) and SLB (Steam Line Break) situations where significant 3D effects may occur in the core, with the aim to develop models and to validate them in a separated-effect way for CFD to system thermal-hydraulic scales. We present the preliminary results for a homogeneous inflow, varying the Reynolds number from laminar regime to fully turbulent regime. We measure pressure loss along the flow, across the grids and for the bare bundle. The axial pressure drop is successfully compared with available literature models and experimental data. Reproducibility and accuracy of the measurements is also very good. Future work will consist in non-symmetrical injections: velocities and/or temperatures

Uniform and non-uniform flows through a PWR-type rod bundle with mixing grids at Reynolds number ranging from 800 up to 70000: pressure loss measurements

International audienceWe present two sets of experiments performed on the METERO-V set-up. METERO-V is a closed loop, equipped with a test section made of two halves of PWR-type rod bundles (8x34 rods) at full scale. The set up allows injection of different flow rates and temperatures at the inlet of each half of rod bundles. METERO-V experimental program focuses on IBLOCA (Intermediate Break Loss of Coolant Accident), SBLOCA (Small Break) and SLB (Steam Line Break) situations where significant 3D effects may occur in the core, with the aim to develop models and to validate them in a separated-effect way for CFD to system thermal-hydraulic scales. We present preliminary results for a homogeneous inflow, varying the Reynolds number from laminar regime to fully turbulent regime. We measure pressure loss along the flow, across the grids and for the bare bundle. For non-symmetrical inlet velocity, we measure also transverse pressure across the test section at different elevations. For the homogeneous injections, the axial pressure drop is successfully compared with available literature models and experimental data. Principle of tests in non-symmetrical configuration is presented