Influence of hydrological conditions on the Escherichia coli population structure in the water of a creek on a rural watershed.

International audienceBACKGROUND: Escherichia coli is a commensal bacterium of the gastro-intestinal tract of human and vertebrate animals, although the aquatic environment could be a secondary habitat. The aim of this study was to investigate the effect of hydrological conditions on the structure of the E. coli population in the water of a creek on a small rural watershed in France composed of pasture and with human occupation. RESULTS: It became apparent, after studying the distribution in the four main E. coli phylo-groups (A, B1, B2, D), the presence of the hly (hemolysin) gene and the antibiotic resistance pattern, that the E. coli population structure was modified not only by the hydrological conditions (dry versus wet periods, rainfall events), but also by how the watershed was used (presence or absence of cattle). Isolates of the B1 phylo-group devoid of hly and sensitive to antibiotics were particularly abundant during the dry period. During the wet period and the rainfall events, contamination from human sources was predominantly characterized by strains of the A phylo-group, whereas contamination by cattle mainly involved B1 phylo-group strains resistant to antibiotics and exhibiting hly. As E. coli B1 was the main phylo-group isolated in water, the diversity of 112 E. coli B1 isolates was further investigated by studying uidA alleles (beta-D-glucuronidase), the presence of hly, the O-type, and antibiotic resistance. Among the forty epidemiolgical types (ETs) identified, five E. coli B1 ETs were more abundant in slightly contaminated water. CONCLUSIONS: The structure of an E. coli population in water is not stable, but depends on the hydrological conditions and on current use of the land on the watershed. In our study it was the ratio of A to B1 phylo-groups that changed. However, a set of B1 phylo-group isolates seems to be persistent in water, strengthening the hypothesis that they may correspond to specifically adapted strains

A new access control unit for GANIL and SPIRAL 2

International audienceFor the GANIL safety revaluation and the new project of accelerator SPIRAL 2, it was decided to replace theexisting access control system for radiological controlled areas. These areas are all cyclotron rooms and experimental areas. The existing system is centralized around VME cards. Updating is becoming very problematic. The new UGA (access control unit) will becomposed of a pair of PLC to ensure the safety of each room. It will be supplemented by a system UGB (radiological control unit) that will assure the radiological monitoring of the area concerned

Investigating Ramp Wave Propagation inside Silica Glass with Laser Experiments and Molecular Simulations

Under elastic shock compression silica glass exhibits a very specific behaviour. A shock propagating inside a material is usually seen as the propagation of a discontinuity. However in silica glass, shocks are unstable and lead to the propagation of a ramp wave where the shock front becomes gradually larger over time. Ramp waves were already reported in the literature, however their origin remain uncertain. This work presents an original study combining laser shock-induced experiments and molecular dynamics simulation aiming to improve the understanding of the mechanisms involved. Experimental ramp waves were directly observed using shadowgraphy technique allowing for an estimation of the head and tail velocities. Molecular dynamics simulations were carried out in order to reproduce ramp waves and to gain insight into the material properties. Ramp waves were observed for both elastic and plastic shockwaves. In the latter case, the plastic waves were preceded by an elastic ramp precursor. The sound speed, related to the material compressibility, was found to decrease with increasing pressure, as observed experimentally for quasi-static hydrostatic loading, thus providing an explanation for the instabilities that lead to the propagation of ramp waves

Anemone bleaching impacts the larval recruitment success of an anemone-associated fish

In marine environments, mutualisms such as those between corals or sea anemones and their algal symbionts (Symbiodiniaceae) play a key role for supporting surrounding biodiversity. However, as the breakdown of the mutualism between corals and/or anemones and Symbiodiniaceae (i.e. bleaching) become increasingly frequent and severe, the risk of losing the additional species that rely on them may also increase. While the effects of anemone bleaching on the biology and ecology of anemone-associated fishes have been the subject of recent research, relatively little is known about the impacts that anemone bleaching might have on the recruitment of larval fish. Here, we report that climate change-induced anemone bleaching impairs a secondary mutualism between anemones and an anemone-associated fish species, the threespot dascyllus (Dascyllus trimaculatus). Field-based monitoring over a 1-year period showed anemones that bleached experienced decreased recruitment of larval D. trimaculatus compared to those that did not bleach, with abundances of newly settled D. trimaculatus three times lower in bleached versus unbleached anemones. A visual choice experiment showed that this pattern is associated with fish being less attracted to bleached anemones, and a predation experiment demonstrated that fish associated with bleached anemones experienced higher mortality compared to those associated with unbleached anemones. These results suggests that the decreased recruitment of D. trimaculatus observed in bleached anemones may be driven by hampered pre-settlement (habitat selection) and post-settlement (survival to predation) processes for larval D. trimaculatus in bleached hosts. This study highlights the risk of cascading mutualism breakdowns in coral reefs as conditions deteriorate and stresses the importance of protecting these mutualisms for the maintenance of coral reef biodiversity

FMR1 expression in human granulosa cells increases with exon 1 CGG repeat length depending on ovarian reserve

Background: Fragile-X-Mental-Retardation-1- (FMR1)-gene is supposed to be a key gene for ovarian reserve and folliculogenesis. It contains in its 5’-UTR a triplet-base-repeat (CGG), that varies between 26 and 34 in general population. CGG-repeat-lengths with 55–200 repeats (pre-mutation = PM) show instable heredity with a tendency to increase and are associated with premature-ovarian-insufficiency or failure (POI/POF) in about 20%. FMR1-mRNA-expression in leucocytes and granulosa cells (GCs) increases with CGG-repeat-length in PM-carriers, but variable FMR1-expression profiles were also described in women with POI without PM-FMR1 repeat-length. Additionally, associations between low numbers of retrieved oocytes and elevated FMR1-expression levels have been shown in GCs of females with mid-range PM-CGG-repeats without POI. Effects of FMR1-repeat-lengths-deviations (n < 26 or n > 34) below the PM range (n < 55) on ovarian reserve and response to ovarian stimulation remain controversial. Methods: We enrolled 229 women undergoing controlled ovarian hyperstimulation for IVF/ICSI-treatment and devided them in three ovarian-response-subgroups: Poor responder (POR) after Bologna Criteria, polycystic ovary syndrome (PCO) after Rotterdam Criteria, or normal responder (NOR, control group). Subjects were subdivided into six genotypes according to their be-allelic CGG-repeat length. FMR1-CGG-repeat-length was determined using ALF-express-DNA-sequencer or ABI 3100/3130 × 1-sequencer. mRNA was extracted from GCs after follicular aspiration and quantitative FMR1-expression was determined using specific TaqMan-Assay and applying the ΔΔCT method. Kruskall-Wallis-Test or ANOVA were used for simple comparison between ovarian reserve (NOR, POR or PCO) and CGG-subgroups or cohort demographic data. All statistical analysis were performed with SPSS and statistical significance was set at p ≤ 0.05. Results: A statistically significant increase in FMR1-mRNA-expression-levels was detected in GCs of PORs with heterozygous normal/low-CGG-repeat-length compared with other genotypes (p = 0.044). Conclusion: Female ovarian response may be negatively affected by low CGG-alleles during stimulation. In addition, due to a low-allele-effect, folliculogenesis may be impaired already prior to stimulation leading to diminished ovarian reserve and poor ovarian response. A better understanding of FMR1 expression-regulation in GCs may help to elucidate pathomechanisms of folliculogenesis disorders and to develop risk-adjusted treatments for IVF/ICSI-therapy. Herewith FMR1-genotyping potentially provides a better estimatation of treatment outcome and allows the optimal adaptation of stimulation protocols in future

Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces

The band structure and the Fermi level pinning at clean and well-ordered sidewall surfaces of zincblende (ZB)-wurtzite (WZ) GaAs nanowires are investigated by scanning tunneling spectroscopy and density functional theory calculations. The WZ-ZB phase transition in GaAs nanowires introduces p-i junctions at the sidewall surfaces. This is caused by the presence of numerous steps, which induce a Fermi level pinning at different energies on the non-polar WZ and ZB sidewall facets.This study was financially supported by the EQUIPEX program Excelsior, the European Community’s Seventh Framework Program (Grant No. PITN-GA-2012- 316751, “Nanoembrace” Project) and the Impuls- und Vernetzungsfonds of the Helmholtz-Gemeinschaft Deutscher Forschungszentren under Grant No. HIRG-0014. T. Xu acknowledges the support from the National Natural Science Foundation of China (Grant No. 61204014)

Laser fiber and flexible ureterorenoscopy: the safety distance concept

INTRODUCTION The costs of flexible ureterorenoscopes (fURS) and their repair oblige the surgeon to know the proper handling of instruments. There is a lack of evidence in the literature about the safety distance that the laser fiber should have once out from the scope to avoid instrumental damages. MATERIAL AND METHODS We performed an in-vitro observational study. Seven fURS were tested. The distance from the laser fiber tip and the fURS camera was measured at the first appearance on the endoscopic screen and when the fiber was reaching one fourth of the screen. Secondly, to evaluate the impact of the Holmium laser bubble according to the different fiber distances, an assessment of the size and shape of the bubble created at the tip of the fiber with the laser activated was done recording the images with an High Speed Camera. RESULTS The first appearance on the screen of the laser tip is different in different scopes. In all the scopes when observed that when the laser fiber was at \ubc of the screen the bubble was never touching the fURS tip. CONCLUSION Even if there is a big limitation of this study due the impossibility to measure and to evaluate the damage of the fURS tip surface, we observed that when the laser fiber tip reach \ubc of the screen, the bubble generated by the laser activation is never rebounding on the camera of the scope preserving it from laser damages. We can define this position as the "safety distance"

FDG-PET/CT for differentiating between aseptic and septic delayed union in the lower extremity

Background: 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has proven to have a high diagnostic accuracy for the detection of bone infections. In patients with delayed union it may be clinically important to differentiate between aseptic and septic delayed union. The aim of this study was to evaluate the efficacy and to assess the optimal diagnostic accuracy of FDG-PET/CT in differentiating between aseptic and septic delayed union in the lower extremity. Methods: This is a retrospective study of consecutive patients who underwent FDG-PET/CT scanning for suspicion of septic delayed union of the lower extremity. Diagnosis of aseptic delayed union or septic delayed union was made based on surgical deep cultures following PET/CT scanning and information on clinical follow-up. FDG-uptake values were measured at the fractured site by use of the maximum standardized uptake value (SUVmax). Sensitivity, specificity and diagnostic accuracy of FDG-PET/CT were calculated at various SUVmax cut-off points. Results: A total of 30 patients were included; 13 patients with aseptic delayed unions and 17 patients with septic delayed unions. Mean SUVmax in aseptic delayed union patients was 3.23 (SD ± 1.21). Mean SUVmax in septic delayed union patients was 4.77 (SD ± 1.87). A cut-off SUVmax set at 4.0 showed sensitivity, specificity and diagnostic accuracy of FDG-PET/CT were 65, 77 and 70% to differentiate between aseptic and septic delayed union, respectively. Conclusion: Using a semi-quantitative measure (SUVmax) for interpretation of FDG-PET/CT imaging seems to be a promising tool for the discrimination between aseptic and septic delayed union