ALBERT

Description: Coagulase-negative staphylococci are thought to act as reservoirs of antibiotic resistance genes that can be transferred to Staphylococcus aureus , thus hindering the combat of this bacterium. In this work, we analyzed the presence of plasmids conferring resistance to the antibiotic mupirocin—widely used to treat and prevent S. aureus infections in hospital environments—in nosocomial S. haemolyticus strains. About 12% of the 75 strains tested were resistant to mupirocin, and this phenotype was correlated with the presence of plasmids. These plasmids were shown to be diverse, being either conjugative or mobilizable, and capable of transferring mupirocin resistance to S. aureus . Our findings reinforce that S. haemolyticus , historically and mistakenly considered as a less important pathogen, is a reservoir of resistance genes which can be transferred to other bacteria, such as S. aureus , emphasizing the necessity of more effective strategies to detect and combat this emergent opportunistic pathogen.

Description: The aim of this study was to understand the pathogenesis of motile aeromonas septicemia caused by an emergent, high virulent Aeromonas hydrophila (vAh) in channel catfish, Ictalurus punctatus . Adipose fin clipped catfish were challenged with vAh using a waterborne challenge method, and the distribution of vAh over a time course was detected and quantified using real-time polymerase chain reaction. The results showed that 77.8% of fish died within 48 h post challenge with mean day to death of 1.5 days. At 2 h post challenge, vAh (inferred from genomic DNA copies or genome equivalents) was detected in all external and internal tissues sampled. Gill had the highest vAh cells at 1 h post challenge. Spleen harbored the most vAh cells among internal organs at 4 h post challenge. The tissues/organs with most vAh cells detected at 8 h post challenge were adipose fin, blood, intestine, kidney and skin, while liver showed the highest vAh cells at 24 h post challenge. These results suggest that vAh was able to rapidly proliferate and spread, following wound infection, through the fish blood circulation system and cause mortality within 8–24 h.

Description: The terrestrial reference frame is a cornerstone for modern geodesy and its applications for a wide range of Earth sciences. The underlying assumption for establishing a terrestrial reference frame is that the motion of the solid Earth's figure centre relative to the mass centre of the Earth system on a multidecadal timescale is linear. However, past international terrestrial reference frames (ITRFs) showed unexpected accelerated motion in their translation parameters. Based on this underlying assumption, the inconsistency of relative origin motions of the ITRFs has been attributed to data reduction imperfection. We investigated the impact of surface mass loading from atmosphere, ocean, snow, soil moisture, ice sheet, glacier and sea level from 1983 to 2008 on the geocentre variations. The resultant geocentre time-series display notable trend acceleration from 1998 onward, in particular in the z -component. This effect is primarily driven by the hydrological mass redistribution in the continents (soil moisture, snow, ice sheet and glacier). The acceleration is statistically significant at the 99 per cent confidence level as determined using the Mann–Kendall test, and it is highly correlated with the satellite laser ranging determined translation series. Our study, based on independent geophysical and hydrological models, demonstrates that, in addition to systematic errors from analysis procedures, the observed non-linearity of the Earth-system behaviour at interannual timescales is physically driven and is able to explain 42 per cent of the disparity between the origins of ITRF2000 and ITRF2005, as well as the high level of consistency between the ITRF2005 and ITRF2008 origins.

Description: Sensitive instruments like strainmeters and tiltmeters are necessary for measuring slowly varying low amplitude Earth deformations. Nonetheless, laser and fibre interferometers are particularly suitable for interrogating such instruments due to their extreme precision and accuracy. In this paper, a practical design of a simple pendulum borehole tiltmeter based on laser fibre interferometric displacement sensors is presented. A prototype instrument has been constructed using welded borosilicate with a pendulum length of 0.85 m resulting in a main resonance frequency of 0.6 Hz. By implementing three coplanar extrinsic fibre Fabry-Perot interferometric probes and appropriate signal filtering, our instrument provides tilt measurements that are insensitive to parasitic deformations caused by temperature and pressure variations. This prototype has been installed in an underground facility (Rustrel, France) where results show accurate measurements of Earth strains derived from Earth and ocean tides, local hydrologic effects, as well as local and remote earthquakes. The large dynamic range and the high sensitivity of this tiltmeter render it an invaluable tool for numerous geophysical applications such as transient fault motion, volcanic strain and reservoir monitoring.

Description: The activity of levofloxacin against planktonic and biofilm Stenotrophomonas maltophilia cells and the role played by the multidrug efflux pump SmeDEF were evaluated under conditions relevant to the cystic fibrosis (CF) lung. MIC, MBC and MBEC of levofloxacin were assessed, against five CF strains, under ‘standard’ (CLSI-recommended) and ‘CF-like’ (pH 6.8, 5% CO 2 , in a synthetic CF sputum) conditions. Levofloxacin was tested against biofilms at concentrations (10, 50 and 100 μg mL –1 ) corresponding to achievable serum levels and sputum levels by aerosolisation. smeD expression was evaluated, under both conditions, in planktonic and biofilm cells by RT-PCR. The bactericidal effect of levofloxacin was decreased, in three out of five strains tested, under ‘CF-like’ conditions (MBC: 2–4 vs 8–16 μg mL –1 , under ‘standard’ and ‘CF-like’ conditions, respectively). Biofilm was intrinsically resistant to levofloxacin, regardless of conditions tested (MBECs ≥ 100 μg mL –1 for all strains). Only under ‘CF-like’ conditions, smeD expression increased during planktonic-to-biofilm transition, and in biofilm cells compared to stationary planktonic cells. Our findings confirmed that S. maltophilia biofilm is intrinsically resistant to therapeutic concentrations of levofloxacin. Under conditions relevant to CF, smeD overexpression could contribute to levofloxacin resistance. Further studies are warranted to define the clinical relevance of our findings .

Description: We review the theory of the Earth's elastic and gravitational response to a surface disk load. The solutions for displacement of the surface and the geoid are developed using expansions of Legendre polynomials, their derivatives and the load Love numbers. We provide a matlab  function called diskload that computes the solutions for both uncompensated and compensated disk loads. In order to numerically implement the Legendre expansions, it is necessary to choose a harmonic degree, n max , at which to truncate the series used to construct the solutions. We present a rule of thumb (ROT) for choosing an appropriate value of n max , describe the consequences of truncating the expansions prematurely and provide a means to judiciously violate the ROT when that becomes a practical necessity.

Description: In autumn 2012, the new release 05 (RL05) of monthly geopotencial spherical harmonics Stokes coefficients (SC) from Gravity Recovery and Climate Experiment (GRACE) mission was published. This release reduces the noise in high degree and order SC, but they still need to be filtered. One of the most common filtering processing is the combination of decorrelation and Gaussian filters. Both of them are parameters dependent and must be tuned by the users. Previous studies have analyzed the parameters choice for the RL05 GRACE data for oceanic applications, and for RL04 data for global application. This study updates the latter for RL05 data extending the statistics analysis. The choice of the parameters of the decorrelation filter has been optimized to: (1) balance the noise reduction and the geophysical signal attenuation produced by the filtering process; (2) minimize the differences between GRACE and model-based data and (3) maximize the ratio of variability between continents and oceans. The Gaussian filter has been optimized following the latter criteria. Besides, an anisotropic filter, the fan filter, has been analyzed as an alternative to the Gauss filter, producing better statistics.

Description: Activating transcription factor 3 (ATF3) is a stress-induced transcriptional regulator in eukaryote. The role of ATF3 in cancer has been well defined, but how ATF3 functions in bacterial infection is not well understood. Pneumococcal infection has been shown to induce ATF3 expression, which subsequently enhances cytokine production and provides protection from lethal Streptococcus pneumoniae infection, but the role of ATF3 in other Gram-positive (G + ) infections remains unclear. Here, we report that infection with other G + bacteria ( Staphylococcus aureus and Listeria monocytogenes ) and with G – bacteria (uropathogenic Escherichia coli ) also significantly induced ATF3 expression. Moreover, the production of cytokines (tumor necrosis factor alpha [TNF]-α, interleukin [IL]-1β, IL-6 and interferon [IFN]-) was enhanced by ATF3 in S. aureus and L. monocytogenes infection, but decreased in uropathogenic E. coli (UPEC) infection. In addition, in S. aureus and L. monocytogenes infections, ATF3 WT mice cleared bacteria more efficiently and had higher survival rates than ATF3 knockout mice. However, in UPEC infection, no significant difference was found in survival rate. Taken together, these data suggest that ATF3 provides protection from S. aureus and L. monocytogenes infections; however, the role of ATF3 in UPEC infection is more complicated and should be further elucidated.

Description: In the present work we illustrate a new local inversion algorithm to retrieve the Moho depth from GOCE (Gravity field and steady-state Ocean Circulation Explorer) gravity field. In details the proposed procedure can be divided into two main steps: the first one consists in recognizing and isolating the different geological provinces in the study area by exploiting information coming from the GOCE global gravity field model. Once the main geological provinces are defined, a function relating the crust density of each province with depth is built and used to reduce the data. The gravitational effects of sediments, topography, bathymetry and upper mantle are also removed. In the second step the residual gravitational field is inverted to retrieve the Moho depth and some information on the crustal density. In particular, the clustering of geological province is performed by means of an automatic Bayesian classification algorithm while the inversion of GOCE residual field is performed by adapting the global algorithm developed in the framework of the GEMMA project to the local scale. The procedure, based on an iterative Wiener filter, allows to compute the Moho depth considering lateral as well as radial variations of crustal density. The algorithm has been applied to the fifth release of GOCE time-wise global gravity field model to infer information on the crustal structure in the Western Balkan area, that is, the region laying between Bulgaria and the Adriatic Sea. This region is one of the most complex and active, from the tectonic point of view, in the whole Europe and it is characterized by the presence of the Alpine-Himalayan orogenic belt, formed by the collision between the African and Eurasian plates, and by the opening of the Pannonian Basin. Results show a good agreement between the obtained geological provinces with the actual knowledge on the region. The resulting Moho depth ranges between about 20 km beneath the Adriatic Sea and 45 km in the Dinarides. Comparisons with available seismic data show differences smaller than 1 km (standard deviation).

Description: Enteroaggregative Escherichia coli (EAEC) is an important diarrhoeal pathogen causing diseases in multiple epidemiological and clinical settings. In developing countries like India, diarrhoeal diseases are one of the major killers among paediatric population and oddly, few studies are available from Indian paediatric population on the variability of EAEC virulence genes. In this study, we examined the distribution of plasmid and chromosomal-encoded virulence determinants in EAEC isolates, and analysed cytokines response generated against EAEC with specific aggregative adherence fimbriae (AAF) type in duodenal biopsies using in vitro organ culture (IVOC) mimicking in vivo conditions. Different virulence marker combinations among strains were reflected as a function of specific adhesins signifying EAEC heterogeneity. fis gene emerged as an important genetic marker apart from aggA and aap . Further, EAEC infection in IVOC showed upregulation of IL-8, IL-1β, IL-6, TNF-α and TLR-5 expression. EAEC with AAFII induced significant TLR-5 and IL-8 response, conceivably owing to more pathogenicity markers. This study sheds light on the pattern of EAEC pathotypes prevalent in North Indian paediatric population and highlights the presence of unique virulence combinations in pathogenic strains. Thus, evident diversity in EAEC virulence and multifaceted bacteria-host crosstalk can provide useful insights for the strategic management of diarrhoeal diseases in India, where diarrhoeal outbreaks are more frequent.