Local pH variation as an initial step in bacterial surface-sensing and biofilm formation

The development of surface-associated layers of matrix-embedded microbial populations, called biofilms, is a serious problem in many medical and industrial settings. These contaminations are difficult to eradicate because of the high resistance level acquired by the cells in their particular environment. From the very beginning of the colonization process, modifications of gene expression are observed and could, at least partially, explain biofilm resistance. In order to develop anti-biofilm molecules and surface treatments, it is of pivotal importance to identify the physico-chemical parameters which activate the sensor systems of pioneering microbes when they come into contact with a surface. The aim of our study was to examine the pH variations in the local micro-environment created between the cell layer and the surface after bacteria adhesion. Using an ion-sensitive field effect transistor (ISFET), as a substratum, colonized by a curli hyperproducing strain known to form biofilms, we observed that the evolution of the pH change was significantly different in the micro-compartment in contact with the electrochemical sensor compared to that within the liquid phase.     

Historical perspective of heavy metals contamination (Cd, Cr, Cu, Hg, Pb, Zn) in the Seine River basin (France) following a DPSIR approach (1950-2005)

The Driver-Pressures-State-Impact-Response approach is applied to heavy metals in the Seine River catchment (65,000 km(2); 14 million people of which 10 million are aggregated within Paris megacity; 30% of French industrial and agricultural production). The contamination pattern at river mouth is established on the particulate material at different time scales: 1930-2000 for floodplain cores, 1980-2003 for suspended particulate matter (SPM) and bed-sediments, 1994-2003 for atmospheric fallout and annual flood deposits. The Seine has been among the most contaminated catchments with maximum contents recorded at 130 mg kg(-1) for Cd, 24 for Hg, 558 for Pb, 1620 for Zn, 347 for Cu, 275 for Cr and 150 for Ni. Today, the average levels for Cd (1.8 mg kg(-1)), Hg (1.08), Pb (108), Zn (370), Cu (99), Cr (123) and Ni (31) are much lower but still in the upper 90% of the global scale distribution (Cr and Ni excepted) and well above the natural background values determined on pre-historical deposits. All metal contents have decreased at least since 1955/65, well before metal emission regulations that started in the mid 1970's and the metal monitoring in the catchment that started in the early 1980's. In the last 20 y, major criteria changes for the management of contaminated particulates (treated urban sludge, agricultural soils, dredged sediments) have occurred. In the mid 1990's, there was a complete shift in the contamination assessment scales, from sediment management and water usage criteria to the good ecological state, now required by the 2000 European Directive. When comparing excess metal outputs, associated to river SPM, to the average metal demand within the catchment from 1950 to 2000, the leakage ratios decrease exponentially from 1950 to 2000 for Cd, Cr, Cu, Pb and Zn, meanwhile, a general increase of the demand is observed: the rate of recycling and/or treatment of metals within the anthroposphere has been improved ten-fold. Hg environmental trajectory is very specific: there is a marked decontamination from 1970 to 2000, but the leakage ratio remains very high (10 to 20%) during this period. Drivers and Pressures are poorly known prior to 1985; State evolution since 1935 has been reconstructed from flood plain cores analysis; Impacts were maximum between 1950 and 1970 but remained unknown due to analytical limitation and lack of awareness. Some Responses are lagging 10 y behind monitoring and have much evolved in the past 10 y.     

Characterization of plutonium distribution in MIMAS MOX by image analysis

A better understanding of MOX fuel in-pile behaviour requires a very detailed characterization of the Pu distribution in the pellet before and after irradiation. Electron probe microanalysis (EPMA) can be used to determine the distributions of chemical elements with a spatial resolution of 1 μm. This paper describes the development of X-ray microanalysis techniques to produce semi-quantitative ‘maps’ of plutonium concentrations in order to rapidly characterize large areas of the fuel microstructure (1 mm²) with reasonable accuracy. A new segmentation technique based on statistical compatibility is then proposed, so as to finely describe the MIMAS MOX fuel microstructure. Two materials were finely characterized to demonstrate the reliability of this new method. In each case, the results demonstrate the good and reliable accuracy of this new characterization methodology. The analysis method used is currently able to identify three so-called phases (Pu-rich agglomerates, a coating phase and uranium-rich agglomerates), as well as to quantify the plutonium distribution and the plutonium content of these three phases. The impact of the fabrication process on the microstructure can be seen both in the surface distribution variations of the plutonium and in the local plutonium content variations.     

Hypnotic susceptibility and verbal automaticity: Automatic and strategic processing differences in the Stroop color-naming task.

The original hypothesis of M. Dixon et al (1990) that highly hypnotizable (HH) Ss process words more automatically than do low hypnotizable (LH) Ss was retested in a paradigm that separated strategic from automatic processes in the Stroop color-naming task. The words red and blue preceded a color patch that was red or blue. Ss were told that the word predicted the opposite color 75% of the time. Automatic and strategic processes were assessed by varying interstimulus interval (ISI) between the word and the color patch. Both HH and LH Ss showed significant strategic effects (faster incongruent-trial, color-naming reaction times [RTs] than congruent-trial RTs at ISIs over 400 msec), but only HH Ss showed significant automaticity (significantly faster congruent-trial RTs than incongruent-trial RTs at 16.7 msec, the lowest ISI). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detecting Localized Plastic Strain by a Scanning Collinear Wave Mixing Method

When the frequencies of a pair of collinear shear and longitudinal waves satisfy the resonant condition, mixing of these two primary waves generates a third, resonant shear wave that propagates in the direction opposite to the propagating direction of the primary shear wave. In this study, experiments were conducted to demonstrate that the acoustic nonlinearity parameter at the location of the mixing zone can be obtained by measuring the resonant shear wave. Since the location of the mixing zone can be controlled by adjusting the trigger time of the transducers that generate the primary waves, this collinear wave mixing technique enables the scanning of a bar sample to measure the distribution of acoustic nonlinearity along the bar. To demonstrate this scanning capability, bar samples with non-uniform acoustic nonlinearity parameters were fabricated by inducing localized plastic deformation at known locations. Scanning collinear wave mixing tests conducted on such bar samples clearly identified the locations of the plastic zone. These results show that collinear wave mixing is a promising method for scanning the test sample to map out the distribution of localized plastic deformation.     

Development of Anti-LRRC15 Small Fragments for Imaging Purposes Using a Phage-Display ScFv Approach

The human leucine-rich repeat-containing protein 15 (LRRC15) is a membrane protein identified as a marker of CAF (cancer-associated fibroblast) cells whose overexpression is positively correlated with cancer grade and outcome. Nuclear molecular imaging (i.e., SPECT and PET) to track LRRC15 expression could be very useful in guiding further therapeutic strategies. In this study, we developed an ScFv mouse phage-display library to obtain small fragment antibodies against human LRRC15 for molecular imaging purposes. Mice were immunized with recombinant human LRRC15 (hLRRC15), and lymph node cells were harvested for ScFv (single-chain variable fragment) phage-display analysis. The built library was used for panning on cell lines with constitutive or induced expression after transfection. The choice of best candidates was performed by screening various other cell lines, using flow cytometry. The selected candidates were reformatted into Cys-ScFv or Cys-diabody by addition of cysteine, and cloned in mammalian expression vectors to obtain batches of small fragments that were further used in site-specific radiolabeling tests. The obtained library was 1.2 × 10⁷ cfu/µg with an insertion rate >95%. The two panning rounds performed on cells permittedenrichment of 2 × 10⁻³. Screening with flow cytometry allowed us to identify 28 specific hLRRC15 candidates. Among these, two also recognized murine LRCC15 and were reformatted into Cys-ScFv and Cys-diabody. They were expressed transiently in a mammalian system to obtain 1.0 to 4.5 mg of Cys fragments ready for bioconjugation and radiolabeling. Thus, in this paper, we demonstrate the relevance of the phage-display ScFv library approach for the fast-track development of small antibodies for imaging and/or immunotherapy purposes.     

A systematic review of the potential hurdles of interoperability to the emergency services in major incidents: recommendations for solutions and alternatives

This study presents a narrative synthesis of a systematic literature review relating to multi-agency interoperability and major incident decision-making in high risk, high stake environments. The review methodology includes the identification of relevant studies, a critical appraisal of the concepts inherent in the main review question and a narrative synthesis of the central themes that relate to the study as a whole. The review firstly outlines what, currently, appear to be the perceived defining features of successful interoperability by using the SAFE-T phase model of major incident decision-making. It then considers whether these defining features are realistically achievable in major incident practice. Findings suggest that the current definition of an interoperable network is too demanding for the inherent complexity and dynamic nature of the major incident task environment. Individual teams tend to focus on agency-specific behaviour, as opposed to coordinated multi-team functioning, and so collective interoperability is not achieved. Inevitably, this reduces the ability to perform collaborative behaviours, including decision-making and action implementation. The paper concludes that aiming for the current conceptualisation of interoperability along a hierarchical command structure may actually inhibit effective decision-making. Instead, multi-agency systems would do better to work towards an improved understanding of a non-hierarchical and decentralised yet interoperable major incident management network. Recommendations include the need to relate theory and practice in the development of multi-agency decision-making via simulation-based training and to deepen our understanding of interoperability to prevent inertia in high risk, high stake major incident environments.