Nationwide Surveillance of Nasopharyngeal Streptococcus pneumoniae Isolates from Children with Respiratory Infection, Switzerland, 1998-1999

The surveillance of pneumococcal antibiotic resistance and serotype distribution is hampered by the relatively low numbers of invasive pneumococcal infections. In Switzerland, a nationwide sentinel surveillance network was used to assess antibiotic resistance and serotype distribution among 1179 pneumococcal isolates cultured from 2769 nasopharyngeal swabs obtained from outpatients with acute otitis media or pneumonia during 1998 and 1999. The proportion of penicillin-susceptible pneumococcal isolates overall (87%) and among infants <2 years old (81%) was comparable to that of invasive isolates (90% and 81%, respectively). The high number of nasopharyngeal isolates allowed for the detection of a rapid increase in the number of penicillin-nonsusceptible pneumococcal (PNSP) strains in the West region of Switzerland, partly because of an epidemic caused by the 19F clone of Streptococcus pneumoniae. Clustering of risk factors for the carriage of PNSP isolates further explained the geographic variation in resistance rates. The nationwide sentinel surveillance of nasopharyngeal pneumococcus proved to be valuable for the monitoring of antibiotic resistance, risk factors for carriage of PNSP isolates, and serotype distribution and for the detection of the emergence of a new epidemic clon

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Antirabies vaccination of dogs by oral way in Tunisia. Assay with baits and two attenuated virus vaccines

Quatre types d’appâts ont été testés simultanément sur 200 chiens (50 chiens/type d’appât). L’appât “tête de poulet”-TP a été significativement le meilleur appât, avec un pourcentage d’acceptation de 96% et un taux de succès vaccinal de 94 % ; l’appât industriel à base de “farine de poisson”-FP a occupé la seconde position avec un taux d’acceptation de 80% et un taux de succès vaccinal de 62%. L’essai de deux vaccins à virus atténués dérivés de la souche S AD, SAD Berne et SAG 1, a par ailleurs confirmé l’immunogénicité par la voie orale de ces souches chez le chien, et encourage donc à envisager ce mode de vaccination chez cette espèce, en complément de la vaccination par voie parentérale

Vaccination antirabique des chiens par voie orale en Tunisie. Essai d’appâts et de deux vaccins à virus atténués

Quatre types d’appâts ont été testés simultanément sur 200 chiens (50 chiens/type d’appât). L’appât “tête de poulet”-TP a été significativement le meilleur appât, avec un pourcentage d’acceptation de 96% et un taux de succès vaccinal de 94% ; l’appât industriel à base de “farine de poisson”-FP a occupé la seconde position avec un taux d’acceptation de 80% et un taux de succès vaccinal de 62%. L’essai de deux vaccins à virus atténués dérivés de la souche SAD, SAD Berne et SAG 1, a par ailleurs confirmé l’immunogénicité par la voie orale de ces souches chez le chien, et encourage donc à envisager ce mode de vaccination chez cette espèce, en complément de la vaccination par voie parentérale.Haddad Nadia, Ben Khelifa Leïla, Matter Hans C., Flamand Anne, Wandeler Alexander I. Vaccination antirabique des chiens par voie orale en Tunisie. Essai d’appâts et de deux vaccins à virus atténués. In: Bulletin de l'Académie Vétérinaire de France tome 146 n°3, 1993. pp. 327-336

Förster Resonance Energy Transfer between Colloidal CuInS2/ZnS Quantum Dots and Dark Quenchers

Förster resonance energy transfer (FRET) using colloidal semiconductor quantum dots (QDs) and dyes is of importance in a wide range of biological and biophysical studies. Here, we report a study on FRET between CuInS2/ZnS QDs and dark quencher dye molecules (IRDye QC-1). Oleate-capped QDs with photoluminescence quantum yields (PLQYs) of 55 ± 4% are transferred into water by using two types of multifunctional polymer ligands combining imidazole groups and specific moieties with amine or methoxy groups as the terminal sites. The resulting water-dispersible QDs show PLQYs as high as 44 ± 4% and exhibit long-term colloidal stability (at least 10 months at 4 °C in the dark) with a hydrodynamic diameter of less than 20 nm. A side-by-side comparison experiment was performed using the amine or methoxy-functionalized QDs for coupling to dark quencher dye molecules. The amine-functionalized QDs bind to the dye molecules via covalent bonds, while methoxy-functionalized ones bind only weakly and nonspecifically. The progressive quenching of the QD emission and shortening of its photoluminescence decay time upon increasing the number of conjugated dye molecules demonstrate that the QD acts as the energy donor and the dark quencher dye as the energy acceptor in a donor-acceptor FRET pair. The FRET dynamics of the QD-dye conjugates are simulated using two different models based on the possible origin of the multiexponential PL decay of the QDs (i.e., variations in nonradiative or radiative decay rates). The model based on the radiative decay rates provides a better fit of our experimental data and estimates a donor-acceptor distance (6.5 nm) that matches well the hydrodynamic radius of the amine-functionalized QDs

Fluorescently Labelled Silica Coated Gold Nanoparticles as Fiducial Markers for Correlative Light and Electron Microscopy

In this work, gold nanoparticles coated with a fluorescently labelled (rhodamine B) silica shell are presented as fiducial markers for correlative light and electron microscopy (CLEM). The synthesis of the particles is optimized to obtain homogeneous, spherical core-shell particles of arbitrary size. Next, particles labelled with different fluorophore densities are characterized to determine under which conditions bright and (photo)stable particles can be obtained. 2 and 3D CLEM examples are presented where optimized particles are used for correlation. In the 2D example, fiducials are added to a cryosection of cells whereas in the 3D example cells are imaged after endocytosis of the fiducials. Both examples demonstrate that the particles are clearly visible in both modalities and can be used for correlation. Additionally, the recognizable core-shell structure of the fiducials proves to be very powerful in electron microscopy: it makes it possible to irrefutably identify the particles and makes it easy to accurately determine the center of the fiducials

3D test sample for the calibration and quality control of stimulated emission depletion (STED) and confocal microscopes

Multiple samples are required to monitor and optimize the quality and reliability of quantitative measurements of stimulated emission depletion (STED) and confocal microscopes. Here, we present a single sample to calibrate these microscopes, align their laser beams and measure their point spread function (PSF) in 3D. The sample is composed of a refractive index matched colloidal crystal of silica beads with fluorescent and gold cores. The microscopes can be calibrated in three dimensions using the periodicity of the crystal; the alignment of the laser beams can be checked using the reflection of the gold cores; and the PSF can be measured at multiple positions and depths using the fluorescent cores. It is demonstrated how this sample can be used to visualize and improve the quality of STED and confocal microscopy images. The sample is adjustable to meet the requirements of different NA objectives and microscopy techniques and additionally can be used to evaluate refractive index mismatches as a function of depth quantitatively