Self-assembled monolayers of bisphosphonates: Influence of side chain steric hindrance

Bisphosphonates form self-assembled monolayers (SAMs) spontaneously on stainless steel, silicon, and titanium oxidized surfaces. We used contact angle measurements, atomic force microscopy, and X-ray reflectivity analysis to study the formation of SAMs on a model surface of ultraflat titanium (rms=0.2 nm). The results were extended to standard materials (mechanically polished titanium, stainless steel, and silicon) and showed that water-soluble bisphosphonic perfluoropolyether can easily form SAMs, with 100% surface coverage and a layer thickness of less than 3 nm. Hydrophobic (water contact angle >110° on stainless steel or titanium) and lipophobic (methylene iodide contact angle >105° on titanium) properties are discussed in terms of industrial applications

Dendritic Cell-Mediated-Immunization with Xenogenic PrP and Adenoviral Vectors Breaks Tolerance and Prolongs Mice Survival against Experimental Scrapie

In prion diseases, PrPc, a widely expressed protein, is transformed into a pathogenic form called PrPSc, which is in itself infectious. Antibodies directed against PrPc have been shown to inhibit PrPc to PrPSc conversion in vitro and protect in vivo from disease. Other effectors with potential to eliminate PrPSc-producing cells are cytotoxic T cells directed against PrP-derived peptides but their ability to protect or to induce deleterious autoimmune reactions is not known. The natural tolerance to PrPc makes difficult to raise efficient adaptive responses. To break tolerance, adenovirus (Ad) encoding human PrP (hPrP) or control Ad were administered to wild-type mice by direct injection or by transfer of Ad-transduced dendritic cells (DCs). Control Ad-transduced DCs from Tg650 mice overexpressing hPrP were also used for immunization. DC-mediated but not direct administration of AdhPrP elicited antibodies that bound to murine native PrPc. Frequencies of PrP-specific IFNγ-secreting T cells were low and in vivo lytic activity only targeted cells strongly expressing hPrP. Immunohistochemical analysis revealed that CD3+ T cell infiltration was similar in the brain of vaccinated and unvaccinated 139A-infected mice suggesting the absence of autoimmune reactions. Early splenic PrPSc replication was strongly inhibited ten weeks post infection and mean survival time prolonged from 209 days in untreated 139A-infected mice to 246 days in mice vaccinated with DCs expressing the hPrP. The efficacy appeared to be associated with antibody but not with cytotoxic cell-mediated PrP-specific responses

Early detection of West Nile virus in France: quantitative assessment of syndromic surveillance system using nervous signs in horses

West Nile virus (WNV) is a growing public health concern in Europe and there is a need todevelop more efficient early detection systems. Nervous signs in horses are considered to be anearly indicator of WNV and, using them in a syndromic surveillance system, might be relevant.In our study, we assessed whether or not data collected by the passive French surveillance systemfor the surveillance of equine diseases can be used routinely for the detection of WNV. We testedseveral pre-processing methods and detection algorithms based on regression. We evaluatedsystem performances using simulated and authentic data and compared them to those of thesurveillance system currently in place. Our results show that the current detection algorithmprovided similar performances to those tested using simulated and real data. However, regressionmodels can be easily and better adapted to surveillance objectives. The detection performancesobtained were compatible with the early detection of WNV outbreaks in France (i.e. sensitivity98%, specificity >94%, timeliness 2·5 weeks and around four false alarms per year) but furtherwork is needed to determine the most suitable alarm threshold for WNV surveillance in Franceusing cost-efficiency analysis

Influence of water on the circulation of the West Nile Virus in horses in Southern France

National audienc

Oligosaccharide induced resistance in grapevine as affected by cuticle permeability

International audienceGrapevine is susceptible to many diseases such as downy mildew, caused by the oomycete Plasmopara viticola (Pv). Sulfated laminarin PS3 is obtained by chemical sulfation of laminarin, an oligosaccharide (OS) from the brown algae Laminaria digitata. PS3 has been shown to elicit plant defense reactions and to induce resistance against Pv in grapevine (1). Our aim is to understand the penetration of OS in the grapevine leaf and to correlate it with the resistance induced against Pv. For this purpose, we followed the uptake of labeled compounds in the leaf, the effect of different adjuvants on their penetration and PS3 efficacy in Pv resistance tests. 1. S. Trouvelot, A. Varnier, M. Allegre, L. Mercier, F. Baillieul, C. Arnould, V. Gianinazzi-Pearson, O. Klarzynski, J. M. Joubert, A. Pugin, X. Daire Mol Plant Microbe Interact. 21, 232-243 (2008)

Expanded single-mode fiber using graded index multimode fiber

International audienceA compact large Gaussian mode field diameter single-mode fiber is developed. This expanded single-mode fiber consists of splicing fibers with various lengths and characteristics. The principle of this optical arrangement is to excite the first mode of propagation of the multimode graded index to preserve a Gaussian field. The coupling properties are numerically analyzed, considering the effects of gap, radial offset, and tilt. The fiber connections loss between the same kinds of expanded single-mode fibers with a Gaussian mode field diameter of 18 µm is measured with an average of 0.55 dB. This large mode field diameter is preserved on a long length of fiber >20 cm

Circulation of a Meaban-like virus in yellow-legged gulls and seabird ticks in the western Mediterranean Basin

In recent years, a number of zoonotic flaviviruses have emerged worldwide, and wild birds serve as their major reservoirs. Epidemiological surveys of bird populations at various geographical scales can clarify key aspects of the eco-epidemiology of these viruses. In this study, we aimed at exploring the presence of flaviviruses in the western Mediterranean by sampling breeding populations of the yellow-legged gull (Larus michahellis), a widely distributed, anthropophilic, and abundant seabird species. For 3 years, we sampled eggs from 19 breeding colonies in Spain, France, Algeria, and Tunisia. First, ELISAs were used to determine if the eggs contained antibodies against flaviviruses. Second, neutralization assays were used to identify the specific flaviviruses present. Finally, for colonies in which ELISA-positive eggs had been found, chick serum samples and potential vectors, culicid mosquitoes and soft ticks (Ornithodoros maritimus), were collected and analyzed using serology and PCR, respectively. The prevalence of flavivirus-specific antibodies in eggs was highly spatially heterogeneous. In northeastern Spain, on the Medes Islands and in the nearby village of L'Escala, 56% of eggs had antibodies against the flavivirus envelope protein, but were negative for neutralizing antibodies against three common flaviviruses: West Nile, Usutu, and tick-borne encephalitis viruses. Furthermore, little evidence of past flavivirus exposure was obtained for the other colonies. A subset of the Ornithodoros ticks from Medes screened for flaviviral RNA tested positive for a virus whose NS5 gene was 95% similar to that of Meaban virus, a flavivirus previously isolated from ticks of Larus argentatus in western France. All ELISA-positive samples subsequently tested positive for Meaban virus neutralizing antibodies. This study shows that gulls in the western Mediterranean Basin are exposed to a tick-borne Meaban-like virus, which underscores the need of exploring the spatial and temporal distribution of this flavivirus as well as its potential pathogenicity for animals and humans

Dynamic behaviour of a monolithic suspension device for the French watt balance experiment

In the French watt balance experiment, in order to have a single point of application of a weight and an electromagnetic force balancing this weight, a system of double gimbals with flexure pivots was made out of copper-beryllium alloy. This allows the articulation of the suspension devices of the mass (generating the weight) and coil (on which the electromagnetic force acts) around four coplanar axes which intersect at one point (equivalent to a virtual centre of rotation). The study of the free dynamic behaviour under vacuum of this device dealt with resonance, damping due to internal friction of the material and coupling between the two systems of gimbals. The results obtained show that this novel device presents suitable characteristics for concentrating two different forces at a single point and aligning them around a common vertical axis. It can be used not only for watt balance experiments but also for any other mechanical applications where alignment and concentration of two forces are necessary