Surgical Mask to Prevent Influenza Transmission in Households: A Cluster Randomized Trial

Facemasks and respirators have been stockpiled during pandemic preparedness. However, data on their effectiveness for limiting transmission are scarce. We evaluated the effectiveness of facemask use by index cases for limiting influenza transmission by large droplets produced during coughing in households.A cluster randomized intervention trial was conducted in France during the 2008-2009 influenza season. Households were recruited during a medical visit of a household member with a positive rapid influenza A test and symptoms lasting less than 48 hours. Households were randomized either to the mask or control group for 7 days. In the intervention arm, the index case had to wear a surgical mask from the medical visit and for a period of 5 days. The trial was initially intended to include 372 households but was prematurely interrupted after the inclusion of 105 households (306 contacts) following the advice of an independent steering committee. We used generalized estimating equations to test the association between the intervention and the proportion of household contacts who developed an influenza-like illness during the 7 days following the inclusion. Influenza-like illness was reported in 24/148 (16.2%) of the contacts in the intervention arm and in 25/158 (15.8%) of the contacts in the control arm and the difference between arms was 0.40% (95%CI: -10% to 11%, P = 1.00). We observed a good adherence to the intervention. In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.This study should be interpreted with caution since the lack of statistical power prevents us to draw formal conclusion regarding effectiveness of facemasks in the context of a seasonal epidemic.clinicaltrials.gov NCT00774774

Molecular dynamics to rationalize EXAFS experiments : a dynamical model explaining hydration behaviour across the lanthanoid(III) series

International audienceIn this paper we show how polarizable molecular dynamics can be successfully used to understand lanthanoid(III) (Ln) hydration. In particular, our modelling is in very good agreement with EXAFS data and thus the microscopic picture emerging directly from dynamics can be useful to understand experiments. We show three examples across the series: at the beginning (Nd3+), middle (Gd3+) and end (Yb3+). Using these examples, we show that we are able to reproduce not only Ln-oxygen distances but also the changeover in coordination number across the series. The peculiarity of the changeover of lanthanoid coordination number in the middle of the series emerges from high exchange frequency, such that a molecular dynamics approach becomes a fundamental tool to understand this phenomenon

What first principles molecular dynamics can tell us about EXAFS spectroscopy of radioactive heavy metal cations in water

International audienceIn this paper we show how molecular dynamics simulation can improve comprehension of structure and dynamics of water solvent around heavy cations. In particular, metal-water radial distribution function obtained from molecular dynamics can be used into EXAFS equation to improve the experimental signal fitting. Here we show results on structure and dynamics of Co2+, that is a radiocontaminant cation in its isotopic form 60Co, and lanthanoids(III) that are the chemical analogues of actinides(III) in aqueous solution

Revised ionic radii of lanthanoid(III) ions in aqueous solution

International audienceA new set of ionic radii in aqueous solution has been derived for lanthanoid(III) cations starting from a very accurate experimental determination of the ion–water distances obtained from extended X-ray absorption fine structure (EXAFS) data. At variance with previous results, a very regular trend has been obtained, as expected for this series of elements. A general procedure to compute ionic radii in solution by combining the EXAFS technique and molecular dynamics (MD) structural data has been developed. This method can be applied to other ions allowing one to determine ionic radii in solution with an accuracy comparable to that of the Shannon crystal ionic radii

A coupled Car-Parrinello molecular dynamics and EXAFS data analysis investigation of aqueous Co²⁺

International audienceWe have studied the microscopic solvation structure of Co2+ in liquid water by means of density functional theory (DFT)-based Car−Parrinello molecular dynamics (CPMD) simulations and extended X-ray absorption fine structure (EXAFS) data analysis. The effect of the number of explicit water molecules in the simulation box on the first and second hydration shell structures has been considered. Classical molecular dynamics simulations, using an effective two-body potential for Co2+−water interactions, were also performed to show box size effects in a larger range. We have found that the number of explicit solvent molecules has a marginal role on the first solvation shell structural parameters, whereas larger boxes may be necessary to provide a better description of the second solvation shell. Car−Parrinello simulations were determined to provide a reliable description of structural and dynamical properties of Co2+ in liquid water. In particular, they seem to describe both the first and second hydration shells correctly. The EXAFS signal was reconstructed from Car−Parrinello simulations. Good agreement between the theoretical and experimental signals was observed, thus strengthening the microscopic picture of the Co2+ solvation properties obtained using first-principle simulations

In vitro interaction of bovine herpesvirus 1 with uterine tube epithelial cells and oocytes

The aims of this study were to assess in vitro if bovine oocytes and oviductal epithelial cells from slaughterhouses for in vitro fertilization use may be infected with bovine herpesvirus 1; to analyze whether the treatment with trypsin according to the International Embryo Transfer Society guideline is efficient to inactivate the bovine herpesvirus 1; to morphologically study the virus-oocyte interaction through optical microscopy. In this study, Madin Darby Bovine Kidney (MDBK) cells that were co-cultured with oocytes matured in vitro and exposed to bovine herpesvirus 1 showed a cytopathic effect. The nested polymerase chain reaction for the supernatant was positive for the bovine herpesvirus 1, thus suggesting that the cytopathic effect observed in the MDBK monolayer was seen due to virus replication and not because of any culture toxicity. It was also observed cytopathic effect and positive nested polymerase chain reaction in MDBK cells co-cultured with in vitro maturated oocytes free of virus, but that were co-cultured in uterine epithelial cells pre-infected with bovine herpesvirus 1 and washed or not with trypsin, demonstrating an oocyte contamination by the virus. When trypsin-washing efficacy was evaluated, we could observe that the trypsin treatment was not able to eliminate the bovine herpesvirus 1 of the oocytes, and it was not observed any morphological difference in the infected oocytes