Varying susceptibility of clinical and environmental Scedosporium isolates to chemical oxidative stress in conidial germination

Scedosporium species are opportunistic pathogens causing a great variety of infections in both immunocompetent and immunocompromised individuals. The Scedosporium genus ranks the second among the filamentous fungi colonizing the airways of patients with cystic fibrosis (CF), after Aspergillus fumigatus, and most species are capable to chronically colonize the respiratory tract of these patients. Nevertheless, few data are available regarding evasion of the inhaled conidia to the host immune response. Upon microbial infection, macrophages and neutrophils release reactive oxygen species (ROS). To colonize the respiratory tract, the conidia need to germinate despite the oxidative stress generated by phagocytic cells. Germination of spores from different clinical or environmental isolates of the major Scedosporium species was investigated in oxidative stress conditions. All tested species showed susceptibility to oxidative stress. However, when comparing clinical and environmental isolates, differences in germination capabilities under oxidative stress conditions were seen between species as well as within each species. Among environmental isolates, Scedosporium aurantiacum isolates were the most resistant to oxidative stress whereas Scedosporium dehoogii were the most susceptible. Overall, the differences observed between Scedosporium species in the capacity to germinate under oxidative stress conditions could explain their varying prevalence and pathogenicity

On The Orbital Evolution of Jupiter Mass Protoplanet Embedded in A Self-Gravity Disk

We performed a series of hydro-dynamic simulations to investigate the orbital migration of a Jovian planet embedded in a proto-stellar disk. In order to take into account of the effect of the disk's self gravity, we developed and adopted an \textbf{Antares} code which is based on a 2-D Godunov scheme to obtain the exact Reimann solution for isothermal or polytropic gas, with non-reflecting boundary conditions. Our simulations indicate that in the study of the runaway (type III) migration, it is important to carry out a fully self consistent treatment of the gravitational interaction between the disk and the embedded planet. Through a series of convergence tests, we show that adequate numerical resolution, especially within the planet's Roche lobe, critically determines the outcome of the simulations. We consider a variety of initial conditions and show that isolated, non eccentric protoplanet planets do not undergo type III migration. We attribute the difference between our and previous simulations to the contribution of a self consistent representation of the disk's self gravity. Nevertheless, type III migration cannot be completely suppressed and its onset requires finite amplitude perturbations such as that induced by planet-planet interaction. We determine the radial extent of type III migration as a function of the disk's self gravity.Comment: 19 pages, 13 figure

FUSE Observations of the Dwarf Novae UU Aql, BV Cen, and CH UMa in Quiescence

We report on FUSE spectra of three U Gem-type, long period, dwarf novae, UU Aql, BV Cen and CH UMa taken during their quiescence intervals. We discuss the line identifications in their spectra and attempt to characterize the source(s) of their FUV flux distribution. Archival IUE spectrum of CH UMa and BV Cen in quiescence were identified as having a matching flux level with the FUSE spectra and these were combined with each FUSE spectrum to broaden the wavelength coverage and further constrain model fits. Multi-component synthetic spectral fits from our model grids, consisting of single temperature white dwarfs, two-temperature white dwarfs, accretion disks and white dwarfs plus accretion disks, were applied to the FUSE spectra alone and to the combined FUSE + IUE spectra. We present the results of our model analyses and their implications.Comment: accepted in AJ, 26 pages, 6 tables, 8 figures (5 color, 3 b/w

Production de protéines recombinantes de Scedosporium apiospermum, Cu,Zn superoxide dismutase et catalase, pour l’amélioration et la standardisation du sérodiagnostic des infections à Scedosporium apiospermum chez les patients atteints de mucoviscidose

National audienc

Pharmacokinetics of voriconazole and posaconazole administered in experimental models of disseminated scedosporiosis with cerebral involvement

International audienc

Scedosporium apiospermum complex Catalase A1 and Cu-Zn SOD recombinant proteins are useful tools for serodiagnosis of Scedosporium infection

International audienc

Vortex migration in protoplanetary disks

We consider the radial migration of vortices in two-dimensional isothermal gaseous disks. We find that a vortex core, orbiting at the local gas velocity, induces velocity perturbations that propagate away from the vortex as density waves. The resulting spiral wave pattern is reminiscent of an embedded planet. There are two main causes for asymmetries in these wakes: geometrical effects tend to favor the outer wave, while a radial vortensity gradient leads to an asymmetric vortex core, which favors the wave at the side that has the lowest density. In the case of asymmetric waves, which we always find except for a disk of constant pressure, there is a net exchange of angular momentum between the vortex and the surrounding disk, which leads to orbital migration of the vortex. Numerical hydrodynamical simulations show that this migration can be very rapid, on a time scale of a few thousand orbits, for vortices with a size comparable to the scale height of the disk. We discuss the possible effects of vortex migration on planet formation scenarios.Comment: 13 pages, 13 figures, accepted for publication in Ap

Impact of cyclosporine dosing regimen and infection on voriconazole pharmacodynamics in an experimental model of cerebral scedosporiosis

International audienc

Experimental models of disseminated scedosporiosis with cerebral involvement

Scedosporium apiospermum is a soil fungus which can cause severe and often fatal cerebral infections in both immunocompetent patients in the event of near drowning and immunosuppressed patients such as lung transplant recipients. Because of the low susceptibility of this fungus to antifungal drugs, and the low permeability of the blood-brain barrier (BBB), therapeutic drug monitoring is necessary to reach an effective tissue concentration with limited side effects. Indeed, diffusion of the drug in the brain is dependent on several parameters, such as the integrity of the BBB and the activity of efflux pumps. To evaluate drug diffusion, two experimental models were developed in immunocompetent and immunosuppressed rats. Inocula were administered via the penile vein and a clinical scale (0-9) was established, based on weight and clinical and neurologic signs evaluated by the tail suspension test. Cerebral involvement was confirmed by magnetic resonance imaging and histologic examination of brain sections after hematoxylin-eosin-safran or silver staining. Voriconazole or posaconazole was given to the rats at doses ranging from 10 to 75 mg/kg/day via i.v. or oral routes, respectively. Whatever the immune status, the effective doses (defined by a doubling of the survival time and the absence of neurologic sequelae) were 30 mg/kg/day for voriconazole and 50 mg/kg/day for posaconazole. Overall, the results demonstrated that these models may constitute valuable tools for the performance of pharmacokinetic and pharmacodynamic studies for pharmacokinetic-pharmacodynamic modeling