The FIV (feline immunodeficiency virus) induces in cats brain changes presenting similarities with those observed in human immunodeficiency virus infection. This FIV model was used to study the ...relationship between viral load in brain, in lymphoid organs and central nervous system (CNS) changes during the early and late stages of infection. Early brain changes were analyzed in animals experimentally infected with two different FIV isolates and sacrificed at 7 and 15 days, 1, 2, 6, and 12 months post inoculation (p.i.). Late CNS abnormalities were analyzed in naturally FTV-infected cats referred to the Veterinary School of Nantes. For each animal, one cerebral hemisphere was fixed and examined using routine techniques. The characterization of FIV replicating cells by in situ hybridization was performed on the other half frozen hemisphere on sections performed in the anterior and the median regions of the brain. During the early stages of infection, moderate gliosis with glial nodules and sometimes white matter pallor and meningitis were associated with few infected cells scattered in the brain. Infection was an early event as infected cells could be detected in brain at 7 p.i. For each cat, these findings were found identical in the two analyzed areas. During the late stages, brain lesions and the number of virus replicating cells increased especially in animals with perivascular infiltrates. The multinucleated giant cells encephalitis was never observed and the number of FIV replicating cells scattered in the whole brain was always low. This discrepancy between the number of replicating cells and the brain lesions, corroborates the hypotheses suggesting that brain injuries may be mediated via diffusive factors and amplification processes through cytokine cascades and cell activations.
Two surface antigens were isolated from young or adult schistosomes by affinity chromatography with monoclonal antibodies. Vaccination with an antigen having a molecular weight of 155,000 gave ...partial protection against challenge in some batches of mice and in a group of cynomolgus monkeys. Vaccination with an antigen having a molecular weight of 53,000 gave similar levels of protection in mice. The results demonstrate that protection can be obtained with single antigens, but the precise requirements for reproducible vaccination are as yet unknown.
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Transition disks correspond to a short stage between the young protoplanetary phase and older debris phase. Along this evolutionary sequence, the gas component disappears leaving room for a ...dust-dominated environment where already-formed planets signpost their gravitational perturbations. We endeavor to study the very inner region of the well-known and complex debris, but still gas-rich disk, around HD 141569A using the exquisite high-contrast capability of SPHERE at the VLT. Recent near-infrared (IR) images suggest a relatively depleted cavity within ~200 au, while former mid-IR data indicate the presence of dust at separations shorter than ~100 au. We obtained multi-wavelength images in the near-IR in J, H2, H3 and Ks bands with the IRDIS camera and a 0.95-1.35 micrometers spectral data cube with the IFS. Data were acquired in pupil-tracking mode, thus allowing for angular differential imaging. We discovered several new structures inside 1", of which the most prominent is a bright ring with sharp edges (semi-major axis: 0.4") featuring a strong north-south brightness asymmetry. Other faint structures are also detected from 0.4" to 1" in the form of concentric ringlets and at least one spiral arm. Finally, the VISIR data at 8.6 micrometers suggests the presence of an additional dust population closer in. Besides, we do not detect companions more massive than 1-3 mass of Jupiter. The performance of SPHERE allows us to resolve the extended dust component, which was previously detected at thermal and visible wavelengths, into very complex patterns with strong asymmetries ; the nature of these asymmetries remains to be understood. Scenarios involving shepherding by planets or dust-gas interactions will have to be tested against these observations.
In recent years there have been many attempts to characterize the occurrence of stellar, BD and planetary-mass companions to solar-type stars, with the aim of constraining formation mechanisms. From ...RV observations a dearth of companions with masses between 10-40 MJup has been noticed at close separations, suggesting the possibility of a distinct formation mechanism for objects above and below this range. We present a model for the substellar companion mass function (CMF). It consists of the superposition of the planet and BD companion mass distributions, assuming that we can extrapolate the RV measured companion mass function for planets to larger separations and the stellar companion mass-ratio distribution over all separations into the BD mass regime. By using both the results of the VLT/NaCo large program and the complementary archive datasets that probe the occurrence of planets and BDs on wide orbits around solar-type stars, we place some constraints on the planet and BD distributions. We developed a MC simulation tool to predict the outcome of a given survey, depending on the shape of the orbital parameter distributions. Comparing the predictions with the results of the observations, we calculate how likely different models are and which can be ruled out. Current observations are consistent with the proposed model for the CMF, as long as a sufficiently small outer truncation radius is introduced for the planet separation distribution. The results of the direct imaging surveys searching for substellar companions around Sun-like stars are consistent with a combined substellar mass spectrum of planets and BDs. This mass distribution has a minimum between 10 and 50 MJup, in agreement with RV measurements. The dearth of objects in this mass range would naturally arise from the shape of the mass distribution, without the introduction of any distinct formation mechanism for BDs.
HD~106906AB is so far the only young binary system around which a planet has been imaged and a debris disk evidenced thanks to a strong IR excess. As such, it represents a unique opportunity to study ...the dynamics of young planetary systems. We aim at further investigating the close (tens of au scales) environment of the HD~106906AB system. We used the extreme AO fed, high contrast imager SPHERE recently installed on the VLT to observe HD~106906. Both the IRDIS imager and the Integral Field Spectrometer were used. We discovered a very inclined, ring-like disk at a distance of 65~au from the star. The disk shows a strong brightness asymmetry with respect to its semi-major axis. It shows a smooth outer edge, compatible with ejection of small grains by the stellar radiation pressure. We show furthermore that the planet's projected position is significantly above the disk's PA. Given the determined disk inclination, it is not excluded though that the planet could still orbit within the disk plane if at a large separation (2000--3000 au). We identified several additional point sources in the SPHERE/IRDIS field-of-view, that appear to be background objects. We compare this system with other debris disks sharing similarities, and we briefly discuss the present results in the framework of dynamical evolution.
The frequency of human papillomavirus (HPV) in series of endocervical adenocarcinoma in situ (AIS) ranges from 6 to 100%. Some of this variability can be attributed to small study numbers and such ...technical considerations as the sensitivity of the hybridization method employed. Consequently, the role of the HPV in AIS oncogenesis is unclear. The frequency and relative distribution of HPV DNA types 6, 11, 16, 18, 31, 33, and 35 in 37 cases of AIS were determined and correlated with clinical variables. All cases were first typed by dot blot hybridization (DBH), and those found to be HPV negative were subsequently typed by polymerase chain reaction amplification with DBH enhancement (PCR/DBH). The HPV DNA positivity rate was 27% by DBH alone and 52% by PCR/DBH amplification. Combining the results of both methods, the overall HPV positivity rate was 66%: HPV 18 in 15 cases (43%), HPV 16 in eight cases (23%). The HPV status did not correlate with any clinical variable. This study showed that the sensitivity of the hybridization method is principally accountable for the variable frequency of HPV in AIS. The identification of only high-risk oncogenic HPV types in two-thirds of the cases suggests a significant role for the virus in AIS oncogenesis; HPV status, however, does not delineate a clinical profile.
The respiratory release of CO2 from soils is a major determinant of the global carbon cycle. It is traditionally considered that this respiration is an intracellular metabolism consisting of complex ...biochemical reactions carried out by numerous enzymes and co-factors. Here we show that the endoenzymes released from dead organisms are stabilised in soils and have access to suitable substrates and co-factors to permit function. These enzymes reconstitute an extracellular oxidative metabolism (EXOMET) that may substantially contribute to soil respiration (16 to 48% of CO2 released from soils in the present study). EXOMET and respiration from living organisms should be considered separately when studying effects of environmental factors on the C cycle because EXOMET shows specific properties such as resistance to high temperature and toxic compounds.
The respiratory release of CO2 from soils is a major determinant of the global carbon cycle. It is traditionally considered that this respiration is an intracellular metabolism consisting of complex ...biochemical reactions carried out by numerous enzymes and co-factors. Here we show that the endoenzymes released from dead organisms are stabilised in soils and have access to suitable substrates and co-factors to permit function. These enzymes reconstitute an extracellular oxidative metabolism (EXOMET) that may substantially contribute to soil respiration (16 to 48% of CO2 released from soils in the present study). EXOMET and respiration from living organisms should be considered separately when studying effects of environmental factors on the C cycle because EXOMET shows specific properties such as resistance to high temperature and toxic compounds.
Increasing biological findings argue for the importance of cholesterol-24S-hydroxylase (CYP46A1) in cholesterol homeostasis in cerebral structures. Based on the similarity between the brain and the ...neural retina, the aim of the current study was to evaluate the expression of CYP46A1 in the mammalian retina. RT-PCR analysis of CYP46A1 in bovine samples revealed the highest expression in the neural retina. The retinal pigment epithelium expressed CYP46A1 gene at a low level while the ciliary body showed no expression. Immunohistochemical evaluation of the posterior pole of rat retina showed that the protein is specifically expressed in neurons, whereas cone-rods photoreceptors were negative for CYP46A1 staining. The metabolite produced by CYP46A1, 24S-hydroxycholesterol, was almost exclusively found in neural retina, the concentration therein being more than 10-fold higher than in the retinal pigment epithelium or the ciliary body. The results of the current study are consistent with our primary hypothesis: the neural retina specifically expresses cholesterol-24S-hydroxylase, a metabolizing enzyme responsible for the removal of cholesterol in neurons. Based on the link between cholesterol-24S-hydroxylase, 24S-hydroxycholesterol, and neurologic disorders, CYP46A1 may be a valuable gene candidate for retinal pathologies like age-related macular degeneration or glaucomas, and 24S-hydroxycholesterol may be involved in the onset of the degenerative processes in these diseases.
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We present the performance of the Integral Field Spectrograph (IFS) of SPHERE, the high-contrast imager for the ESO VLT telescope designed to perform imaging and spectroscopy of extrasolar planets, ...obtained from tests performed at the Institute de Planétologie et d'Astrophysique de Grenoble facility during the integration phase of the instrument.} {The tests were performed using the instrument software purposely prepared for SPHERE. The output data were reduced applying the SPHERE data reduction and handling software, adding an improved spectral deconvolution procedure. To this aim, we prepared an alternative procedure for the spectral subtraction exploiting the principal components analysis algorithm. Moreover, a simulated angular differential imaging procedure was also implemented to estimate how the instrument performed once this procedure was applied at telescope. The capability of the IFS to faithfully retrieve the spectra of the detected faint companions was also considered.} {We found that the application of the updated version of the spectral deconvolution procedure alone, when the algorithm throughput is properly taken into account, gives us a \(5\sigma\) limiting contrast of the order of 5$\times$$10^{-6}\( or slightly better. The further application of the angular differential imaging procedure on these data should allow us to improve the contrast by one order of magnitude down to around 7\)\times$$10^{-7}$ at a separation of 0.3 arcsec. The application of a principal components analysis procedure that simultaneously uses spectral and angular data gives comparable results. Finally, we found that the reproducibility of the spectra of the detected faint companions is greatly improved when angular differential imaging is applied in addition to the spectral deconvolution.
