38 research outputs found
The star formation history of RCW 36
Recent studies of massive-star forming regions indicate that they can contain
multiple generations of young stars. These observations suggest that star
formation in these regions is sequential and/or triggered by a previous
generation of (massive) stars. Here we present new observations of the star
forming region RCW 36 in the Vela Molecular Ridge, hosting a young cluster of
massive stars embedded in a molecular cloud complex. In the periphery of the
cluster several young stellar objects (YSOs) are detected which produce bipolar
jets (HH 1042 and HH 1043) demonstrating that these objects are still actively
accreting. The VLT/X-shooter spectrum of the jet structure of HH 1042 provides
detailed information on the physical conditions and kinematical properties of
the jet plasma. From this information the YSO's accretion history can be
derived. Combining the photometric and spectroscopic observations of RCW 36
gives insight into the formation process of individual stars and the star
formation history of this young massive-star forming region.Comment: 10 pages, 5 figures, to appear in the proceedings of the ESO workshop
"Circumstellar Dynamics at High Resolution", Foz do Iguacu (Br), Feb 2012,
eds. A. Carciofi and T. Riviniu
AA Tau's sudden and long-lasting deepening: enhanced extinction by its circumstellar disk
AA Tau has been monitored for more than 20 years since 1987, exhibiting a
nearly constant brightness level of V=12.5 mag. We report here that in 2011 it
suddenly faded away, becoming 2 magnitudes fainter in the V-band, and has
remained in this deep state since then. We report new optical and near-IR
photometry and spectroscopy obtained during the fading event. The system
appears much redder and fainter than it was in the bright state. Also, the 8.2d
photometric period continuously observed for more than 20 years is not seen
during most of the deep state. The analysis of the system's brightness and
colors suggests that the visual extinction on the line of sight has increased
by about 3-4 magnitudes in the deep state. At optical wavelengths, the system
appears to be dominated by scattered light, probably originating from the upper
surface layers of a highly inclined circumstellar disk. The profiles of the
Balmer lines have significantly changed as well, with the disappearance of a
central absorption component regularly observed in the bright state. We ascribe
this change to the scattering of the system's spectrum by circumstellar dust.
Noticeably, the mass accretion rate in the inner disk and onto the central star
has not changed as the system faded away. We conclude that the deepening of the
AA Tau system is due to a sudden increase of circumstellar dust extinction on
the line of sight without concomitant change in the accretion rate. We suggest
that the enhanced obscuration may be produced by a non-axisymmetric overdense
region in the disk, located at a distance of 7.7 AU or more, that was recently
brought on the line of sight by its keplerian motion around the central star.Comment: 9 pages, 6 figures, Astronomy & Astrophysics; english language
edited, email address update
Massive pre-main sequence stars in M17
The formation process of massive stars is still poorly understood. Massive
young stellar objects (mYSOs) are deeply embedded in their parental clouds,
they are rare and thus typically distant, and their reddened spectra usually
preclude the determination of their photospheric parameters. M17 is one of the
best studied HII regions in the sky, is relatively nearby, and hosts a young
stellar population. With X-shooter on the ESO Very Large Telescope we have
obtained optical to near-infrared spectra of candidate mYSOs, identified by
Hanson et al. (1997), and a few OB stars in this region. The large wavelength
coverage enables a detailed spectroscopic analysis of their photospheres and
circumstellar disks. We confirm the pre-main sequence (PMS) nature of six of
the stars and characterise the O stars. The PMS stars have radii consistent
with being contracting towards the main sequence and are surrounded by a
remnant accretion disk. The observed infrared excess and the (double-peaked)
emission lines provide the opportunity to measure structured velocity profiles
in the disks. We compare the observed properties of this unique sample of young
massive stars with evolutionary tracks of massive protostars by Hosokawa &
Omukai (2009), and propose that these mYSOs near the western edge of the HII
region are on their way to become main-sequence stars (
) after having undergone high mass-accretion rates ( ). Their spin
distribution upon arrival at the zero age main sequence (ZAMS) is consistent
with that observed for young B stars, assuming conservation of angular momentum
and homologous contraction.Comment: Accepted for publication in A&A. Appendixes A and B have been
truncated due to size limitations, the full version will be available on A&
VLT/X-shooter spectroscopy of the candidate black-hole X-ray binary MAXI J1659-152 in outburst
We present the optical to near-infrared spectrum of MAXI J1659-152, during
the onset of its 2010 X-ray outburst. The spectrum was obtained with X-shooter
on the ESO - Very Large Telescope (VLT) early in the outburst simultaneous with
high quality observations at both shorter and longer wavelengths. At the time
of the observations, the source was in the low-hard state. The X-shooter
spectrum includes many broad (~2000 km/s), double-peaked emission profiles of
H, HeI, HeII, characteristic signatures of a low-mass X-ray binary during
outburst. We detect no spectral signatures of the low-mass companion star. The
strength of the diffuse interstellar bands results in a lower limit to the
total interstellar extinction of Av ~ 0.4 mag. Using the neutral hydrogen
column density obtained from the X-ray spectrum we estimate Av ~1 mag. The
radial-velocity structure of the interstellar NaI D and CaII H & K lines
results in a lower limit to the distance of ~ 4 +/- 1 kpc, consistent with
previous estimates. With this distance and Av, the dereddened spectral energy
distribution represents a flat disk spectrum. The two subsequent 10 minute
X-shooter spectra show significant variability in the red wing of the
emission-line profiles, indicating a global change in the density structure of
the disk, though on a timescale much shorter than the typical viscous timescale
of the disk.Comment: Accepted for publication in ApJ Letter
Impaired Release of Antimicrobial Peptides into Nasal Fluid of Hyper-IgE and CVID Patients
Patients with primary immunodeficiency (PID) often suffer from frequent respiratory tract infections. Despite standard treatment with IgG-substitution and antibiotics many patients do not improve significantly. Therefore, we hypothesized that additional immune deficits may be present among these patients.To investigate if PID patients exhibit impaired production of antimicrobial peptides (AMPs) in nasal fluid and a possible link between AMP-expression and Th17-cells.Nasal fluid, nasopharyngeal swabs and peripheral blood mononuclear cells (PBMCs) were collected from patients and healthy controls. AMP levels were measured in nasal fluid by Western blotting. Nasal swabs were cultured for bacteria. PBMCs were stimulated with antigen and the supernatants were assessed for IL-17A release by ELISA.In healthy controls and most patients, AMP levels in nasal fluid were increased in response to pathogenic bacteria. However, this increase was absent in patients with common variable immunodeficiency (CVID) and Hyper-IgE syndrome (HIES), despite the presence of pathogenic bacteria. Furthermore, stimulation of PBMCs revealed that both HIES and CVID patients exhibited an impaired production of IL-17A.CVID and HIES patients appear to have a dysregulated AMP response to pathogenic bacteria in the upper respiratory tract, which could be linked to an aberrant Th17 cell response
Clinical Experience With an L-Proline–Stabilized 10 % Intravenous Immunoglobulin (Privigen®): Real-Life Effectiveness and Tolerability
PURPOSE: This retrospective study evaluated the effectiveness and tolerability in clinical practice of an L-proline–stabilized 10 % intravenous immunoglobulin (IVIG; Privigen®) in patients with primary (PID) or secondary immunodeficiency (SID). METHODS: Patients from 6 centers in Europe and the US were treated with individually determined regimens of Privigen® for ≥3 months. Serum immunoglobulin G (IgG) trough levels, annualized rates of infection, hospitalization and antibiotics use, and the incidence of adverse events (AEs) were analyzed. RESULTS: Of 72 patients, three infants with severe combined immunodeficiency (SCID) were analyzed separately. The remaining 69 patients (52.2 % male; median age 38 years [range: 0.1–90.0]) with PID (82.6 %) or SID (17.4 %) received a mean (±standard deviation) Privigen® dose of 532 ± 250 mg/kg/month resulting in trough serum IgG levels of 407–1,581 mg/dL (median: 954 mg/dL). Ten patients (14.5 %) experienced 11 serious bacterial infections over 22.0 ± 15.0 months of treatment (0.087 events/patient/year, upper one-sided 99 % confidence interval: 0.170), the most common being pneumonia (11.6 %). The rates for any infection and hospitalization were 1.082 events/patient/year and 3.63 days/patient/year, respectively. Two patients with severe disease accounted for 303 of 460 hospital days. Across all 72 patients, 13 (18.1 %) patients experienced AEs, including 10 (13.9 %) patients with AEs at least possibly related to Privigen®, including headache (8.3 %), fever, and chills (2.8 % each). No related serious AEs were reported. One infant with SCID died due to severe viral infection. CONCLUSIONS: Despite the heterogeneous population, effectiveness and tolerability of Privigen® in clinical practice closely matched those reported in clinical studies
Gender differences in the use of cardiovascular interventions in HIV-positive persons; the D:A:D Study
Peer reviewe
II Brazilian Consensus on the use of human immunoglobulin in patients with primary immunodeficiencies
Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study
Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe