271 research outputs found
Novel calibrations of virial black hole mass estimators in active galaxies based on X-ray luminosity and optical/NIR emission lines
Accurately weigh the masses of SMBH in AGN is currently possible for only a
small group of local and bright broad-line AGN through reverberation mapping
(RM). Statistical demographic studies can be carried out considering the
empirical scaling relation between the size of the BLR and the AGN optical
continuum luminosity. However, there are still biases against low-luminosity or
reddened AGN, in which the rest-frame optical radiation can be severely
absorbed/diluted by the host and the BLR emission lines could be hard to
detect. Our purpose is to widen the applicability of virial-based SE relations
to reliably measure the BH masses also for low-luminosity or intermediate/type
2 AGN that are missed by current methodology. We achieve this goal by
calibrating virial relations based on unbiased quantities: the hard X-ray
luminosities, in the 2-10 keV and 14-195 keV bands, that are less sensitive to
galaxy contamination, and the FWHM of the most important rest-frame NIR and
optical BLR emission lines. We built a sample of RM AGN having both X-ray
luminosity and broad optical/NIR FWHM measurements available in order to
calibrate new virial BH mass estimators. We found that the FWHM of the
H, H and NIR lines (i.e. Pa, Pa and
HeI10830) all correlate each other having negligible or small offsets.
This result allowed us to derive virial BH mass estimators based on either the
2-10 keV or 14-195 keV luminosity. We took also into account the recent
determination of the different virial coefficients for pseudo and classical
bulges. By splitting the sample according to the bulge type and adopting
separate factors we found that our virial relations predict BH masses of
AGN hosted in pseudobulges 0.5 dex smaller than in classical bulges.
Assuming the same average factor for both populations, a difference of
0.2 dex is still found.Comment: 11 pages, 2 figures, 4 tables, accepted for publication on A&
The T2238C human atrial natriuretic peptide molecular variant and the risk of cardiovascular diseases
Atrial natriuretic peptide (ANP) is a cardiac hormone which plays important functions to maintain cardio-renal homeostasis. The peptide structure is highly conserved among species. However, a few gene variants are known to fall within the human ANP gene. The variant rs5065 (T2238C) exerts the most substantial effects. The T to C transition at the 2238 position of the gene (13-23% allele frequency in the general population) leads to the production of a 30-, instead of 28-, amino-acid-long α-carboxy-terminal peptide. In vitro, CC2238/αANP increases the levels of reactive oxygen species and causes endothelial damage, vascular smooth muscle cells contraction, and increased platelet aggregation. These effects are achieved through the deregulated activation of type C natriuretic peptide receptor, the consequent inhibition of adenylate cyclase activity, and the activation of Giα proteins. In vivo, endothelial dysfunction and increased platelet aggregation are present in human subjects carrying the C2238/αANP allele variant. Several studies documented an increased risk of stroke and of myocardial infarction in C2238/αANP carriers. Recently, an incomplete response to antiplatelet therapy in ischemic heart disease patients carrying the C2238/αANP variant and undergoing percutaneous coronary revascularization has been reported. In summary, the overall evidence supports the concept that T2238C/ANP is a cardiovascular genetic risk factor that needs to be taken into account in daily clinical practice
On a diffusion model with absorption and production
We discuss the structure of radial solutions of some superlinear elliptic
equations which model diffusion phenomena when both absorption and production
are present. We focus our attention on solutions defined in R (regular) or in R
\ {0} (singular) which are infinitesimal at infinity, discussing also their
asymptotic behavior. The phenomena we find are present only if absorption and
production coexist, i.e., if the reaction term changes sign. Our results are
then generalized to include the case where Hardy potentials are considered
Detection of Faint BLR Components in the Starburst/Seyfert Galaxy NGC 6221 and Measure of the Central BH Mass
In the last decade, using single epoch virial based techniques in the optical
band, it has been possible to measure the central black hole mass on large AGN1
samples. However these measurements use the width of the broad line region as a
proxy of the virial velocities and are therefore difficult to be carried out on
those obscured (type 2) or low luminosity AGN where the nuclear component does
not dominate in the optical. Here we present the optical and near infrared
spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT.
Previous observations of NGC 6221 in the X-ray band show an absorbed (N_H=8.5
+/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity
log(L_14-195 keV) = 42.05 erg/s, while in the optical band its spectrum is
typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations
have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta
lines (FWHM ~1400-2300 km/s) confirming previous studies indicating that NGC
6221 is a reddened starburst galaxy which hosts an AGN. We use the measure of
the broad components to provide a first estimate of its central black hole mass
(M_BH = 10^(6.6 +/- 0.3) Msol, lambda_Edd=0.01-0.03), obtained using recently
calibrated virial relations suitable for moderately obscured (N_H<10^24 cm^-2)
AGN.Comment: 13 pages, 3 figures, 1 table. Published in Frontiers in Astronomy and
Space Science
C2238/αANP modulates apolipoprotein E through Egr-1/miR199a in vascular smooth muscle cells in vitro
Subjects carrying the T2238C ANP gene variant have a higher risk to suffer a stroke or myocardial infarction. The mechanisms through which T2238C/αANP exerts detrimental vascular effects need to be fully clarified. In the present work we aimed at exploring the impact of C2238/αANP (mutant form) on atherosclerosis-related pathways. As a first step, an atherosclerosis gene expression macroarray analysis was performed in vascular smooth muscle cells (VSMCs) exposed to either T2238/αANP (wild type) or C2238/αANP. The major finding was that apolipoprotein E (ApoE) gene expression was significantly downregulated by C2238/αANP and it was upregulated by T2238/αANP. We subsequently found that C2238/αANP induces ApoE downregulation through type C natriuretic peptide receptor (NPR-C)-dependent mechanisms involving the upregulation of miR199a-3p and miR199a-5p and the downregulation of DNAJA4. In fact, NPR-C knockdown rescued ApoE level. Upregulation of miR199a by NPR-C was mediated by a reactive oxygen species-dependent increase of the early growth response protein-1 (Egr-1) transcription factor. In fact, Egr-1 knockdown abolished the impact of C2238/αANP on ApoE and miR199a. Of note, downregulation of ApoE by C2238/αANP was associated with a significant increase in inflammation, apoptosis and necrosis that was completely rescued by the exogenous administration of recombinant ApoE. In conclusion, our study dissected a novel mechanism of vascular damage exerted by C2238/αANP that is mediated by ApoE downregulation. We provide the first demonstration that C2238/αANP downregulates ApoE in VSMCs through NPR-C-dependent activation of Egr-1 and the consequent upregulation of miR199a. Restoring ApoE levels could represent a potential therapeutic strategy to counteract the harmful effects of C2238/αANP
On the Iwasawa-Taniguchi effect of radio-quiet AGN
The existence of an anti-correlation between the Equivalent Width (EW) of the
neutral narrow core of the iron Kalpha emission line and the 2-10 keV
luminosity (the so-called `X-ray Baldwin' or `Iwasawa-Taniguchi' effect) has
been debated in the last years. We aim at testing this claim on the largest
catalogue of radio quiet AGN high-quality X-ray spectra ever published. The
final sample comprises 157 objects. We search for a relation of the iron line
EW not only with the X-ray luminosity, but also with the Black Hole mass, the
Eddington ratio and the cosmological distance. The data presented here were
analyzed homogeneously, all spectra are from the same instrument and with high
Signal-to-Noise Ratio. A linear censored fit on the EW versus 2-10 keV
luminosity is highly significant and yields , where is the EW of the neutral iron
Kalpha line in eV and is the 2-10 keV X-ray luminosity in units of
erg s. The anti-correlation with the Eddington ratio is also
very significant, while no dependence of the iron EW on the BH mass is
apparent.Comment: 4 pages, 4 figures, accepted for publication in Astronomy and
Astrophysics Letter
Extending Virial Black Hole Mass Estimates to Low-Luminosity or Obscured AGN: the cases of NGC 4395 and MCG -01-24-012
In the last decade, using single epoch (SE) virial based spectroscopic
optical observations, it has been possible to measure the black hole (BH) mass
on large type 1 Active Galactic Nuclei (AGN) samples. However this kind of
measurements can not be applied on those obscured type 2 and/or low luminosity
AGN where the nuclear component does not dominate in the optical. We have
derived new SE relationships, based on the FWHM and luminosity of the broad
line region component of the Pabeta emission line and/or the hard X-ray
luminosity in the 14-195 keV band, which have the prospect of better working
with low luminosity or obscured AGN. The SE relationships have been calibrated
in the 10^5-10^9 M_sol mass range, using a sample of AGN whose BH masses have
been previously measured using reverberation mapping techniques. Our tightest
relationship between the reverberation-based BH mass and the SE virial product
has an intrinsic spread of 0.20 dex. Thanks to these SE relations, in agreement
with previous estimates, we have measured a BH mass of M_BH =1.7^+1.3_-0.7 X
10^5 M_sol for the low luminosity, type 1, AGN NGC 4395 (one of the smallest
active galactic BH known). We also measured, for the first time, a BH mass of
M_BH = 1.5^+1.1_-0.6 X 10^7 M_sol for the Seyfert 2 galaxy MCG -01-24-012.Comment: 10 pages, 7 figures. Accepted by MNRA
HST unveils a compact mildly relativistic Broad Line Region in the candidate true type 2 NGC 3147
NGC 3147 has been considered the best case of a true type 2 AGN: an
unobscured AGN, based on the unabsorbed compact X-ray continuum, which lacks a
broad line region (BLR). However, the very low luminosity of NGC 3147 implies a
compact BLR, which produces very broad lines, hard to detect against the
dominant background host galaxy. Narrow (0.1"x0.1") slit HST spectroscopy
allowed us to exclude most of the host galaxy light, and revealed an H
line with an extremely broad base (FWZI km s). The line
profile shows a steep cutoff blue wing and an extended red wing, which match
the signature of a mildly relativistic thin accretion disk line profile. It is
indeed well fit with a nearly face on thin disk, at , with an
inner radius at r, which matches the prediction of
r from the relation. This
result questions the very existence of true type 2 AGN. Moreover, the detection
of a thin disk, which extends below 100 r in an
system, contradicts the current view of the accretion flow configuration at
extremely low accretion rates.Comment: 6 pages, 3 figures, accepted for publication in MNRAS Letter
Blood Pressure Target Achievement Under Monotheraphy. A Real-Life Appraisal
Introduction: Despite hypertension guidelines suggest that the most effective treatment strategy to improve blood pressure (BP) target achievement is to implement the use of combination treatment, monotherapy is still widely used in the clinical practice of hypertension.
Aim: To investigate BP control under monotherapy in the setting of real-life.
Methods: We extracted data from a medical database of adult outpatients who were referred to the Hypertension Unit, Sant'Andrea Hospital, Rome (IT), including anthropometric data, CV risk factors and comorbidities, presence or absence of antihypertensive therapy and concomitant medications. Among treated hypertensive patients, we identified only those under single antihypertensive agent (monotherapy). Office BP treatment targets were defined according to 2018 ESC/ESH guidelines as: (a) < 130/80 mmHg in individuals aged 18-65 years; (b) < 140/80 mmHg in those aged > 65 years.
Results: From an overall sample of 7797 records we selected 1578 (20.2%) hypertensive outpatients (47.3% female, age 59.5 ± 13.6 years, BMI 26.6 ± 4.4 kg/m2) treated with monotherapies, among whom 30.5% received ACE inhibitors, 37.7% ARBs, 15.8% beta-blockers, 10.6% CCBs, 3.0% diuretics, and 2.0% alpha-blockers. 36.6% of these patients reached the conventional clinic BP goal of < 140/90 mmHg, whilst the 2018 European guidelines BP treatment targets were fulfilled only in 14.0%. In particular, 10.2% patients aged 18-65 years and 20.4% of those aged > 65 years achieved the recommended BP goals. All these proportions results significantly lower than those achieved with dual (18.2%) or triple (22.2%) combination therapy, though higher than those obtained with life-style changes (10.8%). Proportions of patients on monotherapies with normal home and 24-h BP levels were 22.0% and 30.2%, respectively, though only 5.2% and 7.3% of these patients achieved sustained BP control, respectively. Ageing and dyslipidaemia showed significant and independent positive predictive value for the achievement of the recommended BP treatment targets, whereas European SCORE resulted a negative and independent predictor in outpatients treated with monotherapies.
Conclusions: Our data showed a persistent use of monotherapy in the clinical practice, though with unsatisfactory BP control, especially in light of the BP treatment targets suggested by the last hypertension guidelines
- …