Gravitationally lensed QSOs in the ISSIS/WSO-UV era

Gravitationally lensed QSOs (GLQs) at redshift z = 1-2 play a key role in understanding the cosmic evolution of the innermost parts of active galaxies (black holes, accretion disks, coronas and internal jets), as well as the structure of galaxies at intermediate redshifts. With respect to studies of normal QSOs, GLQ programmes have several advantages. For example, a monitoring of GLQs may lead to unambiguous detections of intrinsic and extrinsic variations. Both kinds of variations can be used to discuss central engines in distant QSOs, and mass distributions and compositions of lensing galaxies. In this context, UV data are of particular interest, since they correspond to emissions from the immediate surroundings of the supermassive black hole. We describe some observation strategies to analyse optically bright GLQs at z of about 1.5, using ISSIS (CfS) on board World Space Observatory-Ultraviolet.Comment: 7 pages, 4 figures, Accepted for publication in Astrophysics & Space Scienc

Disk-Jet Connection in the Radio Galaxy 3C 120

We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 120 between 2002 and 2007 at X-ray, optical, and radio wave bands, as well as imaging with the Very Long Baseline Array (VLBA). Over the 5 yr of observation, significant dips in the X-ray light curve are followed by ejections of bright superluminal knots in the VLBA images. Consistent with this, the X-ray flux and 37 GHz flux are anti-correlated with X-ray leading the radio variations. This implies that, in this radio galaxy, the radiative state of accretion disk plus corona system, where the X-rays are produced, has a direct effect on the events in the jet, where the radio emission originates. The X-ray power spectral density of 3C 120 shows a break, with steeper slope at shorter timescale and the break timescale is commensurate with the mass of the central black hole based on observations of Seyfert galaxies and black hole X-ray binaries. These findings provide support for the paradigm that black hole X-ray binaries and active galactic nuclei are fundamentally similar systems, with characteristic time and size scales linearly proportional to the mass of the central black hole. The X-ray and optical variations are strongly correlated in 3C 120, which implies that the optical emission in this object arises from the same general region as the X-rays, i.e., in the accretion disk-corona system. We numerically model multi-wavelength light curves of 3C 120 from such a system with the optical-UV emission produced in the disk and the X-rays generated by scattering of thermal photons by hot electrons in the corona. From the comparison of the temporal properties of the model light curves to that of the observed variability, we constrain the physical size of the corona and the distances of the emitting regions from the central BH.Comment: Accepted for publication in the Astrophysical Journal. 28 pages, 21 figures, 2 table

Increase in the constrictor effects of Rho-kinase in skeletal muscle and coronary arteries of rats with chronic hypothyroidism

Aim. The deficit of thyroid function is known to be accompanied by an increase in the overall peripheral vascular resistance. This work tested the hypothesis that long-term hypothyroidism leads to an increase in the vasoconstrictor effect of Rho-kinase in skeletal muscle and heart resistance arteries of adult rats.Materials and methods. Male Wistar rats consumed the antithyroid drug propylthiouracil (PTU) in drinking water (0.025%), starting at 10 weeks of age. The rats of the control group received PTU-free water. After 14 weeks, the contractile responses of the gastrocnemius muscle arteries (to the α1-adrenoceptor agonist methoxamine) and the septal coronary artery (to the thromboxane A2 receptor agonist U46619) were isometrically recorded. The contribution of the Rho-kinase to the arterial contractile responses was assessed using inhibitor Y27632 (3 μM).Results. The consumption of propylthiouracil was accompanied by a marked decrease of thyroid hormone concentrations and an increase in total cholesterol serum level as well as a decrease in body weight. Maximal contractile responses of studied arteries were also reduced in hypothyroid rats. However, basal tone and reactivity to the moderate concentrations of agonists in arteries of hypothyroid rats were increased compared to control animals. Y27632 significantly weakened the contractile responses of the arteries and negated the differences between the two groups of rats.Conclusion. Chronic hypothyroidism leads to an increase in the activity of the Rho-kinase signaling pathway in the arteries of the gastrocnemius muscle and heart, which results in the increase of the spontaneous tone of the arteries and their reactivity to agonists

Alterations of the Purinergic Regulation in Mesenteric Arteries of Pannexin-1-Knockout Mice

Pannexin 1 (Panx1) forms plasma membrane channels that release ATP, an important vascular tone regulator. However, despite the abundant expression of Panx1 in the vascular system, its effects on smooth muscle contraction are not evident in all arteries. In this study, we tested the hypothesis that the functional consequences of Panx1 deficiency can be masked by the augmented action of ATP secreted in a Panx1-independent way. Experiments were performed on small mesenteric arteries obtained from Panx1-knockout (Panx1–/–) and C57Bl/6 (Panx1+/+) male mice using wire myography of endothelium-denuded arterial preparations and reverse-transcription quantitative PCR techniques. Arterial contractile responses to phenylephrine did not differ in two experimental groups. Ecto-ATPase inhibitor ARL67156 (100 μM) potentiated the responses to phenylephrine in Panx1+/+ but not in Panx1–/–, while ARL67156 did not affect the contractile responses to the thromboxane A2 receptor agonist in any of the two groups. Contractile responses to exogenous ATP (10 μM) were smaller in Panx1+/+ than in Panx1–/– mice. By contrast, NTPDase1 mRNA content was higher in Panx1+/+ than in Panx1–/– mice. These results suggest that ATP released from smooth muscle cells through Panx1 channels can potentiate contractile responses of murine mesenteric arteries upon activation of α1-adrenoceptors. In Panx1–/– mice an increased arterial ATP sensitivity and diminished NTPDase1 activity may augment the contractile effects of Panx1-independent ATP