Thrombosis of the left anterior descending artery due to compression from giant pseudoaneurysm late after a bentall operation.

BACKGROUND: A postoperative pseudoaneurysm may develop and gradually expand in the mediastinal space even late following Bentall operation for aortic root replacement, particularly in patients with dissection of the aorta. METHODS: A very large (148 mm) pseudoaneurysm originating of the right coronary ostium suture line was observed in a patient admitted with unstable angina 6 years after Bentall procedure for type A aortic dissection. Angiograms showed reduced flow in the right coronary and thrombotic subocclusion of the left anterior descending (LAD) coronary artery due to extrinsic compression from the expanding mediastinal mass. RESULTS: Reoperation was performed during femoro-femoral cardiopulmonary bypass and brief period of circulatory arrest to clamp the tubular graft. After closure of the detected right coronary ostium in the tubular graft double bypass, grafting to the right coronary and LAD arteries was required. Postoperative course was uneventful. CONCLUSIONS: Close long-term follow-up after a Bentall procedure is required to minimize the risk of developing a large pseudoaneurysmal mass, in particular, after dissection of the aorta

Sildenafil Reduces Expression and Release of IL-6 and IL-8 Induced by Reactive Oxygen Species in Systemic Sclerosis Fibroblasts

Oxidative stress linked to vascular damage plays an important role in the pathogenesis of systemic sclerosis (SSc). Indeed, vascular damage at nailfold capillaroscopy in patients with Raynaud’s Phenomenon (RP) is a major risk factor for the development of SSc together with the presence of specific autoantiobodies. Here, we investigated the effects of the phosphodiesterase type 5 inhibitor (PDE5i) sildenafil, currently used in the management of RP, in modulating the proinflammatory response of dermal fibroblasts to oxidative stress in vitro. Human fibroblasts isolated from SSc patients and healthy controls were exposed to exogenous reactive oxygen species (ROS) (100 µM H2O2), in the presence or absence of sildenafil (1 µM). Treatment with sildenafil significantly reduced dermal fibroblast gene expression and cellular release of IL-6, known to play a central role in the pathogenesis of tissue damage in SSc and IL-8, directly induced by ROS. This reduction was associated with suppression of STAT3-, ERK-, NF-κB-, and PKB/AKT-dependent pathways. Our findings support the notion that the employment of PDE5i in the management of RP may be explored for its efficacy in modulating the oxidative stress-induced proinflammatory activation of dermal fibroblasts in vivo and may ultimately aid in the prevention of tissue damage caused by SSc

The imaging properties of the Gas Pixel Detector as a focal plane polarimeter

X-rays are particularly suited to probe the physics of extreme objects. However, despite the enormous improvements of X-ray Astronomy in imaging, spectroscopy and timing, polarimetry remains largely unexplored. We propose the photoelectric polarimeter Gas Pixel Detector (GPD) as an instrument candidate to fill the gap of more than thirty years of lack of measurements. The GPD, in the focus of a telescope, will increase the sensitivity of orders of magnitude. Moreover, since it can measure the energy, the position, the arrival time and the polarization angle of every single photon, allows to perform polarimetry of subsets of data singled out from the spectrum, the light curve or the image of source. The GPD has an intrinsic very fine imaging capability and in this work we report on the calibration campaign carried out in 2012 at the PANTER X-ray test facility of the Max-Planck-Institut f\"ur extraterrestrische Physik of Garching (Germany) in which, for the first time, we coupled it to a JET-X optics module with a focal length of 3.5 m and an angular resolution of 18 arcsec at 4.5 keV. This configuration was proposed in 2012 aboard the X-ray Imaging Polarimetry Explorer (XIPE) in response to the ESA call for a small mission. We derived the imaging and polarimetric performance for extended sources like Pulsar Wind Nebulae and Supernova Remnants as case studies for the XIPE configuration, discussing also possible improvements by coupling the detector with advanced optics, having finer angular resolution and larger effective area, to study with more details extended objects.Comment: Accepted for publication in The Astrophysical Journal Supplemen

Gas pixel detectors

Abstract With the Gas Pixel Detector (GPD), the class of micro-pattern gas detectors has reached a complete integration between the gas amplification structure and the read-out electronics. To obtain this goal, three generations of application-specific integrated circuit of increased complexity and improved functionality has been designed and fabricated in deep sub-micron CMOS technology. This implementation has allowed manufacturing a monolithic device, which realizes, at the same time, the pixelized charge-collecting electrode and the amplifying, shaping and charge measuring front-end electronics of a GPD. A big step forward in terms of size and performances has been obtained in the last version of the 0.18 μm CMOS analog chip, where over a large active area of 15×15 mm 2 a very high channel density (470 pixels/mm 2 ) has been reached. On the top metal layer of the chip, 105,600 hexagonal pixels at 50 μm pitch have been patterned. The chip has customable self-trigger capability and includes a signal pre-processing function for the automatic localization of the event coordinates. In this way, by limiting the output signal to only those pixels belonging to the region of interest, it is possible to reduce significantly the read-out time and data volume. In-depth tests performed on a GPD built up by coupling this device to a fine pitch (50 μm) gas electron multiplier are reported. Matching of the gas amplification and read-out pitch has let to obtain optimal results. A possible application of this detector for X-ray polarimetry of astronomical sources is discussed

A gas pixel detector for x-ray polarimetry

Even though lacking of solid experimental verifications, X-ray polarimetry is strongly established as a deep diagnostic tool for probing the emission mechanisms in astronomical sources of high energy radiation. The recent development of new, more efficient instrumentation, as well as the renewed interest of the theoreticians, has drawn a significant attention to the field. Particularly, the exploitation of the photoelectric effect for deriving polarization information seems to promise a great advance in sensitivity with respect to the conventional techniques. To this aim we have designed, produced and tested a CMOS VLSI array of 2101 pixels (with 80 μm pitch), to be directly used as the charge collecting anode of a Gas Electron Multiplier (GEM). Each pixel is fully covered by a hexagonal metal electrode and each of these electrodes is individually connected to a full electronics chain, built immediately below it; in this sense detector and read-out electronics become virtually the same thing. Even though we focus our attention on the polarimetric applications, our achievements are highly significant for the whole field of development of gas detectors, which for the first time reach the level of integration and resolution typical of solid state detectors

Sildenafil Counteracts the In Vitro Activation of CXCL-9, CXCL-10 and CXCL-11/CXCR3 Axis Induced by Reactive Oxygen Species in Scleroderma Fibroblasts

Oxidative stress plays a key role in systemic sclerosis (SSc) pathogenesis, and an altered redox homeostasis might be responsible for abnormal inflammatory status, fibrosis and tissue damage extension. In this study, we explored the effect of the phosphodiesterase type 5 inhibitor sildenafil in modulating the activation of the CXCL-9, -10, -11/CXCR3 axis, which is fundamental in the perpetuation of inflammation in different autoimmune diseases, in the cell culture of SSc human dermal fibroblasts exposed to a pro-oxidant environment. We observed that sildenafil significantly reduced gene expression and release of CXCL-9, -10 and -11, inhibited the CXCR3 action and suppressed the activation of STAT1-, JNK- and p38MAPK pathways. This in vitro study on dermal fibroblasts supports clinical studies to consider the efficacy of sildenafil in preventing tissue damage and fibrosis in SSc by targeting central biomarkers of disease progression, vascular injuries and fibrosis and reducing the pro-inflammatory activation induced by oxidative stress

Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV

We present the results of our analysis of cosmic-ray electrons using about 8 million electron candidates detected in the first 12 months on-orbit by the Fermi Large Area Telescope. This work extends our previously-published cosmic-ray electron spectrum down to 7 GeV, giving a spectral range of approximately 2.5 decades up to 1 TeV. We describe in detail the analysis and its validation using beam-test and on-orbit data. In addition, we describe the spectrum measured via a subset of events selected for the best energy resolution as a cross-check on the measurement using the full event sample. Our electron spectrum can be described with a power law $\propto {\rm E}^{-3.08 \pm 0.05}$ with no prominent spectral features within systematic uncertainties. Within the limits of our uncertainties, we can accommodate a slight spectral hardening at around 100 GeV and a slight softening above 500 GeV.Comment: 20 pages, 23 figures, 2 tables, published in Physical Review D 82, 092004 (2010) - contact authors: C. Sgro', A. Moisee

Constraints on dark matter models from a Fermi LAT search for high-energy cosmic-ray electrons from the Sun

During its first year of data taking, the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope has collected a large sample of high-energy cosmic-ray electrons and positrons (CREs). We present the results of a directional analysis of the CRE events, in which we searched for a flux excess correlated with the direction of the Sun. Two different and complementary analysis approaches were implemented, and neither yielded evidence of a significant CRE flux excess from the Sun. We derive upper limits on the CRE flux from the Sun's direction, and use these bounds to constrain two classes of dark matter models which predict a solar CRE flux: (1) models in which dark matter annihilates to CREs via a light intermediate state, and (2) inelastic dark matter models in which dark matter annihilates to CREs.Comment: 18 pages, 8 figures, accepted for publication in Physical Review D - contact authors: Francesco Loparco ([email protected]), M. Nicola Mazziotta ([email protected]) and Jennifer Siegal-Gaskins ([email protected]

Fermi-LAT Study of Gamma-ray Emission in the Direction of Supernova Remnant W49B

We present an analysis of the gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the direction of SNR W49B (G43.3-0.2). A bright unresolved gamma-ray source detected at a significance of 38 sigma is found to coincide with SNR W49B. The energy spectrum in the 0.2-200 GeV range gradually steepens toward high energies. The luminosity is estimated to be 1.5x10^{36} (D/8 kpc)^2 erg s^-1 in this energy range. There is no indication that the gamma-ray emission comes from a pulsar. Assuming that the SNR shell is the site of gamma-ray production, the observed spectrum can be explained either by the decay of neutral pi mesons produced through the proton-proton collisions or by electron bremsstrahlung. The calculated energy density of relativistic particles responsible for the LAT flux is estimated to be remarkably large, U_{e,p}>10^4 eV cm^-3, for either gamma-ray production mechanism.Comment: 9 pages, 10 figure

Playing Darwin. Part B. 20 years of domestication in Drosophila subobscura

Adaptation to a new environment (as well as its underlying mechanisms) is one of the most important topics in Evolutionary Biology. Understanding the adaptive process of natural populations to captivity is essential not only in general evolutionary studies but also in conservation programmes. Since 1990, the Group of Experimental Evolution (CBA/FCUL) has been performing long-term, real-time evolutionary studies, with the characterization of laboratory adaptation in populations of Drosophila subobscura founded in different times and from different locations. Initially, these experiments involved phenotypic assays and more recently were expanded to studies at the molecular level (microsatellite and chromosomal polymorphisms) and with different population sizes. Throughout these two decades, a clear pattern of evolutionary convergence to long-established laboratory populations has been consistently observed in several life-history traits. However, contingencies across foundations were also found during the adaptive process. In characters with complex evolutionary trajectories, the data suggested that the comparative method lacked predictive capacity relative to real-time evolutionary trajectories (experimental evolution). Microsatellite analysis revealed general similarity in gene diversity and allele number between studied populations, as well as an unclear association between genetic variability and evolutionary potential. Nevertheless, ongoing studies in all foundations are being carried out to further test this hypothesis. A comparison between recently introduced and long-term populations (founded from the same natural location) has shown higher degree of chromosomal polymorphism in recent ones. Finally, our findings suggest higher heterogeneity between small-sized populations, as well as a slower evolutionary rate in characters close to fitness (such as fecundity and mating behaviour). This comprehensive study is aimed at better understanding the processes and patterns underlying adaptation to captivity, as well as its genetic basis