Search Results (7)

Multidrug-resistant Acinetobacter baumannii is a major concern in healthcare institutions worldwide. Several reports described the dissemination of A. baumannii high-risk clones that are responsible for a high number of difficult-to-treat infections. In our study, 19 multidrug-resistant A. baumannii strains from Budapest, Hungary, were investigated based on whole-genome sequencing (WGS). The obtained results were analysed together with data from 433 strains of A. baumannii from the Pathogenwatch database. WGS analysis of 19 A. baumannii strains detected that 12 belonged to ST2 and seven belonged to ST636. Among ST2 strains, 11 out of 12 carried either bla_OXA-23 or bla_OXA-58 genes; however, all strains of ST636 uniformly carried bla_OXA-72 gene. All strains of ST2 and ST636 carried bla_OXA-66 and bla_ADC-25 genes. Based on core genome multilocus sequence typing (cgMLST), 10 strains of ST2 belonged to cgMLST906, one strain to cgMLST458, and one strain to cgMLST1320; by contrast, all strains of ST636 belonged to cgMLST1178. Certain virulence determinants were present in all strains of both ST2 and ST636, namely, Ata, Bap, BfmRS, T2SS and PNAG. Interestingly, OmpA was present in all strains of ST2, but it was absent in all strains of ST636. Comparative analysis of 19 strains of this study and the collection of 433 isolates from Pathogenwatch database, proved a diverse clonal distribution of high-risk A. baumannii clones in Europe. The major clone in Europe is ST2, which is present all over the continent. However, ST636 has been mainly reported in Eastern Europe. Interestingly, cgMLSTs of ST2 correspond to the production of different beta-lactamases, namely, OXA-82 in cgMLST116, OXA-72 in cgMLST506, and cgMLST556, PER-1 in cgMLST456 and cgMLST1041. Our study demonstrates that the ST2 high-risk clone of A. baumannii is the most widespread in Europe; however, based on cgMLST analysis, a detailed detection of beta-lactamase production can be determined. Full article

The precessing jets of microquasar SS 433 have punched through the supernova remnant W 50 from the explosion forming the compact object. The jets collimate before reaching beyond the shell, some 40 pc downstream, just the region of origin of TeV gamma radiation. Collimation could be effected by ambient pressure in the SNR cavity; I investigate conditions under which the W 50 morphology and the sites of TeV gamma radiation can be explained in terms of collimation, with associated shocks, induced by ambient pressure. The SNR is now ~${10}^5$ years after the supernova; with the present pressure, collimation and associated shocks would indeed occur ~40 pc downstream. Modeling of the evolution of binary systems indicates that the Roche lobe overflow and the initiation of the jets may be recent rather than early; present day collimation would still occur ~40 pc downstream, but the cone angle of the precession must then have increased with time—driven by the Roche lobe overflow. The morphology of W 50 and the site of the origin of TeV radiation are readily explained in terms of the collimation of the jets by internal SNR pressure. Full article

Flaring in the SS 433 microquasar is dominated by outbursts from material at distances from the centre of mass of the binary system comparable to the separation of the two components. This note completes a demonstration that ejected plasma leaves the system in the region of the L₂ point, there overflowing the outer Roche lobe and giving rise to a spiral structure as it leaves the system as part of the local environment. It also provides a new measure of the mass ratio of the binary. Full article

Astrophysical plasma ejections (jets) are formed and powered by black holes that accrete material from their companion star in binary systems. Black hole X-ray binary systems constitute potential powerful galactic and extragalactic neutrino and gamma-ray sources. After being accelerated to highly relativistic velocities and subjected to various energy-consuming interactions, the lepto-hadronic content of the jets produces secondary particles such as pions and muons that decay to gamma-ray photons and neutrinos heading towards the Earth. In this work, we employ a jet emission model in order to predict the neutrino and gamma-ray integral fluxes emanating from some of the most investigated and prominent stellar black hole X-ray binary systems in the Milky Way, such as GRO J1655-40, Cygnus X-1, SS 433, and GRS 1915+105. For the sake of comparison, we also include an extragalactic system, namely, LMC X-1, located in the Large Magellanic Cloud. For the case of gamma-ray emissions, we also include absorption effects due to X-ray emission from the accretion disk and the black hole corona, as well as ultraviolet (UV) emission from the binary system’s companion star. Full article

Recently, microquasar jets have aroused the interest of many researchers focusing on the astrophysical plasma outflows and various jet ejections. In this work, we concentrate on the investigation of electromagnetic radiation and particle emissions from the jets of stellar black hole binary systems characterized by the hadronic content in their jets. Such emissions are reliably described within the context of relativistic magneto-hydrodynamics. Our model calculations are based on the Fermi acceleration mechanism through which the primary particles (mainly protons and electrons) of the jet are accelerated. As a result, a small portion of thermal protons of the jet acquire relativistic energies, through shock-waves generated into the jet plasma. From the inelastic collisions of fast (non-thermal) protons with the thermal (cold) ones, secondary charged and neutral particles (pions, kaons, muons, $\eta$-particles, etc.) are created, as well as electromagnetic radiation from the radio wavelength band to X-rays and even very high energy gamma-rays. One of our main goals is, through the appropriate solution of the transport equation and taking into account the various mechanisms that cause energy losses to the particles, to study the secondary particle concentrations within hadronic astrophysical jets. After assessing the suitability and sensitivity of the derived (for this purpose) algorithms on the Galactic MQs SS 433 and Cyg X-1, as a concrete extragalactic binary system, we examine the LMC X-1 located in the Large Magellanic Cloud, a satellite galaxy of our Milky Way Galaxy. It is worth mentioning that, for the companion O star (and its extended nebula structure) of the LMC X-1 system, new observations using spectroscopic data from VLT/UVES have been published a few years ago. Full article

Serum bilirubin levels, which are determined by a complex interplay of various enzymes, including heme oxygenase-1 (HO-1) and uridine diphosphate–glucuronosyl transferase (UGT1A1), may be protective against progression of cardiovascular disease (CVD) in hemodialysis patients. However, the combined effect of HO-1 and UGT1A1*28 gene polymorphisms on CVD outcomes among hemodialysis patients is still unknown. This retrospective study enrolled 1080 prevalent hemodialysis patients and the combined genetic polymorphisms of HO-1 and UGT1A1 on serum bilirubin were analyzed. Endpoints were CVD events and all-cause mortality. Mean serum bilirubin was highest in patients with S/S + S/L of the HO-1 promoter and UGT1A1 7/7 genotypes (Group 1), intermediate in those with S/S + S/L of the HO-1 promoter and UGT1A1 7/6 + 6/6 genotypes (Group 2), and lowest in the carriers with the L/L HO-1 promoter and UGT1A1 7/6 + 6/6 genotypes (Group 3) (p < 0.001). During a median follow-up of 50 months, 433 patients developed CVD. Compared with patients in Group 3, individuals among Groups 1 and 2 had significantly lower risks for CVD events (adjusted hazard ratios (aHRs) of 0.35 for Group 1 and 0.63 for Group 2), respectively. Compared with the lower bilirubin tertile, the aHRs were 0.72 for the middle tertile and 0.40 for the upper tertile for CVD events. We summarized that serum bilirubin as well as HO-1 and UGT1A1 gene polymorphisms were associated with CVD among patients receiving chronic hemodialysis. Full article

The microquasar SS 433 exhibits in H$\alpha$ intermittent flares. A sequence of observations made in 2004 showed flaring Doppler shifted to both the red and the blue simultaneously. The mean shifts varied from day to day, following the orbital phase of the compact object. At the time, this behaviour was interpreted as indicating an origin in the outer rim of the accretion disk. A new analysis of these old data, presented in this paper, shows that the flares are not eclipsed by the Companion that eclipses the photosphere surrounding the compact object. They are therefore not intermittent sightings of an accretion disk. The alternative explanation is plasma expelled through the $L_2$ point, following the phase of the orbit as it invades the space beyond the system. That space has been mapped with comparatively recent GRAVITY observations of a similar flare in Br$\gamma$, indeed revealing a strong rotation component. Full article