12 research outputs found
TAp63gamma is required for the late stages of myogenesis
<p>p53 family members, p63 and p73, play a role in controlling early stage of myogenic differentiation. We demonstrated that TAp63gamma, unlike the other p53 family members, is markedly up-regulated during myogenic differentiation in murine C2C7 cell line. We also found that myotubes formation was inhibited upon TAp63gamma knock-down, as also indicated by atrophyic myotubes and reduction of myoblasts fusion index. Analysis of TAp63gamma-dependend transcripts identified several target genes involved in skeletal muscle contractility energy metabolism, myogenesis and skeletal muscle autocrine signaling. These results indicate that TAp63gamma is a late marker of myogenic differentiation and, by controlling different sub-sets of target genes, it possibly contributes to muscle growth, remodeling, functional differentiation and tissue homeostasis.</p
Effects of Raloxifene (RAL) on proliferation in healthy (H) and rheumatoid arthritis (RA) synoviocytes
<p><b>Copyright information:</b></p><p>Taken from "Raloxifene reduces urokinase-type plasminogen activator-dependent proliferation of synoviocytes from patients with rheumatoid arthritis"</p><p>Arthritis Research & Therapy 2005;7(6):R1244-R1253.</p><p>Published online 8 Sep 2005</p><p>PMCID:PMC1297569.</p><p>Copyright © 2005 Guiducci et al.; licensee BioMed Central Ltd.</p> Proliferation of H and RA synoviocytes as a function of RAL concentration. Synoviocytes were seeded in 24 multi-well plates (15,000 cells/well) with 10% FCS in RPMI 1640. After 24 h incubation, cells were treated with increasing concentrations of RAL (0.5 to 2 μM). Proliferation of H and RA synoviocytes under control conditions (0.2% FCS as a negative control, and 10% FCS as a positive control), in 0.2% FCS under the effect of 500 ng/ml urokinase-type plasminogen activator (u-PA) and in the presence of 0.5 and 1 μM RAL or the monoclonal antibodies (mAbs) 5B4 and 3936, which impair u-PA/u-PAR binding (see text for details). In both and , each point represents the mean ± standard deviation of three experiments performed in triplicate on four normal and four RA synovial cell lines. § = p < 0.01 versus basal (0.2% FCS); # = p < 0.001 versus 10% FCS or u-PA, for both H and RA
Fibrinolytic pattern of healthy (H) and rheumatoid arthritis (RA) synoviocytes treated with Raloxifene
<p><b>Copyright information:</b></p><p>Taken from "Raloxifene reduces urokinase-type plasminogen activator-dependent proliferation of synoviocytes from patients with rheumatoid arthritis"</p><p>Arthritis Research & Therapy 2005;7(6):R1244-R1253.</p><p>Published online 8 Sep 2005</p><p>PMCID:PMC1297569.</p><p>Copyright © 2005 Guiducci et al.; licensee BioMed Central Ltd.</p> Samples were analyzed both in basal conditions and after treatment with 0.5 and 1 μM Raloxifene (48 h). Urokinase-type plasminogen activator (u-PA) antigen was quantified on aliquots of the culture medium by ELISA assay and reported as ng/10synovial cells. u-PA receptor (u-PAR) was quantified by ELISA assay on aliquots of cell lysates and reported as ng/10synovial cells. Plasminogen activator inhibitor (PAI)-1 was also measured in aliquots of the culture medium, and reported as μg/10synovial cells. H refers to four different synovial cell cultures from healthy individuals, RA refers to synovial cell cultures from four different rheumatoid arthritis patients. In , each point represents the mean ± standard deviation of three experiments performed in triplicate on each synovial cell line. § = p < 0.01 versus basal (0.2% FCS)
The ultra-long GRB 220627A at z = 3.08
Context. GRB 220627A is a rare burst with two distinct γ-ray emission episodes separated by almost 1000 s that triggered the Fermi Gamma-ray Burst Monitor twice. High-energy GeV emission was detected by the Fermi Large Area Telescope coincident with the first emission episode but not the second. The discovery of the optical afterglow with MeerLICHT led to MUSE observations which secured the burst redshift to z'., ='., 3.08, making this the most distant ultra-long gamma-ray burst (GRB) detected to date. Aims. The progenitors of some ultra-long GRBs have been suggested in the literature to be different to those of normal long GRBs. Our aim is to determine whether the afterglow and host properties of GRB 220627A agree with this interpretation. Methods. We performed empirical and theoretical modelling of the afterglow data within the external forward shock framework, and determined the metallicity of the GRB environment through modelling the absorption lines in the MUSE spectrum. Results. Our optical data show evidence for a jet break in the light curve at 1.2 days, while our theoretical modelling shows a preference for a homogeneous circumburst medium. Our forward shock parameters are typical for the wider GRB population, and we find that the environment of the burst is characterised by a sub-solar metallicity. Conclusions. Our observations and modelling of GRB 220627A do not suggest that a different progenitor compared to the progenitor of normal long GRBs is required. We find that more observations of ultra-long GRBs are needed to determine if they form a separate population with distinct prompt and afterglow features, and possibly distinct progenitors.</p
A search for the afterglows, kilonovae, and host galaxies of two short GRBs: GRB 211106A and GRB 211227A
Context. GRB 211106A and GRB 211227A are two recent gamma-ray bursts (GRBs) whose initial X-ray position enabled us to possibly associate them with bright, low-redshift galaxies (z < 0.7). The prompt emission properties suggest that GRB 211106A is a genuine short-duration GRB and GRB 211227A is a short GRB with extended emission. Therefore, they are likely to be produced by a compact binary merger. However, a classification based solely on the prompt emission properties can be misleading. Aims. The possibility of having two short GRBs occurring in the local Universe makes them ideal targets for the search of associated kilonova (KN) emission and for detailed studies of the host galaxy properties. Methods. We carried out deep optical and near-infrared (NIR) follow-up with the ESO-VLT FORS2, HAWK-I, and MUSE instruments for GRB 211106A and with ESO-VLT FORS2 and X-shooter for GRB 211227A, starting from hours after the X-ray afterglow discovery up to days later. We performed photometric analysis to look for afterglow and KN emissions associated with the bursts, together with imaging and spectroscopic observations of the host galaxy candidates. We compared the results obtained from the optical/NIR observations with the available Swift X-Ray Telescope (XRT) and others high-energy data of both events. Results. For both GRBs we placed deep limits to the optical/NIR afterglow and KN emission. We identified their associated host galaxies, GRB 211106A at a photometric redshift z = 0.64, GRB 211227A at a spectroscopic z = 0.228. From MUSE and X-shooter spectra we derived the host galaxy properties, which turned out to be consistent with short GRBs typical hosts. We also compared the properties of GRB 211106A and GRB 211227A with those of the short GRBs belonging to the S-BAT4 sample, here extended up to December 2021, in order to further investigate the nature of these two bursts. Conclusions. Our study of the prompt and afterglow phase of the two GRBs, together with the analysis of their associated host galaxies, allows us to confirm the classification of GRB 211106A as a short GRB, and GRB 211227A as a short GRB with extended emission. The absence of an optical/NIR counterpart down to deep magnitude limits is likely due to high local extinction for GRB 211106A and a peculiarly faint kilonova for GRB 211227A.</p
Correction to: Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at <i>z</i> = 2−4 using JWST
This is a correction to: P. Schady and others, Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z = 2−4 using JWST, Monthly Notices of the Royal Astronomical Society, Volume 529, Issue 3, April 2024, Pages 2807–2831, https://doi.org/10.1093/mnras/stae677.We found a mistake in our abstract where we accidentally wrote that the host galaxy of GRB 090323 was at z = 4.7 whereas it is in fact at redshift z = 3.58 based on the NIRSpec emission line spectrum of the host galaxy. The redshift of this GRB host galaxy is correctly reported in the rest of the paper. We also found a bug in our code that produces the [O III] λ5007 surface brightness maps of the host galaxies of GRB 050820A and GRB 150403A (figs 1 and 2 of the original paper) that caused the labelled physical pixel scale to be too small by a factor of ∼1.4. This error only affected the axes shown in the figures and has no implications for the rest of the paper. The corresponding pixel-to-kpc conversions have now been corrected and the updated maps are shown in Figs 1 and 2.</p
The cosmic buildup of dust and metals: Accurate abundances from GRB-selected star-forming galaxies at 1.7 < z < 6.3
The chemical enrichment of dust and metals in the interstellar medium of galaxies throughout cosmic time is one of the key driving processes of galaxy evolution. Here we study the evolution of the gas-phase metallicities, dust-to-gas (DTG) ratios, and dust-to-metal (DTM) ratios of 36 star-forming galaxies at 1.7 40 000) spectroscopic data, including three new sources, for which at least one refractory (e.g., Fe) and one volatile (e.g., S or Zn) element have been detected at S/N > 3. This is to ensure that accurate abundances and dust depletion patterns can be obtained. We first derived the redshift evolution of the dust-corrected, absorption-line-based gas-phase metallicity, [M/H]tot, in these galaxies, for which we determine a linear relation with redshift [M/H]tot(z) = (- 0.21 ± 0.04)z - (0.47 ± 0.14). We then examined the DTG and DTM ratios as a function of redshift and through three orders of magnitude in metallicity, quantifying the relative dust abundance both through the direct line-of-sight visual extinction, AV, and the derived depletion level. We used a novel method to derive the DTG and DTM mass ratios for each GRB sightline, summing up the mass of all the depleted elements in the dust phase. We find that the DTG and DTM mass ratios are both strongly correlated with the gas-phase metallicity and show a mild evolution with redshift as well. While these results are subject to a variety of caveats related to the physical environments and the narrow pencil-beam sightlines through the interstellar medium probed by the GRBs, they provide strong implications for studies of dust masses that aim to infer the gas and metal content of high-redshift galaxies, and particularly demonstrate the large offset from the average Galactic value in the low-metallicity, high-redshift regime.</p
A kilonova following a long-duration gamma-ray burst at 350 Mpc
Gamma-ray bursts (GRBs) are divided into two populations1,2; long GRBs that derive from the core collapse of massive stars (for example, ref. 3) and short GRBs that form in the merger of two compact objects4,5. Although it is common to divide the two populations at a gamma-ray duration of 2 s, classification based on duration does not always map to the progenitor. Notably, GRBs with short (≲2 s) spikes of prompt gamma-ray emission followed by prolonged, spectrally softer extended emission (EE-SGRBs) have been suggested to arise from compact object mergers6-8. Compact object mergers are of great astrophysical importance as the only confirmed site of rapid neutron capture (r-process) nucleosynthesis, observed in the form of so-called kilonovae9-14. Here we report the discovery of a possible kilonova associated with the nearby (350 Mpc), minute-duration GRB 211211A. The kilonova implies that the progenitor is a compact object merger, suggesting that GRBs with long, complex light curves can be spawned from merger events. The kilonova of GRB 211211A has a similar luminosity, duration and colour to that which accompanied the gravitational wave (GW)-detected binary neutron star (BNS) merger GW170817 (ref. 4). Further searches for GW signals coincident with long GRBs are a promising route for future multi-messenger astronomy
Synergies of THESEUS with the large facilities of the '30s and GO opportunities
The proposed THESEUS mission will vastly expand the capabilities to monitor the high-energy sky. It will specifically exploit large samples of gamma-ray bursts to probe the early universe back to the first generation of stars, and to advance multimessenger astrophysics by detecting and localizing the counterparts of gravitational waves and cosmic neutrino sources. The combination and coordination of these activities with multi-wavelength, multi-messenger facilities expected to be operating in the 2030s will open new avenues of exploration in many areas of astrophysics, cosmology and fundamental physics, thus adding considerable strength to the overall scientific impact of THESEUS and these facilities.We discuss here a number of these powerful synergies and guest observer opportunities.</p
Fires in the deep: The luminosity distribution of early-time gamma-ray-burst afterglows in light of the Gamow Explorer sensitivity requirements
Context. Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (É€), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights with simple featureless power-law spectra that can be used to spectrally fingerprint the intergalactic medium and host galaxy during the period of reionization. Future missions such as Gamow Explorer (hereafter Gamow) are being proposed to unlock this potential by increasing the rate of identification of high-É€ (É€ > 5) GRBs in order to rapidly trigger observations from 6 to 10 m ground telescopes, the James Webb Space Telescope (JWST), and the upcoming Extremely Large Telescopes (ELTs).
Aims. Gamow was proposed to the NASA 2021 Medium-Class Explorer (MIDEX) program as a fast-slewing satellite featuring a wide-field lobster-eye X-ray telescope (LEXT) to detect and localize GRBs with arcminute accuracy, and a narrow-field multi-channel photo-ɀ infrared telescope (PIRT) to measure their photometric redshifts for > 80% of the LEXT detections using the Lyman-α dropout technique. We use a large sample of observed GRB afterglows to derive the PIRT sensitivity requirement.
Methods. We compiled a complete sample of GRB optical–near-infrared (optical-NIR) afterglows from 2008 to 2021, adding a total of 66 new afterglows to our earlier sample, including all known high-ɀ GRB afterglows. This sample is expanded with over 2837 unpublished data points for 40 of these GRBs. We performed full light-curve and spectral-energy-distribution analyses of these after-glows to derive their true luminosity at very early times. We compared the high-ɀ sample to the comparison sample at lower redshifts. For all the light curves, where possible, we determined the brightness at the time of the initial finding chart of Gamow, at different high redshifts and in different NIR bands. This was validated using a theoretical approach to predicting the afterglow brightness. We then followed the evolution of the luminosity to predict requirements for ground- and space-based follow-up. Finally, we discuss the potential biases between known GRB afterglow samples and those to be detected by Gamow.
Results. We find that the luminosity distribution of high-ɀ GRB afterglows is comparable to those at lower redshift, and we therefore are able to use the afterglows of lower-ɀ GRBs as proxies for those at high ɀ. We find that a PIRT sensitivity of 15 µJy (21 mag AB) in a 500 s exposure simultaneously in five NIR bands within 1000 s of the GRB trigger will meet the Gamow mission requirements. Depending on the ɀ and NIR band, we find that between 75% and 85% of all afterglows at ɀ > 5 will be recovered by Gamow at 5σ detection significance, allowing the determination of a robust photo-ɀ. As a check for possible observational biases and selection effects, we compared the results with those obtained through population-synthesis models, and find them to be consistent.
Conclusions. Gamow and other high-É€ GRB missions will be capable of using a relatively modest 0.3 m onboard NIR photo-É€ telescope to rapidly identify and report high-É€ GRBs for further follow-up by larger facilities, opening a new window onto the era of reionization and the high-redshift Universe.</p