93 research outputs found
Systemic Effects Induced by Hyperoxia in a Preclinical Model of Intra-abdominal Sepsis
Supplemental oxygen is a supportive treatment in patients with sepsis to balance tissue oxygen delivery and demand in the tissues. However, hyperoxia may induce some pathological effects. We sought to assess organ damage associated with hyperoxia and its correlation with the production of reactive oxygen species (ROS) in a preclinical model of intra-abdominal sepsis. For this purpose, sepsis was induced in male, Sprague-Dawley rats by cecal ligation and puncture (CLP). We randomly assigned experimental animals to three groups: control (healthy animals), septic (CLP), and sham-septic (surgical intervention without CLP). At 18 h after CLP, septic (n = 39), sham-septic (n = 16), and healthy (n = 24) animals were placed within a sealed Plexiglas cage and randomly distributed into four groups for continuous treatment with 21%, 40%, 60%, or 100% oxygen for 24 h. At the end of the experimental period, we evaluated serum levels of cytokines, organ damage biomarkers, histological examination of brain and lung tissue, and ROS production in each surviving animal. We found that high oxygen concentrations increased IL-6 and biomarkers of organ damage levels in septic animals, although no relevant histopathological lung or brain damage was observed. Healthy rats had an increase in IL-6 and aspartate aminotransferase at high oxygen concentration. IL-6 levels, but not ROS levels, are correlated with markers of organ damage. In our study, the use of high oxygen concentrations in a clinically relevant model of intra-abdominal sepsis was associated with enhanced inflammation and organ damage. These findings were unrelated to ROS release into circulation. Hyperoxia could exacerbate sepsis-induced inflammation, and it could be by itself detrimental. Our study highlights the need of developing safer thresholds for oxygen therapy
Emission line gas ionisation in young radio galaxies
This paper is the second in a series in which we present
intermediate-resolution spectra for a complete sample of 14 compact radio
sources, taken with the aim of investigating the impact of the nuclear activity
on the cirumnuclear interstellar medium (ISM) in the early stages of radio
source evolution. In the first paper we presented the kinematic results from
the line modelling and reported fast outflows in the circumnuclear gas. Here,
we use the line fluxes to investigate the physical conditions and dominant
ionisation mechanisms of the emission line gas. We find evidence for large
electron densities and high reddening in the nuclear regions, particularly in
the broader, blueshifted components. These results are consistent with the idea
that the young, recently triggered radio sources still reside in dense and
dusty cocoons deposited by the recent activity triggering event. In addition,
we find that the quiescent nuclear and extended narrow components are
consistent with AGN photoionisation. For the nuclear broader and shifted
components the results are less clear. Whilst there are suggestions that the
broader components may be closer to shock plus precursor models on the
diagnostic diagrams (with high electron temperatures and densities), we are
unable to unambiguously distinguish the dominant ionisation mechanism using the
optical emission line ratios. This is surprising given the strong evidence for
jet-cloud interactions (broad emission lines, large outflow velocities and
strong radio-optical alignments), which favours the idea that the warm gas has
been accelerated in shocks driven by the radio lobes expanding through a dense
cocoon of gas deposited during the triggering event.Comment: Accepted for publication in MNRAS - Full paper (including Appendices)
available at http://www.astron.nl/~morganti/Papers/Holt_MNRAS2009.p
Lyman Alpha Blobs as an Observational Signature of Cold Accretion Streams into Galaxies
Recent hydrodynamic simulations of galaxy formation reveal streams of cold (T
~ 1e4 K) gas flowing into the centers of dark matter halos as massive as
1e12-1e13.5 M_sun at redshifts z~1-3. In this paper we show that if > 20% of
the gravitational binding energy of the gas is radiated away, then the
simulated cold flows are spatially extended Lyman Alpha (Lya) sources with
luminosities, Lya line widths, and number densities that are comparable to
those of observed Lya blobs. Furthermore, the filamentary structure of the cold
flows can explain the wide range of observed Lya blob morphologies. Since the
most massive halos form in dense environments, the association of Lya blobs
with overdense regions arise naturally. We argue that Lya blobs - even those
which are clearly associated with starburst galaxies or quasars - provide
direct observational support for the cold accretion mode of galaxies. We
discuss various testable predictions of this association.Comment: MNRAS in press. 13 pages, 6 figures. Discussion + references added.
Main conclusions unaffecte
LipoDDx: a mobile application for identification of rare lipodystrophy syndromes
BACKGROUND: Lipodystrophy syndromes are a group of disorders characterized by a loss of adipose tissue once other situations of nutritional deprivation or exacerbated catabolism have been ruled out. With the exception of the HIV-associated lipodystrophy, they have a very low prevalence, which together with their large phenotypic heterogeneity makes their identification difficult, even for endocrinologists and pediatricians. This leads to significant delays in diagnosis or even to misdiagnosis. Our group has developed an algorithm that identifies the more than 40 rare lipodystrophy subtypes described to date. This algorithm has been implemented in a free mobile application, LipoDDx(R). Our aim was to establish the effectiveness of LipoDDx(R). Forty clinical records of patients with a diagnosis of certainty of most lipodystrophy subtypes were analyzed, including subjects without lipodystrophy. The medical records, blinded for diagnosis, were evaluated by 13 physicians, 1 biochemist and 1 dentist. Each evaluator first gave his/her results based on his/her own criteria. Then, a second diagnosis was given using LipoDDx(R). The results were analysed based on a score table according to the complexity of each case and the prevalence of the disease. RESULTS: LipoDDx(R) provides a user-friendly environment, based on usually dichotomous questions or choice of clinical signs from drop-down menus. The final result provided by this app for a particular case can be a low/high probability of suffering a particular lipodystrophy subtype. Without using LipoDDx(R) the success rate was 17 +/- 20%, while with LipoDDx(R) the success rate was 79 +/- 20% (p < 0.01). CONCLUSIONS: LipoDDx(R) is a free app that enables the identification of subtypes of rare lipodystrophies, which in this small cohort has around 80% effectiveness, which will be of help to doctors who are not experts in this field. However, it will be necessary to analyze more cases in order to obtain a more accurate efficiency value
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at = 2.76 TeV
The yield of charged particles associated with high- trigger
particles ( GeV/) is measured with the ALICE detector in
Pb-Pb collisions at = 2.76 TeV relative to proton-proton
collisions at the same energy. The conditional per-trigger yields are extracted
from the narrow jet-like correlation peaks in azimuthal di-hadron correlations.
In the 5% most central collisions, we observe that the yield of associated
charged particles with transverse momenta GeV/ on the
away-side drops to about 60% of that observed in pp collisions, while on the
near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/350
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Hypertriton Production in p-Pb Collisions at √sNN = 5.02 TeV
The study of nuclei and antinuclei production has proven to be a powerful
tool to investigate the formation mechanism of loosely bound states in
high-energy hadronic collisions. The first measurement of the production of
in p-Pb collisions at = 5.02
TeV is presented in this Letter. Its production yield measured in the rapidity
interval -1 < y < 0 for the 40% highest multiplicity p-Pb collisions is . The measurement is compared with the expectations of statistical
hadronisation and coalescence models, which describe the nucleosynthesis in
hadronic collisions. These two models predict very different yields of the
hypertriton in small collision systems such as p-Pb and therefore the
measurement of is crucial to distinguish between them.
The precision of this measurement leads to the exclusion with a significance
larger than 6 of some configurations of the statistical hadronisation,
thus constraining the production mechanism of loosely bound states
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