9 research outputs found
Carbonyl stress phenomena during chronic infection with Opisthorchis felineus.
Infection with the fish borne liver fluke Opisthorchis felineus is common in the Eastern Europe (Ukraine, European part of Russia), Northern Asia (Siberia) and Central Asia (Northern Kazakhstan). Better understanding of the molecular pathogenesis of the biliary tract and liver during chronic opisthorchiasis can be expected to improve protection against and management of complications of this disease. We hypothesize that infection with O. felineus associates with formation of methylglyoxal and carbonyl stress in the liver and hence here we investigated the glyoxalase system and the receptor for advanced glycated end products (RAGE) in the liver of hamsters infected with this liver fluke. Expression of mRNA encoding glyoxalase 1 decreased at 8 weeks of the infection and catalytic activity as well decreased at 8 and 12 weeks after infection, and the expression of the glyoxalase 2 decreased until 36 week post infection, which associated with the decreasing activity of the enzyme at 8, 12 week post infection. Glutathione levels in infected livers had decreased at week 8, whereas up-regulation of RAGE at mRNA levels was seen for the extended duration of the experimental infection of the hamsters. This outcome supported the notion of hepatic dicarbonyl stress during chronic opisthorchiasis. The inhibition of the glyoxalase system and accumulation of methylgyloxal at the early stages of the infection may underpin development of insulin resistance during opisthorchiasis
Measurement of inclusive and leading subjet fragmentation in pp and Pb–Pb collisions at = 5.02 TeV
This article presents new measurements of the fragmentation properties of jets in both proton--proton (pp) and heavy-ion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction of transverse momentum carried by subjets of radius within jets of radius . Charged-particle jets are reconstructed at midrapidity using the anti- algorithm with jet radius , and subjets are reconstructed by reclustering the jet constituents using the anti- algorithm with radii and . In proton--proton collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet fragmentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark-gluon plasma (QGP). We find indications that there is a turnover in the ratio between the distributions in \mbox{Pb--Pb} and collisions as , exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP.This article presents new measurements of the fragmentation properties of jets in both proton–proton (pp) and heavy-ion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction z of transverse momentum carried by subjets of radius r within jets of radius R. Charged-particle jets are reconstructed at midrapidity using the anti-k algorithm with jet radius R = 0.4, and subjets are reconstructed by reclustering the jet constituents using the anti-k algorithm with radii r = 0.1 and r = 0.2. In proton–proton collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the z distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet frag- mentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The z distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark–gluon plasma (QGP). We find no significant modification of z distributions in Pb–Pb compared to pp collisions. However, the distributions are also consistent with a hardening trend for z< 0.95, as predicted by several jet quenching models. As z → 1 our results indicate that any such hardening effects cease, exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP.[graphic not available: see fulltext]This article presents new measurements of the fragmentation properties of jets in both proton-proton (pp) and heavy-ion collisions with the ALICE experiment at the LHC. We report distributions of the fraction of transverse momentum carried by subjets of radius within jets of radius . Charged-particle jets are reconstructed at midrapidity using the anti- algorithm with jet radius , and subjets are reconstructed by reclustering the jet constituents using the anti- algorithm with radii and . In pp collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet fragmentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark-gluon plasma (QGP). We find no significant modification of distributions in Pb-Pb compared to pp collisions. However, the distributions are also consistent with a hardening trend for , as predicted by several jet quenching models. As our results indicate that any such hardening effects cease, exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP
Measurement of the production of charm jets tagged with D mesons in pp collisions at = 5.02 and 13 TeV
International audienceThe measurement of the production of charm jets, identified by the presence of a D meson in the jet constituents, is presented in proton–proton collisions at centre-of-mass energies of = 5.02 and 13 TeV with the ALICE detector at the CERN LHC. The D mesons were reconstructed from their hadronic decay D → Kπ and the respective charge conjugate. Jets were reconstructed from D-meson candidates and charged particles using the anti-k algorithm, in the jet transverse momentum range 5 < p< 50 GeV/c, pseudorapidity |η| < 0.9 − R, and with the jet resolution parameters R = 0.2, 0.4, 0.6. The distribution of the jet momentum fraction carried by a D meson along the jet axis was measured in the range 0.4 << 1.0 in four ranges of the jet transverse momentum. Comparisons of results for different collision energies and jet resolution parameters are also presented. The measurements are compared to predictions from Monte Carlo event generators based on leading-order and next-to-leading-order perturbative quantum chromodynamics calculations. A generally good description of the main features of the data is obtained in spite of a few discrepancies at low p. Measurements were also done for R = 0.3 at = 5.02 and are shown along with their comparisons to theoretical predictions in an appendix to this paper.[graphic not available: see fulltext
Observation of flow angle and flow magnitude fluctuations in Pb-Pb collisions at = 5.02 TeV at the LHC
This Letter reports on the first measurements of transverse momentum dependent flow angle Ψn and flow magnitude vn fluctuations determined using new four-particle correlators. The measurements are performed for various centralities in Pb–Pb collisions at a center-of-mass energy per nucleon pair of sNN = 5.02 TeV with ALICE at the CERN Large Hadron Collider. Both flow angle and flow magnitude fluctuations are observed in the presented centrality ranges and are strongest in the most central collisions and for a transverse momentum pT>2GeV/c. Comparison with theoretical models, including iEBE-VISHNU, MUSIC, and AMPT, show that the measurements exhibit unique sensitivities to the initial state of heavy-ion collisions.This Letter reports on the first measurements of transverse momentum dependent flow angle and flow magnitude fluctuations, determined using new four-particle correlators. The measurements are performed for various centralities in Pb-Pb collisions at a centre-of-mass energy per nucleon pair of = 5.02 TeV with ALICE at the CERN Large Hadron Collider. Both flow angle and flow magnitude fluctuations are observed in the presented centrality ranges and are strongest in the most central collisions and for a transverse momentum GeV/. Comparison with theoretical models, including iEBE-VISHNU, MUSIC, and AMPT, show that the measurements exhibit unique sensitivities to the initial state of heavy-ion collisions