2,684 research outputs found
Physics with the ALICE experiment
ALICE experiment at LHC collects data in pp collisions at =0.9,
2.76 and 7 TeV and in PbPb collisions at 2.76 TeV. Highlights of the detector
performance and an overview of experimental results measured with ALICE in pp
and AA collisions are presented in this paper. Physics with proton-proton
collisions is focused on hadron spectroscopy at low and moderate .
Measurements with lead-lead collisions are shown in comparison with those in pp
collisions, and the properties of hot quark matter are discussed.Comment: Presented at the Conference of the Nuclear Physics Division of the
Russian Academy of Science, 11-25.11.2011, ITEP, Moscow. 16 pages, 14 figure
D(-)lentiginosine-induced apoptosis involves the intrinsic pathway and is p53-independent
We have recently found that D(-)lentiginosine, a synthetic iminosugar exerting glucosidase inhibitory activity, but not its natural enantiomer lentiginosine, is endowed with an unexpected, pro-apoptotic activity. Here, we investigated mechanisms involved in apoptosis induced by D(-)lentiginosine in MOLT-3, HT-29 and SH-SY5Y tumour cell lines. The results showed that D(-)lentiginosine increased caspase 9 expression at 18 h in all the cell lines from 1.5-3.1 folds. Cytochrome c in the cytoplasm was found to be increased from 2.3-2.6 folds in treated cells with respect to control cells. These effects were accompanied by a remarkable collapse of the mitochondrial membrane potential and by the downregulation of anti-apoptotic genes, as well as the upregulation of pro-apoptotic genes of the Bcl-2 family. U937Bcl-2 transfectants, highly expressing Bcl-2, were reluctant to undergo apoptosis even following treatment with 500 μM D(-)lentiginosine, whereas apoptosis by D(-)lentiginosine was induced also in U937 cells, naturally deficient in P53. Thus, our study establishes that the enantiomer of a natural iminosugar is endowed with a possible anti-tumorigenic effect that might be ascribed not only to their capacity to inhibit glycosidases but also to other unknown mechanisms. These data encourage further investigation on similar compounds to make them an interesting platform for the generation of new anticancer drugs
Model and parameter dependence of heavy quark energy loss in a hot and dense medium
Within the framework of the Langevin equation, we study the energy loss of
heavy quark due to quasi-elastic multiple scatterings in a quark-gluon plasma
created by relativistic heavy-ion collisions. We investigate how the initial
configuration of the quark-gluon plasma as well as its properties affect the
final state spectra and elliptic flow of D meson and non-photonic electron. We
find that both the geometric anisotropy of the initial quark-gluon plasma and
the flow profiles of the hydrodynamic medium play important roles in the heavy
quark energy loss process and the development of elliptic flow. The relative
contribution from charm and bottom quarks is found to affect the transverse
momentum dependence of the quenching and flow patterns of heavy flavor decay
electron; such influence depends on the interaction strength between heavy
quark and the medium.Comment: 16 pages, 7 figure
Jet-like correlations of heavy-flavor particles - from RHIC to LHC
Measurements at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven
National Laboratory have revealed strong modification of the jet structure in
high-energy heavy-ion collisions, which can be attributed to the interaction of
hard scattered partons with the hot and dense QCD matter. The study of
heavy-quark (charm and bottom) production in such collisions provides key tests
of parton energy-loss models and, thus, yields profound insight into the
properties of the produced matter. The high-pT yield of heavy-flavor decay
electrons exhibits an unexpected large suppression. Since those single
electrons have contributions from charm and bottom decays an experimental
method is needed to investigate them separately. Heavy-flavor particle
correlations provide information about the underlying production mechanism. In
this contribution, a review on recent measurements on azimuthal correlations of
single electrons and open charmed mesons at RHIC and perspectives of such
measurements at the CERN-Large Hadron Collider (LHC) are presented. Moreover,
it has been shown that next-to-leading-order (NLO) QCD processes, such as gluon
splitting, become important at LHC energies. It will be demonstrated how this
contribution can be determined through the measurement of the charm content in
jets.Comment: 8 pages, 6 figures, Proceedings of the 27th Winter Workshop on
Nuclear Dynamics, Winter Park, Colorado, USA. To be published in Journal of
Physics: Conference Series (JPCS
Inhibition of IκBα phosphorylation potentiates regulated cell death induced by azidothymidine in HTLV-1 infected cells
Adult T cell leukemia/lymphoma (ATL) can be susceptible, at least transiently, to treatments with azidothymidine (AZT) plus IFNα and/or arsenic trioxide. However, the real role of AZT in this effect is still unclear. In fact, while reverse transcriptase (RT) inhibition could explain reduction of clonal expansion and of renewal of HTLV-1 infected cells during ATL progression, this effect alone seems insufficient to justify the evident and prompt decrease of the pro-viral load in treated patients. We have previously demonstrated that AZT is endowed with an intrinsic pro-apoptotic potential towards both peripheral blood mononuclear cells from healthy donors or some tumor cell lines, but this cytotoxic potential cannot be fully achieved unless IκBα phosphorylation is inhibited. Since the constitutive activation of NF-kappa B (NF-κB) appears a common biological basis of HTLV-1-infected cells, a pharmacological inhibition of IκBα phosphorylation seems a potential strategy for treating and preventing HTLV-1 related pathologies. In this study, we have demonstrated that a combination treatment with the IκBα phosphorylation inhibitor Bay 11-7085 and AZT induced increased levels of regulated cell death (RCD) by apoptosis compared to the single treatments in HTLV-1 infected cells of different origin. Importantly, levels of RCD were considerably higher in infected cells in comparison with the uninfected ones. Inhibition of NF-κB activation following the combined treatment was confirmed by analysis of both gel-shift and functional activity of the NF-κB complex proteins, p65/p52. Moreover, a transcriptional analysis revealed that the addition of Bay 11-7085 to AZT treatment in HTLV-1-infected cells modified their transcriptional profile, by inducing the upregulation of some pro-apoptotic genes together with the downregulation of some anti-apoptotic genes. Our data suggest that addition of adequate concentrations of IκBα phosphorylation inhibitor to therapeutic regimens including AZT could be a promising strategy in ATL
Charge dependent azimuthal correlations in Pb--Pb collisions at TeV
Separation of charges along the extreme magnetic field created in non-central
relativistic heavy--ion collisions is predicted to be a signature of local
parity violation in strong interactions. We report on results for charge
dependent two particle azimuthal correlations with respect to the reaction
plane for Pb--Pb collisions at TeV recorded in 2010 with
ALICE at the LHC. The results are compared with measurements at RHIC energies
and against currently available model predictions for LHC. Systematic studies
of possible background effects including comparison with conventional
(parity-even) correlations simulated with Monte Carlo event generators of
heavy--ion collisions are also presented.Comment: Published in the proceedings of "Quark Matter 2011", Annecy-Franc
Comparison of Cytogenetic and Static Cytometry Procedures in the Evaluation of Potentially Malignant Oral Lesions
Gross genomic damage or specific chromosomal alterations have been revealed by different laboratory procedures in potentially malignant oral lesions, but two or more procedures have never been applied at the same time to the same cell population. In the present study we considered cell suspensions obtained from 34 oral lesions at risk of malignancy to see whether they might harbour genetic alterations and whether a correlation exists between the results obtained by two different methods of assessing DNA aberrations. Each suspension underwent DNA-content assessment by static cytometry, and cytogenetic G-banding analysis of short-term primary cultures. DNA content was determined in a minimum of 1000 cells on a Fairfield ploidy analyser and results expressed as percent of aneuploid cells in the S-phase; cytogenetic analysis was carried out according to standard procedures on in situ G-banding metaphases, and results expressed as percent of metaphases with chromosomal alterations. The results showed that the percentage of metaphases with chromosomal alterations was significantly correlated with the percentage of aneuploid cells in the S-phase. In conclusion, genetic alterations can be revealed in the same oral specimen either by procedures studying DNA content in fixed cells or by procedures investigating chromosomal alterations in cultured and proliferating cells
Antioxidant phytocomplexes extracted from pomegranate (Punica granatum L.) using hydrodynamic cavitation show potential anticancer activity in vitro
Hydrodynamic cavitation (HC), as an effective, efficient, and scalable extraction technique for natural products, could enable the affordable production of valuable antioxidant extracts from plant resources. For the first time, whole pomegranate (Punica granatum L.) fruits, rich in bioactive phytochemicals endowed with anti-cancer properties, were extracted in water using HC. Aqueous fractions sequentially collected during the process (M1–M5) were lyophilized (L), filtered (A), or used as such, i.e., crude (C), and analyzed for their biochemical profile and in vitro antioxidant power. The fractions M3 and M4 from the L and C series showed the highest antiradical activity and phytochemical content. While the lyophilized form is preferable for application purposes, sample L-M3, which was produced faster and with lower energy consumption than M4, was used to assess the potential antiproliferative effect on human breast cancer line (AU565-PAR) and peripheral blood mononuclear (PBMC) cells from healthy donors. In a pilot study, cell growth, death, and redox state were assessed, showing that L-M3 significantly reduced tumor cell proliferation and intracellular oxygen reactive species. No effect on PBMCs was detected. Thus, the antioxidant phytocomplex extracted from pomegranate quickly (15 min), at room temperature (30 °C), and efficiently showed potential anticancer activity without harming healthy cells
First measurement of production in pp collisions at = 7 TeV
The production of the charm-strange baryon is measured for
the first time at the LHC via its semileptonic decay into e
in pp collisions at TeV with the ALICE detector. The transverse
momentum () differential cross section multiplied by the branching
ratio is presented in the interval 1 8 GeV/ at
mid-rapidity, 0.5. The transverse momentum dependence of the
baryon production relative to the D meson production is
compared to predictions of event generators with various tunes of the
hadronisation mechanism, which are found to underestimate the measured
cross-section ratio.Comment: 22 pages, 6 captioned figures, 1 table, authors from page 17,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/412
Measurement of an excess in the yield of J/ at very low in Pb-Pb collisions at = 2.76 TeV
We report on the first measurement of an excess in the yield of J/ at
very low transverse momentum ( GeV/) in peripheral hadronic
Pb-Pb collisions at = 2.76 TeV, performed by ALICE at the
CERN LHC. Remarkably, the measured nuclear modification factor of J/ in
the rapidity range reaches about 7 (2) in the range 0-0.3
GeV/ in the 70-90% (50-70%) centrality class. The J/ production cross
section associated with the observed excess is obtained under the hypothesis
that coherent photoproduction of J/ is the underlying physics mechanism.
If confirmed, the observation of J/ coherent photoproduction in Pb-Pb
collisions at impact parameters smaller than twice the nuclear radius opens new
theoretical and experimental challenges and opportunities. In particular,
coherent photoproduction accompanying hadronic collisions may provide insight
into the dynamics of photoproduction and nuclear reactions, as well as become a
novel probe of the Quark-Gluon Plasma.Comment: 18 pages, 3 captioned figures, 1 table, authors from page 13,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/191
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