5,846 research outputs found

    Blockade of T-cell activation by dithiocarbamates involves novel mechanisms of inhibition of nuclear factor of activated T cells.

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    Dithiocarbamates (DTCs) have recently been reported as powerful inhibitors of NF-kappaB activation in a number of cell types. Given the role of this transcription factor in the regulation of gene expression in the inflammatory response, NF-kappaB inhibitors have been suggested as potential therapeutic drugs for inflammatory diseases. We show here that DTCs inhibited both interleukin 2 (IL-2) synthesis and membrane expression of antigens which are induced during T-cell activation. This inhibition, which occurred with a parallel activation of c-Jun transactivating functions and expression, was reflected by transfection experiments at the IL-2 promoter level, and involved not only the inhibition of NF-kappaB-driven reporter activation but also that of nuclear factor of activated T cells (NFAT). Accordingly, electrophoretic mobility shift assays (EMSAs) indicated that pyrrolidine DTC (PDTC) prevented NF-kappaB, and NFAT DNA-binding activity in T cells stimulated with either phorbol myristate acetate plus ionophore or antibodies against the CD3-T-cell receptor complex and simultaneously activated the binding of AP-1. Furthermore, PDTC differentially targeted both NFATp and NFATc family members, inhibiting the transactivation functions of NFATp and mRNA induction of NFATc. Strikingly, Western blotting and immunocytochemical experiments indicated that PDTC promoted a transient and rapid shuttling of NFATp and NFATc, leading to their accelerated export from the nucleus of activated T cells. We propose that the activation of an NFAT kinase by PDTC could be responsible for the rapid shuttling of the NFAT, therefore transiently converting the sustained transactivation of this transcription factor that occurs during lymphocyte activation, and show that c-Jun NH2-terminal kinase (JNK) can act by directly phosphorylating NFATp. In addition, the combined inhibitory effects on NFAT and NF-KB support a potential use of DTCs as immunosuppressants

    Determinants of a transcriptionally competent environment at the GM-CSF promoter

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    Granulocyte macrophage-colony stimulating factor (GM-CSF) is produced by T cells, but not B cells, in response to immune signals. GM-CSF gene activation in response to T-cell stimulation requires remodelling of chromatin associated with the gene promoter, and these changes do not occur in B cells. While the CpG methylation status of the murine GM-CSF promoter shows no correlation with the ability of the gene to respond to activation, we find that the basal chromatin environment of the gene promoter influences its ability to respond to immune signals. In unstimulated T cells but not B cells, the GM-CSF promoter is selectively marked by enrichment of histone acetylation, and association of the chromatin-remodelling protein BRG1. BRG1 is removed from the promoter upon activation concomitant with histone depletion and BRG1 is required for efficient chromatin remodelling and transcription. Increasing histone acetylation at the promoter in T cells is paralleled by increased BRG1 recruitment, resulting in more rapid chromatin remodelling, and an associated increase in GM-CSF mRNA levels. Furthermore, increasing histone acetylation in B cells removes the block in chromatin remodelling and transcriptional activation of the GM-CSF gene. These data are consistent with a model in which histone hyperacetylation and BRG1 enrichment at the GM-CSF promoter, generate a chromatin environment competent to respond to immune signals resulting in gene activation

    A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector

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    Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 meters of water equivalent, have been used to infer the nuclear composition of cosmic rays in the "knee" region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 800,000 - 13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review

    Radiation hardness qualification of PbWO4 scintillation crystals for the CMS Electromagnetic Calorimeter

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    This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPEnsuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered

    Balloon kyphoplasty in the treatment of metastatic disease of the spine: a 2-year prospective evaluation

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    There is currently little data on the longer term efficacy and safety of balloon kyphoplasty (BKP) in patients with metastatic vertebral compression fractures (VCFs). To prospectively assess the long-term efficacy and safety of BKP in treating thoracic and lumbar spinal metastatic fractures that result in pain or instability. Sixty-five patients (37 men, mean age: 66 years) underwent 99 BKP procedures. Patient-related outcomes of pain visual analogue scale (VAS) and Oswestry Disability Index were assessed pre- and post-operatively and after 3, 6, 12 and 24 months. Correction of vertebral height and kyphotic deformity were assessed by radiographic measurements. Mean pain VAS and Oswestry Disability Index significantly improved from pre- to post-treatment (P < 0.0001), this improvement being sustained up to 24-month follow up. A gain in height restoration and a reduction of the post-operative kyphotic angle were seen post-operatively and at 3 months although these radiographic outcomes returned to pre-operative levels at 12 months. BKP was associated with a rate of cement leakage and incidence vertebral fracture of 12 and 8%, respectively. No symptomatic cement leaks or serious adverse events were seen during the 24 months of follow up. BKP is a minimally invasive procedure that provides immediate and long-term pain relief and improvement in functional ability in selected patients with metastatic VCFs. The procedure appears to have good long-term safety

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

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    A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

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    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

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    Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated
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