Displaying publications 1 - 20 of 188 in total

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  1. Wong SP, Er YX, Tan SM, Lee SC, Rajasuriar R, Lim YAL
    Transplant Cell Ther, 2023 Oct;29(10):633.e1-633.e13.
    PMID: 37422196 DOI: 10.1016/j.jtct.2023.06.016
    Mucositis is a debilitating complication of hematopoietic stem cell transplantation (HSCT). It is unclear how changes in the composition of microbiota, which are modulated by geographical location and ethnicity, may influence immune regulation leading to the development of mucositis, and the study of both oral and gut microbiota in a single population of autologous HSCT in the Asian region is lacking. The present study aimed to characterize the oral and gut microbiota changes, and the impact on both oral and lower gastrointestinal (GI) mucositis, with associated temporal changes in a population of adult recipients of autologous HSCT. Autologous HSCT recipients age ≥18 years were recruited from Hospital Ampang, Malaysia, between April 2019 and December 2020. Mucositis assessments were conducted daily, and blood, saliva, and fecal samples were collected prior to conditioning, on day 0, and at 7 days and 6 months post-transplantation. Longitudinal differences in alpha diversity and beta diversity were determined using the Wilcoxon signed-rank test and permutational multivariate analysis of variance, respectively. Changes in relative abundances of bacteria across time points were assessed using the microbiome multivariate analysis by linear models function. The combined longitudinal effects of clinical, inflammatory, and microbiota variables on mucositis severity were measured using the generalized estimating equation. Among the 96 patients analyzed, oral mucositis and diarrhea (representing lower GI mucositis) occurred in 58.3% and 95.8%, respectively. Alpha and beta diversities were significantly different between sample types (P < .001) and across time points, with alpha diversity reaching statistical significance at day 0 in fecal samples (P < .001) and at day +7 in saliva samples (P < .001). Diversities normalized to baseline by 6 months post-transplantation. Significant microbiota, clinical, and immunologic factors were associated with increasing mucositis grades. Increasing relative abundances of saliva Paludibacter, Leuconostoc, and Proteus were associated with higher oral mucositis grades, whereas increasing relative abundances of fecal Rothia and Parabacteroides were associated with higher GI mucositis grades. Meanwhile, increasing relative abundances of saliva Lactococcus and Acidaminococcus and fecal Bifidobacterium were associated with protective effects against worsening oral and GI mucositis grades, respectively. This study provides real-world evidence and insights into the dysbiosis of the microbiota in patients exposed to conditioning regimen during HSCT. Independent of clinical and immunologic factors, we demonstrated significant associations between relative bacteria abundances with the increasing severity of oral and lower GI mucositis. Our findings offer a potential rationale to consider the inclusion of preventive and restorative measures targeting oral and lower GI dysbiosis as interventional strategies to ameliorate mucositis outcome in HSCT recipients.
  2. Kuan JW, Su AT, Wong SP, Sim XY, Toh SG, Ong TC, et al.
    Transfus Apher Sci, 2015 Oct;53(2):196-204.
    PMID: 25910537 DOI: 10.1016/j.transci.2015.03.017
    There are few randomized trials comparing filgrastim and pegfilgrastim in peripheral blood stem cell mobilization (PBSCM). None of the trials studied the effects of the timing of pegfilgrastim administration on the outcomes of mobilization. We conducted a randomized triple blind control trial comparing the outcomes of filgrastim 5 µg/kg daily from day 3 onwards, 'early' pegfilgrastim 6 mg on day 3 and 'delayed' pegfilgrastim 6 mg on day 7 in cyclophosphamide PBSCM in patients with no previous history of mobilization. Peripheral blood (PB) CD34+ cell count was checked on day 8 and day 11 onward. Apheresis was started when PB CD34+ ≥ 10/µl from day 11 onward. The primary outcome was the successful mobilization rate, defined as cumulative collection of ≥2 × 10(6)/kg CD34+ cells in three or less apheresis. The secondary outcomes were the day of neutrophil and platelet engraftment post transplantation. There were 156 patients randomized and 134 patients' data analyzed. Pegfilgrastim 6 mg day 7 produced highest percentage of successful mobilization, 34 out of 48 (70.8%) analyzed patients, followed by daily filgrastim, 28 out of 44 (63.6%) and day 3 pegfilgrastim, 20 out of 42 (47.6%) (p = 0.075). Pegfilgrastim day 7 and daily filgrastim reported 1.48 (p = 0.014) and 1.49 (p = 0.013) times higher successful mobilization rate respectively as compared to pegfilgrastim day 3 after adjusting for disease, gender and exposure to myelotoxic agent. Multiple myeloma patients were three times more likely to achieve successful mobilization as compared to acute leukemia or lymphoma patients. Pegfilgrastim avoided the overshoot of white cells compared to filgrastim. There was no difference in the duration of both white cells and platelet recovery post transplantation between the three interventional arms.
  3. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(5):444.
    PMID: 31265003 DOI: 10.1140/epjc/s10052-019-6926-x
    A search for supersymmetry is presented based on events with at least one photon, jets, and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of 13



    Te



    . The data correspond to an integrated luminosity of 35.9



    fb

    -
    1



    and were recorded at the LHC with the CMS detector in 2016. The analysis characterizes signal-like events by categorizing the data into various signal regions based on the number of jets, the number of
    b
    -tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits are placed on the gluino and top squark pair production cross sections using several simplified models of supersymmetric particle production with gauge-mediated supersymmetry breaking. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120



    Ge



    and the production of top squarks with masses as large as 1230



    Ge



    are excluded at 95% confidence level.
  4. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Dragicevic M, et al.
    Eur Phys J C Part Fields, 2020;80(8):752.
    PMID: 32852485 DOI: 10.1140/epjc/s10052-020-8168-3
    A data sample of events from proton-proton collisions with at least two jets, and two isolated same-sign or three or more charged leptons, is studied in a search for signatures of new physics phenomena. The data correspond to an integrated luminosity of

    137




    fb


    -
    1




    at a center-of-mass energy of

    13

    TeV

    , collected in 2016-2018 by the CMS experiment at the LHC. The search is performed using a total of 168 signal regions defined using several kinematic variables. The properties of the events are found to be consistent with the expectations from standard model processes. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos or squarks for various decay scenarios in the context of supersymmetric models conserving or violating R parity. The observed lower mass limits are as large as

    2.1

    TeV

    for gluinos and

    0.9

    TeV

    for top and bottom squarks. To facilitate reinterpretations, model-independent limits are provided in a set of simplified signal regions.
  5. Khachatryan V, Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2017;77(11):751.
    PMID: 31999282 DOI: 10.1140/epjc/s10052-017-5140-y
    Measurements of the associated production of a
    Z
    boson with at least one jet originating from a b quark in proton-proton collisions at


    s

    =
    8

    TeV

    are presented. Differential cross sections are measured with data collected by the CMS experiment corresponding to an integrated luminosity of 19.8



    fb

    -
    1



    .
    Z
    bosons are reconstructed through their decays to electrons and muons. Cross sections are measured as a function of observables characterizing the kinematics of the
    b
    jet and the
    Z
    boson. Ratios of differential cross sections for the associated production with at least one
    b
    jet to the associated production with any jet are also presented. The production of a
    Z
    boson with at least two
    b
    jets is investigated, and differential cross sections are measured for the dijet system. Results are compared to theoretical predictions, testing two different flavour schemes for the choice of initial-state partons.
  6. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(2):90.
    PMID: 30814908 DOI: 10.1140/epjc/s10052-019-6556-3
    A search is presented for the single production of vector-like quarks in proton-proton collisions at


    s

    =
    13

    TeV

    . The data, corresponding to an integrated luminosity of 35.9



    fb

    -
    1



    , were recorded with the CMS experiment at the LHC. The analysis focuses on the vector-like quark decay into a top quark and a
    W
    boson, with one muon or electron in the final state. The mass of the vector-like quark candidate is reconstructed from hadronic jets, the lepton, and the missing transverse momentum. Methods for the identification of
    b
    quarks and of highly Lorentz boosted hadronically decaying top quarks and
    W
    bosons are exploited in this search. No significant deviation from the standard model background expectation is observed. Exclusion limits at 95% confidence level are set on the product of the production cross section and branching fraction as a function of the vector-like quark mass, which range from 0.3 to 0.03


    pb

    for vector-like quark masses of 700 to 2000


    GeV

    . Mass exclusion limits up to 1660


    GeV

    are obtained, depending on the vector-like quark type, coupling, and decay width. These represent the most stringent exclusion limits for the single production of vector-like quarks in this channel.
  7. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(11):969.
    PMID: 31886778 DOI: 10.1140/epjc/s10052-019-7451-7
    Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in

    p
    p

    collisions at


    s

    =
    8

    TeV as a function of photon transverse momentum (

    p

    T


    γ




    ), photon pseudorapidity (

    η

    γ




    ), and jet pseudorapidity (

    η
    jet

    ). The data correspond to an integrated luminosity of

    19.7



    fb

    -
    1




    that probe a broad range of the available phase space, for


    |


    η

    γ





    |
    <
    1.44


    and


    1.57
    <
    |


    η

    γ





    |
    <
    2.50


    ,


    |


    η
    jet


    |
    <
    2.5


    ,

    40
    <

    p

    T


    γ




    <
    1000




    GeV

    , and jet transverse momentum,

    p

    T

    jet

    , > 25


    GeV

    . The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.
  8. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Eur Phys J C Part Fields, 2017;77(12):845.
    PMID: 31985736 DOI: 10.1140/epjc/s10052-017-5317-4
    A search is presented for an excess of events with heavy-flavor quark pairs (

    t

    t
    ¯


    and

    b

    b
    ¯


    ) and a large imbalance in transverse momentum in data from proton-proton collisions at a center-of-mass energy of 13


    TeV

    . The data correspond to an integrated luminosity of 2.2



    fb

    -
    1



    collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in

    t

    t
    ¯


    and

    b

    b
    ¯


    final states in a simplified model. This analysis is also the first to perform a statistical combination of searches for dark matter produced with different heavy-flavor final states. The combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states.
  9. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Dragicevic M, et al.
    Eur Phys J C Part Fields, 2021;81(4):312.
    PMID: 34727148 DOI: 10.1140/epjc/s10052-021-08949-5
    This paper presents new sets of parameters ("tunes") for the underlying-event model of the H E R W I G 7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in H E R W I G 7 , and are obtained from a fit to minimum-bias data collected by the CMS experiment at s = 0.9 , 7, and 13 Te . The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the data.
  10. CMS Collaboration, Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, et al.
    Eur Phys J C Part Fields, 2021;81(7):629.
    PMID: 34727144 DOI: 10.1140/epjc/s10052-021-09236-z
    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV , corresponding to an integrated luminosity of 35.9 fb - 1 , are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
  11. Sirunyan AM, Tumasyan A, Adam W, Bergauer T, Dragicevic M, Erö J, et al.
    Eur Phys J C Part Fields, 2021;81(8):688.
    PMID: 34780582 DOI: 10.1140/epjc/s10052-021-09348-6
    A search is presented for a heavy vector resonance decaying into a Z boson and the standard model Higgs boson, where the Z boson is identified through its leptonic decays to electrons, muons, or neutrinos, and the Higgs boson is identified through its hadronic decays. The search is performed in a Lorentz-boosted regime and is based on data collected from 2016 to 2018 at the CERN LHC, corresponding to an integrated luminosity of 137 fb - 1 . Upper limits are derived on the production of a narrow heavy resonance Z ' , and a mass below 3.5 and 3.7 Te is excluded at 95% confidence level in models where the heavy vector boson couples predominantly to fermions and to bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z ' model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3 fb for a Z ' mass between 0.8 and 4.6 Te , respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay.
  12. Sirunyan AM, Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, et al.
    Eur Phys J C Part Fields, 2021;81(9):800.
    PMID: 34781320 DOI: 10.1140/epjc/s10052-021-09538-2
    The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton-proton collisions at s = 13 TeV in 2015 and 2016, is reported. The absolute luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3 fb - 1 in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.
  13. Sirunyan AM, Tumasyan A, Adam W, Bergauer T, Dragicevic M, Erö J, et al.
    Eur Phys J C Part Fields, 2021;81(9):852.
    PMID: 34727147 DOI: 10.1140/epjc/s10052-021-09570-2
    Collinear (small-angle) and large-angle, as well as soft and hard radiations are investigated in three-jet and Z  + two-jet events collected in proton-proton collisions at the LHC. The normalized production cross sections are measured as a function of the ratio of transverse momenta of two jets and their angular separation. The measurements in the three-jet and Z  + two-jet events are based on data collected at a center-of-mass energy of 8 TeV , corresponding to an integrated luminosity of 19.8 fb - 1 . The Z  + two-jet events are reconstructed in the dimuon decay channel of the Z  boson. The three-jet measurement is extended to include s = 13 TeV data corresponding to an integrated luminosity of 2.3 fb - 1 . The results are compared to predictions from event generators that include parton showers, multiple parton interactions, and hadronization. The collinear and soft regions are in general well described by parton showers, whereas the regions of large angular separation are often best described by calculations using higher-order matrix elements.
  14. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(9):773.
    PMID: 31713548 DOI: 10.1140/epjc/s10052-019-7276-4
    A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Δ ϕ 12 , is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 Te and corresponding to an integrated luminosity of 35.9 fb - 1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177 ∘ < Δ ϕ 12 < 180 ∘ . The 2- and 3-jet measurements are not simultaneously described by any of models.
  15. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(7):564.
    PMID: 31397444 DOI: 10.1140/epjc/s10052-019-7058-z
    A search is presented for a heavy pseudoscalar boson A decaying to a Z  boson and a Higgs boson with mass of 125 GeV . In the final state considered, the Higgs boson decays to a bottom quark and antiquark, and the Z  boson decays either into a pair of electrons, muons, or neutrinos. The analysis is performed using a data sample corresponding to an integrated luminosity of 35.9 fb - 1 collected in 2016 by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13 Te . The data are found to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the A boson mass range between 225 and 1000 GeV .
  16. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(4):364.
    PMID: 31180390 DOI: 10.1140/epjc/s10052-019-6855-8
    A search for the pair production of heavy vector-like partners T and B of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton-proton collisions at s = 13 Te . The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9 fb - 1 . Final states studied for T T ¯ production include those where one of the T quarks decays via T → t Z and the other via T → b W , t Z , or t H , where H is a Higgs boson. For the B B ¯ case, final states include those where one of the B quarks decays via B → b Z and the other B → t W , b Z , or b H . Events with two oppositely charged electrons or muons, consistent with coming from the decay of a Z boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the T and B quarks for a range of branching fractions. Assuming 100% branching fractions for T → t Z , and B → b Z , T and B quark mass values below 1280 and 1130 Ge , respectively, are excluded.
  17. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(4):313.
    PMID: 31031568 DOI: 10.1140/epjc/s10052-019-6788-2
    A top quark mass measurement is performed using 35.9 fb - 1 of LHC proton-proton collision data collected with the CMS detector at s = 13 TeV . The measurement uses the t t ¯ all-jets final state. A kinematic fit is performed to reconstruct the decay of the t t ¯  system and suppress the multijet background. Using the ideogram method, the top quark mass ( m t ) is determined, simultaneously constraining an additional jet energy scale factor ( JSF ). The resulting value of m t = 172.34 ± 0.20 (stat+JSF) ± 0.70 (syst) GeV is in good agreement with previous measurements. In addition, a combined measurement that uses the t t ¯ lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an m t measurement of 172.26 ± 0.07 (stat+JSF) ± 0.61 (syst) GeV . This is the first combined m t extraction from the lepton+jets and all-jets channels through a single likelihood function.
  18. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(2):140.
    PMID: 31265001 DOI: 10.1140/epjc/s10052-018-5607-5
    A search for standard model production of four top quarks ( t t ¯ t t ¯ ) is reported using events containing at least three leptons ( e , μ ) or a same-sign lepton pair. The events are produced in proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9 fb - 1 . Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the t t ¯ t t ¯ cross section is measured to be 16 . 9 - 11.4 + 13.8 fb , in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level.
  19. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(4):291.
    PMID: 31007582 DOI: 10.1140/epjc/s10052-018-5740-1
    A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at s = 13 TeV , corresponding to an integrated luminosity of 35.9 fb - 1 . The results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like Higgs boson produced in association with the Z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. No significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel.
  20. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Eur Phys J C Part Fields, 2018;78(3):242.
    PMID: 31264999 DOI: 10.1140/epjc/s10052-018-5691-6
    Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at s = 7 TeV . The jets were required to have transverse momentum p T jet > 40 GeV and pseudorapidity 1.5 < | η jet | < 4.7 , and to have values of η jet with opposite signs. The data used for this study were collected with the CMS detector during low-luminosity running at the LHC, and correspond to an integrated luminosity of 8 pb - 1 . Events with no charged particles with p T > 0.2 GeV in the interval - 1 < η < 1 between the jets are observed in excess of calculations that assume no color-singlet exchange. The fraction of events with such a rapidity gap, amounting to 0.5-1% of the selected dijet sample, is measured as a function of the p T of the second-leading jet and of the rapidity separation between the jets. The data are compared to previous measurements at the Tevatron, and to perturbative quantum chromodynamics calculations based on the Balitsky-Fadin-Kuraev-Lipatov evolution equations, including different models of the non-perturbative gap survival probability.
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