Displaying publications 1 - 20 of 57 in total

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  1. Emelia O, Rahana AR, Mohamad Firdaus A, Cheng HS, Nursyairah MS, Fatinah AS, et al.
    Trop Biomed, 2014 Dec;31(4):633-40.
    PMID: 25776588 MyJurnal
    An accurate diagnosis for toxoplasmosis is crucial for pregnant women as this infection may lead to severe sequelae in the fetus. The value of IgG avidity assay as a tool to determine acute and chronic toxoplasmosis during pregnancy was evaluated in Universiti Kebangsaan Malaysia Medical Centre (UKMMC). In this study, 281 serum samples from 281 pregnant women in various trimesters were collected. These samples were assayed using specific anti-Toxoplasma IgM and IgG antibodies, followed by IgG avidity test. The overall seroprevalence of toxoplasmosis in pregnant women was 35.2% (33.5% for anti-Toxoplasma IgG and 1.8% for both anti-Toxoplasma IgG and IgM antibodies). Of 5 (1.8%) serum samples positive for IgM ELISA, 4 had high-avidity antibodies, suggesting past infection and one sample with borderline avidity index. Two samples with low avidity were from IgM negative serum samples. The IgG avidity assay exhibited an excellent specificity of 97.6% and a negative predictive value (NPV) of 95.6%. The study also demonstrated no significant correlation between avidity indexes of the sera with IgG (r=0.12, p=0.24) and IgM (r=-0.00, p=0.98), suggesting the complementary needs of the two tests for a better diagnosis outcome. These findings highlight the usefulness of IgG avidity assay in excluding a recently acquired toxoplasmosis infection in IgM-positive serum sample.
  2. Li T, Cheng H, Li Y, Mou Z, Zhu X, Wu W, et al.
    Sci Total Environ, 2023 Jul 10;881:163204.
    PMID: 37044342 DOI: 10.1016/j.scitotenv.2023.163204
    Tropical primary forests are being destroyed at an alarming rate and converted for other land uses which is expected to greatly influence soil carbon (C) cycling. However, our understanding of how tropical forest conversions affect the accumulation of compounds in soil functional C pools remains unclear. Here, we collected soils from primary forests (PF), secondary forests (SF), oil-palm (OP), and rubber plantations (RP), and assessed the accumulation of plant- and microbial-derived compounds within soil organic carbon (SOC), particulate (POC) and mineral-associated (MAOC) organic C. PF conversion to RP greatly decreased SOC, POC, and MAOC concentrations, whereas conversion to SF increased POC concentrations and decreased MAOC concentrations, and conversion to OP only increased POC concentrations. PF conversion to RP decreased lignin concentrations and increased amino sugar concentrations in SOC pools which increased the stability of SOC, whereas conversion to SF only increased the lignin concentrations in POC, and conversion to OP just increased lignin concentrations in POC and decreased it in MAOC. We observed divergent dynamics of amino sugars (decrease) and lignin (increase) in SOC with increasing SOC. Only lignin concentrations increased in POC with increasing POC and amino sugars concentrations decreased in MAOC with increasing MAOC. Conversion to RP significantly decreased soil enzyme activities and microbial biomasses. Lignin accumulation was associated with microbial properties, whereas amino sugar accumulation was mainly associated with soil nutrients and stoichiometries. These results suggest that the divergent accumulation of plant- and microbial-derived C in SOC was delivered by the distribution and original composition of functional C pools under forest conversions. Forest conversions changed the formation and stabilization processes of SOC in the long run which was associated with converted plantations and management. The important roles of soil nutrients and stoichiometry also provide a natural-based solution to enhance SOC sequestration via nutrient management in tropical forests.
  3. Chew CH, Goh PP, Lim TO
    N Engl J Med, 2016 04 07;374(14):1388.
    PMID: 27050221 DOI: 10.1056/NEJMc1514451
  4. Chang TC, Cheng HH
    Med J Malaysia, 1994 Dec;49(4):351-4.
    PMID: 7545778
    The use of maternal age alone to identify pregnant mothers at risk of a fetus with Down's syndrome has recently been supplemented by maternal serum screening using biochemical markers such as alpha-protein, human chorionic gonadotrophin and oestriol. These tests have been reported to increase the sensitivity of antenatal detection of such fetuses from 35% to 67% with a false positive rate of 5%. However, these maternal serum markers may be affected by maternal weight, the smoking history of mothers and diabetes mellitus. Furthermore, such sensitivities are achieved only when gestational age is assessed accurately by ultrasound. Many further studies need to be carried out before the introduction of maternal serum screening into routine obstetric practice in Singapore. These include studies on the incidence of Down's syndrome in the local population, studies on the distribution of these serum markers in the second trimester of pregnancy, sensitivities and positive predictive values of such a test in the local population as well as the socio-economic implications of implementing such a screening test in the local obstetric population.
  5. Lee MK, Cheng HM, Ng SC, Menaka N, Tan CT, Wang F
    Med J Malaysia, 1993 Sep;48(3):330-5.
    PMID: 8183147
    Cerebral infarction in the young is likely to be non-atheromatous. While in previous studies no cause has been found in 40% to 50% of patients, an increasing role for haemorheological factors is becoming apparent. Among these, an association between antiphospholipid antibodies (aPLs) and ischaemic cerebrovascular disease is now well-recognised. This entity has not been previously reported in Malaysian patients. In a study of 80 patients with stroke below the age of 50 years who were seen at the University Hospital, Kuala Lumpur, between January 1982 and May 1992, 3 patients with ischaemic cerebral infarction were found to have aPLs. aPLs was detected using ELISA method for anticardiolipin antibodies (aCLs), and presence of lupus anticoagulant (LA) was established by kaolin clotting time, thromboplastin inhibition test and platelet neutralisation procedure. Only 1 patient had active systemic lupus erythematous. Cerebrovascular events were recurrent in one of the 2 non-lupus patients. aPL-related stroke should be considered in young patients who have cerebral ischaemia occurring without obvious cause. More cases are likely to emerge in Malaysia with active screening.
  6. Sun J, Cheng H, Hassan MRA, Chan HK, Piedagnel JM
    Lancet Reg Health West Pac, 2021 Nov;16:100261.
    PMID: 34590064 DOI: 10.1016/j.lanwpc.2021.100261
    Background: To discuss a range of strategic options for China to improve the accessibility of direct antiviral agents (DAAs) as the treatment for hepatitis C. Methods: We adopted a narrative review approach for comprehensive comparisons and in-depth analyses of the country context, and barriers of increasing the DAA treatment rate of hepatitis C in Malaysia and China, and how the two countries have been navigating the hepatitis C agenda. Findings: Malaysia adopted a series of successful strategies to scale up the diagnosis of hepatitis C and DAA treatment, which have valuable implications for China. Interpretation: The potential game-changing strategies for China to adapt from Malaysian experiences range from the stepping-up of political commitment and leadership, enhanced market competition, simplified and decentralized treatment at the strengthened primary care level, integrated healthcare services, coordinated government initiatives, to multi-organizational participation and civil society's active role in raising public awareness, and training of non-specialist physicians. Embarking on scale-up of hepatitis C treatment marks another contribution of China to improve the health of not only the Chinese citizens but also mankind, which is an important component for building healthy Chinese and global communities. Funding: No funding supported this study.
  7. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Eur Phys J C Part Fields, 2023;83(8):722.
    PMID: 37578844 DOI: 10.1140/epjc/s10052-023-11833-z
    The production of Z bosons associated with jets is measured in pp collisions at s=13TeV with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3fb-1. The multiplicity of jets with transverse momentum pT>30GeV is measured for different regions of the Z boson's pT(Z), from lower than 10GeV to higher than 100GeV. The azimuthal correlation Δϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of pT(Z). The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low pT(Z) regions.
  8. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Eur Phys J C Part Fields, 2023;83(7):587.
    PMID: 37440247 DOI: 10.1140/epjc/s10052-023-11630-8
    New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia  8 event generator, are obtained based on the default CMS pythia  8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies s=7 and 13TeV, and by the CDF experiment at 1.96TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13TeV including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair (tt¯) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of tt¯ events in the semileptonic channel at 13TeV.
  9. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Eur Phys J C Part Fields, 2023;83(10):933.
    PMID: 37855556 DOI: 10.1140/epjc/s10052-023-11952-7
    A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at s=13TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138fb-1. The 95% confidence level upper limit set on the branching fraction of the 125GeV Higgs boson to invisible particles, B(H→inv), is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous B(H→inv) searches carried out at s=7, 8, and 13TeV in complementary production modes. The combined upper limit at 95% confidence level on B(H→inv) is 0.15 (0.08 expected).
  10. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Eur Phys J C Part Fields, 2023;83(10):963.
    PMID: 37906635 DOI: 10.1140/epjc/s10052-023-12050-4
    The mass of the top quark is measured in 36.3fb-1 of LHC proton-proton collision data collected with the CMS detector at s=13TeV. The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables per event to extract the top quark mass. The top quark mass is measured to be 171.77±0.37GeV. This approach significantly improves the precision over previous measurements.
  11. Lai SM, Lim KW, Cheng HK
    Singapore Med J, 1990 Oct;31(5):463-5.
    PMID: 2259944
    Margosa Oil is an extract of the seed of the Neem tree and is widely used as a traditional medicine by Indians in India, Sri Lanka, Burma, Thailand, Malaysia and Indonesia. Used mainly for external applications, it is often administered orally to neonates and infants regularly in small amounts. Margosa Oil causes toxic encephalopathy particularly in infants and young children. The usual features are vomiting, drowsiness, tachypnea and recurrent generalised seizures. Leucocytosis and metabolic acidosis are significant laboratory findings. Management is aimed primarily towards the control of convulsions although supportive management is equally important. Prognosis is usually good but fatalities and neurological deficits have been reported. We report here two infants with Margosa Oil poisoning presenting with encephalopathy.
  12. Zhang S, Zhang R, Yin X, Lu Y, Cheng H, Pan Y, et al.
    Reprod Sci, 2023 Nov;30(11):3325-3338.
    PMID: 37308799 DOI: 10.1007/s43032-023-01282-0
    Endometrial injury is one of the leading causes of female infertility and is caused by intrauterine surgery, endometrial infection, repeated abortion, or genital tuberculosis. Currently, there is little effective treatment to restore the fertility of patients with severe intrauterine adhesions and thin endometrium. Recent studies have confirmed the promising therapeutic effects of mesenchymal stem cell transplantation on various diseases with definite tissue injury. The aim of this study is to investigate the improvements of menstrual blood-derived endometrial stem cells (MenSCs) transplantation on functional restoration in the endometrium of mouse model. Therefore, ethanol-induced endometrial injury mouse models were randomly divided into two groups: the PBS-treated group, and the MenSCs-treated group. As expected, the endometrial thickness and gland number in the endometrium of MenSCs-treated mice were significantly improved compared to those of PBS-treated mice (P 
  13. Sun T, Wang D, Mirkin MV, Cheng H, Zheng JC, Richards RM, et al.
    Proc Natl Acad Sci U S A, 2019 06 11;116(24):11618-11623.
    PMID: 31127040 DOI: 10.1073/pnas.1821091116
    The catalytic activity of low-dimensional electrocatalysts is highly dependent on their local atomic structures, particularly those less-coordinated sites found at edges and corners; therefore, a direct probe of the electrocatalytic current at specified local sites with true nanoscopic resolution has become critically important. Despite the growing availability of operando imaging tools, to date it has not been possible to measure the electrocatalytic activities from individual material edges and directly correlate those with the local structural defects. Herein, we show the possibility of using feedback and generation/collection modes of operation of the scanning electrochemical microscope (SECM) to independently image the topography and local electrocatalytic activity with 15-nm spatial resolution. We employed this operando microscopy technique to map out the oxygen evolution activity of a semi-2D nickel oxide nanosheet. The improved resolution and sensitivity enables us to distinguish the higher activities of the materials' edges from that of the fully coordinated surfaces in operando The combination of spatially resolved electrochemical information with state-of-the-art electron tomography, that unravels the 3D complexity of the edges, and ab initio calculations allows us to reveal the intricate coordination dependent activity along individual edges of the semi-2D material that is not achievable by other methods. The comparison of the simulated line scans to the experimental data suggests that the catalytic current density at the nanosheet edge is ∼200 times higher than that at the NiO basal plane.
  14. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Phys Rev Lett, 2023 Sep 22;131(12):121901.
    PMID: 37802954 DOI: 10.1103/PhysRevLett.131.121901
    The dependence of the ratio between the B_{s}^{0} and B^{+} hadron production fractions, f_{s}/f_{u}, on the transverse momentum (p_{T}) and rapidity of the B mesons is studied using the decay channels B_{s}^{0}→J/ψϕ and B^{+}→J/ψK^{+}. The analysis uses a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 61.6  fb^{-1}. The f_{s}/f_{u} ratio is observed to depend on the B p_{T} and to be consistent with becoming asymptotically constant at large p_{T}. No rapidity dependence is observed. The ratio of the B^{0} to B^{+} meson production fractions, f_{d}/f_{u}, is also measured, for the first time in proton-proton collisions, using the B^{0}→J/ψK^{*0} decay channel. The result is found to be within 1 standard deviation of unity and independent of p_{T} and rapidity, as expected from isospin invariance.
  15. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Phys Rev Lett, 2023 Oct 13;131(15):151803.
    PMID: 37897747 DOI: 10.1103/PhysRevLett.131.151803
    We present an observation of photon-photon production of τ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404  μb^{-1} collected by the CMS experiment at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02  TeV. The γγ→τ^{+}τ^{-} process is observed for τ^{+}τ^{-} events with a muon and three charged hadrons in the final state. The measured fiducial cross section is σ(γγ→τ^{+}τ^{-})=4.8±0.6(stat)±0.5(syst)  μb, where the second (third) term corresponds to the statistical (systematic) uncertainty in σ(γγ→τ^{+}τ^{-}) in agreement with leading-order QED predictions. Using σ(γγ→τ^{+}τ^{-}), we estimate a model-dependent value of the anomalous magnetic moment of the τ lepton of a_{τ}=0.001_{-0.089}^{+0.055}.
  16. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Phys Rev Lett, 2023 Jul 07;131(1):011803.
    PMID: 37478454 DOI: 10.1103/PhysRevLett.131.011803
    The first search exploiting the vector boson fusion process to probe heavy Majorana neutrinos and the Weinberg operator at the LHC is presented. The search is performed in the same-sign dimuon final state using a proton-proton collision dataset recorded at sqrt[s]=13  TeV, collected with the CMS detector and corresponding to a total integrated luminosity of 138  fb^{-1}. The results are found to agree with the predictions of the standard model. For heavy Majorana neutrinos, constraints on the squared mixing element between the muon and the heavy neutrino are derived in the heavy neutrino mass range 50 GeV-25 TeV; for masses above 650 GeV these are the most stringent constraints from searches at the LHC to date. A first test of the Weinberg operator at colliders provides an observed upper limit at 95% confidence level on the effective μμ Majorana neutrino mass of 10.8 GeV.
  17. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Phys Rev Lett, 2023 Aug 11;131(6):061801.
    PMID: 37625071 DOI: 10.1103/PhysRevLett.131.061801
    A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cc[over ¯], produced in association with a leptonically decaying V (W or Z) boson is presented. The search is performed with proton-proton collisions at sqrt[s]=13  TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138  fb^{-1}. Novel charm jet identification and analysis methods using machine learning techniques are employed. The analysis is validated by searching for Z→cc[over ¯] in VZ events, leading to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed (expected) upper limit on σ(VH)B(H→cc[over ¯]) is 0.94 (0.50_{-0.15}^{+0.22})pb at 95% confidence level (C.L.), corresponding to 14 (7.6_{-2.3}^{+3.4}) times the standard model prediction. For the Higgs-charm Yukawa coupling modifier, κ_{c}, the observed (expected) 95% C.L. interval is 1.1
  18. Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, Chatterjee S, Damanakis K, et al.
    Phys Rev Lett, 2023 Jul 28;131(4):041803.
    PMID: 37566864 DOI: 10.1103/PhysRevLett.131.041803
    A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138  fb^{-1} collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, κ_{2V}, excluding κ_{2V}=0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values.
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