Displaying publications 1 - 20 of 219 in total

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  1. Wang YG, Hassan MD, Shariff M, Zamri SM, Chen X
    Dis Aquat Organ, 1999 Dec 22;39(1):1-11.
    PMID: 11407399
    Since 1994, white spot syndrome virus (WSSV) has been detected in cultured shrimp Penaeus monodon in Peninsular Malaysia. The gross signs, target organs and histo-cytopathology for the viral infection were studied and it was found to infect most organs and tissues including oocytes, but not hepatopancreatocytes and epithelial cells of the midgut, which were regarded as refractory tissues. Based on a time-sequence of ultrastructural cytopathology, 4 cytopathic profiles and 6 phases of viral morphogenesis were described. The virions were elliptical to short rods with trilamilar envelopes that measured 305 +/- 30 x 127 +/- 11 nm. Viral nucleosomes were often present singly in infected nuclei and were associated with the early stages of viral replication. The structure of WSSV pathognomonic white, cuticular lesions was examined at the microscopic and ultrastructural levels and the mechanism of their formation appeared to be related to the disruption of exudate transfer from epithelial cells to the cuticle via cuticular pore canals.
  2. Choong YK, Chen X, Jamal JA, Wang Q, Lan J
    Int J Med Mushrooms, 2012;14(3):295-305.
    PMID: 22577979
    Spaceflight represents a complex environmental condition. Space mutagenesis breeding has achieved marked results over the years. The objective of this study is to determine the chemical changes in medicinal mushroom Ganoderma lucidum cultivated after spaceflight in 1999. Fourier transform infrared (FTIR) and two-dimensional infrared (2DIR) correlation spectroscopy were used in analysis. The sample Sx and its control Cx showed the least dissimilarities in one-dimensional FTIR spectra, but absorbance of Sx is twice as high as Cx. Sx presented a clear peak at 1648 cm in 2nd derivative spectra, which could not be detected in the Cx. The 2DIR spectra showed the intensity of Sx in the range 1800-1400 cm-1 for protein is higher than the control. The sample Sx produced some carbohydrate peaks in the area of 889 cm-1 compared with the Cx. The spaceflight set up an extreme condition and caused changes of chemical properties in G. lucidum strain.
  3. Chen X, Tan X, Li J, Jin Y, Gong L, Hong M, et al.
    PLoS One, 2013;8(12):e82861.
    PMID: 24340064 DOI: 10.1371/journal.pone.0082861
    Coxsackievirus A16 (CVA16) is responsible for nearly 50% of all the confirmed hand, foot, and mouth disease (HFMD) cases in mainland China, sometimes it could also cause severe complications, and even death. To clarify the genetic characteristics and the epidemic patterns of CVA16 in mainland China, comprehensive bioinfomatics analyses were performed by using 35 CVA16 whole genome sequences from 1998 to 2011, 593 complete CVA16 VP1 sequences from 1981 to 2011, and prototype strains of human enterovirus species A (EV-A). Analysis on complete VP1 sequences revealed that subgenotypes B1a and B1b were prevalent strains and have been co-circulating in many Asian countries since 2000, especially in mainland China for at least 13 years. While the prevalence of subgenotype B1c (totally 20 strains) was much limited, only found in Malaysia from 2005 to 2007 and in France in 2010. Genotype B2 only caused epidemic in Japan and Malaysia from 1981 to 2000. Both subgenotypes B1a and B1b were potential recombinant viruses containing sequences from other EV-A donors in the 5'-untranslated region and P2, P3 non-structural protein encoding regions.
  4. Chen X, Keong CY, Mei X, Lan J
    PMID: 24508891 DOI: 10.1016/j.saa.2014.01.048
    Spaceflight represents a complex environmental condition. Space mutagenesis breeding has achieved and marked certain results over the years. This method was employed in our previous studies in order to obtain improved germplasm of Isatis indigotica. This study is to determine the chemical changes in I. indigotica seeds carried after Chinese first spaceship (Shenzhou I). Fourier transform infrared (FTIR), second derivative and two-dimensional infrared (2DIR) correlation spectroscopy were used in analysis. Not much differences between the two spectra were found except the peaks in the range of 1500-1200 cm(-)(1) which was about 7 cm(-)(1) different and indicated the absorption could be initialed from different bonds. SP4 showed different derivative compared with C4 in the second derivative spectra of 1200-800 cm(-)(1). The stronger signal of 2DIR in SP4 indicated the protein content of the seed was changed after spaceflight. It is concluded that spaceflight provided an extreme condition that caused changes of chemical properties in I. indigotica.
  5. Lu J, Li Y, Hu D, Chen X, Liu Y, Wang L, et al.
    Saudi J Biol Sci, 2016 Jan;23(1):S22-31.
    PMID: 26858562 DOI: 10.1016/j.sjbs.2015.06.012
    A novel interpenetrating network hydrogel for drug controlled release, composed of modified poly(aspartic acid) (KPAsp) and carboxymethyl chitosan (CMCTS), was prepared in aqueous system. The surface morphology and composition of hydrogels were characterized by SEM and FTIR. The swelling properties of KPAsp, KPAsp/CMCTS semi-IPN and KPAsp/CMCTS IPN hydrogels were investigated and the swelling dynamics of the hydrogels was analyzed based on the Fickian equation. The pH, temperature and salt sensitivities of hydrogels were further studied, and the prepared hydrogels showed extremely sensitive properties to pH, temperature, the ionic salts kinds and concentration. The results of controlled drug release behaviors of the hydrogels revealed that the introduction of IPN observably improved the drug release properties of hydrogels, the release rate of drug from hydrogels can be controlled by the structure of the hydrogels and pH value of the external environment, a relative large amount of drug released was preferred under simulated intestinal fluid. These results illustrated high potential of the KPAsp/CMCTS IPN hydrogels for application as drug carriers.
  6. Chen X, Li J, Xiao S, Liu X
    Gene, 2016 Jan 15;576(1 Pt 3):537-43.
    PMID: 26546834 DOI: 10.1016/j.gene.2015.11.001
    Paphia textile is an important, aquaculture bivalve clam species distributed mainly in China, Philippines, and Malaysia. Recent studies of P. textile have focused mainly on artificial breeding and nutrition analysis, and the transcriptome and genome of P. textile have rarely been reported. In this work, the transcriptome of P. textile foot tissue was sequenced on an Illumina HiSeq™ 2000 platform. A total of 20,219,795 reads were generated, resulting in 4.08 Gb of raw data. The raw reads were cleaned and assembled into 54,852 unigenes with an N50 length of 829 bp. Of these unigenes, 38.92% were successfully annotated based on their matches to sequences in seven public databases. Among the annotated unigenes, 14,571 were assigned Gene Ontology terms, 5448 were classified to Clusters of Orthologous Groups categories, and 6738 were mapped to 228 pathways in the Kyoto Encyclopedia of Genes and Genomes database. For functional marker development, 5605 candidate simple sequence repeats were identified in the transcriptome and 80 primer pairs were selected randomly and amplified in a wild population of P. textile. A total of 36 loci that exhibited obvious repeat length polymorphisms were detected. The transcriptomic data and microsatellite markers will provide valuable resources for future functional gene analyses, genetic map construction, and quantitative trait loci mapping in P. textile.
  7. Chen X, Li QY, Li GD, Xu FJ, Jiang Y, Han L, et al.
    Antonie Van Leeuwenhoek, 2016 Sep;109(9):1177-83.
    PMID: 27260265 DOI: 10.1007/s10482-016-0718-1
    A novel aerobic, non-motile, Gram-positive, rod-shaped actinobacterium, designated YIM 100951(T), was isolated from the faeces of civets (Viverra zibetha) living in the National Nature Protect Region in Selangor, Malaysia. Strain YIM 100951(T) shows high similarities with Microbacterium barkeri DSM 20145(T) (97.6 %), Microbacterium oryzae MB10(T) (97.3 %), Microbacterium lemovicicum ViU22(T) (97.1 %) and Microbacterium indicum BBH6(T) (97.0 %) based on their 16S rRNA genes. However, phylogenetic analysis showed that strain YIM 100951(T) formed a clade with Microbacterium halotolerans YIM 70130(T) (96.7 %), Microbacterium populi 10-107-8(T) (96.7 %) and Microbacterium sediminis YLB-01(T) (96.9 %). DNA-DNA hybridization was carried out between strains YIM 100951(T) and M. barkeri DSM 20145(T), the result showed a value of 23.2 ± 4.5 %. In addition, some of the physiological, biochemical and chemotaxonomic characteristics of strain YIM 100951(T) are different from the closely related strains. Thus, we suggest that strain YIM 100951(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium gilvum sp. nov. is proposed. The type strain is YIM 100951(T) (=DSM 26235(T) = CCTCC AB 2012971(T)).
  8. Sing KW, Wang WZ, Wan T, Lee PS, Li ZX, Chen X, et al.
    Genome, 2016 Oct;59(10):827-839.
    PMID: 27327818
    Urbanization requires the conversion of natural land cover to cover with human-constructed elements and is considered a major threat to biodiversity. Bee populations, globally, are under threat; however, the effect of rapid urban expansion in Southeast Asia on bee diversity has not been investigated. Given the pressing issues of bee conservation and urbanization in Southeast Asia, coupled with complex factors surrounding human-bee coexistence, we investigated bee diversity and human perceptions of bees in four megacities. We sampled bees and conducted questionnaires at three different site types in each megacity: a botanical garden, central business district, and peripheral suburban areas. Overall, the mean species richness and abundance of bees were significantly higher in peripheral suburban areas than central business districts; however, there were no significant differences in the mean species richness and abundance between botanical gardens and peripheral suburban areas or botanical gardens and central business districts. Urban residents were unlikely to have seen bees but agreed that bees have a right to exist in their natural environment. Residents who did notice and interact with bees, even though being stung, were more likely to have positive opinions towards the presence of bees in cities.
  9. Keong CY, B V, Daker M, Hamzah MY, Mohamad SA, Lan J, et al.
    Int J Med Mushrooms, 2016;18(2):141-54.
    PMID: 27279536 DOI: 10.1615/IntJMedMushrooms.v18.i2.50
    This study investigated antioxidant and anti-inflammatory properties, and the direct cytotoxic effect of Lignosus rhinocerotis fractions, especially the polysaccharide fraction, on nasopharyngeal carcinoma cells. L. rhinocerotis crude extract was obtained through hot water extraction. The precipitate saturated with 30% ammonium sulfate was purified with ion-exchanged chromatography. Gel permeation chromatography multiangle laser light scattering analysis equipped with light scattering and UV signals revealed two district groups of polymers. A total of four peaks were observed in the total carbohydrate test. Fraction C, which was the second region of the second peak eluted with 0.3 M NaOH, showed the highest integrated molecular weight, whereas fraction E had the lowest integrated molecular weight of 19,790 Da. Fraction A contained the highest β-D-glucan content. Enzymatic analysis showed that most of the polysaccharide fractions contained β-1-3 and β-1-6 skeletal backbones. The peak eluted with 0.6 M NaOH was separated in fraction D (flask 89-92) and fraction E (93-96). The results showed that fraction E expressed higher antioxidant activities than fraction D whereas fraction D expressed higher chelating activity than fraction E. The extract saturated with 30% ammonium sulfate exhibited higher reducing power than the extract saturated with 100% ammonium sulfate. Fractions D and E significantly inhibited the secretion of tumor necrosis factor-α in lipopolysaccharide-stimulated RAW 264.7 macrophages in a dose-dependent manner. There was no apparent difference in the viability of cells exposed or unexposed to L. rhinocerotis fractions.
  10. Klionsky DJ, Abdelmohsen K, Abe A, Abedin MJ, Abeliovich H, Acevedo Arozena A, et al.
    Autophagy, 2016;12(1):1-222.
    PMID: 26799652 DOI: 10.1080/15548627.2015.1100356
  11. Hu J, Yew CT, Chen X, Feng S, Yang Q, Wang S, et al.
    Talanta, 2017 Apr 01;165:419-428.
    PMID: 28153277 DOI: 10.1016/j.talanta.2016.12.086
    The identification and quantification of chemicals play a vital role in evaluation and surveillance of environmental health and safety. However, current techniques usually depend on costly equipment, professional staff, and/or essential infrastructure, limiting their accessibility. In this work, we develop paper-based capacitive sensors (PCSs) that allow simple, rapid identification and quantification of various chemicals from microliter size samples with the aid of a handheld multimeter. PCSs are low-cost parallel-plate capacitors (~$0.01 per sensor) assembled from layers of aluminum foil and filter paper via double-sided tape. The developed PCSs can identify different kinds of fluids (e.g., organic chemicals) and quantify diverse concentrations of substances (e.g., heavy metal ions) based on differences in dielectric properties, including capacitance, frequency spectrum, and dielectric loss tangent. The PCS-based method enables chemical identification and quantification to take place much cheaply, simply, and quickly at the point-of-care (POC), holding great promise for environmental monitoring in resource-limited settings.
  12. Cale EM, Gorman J, Radakovich NA, Crooks ET, Osawa K, Tong T, et al.
    Immunity, 2017 05 16;46(5):777-791.e10.
    PMID: 28514685 DOI: 10.1016/j.immuni.2017.04.011
    Most HIV-1-specific neutralizing antibodies isolated to date exhibit unusual characteristics that complicate their elicitation. Neutralizing antibodies that target the V1V2 apex of the HIV-1 envelope (Env) trimer feature unusually long protruding loops, which enable them to penetrate the HIV-1 glycan shield. As antibodies with loops of requisite length are created through uncommon recombination events, an alternative mode of apex binding has been sought. Here, we isolated a lineage of Env apex-directed neutralizing antibodies, N90-VRC38.01-11, by using virus-like particles and conformationally stabilized Env trimers as B cell probes. A crystal structure of N90-VRC38.01 with a scaffolded V1V2 revealed a binding mode involving side-chain-to-side-chain interactions that reduced the distance the antibody loop must traverse the glycan shield, thereby facilitating V1V2 binding via a non-protruding loop. The N90-VRC38 lineage thus identifies a solution for V1V2-apex binding that provides a more conventional B cell pathway for vaccine design.
  13. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys Rev Lett, 2017 Sep 15;119(11):111802.
    PMID: 28949210 DOI: 10.1103/PhysRevLett.119.111802
    A search is reported for a narrow vector resonance decaying to quark-antiquark pairs in proton-proton collisions at sqrt[s]=13  TeV, collected with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.7   fb^{-1}. The vector resonance is produced at large transverse momenta, with its decay products merged into a single jet. The resulting signature is a peak over background in the distribution of the invariant mass of the jet. The results are interpreted in the framework of a leptophobic vector resonance and no evidence is found for such particles in the mass range of 100-300 GeV. Upper limits at 95% confidence level on the production cross section are presented in a region of mass-coupling phase space previously unexplored at the LHC. The region below 140 GeV has not been explored by any previous experiments.
  14. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Phys Rev Lett, 2017 Oct 06;119(14):141802.
    PMID: 29053305 DOI: 10.1103/PhysRevLett.119.141802
    A search for charged Higgs bosons produced via vector boson fusion and decaying into W and Z bosons using proton-proton collisions at sqrt[s]=13  TeV is presented. The data sample corresponds to an integrated luminosity of 15.2  fb^{-1} collected with the CMS detector in 2015 and 2016. The event selection requires three leptons (electrons or muons), two jets with large pseudorapidity separation and high dijet mass, and missing transverse momentum. The observation agrees with the standard model prediction. Limits on the vector boson fusion production cross section times branching fraction for new charged physical states are reported as a function of mass from 200 to 2000 GeV and interpreted in the context of Higgs triplet models.
  15. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys Rev Lett, 2017 Oct 13;119(15):151802.
    PMID: 29077436 DOI: 10.1103/PhysRevLett.119.151802
    Results are reported from a search for supersymmetric particles in proton-proton collisions in the final state with a single lepton, multiple jets, including at least one b-tagged jet, and large missing transverse momentum. The search uses a sample of proton-proton collision data at sqrt[s]=13  TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9  fb^{-1}. The observed event yields in the signal regions are consistent with those expected from standard model backgrounds. The results are interpreted in the context of simplified models of supersymmetry involving gluino pair production, with gluino decay into either on- or off-mass-shell top squarks. Assuming that the top squarks decay into a top quark plus a stable, weakly interacting neutralino, scenarios with gluino masses up to about 1.9 TeV are excluded at 95% confidence level for neutralino masses up to about 1 TeV.
  16. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Phys Rev Lett, 2017 Oct 13;119(15):152301.
    PMID: 29077459 DOI: 10.1103/PhysRevLett.119.152301
    The differential production cross sections of B^{±} mesons are measured via the exclusive decay channels B^{±}→J/ψK^{±}→μ^{+}μ^{-}K^{±} as a function of transverse momentum in pp and Pb-Pb collisions at a center-of-mass energy sqrt[s_{NN}]=5.02  TeV per nucleon pair with the CMS detector at the LHC. The pp(Pb-Pb) data set used for this analysis corresponds to an integrated luminosity of 28.0  pb^{-1} (351  μb^{-1}). The measurement is performed in the B^{±} meson transverse momentum range of 7 to 50  GeV/c, in the rapidity interval |y|<2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of 2 is observed in the Pb-Pb system in comparison to the expectation from pp reference data. These results are found to be roughly compatible with theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.
  17. Feng X, Guo N, Chen H, Wang H, Yue L, Chen X, et al.
    Dalton Trans, 2017 Oct 24;46(41):14192-14200.
    PMID: 28990615 DOI: 10.1039/c7dt02974h
    A series of coordination polymers {[Ln(aobtc)(H2O)4]·Hbipy·H2O}n (H4aobtc = azoxybenzene-2,2',3,3'-tetracarboxylic acid, bipy = 4,4'-bipyridine, and Ln = Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Er(6)) have been synthesized and characterized systematically. The cationic Hbipy(+) guest incorporated polymers are isostructural sets, featuring a one-dimensional (1D) zigzag double chain edifice composed of binuclear clusters [Ln2(H4aobtc)2], with the Hbipy(+) guest being located on two sides. These 1D chains are further interlinked into a 2D layer structure, and further extended into a 3D framework through hydrogen bonding interactions. The luminescence emission spectra of polymers 2 and 3 are based on the H4aobtc acid ligands, while 1 and 4 display the characteristic f-f transitions of Ln(iii) ions. Magnetic measurements revealed the presence of ferromagnetic behavior in polymer 3. The magnetic behaviors of 4 and 6 are ascribed to the depopulation of the Stark levels and/or weak antiferromagnetic interactions within MOFs at lower temperature. Slow relaxation is observed through the alternating-current susceptibility measurements for 5 at lower temperature, and the coexistence of weak ferromagnetism corresponding to the spin-canting-like behavior.
  18. Michailidou K, Lindström S, Dennis J, Beesley J, Hui S, Kar S, et al.
    Nature, 2017 Nov 02;551(7678):92-94.
    PMID: 29059683 DOI: 10.1038/nature24284
    Breast cancer risk is influenced by rare coding variants in susceptibility genes, such as BRCA1, and many common, mostly non-coding variants. However, much of the genetic contribution to breast cancer risk remains unknown. Here we report the results of a genome-wide association study of breast cancer in 122,977 cases and 105,974 controls of European ancestry and 14,068 cases and 13,104 controls of East Asian ancestry. We identified 65 new loci that are associated with overall breast cancer risk at P 
  19. Milne RL, Kuchenbaecker KB, Michailidou K, Beesley J, Kar S, Lindström S, et al.
    Nat Genet, 2017 Dec;49(12):1767-1778.
    PMID: 29058716 DOI: 10.1038/ng.3785
    Most common breast cancer susceptibility variants have been identified through genome-wide association studies (GWAS) of predominantly estrogen receptor (ER)-positive disease. We conducted a GWAS using 21,468 ER-negative cases and 100,594 controls combined with 18,908 BRCA1 mutation carriers (9,414 with breast cancer), all of European origin. We identified independent associations at P < 5 × 10-8 with ten variants at nine new loci. At P < 0.05, we replicated associations with 10 of 11 variants previously reported in ER-negative disease or BRCA1 mutation carrier GWAS and observed consistent associations with ER-negative disease for 105 susceptibility variants identified by other studies. These 125 variants explain approximately 16% of the familial risk of this breast cancer subtype. There was high genetic correlation (0.72) between risk of ER-negative breast cancer and breast cancer risk for BRCA1 mutation carriers. These findings may lead to improved risk prediction and inform further fine-mapping and functional work to better understand the biological basis of ER-negative breast cancer.
  20. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Phys Rev Lett, 2017 Dec 01;119(22):221802.
    PMID: 29286783 DOI: 10.1103/PhysRevLett.119.221802
    A search for a signal consistent with the type-III seesaw mechanism in events with three or more electrons or muons is presented. The data sample consists of proton-proton collisions at sqrt[s]=13  TeV collected by the CMS experiment at the LHC in 2016 and corresponds to an integrated luminosity of 35.9  fb^{-1}. Selection criteria based on the number of leptons and the invariant mass of oppositely charged lepton pairs are used to distinguish the signal from the standard model background. The observations are consistent with the expectations from standard model processes. The results are used to place limits on the production of heavy fermions of the type-III seesaw model as a function of the branching ratio to each lepton flavor. In the scenario of equal branching fractions to each lepton flavor, heavy fermions with masses below 840 GeV are excluded. This is the most sensitive probe to date of the type-III seesaw mechanism.
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