Publications by authors named "Jiyong Yang"

47 Publications

Genetic characterization of Carbapenem-Resistant Escherichia coli from China, 2015-2017.

BMC Microbiol 2021 09 17;21(1):248. Epub 2021 Sep 17.

Laboratory Medicine Department, First Medical Center of Chinese PLA General Hospital, Beijing, 100853, China.

Background: The molecular characteristics of carbapenem-resistant Escherichia coli (CREco) remain unclear.

Methods: We conducted a multi-center bacterial resistance monitoring project from 2015 to 2017.The minimum inhibitory concentrations ofCREco were determined bybroth microdilution method. The genome sequencing of CREcoisolates was performed, and single-nucleotide polymorphism (SNP) was analyzed.

Results: A total of 144CREcoisolatescollected from 10 cities in China were involved in this study. ST167 (n = 43) is the most popular type, followed by ST410(n = 14), ST131(n = 9). There were 102 (70.83%) CREco isolates that produced various NDMs, including NDM-1 (n = 16), NDM-4(n = 1), NDM-5(n = 79), NDM-6(n = 2) and NDM-9(n = 4). In addition, 15 isolates produced KPC-2, three isolates wereIMP-4 positive, and three isolates produced OXA-48. Genetic relatedness and phylogenetic analysis showed that isolates with the same ST had a high degree of homology. Some STs (including ST167, ST410, ST131, ST46, ST405 and ST617) exhibited a trend of outbreak.

Conclusions: The majority of CREco belonged to ST167, followed by ST410 and ST131, and most of them carried various NDM-coding genes. The spread of high-risk clones of CREco has occurred in different regions of China.
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http://dx.doi.org/10.1186/s12866-021-02307-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8449468PMC
September 2021

Genetic characteristics of OXA-48-producing Enterobacterales from China.

J Glob Antimicrob Resist 2021 Sep 18;26:285-291. Epub 2021 Jul 18.

Department of Laboratory Medicine, First Medical Center of Chinese PLA General Hospital, Beijing 100853, China. Electronic address:

Objectives: In China, OXA-48-producing Enterobacterales have been identified sporadically, causing small-scale regional outbreaks. This study investigated the molecular epidemiology, transmission and evolution of OXA-48-producing Enterobacterales and pOXA48 from mainland China.

Methods: We conducted a multicentre resistance monitoring project from 2013-2018. Genome sequencing of OXA-48-produicng isolates was performed. SNPs were analysed. Eleven isolates were selected for subsequent SMRT sequencing. Genome sequences were annotated, and alignment of the complete sequences of bla-carrying plasmids from a subset of isolates that underwent long-read sequencing was performed.

Results: In total, 41 OXA-48-producing Enterobacterales were included in this study (34 Klebsiella pneumoniae, 3 Escherichia coli, 3 Enterobacter cloacae complex and 1 Klebsiella oxytoca). OXA-48-produicng K. pneumoniae (OXAKp) ST383, ST147 and ST11 caused outbreaks of different scales in our hospital. OXA-48-producing E. coli ST156 and ST648, E. cloacae complex ST414 and ST418, and K. oxytoca ST34 were also identified. bla was embedded in a Tn1999.2 structure located in IncL plasmids with different sizes (63.58-109.14 kb). Importantly, K. pneumoniae ST11 co-producing KPC-2 and OXA-48 was identified in our hospital and it is possible that KPC-2-producing K. pneumoniae ST11 obtained the bla-carrying plasmid during its spread. A novel 109-kb bla-carrying IncL plasmid was identified from OXAKp ST11. Possibly, two plasmids in OXAKp ST383 were integrated to form this larger plasmid.

Conclusion: OXA-48-produicng Enterobacterales were sporadic in China. Importantly, K. pneumoniae ST11 co-producing KPC-2 and OXA-48 has emerged causing an outbreak in China. This high-risk multidrug-resistant clone exhibited high compatibility and strong integration ability with foreign resistance plasmids.
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http://dx.doi.org/10.1016/j.jgar.2021.07.006DOI Listing
September 2021

Strain-Relief Patterns and Kagome Lattice in Self-Assembled C Thin Films Grown on Cd(0001).

Int J Mol Sci 2021 Jun 26;22(13). Epub 2021 Jun 26.

School of Physical Science and Technology, Southwest University, Chongqing 400715, China.

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C monolayer grown on Cd(0001). Individual C molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C thin films present a curved structure to release strain due to dominant molecule-substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C films.
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http://dx.doi.org/10.3390/ijms22136880DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8268109PMC
June 2021

Orientation Ordering and Chiral Superstructures in Fullerene Monolayer on Cd (0001).

Nanomaterials (Basel) 2020 Jul 3;10(7). Epub 2020 Jul 3.

School of Physical Science and Technology, Southwest University, Chongqing 400715, China.

The structure of C thin films grown on Cd (0001) surface has been investigated from submonolayer to second monolayer regimes with a low-temperature scanning tunneling microscopy (STM). There are different C domains with various misorientation angles relative to the lattice directions of Cd (0001). In the (2√3 × 2√3) R30° domain, orientational disorder of the individual C molecules with either pentagon, hexagon, or 6:6 bond facing up has been observed. However, orientation ordering appeared in the R26° domain such that all the C molecules adopt the same orientation with the 6:6 bond facing up. In particular, complex chiral motifs composed of seven C molecules with clockwise or anticlockwise handedness have been observed in the R4° and R8° domains, respectively. Scanning tunneling spectroscopy (STS) measurements reveal a reduced HOMO-LOMO gap of 2.1 eV for the C molecules adsorbed on Cd (0001) due to the substrate screening and charge transfer from Cd to C molecules.
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http://dx.doi.org/10.3390/nano10071305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407170PMC
July 2020

Characterization of a multidrug-resistant Klebsiella pneumoniae ST3330 clone responsible for a nosocomial outbreak in a neonatal intensive care unit.

Ann Palliat Med 2020 May 14;9(3):1092-1102. Epub 2020 May 14.

Medical School of Chinese PLA & Department of Clinical Laboratory, Medical Laboratory Center, Chinese PLA General Hospital, Beijing 100853, China.

Background: The incidence of Klebsiella pneumonia (Kp), which has often been found to produce, extended spectrum beta-lactamase (ESBL), is rising rapidly and poses a serious risk to neonates. To date, the mechanisms related to the spread of ESBL-Kp have not been fully elucidated. This study aimed to investigate the phenotypes, genotypes, and genetic relatedness of ESBL-KP that caused an outbreak of sepsis among neonates in an intensive care unit of a Beijing hospital.

Methods: Between April 2016 and May 2018, 21 non-repetitive clinical ESBL-Kp isolates were collected from a neonatal intensive care unit (NICU) in Beijing, China and were retrospectively analyzed. Pulsed-field gel electrophoresis (PFGE) was used to analyze genetic relatedness, a VITEK 2 AST test kit was used to test antimicrobial susceptibility, sequence type (ST) was analyzed through multilocus sequence typing (MLST), and resistance genes were identified by PCR. Virulence gene profiles, biofilm formation assay, and serum killing assay were used for virulence-associated determinants.

Results: All strains expressed the same antibiotype, combining ESBL production, third generation cephalosporins resistance and carbapenems sensitive. Sixteen of them produced β-lactamases (CTX-M-3 and TEM-1B), while others possessed CTX-M-15, CTX-M-24, CTX-M-66, TEM-1C, SHV-26, SHV172, and OXA-1. PFGE confirmed 5 types (A, B, C, D and E) and MLST identified a ST3330 clone (16 strains), a ST2791 clone (2 strains), a ST37 clone (1 strain), a ST34 clone (1 strain), and a ST2740 clone (1 strain). PFGE type A strains, which belong to ST3330, were identified as the main pathogens involved in the outbreak. All isolates contained virulence genes iutA and mrk. PFGE type A carried both mrk (type 3 fimbriae, biofilm formation) and fimH (type 1 fimbriae), and other STs possessed mrk. Isolates belonging to the endemic ST3330 lineage produced more biofilm than other ST isolates (median OD590 1.829 vs. 0.2280, respectively; P<0.0001). All five PFGE types isolates showed serum high sensitivity (grade 1).

Conclusions: The dissemination and outbreak of ESBL-producing K. pneumoniae in this study seemed to be clonal, and the outbreak was mainly caused by ST3330 K. pneumoniae. The detection of genes (mrk and fimH) belonging to the biofilm formation may partly explain the epidemic strain has high colonization and diffusion potential.
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http://dx.doi.org/10.21037/apm-20-958DOI Listing
May 2020

Nosocomial spread of OXA-232-producing Klebsiella pneumoniae ST15 in a teaching hospital, Shanghai, China.

BMC Microbiol 2019 10 28;19(1):235. Epub 2019 Oct 28.

Center for Clinical Laboratory, the 302 Hospital of Chinese PLA, Beijing, 100039, China.

Background: The spread and outbreak of Enterobacteriaceae producing OXA-48-like carbapenemases have become more and more prevalent in China.

Results: A total of 62 non-duplicated OXA-232-producing K. pneumoniae (OXA232Kp) were isolated between 2015 and 2017. An outbreak of OXA232Kp was observed in burn ICU. The 62 OXA232Kp isolates were all belongs to ST15 and categorized into two PFGE types (A and B). Type A was dominated of the isolates, which contained 61 clinical isolates and divided into 10 subtypes (A1-A10). In addition, most of OXA232Kp strains exhibited low-level carbapenems resistance. All strains carried a 6141 bp ColKP3 plasmid harboring the bla gene which is highly homologous to other bla-bearing plasmids involved in other studies in eastern China.

Conclusions: In this study, clone transmission of OXA232Kp ST15was observed. Highly significant homology among the bla-bearing plasmids indicated the important role of the 6.1 kb ColE-like plasmid on the prevalence of bla gene in China.
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http://dx.doi.org/10.1186/s12866-019-1609-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819465PMC
October 2019

Long noncoding RNA DLX6-AS1 promotes tumorigenesis by modulating miR-497-5p/FZD4/FZD6/Wnt/β-catenin pathway in pancreatic cancer.

Cancer Manag Res 2019 7;11:4209-4221. Epub 2019 May 7.

Department of General Surgery, Longhua Hospital Shanghai University of Traditional Chinese Medicine, Shanghai 210000, China,

Background: Long noncoding RNAs (lncRNAs) are abnormally expressed in various human tumors and play an important role in multiple tumorigeneses, including pancreatic cancer (PC).

Materials And Methods: The present study was designed to evaluate the role of lncRNA DLX6-AS1 in tumorigenesis of PC. The expression of DLX6-AS1 and its effect on proliferation, apoptosis, migration, and invasion was investigated in vitro. Its effect on tumor growth and metastasis in vivo and its potential targets were also examined.

Results: We observed that DLX6-AS1 was highly expressed in PC tissues and PC cell lines, and was negatively correlated with the survival of PC patients. We found that overexpression of DLX6-AS1 promoted proliferation, migration, and invasion of PC cells, inhibited apoptosis, increased Bcl-2, cyclin D1, and MMP-2 expression, and decreased cleaved caspase 3, p27, and E-cadherin expression in PC cells. In addition, overexpression of DLX6-AS1 promoted PC growth by increasing tumor volume and weight and increasing the number of liver and lung metastatic foci. Knockdown of DLX6-AS1 showed an opposite effect in all the experiments. miR-497-5p was demonstrated to be a direct target of DLX6-AS1 and was regulated by DLX6-AS1. We also demonstrated that miR-497-5p targeted FZD4 and FZD6 and decreased their expression. miR-497-5p mimics also decreased the expression of FZD4, FZD6, and β-catenin; the expression of FZD4 or FZD6 was reversed by the overexpression of vectors FZD4 or FZD6, respectively, while the expression of β-catenin was reversed by either vector. Finally, the effect of DLX6-AS1 on proliferation, cell cycle, migration, invasion, and apoptosis of cells and expression of FZD4, FZD6, and β-catenin was neutralized by overexpression of vectors of miR-497-5p, FZD4, or FZD6, totally or partially.

Conclusion: Collectively, these findings suggested that DLX6-AS1/miR-497-5p/FZD4/FZD6/Wnt/β-catenin signaling pathway is involved in the pathogenesis of PC, and DLX6-AS1 could be a potential biomarker and target for PC treatment.
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http://dx.doi.org/10.2147/CMAR.S194453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510228PMC
May 2019

A Case of Biliary Tract Infection Caused by KPC-2-Producing .

Case Rep Infect Dis 2018 11;2018:5745708. Epub 2018 Apr 11.

Department of Microbiology, Chinese PLA General Hospital, Beijing, China.

spp. can cause various infections. However, carbapenemase-producing spp. has not been previously reported. We report a case of biliary tract infection caused by KPC-2-producing in a 13-year-old female. To the best of our knowledge, this is the first report on infection caused by carbapenemase-producing spp.
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http://dx.doi.org/10.1155/2018/5745708DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5925141PMC
April 2018

Emergence of multiple carbapenemase-producing organisms in single patients: an increasing threat to treatment of infection.

J Antimicrob Chemother 2018 02;73(2):544-546

Department of Microbiology, Chinese PLA General Hospital, Beijing, China.

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http://dx.doi.org/10.1093/jac/dkx411DOI Listing
February 2018

Microbiological characterisation of Klebsiella pneumoniae isolates causing bloodstream infections from five tertiary hospitals in Beijing, China.

J Glob Antimicrob Resist 2018 03 12;12:162-166. Epub 2017 Oct 12.

Department of Microbiology, Chinese PLA General Hospital (301 Hospital), 28# Fuxing Road, Beijing 100853, China. Electronic address:

Objectives: Klebsiella pneumoniae is prevalent in China. Little is known about the microbiological characteristics of clinical K. pneumoniae isolates causing bloodstream infections (BSIs).

Methods: BSI-causing K. pneumoniae (BSI-Kpn) were collected from five tertiary-care hospitals in Beijing. Genetic relatedness was analysed by PFGE, antimicrobial susceptibility was determined by agar dilution, and sequence types (STs) were evaluated by MLST. Hypermucoviscosity (HV) phenotype was identified by positive string test. Carbapenemase, capsular serotype and HV-associated genes were detected by PCR.

Results: A total of 219 non-duplicate BSI-Kpn were collected from December 2013 to December 2014 and were categorised into 203 types (strains) with unique PFGE patterns. Among 203 BSI-Kpn, 105 STs were identified. Overall, ST11 and ST23 were the predominant clones (14 strains each; 6.9%), followed by ST412 (n=13), ST37 (n=9), ST65 (n=7), ST15 (n=6), ST86 (n=6), ST592 (n=5) and ST29 (n=4). There were 74 STs containing only a single strain. Approximately 8.4% (17/203) of the strains exhibited carbapenem resistance, most producing KPC carbapenemase. The majority (75.9%; 154/203) of isolates were associated with non-K1/K2/K5/K20/K54/K57 serotypes. Only 16.3% (33/203) of the strains had K1/K2 serotypes. A total of 66 (32.5%) of the BSI-Kpn strains exhibited a HV phenotype. rmpA was a predominant factor in determining a HV phenotype.

Conclusions: The majority of BSI-Kpn strains exhibited high genetic diversity and low resistance to commonly used antimicrobials. The specific capsular serotype and HV phenotype were not major features of BSI-Kpn strains in China.
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http://dx.doi.org/10.1016/j.jgar.2017.10.002DOI Listing
March 2018

Extremely Large Magnetoresistance in a Topological Semimetal Candidate Pyrite PtBi_{2}.

Phys Rev Lett 2017 Jun 23;118(25):256601. Epub 2017 Jun 23.

Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China.

While pyrite-type PtBi_{2} with a face-centered cubic structure has been predicted to be a three-dimensional (3D) Dirac semimetal, experimental study of its physical properties remains absent. Here we report the angular-dependent magnetoresistance measurements of a PtBi_{2} single crystal under high magnetic fields. We observed extremely large unsaturated magnetoresistance (XMR) up to (11.2×10^{6})% at T=1.8  K in a magnetic field of 33 T, which is comparable to the previously reported Dirac materials, such as WTe_{2}, LaSb, and NbP. The crystals exhibit an ultrahigh mobility and significant Shubnikov-de Hass quantum oscillations with a nontrivial Berry phase. The analysis of Hall resistivity indicates that the XMR can be ascribed to the nearly compensated electron and hole. Our experimental results associated with the ab initio calculations suggest that pyrite PtBi_{2} is a topological semimetal candidate that might provide a platform for exploring topological materials with XMR in noble metal alloys.
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http://dx.doi.org/10.1103/PhysRevLett.118.256601DOI Listing
June 2017

Molecular characterization of clinical IMP-producing Klebsiella pneumoniae isolates from a Chinese Tertiary Hospital.

Ann Clin Microbiol Antimicrob 2017 Jun 19;16(1):42. Epub 2017 Jun 19.

Department of Microbiology, Chinese PLA General Hospital, 301 Hospital, 28# Fuxing Road, Beijing, 100853, China.

Background: IMP-producing Klebsiella pneumoniae (IMPKpn) exhibits sporadic prevalence in China. The mechanisms related to the spread of IMPKpn remain unclear.

Methods: Carbapenem non-susceptible K. pneumoniae isolates were collected from our hospital. The genetic relatedness, antimicrobial susceptibility, as well as sequence types (ST) were analyzed by pulsed-field gel electrophoresis (PFGE), VITEK 2 AST test Kit, and multilocus sequence typing (MLST), respectively. S1-PFGE, Southern blot analysis and multiple PCR amplification were used for plasmid profiling.

Results: Between October 2009 and June 2016, 25 non-repetitive IMPKpn isolates were identified. PFGE results showed that these isolates belonged to 20 genetically unrelated IMPKpn strains. Diverse STs were identified by MLST. Most strains carried bla , followed by bla . Four incompatibility types of bla -carrying plasmids were identified, which included A/C (n = 2), B/O (n = 2), L/M (n = 1) and N (n = 14), while type of other one plasmid failed to be determined.

Conclusions: The IMPKpn isolates exhibited sporadic prevalence in our hospital. IncN types of plasmids with various sizes have emerged as the main platform mediating the spread of the bla genes in our hospital.
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http://dx.doi.org/10.1186/s12941-017-0218-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474851PMC
June 2017

NDM-producing Enterobacteriaceae in a Chinese hospital, 2014-2015: identification of NDM-producing Citrobacterwerkmanii and acquisition of blaNDM-1-carrying plasmid in vivo in a clinical Escherichia coli isolate.

J Med Microbiol 2016 Nov 23;65(11):1253-1259. Epub 2016 Sep 23.

Department of Microbiology, Chinese PLA General Hospital, Beijing, PR China.

New Delhi metallo-β-lactamase (NDM)-producing Enterobacteriaceae (NPE) shows prevalence in China. Little is known about the mechanisms related to the spread of NPE. Recently, a total of 51 non-duplicated NPE isolates were collected from a tertiary-care hospital in China and analysed for genetic relatedness by PFGE, antimicrobial susceptibility by Etest and sequence type by multilocus sequence typing. S1-PFGE and Southern blot analysis or PCR amplification were used for plasmid profiling. Between 2014 and 2015, 22 Escherichia coli, 10 Klebsiella pneumoniae, 9 Enterobacter cloacae, 2 Enterobacter aerogenes, 3 Providencia rettgeri, 1 Klebsiella oxytoca, 1 Proteus mirabilis, 1 Citrobacter freundii, 1 Citrobacterwerkmanii and 1 Raoultella planticola were identified as NPE. Results of PFGE and multilocus sequence typing showed that most strains were genetically unrelated. Among the 45 blaNDM-carrying plasmids, there were 25 IncX3 plasmids with a size of about 30 to 50 kb, one 100 kb IncX3 plasmid, 11 IncA/C plasmids with a size range from 70 to 300 kb, six 90 to 120 kb IncB/O plasmids, one IncN plasmid with a size of 100 kb and one 140 kb IncFrep plasmid. An NDM-1-producing isolate of C. werkmanii was identified, which had not been reported previously. An Escherichia coli strain was found acquiring a blaNDM-1-carrying IncFrep plasmid in vivo during infection. In conclusion, an NDM-1-producing isolate of C. werkmanii was identified. An Escherichia coli strain acquired a blaNDM-1-carrying plasmid in vivo. IncX3 and IncA/C plasmids with various sizes might have emerged as the main platforms mediating the spread of the blaNDM genes in China.
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http://dx.doi.org/10.1099/jmm.0.000357DOI Listing
November 2016

Nosocomial Outbreak of OXA-48-Producing Klebsiella pneumoniae in a Chinese Hospital: Clonal Transmission of ST147 and ST383.

PLoS One 2016 4;11(8):e0160754. Epub 2016 Aug 4.

Department of Microbiology, Chinese PLA General Hospital, Beijing, China.

Background: In China, the spread and outbreak of OXA-48-producing Enterobacteriaceae remains largely unknown.

Methods: OXA-48-producing isolates were analyzed for genetic relatedness by pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility by E-test, and sequence type (ST) by multilocus sequence typing. S1-PFGE and southern blotting were used for plasmid profiling, and PCR and subsequent sequencing were performed to determine the genetic environment of blaOXA-48 gene.

Results: In total, 37 non-duplicated OXA-48-producing K. pneumoniae (OXAKp) isolates were recovered. From December 2013 to August 2014, an outbreak was observed at a respiratory ICU. The 37 isolates of K. pneumoniae were categorized into four PFGE types (A, B, C, and D). The predominant strains associated with the outbreak were strains with PFGE type A and B, which belonged to ST383 and ST147, respectively. Plasmid sequencing revealed that the blaOXA-48-carrying plasmid is 69,069 bp in length and belongs to the IncL/M incompatibility group. Sequence analysis revealed that the IS1999 element was located upstream of the blaOXA-48 gene and was truncated by IS1R.

Conclusions: In this study, the dissemination and outbreak of OXAKp isolates were clonal, and ST147 and ST383 K. pneumoniae were the predominant clones that were associated with the outbreak. Meanwhile, the horizontal transfer of plasmids potentially mediate the spread of blaOXA-48 gene between different K. pneumoniae strains.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0160754PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973971PMC
August 2017

Identification of ssDNA aptamers specific to clinical isolates of Streptococcus mutans strains with different cariogenicity.

Acta Biochim Biophys Sin (Shanghai) 2016 Jun 4;48(6):563-72. Epub 2016 May 4.

Department of Stomatology, Chinese PLA General Hospital, Beijing 100853, China

Streptococcus mutans, a Gram-positive facultative anaerobic bacterium, is considered to be a major etiological factor for dental caries. In this study, plaques from dental enamel surfaces of caries-active and caries-free individuals were obtained and cultivated for S. mutans isolation. Morphology examination, biochemical characterization, and polymerase chain reaction were performed to identify S. mutans The cariogenicity of S. mutans strains isolated from clinical specimens was evaluated by testing the acidogenicity, aciduricity, extracellular polysaccharide production, and adhesion ability of the bacteria. Finally, subtractive SELEX (systematic evolution of ligands by exponential enrichment) technology targeting whole intact cells was used to screen for ssDNA aptamers specific to the strains with high cariogenicity. After nine rounds of subtractive SELEX, sufficient pool enrichment was achieved as shown by radioactive isotope analysis. The enriched pool was cloned and sequenced randomly, followed by MEME online and RNA structure software analysis of the sequences. Results from the flow cytometry indicated that aptamers H1, H16, H4, L1, L10, and H19 could discriminate highly cariogenic S. mutans strains from poorly cariogenic strains. Among these, Aptamer H19 had the strongest binding capacity with cariogenic S. mutans strains with a dissociation constant of 69.45 ± 38.53 nM. In conclusion, ssDNA aptamers specific to highly cariogenic clinical S. mutans strains were successfully obtained. These ssDNA aptamers might be used for the early diagnosis and treatment of dental caries.
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http://dx.doi.org/10.1093/abbs/gmw034DOI Listing
June 2016

Weak localization effect in topological insulator micro flakes grown on insulating ferrimagnet BaFe₁₂O₁₉.

Sci Rep 2016 Feb 19;6:21334. Epub 2016 Feb 19.

High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.

Many exotic physics anticipated in topological insulators require a gap to be opened for their topological surface states by breaking time reversal symmetry. The gap opening has been achieved by doping magnetic impurities, which however inevitably create extra carriers and disorder that undermine the electronic transport. In contrast, the proximity to a ferromagnetic/ferrimagnetic insulator may improve the device quality, thus promises a better way to open the gap while minimizing the side-effects. Here, we grow thin single-crystal Sb1.9Bi0.1Te3 micro flakes on insulating ferrimagnet BaFe12O19 by using the van der Waals epitaxy technique. The micro flakes show a negative magnetoresistance in weak perpendicular fields below 50 K, which can be quenched by increasing temperature. The signature implies the weak localization effect as its origin, which is absent in intrinsic topological insulators, unless a surface state gap is opened. The surface state gap is estimated to be 10 meV by using the theory of the gap-induced weak localization effect. These results indicate that the magnetic proximity effect may open the gap for the topological surface attached to BaM insulating ferrimagnet. This heterostructure may pave the way for the realization of new physical effects as well as the potential applications of spintronics devices.
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http://dx.doi.org/10.1038/srep21334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4759543PMC
February 2016

Variation of Circulating Inflammatory Mediators in Staphylococcus aureus and Escherichia coli Bloodstream Infection.

Med Sci Monit 2016 Jan 16;22:161-71. Epub 2016 Jan 16.

Department of Clinical Laboratory Medicine, Chinese PLA General Hospital, Beijing, China (mainland).

Background: The aim of this study was to examine the behavior of circulating inflammatory mediators and to exclude gram-positive from gram-negative bloodstream infections. Results may be helpful in selection of optimal specific antibiotic therapies.

Material/methods: Mice (25-27 g) were randomized to 3 groups infected with Staphylococcus aureus (S. aureus) ATCC 25923, Escherichia coli (E. coli) ATCC 25922, or phosphate-buffered saline (PBS). The white blood cell count (WBC) and the concentrations of serum C-reactive protein (CRP), procalcitonin (PCT), interleukin (IL)-1α, IL-1β, IL-6, IL-10, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1α (MIP-1α) were detected in blood samples at different time intervals after intravenous tail injection.

Results: The results showed that compared to the control mice, infected animals exhibited significantly higher levels of all mediators after bacterial infection. Moreover, compared to the mice that received S. aureus, animals with E. coli infection showed significantly greater increases in serum IL-1α, IL-1β, IL-6, MCP-1, and MIP-1α levels.

Conclusions: These results suggest that the use of the analyzed serum markers at an early stage of bloodstream infection may give useful information for the clinician to distinguish gram-negative from gram-positive infections.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720174PMC
http://dx.doi.org/10.12659/msm.896576DOI Listing
January 2016

Prevalence of Diverse Clones of Vancomycin-Resistant Enterococcus faecium ST78 in a Chinese Hospital.

Microb Drug Resist 2016 Jun 10;22(4):294-300. Epub 2015 Dec 10.

1 Department of Microbiology, Chinese PLA General Hospital , Beijing, China .

Background: Vancomycin-resistant Enterococcus (VRE) has been identified in China. However, little is known about the spread of VRE isolates.

Methods: The genetic relatedness of vancomycin-resistant Enterococcus faecium (VREfm) isolates was analyzed by pulsed-field gel electrophoresis (PFGE), their antimicrobial susceptibilities were analyzed by E-test and the VITEK 2 AST-GP67 test Kit, and their sequence types (STs) were investigated by multilocus sequence typing (MLST). S1-PFGE was used for plasmid profiling, and PCR and subsequent sequencing were performed to identify the virulence genes.

Results: A total of 96 nonduplicated VREfm isolates were obtained and categorized into 38 PFGE types (type 1-38). The predominant MLST type was ST78, while ST17, ST341, and ST342 were also sporadically identified. All types of clinical VREfm strains harbored the vanA gene; however, they carried plasmids of different sizes. While 92.1%, 71.1%, and 60.5% of VREfm strains carried hyl, scm, and ecbA genes, respectively, all of them were positive for esp, acm, sgrA, pilA, and pilB genes.

Conclusions: Clonal VREfm spread was observed, and nonplasmid-mediated horizontal transfer of vancomycin-resistant gene might have conveyed resistance to some vancomycin-susceptible E. faecium strains. E. faecium ST78 carrying vanA gene was the most prevalent clone in this study. The high prevalence of virulence genes, including esp, hyl, acm, scm, ecbA, sgrA, pilA, and pilB, confirmed their important roles in the emergence of VREfm ST78 in nosocomial infections.
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http://dx.doi.org/10.1089/mdr.2015.0069DOI Listing
June 2016

Edge-mediated skyrmion chain and its collective dynamics in a confined geometry.

Nat Commun 2015 Oct 8;6:8504. Epub 2015 Oct 8.

High Magnetic Field Laboratory, Chinese Academy of Science (CAS), Hefei 230031, China.

The emergence of a topologically nontrivial vortex-like magnetic structure, the magnetic skyrmion, has launched new concepts for memory devices. Extensive studies have theoretically demonstrated the ability to encode information bits by using a chain of skyrmions in one-dimensional nanostripes. Here, we report experimental observation of the skyrmion chain in FeGe nanostripes by using high-resolution Lorentz transmission electron microscopy. Under an applied magnetic field, we observe that the helical ground states with distorted edge spins evolve into individual skyrmions, which assemble in the form of a chain at low field and move collectively into the interior of the nanostripes at elevated fields. Such a skyrmion chain survives even when the width of the nanostripe is much larger than the size of single skyrmion. This discovery demonstrates a way of skyrmion formation through the edge effect, and might, in the long term, shed light on potential applications.
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http://dx.doi.org/10.1038/ncomms9504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4633724PMC
October 2015

Preparation, optical and electrical properties of PTCDA nanostructures.

Nanoscale 2015 Oct 30;7(40):17116-21. Epub 2015 Sep 30.

High Magnetic Field Laboratory, Chinese Academy of Science, Hefei 230031, Anhui, People's Republic of China.

Film, nanorods (NRs), nanowires (NWs), and nanoparticles (NPs) of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) were prepared by organic molecular beam deposition (OMBD) on porous anodic alumina oxide (AAO) at different substrate temperatures (Ts). Scanning electron microscopy (SEM) study showed that the morphologies of the nanostructures (NS) formed on AAO strongly depend on the Ts. The absorption spectra of different PTCDA NS present strong absorbance in the wavelength range of 400-600 nm, and the photoluminescence (PL) spectra show a blue shift as Ts increases. The current versus voltage (I-V) characteristic illustrates that the electrical conductivity of the single-crystal NW is about 3 ± 0.1 S m(-1), which is much higher than the conductivity of PTCDA film reported previously.
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http://dx.doi.org/10.1039/c5nr04738bDOI Listing
October 2015

Electrical probing of field-driven cascading quantized transitions of skyrmion cluster states in MnSi nanowires.

Nat Commun 2015 Jul 6;6:7637. Epub 2015 Jul 6.

High Magnetic Field Laboratory, Chinese Academy of Science (CAS), Hefei, Anhui Province 230031, China.

Magnetic skyrmions are topologically stable whirlpool-like spin textures that offer great promise as information carriers for future spintronic devices. To enable such applications, particular attention has been focused on the properties of skyrmions in highly confined geometries such as one-dimensional nanowires. Hitherto, it is still experimentally unclear what happens when the width of the nanowire is comparable to that of a single skyrmion. Here, we achieve this by measuring the magnetoresistance in ultra-narrow MnSi nanowires. We observe quantized jumps in magnetoresistance versus magnetic field curves. By tracking the size dependence of the jump number, we infer that skyrmions are assembled into cluster states with a tunable number of skyrmions, in agreement with the Monte Carlo simulations. Our results enable an electric reading of the number of skyrmions in the cluster states, thus laying a solid foundation to realize skyrmion-based memory devices.
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http://dx.doi.org/10.1038/ncomms8637DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4506500PMC
July 2015

Superconductor-insulator transition in quasi-one-dimensional single-crystal Nb₂PdS₅ nanowires.

Nano Lett 2015 Feb 16;15(2):869-75. Epub 2015 Jan 16.

High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei 230031 Anhui, People's Republic of China.

Superconductor-insulator transition (SIT) in one-dimensional (1D) nanowires attracts great attention in the past decade and remains an open question since contrasting results were reported in nanowires with different morphologies (i.e., granular, polycrystalline, or amorphous) or environments. Nb2PdS5 is a recently discovered low-dimensional superconductor with typical quasi-1D chain structure. By decreasing the wire diameter in the range of 100-300 nm, we observed a clear SIT with a 1D transport character driven by both the cross-sectional area and external magnetic field. We also found that the upper critical magnetic field (Hc2) decreases with the reduction of nanowire cross-sectional area. The temperature dependence of the resistance below Tc can be described by the thermally activated phase slip (TAPS) theory without any signature of quantum phase slips (QPS). These findings demonstrated that the enhanced Coulomb interactions with the shrinkage of the wire diameter competes with the interchain Josephson-like coupling may play a crucial role on the SIT in quasi-1D system.
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http://dx.doi.org/10.1021/nl503538sDOI Listing
February 2015

Characteristics of qacA/B-positive Staphylococcus aureus isolated from patients and a hospital environment in China.

J Antimicrob Chemother 2015 Mar 27;70(3):653-7. Epub 2014 Nov 27.

Center for Hospital Infection Control, Chinese PLA Institute for Disease Control & Prevention, Academy of Military Medical Sciences, Beijing, China

Objectives: This study was designed to demonstrate the characteristics of qacA/B-positive Staphylococcus aureus in China.

Methods: One hundred and forty-five MRSA and 178 MSSA from clinical specimens from seven hospitals in different regions of China, 70 MRSA from superficial sites of patients and 106 MRSA from environmental samples from an ICU were collected and screened for the presence of the qacA/B gene. The qacA/B-positive isolates and 72 randomly selected qacA/B-negative control isolates were further characterized by MLST, spa typing and detection of toxin genes, as well as antimicrobial and chlorhexidine susceptibility. SCCmec typing was conducted for MRSA. PFGE was conducted for qacA/B-positive isolates.

Results: Twenty-five (7.8%) of the 321 MRSA isolates harboured qacA/B, including 11 isolates from clinical specimens (7.6%), 12 isolates from patients' superficial sites (17.1%) and 2 isolates from an ICU environment (1.9%). Ten and five qacA/B-positive MRSA were identified as ST239-t030-MRSA-III and ST239-t037-MRSA-III, respectively. Six PFGE clusters and five singletons were identified among the 25 qacA/B-positive MRSA. Only one (0.6%) of the 178 MSSA isolates harboured qacA/B. qacA/B carriage in MRSA was statistically associated with spa-t037 and the presence of mupA. Compared with qacA/B-negative MRSA, the qacA/B-positive MRSA exhibited a lower susceptibility to chlorhexidine and higher resistance rates to clindamycin and trimethoprim/sulfamethoxazole.

Conclusions: Carriage of qacA/B, although it had a low prevalence, might be the main reason for declining susceptibility to chlorhexidine in MRSA from Chinese patients and is probably associated with spa-t037 and the presence of the mupA gene.
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http://dx.doi.org/10.1093/jac/dku456DOI Listing
March 2015

Performance of the VITEK MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for rapid bacterial identification in two diagnostic centres in China.

J Med Microbiol 2015 Jan 23;64(Pt 1):18-24. Epub 2014 Nov 23.

Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, PR China.

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS systems was not officially launched for diagnostic use in clinical microbiology laboratories in China until 2012. Here, we report the findings from the first large-scale evaluation study of VITEK MS for routine bacterial identification in two major diagnostic centres in Beijing and Hong Kong. A total of 2266 unique isolates representing 56 genera and 127 species were analysed, and results were compared to those obtained by VITEK 2. Any discrepancies were resolved by 16S rRNA sequencing. Overall, VITEK MS provided correct identification for 2246 (99.1%) isolates, including 2193 (96.8 %) with correct species-level identifications and 53 (2.3 %) matched at the genus level only. VITEK MS surpassed VITEK 2 consistently in species-level identification of important pathogens, including non-Enterobacteriaceae Gram-negative bacilli (94.7 versus 92 %), staphylococci (99.7 versus 92.4 %), streptococci (92.6 versus 79.4 %), enterococci (98.8 versus 92.6 %) and Clostridium spp. (97.3 versus 55.5 %). The findings demonstrated that VITEK MS is highly accurate and reliable for routine bacterial identification in clinical settings in China.
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http://dx.doi.org/10.1099/jmm.0.080317-0DOI Listing
January 2015

Robust surface state transport in thin bismuth nanoribbons.

Sci Rep 2014 Nov 18;4:7086. Epub 2014 Nov 18.

1] High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, P. R. China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.

While a two-dimensional (2D) metallic surface state in bismuth has been proposed, experimental 2D evidence of quantum transport, e.g., angular dependent Shubnikov-de Haas (SdH) oscillations is still lacking. Here, we report the angular-dependent magnetoresistance measurements in single-crystal Bi nanoribbons, and found that both the low-field weak antilocalization behavior and the high-field angle-dependent SdH oscillations follow exactly the 2D character, indicative of the 2D metallic surface states which dominate the transport properties of thin Bi nanoribbons. Moreover, by controllable exposing the ribbons to ambient environment (1 atm and room temperature), the metallic surface states were found to be robust to the oxidation although the carrier density in the surface states are modified after the exposures. These results suggest that the metallic surface states in Bi nanoribbons should be topologically protected which can provide key information in understanding the surface properties of Bi in nanometer scale.
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http://dx.doi.org/10.1038/srep07086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4235329PMC
November 2014

In vitro photodynamic inactivation effects of Ru(II) complexes on clinical methicillin-resistant Staphylococcus aureus planktonic and biofilm cultures.

Photochem Photobiol 2015 Jan-Feb;91(1):124-33. Epub 2014 Dec 5.

Department of Laser Medicine, Chinese PLA General Hospital, Beijing, China; College of Medicine, Nankai University, Tianjin, China.

Photosensitizers (PSs) combined with light are able to generate antimicrobial effects. Ru(II) complexes have been recognized as a novel class of PSs. In this study, we investigated the effectiveness of photodynamic inactivation (PDI) mediated by three Ru(II) polypyridine complexes, 1-3, against four isolates of clinical methicillin-resistant Staphylococcus aureus (MRSA-1, MRSA-2, MRSA-3 and MRSA-4). In PDI of a planktonic culture of MRSA-1, compound 3 showed the highest efficacy, likely owing to its advantageous light absorption, (1) O2 quantum yield and bacterial cellular binding. The PDI efficacy of 3 was further evaluated against all other strains and MRSA-1 biofilms. At appropriate PS concentrations, viability reduction of 100% or 96.83% was observed in planktonic or biofilm forms of MRSA, respectively. The mechanisms of action were investigated using negative staining transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). It was demonstrated that PDI of planktonic bacteria was achieved primarily through damage to the cell envelope. Biofilms were eliminated through both the destruction of their structure and inactivation of the individual bacterial cells. In conclusion, Ru(II) complexes, especially 3, are potential candidates for the effective photodynamic control of MRSA infections.
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http://dx.doi.org/10.1111/php.12378DOI Listing
January 2016

Thermal conductivity of a single Bi₀.₅Sb₁.₅Te₃ single-crystalline nanowire.

Nanotechnology 2014 Oct 24;25(41):415704. Epub 2014 Sep 24.

Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.

Single-crystalline Bi₀.₅Sb₁.₅Te₃ nanowires were fabricated by a template-assisted pulsed electrodeposition technique; the thermal conductivity of a single Bi₀.₅Sb₁.₅Te₃ nanowire of different diameters was characterized through a self-heating 3 ω method. The temperature-dependent resistance measurements prove the semiconductor behavior of the nanowires. The extremely low thermal conductivity of the nanowires was found compared with the corresponding bulk, and the Umklapp peaks shift to a higher temperature as the decreasing nanowire's diameter decreases, which qualitatively agrees with the theoretical calculations based on the Callaway model. The boundary scattering plays an important role in the reduction of the thermal conductivity and in the shift of the Umklapp peak of the Bi₀.₅Sb₁.₅Te₃ nanowires.
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http://dx.doi.org/10.1088/0957-4484/25/41/415704DOI Listing
October 2014

Evidence of topological two-dimensional metallic surface states in thin bismuth nanoribbons.

ACS Nano 2014 Jul 10;8(7):7506-12. Epub 2014 Jul 10.

High Magnetic Field Laboratory, Chinese Academy of Sciences , Hefei Anhui 230031, P. R. China .

Understanding the exotic quantum phenomena in bulk bismuth beyond its ultraquantum limit remains controversial and gives rise to renewed interest. The focus of the issues is whether these quantum properties have a conventional bulk nature or just the surface effect due to the significant spin-orbital interaction and in relation to the Bi-based topological insulators. Here, we present angular-dependent magnetoresistance (AMR) measurements on single-crystal bismuth nanoribbons of different thicknesses with magnetic fields up to 31 T. In thin nanoribbons with thickness of ∼40 nm, a two-fold rational symmetry of the low field AMR spectra and two sets of 1/2-shifted (i.e., γ = 1/2) Shubnikov-de Haas (SdH) quantum oscillations with exact two- dimensional (2D) character were obtained. However, when the thickness of the ribbon increases, a 3D bulk-like SdH oscillations with γ = 0 and a four-fold rotational symmetry of the AMR spectra appear. These results provided unambiguous transport evidence of the topological 2D metallic surface states in thinner nanoribbons with an insulating bulk. Our observations provide a promising pathway to understand the quantum phenomena in Bi arising from the surface states.
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http://dx.doi.org/10.1021/nn502813yDOI Listing
July 2014

[Horizontal transmission of Streptococcus mutans in caries-active preschool children].

Nan Fang Yi Ke Da Xue Xue Bao 2014 May;34(5):636-40

1Department of Stomatology, 2Department of Microbiology, General Hospital of PLA, Beijing 100853, China. E-mail:

Objective: To analyze horizontal transmission patterns of Streptococcus mutans among caries-active preschool children for early interventions of dental caries.

Methods: Plaque samples obtained from 20 caries-active preschool children between 4 and 5 years of age were cultured under anaerobic conditions for isolating S. mutans, which were identified by morphological and biochemical analyses and PCR using primers homologous to the surface protein glucosyltransferase B (gtfB). The genotypes of the isolated S. mutans strains were determined by arbitrarily primed PCR (AP-PCR).

Results: Of the 200 S. mutans isolates obtained, 19 were excluded by biochemical analysis, and the remaining 181 isolates were identified as S. mutans by PCR with primers of gtfB, showing 37 different genotypes as identified by AP-PCR. Six children were found to carry S. mutans of a single genotype, 11 carried 2 genotypes, 2 had 3 genotypes, and 1 had 4 genotypes; 2 children from different classes were found to carry S. mutans of the same single genotype.

Conclusion: We identified 37 genotypes of S. mutans in these caries-active preschool children, among whom horizontal transmissions of the strains were not found.
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May 2014

Comparative study of MALDI-TOF MS and VITEK 2 in bacteria identification.

J Thorac Dis 2014 May;6(5):534-8

Department of Microbiology, General Hospital of PLA, Beijing 100853, China.

Background: Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced in diagnostic microbiology laboratories for the identification of bacterial and yeast strains isolated from clinical samples. This study aimed to evaluate the accuracy of MALDI-TOF MS in clinical microbiology diagnosis by comparing it with commonly-used VITEK 2 or gene sequencing.

Methods: The performances of MALDI-TOF MS and VITEK 2 were compared retrospectively for identifying routine isolates. Discrepancies were analyzed by gene sequencing analysis of the 16S genes.

Results: For 1,025 isolates, classified as 55 species of 25 genera, 1,021 (99.60%) isolates were accurately identified at the genus level, and 957 (93.37%) isolates at the species level by using MALDI-TOF MS. A total of 949 (92.59%) isolates were completely matched by both methods. Both methods found 76 unmatched isolates among which one strain had no definite identification by MALDI-TOF MS and VITEK 2 respectively. However, MALDI-TOF MS made no errors at the genus level while VITEK 2 made 6 (0.58%) errors at the genus level. At the species level, the identification error rates for MALDI-TOF MS and VITEK 2 were 5.56% and 6.24%, respectively.

Conclusions: With a lower identification error rate, MALDI-TOF MS has better performance than VITEK 2 in identifying bacteria found routinely in the clinical laboratory. It is a quick and cost-effective technique, and has the potential to replace conventional phenotype methods in identifying common bacterial isolates in clinical microbiology laboratories.
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http://dx.doi.org/10.3978/j.issn.2072-1439.2014.02.18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4015025PMC
May 2014
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