Time filter

Source Type

Hsieh J.H.,Ming Chi University of Technology | Li C.,National Yang Ming University | Lin Y.C.,Ming Chi University of Technology | Chiu C.H.,Chang Gung University | And 3 more authors.
Thin Solid Films | Year: 2015

Hard TaN-(Ag,Cu) nanocomposite films were deposited on PEEK (polyether ether ketone) substrates using reactive co-sputtering. The films were then annealed using RTA (Rapid Thermal Annealing) at 200°C to induce the nucleation and growth of soft metal particles in the TaN matrix and on the surface of the films. After examining the surface morphologies, structures, and mechanical properties of the samples, they were tested for their tribological properties under a normal load of 1 N or 5 N. It was found that the samples' tribological properties were much improved compared to uncoated PEEK, even though the substrate is relatively soft. This was especially apparent for heavier loads. Apparently, the solid lubricants (i.e., Ag and Cu particles) that emerged on coating's surface during the annealing process reduced the frictional force and wear rate of PEEK. These results were similar to those that were obtained using tool steel substrates. The coated samples were also tested for their anti-bacterial properties using Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria. It was found that the anti-bacterial efficiency of these samples was significant against both E. coli and S. aureus, even though the deposited samples were annealed through RTA at the relatively low temperature of 200°C. There was no peeling found between coatings and PEEK substrates after tribological and scratch testings. © 2015 Elsevier B.V.

Hsieh Y.-C.,Chang Gung University | Hsieh Y.-C.,Molecular Infectious Diseases Research Center | Lin T.-L.,National Taiwan University | Chang K.-Y.,National Taiwan University | And 5 more authors.
Journal of Infectious Diseases | Year: 2013

Background. The Streptococcus pneumoniae serotype 19A sequence type (ST) 320 clone, derived from an international Taiwan19F-14 (ST236) clone, has become prevalent in many countries.Methods. The dynamics of invasive pneumococcal disease (IPD) were determined using the database of the National Notifiable Disease Surveillance System in Taiwan. The virulence of 19A ST320 and Taiwan19F-14 (ST236) were assessed in mice. By constructing an isogenic serotype 19F variant of the 19A ST320 strain (19F ST320), we analyzed the role of capsular type and genetic background on the difference in virulence between 19A ST320 and Taiwan19F-14 (ST236).Results. Between 2008 and 2011, IPD due to serotype 19A increased from 2.1 to 10.2 cases per 100 000 population (P <. 001); IPD due to any serotype also significantly increased (P =. 01). Most serotype 19A isolates belonged to ST320. Using competition experiments in a murine model of colonization, we demonstrated that 19A ST320 outcompeted Taiwan19F-14 (ST236; competitive index, 20.3; P =. 001). 19F ST320 was 2-fold less competitive than the 19A ST320 parent (competitive index, 0.47; P =. 04) but remained 14-fold more competitive than Taiwan 19F-14 (ST236; competitive index, 14.7; P <. 001).Conclusions. Genetic evolution of pneumococcal clones from Taiwan19F-14 (ST236) to 19A ST320 has made this pneumococcus better able to colonize of the nasopharynx. This evolution reflects not only a switch in capsular serotype but also changes in other loci. © 2013 The Author 2013. All rights reserved.

Ye J.,Zhejiang University | Su L.-H.,Chang Gung University | Chen C.-L.,Molecular Infectious Diseases Research Center | Hu S.,Zhejiang University | And 3 more authors.
Plasmid | Year: 2011

Salmonella enterica serotype Choleraesuis (S. Choleraesuis) usually causes systemic infections in man and needs antimicrobial treatment. Multidrug resistance (MDR) in S. Choleraesuis is thus a great concern in the treatment of systemic non-typhoid salmonellosis. A large plasmid, pSC138, was identified in 2002 from a S. Choleraesuis strain SC-B67 that was resistant to all antimicrobial agents commonly used to treat salmonellosis, including ciprofloxacin and ceftriaxone. Complete DNA sequence of the plasmid had been determined previously (Chiu et al., 2005). In the present study, the sequence of pSC138 was reannotated in detail and compared with several newly sequenced plasmids. Some transposable elements and drug resistance genes were further delineated. Plasmid pSC138 was 138,742bp in length and consisted of 177 open reading frames (ORFs). While 134 of the ORFs displayed significant identity levels to other plasmid and prokaryotic sequences, the remaining 43 ORFs have not been previously reported. Mobile elements, including two integrons, seven insertion sequences and eight transposons, and a truncated prophage together encompass at least 66,781bp (48.1%) of the plasmid genome. The sequence of pSC138 consists of three major regions: a large composite transposable region Tn6088 with a Tn21-like backbone inserted by a variety of integrons or transposable elements; a transfer/maintenance region that contains a conserved ISEcp1-mediated transposon-like element Tn6092, carrying an AmpC gene, blaCMY-2, that confers the ceftriaxone resistance; and a Rep_3 type of replication region. Another seven bacteremic strains of S. Choleraesuis that expressed the same MDR phenotype were identified during 2003-2008. The same Rep_3 type replicase and the blaCMY-2-containing, ISEcp1-mediated transposon-like element were found in the MDR isolates, suggesting a successful preservation and dissemination of the MDR plasmid. Comparison of pSC138 with other recently published plasmids revealed a high identity level between partial sequences of pSC138 and plasmids of the same or different incompatibility groups. The large MDR region found in pSC138 may provide a niche for the future evolution of the plasmid by acquisition of relevant resistance genes through the panoply of mobile elements and illegitimate recombination events. © 2010 Elsevier Inc.

Chou L.-F.,Kidney Research Center | Chen T.-W.,Chang Gung University | Ko Y.-C.,Kidney Research Center | Pan M.-J.,Central Taiwan University of Science and Technology | And 5 more authors.
Emerging Microbes and Infections | Year: 2014

Leptospira santarosai serovar Shermani is the most frequently encountered serovar, and it causes leptospirosis and tubulointerstitial nephritis in Taiwan. This study aims to complete the genome sequence of L. santarosai serovar Shermani and analyze the transcriptional responses of L. santarosai serovar Shermani to renal tubular cells. To assemble this highly repetitive genome, we combined reads that were generated from four next-generation sequencing platforms by using hybrid assembly approaches to finish two-chromosome contiguous sequences without gaps by validating the data with optical restriction maps and Sanger sequencing. Whole-genome comparison studies revealed a 28-kb region containing genes that encode transposases and hypothetical proteins in L. santarosai serovar Shermani, but this region is absent in other pathogenic Leptospira spp. We found that lipoprotein gene expression in both L. santarosai serovar Shermani and L. interrogans serovar Copenhageni were upregulated upon interaction with renal tubular cells, and LSS19962, a L. santarosai serovar Shermani-specific gene within a 28-kb region that encodes hypothetical proteins, was upregulated in L. santarosai serovar Shermani-infected renal tubular cells. Lipoprotein expression during leptospiral infection might facilitate the interactions of leptospires within kidneys. The availability of the whole-genome sequence of L. santarosai serovar Shermani would make it the first completed sequence of this species, and its comparison with that of other Leptospira spp. may provide invaluable information for further studies in leptospiral pathogenesis. © 2014 SSCC.

Chen C.-L.,Molecular Infectious Diseases Research Center | Su L.-H.,Chang Gung University | Chiu C.-H.,Molecular Infectious Diseases Research Center | Chiu C.-H.,Chang Gung University
Food Research International | Year: 2012

Salmonella enterica serotype Choleraesuis usually causes systemic infection in humans that requires antimicrobial therapy. The emergence of S. Choleraesuis resistant to multiple antimicrobial agents, notably fluoroquinolones, has added difficulties in the selection of appropriate antibiotics. In the present study, microarray analysis was used to evaluate the gene expression changes in S. Choleraesuis with or without the presence of sub-inhibitory concentrations of ciprofloxacin. The expression changes in a ciprofloxacin-resistant strain, SC-B67, were compared to those observed in a ciprofloxacin-susceptible strain, SC-B42. An expression change was considered significant and included for analysis if the difference was over 1.5 fold. Genes showing concomitant up-regulation or down-regulation as well as those showing consistent over-expression/repression in both strains were excluded from analysis. With the addition of ciprofloxacin at 0.5-fold minimum inhibitory concentrations, the number of genes with significant expression changes was much greater in SC-B67 (274 genes; 225 up-regulated and 49 down-regulated) than in SC-B42 (57 genes; 8 up-regulated and 49 down-regulated; P< 0.001). Genes involved in a wide variety of transporters and metabolism functions, including amino acids, carbohydrates, inorganic ions, and coenzymes, were significantly up-regulated. The transcription/translation and replication/recombination/repair processes as well as signal transduction mechanisms were also vividly up-regulated. However, majority of the significant changes were observed only in the ciprofloxacin-resistant strain SC-B67. Besides the well studied resistance mechanisms associated with fluoroquinolone resistance, the ability to respond to unfavorable antibiotic-related stress through the transcriptional modulation of massive genes involved in many vital biological functions may be crucial for S. Choleraesuis to survive and hence become resistant to the antibiotics. © 2011 Elsevier Ltd.

Discover hidden collaborations