56 results on '"Ken Shimuta"'
Search Results
52. Expression and secretion of scytalidopepsin B, an acid protease from Scytalidium lignicolum, in yeast
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Kohei Oda, Hiroshi Oyama, Naoko Oda-Ueda, Ken Shimuta, Daisuke Tsuru, and Masahiro Washio
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medicine.medical_treatment ,Saccharomyces cerevisiae ,Molecular Sequence Data ,Gene Expression ,Applied Microbiology and Biotechnology ,Biochemistry ,Analytical Chemistry ,Shuttle vector ,Scytalidium ,medicine ,Aspartic Acid Endopeptidases ,Amino Acid Sequence ,DNA, Fungal ,Molecular Biology ,Peptide sequence ,Enzyme Precursors ,Protease ,biology ,Base Sequence ,Organic Chemistry ,Amino-Terminal Amino Acid ,General Medicine ,biology.organism_classification ,Molecular biology ,Yeast ,Electrophoresis, Polyacrylamide Gel ,Mitosporic Fungi ,Scytalidopepsin B ,Biotechnology - Abstract
An expression and secretion system for scytalidopepsin B, an acid protease from Scytalidium lignicolum, was constructed in yeast. Saccharomyces cerevisiae AH22 was transformed with an yeast-E. coli shuttle vector, pAM82, in which an yeast invertase signal segment and the cDNA encoding the pro- and mature enzyme regions were inserted. The transformant was found to secret a pepstatin-insensitive acid protease, when cultured aerobically in a low phosphate (Pi) medium. Amino terminal amino acid sequencing analysis indicated that the recombinant acid protease was accurately processed and secreted as a mature form.
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- 2000
53. O3-S4.01 The new superbug Neisseria gonorrhoeae makes gonorrhoea untreatable?--first high-level ceftriaxone resistance worldwide and public health importance
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Ken Shimuta, Makoto Ohnishi, Takeshi Saika, Jo Kitawaki, Kouji Iwasaku, Daniel Golparian, Shu-ichi Nakayama, S Hoshina, and Magnus Unemo
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business.industry ,medicine.drug_class ,Cephalosporin ,Dermatology ,medicine.disease_cause ,Microbiology ,Agar dilution ,Infectious Diseases ,Antibiotic resistance ,Ceftriaxone ,Neisseria gonorrhoeae ,Medicine ,Multilocus sequence typing ,Typing ,business ,Etest ,medicine.drug - Abstract
Background The first Neisseria gonorrhoeae strain (H041) worldwide that is highly resistant to the extended-spectrum cephalosporin (ESC) ceftriaxone, which is the last remaining option for empirical treatment of gonorrhoea, has now been identified! This is a large public health problem and the era of untreatable gonorrhoea may now have been initiated. The present study completely characterised H041, phenotypically and genetically, to confirm the finding, comprehensively examine its antimicrobial resistance (AMR) and in detail elucidate the resistance mechanisms. Finally, public health actions for preventing and/or detaining global spread of ceftriaxone-resistant and untreatable gonorrhoea will be discussed. Methods H041 was examined using seven species-confirmatory tests, antibiograms (30 antimicrobials) with Etest and agar dilution (only for ESCs), porB sequencing, N gonorrhoeae multi-antigen sequence typing (NG-MAST), multilocus sequence typing (MLST) and sequencing of ESC resistance determinants (penA, mtrR, penB, ponA and pilQ). Transformation, using appropriate recipient strains, was performed to confirm the ESC resistance determinants. Results H041 was assigned serovar Bpyust, MLST ST7363 and the new NG-MAST ST4220. H041 proved highly resistant to ceftriaxone (2–4 mg/l, which is 4-8-fold higher than any previously described isolate) and all other cephalosporins, as well as most other antimicrobials tested. A new penA mosaic allele, containing only four not previously described amino acid alterations, caused the ceftriaxone resistance, which was all proven using several transformation experiments. Conclusions The new superbug N gonorrhoeae has now developed also ceftriaxone resistance and an era of untreatable gonorrhoea may have been initiated. A reduction in global gonorrhoea burden by enhanced disease control activities combined with wider strategies for general AMR control and enhanced understanding of mechanisms of emergence and spread of AMR, which need to be monitored globally, is crucial. Furthermore, a public health response plan (including sustainable clinical, microbiological and epidemiological components) for a global perspective is essential. Ultimately, new drugs are essential to develop for efficacious gonorrhoea treatment.
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- 2011
54. Emergence and evolution of internationally disseminated cephalosporin-resistant Neisseria gonorrhoeae clones from 1995 to 2005 in Japan.
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Ken Shimuta, Yuko Watanabe, Shu-ichi Nakayama, Tomoko Morita-Ishihara, Toshiro Kuroki, Unemo, Magnus, Makoto Ohnishi, Shimuta, Ken, Watanabe, Yuko, Nakayama, Shu-Ichi, Morita-Ishihara, Tomoko, Kuroki, Toshiro, and Ohnishi, Makoto
- Abstract
Background: Neisseria gonorrhoeae strains with resistance to extended-spectrum cephalosporins (ESCs), last options for first-line monotherapy of gonorrhoea, likely emerged and initially disseminated in Japan, followed by international transmission. In recent years, multi-locus sequence typing (MLST) ST1901 and N. gonorrhoeae multiantigen sequence typing (NG-MAST) ST1407 isolates with the mosaic penicillin-binding protein (PBP) 2 XXXIV have accounted for most ESC resistance globally. Our aim was to elucidate the initial emergence and transmission of ESC-resistant strains by detailed examination of N. gonorrhoeae isolates from 1995 to 2005 in Kanagawa, Japan.Methods: N. gonorrhoeae isolates were examined phenotypically (n = 690) and genetically (n = 372) by agar dilution method (cefixime, ceftriaxone and ciprofloxacin), penA gene sequencing, MLST and NG-MAST.Results: Already in 1995, one cefixime-resistant (CFM-R) isolate was found, which is the first CFM-R isolate described globally. After 1996, the prevalence of CFM-R and CFM-decreased susceptibility (CFM-DS) isolates significantly increased, with the peak resistance level in 2002 (57.1% CFM-R). In 1997-2002, the CFM-R MLST ST7363 strain type with the mosaic PBP 2 X was predominant among CFM-R/DS isolates. The first CFM-R/DS MLST ST1901 clone(s), which became the predominant CFM-R/DS strain type(s) already in 2003-2005, possessed the mosaic PBP 2 X, which was possibly originally transferred from the MLST ST7363 strains, and subsequently acquired the mosaic PBP 2 XXXIV. The first MLST ST1901 and NG-MAST ST1407 isolate was identified in Kanagawa already in 2003.Conclusions: The two main internationally spread cefixime-resistant gonococcal clones, MLST ST7363 and ST1901 (NG-MAST ST1407 most frequent internationally) that also have shown their capacity to develop high-level ceftriaxone resistance (superbugs H041 and F89), likely emerged, evolved and started to disseminate in the metropolitan area, including Kanagawa, in Japan, which was followed by global transmission. [ABSTRACT FROM AUTHOR]- Published
- 2015
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55. The hemolytic and cytolytic activities of Serratia marcescens phospholipase A (PhlA) depend on lysophospholipid production by PhlA
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Nobuo Koizumi, Makoto Ohnishi, Sunao Iyoda, Haruo Watanabe, Naomasa Gotoh, and Ken Shimuta
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DNA, Bacterial ,Microbiology (medical) ,Erythrocytes ,lcsh:QR1-502 ,Biology ,Microbiology ,Hemolysis ,Phospholipases A ,lcsh:Microbiology ,Agar plate ,Hemolysin Proteins ,Phospholipase A2 ,Phospholipase A1 ,Bacterial Proteins ,Research article ,medicine ,Animals ,Humans ,Horses ,Cloning, Molecular ,Serratia marcescens ,Sequence Deletion ,Phospholipase A ,Sheep ,Hemolysin ,Sequence Analysis, DNA ,medicine.disease ,biology.organism_classification ,Cytolysis ,biology.protein ,Lysophospholipids ,HeLa Cells - Abstract
BackgroundSerratia marcescensis a gram-negative bacterium and often causes nosocomial infections. There have been few studies of the virulence factors of this bacterium. The onlyS. marcescenshemolytic and cytotoxic factor reported, thus far, is the hemolysin ShlA.ResultsAnS. marcescens shlAB deletion mutant was constructed and shown to have no contact hemolytic activity. However, the deletion mutant retained hemolytic activity on human blood agar plates, indicating the presence of anotherS. marcescenshemolytic factor. Functional cloning ofS. marcescensidentified a phospholipase A (PhlA) with hemolytic activity on human blood agar plates. AphlAB deletion mutant lost hemolytic activity on human blood agar plates. Purified recombinant PhlA hydrolyzed several types of phospholipids and exhibited phospholipase A1 (PLA1), but not phospholipase A2 (PLA2), activity. The cytotoxic and hemolytic activities of PhlA both required phospholipids as substrates.ConclusionWe have shown that theS. marcescens phlAgene produces hemolysis on human blood agar plates. PhlA induces destabilization of target cell membranes in the presence of phospholipids. Our results indicated that the lysophospholipids produced by PhlA affected cell membranes resulting in hemolysis and cell death.
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56. Characterization of azithromycin-resistant Neisseria gonorrhoeae isolated in Tokyo in 2005-2011.
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Yoshiko Takayama, Shu-ichi Nakayama, Ken Shimuta, Tomoko Morita-Ishihara, and Makoto Ohnishi
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MEDICAL periodicals , *NEISSERIA gonorrhoeae , *AZITHROMYCIN , *DRUG resistance in bacteria - Abstract
A total of 122 Neisseria gonorrhoeae isolated in the Tokyo metropolitan area in 2005-2011 were collected and analyzed by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and for their susceptibility to azithromycin and ceftriaxone. All 122 strains were susceptible to ceftriaxone, but 8 strains were azithromycin-resistant, defined as an azithromycin MIC = 1 µg/ml. The 8 azithromycin-resistant strains were in 6 NG-MAST types, 3 strains in NG-MAST type 1407 and each of the other 5 strains in a different NG-MAST type. NG-MAST type 1407 strains are multidrug-resistant and are disseminated worldwide. [ABSTRACT FROM AUTHOR]
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- 2014
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- View/download PDF
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