13 results on '"Yamasaki, Shinji"'
Search Results
2. Hypochlorous acid solution is a potent antiviral agent against SARS‐CoV‐2.
- Author
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Hatanaka, Noritoshi, Yasugi, Mayo, Sato, Tomoko, Mukamoto, Masafumi, and Yamasaki, Shinji
- Subjects
ANTIVIRAL agents ,HYPOCHLORITES ,SARS-CoV-2 ,ACID solutions - Abstract
Aim: A novel coronavirus, termed severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) suddenly appeared in Wuhan, China, and has caused pandemic. In this study, we evaluated antiviral activity of purified hypochlorous acid (HClO) against coronaviruses such as SARS‐CoV‐2 and transmissible gastroenteritis virus (TGEV) responsible for pig diseases. Materials and Results: In a suspension test, 28.1 ppm HClO solution inactivated SARS‐CoV‐2 in phosphate‐buffered saline with the reduction of 104 of 50% tissue culture infectious dose per ml (TCID50 per ml) within 10 s. When its concentration increased to 59.4 ppm, the virus titre decreased to below the detection limit (reduction of 5 logs TCID50) within 10 s even in the presence of 0.1% foetal bovine serum. In a carrier test, incubation with 125 ppm HClO solution for 10 min or 250 ppm for 5 min inactivated SARS‐CoV‐2 by more than 4 logs TCID50 per ml or below the detection limit. Because the titre of TGEV was 10‐fold higher, TGEV was used for SARS‐CoV‐2 in a suspension test. As expected, 56.3 ppm HClO solution inactivated TGEV by 6 logs TCID50 within 30 s. Conclusions: In a carrier test, 125 ppm HClO solution for 10 min incubation is adequate to inactivate 4 logs TCID50 per ml of SARS‐CoV‐2 or more while in a suspension test 56.3 ppm HClO is adequate to inactivate 5 logs TCID50 per ml of SARS‐CoV‐2 when incubated for only 10 s regardless of presence or absence of organic matter. Significance and Impact of the Study: Effectiveness of HClO solution against SARS‐CoV‐2 was demonstrated by both suspension and carrier tests. HClO solution inactivated SARS‐CoV‐2 by 5 logs TCID50 within 10 s. HClO solution has several advantages such as none toxicity, none irritation to skin and none flammable. Thus, HClO solution can be used as a disinfectant for SARS‐CoV‐2. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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3. Development of a bivalent food poisoning vaccine: augmented antigenicity of the C-terminus of Clostridium perfringens enterotoxin by fusion with the B subunit of Escherichia coli Shiga toxin 2.
- Author
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Hosomi, Koji, Hinenoya, Atsushi, Suzuki, Hidehiko, Nagatake, Takahiro, Nishino, Tomomi, Tojima, Yoko, Hirata, So-ichiro, Matsunaga, Ayu, Kondoh, Masuo, Yamasaki, Shinji, and Kunisawa, Jun
- Subjects
ESCHERICHIA coli toxins ,FOOD poisoning ,CLOSTRIDIUM perfringens ,IMMUNOGLOBULIN class switching ,ENTEROTOXINS - Abstract
Food poisonings caused by Clostridium perfringens and Shiga toxin (Stx)-producing Escherichia coli (STEC) occur frequently worldwide; however, no vaccine is currently available. Therefore, we aimed to develop a bivalent vaccine against C. perfringens and STEC infections. Although it has been considered that the C-terminal region of C. perfringens enterotoxin (C-CPE) could be a good vaccine antigen to block the binding to its receptor, it was insufficient for induction of a protective immune response because of the low antigenicity. However, the fusion of C-CPE with Stx2 B subunit (Stx2B) augmented the antigenicity of C-CPE without affecting the antigenicity of Stx2B. Indeed, high levels of C-CPE-specific neutralizing IgG were found in the serum of mice immunized with the fusion protein Stx2B–C-CPE. Additionally, comparable and substantial levels of Stx2B-specific neutralizing IgG were induced in mice receiving Stx2B–C-CPE or Stx2B alone. These antibody responses against C-CPE and Stx2B lasted for at least 48 weeks, which were sufficient for protective immunity in vitro and in vivo, indicating that Stx2B–C-CPE could induce long-term protective immunity. As an underlying mechanism, ex vivo stimulation with Stx2B, but not with C-CPE, induced cytokine production from splenic T cells collected from mice immunized with Stx2B–C-CPE, suggesting that Stx2B-specific, but not C-CPE-specific, T cells were induced by the immunization with Stx2B–C-CPE and plausibly promoted immunoglobulin class switching of both Stx2B- and C-CPE-specific B cells from IgM to IgG. These findings collectively indicate that Stx2B–C-CPE is a T-cell-antigen-supplement-type bivalent vaccine, which could be an efficient against C. perfringens and STEC infections. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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4. Immunogenicity and protective efficacy of Vibrio cholerae outer membrane vesicles in rabbit model.
- Author
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Roy, Nivedita, Barman, Soumik, Ghosh, Amit, Pal, Amit, Chakraborty, Krishnendu, Das, Santa Sabuj, Saha, Dhira Rani, Yamasaki, Shinji, and Koley, Hemanta
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VIBRIO cholerae ,IMMUNIZATION ,LABORATORY rabbits ,VIBRIO infections ,PREVENTIVE medicine - Abstract
We show here that oral immunization with purified outer membrane vesicles (OMVs) of Vibrio cholerae induces a prolonged high rise in the protective antibody titre. Rabbit immune sera were vibriocidal against the homologous and against several heterologous V. cholerae strains in vitro. In addition, OMV immunization conferred significant protective immunity against subsequent bacterial challenges. Thirty OMV-immunized rabbits were challenged with different V. cholerae strains; each challenged group contained five immunized and three unimmunized animals. All the immunized rabbits survived bacterial challenges and were healthy after 24 h, except the two from each group that received the SG24 and SG06 strains, respectively, which developed watery diarrhoea. In contrast, all the unimmunized animals developed cholera-like symptoms, with a death toll of eight within 24 h of challenge. This is the first report of the induction of protective immunity by V. cholerae OMVs in a rabbit model (removable intestinal tie-adult rabbit diarrhoea) that mimics the human disease. Finally, OMVs were found to be significantly less reactogenic than the live and the heat-killed bacteria. Our studies show that oral immunization with OMVs of V. cholerae may induce long-term immunity and may be useful as a ‘nonliving’ vaccine candidate for the future. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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5. Capsaicin, a potential inhibitor of cholera toxin production in Vibrio cholerae.
- Author
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Chatterjee, Shruti, Asakura, Masahiro, Chowdhury, Nityananda, Neogi, Sucharit Basu, Sugimoto, Norihiko, Haldar, Soumya, Awasthi, Sharda Prasad, Hinenoya, Atsushi, Aoki, Shunji, and Yamasaki, Shinji
- Subjects
CAPSAICIN ,CAPSICUM annuum ,CHOLERA toxin ,SEROTYPES ,VIBRIO cholerae ,GENETIC transcription ,MICROBIAL virulence -- Molecular aspects ,MICROBIAL viability counts ,REVERSE transcriptase polymerase chain reaction - Abstract
The use of natural compounds as inhibitory agents for virulence factor production is a new approach to overcome increased antimicrobial resistance in pathogenic bacteria. In this study, we examined whether red chilli ( Capsicum annuum) contains any such compound(s) that can repress the cholera toxin (CT) production in Vibrio cholerae. We found that the methanol extract of red chilli could inhibit CT production in recently emerged V. cholerae O1 El Tor variant strains without affecting their viability. Interestingly, capsaicin, a well-studied active component of red chilli, also drastically inhibited CT production in V. cholerae strains belonging to various serogroups including variants. Real-time quantitative reverse transcription-PCR assay revealed that capsaicin effectively repressed the transcription of ctxA, tcpA and toxT genes, but not of toxR and toxS genes. On the contrary, capsaicin significantly enhanced the transcription of the hns gene, the product of which is known to regulate negatively the transcription of ctxAB, tcpA and toxT genes. These results suggest that capsaicin might act as a potent repressor for CT production possibly by enhancing the transcription of hns. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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6. Development of a cytolethal distending toxin ( cdt) gene-based species-specific multiplex PCR assay for the detection and identification of Campylobacter jejuni, Campylobacter coli and Campylobacter fetus.
- Author
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Asakura, Masahiro, Samosornsuk, Worada, Hinenoya, Atsushi, Misawa, Naoaki, Nishimura, Kazuhiko, Matsuhisa, Akio, and Yamasaki, Shinji
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CAMPYLOBACTER infections ,CAMPYLOBACTER jejuni ,CAMPYLOBACTER fetus ,TOXINS ,BACTERIAL antigens ,BACTERIAL diseases ,POLYMERASE chain reaction ,MICROBIAL toxins ,GENE expression - Abstract
A cytolethal distending toxin ( cdt) gene-based species-specific multiplex PCR assay for the detection of cdtA, cdtB or cdtC gene of Campylobacter jejuni, Campylobacter coli or Campylobacter fetus, respectively, was developed and evaluated with 76 Campylobacter strains belonging to seven different species and 131 other bacterial strains of eight different genera. The cdtA, cdtB or cdtC gene of C. jejuni, C. coli or C. fetus, respectively, could be successfully amplified using the corresponding set of primers in a highly species-specific manner. Furthermore, the specific primer set for the cdtA, cdtB or cdtC gene of a particular species could amplify the desired gene from a mixture of DNA templates of any of two or all three species. The detection limit of C. jejuni, C. coli or C. fetus was 10–100 CFU tube
−1 by the multiplex PCR assay on the basis of the presence of the cdtA, cdtB or cdtC gene. These data indicate that the cdt gene-based multiplex PCR assay may be useful for rapid and accurate detection as well as identification of Campylobacter strains in a species-specific manner. [ABSTRACT FROM AUTHOR]- Published
- 2008
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7. Integron-bearing methicillin-resistant coagulase-negative staphylococci in South China, 2001–2004.
- Author
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Zhenbo Xu, Lei Shi, Alam, M. J., Lin Li, and Yamasaki, Shinji
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GRAM-negative bacteria ,ENTEROBACTERIACEAE ,BLOOD coagulation ,DRUG resistance in microorganisms ,METHICILLIN resistance ,SOUTHERN blot ,GENETIC transformation - Abstract
A total of 53 methicillin-resistant coagulase-negative staphylococci strains isolated in a hospital in Guangzhou, China, were analyzed to detect class 1 integrons and SCC mec typing. Thirty strains had the class 1 integrase ( intI1) gene and 26 strains possessed the 3′ conserved region of qacEΔ 1- sul1. Four different types of gene cassette arrays were found and a highly prevalent array of dfrA12-orfF-aadA2 gene cassettes was observed. Thirty class 1 integron-positive coagulase-negative staphylococci strains were subjected to Southern hybridization analysis; the result showed that class 1 integrons were located on chromosome, not plasmid. According to the results of SCC mec typing for 30 integron-bearing MRCNS strains, five, 15 and five strains belonged to type I, II and III SCC mec, respectively, and five strains were untypeable. For 23 non-integron-bearing methicillin-resistant coagulase-negative staphylococci strains, four, nine and seven strains belonged to type I, II and III SCC mec, respectively, and three strains were untypeable. None of the strains belonged to type IV or V. Twenty-three coagulase-negative staphylococci isolates of three Staphylococcal species that contained the dfrA12-orfF-aadA2 gene cassette array were phylogenetically unrelated to each other by randomly amplified polymorphic DNA, indicating that the gene cassettes might be disseminated in the clinical strains by a horizontal gene transfer. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
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8. Comparison of PCR-RFLP and PFGE for determining the clonality of enterohemorrhagic Escherichia coli strains.
- Author
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Shima, Kensuke, Yoshii, Noriyo, Akiba, Masato, Nishimura, Kazuhiko, Nakazawa, Muneo, and Yamasaki, Shinji
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POLYMERASE chain reaction ,PULSED-field gel electrophoresis ,ESCHERICHIA coli O157:H7 ,RESTRICTION fragment length polymorphisms ,DNA fingerprinting - Abstract
We report here on a comparative evaluation of PCR-restriction fragment length polymorphism (PCR-RFLP) and pulsed-field gel electrophoresis (PFGE) assays, and ascertain the clonal relationship between 13 enterohemorrhagic Escherichia coli O157 : H7 strains isolated from fecal samples collected from three cows over a period of 2 months. PCR-RFLP analysis was carried out with either BglI or EcoRV digested LA-PCR amplicons, generated by targeting region V of the Stx-phage. While PCR-RFLP analysis placed these 13 strains into a single clonal type, pulsotyping analysis, as reported earlier, grouped these strains into four different PFGE subtypes of which three were closely related, while the other appeared to be different. The comparative analysis was extended further using two clonally different wild-type (3-0 and Sakai 215) strains and 17 derivative strains which had passed through an animal's gastrointestinal tract. The PCR-RFLP assay, which was not only able to differentiate the wild-type strains, but also placed the passaged derivative strains into their respective parental group, although PFGE patterns of the same set of strains resulted from different PFGE subtypes. These data indicate that PCR-RFLP is the more reliable and useful assay for a molecular epidemiological survey of enterohemorrhagic E. coli strains. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
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9. Analysis of integrons in clinical isolates of Escherichia coli in China during the last six years.
- Author
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Jianyu Su, Lei Shi, Liansheng Yang, Zenghuang Xiao, Xinhui Li, and Yamasaki, Shinji
- Subjects
ESCHERICHIA coli ,ENTEROBACTERIACEAE ,POLYMERASE chain reaction ,ANTI-infective agents - Abstract
A multiple PCR for the detection of the integrase genes of the three classes of integrons was carried out, and their gene cassettes were characterized in 111 clinical strains of Escherichia coli isolated in Guangzhou City, China during the last 6 years. IntI1 and intI2 genes were detected in 95 isolates (85.6%) and four isolates (3.6%), respectively. No intI3 gene was detected. Six different gene cassettes were found in these strains, and a high prevalence of dfr and aad genes was observed. The E. coli isolates that contained a 1664-bp amplicon of dfrA17-aadA5 in class 1 integron were found to be phylogenetically unrelated to each other by using the enterobacterial repetitive intergenic consensus PCR, as the cassette could be transferred to recipient strains, indicating that the gene cassettes might be disseminated in the clinical strains by a horizontal gene transfer. Therefore, it is important that guidelines for the prudent use of antimicrobial agents are adopted and surveillance programs are established. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
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10. Characterisation of Shiga toxin-producing Escherichia coli (STEC) isolated from seafood and beef
- Author
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Kumar, H.S., Karunasagar, Indrani, Karunasagar, I., Teizou, Tsukamoto, Shima, Kensuke, and Yamasaki, Shinji
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ESCHERICHIA coli ,SEAFOOD ,BEEF ,DIARRHEA - Abstract
Shiga toxin-producing Escherichia coli (STEC) strains isolated in Mangalore, India, were characterised by bead-enzyme-linked immunosorbent assay (bead-ELISA), Vero cell cytotoxicity assay, PCR and colony hybridisation for the detection of
stx and1 stx genes. Four strains from seafood, six from beef and one from a clinical case of bloody diarrhoea were positive for Shiga toxins Stx1 and Stx2 and also for2 stx and1 stx genes. The seafood isolates produced either Stx2 alone or both Stx1 and Stx2, while the beef isolates produced Stx1 alone. The2 stx gene of all the beef STEC was found to be of recently reported1 stx c type. All STEC strains and one non-STEC strain isolated from clam harboured EHEC-hlyA. Interestingly, though all STEC strains were negative for eae gene, two STEC strains isolated from seafood and one from a patient with bloody diarrhoea possessed STEC autoagglutinating adhesion (saa) gene, recently identified as a gene encoding a novel autoagglutinating adhesion. [Copyright &y& Elsevier]1 - Published
- 2004
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11. Molecular characterisation of rough strains of Vibrio cholerae isolated from diarrhoeal cases in India and their comparison to smooth strains
- Author
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De, Keya, Ramamurthy, Thandavarayan, Faruque, Shah M., Yamasaki, Shinji, Takeda, Yoshifumi, Nair, G. Balakrish, and Nandy, Ranjan K.
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VIBRIO cholerae ,VIBRIO infections ,DIARRHEA ,GENES - Abstract
Sixteen of the 18 Vibrio cholerae rough strains isolated from hospitalised diarrhoea patients were found to contain O1 serotype-specific (wbe) genes and all currently known virulence genes. Expression of the regulatory element ToxR was evident in these strains. Cholera toxin production ability of the rough strains was found to be higher (c. three- to five-fold) as compared to the smooth counterparts and this was transcriptionally regulated. Strains exhibiting the rough phenotype were more amenable to the uptake of CTXφ, which led us to consider that the rough phenotype could play a role in the generation of genetic diversity among V. cholerae strains. [Copyright &y& Elsevier]
- Published
- 2004
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12. Development and evaluation of a multiplex PCR assay for rapid detection of toxigenic Vibrio cholerae O1 and O139.
- Author
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Hoshino, Katsuaki, Yamasaki, Shinji, Mukhopadhyay, Asish K, Chakraborty, Soumen, Basu, Arnab, Bhattacharya, Sujit K, Nair, G.Balakrish, Shimada, Toshio, and Takeda, Yoshifumi
- Published
- 1998
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13. Development of a multiplex PCR targeting eae , stx and cdt genes in genus Escherichia and detection of a novel cdtB gene in Providencia rustigianii.
- Author
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Hassan, Jayedul, Awasthi, Sharda Prasad, Hatanaka, Noritoshi, Okuno, Kentaro, Hoang, Phuong Hoai, Nagita, Akira, Hinenoya, Atsushi, and Yamasaki, Shinji
- Subjects
ESCHERICHIA ,GENES ,BACTERIAL genes ,ESCHERICHIA coli ,DIARRHEA in children ,POLYMERASE chain reaction - Abstract
This study was aimed to develop a multiplex PCR (m-PCR) for the detection of Escherichia coli attaching and effacing (eae), Shiga toxin (stx) and cytolethal distending toxin (cdt) genes encoding important virulence factors of diarrheagenic E. coli such as EPEC, STEC, and Escherichia albertii. For this purpose, the m-PCR was designed to detect eae, all the subtypes of stx (stx1, stx2a - g except stx2f) and cdt (I – V) genes. The m-PCR was validated with 58 and 55 target gene-positive and negative strains of different sources, respectively. Sensitivity and specificity of the m-PCR were 100%. The m-PCR could also detect the eae, stx and cdt genes in bacteria spiked into stool specimens with or without enrichment culture. Clinical specimens collected from children with diarrhea were tested by the m-PCR, and 27 eae and 32 cdt genes were detected. Among them, three cdt-II and one untypable cdt gene-positive bacteria were isolated and identified as E. albertii and Providencia rustigianii, respectively. This is the first report demonstrating the presence of cdtB gene in P. rustigianii. These results indicate that the m-PCR is useful for surveillance of eae, stx and cdt gene-positive bacteria, not only EPEC, STEC and E. albertii but also P. rustigianii. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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