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Kenji Hirose

Publications and source records attributed to Kenji Hirose.

17 recordsLinked to original sources
PubMed2006

Development of a real-time PCR assay for detection of gyrA mutations associated with reduced susceptibility to ciprofloxacin in Salmonella enterica serovar typhi and paratyphi A.

A real-time PCR assay with the cycling probe method was used to detect mutations at codons 83 and 87 in the DNA gyrase A subunit encoded by gyrA in Salmonella enterica serovar Typhi and Paratyphi A clinical isolates. The susceptibility estimated from the results of the gyrA mutation assay was consistent with that identified by the culture method using an E-test. This assay allows rapid screening of S. enterica serovar Typhi and Paratyphi A with reduced susceptibility to ciprofloxacin.

Anti-Bacterial Agents↗
PubMed2006

Characterization of lysine decarboxylase-negative strains of Salmonella enterica serovar Enteritidis disseminated in Japan.

Salmonella enterica serovar Enteritidis is one of the leading causes of food-borne diseases in Japan. Typically, Salmonella spp. test positive for lysine-decarboxylase. However, the number of isolates of serovar Enteritidis without lysine-decarboxylase activity increased in Japan in 2003. Among 109 strains from distinct outbreaks, 10 lacked lysine-decarboxylase activity. Nine of the ten lysine-decarboxylase-negative strains showed quite similar pulsed-field gel electrophoresis profiles. Their lysine-decarboxylase phenotype was recovered by introduction of the cadBA locus from an lysine-decarboxylase-positive strain. Although the cad loci of the lysine-decarboxylase-negative strains seemed to be intact without any insertion sequences, cadC, a positive regulator of cadBA, had a single-base deletion at the same position, the 973rd base (cytosine), in all the nine lysine-decarboxylase-negative strains, whereas the wild-type cadC gene has a 1542 bp coding region (514 amino acids). This deletion was expected to produce a truncated (338 amino acids) form of CadC due to a frameshift. Because CadC senses environmental cues such as external pH and lysine through its putative C-terminal periplasmic domain, it is likely that the truncated CadC is not sensitive enough to external signaling to activate the cadBA operon, resulting in loss of the lysine-decarboxylase activity. Our results suggest that dissemination of these genetically closely related strains of serovar Enteritidis accounts for the unusual increase in the isolation of lysine-decarboxylase-negative strains.

Amino Acid Sequence↗
PubMed2005

Antimicrobial susceptibility of Shigella sonnei isolates in Japan and molecular analysis of S. sonnei isolates with reduced susceptibility to fluoroquinolones.

We performed susceptibility testing with Shigella sonnei isolates from imported and domestic cases of infection in Japan during 2001 and 2002. Some S. sonnei isolates were resistant to nalidixic acid, tetracycline, and trimethoprim-sulfamethoxazole. Most of the nalidixic acid-resistant strains showed reduced susceptibility to fluoroquinolones but did not show fluoroquinolone resistance.

Drug Resistance, Bacterial↗
PubMed2004

Cloning and characterization of the gene encoding the z66 antigen of Salmonella enterica serovar Typhi.

Z66 antigen-positive strains of Salmonella enterica serovar Typhi change flagellin expression in only one direction from the z66 antigen to the d or j antigen, which is different from the phase variation of S. enterica serovar Typhimurium. In the present study, we identified a new flagellin gene in z66 antigen-positive strains of S. enterica serovar Typhi. The genomic structure of the region containing this new flagellin gene was similar to that of fljBA operon of biphasic S. enterica serovars. A fljA-like gene was present downstream of the new flagellin gene. A rho-independent terminator was located between the new flagellin gene and the fljA-like gene. Hin-like gene was not present upstream of the new flagellin gene. We generated a mutant strain of S. enterica serovar Typhi, which carries a deletion of the new flagellin gene. Western blotting revealed that the 51-kDa z66 antigen protein was absent from the population of proteins secreted by the mutant strain. Southern hybridization demonstrated that the z66 antigen-positive strains of S. enterica serovar Typhi carried the new flagellin gene and fliC on two different genomic EcoRI fragments. When z66 antigen-positive strains were incubated with anti-z66 antiserum, the flagellin expression by S. enterica serovar Typhi changed from z66 antigen to j antigen. The new flagellin gene and the fljA-like gene were absent in the strain with altered flagellin expression. These results suggested that the new flagellin gene is a fljB-like gene, which encodes the z66 antigen of S. enterica serovar Typhi, and that deletion of fljBA-like operon may explain why S. enterica serovar Typhi alters the flagellin expression in only one direction from the z66 antigen to the d or j antigen.

Antigens, Bacterial↗
PubMed2004

A multi-prefectural outbreak of Shigella sonnei infections associated with eating oysters in Japan.

Among roughly one thousand incidents of shigellosis annually in Japan, approximately 70% of the cases are estimated to be associated with overseas travel. However, at the end of 2001, reports of domestically acquired Shigella sonnei infections suddenly increased. We report here the first multi-prefectural outbreak of Shigella sonnei infections linked to the consumption of imported oysters in Japan at the end of 2001. Isolates of S. sonnei from patients epidemiologically linked to eating contaminated oysters and from the imported oysters themselves showed an indistinguishable pulsed-field gel electrophoresis pattern and drug resistance pattern.

Animals↗
PubMed2004

Necessity of meningococcal gamma-glutamyl aminopeptidase for Neisseria meningitidis growth in rat cerebrospinal fluid (CSF) and CSF-like medium.

The growth of a gamma-glutamyl aminopeptidase (GGT)-deficient Neisseria meningitidis strain was much slower than that of the parent strain in rat cerebrospinal fluid (CSF) and in a synthetic CSF-mimicking medium, and the growth failure was suppressed by the addition of cysteine. These results suggested that, in the environment of cysteine shortage, meningococcal GGT provided an advantage for meningococcal multiplication by supplying cysteine from environmental gamma-glutamyl-cysteinyl peptides.

Animals↗
PubMed2003

Local moment formation in quantum point contacts.

Spin-density-functional theory of quantum point contacts (QPCs) reveals the formation of a local moment with a net of one electron spin in the vicinity of the point contact-supporting the recent report of a Kondo effect in a QPC. The hybridization of the local moment to the leads decreases as the QPC becomes longer, while the on site Coulomb-interaction energy remains almost constant.

Journal Article↗
PubMed2003

Keratinocytes can differentiate into eccrine sweat ducts in vitro: involvement of epidermal growth factor and fetal bovine serum.

BACKGROUND: in addition to formation of an epidermal sheet and dermal substitution, reconstruction of skin that possesses functionality is an important goal for dermatologists. OBJECTIVE: we attempted to regenerate eccrine sweat glands in vitro. METHODS: we constructed skin equivalent models with various combination of normal human keratinocytes and fibroblasts and also examined the effect of various growth factors. RESULTS: we found that keratinocytes invaded the collagen gels and formed eccrine duct-like structures, only when (i) the culture media contained at least 15 ng/ml of epidermal growth factor (EGF) and fetal bovine serum (FBS), (ii) the keratinocytes were derived from young donors, and (iii) fibroblasts were present in the gel. Interestingly, when cultured under the same conditions eccrine gland duct cells were unable to invade the gel. Immunohistochemical analyses revealed induction of carcinoembryonic antigen by EGF at the inner part of the eccrine duct-like structures. Proliferating cell nuclear antigen was expressed mainly in basal layers of the epithelia but was not observed in the deeply invaded part. Cytokeratin profiles of the reconstructed epithelia were consistent with those of the regenerating epidermis and partly with the eccrine sweat duct. CONCLUSIONS: although not perfect model, these results indicate that 'young' keratinocytes could differentiate into/toward eccrine sweat ducts in vitro in the presence of EGF and FBS in cooperation with dermal fibroblasts.

Adolescent↗
PubMed2003

Screening method for Salmonella enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones by PCR-restriction fragment length polymorphism.

Salmonella enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones (MICs of ciprofloxacin, 0.25 to 2 microg/ml) have a mutation at codon either Ser-83 or Asp-87 of gyrA gene. A screening method by PCR-restriction fragment length polymorphism (PCR-RFLP) was designed to screen the mutations at codon Ser-83 and Asp-87 of the gyrA gene of S. enterica serovar Typhi and serovar Paratyphi A clinical isolates. This method successfully screened the gyrA mutations of S. enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones.

Anti-Infective Agents↗
PubMed2003

Multiplex polymerase chain reaction assay for selective detection of Salmonella enterica serovar typhimurium.

A multiplex polymerase chain reaction (PCR) assay was developed for the identification of Salmonella enterica serovar Typhimurium. Three sets of primers were designed for detecting O4, H:i, and H:1,2 antigen genes from the antigen-specific genes rfbJ, fliC, and fljB, respectively. These were evaluated in a multiplex PCR assay by using DNAs from S. enterica serovar Typhimurium, 15 other Salmonella serovars, and 8 non-Salmonella enteric pathogens. Multiplex PCR proved to be capable of identifying S. enterica serovar Typhimurium specifically and differentiating it from other Salmonella serovars in addition to non-Salmonella enteric pathogens. Thus, this multiplex PCR assay can be practically applied to the identification of S. enterica serovar Typhimurium.

Polymerase Chain Reaction↗
PubMed2002

Kondo model for the "0.7 anomaly" in transport through a quantum point contact.

Experiments on quantum point contacts have highlighted an anomalous conductance plateau around 0.7(2e(2)/h), with features suggestive of the Kondo effect. Here, an Anderson model for transport through a point contact analyzed in the Kondo limit. Hybridization to the band increases abruptly with energy but decreases with valence, so that the background conductance and the Kondo temperature T(K) are dominated by different valence transitions. This accounts for the high residual conductance above T(K). The model explains the observed gate-voltage, temperature, magnetic field, and bias-voltage dependences. A spin-polarized current is predicted even for low magnetic fields.

Journal Article↗
PubMed2002

DNA sequence analysis of DNA gyrase and DNA topoisomerase IV quinolone resistance-determining regions of Salmonella enterica serovar Typhi and serovar Paratyphi A.

The mutations that are responsible for fluoroquinolone resistance in the gyrA, gyrB, parC, and parE genes of Salmonella enterica serovar Typhi and serovar Paratyphi A were investigated. The sequences of the quinolone resistance-determining region of the gyrA gene in clinical isolates which showed decreased susceptibilities to fluoroquinolones had a single mutation at either the Ser-83 or the Asp-87 codon, and no mutations were found in the gyrB, parC, and parE genes.

Anti-Infective Agents↗
PubMed2002

Selective amplification of tyv (rfbE), prt (rfbS), viaB, and fliC genes by multiplex PCR for identification of Salmonella enterica serovars Typhi and Paratyphi A.

The PCR primers for O, H, and Vi antigen genes, tyv (rfbE), prt (rfbS), fliC-d, fliC-a, and viaB, were designed and used for the rapid identification of Salmonella enterica serovars Typhi and Paratyphi A with multiplex PCR. The results showed that all the clinical isolates examined of Salmonella serovars Typhi and Paratyphi A were accurately identified by this assay.

Antigens, Bacterial↗