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510 results on '"Ebisu, Shigeyuki"'

12. Impact of sleep on the microbiome of oral biofilms

Author

Sotozono, Maki, primary, Kuriki, Nanako, additional, Asahi, Yoko, additional, Noiri, Yuichiro, additional, Hayashi, Mikako, additional, Motooka, Daisuke, additional, Nakamura, Shota, additional, Yamaguchi, Mikiyo, additional, Iida, Tetsuya, additional, and Ebisu, Shigeyuki, additional

Published
2021
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29. Plasmid-mediated genomic recombination at the pilin gene locus enhances the N-acetyl-D-galactosamine-specific haemagglutination activity and the growth rate of Eikenella corrodens

Author

Azakami, Hiroyuki, Akimichi, Hiromi, Noiri, Yuichiro, Ebisu, Shigeyuki, and Kato, Akio

Subjects
Gram-negative bacteria -- Genetic aspects, Bacterial genetics -- Research, Recombinant DNA -- Research, Biological sciences
Abstract

Eikenella corrodens belongs to a group of periodontopathogenic bacteria and forms unique corroding colonies on solid medium due to twitching motility. It is believed that an N-acetyl-D-galactosamine (GalNAc)-specific lectin on the cell surface contributes significantly to its pathogenicity and can be estimated by its haemagglutination (HA) activity. Recently, a plasmid, pMU1, from strain 1073 has been found; this plasmid affects pilus formation and colony morphology. To identify the gene involved in these phenomena, ORF 4 and ORFs 5-6 on pMU1 were separately subcloned into a shuttle vector, and the resultant plasmids were introduced into E. corrodens 23834. Transformants with the ORF 4 gene, which is identified to be a homologous gene of the type IV pilin gene-specific recombinase, lost their pilus structure and formed non-corroding colonies on a solid medium, whereas transformants with ORFs 5-6 exhibited the same phenotype as the host strain 23834. Southern analysis showed that the introduction of the ORF 4 gene into strain 23834 resulted in genomic recombination at the type IV pilin gene locus. The hybridization pattern of these transformants was similar to that of strain 1073. These results suggest that ORF 4 on pMU1 encodes a site-specific recombinase and causes genomic recombination of the type IV pilin gene locus. Furthermore, the introduction of ORF 4 into strain 23834 increased GalNAc-specific HA activity to a level equivalent to that of strain 1073. Although the morphological colony changes and loss of pilus structure are also observed in phase variation, genomic recombination of the type IV pilin gene locus did not occur in these variants. Moreover, an increase was not observed in the GalNAc-specific HA activity of these variants. These results suggested that the loss of pilus structure, the morphological change in colonies and the increase in HA activity due to plasmid pMU1 might be caused by a mechanism that differs from phase variation, such as a genomic recombination of the type IV pilin gene locus.

Published
2006

32. Identification and localization of extraradicular biofilm-forming bacteria associated with refractory endodontic pathogens

Author

Noguchi, Mobuo, Noiri, Yuichiro, Narimatsu, Masahiro, and Ebisu, Shigeyuki

Subjects
Pathogenic microorganisms -- Research, Microbial mats -- Research, Gram-negative bacteria -- Research, Biological sciences
Abstract

The identification and localization of bacteria in human extraradicular biofilms are investigated. The results have shown that Porphyromonas gingivalis, Tannellera forsythensis, and Fusobacterium nucleatum are associated with extraradicular biofilm formation and refractory periapical periodontitis.

Published
2005

46. Application of microwaves and millimeter waves for the characterization of teeth for dental diagnosis and treatment

Author

Hoshi, Naoya, Nikawa, Yoshio, Kawai, Kenji, and Ebisu, Shigeyuki

Subjects
Millimeter waves -- Usage, Dental technology -- Research, Dental caries -- Diagnosis, Business, Computers, Electronics, Electronics and electrical industries
Abstract

This paper presents applications of microwaves and millimeter waves for the characterization of teeth. This is done by measuring the complex permittivity over the frequency range from 0.04 to 40 GHz. These measurements have revealed that dental caries are significantly more lossy to microwaves and millimeter waves than the healthy tooth, and this difference can be used for dental diagnosis. The experimental results have been confirmed by using the finite-difference time-domain (FDTD) method. In addition, millimeter-wave heating of the lossy dental caries can be used as a sterilization treatment. It is concluded that millimeter waves can be used for dental medical diagnosis as well as dental medical treatment. Index Terms - Dentistry, FDTD methods, measurement, medical diagnosis, permittivity, scattering parameters measurement.

Published
1998

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