The Experts below are selected from a list of 13347 Experts worldwide ranked by ideXlab platform

Dong-hyun Kang - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of a new UVC LEDs array continuous type water Disinfection System for inactivating Escherichia coli O157:H7 according to flow rate and electrical energy efficiency analysis
    Food Control, 2021
    Co-Authors: Kyun Kim, Dong-hyun Kang
    Abstract:

    Abstract UVC LEDs are gaining popularity for its advantages which compensate for the limitations of low-pressure mercury UV lamps. In order to investigate the efficacy of UVC LEDs-based continuous water Disinfection System, various numbers of UVC LEDs chips were introduced to inactivate Escherichia coli O157:H7 in water. Also, the effect of an aluminum reflector in the irradiation System was investigated in order to enhance bacterial inactivation. Without the reflector, the pathogen inactivation profile showed a sigmoidal curve, while linear fitting was shown for the treatment with the reflector, and there was a 1.5 times greater bactericidal effect when the reflector was installed. Based on the inactivation rate constant, no significant differences were revealed among the UVC LEDs chip arrays. Electrical energy efficiency necessary for 3- and 5-log reductions were calculated and the 18 UVC LEDs chip array consumed 30% less energy compared to the 33 UVC LEDs array. In this study, kinetic profiles of E. coli O157:H7 in a continuous water Disinfection System using UVC LEDs irradiation with or without a reflector under various operational currents were obtained. Electrical energy consumption was considered in order to optimize the efficacy of this Disinfection System. These results can be used as practical database to develop a water Disinfection System using UVC LEDs and attributed to water and food safety.

  • UVC LED Irradiation Effectively Inactivates Aerosolized Viruses, Bacteria, and Fungi in a Chamber-Type Air Disinfection System.
    Applied and Environmental Microbiology, 2018
    Co-Authors: Dong-hyun Kang
    Abstract:

    ABSTRACT In this study, the possibility of inactivating viral, bacterial, and fungal aerosols in a chamber-type air Disinfection System by using a UVC light-emitting-diode (LED) array was investigated and inactivation rate constants of each microorganism were calculated in fitting curves of surviving populations. UVC LED array treatment effectively inactivated viral infectivity, achieving 5-log reductions within 45 mJ/cm2 for MS2, Qβ, and ϕX174 viruses. UVC LED array effectiveness in inactivating Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Staphylococcus aureus aerosols achieved 2.5- to 4-log reductions within 1.5 to 4.6 mJ/cm2. Also, 4-log reductions of Aspergillus flavus and Alternaria japonica were achieved at a dosage of 23 mJ/cm2 using UVC LED array irradiation. The highest UV susceptibility, represented by the inactivation rate constant, was calculated for bacteria, followed by fungi and viruses. UVC LED, an innovative technology, can effectively inactivate microorganisms regardless of taxonomic classification and can sufficiently substitute for conventional mercury UV lamps. IMPORTANCE The United Nations Environment Programme (UNEP) convened the Minamata Convention on Mercury in 2013 to ban mercury-containing products in order to ensure human and environmental health. It will be effectuated in 2020 to discontinue use of low-pressure mercury lamps and new UV-emitting sources have to replace this conventional technology. However, the UV germicidal irradiation (UVGI) System still uses conventional UV lamps, and no research has been conducted for air Disinfection using UVC LEDs. The research reported here investigated the inactivation effect of aerosolized microorganisms, including viruses, bacteria, and fungi, with an UVC LED module. The results can be utilized as a primary database to replace conventional UV lamps with UVC LEDs, a novel type of UV emitter. Implementation of UVC LED technology is truly expected to significantly reduce the extent of global mercury contamination, and this study provides important baseline data to help ensure a healthier environment and increased health for humanity.

Yoshimi Niwano - One of the best experts on this subject based on the ideXlab platform.

  • In vitro and in vivo anti-Staphylococcus aureus activities of a new Disinfection System utilizing photolysis of hydrogen peroxide.
    Journal of bioscience and bioengineering, 2012
    Co-Authors: Eisei Hayashi, Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate in vitro and in vivo antibacterial activity of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of oral infection diseases such as periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by the photolysis of H(2)O(2) in which 1 mol l(-1) H(2)O(2) was irradiated with a dual wavelength-light emitting diode (LED) at wavelengths of 400 and 465 nm was confirmed by applying an electron spin resonance-spin trapping technique. Secondly, the bactericidal effect of the System was examined under a similar condition in which Staphylococcus aureus suspended in 1 mol l(-1) H(2)O(2) was irradiated with LED light, resulting in substantial reduction of the colony forming unit (CFU) of the bacteria within a short time as 2 min. Finally, in vivo antibacterial effect of the photolysis of H(2)O(2) on a rat model of S. aureus infection was evaluated by a culture study. Since a significant reduction of recovered CFU of S. aureus was obtained, it is expected that in vitro antibacterial effect attributable to hydroxyl radicals generated by photolysis of H(2)O(2) could be well reflected in in vivo superficial bacterial infection.

  • Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a Disinfection System utilizing photolysis of hydrogen peroxide
    Journal of clinical biochemistry and nutrition, 2012
    Co-Authors: Taro Kanno, Keisuke Nakamura, Keiichi Sasaki, Hiroyo Ikai, Katsushi Kikuchi, Yoshimi Niwano
    Abstract:

    We have developed a new Disinfection System for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the System especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

  • Topical treatment of oral cavity and wounded skin with a new Disinfection System utilizing photolysis of hydrogen peroxide in rats
    The Journal of toxicological sciences, 2012
    Co-Authors: Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Eisei Hayashi, Yoshiko Kawana, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate the acute locally injurious property of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by a test device utilizing the photolysis of H(2)O(2) was confirmed by applying an electron spin resonance (ESR)-spin trapping technique. Secondly, the bactericidal effect of the device was examined under a simulant condition in which Staphylococcus aureus suspended in 1 M H(2)O(2) was irradiated with laser light emitted from the test device, resulting in substantial reduction of the colony forming unit of the bacteria within a short time as 2 min. Finally, acute topical effect of the Disinfection System on rat oral mucosa and wounded skin was evaluated by histological examination. No abnormal findings were observed in the buccal mucosal region treated three times with 1 M H(2)O(2) and irradiation. Similarly, no abnormal findings were observed during the healing of skin treated with 1 M H(2)O(2) and irradiation immediately after wounding. Since topical treatment with the novel Disinfection technique utilizing the photolysis of H(2)O(2) had no detrimental effect on the oral mucosa and the healing of full thickness skin wounds in rats, it is expected that the acute locally injurious property of the Disinfection technique is low.

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    Received 2 June 2010/Returned for modification 28 July 2010/Accepted 27 September 2010 The relationship between the amount of hydroxyl radicals generated by photolysis of H2O2 and bactericidal activity was examined. H2O2 (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions i n1MH 2O2 resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 M hydroxyl radicals would result in reductions of viable counts of >99.99%. Oral infectious diseases such as dental caries, periodontitis, and endodontic infections, all of which affect teeth and periodontal tissue, are caused by bacteria that inhabit the oral cavity. It is estimated that 150 or more different species of bacteria inhabit the human oral cavity (27). Of these bacteria,

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    The relationship between the amount of hydroxyl radicals generated by photolysis of H(2)O(2) and bactericidal activity was examined. H(2)O(2) (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions in 1 M H(2)O(2) resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 μM hydroxyl radicals would result in reductions of viable counts of >99.99%.

Taro Kanno - One of the best experts on this subject based on the ideXlab platform.

  • In vitro and in vivo anti-Staphylococcus aureus activities of a new Disinfection System utilizing photolysis of hydrogen peroxide.
    Journal of bioscience and bioengineering, 2012
    Co-Authors: Eisei Hayashi, Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate in vitro and in vivo antibacterial activity of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of oral infection diseases such as periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by the photolysis of H(2)O(2) in which 1 mol l(-1) H(2)O(2) was irradiated with a dual wavelength-light emitting diode (LED) at wavelengths of 400 and 465 nm was confirmed by applying an electron spin resonance-spin trapping technique. Secondly, the bactericidal effect of the System was examined under a similar condition in which Staphylococcus aureus suspended in 1 mol l(-1) H(2)O(2) was irradiated with LED light, resulting in substantial reduction of the colony forming unit (CFU) of the bacteria within a short time as 2 min. Finally, in vivo antibacterial effect of the photolysis of H(2)O(2) on a rat model of S. aureus infection was evaluated by a culture study. Since a significant reduction of recovered CFU of S. aureus was obtained, it is expected that in vitro antibacterial effect attributable to hydroxyl radicals generated by photolysis of H(2)O(2) could be well reflected in in vivo superficial bacterial infection.

  • Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a Disinfection System utilizing photolysis of hydrogen peroxide
    Journal of clinical biochemistry and nutrition, 2012
    Co-Authors: Taro Kanno, Keisuke Nakamura, Keiichi Sasaki, Hiroyo Ikai, Katsushi Kikuchi, Yoshimi Niwano
    Abstract:

    We have developed a new Disinfection System for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the System especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

  • Topical treatment of oral cavity and wounded skin with a new Disinfection System utilizing photolysis of hydrogen peroxide in rats
    The Journal of toxicological sciences, 2012
    Co-Authors: Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Eisei Hayashi, Yoshiko Kawana, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate the acute locally injurious property of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by a test device utilizing the photolysis of H(2)O(2) was confirmed by applying an electron spin resonance (ESR)-spin trapping technique. Secondly, the bactericidal effect of the device was examined under a simulant condition in which Staphylococcus aureus suspended in 1 M H(2)O(2) was irradiated with laser light emitted from the test device, resulting in substantial reduction of the colony forming unit of the bacteria within a short time as 2 min. Finally, acute topical effect of the Disinfection System on rat oral mucosa and wounded skin was evaluated by histological examination. No abnormal findings were observed in the buccal mucosal region treated three times with 1 M H(2)O(2) and irradiation. Similarly, no abnormal findings were observed during the healing of skin treated with 1 M H(2)O(2) and irradiation immediately after wounding. Since topical treatment with the novel Disinfection technique utilizing the photolysis of H(2)O(2) had no detrimental effect on the oral mucosa and the healing of full thickness skin wounds in rats, it is expected that the acute locally injurious property of the Disinfection technique is low.

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    Received 2 June 2010/Returned for modification 28 July 2010/Accepted 27 September 2010 The relationship between the amount of hydroxyl radicals generated by photolysis of H2O2 and bactericidal activity was examined. H2O2 (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions i n1MH 2O2 resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 M hydroxyl radicals would result in reductions of viable counts of >99.99%. Oral infectious diseases such as dental caries, periodontitis, and endodontic infections, all of which affect teeth and periodontal tissue, are caused by bacteria that inhabit the oral cavity. It is estimated that 150 or more different species of bacteria inhabit the human oral cavity (27). Of these bacteria,

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    The relationship between the amount of hydroxyl radicals generated by photolysis of H(2)O(2) and bactericidal activity was examined. H(2)O(2) (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions in 1 M H(2)O(2) resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 μM hydroxyl radicals would result in reductions of viable counts of >99.99%.

Keiichi Sasaki - One of the best experts on this subject based on the ideXlab platform.

  • In vitro and in vivo anti-Staphylococcus aureus activities of a new Disinfection System utilizing photolysis of hydrogen peroxide.
    Journal of bioscience and bioengineering, 2012
    Co-Authors: Eisei Hayashi, Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate in vitro and in vivo antibacterial activity of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of oral infection diseases such as periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by the photolysis of H(2)O(2) in which 1 mol l(-1) H(2)O(2) was irradiated with a dual wavelength-light emitting diode (LED) at wavelengths of 400 and 465 nm was confirmed by applying an electron spin resonance-spin trapping technique. Secondly, the bactericidal effect of the System was examined under a similar condition in which Staphylococcus aureus suspended in 1 mol l(-1) H(2)O(2) was irradiated with LED light, resulting in substantial reduction of the colony forming unit (CFU) of the bacteria within a short time as 2 min. Finally, in vivo antibacterial effect of the photolysis of H(2)O(2) on a rat model of S. aureus infection was evaluated by a culture study. Since a significant reduction of recovered CFU of S. aureus was obtained, it is expected that in vitro antibacterial effect attributable to hydroxyl radicals generated by photolysis of H(2)O(2) could be well reflected in in vivo superficial bacterial infection.

  • Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a Disinfection System utilizing photolysis of hydrogen peroxide
    Journal of clinical biochemistry and nutrition, 2012
    Co-Authors: Taro Kanno, Keisuke Nakamura, Keiichi Sasaki, Hiroyo Ikai, Katsushi Kikuchi, Yoshimi Niwano
    Abstract:

    We have developed a new Disinfection System for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the System especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

  • Topical treatment of oral cavity and wounded skin with a new Disinfection System utilizing photolysis of hydrogen peroxide in rats
    The Journal of toxicological sciences, 2012
    Co-Authors: Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Eisei Hayashi, Yoshiko Kawana, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate the acute locally injurious property of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by a test device utilizing the photolysis of H(2)O(2) was confirmed by applying an electron spin resonance (ESR)-spin trapping technique. Secondly, the bactericidal effect of the device was examined under a simulant condition in which Staphylococcus aureus suspended in 1 M H(2)O(2) was irradiated with laser light emitted from the test device, resulting in substantial reduction of the colony forming unit of the bacteria within a short time as 2 min. Finally, acute topical effect of the Disinfection System on rat oral mucosa and wounded skin was evaluated by histological examination. No abnormal findings were observed in the buccal mucosal region treated three times with 1 M H(2)O(2) and irradiation. Similarly, no abnormal findings were observed during the healing of skin treated with 1 M H(2)O(2) and irradiation immediately after wounding. Since topical treatment with the novel Disinfection technique utilizing the photolysis of H(2)O(2) had no detrimental effect on the oral mucosa and the healing of full thickness skin wounds in rats, it is expected that the acute locally injurious property of the Disinfection technique is low.

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    Received 2 June 2010/Returned for modification 28 July 2010/Accepted 27 September 2010 The relationship between the amount of hydroxyl radicals generated by photolysis of H2O2 and bactericidal activity was examined. H2O2 (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions i n1MH 2O2 resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 M hydroxyl radicals would result in reductions of viable counts of >99.99%. Oral infectious diseases such as dental caries, periodontitis, and endodontic infections, all of which affect teeth and periodontal tissue, are caused by bacteria that inhabit the oral cavity. It is estimated that 150 or more different species of bacteria inhabit the human oral cavity (27). Of these bacteria,

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    The relationship between the amount of hydroxyl radicals generated by photolysis of H(2)O(2) and bactericidal activity was examined. H(2)O(2) (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions in 1 M H(2)O(2) resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 μM hydroxyl radicals would result in reductions of viable counts of >99.99%.

Keisuke Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • In vitro and in vivo anti-Staphylococcus aureus activities of a new Disinfection System utilizing photolysis of hydrogen peroxide.
    Journal of bioscience and bioengineering, 2012
    Co-Authors: Eisei Hayashi, Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate in vitro and in vivo antibacterial activity of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of oral infection diseases such as periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by the photolysis of H(2)O(2) in which 1 mol l(-1) H(2)O(2) was irradiated with a dual wavelength-light emitting diode (LED) at wavelengths of 400 and 465 nm was confirmed by applying an electron spin resonance-spin trapping technique. Secondly, the bactericidal effect of the System was examined under a similar condition in which Staphylococcus aureus suspended in 1 mol l(-1) H(2)O(2) was irradiated with LED light, resulting in substantial reduction of the colony forming unit (CFU) of the bacteria within a short time as 2 min. Finally, in vivo antibacterial effect of the photolysis of H(2)O(2) on a rat model of S. aureus infection was evaluated by a culture study. Since a significant reduction of recovered CFU of S. aureus was obtained, it is expected that in vitro antibacterial effect attributable to hydroxyl radicals generated by photolysis of H(2)O(2) could be well reflected in in vivo superficial bacterial infection.

  • Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a Disinfection System utilizing photolysis of hydrogen peroxide
    Journal of clinical biochemistry and nutrition, 2012
    Co-Authors: Taro Kanno, Keisuke Nakamura, Keiichi Sasaki, Hiroyo Ikai, Katsushi Kikuchi, Yoshimi Niwano
    Abstract:

    We have developed a new Disinfection System for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the System especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

  • Topical treatment of oral cavity and wounded skin with a new Disinfection System utilizing photolysis of hydrogen peroxide in rats
    The Journal of toxicological sciences, 2012
    Co-Authors: Yasutomo Yamada, Takayuki Mokudai, Keisuke Nakamura, Eisei Hayashi, Yoshiko Kawana, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano
    Abstract:

    The present study aimed to evaluate the acute locally injurious property of hydroxyl radical generation System by photolysis of H(2)O(2), which is a new Disinfection System for the treatment of periodontitis developed in our laboratory. Firstly, generation of the hydroxyl radical by a test device utilizing the photolysis of H(2)O(2) was confirmed by applying an electron spin resonance (ESR)-spin trapping technique. Secondly, the bactericidal effect of the device was examined under a simulant condition in which Staphylococcus aureus suspended in 1 M H(2)O(2) was irradiated with laser light emitted from the test device, resulting in substantial reduction of the colony forming unit of the bacteria within a short time as 2 min. Finally, acute topical effect of the Disinfection System on rat oral mucosa and wounded skin was evaluated by histological examination. No abnormal findings were observed in the buccal mucosal region treated three times with 1 M H(2)O(2) and irradiation. Similarly, no abnormal findings were observed during the healing of skin treated with 1 M H(2)O(2) and irradiation immediately after wounding. Since topical treatment with the novel Disinfection technique utilizing the photolysis of H(2)O(2) had no detrimental effect on the oral mucosa and the healing of full thickness skin wounds in rats, it is expected that the acute locally injurious property of the Disinfection technique is low.

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    Received 2 June 2010/Returned for modification 28 July 2010/Accepted 27 September 2010 The relationship between the amount of hydroxyl radicals generated by photolysis of H2O2 and bactericidal activity was examined. H2O2 (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions i n1MH 2O2 resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 M hydroxyl radicals would result in reductions of viable counts of >99.99%. Oral infectious diseases such as dental caries, periodontitis, and endodontic infections, all of which affect teeth and periodontal tissue, are caused by bacteria that inhabit the oral cavity. It is estimated that 150 or more different species of bacteria inhabit the human oral cavity (27). Of these bacteria,

  • photolysis of hydrogen peroxide an effective Disinfection System via hydroxyl radical formation
    Antimicrobial Agents and Chemotherapy, 2010
    Co-Authors: Hiroyo Ikai, Keisuke Nakamura, Taro Kanno, Keiichi Sasaki, Yoshimi Niwano, Midori Shirato, Atsuo Iwasawa, Masahiro Kohno
    Abstract:

    The relationship between the amount of hydroxyl radicals generated by photolysis of H(2)O(2) and bactericidal activity was examined. H(2)O(2) (1 M) was irradiated with laser light at a wavelength of 405 nm to generate hydroxyl radicals. Electron spin resonance spin trapping analysis showed that the amount of hydroxyl radicals produced increased with the irradiation time. Four species of pathogenic oral bacteria, Staphylococcus aureus, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, and Enterococcus faecalis, were used in the bactericidal assay. S. mutans in a model biofilm was also examined. Laser irradiation of suspensions in 1 M H(2)O(2) resulted in a >99.99% reduction of the viable counts of each of the test species within 3 min of treatment. Treatment of S. mutans in a biofilm resulted in a >99.999% reduction of viable counts within 3 min. Other results demonstrated that the bactericidal activity was dependent on the amount of hydroxyl radicals generated. Treatment of bacteria with 200 to 300 μM hydroxyl radicals would result in reductions of viable counts of >99.99%.