著者
Hidekazu Nishimura Michiko Okamoto Isolde Dapat Masanori Katumi Hitoshi Oshitani
出版者
National Institute of Infectious Diseases, Japanese Journal of Infectious Diseases Editorial Committee
雑誌
Japanese Journal of Infectious Diseases (ISSN:13446304)
巻号頁・発行日
pp.JJID.2020.902, (Released:2021-01-29)
参考文献数
8
被引用文献数
25

Green tea extracts effectively inactivated SARS-CoV-2 in vitro in a dose-dependent manner. Serially 10-fold diluted solutions of catechin mixture reagent from green tea were mixed with the viral culture fluid at a volume ratio of nine to one, respectively, and kept at room temperature for 5 min. The solution of 10 mg/mL catechin reagent reduced the viral titer by 4.2 log and 1.0 mg/mL solution reduced only by one log. Pre-infection treatment of the cells with the reagent alone did not affect the viral growth. In addition, cells treated with only the reagent was assayed for host-cell viability using the WST-8 system and almost no host-cell damage by the treatment was observed. These findings suggested that the direct treatment of virus with the reagent before inoculation decreased the viral activity and that catechins might have a potential to suppress the SARS-CoV-2 infection.
著者
Jun Watanabe Yoko Iwamatsu-kobayashi Kenji Kikuchi Tomonari Kajita Hiromitsu Morishima Kensuke Yamauchi Wataru Yashiro Hidekazu Nishimura Hiroyasu Kanetaka Hiroshi Egusa
出版者
Japan Prosthodontic Society
雑誌
Journal of Prosthodontic Research (ISSN:18831958)
巻号頁・発行日
pp.JPR_D_23_00013, (Released:2023-02-22)
参考文献数
52
被引用文献数
3

Purpose: The hazards of aerosols generated during dental treatments are poorly understood. This study aimed to establish visualization methods, discover conditions for droplets/aerosols generated in simulating dental treatments and identify the conditions for effective suction methods.Methods: The spreading area was evaluated via image analysis of the droplets/aerosols generated by a dental air turbine on a mannequin using a light emitting diode (LED) light source and high-speed camera. The effects of different bur types and treatment sites, reduction effect of intra-oral suction (IOS) and extra-oral suction (EOS) devices, and effect of EOS installation conditions were evaluated.Results: Regarding the bur types, a bud-shaped bur on the air turbine generated the most droplets/aerosols compared with round-shaped, round end-tapered, or needle-tapered burs. Regarding the treatment site, the area of droplets/aerosols produced by an air turbine from the palatal plane of the anterior maxillary teeth was significantly higher. The generated droplet/aerosol area was reduced by 92.1% by using IOS alone and 97.8% by combining IOS and EOS. EOS most effectively aspirated droplets/aerosols when placed close (10 cm) to the mouth in the vertical direction (0°).Conclusions: The droplets/aerosols generated by an air turbine could be visualized using an LED light and a high-speed camera in simulating dental treatments. The bur shape and position of the dental air turbine considerably influenced droplet/aerosol diffusion. The combined use of IOS and EOS at a proper position (close and perpendicular to the mouth) facilitated effective diffusion prevention to protect the dental-care environment.
著者
Hidekazu Nishimura Michiko Okamoto Isolde Dapat Masanori Katsumi Hitoshi Oshitani
出版者
National Institute of Infectious Diseases, Japanese Journal of Infectious Diseases Editorial Committee
雑誌
Japanese Journal of Infectious Diseases (ISSN:13446304)
巻号頁・発行日
vol.74, no.5, pp.421-423, 2021-09-30 (Released:2021-09-22)
参考文献数
8
被引用文献数
1 25

Green tea extracts effectively inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro in a dose-dependent manner. Ten-fold serially diluted solutions of catechin mixture reagent from green tea were mixed with the viral culture fluid at a volume ratio of 9:1, respectively, and incubated at room temperature for 5 min. The solution of 10 mg/mL catechin reagent reduced the viral titer by 4.2 log and 1.0 mg/mL solution by one log. Pre-infection treatment of cells with the reagent alone did not affect viral growth. In addition, cells treated with only the reagent were assayed for host cell viability using the WST-8 system, and almost no host cell damage by the treatment was observed. These findings suggested that the direct treatment of virus with the reagent before inoculation decreased the viral activity and that catechins might have the potential to suppress SARSCoV-2 infection.
著者
Hidekazu Nishimura Mutsuo Yamaya
出版者
Tohoku University Medical Press
雑誌
The Tohoku Journal of Experimental Medicine (ISSN:00408727)
巻号頁・発行日
vol.237, no.1, pp.45-50, 2015 (Released:2015-09-03)
参考文献数
30
被引用文献数
11 20

Ebola virus disease (EVD) has been a great concern worldwide because of its high mortality. EVD usually manifests with fever, diarrhea and vomiting, as well as disseminated intravascular coagulation (DIC). To date, there is neither a licensed Ebola vaccine nor a promising therapeutic agent, although clinical trials are ongoing. For replication inside the cell, Ebola virus (EBOV) must undergo the proteolytic processing of its surface glycoprotein in the endosome by proteases including cathepsin B (CatB), followed by the fusion of the viral membrane and host endosome. Thus, the proteases have been considered as potential targets for drugs against EVD. However, no protease inhibitor has been presented as effective clinical drug against it. A synthetic serine protease inhibitor, nafamostat mesilate (NM), reduced the release of CatB from the rat pancreas. Furthermore, it has anticoagulant activities, such as inhibition of the factor VIIa complex, and has been used for treating DIC in Japan. Thus, NM could be considered as a drug candidate for the treatment of DIC induced by EBOV infection, as well as for the possible CatB-related antiviral action. Moreover, the drug has a history of large-scale production and clinical use, and the issues of safety and logistics might have been cleared. We advocate in vitro and in vivo experiments using active EBOV to examine the activities of NM against the infection and the DIC induced by the infection. In addition, we suggest trials for comparison among anti-DIC drugs including the NM in EVD patients, in parallel with the experiments.
著者
Mutsuo Yamaya Hidekazu Nishimura Xue Deng Akiko Kikuchi Ryoichi Nagatomi
出版者
Tohoku University Medical Press
雑誌
The Tohoku Journal of Experimental Medicine (ISSN:00408727)
巻号頁・発行日
vol.251, no.1, pp.27-30, 2020 (Released:2020-05-22)
参考文献数
24
被引用文献数
13

The number of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly increased, although the WHO declared a pandemic. However, drugs that function against SARS-CoV-2 have not been established. SARS-CoV-2 has been suggested to bind angiotensin-converting enzyme 2, the receptor of the SARS coronavirus. SARS coronavirus and coronavirus 229E, the cause of the common cold, replicate through cell-surface and endosomal pathways using a protease, the type II transmembrane protease. To examine the effects of protease inhibitors on the replication of coronavirus 229E, we pretreated primary cultures of human nasal epithelial (HNE) cells with camostat or nafamostat, each of which has been used for the treatment of pancreatitis and/or disseminated intravascular coagulation. HNE cells were then infected with coronavirus 229E, and viral titers in the airway surface liquid of the cells were examined. Pretreatment with camostat (0.1-10 μg/mL) or nafamostat (0.01-1 μg/mL) reduced the titers of coronavirus 229E. Furthermore, a significant amount of type II transmembrane protease protein was detected in the airway surface liquid of HNE cells. Additionally, interferons have been reported to have antiviral effects against SARS coronavirus. The additive effects of interferons on the inhibitory effects of other candidate drugs to treat SARS-CoV-2 infection, such as lopinavir, ritonavir and favipiravir, have also been studied. These findings suggest that protease inhibitors of this type may inhibit coronavirus 229E replication in human airway epithelial cells at clinical concentrations. Protease inhibitors, interferons or the combination of these drugs may become candidate drugs to inhibit the replication of SARS-CoV-2.