論文 - 大久保　圭祐

Bacterial DNA and serum IgG antibody titer assays for assessing infection of human-pathogenic and dog-pathogenic Porphyromonas species in dogs 査読

Masako Tai-Tokuzen, Takashi Ito, Kazuya Tamura, Haruko Hirayama, Hirohito Ogawa, Shin Nakamura, Keisuke Okubo, Kazuhiro Omori, Tadashi Yamamoto, Katsumi Mominoki, Shogo Takashiba

Heliyon   10 ( 11 )   e31872 - e31872   2024年6月

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.heliyon.2024.e31872

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Analysis of subgingival microbiota in monozygotic twins with different severity and progression risk of periodontitis. 査読 国際誌

Tadashi Yamamoto, Makoto Taniguchi, Kazuyuki Matsunaga, Yusuke Kawata, Mari Kawamura, Keisuke Okubo, Keisuke Yamashiro, Kazuhiro Omori, Shogo Takashiba

Clinical case reports   10 ( 4 )   e05725   2022年4月

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記述言語：英語  

The study aims to reveal the composition of subgingival bacteria in monozygotic twins with discordant in severity and progression risk of periodontitis. Microbiome analysis indicated that most bacteria were heritable but differed in their abundance and immune response. The dysbiotic bacteria can be considered as risk markers for periodontitis progression.

DOI： 10.1002/ccr3.5725

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Dual-Function Semaphorin 4D Released by Platelets: Suppression of Osteoblastogenesis and Promotion of Osteoclastogenesis. 査読 国際誌

Satoru Shindo, Irma Josefina Savitri, Takenobu Ishii, Atsushi Ikeda, Roodelyne Pierrelus, Alireza Heidari, Keisuke Okubo, Shin Nakamura, Umadevi Kandalam, Mohamad Rawas-Qalaji, Elizabeth Leon, Maria Rita Pastore, Patrick Hardigan, Toshihisa Kawai

International journal of molecular sciences   23 ( 6 )   2022年3月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Effects of the antiosteoblastogenesis factor Semaphorin 4D (Sema4D), expressed by thrombin-activated platelets (TPs), on osteoblastogenesis, as well as osteoclastogenesis, were investigated in vitro. Intact platelets released both Sema4D and IGF-1. However, in response to stimulation with thrombin, platelets upregulated the release of Sema4D, but not IGF-1. Anti-Sema4D-neutralizing monoclonal antibody (mAb) upregulated TP-mediated osteoblastogenesis in MC3T3-E1 osteoblast precursors. MC3T3-E1 cells exposed to TPs induced phosphorylation of Akt and ERK further upregulated by the addition of anti-sema4D-mAb, suggesting the suppressive effects of TP-expressing Sema4D on osteoblastogenesis. On the other hand, TPs promoted RANKL-mediated osteoclastogenesis in the primary culture of bone-marrow-derived mononuclear cells (BMMCs). Among the known three receptors of Sema4D, including Plexin B1, Plexin B2 and CD72, little Plexin B2 was detected, and no Plexin B1 was detected, but a high level of CD72 mRNA was detected in RANKL-stimulated BMMCs by qPCR. Both anti-Sema4D-mAb and anti-CD72-mAb suppressed RANKL-induced osteoclast formation and bone resorptive activity, suggesting that Sema4D released by TPs promotes osteoclastogenesis via ligation to a CD72 receptor. This study demonstrated that Sema4D released by TPs suppresses osteogenic activity and promotes osteoclastogenesis, suggesting the novel property of platelets in bone-remodeling processes.

DOI： 10.3390/ijms23062938

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Evaluation of the simulator with automatic irrigation control system designed for countermeasures of internal contamination in dental unit water lines. 査読 国際誌

Keisuke Okubo, Takashi Ito, Kentaro Okamoto, Ichiro Yamamoto, Hajime Mizutani, Yusuke Kawata, Yasuyoshi Shiota, Masahiro Ito, Shin Nakamura, Masako Tai, Tadashi Yamamoto, Shogo Takashiba

Heliyon   6 ( 6 )   e04132   2020年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

UNLABELLED: The prevention of nosocomial infections is an imperative task. The dental chair unit (DCU) is an indispensable device used in dental treatment. However, it is known that the dental unit water line (DUWL) can become contaminated with biofilm, consisting mainly of heterotrophic bacteria (HB). Recently, the International Organization for Standardization specified the methods for testing DUWL contamination management. On these grounds, a simulator reproducing DUWL was prepared to standardize the examination method of the DUWL contamination. OBJECTIVES: To evaluate the reproducibility of the DUWL simulator, monitor the DUWL contamination states, and test the efficacy of a commercial decontaminant for DUWL. METHODS: The DUWL simulator was assembled by a DCU manufacturing company. The simulator's DUWL was filled with tap water (TW), and left for approximately one year. Neutral electrolyzed water (NEW) was used as a decontaminant for DUWL. Both TW and NEW were passed through DUWL in a timely manner simulating daily dental treatment. Water was sampled from the air turbine hand piece weekly for 4 weeks and used for HB culture. Contamination status was evaluated by measuring bacterial adenosine triphosphate release and by culturing on Reasoner's 2A medium. RESULTS: The DUWL released contaminated water had a bacterial count of over 6 × 104 cfu/mL. After passing NEW through DUWL for 1 week, the count drastically decreased to its basal level and remained steady for 4 weeks. However, TW showed no effect on DUWL decontamination throughout the examination periods. CONCLUSIONS: The DUWL simulator could be useful to examine the efficacy of the decontaminant for DUWL and development of new methods in DUWL contamination management.

DOI： 10.1016/j.heliyon.2020.e04132

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Tailoring the interaction between graphene oxide and antibacterial pyridinium salts by terminal functional groups 査読

R. Fujii, K. Okubo, S. Takashiba, A. Bianco, Y. Nishina

Carbon   160   204 - 210   2020年4月

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掲載種別：研究論文（学術雑誌）  

Nanocarbons, especially two-dimensional carbons, have received considerable attention due to their unique structure and physical and chemical properties, which make them promising candidate materials for biomedical applications. In this study, we focus on graphene oxide (GO), which has many oxygenated functional groups and high affinity with water and biomaterials, and the synthesis of GO complexes with antibacterial agents, like cetylpyridinium chloride (CPC) and its derivatives. We found that the sustained release of CPCs from GO can be controlled by changing the terminal functional group of CPC. The prepared GO-CPC complexes were subjected to antibacterial tests against S. mutans. CPC with the carboxy group was degraded by the oxidizing property of GO, resulting in the loss of antibacterial properties. On the other hand, the other CPC derivatives were released from GO and showed antibacterial activities. Finally, we propose a new mechanism describing how GO and CPC form a functional complex, and how CPC is released from this complex. These findings will lead to pioneering the carbon-based functional antibacterial agents designed at the molecular level.

DOI： 10.1016/j.carbon.2019.11.094

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Acceleration of bone regeneration of horizontal bone defect in rats using collagen-binding basic fibroblast growth factor combined with collagen scaffolds. 査読 国際誌

Shin Nakamura, Takashi Ito, Kentaro Okamoto, Takehiko Mima, Kentaro Uchida, Yasir D Siddiqui, Masahiro Ito, Masako Tai, Keisuke Okubo, Keisuke Yamashiro, Kazuhiro Omori, Tadashi Yamamoto, Osamu Matsushita, Shogo Takashiba

Journal of periodontology   90 ( 9 )   1043 - 1052   2019年9月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Basic fibroblast growth factor (bFGF) has been applied for periodontal regeneration. However, the application depends on bone defect morphology because bFGF diffuses rapidly from defect sites. In a previous study, collagen-binding bFGF (CB-bFGF) has been shown to enhance bone formation by collagen-anchoring in the orthopedic field. The aim of this study is to demonstrate the efficacy of CB-bFGF with collagen scaffolds in bone regeneration of horizontal bone defect. METHODS: Cell proliferation activity and collagen binding activity of CB-bFGF was confirmed by WST-8 assay and collagen binding assay, respectively. The retention of CB-bFGF in the collagen sheet (CS) was measured by fluorescence imaging. The rat horizontal alveolar bone defect model was employed to investigate the efficacy of CB-bFGF with collagen powder (CP). After 4 and 8 weeks, the regenerative efficacy was evaluated by microcomputed tomography, histological, and immunohistochemical analyses. RESULTS: CB-bFGF had a comparable proliferation activity to bFGF and a collagen binding activity. CB-bFGF was retained in CS longer than bFGF. At 8 weeks postoperation, bone volume, bone mineral content, and new bone area in CB-bFGF/CP group were significantly increased compared with those in other groups. Furthermore, epithelial downgrowth was significantly suppressed in CB-bFGF/CP group. At 4 weeks, the numbers of osteocalcin, proliferating cell nuclear antigen, and osteopontin-positive cells at the regeneration site in CB-bFGF/CP group were greater than those in other groups. CONCLUSIONS: CB-bFGF/CP effectively promoted bone regeneration of horizontal bone defect possibly by sustained release of bFGF. The potential of CB-bFGF composite material for improved periodontal regeneration in vertical axis was shown.

DOI： 10.1002/JPER.18-0674

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Effectiveness and safety of low-concentrated ozonized water for the reduction of contamination in dental unit water lines. 査読 国際誌

Keisuke Okubo, Takashi Ito, Yasuyoshi Shiota, Yusuke Kawata, Tadashi Yamamoto, Shogo Takashiba

Heliyon   5 ( 8 )   e02306   2019年8月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

UNLABELLED: Contamination of dental unit waterlines (DUWL) with heterotrophic bacteria can cause problems in immune compromised patients (aged, tumor and organ transplantation-patients). We focused on the use of low-concentrated ozonized water (OZW) as the biofilm formation restraint system for DUWL. Here, we examined the effects of low-concentrated OZW on the growth of bacteria and related biofilm formation and harmfulness to dental unit components (DUCs) in vitro. OBJECTIVES: To evaluate the bactericidal effects of OZW on biofilms in DUWL and DUC in vitro. METHODS: Low-concentrated OZW (0.4 mg/L) was generated using an OZS-PTDX generator. Heterotrophic bacterial biofilms in old DUWL tubes and Candia albicans solution (control microbe) were treated with OZW for 1 h with gentle agitation before static culturing for 96 h in Reasoner's 2A liquid media. The control solutions were 0.1% cetylpyridinium chloride (CPC), chlorinated tap water (TW), and phosphate-buffered saline (PBS). Adenosine triphosphate (ATP) amounts of the microbes were measured and the biofilms of these microbes were observed using scanning electron microscopy (SEM). Moreover, surfaces of DUC soaked in OZW and TW were observed by SEM. RESULTS: The OZW reduced ATP levels in microbes to 50% compared to TW and PBS treatment, although CPC reduced it below detection limits. SEM observation revealed deformation of microbes cultured with OZW, whereas no changes were seen on DUC surfaces. CONCLUSIONS: Low-concentrated OZW is bactericidal against heterotrophic bacteria biofilms and it is not harmful to DUC, suggesting that it might be useful in preventing DUWL contamination.

DOI： 10.1016/j.heliyon.2019.e02306

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