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6. Incremental Ray Tracing

Author

Murakami, Koichi, Hirota, Katsuhiko, Hewitt, W. T., editor, Gnatz, R., editor, Duce, D. A., editor, Bouatouch, Kadi, editor, and Bouville, Christian, editor

Published
1992
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9. Outer membrane vesicles of Porphyromonas gingivalis: Novel communication tool and strategy

Author

Okamura, Hirohiko, Hirota, Katsuhiko, Yoshida, Kaya, Weng, Yao, He, Yuhan, Shiotsu, Noriko, Ikegame, Mika, Uchida-Fukuhara, Yoko, Tanai, Airi, Guo, Jiajie, Okamura, Hirohiko, Hirota, Katsuhiko, Yoshida, Kaya, Weng, Yao, He, Yuhan, Shiotsu, Noriko, Ikegame, Mika, Uchida-Fukuhara, Yoko, Tanai, Airi, and Guo, Jiajie

Abstract

Extracellular vesicles (EVs) have been recognized as a universal method of cellular communications and are reportedly produced in bacteria, archaea, and eukaryotes. Bacterial EVs are often called "Outer Membrane Vesicles" (OMVs) as they were the result of a controlled blebbing of the outer membrane of gram-negative bacteria such as Porphyromonas gingivalis (P. gingivalis). Bacterial EVs are natural messengers, implicated in intra-and inter-species cell-to-cell communication among microorganism populations present in microbiota. Bacteria can incorporate their pathogens into OMVs; the content of OMVs differs, depending on the type of bacteria. The production of distinct types of OMVs can be mediated by different factors and routes. A recent study highlighted OMVs ability to carry crucial molecules implicated in immune modulation, and, nowadays, they are considered as a way to communicate and transfer messages from the bacteria to the host and vice versa. This review article focuses on the current understanding of OMVs produced from major oral bacteria, P. gingivalis: generation, characteristics, and contents as well as the involvement in signal transduction of host cells and systemic diseases. Our recent study regarding the action of P. gingivalis OMVs in the living body is also summarized.

Published
2021

15. ロイテリン関連化合物の歯周病原因菌への抗菌および抗バイオフィルム効果

Author

Fujiwara, Natsumi, Murakami, Keiji, Nakao, Michiyasu, Toguchi, Munehisa, Yumoto, Hiromichi, Hirota, Katsuhiko, Matsuo, Takashi, Sano, Shigeki, Ozaki, Kazumi, and Miyake, Yoichiro

Subjects
Fusobacterium nucleatum, Lactobacillus reuteri, reuterin, biofilm
Abstract

OBJECTIVE: Lactobacillus reuteri is one of the probiotics that possesses preventive effects on oral infections including dental caries and periodontal disease. Reuterin is a bacteriocin-like compound produced by L. reuteri and plays an important role in the probiotic effects. However, it is difficult to obtain reuterin due to the general lability of its aldehyde moiety. Therefore, fourteen stable reuterin-related compounds (RRCs) were chemically synthesized. Here, we investigated the effects of RRCs on periodontopathic bacteria. MATERIALS AND METHODS: The antibacterial activity of RRCs on pathogenic microorganisms including periodontopathic bacteria was determined. Moreover, the effects of RRCs on biofilm formation by Fusobacterium nucleatum were examined by a crystal violet biofilm formation assay. Cytotoxicity of RRCs was evaluated by a lactate dehydrogenase assay using oral keratinocytes. RESULTS: Among synthesized RRCs, RRC-04, -05, -09, -10, -12, -13, and -14, exhibited antibacterial activities against periodontopathic bacteria. RRCs, except for RRC-06, -07, -08, and -11, significantly suppressed biofilm formation to 60-80 % of the control. Most RRCs, except for RRC-12 and -13, were not cytotoxic to human oral keratinocytes. CONCLUSIONS: The synthesized RRCs can be potent novel oral care products for the prevention of periodontitis without adverse effects.

Published
2017

17. The Pathogenic Factors from Oral Streptococci for Systemic Diseases

Author

Yumoto, Hiromichi, Hirota, Katsuhiko, Hirao, Kouji, Ninomiya, Masami, Murakami, Keiji, Fujii, Hideki, Miyake, Yoichiro, Yumoto, Hiromichi, Hirota, Katsuhiko, Hirao, Kouji, Ninomiya, Masami, Murakami, Keiji, Fujii, Hideki, and Miyake, Yoichiro

Abstract

The oral cavity is suggested as the reservoir of bacterial infection, and the oral and pharyngeal biofilms formed by oral bacterial flora, which is comprised of over 700 microbial species, have been found to be associated with systemic conditions. Almost all oral microorganisms are non-pathogenic opportunistic commensals to maintain oral health condition and defend against pathogenic microorganisms. However, oral Streptococci, the first microorganisms to colonize oral surfaces and the dominant microorganisms in the human mouth, has recently gained attention as the pathogens of various systemic diseases, such as infective endocarditis, purulent infections, brain hemorrhage, intestinal inflammation, and autoimmune diseases, as well as bacteremia. As pathogenic factors from oral Streptococci, extracellular polymeric substances, toxins, proteins and nucleic acids as well as vesicles, which secrete these components outside of bacterial cells in biofilm, have been reported. Therefore, it is necessary to consider that the relevance of these pathogenic factors to systemic diseases and also vaccine candidates to protect infectious diseases caused by Streptococci. This review article focuses on the mechanistic links among pathogenic factors from oral Streptococci, inflammation, and systemic diseases to provide the current understanding of oral biofilm infections based on biofilm and widespread systemic diseases.

Published
2019

21. 2-Methacryloyloxyethyl phosphorylcholine (MPC)-polymer suppresses an increase of oral bacteria: a single-blind, crossover clinical trial

Author

Fujiwara, Natsumi, Yumoto, Hiromichi, Miyamoto, Koji, Hirota, Katsuhiko, Nakae, Hiromi, Tanaka, Saya, Murakami, Keiji, Kudo, Yasusei, Ozaki, Kazumi, Miyake, Yoichiro, Fujiwara, Natsumi, Yumoto, Hiromichi, Miyamoto, Koji, Hirota, Katsuhiko, Nakae, Hiromi, Tanaka, Saya, Murakami, Keiji, Kudo, Yasusei, Ozaki, Kazumi, and Miyake, Yoichiro

Abstract

Objectives The biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymers, which mimic a biomembrane, reduce protein adsorption and bacterial adhesion and inhibit cell attachment. The aim of this study is to clarify whether MPC-polymer can suppress the bacterial adherence in oral cavity by a crossover design. We also investigated the number of Fusobacterium nucleatum, which is the key bacterium forming dental plaque, in clinical samples. Materials and methods This study was a randomized, placebo-controlled, single-blind, crossover study, with two treatment periods separated by a 2-week washout period. We conducted clinical trial with 20 healthy subjects to evaluate the effect of 5% MPC-polymer mouthwash after 5 h on oral microflora. PBS was used as a control. The bacterial number in the gargling sample before and after intervention was counted by an electronic bacterial counter and a culture method. DNA amounts of total bacteria and F. nucleatum were examined by q-PCR. Results The numbers of total bacteria and oral streptcocci after 5 h of 5% MPC-polymer treatment significantly decreased, compared to the control group. Moreover, the DNA amounts of total bacteria and F. nucleatum significantly decreased by 5% MPC-polymer mouthwash. Conclusions We suggest that MPC-polymer coating in the oral cavity may suppress the oral bacterial adherence. Clinical relevance MPC-polymer can be a potent compound for the control of oral microflora to prevent oral infection.

Published
2018

23. Effect of eDNA on biofilm formation

Author

Asikin, Nur, Hirota, Katsuhiko, Yumoto, Hiromichi, Hirao, Kouji, Liu, Dali, Takahashi, Kanako, Murakami, Keiji, Matsuo, Takashi, Shu, Rong, and Miyake, Yoichiro

Subjects
biofilm development, extracellular HLP, Streptococcus intermedius, biochemical phenomena, metabolism, and nutrition, DNA concentration, extracellular DNA
Abstract

Aims: The aim of this study was to clarify the effects of homologous and heterologous extracellular DNAs (eDNAs) and histone-like DNA binding protein (HLP) on Streptococcus intermedius biofilm development and rigidity. Methods and Results: Formed biofilm mass was measured with 0.1% crystal violet staining method and observed with a scanning electron microscope. The localizations of eDNA and extracellular HLP (eHLP) in formed biofilm were detected by staining with 7-hydoxyl-9H-(1,3-dichloro-9,9-dimethylacridin-2-one) and anti-HLP antibody without fixation, respectively. DNase I treatment (200 U ml-1) markedly decreased biofilm formation and cell density in biofilms. Co-localization of eHLP and eDNA in biofilm was confirmed. The addition of eDNA (up to 1 μg ml-1) purified from S. intermedius, other Gram-positive, –negative bacteria, or human KB cells into the S. intermedius culture increased the biofilm mass of all tested strains of S. intermedius, wild-type, HLP down-regulated strain, and control strains. In contrast, the addition of eDNA (> 1 μg ml-1) decreased the biofilm mass of all S. intermedius strains. Conclusions: These findings demonstrated that eDNA and eHLP play crucial roles in biofilm development and its rigidity. Significance and Impact of the Study: eDNA- and HLP-targeting strategies may be applicable to novel treatments for bacterial biofilm-related infectious diseases.

Published
2013

31. Relationships between activity of daily living, and oral cavity care and the number of oral cavity microorganisms in patients with cerebrovascular diseases

Author

Michishige, Fumiko, Yoshinaga, Sumiko, Harada, Eriko, Hirota, Katsuhiko, Miyake, Yoichiro, Matsuo, Takashi, and Yasuoka, Susumu

Subjects
pharyngeal swab, aspiration pneumonia, oral cavity care, bacteria, cerebrovascular disease
Abstract

We examined the relationships among the activity of daily living (ADL), oral cavity care, and the number of oral cavity microorganisms in 40patients with cerebro-vascular diseases (CVD). The CVD patients were classified into 4groups, I, II, III and IV based on their ADL and the method used for oral cavity care. The ADL was highest in group I and lowest in group III. Only the patients of only group III could not eat by themselves and were receiving naso-esophageal feeding. Oral cavity care was performed by the patients themselves in groups I and IV, but was performed by caregivers in groups II and III. The group IV patients had no teeth, but could eat by themselves using full dentures. The numbers of microorganisms in the pharyngeal swabs from the 4groups were measured and expressed as colony-forming units (cfu). The numbers of both Staphylococci spp. and Candida spp. were significantly higher in group III than in the other groups. Moreover, Pseudomonas aeruginosa was isolated only from patients of group III (in about 66%). The oral cavity care by caregivers was almost the same in groups II and III, but the numbers of oral cavity microorganisms were significantly higher in group III than in group II. These results indicated that microorganisms grow more easily in the oral cavities of CVD patients with low ADL compared with CVD patients with higher ADL, and that eating is thought to be important for the prevention of an increase of microorganisms in the oral cavity.

Published
1999

33. Royal Jelly Inhibits Pseudomonas aeruginosa Adherence and Reduces Excessive Inflammatory Responses in Human Epithelial Cells.

Author

Susilowati, Heni, Murakami, Keiji, Yumoto, Hiromichi, Amoh, Takashi, Hirao, Kouji, Hirota, Katsuhiko, Matsuo, Takashi, and Miyake, Yoichiro

Subjects
THERAPEUTIC use of honey, RESPIRATORY infections, PSEUDOMONAS disease treatment, ANTIBIOTICS, TISSUE adhesions, ANALYSIS of variance, BIOLOGICAL assay, EPITHELIAL cells, GRAM-negative bacteria, INFLAMMATION, INTERLEUKINS, MACROPHAGES, NUTRITIONAL requirements, PSEUDOMONAS diseases, RESEARCH funding, STATISTICS, DATA analysis, DATA analysis software, PREVENTION
Abstract

Pseudomonas aeruginosa is a Gram-negative bacterium and causes respiratory infection especially in elderly patients. Royal jelly has been used worldwide as a traditional remedy and as a nutrient; however, the effect against P. aeruginosa is unclear. The aim of this study was to analyze antibacterial, antiadherent, and anti-inflammatory effects of royal jelly against P. aeruginosa. Wild-type strain PAO1 and clinical isolates of P. aeruginosa were used for antibacterial assay and antiadherent assay to abiotic surface and epithelial cells, which are pharynx (Detroit 562) and lung (NCI-H292) epithelial cells. In anti-inflammatory assay, epithelial cells were pretreated with royal jelly before bacterial exposure to investigate its inhibitory effect on interleukin (IL-8) and macrophage inflammatory protein-3α/CCL20 overproduction. Although royal jelly did not have antibacterial activity at concentration of 50% w/v, antiadherent activity was confirmed on the abiotic surface and epithelial cells under concentration of 25%. Pretreatment with royal jelly significantly inhibited overproduction of IL-8 and CCL20 from both cells. These results demonstrated that royal jelly inhibits P. aeruginosa adherence and protects epithelial cells from excessive inflammatory responses against P. aeruginosa infection. Our findings suggested that royal jelly may be a useful supplement as complementary and alternative medicine for preventing respiratory infection caused by P. aeruginosa. [ABSTRACT FROM AUTHOR]

Published
2017
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34. Effects of an autoinducer analogue on antibiotic tolerance in Pseudomonas aeruginosa.

Author

Takashi Amoh, Keiji Murakami, Reiko Kariyama, Kenji Hori, Darija Viducic, Katsuhiko Hirota, Jun Igarashi, Hiroaki Suga, Parsek, Matthew R., Hiromi Kumon, Yoichiro Miyake, Amoh, Takashi, Murakami, Keiji, Kariyama, Reiko, Hori, Kenji, Viducic, Darija, Hirota, Katsuhiko, Igarashi, Jun, Suga, Hiroaki, and Kumon, Hiromi

Subjects
MULTIDRUG tolerance (Microbiology), PSEUDOMONAS aeruginosa, ANTIBIOTICS, MICROBIAL metabolites, INFECTION, BIOFILMS, ANIMAL experimentation, DRUG tolerance, MICE, MICROBIAL sensitivity tests, PSEUDOMONAS, RESEARCH funding, PHARMACODYNAMICS
Abstract

Objectives: Antibiotic tolerance causes chronic, refractory and persistent infections. In order to advance the development of a new type of drug for the treatment of infectious diseases, we herein investigated the effects of a newly synthesized analogue of the Pseudomonas aeruginosa quorum-sensing autoinducer named AIA-1 ( a uto i nducer a nalogue) on antibiotic tolerance in P. aeruginosa .Methods: A P. aeruginosa luminescent strain derived from PAO1 was injected into neutropenic ICR mice and bioluminescence images were acquired for a period of time after treatments with antibiotics and AIA-1. In vitro susceptibility testing and killing assays for the planktonic and biofilm cells of PAO1 were performed using antibiotics and AIA-1. The expression of quorum-sensing-related genes was examined using real-time PCR.Results: In vivo and in vitro assays showed that AIA-1 alone did not exert any bactericidal effects and also did not affect the MICs of antibiotics. However, the combined use of AIA-1 and antibiotics exerted markedly stronger therapeutic effects against experimental infection than antibiotics alone. The presence of AIA-1 also enhanced the killing effects of antibiotics in planktonic and biofilm cells. Although AIA-1 did not inhibit the expression of lasB and rhlA genes, which are directly regulated by quorum sensing, it clearly suppressed expression of the rpoS gene.Conclusions: The new compound, AIA-1, did not alter the antibiotic susceptibility of P. aeruginosa by itself; however, its addition enhanced the antibacterial activity of antibiotics. AIA-1 did not inhibit quorum sensing, but reduced the antibiotic tolerance of P. aeruginosa by suppressing rpoS gene expression. [ABSTRACT FROM AUTHOR]

Published
2017
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41. Heterologous expression of a histone-like protein fromStreptococcus intermediusinEscherichia colialters the nucleoid structure and inhibits the growth ofE. coli

Author

Liu, Dali, primary, Yumoto, Hiromichi, additional, Murakami, Keiji, additional, Hirota, Katsuhiko, additional, Kayama, Shizuo, additional, Taniguchi, Tomonori, additional, Yamamoto, Akitake, additional, Ono, Tsuneko, additional, Matsuo, Takashi, additional, and Miyake, Yoichiro, additional

Published
2008
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43. Histone-like DNA binding protein of Streptococcus intermedius induces the expression of pro-inflammatory cytokines in human monocytes via activation of ERK1/2 and JNK pathways

Author

Liu, Dali, primary, Yumoto, Hiromichi, additional, Hirota, Katsuhiko, additional, Murakami, Keiji, additional, Takahashi, Kanako, additional, Hirao, Kouji, additional, Matsuo, Takashi, additional, Ohkura, Kazuto, additional, Nagamune, Hideaki, additional, and Miyake, Yoichiro, additional

Published
2007
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46. Anti-inflammatory and protective effects of 2-methacryloyloxyethyl phosphorylcholine polymer on oral epithelial cells.

Author

Yumoto, Hiromichi, Hirota, Katsuhiko, Hirao, Kouji, Miyazaki, Tsuyoshi, Yamamoto, Nobuyuki, Miyamoto, Koji, Murakami, Keiji, Fujiwara, Natsumi, Matsuo, Takashi, and Miyake, Yoichiro

Abstract

Periodontitis is a chronic inflammatory disease initiated by a microbial biofilm formed in the periodontal pocket. Gingival epithelium plays important roles as the first physical barrier to bacterial invasion and in orchestrating the innate immune reaction via toll-like receptors (TLRs), which recognize various bacterial products, and maintaining its function. Newly developed oral care products to inhibit bacterial adherence, subsequent inflammatory reaction and protect the gingival epithelium are expected. We previously reported that 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer coating decreased bacterial adhesion to human oral keratinocytes, RT-7, and mouth-rinsing with MPC-polymer inhibited the increase of oral bacteria. In this study, regarding the possibility of MPC-polymer application for preventing the adherence of periodontal pathogen, subsequent inflammatory reaction and protection of gingival epithelium, we examined the effects of MPC-polymer on the adherence of Porphyromonas gingivalis, major periodontitis-related pathogen, and TLR2 ligand to RT-7 and subsequent interleukin (IL)−8 production. MPC-polymer treatment significantly reduced P. gingivalis adherence by 44% and TLR2-mediated IL-8 production by blocking the binding of its specific-ligand in a concentration-dependent manner. Furthermore, MPC-polymer pretreatment protected RT-7 from injury by chemical irritants, cetylpyridinium chloride. These findings suggest that MPC-polymer is potentially useful for oral care to prevent oral infection and to maintain oral epithelial function. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 555-563, 2015. [ABSTRACT FROM AUTHOR]

Published
2015
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