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Publications (6)8.27 Total impact

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    ABSTRACT: Streptococcus mutans possesses a number of ATP-binding cassette (ABC) transporters, which function as multiple sugar metabolism transporters and are promising targets for antimicrobial strategies. In the present study, we performed functional analyses of SMu0836 and SMu0837 products, which are possible ABC transporters. Isogenic mutant strains Δ0836 and Δ0837 were generated by insertional inactivation of SMu0836, and SMu0837, respectively, of strain MT8148 and found to be more sensitive to antibiotics as compared to MT8148. In addition, assays of membrane transport functions using a fluorescent probe showed that export pumps did not function properly in strain Δ0836. Expression of those genes was elevated when strain MT8148 was cultured with a sublethal concentration of tetracycline, as well as when exposed to heat shock, osmotic stress, and oxidative stress conditions. Furthermore, the expressions of other genes including SMu0374, SMu0215, SMu0475, SMu0986, and SMu1051, which encode possible ABC transporters, were also elevated when strain MT8148 was cultured with a sublethal concentration of tetracycline. Together, these results suggest that the products of SMu0836 and SMu0837 are ABC transporters, which may function in stress response.
    Oral health and dental management. 06/2014; 13(2):359-65.
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    ABSTRACT: Objective Streptococcus mutans, a major dental caries pathogen, has shown to be associated with the aggravation of cerebral hemorrhage and inflammatory bowel diseases. In this study, we evaluated the effects of S. mutans on the development of non-alcoholic steatohepatitis (NASH) in a mouse model. Materials and methodsStreptococcus mutans oral strain MT8148 (serotype c) and a blood isolate TW871 (k) were used. C57BL/6J mice (6 weeks old) were fed a high-fat diet for 4 weeks; the test strains or phosphate-buffered saline was then intravenously administered. Mice were euthanized after 8 or 12 weeks. Whole body, extirpated liver, and visceral fat weights were determined, and histopathological evaluations of the liver specimens were performed. ResultsMice infected with TW871 showed significantly greater body and liver weights than those administered MT8148 or phosphate-buffered saline. Histopathological analyses revealed prominent infiltration of inflammatory cells and adipocellular deposition in livers extirpated 8 weeks after an infection with TW871; fibrosis was also observed in livers extirpated after 12 weeks. Conclusion These results suggest that a specific strain of S. mutans could induce NASH.
    Oral Diseases 10/2013; · 2.38 Impact Factor
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    ABSTRACT: produces 3 types of glucosyltransferases (GTFs), whose cooperative action is essential for cellular adhesion. The recombinase A (RecA) protein is required for homologous recombination. In our previous study, we isolated several strains with a smooth colony morphology and low GTF activity, characteristics speculated to be derived from the GTF fusions. The purpose of the present study was to investigate the mechanism of those fusions. strain MT8148 was grown in the presence of recombinant RecA (rRecA) protein, after which smooth colonies were isolated. The biological functions and sequences of the and genes of this as well as other clinical strains were determined. The sucrose-dependent adherence rates of those strains were reduced as compared to that of MT8148. Determination of the sequences of the and genes showed that an approximately 3500 bp region was deleted from the area between them. Furthermore, expression of the gene was elevated in those strains as compared to MT8148. These results suggest that RecA has an important role in fusions of and genes, leading to alteration of colony morphology and reduction in sucrose-dependent adhesion.
    The Scientific World Journal 01/2013; 2013:405075. · 1.73 Impact Factor
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    ABSTRACT: We used the Isolite system for treatment of dental caries identified in a submerged mandibular right primary second molar. A 5-year-6-month-old girl was referred to our clinic for close examination of an impacted mandibular right second primary molar. An intraoral examination showed a slight pit extending inside the gingiva and on the occlusal surface of the tooth. X-ray photographic examination revealed that the affected tooth was severely submerged and had a radiolucent area on the occlusal surface, which extended close to the pulp cavity. Most of the periodontal ligament space could not be clearly identified except for the distal side of the distal root. We considered that the area of the tooth was partially ankylosed and consulted with oral surgeons, who decided to postpone extraction, due to the presence of the permanent successor close to the affected tooth. Thus, we treated the dental caries, which appeared to be technically difficult because of the deep location of the tooth. The Isolite system was utilized in this case, as we considered that adjacent soft tissue and saliva could be excluded with its use. Under infiltration anesthesia, gingival tissue covering the occlusal surface was removed with an electric knife, and the carious lesion was removed, which resulted in pulp exposure. Severe inflammation of the pulp was revealed and pulpectomy was performed. There were no signs and symptoms after the treatment. At 1 year after treatment, the occlusal surface remained exposed and no inflammatory findings were observed in adjacent gingival tissue.
    Pediatric Dental Journal. 01/2012; 22(1):78–83.
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    ABSTRACT: Oenothera biennis (evening primrose) seed extract (OBSE) is known to contain polyphenols, which may possess antioxidant activities. Polyphenols extracted from several plants are reported to exhibit cariostatic activities by inhibiting mutans streptococcus growth and glucosyltransferase activities. The purpose of the present study was to examine the inhibitory effects of OBSE on the development of dental caries, both in vitro and in vivo. OBSE was investigated for its inhibitory effects on cellular aggregation, hydrophobicity, sucrose-dependent adherence and insoluble glucan synthesis. Furthermore, biofilm formation was examined in the presence of OBSE, using confocal microscopic imaging. An animal experiment was also performed to examine the in vivo effects. OBSE induced a strong aggregation of Streptococcus mutans MT8148 cells, while cell surface hydrophobicity was decreased by approximately 90% at a concentration of 0.25 mg/ml. The sucrose-dependent adherence of the MT8148 cells was also reduced by addition of OBSE, with a reduction rate of 73% seen at a concentration of 1.00 mg/ml. Additionally, confocal microscopic observations revealed the biofilm development phase to be remarkably changed in the presence of OBSE. Furthermore, insoluble glucan synthesis was significantly reduced when OBSE was present at concentrations greater than 0.03 mg/ml. In an animal experiment, the caries scores in rats given OBSE (0.05 mg/ml in drinking water) were significantly lower than those in rats given water without OBSE. Our results indicate that OBSE has inhibitory activity on dental caries.
    Caries Research 02/2011; 45(1):56-63. · 2.51 Impact Factor
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    ABSTRACT: Streptococcus mutans is known to be a primary causative agent of dental caries and its surface proteins have been investigated to specify their association with its virulence. Amongst those, 4 glucan-binding proteins (Gbps) are considered to be important factors due to their glucan-binding properties, of which GbpB has been shown to participate in cell-wall construction and cell separation. We examined clinical isolates of S. mutans collected from the oral cavities of Japanese and Finnish subjects, and focused on the association of their GbpB expression profiles and biological properties related to virulence. Western blot analysis of GbpB expression by the isolates revealed a variety of patterns. Strains that showed single and multiple bands were used to designate S and M type strains, respectively, whilst those with no GbpB expression were classified as N type. The distribution of GbpB expression patterns was shown to be quite different between the Japanese and Finnish isolates. Furthermore, the chain length and doubling time of the N type in both populations were significantly longer than those of the other types. Our results suggest variations in S. mutans GbpB expression patterns, which may have relationships with the virulence of S. mutans.
    Archives of oral biology 10/2010; 56(3):258-63. · 1.65 Impact Factor