Kisaki Shimazu

Contribution of sialic acid-binding adhesin to pathogenesis of experimental endocarditis caused by Streptococcus gordonii DL1.

ABSTRACT An insertional mutation in hsa, the gene encoding the sialic acid-binding adhesin of Streptococcus gordonii DL1, resulted in a significant reduction of the infection rate of the organism and an inflammatory reaction in the rat aortic valve with experimental endocarditis, suggesting that the adhesin contributes to the infectivity of the organism for heart valves.

Evaluation of the ion-releasing and recharging abilities of a resin-based fissure sealant containing S-PRG filler.

We evaluated the concentration of fluoride release at the initial stage and after recharging the fluoride from a resin-based sealant containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler and conventional resin-based sealants. The concentration of other ions released from the sealants in the surrounding distilled water was also examined. At the initial stage, fluoride was released from all sealants. For the sealant containing S-PRG filler, a significantly higher amount of Sr and B ions was detected relative to those from other sealants. After sealant samples were soaked in a sodium fluoride solution, a significant amount of fluoride and other ions was released from the sealant containing S-PRG filler. These findings suggest that sealants containing S-PRG filler enhance the enamel demineralization-inhibiting effect and the remineralization-promoting effect for long-term dental care.

Prevalence and association of self-reported anxiety, pain, and oral parafunctional habits with temporomandibular disorders in Japanese children and adolescents: a cross-sectional survey

BackgroundAssociations between temporomandibular disorder (TMD) and psychological variables, pain conditions, and daily activities have been reported more commonly in middle-aged individuals than in children. However, to determine factor-specific preventive programs for TMD, it is important to evaluate the associations between multiple factors and TMD symptoms during childhood. The aim of this study was to assess the relationship between TMD symptoms and other orofacial pain conditions, daily activities, and trait anxiety in a population-based cross-sectional survey of Japanese children and adolescents.MethodsA total of 1,415 subjects (11–15 years old) self-reported their TMD symptoms, headache, neck pain, and toothache, and completed questionnaire scales that assessed 15 daily activities. Trait anxiety was assessed using the State Trait Anxiety Inventory for Children-Trait (STAIC-T) scale. Subjects were dichotomized into a TMD group or control group, based on whether they reported at least 1 TMD symptom: the TMD group (≥1 TMD symptom, n = 182) and the control group (no TMD symptoms, n = 1,233). Data were analyzed using the chi-square test and multivariate logistic regression analysis.ResultsThe prevalence rates for headache and neck pain were significantly higher in the TMD group than in the control group (44.0% vs. 24.7% and 54.4% vs. 30.0%, respectively; both P < 0.001). The odds ratios for TMD symptoms in subjects with neck pain and frequent diurnal clenching were 2.08 (P < 0.001) and 3.69 (P = 0.011), respectively. Moreover, high STAIC-T scores were weakly associated with TMD symptoms.ConclusionsIn this young Japanese population, TMD symptoms were associated with other orofacial pain conditions, particularly neck pain, although they were only weakly associated with trait anxiety. Diurnal clenching was strongly associated with TMD symptoms. Health professionals should carefully consider these factors when developing appropriate management strategies for TMD in children and adolescents.

Hsa, an adhesin of Streptococcus gordonii DL1, binds to α2-3-linked sialic acid on glycophorin A of the erythrocyte membrane

Bacterial recognition of host sialic acid‐containing receptors plays an important role in microbial colonization of the human oral cavity. The aggregation of human platelets by Streptococcus gordonii DL1 is implicated in the pathogenesis of infective endocarditis. In addition, we consider that hemagglutination of this organism may act as an additive factor to increase the severity of this disease. We previously reported that this interaction requires the bacterial expression of a 203‐kDa protein (Hsa), which has sialic acid‐binding activity. In the present study, we confirmed that erythrocyte surface sialoglycoproteins are the receptors for Hsa. We examined the effects of proteinase K, chymotrypsin, phospholipase C, and α(2‐3) or α(2‐3, 6, 8) neuraminidase on hemagglutination activity and found that the interaction occurs between Hsa and α2‐3‐linked sialic acid‐containing proteins of erythrocytes. We expressed recombinant NR2, which is the putative binding domain of Hsa, fused with GST in Escherichia coli BL21. Dot‐blot analysis demonstrated that GST‐HsaNR2 binds both glycophorin A (GPA) and band 3. Moreover, GPA and a small amount of band 3 were detected by GST pull‐down assays. These findings indicate that S. gordonii Hsa specifically binds to GPA and band 3, α2‐3‐linked sialic acid membrane glycoproteins.

Comparison of Subjective Symptoms of Temporomandibular Disorders in Young Patients by Age and Gender

Abstract The authors assessed the subjective symptoms of temporomandibular disorders (TMDs) in 167 young patients using self-reported forms, with five ratings for pain intensity and six ratings for difficulty in activities of daily living (ADL), to compare TMD symptoms according to gender and three age groups: group 1: 6- to 12-year-olds (juvenile); group 2: 13- to 15-year-olds (early adolescent); group 3: 16- to 18-year-olds (late adolescent). No significant gender differences were found in the symptoms among the groups, except for headache and neck pain in group 3. Pain intensity and tightness in the jaw/face, headache, and neck pain, as well as the ADL-related difficulty in prolonged jaw opening, eating soft/hard foods, and sleeping significantly differed among the groups (p<0.01, Kruskal–Wallis test). Therefore, late adolescent patients with TMDs have higher pain intensity in the orofacial region and greater difficulty in ADL than do early adolescent and juvenile patients with TMDs.

Contribution of phosphoglucosamine mutase to determination of bacterial cell morphology in Streptococcus gordonii

Phosphoglucosamine mutase (GlmM; EC 5.4.2.10) catalyzes the interconversion of glucosamine-6-phosphate to glucosamine-1-phosphate, an essential step in the biosynthetic pathway leading to the formation of the peptidoglycan precursor uridine 5′-diphospho-N-acetylglucosamine. We have recently identified the gene (glmM) encoding the enzyme of Streptococcus gordonii, an early colonizer on the human tooth and an important cause of infective endocarditis, and indicated that the glmM mutation in S. gordonii appears to influence bacterial cell growth, morphology, and sensitivity to penicillins. Moreover, the glmM mutation results in increased sensitivity to polymorphonuclear leukocyte (PMN)-dependent killing. In the present study, we observed similarities in the utilization of sugar between the wild-type strain and the glmM mutant of S. gordonii when cultivated with medium containing 0.2% glucose, fructose, lactose, or sucrose. Morphological analyses clearly indicated that the glmM mutation causes marked elongation of the streptococcal chains, enlargement of bacterial cells, increased distortion of the bacterial cell surface, and defects in cell separation. These results suggest that mutations in glmM appear to influence bacterial cell growth and morphology, independent of the carbon source.

Contribution of Streptococcus gordonii Hsa adhesin to biofilm formation

Adhesion of oral mitis group streptococci, such as Streptococcus gordonii, to acquired pellicle on the tooth surface is the first step in oral biofilm formation. S. gordonii strain DL1 possesses an Hsa adhesin, which recognizes the terminal sialic acid of host sialoglycoconjugates. The aim of the present study was to investigate the role of the Hsa adhesin in biofilm formation. The biofilm-forming ability of a S. gordonii hsa mutant on microtiter plates pre-coated with saliva, fetuin, or mucin was significantly lower than that of wild-type strain DL1. In contrast, no significant difference in biofilm-forming ability was observed in plates pre-coated with bovine serum albumin, which does not contain sialic acid. The biofilm-forming ability of strain DL1 in saliva-coated microtiter plates was also significantly reduced when the plate was pre-treated with neuraminidase. The sialic acid-dependent biofilm-forming ability of different wild-type S. gordonii strains varied. However, Southern and western blot analyses showed that all the tested wild-type strains possessed and expressed hsa homologs, respectively. These results indicate that the binding of Hsa adhesin to sialoglycoconjugates is associated with biofilm formation of S. gordonii DL1, and imply variation in the contribution of Hsa and its homologs to S. gordonii biofilm formation.

Effects of surface reaction-type pre-reacted glass ionomer on oral biofilm formation of Streptococcus gordonii.

Streptococcus gordonii, a bacterium involved in the initial colonization of tooth surfaces, contributes to dental biofilm formation and is an important cause of infective endocarditis. This study aimed to investigate the influence of surface reaction-type pre-reacted glass ionomer (S-PRG) filler on oral bacterial growth and aggregation of S. gordonii. The effect of various concentrations of S-PRG eluate on the growth and the biofilm formation of S. gordonii and other oral microorganisms (Streptococcus mutans, Streptococcus oralis, Lactobacillus acidophilus, and Candida albicans) was assessed. In addition, the effect of S-PRG eluate on coaggregation of S. gordonii with both S. oralis and Fusobacterium nucleatum was assessed. The effect of S-PRG eluate treatment on autoaggregation of S. gordonii was also evaluated. Our results indicate that S-PRG eluate treatment reduced both for the growth and for biofilm of all organisms in a dose-dependent manner. Coaggregation of S. gordonii with both S. oralis and F. nucleatum was inhibited by S-PRG eluate, whereas autoaggregation of S. gordonii increased at certain concentrations of S-PRG eluate. These results indicate that the S-PRG filler possesses antimicrobial activity that is mediated by inhibiting growth and biofilm of oral microorganisms, and by suppressing coaggregation of S. gordonii. In addition, these findings indicate that coaggregation of S. gordonii with other bacteria is inhibited by increased autoaggregation of S. gordonii.