Satoko Inagaki

Potential involvement of collagen-binding proteins of Streptococcus mutans in infective endocarditis.

OBJECTIVE Streptococcus mutans, a major pathogen of dental caries, is considered to be one of the causative agents of infective endocarditis (IE). Two types of cell surface collagen-binding proteins, Cnm and Cbm, have been identified in the organism. The aim of the present study was to analyze these proteins as possible etiologic factors for IE. MATERIALS AND METHODS The binding activities of S. mutans strains to collagen types I, III, and IV were analyzed relative to the presence of Cnm and Cbm, as were their adhesion and invasion properties with human umbilical vein endothelial cells (HUVEC). In addition, distributions of the genes encoding Cnm and Cbm in S. mutans-positive heart valve specimens extirpated from IE and non-IE patients were analyzed by PCR. RESULTS Most of the Cbm-positive strains showed higher levels of binding to type I collagen as well as higher rates of adhesion and invasion with HUVEC as compared to the Cnm-positive strains. Furthermore, the gene encoding Cbm was detected significantly more frequently in heart valve specimens from IE patients than from non-IE patients. CONCLUSIONS These results suggest that the collagen-binding protein Cbm of S. mutans may be one of the potential important factor associated with the pathogenesis of IE.

Contribution of cell surface protein antigen c of Streptococcus mutans to platelet aggregation

INTRODUCTION Streptococcus mutans is considered to be one of the pathogens that cause infective endocarditis. The purpose of the present study was to examine the properties of S. mutans with regard to platelet aggregation by focusing on its high molecular protein antigen c (PAc). METHODS The platelet aggregation properties of six clinical strains and one isogenic mutant strain of S. mutans were analysed using an aggregometer and confocal microscopy, as well as with an inhibition assay of platelet aggregation using anti-PAc serum. RESULTS S. mutans strains with PAc expression induced platelet aggregation, while a PAc-deficient mutant and two clinical isolates with no PAc expression did not. When platelets were pretreated with higher amounts of anti-PAc serum, the platelet aggregation rate was reduced in a dose-dependent manner, indicating that PAc binds directly to platelets. CONCLUSION S. mutans PAc is involved in human platelet aggregation and may be one of the virulence factors in the pathogenesis of infective endocarditis.

Effects of recombinase A deficiency on biofilm formation by Streptococcus mutans.

BACKGROUND/AIM Recombinase A (RecA) is essential for the transformation of both plasmid and chromosomal DNA in Streptococcus pneumoniae and is considered to be related to the SOS-response in Streptococcus mutans. METHODS In the present study, a RecA-deficient mutant strain (RAD) was constructed by insertional inactivation of the recA gene encoding the RecA protein in strain MT8148 of S. mutans, after which the biological functions of acid tolerance and biofilm formation were investigated. RESULTS RAD showed reduced acid tolerance and produced lower density biofilm compared with the wild-type strain. In addition, confocal microscopic observation indicated that the biofilm produced by RAD was composed of cells with significantly lower viability compared with that produced by strain MT8148. CONCLUSION These results suggest that RecA has a relationship with biofilm formation.

Inhibitory Effects of Oenothera biennis (Evening Primrose) Seed Extract on Streptococcus mutans and S. mutans-Induced Dental Caries in Rats

Background: 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. Methods: 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. Results: 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. Conclusion: Our results indicate that OBSE has inhibitory activity on dental caries.

Regulation of Recombination between gtfB/gtfC Genes in Streptococcus mutans by Recombinase A

Streptococcus mutans 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. S. mutans 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 gtfB and gtfC 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 gtfB and gtfC genes showed that an approximately 3500 bp region was deleted from the area between them. Furthermore, expression of the recA gene was elevated in those strains as compared to MT8148. These results suggest that RecA has an important role in fusions of gtfB and gtfC genes, leading to alteration of colony morphology and reduction in sucrose-dependent adhesion.

Correlation of biological properties with glucan-binding protein B expression profile in Streptococcus mutans clinical isolates

OBJECTIVE 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. DESIGN 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. RESULTS 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. CONCLUSION Our results suggest variations in S. mutans GbpB expression patterns, which may have relationships with the virulence of S. mutans.

A case of incidental identification of mesiodens in 1-year-old boy followed for 6 years

We present a case of mesiodens identified in a 1-year 9-month-old boy. The patient visited our clinic after receiving a traumatic injury, which caused intrusion of the maxillary right and left primary central incisors. A periapical radiograph revealed no root fractures, though a mesiodens was incidentally found. The intruded teeth naturally moved into their original positions and periodical examinations were scheduled. At 4Y2M, uncommon mesial inclination of the maxillary right primary central incisor was noted. A radiographic examination showed the enlarged dental follicle of the mesiodens, which appeared to cause the inclination, and we planned fenestration when enlargement of the lesion was identified. At 5Y1M, he received another traumatic injury and the maxillary right primary central incisor was exfoliated. At 5Y5M, the mesiodens spontaneously emerged into the oral cavity and a radiographic examination showed prominent rotation of the maxillary right central incisor. Two-thirds of the crown of the mesiodens could be seen at 6Y4M. At 6Y11M, the patient again received a traumatic injury, and intrusion of the maxillary left primary central incisor was observed. At 7Y0M, the mesiodens and maxillary left primary central incisor were extracted under infiltration anesthesia, after which inclination of the axis of the adjacent maxillary right central incisor gradually improved.

Developmental anomalies of permanent teeth identified in children who received chemotherapy : Report of three cases

Abstract Childhood cancer, such as that manifested by neuroblastoma and hepatoblastoma tumors, is one of the leading causes of death for young children. Chemotherapy is one of the most important approaches available, though it is considered to cause tooth developmental disturbances when patients receive treatment during that period of development. Microdontia, disturbed root development, hypodontia and enamel hypoplasia are reported to be possible late adverse effects of chemotherapy. We analyzed 3 children, for whom chemotherapy had been given for treatment of cancer from the ages of 1 to 2.5 years old. Intraoral examinations revealed microdont of the bilateral maxillary lateral incisors and canines in 1 case, whereas that of the bilateral mandibular first premolars was shown in another. Orthopantomograph examinations revealed congenital absence of the first and second premolars in all 3 cases. The developmental period of the affected teeth in these cases appeared to correspond to the chronological age when chemotherapy was administered.

Multiple sites of idiopathic internal resorption in primary dentition: A case report

Abstract We treated a rare case with multiple sites of idiopathic internal resorption in primary dentition. A 3-year-old Japanese boy with no history of medical or dental disorders was referred by a general dentist for management of multiple sites of internal resorption in the primary teeth. Those with internal resorption had a pinkish color, however, no symptoms were noted. An X-ray photographic examination revealed round radiolucent lesions in the crown pulp of the upper right first primary molar, as well as in the roots of the lower right primary canine, upper left central primary incisor, and lower right lateral primary incisor. A histological examination of pulp removed from the right lower lateral primary incisor revealed increases in blood vessels, lymphocytes, and macrophages, while odontoclasts were not identified. Resorption of the teeth progressed rapidly and the lower right primary canine spontaneously exfoliated. Thereafter, endodontic treatment using Vitapex® halted the progress of tooth resorption. Our findings showed that early diagnosis, endodontic treatment, and short-interval follow-up examinations are needed to preserve teeth from rapid internal root resorption.

Idiopathic external root resorption with alveolar bone loss: Case report and microbiological evaluation

Abstract A case of idiopathic external root resorption identified in a girl aged 4 years and 2 months (4Y2M) is presented. The patient visited our clinic with a chief complaint of spontaneous pain in the area of the lower left primary canine. An intraoral examination revealed severe mobility of the affected tooth, while its marginal gingiva was swollen with a maximum periodontal pocket depth of 5mm. Irrigation of the periodontal pocket and general administration of antibiotics relieved the symptoms within 1 week. However, spontaneous pain recurred in the same area at 5Y0M. External root resorption was found with alveolar bone loss on the distal side, and microbiological analyses using broadrange polymerase chain reaction and sequencing methods were carried out with saliva and subgingival dental plaque specimens. In dental plaque specimens from unaffected regions and saliva specimens, Neisseria and Streptococcus species were frequently identified throughout the observation period. On the other hand, Prevotella and Fusobacterium species were predominant species in the dental plaque specimens from the area of the affected tooth. These results indicate that periodontopathic bacterial species rarely seen in children may have inhabited periodontal pockets formed from external root resorption in the present case.