Masahiro Yoneda

Humoral Immune Responses to S-Layer-Like Proteins of Bacteroides forsythus

ABSTRACT Bacteroides forsythus is one of the important periodontopathic bacteria, and this microorganism is known to have an S-layer outside the outer membrane. The S-layer-like antigens were recently isolated from B. forsythus, and they were found to be 270- and 230-kDa proteins in the envelope fraction. In this study, these proteins were confirmed to be specific to B. forsythus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and they were clearly recognized by sera from patients with adult and early-onset periodontitis in Western immmunoblot analysis. We compared the immunoglobulin G (IgG) responses against the purified S-layer-like antigen by enzyme-linked immunosorbent assay. IgG responses against this antigen were low in healthy control subjects, but they were significantly higher in subjects with adult and early-onset periodontitis. Together with the fact that the IgG responses against the crude extract of B. forsythus did not rise significantly in patients with periodontitis, S-layer-like proteins are considered to be specific antigens of B. forsythus and may play an important role in the progression of periodontitis.

Presence OF CXCR3-Positive Cells and IFN-γ–Producing Cells in Human Periapical Granulomas

In an attempt to understand further the balance between the types of helper T (Th) cells in human apical periodontitis, we examined the difference in the expression of the chemokine receptor and cytokine in samples obtained from human subjects by means of immunohistochemical methods. Chemokine receptor CXCR3-positive cells and IFN-γ–producing cells were found to be present in human periapical granulomas, whereas chemokine receptor CCR3-positive cells and IL-4–producing cells could not be detected. By contrast, no factor expression was observed in a clinically healthy periodontal ligament serving as a negative control. Our findings suggest that Th1 cells may play an important role in the pathological process of local inflammation such as apical periodontitis.

Structure and Function of a Novel Arginine-Specific Cysteine Proteinase (Argingipain) as a Major Periodontal Pathogenic Factor From Porphyromonas Gingivalis

Progressive periodontal disease is characterized by acute progressive lesions of gingival connective tissues, excessive leukocyte infiltration, and occurrence of a characteristic microflora (1). Porphyromonas gingivalis (formerly Bacteroides gingivalis), a Gram-negative anaerobic rod-shaped bacterium, is frequently isolated from cases of advanced periodontitis in humans and implicated in the etiology of the disease (review in references 2 and 3). This organism is known to produce a number of potential virulence factors, including fimbriae, hemagglutinins, lipopolysaccharides, and various hydrolytic enzymes (review in reference 4 and 5). Among the candidate virulence factors, the proteolytic enzymes are of special importance since they have the capacity closely related to the virulence of the organism. For example, the ability to degrade physiologically important proteins, including collagens and fibronectin, is likely to be associated with the direct periodontal tissue breakdown. Also, the ability to degrade immunoglobulins and complement factors appears to be involved in the disruption of normal host defense mechanisms. Further, these proteases may contribute to the bacterial nutrition during infection. A number of P. gingivalis proteinases have so far been described in both the cell-associated and secretory forms (review in reference 4 and 5). Recent molecular genetic approaches have also revealed that a variety of distinct proteinases are expressed by the organism (6–11).

Evaluation of a New Ceramic-containing Toothbrush Bristle 1. Questionnaire Survey on Dental Hygienist Students about its Usability and First Impressions

Toothbrushes after use are contaminated by many microorganisms including bacteria, fungi and viruses. We are thinking of making an anti-bacterial toothbrush by including ceramics in the bristle. But if the ceramic-containing bristles are too hard for the tooth and gingiva, it cannot be used as a toothbrush. So, before examining the antibacterial properties, we evaluated the feeling by asking students of dental hygiene. In our preliminary experiment, we determined the most appropriate width and length of ceramic-containing bristles. The students used this toothbrush and answered the questions. Almost all the students were satisfied with the new toothbrush with ceramic-containing bristles. Moreover, the new toothbrush was found to be comparable with the world-wide sold toothbrush. We obtained data that the ceramic-containing bristles were acceptable. Further study to investigate the anti-bacterial properties and effective cleanliness are in progress.

Applying orthodontic tooth extrusion in a patient treated with bisphosphonate and irradiation: a case report

Bisphosphonates and irradiation are useful medical treatments, but can often cause oral complications such as medication-related oral necrosis of the jaw (MRONJ) and osteoradionecrosis (ORN) during oral surgery, including tooth extraction. Therefore, we should take all risks into consideration carefully before choosing dental treatment for patients with a medical history of such therapies. A 55-year-old woman who underwent cord blood transplantation to treat extranodal natural killer T (NK/T) cell lymphoma (nasal type IVB) had a medical history of bisphosphonate and irradiation treatments. We treated her residual tooth root by applying orthodontic extrusion to avoid extraction and successfully restored the tooth. Application of an orthodontic tooth extrusion technique for conservative treatment of a residual tooth is a useful means of avoiding MRONJ or ORN in patients who have a medical history of bisphosphonate and irradiation treatments.