Yoshimichi Gonda

Cloning and sequencing of the gene coding for dextranase from Streptococcus salivarius.

We cloned and sequenced the dextranase (Dex) (1,6-alpha-glucanhydrolase; EC 3.2.1.11)-encoding gene from Streptococcus salivarius (Ss) strain M-33. Recombinant clones from an Ss genomic library specifying Dex activity were identified as colonies surrounded by transparent halos on blue dextran plates. One of the clones had a 4.3-kb KpnI fragment containing the gene coding for an 826-amino-acid polypeptide with a molecular mass of 87.9 kDa, which corresponds well to that of native Dex from the Ss culture supernatant. There was no sequence homology between the gene encoding Ss Dex and the gene encoding dextran glucosidase of S. mutans, or between their protein products.

Disaccharide analysis of chondroitin sulphate in human gingival crevicular fluid using high-performance liquid chromatography.

Gingival crevicular fluid (GCF) was collected into capillary tubes from healthy gingiva and sites of advanced periodontitis. Following digestion with Pronase E, the glycosaminoglycans were isolated by successive precipitation into 5% cetylpyridinium chloride and 95% ethanol. Unsaturated disaccharide isomers of chondroitin sulphate, obtained following chondroitinase ACII digestion, were analysed by high-performance liquid chromatography. Chondroitin sulphate was found in all GCF samples, with greater amounts in patients with periodontal disease than at control sites with a relatively healthy periodontium. The predominant isomer in the periodontal diseased group was delta Di-4S, while that in the control group and serum samples was delta Di-0S. Comparison of the relative proportions of the unsaturated disaccharides in GCF with previously reported values for alveolar bone, cementum, gingiva and periodontal ligament, as well as for serum, indicates that the chondroitin sulphate present in GCF of patients with periodontal disease originated from the mineralized connective tissues of the periodontium, notably alveolar bone, possibly with some contributions from soft connective tissues of gingiva and periodontal ligament and from serum.

Application of lingual contact occlusion to complete dentures with two-layered posterior teeth: A clinical report

When two-layered artificial teeth are used, acrylic resin occlusal parts can be removed from base parts and used directly as resin patterns for casting, which facilitates fabrication of metal occlusal surfaces. Because these teeth were made of acrylic resin, it was easy to modify occlusal morphology before converting to metal. Application of two-layered artificial teeth to achieve lingual contact occlusion brought about sufficient masticatory forces and denture stability and resulted in patient satisfaction.

Scanning Electron Microscopic Study on Microvasculature Surrounding Titanium Implants.

Recently, more concern has been directed to pen-abutment tissues as they relate to the marginal design of the superstructure, hygiene management, and sequelae of peri-implantitis. Especially, since penabutment tissues lack periodontium, whether or not they play a role as a biological defense mechanism against various external stimuli has been in question. In this study, the microvasculature around implant was investigated.Titanium screw-type implants were used in this study. Three adult Japanese monkeys were used. At weeks 2, 4, and 8 after the abutment connection, the animals were sacrificed, and microvascular casts were prepared for examination by scanning electron microscopy.At week 8, as was observed at weeks 2 and 4, the capillary network surrounding the abutment had developed a running horizontal structure and was well defined. At the superior margin of the alveolar bone, the pen-abutment capillary network was anastomosed to the periosteum capillary network. Extension of the pen-abutment capillary network into the alveolar bone surface corresponding to the fixture flange was not observed.If peri-implantitis exacerbates, or lasts long, due to poor microvascularization lacking periodontal ligament in this region, it is easy for external stimuli to cause damage the alveolar bone. Hygiene control around the implant is more important than around natural teeth.

Development of Clinical Examination Device for Complete Denture Construction.

A clinical examination device for complete denture construction was developed, and its use was investigated. The device was found to be effective for recording and examining the relation between artificial teeth and the alveolar ridge. Additionally, it was confirmed to be possible to make the occlusal rim and to arrange artificial teeth in accordance with the location of the incisive papilla and alveolar ridge. This device also allows fabrication of the base of the model parallel to the occlusal plane.

Horizontal dimensional changes in maxillary dentures made of polyethersulfone.

The purpose of this research was to investigate the horizontal dimensional variations in maxillary complete dentures fabricated with Polyethersulfone (PES) using compression molding. Dimensional changes were compared for the three different materials PES, Polysulfone (PSF), and PMMA.The results were as follows:1. In the case of the occlusion rim, all three materials displayed horizontal shrinkage both in the anteroposterior and in the left/right directions. PMMA had the largest shrinkage, followed by PSF and PES in that order.2. In the case of the denture, PSF had the largest horizontal shrinkage in the anteroposterior direction, followed by PES and PMMA in that order. In the left/right direction the shrinkage was largest for PMMA, followed by PES and PSF in that order.3. PES, like PMMA displayed a uniform shrinkage in the anteroposterior direction, with little difference observed between shrinkage in the anterior and posterior region. However, PES, like PSF, had greater shrinkage in molar region than the anterior region.

A biochemical study of glycosaminoglycans in the palatal rugae of the monkey (Macaca fascicularis)

Glycosaminoglycans (GAG) were extracted from the connective tissue of the palatal rugae, separated by electrophoresis and compared with the results obtained for the remaining palatal mucosal and gingival connective tissues. The GAG content of the rugae (3.01 mg/g defatted dry weight) was higher than in the remaining palatal mucosa (2.33 mg/g defatted dry weight) or gingiva (1.68 mg/g defatted dry weight). Dermatan sulphate was the predominant GAG in both the palatal rugae (48% of total GAG) and the remaining palatal mucosa (50%) followed by hyaluronic acid (33 and 31% respectively). The results do not support previous histochemical observations in which the rugae appeared to be rich in hyaluronic acid.

[Decubitus ulcer of the oral mucosa--changes in glycosaminoglycans].

This study has been performed to observe macroscopic, histological and histochemical changes in the decubital ulcer that was formed experimentally by the 5mm length and 1mm diameter wire cemented on the buccal surface of upper first molar.The tissue destruction was progressed from the surface of the decubital ulcer by mechanical stimuli, and the tissue restoration advansed from the circumference of the ulcer. At the bottom of the decubital ulcer the tissue destruction and restoration was repeated mutually. The location and molecular kinds of glycosaminoglycans also changed with these changes.