Masaaki Kanazawa

Establishment of high- and low-invasion clones derived for a human tongue squamous-cell carcinoma cell line SAS

Distant-organ metastasis and regional lymph node metastasis are still the major cause of mortality of oral-cavity squamous-cell cancer (SCC). However, only a few studies have been undertaken to elucidate the mechanism of invasion and metastasis of oral SCC. In this study, we attempted to establish human oral SCC clones with different invasiveness, defined by endothelial cell monolayer assay, which can be used for the study of invasion and metastasis of oral SCC. We established five clones from the human oral SCC cell line SAS by a limiting-dilution method. Two distinct clones, SAS-L1 with very low invasive potential and SAS-H1 with very high invasive potential, were picked out by rat lung endothelial cell monolayer assay. The number of SAS-H1 that penetrated the rat lung endothelial cell monolayer was six fold higher than the number of SAS-L1. There were no differences of metalloproteinase production and cell adhesiveness to Matrigel of SAS-L1 and SAS-H1. However, SAS-H1 exhibited a higher migration ability than SAS-L1. This pair of clones would be a useful experimental model to help in the study of the invasiveness of human oral SCC.

Positional change of the hyoid bone at maximal mouth opening

The positional change of the hyoid bone in both closed and maximal mouth-opening positions of the mandible was investigated by cephalometric measurements. The following results were obtained: (1) With the increase in mouth opening the hyoid bone moved downward and backward. At maximal mouth opening the head posture changed posteriorly compared with that of occluded mouth position. (2) By superimposing films of the S-N plane, it became apparent that the hyoid bone was displaced downward by sagittal opening movement of the mandible and backward by the posterior change of the head posture. (3) Significant correlations were found between the degrees of sagittal rotation of the mandible and the position of the hyoid bone. (4) These results suggest that the posterior change of the head posture and inferior shift of the hyoid bone with mouth opening are important factors in obtaining maximal mouth opening.

Histologic study of synovitis induced by trauma to the rat temporomandibular joint

OBJECTIVE The purpose of this study was to establish and histologically examine the time course of synovitis induced by trauma to the rat temporomandibular joint. STUDY DESIGN Synovitis of the temporomandibular joints of 8-week-old male Wister rats was induced by forced condylar hypermobility, which was administered 10 times successively once a day for 10 days. Pathologic changes were observed microscopically at 2 and 5 days and 2, 4, 6, 8, 10, and 20 weeks after treatment. RESULTS Histologic findings from the 5th day to the 6th week after treatment were characterized by multiple layers of synovial cells, an increase of dilated vasculature, fibrin deposits, and synovial adhesion. These findings were in good agreement with those reported for the human temporomandibular joint. The pathologic changes decreased with advancing time, and synovitis was not observed at 20 weeks after treatment. CONCLUSION The present procedure for inducing synovitis of the temporomandibular joint in rats will be useful in understanding the pathogenesis of synovitis in human temporomandibular joints.

Pycnodysostosis: Report of a case and review of the Japanese literature, with emphasis on oral and maxillofacial findings

We report a case of pycnodysostosis and review 54 cases of this syndrome in the Japanese literature, with special emphasis on oral and maxillofacial findings. Common findings were as follows: hypoplasia of maxilla and mandible, hypopneumatization of the maxillary sinuses, loss of mandibular angle, a grooved palate, and malpositioned teeth.

The position of the mandibular condyle at maximal mouth opening in normal subjects

PURPOSE To investigate the position of the mandibular condyle at maximal mouth opening in individuals 19 to 30 years of age with no functional disorders of the masticatory system. PATIENTS AND METHODS Measurements were made in 153 subjects (99 men, 54 women), and 41 men and 44 women had transcranial radiographs taken of their right and left temporomandibular joints in the closed and maximal opening positions. RESULTS In all subjects the condyle moved forward beyond the summit of the articular eminence, and in more than half the subjects the condyle was located inferior to the eminence at maximal opening. CONCLUSION The correlation between maximal opening and anterior shift of the condyle from the summit of the eminence was significant, but the correlation with vertical shift of the condyle was not significant. The correlation between the form of the glenoid fossa (length and depth) and anterior or vertical shift of the condyle from the summit of the eminence also was not significant.

Basaloid-squamous cell carcinoma of the oral mucosa: Report of two cases and study of the proliferative activity

Two cases of basalold‐squamous cell carcinoma (BSC) of the oral mucosa are described. The first case occurred at the floor of the mouth in a 58‐year‐old man, and the second case occurred at the mandibular gingiva in a 79‐year‐old woman. The laboratory data of the first case showed a positive response to hepatitis C virus antibody. in the first case, the tumor mass measured 4 times 4 cm in size, and was i‐texl at the lingual side of the median mandible beside the sublingual gland. In the second case, the tumor mass measured 25 times 15 mm In size, and was located in the alveolar mucosa of the right mandible. Histologically, both tumors showed a neoplastic epithelium arranged in a solid pattern with evidence of peripheral palisading, central necrosis, and some squamous differentiation. The pro‐ilferathfe activities of the BSC were compared with conventional squamous cell carcinomas (SCC) in the oral floor and gingiva, respectively, by employing a sensitive argy‐rophillc nuclear organizer region (AgNOR) staining method. The number of AgNOR per nucleus of the BSC was higher than that of any other SCC cases. The results support the opinion that BSC of the oral mucosa has a worse prognosis than conventional SCC.

Protein phosphatase inhibitor calyculin A induces hyperphosphorylation of cytokeratins and inhibits amylase exocytosis in the rat parotid acini

Calyculin A, a protein phosphatase inhibitor with a chemical structure completely different from that of okadaic acid, reproduced the inhibitory effect of okadaic acid on cyclic AMP‐mediated amylase release from rat parotid acinar cells. Calyculin A markedly enhanced phosphorylation of cytokeratins in the cytoskeletal fraction of the cells, whereas cAMP had apparently no effect on the phosphorylation. Microscopic observations showed that parotid acini incubated with 100 nM calyculin A for 15 min had large vacuoles in the cytoplasm and conspicuous blebs on the basal plasma membrane. K252a, a nonselective protein kinase inhibitor, clearly reduced calyclin A‐induced phosphorylation of cytokeratins, and it markedly blocked the inhibition of amylase release and morphological changes evoked by calyculin A. These results suggest that hyperphosphorylation of cytokeratins profoundly affects the morphology and secretory activity of parotid acinar cells.

Development and histologic characteristics of synovitis induced by trauma in the rat temporomandibular joint

Histopathological changes caused by trauma to the rat temporomandibular joint synovium were examined by light microscopy. The trauma was induced by forced hypermobility of the condyle. Pathological changes of the synovium were found primarily in the anterior pouch of the upper joint compartment. The main findings included surface cell proliferation, increased capillary hyperemia, fibrin deposits on the surfaces of inflamed synovial membranes, and fibrinous adhesion between closely opposed synovial membranes. A gradual change from fibrinous adhesion to fibrous adhesion was also seen.

Linear and angular measurements of the mandible during maximal mouth opening

PURPOSE There are numerous reports of the translatory movement of the condyle in maximal mouth opening; however, the rotatory movement is less well understood. The purpose of this study was to investigate the rotatory condylar movement and the factors associated with it in normal subjects. PATIENTS AND METHODS To study the role of facial morphology in maximal mouth opening, linear and angular measurements of the mandible in both the closed and maximal open positions were made by means of cephalometry. Dental students, 29 men and 31 women with no functional disorders of the masticatory system, were investigated. RESULTS When the mouth was fully opened, the linear measurement of condylar movement was 20.5 +/- 4.0 mm in men and 18.1 +/- 2.5 mm in women, and the angular measurements of the rotation of the mandibular ramus were 39.1 +/- 5.9 degrees in men and 36.3 +/- 4.3 degrees in women. These differences were statistically significant (P < .01). CONCLUSIONS During condylar movement and rotation of the mandible, mandibular length and the inclination of the mandibular ramus in the former, and the inclination of the mandibular ramus, the mandibular angle and the position of the condyle in the latter, were important factors.

Necrotizing fasciitis of the neck and chest. Report of a case

A case is presented of necrotizing fasciitis of the neck and chest characterized by rapid progressive necrosis of subcutaneous tissue, fascia and skin. The diagnosis and management is discussed.