The proliferative potential of two common histologic variants of ameloblastoma was investigated immunohistochemically using Ki-67 antibody on routinely processed, formalinfixed, paraffin-embedded sections. Thirty cases of ameloblastomas (15 cases of follicular and 15 cases of plexiform type) were analyzed. Autoclave heating pretreatment was employed at 121℃ for 20 min prior to analysis. This retrieval method allowed immunoreactive sites of the Ki-67 antigen to become exposed and thus available for immunohistochemical reaction. We found that expressed Ki-67 antigen was localized within the nucleus of tumor cells in both follicular and plexiform ameloblastomas. Immunoreactive cells were localized in the peripheral area of tumor islands as well as in the central stellate reticulum-area. The labeling rate was higher in the plexiform (3.68%) than in the follicular type (1.78%). Results suggest that cell proliferation of ameloblastoma was different depending on histologic variation of the tumor. Further, the proliferative potential was higher in the plexiform ameloblastoma than that in the follicular type. (J Osaka Dent Univ 1999; 33: 53-57)

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We investigated the characteristics of cell-membrane and extracellular proteoglycans in the monkey submandibular gland using enzymatic digestion and Western blot analysis. Extracellular proteoglycans and cell-membrane proteoglycans were extracted from the phosphate-buffered saline (PBS) soluble fraction and microsomal fraction of submandibular glands, respectively, and purified partially by ion exchange chromatography. Cellulose acetate membrane electrophoresis and immunoblotting with 3G10 monoclonal antibody or 6B6 monoclonal antibody showed that the extracellular proteoglycans contain several heparan sulfate proteoglycans (117, 67, 47 and 35 kDa core proteins) and a dermatan sulfate proteoglycan (45-50 kDa core protein), while the cell-membrane proteoglycans contain only a heparan sulfate proteoglycan with 69 kDa core protein. These results indicate that the several extracellular heparan sulfate proteoglycans may be released ectodomains of the cell-membrane proteoglycans from cell surface. It is suggested that the cell-membrane and extracellular proteoglycans may regulate the function of growth factors and the microenvironment in the normal submandibular gland. (J Osaka Dent Univ 1999; 33: 59-64)

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We studied functional properties of nociceptive neurons in the thalamic intralaminar nuclei, especially the nucleus centralis lateralis (CL) in urethane-chloralose anesthetized cats. Nociceptive neurons were found in the intralaminar nuclei, i.e. CL, nucleus centralis medialis (CeM) and nucleus parafascicularis (Pf). One third of these nociceptive neurons had their receptive fields throughout the body, including the orofacial area. Namely, they received convergent nociceptive input from the trigeminal and spinal nerve territories. These neurons with widely complex receptive fields were similar to those we found in the middle third of the caudal bulbar reticular formation (RF). Electrical stimulation of the CL antidromically activated about half of the caudal bulbar RF neurons tested. Furthermore, electrical stimulation of the cingulate gyrus antidromically activated some of CL neurons. These findings suggest that most of the CL neurons receiving nociceptive input from throughout the body receive information directly or indirectly via the caudal bulbar RF, and that certain of this information is then conveyed to the cingulate gyrus. J Osaka Dent 1999; 33: 65-73)

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The precise mechanism of disruption of cell-cell adhesion in oral squamous cell carcinomas has yet to be established. We therefore sought to clealy this mechanism by investigating expression of both E-cadherin (E-CD) and α-catenin (α-CAT), which is an intracellular CD-binding molecule, in squamous cell carcinomas of the tongue, gingiva and floor of the mouth using immunohistochemical and immunoblotting techniques. We found that reduced expression of both E-CD and α-CAT occurred more frequently in moderately and poorly-differentiated carcinomas than in well-differentiated specimens (p<0.001), and this reduced expression showed no regional specificity. Relatively frequent loss of α-CAT expression in poorly-differentiated carcinomas was detected by both immunohistochemical and immunoblotting analyses. These findings suggest that E-CD and α-CAT are both important regulators of intercellular adhesion, and that the reduction of these molecules is also linked to the process of tumor dedifferentiation. (J Osaka Dent Univ 1999; 33: 75-81)

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We investigated the mRNA expression of cell-surface heparan sulfate proteoglycans, syndecans and glypican, in the adult female monkey submandibular gland using the reverse transcription-polymerase chain reaction (RT-PCR) technique. Agarose gel electrophoresis of the PCR products of the cDNA generated from RNA was carried out to demonstrate the expression of mRNA in syndecan-1, syndecan-2, syndecan-4 and glypican in this study. In order to compare the mRNA expression level among the cell-surface heparan sulfate proteoglycans, we measured changes in the relative intensity of PCR products with increasing thermal cycle number. The expression levels were syndecan-4 >syndecan-1, syndecan-2>glypican. Considering these results together with our previous report, we found that the cell-surface heparan sulfate proteoglycans, syndecan-1, syndecan-2, syndecan-4 and glypican, are synthesized in the monkey submandibular glands, and that their ectodomains are released into the extracellular matrix. It was speculated that control of the expression patterns of the cell-surface proteoglycans may regulate the cellular function and behavior in the submandibular gland. (J Osaka Dent Univ 1999; 33: 83-87)

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