Ichiro Semba

Kimura's disease: A clinicopathologic study of 54 chinese patients

Kimuras disease, a chronic inflammatory condition of unknown cause, is endemic in Orientals. The present study documented 54 cases of Kimuras disease in patients from mainland China. The main clinical features of this series included young and middle-aged male predominance (male:female = 3.5:1), predilection for the head and neck regions, and a long duration. The disease presented as either single (31 cases), or multiple lesions (23 cases), and mainly involved subcutaneous tissues (29 cases), major salivary glands (21 cases), and lymph nodes (17 cases) in isolation or in combination. Histopathologically, the lesion was characterized by hyperplasia of lymphoid tissue with well-developed lymphoid follicles, marked infiltration of eosinophils, proliferation of thin-walled capillary venules, and varying degrees of fibrosis. Distinctive features of salivary glands and nodal involvement were also described. Differences between Kimuras disease and angiolymphoid hyperplasia with eosinophilia, mostly reported in the West, were discussed to draw attention to their distinction.

Tumor lymphangiogenesis correlates with lymph node metastasis and clinicopathologic parameters in oral squamous cell carcinoma

Lymphatic vessel density (LVD) and microvessel density (MVD) are important parameters for assessing the malignant potential of tumors and patient survival. In this report, the authors defined LVD as the density of D2‐40‐positive lymphatic vessels and MVD as the density of CD105‐positive microvessels per unit area of tissue. It was reported previously that vascular endothelial growth factor C (VEGF‐C) is a major modulator of LVD and MVD. The objectives of this study were to clarify the clinical and prognostic significance of both LVD and MVD in oral squamous cell carcinoma (OSCC) and to elucidate the lymphangiogenic and angiogenic activities of VEGF‐C in cancer tissues.

Expression of hepatocyte growth factor/scatter factor and c-Met in human dental papilla and fibroblasts from dental papilla

Hepatocyte growth factor/scatter factor (HGF/SF), a broad-spectrum and multifunctional cytokine, is essential for the development of tissues including tooth. Here it was found that the HGF/SF content of human dental papillae obtained from 8 to 16-year-old individuals decreased significantly with age. Cultured fibroblasts prepared from the dental papillae of individuals of different ages produced HGF/SF at almost the same rate, but the sensitivities of the cells to interleukin-1alpha and tumour necrosis factor-alpha for the production of HGF/SF increased with age. Generally, mesenchymal cells such as fibroblasts produce HGF/SF but do not express c-Met, a receptor for HGF/SF, yet fibroblasts in dental papilla and cultured fibroblasts prepared from dental papilla did express c-Met, as determined by immunohistochemistry, in situ hybridization and reverse transcription-polymerase chain reaction. Recombinant human [125I]iodo-HGF/SF specifically bound to cell-surface macromolecules with a mol. wt of 146,000, which is the same as that of the beta-subunit of c-Met. The physiological role of c-Met on fibroblasts in dental papilla is unknown, but the addition of 2 ng of HGF/SF per ml to the culture medium significantly stimulated DNA synthesis in the cells, as determined by pulse labelling with [3H]thymidine. Exogenous HGF/SF also stimulated secretion by the cells of vascular endothelial growth factor, a cytokine that induces blood vessel-formation. These results suggest that HGF/SF may be involved in tooth development via autocrine mechanisms.

Higher osteoclastic demineralization and highly mineralized cement lines with osteocalcin deposition in a mandibular cortical bone of autosomal dominant osteopetrosis type II: ultrastructural and undecalcified histological investigations.

In this study we report on histological and ultrastructural investigations of the mandibular cortical bone in a case of autosomal dominant osteopetrosis type II complicated by mandibular osteomyelitis. Histologically, there was a marked increase in the number and size of osteoclasts on the inner bone surface. An undecalcified preparation showed a pair of deeply stained (highly demineralized) and stain-phobic (highly mineralized) layers on the bone surface just beneath the osteoclasts. The layers were incorporated into the bone matrix during the remodeling process as thickened cement lines. A contact microradiogram of the cortical bone revealed highly mineralized layers at the cement lines, which were closely correlated with immunohistochemical evidence of deposition of osteocalcin at the thickened cement lines. Ultrastructural examination showed that the osteoclasts had a typical clear zone, but they were deficient in ruffled border formation and had numerous lysosomal vacuoles containing dense substances. An electron-dense amorphous material layer was present on the bone surface just beneath the osteoclasts as well as at the cement lines. The layer was partly composed of a short fibrillar material, and it partially revealed the lamellar structure. Consequently, an osteoclastic malfunction might be primarily involved in the process of bone matrix resorption rather than demineralization, resulting in higher demineralization and abnormal material deposition on the bone surface and at the cement lines. Furthermore, evidence of active osteoclastic bone resorption with a brush border formation at the bone involved in the inflammatory lesion in this case suggests that the osteoclastic malfunction is influenced and recovered by a microenvironment such as inflammatory cytokines.

Hepatocyte growth factor/scatter factor stimulates migration of muscle precursors in developing mouse tongue.

Hepatocyte growth factor (HGF) stimulates the migration of myogenic cells during the development of skeletal muscles. The inactivation of HGF genes or that of its receptor, c‐met, in mice causes hypoplasia of skeletal muscle organs, such as the tongue. Basic fibroblast growth factor (FGF‐2) also induces migration of skeletal myoblasts. A comparison of the functions of HGF and FGF‐2 in myogenesis revealed the crucial effect of HGF in the development of skeletal muscles. Unlike FGF‐2, HGF induced migration of myoblasts from the developing mouse tongue. The differences between the activities of HGF and FGF‐2 were determined by comparing their effects on the expression of matrix metalloproteinase‐9 (MMP‐9) in myoblasts, C2C12 cells, cultured in collagen‐coated dishes. The results showed that HGF, but not FGF‐2, stimulated MMP‐9 expression, and that the stimulation was mediated through the activation of phosphoinositide 3‐kinase (PI3K) which was not associated with FGF‐2 signal transduction. Nevertheless, both growth factors exerted almost the same effect on the reduction of myogenin expression in, and on the proliferation of, C2C12 cells, suggesting that HGF, rather than FGF‐2, plays a crucial role in the generation of skeletal muscles, including the tongue. Moreover, the specific role of HGF through the PI3K signal pathway is the induction of MMP‐9 expression in, and the migration of, myoblasts.

Hepatocyte growth factor in gingival crevicular fluid and the distribution of hepatocyte growth factor-activator in gingival tissue from adult periodontitis

Hepatocyte growth factor (HGF), also known as scatter factor, is a broad-spectrum and multifunctional cytokine required for the development, growth and regeneration of various organs and tissues. The expression of HGF in human gingival fibroblasts is induced by inflammatory cytokines such as interleukin 1. Thus, although it is possible that content of HGF in gingival crevicular fluid (GCF) in periodontitis is increased, this has not so far been reported because the volume of GCF is too small to determine HGF by the available enzyme-linked immunosorbent assay (ELISA). A recently developed, highly sensitive ELISA for HGF, with a detection limit of 1 pg/ml sample, has now enabled HGF to be measured in GCF.The mean HGF content in GCF from sites with clinically healthy gingiva, defined by the absence of overt signs of gingival inflammation and a probing depth (PD) <3 mm, was 1.7 ng/ml, and that of periodontitis, defined by obvious alveolar bone loss detected by radiographic examination and a PD> or =3 mm, was 3.23 ng/ml. Although treating the periodontitis did not significantly decrease the HGF concentration despite significantly improved clinical scores such as PD and Gingival Index, the total amount of HGF in GCF did decrease significantly after treatment. HGF was expressed by gingival fibroblasts and inflammatory cells as determined by in situ hybridization. HGF-activator (HGFA), which converts inactive pro-HGF to active mature HGF, was detected in gingival epithelial cells by immunostaining. The expression of HGFA was also confirmed in gingival tissue by reverse transcription-polymerase chain reaction (RT-PCR). These findings indicate that HGF is synthesized and activated in gingiva that is clinically healthy or associated with periodontitis.

Pigmented ameloblastic fibro-odontoma with melanophages

A case of pigmented ameloblastic fibro-odontoma in the mandible of a 9-year-old Japanese girl is reported. In this tumor, melanin was widely distributed in the nests of the odontogenic epithelial component, and an aggregation of large round melanophages with a large amount of melanin similar to nevus cells was observed in the areas of the connective tissue component. A considerable number of dendritic cells that were considered to be melanocytes were scattered in the epithelial nests. This is the first case of pigmented odontogenic tumor that showed such extensive pigmentation with an aggregation of melanophages.

Histomorphometric analysis of age changes in the human inferior alveolar artery

Angiography is often used to investigate age-related changes in the inferior alveolar artery, the major nutrient artery of the mandible. Although histological examinations have been made from several viewpoints, e.g. age change, pathogenesis of osteoradionecrosis, and relation to tooth extraction, these studies have used a limited number of samples and simple histometric methods. The purpose here was to describe histopathological and histomorphometric age-related changes, and to investigate the relation between dentate status and the histomorphometry of the artery. Inferior alveolar arteries from 162 autopsy cases (age range 3-86 years) were examined histometrically with a mathematically standardized method. Histologically, there was diffuse fibrous intimal thickening, but no atheroma formation. Histometric analyses revealed a very gradual increase in both the radius of the artery and the thickness of the media with age, but the luminal radius did not correlate with age. Intimal thickness increased exponentially with age with very different features from those of the increase in the media. The relative radius of the lumen decreased with age after the sixth decade; this is thought to be an index for senile changes in the artery. Among the variables of arterial architecture examined, no particular difference was found between the dentate and non-dentate cases in the molar region.

A novel ameloblastoma cell line (AM-3) secretes MMP-9 in response to Wnt-3a and induces osteoclastogenesis

OBJECTIVE Ameloblastoma has a high risk of bone invasion and local recurrence. However, the mechanisms of bone invasion in ameloblastoma remain unclear. In this study, we established an experimental model for matrix metalloproteinase (MMP) induction and osteoclastogenesis using ameloblastoma-derived cells. STUDY DESIGN We established an ameloblastoma-derived cell line without viral genes and analyzed the expression of all Wnt and Frizzled members and MMPs by real-time reverse transcription-polymerase chain reaction, and analyzed the activity of MMP-2 and MMP-9 by the in-gel-gelatinase assay. RESULTS AM-3, newly established ameloblastoma-derived cells retained the morphology of primary-cultured ameloblastoma cells. AM-3 cells overexpressed the messenger RNA of Wnt-5a, Frizzled-2, MMP-2, and MMP-9 and showed the potential of osteoclastogenesis. In addition, Wnt-3a-treatment induced expression and activation of MMP-9 in AM-3 cells. CONCLUSIONS Our study suggests that AM-3 cells retained the characteristics of ameloblastoma, without acquiring typical features of cancer cells. Furthermore, Wnt signaling induced MMP-9 in ameloblastoma cells.

Expressions of junB and c‐fos are enhanced in 4‐nitroquinoline 1‐oxide‐induced rat tongue cancers

Activator protein‐1 (AP‐1) is a transcription factor activated in many tumors. Using 4‐nitroquinoline 1‐oxide (4NQO)‐induced rat tongue cancers (TC), the present study investigated the expression levels of genes that encode the components of AP‐1, the jun gene family (c‐jun, junB and junD) and the fos gene family (c‐fos, fra‐1, fra‐2 and fosB). Expression levels of junB and c‐fos mRNAs in TC were significantly elevated compared with those in epithelial tissue of control rat tongue, although only c‐fos mRNA levels tended to be elevated in dysplastic tongue epithelium. Histologically, all 4NQO‐induced rat TC were well‐differentiated squamous cell carcinomas. Immunostaining for JunB and c‐Fos proteins was positive in the nuclei of tumor cells of all TC. It is noteworthy that JunB was negative, but c‐Fos was positive in the dysplastic tongue epithelium of the 4NQO‐treated rats. Immunostaining for both proteins was negative in tongue mucosal epithelium of control rats. There were no mutations in the coding regions of either junB or c‐fos in all the TC examined. These results suggest the possibility that the expressions of junB and c‐fos were enhanced stepwise in 4NQO‐induced carcinogenesis of rat tongue, and that the coexpression of JunB and c‐Fos might play an important role in the establishment of TC.