In the present study, rat bone marrow (RBM) cells were cultured on dental implants. After primary culture, RBM cells were cultured on dental implants for 2 weeks with and without osteogenic factors. DNA, alkaline phosphatase activity, osteocalcin and osteopontin were measured. Biochemical analyses revealed that, on the dental implants, RBM cell differentiation into osteoblasts was induced by osteogenic factors. Dental implants with and without cultured RBM cells were implanted in the subcutaneous tissue or on the femur in syngeneic rats. Osteogenesis in the subcutaneous tissue and more extensive and faster bone formation around the femur were observed for the implants combined with cells cultured with osteogenic factors. These results demonstrated that dental implants combined with osteoblasts differentiated from RBM cells with osteogenic factors were effective for osseointegration and bone formation.

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This study assessed the clinicopathological and immunohistochemical characteristics of benign and malignant vascular lesions using Factor VIII Related-Antigen (FVIIIRAg), CD31, CD34, VEGF, Ki-67, SMA (smooth-muscle actin), and D2-40. Eighty-one cases were collected: 15 VN (vascular neoplasms) (mean age of 43.34 ± 19.45 years old, 1.2:1 male:female ratio) and 66 VA (vascular anomalies) (mean age of 45.70 ± 19.66 years old, 1.37:1 male:female ratio). Most VN and VA were located on the lips, tongue, and buccal mucosa. VN showed increased endothelial cell (EC) proliferation and VA revealed dilated vascular channels lined by flat EC. Hemangiosarcoma demonstrated clusters of epithelioid and spindle cells and expressed immunoreactivity to panendothelial cell markers (CD31, CD34, and FVIIIRAg), Ki-67, VEGF, and D2-40. CD34 is the most consistent vascular EC marker, whereas, Ki-67 and VEGF are useful in delineating VN from VA. For differential diagnosis of hemangiosarcoma, panendothelial cell markers and D2-40 is recommended.

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The purpose of the present study was to investigate the frequency of human papillomavirus (HPV) infection in the normal oral cavity of young people in Mongolia using the PCR method. Twenty-five percent of all samples (48/192) were positive for HPV infection. The positive rates of HPV infection for males and females were 22.5% (20/89) and 27.2% (28/103), respectively. Moreover, positive rates for 4 different age groups of 1-5 years old, 6-10 years old, 11-15 years old and 16-20 years old were 4.7% (2/43), 34.3% (24/70), 31.0% (18/58) and 19.0% (4/21), respectively. The frequent types of HPVs in 48 positive samples were HPV-16 (54.0%, 26/48), -4 (29.2%, 14/48), -18 (25.0%, 12/48), -1 (16.7%, 8/48), -37 (16.7%, 8/48), -11 (12.5%, 6/48), -23 (12.5%, 6/48), and -60 (12.5%, 6/48). Multiple infection of HPV was found in 37 of 48 positive samples (77.0%). It was suggested by the results of the present study that the normal oral cavities of young people in Mongolia were already infected with various types of HPVs in childhood and adolescence. Since some types of HPVs are considered related to the development of oral malignant lesions, it is necessary to conduct further studies to ascertain the outcome of HPV infection in the normal oral cavity.

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This investigation was carried out to study tumorigenesis in the tongue of athymic nude mice by painting with carcinogens such as DMBA, Trp-P-2 and ENU after mechanical scratching. Tumorigenesis in the skin of the same animals was also investigated by painting with the above-mentioned carcinogens. In athymic nude mice, severe dysplasia of the tongue was induced by a combination of mechanical trauma and applications of DMBA, and the expression pattern for PCNA indicated that dysplastic cells were more proliferative and of a higher malignant potential than those induced by applications of Trp-P-2 or ENU. Squamous cell carcinoma was produced in the skin of the same athymic nude mice by application of DMBA only, indicating that the skin of nude mice was more sensitive than the tongue to DMBA. Our results indicated that the mechanical trauma was very significant in producing oral epithelial dysplasia after application of carcinogens.

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To identify tumor-promoting genes in tongue carcinoma, we constructed a retroviral cDNA expression library from a tongue carcinoma cell line, and used it to screen transforming genes by a focus formation assay with mouse 3T3 fibroblasts. One of the cDNA inserts harvested from such cell clones turned out to encode RRAS2 with a glycine-to-aspartic acid substitution at codon 24. The oncogenic potential of RRAS2 (G24D) was further confirmed by injecting the transformed fibroblasts into athymic nude mice. Unfortunately, we failed to detect the nucleotide change corresponding to the G24D mutation in the cDNA or genomic DNA of the cell line, indicating that such change in our transforming cDNA was artificially generated in the process of library construction. Our findings, which are the first to demonstrate the activating mutation at this codon of RRAS2, may help to better understand the role of RRAS2 in human carcinogenesis.

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Spindle cell carcinoma (SPCC) is a relatively rare tumor and its histogenesis is controversial, since the spindle cell feature is often difficult to differentiate from sarcomatous lesions. We report a case of SPCC arising from the base of the tongue and its cytological and immunohistochemical findings are highlighted. Cytologically, the smear revealed two kinds of tumor cells: squamous and spindle-like cells. The spindle shaped-cells showed sarcomatous features while the atypical squamous cell nuclei were hyperchromatic with increased N/C ratio. Histopathology showed SCC and proliferation of spindle shaped cells. Histochemistry revealed a moderately dense amount of collagen fibers in the stroma. Immunohistochemically, the SCC component was positive for keratin and EMA and the spindle cell component was positive for vimentin. These results were considered to support the concept of a malignant epithelial cell undergoing metaplastic alterations. The study also suggested that a proper cytological and histological recognition of this lesion is important.

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