Electrochemotherapy (ECT) is currently receiving much attention as a method that can enhance the delivery of antitumour drugs into tumour cells by electroporation. In this study, we examined the effect of cisplatin on metastatic lesions of hamster oral fibrosarcoma by administering it in association with low-voltage electrical pulses. Oral fibrosarcoma was transplanted submucosally into the cheek pouches of 80 hamsters. After transplantation, when the diameter of the metastatic lesion in the left submandibular lymph node had reached 100 mm 3 , the hamsters were divided into four groups: D+E+ group (cisplatin treatment followed by electroporation; D+E-group (cisplatin treatment); D-E+ group (electroporation without cisplatin treatment); and D-E-group (no treatment). The antitumour effect of cisplatin was marked in the D+E+ group and the metastatic lesion disappeared in some of the animals. These results showed that when ECT consisting of cisplatin plus low-voltage electroporation was applied to metastatic tumour lesions, the antitumour effect of the drug on the lesions was enhanced. Therefore, ECT would seem to be a highly-safe new method that may be of use in the treatment of metastatic tumours.

To date, more than 120 total types of HPV have been identified, and in a recent meta-analysis, HPV was confirmed as an independent risk factor for oral carcinoma. Some investigators have reported that HPV infection is related to certain factors, including the gender, age, alcohol consumption, smoking habit, sexual behavior and denture wearing. Denture wearing can lead to denture epulis, which is a hyperplasia of fibrous connective tissue caused by denture irritation. Recently, HPV infection was detected in the hyperplastic epithelium of denture fibroma, but it still has received little study. The objective of the present investigation, therefore, was to clarify the relationship between the hyperplastic epithelium of the denture epulis and HPV infection. DNA of 118 formalin-fixed, paraffin-embedded hyperplastic epithelium biopsies of epulis specimens was extracted. Firstly, HPV infection was detected by PCR using consensus primers. Secondary, PCR using HPV type-specific primers (low risk types 6 and 11; high risk types 16, 18 and 33) was done in positive PCR samples. HPV infection was also detected by in situ hybridization and immunohistochemical techniques. Eighteen (23.1 %) of the 78 cases of denture epulis were positive, and 2 (5.0 %) of the 40 cases of non-denture epulis were positive. The difference was statistically significant (p<0.05, using Fisher's exact test). The most frequent type of HPV found in the 14 positive samples was HPV 16. It seems that the hyperplastic epithelium of denture epulis is easily infected with viruses because the epithelium is exposed daily to traumatic irritation from dentures. These results suggest that the hyperplastic epithelium of denture epulis might be an important reservoir for HPV infection of the oral region where later HPV-associated diseases, such as oral cancer and other oral lesions, may develop.

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The purpose of this study was to assess the response of osteoblasts (MC3T3-E1) and fibroblasts (L929) toward an extremely low magnetic field (ELMF) exposure. The strength and frequency of the field were set to 0.4 T and 0.17 Hz, respectively. The cells were exposed to semi-confluent culture plates for 6 hours. Cell proliferation was assessed on days 1, 3, 7 and 10 after the ELMF exposure. To evaluate osteoblastic differentiation, we measured alkaline phosphatase (ALP) activities of MC3T3-E1 cells at 3, 7 and 10 days after the exposure. The effects on mineralized nodule formation was evaluated by Alizarin Red S staining at 21 day culture. The results revealed that proliferation of the MC3T3-E1 cells was stimulated 3 days after ELMF exposure, whereas that of L929 cells was not stimulated in the day 3 culture. This stimulation was not observed at 7 or 10 days in either cell. ALP activities of the MC3T3-E1 cells were significantly increased 7 and 10 days after the exposure, and calcified nodule formation was also promoted as compared to the non exposed control culture on day 21. These results suggest that osteoblasts demonstrate specific response to magnetic fields, and that bone formation can be accelerated through the stimulation of osteoblasts by ELMF.