No abstract

These data suggest that dietary factors may not be strong determinants of prostate cancer in these Japanese men, although the increased risk associated with a high consumption of fish warrants further study.

No abstract

We confirmed infection of 2 patients with Borrelia miyamotoi in Japan by retrospective surveillance of Lyme disease patients and detection of B. miyamotoi DNA in serum samples. One patient also showed seroconversion for antibody against recombinant glycerophosphodiester phosphodiesterase of B. miyamotoi. Indigenous relapsing fever should be considered a health concern in Japan.

Ionizing radiation is a well known risk factor of thyroid cancer development, but the mechanism of radiation induced carcinogenesis is not clear. The RET/PTC oncogene, an activated form of the RET proto-oncogene, is frequently observed in papillary thyroid carcinoma (PTC); RET/PTC1, -2 and -3 are known to be the three major forms. High frequencies of RET/PTC rearrangements have been observed in radiation-associated PTC, such as those appearing post-Chernobyl or post-radiotherapy, but the rearrangement types dier between these two populations. We investigated whether a speci®c type of RET/PTC rearrangement was induced by X-rays in vivo and in vitro. In human normal thyroid tissues transplanted in scid mice, the RET/PTC1 rearrangement was predominantly detected throughout the observation period (up to 60 days) after X-ray exposure of 50 Gy. On the other hand, RET/PTC3 was detected only 7 days after X-irradiation, and no transcript of RET/PTC2 was detected. These results are supported by the results of an in vitro study. The RET/PTC1 rearrangement was preferentially induced in a dose-dependent manner by X-rays within a high dose range (10, 50 and 100 Gy) in four cell lines. On the other hand, RET/PTC3 was induced at a much lower frequency, and no induction of RET/PTC2 was observed. These results suggest that the preferential induction of the RET/PTC1 rearrangement may play an important role in the early steps of thyroid carcinogenesis induced by acute X-irradiation. Oncogene (2000) 19, 438 ± 443.