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α‐Tocopheral transfer protein was purified from the 10 000 × g supernatant of rat liver. Two isoforms of the transfer protein exist, of which the isoelectric points are 5.0 and 5.1 as determined by chromatofocusing. These two isoforms have the same molecular weight; both showed molecular weight of approx. 30 500 on SDS‐polyacrylamide gel electrophoresis. They cannot be distinguished from each other by amino acid composition or substrate specificity.

Connexin genes expressing gap junction proteins have tumor-suppressive effects on primary cancers with certain cell specificity, but the suppressive effects on metastatic cancers are still conflicting. In this study, we show that connexin32 (Cx32) has a strong tumor-suppressive effect on a human metastatic renal cell carcinoma cell line (Caki-1 cell). Cx32 expression in Caki-1 cells reduced in vitro malignant phenotypes of the cells such as anchorage independency and invasion capacity. Furthermore, the Cx32 expression drastically reduced the development of Caki-1 cells in nude mice. We also determined that Cx32 reduced the malignant phenotypes in Caki-1 cells mainly through the inactivation of Src signaling. Especially, Cx32-dependent inactivation of Src decreased the production of vascular epithelial growth factor (VEGF) via the suppression of signal transducers and activators of transcription 3 (Stat3) activation, and we confirmed this result using short interfering RNA. In nude mice, Cx32-transfected Caki-1 cells showed lower serum level of VEGF comparing mock transfectant, and the development of the cells in nude mice positively related to the VEGF level. These data suggest that Cx32 acts as a tumor suppressor gene in Caki-1 cells and that the tumor-suppressive effect partly depends on the inhibition of Src-Stat3-VEGF signal pathway.

It has been assumed that the agent causing BSE in cattle is a uniform strain (classical BSE); however, different neuropathological and molecular phenotypes of BSE (atypical BSE) have been recently reported. We demonstrated the successful transmission of L-type-like atypical BSE detected in Japan (BSE/JP24 isolate) to cattle. Based on the incubation period, neuropathological hallmarks, and molecular properties of the abnormal host prion protein, the characteristics of BSE/JP24 prion were apparently distinguishable from the classical BSE prion and closely resemble those of bovine amyloidotic spongiform encephalopathy prion detected in Italy.

A case of L-type-like atypical bovine spongiform encephalopathy was detected in 14-year-old Japanese black beef cattle (BSE/ JP24). To clarify the biological and biochemical properties of the prion in BSE/JP24, we performed a transmission study with wildtype mice and bovinized transgenic mice (TgBoPrP). The BSE/ JP24 prion was transmitted to TgBoPrP mice with the incubation period of 199.7 ± 3.4 days, which was shorter than that of classical BSE (C-BSE) (223.5 ± 13.5 days). Further, C-BSE was transmitted to wild-type mice with the incubation period of about 409 days, whereas BSE/JP24 prion inoculated mice showed no clinical signs up to 649 days. Severe vacuolation and a widespread and uniform distribution of PrP Sc were pathologically observed in the brain of BSE/JP24 prion affected TgBoPrP mice. The molecular weight and glycoform ratio of PrP Sc in BSE/JP24 were different from those in C-BSE, and PrP Sc in BSE/JP24 exhibited weaker proteinase K resistance than that in C-BSE. These findings revealed that the BSE/JP24 prion has distinct biological and biochemical properties reported for that of C-BSE. Interestingly, a shorter incubation period was observed at the subsequent passage of the BSE/JP24 prion to TgBoPrP mice (152.2 ± 3.1 days). This result implies that BSE/JP24 prion has newly emerged and showed the possibility that L-type BSE prion might be classified into multiple strains.

We found a high concentration (1030 pmol per pineal gland) of D-aspartic acid (D-Asp) in the pineal gland of 6-week-old Sprague-Dawley (SD) rats. The content of D-Asp decreased with age, being 210 and 33 pmol per pineal gland in 28- and 45-week-old rats respectively. The proportion of D-Asp [(D-Asp/total Asp) x 100] also decreased with age, declining from 66% to 10% between 6 and 45 weeks after birth. The proportion of D-Asp did not differ between the sexes. The concentration of D-Asp was higher at night (at 2.00 a.m. 2830 +/- 485 pmol per pineal gland) than during the day (at 10.00 a.m. 1030 +/- 200 and at 3:00 p.m. 682 +/- 194 pmol per pineal gland), suggesting that biosynthesis of D-Asp in the pineal gland occurs at night. D-Asp was found to be distributed in the cytosol of pinealocytes, but its biological role remains unclear.

Although the constitute activation of the Src family of kinases (Src) has been established as a poor prognostic factor in several types of cancer, the role of Src in renal cell carcinoma (RCC) has not been defined. This study aimed to determine whether Src could contribute to the appearance of malignant phenotypes in RCC. The role of Src in the appearance of malignant phenotypes in RCC was examined in two human renal cancer cell lines, Caki-1 from human metastatic RCC and ACHN from human primary RCC. Src activity in Caki-1 cells was higher than that in ACHN cells, and this difference corresponded to the difference of PP1 (a Src family inhibitor)-induced cytotoxicity on the two cells. The difference in cytotoxicity between the cells did not depend on cell cycle regulation but on the induction of apoptosis, and the difference in apoptosis particularly related to the reduction of the Bcl-xL level. Furthermore, in Caki-1 cells with higher Src activity, Src stimulated the production of vascular endothelial growth factor (VEGF), partially via the activation of Stat3, and the inhibition of Src activity caused a reduction of the VEGF level in serum, angiogenesis, and tumor development in a xenograft model. These results suggested that Src contributed to the appearance of malignant phenotypes in renal cancer cells, particularly due to the resistance against apoptosis by Bcl-xL and angiogenesis stimulated by Src-Stat3-VEGF signaling.

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