Epigenetic gene silencing is a novel mechanism involved in delayed manifestation of radiation-induced genomic instability in mammalian cells.

We examined mechanisms involved in delayed mutagenesis in CHO-LacZeo cells harboring the fusion gene between the bacterial LacZ and the Zeocin-resistance genes. After X irradiation, Zeocin-resistant primary colonies were isolated, and the primary clones were subjected to the secondary colony formation in the absence of Zeocin. We found that the surviving primary clones showed a significantly higher delayed mutation frequency compared with those derived from nonirradiated CHO-LacZeo cells.

Itraconazole-induced cholestasis: involvement of the inhibition of bile canalicular phospholipid translocator MDR3/ABCB4.

Biliary secretion of bile acids and phospholipids, both of which are essential components of biliary micelles, are mediated by the bile salt export pump (BSEP/ABCB11) and multidrug resistance 3 P-glycoprotein (MDR3/ABCB4), respectively, and their genetic dysfunction leads to the acquisition of severe cholestatic diseases. In the present study, we found two patients with itraconazole (ITZ)-induced cholestatic liver injury with markedly high serum ITZ concentrations. To characterize the effect of ITZ on bile formation in vivo, biliary bile acids and phospholipids were analyzed in ITZ-treated rats, and it was revealed that biliary phospholipids, rather than bile acids, were drastically reduced in the presence of clinically relevant concentrations of ITZ.