Cryptochromes are photoactive pigments in the eye that have been proposed to function as circadian photopigments. Mice lacking the cryptochrome 2 blue-light photoreceptor gene (mCry2) were tested for circadian clock-related functions. The mutant mice had a lower sensitivity to acute light induction of mPer1 in the suprachiasmatic nucleus (SCN) but exhibited normal circadian oscillations of mPer1 and mCry1 messenger RNA in the SCN. Behaviorally, the mutants had an intrinsic circadian period about 1 hour longer than normal and exhibited high-amplitude phase shifts in response to light pulses administered at circadian time 17. These data are consistent with the hypothesis that CRY2 protein modulates circadian responses in mice and suggest that cryptochromes have a role in circadian photoreception in mammals.

Background and Objectives:The clear delineation between tumor and normal tissue is ideal for real-time surgical navigation imaging. We present a novel indocyanine green (ICG) fluorescence imaging technique to visualize hepatocellular carcinoma (HCC). Methods: Ten patients with solitary HCC underwent hepatectomy between February and September 2007 at Osaka Medical Center for Cancer and Cardiovascular Diseases. ICG had been injected intravenously several days before surgery at a dose of 0.5 mg/kg body weight. After laparotomy, the liver was inspected with intraoperative ultrasonography (IOUS), and then with a near-infrared (NIR) fluorescence imaging system (PDE; Hamamatsu Photonics K.K. Hamamatsu, Japan). Results: All the 10 primary tumors showed bright fluorescent signals and could be completely removed with negative margins under the guide of PDE. In four cases (40.0%), new HCC nodules that were not detected by use of any preoperative examinations including IOUS were detected by PDE. These newly identified HCC nodules were very small in size and most of the tumors were well-differentiated HCCs. Conclusions: This novel technique is simple and safe, and is therefore considered to be a promising tool for routine intraoperative imaging during a hepatic resection and further clinical exploration for HCC.