We have established the nanofabrication technique for constructing nanopillars with high aspect ratio (100-500 nm diameter and 500-5000 nm tall) inside a microchannel on a quartz chip. The size of pillars and the spacing between pillars are designed as a DNA sieving matrix for optimal analysis of large DNA fragments over a few kilobase pairs (kbp). A chip with nanopillar channel and simple cross injector was developed based on the optimal design and applied to the separation of DNA fragments (1-38 kbp) and large DNA fragments (lambda DNA, 48.5 kbp; T4 DNA, 165.6 kbp) that are difficult to separate on conventional gel electrophoresis and capillary electrophoresis without a pulsed-field technique. DNA fragments ranging from 1 to 38 kbp were separated as clear bands, and furthermore, the mixture of lambda DNA and T4 DNA was successfully separated by a 380-microm-long nanopillar channel within only 10 s even under a direct current (dc) electric field. Theoretical plate number N of the channel (380-1450 microm long) was 1000-3000 (0.7 x 10(6)-2.1 x 10(6) plates/m). A single DNA molecule observation during electrophoresis in a nanopillar channel revealed that the optimal nanopillars induced T4 DNA to form a narrow U-shaped conformation during electrophoresis whereas lambda DNA kept a rather spherical conformation. We demonstrated that, even under a dc electric field, the optimal nanopillar dimensions depend on a gyration radius of DNA molecule that made it possible to separate large DNA fragments in a short time.

Post-IFN treatment ALT and AFP levels are significantly associated with hepatocarcinogenesis. Measurement of these values is useful for predicting future HCC risk after IFN treatment. Suppression of these values after IFN therapy reduces HCC risk even in patients without HCV eradication.

An increase in the aging population is an impending problem. A large cohort study was carried out to determine the influence of aging and other factors on hepatocarcinogenesis in patients treated with interferon. Biopsy-proven 2547 chronic hepatitis C patients registered at our referral center since 1992 were included. Of these, 2166 were treated with interferon-based therapy. Incidences of hepatocellular carcinoma (HCC) associated with interferon were analyzed by Kaplan-Meier and person-years methods for an average follow-up of 7.5 years. Factors associated with HCC risk were determined by Cox proportional hazard analysis. HCC developed in 177 interferon-treated patients. The risk for HCC depended on age at primary biopsy and increased more than 15-fold after 65 years of age. Even when stratified by stage of fibrosis, the cumulative and annual incidences of HCC were significantly higher in older patients than in younger patients (P < 0.001) at the same stage of fibrosis, except for cirrhosis. Progression of fibrosis over time was significantly accelerated in older patients. The impact of viral eradication on HCC prevention was less significant in older patients than in younger patients. Multivariate analysis confirmed that age, gender, liver fibrosis, liver steatosis, total cholesterol level, fasting blood sugar level, baseline and postinterferon alpha-fetoprotein level, and virological response to interferon were independent risk factors associated with HCC. Aging was the strongest risk factor for a nonvirological response to interferon-based antiviral therapy. Conclusion: Elderly patients are at a higher risk for HCC. Hepatitis C viral eradication had a smaller effect on hepatocarcinogenesis in older patients. Patients should therefore be identified at an earlier age and treatment should be initiated. (HEPATOLOGY 2010;52:518-527) P rimary liver cancer is the third most common cause of cancer mortality worldwide, 1 and hepatocellular carcinoma (HCC) is one of the most frequent primary liver cancers.2,3 Infection with hepatitis C virus (HCV) is a common cause of chronic hepatitis, which progresses to HCC in many patients. 4 The prevalence of older patients has been increasing in Japan, and this is an impending problem in other countries where viral spread has occurred more recently. 5 The number of Americans older than 65 years is expected to double by the year 2030. 6 In Western Europe, people older than 65 years already constitute 15%-18% of the population 7 ; thus, aging patient who is chronically infected with HCV is