Single lymphocyte analysis with a microwell array chip.

Following genomics and proteomics, cytomics, a novel method of looking at life, has emerged for analyzing large populations of cells on a single-cell basis with multiple parameters in a quantitative manner. We have developed a highly integrated live-cell microarray system for analyzing the cellular responses of individual cells using a microwell array chip that has 234,000 microwells each of which is just large enough to fit a single cell. Compared with flow cytometry and microscope-based methods, our system can analyze the history of the cellular responses of a large number of cells. We have successfully applied the system to analyze human antigen-specific B-cells and produced human monoclonal antibodies (MoAb) against hepatitis B virus surface antigen. We have also constructed a mouse system to assess hepatitis B virus-neutralization activity and have demonstrated the neutralization activity of our antibodies. Our technology should expand the horizons of cell analysis as well as enable generation of human MoAb for antibody-based therapeutics and diagnosis for infectious diseases such as hepatitis viruses.

Infection of human hepatocyte chimeric mouse with genetically engineered hepatitis B virus.

Studies of hepatitis B virus (HBV) mutants have been hampered by the lack of a small animal model with long-term infection of cloned HBV. Using a mouse model in which liver cells were highly replaced with human hepatocytes that survived over a long time with mature human hepatocyte function, we performed transmission experiments of HBV. Human serum containing HBV and the virus produced in HepG2 cell lines that transiently or stably transfected with 1.4 genome length HBV DNA were inoculated. Genetically modified e-antigen-negative mutant strain also was produced and inoculated into the mouse model. A high-level (approximately 10(10) copies/mL) viremia was observed in mice inoculated with HBV-positive human serum samples. The level of viremia tended to be high in mice with a continuously high human hepatocyte replacement index. High levels and long-lasting viremia also were observed in mice injected with the in vitro generated HBV. The viremia continued up to 22 weeks until death or killing. Passage experiments showed that the serum of these mice contained infectious HBV. Genetically engineered hepatitis B e antigen-negative mutant clone also was shown to be infectious. Lamivudine effectively reduced the level of viremia in these infected mice. In conclusion, this mouse model of HBV infection is a useful tool for the study of HBV virology and evaluation of anti-HBV drugs. Our results indicate that HBeAg is dispensable for active viral production and transmission.

A highly sensitive and quantitative telomerase activity assay with pancreatic juice is useful for diagnosis of pancreatic carcinoma without problems due to polymerase chain reaction inhibitors: analysis of 100 samples of pancreatic juice from consecutive patients.

BACKGROUND: Early detection of pancreatic carcinoma is difficult even with current diagnostic tools. Novel biomarkers and detection techniques are urgently needed. Telomerase activity is a promising diagnostic marker. However, the conventional telomeric repeat amplification protocol (TRAP) assay is not suitable for clinical application because of its complexity, time-consuming nature, and the effects of polymerase chain reaction (PCR) inhibitors in samples leading to difficulties in quantification. METHODS: The authors used a hybridization protection assay in combination with TRAP (TRAP/HPA) to investigate the effects of PCR inhibitors in pancreatic juice on quantification of telomerase activity. They analyzed 117 consecutive samples of pancreatic juice to determine the feasibility of TRAP/HPA for diagnosis of pancreatic carcinoma. RESULTS: The authors found that TRAP/HPA was 1000-fold more sensitive than the conventional TRAP assay, and that the effects of PCR inhibitors could be avoided by diluting samples. In a large analysis of pancreatic juice samples with TRAP/HPA, 17 samples were excluded from the final analysis because of insufficient follow-up periods or inadequate treatment of the samples. Relative telomerase activity (RTA) in samples from patients with pancreatic carcinoma was significantly higher in comparison to samples from patients with pancreatitis and 13 (61.9%) of 21 samples from patients with pancreatic carcinoma showed high RTA (> 4 U). Meanwhile, high RTAs were observed in 4 of 35 (11.4%) samples from patients with intraductal papillary mucinous tumor and in 1 of 40 samples (2.5%) fom patients without malignant disease. CONCLUSIONS: TRAP/HPA accurately evaluated weak telomerase activity in pancreatic juice samples without the problem due to PCR inhibitors. This large analysis of nonselected pancreatic juice samples suggested that TRAP/HPA is a promising approach for the diagnosis of pancreatic carcinoma.