Long-term voluntary exercise, representing habitual exercise, lowers visceral fat and alters plasma amino acid levels in mice.

OBJECTIVES: To determine the impact of long-term voluntary exercise, representing habitual exercise for the prevention of lifestyle-related diseases, on glucose, lipid, and amino acid metabolism in mice. METHODS: Twenty-four mice aged 6 weeks were divided into three groups. Two groups (16 mice) were housed individually in either cages equipped with a running wheel (8 mice, exercising, Ex-mice) or without (8 mice, sedentary, Se-mice) for 24 weeks. The remaining group (8 mice) was sacrificed at 6 weeks of age. Biomarkers related to glucose, lipid, and amino acid metabolism were examined. RESULTS: Ex-mice ran voluntarily, predominantly in the dark. The distance per day peaked at 4 weeks and then decreased until 12 weeks to around the level seen at the beginning of the experimental period, and was maintained at 4.9 ± 0.2 km/day from 12 to 24 weeks. Ex-mice showed a similar adrenal weight and vitamin C content to Se-mice but had a significantly lower body weight and higher food intake. Ex-mice also showed a higher skeletal muscle weight, a lower white adipose tissue and liver weight, associated with lower plasma leptin and insulin-like growth factor-1 levels, and a lower hepatic triglyceride content. Analysis of plasma amino acids showed that Ex-mice had significantly higher phenylalanine, tyrosine, and glutamine levels, resulting in a significantly lower Fischer's ratio. CONCLUSIONS: We present an animal model of long-term voluntary exercise under low stress. Findings related to the effects of long-term voluntary exercise on lipid, and amino acid metabolism in our mouse model indicate that such an exercise regimen may affect pathophysiological states related to appetite and behavior.

Generation of 8-hydroxydeoxyguanosine from DNA using rat liver homogenates.

In relation to carcinogenesis, aging and other pathologic conditions, urinary 8-hydroxydeoxyguanosine (8OHdG) is widely used as a marker for evaluating the effect of oxidative stress on DNA. Because no reports have described how 8OHdG is generated from DNA in vivo or by biological materials, and how it is excreted into urine, the authors investigated the generation of 8OHdG from DNA, using rat liver homogenate. Oxidatively damaged DNA samples containing different levels of 8OHdG were prepared using ultraviolet irradiation with three different concentrations of riboflavin. Following incubation of damaged DNA samples with rat liver homogenates, the generation of 8OHdG from the DNA was determined using high-performance liquid chromatography with electrochemical detection after ultrafiltration of the incubation mixtures. The generation of 8OHdG was also tested with an anti-8OHdG antibody. The quantity of 8OHdG generated from the DNA by rat liver homogenates was dependent on the 8OHdG levels in the DNA: almost all 8OHdG in the DNA was released as 8OHdG by rat liver homogenates. Generation of 8OHdG correlated with the degradation of DNA. Interestingly, the generated 8OHdG was stable in the presence of rat liver homogenates, whereas deoxyguanosine (dG) rapidly disappeared in the same conditions. Less than 1/10,000 of dG was converted to 8OHdG when dG was incubated with rat liver homogenate. Incubation of 8-hydroxyguanine with rat liver homogenates did not generate 8OHdG. These findings suggest that most of the 8OHdG in DNA is released as 8OHdG during DNA degradation and that, because of its stability, 8OHdG is excreted into urine, thus providing a convenient measure of oxidative damage to DNA.

High Prevalence of HBV in Tibet, China.

Hepatitis B virus (HBV), distributed throughout the world, is classified into seven geographically separated genotypes designated A to G. Since the prevalence of HBV infection in isolated ethnic Tibetan populations in China, and the HBV genotypes involved have been hither to remained unclear, we collected 262 blood samples from four isolated villages in the east and west regions of Tibet. The prevalence of HBV infection was estimated by EIA for HBV Ag and HBV Ab. The HBV genotypes were determined by a PCR-microwell plate hybridization method using plasma DNA. The prevalence of HBV Ag and HBV Ab positives was 19.1% (50/262 cases) and 29.0% (76/262 cases), respectively. We detected only the C genotype (20/20 cases), this being known as a predominant type of HBV among Mongoloid populations in Asia. The results revealed, for the first time, that Tibetan villagers have a high rate of infection with HBV of C genotype, in line with the available data for chronic hepatitis and liver cancer.