[Heat impact upon the infectivity of hepatitis B virus in serum].

OBJECTIVE: This article was to explore the impact of temperature on hepatitis B virus infectivity. METHODS: HBV positive serum with a HBV DNA titer of 1.33 × 10(8) copies/ml was aliquots into 23 Ep tubes with 1.5 ml, 100 µl in one tube.15 tubes were incubated at 37, 56 and 65°C for 0, 30, 60, 120 and 600 minutes, respectively. The other 8 tubes were incubated at 98°C for 0, 5, 10 and 30 minutes, respectively. Post-treated serum at all time points were selected to infect HepG-2 cell. When 18 hours after infection, these cells were extensively washed with phosphate buffered saline. Cells were harvested after the addition of fresh culture medium to culture cells for 48 hours. HBV DNA was detected by FQ-PCR. RESULTS: HBV DNA was detected in cells that were infected by serum at 37°C and 56°C for 30, 60, 120 and 600 minutes, respectively. The titers for the cells incubated at 37°C were (4.85 ± 1.71) × 10(5), (3.85 ± 1.76) × 10(5), (1.67 ± 0.67) × 10(5), (7.86 ± 1.03) × 10(4) copies/ml, and those for the cells incubated at 56°C were (4.01 ± 0.16) × 10(5), (9.77 ± 0.97) × 10(4), (6.36 ± 0.65) × 10(4), (5.05 ± 0.24) × 10(3) copies/ml at different incubation time points. For the cells incubated at 65°C for 60 and 120 minutes, HBV DNAs were (5.15 ± 7.28) × 10(3) and (7.56 ± 10.60) × 10(2) copies/ml, respectively, which were much lower than those in the controls cells ((6.79 ± 1.48) × 10(5) copies/ml). The results of HBV DNA were different (F = 104.4, P < 0.001) in groups treated with different temperature, and results of HBV DNA were also different (F = 144.0, P < 0.001) in groups processed for different period of time. Temperature and processing time had interaction (F = 23.6, P < 0.001). After heating at 98°C for 10 minutes and boiling for 5 minutes, the HBV DNA copy number ((3.02 ± 4.26) × 10(2), (4.31 ± 6.09) × 10(2) copies/ml) in infected cells decreased by about 10 folds than that in the control group ((6.79 ± 1.48) × 10(5) copies/ml). HBV DNAs were not detected in cells that were infected by serum which was heated at 98°C for 30 minutes and boiled for 10 minutes. CONCLUSION: The infectivity of HBV serum in vitro was relatively stable at low temperature, and it would lose its infectivity in short period of time at high temperature.

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms and the risk of primary hepatocellular carcinoma (HCC) in a Chinese population.

OBJECTIVES: Methylenetetrahydrofolate reductase (MTHFR), which is expressed in the liver, may be involved in both DNA methylation and DNA synthesis. It is also indicated as a potential risk factor of liver cancer in patients with chronic liver disease. To date, no study has been conducted on MTHFR and hepatocellular carcinoma (HCC) using a population-based design. The objective of this study was to evaluate the effects of polymorphisms of the MTHFR gene on the risk of primary liver cancer and their possible effect modifications on various environmental risk factors. METHODS: A population-based case-control study was conducted in Taixing, China. MTHFR C677T and A1298C were assayed by PCR-RFLP techniques. RESULTS: The frequency of MTHFR 677 C/C wild homozygotes genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratios (ORs) for the MTHFR 677 C/T and T/T genotype were 1.66(95% CI: 1.06-2.61), 1.21(95% CI: 0.65-2.28) respectively when compared with the MTHFR 677 C/C genotype. Subjects carrying any T genotype have the increased risk of 1.55(95% CI: 1.01-2.40) for development of primary hepatocellular carcinoma. A high degree of linkage disequilibrium was observed between the C677T and A1298C polymorphisms, with the D' of 0.887 and p < 0.01. The MTHFR 677 any T genotype was suggested to have potentially more than multiplicative interactions with raw water drinking with p-value for adjusted interaction of 0.03. CONCLUSION: We observed that the MTHFR 677 C/T genotype was associated with an increased risk of primary liver cancer in a Chinese population. The polymorphism of MTHFR 677 might modify the effects of raw water drinking on the risk of primary hepatocellular carcinoma.

[A case-control study on the relationship between methyl-tetra-hydrofolic acid reductase 677 gene polymorphism and the risk of stomach cancer].

OBJECTIVE: To explore the relationship between methyl-tetra-hydrofolic acid (MTHFR) 677 gene polymorphism and the risk of stomach cancer. METHODS: A population based case-control study was conducted and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect its genotypes. RESULTS: Among cases with stomach cancer, the frequency of C/C, C/T, T/T genotype were 25.8%, 54.6%, 19.6%, compared with controls as 34.5%, 50.9%, 14.6% respectively. Using C/C genotype as reference, the OR of C/T or T/T genotype was 1.52 (95% CI: 1.04 - 2.23). 53.3% C and 46.7% T allele were distributed in stomach cancer cases, while 60.0% C and 40.0% T in controls. The OR for T allele in relation to C allele was 1.31 (1.02 - 1.69) when C allele was used as reference. In addition, the present study showed that MTHFR677 AnyT genotype might interact with smoking, moldy food intake, wheat porridge intake, eating salty food and Hp CagA infection to increase the risk of stomach cancer. No interaction was observed between MTHFR677 AnyT genotype and alcohol drinking or green tea intake. CONCLUSION: MTHFR677 AnyT genotype, might increase the risk of stomach cancer development and the genotype might also interact with other environmental risk factors to increase the risk of stomach cancer.

[A case-control study on drinking green tea and decreasing risk of cancers in the alimentary canal among cigarette smokers and alcohol drinkers].

OBJECTIVE: To explore the role of green tea in decreasing the risks of gastric cancer, liver cancer, esophageal cancer among alcohol drinkers or cigarette smokers. METHODS: A population based case-control study was conducted in Taixing, Jiangsu province. RESULTS: In Taixing city, identified cases of stomach, liver and esophageal cancers were chosen with informed consent. The numbers were 206, 204, 218 respectively. Controls were chosen from normal population having lived in the area for longer than 10 years, also with informed consent. Green tea drinking seemed to have decreased 81%, 78%, 39% risk for the development of gastric cancer, liver cancer and esophageal cancer among alcohol drinkers. It might also have decreased 16%, 43%, 31% on the risks of developing the three kinds of cancers among cigarette smokers. Interaction assessment showed that drinking green tea could significantly decrease the risk of gastric cancer and liver cancer among alcohol drinkers, with ORs of interaction item 0.23 (95% CI: 0.10 - 0.55) and 0.25 (95% CI: 0.11 - 0.57) respectively. CONCLUSION: Habit of drinking green tea seemed to have significant protective effects on the development of both gastric and liver cancer among alcohol drinkers while, green tea also having some protective effect on esophageal cancer among alcohol drinkers and on three kinds of cancers among cigarette smokers.