Down-regulation of poly (ADP-ribose) polymerase 1 leads to change of hydroquinone cytotoxicity in TK6 cells.

Hydroquinone (HQ), one of the most important metabolites derived from benzene, is known to be associated with acute myelogenous leukemia risk; however, its carcinogenic mechanism remains unclear. In a previous study, we found that low-level of benzene exposure down-regulated the expression of poly(ADP-ribose)polymerase 1 (PARP1). Here, we employed RNA interference to knock down PARP1 expression in TK6 cells and explored the potential role of PARP1 in HQ-induced cytotoxicity. The results showed that stable PARP1-knockdown cells were successfully constructed and more than 80% inhibition of PARP1 expression was confirmed. We found that HQ treatment of TK6 cells decreased cell viability, increased cell apoptosis, and caspase3/7 activity. Knockdown of PARP1 in HQ-treated TK6 cells prevented caspase3 activation, and increased apoptosis than that in the wild-type TK6 cells, with fully functional PARP1. The results also showed that down-regulation of PARP1 led to a decrease in cell proliferation and an enhanced susceptibility to HQ-induced cytotoxicity with concentration less than 40 µM than that in normal TK6 cells. Moreover, PARP1-knockdown TK6 cells treated with HQ displayed an increased level of DNA double-strand breaks as measured by olive tail moment. No evidence was obtained of an effect of PARP1 depletion on H2AX phosphorylation induction. Under the experimental conditions, PARP1 has a role in HQ-induced DNA damage repair rather than in long-term chromatin modifications signaled by phosphorylated H2AX.

[Detecting the isoflurane in the air of workplaces with chromatographic method].

OBJECTIVE: To establish a solvent desorption Gas chromatographic method for detecting the isoflurane in air of workplaces. METHODS: This method is based on "Standardization of methods for determination of toxic substances in workplace air". RESULTS: This method presents the linear relation with the minimum detectable limit 1.0 µg/ml and the minimum detectable concentration 0.07 mg/m(3). The precision (RSD) was 0.5% ∼ 5.0%, the mean dsorption efficiencies were 96.7% ∼ 98.9%, the absorption efficiencies were 92.1% ∼ 100%, the breakthrough volume was 3.7 mg isoflurane/100 mg active carbon. Other volatile organic solvents (Sevoflurane, Enflurane and Ethyl Alcohol) did not interfere the detection. The sample could be stored in the active carbon tube at least for 10 days. CONCLUSION: This method is meet the requirement of GBZ/T 210.4-2008 "Guide for establishing occupational health standards-Part4: Determination methods of air chemicals in workplace" and is feasible for determining the isoflurane in the air of workplaces.

[Simultaneous determination of seven chemicals of halogenated alkanes and aromatic hydrocarbons in the air of workplace by gas chromatography].

OBJECTIVE: To establish a gas chromatographic method for determination of halogenated alkanes and aromatic hydrocarbons including trichloromethane, 1,2-dichloroethane, carbon tetrachloride, benzene, toluene, ethylbenzene and xylene in the air of workplace. METHODS: After the air samples collected with activated carbon tubes and desorbed with CS(2), the target toxicants were separated with FFAP capillary columns and detected with flame ionization detector. RESULTS: The coefficient of correlation was above 0.999 and the lowest detectable concentrations were 0.2 ∼ 3.6 mg/m(3) with the RSD of 1.2% ∼ 4.6%. The desorption efficiencies was 94.9% ∼ 100.7%. CONCLUSION: The method shows lower detection limit, high accuracy and precision. It is feasible for determination of the seven halogenated alkanes and aromatic hydrocarbons in the air of workplace.