[Effect of 1.8 GHz radiofrequency electromagnetic fields on gene expression of rat neurons].

OBJECTIVE: To investigate the changes of gene expression in rat neuron induced by 1.8 GHz radiofrequency electromagnetic fields (RF EMF) to screen for RF EMF-responsive genes and the effect of different exposure times and modes on the gene expression in neuron. METHODS: Total RNA was extracted immediately and purified from the primary culture of neurons after intermittent exposed or sham-exposed to a frequency of 1.8 GHz RF EMF for 24 hours at an average special absorption rate (SAR) of 2 W/kg. Affymetrix Rat Neurobiology U34 array was applied to investigate the changes of gene expression in rat neuron. Differentially expressed genes (Egr-1, Mbp and Plp) were further confirmed by semi-quantitative revere transcription polymerase chain reaction (RT PCR). The expression levels of Egr-1, Mbp and Plp were observed at different exposure times (6, 24 h) and modes (intermittent and continuous exposure). RESULTS: Among 1200 candidate genes, 24 up-regulated and 10 down-regulated genes were found by using Affymetrix microarray suite software 5.0 which are associated with multiple cellular functions (cytoskeleton, signal transduction pathway, metabolism, etc.) after functional classification. Under 24 h and 6 h intermittent exposure, Egr-1 and Plp in experiment groups showed statistic significance (P < 0.05) compared with the control groups, while expression of Mbp did not change significantly (P > 0.05). After 24 h continuous exposure, Egr-1 and Mbp in experiment groups showed statistic significance (P < 0.05) compared with the control group, while expression of Plp did not change significantly (P > 0.05). Under the same exposure mode 6 h, expression of all the 3 genes did not change significantly. Different times (6, 24 h) and modes (intermittent and continuous exposure) of exposure exerted remarkable different influences on the expression of Egr-1, Mbp, Plp genes (P < 0.01). CONCLUSION: The changes of many genes transcription were involved in the effect of 1.8 GHz RF EMF on rat neurons; Down-regulation of Egr-1 and up-regulation of Mbp, Plp indicated the negative effects of RF EMF on neurons; The effect of RF intermittent exposure on gene expression was more obvious than that of continuous exposure; The effect of 24 h RF exposure (both intermittent and continuous) on gene expression was more obvious than that of 6 h (both intermittent and continuous).

[Differential proteomic expression in human liver cells stimulated by hydroquinone].

OBJECTIVE: To explore the differential proteomic expression in human liver cells L-02 after exposure to HQ. METHODS: Subcultured L-02 cells were treated by HQ for 24 h at a 1 x 10(-4) mol/L concentration and a blank group was set as the control. Immediately after the treatment, total cellular proteins were extracted and separated by 2-DE, and the images were analyzed by PDQuest software. The experiment was totally repeated 3 times with 3 repetitions for each group every time. The well repeated spots were identified by MALDI-TOF MS and then searched in NCBI human protein database with Mascot. RESULTS: About 1,000 spots per gel were found. Compared with the control group, 17, 18 and 24 spots were significantly altered in 3 separate experiments. The 4 well repeated spots were identified by MALDI-TOF MS as Rho GDP dissociation inhibitor GDI alpha, 6-phosphogluconolactonase, erbB3 binding protein EBP1 and lamin A/C, isoform 1 precursor. They were involved in cell skeleton, signal transduction and energy metabolization in functional classification. CONCLUSION: Hydroquinone can change the protein expression in liver cells, which provides clues for exploring the toxic mechanism.

[Effect of 1.8 GHz radiofrequency electromagnetic fields on the expression of microtubule associated protein 2 in rat neurons].

OBJECTIVE: To investigate the changes of gene expression in rat neurons induced by 1.8 GHz radiofrequency electromagnetic fields (RF EMF) and to screen for the RF EMF-responsive genes. METHODS: Newly-born SD rats in 24 hours were sacrificed to obtain cortex and hippocampus neurons. The cells were divided randomly into two groups: the experiment group (the irradiation group) and the control group (the false irradiation group). In the irradiation group, after twelve days' culture, neurons were exposed to 1.8 GHz RF EMF modulated by 217 Hz at a specific absorption rate (SAR) of 2 W/kg for 24 hours (5 minutes on/10 minutes off) while in the false control group, the neurons were put in the same waveguide as in the irradiation group, but were not exposed to any irradiation. The total RNA was isolated and purified immediately after exposure. The affymetrix rat neurobiology U34 assay was used for detecting the changes in gene expression profile according to the manufacturer's instruction. RF EMF-responsive candidate gene was confirmed by using ribonuclease protection assay (RPA). RESULTS: Among 1200 candidate genes, the expression levels of 34 genes were up or down regulated. Microtubule associated protein 2 (Map2) gene was selected as the candidate and subjected to further analysis. RPA data clearly revealed that Map2 was statistically significantly up-regulated after neurons were exposed to the RF EMF (P < 0.05). CONCLUSION: The modulation of gene expression and function of Map2 as a neuron specific cytoskeleton protein is crucial to maintain the normal framework and function of neurons. The finding that 1.8 GHz RF EMF exposure increases the expression of Map2 might indicate some unknown effects of RF EMF on neurons.

[Effects of acrylamide on DNA damage in human keratinocytes].

OBJECTIVE: To investigate the toxic and DNA damaging effect of acrylamide (AA) on human keratinocytes and its mechanism. METHODS: (1) After the keratinocyte cell line HaCaT cells were exposed to AA with different concentrations for 44 hours, cell survival rate was detected by MTT method. (2) The effects of DNA damage of exposed cells were detected by comet assay. (3) After treating the cells with 2.00 mmol/L of AA plus 0.50 mmol/L of 1-aminobenzotriazole (1-ABT), an inhibitor of cytochrome P-450 enzymes (CYP-450), for 4 hours, the relationship between DNA damage and CYP-450 was studied. RESULTS: (1) Cytotoxicity measurement of AA showed that cell survival rate decreased significantly after 44-hour treatment. (2) Cytotoxicity was not detected after 4-hour AA treatment, but significant DNA damage was observed in all treatment groups, and the degree of damage increased with the concentration of AA. Moreover, the tail lengths of comet cells were in dose-effect relationship. As for cells treated by 1-ABT with 2 mmol/L AA, comet rate and tail length were 15.4% and (8.2 +/- 2.0) micro m respectively, which were decreased significantly (P < 0.01) when compared with 2 mmol/L AA treatment group [80.6% and (44.3 +/- 4.0) micro m]. CONCLUSIONS: Acrylamide has significant cytotoxicity and genotoxicity on HaCaT cells. AA-induced DNA damage may be related to the oxidative metabolite(s) of AA through CYP-450.