Studying the protein expression in human B lymphoblastoid cells exposed to 1.8-GHz (GSM) radiofrequency radiation (RFR) with protein microarray.

In the present study, the protein microarray was used to investigate the protein expression in human B-cell lymphoblastoid cells intermittently exposed to 1.8-GHz GSM radiofrequency radiation (RFR) at the specific absorption rate (SAR) of 2.0 W/kg for 24 h. The differential expression of 27 proteins was found, which were related to DNA damage repair, apoptosis, oncogenesis, cell cycle and proliferation (ratio >1.5-fold, P<0.05). The results validated with Western blot assay indicated that the expression of RPA32 was significantly down-regulated (P<0.05) while the expression of p73 was significantly up-regulated in RFR exposure group (P<0.05). Because of the crucial roles of those proteins in DNA repair and cell apoptosis, the results of present investigation may explain the biological effects of RFR on DNA damage/repair and cell apoptosis.

Impact of 1.8-GHz radiofrequency radiation (RFR) on DNA damage and repair induced by doxorubicin in human B-cell lymphoblastoid cells.

In the present in vitro study, a comet assay was used to determine whether 1.8-GHz radiofrequency radiation (RFR, SAR of 2W/kg) can influence DNA repair in human B-cell lymphoblastoid cells exposed to doxorubicin (DOX) at the doses of 0microg/ml, 0.05microg/ml, 0.075microg/ml, 0.10microg/ml, 0.15microg/ml and 0.20microg/ml. The combinative exposures to RFR with DOX were divided into five categories. DNA damage was detected at 0h, 6h, 12h, 18h and 24h after exposure to DOX via the comet assay, and the percent of DNA in the tail (% tail DNA) served as the indicator of DNA damage. The results demonstrated that (1) RFR could not directly induce DNA damage of human B-cell lymphoblastoid cells; (2) DOX could significantly induce DNA damage of human B-cell lymphoblastoid cells with the dose-effect relationship, and there were special repair characteristics of DNA damage induced by DOX; (3) E-E-E type (exposure to RFR for 2h, then simultaneous exposure to RFR and DOX, and exposure to RFR for 6h, 12h, 18h and 24h after exposure to DOX) combinative exposure could obviously influence DNA repair at 6h and 12h after exposure to DOX for four DOX doses (0.075microg/ml, 0.10microg/ml, 0.15microg/ml and 0.20microg/ml) in human B-cell lymphoblastoid cells.

Influence of 1.8-GHz (GSM) radiofrequency radiation (RFR) on DNA damage and repair induced by X-rays in human leukocytes in vitro.

In the present study, the in vitro comet assay was used to determine whether 1.8-GHz radiofrequency radiation (RFR) can influence DNA repair in human leukocytes exposed to X-rays. The specific energy absorption rate (SAR) of 2 W/kg (the current European safety limit) was applied. The leukocytes from four young healthy donors were intermittently exposed to RFR for 24 h (fields on for 5 min, fields off for 10 min), and then irradiated with X-rays at doses of 0.25, 0.5, 1.0 and 2.0 Gy. DNA damage to human leukocytes was detected using the comet assay at 0, 15, 45, 90, 150 and 240 min after exposure to X-rays. Using the comet assay, the percent of DNA in the tail (% tail DNA) served as the indicator of DNA damage; the DNA repair percentage (DRP) served as the indicator of the DNA repair speed. The results demonstrated that (1) the DNA repair speeds of human leukocytes after X-ray exposure exhibited individual differences among the four donors; (2) the intermittent exposures of 1.8-GHz RFR at the SAR of 2 W/kg for 24 h did not directly induce DNA damage or exhibit synergistic effects with X-rays on human leukocytes.

Evaluating the combinative effects on human lymphocyte DNA damage induced by ultraviolet ray C plus 1.8 GHz microwaves using comet assay in vitro.

The objective of this study was to observe whether 1.8 GHz microwaves (MW) (SAR, 3 W/kg) exposure can influence human lymphocyte DNA damage induced by ultraviolet ray C (UVC). The lymphocytes, which were from three young healthy donors, were exposed to 254 nm UVC at the doses of 0.25, 0.5, 0.75, 1.0, 1.5 and 2.0 J m(-2), respectively. The lymphocytes were irradiated by 1.8 GHz MW (SAR, 3 W/kg) for 0, 1.5 and 4 h. The combinative exposure of UVC plus MW was conducted. The treated cells were incubated for 0, 1.5 and 4 h. Finally, comet assay was used to measure DNA damage of above treated lymphocytes. The results indicated that the difference of DNA damage induced between MW group and control group was not significant (P>0.05). The MTLs induced by UVC were 1.71+/-0.09, 2.02+/-0.08, 2.27+/-0.17, 2.27+/-0.06, 2.25+/-0.12, 2.24+/-0.11 microm, respectively, which were significantly higher than that (0.96+/-0.05 microm) of control (P<0.01). MTLs of some sub-groups in combinative exposure groups at 1.5-h incubation were significantly lower that those of corresponding UVC sub-groups (P<0.01 or P<0.05). However, MTLs of some sub-groups in combinative exposure groups at 4-h incubation were significantly higher that those of corresponding UVC sub-groups (P<0.01 or P<0.05). In this experiment it was found that 1.8 GHz (SAR, 3 W/kg) MW exposure for 1.5 and 4 h did not enhance significantly human lymphocyte DNA damage, but could reduce and increase DNA damage of human lymphocytes induced by UVC at 1.5-h and 4-h incubation, respectively.

Effects of 1.8 GHz radiofrequency field on DNA damage and expression of heat shock protein 70 in human lens epithelial cells.

To investigate the DNA damage, expression of heat shock protein 70 (Hsp70) and cell proliferation of human lens epithelial cells (hLEC) after exposure to the 1.8 GHz radiofrequency field (RF) of a global system for mobile communications (GSM). An Xc-1800 RF exposure system was used to employ a GSM signal at 1.8 GHz (217 Hz amplitude-modulated) with the output power in the specific absorption rate (SAR) of 1, 2 and 3 W/kg. After 2 h exposure to RF, the DNA damage of hLEC was accessed by comet assay at five different incubation times: 0, 30, 60, 120 and 240 min, respectively. Western blot and RT-PCR were used to determine the expression of Hsp70 in hLECs after RF exposure. The proliferation rate of cells was evaluated by bromodeoxyuridine incorporation on days 0, 1 and 4 after exposure. The results show that the difference of DNA-breaks between the exposed and sham-exposed (control) groups induced by 1 and 2 W/kg irradiation were not significant at any incubation time point (P > 0.05). The DNA damage caused by 3 W/kg irradiation was significantly increased at the times of 0 and 30 min after exposure (P < 0.05), a phenomenon that could not be seen at the time points of 60, 120 or 240 min (P > 0.05). Detectable mRNA as well as protein expression of Hsp70 was found in all groups. Exposure at SARs of 2 and 3 W/kg for 2 h exhibited significantly increased Hsp70 protein expression (P < 0.05), while no change in Hsp70 mRNA expression could be found in any of the groups (P > 0.05). No difference of the cell proliferation rate between the sham-exposed and exposed cells was found at any exposure dose tested (P > 0.05). The results indicate that exposure to non-thermal dosages of RF for wireless communications can induce no or repairable DNA damage and the increased Hsp70 protein expression in hLECs occurred without change in the cell proliferation rate. The non-thermal stress response of Hsp70 protein increase to RF exposure might be involved in protecting hLEC from DNA damage and maintaining the cellular capacity for proliferation.

Design and control of in vitro pulse modulated microwave exposure system / 生物医学工程学杂志

This paper presents the design and development of a set of microwave exposure system based on 1.8GHz mobile RF signal. This system can work on several modulation types to do microwave exposure experiment under different specific absorption rate (SAR) and prepare the way for researches in the effect exerted by the electromagnetic signal of mobile on human health. The hardware is made up of several RF instruments, waveguide and computer, and the software introduces the accomplishment of the control system and the algorithm of control.

Studying the synergistic damage effects induced by 1.8 GHz radiofrequency field radiation (RFR) with four chemical mutagens on human lymphocyte DNA using comet assay in vitro.

The aim of this investigation was to study the synergistic DNA damage effects in human lymphocytes induced by 1.8 GHz radiofrequency field radiation (RFR, SAR of 3 W/kg) with four chemical mutagens, i.e. mitomycin C (MMC, DNA crosslinker), bleomycin (BLM, radiomimetic agent), methyl methanesulfonate (MMS, alkylating agent), and 4-nitroquinoline-1-oxide (4NQO, UV-mimetic agent). The DNA damage of lymphocytes exposed to RFR and/or with chemical mutagens was detected at two incubation time (0 or 21 h) after treatment with comet assay in vitro. Three combinative exposure ways were used. Cells were exposed to RFR and chemical mutagens for 2 and 3h, respectively. Tail length (TL) and tail moment (TM) were utilized as DNA damage indexes. The results showed no difference of DNA damage indexes between RFR group and control group at 0 and 21 h incubation after exposure (P>0.05). There were significant difference of DNA damage indexes between MMC group and RFR+MMC co-exposure group at 0 and 21 h incubation after treatment (P<0.01). Also the significant difference of DNA damage indexes between 4NQO group and RFR+4NQO co-exposure group at 0 and 21 h incubation after treatment was observed (P<0.05 or P<0.01). The DNA damage in RFR+BLM co-exposure groups and RFR+MMS co-exposure groups was not significantly increased, as compared with corresponding BLM and MMS groups (P>0.05). The experimental results indicated 1.8 GHz RFR (SAR, 3 W/kg) for 2h did not induce the human lymphocyte DNA damage effects in vitro, but could enhance the human lymphocyte DNA damage effects induced by MMC and 4NQO. The synergistic DNA damage effects of 1.8 GHz RFR with BLM or MMS were not obvious.

Analysis of millimeter-wave dosimetry in cell culture dishes with finite-difference time-domain technique / 生物医学工程学杂志

Analysis is carried out on millimeter-wave (MMW) dosimetry in culture dishes used in experiments on MMW biological effects at the cellular level. Finite-difference time-domain (FDTD) technique is employed to compute the 6 mm MMW power density (PD) irradiated into cells in a typical culture dish and the MMW power absorption density (PAD) of cells, followed by the qualitative and quantitative analyses on the outcomes. Indicated in the results, distributions of MMW PD irradiated into cells and the PAD of cells are complicated with evident inhomogeneity so that MMW dosimetry varies a lot in different position whose influence on the experimental outcomes is not neglectable. Consequently, the precise determination of dosimetry is of great importance to be conducted in related experiments.

Power density analysis on millimeter waves irradiated into cell monolayers in culture dishes / 生物医学工程学杂志

Biological effects of millimeter waves (MMWs) at the cellular level are explored in experiments using culture dishes containing cell monolayers with MMW irradiated from the underneath. Analysis is carried out for culture dishes with diameters much larger than the MMW wavelength to discover the relation between the portion of the incident MMW power density (PD) irradiated into the cell monolayer and the interfering factors such as the bottom thickness of the culture dish, the MMW wavelength, and the electromagnetic parameters of the dish and culture solution. With the help of the finite-difference time-domain (FDTD) technique, another analysis is performed to display the effect of the dish geometries upon the MMW PD irradiated into the cell monolayer in a specific culture dish with a diameter similar to the MMW wavelength. The results indicate that rigorous analysis, precise measurement and accurate calculation of MMW PD are essential accompaniments for these experiments, and large-diameter culture dishes are more preferred in experiments to small-caliber ones.

Changes in gap junctional intercellular communication in rabbits lens epithelial cells induced by low power density microwave radiation / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To demonstrate the changes in gap junctional intercellular communication (GJIC) mediated by low power density microwave radiation in rabbits lens epithelial cells (LECs) and its mechanisms.</p><p><b>METHODS</b>Rabbits' eyes were exposed to 5 mW/cm(2) and 10 mW/cm(2) power densities of microwave radiation for 3 hours. The fluorescence-recovery-after-photobleaching (FRAP) method was used to determine the GJIC. The localization and function of connexin 43 in LECs was detected by laser scanning confocal microscopy.</p><p><b>RESULTS</b>The GJIC of rabbits LECs was inhibited by microwave radiation especially in the 10 mW/cm(2) irradiated samples. A decrease in connexin 43-positive staining was seen in 5 mW/cm(2) x 3 h treated LECs. Intracellular space accumulation and cytoplasmic internalization were clearly demonstrated in 10 mW/cm(2) group.</p><p><b>CONCLUSIONS</b>Low power densities microwave radiation (5 mW/cm(2) and 10 mW/cm(2)) induces damage to connexin 43 and inhibits the GJIC of rabbits LECs. These changes result in an osmotic imbalance within the lens and induce early cataract. 5 mW/cm(2) or 10 mW/cm(2) microwave radiation is cataractogenic.</p>

Electromagnetic noise blocks the gap-junctional intercellular communication suppression induced by 50 Hz magnetic field / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore whether the superposition of an electromagnetic noise can block gap-junctional intercellular communication(GJIC) suppression induced by 50 Hz 0.4 mT extremely low frequency magnetic field(ELF MF).</p><p><b>METHODS</b>Fibroblast cells of mice(NIH 3T3) were exposed to 0.4 mT ELF MF or(and) electromagnetic noise with the same intensity of MF for 24 h, and the GJIC was determined by using fluorescence recovery after photobleaching(FRAP) analysis, which was performed with a laser-scanning confocal microscope(Leica, Germany).</p><p><b>RESULTS</b>ELF MF exposure significantly inhibited GJIC with fluorescence recovery rate of 27.67% +/- 5.12% as compared with the control group(45.57% +/- 9.72%) (P < 0.01), while that of ELF MF plus noise group was (52.61% +/- 8.30%), which was significantly different from ELF MF group(P < 0.01), but not from control(P > 0.05).</p><p><b>CONCLUSION</b>Electromagnetic noise could block the GJIC suppression induced by 50 Hz 0.4 mT MF.</p>

Effects of electromagnetic noise on the enhancement of stress-activated protein kinase(SAPK) phosphorylation induced by 50 Hz magnetic fields / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the possible interference effect of electromagnetic noise exposure on phosphorylation of stress-activated protein kinase(SAPK) induced by 50 Hz magnetic field(MF).</p><p><b>METHODS</b>Chinese hamster lung(CHL) cells were exposed to sham exposure(C), 0.4 mT 50 Hz sinusoidal MF, 0.4 mT electromagnetic noise and the combined noise MF with 50 Hz MF for 3 min and 15 min respectively. After exposure, the cells were lysed, and the proteins were extracted. The SAPK and phosphorylated SAPK (activated form of SAPK) were measured indirectly by Western blot with corresponding antibodies. The percentage of phosphorylated SAPK was calculated and analyzed.</p><p><b>RESULTS</b>Exposure of cells to 50 Hz MF for 3 min and 15 min enhanced the SAPK phosphorylation. The percentage of phosphorylated SAPK were 49.3% and 57.0% respectively, and were significantly different from those of control(P < 0.05, n = 4). However, single noise MF exposure with the same intensity did not enhance the SAPK phosphorylation, the percentage of phosphorylated SAPK were 37.7% and 31.8% (P > 0.05). When cells were exposed to the combined noise MF with 50 Hz MF for 3 min, the SAPK phosphorylation was significantly inhibited (24.4%, P < 0.05); for 15 min, the SAPK phosphorylation was also decreased (39.0%), but there was no significant difference from control and 50 Hz MF exposure(P > 0.05).</p><p><b>CONCLUSION</b>Noise MF with certain intensity could inhibit the biological effect induced by 50 Hz MF.</p>

The effect of extremely low frequency magnetic fields on cytochrome oxidase subunit 1 mRNA transcription / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To clone and identify MF-1 gene which responded to extremely low frequency magnetic fields(ELF MF) in Daudi cells, and explore the response universality of MF-1 gene in several MF-sensitive cell lines, so as to provide experimental basis for revealing the mechanism of biological effects induced by magnetic field.</p><p><b>METHODS</b>The DNA fragment of MF-1 was cloned and sequenced; the mRNA level of MF-1 gene were analysed in MF-sensitive cell lines(HL-60, L1210 and CHL) by Northern blot after these cells being treated with 0.1 mT and 0.8 mT MF for 20 minutes and 24 hours, respectively.</p><p><b>RESULTS</b>The MF-1 cDNA sequence had 100% homology with cytochrome oxidase subunit 1 gene(CO1) by searching Gene Bank database; the transcription of CO1 in HL-60, L1210 and CHL cell lines which exposed to 0.1 mT and 0.8 mT MF for 20 minutes were significantly lower(0.38 +/- 0.12 and 0.37 +/- 0.04) than that of control(0.58 +/- 0.12) and so did for 24 hours exposure(0.46 +/- 0.09 and 0.45 +/- 0.09 vs 0.65 +/- 0.06) (P < 0.05).</p><p><b>CONCLUSION</b>CO1 is a MF-responsive gene. Cytochrome oxidase activity may be affected through low level of CO1 transcription by magnetic fields, thus induce bioeffects in organisms.</p>

Exposure to power-frequency magnetic fields can induce activation of P38 mitogen-activated protein kinase / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of 50 Hz power-frequency magnetic fields on signal transduction pathway of P38 mitogen-activated protein kinase (P38 MAPK), and explore the cellular signal transduction mechanism of the biological effects induced by power-frequency magnetic fields.</p><p><b>METHODS</b>Chinese hamster lung (CHL) cell line was exposed to power-frequency magnetic fields with two intensities(0.1 and 0.4 mT) for different exposure durations. The cytoplasmic protein was extracted. The phosphorylated(activated) and non-phosphorylated P38 MAPK and MKK3/MKK6 were measured by Western blotting analysis with their specific corresponding antibodies.</p><p><b>RESULTS</b>Power-frequency magnetic fields at 0.4 mT for 10 min could transitorily induce the activation of P38 MAPK and after 15 min the phosphorylation of P38 MAPK restored to control level, while 0.1 mT power-frequency magnetic fields could not induce the activation of P38 MAPK within 24 h. However, both 0.1 mT and 0.4 mT power-frequency magnetic fields could not phosphorylate(activate) the MKK3/MKK6, which is a general upstream kinase of P38 MAPK.</p><p><b>CONCLUSION</b>Power-frequency magnetic fields could transitorily activate the P38 MAPK, but not MKK3/MKK6. The activation mechanism of P38 MAPK needs to be further identified.</p>

Effects of power-frequency magnetic fields exposure on phosphorylation and enzymatic activity of stress-activated protein kinase and its upstream kinase / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of 50 Hz power-frequency magnetic fields on signal transduction pathway of stress-activated protein kinase(SAPK), and explore the cellular signal transduction mechanism of the biological effects induced by power-frequency magnetic fields.</p><p><b>METHODS</b>Chinese hamster lung(CHL) cell line was exposed to power-frequency magnetic fields with two intensities for different exposure durations. The cytoplasmic protein was extracted and the phosphorylated portion of SAPK and SEK1/MKK4 was measured with Western blotting analysis. The SAPK enzymatic activity was measured by the solid-phase kinase assay in cells exposed to power-frequency magnetic fields for 15 min.</p><p><b>RESULTS</b>Both 0.4 mT and 0.8 mT power-frequency magnetic fields could enhance the phosphorylation of SAPK in a time-relative course manner, and reached the maximum extent at 15 min, with an increase of 20% and 17% respectively. The solid-phase kinase assay showed that the enzymatic activities of SAPK were also increased, which were 2.9 +/- 0.4 and 2.1 +/- 0.9 times of control respectively. However, the duration of SAPK phosphorylation induced by 0.8 mT was longer than that of 0.4 mT, while the duration and extent of SAPK dephosphorylation was remarkably shorter than that of 0.4 mT. The power-frequency magnetic fields under equal conditions could not phosphorylate(activate) the SEK1/MKK4.</p><p><b>CONCLUSION</b>Power-frequency magnetic fields could activate the SAPK, but not SEK1/MKK4. It is suggested that power-frequency magnetic fields may activate SAPK signal transduction pathway through a kinase other than SEK1/MKK4. The activation mechanism of SAPK of power-frequency magnetic fields needs to be identified in more detail.</p>

Abnormal shift of connexin 43 gap-junction protein induced by 50 Hz electromagnetic fields in Chinese hamster lung cells / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of extremely low frequency magnetic fields(ELF MF) on the amount and localization of connexin 43(Cx43) gap-junction protein in the Chinese hamster lung(CHL) cells, and to explore the mechanism of ELF MF suppression on gap-junctional intercellular communication(GJIC).</p><p><b>METHODS</b>The cells were irradiated for 24 h with 50 Hz sinusoidal magnetic field at 0.8 mT without or with 12-O-tetrade-canoylphorbol-3-acetate(TPA), 5 ng/ml for 1 h. The localization of Cx43 proteins were performed by indirect immunofluorescence histochemical analysis and detected by confocal microscopy. The second experiment was conducted to examine the quantity of Cx43 proteins level in nuclei or cytoplasm and detected by Western blotting analysis.</p><p><b>RESULTS</b>The cells exposed to TPA for 1 h displayed less bright labelled spots in the regions of intercellular junction than the normal cells. Most of Cx43 labelled spots occurred in the cytoplasm and aggregated near the nuclei. At the same time, the amount of Cx43 protein in cytoplasm were increased[(2.03 +/- 0.89) in ELF group, (2.43 +/- 0.82) in TPA group] as compared to normal control(1.04 +/- 0.17) (P < 0.01).</p><p><b>CONCLUSION</b>Inhibition on GJIC function by ELF MF alone or combined with TPA may be related with the shift of Cx43 from the regions of intercellular junction to the cytoplasm.</p>

Effect of low-intensity microwave of on mitomycin C-induced genotoxicity in vitro / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study that low-intensity microwave whether or not enhances the genotoxic effects of mitomycin C(MMC) on human lymphocytes.</p><p><b>METHODS</b>Single strand DNA breaks and chromosomal aberrations were measured by comet assay and cytokinesis-blocked micronucleus(CBMN) test in vitro when human lymphocytes were exposed to 2,450-MHz microwave (5.0 mW/cm2) alone and in combination with mitomycin C.</p><p><b>RESULTS</b>In the comet assay, the average comet lengths of microwave group[(29.1 +/- 8.1) micron in male and (25.9 +/- 7.5) micron in female] were not significantly different from those of control groups [(26.3 +/- 6.6) and (24.1 +/- 4.3) micron respectively] (P > 0.05). The average comet lengths of MMC group(0.0125, 0.0250, 0.0500, 0.1000 microgram/ml) were significantly longer than those of control groups (P < 0.01) and were increased with the dose of MMC. The average comet lengths of microwave combined with MMC (MW + MMC) also were increased with the doses of MMC and were significantly longer than those of control groups (P < 0.01). When MMC was > or = 0.0250 microgram/ml, microwave and MMC synergistically increased the single strand DNA breaks. In the micronucleus test, the average micronucleus rates of microwave groups were not higher than those of control groups (P > 0.05). The average micronucleus rates of MMC groups and MW + MMC groups were significantly higher than those of control groups (P < 0.01) when MMC was > or = 0.0500 microgram/ml. The average micronucleus rates of MW + MMC groups seemed higher than those of corresponding MMC groups, however the difference was not significant (P > 0.05).</p><p><b>CONCLUSION</b>Low-intensity(2,450-MHz) microwave did not induce DNA and chromosome damages on human lymphocytes, but enhanced the effects of DNA breaks induced by MMC.</p>