研究のタイプ: 医学/生物学の研究 (experimental study)

[60Hz時間変動電界のDNA損傷および細胞生存率への影響からみて電界による遺伝毒性は無視してよい] med./bio.

Effects of 60-Hz Time-Varying Electric Fields on DNA Damage and Cell Viability Support Negligible Genotoxicity of the Electric Fields.

掲載誌: JEES 2015; 15 (3): 134-141

この研究は、以前の研究で報告された60Hz時間変動電界による遺伝毒性についてさらに詳しく調べるため、対向電極装置(FED)および共面電極装置(CED)を用いてヒト口腔扁平上皮細胞株SCC25、HeLa細胞、正常初代線維芽細胞株IMR90で実験した。その結果、どちらの装置での30分ばく露実験においても、それらの細胞でのDNA二重鎖切断アポトーシスのような明らかな生物学的影響は見られなかった;CEDを用いた3日間の反復ばく露、最大144時間の連続ばく露のいずれにおいても、HeLa細胞またはIMR90細胞にDNA損傷アポトーシス誘導はなかった、と報告している。

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研究目的(著者による)

The effects of exposure of different cell lines to 60 Hz electric fields on DNA damage and cell viability should be investigated.

詳細情報

The study was based on two previous studies by the authors (Kim et al. (2012) and Kim et al. (2010)) and should clarify whether the magnetic field or the electric field had been responsible for the effects observed in the previous studies.
Human tongue squamous carcinoma cells (SCC25), human adenocarcinoma (HeLa) cells and human lung fibroblast (IMR90) were exposed to electric fields generated by two different devices: one device generated a field parallel to the surface of the culture dishes and the other device generated a perpendicular field.
SCC25 cells were exposed to the perpendicular electric field for 30 minutes. HeLa and IMR90 cells were continuously exposed to the parallel field for 10 min to 144 hours. Moreover, HeLa and IMR90 cells were exposed to the parallel field for 30 minutes per day over 1-3 consecutive days. For each exposure condition a separate unexposed control group was used.
A positive control was conducted.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 60 Hz
ばく露時間: continuous for 30 minutes
perpendicular field
ばく露2: 60 Hz
Modulation type: pulsed
ばく露時間: continuous for 10 minutes to 144 hours
parallel field
  • 電界強度: 16 kV/m maximum (at the center of the culture dish)
  • 電界強度: 10 kV/m spatial average (in the culture dish)
ばく露3: 60 Hz
Modulation type: pulsed
ばく露時間: continuous for 30 minutes/day over 1-3 days
parallel field
  • 電界強度: 16 kV/m maximum (at the center of the culture dish)
  • 電界強度: 10 kV/m spatial average (in the culture dish)

General information

for the positive control, cells were exposed to UVC radiation for 2 minutes (50 J/m2)

ばく露1

主たる特性
周波数 60 Hz
タイプ
  • electric field
波形
  • sinusoidal
ばく露時間 continuous for 30 minutes
Additional information perpendicular field
ばく露装置
ばく露の発生源/構造
  • electrode
ばく露装置の詳細 the device was composed of two facing electrodes parallel to the dishes; the powered electrode was located at the bottom surface and the four grounded electrodes were connected to a sinusoidal voltage source with a frequency of 60 Hz; for safety, the powered electrode was covered with white dielectric material with a relative permittivity of 10 and a thickness of 0.18 mm; four dishes were used at the same time for one experimental set; the direction of the electric field was perpendicular to the dish surface
パラメータ
測定量 種別 Method Mass 備考
電界強度 10 kV/m maximum 推定値 - in the medium
電界強度 750 kV/m peak - - in the air

ばく露2

主たる特性
周波数 60 Hz
タイプ
  • electric field
波形
  • pulsed
ばく露時間 continuous for 10 minutes to 144 hours
Additional information parallel field
Modulation
Modulation type pulsed
Duty cycle 25 %
Pulse type biphasic
ばく露装置
ばく露の発生源/構造
  • electrode
チャンバの詳細 CO2 incubator
ばく露装置の詳細 the device consisted of two electrodes of 2 cm width and of 12 cm length covered on the bottom side of a plane glass; the left-side electrode was powered by a bipolar voltage source and the right-side electrode was grounded; the gap distance was 1 cm; the thickness and the relative permittivity of the glass were 3 mm and 4.2, respectively; for safety, the electrodes were covered with white dielectric material with a relative permittivity of 10 and a thickness of 0.18 mm; culture dishes were located on the top of the glass so the center of the dish was at the center of the gap; three dishes were used for one experimental set; the temperature was maintained at 36.7 - 37.1°C
パラメータ
測定量 種別 Method Mass 備考
電界強度 16 kV/m maximum 計算値 - at the center of the culture dish
電界強度 10 kV/m spatial average 計算値 - in the culture dish

ばく露3

主たる特性
周波数 60 Hz
タイプ
  • electric field
波形
  • pulsed
ばく露時間 continuous for 30 minutes/day over 1-3 days
Additional information parallel field
Modulation
Modulation type pulsed
Duty cycle 25 %
Pulse type biphasic
ばく露装置
ばく露の発生源/構造
  • same setup as in E2
パラメータ
測定量 種別 Method Mass 備考
電界強度 16 kV/m maximum 計算値 - at the center of the culture dish
電界強度 10 kV/m spatial average 計算値 - in the culture dish

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

Exposure of the different cells strains to either exposure system did not cause any significant differences between exposed cells and the respective cells of the control group.
The authors conclude that exposure of different cell lines to 60 Hz electric fields does not induce DNA damages and has no effect on the cell viability. Therefore, the effects reported in the previous studies can be attributed to the magnetic field.

研究の種別:

研究助成

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