この研究は、磁気共鳴画像（MRI）の造影剤として用いられるガドリニウム（Gd）と超低周波電磁界（ELF-EMF）との共ばく露が正常なヒトリンパ球に与える影響を調べた。著者は、MRIスキャナから発生する勾配磁界をELF-EMFと見なして、ELF-EMFで実験したと述べている。ソレノイドコイル中心部にリンパ球の培養皿を置き、60Hz、0.8 mTに24時間または48時間、培養中にばく露した。Gd濃度は、0、0.2、0.4、0.8、1.2 mMとし、Gd単独ばく露とGd＋ELF-EMFの共ばく露について、培養終了後、小核（MN）アッセイ、トリパンブルー色素排除試験法、単細胞ゲル電気泳動法、アポトーシス分析などにより細胞毒性を検査した。その結果、Gd単独ばく露群では、濃度および培養時間に依存して、細胞生存率の低下、MN発生頻度・DNA単鎖切断・アポトーシスによる細胞死・活性酸素種産生の増加が見られた；ELF-EMFとの共ばく露群では、Gd単独により誘導される細胞死、MN頻度、オリーブテイルモーメント、アポトーシスが増加した、と報告している。
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To investigate the effects of extremely low frequency electromagnetic fields (ELF-EMF) on the toxicity of gadolinium in human lymphocytes.
The chemical element gadolinium with the atomic number 64 is used as a contrast agent in magnetic resonance imaging. Gadolinium is known to be toxic. However, the combined effects of gadolinium and extremely low frequency magnetic fields, as patients are exposed to during magnetic resonance imaging, have not been investigated by now.
Human lymphocytes were treated with different concentrations of gadolinium (0 mM (control group), 0.2 mM, 0.4 mM, 0.8 mM, 1.2 mM) while exposed to a 60 Hz magnetic field or sham exposed.
ばく露時間: continuous for up to 72 hours
|ばく露時間||continuous for up to 72 hours|
|ばく露装置の詳細||two identical, electrically coupled solenoid coils (length 0.30 m, diameter 0.15 m) were wound with 350 turns/m of number-16 bifilar magnet wire on a cylindrical acrylic support; uniformity of the magnetic field in the active exposure volume was ± 2.5%; no significant temperature variations were observed during sham exposure and magnetic field exposure (37 ± 0.5°C)|
|Sham exposure||A sham exposure was conducted.|
|Additional information||sham exposed cultures were tested before the experiments with the same exposure system but with the power supply switched off|
Lymphocytes which were treated with gadolinium showed a time-dependent and concentration-dependent significant decrease in cell viability in comparison to the control group. A combined treatment of gadolinium (0.4 mM, 0.8 mM, or 1.2 mM) and 60 Hz magnetic field resulted in a further significant decrease compared to gadolinium treatment alone. The apoptosis rate and the micronucleus formation were significantly increased in cells treated with 1.2 mM gadolinium and a 60 Hz magnetic field compared to the control group and compared to gadolinium alone. The number of DNA strand breaks was significantly increased in gadolinium treated cells (0.2 mM, 0.4 mM, or 0.8 mM) compared to the control. Furthermore, exposure to the 60 Hz magnetic field alone led to a significant increase in the number of strand breaks compared to the control. A combined treatment of gadolinium and exposure to the 60 Hz magnetic field led to a further significant increase in the number of strand breaks compared to gadolinium treatment alone.
In gadolinium treated cells (0.2 mM, 0.4 mM, or 0.8 mM), the level of reactive oxygen species was significantly increased in a concentration-dependent manner compared to the control. A combined treatment with 0.8 mM gadolinium and a 60 Hz magnetic field resulted in higher levels of reactive oxygen species in comparison to gadolinium treatment alone. An addition of N-acetylcysteine prevented this increase.
The data suggest that gadolinium induces DNA damage and apoptotic cell death in human lymphocytes and that these effects could be enhanced by extremely low frequency magnetic fields.