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

[変調された836.55 MHz無線周波電磁界への神経成長因子処置されたPC12ラット褐色細胞腫細胞のばく露：c-Junおよびc-Fosの発現への影響] med./bio.

Exposure of nerve growth factor-treated PC12 rat pheochromocytoma cells to a modulated radiofrequency field at 836.55 MHz: effects on c-jun and c-fos expression

著者: Ivaschuk OI, Jones RA, Ishida-Jones T, Haggren W, Adey WR, Phillips JL
掲載誌: Bioelectromagnetics 1997; 18 (3): 223-229
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この研究は、神経成長因子を投与されたラットPC12褐色細胞腫細胞に、非熱的レベルの、変調836.55MHz電磁界（時分割多元接続方式で用いられる信号）のばく露を与え、遺伝毒性影響を調べた。信号のタイムスロット平均電力密度は0.09、0.9、および9 mW / cm 2、ばく露時間が20、40および60分間の連続ばく露と断続ばく露（20分オン/ 20分オフ：それぞれの総培養時間は20［JEIC注：正しくは40か］、60および100分となった）で実験した。並行して対照群は擬似ばく露を受けた。全細胞RNAを抽出した後、ノーザンブロット分析を用いて、すべての細胞集団における最初期遺伝子c-fosおよびc-junの発現を評価した。その結果、各電力密度での20分間ばく露後に、c-fos転写産物レベルの変化は検出されなかった（20分間以外のばく露時間では、c-fosメッセージ検出に一貫性がなかった）；c-junの転写産物レベルは、9 mW / cm2での20分間ばく露後においてのみ変化した（平均38％減少）と報告している。

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研究目的（著者による）

To determine whether exposure of NGF (nerve growth factor)-treated PC12 cells to an athermal modulated radiofrequency field at 836.55 MHz altered the expression of the immediate early genes encoding c-jun and c-fos.

詳細情報

NGF is required for the survival and development of neuronal populations in both the central and peripheral nervous system, and it influences the phenotypic characteristics of neurons in vivo and in vitro.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 836.55 MHz
Modulation type: pulsed
ばく露時間: intermittent, 20 min on/off, for 20, 60 and 100 min
  • 電力: 0.17 W average over time (0.017, 0.17 and 1.7 W)
  • 電力密度: 0.3 mW/cm² average over time (0.03, 0.3 and 3 mW/cm²)
  • 電力密度: 0.9 mW/cm² cf. remarks (0.09, 0.9 and 9 mW/cm² slot average)
  • SAR: 2.6 µW/g cf. remarks (± 1.9 µW/g slot average at 0.9 mW/cm²)

ばく露1

主たる特性
周波数 836.55 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 intermittent, 20 min on/off, for 20, 60 and 100 min
Modulation
Modulation type pulsed
Pulse width 6.67 ms
Duty cycle 33 %
Repetition frequency 50 Hz
Additional information

TDMA with π/4 DQPSK according to NADC standard
ばく露装置
ばく露の発生源／構造
チャンバの詳細 Two TEM cells of square cross section, one powered and one for sham exposure, were placed in a water-jacketed incubator maintained at 37 °C and 5% CO2.
ばく露装置の詳細 Cells were seeded on 100 mm Petri dishes with 20 ml of medium (depth of 3 mm). In most experiments, two stacks of two dishes each were placed centrally on the septum in each TEM cell, and in a few experiments, dishes were placed on both the septum and the bottom of the TEM cells in an identical fashion. The E-field was normal to the Petri dishes.
Additional information The transmitter was switched on/off at 20 min intervals for total exposures of 20, 40, and 60 min (20, 60, and 100 min total incubation times).
パラメータ
測定量 値 種別 Method Mass 備考
電力 0.17 W average over time 測定値 - 0.017, 0.17 and 1.7 W
電力密度 0.3 mW/cm² average over time 測定値 - 0.03, 0.3 and 3 mW/cm²
電力密度 0.9 mW/cm² cf. remarks 測定値 - 0.09, 0.9 and 9 mW/cm² slot average
SAR 2.6 µW/g cf. remarks 計算値 - ± 1.9 µW/g slot average at 0.9 mW/cm²
Additional parameter details

Local static magnetic field in the incubator was 31 ± 12 µT at 9 ± 28° inclination. Ambient 60 Hz magnetic field was 0.13 ± 0.02 µT rms and 0.20 ± 0.04 µT rms at the location of the exposure and sham exposure cell, respectively.

測定および計算の詳細

The RF output from the transmitter passed through an in-line wattmeter to a 1:4 splitter one port of which was used for monitoring RF power levels via bidirectional coupler, attenuator and a diode detector. The forward power port of the coupler was connected to a power meter through a thermistor mount. RF power at the TEM cell input was measured using a power meter and power sensor and matched attenuator. The power densities were based on measured input powers and the dimensions of the TEM cell. Dosimetric considerations also used in this study are presented in more detail in the reference article. The experimental conditions were simulated using the MAFIA simulation tool to calculate slot average SAR values.

Reference articles

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:
  • ばく露後

研究の主なアウトカム（著者による）

No change in c-fos transcript levels were detected after 20 min exposure at each field intensity (20 min was the only time period at which the c-fos transcript could be detected consistently). Transcript levels for c-jun were altered only after 20 min exposure (9mW/cm²).

研究の種別:

研究助成

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