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

[836.55 MHzの変調無線周波電磁界にばく露したC6神経膠腫細胞および初代培養グリア細胞におけるDNA合成および細胞増殖] med./bio.

DNA synthesis and cell proliferation in C6 glioma and primary glial cells exposed to a 836.55 MHz modulated radiofrequency field

著者: Stagg RB, Thomas WJ, Jones RA, Adey WR
掲載誌: Bioelectromagnetics 1997; 18 (3): 230-236
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この研究は、変調RF電磁界がDNA合成を変化させることによって腫瘍プロモータとして作用し、結果として細胞増殖を増加させるという仮説を試験した。ラットグリア細胞の初代培養細胞および形質転換細胞（C6グリオーマ培養細胞）に、836.55MHz、パケット変調RF電磁界（電力密度0.09、0.9および9mW / cm 2；SARは、0.15〜 59mW / g）ばく露を与えた。ばく露にはTEMセルが用いられ、北米デジタルセルラー電話規格に準拠するプロトタイプのTDMA送信機により給電された。給電TEMセルおよび擬似給電TEMセルを、37℃およびCO 2濃度5％を保つ標準インキュベーターに入れた。24時間のばく露後に、 0.59-59μW/ gのSARばく露については、DNA合成アッセイを対数的増殖期および血清飢餓状態での半定量培養で行った。0.15〜15μW/ gのSARばく露については、細胞増殖は、2週間プロトコルの0,1,5,7,9,12、および14日目に、対数増殖期の細胞計数により測定した。その結果、DNA合成アッセイの結果は、2つの細胞タイプによって異なった；初代ラットグリア細胞では、対数期または血清飢餓状態のいずれの条件においても、擬似ばく露とばく露で有意差がなかった；5.9μW/ gのSAR（0.9mW / cm 2）でのRFばく露を受けたC6グリオーマ培養細胞では、[3 H]チミジン取り込みがわずかな（20〜40％）ではあるが、有意（38％）に増加した；擬似ばく露およびRFばく露での増殖曲線は、試験した全ての電力密度で、また正常グリア細胞または形質転換グリア細胞のいずれでも差がなかった； C6神経膠腫細胞の細胞倍加時間もまた有意差を示さなかった、と報告している。

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研究目的（著者による）

To examine the effect of TDMA-modulated radiofrequency at 836.55 MHz on DNA synthesis and cell proliferation in tissues of glial origin.

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: continuous for 4 and 24 h
  • 電力密度: 0.09 mW/cm² cf. remarks (slot average)
  • SAR: 0.59 µW/g cf. remarks (slot average)
  • 電力密度: 0.3 mW/cm² average over time (at 0.9 mW/cm² slot average)
  • 電力密度: 0.9 mW/cm² cf. remarks (slot average)
  • SAR: 5.9 µW/g cf. remarks (± 2.8 µW/g slot average)
  • 電力密度: 9 mW/cm² cf. remarks (slot average)
  • SAR: 59 µW/g cf. remarks (slot average)
ばく露2: 836.55 MHz
Modulation type: pulsed
ばく露時間: continuous for up to 14 days, see below
  • 電力密度: 0.09 mW/cm² cf. remarks (slot average)
  • SAR: 0.15 µW/g cf. remarks (slot average)
  • 電力密度: 0.3 mW/cm² average over time (at 0.9 mW/cm² slot average)
  • 電力密度: 0.9 mW/cm² cf. remarks (slot average)
  • SAR: 1.5 µW/g cf. remarks (± 1.0 µW/g slot average)
  • 電力密度: 9 mW/cm² cf. remarks (slot average)
  • SAR: 15 µW/g cf. remarks (slot average)

General information

For a complete description of the exposure system used for this study, see Ivaschuk et al. [1997].

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 continuous for 4 and 24 h
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33 %
Repetition frequency 50 Hz
Additional information

TDMA modulation conforming to the NADC standard
ばく露装置
ばく露の発生源／構造
チャンバの詳細 Four TEM cells were placed in two standard incubators maintained at 37 °C and 5% CO 2. TEM cells in each location were randomly used for RF and sham exposure.
ばく露装置の詳細 Cells were exposed in 48-well plates, with one stack of two plates placed on the septum of the TEM cell. The electric field vector was normal to the dishes.
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 0.09 mW/cm² cf. remarks 測定値 - slot average
SAR 0.59 µW/g cf. remarks 計算値 - slot average
電力密度 0.3 mW/cm² average over time 測定値 - at 0.9 mW/cm² slot average
電力密度 0.9 mW/cm² cf. remarks 測定値 - slot average
SAR 5.9 µW/g cf. remarks 計算値 - ± 2.8 µW/g slot average
電力密度 9 mW/cm² cf. remarks 測定値 - slot average
SAR 59 µW/g cf. remarks 計算値 - slot average
Additional parameter details

The local static field, measured with a three-axis fluxgate magnetometer, was 63 ± 10 µT at an inclination of 63° ± 20° relative to the horizontal in one incubator and 31 ± 9 µT at an inclination of 70° ± 17° in the other incubator. The ambient 60 Hz MF, measured with a gaussmeter, was 0.15 ± 0.05 µT, 0.29 ± 0.17 µT, 0.12 ± 0.02 µT, and 0.14 ± 0.09 µT rms at the location of the four TEM cells in the two incubators, respectively.

測定および計算の詳細

Modelling, calculations, and experimental assessment of SAR values of the cell monolayers in both 48-well plates and 60-mm culture dishes were performed in a collaborative study [Burkhardt et al., 1996]. The SAR values were determined in a two-step approach: First, the EMF distribution was mapped using E-field and H-field probes, and then, induced SAR values were numerically assessed for homogeneous exposure. None of the input powers (51 mW, 0.51 W, and 5.1 W slot average) produced a detectable rise in temperature.

ばく露2

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 continuous for up to 14 days, see below
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33 %
Repetition frequency 50 Hz
Additional information

TDMA modulation conforming to the NADC standard
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
ばく露装置の詳細 Cells were exposed in 60-mm culture dishes, with two groups of three stacks (three dishes to a stack) placed on the septum and on the bottom of the TEM cell. The electric field vector was normal to the dishes.
Sham exposure A sham exposure was conducted.
Additional information Unfortunately, cell harvesting times have been described and depicted in several inconsistent ways.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 0.09 mW/cm² cf. remarks 測定値 - slot average
SAR 0.15 µW/g cf. remarks 計算値 - slot average
電力密度 0.3 mW/cm² average over time 測定値 - at 0.9 mW/cm² slot average
電力密度 0.9 mW/cm² cf. remarks 測定値 - slot average
SAR 1.5 µW/g cf. remarks 計算値 - ± 1.0 µW/g slot average
電力密度 9 mW/cm² cf. remarks 測定値 - slot average
SAR 15 µW/g cf. remarks 計算値 - slot average

Reference articles

  • Ivaschuk OI et al. (1997): [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]
  • Burkhardt M et al. (1996): [ペトリ皿ばく露装置の数値計算および実験によるドシメトリ]

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:
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

Increased 3H-thymidine incorporation during acute exposure was observed, but a significant increase in cell numbers in continuously exposed cultures was not observed. DNA synthesis: sham-exposed and radiofrequency (RF)-exposed cultures of primary rat glial cells showed no significant differences. C6 glioma cells exposed to radiofrequency at 5.9 µW/g SAR exhibited small significant (20-40%) increases in 38% of 3H-thymidine incorporation experiments. Growth curves of sham and RF-exposed cultures showed no differences in either normal or transformed glial cells. Cell doubling times of C6 cells also demonstrated no significant differences that could be attributed to altered DNA synthesis rates. Under these conditions, this radiofrequency field did not increase cell proliferation of normal or transformed cultures of glial cells.

研究の種別:

研究助成

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