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

[緑色蛍光タンパクに対するマイクロ波放射の影響の証拠] med./bio.

Evidence for a specific microwave radiation effect on the green fluorescent protein.

掲載誌: Biophys J 2006; 91 (4): 1413-1423

この研究は、緑色蛍光タンパクの溶液の蛍光に対するマイクロ波放射および通常の熱の影響を比較した。マイクロ波ばく露には、入力電力250mWで動作する8.5GHzのマイクロ波アプリケータからの近傍界を用いた。マイクロ波ばく露または通常加熱の場合について、溶液温、緑色蛍光タンパクからの蛍光の強度とスペクトラムを測定した。その結果、どちらの場合も、蛍光の強度低下、スペクトラムの赤色方向へのシフトが見られた、と報告している。

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研究目的(著者による)

To compare the effect of microwave irradiation and of conventional heating on the fluorescence of green fluorescent protein (in solution).

詳細情報

An aqueous egg-white solution and a liquid crystal indicator were also used to test temperature measurement.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 8.53 GHz
Modulation type: CW
ばく露時間: intermittent, about 200 s on/off, at each of 6 decreasing power levels, for a total of 3200 s
  • 電力: 250 mW maximum (250, 200, 160, 100, 50, 20, and 250 mW)
  • SAR: 4,000 W/kg maximum (at 250 mW)
ばく露2: 8.53 GHz
Modulation type: pulsed
ばく露時間: intermittent, about 200 s on/off, at CW and each of 3 decreasing duty cycles, for a total of 1600 s
ばく露3: 250 MHz–20 GHz
Modulation type: CW
ばく露時間: continuous, with increasing frequencies, 10 s at each step, for a total of 4000 s

General information

The EGFP fluorescence was excited by a 488-nm Argon laser with its beam directed across a transparent 2-mm diameter glass pipette (with 150-µm walls) containing the sample. The temperature dependence of the EGFP fluorescence was measured by a thermocouple in close vicinity of the laser beam. In the absence of MW radiation, the sample was heated between 22 and 43°C using a water bath or a thermal resistor.

ばく露1

主たる特性
周波数 8.53 GHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 intermittent, about 200 s on/off, at each of 6 decreasing power levels, for a total of 3200 s
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • narrowband microwave applicator
Distance between exposed object and exposure source 0.25 mm
チャンバの詳細 The MW applicator was brought to a distance of 100 µm above the glass pipette in such a way that the probe's apex aimed directly at the laser illuminated region.
ばく露装置の詳細 For narrowband measurements, a special 8.5 GHz applicator was used, based on a narrow rectangular aperture microfabricated on the convex surface of the sapphire dielectric resonator. The operating frequency of the probe was 8.53 GHz, and the bandwidth with the sample present was typically 0.3 GHz.
Additional information The incident MW power was switched on and off, decreasing from 250 mW to 20 mW, and finally returning to 250 mW. In a different experiment, the MW power was varied in steps of 0.1 dBm with a dwell time of 2 s.
パラメータ
測定量 種別 Method Mass 備考
電力 250 mW maximum - - 250, 200, 160, 100, 50, 20, and 250 mW
SAR 4,000 W/kg maximum 計算値 - at 250 mW

ばく露2

主たる特性
周波数 8.53 GHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 intermittent, about 200 s on/off, at CW and each of 3 decreasing duty cycles, for a total of 1600 s
Modulation
Modulation type pulsed
Pulse width 1 µs
Additional information

pulse periods of 2, 5 and 10 µs, resulting in duty cycles of 50, 20, and 10%

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Additional information The incident MW power was switched on and off, with the duty cycle decreasing from CW to 10%.
パラメータ
測定量 種別 Method Mass 備考
電力 250 mW - - - -

ばく露3

主たる特性
周波数 250 MHz–20 GHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 continuous, with increasing frequencies, 10 s at each step, for a total of 4000 s
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • broadband microwave applicator with an unmatched 6.5-mm long coaxial tip
Distance between exposed object and exposure source 0.25 mm
Additional information The frequency was varied from 250 MHz to 20 GHz in steps of 50 MHz with a dwell time of 10 s at each step.
パラメータ
測定量 種別 Method Mass 備考
電力 250 mW - - - -

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)

A specific microwave effect on the fluorescence of the green fluorescent protein molecule which is distinguishable from conventional heating is found. In both cases the fluorescence intensity decreased, but the effect of microwave exposure on the fluorescence is stronger than expected from thermal physics considerations. Although the microwave irradiation heated the solution, the microwave-induced changes in fluorescence cannot be explained by heating alone.

研究の種別:

研究助成

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