この研究は、C3H 10T（1/2）細胞を用いて、無線周波（RF）の3種類の変調信号（CDMA、FDMA、TDMA：いずれの信号の場合もSARは5および10 W / kg）が、がん原遺伝子Fosの発現レベルを変化させるか否かを調べた。この研究は、Goswamiらの論文（Radiat. Res. 151、300-309、1999）の検証を目的として実施された。彼らは、細胞がばく露中にプラトー期に入ったときに、CDMAおよびFDMAばく露によりFosレベルが僅かではあるが統計的に有意に上昇したこと、MycまたはJunレベルへの影響は観察されなかったことを報告した。したがって、この研究では、指数関数的成長からプラトー期への移行中のFos発現に限定し、リアルタイムポリメラーゼ連鎖反応（RT-PCR）法で分析した。血清刺激C3H 10T（1/2）細胞をFos発現の陽性対照に用いた。最終細胞数またはpH変動がFos発現に与える得る影響を吟味した。その結果、いずれのSARレベルでのいずれの変調信号へのばく露群においても、C3H 10T（1/2）細胞でのFos mRNAの発現に擬似ばく露群との有意差はなかった；したがって、Goswamiらの研究結果は再現できなかった、と報告している。
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To determine whether there was a dose-response relationship of radiofrequency irradiation on c-Fos expression by exposing cells to higher SARs.
This study was undertaken to confirm a previous work (see publication 3649) where CDMA and FDMA irradiation caused small but statistically significant increases in Fos levels as cells entered plateau phase during exposure. If radiofrequency irradiation increases Fos expression during transition from exponential to plateau phase, such a response should be dependent on the energy delivered.
In the present study, analyses were restricted to Fos expression during the transition from exponential growth to plateau phase. The effect of TDMA signal modulation in addition to those of CDMA and FDMA was also determined.
Serum-stimulated cells were used as a positive control.
| ばく露 | パラメータ |
|---|---|
|
ばく露1:
847.74 MHz
ばく露時間:
continuous for 4 days
CDMA
|
|
|
ばく露2:
835.62 MHz
ばく露時間:
continuous for 4 days
FDMA
|
|
|
ばく露3:
836.55 MHz
ばく露時間:
continuous for 4 days
|
| 周波数 | 847.74 MHz |
|---|---|
| タイプ |
|
| 特性 |
|
| ばく露時間 | continuous for 4 days |
| Additional information | CDMA |
| Modulation type | cf. additional information |
|---|---|
| Additional information |
CDMA |
| ばく露の発生源／構造 | |
|---|---|
| チャンバの詳細 | The exposure system consisted of an environmentally enclosed room containing nine radial transmission lines (RTL). A detailed description of the RTL irradiator and its environmental controls has been given in several publications (see reference articles). Each RTL was formed by two horizontal parallel conductive plates 4.3 cm apart, with a lightweight composite top plate hinged to the bottom aluminium plate (6 mm thick) providing mechanical support and minimizing temperature gradients among flasks. A central conical aluminium antenna emitted TEM waves radially outward that were terminated by an annulus of RF-absorbing foam braced by a thin lamina of perforated aluminium located 53.3 cm from the antenna's center. |
| ばく露装置の詳細 | A total of 16 T-75 culture flasks each containing 40 ml of medium (5 mm deep) were distributed angularly around the antenna with their centers located at a radius of 29.2 cm. The nominal distances of the cell layer from the antenna's center were between 24.7 and 33.8 cm. To boost and homogenize the SAR distribution, each flask was dielectrically loaded with a 3-mm-thick shim of alumina (Al2O3) ceramic that fit snugly under the skirt of the flask. |
| Sham exposure | A sham exposure was conducted. |
| Additional information | The flasks were separated into four groups: RTL shams, RTL exposed, start-of-run incubator controls (day 0), and end-of-run incubator controls (day 4). The flasks for simultaneous sham exposure were handled in the same way as the flasks exposed to RF radiation but RTLs were not connected to an RF field source. The mean temperature of the culture medium was maintained at 37 ± 0.3°C with the temperature of each RTL being monitored continuously. However, thermometric measurements revealed bell-shaped temperature profiles along orthogonal axes on the bottom of a flask exposed at 10.0 W/kg with thermal gradients as large as 0.5°C/cm, implying that the cell layer sustained a temperature distribution over a range of ± 1°C which must be taken into consideration in the experimental design and/or interpretation of results. |
| 周波数 | 835.62 MHz |
|---|---|
| タイプ |
|
| 特性 |
|
| ばく露時間 | continuous for 4 days |
| Additional information | FDMA |
| Modulation type | cf. additional information |
|---|---|
| Additional information |
FDMA |
| ばく露の発生源／構造 |
|
|---|---|
| Sham exposure | A sham exposure was conducted. |
| 周波数 | 836.55 MHz |
|---|---|
| タイプ |
|
| 特性 |
|
| ばく露時間 | continuous for 4 days |
| Additional information | TDMA |
| Modulation type | cf. additional information |
|---|---|
| Additional information |
| ばく露の発生源／構造 |
|
|---|---|
| Sham exposure | A sham exposure was conducted. |
Expression of Fos mRNA in the cells was not significantly different from that found after sham exposure at either SAR level for any signal modulation. Therefore, the data of Goswami et al. could not be confirmed.
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