研究のタイプ: 治療に関する研究 (experimental study)

[移植した悪性黒色腫細胞の成長は特定の空間・時間的j構成の低強度磁界への全身ばく露によって抑制される] med./bio.

Growth of injected melanoma cells is suppressed by whole body exposure to specific spatial-temporal configurations of weak intensity magnetic fields.

掲載誌: Int J Radiat Biol 2010; 86 (2): 79-88

この研究は、C57b雄マウスの皮下に植え付けたB16-BL6メラノーマ細胞の成長に対する低レベル磁界の影響を調べた。ばく露に用いたのはThomasパターン(15ms幅の2峰ピーク波が規則的に断続するようなパターン)をもつ磁界であり、発生方法は、1)面状ソレノイドコイルによる不均一磁界(中心で5μT);2)ヘルムホルツコイルによる均一磁界(5μT);3)2個の対向コイルによる打ち消し合った磁界(地磁気レベル5-15μT);4)2個の対向コイルに最も近い空間の強い磁界(2-5μT);5)2個の対向コイルから最も離れた空間の弱い磁界(1-5nT);6)3軸ソレノイドコイルによる空間回転磁界(2-5μT)の6条件と、擬似ばく露とケージコントロールである。その結果、特定の空間時間的構成となるよう調整された電磁界は、マウスの移植実験腫瘍の成長に影響する可能性があることが示されたと報告している。

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研究目的(著者による)

To measure the effect of exposure to a specific spatial-temporal electromagnetic field presented using different geometric configurations on the growth of experimental tumors in mice.

詳細情報

A total of 65 male mice were used. The experiment was performed in two separate blocks separated by six months to control for potential effects of the endogenous geomagnetic field: Block 1 contained 32 mice and block 2 contained 33 mice. Beginning on the day of cancer cell injection, the mice were exposed to two control (sham exposure and cage control) and six different magnetic field configurations (six groups of four mice) between 21 h and midnight (3 h) every day for 38 days.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
cylindrical field
ばく露2: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
Helmholtz coils
ばく露3: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
attenuated geomagnetic field
ばく露4: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
low intensity field
ばく露5: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
high intensity field
ばく露6: 25 Hz
Modulation type: pulsed
ばく露時間: 3 hr/day on 38 days
rotating field

ばく露1

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information cylindrical field
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997

ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 two 25 cm x 1 cm solenoids created by 1050 turns of insulated wire wound around an iron nail; solenoids separated by 20 cm: mice placed in 20 cm x 30 cm x 20 cm plastic cages in the heterogenous field between the solenoids
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 5 µT - 測定値 - at the central axis

ばく露2

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information Helmholtz coils
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997

ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 two Helmholtz coils 30 cm apart; each constructed by wrapping a 39 cm x 39 cm box with 305 m of 3 American Wire Gauge in a single layer, 18 cm wide ; mice placed in 20 cm x 30 cm x 20 cm plastic cages in the homogenous field between the coils
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 5 µT - 測定値 - -

ばく露3

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information attenuated geomagnetic field
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997

ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 two opposing double Helmholtz coils created by wrapping two 112 cm x 125 cm plastic boxes with 72 turns of 30 AWG wire in a single layer, 13 cm wide; coils placed 2 cm apart; two stainless steel shelfs for shielding of the geomagnetic field
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 5 µT minimum 測定値 - geomagnetic field
磁束密度 15 µT maximum 測定値 - geomagnetic field

ばく露4

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information low intensity field
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997

ばく露装置
ばく露の発生源/構造
  • same as E3
ばく露装置の詳細 adjacent housing area furthest from the activated coil used
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 nT minimum 測定値 - -
磁束密度 5 nT maximum 測定値 - -

ばく露5

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information high intensity field
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997

ばく露装置
ばく露の発生源/構造
  • same as E3
ばく露装置の詳細 housing area nearest to the activated coil used
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2 µT minimum 測定値 - -
磁束密度 5 µT maximum 測定値 - -

ばく露6

主たる特性
周波数 25 Hz
タイプ
  • magnetic field
ばく露時間 3 hr/day on 38 days
Additional information rotating field
Modulation
Modulation type pulsed
Additional information

Thomas pattern, for further information see Thomas et al. 1997 field for 0.5 s in each opposing solenoid within the X-, Y-, Z-plane, then for 0.5 s in all planes simultaneously

ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 three pairs of solenoids; each solenoid placed in the center of each face of a 30 cm x 30 cm x 30 cm cube;
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 2 µT minimum 測定値 - -
磁束密度 5 µT maximum 測定値 - -

Reference articles

  • Persinger MA et al. (2005): [地磁気の活動の突然の変化の大きさと強度を模擬した夜間磁界にばく露された癲癇ラットの突然死]
  • Martin LJ et al. (2004): [弱い複合磁界と薬剤との相互作用による熱刺激に対する鎮痛効果]
  • Martin LJ et al. (2003): [複雑な周波数変調パターンの磁界にばく露中の磁界の空間的非一様性は鎮痛を促進するが、一様の場合は促進しない]
  • McKay BE et al. (2000): [シータ波バーストパターン磁界へのばく露はラットでの離散的ではなく文脈的条件付け恐怖の記憶獲得および記憶固定を損なう]
  • Persinger MA et al. (1999): [1マイクロテスラの複雑磁界による辺縁てんかんラットの発作の促進]
  • St-Pierre LS et al. (1998): Experimental induction of intermale aggressive behavior in limbic epileptic rats by weak, complex magnetic fields: implications for geomagnetic activity and the modern habitat?.
  • Thomas AW et al. (1997): [陸生巻貝「セパエラ・ネモラリス」に対するパルス磁界の抗侵害受容作用]

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)

Mice exposed to the field that was rotated through the three spatial dimensions and through all three planes every two seconds (see field 6) did not grow tumors after 38 days. However, the animals in the sham exposed field and cage controls showed massive tumors after 38 days. Tumor growth was also affected by the intensity of the field, with mice exposed to a weak intensity field (1-5 nT, field 4) forming smaller tumors than animals exposed to sham exposure or high intensity (2-5 µT) fields. The mice exposed to the cylindrical field, Helmholtz field, attenuated geomagnetic field, high intensity field, or the sham exposure conditions formed large tumours that were not different from the non-handled cage controls.
Immunohistochemistry of tumors from those mice exposed to the different intensity fields suggested that alterations in leukocyte infiltration or vascularization could contribute to the differences in tumor growth.
The authors conclude that exposure to specific spatial-temporal regulated electromagnetic field configurations had potent effects on the growth of experimental tumors in mice. These effects were also dependent on the intensity and special complexity of the field pattern.

研究の種別:

研究助成

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