Study type: Medical/biological study (experimental study)

Electromagnetic field stimulation of biosynthesis: changes in c-myc transcript levels during continuous and intermittent exposures. med./bio.

Published in: Bioelectrochem Bioenerg 1996; 39 (2): 215-220

Aim of study (acc. to author)

To study the in vitro effects on c-myc transcription in human cells exposed to a continuous (up to 240 hours) or intermittent (single 20 minutes exposure) electromagnetic field.

Background/further details

The c-myc transcript levels were further analysed in regard to: 1. a change to the steady state transcript levels, 2. the return to control levels, 3. the influence of a second stimulus with the same or different field strength, 4. the occurrence of a refractory period and 5. the occurrence of an "acquired tolerance".

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: 20 min or up to 240 min

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration 20 min or up to 240 min
Exposure setup
Exposure source
Setup The magnetic field was generated by a pair of coils consisting of 164 turns of 19 gauge copper wire which was wound around a 13 x 14 cm Plexiglass form with in an 8 cm space. The exposure system was placed in a µ-metal container. The flasks were placed horizontally on a Plexiglass stand in an homogeneous area of the coil. sham exposure took place simultaneously in the same incubator which was also shielded with a µ-metal container.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.8 µT - measured - -
magnetic flux density 8 µT - measured - -
magnetic flux density 80 µT - measured - -
electric field strength 11 µV/m - calculated - at 8 µT

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The continuous exposure caused a c-myc transcription peak after 20 minutes which returned to control levles in 60 minutes. In contrast the return to control levels in the intermittent exposed cells was extended three-fold.
The effect of a second electromagnetic field stimulation on the cells after an initial 20 minutes exposure was also examined. It was observed that the cells became refractory to a second stimulation at the same field strength, but that stimulation with a field of different strength produced a restimulatory response.

Study character:

Study funded by

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