Study type: Medical/biological study (experimental study)

HSP27 phosphorylation increases after 45°C or 41°C heat shocks but not after non-thermal TDMA or GSM exposures. med./bio.

Published in: Int J Hyperthermia 2006; 22 (6): 507-519

Aim of study (acc. to author)

To determine if in vitro exposure to hyperthermia or to non-thermal radiofrequency irradiation induces changes in the heat shock protein 27 (HSP27) phosphorylation of human cell lines.

Background/further details

Five different isoforms of the heat shock protein 27 (HSP27) were considered.
Each experiment was repeated three times.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 847 MHz
Modulation type: pulsed
Exposure duration: continuous for 1, 2 or 24 h
Exposure 2: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 1, 2 or 5 h

Exposure 1

Main characteristics
Frequency 847 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 1, 2 or 24 h
Modulation
Modulation type pulsed
Additional info

TDMA

Exposure setup
Exposure source
Distance between exposed object and exposure source 292 mm
Chamber A detailed description of the radial transmission line used for exposure has been reported in several publications [Moros et al., 1998 and 1999]. The RTL was formed by two horizontal parallel conductive plates, 43 mm apart. The 6 mm thick bottom AL plate was highly thermally conductive thus minimising temperature gradients among flasks. A central conical AL antenna emitted TEM waves propagating radially outward and terminated by an annulus of RF-absorbing foam material braced by a thin lamina of perforated aluminium at 533 mm from the centre.
Setup A total of 16 T-75 culture flasks could be distributed angularly around the antenna with their centres located at a radius of 292 mm. The cell layer was between 247 and 338 mm from the centre. Each flask was dielectrically loaded with a 3 mm thick shim of alumina (Al2O3) in order to boost and homogenise the SAR distribution.
Sham exposure A sham exposure was conducted.
Additional info Cells in T-75 tissue culture flasks containing 40 ml of medium (height 5 mm) were exposed to RF radiation at 37°C or heat shock (2 h at 41°C or 30 min at 45°C). All heat shock and RF exposure conditions were analysed simultaneously along with a matched incubator control sample.
Parameters
Measurand Value Type Method Mass Remarks
SAR 5 W/kg mean measured - -

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 1, 2 or 5 h
Modulation
Modulation type pulsed
Additional info

GSM

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 3.7 W/kg mean measured - -

Reference articles

  • Moros EG et al. (1999): The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks.
  • Moros EG et al. (1998): A compact shielded exposure system for the simultaneous long-term UHF irradiation of forty small mammals: I. Electromagnetic and environmental design.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The exposure to hyperthermia (30 minutes at 45 °C acute, two hours at 45 °C chronic) significantly increased heat shock protein 27 (HSP27) phosphorylation.
No significant differences in the levels of heat shock protein 27 (HSP27) phosphorylation were observed in the exposure of HeLa S3 cells to TDMA.
The exposure of EA.hy926 cells to 900 MHz GSM did not induce significant differences in the levels of heat shock protein 27 (HSP27) phosphorylation.

Study character:

Study funded by

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