Study type: Medical/biological study (experimental study)

Effects of 2.45 GHz microwave fields on liposomes entrapping glycoenzyme ascorbate oxidase: Evidence for oligosaccharide side chain involvement. med./bio.

Published in: Bioelectromagnetics 2004; 25 (5): 338-345

Aim of study (acc. to author)

To investigate the effects of 2.45 GHz microwave exposure on ascorbate oxidase. Ascorbate oxidase is a glycoprotein. Enzyme kinetics were investigated in presence or abscence of oligosaccharide side chains. Investigation took place on enzymes entrapped in artifical liposomes or in homogenous solution.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Exposure duration: 3 min
  • SAR: 1.4 mW/g unspecified (cf. remarks) (determined by direct temperature measurement.)
Exposure 2: 2.45 GHz
Exposure duration: 3 min
  • SAR: 2.8 mW/g unspecified (cf. remarks) (determined by direct temperature measurement.)
Exposure 3: 2.45 GHz
Exposure duration: 3 min
  • SAR: 4.2 mW/g unspecified (cf. remarks) (determined by direct temperature measurement.)
Exposure 4: 2.45 GHz
Exposure duration: 3 min
  • SAR: 5.6 mW/g unspecified (cf. remarks) (determined by direct temperature measurement.)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration 3 min
Exposure setup
Exposure source
Setup Sample cuvette (12 x 12 x 42 mm³ ) containing liposomes was placed in the exposure system and a second cuvette containing empty liposomes or buffer was placed in the reference beam of the spectrophotometer.
Sham exposure A sham exposure was conducted.
Additional info Microwave and sham exposures were conducted in a modified sample beam of a spectrophotometer. The cuvette and thermoregulatory cell were adjacent parts of the dielectric substrate of the stripline.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.4 mW/g unspecified measured and calculated cf. remarks determined by direct temperature measurement.

Exposure 2

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration 3 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2.8 mW/g unspecified measured and calculated cf. remarks determined by direct temperature measurement.

Exposure 3

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration 3 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 4.2 mW/g unspecified measured and calculated cf. remarks determined by direct temperature measurement.

Exposure 4

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration 3 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 5.6 mW/g unspecified measured and calculated cf. remarks determined by direct temperature measurement.

Reference articles

  • Schönborn F et al. (2000): Design, optimization, realization, and analysis of an in vitro system for the exposure of embryonic stem cells at 1.71 GHz.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

A statistically significant decreased enzyme activity could only be observed at high SAR values of 5.6 W/kg for native ascorbate oxidase (present of oligosaccharide side chain) entrapped in liposomes. No differences were found between native and deglycated (absence of oligosaccharide side chain) enzymes in homogenous solutions. These result may suggest a crucial role of the oligosaccharide side chane of the enzyme for the observed effects. The mechanism of the observed reduction of enzyme activity remains unclear.

Study character:

Study funded by

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