Medical/biological study (experimental study)

Effects of high ELF magnetic fields on enzyme-catalyzed DNA and RNA synthesis in vitro and on a cell-free DNA mismatch repair med./bio.

By: Harada S, Yamada S, Kuramata O, Gunji Y, Kawasaki M, Miyakawa T, Yonekura H, Sakurai S, Bessho K, Hosono R, Yamamoto H

Published in: Bioelectromagnetics 2001; 22 (4): 260-266

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Aim of study (acc. to author)

This study was performed to answer the question whether extremely low frequency magnetic fields can affect in vitro DNA synthesis, DNA transcription or DNA repair and therefore exert an influence on carcinogenesis.

Background/further details

Bacteriophages, DNA mismatch repair-proficient human cervical carcinoma (HeLa) cells, and E.coli were used in the so called "DNA mismatch repair assay" as abnormalities in the DNA mismatch repair system have been regarded as one of the major cause of human cancer. DNA mismatch repair is a cellular system for recognising and repairing erroneous bases sequences that can arise during DNA replication and recombination, as-well as repairing some forms of DNA damage. In this study it should be investigated whether the exposure to extremely low frequency magnetic fields could affect the human cervical carcinoma cells ability to repair the base transition in the bacteriophage lacZ gene. Loss of DNA mismatch repair was visible in mixed coloured E.coli plaques.

Endpoint

genotoxicity/mutation: DNA/RNA synthesis, DNA repair

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: 1- 15 min for DNA synthesis; 1 - 30 min for RNA synthesis	magnetic flux density: 0.25 T peak value (0.25 T - 0.5 T) magnetic flux density: 0.5 T peak value
Exposure 2: 60 Hz Exposure duration: 15 min DNA mismatch repair	magnetic flux density: 1 T peak value

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	1- 15 min for DNA synthesis; 1 - 30 min for RNA synthesis

Exposure setup

Exposure source	coil(s)
Setup	two iron cores, each with the shape of the letter E, whose two outside yokes were in contact and the middle yokes were separated by 13 mm and encircled by the coils; test tubes placed in the central gap of this field generator
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.25 T	peak value	measured	-	0.25 T - 0.5 T
magnetic flux density	0.5 T	peak value	measured	-	-

Exposure 2

Main characteristics

Frequency	60 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	15 min
Additional info	DNA mismatch repair

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 T	peak value	measured	-	-

Reference articles

Bessho K et al. (1995): Biological responses in Caenorhabditis elegans to high magnetic fields

Exposed system:

DNA/RNA
HeLa (DNA mismatch repair-proficient cell extract)

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA repair (successful DNA repair occurs as blue or white E. coli plaques, unsuccessful DNA repair as mixed colored plaques)
molecular biosynthesis: DNA/RNA synthesis (³⁵S/³H incorporation, scintillation counting)

Investigated system:

DNA/RNA
bacterium

Time of investigation:

after exposure

Main outcome of study (acc. to author)

No statistically significant effects of the exposure to extremely low frequency magnetic field were observed in neither DNA/RNA synthesis nor DNA repair.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Magnetic Health Science Foundation, Japan
Ministry of Education, Culture, Sports, Science and Technology, Japan

Delimaris J et al. (2006): Effects of pulsed electric fields on DNA of human lymphocytes
Villarini M et al. (2006): Effects of co-exposure to extremely low frequency (50 Hz) magnetic fields and xenobiotics determined in vitro by the alkaline comet assay
Wolf FI et al. (2005): 50-Hz extremely low frequency electromagnetic fields enhance cell proliferation and DNA damage: possible involvement of a redox mechanism
Belyaev IY et al. (2005): 915 MHz microwaves and 50 Hz magnetic field affect chromatin conformation and 53BP1 foci in human lymphocytes from hypersensitive and healthy persons
Lopucki M et al. (2005): Low dose magnetic fields do not cause oxidative DNA damage in human placental cotyledons in vitro
Moretti M et al. (2005): Effects of co-exposure to extremely low frequency (ELF) magnetic fields and benzene or benzene metabolites determined in vitro by the alkaline comet assay
Ivancsits S et al. (2005): Cell type-specific genotoxic effects of intermittent extremely low-frequency electromagnetic fields
Koyama S et al. (2005): Combined exposure of ELF magnetic fields and x-rays increased mutant yields compared with x-rays alone in pTN89 plasmids
Scarfi MR et al. (2005): Evaluation of genotoxic effects in human fibroblasts after intermittent exposure to 50 Hz electromagnetic fields: a confirmatory study
Luceri C et al. (2005): Extremely low-frequency electromagnetic fields do not affect DNA damage and gene expression profiles of yeast and human lymphocytes
Cridland NA et al. (1996): Effects of 50 Hz magnetic field exposure on the rate of DNA synthesis by normal human fibroblasts

Effects of high ELF magnetic fields on enzyme-catalyzed DNA and RNA synthesis in vitro and on a cell-free DNA mismatch repair med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Exposure 2

Main characteristics

Exposure setup

Parameters

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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