Medical/biological study (experimental study)

Effects of pulsed electric fields on DNA of human lymphocytes med./bio.

By: Delimaris J, Tsilimigaki S, Messini-Nicolaki N, Ziros E, Piperakis SM

Published in: Cell Biol Toxicol 2006; 22 (6): 409-415

Aim of study (acc. to author)

To study the effects of pulsed low frequency electric fields (50 Hz) on DNA of human lymphocytes of 40 men.

Background/further details

The influence of additional external factors (synergistic effects), such as hydrogen peroxide (0. 50, 100, or 150 µmol/l) and gamma radiation (0, 0.8, 2.5, or 4.2 Gy) was also determined.

Endpoint

genotoxicity/mutation: DNA damage

Exposure

- 50/60 Hz
- electric field
- signals/pulses

Exposure	Parameters
Exposure 1: 10–50 Hz Modulation type: pulsed Exposure duration: continuous for 120 min	electric field strength: 400 kV/m unspecified

Exposure 1

Main characteristics

Frequency	10–50 Hz
Type	electric field
Waveform	pulsed
Exposure duration	continuous for 120 min

Modulation

Modulation type	pulsed
Packets per second	10
Repetition frequency	50 Hz
Additional info	"decreasing sinusoidally bipolar pulses of a positive half period, with pulse frequency of 50 Hz and carrier frequency 10 Hz [Panagopoulos et al., 2000]"

Exposure setup

Exposure source	high voltage pulse generator
Chamber	Thawed lymphocytes suspended in ice cold PBS were exposed in microcentrifuge tubes at 5 ± 0.5°C.
Setup	Using network electricity, short-duration pulses were transformed into high voltage.
Additional info	Lymphocytes were also exposed to 0, 50, 100, or 150 µmol/l H₂O₂ or to 0, 0.8, 2.5, or 4.2 Gy γ radiation from a ⁶⁰Co source at a dose rate of 3.99 Gy/min after being treated or not with the pulsed electric field.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	400 kV/m	unspecified	unspecified	-	-

Additional parameter details

The induced magnetic field was very small, in the range of 4.8 Œ 10^-12 T [Panagopoulos et al., 2002].

Reference articles

Panagopoulos DJ et al. (2002): Mechanism for action of electromagnetic fields on cells
Panagopoulos DJ et al. (2000): A mechanism for action of oscillating electric fields on cells

Exposed system:

intact cell/cell culture
human lymphocytes

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage; DNA repair efficiency (comet assay)

Investigated system:

DNA/RNA
cell lysates

Time of investigation:

after exposure

Main outcome of study (acc. to author)

A significant increased DNA damage was found after exposure to the electric fields, compared to the controls. After 2 h incubation at 37°C, a proportion of damage was repaired.
Hydrogen peroxide and gamma radiation increased the DNA damage of lymphocytes exposed to pulsed electric fields according to the dose used, while the amount of the DNA repair was proportional to the damage.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Friedman J et al. (2007): Mechanism of short-term ERK activation by electromagnetic fields at mobile phone frequencies
Wahab MA et al. (2007): Elevated sister chromatid exchange frequencies in dividing human peripheral blood lymphocytes exposed to 50 Hz magnetic fields
Hone P et al. (2006): Chromatid damage in human lymphocytes is not affected by 50 Hz electromagnetic fields
Hone P et al. (2003): Possible associations between ELF electromagnetic fields, DNA damage response processes and childhood leukaemia
Robison JG et al. (2002): Decreased DNA repair rates and protection from heat induced apoptosis mediated by electromagnetic field exposure
Harada S et al. (2001): Effects of high ELF magnetic fields on enzyme-catalyzed DNA and RNA synthesis in vitro and on a cell-free DNA mismatch repair
Kindzelskii AL et al. (2000): Extremely low frequency pulsed DC electric fields promote neutrophil extension, metabolic resonance and DNA damage when phase-matched with metabolic oscillators
Scarfi MR et al. (1997): 50-Hz, 1-mT sinusoidal magnetic fields do not affect micronucleus frequency and cell proliferation in human lymphocytes from normal and Turner's syndrome subjects
Cantoni O et al. (1996): Effect of 50 Hz sinusoidal electric and/or magnetic fields on the rate of repair of DNA single strand breaks in cultured mammalian cells exposed to three different carcinogens: methylmethane sulphonate, chromate and 254 nm U.V. radiation
Cantoni O et al. (1995): The effect of 50 Hz sinusoidal electric and/or magnetic fields on the rate of repair of DNA single/double strand breaks in oxidatively injured cells
Scarfi MR et al. (1993): 50 Hz AC sinusoidal electric fields do not exert genotoxic effects (micronucleus formation) in human lymphocytes
Fiorani M et al. (1992): Electric and/or magnetic field effects on DNA structure and function in cultured human cells
Frazier ME et al. (1990): Exposure of mammalian cells to 60-Hz magnetic or electric fields: analysis of DNA repair of induced, single-strand breaks
Reese JA et al. (1988): Exposure of mammalian cells to 60-Hz magnetic or electric fields: analysis for DNA single-strand breaks
Cohen MM et al. (1986): Effect of low-level, 60-Hz electromagnetic fields on human lymphoid cells: I. Mitotic rate and chromosome breakage in human peripheral lymphocytes
Whitson GL et al. (1986): Effects of extremely low frequency (ELF) electric fields on cell growth and DNA repair in human skin fibroblasts
Nordenson I et al. (1984): Clastogenic effects in human lymphocytes of power frequency electric fields: in vivo and in vitro studies