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Cho, S. I., Nam, Y. S., Chu, L. Y., Lee, J. H., Bang, J. S., Kim, H. R., et al. (2012). Extremely low-frequency magnetic fields modulate nitric oxide signaling in rat brain. Bioelectromagnetics, 33(7), 568–574.
Abstract: Our previous study has shown that an extremely low-frequency magnetic field (ELF-MF) induces nitric oxide (NO) synthesis by Ca(2+) -dependent NO synthase (NOS) in rat brain. The present study was designed to confirm that ELF-MF affects neuronal NOS (nNOS) in several brain regions and to investigate the correlation between NO and nNOS activation. The exposure of rats to a 2 mT, 60 Hz ELF-MF for 5 days resulted in increases of NO levels in parallel with cGMP elevations in the cerebral cortex, striatum, and hippocampus. Cresyl violet staining and electron microscopic evaluation revealed that there were no significant differences in the morphology and number of neurons in the cerebral cortex, striatum, and hippocampus. Differently, the numbers of nNOS-immunoreactive (IR) neurons were significantly increased in those cerebral areas in ELF-MF-exposed rats. These data suggest that the increase in NO could be due to the increased expression and activation of nNOS in cells. Based on NO signaling in physiological and pathological states, ELF-MF created by electric power systems may induce various physiological changes in modern life.
Keywords: Animals; Benzoxazines/metabolism; Brain/*cytology/metabolism/*radiation effects/ultrastructure; Cyclic GMP/metabolism; Densitometry; Electromagnetic Fields/*adverse effects; Male; Microscopy, Electron; Nitric Oxide/*metabolism; Rats; Rats, Sprague-Dawley; Signal Transduction/*radiation effects
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Christ A, K. W., Hahn EG, Honegger K, Zefferer M, Neufeld E, Rascher W, Janka R, Bautz W, Chen J, Kiefer B, Schmitt P, Hollenbach HP, Shen J, Oberle M, Szczerba D, Kam A, Guag JW, Kuster N. (2010). The Virtual Family--development of surface-based anatomical models of two adults and two children for dosimetric simulations. Phys Med Biol., 55(23-38).
Abstract: The objective of this study was to develop anatomically correct whole body human models of an adult male (34 years old), an adult female (26 years old) and two children (an 11-year-old girl and a six-year-old boy) for the optimized evaluation of electromagnetic exposure. These four models are referred to as the Virtual Family. They are based on high resolution magnetic resonance (MR) images of healthy volunteers. More than 80 different tissue types were distinguished during the segmentation. To improve the accuracy and the effectiveness of the segmentation, a novel semi-automated tool was used to analyze and segment the data. All tissues and organs were reconstructed as three-dimensional (3D) unstructured triangulated surface objects, yielding high precision images of individual features of the body. This greatly enhances the meshing flexibility and the accuracy with respect to thin tissue layers and small organs in comparison with the traditional voxel-based representation of anatomical models. Conformal computational techniques were also applied. The techniques and tools developed in this study can be used to more effectively develop future models and further improve the accuracy of the models for various applications. For research purposes, the four models are provided for free to the scientific community.
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Christ, A., Guldimann, R., Buhlmann, B., Zefferer, M., Bakker, J. F., van Rhoon, G. C., et al. (2012). Exposure of the human body to professional and domestic induction cooktops compared to the basic restrictions. Bioelectromagnetics, 33(8), 695–705.
Abstract: We investigated whether domestic and professional induction cooktops comply with the basic restrictions defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Based on magnetic field measurements, a generic numerical model of an induction cooktop was derived in order to model user exposure. The current density induced in the user was simulated for various models and distances. We also determined the exposure of the fetus and of young children. While most measured cooktops comply with the public exposure limits at the distance specified by the International Electrotechnical Commission (standard IEC 62233), the majority exceeds them at closer distances, some of them even the occupational limits. The maximum current density in the tissue of the user significantly exceeds the basic restrictions for the general public, reaching the occupational level. The exposure of the brains of young children reaches the order of magnitude of the limits for the general public. For a generic worst-case cooktop compliant with the measurement standards, the current density exceeds the 1998 ICNIRP basic restrictions by up to 24 dB or a factor of 16. The brain tissue of young children can be overexposed by 6 dB or a factor of 2. The exposure of the tissue of the central nervous system of the fetus can exceed the limits for the general public if the mother is exposed at occupational levels. This demonstrates that the methodology for testing induction cooktops according to IEC 62233 contradicts the basic restrictions. This evaluation will be extended considering the redefined basic restrictions proposed by the ICNIRP in 2010. Bioelectromagnetics 33:695-705, 2012. (c) 2012 Wiley Periodicals, Inc.
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Chu, L. Y., Lee, J. H., Nam, Y. S., Lee, Y. J., Park, W. - H., Lee, B. - C., et al. (2011). Extremely low frequency magnetic field induces oxidative stress in mouse cerebellum. Gen Physiol Biophys, 30(4), 415–421.
Abstract: We have investigated whether extremely low frequency magnetic field (ELF-MF) induces lipid peroxidation and reactive oxygen species in mouse cerebellum. After exposure to 60 Hz ELF-MF at 2.3 mT intensity for 3 hours, there was a significant increase in malondialdehyde level and hydroxyl radical. ELF-MF significantly induced concomitant increase in superoxide dismutase without alteration in glutathione peroxidase activity. While glutathione contents were not altered, ascorbic acid levels were significantly decreased by ELF-MF exposure. These results indicate that ELF-MF may induce oxidative stress in mouse cerebellum. However, the mechanism remains further to be characterized.
Keywords: Animals; Ascorbic Acid/metabolism; Cerebellum/*pathology; Glutathione Peroxidase/metabolism; Hydroxyl Radical/metabolism; Lipid Peroxidation; *Magnetic Fields; Male; Malondialdehyde/metabolism; Mice; Mice, Inbred BALB C; *Oxidative Stress; Reactive Oxygen Species
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Chung, M. - K., Kim, Y. - B., Ha, C. - S., & Myung, S. - H. (2008). Lack of a co-promotion effect of 60 Hz rotating magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in F344 rats. Bioelectromagnetics, 29(7), 539–548.
Abstract: The present study was conducted to investigate the possible effect of 60 Hz magnetic fields as promoters of brain tumors initiated transplacentally by ethylnitrosourea (ENU) in F344 rats. One hundred twenty mated animals were divided into six different groups and exposed in utero on day 18 of gestation to a single intravenous dose of either Saline (vehicle control, Group I), or ENU 10 mg/kg (Groups II-VI). In the present study, a total of 480 offspring was used. The offspring in group II were given no further treatment while the offspring in Groups III-VI were exposed to four different intensities of magnetic fields. Animals received exposure to 60 Hz magnetic field at field strengths of 0 Tesla (sham control, T1, Group III), 5 muT (T2, Group IV), 83.3 muT (T3, Group V), or 500 muT (T4, Group VI), for 21 h/day from the age of 4 weeks to the age of 32 or 42 weeks. At histopathological examination, tumors of the nervous system were seen in all the ENU-treated groups. The tumor incidence of the ENU group at 32nd and 42nd week necropsy was higher than that of the vehicle control group. The incidence of glial tumors at 42nd week necropsy was higher than the 32nd week necropsy. However, there were no differences in the tumor incidence between the sham control (T1) and ENU + magnetic field exposure groups (T2-T4). In conclusion, there was no evidence that exposure of offspring to 60 Hz at magnetic field strengths up to 500 muT to the age of 32 or 42 weeks promoted ENU-initiated brain tumors in rats.
Keywords: Animals; Brain Neoplasms/*etiology/*pathology; *Electromagnetic Fields; *Ethylnitrosourea; Female; Male; Neoplasms, Radiation-Induced/*etiology/*pathology; Rats; Rats, Inbred F344; Rotation
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