Reproducibility and desensitization of the power frequency magnetic field effect on movement of the common cutworm Spodoptera litura

All creatures on Earth, including human beings, can be influenced by the power frequency electromagnetic field (EMF), even though the consequence and degree of the effect may vary due to regional context, species, etc. Most of the outstanding scientific achievements about the EMF effect on life have come from behavioral studies. In such studies, in contrast to the geomagnetic field or static magnetic field (MF), the oscillating MF has attracted far less attention so far. Following a previous report, to attain deep basic knowledge about the effect of an extremely low frequency (ELF) MF on animal behavior, we characterized the 60‐Hz MF‐responsive movement activity of common cutworm larvae using sophisticated experimental schemes. The MF‐exposed third instar larvae showed significantly reduced locomotive activity compared to the matching sham‐exposed larvae. Moreover, repeated MF exposure to the same larvae up to three times also showed similar behavioral responsiveness even though the extent of movement decrease was attenuated by the repetition time. These results suggest that sinusoidal power frequency MF could disrupt the normal locomotory activity of insect larvae, and the insects may show adaptive desensitization to the same MF.     

Effects of 50‐Hz magnetic field exposure on hormone secretion and apoptosis‐related gene expression in human first trimester villous trophoblasts in vitro

Evidence from epidemiological and animal studies showed that exposure to extremely low frequency magnetic fields (ELF‐MF) could produce deleterious effects on reproduction. In order to investigate the possible mechanism of MF exposure on reproductive effects, first trimester human chorionic villi at 8–10 weeks' gestation were obtained, and trophoblasts were isolated, cultured, and exposed to a 50‐Hz MF for different durations. The human chorionic gonadotropin (hCG) and progesterone in the culture medium was measured by electrochemiluminescence immunoassay. The mRNA levels of apoptosis‐related genes bcl‐2, bax, caspase‐3, p53, and fas in trophoblasts were analyzed using real‐time RT‐PCR. The results showed that exposure of trophoblasts to MF at 0.2 mT for 72 h did not affect secretion of hCG and progesterone from these cells. There was also no significant change in secretion of these hormones when trophoblasts were exposed to a 0.4 mT MF for 48 h. However, MF significantly inhibited hCG and progesterone secretion of trophoblasts after exposure for 72 h at 0.4 mT. Results of apoptosis‐related gene expression analysis showed that, within 72 h of exposure at 0.4 mT, there was no significant difference between MF exposure and control on the expression pattern of each gene. Based on results of the present experiment, it is suggested that exposure to MF for a longer duration (72 h) could inhibit secretion of hCG and progesterone by human first trimester villous trophoblasts, however, the effect might not be related to trophoblast apoptosis. Bioelectromagnetics 31:566–572, 2010. © 2010 Wiley‐Liss, Inc.     

Chronic exposure to an extremely low‐frequency magnetic field induces depression‐like behavior and corticosterone secretion without enhancement of the hypothalamic–pituitary–adrenal axis in mice

An extremely low‐frequency magnetic field (ELF‐MF) is generated by power lines and household electrical devices. Many studies have suggested an association between chronic ELF‐MF exposure and anxiety and/or depression. The mechanism of these effects is assumed to be a stress response induced by ELF‐MF exposure. However, this mechanism remains controversial. In the present study, we investigated whether chronic ELF‐MF exposure (intensity, 3 mT; total exposure, 200 h) affected emotional behavior and corticosterone synthesis in mice. ELF‐MF‐treated mice showed a significant increase in total immobility time in a forced swim test and showed latency to enter the light box in a light–dark transition test, compared with sham‐treated (control) mice. Corticosterone secretion was significantly high in the ELF‐MF‐exposed mice; however, no changes were observed in the amount of the adrenocorticotropic hormone and the expression of genes related to stress response. Quantification of the mRNA levels of adrenal corticosteroid synthesis enzymes revealed a significant reduction in Cyp17a1 mRNA in the ELF‐MF‐exposed mice. Our findings suggest the possibility that high intensity and chronic exposure to ELF‐MF induces an increase in corticosterone secretion, along with depression‐ and/or anxiety‐like behavior, without enhancement of the hypothalamic–pituitary–adrenal axis. Bioelectromagnetics 34:43–51, 2013. © 2012 Wiley Periodicals, Inc.     

Synergic effect of retinoic acid and extremely low frequency magnetic field exposure on human neuroblastoma cell line BE(2)C

The aim of the present study was to assess whether exposure to a sinusoidal extremely low frequency magnetic field (ELF‐MF; 50 Hz, 1 mT) can affect proliferation and differentiation in the human neuroblastoma cell line BE(2)C, which is representative of high risk neuroblastomas. Cells were subjected to ELF‐MF exposure in the presence or absence of a neuronal differentiating agent (all‐trans‐retinoic acid, ATRA) for 24–72 h. In each experiment, ELF‐MF‐exposed samples were compared to sham‐exposed samples. Cells exposed to ELF‐MF combined with retinoic treatment showed a decreased cellular proliferation and an increased proportion of G₀/G₁ phase cells compared to cells exposed to either treatment alone. Moreover, ELF‐MF‐ and ATRA‐treated cells showed more differentiated morphological traits (a higher neurite number/cell, an increased neurite length), together with a significant increase of mRNA levels of p21^WAF1/CIP1 and cdk5 genes, both involved in neuronal differentiation. In addition, the expression of cyp19 gene, which is involved both in neuronal differentiation and stress response, was evaluated; cyp19 gene expression was enhanced by ATRA treatment and significantly enhanced further by ELF‐MF exposure combined with ATRA. In conclusion, our data suggest that ELF‐MF exposure can strengthen ATRA effects on neuroblastoma cells. Bioelectromagnetics 31:425–433, 2010. © 2010 Wiley‐Liss, Inc.     

Extremely low-frequency magnetic fields modulate nitric oxide signaling in rat brain

Our previous study has shown that an extremely low‐frequency magnetic field (ELF‐MF) induces nitric oxide (NO) synthesis by Ca²⁺‐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. Bioelectromagnetics 33:568–574, 2012. © 2012 Wiley Periodicals, Inc.     

Survey of electromagnetic field exposure in bedrooms of residences in lower Austria

Previous investigations of exposure to electric, magnetic, or electromagnetic fields (EMF) in households were either about electricity supply EMFs or radio frequency EMFs (RF‐EMFs). We report results from spot measurements at the bedside that comprise electrostatic fields, extremely low‐frequency electric fields (ELF‐EFs), extremely low‐frequency magnetic fields (ELF‐MFs), and RF‐EMFs. Measurements were taken in 226 households throughout Lower Austria. In addition, effects of simple reduction measures (e.g., removal of clock radios or increasing their distance from the bed, turning off Digital Enhanced Cordless Telecommunication (DECT) telephone base stations) were assessed. All measurements were well below International Commission on Non‐Ionizing Radiation Protection (ICNIRP) guideline levels. Average night‐time ELF‐MFs (long‐term measurement from 10 pm to 6 am, geometric mean over households) above 100 nT were obtained in 2.3%, and RF‐EMFs above 1000 µW/m² in 7.1% of households. Highest ELF‐EFs were primarily due to lamps beside the bed (max = 166 V/m), and highest ELF‐MFs because of transformers of devices (max = 1030 nT) or high current of power lines (max = 380 nT). The highest values of RF‐EMFs were caused by DECT telephone base stations (max = 28979 µW/m²) and mobile phone base stations (max = 4872 µW/m²). Simple reduction measures resulted in an average decrease of 23 nT for ELF‐MFs, 23 V/m for ELF‐EFs, and 246 µW/m² for RF‐EMFs. A small but statistically significant correlation between ELF‐MF exposure and overall RF‐EMF levels of R = 0.16 (P = 0.008) was computed that was independent of type (flat, single family) and location (urban, rural) of houses. Bioelectromagnetics 31:200–208, 2010. © 2009 Wiley‐Liss, Inc.     

A short‐term extremely low frequency electromagnetic field exposure increases circulating leukocyte numbers and affects HPA‐axis signaling in mice

There is still uncertainty whether extremely low frequency electromagnetic fields (ELF‐EMF) can induce health effects like immunomodulation. Despite evidence obtained in vitro, an unambiguous association has not yet been established in vivo. Here, mice were exposed to ELF‐EMF for 1, 4, and 24 h/day in a short‐term (1 week) and long‐term (15 weeks) set‐up to investigate whole body effects on the level of stress regulation and immune response. ELF‐EMF signal contained multiple frequencies (20–5000 Hz) and a magnetic flux density of 10 μT. After exposure, blood was analyzed for leukocyte numbers (short‐term and long‐term) and adrenocorticotropic hormone concentration (short‐term only). Furthermore, in the short‐term experiment, stress‐related parameters, corticotropin‐releasing hormone, proopiomelanocortin (POMC) and CYP11A1 gene‐expression, respectively, were determined in the hypothalamic paraventricular nucleus, pituitary, and adrenal glands. In the short‐term but not long‐term experiment, leukocyte counts were significantly higher in the 24 h‐exposed group compared with controls, mainly represented by increased neutrophils and CD4 ± lymphocytes. POMC expression and plasma adrenocorticotropic hormone were significantly lower compared with unexposed control mice. In conclusion, short‐term ELF‐EMF exposure may affect hypothalamic‐pituitary‐adrenal axis activation in mice. Changes in stress hormone release may explain changes in circulating leukocyte numbers and composition. Bioelectromagnetics. 37:433–443, 2016. © 2016 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.     

Characterization of Levels of Extremely Low Frequency Magnetic Fields Emitted From Portable Hand‐Held Fans

This study aims to assess the levels of extremely low frequency magnetic fields (ELF‐MF) emitted from portable hand‐held fans (HHFs) and their principal frequency and to identify factors influencing these levels. We collected a total of eleven models of HHF and monitored the ELF‐MF as a function of fan speed and distance from the fan. EMDEX II was used to monitor the ELF‐MF. An SMP2 EMF‐meter equipped with a P400 field probe was used to determine the levels of ELF‐MF and the frequency spectrum. Ten of the fans, excluding only one bladeless‐fan model, emitted a high level of ELF‐MF near the source of the HHF direct‐current motor. The maximum measured level of ELF‐MF ranged from 14.07 to 218.7 µT. All measurements of the ELF‐MF taken within 10 cm from the HHFs showed values higher than 1.0 µT. ELF‐MF levels were found to decrease markedly with distance, regardless of the HHF product. The level of ELF‐MF rose noticeably with increased fan speed. The speed of and distance from the HHF significantly influenced the level of ELF‐MF. All principal frequencies ranged from 1 to 300 Hz, which falls in the typical range of ELF. Bioelectromagnetics. 2019;40:569–577. © 2019 Bioelectromagnetics Society.     

The effects of long-term exposure to extremely low-frequency magnetic fields on bone formation in ovariectomized rats

The effects of long‐term extremely low‐frequency magnetic field (ELF‐MF) exposure on bone formation and biochemical markers were investigated in ovariectomized rats. Sixty mature female Sprague–Dawley rats were randomly divided into four different groups (n = 15): (i) unexposed control (CTL); (ii) ovariectomized only (OVX); (iii) non‐ovariectomized, exposed (SHAM + ELF‐MF); and (iv) ovariectomized, exposed (OVX + ELF‐MF). The third and fourth groups were exposed to 1.5 mT ELF‐MF for 4 h a day for 6 months. Bone mineral density (BMD) was determined using dual energy X‐ray absorption (DEXA) measurements. The formation and resorption of bone were evaluated using bone‐specific alkaline phosphatase (BAP), osteocalcin, osteoprotogerin, and N‐telopeptide. After 6 months of ELF‐MF therapy, BMD values were significantly lower in the OVX group and higher in the OVX + ELF‐MF and SHAM + ELF‐MF groups than they were before therapy (P < 0.001). Although there was no significant difference in BMD values among the groups before therapy, the BMD values increased significantly after 6 months in the OVX + ELF‐MF and SHAM + ELF‐MF groups and were reduced in the OVX group compared to the CTL group (P < 0.001). The concentrations of BAP, osteocalcin, osteoprotogerin, and N‐telopeptide in the three experimental groups also changed in a significant way compared to the CTL group. The results of the present study suggest that osteoporosis can be inhibited by ELF‐MF stimulation treatments. It was also concluded that ELF‐MF may be useful in the prevention of osteoporosis in ovariectomized rats. Bioelectromagnetics 33:543–549, 2012. © 2012 Wiley Periodicals, Inc.     

Short‐term exposure to 50 Hz ELF‐EMF alters the cisplatin‐induced oxidative response in AT478 murine squamous cell carcinoma cells

The aim of this study was to assess the influence of cisplatin and an extremely low frequency electromagnetic field (ELF‐EMF) on antioxidant enzyme activity and the lipid peroxidation ratio, as well as the level of DNA damage and reactive oxygen species (ROS) production in AT478 carcinoma cells. Cells were cultured for 24 and 72 h in culture medium with cisplatin. Additionally, the cells were irradiated with 50 Hz/1 mT ELF‐EMF for 16 min using a solenoid as a source of the ELF‐EMF. The amount of ROS, superoxide dismutase (SOD) isoenzyme activity, glutathione peroxidase (GSH‐Px) activity, DNA damage, and malondialdehyde (MDA) levels were assessed. Cells that were exposed to cisplatin exhibited a significant increase in ROS and antioxidant enzyme activity. The addition of ELF‐EMF exposure to cisplatin treatment resulted in decreased ROS levels and antioxidant enzyme activity. A significant reduction in MDA concentrations was observed in all of the study groups, with the greatest decrease associated with treatment by both cisplatin and ELF‐EMF. Cisplatin induced the most severe DNA damage; however, when cells were also irradiated with ELF‐EMF, less DNA damage occurred. Exposure to ELF‐EMF alone resulted in an increase in DNA damage compared to control cells. ELF‐EMF lessened the effects of oxidative stress and DNA damage that were induced by cisplatin; however, ELF‐EMF alone was a mild oxidative stressor and DNA damage inducer. We speculate that ELF‐EMF exerts differential effects depending on the exogenous conditions. This information may be of value for appraising the pathophysiologic consequences of exposure to ELF‐EMF. Bioelectromagnetics 33:641–651, 2012. © 2012 Wiley Periodicals, Inc.     

Evaluation of Radiofrequency and Extremely Low‐Frequency Field Levels at Children's Playground Sites in Greece From 2013 to 2018

From 2013 to 2018, in‐situ measurements of radiofrequency (RF) electromagnetic fields (EMF) and extremely low‐frequency (ELF) electric and magnetic fields in 317 existing and under‐construction children's playground facilities, in 16 municipalities all over Greece, were carried out by the Greek Atomic Energy Commission (EEAE). These measurements were conducted following legislative framework established in 2009, which requires that compliance with the established exposure limits for EMFs should be verified in playground areas. The results are presented by the value of the electric field (E) and exposure ratio (Λ) for the RF EMF, as well as the value of the electric field (E) and magnetic flux density (B) for the ELF electric and magnetic fields. Statistical analysis tools were applied on measurement data and conclusions have been made, taking into consideration: (i) environment type (urban/suburban), and (ii) vicinity to any transmitting installations. Measurement results correspond to the typical EMF background levels for each environment type. Concerning the environment type, RF EMF, and ELF electric/magnetic field measurements reveal no differentiation between urban and suburban environments. Bioelectromagnetics. 2019;40:602–605. © 2019 Bioelectromagnetics Society.     

Bidirectional frequency-dependent effect of extremely low-frequency electromagnetic field on E. coli K-12

In the present work, the frequency-dependent effects of extremely low-frequency electromagnetic field (ELF EMF) on Escherichia coli K-12 growth have been studied. The frequency-dependent effects of ELF EMF have shown that it can either stimulate or inhibit the growth of microbes. However, the mechanism by which the ELF EMF affects the bacterial cells is not clear yet. It was suggested that the aqua medium can serve as a target through which the biological effect of ELF EMF on microbes may be realized. To check this hypothesis, the frequency-dependent effects (2, 4, 6, 8, 10 Hz, B = 0.4 mT, 30 min) of ELF EMF on the bacterial growth were studied in both cases where the microbes were in the culture media during the exposure and where culture media was preliminarily exposed to the ELF EMF before the addition of bacteria. For investigating the cell proliferation, the radioactive [³H]-thymidine assay was carried out. It has been shown that EMF at 4 Hz exposure has pronounced stimulation while at 8 Hz it has inhibited cell proliferation.     

Extremely low‐frequency electromagnetic fields affect the immune response of monocyte‐derived macrophages to pathogens

This study aimed to determine the effect of extremely low‐frequency electromagnetic fields (ELF‐EMF) on the physiological response of phagocytes to an infectious agent. THP‐1 cells (human monocytic leukemia cell line) were cultured and 50 Hz, 1 mT EMF was applied for 4–6 h to cells induced with Staphylococcus aureus or interferon gamma/lipopolysaccharide (IFγ/LPS). Alterations in nitric oxide (NO), inducible nitric oxide synthase (iNOS) levels, heat shock protein 70 levels (hsp70), cGMP levels, caspase‐9 activation, and the growth rate of S. aureus were determined. The growth curve of exposed bacteria was lower than the control. Field application increased NO levels. The increase was more prominent for S. aureus‐induced cells and appeared earlier than the increase in cells without field application. However, a slight decrease was observed in iNOS levels. Increased cGMP levels in response to field application were closely correlated with increased NO levels. ELF‐EMF alone caused increased hsp70 levels in a time‐dependent manner. When cells were induced with S. aureus or IFγ/LPS, field application produced higher levels of hsp70. ELF‐EMF suppressed caspase‐9 activation by a small extent. These data confirm that ELF‐EMF affects bacterial growth and the response of the immune system to bacterial challenges, suggesting that ELF‐EMF could be exploited for beneficial uses. Bioelectromagnetics 31:603–612, 2010. © 2010 Wiley‐Liss, Inc.     

Combined effects of 60 Hz electromagnetic field exposure with various stress factors on cellular transformation in NIH3T3 cells

Epidemiological studies have suggested that extremely low‐frequency magnetic fields (ELF‐MF) are associated with an increased incidence of cancer. Studies using in vitro systems have reported mixed results for the effects of ELF‐MF alone, and the World Health Organization (WHO) Research Agenda published in 2007 suggested that high priority research should include an evaluation of the co‐carcinogenic effects of ELF‐MF exposure using in vitro models. Here, the carcinogenic potential of ELF‐MF exposure alone and in combination with various stress factors was investigated in NIH3T3 mouse fibroblasts using an in vitro cellular transformation assay. NIH3T3 cells were exposed to a 60 Hz ELF‐MF (1 mT) alone or in combination with ionizing radiation (IR), hydrogen peroxide (H₂O₂), or c‐Myc overexpression, and the resulting number of anchorage‐independent colonies was counted. A 4 h exposure of NIH3T3 cells to ELF‐MF alone produced no cell transformation. Moreover, ELF exposure did not influence the transformation activity of IR, H₂O₂, or activated c‐Myc in our in vitro assay system, suggesting that 1 mT ELF‐MF did not affect any additive or synergistic transformation activities in combination with stress factors such as IR, H₂O₂, or activated c‐Myc in NIH3T3 cells. Bioelectromagnetics 33:207–214, 2012. © 2011 Wiley Periodicals, Inc.     

Involvement of mitochondrial activity in mediating ELF‐EMF stimulatory effect on human sperm motility

It has recently been reported that the exposure of human spermatozoa to an extremely low frequency (ELF) electromagnetic field (EMF) with a square waveform of 5 mT amplitude and frequency of 50 Hz improves sperm motility. The functional relationship between the energy metabolism and the enhancement of human sperm motility induced by ELF‐EMF was investigated. Sperm exposure to ELF‐EMF resulted in a progressive and significant increase of mitochondrial membrane potential and levels of ATP, ADP and NAD⁺ that was associated with a progressive and significant increase in the sperm kinematic parameters. No significant effects were detected on other parameters such as ATP/ADP ratio and energy charge. When carbamoyl cyanide m‐chlorophenylhydrazone (CICCP) was applied to inhibit the oxidative phosphorylation in the mitochondria, the values of energy parameters and motility in the sperm incubated in the presence of glucose and exposed to ELF‐EMF did not change, thus indicating that the glycolysis was not involved in mediating ELF‐EMF stimulatory effect on motility. By contrast, when pyruvate and lactate were provided instead of glucose, the energy status and motility increased significantly in ELF‐EMF‐treated sperm. Under these culture conditions, the inhibition of glycolitic metabolism by 2‐deoxy‐D ‐glucose (DOG) again resulted in increased values of energy and kinematic parameters, indicating that gluconeogenesis was not involved in producing glucose for use in glycolysis. We concluded that the key role in mediating the stimulatory effects exerted by ELF‐EMF on human sperm motility is played by mitochondrial oxidative phosphorylation rather than glycolysis. Bioelectromagnetics 32:15–27, 2011. © 2010 Wiley‐Liss, Inc.     

Melatonin protects rat cerebellar granule cells against electromagnetic field‐induced increases in Na+ currents through intracellular Ca2+ release

Although melatonin (MT) has been reported to protect cells against oxidative damage induced by electromagnetic radiation, few reports have addressed whether there are other protective mechanisms. Here, we investigated the effects of MT on extremely low‐frequency electromagnetic field (ELF‐EMF)‐induced Na_v activity in rat cerebellar granule cells (GCs). Exposing cerebellar GCs to ELF‐EMF for 60 min. significantly increased the Na_v current (I_Na) densities by 62.5%. MT (5 μM) inhibited the ELF‐EMF‐induced I_Na increase. This inhibitory effect of MT is mimicked by an MT₂ receptor agonist and was eliminated by an MT₂ receptor antagonist. The Na_v channel steady‐state activation curve was significantly shifted towards hyperpolarization by ELF‐EMF stimulation but remained unchanged by MT in cerebellar GC that were either exposed or not exposed to ELF‐EMF. ELF‐EMF exposure significantly increased the intracellular levels of phosphorylated PKA in cerebellar GCs, and both MT and IIK‐7 did not reduce the ELF‐EMF‐induced increase in phosphorylated PKA. The inhibitory effects of MT on ELF‐EMF‐induced Na_v activity was greatly reduced by the calmodulin inhibitor KN93. Calcium imaging showed that MT did not increase the basal intracellular Ca²⁺ level, but it significantly elevated the intracellular Ca²⁺ level evoked by the high K⁺ stimulation in cerebellar GC that were either exposed or not exposed to ELF‐EMF. In the presence of ruthenium red, a ryanodine‐sensitive receptor blocker, the MT‐induced increase in intracellular calcium levels was reduced. Our data show for the first time that MT protects against neuronal I_Na that result from ELF‐EMF exposure through Ca²⁺ influx‐induced Ca²⁺ release.     

The Short‐Term Effect of Occupational Levels of 50 Hz Electromagnetic Field on Human Heart Rate Variability

Previous studies have indicated that there is no consensus on the effects of extremely low‐frequency electromagnetic (ELF‐EMF) exposure on the cardiovascular system. This study aimed to explore the short‐term effect of ELF‐EMF exposure on heart rate (HR) and HR variability (HRV). The sample consisted of 34 healthy males aged 18–27 years. The participants were randomly assigned to the EMF (n = 17) or the Sham group (n = 17). We employed a double‐blind repeated‐measures design consisting of three 5 min experimental periods. The chest region of each individual in the EMF group was exposed to 50 Hz, 28 μT, linear polarized, continuous EMF during the EMF exposure period. HR and HRV data were recorded continuously by using a photoplethysmography sensor. Within‐subject statistical analysis indicated a significant HR deceleration in both the EMF and Sham groups. However, the standard deviation of the NN intervals (SDNN), root mean square of successive differences (RMSSD), low‐frequency (LF), and high‐frequency (HF) powers increased only in the EMF group and remained stable in the Sham group. We also compared the same HRV indices measured during the EMF and Sham periods between the two experimental groups. The between‐subject analysis results demonstrated significantly higher SDNN, RMSSD, LF, and HF values in the EMF group than in the Sham group. The LF/HF ratio did not change significantly within and between groups. On the basis of these results, we concluded that short‐term exposure of the chest region to ELF‐EMF could potentially enhance parasympathetic predominance during the resting condition. Bioelectromagnetics. 2021;42:60–75. © 2020 Bioelectromagnetics Society.     

Extremely low‐frequency electromagnetic fields accelerates wound healing modulating MMP‐9 and inflammatory cytokines

Objectives

In our previous reports, we have demonstrated that extremely low‐frequency electromagnetic fields (ELF‐EMF) exposure enhances the proliferation of keratinocyte. The present study aimed to clarify effects of ELF‐EMF on wound healing and molecular mechanisms involved, using a scratch in vitro model.

Materials and methods

The wounded monolayer cultures of human immortalized keratinocytes (HaCaT), at different ELF‐EMF and Sham exposure times were monitored under an inverted microscope. The production and expression of IL‐1β, TNF‐α, IL‐18 and IL‐18BP were measured by enzyme‐linked immunosorbent assay and quantitative real‐time PCR. The activity and the expression of matrix metalloproteinases (MMP)‐2/9 was evaluated by zymography and Western blot analysis, respectively. Signal transduction proteins expression (Akt and ERK) was measured by Western blot.

Results

The results of wound healing in vitro assay revealed a significant reduction of cell‐free area time‐dependent in ELF‐EMF‐exposed cells compared to Sham condition. Gene expression and release of cytokines analysed were significantly increased in ELF‐EMF‐exposed cells. Our results further showed that ELF‐EMF exposure induced the activity and expressions of MMP‐9. Molecular data showed that effects of ELF‐EMF might be mediated via Akt and ERK signal pathway, as demonstrated using their specific inhibitors.

Conclusions

Our results highlight ability of ELF‐EMF to modulate inflammation mediators and keratinocyte proliferation/migration, playing an important role in wound repair. The ELF‐EMF accelerates wound healing modulating expression of the MMP‐9 via Akt/ERK pathway.

     

Human cognitive performance in a 3 mT power-line frequency magnetic field

Extremely low frequency (ELF, <300 Hz) magnetic fields (MF) have been reported to modulate cognitive performance in humans. However, little research exists with MF exposures comparable to the highest levels experienced in occupations like power line workers and industrial welders. This research aims to evaluate the impact of a 60 Hz, 3 mT MF on human cognitive performance. Ninety‐nine participants completed the double‐blind protocol, performing a selection of psychometric tests under two consecutive MF exposure conditions dictated by assignment to one of three groups (sham/sham, MF exposure/sham, or sham/MF exposure). Data were analyzed using a 3 × 2 mixed model analysis of variance. Performance between repetitions improved in 11 of 15 psychometric parameters (practice effect). A significant interaction effect on the digit span forward test (F = 5.21, P < 0.05) revealed an absence of practice effects for both exposure groups but not the control group. This memory test indicates MF‐induced abolition of the improvement associated with practice. Overall, this study does not establish any clear MF effect on human cognition. It is speculated that an ELF MF may interfere with the neuropsychological processes responsible for this short‐term learning effect supported by brain synaptic plasticity. Bioelectromagnetics. Bioelectromagnetics 32:620–633, 2011. © 2011 Wiley Periodicals, Inc.