ELF magnetic field inhibits gap junctional intercellular communication and induces hyperphosphorylation of connexin43 in NIH3T3 cells

Effects of extremely low-frequency magnetic fields on human MDA-MB-231 breast cancer cells: proteomic characterization

Extremely low-frequency electromagnetic fields (ELF-MF) can modify the cell viability and regulatory processes of some cell types, including breast cancer cells. Breast cancer is a multifactorial disease where a role for ELF-MF cannot be excluded. ELF-MF may influence the biological properties of breast cells through molecular mechanisms and signaling pathways that are still unclear. This study analyzed the changes in the cell viability, cellular morphology, oxidative stress response and alteration of proteomic profile in breast cancer cells (MDA-MB-231) exposed to ELF-MF (50 Hz, 1 mT for 4 h). Non-tumorigenic human breast cells (MCF-10A) were used as control cells. Exposed MDA-MB-231 breast cancer cells increased their viability and live cell number and showed a higher density and length of filopodia compared with the unexposed cells. In addition, ELF-MF induced an increase of the mitochondrial ROS levels and an alteration of mitochondrial morphology. Proteomic data analysis showed that ELF-MF altered the expression of 328 proteins in MDA-MB-231 cells and of 242 proteins in MCF-10A cells. Gene Ontology term enrichment analysis demonstrated that in both cell lines ELF-MF exposure up-regulated the genes enriched in "focal adhesion" and "mitochondrion". The ELF-MF exposure decreased the adhesive properties of MDA-MB-231 cells and increased the migration and invasion cell abilities. At the same time, proteomic analysis, confirmed by Real Time PCR, revealed that transcription factors associated with cellular reprogramming were upregulated in MDA-MB-231 cells and downregulated in MCF-10A cells after ELF-MF exposure. MDA-MB-231 breast cancer cells exposed to 1 mT 50 Hz ELF-MF showed modifications in proteomic profile together with changes in cell viability, cellular morphology, oxidative stress response, adhesion, migration and invasion cell abilities. The main signaling pathways involved were relative to focal adhesion, mitochondrion and cellular reprogramming.

Effect of Occupational Extremely Low-Frequency Electromagnetic Field Exposure on the Thyroid Gland of Workers: A Prospective Study

OBJECTIVE

The aim of this study was to investigate the biological effects of occupational extremely low-frequency electromagnetic field (ELF-EMF) exposure on the thyroid gland.

METHODS

We conducted a prospective analysis of 85 workers (exposure group) exposed to an ELF-EMF (100 μT, 10-100 Hz) produced by the electromagnetic aircraft launch system and followed up on thyroid function indices, immunological indices, and color Doppler images for 3 years. Additionally, 116 healthy volunteers were randomly selected as controls (control group), the thyroid function of whom was compared to the exposure group.

RESULTS

No significant difference was observed in thyroid function between the exposure and control groups. During the follow-up of the exposure group, the serum free triiodothyronine (FT3) level was found to slowly decrease and free thyroxine (FT4) level slowly increase with increasing exposure time. However, no significant difference was found in thyroid-stimulating hormone (TSH) over the three years, and no significant difference was observed in the FT3, FT4 and TSH levels between different exposure subgroups. Furthermore, no significant changes were observed in thyroid autoantibody levels and ultrasound images between subgroups or over time.

CONCLUSION

Long-term exposure to ELF-EMF may promote thyroid secretion of T4 and inhibit deiodination of T4 to T3. ELF-EMF has no significant effect on thyroid immune function and morphology.

The Relative Permittivity Changes of EGF by 50 Hz MF Exposure Neither Affect the Interaction of EGF With EGFR Nor Its Biological Effects

The biophysical mechanism of magnetic fields (MFs) acting on living systems is not clear. Previous research showed that, similar to epidermal growth factor (EGF), MF exposure induced EGF receptor (EGFR) clustering and activated EGFR signaling. In this study, we investigated whether MF exposure induced the changes in physical characteristics of EGF and downstream effects of EGF and EGFR interaction. The phase-interrogation surface plasmon resonance (SPR) sensing analyses showed that 50 Hz MF exposure at 4.0 mT for 1 h induced reversible relative permittivity changes of EGF solution. However, compared with sham-exposed EGF solution, the MF-exposed EGF solution did not affect the binding of EGF to EGFR, nor the cell viability and EGFR clustering in human amniotic epithelial cells (FL cells). Our data suggest that cellular EGFR clustering response to MF exposure might not be a result of changes in relative permittivity of EGF in cell culture solution. Bioelectromagnetics. © 2020 Bioelectromagnetics Society.

Signaling pathways involved in anti-inflammatory effects of Pulsed Electromagnetic Field in microglial cells

Literature studies suggest important protective effects of low-frequency, low-energy pulsed electromagnetic fields (PEMFs) on inflammatory pathways affecting joint and cerebral diseases. However, it is not clear on which bases they affect neuroprotection and the mechanism responsible is yet unknown. Therefore the aim of this study was to identify the molecular targets of PEMFs anti-neuroinflammatory action. The effects of PEMF exposure in cytokine production by lipopolysaccharide (LPS)-activated N9 microglial cells as well as the pathways involved, including adenylyl cyclase (AC), phospholipase C (PLC), protein kinase C epsilon (PKC-ε) and delta (PKC-δ), p38, ERK1/2, JNK1/2 mitogen activated protein kinases (MAPK), Akt and caspase 1, were investigated. In addition, the ability of PEMFs to modulate ROS generation, cell invasion and phagocytosis, was addressed. PEMFs reduced the LPS-increased production of TNF-α and IL-1β in N9 cells, through a pathway involving JNK1/2. Furthermore, they decreased the LPS-induced release of IL-6, by a mechanism not dependent on AC, PLC, PKC-ε, PKC-δ, p38, ERK1/2, JNK1/2, Akt and caspase 1. Importantly, a significant effect of PEMFs in the reduction of crucial cell functions specific of microglia like ROS generation, cell invasion and phagocytosis was found. PEMFs inhibit neuroinflammation in N9 cells through a mechanism involving, at least in part, the activation of JNK MAPK signalling pathway and may be relevant to treat a variety of diseases characterized by neuroinflammation.

Comparative Analysis of Biological Effects Induced on Different Cell Types by Magnetic Fields with Magnetic Flux Densities in the Range of 1–60 mT and Frequencies up to 50 Hz

Moderate static magnetic fields (SMFs) are generated from sources such as new-generation electric trams and trains, electric arc welding, and magnetic resonance imaging (MRI) devices, as well as during the industrial production of aluminium, while extremely low frequency pulsed magnetic fields (ELF-PMFs) are produced by house power installations, household appliances, and high voltages transmission lines. Moderate SMFs and ELF-PMFs with magnetic flux densities (B) in the range of 1–60 mT and frequencies (f) up to 50 Hz are common MF exposure sources for the population. Even though humans are continually exposed to these MFs, to date no definitive endpoint has been drawn about their safety. In this review, the state of knowledge about the biological effects induced by these MFs on different cell types will be addressed. In our own observation, the putative modulation of Ca2+/H+ and Na+/H+ plasma membrane antiporters of human peripheral blood lymphocytes (PBLs) was found to occur after a 24 h exposure to a 6 mT SMF, and the bystander effect observed on U937 cells cultivated for up to 6 h in the conditioned medium harvested from human PBLs previously exposed for 24 h to the same MF (secondary necrosis induction) will be also herein discussed.

Effects of 50 Hz magnetic fields on gap junctional intercellular communication in NIH3T3 cells

The present study focused on gap junctional intercellular communication (GJIC) as a target for biological effects of extremely low-frequency (ELF) magnetic field (MF) exposure. Fluorescence recovery after photobleaching microscopy (FRAP) was used to visualize diffusion of a fluorescent dye between NIH3T3 fibroblasts through gap junctions. The direct effect of 24 h exposure to 50 Hz MF at 0.4 or 1 mT on GJIC function was assessed in one series of experiments. The potential synergism of MF with an inhibitor of GJIC, phorbol ester (TPA), was studied in another series by observing FRAP when NIH3T3 cells were incubated with TPA for 1 h following 24 h exposure to MF. In contrast to other reports of ELF-MF effects on GJIC, under our experimental conditions we observed neither direct inhibition of GJIC nor synergism with TPA-induced inhibition from 50 Hz MF exposures.

Do extremely low frequency magnetic fields enhance the effects of environmental carcinogens? A meta-analysis of experimental studies

PURPOSE

This paper is a meta-analysis of data from in vitro studies and short-term animal studies that have combined extremely low frequency magnetic fields with known carcinogens or other toxic physical or chemical agents.

MATERIALS AND METHODS

The data was analyzed by systematic comparison of study characteristics between positive and negative studies to reveal possible consistent patterns.

RESULTS

The majority of the studies reviewed were positive, suggesting that magnetic fields do interact with other chemical and physical exposures. Publication bias is unlikely to explain the findings. Interestingly, a nonlinear 'dose-response' was found, showing a minimum percentage of positive studies at fields between 1 and 3 mT. The radical pair mechanism (magnetic field effects on recombination of radical pairs) is a good candidate mechanism for explaining the biphasic dose-response seen in the present analysis.

CONCLUSIONS

Most of the studies reviewed used magnetic fields of 100 microT or higher, so the findings are not directly relevant for explaining the epidemiological findings suggesting increased risk of childhood leukemia above 0.4 microT. However, confirmed adverse effects even at 100 microT would have implications for risk assessment and management, including the need to reconsider the exposure limits for magnetic fields. There is an obvious need for further studies on combined effects with magnetic fields.

50-Hz magnetic field induces EGF-receptor clustering and activates RAS

PURPOSE

In a previous study, we found that exposure to a 50 Hz magnetic field (MF) could activate stress-activated protein kinase (SAPK) and P38 mitogen-activated protein (MAP) kinase (P38 MAPK) in Chinese hamster lung (CHL) fibroblast cells, and simultaneous exposure to a 'noise' MF of the same intensity inhibited these effects. In order to explore the possible target sites and upstream signal transduction molecules of SAPK and P38 MAPK, and further validate the interference effects of 'noise' MF on 50 Hz MF, the effects of MF exposure on clustering of epidermal growth factor (EGF) receptors and Ras protein activation were investigated.

MATERIALS AND METHODS

CHL cells were exposed to a 50 Hz sinusoidal MF at 0.4 mT for different durations, and clustering of EGF receptors on cellular membrane and Ras protein activation were analyzed using immunofluorescence confocal microscopy and co-precipitation technology. EGF treatment served as the positive control.

RESULTS

The results showed that, compared with sham-exposed cells, exposure to a 50 Hz MF at 0.4 mT for 5 min slightly induced EGF receptor clustering, whereas exposure for 15 min enhanced receptor clustering significantly. Corresponding to receptor clustering, Ras protein was also activated after exposure to the 50 Hz MF. Exposure to a 'noise' MF (with frequency ranges from 30 - 90 Hz) at the same intensity and durations, did not significantly affect EGF receptor clustering and Ras protein. However, by superimposing the 'noise' MF, receptor clustering and Ras activation induced by 50 Hz MF were inhibited.

CONCLUSION

The results suggested that membrane receptors could be one of the most important targets where extremely low frequency (ELF) MF interacts with cells, and Ras may participate in the signal transduction process of 50 Hz MF. Furthermore, a 'noise' MF could inhibit these effects caused by ELF-MF.

Noise magnetic fields abolish the gap junction intercellular communication suppression induced by 50 hz magnetic fields

Previously, we have reported that exposure to 50 Hz coherent sinusoidal magnetic fields (MF) for 24 h inhibits gap junction intercellular communication (GJIC) in mammalian cells at an intensity of 0.4 mT and enhances the inhibition effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) at 0.2 mT. In the present study, we further explored the effects of incoherent noise MF on MF-induced GJIC inhibition. GJIC was determined by fluorescence recovery after photobleaching (FRAP) with a laser-scanning confocal microscope. The rate of fluorescence recovery (R) at 10 min after photobleaching was adopted as the functional index of GJIC. The R-value of NIH3T3 cells exposed to 50 Hz sinusoidal MF at 0.4 mT for 24 h was 30.85 +/- 14.70%, while the cells in sham exposure group had an R-value of 46.36 +/- 20.68%, demonstrating that the GJIC of NIH3T3 cells was significantly inhibited by MF exposure (P < .05). However, there were no significant differences in the R-values of the sham exposure, MF-plus-noise MF exposure (R: 49.58 +/- 19.38%), and noise MF exposure groups (R: 46.74 +/- 21.14%) (P > .05), indicating that the superposition of a noise MF alleviated the suppression of GJIC induced by the 50 Hz MF. In addition, although MF at an intensity of 0.2 mT synergistically enhanced TPA-induced GJIC inhibition (R: 24.90 +/- 13.50% vs. 35.82 +/- 17.18%, P < .05), further imposition of a noise MF abolished the synergistic effect of coherent MF (R: 32.51 +/- 18.37%). Overall, the present data clearly showed that although noise MF itself had no effect on GJIC of NIH3T3 cells, its superposition onto a coherent sinusoidal MF at the same intensity abolished MF-induced GJIC suppression. This is the first report showing that noise MF neutralizes 50 Hz MF-induced biological effect by using a signaling component as the test endpoint.

Bioelectromagnetics in morphogenesis

Understanding the factors that allow biological systems to reliably self-assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration.

Weak extremely high frequency microwaves affect pollen-tube emergence and growth in kiwifruit: pollen grain irradiation and water-mediated effects

OBJECTIVE

This study was designed to evaluate the effects of weak-intensity extremely high frequency (EHF) microwaves in a model system-the plant organism pollen grain-lacking the placebo effect, available in large populations, to ensure accurate statistical analysis, and whose sensitivity is closely relevant to animal and human biology.

DESIGN

This study was blinded using an in vitro pollen germination technique. SUBJECTS AND STUDY INTERVENTIONS: Pollen of kiwifruit (Actinidia deliciosa) was either directly irradiated or grown in a medium prepared with irradiated water, using a CromoStim 2000, (PromoPharma, Republic of San Marino) designed for EHF microwave resonance therapy (MRT). It produces weak intensity EHF radiations (40-78 GHz), either continuous wave (cw) or modulated, at a 10 Hz-frequency, with infrared (IR) carried to 635-950 nm, and with an impedance (IPD) of 10(-21) W/Hz cm(2) and a power supply from 0 to 20 mW.

OUTCOME MEASUREMENTS

Pollen-tube emergence was expressed as a percent of grains producing a tube and tube elongation was measured at 4 hours of incubation by a turbidimetric assay (A(500)) of cultures, expressed as the net absorbance increase over time 0.

RESULTS

At days 2 and 4 during aging, both percent of germination and tube growth significantly and consistently improved over controls in kiwifruit pollen grains irradiated for 30 minutes at day 0 at 10 Hz frequency with the CromoStim 2000. Highly significant effects, either stimulant or inhibitory, were also observed on kiwifruit pollen (stressed or not) growing in a medium prepared with water previously irradiated either cw or modulated. Irradiated water affected pollen germination immediately and even after several days following EHF treatment.

CONCLUSIONS

Either direct or indirect EHF irradiation performed by the CromoStim 2000 is effective on pollen growth processes. In both cases, water seemed to play a primary role. According to the quantum electrodynamical coherence theory, our work could also have implications for homeopathy, suggesting a key to explain the efficacy of high dilutions and succussion procedures.

ELF magnetic fields induce internalization of gap junction protein connexin 43 in Chinese hamster lung cells

We have previously demonstrated that exposure of Chinese hamster lung (CHL) cells to 50 Hz magnetic fields (MFs) and/or 12-O-tetradecanoylphorbol-3-acetate (TPA)-inhibited gap junctional intercellular communication (GJIC). To explore and compare the mechanisms of GJIC inhibition induced by extremely low frequency (ELF) MF and TPA, the number and localization of connexin 43 (C x 43) were studied. The localization of C x 43 was determined with indirect immunofluorescence histochemical analysis and detected by confocal microscopy after exposing CHL cells to 50 Hz sinusoidal magnetic field at 0.8 mT for 24 h without or with TPA (5 ng/ml) for the last 1 h. The C x 43 levels in nuclei and in cytoplasm were examined by Western blotting analysis. The results showed that the cells exposed to MF and/or TPA displayed individual plaques at regions of intercellular contact, which were fewer than the normal cells in number, while the number of C x 43 in cytoplasm increased and congregated near the nuclei. Western blot analysis further demonstrated the quantity of changes in location of Cx43. These results suggest that reduction of C x 43 at regions of intercellular contact may be one of the mechanisms of GJIC inhibition induced by ELF MF.

Millimeter wave exposure reverses TPA suppression of gap junction intercellular communication in HaCaT human keratinocytes

The effect of 30.16 GHz millimeter wave (MMW) exposure at 1.0 and 3.5 mW/cm2 on gap junction intercellular communication (GJIC) was studied in cultured HaCaT keratinocytes, using the fluorescence recovery after photobleaching (FRAP) technique and laser confocal scanning microscopy to follow the intracellular movement of 5,6-carboxyfluorescein diacetate dye. While MMW exposure alone for 1 h at either 1.0 or 3.5 mW/cm2 did not affect GJIC, MMW exposure in combination with 5 ng/ml TPA treatment reversed TPA induced suppression of GJIC. Exposure at 1.0 mW/cm2 resulted in a partial reversal, and exposure at 3.5 mW/cm2 resulted in essentially full reversal of the TPA suppression.

Low-intensity electromagnetic and mechanical modulation of bone growth and repair: are they equivalent?

Signals from both electromagnetic fields (EMF) and ultrasound (US) have a clinically significant effect upon bone repair. Both modalities are now a common part of the orthopedist's armamentarium for the care of delayed union, nonunion, and fresh fractures. Dynamization or controlled weight bearing also enhances bone repair. Consideration of the dosimetry of both EMF and US modalities suggests a possible unifying mechanism for the bioeffects from EMF, US, and strain-generated potentials (SGP) signals based on the time-varying electric field, E(t), associated with each type of stimulus. The E(t) field is directly induced with EMF devices and indirectly induced via the streaming potentials associated with the mechanical movement of ionic fluids within bone caniculi or directly past cell surfaces from US and SGP signals. It is shown that both electrically and mechanically induced E(t) have common waveform characteristics at the treatment site and thus can deliver similar doses of electrical stimulation. It is proposed that the time-varying endogenous electric field, E(t), from a time-varying change in the mechanical environment of healing or remodeling bone, can act as a dose-dependent growth stimulus. Thus, the primary messenger affecting cellular activity is E(t), suggesting that bone repair or remodeling may be interchangeably modulated using mechanical (including US) or electromagnetic signals.