Effect of 50 Hz Electromagnetic Fields on the Induction of Heat-Shock Protein Gene Expression in Human Leukocytes

Effects of mobile phone radiofrequency radiation on sperm quality

In the last decades, the universal use of mobile phones has contributed to radiofrequency electromagnetic radiation environmental pollution. The steady growth in mobile phone usage has raised concerns about the effects of phone radiation on male reproductive health. Epidemiological studies report a sharp decline in sperm counts in developing countries, and worldwide with c. 14% of couples having difficulties to conceive, many of which are attributed to a male infertility factor. Environment and lifestyle factors are known to contribute to male infertility. Exposure to heat, radiation, or radioactivity might induce damage to biological tissue organs, including the testis. Given the ubiquitous use of mobile phones, the potential adverse effects of the resulting environmental radiation needs to be elucidated further. It seems to be an apparent relationship between the increased exposure to mobile phone radiofrequency and sperm quality decline, but the evidence is not conclusive. Our review summarizes the evidence concerning the possible adverse effects of cell phone radiation on the male reproductive system, with a focus on sperm quality. Also, we critically analyze the effects of elevated testicular temperature and oxidative stress on male fertility and how these factors could interfere with the physiological activities of the testis.

Radiofrequency radiation: A possible threat to male fertility

Radiofrequency exposure from man-made sources has increased drastically with the era of advanced technology. People could not escape from such RF radiations as they have become the essential part of our routine life such as Wi-Fi, microwave ovens, TV, mobile phones, etc. Although non-ionizing radiations are less damaging than ionizing radiations but its long term exposure effect cannot be avoided. For fertility to be affected, either there is an alteration in germ cell, or its nourishing environment, and RF affects both the parameters subsequently, leading to infertility. This review with the help of in vitro and in vivo studies shows that RF could change the morphology and physiology of germ cells with affected spermatogenesis, motility and reduced concentration of male gametes. RF also results in genetic and hormonal changes. In addition, the contribution of oxidative stress and protein kinase complex after RFR exposure is also summarized which could also be the possible mechanism for reduction in sperm parameters. Further, some preventative measures are described which could help in reverting the radiofrequency effects on germ cells.

Cellular Response to ELF-MF and Heat: Evidence for a Common Involvement of Heat Shock Proteins?

It has been shown that magnetic fields in the extremely low frequency range (ELF-MF) can act as a stressor in various in vivo or in vitro systems, at flux density levels below those inducing excitation of nerve and muscle cells, which are setting the limits used by most generally accepted exposure guidelines, such as the ones published by the International Commission on Non-Ionizing Radiation Protection. In response to a variety of physiological and environmental factors, including heat, cells activate an ancient signaling pathway leading to the transient expression of heat shock proteins (HSPs), which exhibit sophisticated protection mechanisms. A number of studies suggest that also ELF-MF exposure can activate the cellular stress response and cause increased HSPs expression, both on the mRNA and the protein levels. In this review, we provide some of the presently available data on cellular responses, especially regarding HSP expression, due to single and combined exposure to ELF-MF and heat, with the aim to compare the induced effects and to detect possible common modes of action. Some evidence suggest that MF and heat can act as costressors inducing a kind of thermotolerance in cell cultures and in organisms. The MF exposure might produce a potentiated or synergistic biological response such as an increase in HSPs expression, in combination with a well-defined stress, and in turn exert beneficial effects during certain circumstances.

Low-Frequency Pulsed Electromagnetic Field Is Able to Modulate miRNAs in an Experimental Cell Model of Alzheimer's Disease

The aim of the present study was to investigate on the effects of a low-frequency pulsed electromagnetic field (LF-PEMF) in an experimental cell model of Alzheimer's disease (AD) to assess new therapies that counteract neurodegeneration. In recent scientific literature, it is documented that the deep brain stimulation via electromagnetic fields (EMFs) modulates the neurophysiological activity of the pathological circuits and produces clinical benefits in AD patients. EMFs are applied for tissue regeneration because of their ability to stimulate cell proliferation and immune functions via the HSP70 protein family. However, the effects of EMFs are still controversial and further investigations are required. Our results demonstrate the ability of our LF-PEMF to modulate gene expression in cell functions that are dysregulated in AD (i.e., BACE1) and that these effects can be modulated with different treatment conditions. Of relevance, we will focus on miRNAs regulating the pathways involved in brain degenerative disorders.

On the thermal effect induced in tissue samples exposed to extremely low-frequency electromagnetic field

BACKGROUND

The influence of electromagnetic exposure on mammalian tissues was approached as a public health issue aiming to reveal the putative side effect of 50 Hz industrial and domestic supply source (i) during aliments storage near such sources; (ii) in people staying couple of hours in the proximity of conducting wires.

MATERIALS AND METHODS

Fluorescence emission based thermal sensor was used to emphasize temperature dynamics of fresh meat samples during controlled electromagnetic exposure in Helmholtz coils adjusted to deliver 50 Hz / (4÷10) mT electromagnetic field in their inner volume. Fluoroptic temperature probe with 0.1 °C accuracy measurement and data acquisition software allowed reading temperature every second, in the tissue volume during exposure.

RESULTS

The temperature dynamics curves of ex-vivo porcine tissues like liver, kidney, brain, muscle, lung, and bone, were comparatively analyzed - the choosing of the mammalian species being justified by metabolic and physiological similarities with human body. The curve slopes appear to be the same for the range of initial temperatures chosen to perform the tests (20.0 ± 0.1 °C), the temperature increase reaching around 2.0 °C for the magnetic flux density of 10 mT. Quantitative dependence was evidenced between the thermal effect and the magnetic flux density.

CONCLUSIONS

The technical interpretation is based on heating effect, on bioimpedance increasing and on water vaporization during wet sample exposure. The biomedical aspects derive from the degrading effects of food heating as well as from possible in vivo effects of living body exposure.

Effects of 50-Hz magnetic field exposure on superoxide radical anion formation and HSP70 induction in human K562 cells

Epidemiological studies suggest a correlation between exposure to low-level extremely low-frequency (ELF) magnetic fields (MF) and certain cancers and neurodegenerative diseases. Experimental studies have not provided any mechanism for such effects, although at flux density levels significantly higher than the ones encountered in epidemiological studies, radical homoeostasis and levels of stress response proteins can be affected. Here, we report on the influence of MF exposure (50-Hz sine wave; 1 h; 0.025-0.10 mT; vertical or horizontal MF exposure direction) on different cellular parameters (proliferation, cell cycle distribution, superoxide radical anion, and HSP70 protein levels) in the human leukaemia cell line K562. The positive control heat treatment (42°C, 1 h) did not affect either cell proliferation or superoxide radical anion production but caused accumulation of cells in the G2 phase and increased the stress protein HSP70. MF exposure (0.10 mT, 1 h) did not affect either cell cycle kinetics or proliferation. Both vertical and horizontal MF exposures for 1 h caused significantly and transiently increased HSP70 levels (>twofold), at several flux densities, compared to sham controls and also compared to heat treatment. This exposure also increased (30-40%) the levels of the superoxide radical anion, comparable to the positive control PMA. Addition of free radical scavengers (melatonin or 1,10-phenantroline) inhibited the MF-induced increase in HSP70. In conclusion, an early response to ELF MF in K562 cells seems to be an increased amount of oxygen radicals, leading to HSP70 induction. Furthermore, the results suggest that there is a flux density threshold where 50-Hz MF exerts its effects on K562 cells, at or below 0.025 mT, and also that it is the MF, and not the induced electric field, which is the active parameter.

Effect of 60 Hz magnetic fields on the activation of hsp70 promoter in cultured INER-37 and RMA E7 cells

It has been reported that 50-60 Hz magnetic fields (MF) with flux densities ranging from microtesla to millitesla are able to induce heat shock factor or heat shock proteins in various cells. In this study, we investigated the effect of 60 Hz sinusoidal MF at 8 and 80 μT on the expression of the luciferase gene contained in a plasmid labeled as electromagnetic field-plasmid (pEMF). This gene construct contains the specific sequences previously described for the induction of hsp70 expression by MF, as well as the reporter for the luciferase gene. The pEMF vector was transfected into INER-37 and RMA E7 cell lines that were later exposed to either MF or thermal shock (TS). Cells that received the MF or TS treatments and their controls were processed according to the luciferase assay system for evaluate luciferase activity. An increased luciferase gene expression was observed in INER-37 cells exposed to MF and TS compared with controls (p < 0.05), but MF exposure had no effect on the RMA E7 cell line.

The effect of 100 mT SMF on activation of the hsp70 promoter in a heat shock/luciferase reporter system

Human exposure to magnetic fields, increased through use of new technologies like magnetic resonance imaging (MRI), has prompted investigations into possible effects of static magnetic fields (SMFs) on cellular processes. However, controversy still remains between many studies, which likely results from a lack of uniformity across experimental parameters, including the length of magnetic field exposure, the strength of the magnetic field, and the cell type or organism under investigation. The purpose of this research was to monitor effects of SMF exposure using real-time luminescence photometry. The study investigated the potential interaction of a 100 mT SMF on a heat shock protein (hsp70)/luciferase reporter construct in stably transfected NIH3T3 cells. Changes in heat shock promoter activation following 100 mT SMF exposure were analyzed and detected as bioluminescence in real-time. Two heat parameters were considered in combination with sham- and 100 mT-exposed experiments: no heat or 1,800 s heat. As expected, there was a significant increase in bioluminescence in response to 1,800 s of heat alone. However, no significant difference in average hsp70 promoter activation between sham and 100 mT experiments was observed for no heat or 1,800 s heat experiments. Therefore, a 100 mT SMF was shown to have no effect on the activation of the heat shock protein promoter during SMF exposure or when SMF exposure was combined with a heat insult.

Exposure to high static or pulsed magnetic fields does not affect cellular processes in the yeast Saccharomyces cerevisiae

We report results of a study of the effects of strong static (up to 16 T for 8 h) and pulsed (up to 55 T single-shot and 4 x 20 T repeated shots) magnetic fields on Saccharomyces cerevisiae cultures in the exponential phase of growth. In contrast to previous reports restricted to only a limited number of cellular parameters, we have examined a wide variety of cellular processes: genome-scale gene expression, proteome profile, cell viability, morphology, and growth, metabolic and fermentation activity after magnetic field exposure. None of these cellular activities were impaired in response to static or pulsed magnetic field exposure. Our results confirm and extend previous reports on the absence of magnetic field effects on yeast and support the hypothesis that magnetic fields have no impact on the transcriptional machinery and on the integrity of unicellular biological systems.

Do static or time-varying magnetic fields in magnetic resonance imaging (3.0 T) alter protein-gene expression?-A study on human embryonic lung fibroblasts

PURPOSE

To evaluate the influence of magnetic resonance imaging (MRI) on gene expression in embryonic human lung fibroblasts (Hel 299).

MATERIALS AND METHODS

The cells were exposed to the static magnetic field and to a turbo spin-echo sequence of an MR scanner at 3.0 Tesla. An MR group (exposed) and a control group (sham-exposed) were set up using a special MR-compatible incubation system. The exposure time was two hours. Gene expression profiles were studied using a complementary deoxyribonucleic acid (cDNA) microarray containing 498 known genes involved in transcription, intracellular transport, structure/junction/adhesion or extracellular matrix, signaling, host defense, energetics, metabolism, cell shape, and death.

RESULTS

No changes in gene expression were found in either group (exposed or sham-exposed cells) at the end of a two-hour exposure for any of the 498 tested protein genes.

CONCLUSION

The results suggest that MRI has no influence on protein-gene expression in eugenic human lung cells.

Effects of 50 Hz sinusoidal magnetic fields on Hsp27, Hsp70, Hsp90 expression in porcine aortic endothelial cells (PAEC)

The aim of the present study was to investigate the influence of 50 Hz sinusoidal magnetic field on Hsp27, Hsp70, and Hsp90 expression in a model of primary culture of porcine aortic endothelial cells (PAEC). We took into consideration the Hsp profile in terms of mRNA expression, protein expression and protein localization inside the cells. The choice of the cell system was motivated by the involvement of the endothelial cells in the onset of many diseases; moreover, only few reports describe the effects of extremely low frequency magnetic fields (ELF-MFs) on such cells. ELF-MF exposure induced an increase in the mRNA levels of the three proteins, which was statistically significant for Hsp70. On the contrary, we did not observe any influence on Hsp27, Hsp70, and Hsp90 protein levels. Analysis in situ by immunofluorescence revealed that ELF-MF exposure affected the cellular distribution of Hsp27; in particular a partial relocalization in the nucleus was observed.

Fifty Hertz electromagnetic field exposure stimulates secretion of beta-amyloid peptide in cultured human neuroglioma

Recent epidemiological studies raise the possibility that individuals with occupational exposure to low frequency (50-60 Hz) electromagnetic fields (LF-EMF), are at increased risk of Alzheimer's disease (AD). However, the mechanisms through which LF-EMF may affect AD pathology are unknown. We here tested the hypothesis that the exposure to LF-EMF may affect amyloidogenic processes. We examined the effect of exposure to 3.1 mT 50 Hz LF-EMF on Abeta secretion in H4 neuroglioma cells stably overexpressing human mutant amyloid precursor protein. We found that overnight exposure to LF-EMF induces a significant increase of amyloid-beta peptide (Abeta) secretion, including the isoform Abeta 1-42, without affecting cell survival. These findings show for the first time that exposure to LF-EMF stimulates Abeta secretion in vitro, thus alluding to a potential link between LF-EMF exposure and APP processing in the brain.

14.6 mT ELF magnetic field exposure yields no DNA breaks in model systemSalmonella, but provides evidence of heat stress protection

In this study, we demonstrate that common extremely low frequency magnetic field (MF) exposure does not cause DNA breaks in this Salmonella test system. The data does, however, provide evidence that MF exposure induces protection from heat stress. Bacterial cultures were exposed to MF (14.6 mT 60 Hz field, cycled 5 min on, 10 min off for 4 h) and a temperature-matched control. Double- and single-stranded DNA breaks were assayed using a recombination event counter. After MF or control exposure they were grown on indicator plates from which recombination events can be quantified and the frequency of DNA strand breaks deduced. The effect of MF was also monitored using a recombination-deficient mutant (recA). The results showed no significant increase in recombination events and strand breaks due to MF. Evidence of heat stress protection was determined using a cell viability assay that compared the survival rates of MF exposed and control cells after the administration of a 10 min 53 degrees C heat stress. The control cells exhibited nine times more cell mortality than the MF exposed cells. This Salmonella system provides many mutants and genetic tools for further investigation of this phenomenon.

Synthesis of DnaK and GroEL in Escherichia coli cells exposed to different magnetic field signals

The effects of extremely low frequency magnetic field (ELF-MF)(1 mT, 50 Hz) on the heat shock protein (HSP) synthesis in Escherichia coli were investigated. Two magnetic field signals were studied: sinusoidal (SMF) and pulsed square wave (PMF). It was found that bacteria exposed to SMF showed a significantly higher level of DnaK and GroEL proteins as compared to sham-exposed bacteria as revealed by Western blot, whereas a lower level was observed after PMF exposure. Similar results were obtained when bacterial cells were exposed to heat shock (HS) after ELF-MF exposure: again SMF and PMF resulted in an increase and in a reduction of HSP amount in comparison with sham control, respectively. In conclusion, the MF influences the synthesis of HSPs in E. coli in a way that critically depends on the signal characteristics.

The influence of extremely low frequency magnetic fields on cytoprotection and repair

Ischemia-reperfusion injuries, such as those suffered from various types of cardiovascular disease, are major causes of death and disability. For relatively short periods of ischemia, much of the damage is potentially reversible and in fact, does not occur until the influx of oxygen during the reperfusion stage. Because of this, there is a window of opportunity to protect the ischemic tissue. Here, we review several mechanisms of protection, such as heat shock proteins, opioids, collateral blood flow, and nitric oxide induction, and the evidence indicating that magnetic fields may be used as a means of providing protection via each of these mechanisms. While there are few studies demonstrating direct protection with magnetic field therapies, there are a number of published reports indicating that electromagnetic fields may be able to influence some of the biochemical systems with protective applications.

50 Hz magnetic fields of constant or fluctuating intensity: Effects on immunocytehsp70 in the musselMytilus galloprovincialis

Effects of a single 30 min exposure to a 50 Hz, 400 microT sinusoidal extremely low frequency magnetic field (ELF MF) on hsp70 expression in immunocytes from the bivalve Mytilus galloprovincialis was investigated using RT-PCR and immunoblot approaches. The results indicate that in M. galloprovincialis immunocytes hsp70 expression was unaltered at both transcriptional and translational level after exposure to constant or fluctuating intensity MFs.

Increased Levels of Inducible HSP70 in Cells Exposed to Electromagnetic Fields

Because reports in the literature on the effects of electromagnetic fields (EMFs) on expression of the 70-kDa heat-shock protein (HSP70) are somewhat contradictory, we studied the influence of low-frequency EMFs on the accumulation of inducible HSP70 in several cell models. Some of the cell types tested showed increased levels of HSP70 protein when exposed for 24 h to 50 Hz, 680 microT EMFs. In endothelial cells, EMFs alone induced only a poor and transient activation of the heat-shock transcription factor 1 (HSF1); however, neither the level of HSP70 mRNA nor the synthesis of HSP70 appeared to be altered significantly. Accordingly, transfection experiments involving HSP70 promoter showed that gene transcription was not affected. We also noted a marked reduction in proteasome activities in cell extracts exposed to EMFs. Interestingly, the heat-shock-induced levels of HSP70 mRNA and protein were increased by a concomitant weak stressor like EMFs. Taken together, our results indicate that in EMF-exposed endothelial cells, HSP70 gene transcription and translation are unaffected; however, EMFs alone promoted accumulation of the inducible HSP70 protein, probably by increasing its stability, and it enhanced accumulation and translation of the heat-induced HSP70 mRNA when applied in concert with heat shock.

Extremely Low-Frequency Electromagnetic Fields do not Affect DNA Damage and Gene Expression Profiles of Yeast and Human Lymphocytes

We studied the effects of extremely low-frequency (50 Hz) electromagnetic fields (EMFs) on peripheral human blood lymphocytes and DBY747 Saccharomyces cerevisiae. Graded exposure to 50 Hz magnetic flux density was obtained with a Helmholtz coil system set at 1, 10 or 100 microT for 18 h. The effects of EMFs on DNA damage were studied with the single-cell gel electrophoresis assay (comet assay) in lymphocytes. Gene expression profiles of EMF-exposed human and yeast cells were evaluated with DNA microarrays containing 13,971 and 6,212 oligonucleotides, respectively. After exposure to the EMF, we did not observe an increase in the amount of strand breaks or oxidated DNA bases relative to controls or a variation in gene expression profiles. The results suggest that extremely low-frequency EMFs do not induce DNA damage or affect gene expression in these two different eukaryotic cell systems.

Effect of 900 MHz electromagnetic fields on nonthermal induction of heat-shock proteins in human leukocytes

Despite many studies, the evidence as to whether radiofrequency fields are detrimental to health remains controversial, and the debate continues. Cells respond to some abnormal physiological conditions by producing cytoprotective heat-shock (or stress) proteins. The aim of this study was to determine whether exposure to mobile phone-type radiation causes a nonthermal stress response in human leukocytes. Human peripheral blood was sham-exposed or exposed to 900 MHz fields (continuous-wave or GSM-modulated signal) at three average specific absorption rates (0.4, 2.0 and 3.6 W/kg) for different durations (20 min, 1 h and 4 h) in a calibrated TEM cell placed in an incubator to give well-controlled atmospheric conditions at 37 degrees C and 95% air/5% CO(2). Positive (heat-stressed at 42 degrees C) and negative (kept at 37 degrees C) control groups were incubated simultaneously in the same incubator. Heat caused an increase in the number of cells expressing stress proteins (HSP70, HSP27), measured using flow cytometry, and this increase was dependent on time. However, no statistically significant difference was detected in the number of cells expressing stress proteins after RF-field exposure. These results suggest that mobile phone-type radiation is not a stressor of normal human lymphocytes and monocytes, in contrast to mild heating.