Exposure to 900 MHz electromagnetic field induces an unbalance between pro‐apoptotic and pro‐survival signals in T‐lymphoblastoid leukemia CCRF‐CEM cells

The original article to which this Erratum was published in J. Cell. Physiol. 198:324–332, 2004 It has been recently established that low‐frequency electromagnetic field (EMFs) exposure induces biological changes and could be associated with increased incidence of cancer, while the issue remains unresolved as to whether high‐frequency EMFs can have hazardous effect on health. Epidemiological studies on association between childhood cancers, particularly leukemia and brain cancer, and exposure to low‐ and high‐frequency EMF suggested an etiological role of EMFs in inducing adverse health effects. To investigate whether exposure to high‐frequency EMFs could affect in vitro cell survival, we cultured acute T‐lymphoblastoid leukemia cells (CCRF‐CEM) in the presence of unmodulated 900 MHz EMF, generated by a transverse electromagnetic (TEM) cell, at various exposure times. We evaluated the effects of high‐frequency EMF on cell growth rate and apoptosis induction, by cell viability (MTT) test, FACS analysis and DNA ladder, and we investigated pro‐apoptotic and pro‐survival signaling pathways possibly involved as a function of exposure time by Western blot analysis. At short exposure times (2–12 h), unmodulated 900 MHz EMF induced DNA breaks and early activation of both p53‐dependent and ‐independent apoptotic pathways while longer continuous exposure (24–48 h) determined silencing of pro‐apoptotic signals and activation of genes involved in both intracellular (Bcl‐2) and extracellular (Ras and Akt1) pro‐survival signaling. Overall our results indicate that exposure to 900 MHz continuous wave, after inducing an early self‐defense response triggered by DNA damage, could confer to the survivor CCRF‐CEM cells a further advantage to survive and proliferate. J. Cell. Physiol. 198: 324–332, 2004. © 2003 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.     

Assessment of intermittent UMTS electromagnetic field effects on blood circulation in the human auditory region using a near-infrared system

The aim of the present study was to assess the potential effects of intermittent Universal Mobile Telecommunications System electromagnetic fields (UMTS‐EMF) on blood circulation in the human head (auditory region) using near‐infrared spectroscopy (NIRS) on two different timescales: short‐term (effects occurring within 80 s) and medium‐term (effects occurring within 80 s to 30 min). For the first time, we measured potential immediate effects of UMTS‐EMF in real‐time without any interference during exposure. Three different exposures (sham, 0.18 W/kg, and 1.8 W/kg) were applied in a controlled, randomized, crossover, and double‐blind paradigm on 16 healthy volunteers. In addition to oxy‐, deoxy‐, and total haemoglobin concentrations ([O₂Hb], [HHb], and [tHb], respectively), the heart rate (HR), subjective well‐being, tiredness, and counting speed were recorded. During exposure to 0.18 W/kg, we found a significant short‐term increase in Δ[O₂Hb] and Δ[tHb], which is small (≈17%) compared to a functional brain activation. A significant decrease in the medium‐term response of Δ[HHb] at 0.18 and 1.8 W/kg exposures was detected, which is in the range of physiological fluctuations. The medium‐term ΔHR was significantly higher (+1.84 bpm) at 1.8 W/kg than for sham exposure. The other parameters showed no significant effects. Our results suggest that intermittent exposure to UMTS‐EMF has small short‐ and medium‐term effects on cerebral blood circulation and HR. Bioelectromagnetics 33:40–54, 2012. © 2011 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.     

Chelation of hippocampal zinc enhances long‐term potentiation and synaptic tagging/capture in CA1 pyramidal neurons of aged rats: implications to aging and memory

Aging is associated with decline in cognitive functions, prominently in the memory consolidation and association capabilities. Hippocampus plays a crucial role in the formation and maintenance of long‐term associative memories, and a significant body of evidence shows that impairments in hippocampal function correlate with aging‐related memory loss. A number of studies have implicated alterations in hippocampal synaptic plasticity, such as long‐term potentiation (LTP), in age‐related cognitive decline although exact mechanisms underlying are not completely clear. Zinc deficiency and the resultant adverse effects on cognition have been well studied. However, the role of excess of zinc in synaptic plasticity, especially in aging, is not addressed well. Here, we have investigated the hippocampal zinc levels and the impairments in synaptic plasticity, such as LTP and synaptic tagging and capture (STC), in the CA1 region of acute hippocampal slices from 82‐ to 84‐week‐old male Wistar rats. We report increased zinc levels in the hippocampus of aged rats and also deficits in the tetani‐induced and dopaminergic agonist‐induced late‐LTP and STC. The observed deficits in synaptic plasticity were restored upon chelation of zinc using a cell‐permeable chelator. These data suggest that functional plasticity and associativity can be successfully established in aged neural networks by chelating zinc with cell‐permeable chelating agents.     

Exposure to 900 MHz electromagnetic field induces an unbalance between pro-apoptotic and pro-survival signals in T-lymphoblastoid leukemia CCRF-CEM cells

It has been recently established that low-frequency electromagnetic field (EMFs) exposure induces biological changes and could be associated with increased incidence of cancer, while the issue remains unresolved as to whether high-frequency EMFs can have hazardous effect on health. Epidemiological studies on association between childhood cancers, particularly leukemia and brain cancer, and exposure to low- and high-frequency EMF suggested an etiological role of EMFs in inducing adverse health effects. To investigate whether exposure to high-frequency EMFs could affect in vitro cell survival, we cultured acute T-lymphoblastoid leukemia cells (CCRF-CEM) in the presence of unmodulated 900 MHz EMF, generated by a transverse electromagnetic (TEM) cell, at various exposure times. We evaluated the effects of high-frequency EMF on cell growth rate and apoptosis induction, by cell viability (MTT) test, FACS analysis and DNA ladder, and we investigated pro-apoptotic and pro-survival signaling pathways possibly involved as a function of exposure time by Western blot analysis. At short exposure times (2-12 h), unmodulated 900 MHz EMF induced DNA breaks and early activation of both p53-dependent and -independent apoptotic pathways while longer continuous exposure (24-48 h) determined silencing of pro-apoptotic signals and activation of genes involved in both intracellular (Bcl-2) and extracellular (Ras and Akt1) pro-survival signaling. Overall our results indicate that exposure to 900 MHz continuous wave, after inducing an early self-defense response triggered by DNA damage, could confer to the survivor CCRF-CEM cells a further advantage to survive and proliferate.     

No effects of mobile phone electromagnetic field on auditory brainstem response

The present study investigated the possible effects of the electromagnetic field (EMF) emitted by an ordinary GSM mobile phone (902.4 MHz pulsed at 217 Hz) on brainstem auditory processing. Auditory brainstem responses (ABR) were recorded in 17 healthy young adults, without a mobile phone at baseline, and then with a mobile phone on the ear under EMF‐off and EMF‐on conditions. The amplitudes, latencies, and interwave intervals of the main ABR components (waves I, III, V) were compared among the three conditions. ABR waveforms showed no significant differences due to exposure, suggesting that short‐term exposure to mobile phone EMF did not affect the transmission of sensory stimuli from the cochlea up to the midbrain along the auditory nerve and brainstem auditory pathways. Bioelectromagnetics 31:48–55, 2010. © 2009 Wiley‐Liss, Inc.     

Short‐term exposure to a 1439‐MHz TDMA signal exerts no estrogenic effect in rats

The aim of this study was to elucidate the possible effects of short‐term exposure to a 1439‐MHz electromagnetic field (EMF) employing time division multiple access (TDMA), which is the basis of the Japanese Personal Digital Cellular system, on estrogenic activity in rats. Sixty‐four ovariectomized female Sprague–Dawley rats were divided into four groups: EMF exposure (EM), sham exposure, cage control, and 17 beta‐estradiol injected (E2). The EM group was exposed, for 4 h per day on three consecutive days, to the 1439‐MHz TDMA signal that produced 5.5–6.1 and 0.88–0.99 W/kg average specific absorption rates in the brain and the whole body, respectively. The uterine wet mass and serum estradiol level significantly increased in the E2 group, while there were no differences among the other three groups. Although negative effects of long‐term EMF exposure must be thoroughly investigated before a final conclusion can be reached, our results do not support the assumption that the high frequency EMF used in cellular phones exerts estrogenic activity. Bioelectromagnetics 31:573–575, 2010. © 2010 Wiley‐Liss, Inc.     

Tempol suppresses micronuclei formation in astrocytes of newborn rats exposed to 50-Hz, 10-mT electromagnetic fields under bleomycin administration

A number of epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors. The aim of this study was to investigate the mutagenetic effects of co-exposure to 50-Hz, 10-mT EMFs and bleomycin (BLM) using an ex vivo newborn rat astrocyte micronucleus assay. We also investigated whether the mutagenetic effects of EMFs were related to active oxygen species by using 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (tempol), a superoxide radical scavenger. Three-day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and BLM (5 or 10mg/kg body weight (BW)) in each group (n=6; total 6 group), and were co-exposed to 50-Hz EMFs and 10mg/kg BW BLM with administration of 200μmol/kg BW tempol in each group (total 4 group). Brain cells were dissociated into single cells, cultured for 96h, incubated with an antibody against glial fibrillary acidic protein, and stained with acridine orange. The frequency of micronucleated astrocytes was determined using a fluorescence microscope. The frequency of micronucleated astrocytes in the 10mg/kg BW bleomycin plus EMF exposure group (Mean±SD: 19.8±5.2‰) was 1.6 times higher than that in the 10mg/kg BW bleomycin plus sham-exposure group (Mean±SD: 12.7±3.3‰) (p<0.05). Analysis of the frequency of micronuclei in astrocytes after co-exposure to EMF and bleomycin for 72h and administration of tempol revealed that, in the EMF exposure group, the frequency of micronuclei in rats administered with 10mg/kg BW bleomycin and treated with tempol (Mean±SD: 11.2±1.9‰) was 40% of that in rats administered with the same dose of bleomycin and physiological saline (Mean±SD: 28.0±15.0‰) (p<0.01). Results of the current study suggested that the mechanism responsible for the elevated frequency of micronuclei in astrocytes of rats co-exposed to BLM and EMFs is related to active oxygen species.     

Reduction in glutamate uptake is associated with extrasynaptic NMDA and metabotropic glutamate receptor activation at the hippocampal CA1 synapse of aged rats

This study aims to determine whether the regulation of extracellular glutamate is altered during aging and its possible consequences on synaptic transmission and plasticity. A decrease in the expression of the glial glutamate transporters GLAST and GLT‐1 and reduced glutamate uptake occur in the aged (24–27 months) Sprague–Dawley rat hippocampus. Glutamatergic excitatory postsynaptic potentials recorded extracellularly in ex vivo hippocampal slices from adult (3–5 months) and aged rats are depressed by DL‐TBOA, an inhibitor of glutamate transporter activity, in an N‐Methyl‐d‐ Aspartate (NMDA)‐receptor‐dependent manner. In aged but not in young rats, part of the depressing effect of DL‐TBOA also involves metabotropic glutamate receptor (mGluRs) activation as it is significantly reduced by the specific mGluR antagonist d‐methyl‐4‐carboxy‐phenylglycine (MCPG). The paired‐pulse facilitation ratio, a functional index of glutamate release, is reduced by MCPG in aged slices to a level comparable to that in young rats both under control conditions and after being enhanced by DL‐TBOA. These results suggest that the age‐associated glutamate uptake deficiency favors presynaptic mGluR activation that lowers glutamate release. In parallel, 2 Hz‐induced long‐term depression is significantly decreased in aged animals and is fully restored by MCPG. All these data indicate a facilitated activation of extrasynaptic NMDAR and mGluRs in aged rats, possibly because of an altered distribution of glutamate in the extrasynaptic space. This in turn affects synaptic transmission and plasticity within the aged hippocampal CA1 network.     

Characteristics of the electrical activity in hippocampal slices in mice with Corazol kindling

It has been shown in experiments on hippocampal slices of (CBA X C57BL/6)F1 mice with corazol kindling that the threshold of the appearance of the induced seizure discharge (ISD) in the area CA1 was decreased by stimulation of Schaffer collaterals. Diazepam provoked an increase in seizure susceptibility to corazol and penicillin and reduction of the ISD. The data suggest that alterations in neuronal reactivity, which follow kindling, can be found in an individual hippocampal segment, thus making it possible to investigate this phenomenon at the synaptic and molecular levels.     

Deprotonation of glutamic acid induced by weak magnetic field: an FTIR-ATR study

It has been claimed that weak extremely low frequency electromagnetic fields (ELF‐EMFs) can affect biochemical reactions and a wide‐ranging body of literature is available on this topic. Nevertheless, the physical nature of these effects remains largely unknown. We investigated the influence of ELF‐EMF on glutamic acid solutions using Fourier transform infrared‐attenuated total reflectance (FTIR‐ATR) spectra. Samples were exposed for 10, 20, or 30 min to a weak EMF generated by Helmoltz coils, and then placed in a spectrometer. After exposure, those solutions that had a pH lower than the isoelectric point tended to show a shift toward the deprotonation of the carboxylic group, while solutions having a pH greater than the isoelectric point showed the deprotonation of the residual amine group. Moreover, at low pH values, we also detected a shift of the δ_antisym band of the amine. The effects lasted a few minutes after exposure before the native configuration was restored. The spectral modifications were observed after each independent exposure to EMFs, and the same effects were seen by varying the frequencies in the range of 0–7 kHz. Therefore, the hypothesis of the existence of a resonant frequency that has been proposed elsewhere cannot be supported by the results of this study. The most surprising characteristic of this effect is the long‐lasting nature of the perturbation, which is hard to be explained in terms of short‐living excitations in biological matter. Bioelectromagnetics 32:218–225, 2011. © 2010 Wiley‐Liss, Inc.     

Electromagnetic exposure of scaffold-free three-dimensional cell culture systems

In recent years, a number of in vitro studies have reported on the possible athermal effects of electromagnetic exposure on biological tissue. Typically, this kind of study is performed on monolayers of primary cells or cell lines. However, two‐dimensional cell layer systems lack physiological relevance since cells in vivo are organized in a three‐dimensional (3D) architecture. In monolayer studies, cell‐cell and cell‐ECM interactions obviously differ from live tissue and scale‐ups of experimental results to in vivo systems should be considered carefully. To overcome this problem, we used a scaffold‐free 3D cell culture system, suitable for the exploration of electrophysiological effects due to electromagnetic fields (EMF) at 900 MHz. Dissociated cardiac myocytes were reaggregated into cellular spheres by constant rotation, and non‐invasive extracellular recordings of these so‐called spheroids were performed with microelectrode arrays (MEA). In this study, 3D cell culture systems were exposed to pulsed EMFs in a stripline setup. We found that inhomogeneities in the EMF due to electrodes and conducting lines of the MEA chip had only a minor influence on the field distribution in the spheroid if the exposure parameters were chosen carefully. Bioelectromagnetics 32:351–359, 2011. © 2011 Wiley‐Liss, Inc.     

Hypersensitivity to RF fields emitted from CDMA cellular phones: A provocation study

With the number of cellular phone users rapidly increasing, there is a considerable amount of public concern regarding the effects that electromagnetic fields (EMFs) from cellular phones have on health. People with self‐attributed electromagnetic hypersensitivity (EHS) complain of subjective symptoms such as headaches, insomnia, and memory loss, and attribute these symptoms to radio frequency (RF) radiation from cellular phones and/or base stations. However, EHS is difficult to diagnose because it relies on a person's subjective judgment. Various provocation studies have been conducted on EHS caused by Global System for Mobile Communications (GSM) phones in which heart rate and blood pressure or subjective symptoms were investigated. However, there have been few sham‐controlled provocation studies on EHS with Code Division Multiple Access (CDMA) phones where physiological parameters, subjective symptoms, and perception of RF radiation for EHS and non‐EHS groups were simultaneously investigated. In this study, two volunteer groups of 18 self‐reported EHS and 19 non‐EHS persons were tested for both sham and real RF exposure from CDMA cellular phones with a 300 mW maximum exposure that lasted half an hour. We investigated not only the physiological parameters such as heart rate, respiration rate, and heart rate variability (HRV), but also various subjective symptoms and the perception of EMF. In conclusion, RF exposure did not have any effects on physiological parameters or subjective symptoms in either group. As for EMF perception, there was no evidence that the EHS group better perceived EMF than the non‐EHS group. Bioelectromagnetics 30:641–650, 2009. © 2009 Wiley‐Liss, Inc.     

Nonthermal electromagnetic fields and estimation of the probable development of the convulsive syndrome

Development of the convulsive syndrome occurs during exposure to electromagnetic fields (EMFs) during physiotherapy and under conditions of professional work. Some researchers believe that EMFs may have medical effects during the treatment of the epilepsy syndrome. Some publications have noted the development of epileptic convulsions in experiments using EMF exposures at various frequencies. Four conditions that may promote the development of convulsions upon EMF exposure are considered.     

The effects of simultaneous combined exposure to CDMA and WCDMA electromagnetic fields on rat testicular function

Wireless mobile phones and other telecommunication devices are used extensively in daily life. We therefore examined the effects of combined exposure to radiofrequency electromagnetic fields (RF‐EMF) on rat testicular function, specifically with respect to sensitive processes such as spermatogenesis. Male rats were exposed to single code division multiple access (CDMA) and wideband code division multiple access (WCDMA) RF signals for 12 weeks. The RF exposure schedule comprised 45 min/day, 5 days/week for a total of 12 weeks. The whole‐body average specific absorption rate (SAR) of CDMA and WCDMA was 2.0 W/kg each or 4.0 W/kg in total. We then investigated the correlates of testicular function such as sperm count in the cauda epididymis, testosterone concentration in the blood serum, malondialdehyde concentrations in the testes and epididymis, frequency of spermatogenesis stages, and appearance of apoptotic cells in the testes. We also immunoblotted for p53, bcl2, GADD45, cyclin G, and HSP70 in the testes of sham‐ and combined RF‐exposed animals. Based on the results, we concluded that simultaneous exposure to CDMA and WCDMA RF‐EMFs at 4.0 W/kg SAR did not have any observable adverse effects on rat spermatogenesis. Bioelectromagnetics 33:356–364, 2012. © 2011 Wiley Periodicals, Inc.     

Effect of intermittent and continuous exposure to electromagnetic fields on cultured hippocampal cells

This study was designed to assess the effect of 50 Hz electromagnetic fields (EMFs) on hippocampal cell cultures in the presence or absence of either sodium nitroprusside (SNP, a NO donor) or Fe2+ induced oxidative stress. One week old cultured rat hippocampal cells were exposed to either intermittent EMFs (IEMFs, 50 Hz, 0-5 mT, 1 min ON/OFF cycles, repeated 10 times every 2 h, 6 times/day during 48 h) or continuous EMFs (CEMFs, 50 Hz, 0-5 mT for 48 h). In a second set of experiments, the effect on such EMFs applied in combination with oxidative stress induced by 0.5 microM Fe2+ or SNP was estimated. At the end of both sets of experiments, cell mortality was assessed by lactate dehydrogenase measurements (LDH). Neither type of exposure to EMFs was observed to modify the basal rate of cell mortality. The exposure to CEMFs in presence of either NO or Fe2+ did not induce any significant increase in cell death. However, when cells were exposed to EMFs in the presence of NO, we observed a significant increase in cell death of 11 and 23% (P<0.001) at 2.5 and 5 mT, respectively. This effect had some specificity because IEMFs did not modify the effect of Fe2+ on cell mortality. Although the effects of IEMFs reported in this study were only observed at very high intensities, our model may prove valuable in trying to identify one cellular target of EMFs.