Effect of static magnetic fields on bioelectric properties of the Br and N1 neurons of snail Helix pomatia

The effects of 2.7 mT and 10 mT static magnetic fields were investigated on two identified neurons with different bioelectric properties of the snail Helix pomatia. Membrane resting potential, amplitude, spiking frequency, and duration of action potential were measured. The two neurons of H. pomatia, parabolic burster Br and silent N₁, showed different responses to a static magnetic field. The magnetic field of 2.7 mT intensity caused changes in the amplitude and duration of action potential of the Br neuron, whereas the 10 mT magnetic field changed the resting potential, amplitude spike, firing frequency, and duration of action potential of the Br neuron. Bioelectric parameters measured on the N₁ neuron did not change significantly in these magnetic fields.     

Correlation of magnetic AC field on cardiac myocyte Ca2+ transients at different magnetic DC levels

The purpose of this study was to determine the effect of extremely low frequency and weak magnetic fields (WMF) on cardiac myocyte Ca²⁺ transients, and to explore the involvement of potassium channels under the WMF effect. In addition, we aimed to find a physical explanation for the effect of WMF on cardiac myocyte Ca²⁺ transients. Indo‐1 loaded cells, which were exposed to a WMF at 16 Hz and 40 nT, demonstrated a 75 ± 4% reduction in cytosolic Ca²⁺ transients versus control. Treatment with the K_ATP channel blocker, glibenclamide, followed by WMF at 16 Hz exposure, blocked the reduction in cytosolic calcium transients while treatment with pinacidil, a K_ATP channel opener, or chromanol 293B, a selective potassium channel blocker of the delayed rectifier K⁺ channels, did not inhibit the effect. Based on these finding and the ion cyclotron resonance frequency theory, we further investigated the effect of WMF by changing the direct current (DC) magnetic field (B₀). When operating different DC magnetic fields we showed that the WMF value changed correspondingly: for B₀ = 44.5 µT, the effect was observed at 17.05 Hz; for B₀ = 46.5 µT, the effect was observed at 18.15 Hz; and for B₀ = 49 µT the effect was observed at 19.1 Hz. We can conclude that the effect of WMF on Ca²⁺ transients depends on the DC magnetic field level. Bioelectromagnetics 33:634–640, 2012. © 2012 Wiley Periodicals, Inc.     

The influence of extremely weak alternating magnetic fields on the regeneration of planarians and the gravitropic response of plants

The influence of extremely weak alternating magnetic fields (EW AMF) directed collinearly to the static Earth magnetic field on the rate of regeneration of planarians and the rate of gravitropic response in the stem segments of flax has been studied. The value of bioeffects of EW AMF is determined by the parameter γB _AC/f, where γ is the gyromagnetic ratio of the magnetic moments induced by the orbital movements of electrons in atoms, and B _AC and f correspond to magnetic induction and frequency of the alternating magnetic component. It was shown that the magnitude of bioeffects depends on the amplitude (at fixed 1000 Hz — frequency) and frequency (at fixed 192 nT — amplitude) of the alternating component. Maxima of bioeffects are observed at γB _AC/f = 0.9; 2.75, and minor maxima γB _AC/f = 4.5; 6.1. The bioeffects are absent at γB _AC/f =1.8, 3.8, 5.3, 6.7. The positions of the maxima and minima of bioeffects correspond to the theoretical prediction (at γ = 14000 Hz/μT). Primary targets for the EW AMF of this type are the magnetic moments induced by the orbital movements of electrons in atoms.     

Light-dependent and -independent behavioral effects of extremely low frequency magnetic fields in a land snail are consistent with a parametric resonance mechanism

Exposure to extremely low frequency (ELF) magnetic fields has been shown to attenuate endogenous opioid peptide mediated antinociception or “analgaesia” in the terrestrial pulmonate snail, Cepaea nemoralis. Here we examine the roles of light in determining this effect and address the mechanisms associated with mediating the effects of the ELF magnetic fields in both the presence and absence of light. Specifically, we consider whether the magnetic field effects involve an indirect induced electric current mechanism or a direct effect such as a parametric resonance mechanism (PRM). We exposed snails in both the presence and absence of light at three different frequencies (30, 60, and 120 Hz) with static field values (B_DC) and ELF magnetic field amplitude (peak) and direction (B_AC) set according to the predictions of the PRM for Ca²⁺. Analgaesia was induced in snails by injecting them with an enkephalinase inhibitor, which augments endogenous opioid (enkephalin) activity. We found that the magnetic field exposure reduced this opioid-induced analgaesia significantly more if the exposure occurred in the presence rather than the absence of light. However, the percentage reduction in analgaesia in both the presence and absence of light was not dependent on the ELF frequency. This finding suggests that in both the presence and the absence of light the effect of the ELF magnetic field was mediated by a direct magnetic field detection mechanism such as the PRM rather than an induced current mechanism. Bioelectromagnetics 18:284–291, 1997. © 1997 Wiley-Liss, Inc.     

ELF-ELECTROMAGNETIC FIELDS INHIBIT THE PROLIFERATION OF HUMAN CANCER CELLS AND INDUCE APOPTOSIS

Weak and low-frequency pulsating electromagnetic fields (ELF-MF) can be applied to change cell metabolism, if cells are treated in a specific range of frequency and amplitude. In our case, the influence on proliferation of human K562 cells has been studied by applying a sinusoidal 50 Hz field of magnetic flux densities (B) between 2 and 13 mT for 2 or 4 days. In repeating all runs three times—counting each day—no difference between experiment and control was found below 6 mT. However, stronger field amplitudes inhibit cell division and induce apoptosis and necrosis as shown by flow cytometry. Treatment with ≥10 mT decreases the number of living cells to only 2% of the control. This electromagnetically induced apoptosis may be a first step for a noninvasive treatment of cancer tissue for inhibition of its proliferation.     

Behavioural evidence that magnetic field effects in the land snail,Cepaea nemoralis,might not depend on magnetite or induced electric currents

Although extremely low frequency (ELF) magnetic fields (<300 Hz) appear to exert a variety of biological effects, the magnetic field sensing/transduction mechanism(s) remains to be established. Here, using the inhibitory effects of magnetic fields on endogenous opioid peptide-mediated “analgaesic” response of the land snail. Cepaea nemoralis, we addressed the mechanism(s) of action of ELF magnetic fields. Indirect mechanisms involving both induced electric fields and direct magnetic field detection mechanisms (e.g., magnetite, parametric resonance) were evaluated. Snails were exposed to a static magnetic field (B_DC=78±1 μT) and to a 60 Hz magnetic field (B_AC=299±1 μT peak) with the angle between the static and 60 Hz magnetic fields varied in eight steps between 0° and 90°. At 0° and 90°, the magnetic field reduced opioid-induced analgaesia by approximately 20%, and this inhibition was increased to a maximum of 50% when the angle was between 50° and 70°. Because B_AC was fixed in amplitude, direction, and frequency, any induced electric currents would be constant independent of the B_AC/B_DC angle. Also, an energy transduction mechanism involving magnetite should show greatest sensitivity at 90°. Therefore, the energy transduction mechanism probably does not involve induced electric currents or magnetite. Rather, our results suggest a direct magnetic field detection mechanism consistent with the parametric resonance model proposed by Lednev. © 1996 Wiley-Liss, Inc.     

Effects and molecular mechanisms of the biological action of weak and extremely weak magnetic fields

A number of effects of weak combined (static and alternating) magnetic fields with an alternating component of tens and hundreds nT at a collinear static field of 42 μT, which is equivalent to the geomagnetic field, have been found: activation of fission and regeneration of planarians Dugesia tigrina, inhibition of the growth of the Ehrlich ascites carcinoma in mice, stimulation of the production of the tumor necrosis factor by macrophages, decrease in the protection of chromatin against the action of DNase 1, and enhancement of protein hydrolysis in systems in vivo and in vitro. The frequency and amplitude ranges for the alternating component of weak combined magnetic fields have been determined at which it affects various biological systems. Thus, the optimal amplitude at a frequency of 4.4 Hz is 100 nT (effective value); at a frequency of 16.5 Hz, the range of effective amplitudes is broader, 150–300 nT; and at a frequency of 1 (0.5) Hz, it is 300 nT. The sum of close frequencies (e.g., 16 and 17 Hz) produces a similar biological effect as the product of the modulating (0.5 Hz) and carrying frequencies (16.5 Hz), which is explained by the ratio A = A ₀sinω₁ t + A ₀sinω₂ t = 2A ₀sin(ω₁ + ω₂)t/2cos(ω₁–ω₂)t/2. The efficiency of magnetic signals with pulsations (the sum of close frequencies) is more pronounced than that of sinusoidal frequencies. These data may indicate the presence of several receptors of weak magnetic fields in biological systems and, as a consequence, a higher efficiency of the effect at the simultaneous adjustment to these frequencies by the field. Even with consideration of these facts, the mechanism of the biological action of weak combined magnetic fields remains still poorly understood.     

Effect of static magnetic fields on the budding of yeast cells

The effect of static magnetic fields on the budding of single yeast cells was investigated using a magnetic circuit that was capable of generating a strong magnetic field (2.93 T) and gradient (6100 T² m^?1). Saccharomyces cerevisiae yeast cells were grown in an aqueous YPD agar in a silica capillary under either a homogeneous or inhomogeneous static magnetic field. Although the size of budding yeast cells was only slightly affected by the magnetic fields after 4 h, the budding angle was clearly affected by the direction of the homogeneous and inhomogeneous magnetic fields. In the homogeneous magnetic field, the budding direction of daughter yeast cells was mainly oriented in the direction of magnetic field B. However, when subjected to the inhomogeneous magnetic field, the daughter yeast cells tended to bud along the axis of capillary flow in regions where the magnetic gradient, estimated by B(dB/dx), were high. Based on the present experimental results, the possible mechanism for the magnetic effect on the budding direction of daughter yeast cells is theoretically discussed. Bioelectromagnetics 31:622–629, 2010. © 2010 Wiley‐Liss, Inc.     

Enhancement of the hydrolysis activity of F0F1‐ATPases using 60 Hz magnetic fields

The effects of extremely low frequency (ELF) magnetic fields on membrane F₀F₁‐ATPase activity have been studied. When the F₀F₁‐ATPase was exposed to 60 Hz magnetic fields of different magnetic intensities, 0.3 and 0.5 mT magnetic fields enhanced the hydrolysis activity, whereas 0.1 mT exposure caused no significant changes. Even if the F₀F₁‐ATPase was inhibited by N,N‐dicyclohexylcarbodiimide, its hydrolysis activity was enhanced by a 0.5 mT 60 Hz magnetic field. Moreover, when the chromatophores which were labeled with F‐DHPE were exposed to a 0.5 mT, 60 Hz magnetic field, it was found that the pH of the outer membrane of the chromatophore was unchanged, which suggested that the magnetic fields used in this work did not affect the activity of F0. Taken together, our results show that the effects of magnetic fields on the hydrolysis activity of the membrane F₀F₁‐ATPases were dependent on magnetic intensity and the threshold intensity is between 0.1 and 0.3 mT, and suggested that the F1 part of F₀F₁‐ATPase may be an end‐point affected by magnetic fields. Bioelectromagnetics 30:663–668, 2009. © 2009 Wiley‐Liss, Inc.     

Oviposition and development of Drosophila modified by magnetic fields

Drosophila flies placed in a habitat with two lateral boxes demonstrated sensitivity to magnetic fields: Oviposition decreased by exposure to pulsated extremely low frequency (ELF) (100)Hz, 1.76 miliTesla (mT) and sinusosidal fields (50 Hz, 1 mT), while there was no initial effect of exposure to a static magnetic field (4.5 mT). Drosophila eggs treated for 48 h with the above described fields showed that (1) mortality of eggs was lower in controls than in eggs exposed to all tested magnetic fields; (2) mortality of larvae increased when a permanent magnet was used; (3) mortality of pupae was highest when a permanent magnet was used; and (4) general adult viability was highest in controls (67%) and diminished progressively when eggs were exposed to pulsated (55%), sinusoidal (45%), and static (35%) magnetic fields.     

Analysis of human brain exposure to low‐frequency magnetic fields: A numerical assessment of spatially averaged electric fields and exposure limits

Compliance with the established exposure limits for the electric field (E‐field) induced in the human brain due to low‐frequency magnetic field (B‐field) induction is demonstrated by numerical dosimetry. The objective of this study is to investigate the dependency of dosimetric compliance assessments on the applied methodology and segmentations. The dependency of the discretization uncertainty (i.e., staircasing and field singularity) on the spatially averaged peak E‐field values is first determined using canonical and anatomical models. Because spatial averaging with a grid size of 0.5 mm or smaller sufficiently reduces the impact of artifacts regardless of tissue size, it is a superior approach to other proposed methods such as the 99th percentile or smearing of conductivity contrast. Through a canonical model, it is demonstrated that under the same uniform B‐field exposure condition, the peak spatially averaged E‐fields in a heterogeneous model can be significantly underestimated by a homogeneous model. The frequency scaling technique is found to introduce substantial error if the relative change in tissue conductivity is significant in the investigated frequency range. Lastly, the peak induced E‐fields in the brain tissues of five high‐resolution anatomically realistic models exposed to a uniform B‐field at ICNIRP and IEEE reference levels in the frequency range of 10 Hz to 100 kHz show that the reference levels are not always compliant with the basic restrictions. Based on the results of this study, a revision is recommended for the guidelines/standards to achieve technically sound exposure limits that can be applied without ambiguity. Bioelectromagnetics 34:375–384, 2013. © 2012 Wiley Periodicals, Inc.     

Radio frequency magnetic field effects on molecular dynamics and iron uptake in cage proteins

The protein ferritin has a natural ferrihydrite nanoparticle that is superparamagnetic at room temperature. For native horse spleen ferritin, we measure the low field magnetic susceptibility of the nanoparticle as 2.2 × 10^?6 m³ kg^?1 and its Néel relaxation time at about 10^?10 s. Superparamagnetic nanoparticles increase their internal energy when exposed to radio frequency magnetic fields due to the lag between magnetization and applied field. The energy is dissipated to the surrounding peptidic cage, altering the molecular dynamics and functioning of the protein. This leads to an increased population of low energy vibrational states under a magnetic field of 30 µT at 1 MHz, as measured via Raman spectroscopy. After 2 h of exposure, the proteins have a reduced iron intake rate of about 20%. Our results open a new path for the study of non‐thermal bioeffects of radio frequency magnetic fields at the molecular scale. Bioelectromagnetics 31:311–317, 2010. © 2010 Wiley‐Liss, Inc.     

Permeability changes of connexin32 hemi channels reconstituted in liposomes induced by extremely low frequency, low amplitude magnetic fields

The effect of extremely low frequency and low amplitude magnetic fields on gap junctional permeability was investigated by using reconstituted connexin32 hemi channel in liposomes. Cytochrome c was loaded inside these proteoliposomes and its reduction upon addition of ascorbate in the bulk aqueous phase was adopted as the index of hemi channel permeability. The permeability rate of the hemi channels, expressed as ΔA/min, was dependent on the incubation temperature of proteoliposomes. The effect of exposures to magnetic fields at different frequencies (7, 13 and 18 Hz) and amplitudes (50, 50 and 70 μT, respectively), and at different temperatures (16, 18 and 24 °C) was studied. Only the exposure of proteoliposomes to 18-Hz (B_acpeak and B_dc=70 μT) magnetic field for 60 min at 16±0.4 °C resulted in a significant enhancement of the hemi channel permeability from ΔA/min=0.0007±0.0002 to ΔA/min=0.0010±0.0001 (P=0.030). This enhancement was not found for magnetic field exposures of liposomes kept at the higher temperatures tested. Temperature appears to influence lipid bilayer arrangement in such a way as being capable to mask possible effects induced by the magnetic field. Although the observed effect was very low, it seems to confirm the applicability of our model previously proposed for the interaction of low frequency electromagnetic fields with lipid membrane.     

Growth inhibition of Staphylococcus aureus induced by low‐frequency electric and electromagnetic fields

Magnetic field therapy is an established technique in the treatment of pseudarthrosis. In cases of osteomylitis, palliation is also observed. This study focuses on the impact of different electric and electromagnetic fields on the growth of Staphylococcus aureus by in vitro technologies. Cultures of Staphylococcus aureus in fluid and gel‐like medium were exposed to a low‐frequency electromagnetic field, an electromagnetic field combined with an additional electric field, a sinusoidal electric field and a static electric field. In gel‐like medium no significant difference between colony‐forming units of exposed samples and non‐exposed references was detected. In contrast, Staphylococcus aureus concentrations in fluid medium could clearly be reduced under the influence of the four different applied fields within 24 h of experiment. The strongest effects were observed for the direct current electric field which could decrease CFU/ml of 37%, and the low‐frequency electromagnetic field with additional induced electric alternating field with a decrease of Staphylococci concentration by 36%. The effects of the electromagnetic treatment on Staphylococci within fluid medium are significantly higher than in gel‐like medium. The application of low‐frequency electromagnetic fields corroborates clinical situations of bone infections during magnetic field therapy. Bioelectromagnetics 30:270–279, 2009. © 2009 Wiley‐Liss, Inc.     

Magnetic field effects on coenzyme B12-dependent enzymes: Validation of ethanolamine ammonia lyase results and extension to human methylmalonyl CoA mutase

Enzymes with radical-pair intermediates have been considered as a likely target for purported magnetic field effects in humans. The bacterial enzyme ethanolamine ammonia lyase and the human enzyme methylmalonyl-CoA mutase catalyze coenzyme B₁₂-dependent rearrangement reactions. A common step in the mechanism of these two enzymes is postulated to be homolysis of the cobalt-carbon bond of the cofactor to generate a spin-correlated radical pair consisting of the 5′-deoxyadenosyl radical and cob(II)alamin [Ado^· Cbl(II)]. Thus, the reactions catalyzed by these enzymes are expected to be sensitive to an applied magnetic field according to the same principles that control radical pair chemical reactions. The magnetic field effect on ethanolamine ammonia lyase reported previously has been corroborated independently in one of the authors' laboratory. However, neither the human nor the bacterial mutase from Propionibacterium shermanii exhibits a magnetic field effect that could be greater than about 15%, considering the error limit imposed by the uncertainty of the coupled assay. Our studies suggest that putative magnetic field effects on physiological processes are not likely to be mediated by methylmalonyl-CoA mutase. Bioelectromagnetics 18:506–513, 1997. © 1997 Wiley-Liss, Inc.     

PRELIMINARY EVIDENCE FOR WEAK MAGNETIC FIELD EFFECTS ON MECHANOSENSITIVE ION CHANNEL SUBCONDUCTING STATES IN ESCHERICHIA COLI

Investigations on the effects of applied magnetic fields on mechanosensitive (MS) ion channel activity in Escherichia coli reveal an enhancement of subconducting activity with field exposure. In nine of 10 experimental runs, more subconducting activity was observed during the application of a 1.35 millitesla (mT) DC magnetic field when compared to control periods before field application (p=.1). This is an indication that these weak fields may interfere with the function of MS channel subunits in this bacterium and may have implications for the interaction of applied magnetic fields with human MS ion channels.     

The pattern of exposure to static magnetic field of nurses involved in activities related to contrast administration into patients diagnosed in 1.5 T MRI scanners

Static magnetic fields (SMFs) and time-varying electromagnetic fields exposure is necessary to obtain the diagnostic information regarding the structure of patient's tissues, by the use of magnetic resonance imaging (MRI) scanners. A diagnostic procedure may also include the administration of pharmaceuticals called contrast, which are to be applied to a patient during the examination. The nurses involved in administering contrast into a patient during the pause in examination are approaching permanently active magnets of MRI scanners and are exposed to SMF. There were performed measurements of spatial distribution of SMF in the vicinity of MRI magnets and parameters of personal exposure of nurses (i.e. individual exposimetric profiles of variability in time of SMF affecting the nurse who is performing tasks in the vicinity of magnet, characterized by statistical parameters of recorded magnetic flux density affecting the nurse). The SMF exposure in the vicinity of various MRI magnets depends on both magnetic flux density of the main field B ₀ (applicable to a patient) and the construction of the scanner, but the most important factor determining the workers' exposure is the work practice. In the course of a patient's routine examination in scanners of B ₀ = 1.5 T, the nurses are present over ～0.4–2.9 min in SMF exceeding 0.03% of B ₀ (i.e. 0.5 mT), but only sometimes they are present in SMF exceeding 5% of B ₀ (i.e. 75 mT). When patients need more attention because of their health status/condition, the nurses' exposure may be significantly longer – it may even exceed 10 min and 30% of B ₀ (i.e. 500 mT). We have found that the level of exposure of nurses to SMF may vary from < 5% of the main field (a median value: 0.5–1.5%; inter-quartile range: 0.04–8.8%; max value: 1.3–12% of B ₀) when a patient is moved from the magnets bore before contrast administration, up to the main field level (B ₀) when a patient stays in the magnets bore and nurse is crawling into the bore.     

Potentials of radio-frequency field gradient NMR microscopy in environmental science

An understanding of transport, flow, diffusivity and mass transfer processes is of central importance in many fields of environmental biotechnology such as biofilm, bioreactor and membrane engineering, soil and groundwater bioremediation, and wastewater treatment. Owing to its remarkable sensitivity to molecular displacements and to its noninvasive and nondestructive character, pulsed field gradient (PFG) nuclear magnetic resonance (NMR) can be a valuable tool for investigating such processes. In conventional NMR microscopy, spatial encoding is achieved by using static magnetic field gradients (B ₀ gradients). However, an interesting alternative is to use radio-frequency magnetic field gradients (RF or B ₁ gradients). Although the latter are less versatile than the former, RF field gradient microscopy is particularly suitable for dealing with heterogeneous systems such as porous media because of its quasi-immunity to background static magnetic field gradients arising from magnetic susceptibility inhomogeneities, unlike the B ₀ gradients microscopy. Here, we present an overview of basic principles and the main features of this technique, which is still relatively unused. Different examples of diffusion imaging illustrate the potentialities of the method in both micro-imaging and the measurement of global or local diffusion coefficients within membranes and at liquid–solid interfaces. These examples suggest that a number of environmental problems could benefit from this technique. Different future prospects of application of B ₁ gradient NMR microscopy in environmental biotechnology are considered. Journal of Industrial Microbiology & Biotechnology (2001) 26, 53–61. Received 09 February 2000/ Accepted in revised form 07 August 2000     

EFFECTS OF SINUSOIDAL MAGNETIC FIELD ON ADHERENCE INHIBITION OF LEUKOCYTES

Response of leukocytes to exposure to an external magnetic field with frequency 50 Hz and sinusoidal waveform was investigated in vitro using the leukocyte adherence inhibition (LAI) assay developed as a measure of cell-mediated immunity. Leukocytes taken from healthy humans adhere, but their adherence decreases after 1 hr of exposure to the magnetic field with magnetic induction of 1 and 10 mT. The majority of leukocytes taken from cancer patients before any medical treatment do not adhere, and exposure to the magnetic field increases adherence. Correlation between the LAI assay results and the cell-mediated immunity suggests an effect of magnetic fields on leukocyte immune function in humans.     

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.