No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The Effects of Weak Magnetic Fields on Radical Pairs
Abstract
It is proposed that radical concentrations can be modified by combinations of weak, steady and alternating magnetic fields that modify the population distribution of the nuclear and electronic spin state, the energy levels and the alignment of the magnetic moments of the components of the radical pairs. In low external magnetic fields, the electronic and nuclear angular momentum vectors are coupled by internal forces that outweigh the external fields' interactions and are characterized in the Hamiltonian by the total quantum number F. Radical pairs form with their unpaired electrons in singlet (S) or triplet (T) states with respect to each other. At frequencies corresponding to the energy separation between the various states in the external magnetic fields, transitions can occur that change the populations of both electron and nuclear states. In addition, the coupling between the nuclei, nuclei and electrons, and Zeeman shifts in the electron and nuclear energy levels can lead to transitions with resonances spanning frequencies from a few Hertz into the megahertz region. For nuclear energy levels with narrow absorption line widths, this can lead to amplitude and frequency windows. Changes in the pair recombination rates can change radical concentrations and modify biological processes. The overall conclusion is that the application of magnetic fields at frequencies ranging from a few Hertz to microwaves at the absorption frequencies observed in electron and nuclear resonance spectroscopy for radicals can lead to changes in free radical concentrations and have the potential to lead to biologically significant changes. Bioelectromagnetics. 2014;9999:1–10. © 2014 Wiley Periodicals, Inc.
... Weak and super-weak electromagnetic fields represent an emerging aspects in modern science with potentially profound implications across the natural sciences and medicine [1]. They cover a range of low frequency and intensity exposures that have recently been shown to interact with biological systems. ...
... Research in this fledgling field indicates weak and super-weak fields can influence fundamental biological processes ranging from gene expression to tissue growth and regeneration [15], though the underlying mechanisms remain incompletely elucidated. Nonthermal field interactions involving electron transfers, radical pairs, or resonant absorption have been proposed as potential modes of bioactivity [1]. Nonetheless, the possibility that such fields may be harnessed to benefit human health has attracted growing interest across disciplines spanning physics, biology and medicine [4]. ...
Mesenchymal stem cells (MSCs) have emerged as a promising tool for regenerative medicine due to their multipotency and immunomodulatory properties. According to recent research, exposing MSCs to super-low-intensity microwave radiation can have a significant impact on how they behave and operate. This review provides an overview of the most recent studies on the effects of microwave radiation on MSCs with power densities that are much below thermal values. Studies repeatedly show that non-thermal mechanisms affecting calcium signaling, membrane transport, mitochondrial activity, along ion channel activation may increase MSC proliferation, differentiation along mesodermal lineages, paracrine factor secretion, and immunomodulatory capabilities during brief, regulated microwave exposures. These bioeffects greatly enhance MSC regeneration capability in preclinical models of myocardial infarction, osteoarthritis, brain damage, and other diseases. Additional study to understand microwave treatment settings, biological processes, and safety assessments will aid in the translation of this unique, non-invasive strategy of activating MSCs with microwave radiation to improve cell engraftment, survival, and tissue healing results. Microwave-enhanced MSC treatment, if shown safe and successful, might have broad relevance as a novel cell-based approach for a variety of regenerative medicine applications.
... 3.1. SMF Regulates the Ability of HD Water Pre-Exposed to a Magnetic Field to Enhance ROS Production by Neutrophils Weak and ultra-weak magnetic fields have pronounced biophysical effects, associated with the formation of free radicals and respiratory burst [12][13][14][15]. Earlier, we showed that the treatment of water with a CMF (SMF of 60 µT, AMF of 150 nT, and the variable component frequency of 12.6 or 48.5 Hz) affects the ability of these samples to regulate the activity of neutrophils to produce ROS in different ways. ...
... Currently, there are different opinions on this issue: the ability of water after exposure to the CMF to enhance ROS production by neutrophils can be associated with "cyclotron" resonance [18] or be the consequence of the correspondence of the AMF frequency to the magnetic moments of protons in molecules [13,19,20], in clusters or hydrated ions, or other general physical mechanisms [21][22][23]. This assumption is supported by works on changes in the refractive index under conditions of weak magnetic fields [24], as well as studies defining water as a tunable oscillator [18]. ...
The influence of magnetic fields on the physico–chemical properties of water and aqueous solutions is well known. We have previously shown that weak combined magnetic fields with a 60 µT static component and a 100 nT (at 12.6 Hz) variable component are able to activate neutrophils, both directly and indirectly, through water pre-incubated in these fields. The ability to influence the activity of neutrophils was retained in serial dilutions of water, but only when a mechanical effect (shaking) was applied at each dilution step. Here, we confirm that combined magnetic fields are required for the formation of the stimulatory activity of water on ROS production by neutrophils. For the first time, we determined the threshold values of a constant magnetic field (at least 350–550 nT) necessary to maintain this activity in a series of successive dilutions. Additionally, the biophysical properties of various dilutions appeared to be not identical. This confirms that the number of technological steps (successive dilutions with physical influence) is a key factor that determines the activity of highly diluted samples.
... It is necessary to evaluate the effects of HMF exposure, and to develop effective counteractive strategy against the HMF to protect the health of astronauts and workers who are exposed to occupational HMF [16]. Some studies on the mechanisms underlying the biological effects of a HMF have been carried out [3].These studies give the mechanism of the biological effects of a HMF at the cellular level [18][19][20][21][22][23][24],the mechanism at the molecular level [8,[25][26][27][28][29][30][31][32][33][34], the mechanism at the tissue level [35][36][37] ,and the physical mechanism respectively Binhi [37]; Binhi and Prato [38]; Binhi and Prato [39]. Binhi and Prato [38] proposed one universal physical mechanism of biological effects on the side of magnetic moment under the action of the HMF, but the mechanism can't give the possible molecules related to biological effects. ...
... Binhi and Prato [38] proposed one universal physical mechanism of biological effects on the side of magnetic moment under the action of the HMF, but the mechanism can't give the possible molecules related to biological effects. Barnes and Greenebaum [26] suggested the radical pair mechanism of biological effects under the action of weak magnetic fields, but the intensity of the fields is about 45uT which is much bigger than a HMF. Ouyang and Li [3] gave the point [3] that the change of singlet yield in a radical pair may be one quantum mechanism of biological effects on a HMF, but it is only a simple viewpoint. ...
The biological effects due to a hypomagnetic field (HMF) is a very important subject not only for aerospace traveling and space station living but also for some magnetic shielding conditions on the ground just like the underground bunkers and etc. However, to my knowledge, the mechanisms which can be related to the biological effects of a HMF remain unclear. In this study, I firstly summary one radical pair mechanism of biological effects on a HMF based on present researches, and then propose how to prove the radical pair mechanism’s truth in biological effects on a HMF through experiments. In the way of how to prove the radical pair mechanism’s truth I give the relation between the singlet yield of the radical pair and the angle describing the orientation of a HMF to the basis of the hyperfine tensor related to the electron spin and the nuclei spin is the possible one radical pair mechanism on one hand, and give the crucial method which is through that angle changed causes the biological effects in vivo or vitro to prove or disprove the mechanism on the other hand, because the biological effects of a HMF can be related with that angle, which is very easy to be controlled in experiments.
... Physical mechanisms of biological LF MF interaction, such as ion cyclotron resonance [5], ion parametric resonance [6], or radical pair mechanism were proposed [7]. Their experimental verification is still largely absent, due to the fact, that most experimental studies focus only on a small set of frequencies. ...
... Composition of the experimental platform: Pair of cultivation chambers with proportional-integralderivative (PID) temperature regulators (1), Helmholtz coils (2), signal generator(3), power amplifier (4), impedance spectroscopy analyzer (5), inverted light microscope(6), and central computer(7). ...
... Barnes and Greenebaum [3] outlined a model by which changes in radical concentrations may result from exposures to LF MF, noting that these changes can lead to biologically significant changes in metabolic rates and other processes. Transitions that alter the populations of the combined electron and nuclear states, can take place at frequencies that correspond to the energy separation between the various states in the external magnetic fields, especially at low external field intensities. ...
... Three different volumes of inoculum are used. For the first set of Petri dishes (1)(2)(3)(4)(5), the inoculum is not spread on YPD agar. For another set of Petri dishes (6-20), the inoculum was spread with laboratory spoon. ...
... In the majority of publications, exhibiting magnetic effects on the gene chemistry [36][37][38][39][40][41][42][43][44][45][46], it is recognized that the sources of the effects remain enig- ...
... Electromagnetic fields of low frequencies 7.83 and 60 Hz were shown to inhibit B16F10 cancer cells [55]; exposed to sweep frequencies for 24 hours these cells were inhibited by 17-26% compared with those of the control group. There are many other similar observations cited in references [36][37][38][39][40][41][42][43][44][45][46]. ...
... The state of current knowledge suggests that, while acute exposure to RF and microwaves within regulatory safety limits may not pose immediate threats, the cumulative effects of prolonged exposure in space conditions could exacerbate underlying biological stresses, such as mitochondrial dysfunction or oxidative stress. 121,122 Understanding the molecular mechanisms, particularly how RF and microwave radiation (both its electric and magnetic field components) interact with cellular components like membranes, proteins, and DNA, is crucial. Space missions introduce variables such as altered electromagnetic fields and increased exposure to different radiation spectra, making it imperative to deepen our understanding of how these factors influence astronaut health over time. ...
Keeping people healthy in space is going to be very important, especially on long trips to Mars. Unfortunately, evidence is suggesting that even in low earth orbit (LEO), within the protective effects of the magnetosphere, astronauts are displaying many markers of accelerated ageing, including mitochondrial dysfunction. Beyond LEO the problem could be much worse, which presents a big challenge. In this report, we summarise and approach the problem from a holistic aspect, and include some ideas that arise from viewing health from the quantum biological perspective, which raises the possibility that even the reduced strength of the magnetic field beyond the Earth's magnetosphere could be having a direct effect. All the data to date is suggesting that a great deal more research is required to fully understand both the short and long term impacts of space travel on life, and for complex organisms, such as humans, how the emerging pathological effects can be mitigated.
... At the molecular level, several theories describing the biological effects of an extremely low-frequency magnetic field (ELF MF) have already been proposed, among which the theory about reactive oxygen species (ROS) and free radical pairs [20][21][22][23] is one of the most popular explanations of ELF MF nonthermal effects, postulating that it is the increase in the amount of ROS that causes various pathological processes and diseases in the body. Current extensive research and growing evidence [23][24][25][26][27][28][29] from observed biological effects on various cell lines helps strengthen the reliability of the radical pairs mechanism affecting the ROS, despite the fact that detailed and exact physical description is still an object of investigation. ...
The increasing evidence regarding biological effects of exposure to an extremely low frequency magnetic field is of utmost interest not only to the scientific community, but also to legislative bodies and the public. However, the research in this field is full of controversial and inconsistent results, originated from a lack of widely acceptable physical mechanisms that could sufficiently describe the principle of such a field’s action. This experimental study addresses and points to possible sources of ambiguities via investigation of the ion parametric resonance mechanism at 50 Hz frequency. The chosen methodology incorporates exposure of the Saccharomyces cerevisiae yeast strain based on an established exposure protocol with special attention to the measurement of an applied time-varying magnetic field corresponding to the ion parametric resonance requirements. Subsequently, the differences in cell growth as a reaction to changes in magnetic flux density are evaluated and statistically analyzed. It is found that fluctuations in the magnetic field within the exposure setup need to be addressed properly, since this could have an impact on replication of the experiments and reliability of the results. Furthermore, comparison of two independently performed sets of 10 experiments showed statistically significant effects even in conditions that did not fulfill the requirements of the resonance theory, putting the validity and practical application of the ion parametric resonance model into question.
... The calculated Zeeman energies highlight the potential for RF fields to influence radical pairs by inducing transitions at specific frequencies. For example, the transition frequencies for electron spin states in the Earth's magnetic field (~45 µT) typically fall between 1 and 10 MHz [70]. These transitions can alter the recombination rates of radical pairs, affecting the production of ROS and the activities of antioxidant enzymes. ...
This study explores the complex relationship between radio frequency (RF) exposure and cancer cells, focusing on the HT-1080 human fibrosarcoma cell line. We investigated the modulation of reactive oxygen species (ROS) and key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase, and glutathione (GSH), as well as mitochondrial superoxide levels and cell viability. Exposure to RF fields in the 2–5 MHz range at very weak intensities (20 nT) over 4 days resulted in distinct, frequency-specific cellular effects. Significant increases in SOD and GSH levels were observed at 4 and 4.5 MHz, accompanied by reduced mitochondrial superoxide levels and enhanced cell viability, suggesting improved mitochondrial function. In contrast, lower frequencies like 2.5 MHz induced oxidative stress, evidenced by GSH depletion and increased mitochondrial superoxide levels. The findings demonstrate that cancer cells exhibit frequency-specific sensitivity to RF fields even at intensities significantly below current safety standards, highlighting the need to reassess exposure limits. Additionally, our analysis of the radical pair mechanism (RPM) offers deeper insight into RF-induced cellular responses. The modulation of ROS and antioxidant enzyme activities is significant for cancer treatment and has broader implications for age-related diseases, where oxidative stress is a central factor in cellular degeneration. The findings propose that RF fields may serve as a therapeutic tool to selectively modulate oxidative stress and mitochondrial function in cancer cells, with antioxidants playing a key role in mitigating potential adverse effects.
... A radical pair mechanism (RPM) (see Sec. 1 of the supplementary material) has been proposed to explain the impact of WMFs on modulation of ROS levels with some preliminary results. 5,6 The RPM is a leading theory for explaining the influence of WMFs in biological systems, 7-10 including avian magnetoreception. [11][12][13][14][15] A few recent works suggest that chirality-induced spin selectivity (CISS) might work alongside the RPM in avian magnetoreception. ...
Planaria serve as an intriguing model system wherein the effects of electric and magnetic fields on various biochemical pathways during cell morphogenesis can be studied. Recent experimental observations have demonstrated the non-trivial modulation of reactive oxygen species (ROS) levels by a weak magnetic field (WMF) during planaria regeneration. However, the underlying biophysical mechanism behind this remains elusive. In this work, we investigate the role of the radical pair mechanism (RPM) and attempt to explain the experimental results of the effect of WMFs on ROS modulation during planaria regeneration. We also propose that instead of the flavin adenine dinucleotide-superoxide radical pair (FADH•−O2•−), a non-superoxide-based flavin adenine dinucleotide-tryptophan radical pair (FAD•−−TrpH•+) might be a more suitable radical pair (RP) candidate for the observed ROS modulation. We also investigate the role of chirality-induced spin selectivity on ROS levels by including it in the framework of the RPM. We conclude that the singlet initiated FAD•−−TrpH•+ is a more realistic choice of RP, and hence, superoxide formation might happen later and not during the RP spin dynamics.
... TMR is based on the exposition of PEMFs, which work at molecular, cellular, and tissue level. At molecular level, there are effects on ionic particles, molecules, macromolecules, intracellular concentration of calcium ions and free radicals [9,[20][21][22][23], epigenetic modifications of the transcription process of DNA [24][25][26], and at mitochondrial level, effects on the electron transport chain [27]. At cellular level, there are effects on microcrystals, membranes, and cellular organelles, as the upregulation of ion channels [28], the modulation of apoptosis [29][30][31], and the expression of adenosine receptors A2A and A3 [32][33][34]. ...
Purpose
The aim of our study was to assess the possible benefits of Therapeutic Magnetic Resonance (TMR) in the treatment of spontaneous perineal lacerations and episiotomies in the postpartum.
Methods
We performed a prospective, non-pharmacologic, non-profit, monocentric interventional study on women who had a spontaneous laceration and/or an episiotomy at delivery. The TMR device treatment was accepted by 52 women, while 120 women underwent standard care. Patients were visited 1 day postpartum, before starting the treatment; then a follow-up visit was performed at 3 weeks, 5 weeks, and 3 months after delivery. The main endpoint was the time required for complete healing of the laceration and/or the episiotomy. Secondary endpoints were the prevalence of dehiscence, infections, urinary discomfort, urinary leakage, and the quality of restoration of sexual function.
Results
In the treatment group the REEDA score was significantly better both at 3- and 5-weeks postpartum follow-up. At 3 weeks and 5 weeks postpartum, we observed a significantly better outcome in the treatment group for all subjective complaints and perineal complications associated with lacerations and episiotomies. The percentage of patients who scored above the cutoff for sexual dysfunction was significantly better in the treatment group (83.3%) than in the control group (31.8%) (p < 0.001).
Conclusions
With this pilot study, we introduced low dose Pulsating Electromagnetic Fields (PEMFs) as a novel conservative and not pharmacological approach to reduce complications of perineal lesions. Our results demonstrated to significantly improve perineal wound healing and to ameliorate the sexual function in the postpartum.
... So far, the level of statistical significance used in the analysis of experimental data has been considered to support the occurrence of significant cellular effects, but no optimal underlying mechanism is available to explain statistical significance. Some of the proposed mechanisms cite transient radical pairs and triplet phenomena [154][155][156] or resonant effects [10,[145][146][147][148][149][150][151][152]. The main theory of the mechanisms of action was based on the induction of electric fields and currents in biological tissues, but many of these phenomena require much lower energy levels at which the occurrence of these effects is limited, which could be explained by the existence of non-linear states. ...
Since the establishment of regulations for exposure to extremely low-frequency (0–300) Hz electromagnetic fields, scientific opinion has prioritised the hypothesis that the most important parameter determining cellular behaviour has been intensity, ignoring the other exposure parameters (frequency, time, mode, waveform). This has been reflected in the methodologies of the in vitro articles published and the reviews in which they are included. A scope review was carried out, grouping a total of 79 articles that met the proposed inclusion criteria and studying the effects of the different experiments on viability, proliferation, apoptosis, oxidative stress and the cell cycle. These results have been divided and classified by frequency, intensity, exposure time and exposure mode (continuous/intermittent). The results obtained for each of the processes according to the exposure parameter used are shown graphically to highlight the importance of a good methodology in experimental development and the search for mechanisms of action that explain the experimental results, considering not only the criterion of intensity. The consequence of this is a more than necessary revision of current exposure protection regulations for the general population based on the reductionist criterion of intensity.
... Therapeutic Magnetic Resonance (TMR) is based on the exposition of low intensity Pulsating Electromagnetic Fields (PEMFs), which work at molecular, cellular, and tissue level. At molecular level, there are effects on ionic particles, molecules, macromolecules, intracellular concentration of calcium ions and free radicals (9,(20)(21)(22)(23) epigenetic modi cations of the transcription process of DNA (24)(25)(26), and at mitochondrial level, effects on the electron transport chain (27). At cellular level, there are effects on microcrystals, membranes, and cellular organelles, as the upregulation of ion channels (28), the modulation of apoptosis (29)(30)(31), and the expression of adenosine receptors A2A and A3 (32)(33)(34). ...
Background
In the last years, there has been a growing interest in non-invasive biophysical treatments to support surgical healing techniques beyond pharmacological therapies. Among these, the Pulsating Electromagnetic Fields (PEMFs), and in particular the Therapeutic Magnetic Resonance (TMR), had been studied in orthopedics with promising results. The aim of our study was to assess the possible benefits of this technology in the treatment of spontaneous perineal lacerations and episiotomies in the postpartum.
Methods
We performed a prospective, non-pharmacologic, non-profit, monocentric interventional study on women who delivered and were admitted to our postpartum ward with a spontaneous laceration and/or an episiotomy at delivery. 172 women were eligible for this study. 52 women accepted to undergo treatment with TMR device, while 120 women underwent standard care and were followed-up according to the same protocol. Patients were visited one day post-partum, before starting the treatment; then a follow-up visit was performed at three weeks (time 1), five weeks (time 2), and three months (time 3) after delivery. The main endpoint was the time required for complete healing of the laceration and/or the episiotomy. Secondary endpoints were the prevalence of dehiscence, infections, urinary discomfort, urinary leakage, and the quality of restoration of sexual function.
Results
The REEDA score, used to assess the progression of wound healing, was significantly better both at three- and five-weeks postpartum follow-up. At three weeks and five weeks postpartum, we observed a significantly better outcome in the treatment group for all subjective complaints and perineal complications associated with lacerations and episiotomies. The percentage of patients who scored above the cutoff for sexual dysfunction (26, 5) was significantly better in the treatment group (83%) than in the control group (29%) (p < 0,001).
Conclusions
With this pilot study, we introduced low dose Pulsating Electromagnetic Fields (PEMFs) as a novel conservative and not pharmacological approach to reduce complications of perineal lesions. This technology is compatible with breastfeeding, easy to use and therefore well accepted by women. Our results demonstrated to significantly improve perineal wound healing and to ameliorate the sexual function in the post-partum.
... The most important possible biophysical mechanism involved in magnetic field modifying effects on biological responses to UV radiation and other oxidizing agents is the "radical-pair mechanism" (Barnes and Greenebaum 2015). Based on this mechanism, the low (below approximately 1 mT) and high field magnetic field can affect specific types of chemical reactions, which involve pair of radical molecules, by generally increasing or decreasing the concentration of free radicals in low and high fields, respectively. ...
All organisms, including humans, emit ultraweak luminescence (10–1000 photons∙s−1∙cm−2 in the wavelength range of at least 350–1270 nm). These photons can be detected by very sensitive photomultiplier tubes or charge-coupled device imaging detectors. Biological autoluminescence (BAL) is an endogenously generated light and does not depend on external excitation by chemical means or light irradiation. It is widely accepted that BAL originates from electron-excited states, which are produced during oxidation reactions of biomolecules in living cells, i.e., it is related to the formation of reactive oxygen species (ROS). Because oxidative metabolism, as the main generating source of ROS, continues throughout the life of a living organism, it is possible to identify the health or disease status of a living system by analyzing the properties of these photons. Although BAL signals might contain valuable information about the physiological environment of a living cell, the detection of their ultraweak signal is a challenge for future in vivo diagnostic applications. Therefore, the development of appropriate strategies for enhancement of the BAL signal is necessary. Here, we review novel biophysical approaches for enhancement of BAL.
... For example, if you push a swing at the top, you increase the amplitude and if you push at the bottom in the same direction, you decrease it. [25] Therefore, the timing of an electromagnetic pulse concerning oscillating biological processes can lead to either positive or negative effects. Two or ...
Living organisms of Saccharomyces cerevisiae are subjected to extremely low-frequency electromagnetic field exposition during the workweek, followed by cultivation over the weekend. Initially, the weight of the inoculum with YPD agar is examined in the exposure setup without exposition between the first and the last day. Subsequently, the coil is supplied, generating a static and time-varying electromagnetic field. The theoretical assumption underlying this experiment is based on the modified ion parametric resonance theory, which specifically focuses on calcium ions at a frequency of 192.26 Hz. The time-varying magnetic field amplitude is set at 451.66 μT, accompanied by a static field of 250.92 μT. By employing an experimental protocol, the cells are exposed to these conditions for a long-term exposition within Petri dishes.
... Khususnya, kita harus mempertimbangkan interaksi magnetik antara momen magnetik spin elektron dan medan magnetik yang berasal dari orbit elektron. Medan magnetik ini terjadi Aproksimasi Central Field dan Teori Gangguan pada Atom akibat gerak elektron dalam medan listrik inti dan elektron-elektron lainnya (Barnes & Greenebaum, 2015). Energi yang terkait dengan interaksi spin-orbit ini dijelaskan oleh gangguan 2 H . Muncul pertanyaan: gangguan mana yang lebih signifikan, 1 H atau 2 H ? Seseorang mungkin tergoda untuk mengasumsikan bahwa 12Ĥ H karena gaya elektrostatik biasanya lebih kuat daripada gaya magnetik. ...
Dengan rasa syukur dan hormat yang mendalam, kami memulai pengantar ini dengan ungkapan puji dan terima kasih kepada Tuhan Yang Maha Esa atas anugerah-Nya yang tak terhingga. Melalui berkat rahmat-Nya, buku ini, yang berjudul "Spektroskopi dan Struktur Atom: Teori dan Aplikasi," kini hadir di hadapan Anda, melengkapi perjalanan ilmiah kami yang penuh dedikasi. Karya ini merambah kedalaman spektroskopi dan struktur atom, membongkar dasar-dasar pengetahuan yang membentuk pandangan kita terhadap mikrokosmos atomik.
Di era yang terus maju ini, pemahaman tentang struktur dan karakteristik atom menjadi landasan yang tak tergantikan, sementara spektroskopi memainkan peran utama dalam membuka pintu wawasan mendalam terhadap makna yang tersembunyi dalam radiasi atom. Kami mengajak Anda dalam perjalanan ilmiah yang bermakna, membekali Anda dengan perangkat dan metode spektroskopi secara cermat dan terperinci. Mulai dari konsep dasar hingga kompleksitas atom multielektron, kami menyajikan gagasan-gagasan yang menggugah pikiran Anda. Eksplorasi lebih mendalam tentang efek spin-orbit, interaksi nuklir, dan fenomena spektroskopi modern seperti sinar-X dan laser resolusi tinggi menjadi bagian tak terpisahkan dari pencerahan ini.
Kami juga ingin mengucapkan penghargaan tertinggi kepada mereka yang telah ikut serta dalam perjalanan ini. Para ilmuwan, peneliti, dan praktisi yang telah berbagi wawasan dan pengetahuan berharga, serta penerbit yang telah membantu mewujudkan buku ini, semuanya merupakan pilar yang membangun fondasi buku ini. Kami berharap dengan tulus bahwa buku ini akan memberikan manfaat nyata bagi Anda, para mahasiswa, peneliti, dan para profesional di bidang ilmu fisika, kimia, serta disiplin ilmu terkait. Semoga buku ini mendorong pertumbuhan dan perkembangan ilmu pengetahuan, menerangi jalan bagi kemajuan teknologi, serta meningkatkan pemahaman kita tentang alam semesta.
Dengan rendah hati, kami berharap bahwa buku ini tidak hanya menjadi sumber pengetahuan berharga, tetapi juga menjadi pemicu semangat eksplorasi dan pengembangan lebih lanjut di bidang spektroskopi dan struktur atom. Kami mengucapkan terima kasih atas perhatian dan dukungan tak ternilai dari Anda.
... SMFs (≥100 µT) enhance the reactive oxygen species (ROS) levels (Calabrò et al., 2013;Vergallo et al., 2014;Zablotskii et al., 2014;Wang and Zhang, 2017); however, the mechanism by which magnetic field exposure modulates ROS concentration in the cells still remains unclear. Weak magnetic fields can change free-radical reactions and concentrations in biological systems and influence specific cellular functions (Barnes and Greenebaum, 2015;Montoya, 2017). The presented results show that SMF (0.5-2.0 T) could intensify a generation of reactive oxygen species with disturbances of LP processes (i.e., secondary products of LP) in erythrocytes from healthy subjects. ...
Introduction: The current understanding of the biological impacts of a static magnetic field (SMF) is restricted to the direct interactions of the magnetic field with biological membranes. The electrokinetic (zeta) potential is an electrochemical property of erythrocyte surfaces which was negatively charged in physiological media after SMF exposure (0.1‒2.0 T).
Methods: The novel data about electrokinetic parameters of the erythrocytes is determined by microelectrophoresis after SMF-exposure in norm and heterozygous β-thalassemia. The methods of light scattering, lipid peroxidation, fluorescence microscopy are used.
Results: The electrokinetic potential of erythrocytes in norm is increased after SMF intensities due to enhanced negatively exposed charges on the outer surface of the membrane accompanied by an increase in light scattering where changes in cell morphology are observed. Conversely, a decrease in the zeta potential of β-thalassemia erythrocytes upon SMF-treatment was determined because of the reduction in the surface electrical charge of the membranes, where a significant decrease in light scattering at 1.5 T and 2.0 T was recorded. Exposure to SMF (0.5–2.0 T) was associated with an increase in the malondialdehyde content in erythrocytes. Biophysical studies regarding the influence of SMF on the electrostatic free energy of cells shows an increase in negative values in healthy erythrocytes, which corresponds to the implementation of a spontaneous process. This is also the process in β-thalassemia cells after SMF exposure with lower negative values of free electrostatic energy than erythrocytes in norm.
Discussion: The effect of static magnetic field (SMF 0.1–2.0 T) on the electrokinetic and morphological characteristics of erythrocytes in norm and β-thalassemia is determined and correlated with the increase/reduction in surface charge and shrinkage/swelling of the cells, respectively. Lipid peroxidation of healthy and β-thalassemia erythrocytes caused an enhancement of lipid peroxidation because of the higher concentrations of TBARS products in cellular suspension. SMF (0.1‒2.0 T) altered the spontaneous chemical processes with negative values of electrostatic free energy of erythrocytes in norm and β-thalassemia accompanied by a lower FITC-Concanavalin A binding affinity to membrane receptors (SMF 2.0 T). The electrokinetic properties of human erythrocytes in norm and β-thalassemia upon SMF treatment and their interrelationship with the structural-functional state of the membrane were reported. The presented work would have future fundamental applications in biomedicine.
... That is corresponding to the medium, where the cells are basically seeded at the start of the experiment. To investigate how extremely low-frequency electromagnetic field can impact biological organisms, for better understanding of the theories [8,9,10], the numerical simulations help to observe the uniformity and homogeneity of B-field. For numerical simulations, the CST Studio Suite tool (Computer Aided Technology, USA) was used. ...
This article presents numerical simulations focused on static magnetic fields, employing a Mu-metal cage for shielding against the geomagnetic field. The objective is to verify, how homogeneous and uniform magnetic field within the magnetic field applicator is created. Square Helmholtz coils are employed to ensure this homogeneity. Observations indicate a 5.3% deviation in the B-field when the coils are supplied with a DC current of 110 mA. In the absence of a DC field supply, a 12% deviation is observed. The impact of extremely low-frequency electromagnetic fields and static magnetic fields on living organisms is well-documented, emphasizing the significance of even small changes and deviations in the magnetic field. This underscores the importance of employing a Mu-metal cage when investigating the effects of these fields. Numerical simulations using specialized software demonstrate that the highly permeable Mu-metal box provides approximately 90% shielding efficiency against the geomagnetic field.
... Radical recombination rates can be influenced by an applied static magnetic field (SMF) via the electron Zeeman interaction 13 . An RF field in combination with static magnetic fields (SMFs) can change the product yields if it is in resonance with the energy-level splitting arising from the hyperfine and Zeeman interactions 14,15 . Mitochondrial network may function as a frequency-and amplitude-modulated signaling system and may be sensitive to physiological variables such as rates of generation and scavenging of ROS. ...
There are substantial concerns that extended exposures to weak radiofrequency (RF) fields can lead to adverse health effects. In this study, HT-1080 fibrosarcoma cells were simultaneously exposed to a static magnetic flux density between 10 μT and 300 μT and RF magnetic fields with amplitudes ranging from 1 nT to 1.5 μT in the frequency range from 1.8 to 7.2 MHz for four days. Cell growth rates, intracellular pH, hydrogen peroxide, peroxynitrite, membrane potential and mitochondrial calcium were measured. Results were dependent on carrier frequency and the magnitude of the RF magnetic field, modulation frequencies and the background static magnetic field (SMF). Iron sulphur (Fe-S) clusters are essential for the generation of reactive oxygen species and reactive nitrogen species (ROS and RNS). We believe the observed changes are associated with hyperfine couplings between the chemically active electrons and nuclear spins. Controlling external magnetic fields may have important clinical implications on aging, cancer, arthritis, and Alzheimer’s.
... Выявленные экспериментальные зависимости эффектов ПеМП от частоты не исключают возможность реализации эффектов резонансной природы, теоретические подходы к которым разрабатываются уже в течение длительного времени [66] , и, несмотря на явный прогресс [67,68,69,70] все еще далеки от полного понимания. До сих пор не ясно, в какой степени к анализу этих эффектов может быть применим широко обсуждаемый механизм радикальных пар [71,72] , а также другие общефизические механизмы [73] . В таблицах 2 и 3 суммированы биологические эффекты слабых переменных и комбинированных магнитных полей и влияние на эти эффекты различных химических ингибиторов. ...
В статье рассмотрены основные за последние годы достижения в области исследования биологических эффектов слабых и сверхслабых низкочастотных переменных и комбинированных магнитных полей в отношении таких объектов как нейтрофильные гранулоциты (активируемые химическими стимуляторами или интактные) при воздействии на изолированные клетки, кровь и целые организмы. Методики включают в себя регистрацию изменения уровней концентраций АФК (наиболее заметный эффект воздействия слабого магнитного поля), индекса прайминга, гомеостаза кальция, пролиферативной активности, иммунного статуса, а также влияния на эти показатели различных химических агентов. Ведущими методами в этой области являются флуоресцентная спектрометрия и хемилюминесцентный анализ. Результаты экспериментов свидетельствуют о биологической эффективности данного физического фактора, конкретный эффект которого зависит от типа биосистемы, её функционального статуса, окружающей среды и параметров самих полей. Полученные данные могут иметь как прикладное значение (магнитотерапия, оптимизация иммунного ответа при различных заболеваниях, ускорение процессов регенерации и восстановления тканей, повышение сопротивляемости организма при инфекциях), так и академическое (выявление первичных акцепторов поля и магнитных мишеней, их локализации в клетке, взаимосвязи с сигнальными каскадами и построение моделей путей амплификации биологического сигнала, выявление биологически значимых частот и амплитуд полей).
Правильная ссылка на статью: Шаев И.А., Новиков В.В. — Влияние слабых переменных магнитных полей на нейтрофильные гранулоциты. Аналитический обзор // Физика биологии и медицины. – 2023. – № 1. – С. 26 - 43. DOI: 10.7256/2730-0560.2023.1.40410 EDN: CXPBMJ URL: https://nbpublish.com/library_read_article.php?id=40410
... The issue of what molecular mechanisms underlie the biological effects of EMFs is still an open question [50][51][52]. One hypothesis is that EMFs induce changes in the energy levels of certain molecules affecting the concentration of free radicals, such as reactive oxygen species (ROS) [53,54]. Several studies documented the ability of RF-EMF to induce an increased production of ROS [55][56][57][58][59][60][61] and similar results have been reported for ELF-MF [62][63][64][65]. ...
A large body of evidence indicates that environmental agents can induce alterations in DNA methylation (DNAm) profiles. Radiofrequency electromagnetic fields (RF-EMFs) are radiations emitted by everyday devices which have been classified as “possibly carcinogenic”, however their biological effects are unclear. As aberrant DNAm of genomic repetitive elements (RE) may promote genomic instability, here we sought to determine whether exposure to RF-EMFs could affect DNAm of different classes of RE, such as long interspersed nuclear element1s (LINE-1), Alu short interspersed nuclear element and ribosomal repeats. To this purpose, we analysed DNAm profiles of cervical cancer and neuroblastoma cell lines (HeLa, BE(2)C and SH-SY5Y) exposed to 900 MHz GSM-modulated RF-EMF through an Illumina-based targeted deep bisulfite sequencing approach. Our findings showed that radiofrequency exposure did not affect DNAm of Alu elements in any of the cell lines analysed. Conversely, it influenced DNAm of LINE1 and ribosomal repeats in terms of both average profiles and organization of methylated and un-methylated CpG sites, in different ways in each of the three cell lines studied.
... MF can act in the production of triplet states in electrons, dissociating them in the form of free radicals in cells, and thus, leading to oxidative stress in biological systems [11,12]. Factors, such as exposure time and MF intensity seem to influence this dissociation in a non-linear manner and trigger oxidative stress. ...
The application of magnetic fields (MF) has attracted the attention of researchers due to their efficiency to change cell metabolism. Chlamydomonas reinhardtii is a biotechnologically useful microalga with versatile metabolism that may be a valuable organism to study the effects of the MF in biology. Therefore, two C. reinhardtii strains, one with cell wall (2137) and other which lacks the cell wall (Wt-S1-cc4694), were evaluated that a new sensitivity factor in the analysis could be included. Comparative studies were undertaken with the two C. reinhardtii strains under the MF intensities of 0.005 mT (terrestrial MF - control), 11 and 20 mT. Results indicated that the physical cell wall barrier protected cells against the MF applied during the assays. Only with the highest MF applied (20 mT) a slight increase in lipid concentration in the cell wall strain was detected. The lowest growth of the strain that lacks cell wall (Wt-S1) indicated that these cells are under a negative effect. To cope with the two MF stresses conditions, Wt-S1 cells produced more pigments (chlorophylls and carotenoids) and lipids and enhanced the antioxidant defense system. The raise of these compounds under MF could potentially have a positive biotechnological impact on algal biomass.
... Still, in some studies, there is a description of a threshold around 10 −4 V·m −1 for an external EF intensity to elicit a biological reaction at the cellular level [15]. At the cellular and subcellular levels, there are already several theories published describing the effects of weak LF MF, i.e., on proteins located on the surface of the cell membrane responsible for ion channels opening/closing: the ion cyclotron resonance (ICR) theory [16]; the ion parametric resonance (IPR) mechanism [17,18]; the theory about reactive oxygen species and free radical pairs [19,20]. The mentioned physical models are almost exclusively focused on the nonthermal effects of LF MF. ...
This article is focused on the in vitro experimental verification of the basic necessary conditions for valid interpretation of an ion parametric resonance prediction model of biological reaction on an externally applied, extremely low-frequency magnetic field. Experiments are performed on model organism Saccharomyces cerevisiae strain BY4741, with the intention to target calcium ions, which already produced interesting preliminary results within authors’ previous works, confirming specific magnetic field settings being bioactive. To study the nature and origin of biological reactions more exhaustingly, the research is aimed at two chosen physical aspects of ion parametric resonance theory. In the first part, experiments are set up to verify the resonance point validity for calcium ions and to perform a sensitivity analysis of the biological system response around this point. In the second part, the main attention is paid to the verification of the validity of maximum biological effect at specific BAC/BDC ratios, reflecting the ion parametric resonance theory as well as the current state of the art and knowledge. Both series of experiments have shown interesting results, confirming 29.89 Hz as a bioactive frequency for a BAC/BDC ratio of 1.8. These observations are in close correlation with the assumptions of the ion parametric resonance model for targeting calcium ions. The performed sensitivity analysis around the resonance point looks even more interesting, as conducted preliminary experiments resulted in two more pronounced bioactive frequencies of 24.89 and 34.89 Hz, in terms of biological response significance, than the resonance frequency assumed by an investigated prediction model. The narrow width of the peak, which is typical for physical phenomena of resonant nature, was not observed within this series of experiments, which would be addressed more precisely in future work of authors.
... In recent studies, it is also suggested that radical pairs may explain hypomagnetic field effects on hippocampal neurogenesis [36] and microtubule reorganization [37]. The LFEs on radical pair reactions have been extensively studied experimentally and theoretically [38][39][40][41][42][43]. Here, based on the radical pair mechanism, we show that changing the magnetic field experienced by a biological system from the geomagnetic field to near zero can, under certain conditions, lead to stronger effects than changing it from the geomagnetic field to a much stronger field ( Figure 2). ...
Near-zero magnetic fields, called hypomagnetic fields, are known to impact biological phenomena, including developmental processes, the circadian system, neuronal and brain activities, DNA methylation, calcium balance in cells, and many more. However, the exact mechanism underlying such effects is still elusive, as the corresponding energies are far smaller than thermal energies. It is known that chemical reactions involving radical pairs can be magnetic field dependent at very low intensities comparable to or less than the geomagnetic field. Here, we review in detail hypomagnetic field effects from the perspective of the radical pair mechanism, pointing out that under certain conditions, they can be comparable or even stronger than the effects of increasing the magnetic field. We suggest that hypomagnetic field effects are an interesting avenue for testing the radical pair mechanism in biology.
... A predominant theory for understanding the biological effects of WMF exposures centers on the radical pair mechanism, which has been reviewed in detail [25][26][27][28][29][30]. Briefly, theoretical modeling ( Figure 1A) suggests that WMFs can modulate radical pairs through changes in the angular momentum of lone electrons (spin state theory). ...
Reactive oxygen species (ROS) signaling regulates cell behaviors and tissue growth in development, regeneration, and cancer. Commonly, ROS are modulated pharmacologically, which while effective comes with potential complications such as off-target effects and lack of drug tolerance. Thus, additional non-invasive therapeutic methods are necessary. Recent advances have highlighted the use of weak magnetic fields (WMFs, <1 mT) as one promising approach. We previously showed that 200 μT WMFs inhibit ROS formation and block planarian regeneration. However, WMF research in different model systems at various field strengths have produced a range of results that do not fit common dose response curves, making it unclear if WMF effects are predictable. Here, we test hypotheses based on spin state theory and the radical pair mechanism, which outlines how magnetic fields can alter the formation of radical pairs by changing electron spin states. This mechanism suggests that across a broad range of field strengths (0–900 μT) some WMF exposures should be able to inhibit while others promote ROS formation in a binary fashion. Our data reveal that WMFs can be used for directed manipulation of stem cell proliferation, differentiation, and tissue growth in predictable ways for both loss and gain of function during regenerative growth. Furthermore, we examine two of the most common ROS signaling effectors, hydrogen peroxide and superoxide, to begin the identification and elucidation of the specific molecular targets by which WMFs affect tissue growth. Together, our data reveal that the cellular effects of WMF exposure are highly dependent on ROS, and we identify superoxide as a specific ROS being modulated. Altogether, these data highlight the possibilities of using WMF exposures to control ROS signaling in vivo and represent an exciting new area of research.
... Обнаруженные на сегодня эффекты «нулевого» поля в отношении клеток и целых организмов носят как позитивный, так и негативный характер и демонстрируют широкий интервал биологических изменений, начиная от процессов эмбрионального развития [15][16][17] и морфогенеза [18][19][20][21][22] и заканчивая поведенческими реакциями [23,24], что говорит о важности такого свойства как биомагниторецепция практически на каждом этапе развития биологического организма. Исследования в этой области имеют также и биофизический аспект, заключающийся в поиске и установлении первичного механизма неспецифической рецепции слабых магнитных полей биосистемами [4,5,25,26]. В данной работе были получены результаты, которые могут послужить прологом к дальнейшим экспериментам, призванным пролить свет на природу как первичной «мишени» магнитного воздействия, так и последующих звеньев цепи ответных реакций клетки на магнитную стимуляцию. ...
. It was shown that incubation of a suspension of mouse peritoneal neutrophils for 30 minutes under hypomagnetic conditions obtained using permalloy magnetic screens (a constant magnetic field of not more than 20 nT, the level of variable man-made noise is reduced to a few nT) causes a significant decrease (about 48%) signal intensity of lucigenin-dependent chemiluminescence measured immediately after incubation. 20 minutes after magnetic treatment (followed by incubation in a geomagnetic field during this time, induction 44 μT, the level of magnetic interference at a frequency of 50 Hz was 15-50 nT), the differences between the control and experimental groups remain completely (the difference was about 49%). In 40 and 60 minutes after exposure to the "zero" field, followed by keeping the samples in the geomagnetic field for the specified time intervals, the difference between the control and experimental samples decreased to 32% and 22%, respectively. This effect was registered without additional activation of neutrophils by chemical agents initiating respiratory burst, such as N-formyl-Met-Leu-Phe formylated peptide or phorbol-12-meristat-13-acetate phorbol ester, and was not associated with effects on cellular systems, providing this explosion.
... Possible physical principles were reported e.g. Barnes andGreenebaum, 2014, Vistnes andGjotterud (2001) and Peleg (2012). ...
Introduction:
In 2018, we reported a case series of 47 patients diagnosed with cancer following several years of exposure to high-intensity whole-body radiofrequency radiation (RFR) using the parameter of percentage frequency (PF). Consistent high and statistically significant PFs of hematolymphoid (HL) cancers were found in this group and in four previous reports on RFR-exposed groups in Belgium, Poland and Israel together with increased all-cancers rates. In this paper we report a new series of 46 young cancer patients who were exposed during military service to such radiation.
Materials and methods:
The new group of patients comprises Israeli soldiers previously exposed to occupational RFR. The patients were self-selected to enroll in the research in cooperation with an NGO assisting patients with administrative counseling and legal and social services. The new group of patients was studied with respect to distribution (proportion) of cancer types using the method of PF. When possible, cancer risk ratios (RR) were estimated too. The results are compared to those of other occupational groups in three countries.
Results:
Median age at diagnosis was 23 years; duration of exposure was between 1-3 years and the latencies were short, median 4.6 years. The PF of HL cancers was 41.3%, 95% CI (27% - 57%), versus 22.7% expected in non-exposed subjects matched for age and gender profiles, p=0.003; 19 out of the 46 patients had HL cancers. The PF of Hodgkin lymphoma cancers was 21.7%, 95%CI (11% - 36%), versus 11.6% expected, p=0.033. For a subgroup of 6 patients, the number of soldiers in the units was known, and we were able estimate approximately the overall cancer risk ratio (RR) after 8 years as being 8.0 with 95% CI (2.9, 17), p<0.002, with only 0.75 cases expected from the Cancer Registry data. In this subgroup, there were 3 HL cancer cases and 3 non-HL cases. Sarcoma PF was higher than expected, 7 out of the 46 patients were diagnosed with sarcoma, PF=15.2%, 95%CI (6.3%- 28.9%), p=0.04 versus the expected PF of 7%.
Conclusion:
The HL PF was high and consistent with previous reports. Epidemiological studies on excess risk for HL and other cancers, brain tumors in cellphone users, and experimental studies on RFR and carcinogenicity strongly point to a cause-effect relationship. It is mandatory to reduce the RFR exposure of all personnel to that of the typical community levels, including the peak level of radar pulses. Radiation protection, safety instructions, cancer risk warnings and quantitative data on individual exposure together with regular medical monitoring must be instituted for all personnel exposed to such risks. The findings from our study add to the growing body of evidence underscoring the gross inadequacy of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) thermal standards. Based on our findings and on the previous accumulated research, we endorse the recommendations to reclassify RFR exposure as a human carcinogen, International Agency for Research on Cancer (IARC) group .
Keywords:
Radio-frequency radiation, non-ionizing radiation, radar, hematolymphoid cancers, hematopoietic malignancies, sarcoma
... Increased production of ROS in living cells may be caused by weak magnetic fields altering recombination rates of short-lived radical pairs generated by normal metabolic processes leading to changes in free radical concentrations [73], or by low intensity extremely low frequency (ELF) EMFs resulting in alterations in voltagegated ion channels in cell membranes causing changes in cation flow across membranes [74]. These mechanisms apply to both ELF-EMFs and to RFR modulated by pulsed fields at extremely low frequencies. ...
In the late-1990s, the FCC and ICNIRP adopted radiofrequency radiation (RFR) exposure limits to protect the public and workers from adverse effects of RFR. These limits were based on results from behavioral studies conducted in the 1980s involving 40–60-minute exposures in 5 monkeys and 8 rats, and then applying arbitrary safety factors to an apparent threshold specific absorption rate (SAR) of 4 W/kg. The limits were also based on two major assumptions: any biological effects were due to excessive tissue heating and no effects would occur below the putative threshold SAR, as well as twelve assumptions that were not specified by either the FCC or ICNIRP. In this paper, we show how the past 25 years of extensive research on RFR demonstrates that the assumptions underlying the FCC’s and ICNIRP’s exposure limits are invalid and continue to present a public health harm. Adverse effects observed at exposures below the assumed threshold SAR include non-thermal induction of reactive oxygen species, DNA damage, cardiomyopathy, carcinogenicity, sperm damage, and neurological effects, including electromagnetic hypersensitivity. Also, multiple human studies have found statistically significant associations between RFR exposure and increased brain and thyroid cancer risk. Yet, in 2020, and in light of the body of evidence reviewed in this article, the FCC and ICNIRP reaffirmed the same limits that were established in the 1990s. Consequently, these exposure limits, which are based on false suppositions, do not adequately protect workers, children, hypersensitive individuals, and the general population from short-term or long-term RFR exposures. Thus, urgently needed are health protective exposure limits for humans and the environment. These limits must be based on scientific evidence rather than on erroneous assumptions, especially given the increasing worldwide exposures of people and the environment to RFR, including novel forms of radiation from 5G telecommunications for which there are no adequate health effects studies.
... RF magnetic fields by more than 25% (18,30,31). Variation in the static magnetic fields can both increase and decrease the energy separation between triplet states of radicals and thus the frequency for transferring electrons or nuclei between energy levels that are actively involved in a chemical reaction (32). The long relaxation times for nuclear spins and the corresponding rapid variations in frequency responses can lead to changes in HT-1080 fibrosarcoma cell growth rates with variations in frequency as little as half a cycle per second at 16.5Hz for 4-day exposures to 9.8 µT in a static field of 45 µT (33). ...
Concerns about the possible health effects from exposure to weak electric and magnetic (EM) fields have been debated since the early 1960s. It is now well established that biological systems respond to exposure to weak EM fields at energy levels well below the current safety guidelines which result in modification of their functionality without significant changes in temperature. These observations are adding to the debate over what should be done to protect the users of cellular telecommunications systems. Experimental results showing both increases and decreases in cancer cell growth rates and concentration of reactive oxygen species for exposure to nano-Tesla magnetic fields at both radio frequencies (RF) and extra low frequencies (ELF) are cited in this paper. Some theoretical models on how variations in EM exposure can lead to different biological outcomes and how feedback and repair processes often mitigate potential health effects due to long-term exposure to low-level EM energy sources are presented. Of particular interest are the application of the radical pair mechanisms that affect polarization of electrons, and nuclear spins and the importance of time-delayed feedback loops and the timing of perturbations to oscillations in biological systems. These models help account for some of the apparently conflicting experimental results reported and suggest further investigation. These observations are discussed with particular emphasis on setting future safety guidelines for exposure to electromagnetic fields in cellular telecommunications systems. The papers cited are a very small fraction of those in the literature showing both biological effects and no effects from weak electric and magnetic fields.
... In recent studies, it is also suggested that radical pairs may explain hypomagnetic field effects on hippocampal neurogenesis 36 and microtubule reorganization 37 . The LFEs on radical pair reactions have been extensively studied experimentally and theoretically [38][39][40][41][42][43] . Here, based on the radical pair mechanism, we show that changing the magnetic field experienced by a biological system from the geomagnetic field to near zero can, under certain conditions, lead to stronger effects than changing it from the geomagnetic field to a much stronger field (Fig. 2). ...
Near-zero magnetic fields, called hypomagnetic fields, are known to impact biological phenomena, including developmental processes, the circadian system, neuronal and brain activities, DNA methylation, calcium balance in cells, and many more. However, the exact mechanism underlying such effects is still elusive, as the corresponding energies are far smaller than thermal energies. It is known that chemical reactions involving radical pairs can be magnetic field dependent at very low intensities comparable to or less than the geomagnetic field. Here, we review in detail hypomagnetic field effects from the perspective of the radical pair mechanism, pointing out that under certain conditions, they can be comparable or even stronger than the effects of increasing the magnetic field. We suggest that hypomagnetic field effects are an interesting avenue for testing the radical pair mechanism in biology.
... The effects of magnetic fields on the kinetics of radical pair recombination have a great potential to enhance the reactivity and generation of new free radicals (5,6). Furthermore, free radicals pair have energy levels of unpaired electron spins that are either singlet state (antiparallel) or triplet state (parallel). ...
Magnetic fields remotely influence cellular homeostasis as a physical agent through the changes in cell physicochemical reactions. Magnetic fields affect cell fate, which may provide an important and interesting challenge in stem cell behaviors. Here, we investigated the effects of the static magnetic field (SMF, 20 mT) and electromagnetic field (EMF, 20 mT–50 Hz) on reactive oxygen species (ROS) production and the acidic pH conditions as stimuli to change cell cycle progression and cell death in mesenchymal stem cells. Results show that SMF, EMF, and their simultaneous (SMF+EMF) administration increase ROS and expression of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2), and glutathione-S-transferase (GST) as an antioxidant defense system. Besides, intracellular pH (pHi) decreases in presence of either EMF or SMF+EMF, but not SMF. Decreased ROS content using ascorbic acid in these treatments leads to increased pH compared to the magnetic field treatments alone. Furthermore, each magnetic field has different effects on the cellular process of stem cells, including cell cycle, apoptosis and necrosis. Moreover, treatment by SMF enhances the cell viability after 24 h, while EMF or SMF+EMF decreases it. These observations indicate that fluctuations of ROS generation and acid enhancement during SMF and EMF treatments may reveal their beneficial and adverse effects on the molecular and cellular mechanisms involved in the growth, death, and differentiation of stem cells.
... It has already been found that EMF in the single-digit GHz range polarizes protein macromolecules in an aqueous solution [30,31]. Interest in the combined action of magnetic fields and radio frequency EMF on biological objects increased in connection with the study of the biological action of magnetic fields, taking into account the hyperfine interaction between nuclei and electrons in the implementation of the mechanism of radical pairs (in this case, frequencies in the range of 1-15 MHz can be active) [32,33]. It should be noted that the number of indoor sources of radio frequency EMF, including in laboratories, has increased significantly over the past two decades, as mobile phones, Wi-Fi, and other wireless technologies have become an integral part of our life. ...
We have previously shown that water incubated in a weak combined magnetic field (CMF) increased the production of reactive oxygen species (ROS) by neutrophils. Adding high dilutions (HD) of water into the same system resulted in a similar effect. HD of antibodies to interferon-gamma (HD Abs to IFNγ) were shown to emit electromagnetic radiation and affect hydrogen bond energies. Here, we aimed to evaluate the effect of HD of substances (donor) on the properties of aqueous solutions (acceptor). The donor and acceptor were incubated for 1 h in a controlled magnetic field so that the walls of the two cuvettes were in close contact. As a control, the acceptor was incubated under the same conditions but without the donor. An aliquot of the acceptor solution was then added to mouse neutrophils, and ROS levels were measured using luminol-dependent chemiluminescence assay. Joint incubation led to a 185–356% increase (p < 0.05) in ROS production, depending on the type of acceptor sample. The magnitude of the effect depended on the parameters of the magnetic field. In a CMF, the effect was strongest, completely disappearing in a magnetic vacuum or with shielding. These findings are important for understanding the physical mechanism of action of HD preparations, which opens up opportunities for expanding their practical applications.
... Different authors have discussed on how to theoretically assess MFs' characteristics to influence ROS concentration in biological systems. The radical pair mechanism (RPM) has offered a valid foundation to explain how MFs can influence biomedical ROS production (Adams et al. 2018; Barnes and Greenebaum 2015;Buchachenko 2016;Hore 2019;Hore and Mouritsen 2016;Tofani 2018;Zhang et al. 2015). ...
The potential therapeutic uses of electromagnetic fields (EMF), part of the nonionizing radiation spectrum, increase with time. Among them, those considering the potential antitumor effects exerted by the Magnetic Fields (MFs), part of the EMF entity, have gained more and more interest. A recent review on this subject reports the MFs' effect on apoptosis of tumor cells as one of the most important breakthroughs. Apoptosis is considered a key mechanism regulating the genetic stability of cells and as such is considered of fundamental importance in cancer initiation and development. According to an atomic/sub-atomic analysis, based on quantum physics, of the complexity of biological life and the role played by oxygen and its radicals in cancer biology, a possible biophysical mechanism is described. The mechanism considers the influence of MFs on apoptosis through an effect on electron spin that is able to increase reactive oxygen species (ROS) concentration. Impacting on the delicate balance between ROS production and ROS elimination in tumor cells is considered a promising cancer therapy, affecting different biological processes, such as apoptosis and metastasis. An analysis in the literature, which allows correlation between MFs exposure characteristics and their influence on apoptosis and ROS concentration, supports the validity of the mechanism.
... The mechanisms should rely on the quantum dynamics of magnetic moments under conditions of low thermal relaxation. These are the mechanisms of MF influence on abstract [40] and proton [44] magnetic moments, as well as on the electron spin (e.g., [23,24,45,46]) and orbital [22,47] magnetic moments. The objects of these mechanisms are, respectively, single moments, spin-correlated pairs of radicals, and quantum rotations of molecular groups within proteins. ...
This review contains information on the development of magnetic biology, one of the multidisciplinary areas of biophysics. The main historical facts are presented and the general observed properties of magnetobiological phenomena are listed. The unavoidable presence of nonspecific magnetobiological effects in the everyday life of a person and society is shown. Particular attention is paid to the formation of theoretical concepts in magnetobiology and the state of the art in this area of research. Some details are provided on the molecular mechanisms of the nonspecific action of a magnetic field on organisms. The prospects of magnetobiology for the near and distant future are discussed.
... It is expected that the data from yeast Saccharomyces cerevisiae could lead to novel insights on the biological effects of more complex eukaryotic organisms including humans. The obtained experimental data should be confronted with the existing physical models like "ion cyclotron resonance", "ion parametric resonance" [8], or "Radical pair mechanism" [9].There are several limitations of the current measurement methods which are used for monitoring and evaluation of biological MF effects. One of these limitations is the real-time monitoring of MF effects on living biological structures. ...
The goal of this contribution lies in the development of an innovative measurement approach for the investigation of magnetic field effects on biological structures. Satisfying explanations of the interactions between the magnetic field and biological systems are still lacking. Impedance spectroscopy is a well-established technique for concentration estimation in the field of cell culture growth rate. Here we present proof of the concept for impedance monitoring during cell cultivation with magnetic field exposure. Potential applications lie in the biomedicine and food industry.
Studies have shown that low magnetic fields (LMFs) of less than 1 x 10-3 Tesla (T) affect numerous biological events, including bacteria and plant growth, bird migration, and human brain activity. On a cellular level, LMFs affect ion channel activities, intracellular Ca2+ concentrations, and mitochondrial reactive oxygen species (mROS) generation. However, the mechanisms that could account for these effects are controversial. Here, we show that applying a static LMF, ranging from ~2.7 x 10-4 to ~1.9 x 10-3 T, to mitochondria isolated from adult rat hearts produced a bell-shaped increase in maximal respiration (Vmax) up to 40%. A similar LMF-induced increase in Vmax was also observed in mitochondria isolated from rat hearts subjected to ischemia-reperfusion (I-R) injury. We then obtained data showing that LMF-mediated bell-shaped response was also observed in the activity of several enzymes involved in oxidative phosphorylation (OXPHOS), including Complexes II, III, and V, and citrate synthase. By contrast, similar LMF caused little change in the enzymatic activity of Complex I. Interestingly, mROS generation responded to LMF with an inverted bell-shaped decrease. We propose a radical pair mechanism of magnetoreception in cytochromes, catalytical reactions, and iron-sulfur clusters within the OXPHOS enzymes to explain how an LMF can increase the likelihood of electron spin transitions from singlet to triplet state and reverse it as the magnetic field strength further increases, resulting in a bell-shaped response. Our results indicate that a narrow range of LMF can enhance mitochondrial bioenergetics and decrease mROS. This may provide a non-invasive approach to treating diseases, such as I-R injury, when energy generation is compromised and oxidative stress is magnified.
Even though the bioeffects of electromagnetic radiation (EMR) have been extensively investigated during the past several decades, our understandings of the bioeffects of EMR and the mechanisms of the interactions between the biological systems and the EMRs are still far from satisfactory. In this article, we introduce and summarize the consensus, controversy, limitations, and unsolved issues. The published works have investigated the EMR effects on different biological systems including humans, animals, cells, and biochemical reactions. Alternative methodologies also include dielectric spectroscopy, detection of bioelectromagnetic emissions, and theoretical predictions. In many studies, the thermal effects of the EMR are not properly controlled or considered. The frequency of the EMR investigated is limited to the commonly used bands, particularly the frequencies of the power line and the wireless communications; far fewer studies were performed for other EMR frequencies. In addition, the bioeffects of the complex EM environment were rarely discussed. In summary, our understanding of the bioeffects of the EMR is quite restrictive and further investigations are needed to answer the unsolved questions.
In the last few decades, evidence has surfaced that weak radiofrequency (RF) fields can influence biological systems. This work aims to improve our understanding of how externally applied weak RF fields alter concentrations of chemical parameters that characterize oxidative stress. We conducted a series of experiments to investigate the effects of applying weak RF magnetic fields within the 3–5 MHz region on mitochondrial respiration in both human fibrosarcoma and fibroblast cells over a period of four days. Our experimental data show that RF fields between 3 and 5 MHz were able to change the modulation of mitochondrial signaling by changing the cell growth, mitochondrial mass, and oxidative stress. Exposure to RF fields at 4.2 MHz significantly increased the mitochondrial mass and oxidative stress in fibrosarcoma cells. There are substantial concerns that extended exposure to weak RF fields can lead to health effects. The ability to control these parameters by external magnetic fields may have important clinical implications.
The gut microbiota has been considered one of the key factors in host health, which is influenced by many environmental factors. The geomagnetic field (GMF) represents one of the important environmental conditions for living organisms. Previous studies have shown that the elimination of GMF, the so-called hypomagnetic field (HMF), could affect the physiological functions and resistance to antibiotics of some microorganisms. However, whether long-term HMF exposure could alter the gut microbiota to some extent in mammals remains unclear. Here, we investigated the effects of long-term (8- and 12-week) HMF exposure on the gut microbiota in C57BL/6J mice. Our results clearly showed that 8-week HMF significantly affected the diversity and function of the mouse gut microbiota. Compared with the GMF group, the concentrations of short-chain fatty acids tended to decrease in the HMF group. Immunofluorescence analysis showed that HMF promoted colonic cell proliferation, concomitant with an increased level of reactive oxygen species (ROS). To our knowledge, this is the first in vivo finding that long-term HMF exposure could affect the mouse gut microbiota, ROS levels, and colonic cell proliferation in the colon. Moreover, the changes in gut microbiota can be restored by returning mice to the GMF environment, thus the possible harm to the microbiota caused by HMF exposure can be alleviated. © 2022 Bioelectromagnetics Society.
There is enough evidence to indicate we may be damaging non-human species at ecosystem and biosphere levels across all taxa from rising background levels of anthropogenic non-ionizing electromagnetic fields (EMF) from 0 Hz to 300 GHz. The focus of this Perspective paper is on the unique physiology of non-human species, their extraordinary sensitivity to both natural and anthropogenic EMF, and the likelihood that artificial EMF in the static, extremely low frequency (ELF) and radiofrequency (RF) ranges of the non-ionizing electromagnetic spectrum are capable at very low intensities of adversely affecting both fauna and flora in all species studied. Any existing exposure standards are for humans only; wildlife is unprotected, including within the safety margins of existing guidelines, which are inappropriate for trans-species sensitivities and different non-human physiology. Mechanistic, genotoxic, and potential ecosystem effects are discussed.
The advancement in science and technology has resulted in the invention and widespread usage of many electrical devices in the daily lives of humans. The exponential use of modern electronic facilities has increased electromagnetic field exposure in the current population. Therefore, the presented article deals with designing, constructing, and testing a new applicator system developed for cells electromagnetic biocompatibility studies. The applicator system is intended for studying the non-thermal impacts of low-frequency magnetic field on cell cultures growth. Main attention is focused on increasing the capacity of the applicator and effectivity of the experiments. The key idea is to reach high level of the magnetic field homogeneity in an area of interest and the temperature stability during the biocompatibility studies. The applicator system is designed based on numerical simulations and its construction, measurements, and properties evaluation are also reported for proving the applicator’s functionality. The new applicator allows performing five parallel experiments at the same time under the same conditions. The simulation together with the experimental results confirm that the magnetic field homogeneity reaches 99% in the area of interest and the maximum temperature instability is lower than 2% during the experiments. The effectiveness of new applicator is tested and proved during preliminary experiments with Saccharomyces Cerevisiae cells. The observed effects of MF exposure represent maximal stimulation of 74% and maximal inhibition of 49%. The reason why MF with the same parameters induces inhibition in one sample and stimulation in the other will be the subject of further research.
Abstract—Some current trends in the development of research on the effects and mechanisms of the biolog-ical action of weak and ultra-weak static magnetic fields, low-frequency alternating magnetic fields, combined magnetic fields, and radio frequency fields in combination with a static magnetic field are presented.Experimental studies in which interesting and somewhat unexpected effects of magnetic fields with strengthsignificantly lower than the magnetic field of the Earth (including those with intensities close to zero) wereobserved, are considered. The data are given taking into account the materials of the joint annual meeting ofthe Society of Bioelectromagnetism and the European Association of Bioelectromagnetism “BioEM 2021”(September 26–30, 2021, Ghent, Belgium).
In this paper, we review the literature on three important exposure metrics that are inadequately represented in most major radiofrequency radiation (RFR) exposure guidelines today: intensity, exposure duration, and signal modulation. Exposure intensity produces unpredictable effects as demonstrated by nonlinear effects. This is most likely caused by the biological system's ability to adjust and compensate but could lead to eventual biomic breakdown after prolonged exposure. A review of 112 low-intensity studies reveals that biological effects of RFR could occur at a median specific absorption rate of 0.0165 W/kg. Intensity and exposure duration interact since the dose of energy absorbed is the product of intensity and time. The result is that RFR behaves like a biological "stressor" capable of affecting numerous living systems. In addition to intensity and duration, man-made RFR is generally modulated to allow information to be encrypted. The effects of modulation on biological functions are not well understood. Four types of modulation outcomes are discussed. In addition, it is invalid to make direct comparisons between thermal energy and radiofrequency electromagnetic energy. Research data indicate that electromagnetic energy is more biologically potent in causing effects than thermal changes. The two likely functionthrough different mechanisms. As such, any current RFR exposure guidelines based on acute continuous-wave exposure are inadequate for health protection.
The work began in 1972 when three young assistant professors used a slime mold to see if electromagnetic fields would affect it. The fields did, though the effects were small and hard to tease out of the noise. The cell cycle was lengthened and there were changes in respiration. So, the next question was “how and why?” Further changes were seen using these and then other bacterial and eukaryotic cells in respiration, in ATP, in the protein replication chain, and so forth. Changes occurred even in cell extracts that lacked an intact plasma membrane. Nerve cells showed changes in leakage of neurotransmitters and in neurite outgrowth from excised ganglia. Based on some experiments with nerve cells, I also did some computer calculations, modeling the internal electric and magnetic fields and current densities in simplified representations of bone fractures and also of spinal cords in vertebrae. More recently, I have collaborated on some theoretical models of what fields might be doing at the cellular and molecular level, particularly with reference to the radical model. With each piece of research, my collaborators and I generally found a small piece of information about fields and biological systems; and each answer raised another set of questions, which is the way of science. Though bioelectromagnetic scientists have learned much and can say much at greater depth about what happens when an organism is exposed to a field, the fundamental question still remains: What exactly is going on here?
In this research, changes in the expression of B-cell lymphoma 2 (BCL2), miR-15-b and miR-16 in human adenocarcinoma gastric cancer cell line (AGS) following the exposure to magnetic flux densities (MFDs) of 0.2 and 2 mT continuously and discontinuously (1.5 h on/1.5 h off) for 18 h were investigated. Changes in the cell viability were evaluated by the MTT assay. Real-time PCR was used to evaluate the expression changes of BCL2, miR-15-b and miR-16. The results showed that extremely low frequency electromagnetic field (ELF-EMF) could significantly reduce the viability of AGS cells in the continuous MFD of 2 mT. The BCL2 expression was significantly decreased following the exposure to continuous MFDs of 0.2 and 2 mT and discontinuous MFD of 2 mT. The expressions of miR-15-b and miR-16 were significantly increased in continuous and discontinuous MFD of 2 mT. According to the results, weak and moderate extremely low-frequency electromagnetic fields can change the expressions of BCL2, miR-15-b and miR-16.
The effects of weak magnetic fields on the biological production of reactive oxygen species (ROS) from intracellular superoxide (O2•-) and extracellular hydrogen peroxide (H2O2) were investigated in vitro with rat pulmonary arterial smooth muscle cells (rPASMC). A decrease in O2•- and an increase in H2O2 concentrations were observed in the presence of a 7 MHz radio frequency (RF) at 10 μTRMS and static 45 μT magnetic fields. We propose that O2•- and H2O2 production in some metabolic processes occur through singlet-triplet modulation of semiquinone flavin (FADH•) enzymes and O2•- spin-correlated radical pairs. Spin-radical pair products are modulated by the 7 MHz RF magnetic fields that presumably decouple flavin hyperfine interactions during spin coherence. RF flavin hyperfine decoupling results in an increase of H2O2 singlet state products, which creates cellular oxidative stress and acts as a secondary messenger that affects cellular proliferation. This study demonstrates the interplay between O2•- and H2O2 production when influenced by RF magnetic fields and underscores the subtle effects of low-frequency magnetic fields on oxidative metabolism, ROS signaling, and cellular growth.
The chemical compass model, based on radical pair reactions, is an idea to explain avian magnetoreception. At present, to the best of our knowledge, questions concerning the key ingredients responsible for the high sensitivity of a chemical compass and the possible role of quantum coherence and decoherence remain unsolved. Here, we investigate the optimized hyperfine coupling for a chemical compass in order to achieve the best magnetic field sensitivity. We show that its magnetic sensitivity limit can be further extended by simple quantum control and may benefit from additional decoherence. With this, we clearly demonstrate how quantum coherence can be exploited in the functioning of a chemical compass. The present results also provide routes toward the design of a biomimetic weak magnetic field sensor.
Magnetoreception in the animal kingdom has focused primarily on behavioural responses to the static geomagnetic field and the slow changes in its magnitude and direction as animals navigate/migrate. There has been relatively little attention given to the possibility that weak extremely low-frequency magnetic fields (wELFMF) may affect animal behaviour. Previously, we showed that changes in nociception under an ambient magnetic field-shielded environment may be a good alternative biological endpoint to orientation measurements for investigations into magnetoreception. Here we show that nociception in mice is altered by a 30 Hz field with a peak amplitude more than 1000 times weaker than the static component of the geomagnetic field. When mice are exposed to an ambient magnetic field-shielded environment 1 h a day for five consecutive days, a strong analgesic (i.e. antinociception) response is induced by day 5. Introduction of a static field with an average magnitude of 44 µT (spatial variability of ±3 µT) marginally affects this response, whereas introduction of a 30 Hz time-varying field as weak as 33 nT has a strong effect, reducing the analgesic effect by 60 per cent. Such sensitivity is surprisingly high. Any purported detection mechanisms being considered will need to explain effects at such wELFMF.
Organisms have been exposed to the geomagnetic field (GMF) throughout evolutionary history. Exposure to the hypomagnetic field (HMF) by deep magnetic shielding has recently been suggested to have a negative effect on the structure and function of the central nervous system, particularly during early development. Although changes in cell growth and differentiation have been observed in the HMF, the effects of the HMF on cell cycle progression still remain unclear. Here we show that continuous HMF exposure significantly increases the proliferation of human neuroblastoma (SH-SY5Y) cells. The acceleration of proliferation results from a forward shift of the cell cycle in G1-phase. The G2/M-phase progression is not affected in the HMF. Our data is the first to demonstrate that the HMF can stimulate the proliferation of SH-SY5Y cells by promoting cell cycle progression in the G1-phase. This provides a novel way to study the mechanism of cells in response to changes of environmental magnetic field including the GMF.
Small alterations in static magnetic fields have been shown to affect certain chemical reaction rates ex vivo. In this manuscript, we present data demonstrating that similar small changes in static magnetic fields between individual cell culture incubators results in significantly altered cell cycle rates for multiple cancer-derived cell lines. This change as assessed by cell number is not a result of apoptosis, necrosis, or cell cycle alterations. While the underlying mechanism is unclear, the implications for all cell culture experiments are clear; static magnetic field conditions within incubators must be considered and/or controlled just as one does for temperature, humidity, and carbon dioxide concentration.
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.
The yield of singlet oxygen sensitized by chemically modified, carotenoidless bacterial photosynthetic reaction centres and the ensuing oxidative damage are both shown to be magnetic field-dependent.
Epidemiologic and experimental research on the potential carcinogenic effects of extremely low frequency electromagnetic fields (ELF-EMF) has been performed for a long time. Epidemiologic studies regarding ELF-EMF-exposure have focused primarily on leukaemia development due to residential sources in children and adults, and from occupational exposure in adults, but also on other kinds of cancer. Genotoxic investigations of EMF have shown contradictory results, a biological mechanism is still lacking that can explain the link between cancer development and ELF-EMF-exposure. Recent laboratory research has attempted to show general biological effects, and such that could be related to cancer development and/or promotion. Metabolic processes which generate oxidants and antioxidants can be influenced by environmental factors, such as ELF-EMF. Increased ELF-EMF exposure can modify the activity of the organism by reactive oxygen species leading to oxidative stress. It is well established that free radicals can interact with DNA resulting in single strand breaks. DNA damage could become a site of mutation, a key step to carcinogenesis. Furthermore, different cell types react differently to the same stimulus, because of their cell type specific redox status. The modulation of cellular redox balance by the enhancement of oxidative intermediates, or the inhibition or reduction of antioxidants, is discussed in this review. An additional aspect of free radicals is their function to influence other illnesses such as Parkinson's and Alzheimer's diseases. On the other hand, modulation of antioxidants by ELF-EMF can lower the intracellular defence activity promoting the development of DNA damage. It has also been demonstrated that low levels of reactive oxygen species trigger intracellular signals that involve the transcription of genes and leading to responses including cell proliferation and apoptosis. In this review, a general overview is given about oxidative stress, as well as experimental studies are reviewed as they are related to changes in oxidant and antioxidant content after ELF-EMF exposure inducing different biological effects. Finally, we conclude from our review that modulations on the oxidant and antioxidant level through ELF-EMF exposure can play a causal role in cancer development.
Magnetic Properties of Electron and Nuclear Spins Introduction to Electron Spin Resonance and Nuclear Magnetic Resonance The Radical Pair Mechanism (RPM) Chemically Induced Dynamic Nuclear Polarization (CIDNP) Chemically Induced Dynamic Electron Polarization (CIDEP) Magnetic Field Effects on Chemical Reactions Due to the RPM Magnetic Fields Effects Due to the Relaxation Mechanism Magnetic Field Effects on Chemical Reactions through Biradicals Magnetic Isotope Effects Triplet Mechanism Theoretical Analysis with the Stochastic Liouville Equation Effects of Ultra-High Magnetic Fields on Chemical Reactions Effects of Magnetic Fields of High Spin Species Optical Detected ESR and Reaction Yield Detected ESR Magnetic Field Effects on Biochemical Reactions and Biological Processes.
A benchmark biochemical reaction is here theoretically investigated by means of a perturbative approach in order to model each reaction step. The reaction is the flavin-indole electron transfer, involving also a spin-state relaxation of the ionic complex. The whole reaction path is modeled and the kinetics of the process is studied. The dipolar interaction between the two radicals is explicitly considered during the dynamic evolution of the system in order to investigate the proper conditions for the triplet-to-singlet transition to occur.
A new algorithm for calculating magnetic fields in a concentrated magnetic fluid with inhomogeneous density is proposed. Inhomogeneity of the fluid is caused by magnetophoresis. In this case, the diffusion and magnetostatic parts of the problem are tightly linked together and are solved jointly. The dynamic diffusion equation is solved by the finite volume method and, to calculate the magnetic field inside the fluid, an iterative process is performed in parallel. The solution to the problem is sought in Cartesian coordinates, and the computational domain is decomposed into rectangular elements. This technique eliminates the need to solve the related boundary-value problem for magnetic fields, accelerates computations and eliminates the error caused by the finite sizes of the outer region. Formulas describing the contribution of the rectangular element to the field intensity in the case of a plane problem are given. Magnetic and concentration fields inside the magnetic fluid filling a rectangular cavity generated under the action of the uniform external filed are calculated.
This article is organized around the principle of hypothesis-based research into biological magnetic field effects. It is intended to serve as an introduction to current issues and to review recent progress toward answering the fundamental question of how magnetic fields interact with biological systems. This review will focus on those magnetic field effects that can be addressed within the existing paradigms of chemistry and physics in order to encourage further research within this community. In the last section of this review, those biological magnetic field effects that are understood at only a minimal level will be summarized, but not evaluated critically. 191 refs.
Accurate expressions are derived for the effect of a radiofrequency (rf) field on the reaction yield of a radical pair (RP). We consider the recombination yield of a geminate RP under the influence of a static magnetic field in combination with a radio frequency field perpendicular to the static field. The results are obtained by solving the steady state stochastic Liouville equation by an approximation scheme introduced in our previous work [M.J. Hansen, J.B. Pedersen, Chem. Phys. Lett. 361 (2002) 219]. The general formula is expressed in terms of a characteristic function for the relative motion of the radical pair. It can thus be applied to a wide range of systems, e.g. confined and low dimensional systems of biochemical interest, such as micelles and membranes. Explicit analytical expressions are given for free diffusion. The expressions are directly applicable to RYDMR spectra since the static magnetic field is assumed to be larger than the hyperfine interaction. The high accuracy of the expressions is illustrated by comparison with numerically exact results.
Bawin and her coworkers have reported changes in binding of calcium
after exposure of avian brain tissue to nonionizing electromagnetic
radiation. Because calcium is intimately involved in the electrical
activity of the brain, their results reveal a heretofore unrecognized
potential for nonionizing radio-frequency radiation to affect biological
function. We have verified and extended their findings. The forebrains
of newly hatched chickens, separated at the midline to provide
treatment-control pairs, were labeled in vitro with radioactive calcium.
Samples of tissue were exposed for 20 minutes in a Crawford irradiation
chamber to 147-MHz radiation, which was amplitude modulated sinusoidally
at selected frequencies between 3 and 30 Hz. Power densities of incident
radiation ranged between 0.5 and 2 mW cm-2. Compared with
nonirradiated samples, a statistically significant increase in efflux of
calcium ions (P < 0.01) was observed in irradiated samples at a
modulation frequency of 16 Hz and at a power density of 0.75 mW
cm-2. Our data confirm the existence of the frequency
"window" reported by Bawin et al., as well as a narrow power-density
"window" within which efflux of calcium ions is enhanced.
A simple method is developed for calculation of nuclear polarization in products of radical coupling reactions carried out at zero magnetic field.
CIDNP during photolysis of diisopropyl ketone is described. In most solvents CIDNP spectra are in accordance with radical pair formation (type I split) from triplet state ketone. In CCl4, however, the reaction probably involves complex formation of excited singlet state ketone with the solvent, as evidenced by CIDNP and fluorescence quenching.
CIDNP NMR spectra of reaction products of five alkyl radicals (methyl, ethyl, propyl, isopropyl and tert-butyl) are presented. Anomalous enhancements in multiplets are observed.
The J=1/2→3/2 (v=0) rotational transition of the 2π1/2 state of N14O16 has been measured. This transition occurs at 150 372.30 Mc/sec and is split into two groups of five lines due to Λ-type doubling and a large magnetic hyperfine interaction. The value of B0 is found to be 1.69510 cm-1 and r0=1.1539A. The Λ-doubling constant p is determined as 355.2 Mc/sec, and a spin of 1 is again confirmed for N14. A preliminary analysis of the magnetic hyperfine structure is given, based on the interaction Hamiltonian aIz′Lz′+bI·S+cIz′Sz′, where a, b, and c are constants.
The nine-line magnetic resonance spectrum of N14O16 is observed at fields in the range of 8600 oersted at a frequency of 9360 megacycle/sec. The spectrum arises from magnetic-dipole transitions between Zeeman levels in the J=32 state of the 2Pi32 spin component. The line positions allow a determination of the magnetic IJ coupling constant, which is 29.8+/-0.3 megacycle/sec., and the nuclear electric quadrupole coupling, which is -1.7+/-0.5 megacycle/sec. The line position and triplet spacings, which arise from molecular perturbations, are in good agreement with the theory of Margenau and Henry. The absolute intensity of the three stronger lines is measured to be chi''=1.2×10-10 which also agrees with theory.
Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies
Optical pumping of ground-state and metastable atoms and ions is
reviewed. We present a critical survey of the literature on pumping
mechanisms, light propagation, relaxation mechanisms, spin exchange, and
experimental details on the various atomic species which have been
successfully pumped.
The radical pair mechanism is used to elucidate how applied magnetic fields that are weaker in strength than typical hyperfine interactions can influence the yields and kinetics of recombination reactions of free radicals in solution. The so-called low field effect is shown to arise from coherent superpositions of degenerate electron-nuclear spin states in a spin-correlated radical pair in zero field. A weak applied magnetic field causes these (zero-quantum) coherences to oscillate, leading to coherent interconversion of singlet and triplet electronic states of the radical pair and hence changes in the yields of recombination products and of the free radicals that escape into solution. For singlet geminate radical pairs, the low field effect leads to a boost in the concentration of free radicals, which may be relevant in the context of in vivo biological effects of electromagnetic fields. Using analytical approaches in limiting cases, the maximum possible low field effects are calculated for a variety of radical pairs. Sizeable changes in reaction yields (~20%) are found for almost any radical pair provided the spin-correlation persists long enough for significant evolution of the electron spins under the influence of the weak applied field. The conditions necessary for observing effects as large as ~ 20% are discussed.
Recent reaction-yield-detected magnetic resonance experiments in weak static magnetic fields and the observation of resonance effects in animal orientation experiments provide the motivation for renewed studies of magnetic field effects on radical-pair reactions. Here, we investigate theoretically resonance patterns for weak static magnetic fields. We focus on the question: for which radical pairs can one expect Zeeman resonances to occur if the static field is weaker than typical hyperfine interactions? Using analytical approaches, we rationalize the occurrence of Zeeman resonances for simple radical pairs. Numerical solutions are presented for a wide range of radical pairs with up to seven hyperfine interactions employing the rotating-frame transformation. The results suggest that resonances occur close to either the Larmor frequency or half the Larmor frequency for a wide variety of radical pairs for spin Hamiltonians with a high degree of symmetry. For larger numbers of hyperfine interactions, Zeeman resonances decrease in size.
Molecular transformation (chemical reaction) as an electron−nuclear rearrangement of the reactants into the products is the heart of chemistry, the central event which all chemistry circulates about. It is selective to the nuclei, both in mass and spin. Nuclear mass selectivity of reactions results in classical isotope effect (CIE), the remarkable phenomenon which continues to play a unique role and has served served for many years as a powerful and reliable tool of mechanistic chemistry and biochemistry. Another breakthrough of similar scale and importance is the discovery of nuclear spin selectivity of chemical reactions, which is the dependence of the reaction rates on the nuclear spin and nuclear magnetic moment of the reactants. In contrast to CIE, which is governed by chemical energy of the starting and transition states of reactant molecules, this new isotope effect is controlled by magnetic interactions, so it was christened the magnetic isotope effect (MIE). The general principles of tuning of the reactions to MIE are discussed, particularly by microwaves, tunable on frequency and amplitude, to selectively modify and control chemical reactivity.
The radical pair theory of high-field CIDNP is generalized to describe nuclear polarization originating from chemical reactions in magnetic fields of any strength. In low fields mixing of electronic singlet (S) with three triplet states (T+, T-, and T0) of the radical pair has to be considered, whereas in high field only S-T0 mixing. Starting from pure S or T states the time development of the spin states is described by the Schrödinger equation in which a time-independent Hamiltonian is employed, containing isotropic Zeeman, exchange, and hyperfine interaction terms. It is assumed that the radical pairs undergo random-walk diffusion (giving a t-3/2 time dependence for the reencounter probability) and that recombination occurs only from the S state. It is found that low-field CIDNP spectra depend on the probability of reaction during a singlet encounter (λ). Furthermore, S and T precursors (of radical pairs) give rise to opposite polarization in all magnetic fields, whereas recombination and "escape" products give opposite behavior only in high fields and in zero field, but not in low fields. The zero-field problem is treated in an Appendix. Experimental low-field CIDNP spectra recorded on an A-60 spectrometer after photolysis of solutions of propionyl peroxide and of diisopropyl ketone in an auxiliary magnet show good agreement with computer-simulated spectra, when it is assumed that sample transfer to the spectrometer field occurs adiabatically. In particular, the theory can account for the observed oscillations in the polarization vs. magnetic field curve.
In an attempt to understand the apparently disparate results reported in magnetic field effect studies on the same reaction system from different experimental groups, two different techniques, time-resolved methods and field-modulated ones, have been applied to systems comprising pyrene and either dicyanobenzene or dimethylaniline. It is shown that these yield different results whose origin lies less in the detection method than in the light sources which produce the radicals. The results from the time-resolved experiments, in which the effects of spin relaxation in a singlet-correlated pair are apparent, have been analyzed using a novel approach applicable to more complex reaction systems than have been studied in the past. An original experiment is introduced to observe the effects of relaxation at field strengths where the hyperfine-driven spin mixing has reached its asymptotic rate. The discrepancy between the results originates in a much shortened radical pair lifetime, resulting from a very low radical concentration under the conditions used in the modulation experiment as opposed to the time-resolved one. This lifetime effect has been confirmed by using degenerate electron-exchange reactions to affect the chemistry in the period of observation in each technique. Low-field minima in the field effect curves observed using the modulation method are shown to originate in hyperfine and effects and not to be due to J-resonances.
Previously, the effect of applied magnetic fields on the yield of the reaction of the radical ions of pyrene and 1,3-dicyanobenzene (DCB) has been measured by monitoring the emission of the pyrene/1,3-DCB exciplex formed from the singlet state of the spin-correlated radical pair (SCRP). This Letter describes an alternative approach that relies on energy transfer from the excited triplet state of pyrene to the tris(2,2′-bipyridyl)ruthenium(II) ion, , allowing the recombination of the triplet SCRP to be monitored by emission spectroscopy. Measurements of magnetic field effects in combination with time-resolved flash photolysis and luminescence experiments confirm triplet–triplet energy transfer as the reaction mechanism.
A mechanism is proposed to account for observations by Fessenden and Schuler and Smaller et al. of ESR emission during radiolysis experiments. The same mechanism supplemented by spin relaxation may explain anomalous CIDNP multiplets.
This paper reviews the latest developments in the field of spin chemistry with a particular focus on the effects of weak static and/or oscillating magnetic fields (typically smaller than the average hyperfine coupling) on radical recombination reactions. Anisotropic magnetic field effects and their significance in the debate about potential mechanisms controlling magnetoreception in birds are discussed.
Thesis (Ph. D.)--University of Colorado, 1996. Includes bibliographical references (leaves [122]-126).
Although the interest in experimental evidence of magnetic field effects (MFEs) on the kinetics of chemical reactions, which might be characterized by the term magnetokinetics, has a long tradition, an impressive evolution of the field took place only after the discovery and understanding of nuclear and electronic spin polarization phenomena during chemical reactions (CIDNP, CIDEP) in the late 1960s. The so-called radical pair mechanism lying at the heart of these phenomena turned out to be a most valuable key for systematically tracing out MFEs on chemical yields and kinetics. Nevertheless one should be aware that other mechanisms, too, with pairs of triplets, triplet-doublet pairs, or individual triplets, which originated at about the same time and were initially developed for explaining magnetic phenomena on luminescence in organic solids, also have their implication on chemical, particularly on photochemical, kinetics. Phenomenologically, the basic mechanisms of magnetic-field-dependent reaction mechanisms may become apparent in fields and systems as different as the gas phase, the solid and liquid states, interfaces, and microheterogeneous systems such as micelles and in billogical systems. In all of these applications they have specific experimental and theoretical characteristics. Also, the techniques applied to study magnetokinetic phenomena span a large variety, ranging from magnetic resonance detection of spin polarization (CIDNP, CIDEP, ODMR) through simple detection of magneticfield-dependent reaction yields and magnetic isotope effects (MIE) to reaction-yield-detected magnetic resonance (RYDMR). Thus the field of magnetokinetic chemical and related physical phenomena appears as a tree with several roots and many branches. Although each of these branches has been reviewed from time to time (cf. Table l), most of the treatments have been rather specialized, and it is not easy to provide oneself with a broad and general view of the scope, objectives, and achievements of the field. Thus we have found it worthwhile to write this survey, developing the different aspects from a fairly general point of view (cf. section 11), and to review, as comprehensively as possible, the original experimental (section IV) and theoretical (section V) work published since the early 1970s, providing whenever possible a systematic compilation in the form of tables. Furthermore, in section I11 an outline of the various experimental techniques applied in the field is given. Of course, the goals of completeness and compactness were not attainable without compromise. Thus the large field of chemically induced spin polarization phenomena would have been beyond the scope of this review. We have, however, attempted to include those theoretical papers in the field that have a general bearing on the understanding of magnetokinetic effects in general. We felt that, especially where photochemistry is concerned, the borderline between truly chemical and purely physical phenomena should not be defined too formally, since from the mechanistic and theoretical point of view they may be closely related. In order to account for this we included what has been termed related phenomena in the title of this review. Of course. the problem of delimitation cannot be solved without arbitrariness. The more photophysical aspects are mainly to be found in the sections on gas-phase and solid-state phenomena. In the solid state our attention has been mainly directed on work with organic molecular crystals. Only some representative references on inorganic solids and semiconductors are given. We hope that this review may provide a welcome guide to the present body of literature on magnetokinetics, that it may help those working in the field to assess the achievements of current original work, and that it may be a useful framework of orientation for those who want to get into it or get an impression of the present scope of magnetokinetics.
Intracranial injection of Ca**2** plus or Mg**2** plus left bracket 20 mu 1, 40 mM right bracket in chronically implanted neonatal chicks resulted in an almost immediate synchronization of the hyperstriatal EEG, accompanied by behavioral depression. During successive testing days, the animals appeared to recover behaviorally but never showed any sustained EEG arousal. By contrast, animals treated with sodium chloride recovered completely within the first hour after the injection. The chick forebrain, being so highly sensitive to small perturbations of the extracellular concentrations of either divalent cations, was therefore chosen for investigating, in vitro, the possible interactions between extracellular weak voltage gradients, induced by vhf radiations, and ionic movements in cerebral tissue. In the present experiment, **4**5Ca**2** plus fluxes from irradiated brains are compared at various frequencies of amplitude modulation of the carrier wave.
A physical mechanism is suggested for a resonant interaction of weak magnetic fields with biological systems. An ion inside a Ca(2+)-binding protein is approximated by a charged oscillator. A shift in the probability of ion transition between different vibrational energy levels occurs when a combination of static and alternating magnetic fields is applied. This in turn affects the interaction of the ion with the surrounding ligands. The effect reaches its maximum when the frequency of the alternating field is equal to the cyclotron frequency of this ion or to some of its harmonics or sub-harmonics. A resonant response of the biosystem to the magnetic field results. The proposed theory permits a quantitative explanation for the main characteristics of experimentally observed effects.
Theoretical models proposed to date have been unable to clearly predict biological results from exposure to low-intensity electric and magnetic fields (EMF). Recently a predictive ionic resonance model was proposed by Lednev, based on an earlier atomic spectroscopy theory described by Podgoretskii and Podgoretskii and Khrustalev. The ion parametric resonance (IPR) model developed in this paper corrects mathematical errors in the earlier Lednev model and extends that model to give explicit predictions of biological responses to parallel AC and DC magnetic fields caused by field-induced changes in combinations of ions within the biological system. Distinct response forms predicted by the IPR model depend explicitly on the experimentally controlled variables: magnetic flux densities of the AC and DC magnetic fields (Bac and Bdc, respectively); AC frequency (fac); and, implicitly, charge to mass ratio of target-ions. After clarifying the IPR model and extending it to combinations of different resonant ions, this paper proposes a basic set of experiments to test the IPR model directly which do not rely on the choice of a particular specimen or endpoint. While the fundamental bases of the model are supported by a variety of other studies, the IPR model is necessarily heuristic when applied to biological systems, because it is based on the premise that the magnitude and form of magnetic field interactions with unhydrated resonant ions in critical biological structures alter ion-associated biological activities that may in turn be correlated with observable effects in living systems.
The radical pair mechanism is discussed as a possible route whereby a magnetic field of environmental strength might affect a biological system. It is well established as the origin of reproducible field effects in chemistry, and these can be observed even at very low magnetic field strengths, including that of the geomagnetic field. Here it is attempted to give a description which might assist experimentalists working in biological laboratories to devize tests of its relevance to their work. The mechanism is well understood and a specific theoretical approach is taken to explore and emphasize the importance of the lifetime of the radical pair and the precise chemical natures of the radicals which comprise it in affecting the size of the low-field effects. Further subsequent processes are likely necessary to cause this primary effect to attain biological significance. Arguments are provided to suggest that the encounters of freely diffusing pairs (F-pairs) of radicals are unlikely to produce significant effects in biology.
We can expect that biological responses to very weak ELF electromagnetic fields will be masked by thermal noise. However, the spin of electrons bound to biologically important molecules is not strongly coupled to the thermal bath, and the effects of the precession of those spins by external magnetic fields is not bounded by thermal noise. Hence, the known role of spin orientation in the recombination of radical pairs (RP) may constitute a mechanism for the biological effects of very weak fields. That recombination will generally take place only if the valence electrons in the two radicals are in a singlet state and the effect of the magnetic field is manifest through differential spin precessions that affect the occupation of that state. Because the spin relaxation times are of the order of microseconds, any effects must be largely independent of frequency up to values of a few megahertz. Using exact calculations on an appropriately general model system, we show that one can expect small, but significant, modifications of the recombination rate by a 50 microT field only under a narrow range of circumstances: the cage time during which the two elements are together must be exceptionally long--of the order of 50 ns or longer; the hyperfine field of either radical must not be so great as to generate a precession period greater than the cage containment time; and the characteristic recombination time of the radical pair in the singlet state must be about equal to the containment time. Thus, even under such singularly favorable conditions, fields as small as 5 microT (50 milligauss) cannot change the recombination rate by as much as 1%. Hence, we conclude that environmental magnetic fields much weaker than the earth's field cannot be expected to affect biology significantly by modifying radical pair recombination probabilities.
The influence of radiofrequency electromagnetic exposure on ligand binding to hydrophobic receptor proteins is a plausible early event of the interaction mechanism. A comprehensive quantum Zeeman-Stark model has been developed which takes into account the energy losses of the ligand ion due to its collisions inside the receptor crevice, the attracting nonlinear endogenous force due to the potential energy of the ion in the binding site, the out of equilibrium state of the ligand-receptor system due to the basal cell metabolism, and the thermal noise. The biophysical "output" is the change of the ligand binding probability that, in some instances, may be affected by a suitable low intensity exogenous electromagnetic "input" exposure, e.g., if the depth of the potential energy well of a putative receptor protein matches the energy of the radiofrequency photon. These results point toward both the possibility of the electromagnetic control of biochemical processes and the need for a new database of safety standards.
We present measurements of the spectrum (1--80 MHz) of the effect of a weak (approximately 500 microT) radio frequency magnetic field on the electron-hole recombination of radical ion pairs in solution. Distinct spectra are observed for the pyrene anion/dimethylaniline cation radical pair in which one or both of the radicals are perdeuterated. The radical pair mechanism is developed theoretically and shown to account satisfactorily for both the magnetic field effect and the associated magnetic isotope effect.
At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, however, nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. Many of the ROS-mediated responses actually protect the cells against oxidative stress and reestablish "redox homeostasis." Higher organisms, however, have evolved the use of NO and ROS also as signaling molecules for other physiological functions. These include regulation of vascular tone, monitoring of oxygen tension in the control of ventilation and erythropoietin production, and signal transduction from membrane receptors in various physiological processes. NO and ROS are typically generated in these cases by tightly regulated enzymes such as NO synthase (NOS) and NAD(P)H oxidase isoforms, respectively. In a given signaling protein, oxidative attack induces either a loss of function, a gain of function, or a switch to a different function. Excessive amounts of ROS may arise either from excessive stimulation of NAD(P)H oxidases or from less well-regulated sources such as the mitochondrial electron-transport chain. In mitochondria, ROS are generated as undesirable side products of the oxidative energy metabolism. An excessive and/or sustained increase in ROS production has been implicated in the pathogenesis of cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and other diseases. In addition, free radicals have been implicated in the mechanism of senescence. That the process of aging may result, at least in part, from radical-mediated oxidative damage was proposed more than 40 years ago by Harman (J Gerontol 11: 298-300, 1956). There is growing evidence that aging involves, in addition, progressive changes in free radical-mediated regulatory processes that result in altered gene expression.
The photoinduced electron-transfer reaction of chrysene with isomers of dicyanobenzene is used to demonstrate the sensitivity of a radical recombination reaction to the orientation and frequency (5-50 MHz) of a approximately 300 muT radio frequency magnetic field in the presence of a 0-4 mT static magnetic field. The recombination yield is detected via the fluorescence of the exciplex formed exclusively from the electronic singlet state of the radical ion pair Chr*+/DCB*-. Magnetic field effects are simulated using a modified version of the gamma-COMPUTE algorithm, devised for the simulation of magic angle spinning NMR spectra of powdered samples. The response of a chemical or biological system to simultaneously applied radio frequency and static or extremely low-frequency magnetic fields could form the basis for a diagnostic test for the operation of the radical pair mechanism that would not require prior knowledge of the nature and properties of the radical reaction.
The aim of the work was verification of the hypothesis that weak power frequency (50 Hz) magnetic fields (MF) affected the number of free oxygen radicals in living biological cells and that these changes could be qualitatively explained by the radical pair mechanism. The experiments were performed on rat lymphocytes. One-hour exposure to 50 Hz MF at 20, 40, or 200 microT flux densities was performed inside a pair of Helmholtz coils with axis along or crosswise to the Earth's static MF. Iron ions (FeCl2) were used as a stimulator of the oxidation processes. Oxygen radicals were measured by fluorimetry using a DCF-DA fluorescent probe. Only in the lymphocytes exposed at 40 microT MF directed along the Earth's static MF there was a decrease of fluorescence in relation to non-exposed samples. Our observation seems to confirm the hypothesis that low level power frequency MF affects oxidative processes which occur in living biological cells and that this effect can be explained by the radical pair mechanism.
Measurements are reported of the effects of 0-23 mT applied magnetic fields on the spin-selective recombination of Py*- and DMA*+ radicals formed in the photochemical reaction of pyrene and N,N-dimethylaniline. Singlet <--> triplet interconversion in [Py*- DMA*+] radical pairs is probed by investigating combinations of fully protonated and fully deuterated reaction partners. Qualitatively, the experimental B1/2 values for the four isotopomeric radical pairs agree with predictions based on the Weller equation using known hyperfine coupling constants. The amplitude of the "low field effect" (LFE) correlates well with the ratio of effective hyperfine couplings, aDMA/aPy. An efficient method is introduced for calculating the spin evolution of [Py*- DMA*+] radical pairs containing a total of 18 spin-1/2 and spin-1 magnetic nuclei. Quantitative analysis of the magnetic field effects to obtain the radical re-encounter probability distribution f (t )-a highly ill-posed and underdetermined problem-is achieved by means of Tikhonov and maximum entropy regularization methods. The resulting f (t ) functions are very similar for the four isotopomeric radical pairs and have significant amplitude between 2 and 10 ns after the creation of the geminate radical pair. This interval reflects the time scale of re-encounters that are crucial for generating the magnetic field effect. Computer simulations of generalized radical pairs containing six spin-1/2 nuclei show that Weller's equation holds approximately only when the radical pair recombination rate is comparable to the two effective hyperfine couplings and that a substantial LFE requires, but is not guaranteed by, the condition that the two effective hyperfine couplings differ by more than a factor of 5. In contrast, for very slow recombination, essentially any radical pair should show a significant LFE.