Effects of weak static magnetic fields on endothelial cells

Pulsed electromagnetic fields (PEMFs) have been used extensively in bone fracture repairs and wound healing. It is accepted that the induced electric field is the dose metric. The mechanisms of interaction between weak magnetic fields and biological systems present more ambiguity than that of PEMFs since weak electric currents induced by PEMFs are believed to mediate the healing process, which are absent in magnetic fields. The present study examines the response of human umbilical vein endothelial cells to weak static magnetic fields. We investigated proliferation, viability, and the expression of functional parameters such as eNOS, NO, and also gene expression of VEGF under the influence of different doses of weak magnetic fields. Applications of weak magnetic fields in tissue engineering are also discussed. Static magnetic fields may open new venues of research in the field of vascular therapies by promoting endothelial cell growth and by enhancing the healing response of the endothelium. Bioelectromagnetics 31:296–301, 2010. © 2010 Wiley‐Liss, Inc.     

Cell response to extremely weak static magnetic fields

The effect of an extremely weak static magnetic field (EWSMF) was studied in diploid fibroblast strains that originated from a healthy donor and an ataxia–telangiectasia patient. Indirect immunofluorescence was used to detect p53, p53BP1, and p21. The pattern that occurred in donor cells exposed to EWSMF similar to that observed in DNA damage, viz., the p53 and p21 levels increased and p3BP1 foci formed. No visible change was observed in primary fibroblasts from the ataxia–telangiectasia patient. The results implicate ATM signaling in the fibroblast response to EWSMF.     

Effect of weak combined static and low-frequency alternating magnetic fields on the Ehrlich ascites carcinoma in mice

The parameters of the low-frequency (1, 4.4, 16.5 Hz or the sum of these frequencies) extremely weak (300, 100, 150–300 nT, according to frequencies) alternating component of combined magnetic fields have been found, which in combination with a weak collinear static field of 42 μT (the induction corresponds to the range of the geomagnetic field) has a marked antitumor activity. The exposure to these magnetic fields inhibits the tumor growth in mice with an intraperitoneally transplanted Ehrlich ascites carcinoma. The effect manifests itself as an increase in the life of tumor-bearing animals and in the content of damaged tumor cells. It was found that the death of tumor cells by the action of weak fields occurs predominantly by the mechanism of necrosis.     

Effect of weak and ultraweak static magnetic fields on the intensity of fission of the planarian Dugesia tigrina

It has been shown that, in the range of 03000 nT, a biological system differently responds to the treatment with a weak static magnetic field. Thus, at a practically complete compensation of the field (induction 5 nT), the intensity of fission of planarian does not differ from control values. As the field intensity is successively increased to 300 nT, a marked and statistically significant stimulating effect is observed (SC 1.51.8), which disappears in the intensity range of 400 and 600 nT. At intensities from 800 to 1500 nT, the stimulating effect manifests itself again. Further increase of field intensity to 3000 nT leads to the disappearance of the effect.     

Effect of static magnetic fields on the budding of yeast cells

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

Influence of weak static and 50 Hz magnetic fields on the redox activity of cytochrome-C oxidase

The effects of static and 50 Hz magnetic fields on cytochrome-C oxidase activity were investigated in vitro by strictly controlled, simultaneous polarographic measurements of the enzyme's high- and low-affinity redox reaction. Cytochrome-C oxidase was isolated from beef heart. Control experiments were carried out in the ambient geomagnetic and 50 Hz magnetic fields at respective flux densities of 45 and 1.8 μT. The experimentally applied fields, static and time-varying, were generated by Helmholtz coils at flux densities between 50 μT and 100 mT. Exposures were timed to act either on the combined enzyme-substrate interchange or directly on the enzyme's electron and proton translo-cations. Significant changes as high as 90% of the overall cytochrome-C oxidase activity resulted during exposure (1) to a static magnetic field at 300 μT or 10 mT in the high-affinity range, and (2) to a 50 Hz magnetic field at 10 or 50 mT in the low-affinity range. No changes were observed at other flux densities. After exposure to a change-inducing, static or time-varying field, normal activity returned. © 1993 Wiley-Liss. Inc.     

Effect of static magnetic fields on survival of leukaemia-prone AKR mice

Summary The influence of a life-long exposure to static magnetic fields (SMF) on the lifespan of female AKR mice which develop spontaneous lymphoblastic leukaemia was investigated. Exposure all day long to a circular SMF, 4.6 mT maximal intensity or 2 h a day, 5 consecutive days a week to a uniform SMF of 400 mT did not modify the lifespan of mice. Exposure 2 h a day, 5 consecutive days a week to a uniform SMF of 600 or 800 mT modified the lifespan: about 50% of the population had a longer survival than the controls. Mice exposed 30 min a day 5 consecutive days a week to a non-uniform SMF presented the same trend.     

Effect of weak static and low-frequency alternating magnetic fields on the fission and regeneration of the planarian dugesia (Girardia) tigrina

The effect of weak static (DC) and alternating (AC) magnetic fields (MFs), as well as combined (AC/DC) collinear MFs on the intensity of morphogenesis processes in the planarian Dugesia (Girardia) tigrina has been studied. It was found that combined MFs produce a stimulating effect on the fission and regeneration of planarians. Both components of the combined MFs, the direct (DC) and the alternating (AC), are important in the realization of the effects of weak MFs. The practically complete absence of one of the components (DC) reverses the sign of the effect. It was shown that the presence of concomitant background MFs does not substantially influence the effects of combined MFs with a very small AC component (100 nT). The effect of the "zero" field is significant and comparable in magnitude with the effects of combined MFs at effective frequencies. Narrow zones of effective amplitudes (in the region of tens and hundreds of nT) of the AC component of the combined MFs, with the DC component close to the value of the geomagnetic field were found, which alternate with regions where the response of the biological object to the influence is absent.     

Effect of static magnetic fields on osteoblasts and fibroblasts in vitro

In vitro assays were made of the effect of a static magnetic field of a neodymium magnet on cellular behavior. The cell turnover rate was examined by the incorporation of radioactive thymidine, and anabolic processes were measured by the incorporation of radioactive proline. Cell cultures of fibroblast- and osteoblast-like cells of the neonatal rat calvarium were assayed to determine uptakes of radioactive thymidine and proline; these assays were performed in conjunction with examination of an explant of the rat calvarium. The cells were assayed after exposure to a field for 1-, 3-, 5-, 7-, and 10-day periods. Cells were exposed to north and south poles with a pole-face flux density of 0.61 T; control cultures were exposed to an unmagnetised piece of neodymium. After sham exposure or exposure to the magnetic field, 50 μCuries/ml of culture media of isotope were added to the culture medium. The cultures were returned to an incubator for 6 h. Then, following centrifugation, the supernatant was assayed for radioactivity in a scintillation counter after addition of 3 ml of scintillation fluid. A statistically significant magnetic stimulation of turnover rate and synthesis of fibroblasts was found, but stimulation of osteoblasts did not occur. Conversely, the explants, which represent the osteoblasts and fibroblasts in an organised system, showed a statistically significant inhibition in uptake of the radioactive label. The data indicate both variability and diversity of cellular behaviour, and they accentuate the need for caution in the interpretation of effects of static magnetic fields. © 1993 Wiley-Liss, Inc.     

Effect of weak combined magnetic fields on the metamorphosis of the mealworm beetle Tenebrio molitor

The effects of weak combined magnetic fields adjusted to the parametric resonance for Ca²⁺ and K⁺ and extremely weak alternating magnetic field on the metamorphosis of the mealworm beetle Tenebrio molitor have been studied. It was shown that the exposure of pupas of insects to all above-indicated types of fields stimulates the metamorphosis. However, after the exposure to weak combined magnetic fields adjusted to the parametric resonance for Ca²⁺ and K⁺, the number of insects with anomalies increases, which is not observed by the action of the weak alternating magnetic field.     

Effect of weak combined magnetic fields on the metamorphosis of the meal-worm beetle Tenebrio molitor

The effects of weak combined magnetic fields adjusted to the parametric resonance for Ca2+ and K+ and extremely weak alternating magnetic field on the metamorphosis of the meal-worm beetle Tenebrio molitor have been studied. It was shown that the exposure of pupas of insects to all above-indicated types of fields stimulates the metamorphosis. However, after the exposure to weak combined magnetic fields adjusted to the parametric resonance for Ca2+ and K+, the number of insects with anomalies increases, which is not observed by the action of the weak alternating magnetic field.     

Influence of weak magnetic fields on fish retina photoreceptors

It has been shown for the first time that retina photoreceptors of the salmon Oncorhynchus masou (masu salmon) fry exposed to a constant magnetic field (80 Gs) in conditions of twilight illumination demonstrated not a twilight reaction, as in the control, but a darkness (scotopic) reaction. The pigment epithelium in this case reacted as to bright light. Under the influence of long wavelength red light, the retinomotor reaction corresponded to partial light adaptation. After the indemnification of the horizontal component (0.1 Gs) of the geomagnetic field, fish retina adapted to complete darkness demonstrated changes that could not be attributed to one of standard conditions of light exposure. Thus, the rods and cones demonstrated a reaction similar to that to twilight, double cones reacted as to complete darkness ("correct" reaction), and PE borrowed a position as at twilight. Apparently, the basic stimuli of the retina reactions were not light but changes of the magnetic field. Based on these results and the results available in literature, the authors offer a new variant of the hypothesis of light-dependent magnetoreception, which is based on the assumption that the liquid crystals of retina pigments are very sensitive receptors of magnetic field and do not require the presence of magnetite crystals. We assume that the layer of retina pigment epithelium participates in the complex process of transformation of a light signal, which takes into account the influence of magnetic field but not simply absorbs light superfluous for photoreceptors. The changes in magnetic field cause a distortion of the liquid crystal line structure of the pigment, which results in the transformation of the light signal acting on the photoreceptors. Monochromatic red light in the same way deforms the response to the native magnetic signal.     

Evaluation of the effects of weak and moderate static magnetic fields on the characteristics of human low density lipoprotein in vitro

It has been suggested that exposure to electromagnetic fields may be a risk factor for cardiovascular disease in humans. Low density lipoprotein (LDL) modifications such as peroxidation and aggregation have been implicated in the pathogenesis of atherosclerosis. The present study investigated the effects of weak (0.125–0.5 mT) and moderate (1–4 mT) static magnetic fields (SMFs) on LDL oxidation, aggregation and zeta potential in vitro. Our results demonstrated that magnetic flux densities of 0.25 and 0.5 mT decreased, and magnetic flux densities of 3 and 4 mT increased the zeta potential and LDL oxidation in comparison with the control samples. All doses of SMFs increased the LDL aggregation in a time‐ and dose‐dependent manner. It is concluded that SMFs can alter the susceptibility of LDL to oxidation and this alteration is dependent on the applied magnetic flux density. The SMF, in addition to its role in the production and stabilization of free radicals and promotion of lipid peroxidation, may influence the metabolism of lipoproteins and their interaction with other molecules such as apolipoproteins, enzymes and receptors through the alteration of the LDL zeta potential and its particles tendency to aggregation. Bioelectromagnetics 34:397–404, 2013. © 2012 Wiley Periodicals, Inc.     

Effects of static magnetic fields on diffusion in solutions

Static magnetic fields affect the diffusion of biological particles in solutions through the Lorentz force and Maxwell stress. These effects were analyzed theoretically to estimate the threshold field strength for these effects. Our results show that the Lorentz force suppresses the diffusion of charged particles such as Na+, K+, Ca2+, Cl-, and plasma proteins. However, the threshold is so high, i.e., more than 10(4) T, that the Lorentz force does not affect the ion diffusion at typical field strengths (a few Tesla at most). Since the threshold of gradient fields for producing a change in ion diffusion through the Maxwell stress is more than 10(5) T2/m for paramagnetic molecules (FeCl3, O2) and plasma proteins, their diffusion would be unaffected by typical gradient fields (100 T2/m at most) and even by high gradient fields (less than 10(5) T2/m) used in magnetic separation techniques. In contrast, movement of deoxygenated erythrocytes and FeCl3 colloids (more than 10(3) molecules) is influenced by the usual gradient fields due to a volume effect.     

Metabolic effects of static magnetic fields on Streptococcus pyogenes

This study aimed to develop a simple experimental system utilising bacterial cells to investigate the dose responses resulting from exposures to static magnetic flux densities ranging from 0.05 to 0.5 T on viability, bacterial metabolism and levels of DNA damage in Streptococcus pyogenes. Exposure of S. pyogenes to a field of 0.3 T at 24 degrees C under anaerobic conditions resulted in a significant (P < 0.05) decrease in growth rate, with an increased mean generation time of 199 +/- 6 min compared to the control cells at 165 +/- 6 min (P < 0.05). Conversely, exposure to magnetic fields of 0.5 T significantly accelerated the growth rate at 24 degrees C compared to control cells, with a decreased mean generation time of 147 +/- 4 min (P < 0.05). The patterns of metabolite release from cells incubated in phosphate buffered saline (PBS) at 24 degrees C and exposed to different magnetic flux densities (0.05-0.5 T) were significantly (P < 0.05) altered, compared to non-exposed controls. Concentrations of metabolites, with the exception of aspartic acid (r = 0.44), were not linearly correlated with magnetic flux density, with all other r < 0.20. Instead, "window" effects were observed, with 0.25-0.3 T eliciting the maximal release of the majority of metabolites, suggesting that magnetic fields of these strengths had significant impacts on metabolic homeostasis in S. pyogenes. The exposure of cells to 0.3 T was also found to significantly reduce the yield of 8-hydroxyguanine in extracted DNA compared to controls, suggesting some possible anti-oxidant protection to S. pyogenes at this field strength.     

Effects of extremely weak alternating magnetic fields on the plant gravitropism

It was shown that the rate of gravitropic response in apical segments excised from the 4-day-old seedlings of flax (Linum bienne) may be substantially influenced by combined magnetic fields (CMF) of two different types: 1) CMF tuned to the parametric resonance for Ca2+; 2) CMF containing extremely weak alternating component with the values of magnetic density ranging from 10(-6) to 10(-10) T. Our experimental data indicate that CMF affect the gravitropic response via at least two different mechanisms. The first one corresponds to the ion parametric resonance well established earlier in studies with test-systems prepared from animals. The origin of the bioeffects induced by CMF containing extremely weak alternating component remains to be established.     

Effect of weak combined static and extremely low‐frequency alternating magnetic fields on tumor growth in mice inoculated with the Ehrlich ascites carcinoma

It has been shown that the ultralow‐frequency extremely weak alternating component of combined magnetic fields (MFs) exhibits a marked antitumor activity. The parameters of this component have been found (frequency 1, 4.4, 16.5 Hz or the sum of these frequencies; intensity 300, 100, 150–300 nT, respectively) at which this MF in combination with a collinear static MF of 42 µT inhibits or suppresses the growth of Ehrlich ascites carcinoma (EAC) in mice. It was shown that the exposure of mice with EAC to combined MFs causes structural changes in some organs (liver, adrenal glands), which are probably due to the total degradation of the tumor tissue. In mice with transplanted EAC, the tumor tissue after exposure to weak MFs was practically absent, as distinct from control animals in which the invasion of the tumor into the adipose tissue surrounding the kidneys, mesenteric lymph nodes, and spermatic appendages was observed. In animals without tumors, no pathological deviations from the norm in the structure of organs and tissues occurred after exposure to weak MF, indicating that this factor per se is not toxic to the organism. Bioelectromagnetics 30:343–351, 2009. © 2009 Wiley‐Liss, Inc.