Human breast carcinoma cells are induced to apoptosis by samsum ant venom through an IGF-1-dependant pathway, PI3K/AKT and ERK signaling

In the present study we evaluated the anti-tumor potential of samsum ant venom (SAV) from Pachycondyla sennaarensis on the human breast carcinoma cell line MCF-7. We found that SAV induced growth arrest of MCF-7 cells without affecting the viability of MCF-10 (non-tumorigenic normal breast epithelial cells) and normal PBMCs. We then analyzed its impact on IGF-1-mediated MCF-7 cell proliferation and its effect on the underlying IGF-1 signaling pathways. Using flow cytometry analysis, we showed that the percentage of apoptotic cells was fourfold higher in SAV-treated cells as compared to untreated cells. More importantly, treatment with SAV induced a marked reduction in actin polymerization and a subsequent marked reduction in IGF-1-mediated cell proliferation. In addition to growth-inhibitory and pro-apoptotic effects, significant reductions were also observed in the phosphorylation of AKT and ERK, but not p38MAPK, in SAV-treated cells as compared to untreated cells. Our data reveal unique anti-tumor effects of samsum ant venom.     

Pulsed Low-Frequency Magnetic Fields Induce Tumor Membrane Disruption and Altered Cell Viability

Tumor cells express a unique cell surface glycocalyx with upregulation of sulfated glycosaminoglycans and charged glycoproteins. Little is known about how electromagnetic fields interact with this layer, particularly with regard to harnessing unique properties for therapeutic benefit. We applied a pulsed 20-millitesla (mT) magnetic field with rate of rise (dB/dt) in the msec range to cultured tumor cells to assess whether this affects membrane integrity as measured using cytolytic assays. A 10-min exposure of A549 human lung cancer cells to sequential 50- and 385-Hz oscillating magnetic fields was sufficient to induce intracellular protease release, suggesting altered membrane integrity after the field exposure. Heparinase treatment, which digests anionic sulfated glycan polymers, before exposure rendered cells insensitive to this effect. We further examined a non-neoplastic human primary cell line (lung lymphatic endothelial cells) as a typical normal host cell from the lung cancer microenvironment and found no effect of field exposure on membrane integrity. The field exposure was also sufficient to alter proliferation of tumor cells in culture, but not that of normal lymphatic cells. Pulsed magnetic field exposure of human breast cancer cells that express a sialic-acid rich glycocalyx also induced protease release, and this was partially abrogated by sialidase pretreatment, which removes cell surface anionic sialic acid. Scanning electron microscopy showed that field exposure may induce unique membrane “rippling” along with nanoscale pores on A549 cells. These effects were caused by a short exposure to pulsed 20-mT magnetic fields, and future work may examine greater magnitude effects. The proof of concept herein points to a mechanistic basis for possible applications of pulsed magnetic fields in novel anticancer strategies.     

Effects of static magnetic field and pulsed electromagnetic field on viability of human chondrocytes in vitro

Effects of electromagnetic fields (EMFs) on human cell lines were described in numerous studies, but still many questions remain unanswered. Our experiment was designed with the aim of studying the effects of EMFs on the metabolic activity of chondrocytes in vitro. Human chondrocyte in vitro cultures, cultured in medium supplemented with 20 % fetal calf serum, were exposed to static magnetic field (SMF) (intensity of 0.6 T) and pulsed electromagnetic fields (PEMF) (21.2 MHz period of 15 ms, burst duration of 2 ms, amplification 3 dBm (0.1 V) and maximum output of 250 W) continually for 72 h. After the exposure, viability was determined using the MTT test and compared with a non-exposed control culture. As compared to the control sample the exposure to SMF resulted in a statistically significant increase (p 0.001) in viability. However, the increase of viability after PEMF exposure was not significant. This could be due to the frequency dependent effect on human cells. The experiments demonstrated that magnetic fields, using the above parameters, have a positive effect on the viability of human chondrocytes cultured in vitro.     

No effect of extremely low-frequency magnetic field observed on cell growth or initial response of cell proliferation in human cancer cell lines

An effect on the tumor promotion process, as represented by accelerated cell growth, has been indicated as one example of areas that demonstrate the possibility of biological effects of extremely-low frequency magnetic fields. We, therefore, exposed the five cell lines (HL-60, K-562, MCF-7, A-375, and H4) derived from human tumors to a magnetic field for 3 days to investigate the effects on cell growth. Prior to exposure or sham exposure, the cells were precultured for 2 days in low serum conditions. The number of growing cells was counted in a blind manner. To investigate the effect on the initial response of cell proliferation, two cell lines were synchronized in G1 phase by serum starvation and then exposed to a magnetic field for 18 h (H4 cells) or 24 h (MCF-7 cells), both with and without serum stimulation. The rate of DNA synthesis, taken as a measure of the cell proliferation, was determined by following the incorporation of [(3)H]-thymidine into the DNA. Three different magnetic field polarizations at both 50 and 60 Hz were used: linearly polarized (vertical); circularly polarized; and an elliptically polarized field. Magnetic field flux densities were set at 500, 100, 20 and 2 microT (rms) for the vertical field and at 500 microT (rms) for the rotating fields. No effect of magnetic field exposure was observed on either cell growth or the initial response of cell proliferation.     

1950 MHz射频电磁场对SRA01/04细胞周期和凋亡的影响

目的：研究显示射频电磁场与白内障的发生关系密切,为了评价晶状体上皮细胞在射频电磁场诱导的白内障发生中的作 用,本实验探讨了1950 MHz射频电磁场暴露对人眼晶状体上皮细胞株（SRA01/04）细胞周期与凋亡的影响。方法：将处于对数生 长期的SRA01/04 细胞暴露或假暴露于频率为1950 MHz,比吸收率（SAR）为2.79 W/kg 的射频电磁场中,每天暴露1 h,每周暴露 5 天,连续暴露4 周。暴露结束后立即收集细胞,显微镜下观察细胞形态变化,噻唑蓝（MTT）法检测细胞存活力,流式细胞仪 （FCM）检测细胞周期与凋亡。结果：与假辐照组相比,暴露组细胞形态未见明显变化;细胞存活力、细胞周期分布及细胞凋亡率亦 无显著改变（P>0.05）。结论：1950 MHz射频电磁场暴露4 周对SRA01/04 细胞的形态、活力、周期以及凋亡均无明显影响,提示在 本实验条件下1950 MHz 射频电磁场不会诱发白内障的发生。     

Low electromagnetic field (50 Hz) induces differentiation on primary human oral keratinocytes (HOK)

This work concerns the effect of low frequency electromagnetic fields (ELF) on biochemical properties of human oral keratinocytes (HOK). Cells exposed to a 2 mT, 50 Hz, magnetic field, showed by scanning electron microscopy (SEM) modification in shape and morphology; these modifications were also associated with different actin distribution, revealed by phalloidin fluorescence analysis. Moreover, exposed cells had a smaller clonogenic capacity, and decreased cellular growth. Indirect immunofluorescence with fluorescent antibodies against involucrin and beta-catenin, both differentiation and adhesion markers, revealed an increase in involucrin and beta-catenin expression. The advance in differentiation was confirmed by a decrease of expression of epidermal growth factor (EGF) receptor in exposed cells, supporting the idea that exposure to electromagnetic field carries keratinocytes to higher differentiation level. These observations support the hypothesis that 50 Hz electromagnetic fields may modify cell morphology and interfere in differentiation and cellular adhesion of normal keratinocytes.     

1950MHz射频电磁场对SRA01／04细胞周期和凋亡的影响

目的：研究显示射频电磁场与白内障的发生关系密切,为了评价晶状体上皮细胞在射频电磁场诱导的白内障发生中的作用,本实验探讨了1950MHz射频电磁场暴露对人眼晶状体上皮细胞株（SRA01／04）细胞周期与凋亡的影响。方法：将处于对数生长期的SRA01／04细胞暴露或假暴露于频率为1950MHz,比吸收率（SAR）为2．79W／kg的射频电磁场中,每天暴露1h,每周暴露5天,连续暴露4周。暴露结束后立即收集细胞,显微镜下观察细胞形态变化,噻唑蓝（MTT）法检测细胞存活力,流式细胞仪（FCM）检测细胞周期与凋亡。结果：与假辐照组相比,暴露组细胞形态未见明显变化;细胞存活力、细胞周期分布及细胞凋亡率亦无显著改变（P〉0．05）。结论：1950MHz射频电磁场暴露4周对SRA01／04细胞的形态、活力、周期以及凋亡均无明显影响,提示在本实验条件下1950MHz射频电磁场不会诱发白内障的发生。     

The differentiation of normal and transformed human fibroblasts in vitro is influenced by electromagnetic fields

We studied the effect of symmetric, biphasic sinusoidal electromagnetic fields (EMF) (20 Hz, 6 mT) on the differentiation of normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in in vitro cultures. Cells were exposed up to 21 days for 2 x 6 h per day to EMF. Normal mitotic human skin and lung fibroblasts could be induced to differentiate into postmitotic cells upon exposure to EMF. Concomitantly, the synthesis of total collagen as well as total cellular protein increased significantly by a factor of 5-13 in EMF-induced postmitotic cells. As analyzed by two-dimensional gel electrophoresis of [35S]methionine-labeled polypeptides, EMF-induced postmitotic cells express the same differentiation-dependent and cell type-specific marker proteins as their spontaneously arising counterparts. In SV40-transformed human lung fibroblasts (cell line WI38SV40) the exposure to EMF induced the differentiation of mitotic WI38SV40 cells into postmitotic and degenerating cells in subpopulations of WI38SV40 cell cultures. Other subpopulations of WI38SV40 cells did not show any effect of EMF on cell proliferation and differentiation. These results indicate that long-term EMF exposure of fibroblasts in vitro induces the differentiation of mitotic to postmitotic cells that are characterized by differentiation-specific proteins and differentiation-dependent enhanced metabolic activities.     

50 Hz sinusoidal magnetic fields do not affect human lymphocyte activation and proliferation in vitro

In the last 30 years, an increasing public concern about the possible harmful effects of electromagnetic fields generated by power lines and domestic appliances has pushed the scientific community to search for a correct and comprehensive answer to this problem. In this work the effects of exposure to 50 Hz sinusoidal magnetic fields, with a magnetic flux density of 0.05 mT and 2.5 mT (peak values), were studied on human peripheral blood mononuclear cells (PBMCs) collected from healthy young and elderly donors. Cell activation and proliferation were investigated by using flow cytometry techniques and 3H-TdR incorporation assays, respectively. The results obtained indicated that exposure to the fields altered neither DNA synthesis nor the capacity of lymphocytes to enter the activation phase and progress into the cell cycle. Thus, the conclusions are that two important functional phases of human lymphocytes, such as activation and proliferation, are not affected by exposures to 50 Hz magnetic fields similar to those found under power lines.     

Transient suppression of X-ray-induced apoptosis by exposure to power frequency magnetic fields in MCF-7 cells

Epidemiological studies suggest that exposure to power frequency magnetic fields may be a risk factor for breast cancer in humans. To study the relationship between exposure to 60-Hz magnetic fields (MFs) and breast cancer, cell cycle distribution, apoptosis, and the expression of related proteins (p21, Bax, and Bcl-2) were determined in MCF-7 cells following exposure to magnetic fields (60 Hz, 5 mT) alone or in combination with X rays. It was found that exposure of MCF-7 cells to 60-Hz MFs for 4, 8, and 24 h had no effect on cell cycle distribution. Furthermore, 60-Hz MFs failed to affect cell growth arrest and p21 expression induced by X rays (4 Gy). Similarly, 60-Hz MFs did not induce apoptosis or the expression of Bax and Bcl-2, two proteins related to apoptosis. However, exposure of cells to 60-Hz MFs for 24 h after irradiation by X rays (12 Gy) significantly decreased apoptosis and Bax expression but increased Bcl-2 expression. The effects of exposure to 60-Hz MFs on X-ray-induced apoptosis and Bax and Bcl-2 expressions were not observed at 72 h. These data suggest that exposure to 60-Hz MFs has no effects on the growth of MCF-7 cells, but it might transiently suppress X-ray-induced apoptosis through increasing the Bcl-2/Bax ratio.     

Human ASPM participates in spindle organisation, spindle orientation and cytokinesis

Background

For clinical applications of mesenchymal stem cells (MSCs), labeling and tracking is crucial to evaluate cell distribution and homing. Magnetic resonance imaging (MRI) has been successfully established detecting MSCs labeled with superparamagnetic particles of iron oxide (SPIO). Despite initial reports that labeling of MSCs with SPIO is safe without affecting the MSC's biology, recent studies report on influences of SPIO-labeling on metabolism and function of MSCs. Exposition of cells and tissues to high magnetic fields is the functional principle of MRI. In this study we established innovative labeling protocols for human MSCs using clinically established SPIO in combination with magnetic fields and investigated on functional effects (migration assays, quantification of colony forming units, analyses of gene and protein expression and analyses on the proliferation capacity, the viability and the differentiation potential) of magnetic fields on unlabeled and labeled human MSCs. To evaluate the imaging properties, quantification of the total iron load per cell (TIL), electron microscopy, and MRI at 3.0 T were performed.

Results

Human MSCs labeled with SPIO permanently exposed to magnetic fields arranged and grew according to the magnetic flux lines. Exposure of MSCs to magnetic fields after labeling with SPIO significantly enhanced the TIL compared to SPIO labeled MSCs without exposure to magnetic fields resulting in optimized imaging properties (detection limit: 1,000 MSCs). Concerning the TIL and the imaging properties, immediate exposition to magnetic fields after labeling was superior to exposition after 24 h. On functional level, exposition to magnetic fields inhibited the ability of colony formation of labeled MSCs and led to an enhanced expression of lipoprotein lipase and peroxisome proliferator-activated receptor-γ in labeled MSCs under adipogenic differentiation, and to a reduced expression of alkaline phosphatase in unlabeled MSCs under osteogenic differentiation as detected by qRT-PCR. Moreover, microarray analyses revealed that exposition of labeled MSCs to magnetic fields led to an up regulation of CD93 mRNA and cadherin 7 mRNA and to a down regulation of Zinc finger FYVE domain mRNA. Exposition of unlabeled MSCs to magnetic fields led to an up regulation of CD93 mRNA, lipocalin 6 mRNA, sialic acid acetylesterase mRNA, and olfactory receptor mRNA and to a down regulation of ubiquilin 1 mRNA. No influence of the exposition to magnetic fields could be observed on the migration capacity, the viability, the proliferation rate and the chondrogenic differentiation capacity of labeled or unlabeled MSCs.

Conclusions

In our study an innovative labeling protocol for tracking MSCs by MRI using SPIO in combination with magnetic fields was established. Both, SPIO and the static magnetic field were identified as independent factors which affect the functional biology of human MSCs. Further in vivo investigations are needed to elucidate the molecular mechanisms of the interaction of magnetic fields with stem cell biology.     

Combined DC and ELF magnetic fields can alter cell proliferation

Effects of extremely-low-frequency (ELF) electromagnetic fields on proliferation of rabbit-ligament fibroblasts were examined. Markedly different effects, ranging from inhibition to stimulation of proliferation, were obtained, depending on the signal parameters of amplitude, frequency, and DC magnetic field. These results demonstrate that simple, single-frequency signals can have dramatic effects on ligament cells, which may be useful for bioelectrical stimulation of growth and repair. Also, the range of frequencies examined in this study covered those commonly used in transmission of electrical energy (50 or 60 Hz), which indicates that further study of possible effects of exposure to fields generated by power transmission equipment is warranted.     

The differentiation of normal and transformed human fibroblasts in vitro is influenced by electromagnetic fields

We studied the effect of symmetric, biphasic sinusoidal electromagnetic fields (EMF) (20 Hz, 6 mT) on the differentiation of normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in in vitro cultures. Cells were exposed up to 21 days for 2 × 6 h per day to EMF. Normal mitotic human skin and lung fibroblasts could be induced to differentiate into postmitotic cells upon exposure to EMF. Concomitantly, the synthesis of total collagen as well as total cellular protein increased significantly by a factor of 5–13 in EMF-induced postmitotic cells. As analyzed by two-dimensional gel electrophoresis of [³⁵S]methionine-labeled polypeptides, EMF-induced postmitotic cells express the same differentiation-dependent and cell type-specific marker proteins as their spontaneously arising counterparts. In SV40-transformed human lung fibroblasts (cell line WI38SV40) the exposure to EMF induced the differentiation of mitotic WI38SV40 cells into postmitotic and degenerating cells in subpopulations of WI38SV40 cell cultures. Other subpopulations of WI38SV40 cells did not show any effect of EMF on cell proliferation and differentiation. These results indicate that long-term EMF exposure of fibroblasts in vitro induces the differentiation of mitotic to postmitotic cells that are characterized by differentiation-specific proteins and differentiation-dependent enhanced metabolic activities.     

No effect of pulsed electromagnetic fields on PC12 and HL-60 cells

The effect of pulsed electromagnetic fields (PEMF) similar to those used in transcranial magnetic stimulation (TMS) on two tumour cell lines, the human promyelocytic leukaemia cell line (HL-60) and the rat pheochromocytoma cell line (PC12), was investigated. The two cell lines were exposed to non-homogeneous pulsed electromagnetic fields (about 0.25–4.5 T peak magnetic field strength; 1–8 exponential pulses, 0.25 Hz) at different positions on the coil (2×25 mm). After exposure with various intensities, various numbers of pulses and at different coil positions, cell viability and the intracellular cyclic AMP content were determined in the two cell lines. Additionally, in HL-60 cells the intracellular Hsp72 content and in PC12 cells the release of the neurotransmitters dopamine, noradrenaline and acetylcholine were measured after PEMF treatment. The results of these analyses do not hint at alterations in the cell viability or in the content of cAMP, Hsp72, dopamine, noradrenaline, and acetylcholine in the two tumour cell lines after PEMF exposure under various conditions.     

Pulsed electromagnetic fields affect the intracellular calcium concentrations in human astrocytoma cells

Experiments assessed whether long term exposure to 50 Hz pulsed electromagnetic fields with a peak magnetic field of 3 mT can alter the dynamics of intracellular calcium in human astrocytoma U-373 MG cells. Pretreatment of cells with 1.2 microM substance P significantly increased the [Ca(2+)](i). The same effect was also observed when [Ca(2+)](i) was evaluated in the presence of 20 mM caffeine. After exposure to electromagnetic fields the basal [Ca(2+)](i) levels increased significantly from 143 +/- 46 nM to 278 +/- 125 nM. The increase was also evident after caffeine addition, but in cells treated with substance P and substance P + caffeine we observed a [Ca(2+)](i) decrease after exposure. When we substituted calcium-free medium for normal medium immediately before the [Ca(2+)](i) measurements, the [Ca(2+)](i) was similar to that measured in the presence of Ca(2+). In this case, after EMFs exposure of cells treated with substance P, the [Ca(2+)](i), measured without and with addition of caffeine, declined from 824 +/- 425 to 38 +/- 13 nM and from 1369 +/- 700 to 11 +/- 4 nM, respectively, indicating that electromagnetic fields act either on intracellular Ca(2+) stores or on the plasma membrane. Moreover the electromagnetic fields that affected [Ca(2+)](i) did not cause cell proliferation or cell death and the proliferation indexes remained unchanged after exposure.     

Influence of 864 MHz electromagnetic field on growth kinetics of established cell line

Considering often contradictory data on biological effects of mobile phones frequencies on established cell culture lines, our study aimed at evaluating the influence of 864 MHz electromagnetic field on proliferation, colony forming ability and viability of Chinese hamster lung cells continuous line V79. Prior to exposure for 1, 2 and 3 hours in transversal electromagnetic mode cell (TEM-cell) equipped by Philips PM 5508 signal generator cell samples were sub-cultivated for one day. Cell samples were exposed to 864 MHz continuous wave at an average specific absorption rate (SAR) of 0.08 W/kg. To determine cell growth, V79 cells were plated in concentration of 1 × 10⁴ cells per milliliter of nutrient medium RPMI 1640, and raised in a humified atmosphere at 37°C in 5% CO₂. Cell proliferation was determined by cell counts for each hour of exposure on post-exposure day 1, 2, 3, 4 and 5. To identify colony-forming ability, cells were cultivated in concentration of 40 cells/mL of RPMI 1640 and incubated according to the deliberated experimental protocol. Colony forming ability for each hour of exposure was defined by colony counts on experimental day 7. Trypan blue exclusion test was used to determine viability of cells. In comparison to sham-exposed cells, growth curve of irradiated cell samples showed significant decrease (p < 0.05) after 2 and 3 hours of exposure on experimental day 3, respectively. Both, the colony forming ability and viability of irradiated cells did not significantly differ from exposed “mock” condition. Under strictly controlled laboratory conditions, applied radiofrequency microwaves (RF/MW) irradiation significantly affected cell proliferation kinetics but not viability or ability of V79 cells to form colonies. Sophisticated mechanism of action is intending to be elucidated in the further research which will include insight into the RF/MW related event at the subcellular level.     

RECQL4-deficient cells are hypersensitive to oxidative stress/damage: Insights for osteosarcoma prevalence and heterogeneity in Rothmund-Thomson syndrome

Rothmund-Thomson syndrome (RTS) is a heterogeneous disease, associated with increased prevalence of osteosarcoma in very young patients with a mutated RECQL4 gene. In this study, we tested the ability of RECQL4 deficient fibroblasts, derived from a RTS patient to recover from hydrogen peroxide (H(2)O(2))-induced oxidative stress/damage. Immunoperoxidase staining for 8-oxo-deoxyguanosine (8-oxo-dG) formation in RTS and normal human fibroblasts were compared to assess DNA damage. We determined DNA synthesis, cell growth, cell cycle distribution, and viability in RTS and normal human fibroblasts before and after H(2)O(2) treatment. H(2)O(2) induces 8-oxo-dG formation in both RTS and normal fibroblasts. In normal human fibroblasts, RECQL4 was predominantly localized to cytoplasm; nuclear translocation and foci formation occurred in response to oxidant stimulation. After recovery from oxidant exposure, viable RTS fibroblasts showed irreversible growth arrest compared to normal fibroblasts. DNA synthesis decreased significantly in treated RTS cells, with concomitant reduction of cells in the S-phase. These results suggest that enhanced oxidant sensitivity in RECQL4 deficient fibroblasts derived from RTS patients could be attributed to abnormal DNA metabolism and proliferation failure. The ramifications of these findings on osteosarcoma prevalence and heterogeneity in RTS are discussed.     

In vitro effects of low frequency electromagnetic fields on osteoblast proliferation and maturation in an inflammatory environment

An in vitro model was set up to investigate the effects of low frequency pulsed electromagnetic fields (PEMF) and its induced electric fields on osteoblast cells under inflammatory conditions. Osteoblasts (7F2) were seeded on top of chitosan scaffolds and co-cultured with macrophage cells (RAW 264.7) growing on the bottom of culture wells, stimulated by lipopolysaccharide to release reactive oxygen species including nitric oxide (NO). The co-culture was exposed to PEMF (magnitude of the magnetic field = 1.5 mT; induced electric voltage = 2.5 mV; frequency = 75 Hz; pulse duration = 1.3 ms) for 9 h. The osteoblasts were examined for their proliferation, viability, alkaline phosphatase (ALP) activity, and genetic expressions of type I collagen (COL I) and osteocalcin (OC), immediately and 7 days after PEMF exposure (days 0 and 7). Macrophage cell viability and NO concentration in the medium were monitored before and after PEMF exposure. The PEMF-exposed co-culture released a significantly higher amount of NO (65 μM) compared to control (17 μM) on day 7. Despite the high level of NO in the medium that was reported to be cytotoxic, PEMF-exposed osteoblasts had enhanced cell proliferation (23%), viability (36%), and COL I mRNA expression (3.4-fold) compared to the controls. The osteoblasts subjected to the PEMF had 41% less ALP activity than the control, which was associated with the active cell proliferation and COL I expression. The expression of OC mRNA was not seen in either the PEMF or control group, indicating cells had not entered the mineralization stage by day 7.     

50 Hz magnetic field exposure alters onset of S-phase in normal human fibroblasts.

This study was undertaken to investigate whether power frequency magnetic fields can affect the kinetics of cell cycle progression in exposed human cells. To achieve this, cultures of normal human fibroblasts were synchronised in the G(0) phase of the cell cycle and exposed to 50 Hz magnetic fields at a range of flux densities. Progression through the cycle was monitored by examining the timing of entry into S phase, as characterised by the onset of DNA synthesis. Simultaneous positive controls were exposed to human recombinant fibroblast growth factor to demonstrate that the system was responsive to external stimuli. Exposure to magnetic fields at 20 and 200 microT induced a small but significant increase in the length of the G(1) phase of the cell cycle. However, exposure at higher flux densities of 2 and 20 mT had no significant effect. These results are discussed in relation to weak magnetic field effects on free radical concentration.     

Effects of extremely low-frequency pulsed electromagnetic fields on morphological and biochemical properties of human breast carcinoma cells (T47D)

This study was carried out to investigate the effects of 100 and 217 Hz extremely low-frequency pulsed electromagnetic fields (ELF-PEMF) on cell proliferation, actin reorganization, and ROS generation in a human breast carcinoma cells (T47D). Cells were exposed for 24–72 h, at 100 and 217 Hz, 0.1 mT. The treatment induced a time dependent decrease in cell growth after 72 h and revealed an increase in fluorescence intensity in cytoplasm and actin aggregations around the nucleus as detected by fluorescence microscopy. The amount of actin in T47D cells increased after 48 h exposure to 100 Hz and 24 h to 217 Hz while no changes in nuclear morphology were detected. Exposing the cells to 217 Hz for 72 h caused a dramatically increase of intracellular ROS generation while with exposure to 100 Hz it remained nearly unchanged. These results suggest that exposure to ELF-PEMF (100, 217 Hz, 0.1 mT) are able inducing an increase of actin level, its migration toward nucleus but despite of these changes and dramatically increase in ROS generation the symptoms of apoptosis were not observed. Our results support the hypothesis that cell response to EMF may only be observed at certain window effects; such as frequency and intensity of EMF parameters.