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At least 1,027 records · Page 57Linked to original sources
PubMed2005

50-Hz extremely low frequency electromagnetic fields enhance cell proliferation and DNA damage: possible involvement of a redox mechanism.

HL-60 leukemia cells, Rat-1 fibroblasts and WI-38 diploid fibroblasts were exposed for 24-72 h to 0.5-1.0-mT 50-Hz extremely low frequency electromagnetic field (ELF-EMF). This treatment induced a dose-dependent increase in the proliferation rate of all cell types, namely about 30% increase of cell proliferation after 72-h exposure to 1.0 mT. This was accompanied by increased percentage of cells in the S-phase after 12- and 48-h exposure. The ability of ELF-EMF to induce DNA damage was also investigated by measuring DNA strand breaks. A dose-dependent increase in DNA damage was observed in all cell lines, with two peaks occurring at 24 and 72 h. A similar pattern of DNA damage was observed by measuring formation of 8-OHdG adducts. The effects of ELF-EMF on cell proliferation and DNA damage were prevented by pretreatment of cells with an antioxidant like alpha-tocopherol, suggesting that redox reactions were involved. Accordingly, Rat-1 fibroblasts that had been exposed to ELF-EMF for 3 or 24 h exhibited a significant increase in dichlorofluorescein-detectable reactive oxygen species, which was blunted by alpha-tocopherol pretreatment. Cells exposed to ELF-EMF and examined as early as 6 h after treatment initiation also exhibited modifications of NF kappa B-related proteins (p65-p50 and I kappa B alpha), which were suggestive of increased formation of p65-p50 or p65-p65 active forms, a process usually attributed to redox reactions. These results suggest that ELF-EMF influence proliferation and DNA damage in both normal and tumor cells through the action of free radical species. This information may be of value for appraising the pathophysiologic consequences of an exposure to ELF-EMF.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Effect of electromagnetic fields emitted by cellular phones on the latency of evoked electrodermal activity.

The widespread use of cellular phones raises the question of their possible adverse biological effects, especially on the central nervous system (CNS). Therefore, the authors examined the effect of electromagnetic fields emitted by cellular phones (CPEMFs) on the evoked neuronal activity of CNS relating to generation and representation of electrodermal activity (EDA), an index of sympathetic nervous system activity. EDA (skin resistance response; SRR) latency was lengthened approximately 200 ms with CPEMFs exposure irrespective of the head site next to mobile phone used. Hemispheric asymmetry of EDA-2 pathway, which is represented by shorter SRR latency in the right hand of the right hand responders, was also distorted with CPEMFs. Because the CNS regions including EDA-2 are also involved in tasks of motor timing and time estimation, delayed response in this neuronal network due to CPEMFs exposure may increase the response time of mobile phone users. Therefore, the findings point to the potential risks of mobile phones on the function of CNS and consequently, possible increase in the risk of phone-related driving hazards.

Adult↗
PubMed1995

Long term beneficial effects of weak electromagnetic fields in multiple sclerosis.

A 39 year-old severely disabled woman with a 19 year history of chronic relapsing-remitting multiple sclerosis (MS) began to experience improvement in symptoms within 24 hours after she received experimental treatment with picotesla electromagnetic fields (EMFs). Pattern reversal visual evoked potential (VEP) study obtained three weeks after the initiation of the first magnetic treatment showed a return to normal of the P100 latencies in each eye. The patient continued to receive 1-2 EMFs treatments per week and during the following 32 months she made a dramatic recovery with resolution of diplopia, blurring of vision, dysarthria, ataxia of gait, and bladder dysfunction as well as improvement in fatigue, heat tolerance, mood, sleep, libido, and cognitive functions. VEP studies, which were repeated in April of 1995 more than 2 1/2 years after the initiation of magnetic treatment, showed that P100 latencies remained normal in each eye providing objective documentation that continued application of these EMFs may sustain normal conduction in the damaged optic pathways over a long period of time. This is the first case report documenting the dramatic long term beneficial effects of treatment with picotesla range EMFs in a patient with MS.

Adult↗
PubMed2006

Effects of electromagnetic field on the batch cultivation and nutritional composition of Spirulina platensis in an air-lift photobioreactor.

Spirulina platensis was batch cultivated in a novel 3.5l magnetic air-lift photobioreactor with external-loop on which 0-0.55 T electromagnetic field (EMF) was imposed to investigate the EMF effects on the algal growth and nutrition composition. At the same time, the correlative mechanism was discussed mainly based on C, N, P uptake. It was found that, EMF has double-side effects on S. platensis cultivation depend on EMF intensity. 0.25 T EMF stress was found to be suitable for the algal cultivation enhancement increasing the maximum cell dry weight by 22% in a time period two days less than that of the control at 35 degrees C and 252 micromol photonsm(-2)S(-1). In addition, the nutritional composition of S. platensis was improved in both essential amino acids such as histidine and trace elements Ni, Sr, Cu, Mg, Fe, Mn, Ca, Co and V. It was suggested it was possible to optimize the cultivation process of S. platensis by imposing suitable weak EMF which may enhance the nutrition assimilation e.g. C, N, P and minerals by S. platensis.

Amino Acids↗
PubMed2003

Universality of electromagnetic-field correlations within homogeneous and isotropic sources.

We investigate the structure of second-order correlations in electromagnetic fields produced by statistically stationary, homogeneous, and isotropic current distributions. We show that the coherence properties of such fields within a low-loss or nondissipative medium do not depend on the source characteristics, but are solely determined by the propagation properties, and that the degree of coherence of the field is given by the sinc law. Our analysis reproduces the known results for blackbody fields, but it applies to a wider class of sources, not necessarily in thermal equilibrium. We discuss the physics behind the universal behavior of the correlations by comparing the results with those obtained by an electromagnetic plane-wave model.

Journal Article↗
PubMed2003

Spatial relationships in electrostimulation: application to electromagnetic field standards.

Spatial relationships in electrostimulation are examined with a myelinated nerve model. Excitation thresholds are determined for: 1) terminated axon within a locally constant electric field; 2) bent axon within a locally constant field; and 3) a field of finite extent over the affected axon. For application to electromagnetic field standards, the minimum excitation threshold of the in situ electric field applies to a straight, terminated axon; a field measurement averaging distance of 5 mm is recommended.

Action Potentials↗
PubMed2002

Precision measurement of the electromagnetic fields in the focal region of a high-numerical-aperture lens using a tapered fiber probe.

We present a measurement of the intensity around the focus of a N.A.-0.95 lens using a tapered optical fiber probe. An asymmetry introduced by the vector nature of the incident polarized light is evident, although it is inconsistent with that predicted theoretically by considering the magnitude squared of the electric field. The sensitivity of the probe to different components of the electromagnetic field is considered, and it is shown that the measurement is consistent with vector diffraction theory when the probe properties are taken into account.

Journal Article↗
PubMed1998

Effects of extremely low frequency electromagnetic field (EMF) on collagen type I mRNA expression and extracellular matrix synthesis of human osteoblastic cells.

Human osteoblastic cells were grown in a three-dimensional (3-D) cell culture model and used to test the effects of a 20 Hz sinusoidal electromagnetic field (EMF; 6 mT and 113 mV/cm max) on collagen type I mRNA expression and extracellular matrix formation in comparison with the effects of growth factors. The cells were isolated from trabecular bone of a healthy individual (HO-197) and from a patient presenting with myositis ossificans (MO-192) and grown in a collagenous sponge-like substrate. Maximal enhancement of collagen type I expression after EMF treatment was 3.7-fold in HO-197 cells and 5.4-fold in MO-192 cells. Similar enhancement was found after transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) treatment. Combined treatment of the cells with EMF and the two growth factors TGF-beta and IGF-I did not act synergistically. MO-192 cells produced an osteoblast-characteristic extracellular matrix containing collagen type I, alkaline phosphatase, and osteocalcin, together with collagen type III, TP-1, and TP-3, two epitopes of an osteoblastic differentiation marker. The data suggest that the effects of EMFs on osteoblastic differentiation are comparable to those of TGF-beta and IGF-I. We conclude that EMF effects in the treatment of skeletal disorders and in orthopedic adjuvant therapy are mediated via enhancement of collagen type I mRNA expression, which may lead to extensive extracellular matrix synthesis.

Cell Line↗
PubMed1996

Nonionizing electromagnetic fields and cancer: a review.

Low-frequency electromagnetic radiation had previously been thought to cause human injury only by generation of excess heat or by shock from direct contact with electric current. Information accumulating over the past few decades, however, suggests that nonionizing electric and magnetic fields associated with this radiation may be an environmental etiology in human disease. Human beings are affected not only by natural background nonionizing electromagnetic fields produced by the Earth, but also by a host of manmade sources. Of the diseases believed related to these fields, cancer and participation of these fields in the carcinogenic process have received considerable attention. This paper is a review of the basic science that points to this possible association.

Animals↗
PubMedDate not supplied

Spine fusion for discogenic low back pain: outcomes in patients treated with or without pulsed electromagnetic field stimulation.

Sixty-one randomly selected patients who underwent lumbar fusion surgeries for discogenic low back pain between 1987 and 1994 were retrospectively studied. All patients had failed to respond to preoperative conservative treatments. Forty-two patients received adjunctive therapy with pulsed electromagnetic field (PEMF) stimulation, and 19 patients received no electrical stimulation of any kind. Average follow-up time was 15.6 months postoperatively. Fusion succeeded in 97.6% of the PEMF group and in 52.6% of the unstimulated group (P < .001). The observed agreement between clinical and radiographic outcome was 75%. The use of PEMF stimulation enhances bony bridging in lumbar spinal fusions. Successful fusion underlies a good clinical outcome in patients with discogenic low back pain.

Adult↗
PubMed1992

The evaluation of biological efficiency of electromagnetic fields generated by implanted radiotelemetric transmitters used in space research on animals.

The study was carried out in 50 male rats abdominally implanted with biotelemetric systems (BTS) or mock-up. The animals were provided with 12/12 light/dark schedule during 6-week experiment. The electromagnetic field (EMF) frequency was 455 kHz, magnetic induction near transducer was about 10(-2) mT. Circadian rhythm of the body temperature and locomotor activity was controlled in course of the experiment. The latter been finished, some tissues and the blood of the animals have been sampled to test corticosterone, testosterone, T3, T4 level in serum with radioimmunoassay and membrane permeability for Ca2+, Na+, K(+)-ATPase activity and charge changes in liver microsomes was detected. The probable ways of the EMF influence on whole body are discussed.

Animals↗