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At least 1,081 records · Page 60Linked to original sources
PubMed2006

Extremely low frequency electromagnetic field exposure promotes differentiation of pituitary corticotrope-derived AtT20 D16V cells.

The pituitary corticotrope-derived AtT20 D16V cell line responds to nerve growth factor (NGF) by extending neurite-like processes and differentiating into neurosecretory-like cells. The aim of this work is the study of the effect of extremely low frequency electromagnetic fields (ELF-EMF) at a frequency of 50 Hz on these differentiation activities. To establish whether exposure to the field could influence the molecular biology of the cells, they were exposed to a magnetic flux density of 2 milli-Tesla (mT). Intracellular calcium ([Ca2+]i) and intracellular pH (pHi) were monitored in single exposed AtT20 D16V cells using fluorophores Indo-1 and SNARF for [Ca2+]i and pHi, respectively. Single-cell fluorescence microscopy showed a statistically significant increase in [Ca2+]i followed by a drop in pHi in exposed cells. Both scanning electron microscopy (SEM) and transmission microscopy of exposed AtT20 D16V cells show morphological changes in plasma membrane compared to non-exposed cells; this modification was accompanied by a rearrangement in actin filament distribution and the emergence of properties typical of peptidergic neuronal cells-the appearance of secretory-like granules in the cytosol and the increase of synaptophysin in synaptic vesicles, changes typical of neurosecretory-like cells. Using a monoclonal antibody toward the neurofilament protein NF-200 gave additional evidence that exposed cells were in an early stage of differentiation compared to control. Pre-treatment with 0.3 microM nifedipine, which specifically blocks L-type Ca2+ channels, prevented NF-200 expression in AtT20 D16V exposed cells. The above findings demonstrate that exposure to 50 Hz ELF-EMF is responsible for the premature differentiation in AtT20 D 16 V cells.

Actin Cytoskeleton↗
PubMed2005

Effects of time-variant extremely low-frequency (ELF) electromagnetic fields (EMF) on cholinesterase activity in Dictyostelium discoideum (Protista).

Recently, we detected propionylcholinesterase (PrChE) activity in single-cell amoebae of Dictyostelium discoideum using cytochemical, electrophoretic, and spectrophotometric methods. The involvement of this enzyme activity in cell-cell and cell-environment interactions was suggested. In this work, we found that exposure of single-cell amoebae to an extremely low-frequency electromagnetic fields (ELF-EMF) of 300 microT, 50 Hz, from 1 h up to 48 h at 21 +/- 1 degrees C affected PrChE activity.

Animals↗
PubMed2003

Modification of osteoarthritis by pulsed electromagnetic field--a morphological study.

OBJECTIVE: Hartley guinea pigs spontaneously develop arthritis that bears morphological, biochemical, and immunohistochemical similarities to human osteoarthritis. It is characterized by the appearance of superficial fibrillation by 12 months of age and severe cartilage lesions and eburnation by 18 months of age. This study examines the effect of treatment with a pulsed electromagnetic field (PEMF) upon the morphological progression of osteoarthritis in this animal model. DESIGN: Hartley guinea pigs were exposed to a specific PEMF for 1h/day for 6 months, beginning at 12 months of age. Control animals were treated identically, but without PEMF exposure. Tibial articular cartilage was examined with histological/histochemical grading of the severity of arthritis, by immunohistochemistry for cartilage neoepitopes, 3B3(-) and BC-13, reflecting enzymatic cleavage of aggrecan, and by immunoreactivity to collagenase (MMP-13) and stromelysin (MMP-3). Immunoreactivity to TGFbeta, interleukin (IL)-1beta, and IL receptor antagonist protein (IRAP) antibodies was examined to suggest possible mechanisms of PEMF activity. RESULTS: PEMF treatment preserves the morphology of articular cartilage and retards the development of osteoarthritic lesions. This observation is supported by a reduction in the cartilage neoepitopes, 3B3(-) and BC-13, and suppression of the matrix-degrading enzymes, collagenase and stromelysin. Cells immunopositive to IL-1 are decreased in number, while IRAP-positive cells are increased in response to treatment. PEMF treatment markedly increases the number of cells immunopositive to TGFbeta. CONCLUSIONS: Treatment with PEMF appears to be disease-modifying in this model of osteoarthritis. Since TGFbeta is believed to upregulate gene expression for aggrecan, downregulate matrix metalloprotease and IL-1 activity, and upregulate inhibitors of matrix metalloprotease, the stimulation of TGFbeta may be a mechanism through which PEMF favorably affects cartilage homeostasis.

Animals↗
PubMed2004

Electromagnetic fields and health effects--epidemiologic studies of cancer, diseases of the central nervous system and arrhythmia-related heart disease.

This epidemiologic investigation comprised separate studies of the risk of cancer, cause-specific mortality rates, risks for neurodegenerative diseases, and the risk of arrhythmia-related heart disease among employees exposed to extremely low-frequency (50-Hz) electromagnetic fields (EMF) in the Danish utility industry. All the employees in this industry were followed-up in several registers. The risk of disease was analyzed in relation to occupational exposure to EMF, latency, and duration of employment. A specific job-exposure matrix was developed and validated by comparison with direct measurements of EMF during a workday. Linkage with the Danish Cancer Register did not identify increased risks for the cancers suggested a priori to be associated with exposure to EMF, including leukemia, brain tumors, and breast cancer. Significantly increased risks for lung cancer and mesothelioma were identified for workers highly exposed to asbestos. Linkage with the National Mortality Register revealed a significantly increased overall mortality rate from amyotrophic lateral sclerosis (ALS), with an increasing trend with duration of employment and EMF exposure. In addition, a significantly increased mortality rate from electric accidents was observed. It was hypothesized that the observation of increased mortality from ALS was associated with exposure to EMF or electric shocks. No increased mortality rate from cardiovascular or cerebrovascular disease was observed. Linkage with the National Hospital Register also revealed an increased risk of ALS and, thereby confirmed the finding of an increased mortality rate for this disease in the previous study. Linkage of the cohort with the Multiple Sclerosis Register revealed an increased risk of multiple sclerosis, which was not, however, significant. Linkage with the Pacemaker Register showed no increased risk of severe arrhythmia-related heart disease. The second part of the study included the establishment of a large, nationwide cohort of mobile phone subscribers comprising some 420 000 persons. No increased risk was observed for the cancers considered a priori to be possibly associated with the radiofrequency fields emitted by mobile phones, which were brain tumors, including acoustic neuroma, salivary gland tumors, and leukemia. The data were analyzed by duration of phone use, latency, system used (NMT, GSM or both) and age at first subscription. A study of the incidence of ocular malignant melanoma in comparison with the annual increase among the mobile phone subscribers showed a highly stable incidence rate for this rare cancer in Denmark over close to 50 years of registration. On the basis of these studies and the scientific literature, it is concluded that occupational exposure to 50-Hz EMF is not associated with an increased risk of cancer, but that these fields, electric shocks, or some other unknown factor related to alternating current electricity may be associated with the risk of ALS. There is no clear evidence that 50-Hz EMF is associated with other neurodegenerative or cardiovascular diseases. At present, there is little, if any, evidence that the use of mobile phones is associated with cancer in adults, including brain tumors, acoustic neuroma, cancer of the salivary glands, leukemia, or malignant melanoma of the eye.

Adolescent↗
PubMed1985

The development and application of pulsed electromagnetic fields (PEMFs) for ununited fractures and arthrodeses.

This article deals with the rational and practical use of surgically noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited fractures, failed arthrodeses, and congenital pseudarthroses (infantile nonunions). The method is highly effective (more than 90 per cent success) in adult patients when used in conjunction with good management techniques that are founded on biomechanical principles. When union fails to occur with PEMFs alone after approximately four months, their proper use in conjunction with fresh bone grafts insures a maximum failure rate of 1 to 1.5 per cent. Union occurs because the weak electric currents induced in tissues by the time-varying fields effect calcification of the fibrocartilage in the fracture gap, thereby setting the stage for the final phases of fracture healing by endochondral ossification. The efficacy, safety, and simplicity of the method has prompted its use by the majority of orthopedic surgeons in this country. In patients with delayed union three to four months postfracture, PEMFs appear to be more successful and healing, generally, is more rapid than in patients managed by other conservative methods. For more challenging problems such as actively infected nonunions, multiple surgical failures, long-standing (for example, more than two years postfracture) atrophic lesions, failed knee arthrodeses after removal of infected prostheses, and congenital pseudarthroses, success can be expected in a large majority of patients in whom PEMFs are used. Finally, as laboratory studies have expanded knowledge of the mechanisms of PEMF action, it is clear that different pulses affect different biologic processes in different ways. Selection of the proper pulse for a given pathologic entity has begun to be governed by rational processes similar, in certain respects, to those applied to pharmacologic agents.

Arthrodesis↗
PubMed2003

[Protection against electromagnetic fields emitted by mobile phone facilities in Poland and the European Union countries].

In personal communication, the mobile phone systems have developed most rapidly. To enlarge the area of mobile phone availability one needs to fine a base antenna network. This means that the base antennas are closer and closer to people. Each antenna is the source of electromagnetic fields, and thus it has to be designed carefully with respect to public health. The standards are different for the general public and for occupational groups. In Polish standards, the limits for the frequency range of 0.3-300 GHz are expressed in power density with value of 0.1 W/m2. The EU standards are more sophisticated as they relate limit values to frequencies. This paper presents these values and other limits binding in the EU countries. Other limits are laid down for the population of workers. In this respect, there is a considerable discrepancy between the Polish and EU standards. The approach to standard setting is quite different. The Polish standards are exactly determined and very restrictive. They require from operators to take great care in establishing new base stations. The question whether the Polish standards should be compatible with the European Union standards remains still open. The EU regulations do not require any change in the standardization of member states if their standards prove to be more restrictive. From 1998, a tendency towards more restrictive limits, especially in respect to the general population, has been observed.

Cell Phone↗
PubMed1979

[Electromagnetic fields and alternating current, do they accelerate bone healing? (author's transl)].

The effects of combined treatment with electromagnetic fields and alternating current according to the method of Kraus is investigated in two groups at bone-nonunions of 21 beagle-dogs. Identical atrophic nonunions of both ulnae are stabilized with plates and treated electrically for eight weeks at one side only, the other side serves as control. The second group gets an additional cancellous bone graft. Qualitative and quantitative evaluation of X-rays and histology of undecalcified bone shows better bone healing in the group with cancellous bone graft on the treated side compared with the control. The first group shows no remarkable differences between both sides, except an increased periosteal bone formation around the active implants.

Animals↗
PubMed1998

Reversal of the bicycle drawing direction in Parkinson's disease by AC pulsed electromagnetic fields.

The Draw-a-Bicycle Test is employed in neuropsychological testing of cognitive skills since the bicycle design is widely known and also because of its complex structure. The Draw-a-Bicycle Test has been administered routinely to patients with Parkinson's disease (PD) and other neurodegenerative disorders to evaluate the effect of transcranial applications of AC pulsed electromagnetic fields (EMFs) in the picotesla flux density on visuoconstructional skills. A seminal observation is reported in 5 medicated PD patients who demonstrated reversal of spontaneous drawing direction of the bicycle after they received a series of transcranial treatments with AC pulsed EMFs. In 3 patients reversal of the bicycle drawing direction was observed shortly after the administration of pulsed EMFs while in 2 patients these changes were observed within a time lag ranging from several weeks to months. All patients also demonstrated a dramatic clinical response to the administration of EMFs. These findings are intriguing because changes in drawing direction do not occur spontaneously in normal individuals as a result of relateralization of cognitive functions. This report suggests that administration of AC pulsed EMFs may induce in some PD patients changes in hemispheric dominance during processing of a visuoconstructional task and that these changes may be predictive of a particularly favourable response to AC pulsed EMFs therapy.

Adult↗
PubMed1992

Dose-response implications of the transient nature of electromagnetic-field-induced bioeffects: theoretical hypotheses and predictions.

Data in the literature imply that the relationship between exposure and bio-effect involves more than a simple time integral of the field strength to which the living system has been subjected. Windows--ranges in which the system exhibits enhanced sensitivity--have been reported for power (or field strength), frequency, and the duration of the exposure. In this paper we show that such isolated window effects can be accounted for by recognizing the transient character of the response of the biological system. The principal assumption here is that the direct effect of the field is to increase the rates of production and degradation of mRNA or proteins. In this paper we review and extend the mathematical model that quantifies this. The model predicts that, for a given field strength, certain optimum relatively short duration exposures cause significantly larger bio-effects than exposure for much longer or much shorter times. The thinking embodied in the model should provide a framework for obtaining a meaningful working definition of "effective dose" and for predicting the response of subjects to environmental electromagnetic fields. It should help in deciding the relevant variables in the design and analysis of epidemiological studies.

Animals↗
PubMed2004

Quantum effects in the evolution of vortices in the electromagnetic field.

We analyze the influence of electron-positron pairs creation on the motion of vortex lines in electromagnetic field. In our approach the electric and magnetic fields satisfy nonlinear equations derived from the Euler-Heisenberg effective Lagrangian. We show that these nonlinearities may change the evolution of vortices.

Journal Article↗
PubMed2006

Exact analytical solution for the vector electromagnetic field of Gaussian, flattened Gaussian, and annular Gaussian laser modes.

The exact vector integral solution for all the electromagnetic field components of a general flattened Gaussian laser mode is derived by using the angular spectrum method. This solution includes the pure and annular Gaussian modes as special cases. The integrals are of the form of Gegenbauer's finite integral and are computed analytically for each case, yielding fields satisfying the Maxwell equations exactly in the form of quickly converging Fourier-Gegenbauer series.

Journal Article↗
PubMed1981

[Neurological status and EEG studies in workers exposed to electromagnetic fields of 27-30 MHz].

The studies covered 57 women who were heat sealing foil in exposure to electromagnetic radiation of 27--30 MHz frequencies, and 30 controls. In the clinical picture--neurotic syndrome predominated. Its form and prevalence did not differ from the control. No organic symptoms have been found in the nervous system of those exposed. In the EEG tests, changes in the bioelectric function of the brain did not exceed the allowable standard for healthy persons; on the other hand the decrease in alpha-waves index was significant.

Adult↗
PubMed1995

Reversal of visuospatial deficit on the Clock Drawing Test in Parkinson's disease by treatment with weak electromagnetic fields.

Visuospatial deficits are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Clinically, impairment of visuospatial functions may not be noted by Parkinsonian patients but may contribute to various functional disabilities including frequent falls, difficulties operating a vehicle, ambulating, and dressing. I have reported recently that treatment with external electromagnetic fields (EMFs) in the picotesla (pT) range intensity is an effective nonpharmacological modality in the management of the motor and various cognitive deficits of Parkinsonism including visuoperceptive and visuospatial functions. The present communication concerns four fully medicated Parkinsonian patients who, in response to treatment with EMFs, exhibited reversal of visuospatial impairments as demonstrated on the Clock Drawing Test. Specifically, prior to treatment with EMFs these patients demonstrated a visuospatial deficit which was evident by the placement of the numbers on the clock distant from the periphery. Following a series of treatments with EMFs this visuospatial deficit was corrected. The report supports prior observations demonstrating that externally applied pT range intensity EMFs may bring about reversal of visuospatial deficits in Parkinsonian patients which usually are not improved by treatment with dopaminergic or anticholinergic drugs.

Aged↗
PubMed1995

Resolution of dysarthria in multiple sclerosis by treatment with weak electromagnetic fields.

It has been reported that 50% or more of patients diagnosed with multiple sclerosis (MS) exhibit speech impairment (dysarthria) which in some cases can be exceedingly disabling. Currently there is no effective medical treatment for the dysarthria of MS which occurs as a result of lesions to the cerebellum and its outflow tracts. It was reported recently that extracranial application of brief AC pulsed electromagnetic fields (EMFs) in the picotesla (pT) range intensity produced in patients with MS sustained improvement in motor functions including cerebellar symptomatology. This communication concerns two MS patients with a chronic progressive course who exhibited severe dysarthria which improved already during the initial treatment with pulsed EMFs and which resolved completely 3-4 weeks later. Since application of EMFs has been shown to alter: (a) the resting membrane potential and synaptic neurotransmitter release through an effect involving changes in transmembrane calcium flux; and (b) the secretion of pineal melatonin which in turn influences the synthesis and release of serotonin (5-HT) and gamma-amino butyric acid (GABA) in the cerebellum, it is suggested that the immediate improvement of the dysarthria occurred as a result of changes in cerebellar neurotransmitter functions particularly 5-HT and GABA rather than from remyelination.

Brain↗
PubMed2003

Cardiac electrophysiology: theoretical considerations of a potential target for weak electromagnetic field effects.

With the widespread introduction of extra high voltage power transmission lines in the 1960s, and subsequent to early reports from Soviet Union scientists about health risks for transformer station personnel, public concern regarding the effects of electromagnetic fields (EMFs) on biological function has given rise to a large number of investigations and legislation to limit domestic and occupational exposure to EMFs. The underlying rationale for concern is related to the fact that living cells are electrically active, which makes them potentially vulnerable to electromagnetic interference. In the heart, electrical activity is crucial in coordinating the contraction of millions of cardiac cells, and disturbances in cardiac electrical activity, also known as arrhythmias, are often life threatening. Electrical fields induced in the heart by weak external EMFs (such as those encountered in a domestic setting) are understood to be at least 2 orders of magnitude smaller (< 1%) than those that occur naturally as an intrinsic consequence of cardiac activity. Using quantitative models of cardiac cellular electrophysiology, the effect of weak (1%) manipulation of key current mechanisms that give rise to the electrical activity of the heart is therefore assessed.

Animals↗
PubMed2000

Human sleep EEG under the influence of pulsed radio frequency electromagnetic fields. Results from polysomnographies using submaximal high power flux densities.

Former exploratory investigations of sleep alterations due to global system for mobile communications (GSM) signals have shown a hypnotic and REM-suppressive effect under field exposure. This effect was observed in a first study using a power flux density of 0.5 W/m(2), and the same trend occurred in a second study with a power flux density of 0.2 W/m(2). For the present study, we applied a submaximal power flux density of 50 W/m(2). To investigate putative effects of radio frequency electromagnetic fields (EMFs) of cellular GSM phones on human sleep EEG pattern, all-night polysomnographies of 20 healthy male subjects both with and without exposure to a circularly polarized EMF (900 MHz, pulsed with a frequency of 217 Hz, pulse duration 577 microseconds) were recorded. The results showed no significant effect of the field application either on conventional sleep parameters or on sleep EEG power spectra.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of electromagnetic fields on osteogenesis: an experimental study on rats].

The authors studied experimentally the electromagnetic pulsing field effects in an experimental model in rats, for evaluation of the velocity of consolidation of tibial and fibular fractures. The animals were followed for a period of three weeks under continuous stimulation and there were done radiological evaluation weekly and histological study at the end of the study. There were no histological, clinical or radiological differences between the group of rats submitted to electromagnetic pulsing fields and the control group.

Animals↗