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At least 199 records · Page 11Linked to original sources
PubMed1991

Intervascular occlusion of canine renal, splenic, and vertebral arteries using electromagnetic field focusing (EFF) probe.

Electromagnetic field-focusing (EFF) probe is a precision surgical and interventional tool. Use of the device produces maximum temperature in excess of 1800 degrees C by convergence of radio-frequency (RF) induced eddy currents in biological tissues. Applications of the EFF probe in angioplasty, aneurysm thrombosis, and neurosurgery have been previously reported. In the present work, the EFF probe was guided under fluoroscopic control and used to occlude renal, splenic, and vertebral arteries in dogs. The occlusion was typically accomplished with about one minute of RF power application. Histology of the treated vessel three to six weeks posttreatment showed total occlusion consisting of intimal and subintimal changes and organized thrombus in the lumen. This suggests that the EFF probe in comparison with other procedures is an inexpensive, relatively safe precision interventional tool for performing an occlusion for experimental and therapeutic purposes.

Animals↗
PubMed2004

Evaluation of the electromagnetic field level emitted by medium frequency AM broadcast stations.

In order to estimate the level of the electromagnetic field produced by telecommunication systems, different computational techniques can be employed whose complexity depends on the accuracy of the final results. In this paper, we present the validation of a code based on the method of moments that allows us to analyse the electromagnetic field emitted by radio-communication systems operating at medium frequencies. The method is able to provide an accurate estimate of the levels of electromagnetic field produced by this type of device and, consequently, it can be used as a method for verifying the compliance of the system with the safe exposure level regulations and population protection laws. Some numerical and experimental results are shown relevant to an amplitude modulated (AM) radio transmitter, together with the results of a forthcoming system that will be operative in the near future.

Algorithms↗
PubMed1982

Treatment of therapeutically resistant non-unions with bone grafts and pulsing electromagnetic fields.

This study reviews the cases of eighty-three adults with ununited fractures who were treated concomitantly with bone-grafting and pulsed electromagnetic fields. An average of 1.5 years had elapsed since fracture and the use of this combined approach. Nearly one-third of the patients had a history of infection, and an average of 2.4 prior operations had failed to produce bone union. Thirty-eight patients who were initially treated with grafts and pulsed electromagnetic fields for ununited fractures with wide gaps, synovial pseudarthrosis, and malalignment achieved a rate of successful healing of 87 per cent. Forty-five patients who had initially been treated unsuccessfully with pulsing electromagnetic fields alone had bone-grafting and were re-treated with pulsing electromagnetic fields. Ninety-three per cent of these fractures healed. The residual failure rate after two therapeutic attempts, one of which was operative, was 1.5 per cent. The median time to union for both groups of patients was four months.

Adult↗
PubMed2003

About the biological effects of high and extremely high frequency electromagnetic fields.

This paper deals with the effects of high (microwave) and extremely high (millimetre waves, MMW) frequency electromagnetic fields on the membrane processes and ion channels, molecular complexes, excitable and other structures. Microwaves as well as millimetre waves are widely used in medical practice and in everyday life. The existence of interaction between the exogenous and endogenous electromagnetic fields with biological systems is now a subject of intense discussion. The most contentious question is the existence of a possible specific (non-thermal) effect of microwaves, unrelated to that caused by increased temperature. Although numerous data have been published on the possible non-thermal effects of the studied electromagnetic fields on different kinds of living systems, only little understanding is gained about the modes of microwave action. Here we review data, which provide evidence that non-thermal microwave effects do exist and may play a significant role. This evidence is based on research at all biological levels, from cell-free systems through cells, tissues and organs, to animal and human organisms.

Animals↗
PubMedDate not supplied

Biological effects of weak electromagnetic fields from 0 Hz to 200 MHz: a survey of the literature with special emphasis on possible magnetic resonance effects.

The literature on biological effects of weak electromagnetic fields of a frequency of 200 MHz or less is surveyed. The topic has been extraordinarily controversial, in part because of disputed assertions about a role for electromagnetic fields in carcinogenesis or production of abnormalities in growth and development. There is fairly widespread acceptance of certain beneficial effects, particularly the stimulation of healing. An increasing number of reports point to interactions between static magnetic fields and time-varying fields in the production of some effects. Safety implications are noted along with the hypothetical possibility of production of experimental artifacts by electromagnetic fields in MRS research.

Animals↗
PubMedDate not supplied

Bioeffects of weak electromagnetic fields.

Time varying magnetic fields are most often employed for therapeutic purposes and are present in environmental sources. In order for an electromagnetic field bioeffect to be possible, the signal parameters should not only satisfy the dielectric properties of the target, but also induce sufficient voltage to be detectable above thermal noise. The problem of the sensitivity of living cells and tissues is discussed in relation to signal/noise ratio at the target site. Some biophysical models for interactions of weak electromagnetic fields with biological systems are summarized. Cell studies and therapeutic application of electric and magnetic fields indicate that weak electromagnetic fields can have a profound effect on a large variety of biological systems.

Animals↗
PubMed2006

Do ambient electromagnetic fields affect behaviour? A demonstration of the relationship between geomagnetic storm activity and suicide.

The relationship between ambient electromagnetic fields and human mood and behaviour is of great public health interest. The relationship between Ap indices of geomagnetic storm activity and national suicide statistics for Australia from 1968 to 2002 was studied. Ap index data was normalised so as to be globally uniform and gave a measure of storm activity for each day. A geomagnetic storm event was defined as a day in which the Ap index was equal to or exceeded 100 nT. Suicide data was a national tally of daily male and female death figures where suicide had been documented as the cause of death. A total of 51 845 males and 16 327 females were included. The average number of suicides was greatest in spring for males and females, and lowest in autumn for males and summer for females. Suicide amongst females increased significantly in autumn during concurrent periods of geomagnetic storm activity (P = .01). This pattern was not observed in males (P = .16). This suggests that perturbations in ambient electromagnetic field activity impact behaviour in a clinically meaningful manner. The study furthermore raises issues regarding other sources of stray electromagnetic fields and their effect on mental health.

Age Distribution↗
PubMedDate not supplied

[Suppression of tumor immunity by electromagnetic fields and glucocorticoids in mice with implanted Ehrlich carcinoma].

INTRODUCTION: The immune system plays a major role in the origin, growth and evolution of tumors; factors that decrease the immune response in any way can cause higher tumor incidence and its faster or uncontrolled growth and evolution. MATERIAL AND METHODS: The research included 18 healthy male Han: NMRI mice, weighing between 25 and 30g, with ten-day-old tumor deposits, divided into three groups consisting of six mice each. The first group was continuously exposed to extremely low frequency electromagnetic fields (intensity 70-320 microT). The second group was treated with high doses of corticosteroids (dexamethasone). The control group was not treated with corticosteroids, nor was exposed to extremely low frequency electromagnetic fields. The exposure period lasted for ten days. The criteria used to evaluate tumor immunity were: histological findings of leukocyte infiltration around the tumor cells and white blood cell count. RESULTS: The control group presented with excellent immune response to tumor cells. Lymphoplasmacytic infiltrates widely surrounded the tumor. Numerous tumor cells showed signs of cell death. The results showed that exposure of animals to high doses of glucocorticoids resulted in extremely decreased leukocyte infiltration in the tumor tissue (single lymphocytes), while exposure to extremely low frequency electromagnetic fields significantly decreased leukocyte infiltration in comparison to the control group. Comparison of white blood cell count in treated groups revealed that the white blood cell count in both treated groups was decreased, compared with the control group. CONCLUSION: Extremely low frequency electromagnetic fields significantly suppress the immune response to tumor cells. Dexamethasone treatment resulted in almost complete absence of immune response to tumor cells. Electromagnetic fields and dexamethasone both decrease the white blood cell count.

Animals↗
PubMed2001

Investigation of brain potentials in sleeping humans exposed to the electromagnetic field of mobile phones.

An investigation was made of 8-hour EEG tracings of sleeping humans exposed to the electromagnetic field of a GSM-standard mobile phone. To analyze the EEG-patterns, manual scoring, nonlinear dynamics, and spectral analysis were employed. It was found that, when human beings were exposed to the electromagnetic field of a cellular phone, their cerebral cortex biopotentials revealed an increase in the alpha-range power density as compared to the placebo experiment. It was also found that the dimension of EEG correlation dynamics and the relation of sleep stages changed under the influence of the electromagnetic field of a mobile phone.

Adult↗
PubMed2004

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.

Actins↗
PubMed2002

Understanding conditions for which biological effects of nonionizing electromagnetic fields can be expected.

Scientific interest in the interaction of nonionizing electromagnetic fields with biological systems is longstanding, but often still controversial. Theories, models and computer simulations have usually emphasized physical interactions with subsystems (e.g. cell membranes) of a biological system. By extending this first necessary physical step to a second step of explicitly and quantitatively considering chemical changes, increased understanding appears possible. In the case of "strong fields", the role of field-altered chemistry is important to electrochemotherapy [Biochem. Pharmacol. 42, Suppl. (1991) 567] and creation of transdermal microconduits [Bioelectrochem. Bioenerg. 49 (1999) 11; J. Controlled Release 61 (1999) 185; J. Invest. Dermatol. 116 (2001) 40] For "weak fields" (a topic with much more controversy) consideration of chemical change shows that organized multicellular systems can be understood to respond to extremely small electric [Chaos 8 (1998) 576] or magnetic fields [Nature 405 (2000) 707]. In contrast, isolated individual cells interacting via voltage-gated channels [Proc. Natl. Acad. Sci. 92 (1995) 3740; Biophys. J. 75 (1998) 2251; Bioelectromagnetics 20 (1999) 102], or processes without "temperature compensation" [Biophys. J. 76 (1999) 3026], appear implausible. Satisfactory understanding is likely only if experimental and theoretical work is reconciled, which should therefore be emphasized. The interaction of electromagnetic fields with biological systems is of interest because of fundamental scientific curiosity, potential medical benefits and possible human health hazards.

Animals↗
PubMed2006

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 (2x25 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.

Acetylcholine↗
PubMedDate not supplied

[Experimental data on extremely low frequency (ELF) electromagnetic fields].

At the current state of knowledge, the biological effects both in vitro and in vivo connected to low frequency electromagnetic fields (ELF) are not univocally interpreted. Indeed a lot of literature seems strictly related to the particular experimental procedure depending both on the biological target and the exposure features under consideration. The best studied biological parameters in vitro are kinetics of cell proliferation, change in enzymatic activities, intramembrane ionic flux and integrity of chromosome complement. In general, the study on genotoxic effects induced by simultaneous exposure to electromagnetic fields and known chemical or physical mutagenes is based on the theory that electromagnetic fields may interfere with mutagenic substances rather than affect directly genetic material. In addition, studies in vivo confirm different results both in different animal species and in different (nervous, neuroendocrine, immunitary systems). Finally, in order to evaluate the wide research activity on this subject, we need to take into account the main standard criteria adopted by the world scientific community, such as the peer review process and the confirmation of experimental data by means of independent repetitions.

Animals↗
PubMedDate not supplied

[Mechanism of the effect of weak electromagnetic fields on the living body].

By using the model conceptions of the dielectric polarization theory, a new mechanism for the effect of electromagnetic field was proposed. The model enables one to explain the experimentally observed influence of low-frequency weak electromagnetic field on biological objects. It was shown that, at the cellular and subcellular levels, an increase in the intensity of the electric component of external electromagnetic field can occur. The magnitude of this increase is determined by the ratio of the contributions of the medium polarization and the depolarizing factor (which depends on body shape) to the total effect. As a result of this increase, a potential comparable with intrinsic biological values can be generated on neuron membranes, which must elicit nervous and physiological responses of the organism.

Animals↗
PubMed1988

Exposure to low-frequency electromagnetic fields--a health hazard?

Several epidemiologic studies indicate an association between exposure to low-frequency electromagnetic fields and certain types of cancer. However, there is no solid evidence from current experimental studies to support the hypothesis of carcinogenicity. Further research is needed, and in the present extended abstract Swedish epidemiologic studies projected for the future are briefly outlined. The studies will be time-consuming and will involve high costs. However, we anticipate that within the next four years the approach described will contribute significantly to knowledge about the possible health hazards caused by electromagnetic fields.

Adult↗
PubMed1995

Exposure to extremely low frequency electromagnetic fields and the risk of malignant diseases--an evaluation of epidemiological and experimental findings.

Epidemiological and experimental studies concerning extremely low frequency electromagnetic field exposure and malignant diseases published up to 1 July 1994 were evaluated to assess the possible carcinogenicity of electromagnetic fields and the scientific basis for environmental and occupational standard setting. We concluded that there are possible associations between (i) an increased risk of leukaemia in children and the existence of, or distance to, power lines in the vicinity of their residence, (ii) an increased risk of chronic lymphatic leukaemia and occupational exposure to low frequency electromagnetic fields and (iii) an increased risk of breast cancer, malignant melanoma of the skin, nervous system tumours, non-Hodgkin lymphoma, acute lymphatic leukaemia or acute myeloid leukaemia and certain occupations. There is no scientific basis for occupational or environmental standard setting for low frequency electric or magnetic fields.

Adult↗
PubMed1984

Treatment of congenital and infantile pseudarthrosis of the tibia with pulsing electromagnetic fields.

The management of congenital and infantile pseudarthrosis of the tibia poses difficult problems because of the variability in the type and prognosis of the lesion and varied response to surgical treatment. Whatever the severity of the lesion, the use of pulsed electromagnetic fields can be expected to improve the prognosis for union by a factor of at least 20 per cent. In a very few patients, usually those with pseudarthrosis presenting later in life, pulsed electromagnetic fields alone together with plaster immobilization may be sufficient to produce union. In some, partially successful previous surgery may be made completely successful by subsequent application of pulsed electromagnetic fields. In patients with a fair or good prognosis as regards the type of lesion, a combination of surgery and pulsed electromagnetic treatment, some period of which may also be given before surgical treatment, gives a moderately high rate of success. In the three groups already described, the overall success rate is likely to be more than 70 per cent. In lesions with a poor prognosis, or after multiple surgical procedures in an older child, a combination of very adequate further surgery and pulsed electromagnetic fields can produce union in perhaps 30 per cent of cases, but it is unwise to commence any treatment if the limb is already unacceptably short, if there is gross wasting of the limb with evidence of inadequate vascular supply, and/or if the joints of the foot and ankle are stiff and associated with deformity. In such cases, the procedure of choice is amputation.

Adolescent↗