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At least 433 records · Page 24Linked to original sources
PubMed2001

[Effects of low-frequency pulsed electromagnetic fields on the proliferation of chondrocytes].

Chondrocytes isolated from the human cartilage of 5 patients between the ages 23 and 56 were exposed to low frequency pulsed electromagnetic fields (9 mT; 3 Hz) for a daily period of 60 minutes on 5 consecutive days and then every 48 hours for the next 6 days (11 days in total). Cell viability was estimated using trypan blue exclusion and proliferation was estimated by counting the cells in a haemacytometer. Cell morphology was compared for control purposes by directly observing the cells under a light microscope after staining cells in a haematoxylin and eosin solution. The results were statistically analysed and compared to a control sample. Data revealed that exposing cells isolated from human cartilage to pulsed electromagnetic fields (9 mT; 3 Hz) led to a significantly higher number of cells in comparison to the control sample. Among the cells from the 5 patients, growth varied between 1.1 to 3.0 folds compared to the control sample. The difference in cell viability between the exposed cells and the control sample was, however, not significant. Some morphological variations were revealed when the cells were observed under a light microscope. The exposed cells were thinner and longer than the control cells which were large and flat. The exposed cells tended to grow in a more uniform direction while the control cells grew in all directions. These differences in morphology and growth may be related to the higher density of the exposed cells.

Adult↗
PubMed2006

Electromagnetic fields: principles of exposure mitigation.

Basic principles of reducing exposure to electromagnetic fields are reviewed in this article. Measures to reduce exposure can be divided into organisational/administrative and technical/engineering actions. Both strategies are briefly analysed and the basic principles of the theory of shielding are presented. A definition of shielding effectiveness (SE) is given, and the results from the general Transmission Lines Theory are presented. Practical situations of shielding static and time-varying electric and magnetic fields are discussed on the basis of the physical properties of the fields and of the shield.

Electric Conductivity↗
PubMed2000

Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study.

OBJECTIVE: To examine mortality from suicide in relation to estimated exposure to extremely low-frequency electromagnetic fields in a cohort of 138,905 male electric utility workers. METHODS: Case-control sampling, which included 536 deaths from suicide and 5, 348 eligible controls. Exposure was classified based on work in the most common jobs with increased exposure to magnetic fields and indices of cumulative exposure to magnetic fields based on a measurement survey. RESULTS: Suicide mortality was increased relative to work in exposed jobs and with indices of exposure to magnetic fields. Increased odds ratios (ORs) were found for years of employment as an electrician (OR, 2.18; 95% confidence interval [CI], 1.25-3.80) or line worker (OR, 1.59; 95% CI, 1.18-2.14), whereas a decreased OR was found for power plant operators (OR, 0.67; 95% CI, 0.33-1.40). A dose-response gradient with exposure to magnetic fields was found for exposure in the previous year, with a mortality OR of 1.70 (95% CI, 1.00-2.90) in the highest exposure category. Stronger associations, with ORs in the range of 2.12 to 3.62, were found for men younger than 50 years. CONCLUSIONS: These data provide evidence for an association between occupational electromagnetic fields and suicide that warrants further evaluation. A plausible mechanism related to melatonin and depression provides a direction for additional laboratory research and epidemiologic evaluation.

Adult↗
PubMed2000

Prediction of electromagnetic field distributions inside biological bodies by using an inverse scattering procedure based on a statistical cooling algorithm.

This paper presents an inverse scattering procedure based on a statistical cooling algorithm to predict the electromagnetic field inside a biological body. By knowing only the scattered electric field distribution in a set of observation points external to the biological model, this method seems to be able to predict the electromagnetic field distributions in the investigation domain, minimizing a suitable cost function. To this end, a numerical statistical procedure is used, which allows to treat functions with a large number of unknowns in an efficient manner and to exploit the so called a priori knowledge in the reconstruction process. Some preliminary results are reported, concerning simplified biological geometries, which clearly show the capabilities and effectiveness, and also the current limitations of the proposed approach. Finally, further advances for the proposed imaging technique are indicated and discussed.

Algorithms↗
PubMed2005

Impact of electromagnetic field exposure limits in Europe: is the future of interventional MRI safe?

The European Union (EU) has recently introduced a directive that aims to protect workers from adverse effects of exposure to electromagnetic fields. All countries within the EU are required to incorporate this directive into their national law by 2008. This legislation applies to all types of occupational exposure to electromagnetic fields with frequencies from 0 Hz to 300 GHz. It has dramatic implications for interventional magnetic resonance (MR) imaging, because workers who are close to the MR scanner while scanning is taking place are exposed at levels substantially above the exposure limits. This is especially the case for time-varying magnetic fields in the 110 Hz-5 kHz range, which includes the field from the imaging gradients. In this article, the scientific evidence on which the limits are based is brought into question. It is concluded that an urgent review of the directive is required and that more research, especially at MR gradient frequencies, is needed.

Electromagnetic Fields↗
PubMed1983

The use of pulsing electromagnetic fields to achieve arthrodesis of the knee following failed total knee arthroplasty. A preliminary report.

Treatment with pulsing electromagnetic fields was used as an adjunct in twenty patients who had had a knee arthrodesis after failure of a total joint arthroplasty. Eighteen had had an infected arthroplasty; one, mechanical loosening; and one, recurrent dislocation. Arthrodesis had been attempted twenty-five times in these twenty patients prior to application of the coils. These procedures included the use of twenty-two external fixation frames, one compression plate, one intramedullary rod, and one cylinder cast. Two groups of patients were identified: those with non-union and those with delayed union. Fourteen patients began treatment six months or more after arthrodesis and were considered to have a non-union. The other six patients started treatment less than six months after attempted arthrodesis because there was no evidence of progression toward union. They were considered to have delayed union. In seventeen (85 per cent) of the twenty patients a clinically solid arthrodesis with roentgenographic evidence of bone-bridging was achieved. The average time to union after coil therapy was started was 5.8 months, with a range of three to twelve months. The patients who started coil treatment earlier after arthrodesis showed a tendency to heal faster. The three patients who had failures were the only ones who did not adhere to the protocol, and all three were in the non-union group. All patients with a solid arthrodesis were free of pain and able to walk at the time of follow-up, nine to thirty-one months after the completion of treatment. The use of pulsing electromagnetic fields appears to be a valuable non-invasive adjunct when performing arthrodesis of the knee after failed total joint arthroplasty.

Adult↗
PubMed1997

Influence of extremely low frequency electromagnetic fields on the swimming behavior of ciliates.

Different species of ciliates (Paramecium biaurelia, Loxodes striatus, Tetrahymena thermophila) have been taken as model systems to study the effects of extremely low-frequency electromagnetic fields (50 Hz, 0.5-2.0 mT) on the cellular level. A dose-dependent increase in the mean swimming velocity and a decrease in the linearity of cell tracks were observed in all wild-type cells. In contrast, field-exposure did not increase the number of directional turns of the Paramecium tetraurelia pawn mutant (d4-500r), which is characterized by defective Ca2+-channels. The described changes indicate a direct effect of low frequency electromagnetic fields on the transport mechanisms of the cell membrane for ions controlling the motile activity of cilia.

Animals↗
PubMed2006

Linear and angular coherence momenta in the classical second-order coherence theory of vector electromagnetic fields.

A new concept of vector and tensor densities is introduced into the general coherence theory of vector electromagnetic fields that is based on energy and energy-flow coherence tensors. Related coherence conservation laws are presented in the form of continuity equations that provide new insights into the propagation of second-order correlation tensors associated with stationary random classical electromagnetic fields.

Journal Article↗
PubMed2001

The efficacy of ununited tibial fracture treatment using pulsing electromagnetic fields: relation to biological activity on nonunion bone ends.

Thirty ununited tibial fractures with a median time since injury of 18+/-9 months were treated by electrical stimulation using pulsing electromagnetic field therapy. Union was achieved in 25 cases (83.3%) in a median interval of 8.6+/-3.2 months. Patient age and gender, the presence of surgical hardware, length of disability, and the number of surgical procedures did not affect the outcome. Ununited fractures that appeared to be hypertrophic or sclerotic type radiographically, indicating a good blood supply to the bone ends, all healed. Treatment failures occurred only among lesions with a poor blood supply, and in necrotic or defective radiopraphic types. Pulsing electromagnetic field therapy is an effective treatment for ununited tibial fractures with good blood supply to the bone ends.

Adult↗
PubMedDate not supplied

[Effect of electromagnetic fields on movement of microorganisms].

Relationships between the motor activity and orientation of microorganisms and parameters of the electromagnetic field and of the microorganisms themselves were investigated. It has been shown that the type of microorganism and field amplitude produces the strongest influence on the behaviour of microorganisms in the fields. Theoretical relationships of the value of rotating moment and the field parameters, microorganism and environment were obtained. The results of the experiments well agree with the theory.

Cell Movement↗
PubMed1998

[Health Council Report 'Radiofrequency electromagnetic fields (300 Hz-300 GHz). The Health Council of the Netherlands].

The Health Council of the Netherlands in 1997 issued a report updating the guidelines for maximum acceptable exposure to radiofrequency electromagnetic fields formulated in 1975. The new recommendations are based on thermal effects for frequencies over 10 MHz. The committee considers the results of studies indicating non-thermal effects such as direct damage to DNA, not reliable enough to be used in setting exposure limits. Electromagnetic interference by electromagnetic fields generated by hand-held telephones may indirectly result in threats to health if vital medical equipment is affected. The committee advises people wearing an implanted pacemaker not to carry a portable telephone that is in stand-by mode in close proximity to the pacemaker; a minimum distance of 15 cm should be observed.

Body Temperature Regulation↗
PubMed1991

[Extremely low frequency electromagnetic fields in human environment and the risk of cancer in the light of epidemiological studies-- based on the literature].

Numerous reports suggest that there is a relationship between the increased incidence of cancer and congenital defects in children on one hand and exposure to extremely low frequency electromagnetic fields at the place of habitation on the other. Some authors suggest that electromagnetic fields persisting in flats, produced by home electric installations, various forms of their execution and external electric power lines may enhance the occurrence of cancer. Living flat buildings are generally remote from electric power lines. They are, however, supplied with electric power by means of trafo stations. The maximum averaged values for 356 living flats in Denver, Colorado, were 14 V/m for the electric component and 0.25 microT for the magnetic component of the field. Besides, various household devices supplied with power from the mains also produce ELF EM fields. From the available epidemiological data it can be concluded that the relationship between exposure to ELF EM fields and increased incidence of cancer has not been unequivocally proved. The estimated risk remains within 0.9-3.2 range.

Adult↗
PubMed2000

Lyn and syk tyrosine kinases are not activated in B-lineage lymphoid cells exposed to low-energy electromagnetic fields.

Exposure of B-lineage lymphoid cells to a 100 microT 60 Hz AC magnetic field has been reported to stimulate the rapid activation of Lyn and Syk tyrosine kinases and the induction of protein tyrosine phosphorylation. These findings are significant because of the critical role played by these B cell signaling events in the control of growth and differentiation, and therefore the potential of electromagnetic field (EMF) exposure to induce cancer. We report the first study carried out with the aim of reproducing the reported EMF effects on Lyn and Syk tyrosine kinases. The system used enabled EMF exposure conditions to be carefully controlled and also allowed experiments to be performed blind. The effects of a 100 microT 60 Hz AC magnetic field on protein tyrosine phosphorylation and on Lyn and Syk tyrosine kinase activities were investigated in Nalm-6 and DT40 B cells in the absence and presence of a 46 microT DC magnetic field. However, no significant effects of low-energy electromagnetic fields on tyrosine kinase activities or protein phosphorylation were observed.

B-Lymphocytes↗
PubMed1999

Three molecular mechanisms to explain some biological effects of electromagnetic fields and hypogravity.

There are many reports about the biological effects of electromagnetic fields and hypogravity and there have been many attempts to develop a theoretical explanation of this phenomenon. In this work, a mechanism is described based on the action of these physical environmental factors on single electrically charged groups from amino acids and considering the elongation stage of the protein synthesis as one of the main targets for both factors. For some rapid bioeffects after short exposures, a direct action on the conformation of the binding site of proteins is postulated. The other mechanism described here is based on the effect of these factors on the motion of the ionized calcium at the extracellular fluid. Many reports about the influences of electromagnetic and gravitational fields on gene expression, enzyme activity, bone mineralization, and oncogenesis are discussed, taking into account the new molecular mechanisms.

Animals↗
PubMedDate not supplied

Congenital "pseudarthroses" of the tibia: treatment with pulsing electromagnetic fields.

During the past seven years, 34 patients with infantile nonunions associated with congenital "pseudarthroses" completed treatment with pulsing electromagnetic fields (PEMFs). An analysis of results reveals that 17/34 (50%) have achieved complete healing with biomechanically sound union and radiographic demonstration of remedullarization. Union with function, i.e., healing with continued need for protection, was achieved in 7/34 (21%). Failure was the outcome in 10/34 patients (29%). Most of these occurred in males with a history of early fracture (less than 1 year) and with spindled, hypermobile lesions (Type III). During the early period of the study, PEMFs were the sole means of treatment. After a "coil effect" had been demonstrated, surgical realignment, immobilization and grafting were combined with PEMF treatment. Fundamentals of orthopedic management developed by the larger experience with adult nonunions were found to apply equally to infantile nonunions treated with PEMFs. These include effective immobilization of the fracture site and controlled "stress working" during recovery to facilitate gradual remodeling. PEMFs have been demonstrated to be a potentially useful adjunct in the orthopedic surgeon's armamentarium for treating infantile nonunions (congenital "pseudarthroses").

Age Factors↗
PubMed1978

[The influence of the electromagnetic field on the activity of alkaline phosphatase in immobilised children (author's transl)].

This paper reports the influence of a changing electromagnetic field on the alkaline phosphatase-activity in the sera of immobilised children. The enzyme activity which was considerably reduced in immobilised children, increased significantly after treatment with an electromagnetic field, whereas the acid phosphatase-activity was not changed. A possible influence of the magnetic field on osteoblastic activity is discussed.

Acid Phosphatase↗
PubMed2000

Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study.

OBJECTIVES: This nested case-control study examines mortality from suicide in relation to estimated exposure to extremely low frequency electromagnetic fields (EMFs) in a cohort of 138,905 male electric utility workers. METHODS: Case-control sampling included 536 deaths from suicide and 5348 eligible controls. Exposure was classified based on work in the most common jobs with increased exposure to magnetic fields and indices of cumulative exposure to magnetic fields based on a measurement survey. RESULTS: Suicide mortality was increased relative to work in exposed jobs and with indices of exposure to magnetic fields. Increased odds ratios (ORs) were found for years of employment as an electrician (OR 2.18; 95% confidence interval (95% CI) 1.25 to 3.80) or lineman (OR 1.59; 95% CI 1.18 to 2.14), whereas a decreased OR was found for power plant operators (OR 0.67; 95% CI 0.33 to 1.40). A dose response gradient with exposure to magnetic fields was found for exposure in the previous year, with a mortality OR of 1.70 (95% CI 1.00 to 2.90) in the highest exposure category. Stronger associations, with ORs in the range of 2.12-3.62, were found for men <50 years of age. CONCLUSION: These data provide evidence for an association between occupational electromagnetic fields and suicide that warrants further evaluation. A plausible mechanism related to melatonin and depression provides a direction for additional laboratory research as well as epidemiological evaluation.

Adolescent↗
PubMed2005

[Change in pain reaction by combined action of nitric oxide modulators and low intensity electromagnetic field].

In experiments on mice with the tonic pain caused by introduced of 5% of formalin in hindpaw, are quantitatively measure changes of painful behavioural reaction (PBR) values under action low intensity electromagnetic field (EMF) and substances that modulate activity of NO-synthase system, and at both of these action also. Such substances were used: in quality inhibitor NO-synthase--Nw-nitro-L-arginin (L-NAME), donors NO--sodium nitroprusside (SNP) and sodium nitrite (SN). Influence of the EMF completely eliminated effect of the L-NAME and SN in concentration of 0.5 mM/l, and also SNP in concentration 5 mcM/l on the painful reaction. The assumption that neurogenetics and NO- ergic mechanisms are basis of the systems analgesic effects of the low intensity electromagnetic fields. Mechanisms of modulation of painful behavioural reaction and other behavioural displays of animals under condition EMF and NO are discussed.

Animals↗