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At least 973 records · Page 54Linked to original sources
PubMed2003

The use of pulsed electromagnetic fields with complex modulation in the treatment of patients with diabetic polyneuropathy.

Clinical and electroneuromyographic studies were performed in 121 patients with diabetic polyneuropathy (DPN) before and after courses of treatment with pulsed electromagnetic fields with complex modulation (PEMF-CM) at different frequencies (100 and 10 Hz). Testing of patients using the TSS and NIS LL scales demonstrated a correlation between the severity and frequency of the main subjective and objective effects of disease and the stage of DPN. The severity of changes in the segmental-peripheral neuromotor apparatus--decreases in muscle bioelectrical activity, the impulse conduction rate along efferent fibers of peripheral nerves, and the amplitude of the maximum M response--depended on the stage of DPN and the duration of diabetes mellitus. The earliest and most significant electroneuromyographic signs of DPN were found to be decreases in the amplitude of the H reflex and the Hmax/Mmax ratio in the muscles of the lower leg. Application of PEMF-CM facilitated regression of the main clinical symptoms of DPN, improved the conductive function of peripheral nerves, improved the state of la afferents, and improved the reflex excitability of functionally diverse motoneurons in the spinal cord. PEMF-CM at 10 Hz was found to have therapeutic efficacy, especially in the initial stages of DPN and in patients with diabetes mellitus for up to 10 years.

Diabetic Neuropathies↗
PubMed1990

Biochemical study of human periodontal ligament: preparation of cell attachment materials induced by pulsed electromagnetic fields.

The periodontium, especially the periodontal ligament and alveolar bone, are tissues constantly subjected to physical stress such as occlusion and mastication. This study was designed to explore the effect of the pulsed electromagnetic fields (PEMF) on the cell attachment and the spread of human periodontal ligament fibroblasts (HPLF) and rat osteoblasts (ROB). PEMF are categorized as one type of mechanical stress. HPLF were obtained by the explantation method described by Saito et al. They were then subcultured in Dulbecco's modified Eagle's medium (D-MEM) and supplemented with 2 mg/ml dialyzed fetal calf serum protein (FCSP), 50 micrograms/ml ascorbic acid and penicillin/streptomycin after trypsinization. ROB were isolated from a two-day-old rat calvaria by the sequential bacterial collagenase digestion method described by Dziak and Brand and were subcultured in D-MEM supplemented with FCSP, ascorbic acid and penicillin/streptomycin. After the confluent HPLF were cultured with serum-free MCDB 107 medium, the quiescent HPLF were exposed with or without PEMF for 24 hr. This was followed by the collection of the control conditioned medium (C-CM) and PEMF exposed conditioned medium (PEMF-CM). The cell attachment assay was performed so that the hydrophobic 24 multiwells were coated with the whole conditioned medium or fractionated conditioned medium by a PO-60K column. After coating, heat inactivated BSA blocked nonspecific sites for cell adhesion, and 3H-TdR labeled HPLF or ROB were cultured on the precoated wells. The activity of cell attachment and spreading was determined by the radioactivity of 3H-TdR using a scintillation counter. The characters of cell attachment factors derived from HPLF were hydrophobic, heat labile and proteolytic enzyme digestible. In addition, the fractionated PEMF-CM enhanced the spreading activity of ROB. PEMF induced the 10 KDa which can enhance the HPLF and ROB spreading. Therefore, the cell attachment and spreading factors secreted by HPLF exposed with PEMF may regulate HPLF and also ROB.

Animals↗
PubMed2002

Exposure to 2.45 GHz electromagnetic fields induces hsp70 at a high SAR of more than 20 W/kg but not at 5W/kg in human glioma MO54 cells.

PURPOSE: To determine potential hazards from exposure to a high-frequency electromagnetic field (HFEMF) at 2.45 GHz by studies of the expression of heat-shock protein 70 (hsp70) in MO54 cells. METHOD: MO54 cells were exposed to a HFEMF at average specific absorption rates (SAR) of 5, 20, 50 and 100 W/kg, using input powers of 0.8, 3.2, 7.8 and 13 W, at a temperature of up to 39 degrees C. An annular culture dish provided three levels of exposure for a given input power, designated inner, middle and outer rings. Two control groups were used: the first was subjected to sham exposure and the second was a temperature control, used to determine the effect of high temperature using incubation in a conventional incubator at 39 degrees C. Cell survival was determined in intervals up to 24 h. Protein was extracted from MO54 cells in both groups after 2, 4, 8 and 16 h exposure times. Changes in the hsp70 protein levels were analysed by Western blots. RESULTS: Little or no cell death was observed in the sham-exposed cells, nor for incubation at 39 degrees C for up to 16 h. Cell survival decreased to about 30% after exposure to HFEMF for 24 h at an average SAR of 100 W/kg. A slight increase in hsp70 was observed in cells in both the inner and outer rings of the plate after exposure at SAR levels of 25 and 78 W/kg, respectively, for 2 h. With increasing exposure time, hsp70 expression increased except for an SAR of 5 W/kg. In the raised temperature control at 39 degrees C, hsp70 expression also increased as the incubation time increased. However, the expression level of hsp70 for the HFEMF exposure was greater than that for the raised temperature control. CONCLUSION: HFEMF can produce an increased level of hsp70 expression in MO54 cells at SAR levels above 20 W/kg, even when the effect of raised temperature is taken into account.

Biomedical Engineering↗
PubMed1991

Effect of low-level pulsed electromagnetic fields on human chromosomes in vitro: analysis of chromosomal aberrations.

The effects of extremely-low-frequency pulsed magnetic fields on human chromosomes with respect to the capacity of inducing chromosome breakage were studied. After human peripheral lymphocytes were exposed in vitro to pulsed electromagnetic fields at different intensities, a significant effect was observed for one of the intensities tested (40 Gauss), relative to the control group with respect to the yield of chromosome breakages.

Analysis of Variance↗
PubMed1999

[The evaluation of the exposure of seamstresses to electromagnetic fields, emitted by sewing machines].

The authors present the results of the first phase of the studies on the risk of pregnancy complications in semesters and on their work environment with special reference to electromagnetic fields (EMF) emitted by various types of industrial sewing machines. EMF measurements were taken in the surrounding of 464 sewing machines used in five sewing works in the region of Lodź. The results obtained provided evidence that semesters++ working with industrial sewing machines were exposed to EMF of 60 Hz. Thirteen types of machines were identified. Having based on the statistical analysis (analysis of variance) it was found that individual types of sewing machines emit substantially different EMFs. Depending on the level of EMF emitted at a given workpost, all the machines were classified into three groups: those with weak (O A/m-1.5 A/m); medium (2 A/m-4 A/m); and strong (9 A/m-16 A/m) emissions.

Electromagnetic Fields↗
PubMed1983

Effects of pulsing electromagnetic fields on bone growth and articular cartilage.

Observations made during treatment of juvenile pseudarthrosis by pulsing electromagnetic fields (PEMF) suggested that bone growth might be altered. PEMF applied to immature rabbits under conditions of continuous stimulation (24 hours/day for 8 weeks) produced no major changes in bone growth. Continuous stimulation by PEMF induced a statistically significant increase (22%) in femoral articular cartilage glycosaminoglycan. Intermittent PEMF stimulation (12 hours with stimulation/12 hours without stimulation) for 18 weeks produced no significant change in bone growth or time of epiphyseal plate closure. No significant changes in the physical characteristics of growing bone were observed with any treatment.

Animals↗
PubMed2002

Effects of 60 Hz electromagnetic field exposure on APP695 transcription levels in differentiating human neuroblastoma cells.

Epidemiological studies have suggested that workers with primary occupation that are likely to have resulted in the medium-to-high extremely low frequency (ELF) electromagnetic field (EMF) exposure are at increased risk of Alzheimer's disease (AD) pathogenesis. As a first step in investigating the possibility of an association between the ELF-EMF exposure and AD at the cellular level, we have used the differentiating IMR-32 neuroblastoma cells. In double-blind experiments, IMR-32 cells were exposed to the magnetic field intensities of 50, 100, and 200 microT at a frequency of 60 Hz for a period of 4 h at the three ages of differentiation (2, 10, and 16 days after incubation in differentiation medium). We used a custom-made Helmholtz coil setup driven by a 60-Hz sinusoidal signal from a function generator and an in-house built power amplifier. Total RNA extracted from the exposed cells was separated by the agarose gel electrophoresis and transferred to a nylon membrane for the northern hybridization. Digoxygenin-labeled APP695 RNA probes were used to detect changes in the APP695 mRNA levels in response to the ELF-EMF exposure. The results reported herein provided no support for any relationship between the APP695 gene transcription and IMR-32 differentiation age, as well as the magnetic field exposure. This study constitutes the first step towards investigating the possibility of an association between the ELF-EMF exposure and AD manifestations at the cellular level.

Alzheimer Disease↗
PubMedDate not supplied

[Permeability of erythrocyte membranes from peripheral blood after exposure to low-frequency alternating electromagnetic field].

The levels of dienic conjugates (DC), malonic dialdehyde (MD), extra-erythrocytic hemoglobin, the rate of chemiluminescence (C), total peroxidase activity (TPA) were determined on a single exposure of animals to low-frequency pulsating electromagnetic field (LFPEF) and chronic exposure of 16 healthy males aged 19-25 years. After acute exposure to LEPEF, the animals showed 64-106% increases in the levels of DC and MD and the rate of C. The persons had higher TPA and C.

Adolescent↗
PubMed2003

Power-line frequency electromagnetic fields do not induce changes in phosphorylation, localization, or expression of the 27-kilodalton heat shock protein in human keratinocytes.

The linkage of the exposure to the power-line frequency (50-60 Hz) electromagnetic fields (EMF) with human cancers remains controversial after more than 10 years of study. The in vitro studies on the adverse effects of EMF on human cells have not yielded a clear conclusion. In this study, we investigated whether power-line frequency EMF could act as an environmental insult to invoke stress responses in human keratinocytes using the 27-kDa heat shock protein (HSP27) as a stress marker. After exposure to 1 gauss (100 micro T) EMF from 20 min to 24 hr, the isoform pattern of HSP27 in keratinocytes remained unchanged, suggesting that EMF did not induce the phosphorylation of this stress protein. EMF exposure also failed to induce the translocation of HSP27 from the cytoplasm to the nucleus. Moreover, EMF exposure did not increase the abundance of HSP27 in keratinocytes. In addition, we found no evidence that EMF exposure enhanced the level of the 70-kDa heat shock protein (HSP70) in breast or leukemia cells as reported previously. Therefore, in this study we did not detect any of a number of stress responses in human keratinocytes exposed to power-line frequency EMF.

Biomarkers↗
PubMed2006

EU Directive, ICNIRP guidelines and Polish legislation on electromagnetic fields.

This review describes the general provisions of and the philosophy behind European Directive 2004/40/EC and ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines. As an example of national legislation on the protection of workers against excessive electromagnetic field exposure, regulations established in Poland are summarized. The problems of a practical implementation of the Directive's provisions are discussed.

Electromagnetic Fields↗
PubMed1995

Coordinated effects of electromagnetic field exposure on erythropoietin-induced activities of phosphatidylinositol-phospholipase C and phosphatidylinositol 3-kinase.

Initial studies with the erythropoietin-sensitive human hematopoietic cell line, TF1, demonstrated both multifarious effects of pulsed electromagnetic field (EMF) exposure on lipid signal transduction and antiproliferative effects of EMF. Stimulation of TF1 cells with erythropoietin resulted in increased phosphatidylinositol 3-kinase activity within 2 min. Addition of wortmannin, an inhibitor of phosphatidylinositol 3-kinase, produced a decrease in cell proliferation as measured by accumulation of cells in the G0/G1 phase of the cell cycle and suppression of erythropoietin-induced DNA synthesis. Similar effects on cell proliferation were seen under EMF treatment. Phosphatidylinositol 3-kinase activity in erythropoietin-stimulated TF1 cells, measured in whole-cell extracts, increased 34% within 2 min and remained above basal levels for at least 20 min. EMF decreased erythropoietin-stimulated phosphatidylinositol 3-kinase activity to lower than basal levels. Additionally, translocation of the 85-kDa regulatory subunit (p85) of phosphatidylinositol 3-kinase to the membrane was prevented by EMF. Phosphatidylinositol-specific phospholipase C was activated, as reflected by increases in diacylglycerol and inositol trisphosphate at 15-60 s after EMF treatment. These results provide the first evidence of subtle coordinated changes by EMF associated with loss of phosphatidylinositol 3-kinase activity, inhibition of the translocation of p85 to the membrane, and activation of phosphatidylinositol-phospholipase C.

Androstadienes↗
PubMed2005

Electromagnetic fields affect transcript levels of apoptosis-related genes in embryonic stem cell-derived neural progenitor cells.

Mouse embryonic stem (ES) cells were used as an experimental model to study the effects of electromagnetic fields (EMF). ES-derived nestin-positive neural progenitor cells were exposed to extremely low frequency EMF simulating power line magnetic fields at 50 Hz (ELF-EMF) and to radiofrequency EMF simulating the Global System for Mobile Communication (GSM) signals at 1.71 GHz (RF-EMF). Following EMF exposure, cells were analyzed for transcript levels of cell cycle regulatory, apoptosis-related, and neural-specific genes and proteins; changes in proliferation; apoptosis; and cytogenetic effects. Quantitative RT-PCR analysis revealed that ELF-EMF exposure to ES-derived neural cells significantly affected transcript levels of the apoptosis-related bcl-2, bax, and cell cycle regulatory "growth arrest DNA damage inducible" GADD45 genes, whereas mRNA levels of neural-specific genes were not affected. RF-EMF exposure of neural progenitor cells resulted in down-regulation of neural-specific Nurr1 and in up-regulation of bax and GADD45 mRNA levels. Short-term RF-EMF exposure for 6 h, but not for 48 h, resulted in a low and transient increase of DNA double-strand breaks. No effects of ELF- and RF-EMF on mitochondrial function, nuclear apoptosis, cell proliferation, and chromosomal alterations were observed. We may conclude that EMF exposure of ES-derived neural progenitor cells transiently affects the transcript level of genes related to apoptosis and cell cycle control. However, these responses are not associated with detectable changes of cell physiology, suggesting compensatory mechanisms at the translational and posttranslational level.

Apoptosis↗
PubMed1995

Variation in cancer risk estimates for exposure to powerline frequency electromagnetic fields: a meta-analysis comparing EMF measurement methods.

We used meta-analysis to synthesize the findings from eleven case-control studies on cancer risks in humans exposed to 50-60 Hertz powerline electromagnetic fields (EMFs). Pooled estimates of risk are derived for different EMF measurement methods and types of cancer. EMF measurement methods are classified as: wiring configuration codes, distance to power distribution equipment, spot measurements of magnetic fields, and calculated indices based on distance to power distribution equipment and historic load data. Pooled odds ratios depicting the risk of cancer by each measurement type are presented for all cancers combined, leukemia for all age groups and childhood leukemia. The wire code measurement technique was associated with a significantly increased risk for all three cancer types, while spot measures consistently showed non-significant odds ratios. Distance measures and the calculated indices produced risk estimates which were significant only for leukemia.

Adult↗
PubMed1993

Investigation of potential genotoxic effects of low frequency electromagnetic fields on Escherichia coli.

Exposure of growing cells of Escherichia coli strain AB1157 to a frequency of 1 Hz with field strengths of 1 or 3 kV m-1 did not affect spontaneous or ultraviolet light (UV)-induced mutation frequencies to rifampicin resistance. Neither did growth in the presence of charge alter the sensitivities of strains AB1157, TK702 umuC or TK501 umuC uvrB to UV. Similarly, although the resistance of strains TK702 umuC and TK501 umuC uvrB to UV was increased by the presence of plasmid pKM101, which carries DNA repair genes, pregrowth of plasmid-containing strains in electric fields did not increase UV resistance. Finally, growth in a low frequency field in the presence of sub-inhibitory concentrations of mitomycin C did not affect mitomycin C-induced mutation frequencies. It is concluded that low frequency electromagnetic fields do not increase spontaneous mutation, induce DNA repair or increase the mutagenic effects of UV or mitomycin C.

DNA Damage↗
PubMed1992

Effects of time-varying electromagnetic fields on K+ (Rb+) fluxes and surface charge of HeLa cells.

The magnetic flux density was varied intermittently from 0.35 to 1.77T and from 0.07 to 1.54 or 1.77T by manual and automatic switchings, respectively, of the power source of an electromagnet. The durations of the "switching-on time" and "-off time" were varied but kept equal. An electric eddy current induced in the culture medium by changes in the magnetic flux density was simulated. When the durations were shorter than 10s, ouabain-sensitive Rb+ influx (active K+ influx) into cultured HeLa cells was significantly inhibited, but the ouabain-insensitive Rb+ influx (passive K+ influx) was not influenced significantly. Inhibition of active Rb+ influx increased with time during exposure for 2 h. Conversely, K+ efflux from the cells was significantly stimulated by the exposure. Microfluorometric examinations of cells loaded with the fluorescent pH indicator 4-heptadecyl-7-hydroxycoumarin (6 microM) and the membrane potential indicator diS-C3-(5) (1 microM) suggested increase in the negative charge on the cell surface during exposure. The observed changes in the K+ (Rb+) fluxes would be related to change in the electric properties of the cell surface caused by exposure to intermittent electromagnetic fields.

Cell Membrane↗
PubMedDate not supplied

[The efficiency and direction of thymus changes after whole-body exposure of mice to the weak electromagnetic field are determined by the initial status of the thymus].

The work presents results of the experimental study on thymus changes developing after whole-body exposure of mice to ultralow power pulse-modulated electromagnetic field (carrying frequency 2.39 GHz, modulating pulses with frequency 4 Hz, duration of impulses 0.025 sec, average power density 60 mW/cm2, absorbed dose 0.086 J/g or 0.172 J/g). It was shown that a percent of the microwave induced increase or decrease of thymus mass and the number of cells in the organ (y) are determined by the initial mass or number of cells in thymus accordingly to equation of linear regression: (yx = 215-2.25x, where x is the thymus mass of control animals (in a range 31-63 mg) and (yx = 178.6-41x, where x is the initial number of cells in thymus (in a range 0.6 x 10(8)-2.6 x 10(8)) reduced by a factor of 10(8).

Animals↗
PubMed2005

The sensitivity of children to electromagnetic fields.

In today's world, technologic developments bring social and economic benefits to large sections of society; however, the health consequences of these developments can be difficult to predict and manage. With rapid advances in electromagnetic field (EMF) technologies and communications, children are increasingly exposed to EMFs at earlier and earlier ages. Consistent epidemiologic evidence of an association between childhood leukemia and exposure to extremely low frequency (ELF) magnetic fields has led to their classification by the International Agency for Research on Cancer as a "possible human carcinogen." Concerns about the potential vulnerability of children to radio frequency (RF) fields have been raised because of the potentially greater susceptibility of their developing nervous systems; in addition, their brain tissue is more conductive, RF penetration is greater relative to head size, and they will have a longer lifetime of exposure than adults. To evaluate information relevant to children's sensitivity to both ELF and RF EMFs and to identify research needs, the World Health Organization held an expert workshop in Istanbul, Turkey, in June 2004. This article is based on discussions from the workshop and provides background information on the development of the embryo, fetus, and child, with particular attention to the developing brain; an outline of childhood susceptibility to environmental toxicants and childhood diseases implicated in EMF studies; and a review of childhood exposure to EMFs. It also includes an assessment of the potential susceptibility of children to EMFs and concludes with a recommendation for additional research and the development of precautionary policies in the face of scientific uncertainty.

Brain Neoplasms↗