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Low-frequency electromagnetic fields alter the replication cycle of MS2 bacteriophage.

The effect of exposure to 60-Hz electromagnetic fields (EMFs) on RNA coliphage MS2 replication was studied. EMF exposure commenced when the bacterial cultures were inoculated with the phage (t = 0). In 12 experiments in which the strength of the field was 5 G, a significant delay in phage yield was found in the EMF-exposed cultures 45-65 min after inoculation, compared with control cultures. However, the EMF did not alter the final phage concentration. Experiments at 25 G (N = 5) suggested that the stronger field resulted in both impeded phage replication and increased phage yield. No differences between test groups were found in experiments involving sham-EMF exposure, thereby indicating that the results obtained with the EMFs were not due to systematic error. It appears that MS2, which codes for only four proteins, is the simplest biological system in which an EMF-induced effect has been demonstrated. The MS2 system is, therefore, conducive to follow-up studies aimed at understanding the level and nature of the underlying interaction process, and perhaps to biophysical modeling of the interaction process.

Electromagnetic Fields↗

Effects of GSM electromagnetic field on the MEG during an encoding-retrieval task.

Potential effects of GSM 1800 electromagnetic fields (EMF) on verbal memory encoding were investigated by recording event-related magnetic fields (ERMF) from the brain during subsequent memory retrieval. Twelve normal subjects participated in the study. After encoding words from a study list presented in the first phase they had to discriminate old from new words mixed together in a test list presented during the second phase. All subjects performed two experimental sessions, one with exposure to EMF during the study phase, and one without. Exposure to EMF changed an early (350-400 ms) task-specific component of the ERMF indicating an interference of EMF and item encoding. Behavioural measures were not significantly affected. Adverse health effects cannot be derived from these data.

Adolescent↗

Influence of continuous electromagnetic fields on the stage, weight and stature of the chick embryo.

The influence of continuous electromagnetic fields (0, 181 or 361 Gs/cm2) on the development of chick embryo (n = 144) was studied. Several parameters were determined at days 5, 10 and 15 of incubation: stage (following Hamburger and Hamilton), vertex-coccyx length (size) and weight. At 5 days of incubation, all embryos showed a similar stage. However, at days 10 and 15, the embryos exposed to 181 Gs/cm2 showed a stage significantly superior to that of the others. There were no differences between the exposed embryos and the control ones with regard to weight and stature, except at 15 days when the embryos exposed to 361 Gs/cm2 showed greater weight and stature than those of the controls.

Animals↗

Parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring.

We examined parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring. Cases were 538 children diagnosed with neuroblastoma between 1992 and 1994 in the United States or Canada. Age-matched controls were selected by random-digit dialing. Occupational exposures to electrical equipment and radiation sources were classified by an industrial hygienist, and average exposures to extremely low frequency magnetic fields were estimated using a job exposure matrix. Maternal exposure to a broad grouping of sources that produce radiofrequency radiation was associated with an increased incidence of neuroblastoma (odds ratio = 2.8; 95% confidence interval = 0.9-8.7). Paternal exposure to battery-powered forklifts was positively associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.8-3.2), as were some types of equipment that emit radiofrequency radiation (odds ratios congruent with 2.0); however, the broad groupings of sources that produce ELF fields, radiofrequency radiation, or ionizing radiation were not associated with neuroblastoma. Paternal average extremely low frequency magnetic field exposure >0.4 microTesla was weakly associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.9-2.8), whereas maternal exposure was not. Overall, there was scant supportive evidence of strong associations between parental exposures in electromagnetic spectrum and neuroblastoma in offspring.

Case-Control Studies↗

Effects of electromagnetic field emitted by cellular phones on the EEG during a memory task.

The effects of electromagnetic fields (EMF) emitted by cellular phones on the ERD/ERS of the 4-6 Hz, 6-8 Hz, 8-10 Hz and 10-12 Hz EEG frequency bands were studied in 16 normal subjects performing an auditory memory task. All subjects performed the memory task both with and without exposure to a digital 902 MHz EMF in counterbalanced order. The exposure to EMF significantly increased EEG power in the 8-10 Hz frequency band only. Nonetheless, the presence of EMF altered the ERD/ERS responses in all studied frequency bands as a function of time and memory task (encoding vs retrieval). Our results suggest that the exposure to EMF does not alter the resting EEG per se but modifies the brain responses significantly during a memory task.

Adult↗

Effects of extremely-low-frequency electromagnetic fields on ion transport in several mammalian cells.

We have investigated the effects of sinusoidal electromagnetic fields (EMF) on ion transport (Ca2+, Na+, K+, and H+) in several cell types (red blood cells, thymocytes, Ehrlich ascites tumor cells, and HL60 and U937 human leukemia cells). The effects on the uptake of radioactive tracers as well as on the cytosolic Ca2+ concentration ([Ca2+]i), the intracellular pH (pHi), and the transmembrane potentsial (TMP) were studied. Exposure to EMF at 50 Hz and 100-2000 microT (rms) had no significant effects on any of these parameters. Exposure to EMF of 20-1200 microT (rms) at the estimated cyclotron magnetic resonance frequencies for the respective ions had no significant effects except for a 12-32% increase of the uptake of 42K within a window at 14.5-15.5 Hz and 100-200 microT (rms), which was found in U937 and Ehrlich cells but not in the other cell types.

Animals↗

Acute effects of 60-Hz electromagnetic fields on ex vivo murine lymphocyte and macrophage functions, and in vitro tumor cell growth.

Electromagnetic fields (EMFs) have been associated with impairing health. There are data that associate EMFs exposure to incidence of cancer, but there are conflicting results between epidemiological and laboratory studies. Similarly studies on the effect of EMF on the immune system have produced variable results. In the present study, we evaluated the acute effects of 60 Hz EMFs exposure at 1.0 mT, on proliferation of murine thymic lymphocytes, production of nitric oxide and phagocytosis of Candida albicans by peritoneal murine macrophages, as well as the effect of 8 h/day of EMF exposure during 6 days on proliferation of murine lymphoma L5178Y-R cell growth. We observed that exposure to EMF did not alter lymphocyte and macrophage functions, and did not affect in vitro cell growth of the murine lymphoma cell line L5178Y-R.

Animals↗

Oxidative stress effects on the central nervous system of rats after acute exposure to ultra high frequency electromagnetic fields.

Mobile telephones and their base stations are an important source of ultra high frequency electromagnetic fields (UHF-EMFs; 800-1800 MHz) and their utilization is increasing all over the world. Epidemiological studies have suggested that low energy UHF-EMFs may have biological effects, such as changes in oxidative metabolism after exposure. Therefore, we have investigated the effect of acute UHF-EMF exposure on non-enzymatic antioxidant defense and lipid and protein oxidative damage in the rat frontal cortex and hippocampus. We have used malondialdehyde (MDA) and carbonyl assays to assess lipid and protein oxidative damages, respectively. No changes in lipid and protein damage, and also in non-enzymatic defense were found in frontal cortex or hippocampus. These results suggest that acute UHF-EMF exposure is not able to produce detectable oxidative stress in rats from any age tested. However, more tests using a longer period of exposure and evaluating other tissues are necessary to ensure that there is no health risk associated with the use of mobile phones.

Animals↗

Correlates of residential wiring code used in studies of health effects of residential electromagnetic fields.

The home wiring code is the most widely used metric for studies of residential electromagnetic field (EMF) exposure and health effects. Despite the fact that wiring code often shows stronger correlations with disease outcome than more direct EMF home assessments, little is known about potential confounders of the wiring code association. In a study carried out in southern Connecticut in 1988-1991, the authors used strict and widely used criteria to assess the wiring codes of 3,259 homes in which respondents lived. They also collected other home characteristics from the tax assessor's office, estimated traffic density around the home from state data, and interviewed each subject (2,967 mothers of reproductive age) for personal characteristics. Women who lived in very high current configuration wiring coded homes were more likely to be in manual jobs and their homes were older (built before 1949, odds ratio (OR) = 73.24, 95% confidence interval (CI) 29.53-181.65) and had lower assessed value and higher traffic densities (highest density quartile, OR = 3.99, 95% CI 1.17-13.62). Because some of these variables have themselves been associated with health outcomes, the possibility of confounding of the wiring code associations must be rigorously evaluated in future EMF research.

Adult↗

[Norms and standards for radiofrequency electromagnetic fields in Latin America: guidelines for exposure limits and measurement protocols].

New technologies that use electromagnetic fields (EMF) have proved greatly beneficial to humankind. EMF are used in a variety of ways in the transmission of electrical energy and in telecommunications, industry, and medicine. However, some studies have shown that EMF could be detrimental to one's health, having found an association between exposure to EMF on the one hand, and the incidence of some types of cancer as well as behavioral changes on the other. Although so far there is no concrete proof that exposure to low-intensity EMF is hazardous, researchers continue to study the issue in an attempt to reach a consensus opinion and to establish safety standards. While developing and establishing such norms and standards have traditionally been the responsibility of international specialized agencies, national health authorities should take an active part in this process. Currently the Pan American Health Organization is promoting scientific research, often in the form of epidemiologic studies, in order to propose uniform norms and standards. Some Latin American countries, including Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Mexico, Peru, and Venezuela, have already enacted incomplete or partial legislation based on recommended international standards. This article describes the norms established in Latin America and the particular approach taken by each country.

Electromagnetic Fields↗

[Use of ultra high-frequency electromagnetic fields in pediatric surgery].

The procedures associated with the application of a super-frequency electromagnetic field (SFEMF) are being introduced into a therapeutical process in their various modifications at the Pediatric Surgery Hospital of Russian State Medical University. This has been preceded by enormous experimental work aimed at evaluating the potentialities of SFEMF for potentiation of cryogenic exposure and for individual use for endovascular occlusion and local hyperthermia. A total of 947 patients were treated with SFEMF from 1979 to 1990. The largest group included children with hemangiomas of various site (n = 465) and those with cheloid scars (n = 395). Thirty-one patients underwent intravascular coagulation with SFEMF in the treatment of arterial and venous malformations and 31 patients were treated for pigmentary spots of various site with SFEMF + cryodestruction. Local hypothermia was performed in 25 children with extensive hemangiomas of the face and neck with SFEMF. The total therapeutical benefits reached 98%. For these purposes the authors used a Plot routine apparatus, 915 mHz, with a set of contact and special emitters. The experience with SFEMF in pediatric surgery suggests that it is highly effective and the trend is promising.

Animals↗

Electromagnetic fields enhance chemically-induced hyperploidy in mammalian oocytes.

Epidemiological studies suggest that exposure to electromagnetic fields (EMFs) in the environment may be associated with mutagenic changes, but the relation between EMF exposure and aneuploidy has not previously been studied. Environmental EMFs apparently lack the energy necessary to function as aneugens, but the possibility exists that EMFs could influence the incidence of aneuploidy synergistically because EMFs can activate the neuroendocrine system, and ovulation and oocyte meiotic maturation are under neurohormonal control. This hypothesis was tested by examining the effect of EMF exposure on the occurrence of hyperploidy in mouse oocytes induced by vinblastine sulphate (VBS), which was employed as a surrogate for aneugens in the environment. The incidence of hyperploidy in metaphase II oocytes of individual mice following superovulation was determined, and statistical methods were developed to assess whether EMF exposure during oogenesis in the presence of VBS altered the rate of hyperploidy. A significant effect of EMF exposure on VBS-induced hyperploidy was found (P < 0.05). The data suggested that the EMF primarily affected the mice that exhibited a high incidence of VBS-induced hyperploidy. Exposure had no effect on the number of oocytes ovulated nor on the occurrence of hypoploidy. The results support the hypothesis that EMF exposure can promote the occurrence of aneuploidy caused by an aneugen via a mechanism involving the neuroendocrine system.

Animals↗

Electromagnetic fields increase in vitro and in vivo angiogenesis through endothelial release of FGF-2.

Pulsed electromagnetic fields (PEMF) have been shown to be clinically beneficial, but their mechanism of action remains unclear. The present study examined the impact of PEMF on angiogenesis, a process critical for successful healing of various tissues. PEMF increased the degree of endothelial cell tubulization (sevenfold) and proliferation (threefold) in vitro. Media from PEMF cultures had a similar stimulatory effect, but heat denaturation ablated this activity. In addition, conditioned media was able to induce proliferative and chemotactic changes in both human umbilical vein endothelial cells and fibroblasts, but had no effect on osteoblasts. Angiogenic protein screening demonstrated a fivefold increase in fibroblast growth factor beta-2 (FGF-2), as well as smaller increases in other angiogenic growth factors (angiopoietin-2, thrombopoietin, and epidermal growth factor). Northern blot analysis demonstrated an increase in FGF-2 transcription, and FGF-2 neutralizing antibody inhibited the effects of PEMF. In vivo, PEMF exposure increased angiogenesis more than twofold. We conclude that PEMF augments angiogenesis primarily by stimulating endothelial release of FGF-2, inducing paracrine and autocrine changes in the surrounding tissue. These findings suggest a potential role for PEMF in therapeutic angiogenesis.

Animals↗

[Effects of different frequency electromagnetic fields on the differentiation of midbrain neural stem cells].

Objective. To examine the effect of electromagnetic fields (EMF) (20 Hz, 8 mT; 5 Hz, 8 mT) on the neuron-orientated differentiation of neural stem cells (NSCs) from midbrains of new-bom rats. Method. Differentiated NSCs were exposed to EMF for 2 x 15 min per day lasting for I d, 5 d, or 10 d. The sham-exposure controls were correspondingly established. Cells were fixed and processed for immunofluorescent staining using the antibody against neuron-specific marker MAP2, then the percentage of MAP2+ cells was calculated. Result. The two EMFs promoted the differentiation of a neuronal fate in different ways. Both of them came into effect even after 1 d exposure. When cells exposed to the 20 Hz EMF, the percentage of neuron-orientated cells gradually increased with longer-term exposure and the most significant effect appeared in 10 d group while that happened in 5 d group under the condition of 5 Hz EMF. The effect contrasted horizontally, significant differences between the two EMFs were observed only at 10 d groups, 20 Hz EMF having more favorable effect than 5 Hz EMF. Conclusion. 20 Hz and 5 Hz EMF could promote the differentiation of midbrain NSCs to a neuronal phenotype in different ways, suggesting that the physical induction might be another strategy to manipulate the differentiation of NSCs.

Animals↗

Effects of high-frequency electromagnetic fields on human EEG: a brain mapping study.

Cell phones emitting pulsed high-frequency electromagnetic fields (EMF) may affect the human brain, but there are inconsistent results concerning their effects on electroencephalogram (EEG). We used a 16-channel telemetric electroencephalograph (ExpertTM), to record EEG changes during exposure of human skull to EMF emitted by a mobile phone. Spatial distribution of EMF was especially concentrated around the ipsilateral eye adjacent to the basal surface of the brain. Traditional EEG was full of noises during operation of a cellular phone. Using a telemetric electroencephalograph (ExpertTM) in awake subjects, all the noise was eliminated, and EEG showed interesting changes: after a period of 10-15 s there was no visible change, the spectrum median frequency increased in areas close to antenna; after 20-40 s, a slow-wave activity (2.5-6.0 Hz) appeared in the contralateral frontal and temporal areas. These slow waves lasting for about one second repeated every 15-20 s at the same recording electrodes. After turning off the mobile phone, slow-wave activity progressively disappeared; local changes such as increased median frequency decreased and disappeared after 15-20 min. We observed similar changes in children, but the slow-waves with higher amplitude appeared earlier in children (10-20 s) than adults, and their frequency was lower (1.0-2.5 Hz) with longer duration and shorter intervals. The results suggested that cellular phones may reversibly influence the human brain, inducing abnormal slow waves in EEG of awake persons.

Adult↗

[GSM 1,800 MHz radiofrequency electromagnetic fields induced clustering of membrane surface receptors and interference by noise magnetic fields].

OBJECTIVE: To investigate the possible effect of exposure to GSM 1,800 MHz radiofrequency electromagnetic fields (RF EMF) on epidermal growth factor (EGF) receptor and its possible interference by noise magnetic fields (MF). METHODS: Chinese hamster lung fibroblasts (CHL) were exposed to 1,800 MHz RF EMF (modulated by 217 Hz or 50 Hz, or unmodulated), 2 microT noise MF, and RF EMF combined with 2 microT noise MF for 15 min, respectively. The specific absorption rates (SARs) of RF EMF were 0.1, 0.5, 1.0, 2.0 and 4.0 W/kg. Commercial EGF (1 ng/ml) treatment was used as positive control. EGF receptors on the cell membrane were observed under a laser scanning confocal microscope after indirect immunofluorescence staining. RESULTS: EGF receptor clustering was induced after exposure to GSM 1,800 MHz RF EMF modulated by 217 Hz or 50 Hz MF at SARs of 0.5, 1.0, 2.0, 4.0 W/kg for 15 min as induced by 1 ng/ml EGF, but not at SAR of 0.1 W/kg. And no EGF receptor clustering was found in cells after exposure to unmodulated RF EMF or 2 microT noise MF. In addition, superposition of 2 microT noise MF could inhibit the EGF receptor clustering induced by GSM 1,800 MHz RF EMF. CONCLUSION: EGF receptor clustering in CHL cells can be induced by GSM 1,800 MHz RF EMF at the lowest SAR of 0.5 W/kg and inhibited by noise MF. The modulation of wave may play an important role in the inducement of receptor clustering after RF exposure.

Animals↗

Pulsed electromagnetic field treatments enhance the healing of fibular osteotomies.

This study tested the hypothesis that pulsed electromagnetic field (PEMF) treatments augment and accelerate the healing of bone trauma. It utilized micro-computed tomography imaging of live rats that had received bilateral 0.2 mm fibular osteotomies (approximately 0.5% acute bone loss) as a means to assess the in vivo rate dynamics of hard callus formation and overall callus volume. Starting 5 days post-surgery, osteotomized right hind limbs were exposed 3 h daily to Physio-Stim PEMF, 7 days a week for up to 5 weeks of treatment. The contralateral hind limbs served as sham-treated, within-animal internal controls. Although both PEMF- and sham-treatment groups exhibited similar onset of hard callus at approximately 9 days after surgery, a 2-fold faster rate of hard callus formation was observed thereafter in PEMF-treated limbs, yielding a 2-fold increase in callus volume by 13-20 days after surgery. The quantity of the new woven bone tissue within the osteotomy sites was significantly better in PEMF-treated versus sham-treated fibulae as assessed via hard tissue histology. The apparent modulus of each callus was assessed via a cantilever bend test and indicated a 2-fold increase in callus stiffness in the PEMF-treated over sham-treated fibulae. PEMF-treated fibulae exhibited an apparent modulus at the end of 5-weeks that was approximately 80% that of unoperated fibulae. Overall, these data indicate that Physio-Stim PEMF treatment improved osteotomy repair. These beneficial effects on bone healing were not observed when a different PEMF waveform, Osteo-Stim, was used. This latter observation demonstrates the specificity in the relationship between waveform characteristics and biological outcomes.

Animals↗

Influence of pulsed electromagnetic fields on healing of experimental colonic anastomosis.

PURPOSE: The study investigated the influence of pulsed electromagnetic fields (PEMFs) on the mechanical strength and collagen content of uncomplicated colonic anastomosis in rats. METHODS: A standardized left colonic resection was performed 3 cm above the peritoneal reflection, and end-to-end anastomosis was constructed with eight interrupted inverting sutures. Beginning immediately after surgery, randomly assigned groups were exposed to one of the following: 1) 100 Hz (frequency), 1 mT (intensity) PEMFs with 16-hour on/8-hour off cycles (n = 8); 2) 100 Hz, 2 mT PEMFs with 16-hour on/8-hour off cycles (n = 8); 3) 100 Hz, 1 mT PEMFs with 6-hour on/6-hour off cycles (n = 6), whereas the control group (n = 10) received no PEMFs. Relaparatomy was performed at 72 hours postoperatively, and the bursting pressure of the anastomotic segment was recorded in situ. The hydroxyproline contents of the anastomotic and adjacent perianastomotic segments of equal lengths were determined. RESULTS: Mean bursting pressure values of the groups that received 100 Hz, 1 or 2 mT PEMFs with 16-hour on/8-hour off cycles (90.88 +/- 19.13 and 83.88 +/- 7.08 mmHg, respectively) were significantly higher than those of the control group (61.66 +/- 10.6 mmHg) and the group with 6-hour on/6-hour off cycles (64.83 +/- 7.36 mmHg; P < 0.05 for all comparisons). Hydroxyproline contents of the anastomotic and perianastomotic segments were consistently higher in the 16-hour on/8-hour off PEMF groups, compared with those of the corresponding segments of the control group. CONCLUSIONS: PEMFs applied externally to unrestrained rats within a "window of PEMF parameters" provided a significant gain in the mechanical strength of the colonic anastomosis, at least 72 hours post-operatively. Associated relative increases in the hydroxyproline contents of the (peri)anastomotic colonic segments suggest that an altered collagen metabolism might contribute to this enhancement of the anastomotic repair. Further investigations based on these preliminary data and the definition of the exact measures regarding the effects of PEMFs on biologic systems, in general, may lead to an efficient and new adjunctive modality in colorectal surgery.

Anastomosis, Surgical↗