Stereological analysis of thyroid mast cells in rats after exposure to extremely low frequency electromagnetic field and the following "off" field period

Influence of extremely low frequency electromagnetic field (ELF-EMF) on thyroid gland mast cells was investigated on male Mill Hill rats. Animals were exposed to EMF (50 Hz, 50 microT to 500 microT, 10 V/m) from 24 hours after birth, 7 hours/day, 5 days/week for three months when a part of animals (group I) was sacrificed, while the rest of them were subjected to recovery evaluation and sacrificed after one (group II), two (group II) and three (group IV) weeks following the exposure. Stereological analysis on toluidine blue-stained paraffin sections showed increased volume density of degranulated mast cells in all groups and, except in group III, and numerical density as well, implicating the sensitivity of thyroidal mast cells to power frequency EMFs. Since in our previous investigations, morphofunctional alterations of thyroid gland in rats exposed to ELF-EMF were found the contribution of released mast cell mediators to these changes could be presumed.     

The effect on rat thymocytes of the simultaneous in vivo exposure to 50-Hz electric and magnetic field and to continuous light

Thymus plays an important role in the immune system and can be modulated by numerous environmental factors, including electromagnetic fields (EMF). The present study has been undertaken with the aim to investigate the role of long-term exposure to extremely low frequency electric and magnetic fields (ELF-EMF) on thymocytes of rats housed in a regular dark/light cycle or under continuous light. Male Sprague-Dawley rats, 2 months old, were exposed or sham exposed for 8 months to 50-Hz sinusoidal EMF at two levels of field strength (1 kV/m, 5 microT and 5 kV/m, 100 microT, respectively). Thymus from adult animals exhibits signs of gradual atrophy mainly due to collagen deposition and fat substitution. This physiological involution may be accelerated by continuous light exposure that induces a massive death of thymocytes. The concurrent exposure to continuous light and to ELF-EMF did not change significantly the rate of mitoses compared to sham-exposed rats, whereas the amount of cell death was significantly increased, also in comparison with animals exposed to EMF in a 12-h dark-light cycle. In conclusion, long-term exposure to ELF-EMF, in animals housed under continuous light, may reinforce the alterations due to a photic stress, suggesting that, in vivo, stress and ELF-EMF exposure can act in synergy determining a more rapid involution of the thymus and might be responsible for an increased susceptibility to the potentially hazardous effects of ELF-EMF.     

Chronic electromagnetic field exposure decreases HSP70 levels and lowers cytoprotection

Electromagnetic field (EMF) exposures have been shown to induce heat shock proteins (HSPs), which help to maintain the conformation of cellular proteins during periods of stress. We have previously reported that short-term exposure of chick embryos to either 60 Hz (extremely low frequency: ELF), or radio-frequency (RF: 915 MHz) EMFs induce protection against hypoxia. Experiments presented in the current report are based on a study in which long-term (4 days), continuous exposure to ELF-EMFs decreased protection against ultraviolet radiation. Based on this result, it was hypothesized that de-protection against hypoxia should also occur following long-term, continuous, or daily, repeated exposures to EMFs. To test this hypothesis, chick embryos were exposed to ELF-EMFs (8 microT) continuously for 4 days, or to ELF or RF (3.5 mW incident power)-EMFs repeated daily (20, 30, or 60 min once or twice daily for 4 days). Several of the exposure protocols yielded embryos that had statistically significant decreases in protection against hypoxic stress (continuous and 30 or 60 min ELF twice daily; or 30 or 60 min once daily RF). This is consistent with our finding that following 4 days of ELF-EMF exposure, HSP70 levels decline by 27% as compared to controls. In addition, the superposition of ELF-EMF noise, previously shown to minimize ELF-EMF induced hypoxia protection, inhibited hypoxia de-protection caused by long term, continuous ELF or daily, repeated RF exposures. This EMF-induced decrease in HSP70 levels and resulting decline in cytoprotection suggests a mechanism by which daily exposure (such as might be experienced by mobile phone users) could enhance the probability of cancer and other diseases.     

Neuronal basis of a sensory analyser, the acridid movement detector system. III. Control of response amplitude by tonic lateral inhibition.

1. The Lobular Giant Movement Detector neurone (LGMD) of Schistocerca responds with spikes when small areas of the visual field change in luminance. Previous work has shown that changes of +/- 1 log 10 unit are enough to produce maximal ON and OFF responses. 2. Using a 5 degree test area, it is shown that the number of spikes generated by such a stimulus depends on the luminance of the surrounding area. When the surround is dark, the response is maximal; when it is brightly lit, the response is minimal. Intermediate intensities produce intermediate values of response. A X 2 change in response is produced by about 3 log 10 units change in surround intensity. 3. A bright annulus, with diameters of 10-5 degrees and 25-8 degrees, inhibits both ON and OFF responses when concentric with the 5 degree test area, but not when it is 30 degrees eccentric to the test area. The inhibitory effect shows no decrease after 4 min. 4. These results are interpreted to indicate a tonic lateral inhibitory network, sited peripherally in the optic lobe prior to the divergence of the separate ON and OFF channels found in the projection from the medulla to the LGMD. It is probably identical with that described for the lamina by previous workers.     

A magnetic field exposure facility for evaluation of animal carcinogenicity

Several animal studies have been carried out at the Institut Armand Frappier (IAF) to determine whether chronic exposure to 60 Hz linearly polarized sinusoidal magnetic fields might increase the risk of cancer development of female Fisher rats. The magnetic field exposure facility was developed to meet the requirements of the study protocol for chronic exposure of large number of animals to field intensities of sham < 0.2 microT, 2 microT, 20 microT, 200 microT, and 2000 microT. At each exposure level, including sham, the animals are distributed in a group of four exposure units. Each exposure unit contains two exposure volumes having uniform distribution of magnetic fields for the animals, while the magnetic field external to the unit falls off rapidly due to the "figure-eight" coil topography used. A program of "shake down" tests, followed by verification and calibration of the exposure facility, was carried out prior to starting the animal experiments. Continuous monitoring of the magnetic field and other environmental parameters was an important part in the overall quality assurance program adopted.     

Evaluation of rat thyroid gland morphophysiological status after three months exposure to 50 Hz electromagnetic field

Objective of our study was to use morphophysiological criteria in order to determine the sensitivity of male rat thyroid gland to an extremely low frequency electromagnetic field (ELF-EMF) influence and the ability of the gland to repair after period of exposure. Animals were exposed to 50Hz, 50-500 microT ELF-EMF for 3 months when a part of them (group I) were sacrificed, while the rest of animals were subjected to recovery evaluation of the gland and sacrificed after 1 (group II), 2 (group III) and 3 (group IV) weeks. Histological and stereological analyses were performed on paraffin and semifine thyroid gland sections. Serum T3 and T4 were also determined. Histological and stereological analyses showed that the volume density of follicular epithelium and thyroid activation index decreased, while the volume density of colloid and capillary network increased in group I, II and III. The values of all these parameters in group IV were similar to corresponding controls. Serum T3 and T4 concentrations were significantly lower in all exposed animals, except in group I. Results of this study demonstrate that after significant morphophysiological changes caused by ELF-EMF exposure thyroid gland recovered morphologically, but not physiologically, during the investigated repair period.     

Slow and rapid electrical pulses in the caval vein at pain-evoked leg contraction in the rat

Previous in vivo experiments in rats have shown that pulsed nerve stimulations of 20-50 mV require "external" electrical communication over vessels. This indicates that potential differences also should occur in associated vessels, at physiologic muscle contractions. Pinching toes of the hind leg of anaesthetized rats in the present study caused the animals to spontaneously pull the leg. This resulted in electric potential differences over two intracaval electrodes, as well as high frequency spikes. The slow potential pulses and high frequency spikes could be recorded dominantly in the vena cava compared with the extravascular tissue fluid. The electrical prerequisites and the previous experiments support the view that the vascular-interstitial fluid represents an "external" low resistant communication route of a closed circuit over the nerve cell bodies, the axons and the muscle fibers. A closed electrical circuit evidently increases our possibilities for explaining various structural and chemical events of the synaptic membranes.     

Variation in the flash pattern of the firefly,Photuris versicolor quadrifulgens (Coleoptera: Lampyridae)

We sampled a population of signalingPhoturis versicolor quadrifulgens fireflies to quantify the variation in flash patterns emitted by males. Males produced five distinct flash patterns during their mate-searching flights. Four of the patterns consisted of two to five equal-intensity pulses and the fifth pattern type was a flicker, a group of rapid modulations in intensity. We found that the proportions of each pattern remained relatively constant from night to night throughout the season. The different flash patterns produced varied significantly with time of night; patterns having fewer pulses occurred earlier in the evening. Local density, an estimate of competition, did not significantly correlate with flash pattern type. On consecutive emissions, individuals changed their flash types with a mean probability of 0.12 (over all males), and they usually switched between patterns differing by a single pulse (from a two- to a three-pulse pattern, from a three- to a two-pulse pattern, etc.). The nightly temporal changes in flash patterns may be related to tradeoffs between female availability and energetic costs of signaling or the changes may be related to increased predation risk from visual predators. Photuris versicolor quadrifulgens was originally described by Barber (1951) as a subspecies ofP. versicolor. The genusPhoturis is currently under revision by Dr. James E. Lloyd, and this firefly will be given species status.     

ELF magnetic fields in a city environment

Some epidemiological studies indicate an association between extremely low frequency electromagnetic field (ELF-EMF) exposure and cancer risks. These studies have mainly taken residential and occupational exposure into consideration. Outdoor environments are often considered as low level areas, but in this paper we show that this is not true in a city environment. We have mapped the ELF magnetic flux densities along certain stretches of sidewalk in central G?teborg City, Sweden. About 50% of the investigated street length shows flux densities of the same order of magnitude (0.2 microT and above) as those associated with increased risks of cancer in epidemiological studies. We conclude that the outdoor exposures in a city environment also should be considered in exposure assessments and risk evaluations. These elevated flux densities are probably due to stray currents. We also found strong magnetic flux densities (> 1.0 microT) close to ordinary distribution pillars, power substations, shoplifting alarms, and other electrical devices.     

Induction of DNA strand breaks by intermittent exposure to extremely-low-frequency electromagnetic fields in human diploid fibroblasts

Results of epidemiological research show low association of electromagnetic field (EMF) with increased risk of cancerous diseases and missing dose-effect relations. An important component in assessing potential cancer risk is knowledge concerning any genotoxic effects of extremely-low-frequency-EMF (ELF-EMF).Human diploid fibroblasts were exposed to continuous or intermittent ELF-EMF (50Hz, sinusoidal, 24h, 1000microT). For evaluation of genotoxic effects in form of DNA single- (SSB) and double-strand breaks (DSB), the alkaline and the neutral comet assay were used.In contrast to continuous ELF-EMF exposure, the application of intermittent fields reproducibly resulted in a significant increase of DNA strand break levels, mainly DSBs, as compared to non-exposed controls. The conditions of intermittence showed an impact on the induction of DNA strand breaks, producing the highest levels at 5min field-on/10min field-off. We also found individual differences in response to ELF-EMF as well as an evident exposure-response relationship between magnetic flux density and DNA migration in the comet assay.Our data strongly indicate a genotoxic potential of intermittent EMF. This points to the need of further studies in vivo and consideration about environmental threshold values for ELF exposure.     

Individual differences in the effects of mobile phone exposure on human sleep: rethinking the problem

Mobile phone exposure‐related effects on the human electroencephalogram (EEG) have been shown during both waking and sleep states, albeit with slight differences in the frequency affected. This discrepancy, combined with studies that failed to find effects, has led many to conclude that no consistent effects exist. We hypothesised that these differences might partly be due to individual variability in response, and that mobile phone emissions may in fact have large but differential effects on human brain activity. Twenty volunteers from our previous study underwent an adaptation night followed by two experimental nights in which they were randomly exposed to two conditions (Active and Sham), followed by a full‐night sleep episode. The EEG spectral power was increased in the sleep spindle frequency range in the first 30 min of non‐rapid eye movement (non‐REM) sleep following Active exposure. This increase was more prominent in the participants that showed an increase in the original study. These results confirm previous findings of mobile phone‐like emissions affecting the EEG during non‐REM sleep. Importantly, this low‐level effect was also shown to be sensitive to individual variability. Furthermore, this indicates that previous negative results are not strong evidence for a lack of an effect and, given the far‐reaching implications of mobile phone research, we may need to rethink the interpretation of results and the manner in which research is conducted in this field. Bioelectromagnetics 33:86–93, 2012. © 2011 Wiley Periodicals, Inc.     

PRIOR NIGHT SLEEP DURATION IS ASSOCIATED WITH PSYCHOMOTOR VIGILANCE IN A HEALTHY SAMPLE OF POLICE ACADEMY RECRUITS

Aviation, military, police, and health care personnel have been particularly interested in the operational impact of sleep restriction and work schedules given the potential severe consequences of making fatigue-related errors. Most studies examining the impact of sleep loss or circadian manipulations have been conducted in controlled laboratory settings using small sample sizes. This study examined whether the relationship between prior night sleep duration and performance on the psychomotor vigilance task could be reliably detected in a field study of healthy police academy recruits. Subjects (N?=?189) were medically and psychiatrically healthy. Sleep-wake activity was assessed with wrist actigraphy for 7 days. Subjects performed the psychomotor vigilance task (PVT) for 5?min on a personal digital assistant (PDA) device before and after their police academy workday and on comparable times during their days off. Mixed-effects logistic regression was used to estimate the probability of having ≥1 lapse on the PVT as a function of the previous night sleep duration during the 7 days of field testing. Valid estimates of sleep duration were obtained for 1082 nights of sleep. The probability of a lapse decreased by 3.5%/h sleep the night prior to testing. The overall probability of having a lapse decreased by 0.9%/h since awakening, holding hours of sleep constant. Perceived stress was not associated with sleep duration or probability of performance lapse. These findings demonstrate the feasibility of detecting sleep and circadian effects on cognitive performance in large field studies. These findings have implications regarding the daytime functioning of police officers. (Author correspondence: Thomas.Neylan@ucsf.edu)     

A preliminary study of oscillating electromagnetic field effects on human spermatozoon motility

Some effects of extremely low frequency electromagnetic fields (ELF-EMFs) on human spermatozoa are reported. Significant increases in the values of the motility and of the other kinematic parameters have been observed when spermatozoa were exposed to an ELF-EMF with a square waveform of 5 mT amplitude and frequency of 50 Hz. By contrast, a 5 mT sine wave (50 Hz) and a 2.5 mT square wave (50 Hz) exposure did not produce any significant effect on sperm motility. The effects induced by ELF-EMF (50 Hz; 5 mT) during the first 3 h of exposure persisted for 21 h after the end of the treatment. These results indicate that ELF-EMF exposure can improve spermatozoa motility and that this effect depends on the field characteristics.     

Electromagnetic fields enhance the stress response at elevated temperatures in the nematode Caenorhabditis elegans

We have studied the effect of extremely low frequency electromagnetic fields (ELF-EMF) in the presence of a second stressor (mild heat shock) on the expression of a lacZ reporter gene under the control of hsp16 or hsp70 promoters in two transgenic strains of C. elegans. The expression of the reporter gene was studied by scoring animals with induced beta-galactosidase activity after staining in toto or by biochemical quantitation of the enzyme activity, respectively. In our experimental setup we were able to expose the animals to 50 Hz magnetic flux density of 0-150 microT and at the same time control temperature with high precision (+/-0.1 degrees C). Experimental conditions were defined for which EMF strongly enhances the expression of the reporter gene.     

神经元对于高频电刺激的动态响应

深部脑刺激(deep brain stimulation,DBS)在许多神经系统疾病的临床治疗上都展现出良好的应用前景,然而,其作用机制尚不明确.常规DBS采用高频刺激(high frequency stimulation,HFS)的脉冲序列,这种窄脉冲最容易激活神经元结构中的轴突部分,通过轴突的投射,将HFS的作用传播至下游神经元.因此,为了探讨DBS的作用机制,并鉴于海马脑区是治疗癫痫和痴呆症等疾病的重要靶点,我们研究了海马区轴突HFS对于下游神经元的作用.对麻醉大鼠的海马CA1区传入神经通路Schaffer侧支施加1 min的100 Hz高频刺激,记录并提取下游CA1区锥体神经元和中间神经元的单元锋电位.计算锋电位的发放率,以及它们与刺激脉冲之间的锁相值(phase-locking value,PLV)和潜伏期,以定量分析HFS期间神经元动作电位发放的变化趋势.结果显示,在传入轴突上施加HFS时,初期会诱发下游神经元群体同步产生动作电位(即群峰电位).在HFS后期(群峰电位消失之后),两类神经元的单元锋电位发放仍然持续,并且发放率较稳定.但是,锋电位与刺激脉冲之间的锁相性逐渐减弱、潜伏期逐渐延长.而且,与中间神经元相比较,锥体神经元锋电位的锁相性更弱、潜伏期更长.这些结果表明,持续的轴突HFS可以诱导下游神经元产生非同步的活动,高频脉冲刺激引起的不完全轴突传导阻滞可能是导致该现象产生的主要原因.本文的研究为揭示脑刺激的作用机制提供了重要信息.     

Electromagnetic interference of GSM mobile phones with the implantable deep brain stimulator,ITREL-III

Background

The purpose was to investigate mobile phone interference with implantable deep brain stimulators by means of 10 different 900 Mega Hertz (MHz) and 10 different 1800 MHz GSM (Global System for Mobile Communications) mobile phones.

Methods

All tests were performed in vitro using a phantom especially developed for testing with deep brain stimulators. The phantom was filled with liquid phantom materials simulating brain and muscle tissue. All examinations were carried out inside an anechoic chamber on two implants of the same type of deep brain stimulator: ITREL-III from Medtronic Inc., USA.

Results

Despite a maximum transmitted peak power of mobile phones of 1 Watt (W) at 1800 MHz and 2 W at 900 MHz respectively, no influence on the ITREL-III was found. Neither the shape of the pulse form changed nor did single pulses fail. Tests with increased transmitted power using CW signals and broadband dipoles have shown that inhibition of the ITREL-III occurs at frequency dependent power levels which are below the emissions of GSM mobile phones. The ITREL-III is essentially more sensitive at 1800 MHz than at 900 MHz. Particularly the frequency range around 1500 MHz shows a very low interference threshold.

Conclusion

These investigations do not indicate a direct risk for ITREL-III patients using the tested GSM phones. Based on the interference levels found with CW signals, which are below the mobile phone emissions, we recommend similar precautions as for patients with cardiac pacemakers: 1. The phone should be used at the ear at the opposite side of the implant and 2. The patient should avoid carrying the phone close to the implant.

     

Clinical patent ductus arteriosus in adult genetically epilepsy-prone rats

Persistent patent ductus arteriosus (PDA) and clinically silent PDAs are relatively common congenital cardiac defects in humans. We report here the occurrence of symptomatic PDA in adults from a colony of genetically epilepsy-prone rats (GEPRs). Affected rats displayed severe ventral edema. Echocardiography revealed PDA in several animals. Necropsy findings included cardiomegaly, hepatic hyperemia and centrilobular necrosis indicative of passive congestion, and vascular changes consistent with pulmonary hypertension. All affected rats were descendants of one of two brother-sister breeding pairs established from a single litter in April 2000. Clinically silent PDAs were also detected in the colony. Histological examination of the ligamentum arteriosus showed normal vascular tissue in asymptomatic GEPR and Sprague-Dawley rats. PDAs are likely to have a genetic component in the GEPR colony and may provide a novel model for the study of pathogenesis and therapy of this condition.     

Mixed self-assembly of polydiacetylenes for highly specific and sensitive strip biosensors

Polydiacetylenes (PDAs), which possess unique properties that allow them to change color in response to environmental changes such as variations in pH, temperature, and molecular binding, have been widely investigated as signal transducers in biosensor applications. Most PDA-based sensors reported to date have been evaluated largely on the basis of their ability to detect purified samples, however, and their specificity has rarely been tested. In this study, novel PDAs fabricated on polyvinylidene fluoride (PVDF) strips by photoreaction of composite diacetylene self-assemblies were developed as biosensors, and nonspecific binding to off-target biomolecules was assessed. A mixed PDA surface containing biotin and ethanolamide bound the target, i.e., streptavidin, more specifically than did biotin alone. The optimized PDA biosensor exhibited approximately 2850-fold higher selectivity for streptavidin relative to bovine serum albumin controls. A PDA biosensor that was further prepared showed distinctive signals for the urine of diabetic patients compared to urine samples from healthy/non-diabetic person due to the concentration of microalbuminuria. To our knowledge, this is the first strip-type biosensor fabricated with PDAs and the first PDA-based biosensor that can effectively overcome the problem of nonspecific binding.     

Biophysical mechanisms: a component in the weight of evidence for health effects of power-frequency electric and magnetic fields

Comparatively high exposures to power-frequency electric and magnetic fields produce established biological effects that are explained by accepted mechanisms and that form the basis of exposure guidelines. Lower exposures to magnetic fields (< 1 microT average in the home) are classified as "possibly carcinogenic" on the basis of epidemiological studies of childhood leukemia. This classification takes into consideration largely negative laboratory data. Lack of biophysical mechanisms operating at such low levels also argues against causality. We survey around 20 biophysical mechanisms that have been proposed to explain effects at such low levels, with particular emphasis on plausibility: the principle that to produce biological effects, a mechanism must produce a "signal" larger than the "noise" that exists naturally. Some of the mechanisms are impossible, and some require specific conditions for which there is limited or no evidence as to their existence in a way that would make them relevant to human exposure. Others are predicted to become plausible above some level of field. We conclude that effects below 5 microT are implausible. At about 50 microT, no specific mechanism has been identified, but the basic problem of implausibility is removed. Above about 500 microT, there are established or likely effects from accepted mechanisms. The absence of a plausible biophysical mechanism at lower fields cannot be taken as proof that health effects of environmental electric and magnetic fields are impossible. Nevertheless, it is a relevant consideration in assessing the overall evidence on these fields.