Effect of exposure to the edge signal on oxidative stress in brain cell models.

In this study we investigated the effect of the Enhanced Data rate for GSM Evolution (EDGE) signal on cells of three human brain cell lines, SH-SY5Y, U87 and CHME5, used as models of neurons, astrocytes and microglia, respectively, as well as on primary cortical neuron cultures. SXC-1800 waveguides (IT'IS-Foundation, Zürich, Switzerland) were modified for in vitro exposure to the EDGE signal radiofrequency (RF) radiation at 1800 MHz. Four exposure conditions were tested: 2 and 10 W/kg for 1 and 24 h. The production of reactive oxygen species (ROS) was measured by flow cytometry using the dichlorofluorescein diacetate (DCFH-DA) probe at the end of the 24-h exposure or 24 h after the 1-h exposure. Rotenone treatment was used as a positive control. All cells tested responded to rotenone treatment by increasing ROS production. These findings indicate that exposure to the EDGE signal does not induce oxidative stress under these test conditions, including 10 W/kg. Our results are in agreement with earlier findings that RF radiation alone does not increase ROS production.

In vitro and in vivo genotoxicity of radiofrequency fields.

There has been growing concern about the possibility of adverse health effects resulting from exposure to radiofrequency radiations (RFR), such as those emitted by wireless communication devices. Since the introduction of mobile phones many studies have been conducted regarding alleged health effects but there is still some uncertainty and no definitive conclusions have been reached so far. Although thermal effects are well understood they are not of great concern as they are unlikely to result from the typical low-level RFR exposures. Concern rests essentially with the possibility that RFR-exposure may induce non-thermal and/or long-term health effects such as an increased cancer risk. Consequently, possible genetic effects have often been studied but with mixed results. In this paper we review the data on alleged RFR-induced genetic effects from in vitro and in vivo investigations as well as from human cytogenetic biomonitoring surveys. Attention is also paid to combined exposures of RFR with chemical or physical agents. Again, however, no entirely consistent picture emerges. Many of the positive studies may well be due to thermal exposures, but a few studies suggest that biological effects can be seen at low levels of exposure. Overall, however, the evidence for low-level genotoxic effects is very weak.

Circulating Antibodies to IDO/THO Pathway Metabolites in Alzheimer's Disease.

In Alzheimer's disease, indoleamine 2,3-dioxygenase and tryptophan hydroxylase are known to induce an overproduction of neurotoxic compounds, such as quinolinic acid and 3-hydroxykynurenine from the former, and 5-hydroxytryptophol and 5-methoxytryptophol from the latter. Other compounds, such as kynurenic acid, serotonin, and melatonin are produced via the same pathways. An improved ELISA method identified circulating antibodies directed against these compounds, linked to proteins, as previously described for other chronic diseases. This describes how only the A isotype of circulating immunoglobulins recognized a pattern of conjugated tryptophan metabolites in the sera of Alzheimer patients. These data indirectly confirmed the involvement of tryptophan derivatives in the pathogenic processes of Alzheimer's disease. Further studies are required to evaluate the relevance of these antibody patterns in monitoring this disease.

A confirmation study of Russian and Ukrainian data on effects of 2450 MHz microwave exposure on immunological processes and teratology in rats.

In a series of Russian and Ukrainian papers published from 1974-1986, it was reported that 30-day whole-body exposures to continuous-wave (CW) radiofrequency (RF) radiation at 2375 MHz and 5 W/m(2) disrupted the antigenic structure of rat brain tissue. The authors suggested that this action caused an autoimmune response in exposed animals. Moreover, these studies reported that blood serum from exposed rats injected into intact nonexposed female rats on the 10th day of pregnancy led to increased postimplantation embryo mortality and decreased fetus size and body weight. Because the results of these studies served in part as the basis for setting exposure limits in the former USSR, it was deemed necessary to perform confirmation studies, using modern dosimetric and biological methods. In our study, a new system was constructed to expose free-moving rats under far-field conditions. Whole-body and brain-averaged specific absorption rates (SARs) were calculated. All results, using ELISA and classic teratology end points, were negative in our laboratory. On the basis of this investigation, we conclude that, under these exposure conditions (2450 MHz, CW, 7 h/day, 30 days, 0.16 W/kg whole-body SAR), RF-radiation exposure had no influence on several immune and degenerative parameters or on prenatal development.

Evaluation of the potential genotoxic effects of rTMS on the rat brain and current density mapping.

OBJECTIVE: The objectives of this work were: (i) to evaluate the relevance for clinical studies of repetitive transcranial magnetic stimulation (rTMS) investigations on rats, (ii) to investigate the occurrence of DNA damage in rat brain cells following rTMS under conditions similar to those used in clinical treatment of depression. METHODS: Rats were exposed to 2000 magnetic pulses at 100% of motor threshold (MT). Software, written to take detailed anatomical and conductivity data into account, was used to map current density in the rat brain. A method was developed for standardizing magnetic pulse efficacy to facilitate comparison with other rTMS studies. Genotoxicity was explored using the alkaline comet assay on rat brain cells, measuring Olive moment and %DNA in the tail. RESULTS: The current density was ca. 6.6 A/m2 in the motor cortex at MT (Motor Cortex Threshold Densities: MCTDs), 5.2 A/m2 in the brain (range 0-17 A/m2), and 2.0 A/m2 at prefrontal cortex. Similar standard MCTDs were found in rats and humans. Concerning the comet assay, both Olive moment and %DNA in the tail, there was no statistically-significant difference between rTMS-exposed and sham-exposed brain cell samples. In contrast, significant increases in both parameters were detected in positive controls. CONCLUSIONS: Under the assumptions developed in the discussion, these data showed no evidence that the standard current density at motor threshold in human motor cortex would differ from that in rats. Furthermore, there was no evidence of DNA damage in rat brain cells following a single scheme of rTMS, under conditions similar to the clinical treatment of depression. SIGNIFICANCE: This study supports the use of rats as a model for studying the bioeffects of rTMS (molecular targets, action mechanisms, toxicology, etc.) and suggests that a single rTMS scheme, similar to that used daily in the treatment of depression, is not genotoxic.

In vitro study of the stress response of human skin cells to GSM-1800 mobile phone signals compared to UVB radiation and heat shock.

The evolution of mobile phone technology is toward an increase of the carrier frequency up to 2.45 GHz. Absorption of radiofrequency (RF) radiation becomes more superficial as the frequency increases. This increasingly superficial absorption of RF radiation by the skin, which is the first organ exposed to RF radiation, may lead to stress responses in skin cells. We thus investigated the expression of three heat-shock proteins (HSP70, HSC70, HSP27) using immunohistochemistry and induction of apoptosis by flow cytometry on human primary keratinocytes and fibroblasts. A well-characterized exposure system, SXC 1800, built by the IT'IS foundation was used at 1800 MHz, with a 217 Hz modulation. We tested a 48-h exposure at an SAR of 2 W/kg (ICNIRP local exposure limit). Skin cells were also irradiated with a 600 mJ/cm2 single dose of UVB radiation and subjected to heat shock (45 degrees C, 20 min) as positive controls for apoptosis and HSP expression, respectively. The results showed no effect of a 48-h GSM-1800 exposure at 2 W/kg on either keratinocytes or fibroblasts, in contrast to UVB-radiation or heat-shock treatments, which injured cells. We thus conclude that the GSM-1800 signal does not act as a stress factor on human primary skin cells in vitro.

[Evaluation of the risk of overheating and displacement of orthodontic devices in magnetic resonance imaging]. / Evaluation des risques d'échauffement et de déplacement des appareils orthodontiques en imagerie par résonance magnétique.

The use of magnetic resonance imaging (MRI) in the exploration of the orofacial region of patients who have orthodontic appliances can be disturbed by artifacts, with a theoretical risk of displacement and overheating of the different materials used in odontology. The purpose of this study was to evaluate the thermal effects and the risk of displacement induced by MRI on certain metallic devices used in orthodontics. The results show a very moderate increase in temperature of the materials during MRI exposure, less than 1 degrees C, in particular in the metal wire linking the brackets. The maximal forces observed were on the order of 0.27 N. The risk of detachment and displacement seems to be nonexistent at 1.5 Tesla when the usual recommendations are respected. Temporary removal of the wire and verification of the adhesive is recommended. However, priority should be given to nonmagnetic or slightly magnetic material to limit artifacts as much as possible when exploring the head region.

Effect of GSM-900 and -1800 signals on the skin of hairless rats. I: 2-hour acute exposures.

PURPOSE: The acute influence on the skin of non-ionizing electromagnetic fields in the radiofrequency (RF) range used in mobile telephony has not been widely studied to date. The purpose of this work was to determine whether the cells of hairless rat skin are affected by acute local exposure to Global System for Mobile Communication: GSM-900 or -1800 RadioFrequency Radiation (RFR). MATERIALS AND METHODS: Hairless female rats were exposed or sham-exposed for 2 h to GSM-900 or -1800 signals, using a loop-antenna located on the right part of the rats' back. The local Specific Absorption rate (SAR) at skin level was ca. 5 W/kg (5.8+/-0.4 and 4.8+/-0.4 W/kg at 900 and 1800 MHz, respectively). A skin biopsy was done at the end of the experiment not only at the location of exposure, but also on the symmetrical part of the back. RESULTS: Analysis of skin sections using Hematoxylin Eosin Saffron (HES) coloration showed no difference in skin thickness or apparent cell toxicity (with no sign of cellular necrosis) among the animal groups. Histological analysis of the epidermis showed that the ratio between cells expressing the antigen Ki-67 (cellular proliferation marker) and the total number of cells remained within the range of normal proliferation ratio for the exposed side of the animal. No Ki-67 labelling was observed at the dermis level. Results on filaggrin, collagen and elastin levels also showed an insignificant influence of RFR. CONCLUSIONS: These results do not demonstrate any major physical and histological variations at skin level induced by RFR used in mobile telephony.

Effect of GSM-900 and -1800 signals on the skin of hairless rats. II: 12-week chronic exposures.

PURPOSE: The purpose of this work was to determine whether the cellular components of Hairless-rat skin are affected by a chronic local exposure to non-ionizing radiations of Global Mobile Phone System: GSM-900 or -1800 radiations at specific absorption rate (SAR) 2.5 and 5 W/kg. MATERIALS AND METHODS: A selected part of the right back of five-week old female hairless rats was exposed or sham exposed (n = 8) for 2 h per day, 5 days a week, for 12 weeks to GSM-900 or -1800 signals using a loop-antenna. At the end of the experiment, skin biopsies were taken. RESULTS: Analyses of skin sections using hematoxylin eosin saffron (HES) coloration showed no significant difference in skin thickness among the groups. Immunohistochemical analysis of basal lamella cells in radiofrequency radiation (RFR)-exposed epidermis showed that the ratio of the antigen Ki-67 (cellular proliferation marker) positive cells to total lamella cells remained within the range of the normal proliferation ratio. No significant differences in the level of filaggrin, collagen, and elastin were observed among the different groups. CONCLUSIONS: The results of this 12-week chronic study do not demonstrate major histological variations in the skin of hairless rats exposed to RFR used in mobile telephony (GSM-900 or -1800).

Circulating antibodies to cysteinyl catecholamines in amyotrophic lateral sclerosis and Parkinson's disease patients.

Amyotrophic lateral sclerosis (ALS) is a degenerative disease of unknown aetiology, affecting motor neurons. Many radical species, such as O(2)(-) NO, and ONOO(-), and lipoperoxidative products are involved, but not all processes have yet been identified. It is known that the oxidation of catecholamines leads to quinone formation. These orthoquinones react with the sulphhydril group of cysteine to produce neurotoxic cysteinyl catecholamine (Cyst-CA) neo-compounds. We synthesised Cyst-CA in order to mimic their endogenous formation. Using the ELISA method, circulating antibodies to Cyst-CA were found in sporadic ALS sera. First, the antibody titres were compared to those of controls and patients with other neurodegenerative diseases. Significant antibody levels were found for Cyst-CA. The G and A isotypes were found but not the M isotype. A second series of experiments showed that A and G titres were elevated, depending on the type of Cyst-CA and the onset of the disease. IgG to Cyst-3,4-dihydroxyphenylalanine (L-DOPA) were present in cases of bulbar and upper limb onsets. IgA to Cyst-homovanillic acid (HVA), Cyst-adrenaline (A), and Cyst-dopamine (DA) were found in lower limb onset. These results indirectly show that: 1) the oxidation of CA and the formation of Cyst-CA may be involved in ALS; 2) these radical processes have different targets depending on the onset of the disease.

Antibodies directed against nitrosylated neoepitopes in sera of patients with human African trypanosomiasis.

Antibodies directed against nitrosylated epitopes have been found in sera from patients suffering from human African trypanosomiasis (HAT) but not in sera from control subjects living in the same endemic area or African control subjects living in France. We conjugated amino acids to albumin by glutaraldehyde (conjugates) and then nitrosylated the conjugates. Both conjugates and nitrosylated conjugates were analysed by enzyme-linked immunosorbent assay (ELISA). We detected antibodies directed against nitrosylated L-cysteine and L-tyrosine conjugates; antibody levels were higher in stage II patients than in stage I. Patients with severe clinical signs had higher antibody levels, and antibody levels were highest in patients with major neurological signs. Antibody response was only associated with the IgM isotype. We evaluated antibody specificity and avidity by competition experiments using conjugates and nitrosylated conjugates. Avidity was around 2 x10(-6) m for the S-nitroso-cysteine epitope and 2 x 10(-8) m for the S-nitroso-tyrosine epitope. Detection of circulating antibodies to S-nitroso-cysteine and S-nitroso-tyrosine epitopes provides indirect evidence for nitric oxide (NO) involvement in HAT and their levels are correlated with disease severity.

Rapporteur report: interaction mechanisms.

Three papers were presented in the session on the interaction mechanisms of weak electric fields induced in the body by exposure to extremely low frequency electromagnetic fields with biological systems, particularly the central nervous system. The first paper considered the plausibility of various interaction mechanisms. The second paper dealt with voltage gated ion channels and the way in which they could be involved in the generation of biological effects. The final paper described a kinetic proofreading mechanism, sensitive, in theory, to very low level perturbations. These papers were discussed in a plenary session and in one breakout group, all of which are briefly summarised in this report.

Effects of ELF and static magnetic fields on calcium oscillations in islets of Langerhans.

Several experimental studies have produced contradictory results on the effects of extremely low frequency (ELF) magnetic fields on cellular processes involving calcium ions. Furthermore, the few positive results have not been independently replicated. In most of these studies, isolated cells were used. Our study used mouse islets of Langerhans, in which very regular oscillations of calcium concentration can be observed at length. These oscillations are sustained by processes that imply energetic and inter-intracellular communication. Various magnetic fields were applied, either sinusoidal at different frequencies (50 Hz or multiples of the natural oscillation frequency) at 0.1 or 1 mT or static at 1 mT. Islets were also exposed to "cyclotron resonance" conditions. There was neither alteration of the fundamental oscillation frequency nor the degree of organisation under all exposure conditions. Using this sensitive model, we could not show new evidence of alterations of calcium processes under exposure to various magnetic fields.

Effects of GSM-900 microwaves on the experimental allergic encephalomyelitis (EAE) rat model of multiple sclerosis.

The effects of acute exposure to GSM-900 microwaves (900 MHz, 217 Hz pulse modulation) on the clinical parameters of the acute experimental allergic encephalomyelitis (EAE) model in rats were investigated in two independent experiments: rats were either habituated or nonhabituated to the exposure restrainers. EAE was induced with a mixture of myelin basic protein and Mycobacterium tuberculosis. Female Lewis rats were divided into cage control, sham exposed, and two groups exposed either at 1.5 or 6.0 W/kg local specific absorption rate (SAR averaged over the brain) using a loop antenna placed over their heads. There was no effect of a 21 day exposure (2 h/day) on the onset, duration, and termination of the EAE crisis.

Interaction of cationic colloids at the surface of J774 cells: a kinetic analysis.

We have characterized the binding of multilamellar colloids to J774 cells. Cationic colloids were shown to bind much more efficiently than neutral ones. Particle uptake by cells was followed by flow cytometry and fluorescence microscopy. Analysis of the kinetics of uptake of cationic particles indicated that binding on the cell surface occurred with two characteristic times. Analysis of the dissociation properties allowed discriminating between several alternative models for adsorption and led us to propose a mechanism that involved two independent classes of binding sites on the cell surface. One class of sites appeared to be governed by a classic mass action law describing a binding equilibrium. The other sites were populated irreversibly by particles made of 10% cationic lipids. This was observed in the absence of endocytosis, under conditions where both the equilibrium and the irreversible binding occurred at the cell surface. We determined the rate constants for the different steps. We found that the reversible association occurred with a characteristic time of the order of tens of seconds, whereas the irreversible binding took a hundred times longer. The presence of serum proteins in the incubation medium did not drastically affect the final uptake of the particles. In contrast, the capture of the particles by cells significantly dropped when the fraction of positively charged lipids contained in the colloids was decreased from 10% to 5%. Finally, the results will be discussed within a comprehensive model where cationic particles find labile binding sites in the volume of the pericellular network (glycocalyx and extracellular matrix) and less-accessible irreversible binding sites at the cell membrane itself.

L-Arginine availability modulates local nitric oxide production and parasite killing in experimental trypanosomiasis.

Nitric oxide (NO) is an important effector molecule of the immune system in eliminating numerous pathogens. Peritoneal macrophages from Trypanosoma brucei brucei-infected mice express type II NO synthase (NOS-II), produce NO, and kill parasites in the presence of L-arginine in vitro. Nevertheless, parasites proliferate in the vicinity of these macrophages in vivo. The present study shows that L-arginine availability modulates NO production. Trypanosomes use L-arginine for polyamine synthesis, required for DNA and trypanothione synthesis. Moreover, arginase activity is up-regulated in macrophages from infected mice from the first days of infection. Arginase competes with NOS-II for their common substrate, L-arginine. In vitro, arginase inhibitors decreased urea production, increased macrophage nitrite production, and restored trypanosome killing. In vivo, a dramatic decrease in L-arginine concentration was observed in plasma from infected mice. In situ restoration of NO production and trypanosome killing were observed when excess L-arginine, but not D-arginine or L-arginine plus N(omega)-nitro-L-arginine (a NOS inhibitor), was injected into the peritoneum of infected mice. These data indicate the role of L-arginine depletion, induced by arginase and parasites, in modulating the L-arginine-NO pathway under pathophysiological conditions.

Effects of 100 mT time varying magnetic fields on the growth of tumors in mice.

The effects of 100-mT, 0.8-Hz square-wave magnetic fields on the growth of chemically induced tumors in mice were investigated. Tumors were initiated using one injection of benzo(a)pyrene (either 0.2 mg or 2.0 mg/animal). Male and female mice (Balb/c, C3H and C57/bl/6 strains) were exposed for 8 h/day from the onset of tumor until death or until the tumor volume reached a predetermined volume. Statistically significant decrease in the rate of tumor growth and increase in survival were observed in all cases. Results are discussed in terms of previous published work and of possible mechanisms.

No effect of short-term exposure to GSM-modulated low-power microwaves on benzo(a)pyrene-induced tumours in rat.

PURPOSE: In view of current interest in the biological effects of amplitude-modulated microwaves arising from the rapid development of mobile communications, the effects of low-level microwaves on cancer development were investigated using a rat sarcoma model. MATERIALS AND METHODS: Two-month-old female Sprague-Dawley rats were treated by injection of benzo(a)pyrene and irradiated with GSM (Global System for Mobile)-modulated 900-MHz microwaves in an anechoic chamber at 55 or 200 microW cm(-2) (75 and 270 mW kg(-1) average whole-body SAR, 2h daily for 2 weeks). Rats were exposed from day 20, 40 or 75 after carcinogen injection. Additional groups of rats were sham-exposed in a second anechoic chamber. Anti-phosphatidylinositol autoantibody levels were evaluated in sera to monitor malignant transformation. RESULTS: Microwave exposure had no effect on the development of tumours. No acceleration or delays in tumour onset were observed. Animal survival was not modified and serum autoantibody levels were similar in exposed and sham-exposed groups. CONCLUSION: Low-level GSM microwave exposure of rat bearing benzo(a)pyrene-induced tumours had no effect on auto-antibody levels, tumour appearance and survival. The low exposure levels used here correspond to exposure limits for whole-body exposure of humans.

Detection of nitrosylated epitopes in Trypanosoma brucei gambiense by polyclonal and monoclonal anti-conjugated-NO-cysteine antibodies.

Activated macrophages with the Calmette/Guérin bacillus (BCG) have a cytotoxic/cytostatic effect on the extracellular parasite, Trypanosoma brucei gambiense. This effect was inhibited when the NO-synthase inhibitor NG-monomethyl-L-arginine (NMMA; 0.5 mM) was added to the culture media. Using an immunocytochemical method with rabbit polyclonal or mouse monoclonal antibodies directed against conjugated nitroso-epitopes (anti-conjugated-NO-cysteine), nitrosylated antigens were visualized in fixed trypanosomes. These results suggest that NO was synthesized by the activated macrophages and that it reacted with some parasitic proteins containing cysteine. The release of NO bound to parasitic proteins may cause the killing of trypanosomes. The immunoreactivity was positive when the trypanosomes were obtained from the supernatant of the BCG-activated macrophages that contains BSA (4 mg/mL). In contrast, the parasites cocultured with non-activated macrophages remained completely viable, and, the immunoreactivity was completely negative.

In vivo exposure of rats to GSM-modulated microwaves: flow cytometry analysis of lymphocyte subpopulations and of mitogen stimulation.

The effects of GSM-modulated microwaves on lymphocyte sub-populations of Sprague-Dawley rats and their normal mitogenic responses were investigated using flow cytometry analysis and a colorimetric method. No alterations were found in the surface phenotype of splenic lymphocytes or in their mitogenic activity, indicating that low-level pulsed microwaves do not seem to affect the integrity of the immune system.