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Radiofrequency Field (radiofrequency + field)
Selected AbstractsUltrastructural Changes in Axons Following Exposure to Pulsed Radiofrequency FieldsPAIN PRACTICE, Issue 6 2009Serdar Erdine MD Abstract Pulsed radiofrequency (PRF) fields applied by an electrode to neural structures, such as the peripheral sensory nociceptor axons and dorsal root ganglion, are clinically effective in reducing pain and other neuropathic syndromes. However, a full understanding of the underlying mechanisms by which this occurs has not yet been clarified. In this study, PRF is applied to the afferent axons of the sciatic nerves of rats. A standard radiofrequency (RF) electrode and RF generator is used to apply the RF signal output to the sciatic nerve using standard PRF parameters that have been successfully used in clinical practice. The ultrastructure of the treated axons is observed after 10 days by electron microscopy. A control, sham application is simultaneously applied to the contralateral sciatic nerve to provide a statistical differential comparison. It is found that the internal ultrastructural components of the axons show microscopic damage after PRF exposure, including: abnormal membranes and morphology of mitochondria, and disruption and disorganization of microfilaments and microtubules. The damage appears to be more pronounced for C-fibers than for A-delta and A-beta fibers. The results are discussed in terms of internal electric field strengths and thermodynamic parameters. [source] Radiofrequency fields and teratogenesis,BIOELECTROMAGNETICS, Issue S6 2003Louis N. Heynick Abstract Experimental studies that sought teratologic effects or developmental abnormalities from exposure to radiofrequency electromagnetic fields (RFEMF) in the range 3 kHz,300 GHz are critically reviewed for their possible consequences on human health. Those studies were conducted on beetles, birds, rodents, and nonhuman primates. Collectively, those experimental studies indicate that teratologic effects can occur only from exposure levels that cause biologically detrimental increases in body temperature. No reliable experimental evidence was found for nonthermal teratologic effects; rodents, mouse fetuses, and perinatal mice are more susceptible to such effects than rats. The primary confirmed effect in rats at high RFEMF levels was initial weight deficits in fetuses and neonates that decreased with infant growth. More generally from findings with pregnant mammals, exposures at RFEMF levels far higher than those permitted under the IEEE human exposure guidelines are necessary to reach or exceed cited experimental thresholds for maternal temperature increases. Some results indicated that the levels necessary to cause such effects in pregnant mammals could exceed those lethal to the dams. In a behavioral study of squirrel monkeys, no effects were observed on usual dam-offspring interactions or EEGs, but unexpected deaths of a number of offspring had occurred. However, this finding was not confirmed in a study solely on infant death using a larger number of subjects for greater statistical validity. Also reviewed were epidemiologic studies of various human populations considered to have been chronically exposed to environmental levels of RFEMF. Early studies on the incidence of congenital anomalies yielded no credible evidence that chronic exposure of pregnant women or of fathers exposed to RFEMF from nearby sources at levels below those guidelines would cause any anomalies in their offspring. The findings of studies on pregnancy outcomes of female physiotherapists occupationally exposed while treating patients with RFEMF were mixed, but taken collectively, the findings were negative. Bioelectromagnetics Supplement 6:S174,S186, 2003. Published 2003 Wiley-Liss, Inc. [source] T1 corrected B1 mapping using multi-TR gradient echo sequencesMAGNETIC RESONANCE IN MEDICINE, Issue 3 2010Tobias Voigt Abstract This work presents a new approach toward a fast, simultaneous amplitude of radiofrequency field (B1) and T1 mapping technique. The new method is based on the "actual flip angle imaging" (AFI) sequence. However, the single pulse repetition time (TR) pair used in the standard AFI sequence is replaced by multiple pulse repetition time sets. The resulting method was called "multiple TR B1/T1 mapping" (MTM). In this study, MTM was investigated and compared to standard AFI in simulations and experiments. Feasibility and reliability of MTM were proven in phantom and in vivo experiments. Error propagation theory was applied to identify optimal sequence parameters and to facilitate a systematic noise comparison to standard AFI. In terms of accuracy and signal-to-noise ratio, the presented method outperforms standard AFI B1 mapping over a wide range of T1. Finally, the capability of MTM to determine T1 was analyzed qualitatively and quantitatively, yielding good agreement with reference measurements. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Evaluation of genotoxic effects in human leukocytes after in vitro exposure to 1950 MHz UMTS radiofrequency fieldBIOELECTROMAGNETICS, Issue 3 2008O. Zeni Abstract In the present study the third generation wireless technology of the Universal Mobile Telecommunication System (UMTS) signal was investigated for the induction of genotoxic effects in human leukocytes. Peripheral blood from six healthy donors was used and, for each donor, intermittent exposures (6 min RF on, 2 h RF off) at the frequency of 1950 MHz were conducted at a specific absorption rate of 2.2 W/kg. The exposures were performed in a transverse electro magnetic (TEM) cell hosted in an incubator under strictly controlled conditions of temperature and dosimetry. Following long duration intermittent RF exposures (from 24 to 68 h) in different stages of the cell cycle, micronucleus formation was evaluated by applying the cytokinesis block micronucleus assay, which also provides information on cell division kinetics. Primary DNA damage (strand breaks/alkali labile sites) was also investigated following 24 h of intermittent RF exposures, by applying the alkaline single cell gel electrophoresis (SCG)/comet assay. Positive controls were included by treating cell cultures with Mitomycin-C and methylmethanesulfonate for micronucleus and comet assays, respectively. The results obtained indicate that intermittent exposures of human lymphocytes in different stages of cell cycle do not induce either an increase in micronucleated cells, or change in cell cycle kinetics; moreover, 24 h intermittent exposures also fail to affect DNA structure of human leukocytes soon after the exposures, likely indicating that repairable DNA damage was not induced. Bioelectromagnetics 29:177,184, 2008. © 2007 Wiley-Liss, Inc. [source] Proliferation and apoptosis in a neuroblastoma cell line exposed to 900 MHz modulated radiofrequency fieldBIOELECTROMAGNETICS, Issue 3 2006P. Merola Abstract The aim of this study was to examine whether a modulated radiofrequency of the type used in cellular phone communications at a specific absorption rate (SAR) higher than International Commission on Non-ionizing Radiation Protection (ICNIRP) reference level for occupational exposure, could elicit alterations on proliferation, differentiation, and apoptosis processes in a neuroblastoma cell line. The cell line was exposed for 24, 48, and 72 h to 900 MHz radiofrequency and proliferation and differentiation were tested by WST-I assay and by a molecular analysis of specific markers, two oncogenes and a cytoskeleton protein, in exponential growth phase and in synchronized cell cultures. Apoptosis was evaluated by caspase activation analysis and by molecular detection of Poly (ADP-ribose) polimerase (PARP) cleavage. Combined exposures to radiofrequency and to the differentiative agent retinoic acid or to the apoptotic inducer camptothecin were carried out to test possible interference between electromagnetic field and chemical agents. Overall our data suggest that 900 MHz radiofrequency exposure up to 72 h does not induce significant alterations in the three principal cell activities in a neuroblastoma cell line. Bioelectromagnetics 27:164,171, 2006. © 2006 Wiley-Liss, Inc. [source] Radiofrequency exposure and mammalian cell toxicity, genotoxicity, and transformationBIOELECTROMAGNETICS, Issue S6 2003Martin L. Meltz Abstract The published in vitro literature relevant to the issue of the possible induction of toxicity, genotoxicity, and transformation of mammalian cells due to radiofrequency field (RF) exposure is examined. In some instances, information about related in vivo studies is presented. The review is from the perspective of technical merit and also biological consistency, especially with regard to those publications reporting a positive effect. The weight of evidence available indicates that, for a variety of frequencies and modulations with both short and long exposure times, at exposure levels that do not (or in some instances do) heat the biological sample such that there is a measurable increase in temperature, RF exposure does not induce (a) DNA strand breaks, (b) chromosome aberrations, (c) sister chromatid exchanges (SCEs), (d) DNA repair synthesis, (e) phenotypic mutation, or (f) transformation (cancer-like changes). While there is limited experimental evidence that RF exposure induces micronuclei formation, there is abundant evidence that it does not. There is some evidence that RF exposure does not induce DNA excision repair, suggesting the absence of base damage. There is also evidence that RF exposure does not inhibit excision repair after the induction of thymine dimers by UV exposure, as well as evidence that indicates that RF is not a co-carcinogen or a tumor promoter. The article is in part a tutorial, so that the reader can consider similarities and discrepancies between reports of RF-induced effects relative to one another. Bioelectromagnetics Supplement 6:S196,S213, 2003. © 2003 Wiley-Liss, Inc. [source] Radiofrequency field-induced thermal cytotoxicity in cancer cells treated with fluorescent nanoparticles,CANCER, Issue 13 2010Evan S. Glazer MD Abstract BACKGROUND: Nonionizing radiation, such as radiofrequency field and near infrared laser, induces thermal cytotoxicity in cancer cells treated with gold nanoparticles. Quantum dots are fluorescent semiconducting nanoparticles that were hypothesized to induce similar injury after radiofrequency field irradiation. METHODS: Gold nanoparticles and 2 types of quantum dot (cadmium-selenide and indium-gallium-phosphide) conjugated to cetuximab (C225), a monoclonal antibody against human epidermal growth factor receptor (EGFR)-1, demonstrated concentration-dependent heating in a radiofrequency field. The authors investigated the effect of radiofrequency field exposure after targeted nanoparticle treatment in a coculture of 2 human cancer cell lines that have differential EGFR-1 expression (a high-expressing pancreatic carcinoma, Panc-1, and a low-expressing breast carcinoma, Cama-1). RESULTS: Radiofrequency revealed that Panc-1 or Cama-1 cells not containing gold nanoparticles or quantum dots had a viability of >92%. The viability of Panc-1 cells exposed to the radiofrequency field after treatment with 50 nM Au-C225 was 39.4% ± 8.3% without injury to bystander Cama-1 cells (viability was 93.7% ± 1.0%; P , .0006). Panc-1 cells treated with targeted cadmium-selenide quantum dots were only 47.5% viable after radiofrequency field exposure (P<.0001 compared with radiofrequency only Panc-1 control cells). Targeted indium-gallium-phosphide quantum dots decreased Panc-1 viability to 58.2% ± 3.4% after radiofrequency field exposure (P = ,.0004 compared with Cama-1 and Panc-1 controls). CONCLUSIONS: The authors selectively induced radiofrequency field cytotoxicity in Panc-1 cells without injury to bystander Cama-1 cells using EGFR-1,targeted nanoparticles, and demonstrated an interesting bifunctionality of fluorescent nanoparticles as agents for both cancer cell imaging and treatment. Cancer 2010. © 2010 American Cancer Society. [source] Mobile phone use and location of glioma: A case,case analysisBIOELECTROMAGNETICS, Issue 3 2009Hanna Hartikka Abstract We assessed a new approach for evaluating the glioma risk among users of mobile phones to focus on the part of the brain most heavily exposed to radiofrequency electromagnetic fields from mobile phones. The tumor midpoint was defined from radiological imaging. A case,case analysis with 99 gliomas was performed using logistic regression. The exposed cases were those with the tumor mid-point within 4.6 cm from the line between the mouth and the external meatus of the ear, representing the most likely location of the mobile phone (the source of exposure). Alternative analyses based on various indicators of mobile phone use as the outcome were also carried out. The majority of cases were regular mobile phone users. A slightly higher proportion of gliomas among mobile phone users than non-users occurred within 4.6 cm from the presumed location of the mobile phone (28% vs. 14%). Modestly elevated odds ratios were observed for several indicators of mobile phone use, but without an exposure gradient. The highest odds ratios were found for contralateral and short-term use. Our results, though limited by the small sample size, demonstrate that detailed information on tumor location allows evaluation of the risk related to the most heavily exposed part of the brain, representing direct evaluation of the possible local carcinogenic effects of the radiofrequency fields. However, field strength varies between users and over time also within a given anatomic site, due to the output power of the phone. Collaborative analysis of a larger sample is planned. Bioelectromagnetics 30:176,182, 2009. © 2009 Wiley-Liss, Inc. [source] Is fertility reduced among men exposed to radiofrequency fields in the Norwegian Navy?BIOELECTROMAGNETICS, Issue 5 2008Ole J. Møllerløkken Abstract The effects of radiofrequency fields on human health are not well understood, and public concern about negative health effects has been rising. The aim of this study was to examine the relationship between workers exposed to electromagnetic fields and their reproductive health. We obtained data using a questionnaire in a cross-sectional study of naval military men, response rate 63% (n,=,1487). We asked the respondents about exposure, lifestyle, reproductive health, previous diseases, work and education. An expert group categorized the work categories related to electromagnetic field exposure. We categorized the work categories "tele/communication," "electronics" and "radar/sonar" as being exposed to electromagnetic fields. Logistic regression adjusted for age, ever smoked, military education, and physical exercise at work showed increased risk of infertility among tele/communication odds ratio (OR,=,1.72, 95% confidence interval 1.04,2.85), and radar/sonar odds ratio (OR,=,2.28, 95% confidence interval 1.27,4.09). The electronics group had no increased risk. This study shows a possible relationship between exposure to radiofrequency fields during work with radiofrequency equipment and radar and reduced fertility. However, the results must be interpreted with caution. Bioelectromagnetics 29:345,352, 2008. © 2008 Wiley-Liss, Inc. [source] Evaluation of genotoxic effects in human peripheral blood leukocytes following an acute in vitro exposure to 900 MHz radiofrequency fieldsBIOELECTROMAGNETICS, Issue 4 2005O. Zeni Abstract Human peripheral blood leukocytes from healthy volunteers have been employed to investigate the induction of genotoxic effects following 2 h exposure to 900 MHz radiofrequency radiation. The GSM signal has been studied at specific absorption rates (SAR) of 0.3 and 1 W/kg. The exposures were carried out in a waveguide system under strictly controlled conditions of both dosimetry and temperature. The same temperature conditions (37.0,±,0.1 °C) were realized in a second waveguide, employed to perform sham exposures. The induction of DNA damage was evaluated in leukocytes by applying the alkaline single cell gel electrophoresis (SCGE)/comet assay, while structural chromosome aberrations and sister chromatid exchanges were evaluated in lymphocytes stimulated with phytohemagglutinin. Alterations in kinetics of cell proliferation were determined by calculating the mitotic index. Positive controls were also provided by using methyl methanesulfonate (MMS) for comet assay and mitomycin-C (MMC), for chromosome aberration, or sister chromatid exchange tests. No statistically significant differences were detected in exposed samples in comparison with sham exposed ones for all the parameters investigated. On the contrary, the positive controls gave a statistically significant increase in DNA damage in all cases, as expected. Thus the results obtained in our experimental conditions do not support the hypothesis that 900 MHz radiofrequency field exposure induces DNA damage in human peripheral blood leukocytes in this range of SAR. Bioelectromagnetics 26:258,265, 2005. © 2005 Wiley-Liss, Inc. [source] Subjective symptoms among mobile phone users,A consequence of absorption of radiofrequency fields?BIOELECTROMAGNETICS, Issue 3 2003Jonna Wilén Abstract In a previous epidemiological study, where we studied the prevalence of subjective symptoms among mobile phone (MP) users, we found as an interesting side finding that the prevalence of many of the subjective symptoms increased with increasing calling time and number of calls per day. In this extrapolative study, we have selected 2402 people from the epidemiological study who used any of the four most common GSM MP. We used the information about the prevalence of symptoms, calling time per day, and number of calls per day and combined it with measurements of the Specific Absorption Rate (SAR). We defined three volumes in the head and measured the maximum SAR averaged over a cube of 1 g tissue (SAR1g) in each volume. Two new exposure parameters Specific Absorption per Day (SAD) and Specific Absorption per Call (SAC) have been devised and are obtained as combinations of SAR, calling time per day, and number of calls per day, respectively. The results indicates that SAR values >0.5 W/kg may be an important factor for the prevalence of some of the symptoms, especially in combination with long calling times per day. Bioelectromagnetics 24:152,159, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||