جستجوی مقالات مرتبط با کلیدواژه « Electromagnetic Fields (EMFs) » در نشریات گروه « پزشکی »
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MRI workers are occupationally exposed to static and time-varying gradient magnetic fields. While the 24-hour time-averaged exposure to static magnetic fields is about a few mT, the maximum static field strength can be as high as 500 mT during patient setup. Over the past several years, our laboratory has performed extensive experiments on the health effects of exposure of animal models and humans to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and MRI. This study is to investigate the adverse health effects in MRI workers and also to assess the effect of exposure of MRI workers to static magnetic fields on their cognitive functions. In the first phase of this study a questionnaire was designed to collect information from 120 MRI personnel. The collection of data about the adverse health effects was based on self-reporting by the participants. In the second phase, 47 volunteer university students were asked to continuously move around a 1.5 T MRI scanner. Visual reaction time and working memory tests were performed on all participants before and after the experiment. Forward digit span and backward digit span were used for assessing the working memory. Furthermore, participants were asked to report the symptoms they had experienced during the movement. The first phase of our study showed increased frequencies of adverse health effects in MRI workers. In this study the rates of self-reported symptoms such as a headache, sleep problems, myalgia, palpitation, fatigue, concentration problems, attention problems, nervousness and backpain were possibly affected by static magnetic field. Furthermore we found that reaction time and working memory could be influenced by the movements of the body around a MRI scanner. It can be concluded that movement through a high magnetic field can also lead to some adverse cognitive effects in MRI staff.Keywords: Static Magnetic Fields (SMF), Electromagnetic Fields (EMFs), MRI, Health Effects, Cognitive Functions}
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Miranda-Filho et al. in their recently published paper entitled Cancers of the brain and CNS: global patterns and trends in incidence provided a global status report of the geographic and temporal variations in the incidence of brain and CNS cancers in different countries across continents worldwide. While the authors confirm the role of genetic risk factors and ionizing radiation exposures, they claimed that no firm conclusion could be drawn about the role of exposure to non-ionizing radiation. The paper authored by Miranda-Filho et al. not only addresses a challenging issue, it can be considered as a good contribution in the field of brain and CNS cancers. However, our correspondence addresses a basic shortcoming of this paper about the role of electromagnetic fields and cancers and provides evidence showing that exposure to radiofrequency electromagnetic fields (RF-EMFs), at least at high levels and long durations, can increases the risk of cancer.Keywords: Mobile Phones, Cancer, Radiofrequency (RF), electromagnetic fields (EMFs)}
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BackgroundThe rapidly increasing use of mobile phones has led to public concerns about possible health effects of these popular communication devices. This study is an attempt to investigate the effects of radiofrequency (RF) radiation produced by GSM mobile phones on the insulin release in rats.MethodsForty two female adult Sprague Dawley rats were randomly divided into 4 groups. Group1 were exposed to RF radiation 6 hours per day for 7 days. Group 2 received sham exposure (6 hours per day for 7 days). Groups 3 and 4 received RF radiation 3 hours per day for 7 days and sham exposure (3 hours per day), respectively. The specific absorption rate (SAR) of RF was 2.0 W/kg.ResultsOur results showed that RF radiations emitted from mobile phone could not alter insulin release in rats. However, mild to severe inflammatory changes in the portal spaces of the liver of rats as well as damage in the cells of islet of Langerhans were observed. These changes were linked with the duration of the exposures.ConclusionRF exposure can induce inflammatory changes in the liver as well causing damage in the cells of islet of Langerhans.Keywords: Mobile Phones, Electromagnetic Fields (EMFs), Radiofrequency (RF), Insulin Release, Rat}
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مقدمهدر سال های اخیر، نقش غلظت یون ها و کانال های یونی در فرایند چرخه ی سلول مورد توجه قرار گرفته است. بررسی نقش کانال های یونی در حین مراحل مختلف چرخه ی سلولی، منجر به کشف رابطه ای بین پتانسیل غشای سلول و قدرت تکثیر پذیری سلول شده است. با تغییر پتانسیل غشا در حین وقوع چرخه ی سلولی، میدان الکتریکی متغیری ناشی از تغییرات پتانسیل به وجود می آید که در تقسیم سلول نقش ایفا می کند. در این پژوهش، با اعمال میدان های الکترومغناطیسی با فرکانس و شدت متناسب با میدان به وجود آمده در داخل سلول، تاثیر میدان خارجی بر فرایند تقسیم سلول مورد بررسی قرار گرفت.روش هابا استفاده از یک تولید کننده ی موج متناوب و یک تقویت کننده، میدان های الکترومغناطیسی با سه فرکانس و سه شدت مختلف ایجاد گردید. سلول های MCF-7 (Michigan cancer foundation-7) به مدت 24، 48 و 72 ساعت در معرض این میدان ها قرار گرفتند. به همراه هر گروه تحت تاثیر میدان، یک گروه شاهد نیز در نظر گرفته شد. تاثیر شدت و فرکانس های مورد استفاده بر روی میزان توانایی تکثیر و زنده ماندن رده ی سلولی MCF-7 با استفاده از آزمون MTT [3-(4، 5-dimethylthiazol-2-yl)-2، 5-diphenyltetrazoliumbromide] به دست آمد.یافته هامیزان توقف رشد سلولی برای فرکانس ثابت 125 کیلوهرتز، تحت شدت های 00/1، 75/1 و 50/2 میکروتسلا در مدت زمان 24 ساعت به ترتیب برابر با 40/2، 04/6 و 28/9 درصد بود. میزان توقف رشد سلولی برای فرکانس ثابت 125 کیلوهرتز، تحت شدت های 00/1، 75/1 و 50/2 میکروتسلا در مدت زمان 48 ساعت به ترتیب برابر 61/5، 66/8 و 95/11 درصد بود. میزان توقف رشد سلولی برای فرکانس ثابت 125 کیلوهرتز، تحت شدت های 00/1، 75/1 و 50/2 میکروتسلا در مدت زمان 72 ساعت به ترتیب برابر با 15/11، 26/23 و 82/31 درصد بود. تحت تاثیر شدت ثابت 50/2 میکروتسلا برای فرکانس های 175 و 225 کیلوهرتز در مدت زمان 24 ساعت، میزان توقف رشد سلولی به ترتیب برابر 58/6 و 79/6 درصد بود.نتیجه گیریهر چه مدت زمان اعمال میدان الکترومغناطیسی بیشتر باشد، درصد کاهش تکثیر بیشتر است. از طرفی، با افزایش شدت میدان الکترومغناطیسی اعمال شده نیز تاثیر توقف در تکثیر بیشتر می شود؛ اما با افزایش فرکانس، افزایش قابل قبولی در میزان توقف تکثیر مشاهده نمی شود. با استفاده از نتایج این تحقیق، می توان اعمال میدان در این محدوده ی فرکانسی و شدت را در ایجاد اختلال در فرایند تقسیم سلولی سلول سرطانی MCF-7 موثر دانست.
کلید واژگان: میدان های الکترومغناطیسی, میزان توقف رشد سلولی, پتانسیل غشا}BackgroundThe role of ion channels and ion concentrations in cell cycle events is noted in recent years. Investigation of the role of ion channels during different cell cycle phases tend to discover a relationship between the potential of cell membrane and cell proliferation ability. A variable electric field is produced due to changes in cell membrane potential that plays role in cell division. In this study, inducing external fields with similar intensity and frequency proportion to those fields in cell membrane, the effects of low-frequency electromagnetic fields (ELFs) on viability and proliferation ability of MCF-7 cancer cells was evaluated.MethodsElectromagnetic fields with three different intensities and frequencies were produced using an alternative wave generator and an amplifier. MCF-7 cells were exposed to electromagnetic fields (EMFs) for 24, 48 and 72 hour. Along with each treated cell group, a control group was considered. The influence of electromagnetic fields on cells viability and proliferation was examined using MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide] assay.FindingsThe relative frequency of cell growth inhibition for constant frequency of 125 kHz, for intensities of 1.00, 1.75 and 2.50 microtesla and exposure time of 24 hours was 2.40, 6.04 and 9.28 percent, respectively. For the exposure time of 48 hours and the same frequency and intensities, the relative frequency was 5.61, 8.66 and 11.95 percent, respectively. Under the same conditions and for the exposure time of 72 hours, the relative frequency was 11.15, 23.26 and 31.82 percent, respectively. For constant intensity of 2.5 microtesla and frequencies of 175 and 225 kHz, the relative frequency of cell growth inhibition for 24 hours was 6.58 and 6.79 percent, respectively.ConclusionThe relative frequency of cell proliferation rate reduced with increase of exposure time as well as intensity of electromagnetic fields. However, it does not notably change with increasing frequency. According to finding of this study, it can be concluded that electromagnetic fields with frequency and intensity in this range can disturb the division cycle of MCF-7 cells.Keywords: Electromagnetic fields (EMFs), Cell growth inhibition rate, Membrane potential}
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