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1.
We studied effects of alternating magnetic fields on the embryonic and fetal development of rats. Mated females of the Han:Wistar-strain were sham exposed or exposed continuously to a 50-Hz field or to a 20,000 pulse-per-second (pps) sawtooth magnetic field from day 0 to day 20 of pregnancy for 24 h/day until necropsied on day 20. The respective peak-to-peak intensities of the fields were 35.6 μT (sinewave) and 15.0 μT (sawtooth). Each treatment group contained 72 bred females. Control animals were kept under the same conditions without the magnetic field. No adverse effects were seen in the dams. The mean numbers of implantations and living fetuses per litter were statistically significantly increased in the 50-Hz group. There were, however, three total resorptions of litters in dams of the control group, which contributed to the difference in the number of living fetuses. The corrected body-mass gains (gains without uterine content) of dams were similar in all groups. Pregnancy rates, incidences of resorptions. late fetal deaths, and fetal body masses were similar in all groups. The incidence of fetuses with minor skeletal anomalies was statistically significantly increased in both exposed groups. Only one serious malformation (anophthalmia, sawtooth-exposed group) and a few minor visceral malformations were found. In conclusion, the magnetic fields used in this study did not increase the incidence of major malformations or resorptions in Wistar rats. The increased number of skeletal anomalies and implantations we observed indicates, however, that some developmental effects in rats may attend exposure to time-varying magnetic fields. © 1993 Wiley-Liss. Inc. 相似文献
2.
Hannele Huuskonen Jukka Juutilainen Antero Julkunen Jorma Mki-Paakkanen Hannu Komulainen 《Bioelectromagnetics》1998,19(8):477-485
Effects of alternating magnetic fields (MFs) on the embryonic and fetal development in CBA/Ca mice were studied. Mated females were exposed continuously to a sinusoidal 50 Hz (13 μT or 0.13 mT root mean square) or a sawtooth 20 kHz (15 μT peak-to-peak) MF from day 0 to day 18 of pregnancy for 24 h/day until necropsied on day 18. Control animals were kept under the same conditions without the MF. MFs did not cause maternal toxicity. No adverse effects were seen in maternal hematology and the frequency of micronuclei in maternal bone marrow erythrocytes did not change. The MFs did not increase the number of resorptions or fetuses with major or minor malformations in any exposure group. The mean number of implantations and living fetuses per litter were similar in all groups. The corrected weight gain (weight gain without uterine content) of dams, pregnancy rates, incidences of resorptions and late fetal deaths, and fetal body weights were similar in all groups. There was, however, a statistically significant increase in the incidence of fetuses with at least three skeletal variations in all groups exposed to MFs. In conclusion, the 50 Hz or 20 kHz MFs did not increase incidences of malformations or resorptions in CBA/Ca mice, but increased skeletal variations consistently in all exposure groups. Bioelectromagnetics 19:477–485, 1998. © 1998 Wiley-Liss, Inc. 相似文献
3.
Christine I. Kowalczuk Lucy Robbins Julia M. Thomas Barbara K. Butland Richard D. Saunders 《Bioelectromagnetics》1994,15(4):349-361
Pregnant CD1 mice were exposed or sham-exposed from day 0 to day 17 of gestation to a 50 Hz sinusoidal magnetic field at 20 mT (rms). Preimplantation and postimplantation survival were assessed and fetuses examined for the presence of gross external, internal, and skeletal abnormalities. There were no statistically significant field-dependent effects on preimplantation or postimplantation survival, sex ratio, or the incidence of fetuses with internal or skeletal abnormalities. Magnetic field exposure was, however, associated with longer and heavier fetuses at term, with fewer external abnormalities. The results lend no support to suggestions of increased rates of spontaneous abortion or congenital malformation following prenatal exposure to power frequency magnetic fields. © 1994 Wiley-Liss, Inc. 相似文献
4.
Physiological processes in organisms can be influenced by extremely low-frequency (ELF) electromagnetic energy. Biological effect studies have great importance; as well as measurement studies since they provide information on the real exposure situations. In this study, the leakage magnetic fields around a transformer were measured in an apartment building in Küçükçekmece, Istanbul, and the measurement results were evaluated with respect to the international exposure standards. The transformer station was on the bottom floor of a three-floor building. It was found that people living and working in the building were exposed to ELF magnetic fields higher than the threshold magnetic field value of the International Agency for Research on Cancer (IARC). Many people living in this building reported health complaints such as immunological problems of their children. There were child-workers working in the textile factories located in the building. Safe distances or areas for these people should be recommended. Protective measures could be implemented to minimize these exposures. Further residential exposure studies are needed to demonstrate the exposure levels of ELF magnetic fields. Precautions should, therefore, be taken either to reduce leakage or minimize the exposed fields. Shielding techniques should be used to minimize the leakage magnetic fields in such cases. 相似文献
5.
Sebastio J. Ismael Fernando Callera Aglair B. Garcia Oswaldo Baffa Roberto P. Falco 《Bioelectromagnetics》1998,19(2):131-135
To address the effect of extremely low frequency electromagnetic fields on programmed cell death we assessed both the spontaneous and dexamethasone (Dex)-induced apoptosis of thymocytes and spleen cells from mice submitted to a long-term continuous exposure of a 0.4–1.0 μT 60 Hz magnetic field or an 8–20 μT direct current (DC) magnetic field. Dex-induced apoptosis but not spontaneous apoptosis was substantially increased in thymocytes from 0.4 to 1.0 μT 60 Hz field-exposed animals. Spontaneous apoptosis and Dex-induced apoptosis of spleen cells were not affected by the 0.4–1.0 μT 60 Hz field exposure. In addition, spontaneous apoptosis and Dex-induced apoptosis of thymocytes and spleen cells from mice exposed to an 8–20 μT DC field were similar to the controls. These findings represent the first demonstration that thymocytes from mice exposed to a long-term 0.4–1.0 μT 60 Hz field may show abnormal response to Dex apoptotic stimuli. Bioelectromagnetics 19:131–135, 1998. © 1998 Wiley-Liss, Inc. 相似文献
6.
Cultures of Escherichia coli kept at 0 °C in a phosphate buffer solution were exposed to a sinusoidal weak 60- or 600-Hz magnetic field of strength 2 × 10?3 Tesla. A decrease of more than 40% in bacterial count was observed after a 60-h exposure to the magnetic field. Electron micrographs of exposed bacteria show ruptured cell walls, possibly due to the breaking away of flagella under the influence of the sinusoidally varying electromotive force. 相似文献
7.
Calcium uptake by leukemic and normal T-lymphocytes exposed to low frequency magnetic fields 总被引:1,自引:0,他引:1
Calcium-ion uptake by normal and leukemia lymphocytes increased during a 30-min exposure to a 13.6 Hz, sinusoidal magnetic field at 20 microT peak. The time-varying field was horizontal and parallel to a 16.5 microT component of the ambient static magnetic field. The uptake of 45Ca2+ increased 102% in a line of murine, cytotoxic T-lymphocytes (C57B1/6-derived CTLL-1), increased 126% in freshly-isolated spleen lymphocytes (C57B1/6 mice), and increased 75% in a line of lymphoma cells (C57B1/6-derived EL4). In contrast, there was no effect when the same field was applied for 30 min immediately before--as opposed to during--incorporation of calcium ions. When spleen lymphocytes were exposed during incubation with 45Ca2+ to a 60 Hz magnetic field at 20 microT peak, a small but statistically significant increase (37%) in uptake of the labeled ions occurred. These results indicate that weak, alternating magnetic fields might affect calcium-dependent functions of normal and leukemic lymphocytes. 相似文献
8.
Jukka Juutilainen Pekka Matilainen Seppo Saarikoski Esa Lr Sakari Suonio 《Bioelectromagnetics》1993,14(3):229-236
The possibility of an association of early pregnancy loss (EPL) with residential exposure to ELF magnetic fields was investigated in a case-control study. Eighty-nine cases and 102 controls were obtained from the data of an earlier study aimed at investigating the occurrence of EPL in a group of women attempting to get pregnant. Magnetic-field exposure was characterized by measurements in residences. Strong magnetic fields were measured more often in case than in control residences. In an analysis based on fields measured at the front door, a cutoff score of 0.5 A/m (0.63 μT) resulted in an odds ratio of 5.1 (95% confidence interval 1.0–25). The results should be interpreted cautiously due to the small number of highly exposed subjects and other limitations of the data. © 1993 Wiley-Liss. Inc. 相似文献
9.
Simultaneous measurements were made of the electrocardiogram (ECG) and the intraarterial blood pressure of adult male Macaca monkeys during acute exposures to homogeneous stationary magnetic fields ranging in strength up to 1.5 tesla. An instantaneous, field strength-dependent increase in the ECG signal amplitude at the locus of the T wave was observed in fields greater than 0.1 tesla. The temporal sequence of this signal in the ECG record and its reversibility following termination of the magnetic field exposure are consistent with an earlier suggestion that it arises from a magnetically induced aortic blood flow potential superimposed on the native T-wave signal. No measurable alterations in blood pressure resulted from exposure to fields up to 1.5 tesla. This experimental finding is in agreement with theoretical calculations of the magnetohydrodynamic effect on blood flow in the major arteries of the cardiovascular system. 相似文献
10.
Daniel B. Lyle Thomas A. Fuchs Jon P. Casamento Christopher C. Davis Mays L. Swicord 《Bioelectromagnetics》1997,18(6):439-445
To explore possible biochemical mechanisms whereby electromagnetic fields of around 0.1 mT might affect immune cells or developing cancer cells, we studied intracellular calcium signaling in the model system Jurkat E6-1 human T-leukemia cells during and following exposure to a 60 Hz magnetic field. Cells were labeled with the intracellular calcium-sensitive fluorescent dye Fluo-3, stimulated with a monoclonal antibody against the cell surface structure CD3 (associated with ligand-stimulated T-cell activation), and analyzed on a FACScan flow-cytometer for increases in intensity of emissions in the range of 515–545 nm. Cells were exposed during or before calcium signal-stimulation to 0.15 mTrms 60 Hz magnetic field. The total DC magnetic field of 78.2 μT was aligned 17.5° off the vertical axis. Experiments used both cells cultured at optimal conditions at 37 °C and cells grown under suboptimal conditions of 24 °C, lowered external calcium, or lowered anti-CD3 concentration. These experiments demonstrate that intracellular signaling in Jurkat E6-1 was not affected by a 60 Hz magnetic field when culture and calcium signal-stimulation were optimal or suboptimal. These results do not exclude field-induced calcium-related effects further down the calcium signaling pathway, such as on calmodulin or other calcium-sensitive enzymes. Bioelectromagnetics 18:439–445, 1997. © 1997 Wiley-Liss, Inc. 1 This article is a US Government work and, as such, is in the public domain in the United States of America. 相似文献
11.
T S Tenforde 《Bioelectromagnetics》1986,7(3):341-346
Rectal temperatures were recorded in mice and rats during exposure to a stationary 7.55 Tesla (1 T = 10(4) Gauss) homogeneous magnetic field, and to magnetic field gradients ranging from 58.1 - 58.6 T/m. Contrary to observations reported recently by other investigators, no evidence was found for a change in the body temperature of rodents exposed to strong homogeneous or gradient magnetic fields. 相似文献
12.
We conducted a pilot study to assess magnetic field levels in electric compared to gasoline‐powered vehicles, and established a methodology that would provide valid data for further assessments. The sample consisted of 14 vehicles, all manufactured between January 2000 and April 2009; 6 were gasoline‐powered vehicles and 8 were electric vehicles of various types. Of the eight models available, three were represented by a gasoline‐powered vehicle and at least one electric vehicle, enabling intra‐model comparisons. Vehicles were driven over a 16.3 km test route. Each vehicle was equipped with six EMDEX Lite broadband meters with a 40–1,000 Hz bandwidth programmed to sample every 4 s. Standard statistical testing was based on the fact that the autocorrelation statistic damped quickly with time. For seven electric cars, the geometric mean (GM) of all measurements (N = 18,318) was 0.095 µT with a geometric standard deviation (GSD) of 2.66, compared to 0.051 µT (N = 9,301; GSD = 2.11) for four gasoline‐powered cars (P < 0.0001). Using the data from a previous exposure assessment of residential exposure in eight geographic regions in the United States as a basis for comparison (N = 218), the broadband magnetic fields in electric vehicles covered the same range as personal exposure levels recorded in that study. All fields measured in all vehicles were much less than the exposure limits published by the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE). Future studies should include larger sample sizes representative of a greater cross‐section of electric‐type vehicles. Bioelectromagnetics 34:156–161, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
13.
D L Miller 《Bioelectromagnetics》1991,12(6):349-360
Chicken eggs are convenient models for observing the effects of inhomogeneities and variations, such as those found in biological membranes and in cellular conductivities, on the distribution of internal electric fields as induced by exposure to magnetic fields. The vitelline membrane separates the yolk, which has a conductivity of 0.26 S/m, from the white, which has a conductivity of 0.85 S/m. A miniaturized probe with 2.4-mm resolution was used to measure induced fields in eggs placed in a uniform, 1-mT magnetic field at 60 Hz. The E fields induced in eggs with homogenized contents agreed with expectations based on simple theory. Results were similar to intact eggs unless the probe moved the yolk off-center, which greatly perturbed the induced fields. A more reproducible arrangement, which consisted of saline-agar filled dishes with a hole cut for test samples, was developed to enhance definition of electrical parameters. With this test system, the vitelline membrane was found to be responsible for most of the perturbation of the induced field, because it electrically isolates the yolk from the surrounding white. From a theoretical viewpoint, this dosimetry for the macroscopic egg yolk is analogous to the interaction of fields with microscopic cells. These findings may have important implications for research on biological effects of ELF electromagnetic fields, especially for studies of avian embryonic development. 相似文献
14.
Stronati L Testa A Villani P Marino C Lovisolo GA Conti D Russo F Fresegna AM Cordelli E 《Bioelectromagnetics》2004,25(1):41-48
In the past, epidemiological studies indicated a possible correlation between the exposure to ELF fields and cancer. Public concern over possible hazards associated with exposure to extremely low frequency magnetic fields (ELFMFs) stimulated an increased scientific research effort. More recent research and laboratory studies, however, have not been able to definitively confirm the correlation suggested by epidemiological studies. The aim of this study was to evaluate the effects of 50 Hz magnetic fields in human blood cells exposed in vitro, using several methodological approaches for the detection of genotoxicity. Whole blood samples obtained from five donors were exposed for 2 h to 50 Hz, 1 mT uniform magnetic field generated by a Helmholtz coil system. Comet assay, sister chromatid exchanges (SCE), chromosome aberrations (CA), and micronucleus (MN) tests were used to assess DNA damage, one hallmark of malignant cell transformation. The effects of a combined exposure with X-rays were also evaluated. Results obtained do not show any significant difference between ELFMFs exposed and unexposed samples. Moreover, no synergistic effect with ionizing radiation has been observed. A slight but significant decrease of cell proliferation was evident in ELFMFs treated samples and samples subjected to the combined exposure. 相似文献
15.
16.
H P Davis S J Mizumori H Allen M R Rosenzweig E L Bennett T S Tenforde 《Bioelectromagnetics》1984,5(2):147-164
Behavioral measures were evaluated in adult CD-1 and LAF-1 mice continuously exposed for 72 h to a 1.5-Tesla (1 T = 10(4) Gauss) homogeneous DC magnetic field, and in LAF-1 mice continuously exposed for 72 h to a sinusoidal 60-Hz, 1.65-mT (rms) homogeneous AC field. Three types of behavioral tests were employed: (1) Memory of an electroshock-motivated passive avoidance task was assessed in animals that had been trained immediately prior to the field exposure. The strength of memory was varied either by altering the strength of the electric footshock during training, or by administering a cerebral protein synthesis inhibitor, anisomycin, at the time of training. (2) General locomotor activity was measured using a quadrant-crossing test immediately after termination of the magnetic field exposure. (3) Sensitivity of the experimental subjects to the seizure-inducing neuropharmacological agent, pentylenetrazole , was assessed immediately after the field exposure on the basis of three criteria: (a) the percentage of subjects exhibiting a generalized seizure, (b) the mean time to seizure, and (c) the mean seizure level. The results of these studies revealed no behavioral alterations in exposed mice relative to controls in any of the experimental tests with the 1.5-T DC field or the 60-Hz, 1.65-mT (rms) AC field. 相似文献
17.
18.
Several studies have indicated that weak, extremely-low-frequency (ELF; 1–100 Hz) magnetic fields affect brain electrical activity and memory processes in man and laboratory animals. Our studies sought to determine whether ELF magnetic fields could couple directly with brain tissue and affect neuronal activity in vitro. We used rat hippocampal slices to study field effects on a specific brain activity known as rhythmic slow activity (RSA), or theta rhythm, which occurs in 7–15 s bursts in the hippocampus during memory functions. RSA, which, in vivo, is a cholinergic activity, is induced in hippocampal slices by perfusion of the tissue with carbachol, a stable analog of acetylcholine. We previously demonstrated that the free radical nitric oxide (NO), synthesized in carbachol-treated hippocampal slices, lengthened and destabilized the intervals between successive RSA episodes. Here, we investigate the possibility that sinusoidal ELF magnetic fields could trigger the NO-dependent perturbation of the rate of occurrence of the RSA episodes. Carbachol-treated slices were exposed for 10 min epochs to 1 or 60 Hz magnetic fields with field intensities of 5.6, 56, or 560 μT (rms), or they were sham exposed. All exposures took place in the presence of an ambient DC field of 45 μT, with an angle of -66° from the horizontal plane. Sinusoidal 1 Hz fields at 56 and 560 μT, but not at 5.6 μT, triggered the irreversible destabilization of RSA intervals. Fields at 60 Hz resulted in similar, but not statistically significant, trends. Fields had no effects on RSA when NO synthesis was pharmacologically inhibited. However, field effects could take place when extracellular NO, diffusing from its cell of origin to the extracellular space, was chelated by hemoglobin. These results suggest that ELF magnetic fields exert a strong influence on NO systems in the brain; therefore, they could modulate the functional state of a variety of neuronal ensembles. © 1996 Wiley-Liss, Inc. 相似文献
19.
Heredia-Rojas JA Caballero-Hernandez DE Rodriguez-de la Fuente AO Ramos-Alfano G Rodriguez-Flores LE 《Bioelectromagnetics》2004,25(1):63-68
The effect of in vivo exposure of mice to a 60 Hz sinusoidal magnetic field (MF) at 2.0 mT on male germ cells was studied. The cytological endpoints measured included meiotic chromosome aberrations in spermatocytes and sperm morphology. Three independent experiments were carried out: (a) animals exposed for 72 h, (b) 10 days/8 h daily, and (c) 72 h exposure to MF plus 5 mg/kg of Mitomycin-C. No statistically significant differences indicative of MF effects were observed between MF exposed and control animals. In addition, an opposite effect between MF exposure and Mitomycin-C treatment in terms of chromosomal aberrations and sperm morphology was observed. 相似文献
20.
Kaune WT 《Bioelectromagnetics》2002,23(8):622-628
Several authors have concluded that thermal electromagnetic noise will be of sufficient magnitude to overwhelm electric and/or magnetic fields induced by environmentally generated, power frequency electric and magnetic fields in the membranes of living cells located in the bodies of humans. Yet, there are research reports that indicate that living cells may respond to power frequency electric and/or magnetic field levels well below the limits set by these thermal noise arguments. The purpose of this study is to suggest that published thermal arguments may not make a full accounting of all membrane force fields of thermal origin, and that when such an accounting is made, the net thermal noise fields may be smaller in the power frequency range than previously thought. If this analysis is correct, there may be no thermal noise barrier that precludes the possibility of cellular membranes of human cells responding to environmental levels of power frequency electric or magnetic fields. 相似文献