SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The transcriptional regulatory region of Elf-1 was analyzed by the combination of a yeast one-hybrid system and site-directed mutagenesis. This analysis enabled us to map an activation region between 85-175 of Elf-1.
We present the results of current epidemiological research on the association between ELF magnetic fields and neoplasm. ELF magnetic fields were considered as 'possibly carcinogenic to humans (Group 2B)' by IARC. The evidence was limited to childhood acute leukemia and to chronic leukemia (associated to occupational exposure) in adults.
Using personal dosimeters worn during two complete work-shifts, we measured occupational exposure to Extremely Low Frequency-Magnetic Fields (ELF-MF) in 290 workers employed in 56 jobs, representative of the main occupational activities in the area of Modena and Reggio Emilia (Italy). Environmental nonoccupational exposure was also monitored. In the whole sample, the mean Time-Weighted Average (TWA) exposure during work resulted 0.59 microT (SD 3.2), while the median was 0.13 microT. Exposure was lower than 1 microT in more than 90% of the workers. In one job only exposure was greater than 1 microT (job-related median TWA); in other 8 exposure was between 1 and 0.4 microT, while about 84% of the jobs presented a median TWA lower than 0.4 microT. A high variability among workers engaged in the same job resulted in various occupational tasks. Non-occupational exposure was lower than 0.4 microT in more than 98% of the examined workers. Our results show a low to moderate occupational exposure to ELF-MF in the greatest part of the workers and working activities. Also the non-occupational exposure resulted low in the large majority of the subjects. The high variability observed among workers engaged in some occupations may represent a problem in exposure evaluation. Personal monitoring is particularly useful in such a situations.
The Elf device delivered the appropriate ground ULV rate at variable road speeds ranging from 4 to 21 mph (6 to 32 kph), and shut off automatically at higher and lower speeds. The system is designed to be compatible with vehicles equipped with digital as well as standard speedometers and can be calibrated at any speed within its operating range. Although not used in these studies, Elf has a distance calibration feature designed to enhance the accuracy of the transducer and thus to yield greater flow precision than could be achieved with the transducer alone.
This randomized, controlled study was performed to evaluate how electromagnetic fields affect the accumulation of 99mTechnetium - methylendiphosphonate (Tc-MDP) in fresh fractures. Thirty women with Colles' fractures, aged 50-70 years, participated in this study--some in a control group and some in a treated group. After reduction, all patients were immobilized for four weeks. After randomization, 15 patients were treated by electromagnetic fields of extremely low frequency (EMF of ELF ), which were generated by a coil and a battery-powered portable current generator during the time of immobilization. The frequency of the alternating magnetic field was 1-1000 Hz; the magnitude was 4 gauss [RMS (root-mean-square) value]. The scintigrams were performed one, two, four, and eight weeks after the injury. The activity ratio in the fracture area was significantly higher at the examination of one and two weeks (p less than 0.05, p less than 0.01) in the treated group than it was in the control group. The clinical relevance of the results is not known, but one interpretation of the data is that the stimulation with EMF of ELF improves (accelerates) the early phase of fracture healing. The data warrant further investigation of fresh fracture treatment with this method.
Averaged electroencephalogram (EEG) frequency spectra were studied in eight unanesthetized and unmyorelaxed adult male rats with chronically implanted carbon electrodes in symmetrical somesthetic areas when a weak (0.1-0.2 mW/cm) microwave (MW, 945 MHz) field, amplitude-modulated at extremely low frequency (ELF) (4 Hz), was applied. Intermittent (1 min "On," 1 min "Off") field exposure (10-min duration) was used. Hemispheric asymmetry in frequency spectra (averaged data for 10 or 1 min) of an ongoing EEG was characterized by a power decrease in the 1.5-3 Hz range on the left hemisphere and by a power decrease in the 10-14 and 20-30 Hz ranges on the right hemisphere. No differences between control and exposure experiments were shown under these routines of data averaging. Significant elevations of EEG asymmetry in 10-14 Hz range were observed during the first 20 s after four from five onsets of the MW field, when averaged spectra were obtained for every 10 s. Under neither control nor pre- and postexposure conditions was this effect observed. These results are discussed with respect to interaction of MW fields with the EEG generators.
Entrainment of output action potentials from repetitively firing pacemaker cells, brought about by regularly spaced excitatory or inhibitory postsynaptic inputs, is a well-known phenomenon. Synchronization of neural firing patterns by extremely low frequency (ELF) external electric fields has also been observed. Whereas current densities of approximately 10 A-m(-2) are required for direct excitation of otherwise quiescent neural tissue, much lower peak current densities (approximately 10[-2] A-m2) have been reported to entrain spontaneously firing molluscan pacemaker cells. We have developed a neural spike generator circuit model that simulates repetitive spike generation by a space clamped patch (area approximately 10[-7] m2) of excitable membrane subjected to depolarizing current. Picoampere (pA) range variation of DC depolarizing current causes a corresponding smooth variation of neural spike frequency, producing a physiologically realistic stimulus-response (S-R) characteristic. When lower pA range 60 Hz AC current is superposed upon the DC depolarizing current, smooth variation of the S-R characteristic is distorted by subharmonic locking of the spike generator at 30, 20, 15, 12, 10 Hz, and higher order subharmonic frequencies. Although the additional superposition of a physiologically realistic level of "white" current noise, covering the bandwidth 4-200 Hz, suffices to obscure higher order subharmonic locking, locking at 30, 20, and 15 Hz is still clearly evident in the presence of noise. Subharmonic locking is observed at an root mean square AC simulated tissue current density of approximately 10(-5) A-m(-2).
Literature on cancer-related biological effects of extremely low frequency (ELF) magnetic fields (MF) is discussed in the light of the current understanding of carcinogenesis as a multistep process of accumulating mutations. Different animal models and study designs have been used to address possible cocarcinogenic effects of MFs. Based on a comparison of the results, we propose a hypothesis that MF exposure may potentiate the effects of known carcinogens only when both exposures are chronic. We also discuss possible mechanisms of MF effects on carcinogenesis and the adequacy of the classical two-step initiation/promotion animal experiments for simulating human exposure to the complex mixture of environmental carcinogens. We conclude that experiments designed according to the two-step concept may not be sufficient for studying the possible role of MF in carcinogenesis. Possible further animal studies are more likely to be productive if they include models that combine chronic exposure to MFs with long-term exposures to known carcinogens.
The possible effects of repeated night-time exposure to an extremely low frequency magnetic field (ELF-MF) on melatonin were investigated in nine healthy male subjects aged 23-37 yr. The 16-week experiment consisted of 3 weeks of pre-exposure, 11 weeks of night-time exposure to MF generated from a nonheated electric sheet (ES), and 2 weeks of post-exposure recovery observation. The average MF intensity (rms, mainly 50 Hz AC) on the surface of the sheet was 0.7 microT at the head, 8.3 microT at the waist, and 3.5 microT at the feet of the subject. For each of the urine samples collected 5 times a day on scheduled sampling days, the urinary excretion rate (ng/h) of melatonin was determined, and 24 h rhythms were extracted for each subject and each experimental period (pre-exposure, first half and latter half exposure, and post-exposure periods) by the method of complex cosine curve fitting. Although estimates of the peak height, acrophase, and total daily amount of melatonin were characterized by significant variations among individual subjects, they did not reveal any statistically significant difference between exposure periods and nonexposure periods. Thus, the present study indicates that any profound effect of the MF originating from an ES on nocturnal melatonin production and its circadian rhythm is unlikely.
A two-color fluorescence detection method is described based upon covalently coupling the succinimidyl ester of BODIPY TR-X dye to proteins immobilized on polyvinylidene difluoride membranes, followed by detection of target proteins using the fluorogenic, precipitating substrate ELF 39-phosphate in combination with alkaline phosphatase conjugated reporter molecules. This results in all proteins in the profile being visualized as fluorescent red signal while those detected specifically with the alkaline phosphatase conjugate appear as fluorescent green signal. The dichromatic detection system is broadly compatible with ultraviolet epi- or trans-illuminators combined with photographic or charge-coupled device cameras, and xenon-arc sources equipped with appropriate excitation/emission filters. The dichromatic method permits detection of low nanogram amounts of protein and allows for unambiguous identification of target proteins relative to the entire protein profile on a single electroblot, obviating the need to run replicate gels that would otherwise require visualization of total proteins by silver staining and subsequent alignment with chemiluminescent or colorimetric signals generated on electroblots. Combining the detection approach with an Alexa Fluor 350 dye conjugated monoclonal antibody permits simultaneous fluorescence detection of two antigens and the total protein profile on the same electroblot.
This is a cross-sectional survey on the health conditions of railways workers active in 258 interconnection and conversion substations all over Italy. Measurements performed in both kinds of substations operating at 220 kV have shown that maximum levels of the electric field strength and of the magnetic flux density at 50 Hz are of the order of 5 kV/m and 15 microT, respectively. Three subject groups, differently exposed (1, 10, 20 h/week), and an unexposed control group, for a total number of 627 workers, constitute the population at study. All subjects underwent a general medical examination, laboratory investigations, and a series of selected examinations relative to three systems (nervous, cardiovascular, and haematopoietic) considered at higher risk. No differences have been found between the exposed and the control groups. It is concluded that workers exposed to ELF electromagnetic fields of moderate strength do not show the presence of clear effects on their state of health.
The lethal effect on human cancer cells was studied under three types of treatment: A) an ELF pulsed sinusoidal of 50 Hz electromagnetic field (PEMF) with amplitudes between 10 and 55 mT; B) the field and a cytostatic agent (actinomycin-C); and C) the field, the cytostatic agent, which has a photodynamic effect, and exposure to a halogen lamp. The results show a decreasing vitality of human K-562 and U-937 cancer cells in suspension with each additional treatment. Combination with other parameters as hyperthermia and/or hyperacidity could yield high killing rates by this noninvasive method.
The influence of an extremely low frequency (ELF) magnetic field (50 Hz and 1 mT, EMF) on the activity of a soluble and insoluble horseradish peroxidase (E.C. 1.11.17) has been studied as a function of time. Insoluble derivatives were obtained by enzyme entrapment into two different gelatin membranes or by covalent attachment of the enzyme on two nylon membranes, differently preactivated. Results have shown that the field affects the inactivation rate of the soluble enzyme, while no effects are observed with insoluble derivatives. Since in vivo enzymes are immobilised into the biomembrane bilayer or entrapped into the cytoplasmic mixture, one might speculate that our experimental conditions do not reflect the catalytic activity of the enzymes in vivo.
The effects of exposure to a 50 Hz magnetic field (maximum of 41.7 to 43.6 mT) on the membrane protein structures of living HeLa cells were studied using attenuated total reflection infrared spectroscopy. One min of such exposure shifted peak absorbance of the amide I band to a smaller wave number, reduced peak absorbance of the amide II band, and increased absorbance at around 1600 cm(-1). These results suggest that exposure to the ELF magnetic field has reversible effects on the N-H inplane bending and C-N stretching vibrations of peptide linkages, and changes the secondary structures of alpha-helix and beta-sheet in cell membrane proteins.
We present the results of a study of the extremely low frequency (ELF) magnetic fields in urban environments of the Extremadura region (Spain). The study included a spectral analysis, an analysis of the temporal variation, and spot measurements in the streets of four cities. The spectral analysis showed that the main source of magnetic field exposure was that corresponding to the principal power frequency (50 Hz) and its third harmonic. The magnetic flux density measured at one point over 24 h presented rapid fluctuations in short time periods. Smoothing the time series eliminated these fluctuations, showing a temporal evolution associated with the differing levels of power consumption over the course of the day. The values of the spot measurements taken in the streets were all below the ICNIRP reference level, although 30% surpassed 0.2 microT, the value that some epidemiological studies take as the threshold above which there exist risks of effects that could be harmful to health. The values found for the magnetic flux density in these urban settings were generally greater than values reported in the literature for residential areas, and similar to, although in some cases less than those in workplace environments.
For in vitro studies on the effect of extremely low frequency (ELF) magnetic field exposures in different laboratories, a programmable, high precision exposure system enabling blinded exposures has been developed and fully characterized. It is based on two shielded 4 coil systems that fit inside a commercial incubator. The volume of uniform B field exposure with 1% field tolerance is 50% larger compared to a Merrit 4 coil system with the same coil volume. The uncertainties for the applied magnetic fields have been specified to be less than 4%. The computer controlled apparatus allows signal waveforms that are composed of several harmonics, blind protocols, monitoring of exposure and environmental conditions and the application of B fields up to 3.6 mT root-mean-square amplitude. Sources of artifacts have been characterized: sham isolation >43 dB, parasitic incident E fields <1 V/m, no recognizable temperature differences in the media for exposure or sham state, and vibrations of the mechanically decoupled dish holder <0.1 m/s(2) (= 0.01 g), which is only twice the sham acceleration background level produced by the incubator and fan vibrations.
In this study, the extremely low frequency (ELF) fields induced in the human head by the battery currents of a mobile phone are considered. The magnetic field induced by the phone was measured, and this data was used to calculate the resulting currents induced in the human head and brain. Both the finite element method (FEM) and finite integration technique (FIT) were used for numerical computations. The computed current density values were then compared with the guidelines given by the International Commission on Non-Ionising Radiation Protection (ICNIRP). The comparison showed that the computed exposure is well within the limits of those guidelines.
Short-circuit currents, surface electric fields, and axial current densities were measured in electrically grounded guinea pigs exposed to a uniform, vertical, ELF electric field. These data are 70-110% of corresponding values obtained in grounded rats exposed to the same electric field.