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  • 1
    Electronic Resource
    Electronic Resource
    Intracellular recording during magnetic field application to monitor neurotransmitter release events: Methods and preliminary results (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 7 (1986), S. 271-281 
    Details
    ISSN: 0197-8462
    Keywords: magnetic fields ; extremely low frequency (ELF) magnetic fields ; neurotransmitter release ; motor end plate ; electrophysiology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A method for simultaneous magnetic field application and intracellular recording is presented. A little used method for magnetic field application was exploited; the field generator consisted of a flat copper sheet through which current was passed to generate a magnetic field. The resultant magnetic field was relatively homogeneous, exhibiting a variation of ± 5%. This compact, current-sheet field generator was mounted on the condensor of a microscope. The current induced in the intracellular electrode was reduced by injecting current equal and opposite to the induced current into the microelectrode. This step reduces the possibility of cellular effects and voltage artifacts due to the induced electrode current. The technique was used to conduct preliminary studies on the effects of extremely low frequency (ELF) linearly and circularly polarized magnetic fields (1.0 Gauss, 60 and 70 Hz) on miniature end plate potential (mepp) frequency (frequency of neurotransmitter release events) of rat flexor digitorum brevis muscle. The same synapse was utilized for both the sham-exposed control and the exposed experimental halves of an experiment. After 10 min of exposure to a 60-Hz linear field, mepp frequency was significantly increased by 12%, but exposure to a 60-Hz circular field did not significantly alter mepp frequency. Exposure to a 70-Hz linear field did not significantly change mepp frequency, but application of a 70-Hz circular field appears to decrease mepp frequency by 4%. These results indicate that both types of magnetic fields can alter mepp frequency, depending upon the frequency and configuration of the field.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250070304
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of pulsed magnetic fields on neurite outgrowth from chick embryo dorsal root gangliaConsideration of this manuscript was coordinated by a guest editor and was independent of any of the authors. (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 17 (1996), S. 293-302 
    Details
    ISSN: 0197-8462
    Keywords: nerve growth factor ; induced electric field ; directional growth ; in vitro ; waveform generator ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have previously shown that neurite outgrowth from 6-day chick embryo dorsal root ganglia (DRG) in vitro was stimulated when nerve growth factor (NGF) and pulsed magnetic fields (PMF) are used in combination. 392 DRGs were studied in a field excited by a commercial PMF generator. We have now analyzed an additional 416 DRGs exposed to very similar PMF's produced by an arbitrary wave from generator and power amplifier. We reproduced our previous findings that combination of NGF and bursts of asymmetric, 220 μs-wide, 4.0 mT-peak pulses induced significantly (p〈0.05) greater outgrowth than NGF alone, that fields without NGF do not significantly alter outgrowth, and that, unlike NGF alone, 4.0 mT fields and NGF can induce asymmetric outgrowth. The asymmetry does not seem to have a preferred orientation with respect to the induced electric field. Analysis of the data for the entire 808 DRGs confirms these findings. Importantly, we find similar results for pulse bursts repeated at 15 or 25 Hz. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Protein kinase C activity following exposure to magnetic field and phorbol ester (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 19 (1998), S. 469-476 
    Details
    ISSN: 0197-8462
    Keywords: HL60 cells ; 60 Hz magnetic fields ; transduction mechanism(s) ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We examined the separate and combined effects of 60 Hz sinusoidal magnetic fields (MFs) and a phorbol ester on protein kinase C (PKC) activity in HL60 cells. No enhancement in PKC activity was observed when a cell culture was exposed to a 1.1 mT (rms) MF alone or to a combination of MF and 2 μM phorbol 12-myristate 13-acetate (PMA) for 1 h. In a second set of experiments, cells were preexposed to a less than optimal concentration of PMA (50 nM) for 45 min, followed by a 15 min exposure to both PMA and MF. The data showed a greater decrease in cytosolic PKC activity and a larger increase in membrane activity than was induced by either 1 h PMA treatment alone or PMA and sham MF exposure. One logical conclusion from these data is that MFs may be acting in a synergistic manner on a pathway that has already been activated. Therefore, we suggest that MFs, rather than producing biological effects by a new pathway or mechanism of interaction, exert their effect(s) by interacting with already functioning reactions or pathways. If correct, the question of an MF's mechanism of interaction refocuses on how weak fields might enhance or depress a molecular reaction in progress, rather than on finding a new transduction pathway. Bioelectromagnetics 19:469-476, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of sinusoidal 60-Hz electric and magnetic fields on ATP and oxygen levels in the slime mold, Physarum polycephalum (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 7 (1986), S. 307-314 
    Details
    ISSN: 0197-8462
    Keywords: ATP ; respiration rate ; electromagnetic fields ; electric fields ; magnetic fields ; Physarum ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have previously reported that exposing the vegetative plasmodia stage of Physarum polycephalum to either individual or simultaneously applied electric and magnetic fields (45-75 Hz, 0.14-2.0 G, and 0.035-0.7 V/m) lengthens their mitotic cycle, depresses their rate of reversible shuttle streaming, and lowers their respiration rate. In this article we report the effects of simultaneously applied electromagnetic fields (60 Hz, 1.0 G, 1.0 V/m), electric fields only (60 Hz, 1.0 V/m), magnetic fields only (60 Hz, 1.0 G) on the haploid amoeba of Physarum exposed for 120-180 days. Statistically significant depressions (about 8-11%) in ATP levels were observed with all field conditions; however, respiration was significantly decreased only when amoebae were subjected to either combined fields or electric fields alone. Magnetic fields alone failed to induce a significant decrease in respiration.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250070307
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  • 5
    Electronic Resource
    Electronic Resource
    Low-voltage ELF electric field measurements in ionic media (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 6 (1985), S. 157-168 
    Details
    ISSN: 0197-8462
    Keywords: ELF electric fields ; measurement technique ; ionic media ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Low-voltage electric fields were measured in conductive tissue culture media using three techniques: voltage slope, current density-conductivity, and dipole methods. All three methods tested yielded comparable results. However, all three techniques have associated errors. These errors fall into three major categories: 1) those associated with the measurement equipment, 2) those associated with electrodes, and 3) errors in cross-sectional area measurements. Each source of error is discussed so that all can be taken into account during construction and/or testing of exposure equipment.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250060207
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic field exposure enhances mRNA expression of σ32 in E. coli (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 68 (1998), S. 1-7 
    Details
    ISSN: 0730-2312
    Keywords: cell stress ; heat shock ; σ32 ; magnetic fields ; ribonuclease protection assay ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The mechanism of interaction between weak electromagnetic fields and cells is not understood. As a result, the health effect(s) induced by exposure to these fields remains unclear. In addition to questions relating to the site of initial magnetic field (MF) interactions, the nature of the cell's response to these perturbations is also unclear. We examined the hypothesis that the cells respond to MFs in a manner similar to other environmental stressors such as heat. Using the bacterium Escherichia coli, we examined the mRNA levels of σ32, a protein that interacts with RNA polymerase to help it recognize a variety of stress promoters in the cell. Our data show that the intracellular level of σ32 mRNA is enhanced following a 15-min exposure to a 60 Hz, 1.1 mT magnetic field. J. Cell. Biochem. 68:1-7, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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