bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of 60‐Hz electric fields and incandescent light as aversive stimuli controlling the behavior of rats
Authors: Stern Sander , Laties Victor G. 
Published: February 2006

AbstractRats were exposed to two procedures which enabled them to press a lever to turn off a 90 or 100 kV/m 60‐Hz electric field or, later in the study, illumination from an incandescent lamp. Under one procedure, a response turned off the stimulus for a fixed duration, after which the stimulus was turned on again. A response during the off‐period restarted the fixed duration. None of the rats turned the field off reliably. Next, under an alternative procedure, pressing one lever turned the field off; pressing the other lever turned it back on; responding under those conditions differed little from that seen at 0 kV/m. Under both procedures, when illumination from an incandescent lamp served as the stimulus, each rat did turn the stimulus off, and performances varied with stimulus intensity. The results show that a 100 kV/m 60‐Hz electric field is not sufficient to function as an aversive stimulus under two procedures where illumination from a lamp does function as an aversive stimulus.
Multiple power‐density windows and their possible origin
Authors: Blackman C. F. , Kinney L. S. , House D. E. , Joines W. T. 
Published: February 2006

AbstractWe have previously reported that in vitro exposure of chick forebrain tissue to 50‐MHz radiofrequency (RF) electromagnetic radiation, amplitude modulated (AM) at 16 Hz, would enhance the efflux of calcium ions within only two power‐density ranges: one from 1.44 to 1.67 mW/cm2, and the other including 3.64 mW/cm2. No effect on efflux occurred at 0.37, 0.72, 2.17, and 4.32 mW/cm2. We confirmed and extended these results by testing at another set of power densities, which included the range of the previous study. Forebrain tissue from 1–7‐day‐old chickens was labeled in vitro with radioactive calcium ions (30 min, at 37 °C), rinsed, placed in a physiological salt solution, and then exposed for 20 min to 50‐MHz radiation, AM at 16 Hz, in a transverse electric and magnetic field (TEM) cell maintained at 37 °C. The solution was then assayed for radioactive calcium activity. A power‐density series was tested. An enhanced efflux of calcium ions was found at 1.75, 3.85, 5.57, 6.82, 7.65, 7.77, and 8.82 mW/cm2; no change was observed at 0.75, 2.30, 4.50, 5.85, 7.08, 8.19, 8.66, 10.6, and 14.7 mW/cm2. Power density is converted to specific absorption rate (SAR) by 0.36 mW/kg per mW/cm2. Even the highest SAR tested (0.005 W/kg) is much too low to result in generalized heating of the sample and thus to be the underlying cause of the enhanced response. A hypothetical mechanism is proposed involving dynamic systems that may account for the power‐density dependency as well as for part of the frequency dependency observed with both modulated RF radiation and extremely‐low‐frequency (ELF) fields.
Thresholds of cat cochlear nucleus neurons to microwave pulses
Authors: Seaman Ronald L. , Lebovitz Robert M. 
Published: February 2006

AbstractAction potentials of neurons in cat dorsal and posteroventral cochlear nuclei were recorded extracellularly with glass microelectrodes while the head of the cat was exposed to microwave pulses at 915 MHz using a diathermy applicator. Response thresholds to acoustic tones, acoustic clicks, and microwave pulses were determined for auditory units with characteristic frequencies (CFs) from 278 Hz to 39.2 kHz. Tests with pulsatile stimuli were performed for durations of 20–700 μs, principally 20, 70, and 200 μs. Brainstem midline specific absorption rate (SAR) threshold was as small as 11.1 mW/g per pulse, and specific absorption (SA) threshold was as small as 0.6 μJ/g per pulse. Microwave thresholds were generally lower for CF less than 9 kHz, as were most acoustic thresholds. However, microwave threshold was only weakly related to click threshold and CF‐tone threshold of each unit.
Electroreception and magnetoreception in simple and complex organisms
Authors: Tenforde T. S. 
Published: February 2006

AbstractA brief summary is presented of electroreception and magnetoreception mechanisms in bacteria and in more complex organisms such as avians, bees, and various aquatic animals. This article is a prologue to the series of three reviews written by specialists in the field of electroreception and magnetoreception that appear in this issue of Bioelectromagnetics.
Chronic exposure of primates to 60‐Hz electric and magnetic fields: I. exposure system and measurements of general health and performance
Authors: Wolpaw Jonathan R. , Seegal Richard F. , Dowman Robert 
Published: February 2006

AbstractWe exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well‐being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E‐ and B‐field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham‐exposed animals. Thus, field exposure had no apparent effects on general health or performance.
New experimental technique for detecting the effect of low‐frequency electric fields on enzyme structure
Authors: Greco Guido , Gianfreda Liliana , d'Ambrosio Guglielmo , Massa Rita , Scarfi Maria Rosaria , Scaglione Antonio 
Published: February 2006

AbstractA new experimental approach has been developed to determine kinetic and thermodynamic parameters of the inactivation of an enzyme under labile conditions both with and without exposure to electrical currents as sources of perturbation. Studies were undertaken to investigate if low‐frequency electric currents can accelerate the thermal inactivation of an enzyme through interactions with dipole moments in enzymatic molecules and through related mechanical stresses. The experiments were conducted with the enzyme acid posphatase. The enzyme was exposed to a 50‐Hz current at different densities (10 to 60 mA/cm2 rms) or to a sinusoidal or square‐wave current at an average density of 3 mA/cm2 and frequencies from, respectively, 50 Hz to 20 kHz and 500 pulses per second (pps) to 50,000 pps. Positive‐control experiments were performed in the presence of a stabilizer or a deactivator. The results indicate that the technique is sensitive to conformational changes that otherwise may be impossible to detect. However, exposure to electric currents under the experimental conditions described herein showed no effects of the currents.
A model to assess personal exposure to ELF magnetic fields from common household sources
Authors: Delpizzo Vincent 
Published: February 2006

AbstractEmission data are inadequate to characterize the contribution of a source to the total personal extremely‐low‐frequency (ELF) magnetic field exposure. In this paper, a simple model is proposed that takes into consideration the position of the subject with respect to the source and the duration of exposure. The magnetic field is spatially averaged over the whole body of the exposed subject and integrated over time. Exposure is regarded as significant if it approaches or exceeds 400 μT‐h/year. By use of this method, the ELF magnetic fields generated by several household sources were compared with the levels of residential external sources, to assess their relative significance. Some common domestic electrical appliances are found to be responsible for an exposure comparable to that from power lines. When the model is used to assess exposure to electric blankets, apparently conflicting findings may be reconciled.
Optimal experimental design for in vitro studies with ELF magnetic fields
Authors: Misakian Martin , Kaune William T. 
Published: February 2006

AbstractAn experimental arrangement is described that maximizes the dosimetric information that can be obtained during in vitro studies with ELF magnetic fields. The arrangement enables researchers to distinguish between a purely magnetic‐field effect and one that also involves the electric fields and currents induced by the magnetic field.
Microwave irradiation of rats at 2.45 GHZ activates pinocytotic‐like uptake of tracer by capillary endothelial cells of cerebral cortex
Authors: Neubauer Cecelia , Phelan Anne M. , Kues Henry , Lange David G. 
Published: February 2006

AbstractFar‐field exposures of male albino rats to 2.45‐GHz microwaves (10‐μsec pulses, 100 pps) at a low average power density (10 mW/cm2; SAR ∼2 W/kg) and short durations (30–120 min) resulted in increased uptakes of tracer through the blood‐brain barrier (BBB). The uptake of systemically administered rhodamine‐ferritin complex by capillary endothelial cells (CECs) of the cerebral cortex was dependent on power density and on duration of exposure. At 5 mW/cm2, for example, a 15‐min exposure had no effect. Near‐complete blockade of uptake resulted when rats were treated before exposure to microwaves with a single dose of colchicine, which inhibits microtubular function. A pinocytotic‐like mechanism is presumed responsible for the microwave‐induced increase in BBB permeability.
Effects of a high‐voltage direct‐current transmission line on beef cattle production
Authors: Angell R. F. , Schott M. R. , Raleigh R. J. , Bracken T. D. 
Published: February 2006

AbstractTwo herds of beef cattle were maintained beneath a ±500 kV direct‐current transmission line during a 30‐month period, and were compared with two similar herds maintained away from the transmission line. Exposures of animals under the line were five to 30 times greater than those of control animals, depending on the parameter of interest, with average exposure magnitudes of 5.6 kV/m, 4.1 nA/m2, and 13 k ions/cm3, respectively, for electric field, ion current, and density of ions. Productivity and health status of cows and calves were similar between lines and control treatments. Mean body mass of cows increased with maturity, from 438 kg in 1985 to 496 kg in 1987. Calf gain averaged 0.93 kg per head per day. No unusual sources of mortality were observed. Based on this confinement study, beef cattle permitted to graze in the vicinity of a high‐voltage, direct‐current transmission lines are not expected to experience any decrease in frequency of conception, calving, growth rate, or survival.
The effect of microwave radiation on the stability and formation of gramicidin‐A channels in lipid bilayer membranes
Authors: Sandblom John , Theander Sten 
Published: February 2006

AbstractThe effects of microwaves on the single‐channel kinetics of gramicidin‐A channels in lipid bilayer membranes were examined. Attempts were made to separate thermal and athermal effects by accurate measurements of temperature at the site of the membrane and by relating the measured parameters to their previously characterized temperature dependence. It was found that microwave radiation does not affect single‐channel conductance or channel life time to a degree that is significantly different from that expected of a purely thermal effect. On the other hand, the rate of channel formation is decreased during exposure, which is opposite to that expected of a purely thermal effect. The mechanism of this effect is discussed in terms of the dimerization process of channel formation.
Antibody responses of mice exposed to low‐power microwaves under combined, pulse‐and‐amplitude modulation
Authors: Veyret B. , Bouthet C. , Deschaux P. , de Seze R. , Geffard M. , Joussot‐Dubien J. , le Diraison M. , Moreau J.‐M. , Caristan A. 
Published: February 2006

AbstractIrradiation by pulsed microwaves (9.4 GHz, 1 μs pulses at 1,000/s), both with and without concurrent amplitude modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz, was assessed for effects on the immune system of Balb/C mice. The mice were immunized either by sheep red blood cells (SRBC) or by glutaric‐anhydride conjugated bovine serum albumin (GA‐BSA), then exposed to the microwaves at a low rms power density (30 μW/cm2; whole‐body‐averaged SAR ∼ 0.015 W/kg). Sham exposure or microwave irradiation took place during each of five contiguous days, 10 h/day. The antibody response was evaluated by the plaque‐forming cell assay (SRBC experiment) or by the titration of IgM and IgG antibodies (GA‐BSA experiment). In the absence of AM, the pulsed field did not greatly alter immune responsiveness. In contrast, exposure to the field under the combined‐modulation condition resulted in significant, AM‐frequency‐dependent augmentation or weakening of immune responses.
Possible mechanism for the influence of weak magnetic fields on biological systems
Authors: Lednev V. V. 
Published: February 2006

AbstractA physical mechanism is suggested for a resonant interaction of weak magnetic fields with biological systems. An ion inside a Ca2+ ‐binding protein is approximated by a charged oscillator. A shift in the probability of ion transition between different vibrational energy levels occurs when a combination of static and alternating magnetic fields is applied. This in turn affects the interaction of the ion with the surrounding ligands. The effect reaches its maximum when the frequency of the alternating field is equal to the cyclotron frequency of this ion or to some of its harmonics or sub‐harmonics. A resonant response of the biosystem to the magnetic field results. The proposed theory permits a quantitative explanation for the main characteristics of experimentally observed effects.
A system for simultaneous exposure of small animals to 50‐Hz electric and magnetic fields
Authors: Baum J. W. , Kuehner A. V. , Benz R. D. , Carsten A. L. 
Published: February 2006

AbstractEquipment designed for simultaneous exposure of rodents to 60‐Hz electric and magnetic fields is described. Three identical systems were constructed, each capable of continuous exposure of 256 rats or 640 mice to a nominal electric field at <50 kV/m, and to horizontal and vertical magnetic fields at < 1 mT. Design features, construction details, and results of various tests of the systems are described. Tests were made: of phase relations between electric and magnetic fields; of uniformity of electric and magnetic fields; of changes across time in electric‐field intensity as a result of animals' soiling of cages and various washing routines; of resistance of bedding material during humid and dry conditions; and of acoustic noise due to background, to field‐generation equipment, and to air conditioning equipment. The results demonstrated that fields were effectively generated but that significant and troublesome changes in electric‐field intensity occurred because of cage‐soiling. However, when cages were frequently cleaned, field intensities were consistent from one exposure to another.
Effects of exposure to 30 kV/m, 60‐Hz electric fields on the social behavior of baboons
Authors: Coelho Anthony M. , Easley Stephen Phillip , Rogers Walter R. 
Published: February 2006

AbstractWe tested the hypothesis that exposure to a 30‐kY/m, 60‐Hz electric field produces significant change (stress) in the social behavior of adult male baboons (Papio cynocephalus anubis). One group of eight baboons was exposed to an electric field (12 hours per day, 7 days per week for 6 weeks) while a second group of eight baboons was maintained in a sham‐exposure (control) condition. Exposed subjects and control subjects were compared over three, six‐week experimental periods (pre‐exposure, exposure, and post‐exposure). Performance rates of six categories of social behaviors (passive affinity, active affinity, approach, tension, threat, and attack) and four categories of nonsocial behaviors (forage, manipulate, posture, and stereotypy) were used to compare the two groups. The results of our study indicate that 1) there were no significant differences between the two groups during the pre‐exposure or post‐exposure periods; 2) during the exposure period, experimental and control groups exhibited statistically significant differences in the mean performance rates of three behavior categories; 3) within‐group comparisons across periods indicate that the experimentally exposed group exhibited statistically significant changes in passive affinity, tension, and stereotypy; and 4) changes in behavior performance among the exposed subjects reflect a stress response to the electric field.
The influence of temperature during electric‐ and magnetic‐field‐induced alteration of calcium‐ion release from in vitro brain tissue
Authors: Blackman C. F. , Benane S. G. , House D. E. 
Published: February 2006

AbstractA technique based on release of calcium ions from in vitro preparations of avian brain tissues has been used by several investigators to demonstrate a biological effect of weak electric and magnetic fields. When the tissues have been exposed to ELF‐modulated, VHF or UHF fields, enhanced release of calcium ions has resulted. In contrast, when the tissues have been exposed directly to an ELF field, outcomes have differed. Both inhibition and enhancement in release of calcium ions have been reported. We now find that either outcome—or a null result—is possible, depending on the temperature of tissue samples before and during exposure. Avian‐brain tissues were exposed to 16‐Hz sinusoidal electromagnetic fields at 14.1 Vrms/m (in air) and 64 nTrms. During 20‐min exposures, as tissue‐sample temperature rose by 0.7 to 2.5 °C to a final temperature of 35, 36, or 37, but not of 38 or 39°C, an enhanced release of ions was observed. When the temperature was stable during exposure (i.e., constant within ±0.3°C) at a final value of 36 or 37, but not of 35 or 38°C, the quantity of ions released was reduced. And when descending by 0.7 to 1.5°C to any final temperature from 35 to 38°C, a null result occurred. These findings may reconcile the apparent disagreement in the direction of a field‐induced response, and they may explain why experimental outcomes have been difficult to confirm in some laboratories. Of greater importance, the findings may also provide insight into the mechanism of the field‐induced phenomenon.
Immediate post‐exposure effects of high‐peak‐power microwave pulses on operant behavior of Wistar rats
Authors: Akyel Yahya , Hunt Edward L. , Gambrill Charles , Vargas Carlos 
Published: February 2006

AbstractBehavioral effects of high‐peak‐power microwave pulses on Wistar rats were studied by operant schedules. Each of twelve rats that had been trained to press a lever to receive food pellets was assigned randomly in groups of four to three different schedules of reinforcement: fixed‐ratio (FR), variable‐interval (VI), and differential‐reinforcement‐of‐low‐rates (DRL). After achieving a steady baseline performance, each animal was exposed for 10 min to 1.25‐GHz microwave radiation at 1‐MW peak‐power (10‐μs pulse width). Each pulse produced a peak whole‐body SA and SAR of 2.1 J/kg and 0.21 MW/kg. Total doses (SAs) were set to 0.50, 1.5, 4.5, and 14 kJ/kg by adjusting the pulse‐repetition rate. The corresponding time‐averaged whole‐body SARs were 0.84, 2.5, 7.6, and 23 W/kg. A microwave‐transparent animal holder was used to keep the animal's body axis parallel to the E‐field. Exposures at the highest dose caused an average colonic temperature rise of 2.5 °C and these animals failed to respond at all for about 13 minutes after the exposure. Their colonic temperatures had decreased to 1.1 °C, or less, above their pre‐exposure (normal) temperature level when they began to respond. The FR and VI animals failed to reach their baseline levels of performance thereafter, while those on the DRL schedule displayed variable effects. No behavioral effects were found at the lower dose levels. It is concluded that the behavioral perturbations produced by pulsed microwave irradiation were thermal in nature.
Magnetic shielding induces early developmental abnormalities in the newt, Cynops pyrrhogaster
Authors: Asashima Makoto , Shimada Kazunori , Pfeiffer Carl J. 
Published: February 2006

AbstractDeveloping larvae of the Japanese newt, Cynops pyrrhogaster, were subjected for 5 days to a shielded environment in which the static magnetic field was about 10,000 times weaker (5 nT) than the geomagnetic norm, which ranges between 30 and 60 μT at the earth's surface. Larvae from non‐cleavage to neurula stages were exposed under shielded or normal (control) conditions and then examined for evidence of developmental abnormalities either 1 day or 20 days after treatment. The magnetic shielding was associated with an increased incidence of somatic defects, especially in larvae that were examined 20 days after shielding. Bi‐headedness and intestinal protrusion were observed in magnetically shielded larvae but not in controls. Other abnormalities more frequently observed in shielded larvae were spinal curvature, malformed eyes, and retarded or blocked development. These data are among the first to illustrate the effects of magnetic‐field deprivation on a developing animal.
Cancer promotion in a mouse‐skin model by a 60‐Hz magnetic field: I. Experimental design and exposure system
Authors: Stuchly Maria A. , Lecuyer David W. , McLean Jack 
Published: February 2006

AbstractThe rationale for selection of an animal model, the experimental design, and the design and evaluation of an exposure system used in studies of 60‐Hz magnetic fields are described. The studies were conceived to assay development of cancer and immune responsiveness in mice exposed to magnetic fields. The exposure system utilized a quadrupole‐coil configuration to minimize stray magnetic fields. Four square‐wound coil provided a uniform field within a volume occupied by 16 animal cages. The magnetic field had a mean flux density of 2 mT that varied less than ±10% within the volume occupied by animals' cages. The flux density decreased to less than 0.1 μT at a distance of 2 m from the coils. In each exposure system 32 animals could be housed in plastic cages.
Electric fields induced in chicken eggs by 60‐Hz magnetic fields and the dosimetric importance of biological membranes
Authors: Miller Douglas L. 
Published: February 2006

AbstractChicken 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.