bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological effects of high‐frequency electromagnetic fields on Salmonella typhimurium and Drosophila melanogaster
Authors: Hamnerius Yngve , Rasmuson Åsa , Rasmuson Bertil
Published: February 2006

Salmonella typhimurium and Drosophila melanogaster were exposed to continuous wave (CW) 2.45‐GHz electromagnetic radiation, pulsed 3.10‐GHz electromagnetic radiation, CW 27.12‐MHz magnetic fields, or CW 27.12‐MHz electric fields (only Drosophila). The temperatures of the treated sample and the nonexposed control sample were kept constant. The temperature difference between exposed and control samples was less than ± 0.3°C. Ames' assays were made on bacteria that had been exposed to microwaves (SAR 60–130 W/kg) or RF fields (SAR up to 20 W/kg) when growing exponentially in nutrient broth. Survival and number of induced revertants to histidine prototrophy were determined by common plating techniques on rich and minimal agar plates. The Drosophila test consisted of a sensitive somatic system where the mutagenicity was measured by means of mutations in a gene‐controlling eye pigmentation. In none of these test systems did microwave or radiofrequency fields induce an elevated mutation frequency. However, a significantly higher concentration of cells was found in the bacterial cultures exposed to the 27‐MHz magnetic field or 2.45‐GHz CW and 3.10‐GHz pulsed microwave radiation.
Regional turnover of norepinephrine and dopamine in rat brain following acute exposure to air ions
Authors: Charry Jonathan M. , Bailey William H.
Published: February 2006

Exposure to air ions has been reported to influence serotonin (5HT), although critical reviews of these studies and previous measurements in our laboratory of the concentration, release, and utilization of brain 5HT indicate that neither the data nor the interpretations of the data are particularly convincing. Measurements of other possibly relevant neuro‐transmitter systems—norepinephrine (NE) and dopamine (DA)—were made in brain regions selected because of their importance in the modulation of brain functions relating to motivation, arousal, endocrine function, and motor activity, all responses that have been reported to be influenced by air ion exposure. Results indicate that exposure of male Holtzman rats to high concentrations (5.0 × 105/cm3) of positive or negative air ions or to DC electric fields (3.0 kV/m) for periods up to 66 h failed to affect the concentration of NE or DA significantly in any of the brain regions.
Sine waves enhance cellular transcription
Authors: Goodman Reba , Henderson Ann S.
Published: February 2006

We previously showed that quasirectangular, asymmetrical, pulsed electromagnetic (EM) fields of low frequency can induce increased transcription in Sciara salivary gland cells. A symmetrical sine wave with the same frequency as known biologically effective asymmetric signals was studied in the present investigations. The results demonstrated that signal shape was not a major factor in causing augmented transcription. The pattern of grain density in transcription autoradiograms, as well as the size classes of RNA responsive to EM fields, was the same irrespective of asymmetry or symmetry of the signal. Following short‐term exposure of the cells to either type of EM field, S values of new transcripts were consistent with those expected for processed and unprocessed messenger RNA.
Postmortem changes of the dielectric properties of bovine brain tissues at low radiofrequencies
Authors: Surowiec A. , Stuchly S. S. , Swarup Arvind
Published: February 2006

The dielectric properties of the bovine brain grey and white matter in the frequency range from 20 kHz to 100 MHz were measured at different times following animal death. Changes in the dielectric parameters versus time are interpreted in terms of the reduction of the cell volume fraction that results from either cell disintegration or cell size reduction. Good agreement between the computer fitted parameters and the values calculated from the Maxwell‐Wagner model of the static dielectric constants was found. At frequencies above 1 MHz the changes of the dielectric properties are less pronounced, confirming earlier observations made by other investigators for different species.
Magnetic field measurements near RF induction heaters
Authors: Conover David L. , Murray William E. , Lary Joseph M. , Johnson Peggy H.
Published: February 2006

We discuss initial magnetic field strength measurements made around radiofrequency (RF) induction heaters. These measurements were made with a monitor developed for the National Institute for Occupational Safety and Health (NIOSH) by the National Bureau of Standards (NBS). The monitor has a dynamic range of .01 to 10,000 A2/m2, a frequency range of 300 kHz to 100 MHz, an isotropic response (± .3 dB) with three mutally orthogonal loop antennas that have the ability to measure and display each of three orthogonal magnetic field components, a high probe burnout protection level of 20,000 A2/m2, and an accuracy of ± 1.0 dB at 13 calibration frequencies. The portable survey monitor was used to measure the magnetic field strengths in the vicinity of 16 RF induction heaters. Typically these induction heaters are operated continuously for several hours. The maximum field strengths (without duty factor correction) ranged from 15 to 4,500 A2/m2 and were measured 5 to 51 cm from the loop applicators of the induction heaters. At locations commonly occupied by workers (ie, approximately 30 to 76 cm from heaters), the fields ranged from .01 to 300 A2/m2 (without duty factor correction).
Circulating antibody response of mice exposed to 9‐GHz pulsed microwave radiation
Authors: Liddle C. G. , Putnam J. P. , Lewter O. H. , West M. , Morrow G.
Published: February 2006

Female CD‐1 mice immunized against the bacterium Streptococcus pneumoniae type III were exposed to 9‐GHz pulsed microwaves (pulse repetition rate 970‐1,000, pulse width 1.0 μs, peak power 1 W/cm2) at an average incident power density of 1 mW/cm2 (calculated SAR = 0.47 W/kg) for 2 h per day for 5 days. Circulating antibody titers for the microwave‐exposed animals were not significantly different from those of the shamirradiated animals, and there were no differences in any of the hematological parameters analyzed, indicating that 9‐GHz pulsed microwaves at 1 mW/cm2 do not alter the immune response of mice immunized against S pneumoniae.
Dosimetric study of microwave cataractogenesis
Authors: Foster Mark R. , Ferri Esther S. , Hagan Gary J.
Published: February 2006

A closed waveguide method has been used to induce opacities in the rabbit eye. A 30‐min exposure to 2.45‐GHz radiation such that 8.7 W is incident on the head (5.75 W being absorbed) produces a cataract in half of the exposed eyes of New Zealand white rabbits.
Dielectric behavior of water in biological solutions: Studies on myoglobin, human low‐density lipoprotein, and polyvinylpyrrolidone
Authors: Grant E. H. , McClean V. E. R. , Nightingale N. R. V. , Sheppard R. J. , Chapman M. J.
Published: February 2006

The dielectric behavior of the aqueous solutions of three widely differing macromolecules has been investigated: myoglobin, polyvinylpyrrolidone (PVP), and human serum low‐density lipoprotein (LDL). It was not possible to interpret unambiguously the dielectric properties of the PVP solution in terms of water structure. The best interpretation of the dielectric data on the myoglobin and LDL solutions was that, in both cases, the macromolecule attracts a layer of water of hydration one or two water molecules in width. For LDL, this corresponds to a hydration factor of only 0.05 g/g, whereas for myoglobin the figure is nearer 0.6 g/g. With myoglobin, part of the water of hydration exhibits its dispersion at frequencies of a few GHz, and the rest disperses at lower frequencies, perhaps as low as 10–12 MHz. The approximate constancy of the width of the hydration shell for two molecules as dissimilar in size as LDL and myoglobin confirms that the proportion of water existing as water of hydration in a biological solution depends critically on the size of the macromolecules as well as on their concentration.
Dynamic characteristics of membrane ions in multifield configurations of low‐frequency electromagnetic radiation
Authors: McLeod B. R. , Liboff Abraham R.
Published: February 2006

We seek to extend the recent suggestion that classical cyclotron resonance of biologically important ions is implicated in weak electromagnetic field‐cell interactions. The motion of charged particles in a constant magnetic field and periodic electric field is examined under the simplifying assumption of no damping. Each of the nine terms of the relative dielectric tensor is found to have a dependence on functions that include the factor (ω2 – ω)−1, where ωB is the gyrofrequency. We also find a plasmalike decomposition of the electric field into oppositely rotating components that could conceivably act to drive oppositely charged ions in the same direction through helical membrane channels. For weak low‐frequency magnetic fields, an additional feature arises, namely, periodic reinforcement of the resonance condition with intervals of the order of tens of msec for biological ions such as Li+, Na+, and K+.
Cardiovascular, hematologic, and biochemical effects of acute ventral exposure of conscious rats to 2450‐MHz (CW) microwave radiation
Authors: Galvin M. J. , McRee D. I.
Published: February 2006

In this study the influence of acute (6 hr) exposure to 2450 MHz (CW) microwave radiation on certain cardiovascular, biochemical, and hematologic indices was examined in unanesthetized rats. Under methoxyflurane anesthesia, a catheter was inserted into the right femoral artery, which was used for monitoring blood pressure, heart rate, and blood sampling. Colonic temperature was monitored via a VITEK thermistor probe inserted rectally to a depth of 5 cm. The rat was subsequently placed into a ventilated restraining cage which was located inside an anechoic chamber. The temperature and humidity in the chamber were maintained at 22 ± 0.5°C and 60 ± 5% (means ± S.E.), respectively, during the experimental period. Rats (60) were exposed to either 0 (sham) or 10 mW/cm2 (exposed) for 6 hr. During exposure rats were oriented perpendicular to the E‐field, and the measured specific absorption rate (SAR) was 3.7 mW/g. In the sham and exposed rats, the preexposure (time 0) mean ± S.E. arterial blood pressure (MABP), heart rate, and colonic temperature were approximately 120 ± 5 mmHg, 450 ± 10 beats/min, and 37.0 ± 0.2 °C, respectively. In the sham‐exposed rats these values remained stable throughout the 6‐hr exposure period. In the exposed rats, no effects were noted on MABP or colonic temperature; however after 1 hr of exposure, a significant reduction in heart rate was noted (450 versus 400 beats/min). This decrease in heart rate persisted throughout the remainder of the exposure period. None of the hematologic or biochemical parameters examined were affected by the microwave exposure. Although other mechanisms may be responsible, this decrease in heart rate may have been due to subtle cardiovascular adjustments because of microwave‐induced heating with a resultant reduction in resting metabolic rate.
60‐Hz electric‐field effects on pineal melatonin rhythms: Time course for onset and recovery
Authors: Wilson B. W. , Chess E. K. , Anderson L. E.
Published: February 2006

Rats exposed for 3 weeks to uniform 60‐Hz electric fields of 39 kV/m (effective field strength) failed to show normal pineal gland circadian rhythms in serotonin N‐acetyl transferase activity and melatonin concentrations. The time required for recovery of the melatonin rhythm after cessation of field exposure was determined to be less than 3 days. The rapid recovery suggests that the overall metabolic competence of the pineal is not permanently compromised by electric‐field exposure, and that the circadian rhythm effect may be neuronally mediated.
Use of the loss‐tangent function in dielectric spectroscopy
Authors: Surowiec Andrzej , Stuchly Stanislaw S.
Published: February 2006

A new method for finding the dielectric parameters of biological substances is presented. The method makes use of the loss‐tangent as a function of frequency to identify the dominating relaxation process. The method was tested for a few cell suspensions (blood and lymphocytes) and two tissues (liver and spleen). The obtained parameters agree well with those calculated from Maxwell‐Wagner theory (β dispersion).
Measurement of small mechanical vibrations of brain tissue exposed to extremely‐low‐frequency electric fields
Authors: Spiegel R. J. , Ali J. S. , Peoples J. F. , Joines W. T.
Published: February 2006

Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely‐low‐frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposure cell is a section of X‐band waveguide that was modified by the addition of a center conductor to form a small TEM cell within the waveguide structure. The ELF signal is applied to the center conductor of the TEM cell. The applied ELF electric field generates an electrostrictive force on the surface of the brain tissue. This force causes the tissue to vibrate at a frequency equal to twice the frequency of the applied sinusoidal signal. An X‐band signal is fed through the waveguide, scattered by the vibrating sample, and detected by a phase‐sensitive receiver. Using a time‐averaging spectrum analyzer, a vibration sensitivity of approximately 0.2 nmp‐p can be achieved. The amplitude of the brain tissue vibrational response is constant for vibrational frequencies below 50 Hz; between 50 and 200 Hz resonant phenomena were observed; and above 200 Hz the amplitude fall‐off is rapid.
Intermittent exposure of rats to 2450 MHz microwaves at 2.5 mW cm2: Behavioral and physiological effects
Authors: D'Andrea John A. , Dewitt John R. , Emmerson Rita Y. , Bailey Cory , Stensaas Suzanne , Gandhi Om P.
Published: February 2006

Long‐Evans male adult rats were intermittently exposed for 14 weeks to continuous wave (CW) 2450‐MHz microwaves at an average power density of 2.5 mW/cm2. The mean specific absorption rate was 0.70 W/kg (± 0.02 SEM). The rats were exposed 7 h/day, 7 days/week in a radiation chamber with a monopole above ground, while housed in Plexiglas cages. Weekly measures of body mass and food intake did not indicate statistically significant effects of microwave irradiation. Assessments of threshold for electric‐footshock detection revealed a significant difference between microwave and sham‐exposed animals. Assessments of cholinesterase and sulfhydryl groups in blood and 17‐ketosteriods in urine did not distinguish the two groups of rats. Behavioral measures made at the end of the 14‐week exposure included an open‐field test, shuttlebox avoidance performance, and schedule‐controlled lever‐pressing for food pellets. Statistically significant differences between microwave‐ and sham‐exposed rats were observed for these measures. Examination of adrenal tissue, plasma electrolytes, and organ masses after 14 weeks of exposure revealed no difference between the two groups of rats.
Behavioral monitoring of rats during exposure to air ions and DC electric fields
Authors: Bailey William H. , Charry Jonathan M.
Published: February 2006

Air ions and direct current (DC) electric fields have been reported to exert subtle behavioral and biological effects on rodents and humans. These effects often appear inconsistent, yet there have been few attempts to resolve these inconsistencies by experimental replication. Rats exposed to negatively or positively charged air ions over a wide range of concentrations and exposure periods have been reported to show alterations in their level of locomotor activity. In this study, locomotor activity of Sprague‐Dawley rats was quantified during exposure to either (1) unipolar air ions and DC fields of the same polarity or (2) DC fields alone. Both polarities were studied. Air ion concentrations were 5.0 × 103, DC fields were 3 kV/m, and exposures lasted 2, 18, or 66 h. In one experiment rats were exposed to DC fields of 12 kV/m. No exposure condition exerted any effect on locomotor activity or rearing behavior. In addition, no behavioral perturbations were observed after the onset of any of the exposure conditions, suggesting that the rats may have failed to detect the altered environment.
Thermoregulation in rodents exposed to high‐intensity stationary magnetic fields
Authors: Tenforde T. S.
Published: February 2006

Rectal temperatures were recorded in mice and rats during exposure to a stationary 7.55 Tesla (1 T = 104 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.
Microwave effects on isolated chick embryo hearts
Authors: Caddemi A. , Tamburello C. C. , Zanforlin L. , Torregrossa M. V.
Published: February 2006

This study was designed to examine the effects of microwaves on the electric activity of hearts as a means of elucidating interactive mechanisms of nonionizing radiations with cardiac tissue. Experiments were performed on isolated hearts of 9–12‐day‐old chick embryos placed in small petri dishes. Oxygenated isotonic Ringer's solution at 37°C permitted heart survival. Samples were irradiatd at 2.45 GHz with a power density of 3 mW/cm2. The heart signal was detected with a glass micropipet inserted into the sinoatrial node and examined by means of a Berg‐Fourier analyzer. Pulsed microwaves caused the locking of the heartbeat to the modulation frequency, whereas continuous wave irradiation might have induced slight bradycardia. Pulsed fields induced stimulation or regularization of the heartbeat in arrhythmia, fibrillation, or arrest of the heart.
Lack of an effect of static magnetic field on calcium efflux from isolated chick brains
Authors: Bellossi A.
Published: February 2006

45Ca2+ efflux from neonatal isolated chick brains was measured. The brains were exposed to uniform or nonuniform static magnetic fields. The field intensity ranged from 200–900 mT. The exposure took place during incubation and/or when efflux was being measured. No difference appeared in the 45Ca2+ efflux between controls and exposed brains.
Effect of extremely‐low‐frequency pulsed magnetic fields on the mitogenic response of peripheral blood mononuclear cells
Authors: Mooney Nuala A. , Smith Roy E. , Watson Bernard W.
Published: February 2006

The effect of extremely‐low‐frequency pulsed magnetic fields (PMF) on the response of human peripheral blood mononuclear cells to mitogenic stimulation is reported. We investigated 25 healthy control subjects. Mitogen‐stimulated mononuclear cells were exposed to PMF for 72 h and an inhibition of 3H‐thymidine uptake was observed in all but one subject. The degree of inhibition of 3H‐thymidine uptake was as much as 60%. There was no significant difference between the blastogenic responses of mononuclear cells exposed to PMF for 12 h and control cultures. This study establishes an inhibitory effect of PMF on an in vitro measure of immune function.
Response of sensory receptors of the cat's hindlimb to a transient, step‐function DC electric field
Authors: Kato M. , Ohta S. , Kobayashi T. , Matsumoto G.
Published: February 2006

There are two possible mechanisms of effects of large electric fields on animals, one caused by the electric field at the body surface and the other caused by the electric current induced inside the body. The purpose of the present experiments was to investigate the former possibility by recording action potentials from afferent fibers innervating various sensory receptors in the cat's hindlimb. Cat hairs were attracted to the upper electrode when exposed to DC electric fields of 180 kV/m or greater, and action potentials were evoked in the afferent fibers innervating G1, G2, and down hair receptors. No action potentials were evoked in afferent fibers innervating type I, type II, field receptors, muscle spindles, or joint receptors. These results indicate that a strong DC electric field induced movement of the hairs, eventually evoked excitation of the hair receptors, but that other receptors located under the skin were not influenced by electric field exposure.
Effect of low‐level, 60‐Hz electromagnetic fields on human lymphoid cells: I. Mitotic rate and chromosome breakage in human peripheral lymphocytes
Authors: Cohen Maimon M. , Kunska Ann , Astemborski Jacqueline A. , McCulloch Duncan , Paskewitz David A.
Published: February 2006

Dividing human peripheral lymphocytes from 10 normal adults (5 males and 5 females) were exposed in vitro to low level 60‐Hz electromagnetic fields for 69 hours. The current density of the electrical field was 30 μA/cm2, while the magnetic field was either 1 or 2 gauss. The cytological endpoints measured were mitotic rate and chromosome breakage. No statistically significant differences, indicative of a field effect, were observed between treated and control cells whether exposed to an electric field, a magnetic field, or to various combinations of the two.
Effects of extremely‐low‐frequency electric fields on neuronal activity in rat brain
Authors: Blackwell R. P.
Published: February 2006

The effects of 50‐, 30‐, and 15‐Hz electric field exposure on the activity of spontaneously firing neurons in the brain of anaesthetized rats were studied. Exposure to fields of 100 V/m (peak‐to‐peak, in air) produced no effect on the overall rate of neuronal firing, but some synchronicity with the period of the exposure waveform was seen with 15‐ and 30‐Hz electric fields.
Acute, whole‐body microwave exposure and testicular function of rats
Authors: Lebovitz R. M. , Johnson L.
Published: February 2006

Male Sprague‐Dawley rats were exposed for 8 h to continuous‐wave microwave radiation (MWR, 1.3 Ghz) at a mean specific absorbed dose rate of 9 mW/g. MWR exposure and sham‐irradiation took place in unidirectionally energized cylindrical waveguide sections, within which the animals were essentially unrestrained. The MWR treatment in this setting was determined to yield an elevation of deep rectal temperature to 4.5 °C. The animals were taken for analysis at 6.5, 13, 26, and 52 days following treatment, which corresponded to 0.5, 1, 2, and 4 cycles of the seminiferous epithelium. Net mass of testes, epididymides, and seminal vesicles; daily sperm production (DSP) per testis and per gram of testis; and the number of epididymal sperm were determined. The levels of circulating follicle‐stimulating hormone (FSH) and leutinizing hormone (LH) were derived via radioimmunoassay of plasma samples taken at the time of sacrifice. Despite the evident acute thermogenesis of the MWR at 9 mW/g, no substantial decrement in testicular function was found. We conclude that, in the unrestrained rat, whole body irradiation at 9 mW/g, while sufficient to induce evident hyperthermia, is not a sufficient condition for disruption of any of these key measures of testicular function.
Microwave facilitation of domperidone antagonism of apomorphine‐induced stereotypic climbing in mice
Authors: Quock R. M. , Kouchich F. J. , Ishii T. K. , Lange D. G.
Published: February 2006

The dopaminergic agonist apomorphine produced dose‐dependent stereotypic climbing behavior in mice housed in cages with vertical bars. This drug effect was competitively inhibited by systemic pretreatment with the centrally acting dopaminergic antagonist haloperidol but not by microwave irradiation (2.45 GHz, 20 mW/cm2, CW, 10 min) nor by systemic pretreatment with domperidone, a dopaminergic antagonist that only poorly penetrates the blood‐brain barrier (BBB). Yet when mice were systemically pretreated with domperidone and then subjected to microwave irradiation (as above), the apomorphine effect was significantly reduced. Microwave irradiation also facilitated antagonism of the apomorphine effect by low and otherwise ineffective systemic pretreatment doses of haloperidol. Apomorphine‐induced stereotypic climbing behavior was also reduced by domperidone administered intracerebrally, which bypassed the BBB. Exposure of intracerebral domperidone‐pretreated animals to microwave irradiation failed to increase the degree of antagonism. These findings indicate that microwave irradiation can facilitate central effects of domperidone, a drug which acts mainly in the periphery. One possible explanation for these findings is that microwave irradiation alters the permeability of the BBB and increases the entry of domperidone to central sites of action.
60‐Hz electric and magnetic fields generated by a distribution network
Authors: Héroux Paul
Published: February 2006

From a mobile unit, 60‐Hz electric and magnetic fields generated by Hydro‐Québec's distribution network were measured. Nine runs, representative of various human environments, were investigated. Typical values were 32 V/m and 0.16 μT. The electrical distribution networks investigated were major contributors to the electric and magnetic environments.
Pulsed subcutaneous electrical stimulation in spinal cord injury: Preliminary results
Authors: Ellis Wladislaw
Published: February 2006

The treatment of long‐term, stable para‐ and quadriplegics with pulsed electrical stimulation for pain control resulted in, anecdotally, a significant number of these individuals showing increased motor function as well as sensory awareness. This small pilot study was conducted in order to assess the hypothesis that pulsed electrical fields can effect diseased neurological function. Thirteen para‐ and quadriplegic subjects with 18 months of stable neurological signs and symptoms were exposed daily to pulsed electrical stimulation for a 6‐month period and assessed for any improvement in motor function or sensory perception. The hypothesis is that pulsed electromagnetic fields can normalize viable but dysfunctional neuronal structures. Results were encouraging.
Control of energy absorption rate in transmission line radiofrequency exposure systems
Authors: Ali Joseph S. , Elliott Dorothy J.
Published: February 2006

A frequent problem in the radiofrequency (RF) irradiation of experimental animals in health effects studies is the temporal variation of the specific absorption rate (SAR) with animal movement. An RF power controller that regulates the energy absorption rate has been designed for use with transmission line exposure systems that utilize the power difference method to monitor the SAR. The controller operates by altering the incident power to the exposure cell in order to compensate for the change in RF energy absorption rate that is due to animal motion. A circuit diagram is presented as well as experimental data under three conditions of exposure. The controller is effective in maintaining the mean value of energy absorption rate at the setpoint value even for the case of a highly active animal.
Acute exposure of rats to air ions: Effects on the regional concentration and utilization of serotonin in brain
Authors: Bailey William H. , Charry Jonathan M.
Published: February 2006

Exposure to electrically charged gas molecules (air ions) has been reported to influence physiological and behavioral functions in animals and humans although there is controversy as to whether these findings are valid. A popular hypothesis concerning the reported effects of air ions is that alterations in serotonin (5HT) metabolism, particularly in the brain, are involved. We measured the concentration and turnover of 5HT in rats exposed to 5.0 × 105 ions/cm3 for up to 66 hours. Contrary to previous reports of other investigators, we were unable to demonstrate any effect of exposure to air ions or associated DC electric fields on the concentration or turnover of 5HT in rats under carefully controlled and characterized exposure conditions.
Rewarming of the hypothermic rhesus monkey with electromagnetic radiation
Authors: Olsen R. G. , Ballinger M. B. , David T. D. , Lotz W. G.
Published: February 2006

To obtain more detailed information relative to the potential usefulness of using radio frequency (RF) energy in treating hypothermia, anesthetized rhesus monkeys were used in a rewarming study that compared a conventional method (heating pad) with an RF induction coil system. Rectal temperature (Tre) of each subject was monitored, and enzyme and isoenzyme levels were determined from blood samples collected before, during, and up to 48 h after hypothermia in order to assess the effects of each rewarming method. The previously observed postprocedure rise in serum enzymes (most visible at 24 h) was again seen, with no statistically significant difference in the time course of serum enzyme levels between the two treatments for comparable durations of hypothermia. To test the limits of the ability of the RF induction coil system, successively more severe hypothermia was induced in the subjects to the point of cardiovascular collapse (Tre < 20°C); RF energy was successful in resuscitating the profoundly hypothermic subjects without discernible harmful effects.
Low‐level, magnetic‐field‐induced growth modification of Bacillus subtilis
Authors: Ramon Ceon , Martin J. T. , Powell M. R.
Published: February 2006

Experimental studies showed an increase in the growth of Bacillus subtilis mutant strain FJ7 above controls by exposing the bacterial culture to 800‐Hz or 1‐KHz magnetic fields with a 2‐s‐on /2‐s‐off period. The magnetic field strength was between 0.8 and 2. 5 mT. Light microscopy and scanning electron microscopy demonstrated the morphology of controls to grow in a macrofiber of right‐handed helix formation. In contrast, the field‐exposed group showed little to no cohesion; the cells appeared to be homogeneously distributed throughout the sample. These results suggest that growth patterns of Bacillus subtilis can be altered as a result of magnetic‐field‐induced effects.
Effects of microwave exposure and temperature on survival of mice infected with Streptococcus pneumoniae
Authors: Liddle C. G. , Putnam J. P. , Lewter O. H.
Published: February 2006

Female CD‐1 mice were injected with an LD50 dose of Streptococcus pneumoniae and then exposed to 2.45 GHz (CW) microwave radiation at an incident power density of 10 mW/cm2 (SAR = 6.8 W/kg), 4 h/d for 5 d at ambient temperatures of 19 °C, 22 °C, 25 °C, 28 °C, 31 °C, 34 °C, 37 °C and 40 °C. Four groups of 25 animals were exposed at each temperature with an equal number of animals concurrently sham‐exposed. Survival was observed for a 10‐d period after infection. Survival of the sham‐exposed animals increased as ambient temperature increased from 19 °C–34 °C. At ambient temperatures at or above 37 °C the heat induced in the body exceeded the thermoregulatory capacity of the animals and deaths from hyperthermia occurred. Survival of the microwave‐exposed animals was significantly greater than the shams (∼20%) at each ambient temperature below 34 °C. Based on an analysis of the data it appears that the hyperthermia induced by microwave exposure may be more effective in increasing survival in infected mice than hyperthermia produced by conventional methods (ie, high ambient temperature). Microwave radiation may be beneficial to infected animals at low and moderate ambient temperatures, but it is detrimental when combined with high ambient temperatures.
Stimulation of cutaneous mechanoreceptors by 60‐Hz electric fields
Authors: Weigel R. J. , Jaffe R. A. , Lundstrom D. L. , Forsythe W. C. , Anderson L. E.
Published: February 2006

Chronic exposure of animals to 60‐Hz electric fields is known to affect the nervous system in a variety of subtle ways. The mechanism whereby these effects are produced remains unknown. One hypothesis is that the effects are a result of direct interaction between neuronal membranes and induced currents. Alternatively, the effects could be produced indirectly, as a result of sensory stimulation and the resulting low‐level stress. To test these hypotheses, a system was developed to expose the surface of an anesthetized cat's paw to surface electric fields up to 600 kV/m while simultaneously measuring, in dorsal root fibers, afferent nerve impulses originating from various receptor types in the exposed paw. Of the 245 receptor units tested, comprising ten cutaneous receptor types, ten responded to the electric field with an increase in firing rate. The most sensitive receptor type was the rapidly adapting field receptor (RAF); eight of 20 (40%) were sensitive to the electric field, with thresholds as low as 160 kV/m. One of 35 rapidly adapting high‐frequency receptors and one of 22 type T hair‐follicle receptors were also sensitive to the electric field. Follow‐up tests on the RAF receptors showed that hair removal reduced but did not eliminate the electric field sensitivity, suggesting that at least one other mechanism was involved in addition to stimulation via hair movement. The most likely mechanism is field‐induced vibrations of the skin, since a further reduction in firing rate occurred following application of mineral oil to the depilated paw. Direct interaction with neuronal membranes is not supported by our evidence.
Finite difference calculations of current densities in a homogeneous model of a man exposed to extremely low frequency electric fields
Authors: Dimbylow P. J.
Published: February 2006

This paper presents three‐dimensional finite difference calculations of induced current densities in a grounded, homogeneous, realistically human‐shaped phantom. Comparison is made with published experimental values of current density at 60 Hz, measured in conducting saline manikins with their arms down by the side. The congruence between calculation and experiment gives confidence in the applicability of the numerical method and phantom shape to other configurations. The effect of raising both arms above the head is to reduce the current densities in the head and neck by ∼50% and to increase those from the thorax downwards by 20–30%. A sensitivity analysis was performed on the shape and dimensions of the phantom, from a 45‐kg, 1.5‐m‐tall person to a 140‐kg, 1.9‐m‐tall person. When the phantom is grounded through both feet the current densities range from 50 to 90 μAm−2 in the head (all values for a 60‐Hz, 1‐kVm−1, vertical applied field), 70 to 140 μAm−2 in the thorax, 150 to 440 μAm−2 at the crotch, and 500 to 2,230 μAm−2 in the ankle. When grounded through only one foot the current densities at the crotch range from 400 to 1,000 μAm−2 and from 1,000 to 4,400 μAm−2 in the ankle of the grounded leg. Scale transformations of the short‐circuit current with phantom height, weight, and surface area are confirmed.
Specific absorption rate in models of man and monkey at 225 and 2,000 MHz
Authors: Olsen Richard G. , Griner Toby A.
Published: February 2006

Full‐size models of a man and a rhesus monkey were exposed to radiofrequency (RF) radiation at 225 MHz. The model of man was also exposed to 2,000 MHz. Specific absorption rates (SARs) were measured in partial‐body sections, such as the arms, legs, etc., using gradient‐layer calorimeters. Also, front‐surface thermographic images were obtained to qualitatively show the heating patterns. For all of the configurations used, the SAR in the limbs was much higher than in the torso. Agreement (whole‐body SARs) with spheroidal models was better for both models at 225 MHz than at 2,000 MHz. These results indicate that in the frequency range two orders of magnitude above whole‐body resonance, SAR in the limbs significantly contributes to the whole‐body average SAR.
Current densities induced in swine and rat models by power‐frequency electric fields
Authors: Kaune William T. , Forsythe William C.
Published: February 2006

Measurements have been made of vector current densities induced by vertical, uniform, 60‐Hz electric fields in the torsos of homogeneous models of swine and rats. The observed data were a strong function of the five grounding configurations invested: all four feet grounded, only front feet grounded, only rear feet grounded, left front and right rear feet grounded, and right front and left rear feet grounded. In the first configuration and with an exposure field strength of 10 kV/m, average total current densities induced in the torsos of pigs and rats were 34 nA/cm2 and 20 nA/cm2, respectively. The corresponding value for human exposure is about 250 nA/cm2, 7.3 and 12.5 times larger than for swine and rats, respectively. Current densities measured at 60 Hz can be linearly extrapolated to frequencies in a range extending from at least 1 Hz to 1 MHz. Human and animal current‐density data can provide an improved rationale for extrapolating biological data across species. In addition, these data can be used to validate the predictions of numerical models.
A strong static‐magnetic field alters operant responding by rats
Authors: Nakagawa Masayoshi , Matsuda Yuzo
Published: February 2006

Forty male rats of the Wistar ST strain were trained and observed for Sidman avoidance (SA) for 7 weeks or for discriminative avoidance (DA) for 14 weeks to determine the effects of exposure to a strong static‐magnetic field. Before avoidance conditioning was completed, rats in the SA group were exposed to the static field at 0.6 T, 16 h/day for 4 days during the fifth week, and those in the DA group were exposed for 6 h/day for 4 days during the seventh week. In the SA conditioning, frequency of lever‐pressing by exposed rats gradually decreased during 1 week of exposure and stayed low for at least 2 weeks after exposure. Frequencies of electric shocks received by the rats increased dramatically during the second day of exposure and consistently stayed higher than those of control rats. In the DA condition, exposed rats responded at lower rates than did control rats throughout the observation period. They received more shocks during the 2 weeks following exposure. The data indicate that performance of avoidance responses was inhibited by a comparatively long exposure to a strong magnetic field.
Comparative study of shortwave heating patterns in phantoms with polyethylene and silk partitions
Authors: Moon Chun Y. , Kantor Gideon , Athey T. Whit , Ho Henry S.
Published: February 2006

Specific absorption rate (SAR) and effective depths of heating patterns induced by a shortwave, pancake diathermy applicator in fat‐muscle phantom are measured. Midplane partitions of polyethylene and silk screen with and without contact chemicals are used. Thermographically obtained SAR data show nearly the same value for silk‐screen partitions with and without contact chemicals and slightly lower values with polyethylene partitions, provided that the partition midplanes are tightly pressed against each other. Thermometry data indicate that for low‐power exposures the major error in thermographic measurements obtained after termination of heating is due to thermal diffusion and not evaporative cooling in the opened midplane of the phantom.
Measurements of housing density along transmission lines
Authors: Florig H. Keith , Morgan M. Granger
Published: February 2006

One of the fundamental inputs to models of population exposure to the power‐frequency fields of high‐voltage transmission lines is the density of population about the lines. We examined aerial photographs of over 1,700 km of transmission corridor to characterize the density of nearby housing units. The data show that the density of houses within 200 m of transmission lines (1) is typically smaller than the average density of houses in the local utility's service area, (2) tends to increase with distance from the line, and (3) is inversely correlated with line voltage.
Development of young rats and rabbits exposed to a strong electric field
Authors: Portet R. , Cabanes J.
Published: February 2006

Body growth and circulating levels of hormones were assessed in young rats and rabbits exposed to a 50‐Hz electric field of 50 kV/m. Eight‐week‐old male rats were exposed 8 h/ day for 4 weeks and rabbits were exposed 16 h/day from the last 2 weeks of gestation to 6 weeks after birth. The body and the organ growth of exposed rats were not statistically different from those of sham‐exposed controls. No important differences from controls were observed in plasma levels of corticosterone, TSH, ACTH, and T4 or in adrenal levels of epinephrine, norepinephrine, and corticosterone although T3 was slightly, but significantly, decreased. No large histological changes in the thyroid or adrenals were noted. In rabbits, organ and body wieghts of exposed animals were comparable to those of controls. Plasma levels of various hormones (ACTH, GH, T3, T4, corticosterone, cortisol), serum glucose, triglycerides, and cholesterol were not significantly altered. Adrenal content of cortisol was lower, however, in exposed rabbits. No histological changes of the thyroid or adrenal glands were observed.
Microwave‐induced thermoelastic pressure wave propagation in the cat brain
Authors: Lin James C. , Su Jenn‐Lung , Wang Yujin
Published: February 2006

This paper presents direct measurements of acoustic pressure wave propagation in cat brains irradiated with pulsed 2.45‐GHz microwaves. Short rectangular microwave pulses (2 μs, 15 kW peak power) were applied singly through a direct‐contact applicator located at the occipital pole of a cat's head. Acoustic pressure waves were detected by using a small hydrophone transducer, which was inserted stereotaxically into the brain of an anesthetized animal through a matrix of holes drilled on the skull. The measurements clearly indicate that pulsed microwaves induce acoustic pressure waves which propagate with an acoustic wave velocity of 1523 m/s.
Exposure to time varying magnetic fields associated with magnetic resonance imaging reduces fentanyl‐induced analgesia in mice
Authors: Teskey G. Campbell , Ossenkopp Klaus‐Peter , Prato Frank S. , Kavaliers Martin
Published: February 2006

The effects of exposure to clinical magnetic resonance imaging (MRI) on analgesia induced by the mu opiate agonist, fentanyl, was examined in mice. During the dark period, adult male mice were exposed for 23.2 min to the time‐varying (0.6 T/sec) magnetic field (TVMF) component of the MRI procedure. Following this exposure, the analgesic potency of fentanyl citrate (0.1 mg/kg) was determined at 5, 10, 15, and 30 min post‐injection, using a thermal test stimulus (hot‐plate 50°C). Exposure to the magnetic‐field gradients attenuated the fentanyl‐induced analgesia in a manner comparable to that previously observed with morphine. These results indicate that the time‐varying magnetic fields associated with MRI have significant inhibitory effects on the analgesic effects of specific mu‐opiate‐directed ligands.
Influence of microwaves on the beating rate of isolated rat hearts
Authors: Yee Kuo‐Chiang , Chou Chung‐Kwang , Guy Arthur W.
Published: February 2006

Previous reports have shown that microwave exposure can decrease the beating rate of isolated rat hearts. These experiments were conducted at room temperature and with the hearts exposed to air. We observed arrhythmia frequently at room temperature, and the variation of heart beat was so large that it makes the results difficult to reproduce. Therefore, we employed a double‐circulating system to provide perfusion through the coronary artery and around the outside of the heart to maintain the rat hearts at 37.7°C. No arrhythmias were observed in our experiments, and the hearts were beating for at least 1 h. The effects of 16‐Hz modulated 2,450‐MHz pulsed microwaves (10 μs, 100 pps) on the beating rate of 50 isolated rat hearts were studied. Results showed no statistically significant changes of heart rate in exposed groups at SARs of 2 and 10 W/kg compared with the control group. The effect seen at 200 W/kg was shown to be similar to that resulting from heating the heart.
Chronic exposure to elf fields may induce depression
Authors: Wilson Bary W.
Published: February 2006

Exposure to extremely‐low‐frequency (ELF) electric or magnetic fields has been postulated as a potentially contributing factor in depression. Epidemiologic studies have yielded positive correlations between magnetic‐ and/or electric‐field strengths in local environments and the incidence of depression‐related suicide. Chronic exposure to ELF electric or magnetic fields can disrupt normal circadian rhythms in rat pineal serotonin‐N‐acetyltransferase activity as well as in serotonin and melatonin concentrations. Such disruptions in the circadian rhythmicity of pineal melatonin secretion have been associated with certain depressive disorders in human beings. In the rat, ELF fields may interfere with tonic aspects of neuronal input to the pineal gland, giving rise to what may be termed “functional pinealectomy.” If long‐term exposure to ELF fields causes pineal dysfunction in human beings as it does in the rat, such dysfunction may contribute to the onset of depression or may exacerbate existing depressive disorders.
Myelogenous leukemia and electric blanket use
Authors: Preston‐Martin Susan , Peters John M. , Yu Mimi C. , Garabrant David H. , Bowman Joseph D.
Published: February 2006

In a case‐control study of adult acute and chronic myelogenous leukemia in Los Angeles County, we tested the hypothesis that excess exposure to electromagnetic fields from electric blankets was associated with risk of leukemia. We did this by studying 116 cases of acute myelogenous leukemia (AML) and 108 cases of chronic myelogenous leukemia (CML) along with matched neighborhood controls. The cases and controls were queried as to electric blanket use and the risks computed. For AML the risk was 0.9 (95% CI 0.5–1.6) and for CML the risk was 0.8 (95% CI 0.4–1.6). Cases did not differ from controls by duration of use, year of first regular use, year since last use, or socioeconomic status. Our best estimates of exposure indicate that electric blanket use increases overall exposure to electric fields by less than 50% and magnetic fields by less than 100%. We conclude that there is no major leukemogenic risk associated with electric blanket use in Los Angeles County.
Influence of electromagnetic fields on the efflux of calcium ions from brain tissue in vitro: A three‐model analysis consistent with the frequency response up to 510 Hz
Authors: Blackman C. F. , Benane S. G. , Elliott D. J. , House D. E. , Pollock M. M.
Published: February 2006

The frequency dependence of electromagnetic field‐induced calcium‐ion efflux from chicken brain tissues has been examined at 15‐Hz intervals over the range 1–510 Hz. The electric field component was 15 Vrms/m and the magnetic component varied between 59 and 69 nTrms. No patterns of response as a function of frequency could be readily discerned when the differences in mean efflux values between exposed and sham samples were compared. However, the calculated P‐value, a function that combines at each frequency the difference between the means of the exposed and sham groups with the variance of each group, does provide a basis for hypothesizing the existence of three frequency‐dependent patterns in the data. One pattern includes all the highly significant (P < .01) responses which occur between 15 and 315 Hz, at 30‐Hz intervals; two independent trials at 165 Hz, giving nonsignificant responses (P > .5), break this pattern into two groups of five frequencies each, which is contrary to the expected result for a simple Lorentz‐force interaction. However, another pattern of significant results at 60, 90, and 180 Hz, but not at 300 Hz, is consistent with a Lorentz‐force model. A third pattern, composed of only one significant response at 405 Hz, is very close to the resonance predicted on a linear extrapolation from high‐frequency data for 13carbon atoms. This hypothetical ordering of the frequency‐response profile provides the basis for future experimental designs to test each possible interaction model and for their connection to the calcium‐ion efflux endpoint.