bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave effects on energy metabolism of rat brain
Authors: Sanders Aaron P. , Schaefer Daniel J. , Joines William T.
Published: February 2006

Rat brain was exposed to 591‐MHz, continuous‐wave (CW) microwaves at 13.8 or 5.0 mW/cm2 to determine the effect on nicotinamide adenine dinucleotide, reduced (NADH), adenosine triphosphate (ATP) and creatine phosphate (CP) levels. On initiation of the in vivo microwave exposures, fluorimetrically determined NADH rapidly increased to a maximum of 4.0%–12.5% above pre‐exposure control levels at one‐half minute, then decreased slowly to 2% above control at three minutes, finally increasing slowly to 5% above control level at five minutes. ATP and CP assays were performed on sham‐ and microwave‐exposed brain at each exposure time. At 13.8 mW/cm2, brain CP level was decreased an average of 39.4%, 41.1%, 18.2%, 13.1%, and 36.4% of control at exposure points one‐half, one, two three, and five minutes, respectively, and brain ATP concentration was decreased an average of 25.2%, 15.2%, 17.8%, 7.4%, and 11.2% of control at the corresponding exposure periods. ATP and CP levels of rat brain exposed to 591‐MHz cw microwaves at 5 mW/cm2 for one‐half and one minute were decreased significantly below control levels at these exposure times, but were not significantly different from the 13.8 mW/cm2 exposures. For all exposures, rectal temperature remained constant. Heat loss through the skull aperture caused brain temperature to decrease during the five‐minute exposures. This decrease was the same in magnitude for experimental and control subjects. Changes in NADH, ATP, and CP levels during microwave exposure cannot be attributed to general tissue hyperthermia. The data support the hypothesis that microwave exposure inhibits mitochondrial electron transport chain function, which results in decreased ATP and CP levels in brain.
Effects of 60‐Hz electric fields on avoidance behavior and activity of rats
Authors: Hjeresen Dennis L. , Kaune William T. , Decker John R. , Phillips Richard D.
Published: February 2006

In repeated short‐term tests (four sessions, each of 45‐minute duration), and one longer test (a 23.5‐hour session), behavior of rats was evaluated in a long, narrow shuttlebox. One side of the box was exposed to an electric field at various strengths, while a visually identical opposite side was shielded from exposure. In the short‐term tests, rats generally remained shielded from electric fields of 90 kV/m and greater during the first session, and maintained this response in subsequent sessions. In the longer test, this same preference response was demonstrated at field strengths of 75 kV/m and greater; however, at 25 and 50 kV/m, rats exhibited a statistically significant preference for the exposed region of the shuttlebox, but only during the light portion of a 12‐hour light: 12‐hour dark cycle. Exposed animals made more traverses than sham‐exposed controls between the two ends of the shuttlebox during the first hour of the test. The experimental data support the hypothesis that the observed behavioral effects are the result of direct interaction of the electric field with the animal, and not the result of secondary factors such as electric shock, corona discharge, audible noise, ozone, or vibration of the experimental apparatus.
Studies on microwave and blood‐brain barrier interaction
Authors: Lin James C. , Lin Mei F.
Published: February 2006

This investigation was aimed at correlating changes of blood‐brain‐barrier permeability with the quantity and distribution of absorbed microwave energy inside the brain of adult Wistar rats anesthetized by sodium pentobarbital. Through use of thermographic methods and a direct‐contact applicator at the animal's head, the pattern of absorbed microwave energy was determined. Indwelling catheters were placed in the femoral vein and in the left external carotid artery. Evans blue and sodium fluorescein in isotonic saline were used as visual indicators of barrier permeation. Exposure to pulsed 2,450‐MHz radiation for 20 min at average power densities of 0.5, 1, 5, 20, 145 or 1,000 mW/cm2, which resulted in average specific absorption rates (SARs) of 0.04, 0.08, 0.4, 1.6, 11.5 or 80.0 mW/g in the brain, did not produce staining, except in the pineal body, the pituitary gland, and the choroid plexus — regions that normally are highly permeable. Except for these regions, staining was also absent in the brains of sham‐exposed animals. The rectal temperature, as monitored by a copper‐constantan thermocouple, showed a maximum increase of less than 0.75°C from a mean pre‐exposure temperature of 36.6°C. The highest brain temperature recorded in a similar group of animals using a thickfilm carbon thermistor was less than 41.0°C.
Dosimetry for a study of effects of 2.45‐GHz microwaves on mouse testis
Authors: Cairnie A. B. , Hill D. A. , Assenheim H. M.
Published: February 2006

In order to determine the effects of microwave radiation on the testis, it is necessary to express the physical insult in animal studies in a way that can be replicated elsewhere and ultimately used as a basis for extrapolation to man. However, there is conflict — especially in chronic experiments — between the desire for precise dosimetry and the need to minimise alteration of the normal physiological functions of the animals. The compromise arrangement used in this study was to house the mice singly, in cages with limited food and water, and to irradiate them for up to 30 days (16 h/day) in an anechoic chamber. The only measurements taken routinely were of power density in the positions normally occupied by the cages. In addition, a series of absorption measurements was made in mouse carcasses: Whole‐body specific absorption rate (SAR); energy‐deposition patterns (determined thermographically); and local SAR in testis (using a miniature electric (E)‐field probe). It was concluded that the SAR in testis was considerably less than the whole‐body SAR. Exposure for 16 h at 50 mW/cm2 elevated rectal but not testis temperature, thus demonstrating the ability of the conscious mouse to regulate the temperature of its testis.
A computer model of temperature distribution inside a lossy sphere after microwave radiation
Authors: Janna W. S. , Russo E. P. , McAfee R. , Davoudi Reza M.
Published: February 2006

The temperature distribution inside a lossy sphere resulting from the absorption of microwave energy was approximated by successive numerical iterations, of the thermal energy equation. Heat transfer within the sphere by conduction was considered. In the model energy was not dissipated by convection but was contained in the sphere for over 200 seconds. Exposure of a 5‐cm sphere to 3,000 MHz at 30 mW/cm2 for 200 seconds was calculated to produce a temperature rise of 0.56°C near the front surface.
Microwave radiation (2450 MHz) alters the endotoxin‐induced hypothermic response of rats
Authors: Smialowicz R. J. , Compton K. L. , Riddle M. M. , Rogers R. R. , Brugnolotti P. L.
Published: February 2006

The parenteral administration of bacterial endotoxin to rats causes a hypothermia that is maximal after approximately 90 minutes. When endotoxin‐injected rats were held in a controlled environment at 22°C and 50% relative humidity and exposed for 90 minutes to microwaves (2450 MHz, CW) at 1 mW/cm2, significant increases were observed in body temperature compared with endotoxintreated, sham‐irradiated rats. The magnitude of the response was related to power density (10 mW/cm2 > 5 mW/cm2 > 1 mW/cm2). Saline‐injected rats exposed for 90 minutes at 5 mW/cm2 (specific absorption rate approximately 1.0 mW/g) showed no significant increase in body temperature compared with saline‐injected, sham‐irradiated rats. The hypothermia induced by endotoxin in rats was also found to be affected by ambient temperature alone. Increases in ambient temperature above 22°C in the absence of microwaves caused a concomitant increase in body temperature. This study reveals that subtle microwave heating is detectable in endotoxin‐treated rats that have an impaired thermoregulatory capability. These results indicate that the interpretation of microwave‐induced biological effects observed in animals at comparable rates and levels of energy absorption should include a consideration of the thermogenic potential of microwaves.
Plane‐wave spectrum approach for the calculation of electromagnetic absorption under near‐field exposure conditions
Authors: Chatterjee I. , Gandhi O. P. , Hagmann M. J. , Riazi A.
Published: February 2006

The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researchers. We have used the plane‐wave‐spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi‐infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free‐space wavelength, the energy coupled into the target is approximately equal to that resulting from plane‐wave exposure.
Electromagnetic absorption in a multilayered slab model of tissue under near‐field exposure conditions
Authors: Chatterjee I. , Hagmann M. J. , Gandhi O. P.
Published: February 2006

The electromagnetic energy deposited in a semi‐infinite slab model consisting of skin, fat, and muscle layers is calculated for both plane‐wave and near‐field exposures. The plane‐wave spectrum (PWS) approach is used to calculate the energy deposited in the model by fields present due to leakage from equipment using electromagnetic energy. This analysis applies to near‐field exposures where coupling of the target to the leakage source can be neglected. Calculations were made for 2,450 MHz, at which frequency the layered slab adequately models flat regions of the human body. Resonant absorption due to layering is examined as a function of the skin and fat thicknesses for plane‐wave exposure and as a function of the physical extent of the near‐field distribution. Calculations show that for fields that are nearly constant over at least a free‐space wavelength, the energy deposition (for the skin, fat, and muscle combination that gives resonant absorption) is equal to or less than that resulting from plane‐wave exposure, but is appreciably greater than that obtained for a homogeneous muscle slab model.
Alteration of circulating antibody response of mice exposed to 9‐GHz pulsed microwaves
Authors: Liddle C. G. , Putnam J. P. , Ali J. S. , Lewis J. Y. , Bell B. , West M. W. , Lewter O. H.
Published: February 2006

A significant increase was observed in the circulating antibody titers of mice exposed to 9‐GHz pulsed microwaves at an average power density of 10 mW/ cm2, two hours per day for five days compared with sham‐irradiated animals. The mice were previously immunized with type III pneumococcal polysaccharide. Following irradiation, a portion of the immunized animals were challenged with virulent Streptococcus pneumoniae, type III. Ten days after challenge, mortality was essentially the same in the two groups, but during the ten day period, there was a noticeable increase in the survival time of the irradiated animals compared with the sham‐irradiated animals, suggesting that the increased circulating antibody response afforded some degree of temporary protection to the animals.
Microwave irradiation and instrumental behavior in rats: Unitized irradiation and behavioral evaluation facility
Authors: Lebovitz R. M. , Seaman R. L.
Published: February 2006

A facility for the exposure of small animals to pulse‐modulated microwave radiation (PM MWR) concurrent with their performance of operant behavioral tasks is described. The computer‐managed facility comprises an array of 32 individual waveguide exposure cells, each enclosing instrumental conditioning apparatus within a plastic subhousing. The distribution of the microwave electric field intensity within the waveguide was measured by a nonperturbing probe and the modifications induced by the behavioral apparatus and animal within the waveguide determined. Input and interior voltage standing wave ratios are presented to characterize the design of the chambers and to demonstrate the suitability of the chambers for whole‐body irradiation of rat. The specific absorption rate (SAR) is presented utilizing data derived from incremental thermometric examination of saline loads and of selected sites in rat carcasses. This is compared with the whole‐body SAR derived from the input/ output energy balance equation for the waveguide. The results of continuous monitoring of the SAR by the latter method, while unrestrained rats were engaged in operant and exploratory behavior within the waveguide, are utilized to derive a relationship between chamber input power and the dose rate for adult rats behaviorally active within the waveguide. From these data, we conclude that the experimental array provides a practical method for exposing a large number of animals to PM MWR for long periods of time and coincident with the establishment and/or performance of complex operant behavior.
Fluorescence depolarization studies of red cell membrane fluidity. The effect of exposure to 1.0‐GHz microwave radiation
Authors: Allis John W. , Sinha Barbara L.
Published: February 2006

The internal viscosity of human red blood cell membranes was investigated during exposure to continuous wave 1.0‐GHz microwave radiation using fluorescence measurements of a lipid seeking molecular probe, diphenylhexatriene. Samples were exposed in a Crawford cell arranged so that fluorescence was measured during microwave exposure; specific absorption rates calculated from electrical measurements were approximately 0.6, 2 and 15 W/kg. Measurements were obtained at selected temperatures between 15 °C and 40 °C and as a function of the duration of exposure at 23 °C. Arrhenius‐type plots of the temperature profile data were linear and showed no difference between exposed and control samples. The exposure duration data also showed no difference between exposed and control samples except for a small effect of elevated temperature at the highest exposure. The activation energy for motion of the fluorescent probe in its environment within the membrane lipid was not affected by the application of the microwave energy and no evidence for a lipid phase transition was found. These results indicate that the increased cation efflux from red cells, observed by others at certain transition temperatures during microwave exposure, was more likely to have been caused by alteration of the membrane bound protein than by changes in the lipid constituents of the red cell membrane.
Biological effects of oscillating electric fields: Role of voltage‐sensitive ion channels
Authors: Cain Charles A.
Published: February 2006

An alternating component of potential across the membrane of an excitable cell may change the membrane conductance by interacting with the voltagesensing charged groups of the protein macromolecules that form voltage‐sensitive ion channels. Because the probability that a voltage sensor is in a given state is a highly nonlinear function of the applied electric field, the average occupancy of a particular state will change in an oscillating electric field of sufficient magnitude. This “rectification” at the level of the voltage sensors could result in conformational changes (gating) that would modify channel conductance. A simplified two‐state model is examined where the relaxation time of the voltage sensor is assumed to be considerably faster than the fastest changes of ionic conductance. Significant changes in the occupancy of voltage sensor states in response to an applied oscillating electric field are predicted by the model.
Interactive effects in 60‐HZ electric‐field exposure systems
Authors: Kaune William T.
Published: February 2006

The level of exposure of laboratory animals to 60‐Hz electric fields is commonly specified in terms of the unperturbed field strength present before the introduction of experimental subjects and their cages. In the research reported in this paper, rats were housed in two parallel rows of 12.4 cm × 25.1 cm × 10.2 cm high plastic cages resting on the lower electrode of a parallel‐plate exposure system, and the actual perturbed electric fields experienced by an experimental animal were investigated. The most important results are: 1) Reducing the spacing between the exposure electrodes from 8.7 to 1.7 times the height of a singly exposed rat model, while maintaining a constant unperturbed field strength, resulted in a 15% increase in the electric field at the highest point on the surface of the body and a 10% increase in the short‐circuit current of the model. 2) For multiple animal exposures, increases of 10% in both the field at the highest point of the body and the short‐circuit current were observed when the electrode spacing was reduced from 8.7 to 2.6 times the height of a rat. 3) Plastic cages caused 1 – 6% reductions in the electric field at the surface of the body, except very near the cage walls, where enhancements of more than 20% were observed. 4) When 16 rats were simultaneously exposed, the short‐circuit current, Is, of an individual subject of weight W (in g), that was surrounded on all sides by other rats of weight W, was reduced from the short‐circuit current, Iu, measured with the same subject individually exposed as follows: during a 12 h light (sleeping) cycle, Is/Iu = 1.00 – 0.0173W1/2; during a 12 h night (awake) cycle, Is/Iu = 1.00 – 0.0136W1/2.
Radiofrequency electromagnetic fields in swedish radio stations and tall FM/TV towers
Authors: Mild Kjell Hansson
Published: February 2006

Radiofrequency electric and magnetic fields have been measured around 11 large broadcast stations and tall FM/TV towers in Sweden. The results show that operating personnel may be exposed to fields exceeding by several times the present standard for occupational exposure to RF radiation. Maintenance personnel are especially vulnerable to exposure when climbing energized towers. The present study indicates that the transmitters should be switched off during the performance of certain tasks on the tower. Safe passage of maintenance personnel near energized antennas of certain types is impossible without a drastic reduction of the transmitted power. In the stations, the RF leakage radiation was generally low, but when work was done with the cabinet doors of the transmitter open, high field strengths were found in the vicinity of the transmitter even though it was switched off. It was found that the transmitter acted as a tuned receiver of energy from the other transmitters.
Microwave treatment of intracerebral l1210 leukemia: Schedule‐dependent partial reversal of the effects of methotrexate
Authors: Chang Barbara K. , Huang Andrew T. , Joines William T.
Published: February 2006

One‐GHz microwave (MW) irradiation at a power density of 5 mW/cm2 was combined with methotrexate (MTX) in an attempt to treat more effectively central nervous system (CNS) L1210 leukemia in DBA/2J mice. When mice with CNS leukemia were treated with the combination of MW and MTX, there was no improvement in survival compared with a group of animals treated with MTX alone; however, the group that received MTX before the MW exposure had a significantly reduced survival time compared with the group treated with MTX alone or with the group to which MTX was administered after MW.
Effect of short electromagnetic pulses on brain acetylcholine content and spontaneous motor activity of mice
Authors: Modak A. T. , Stavinoha W. B. , Deam A. P.
Published: February 2006

Mice were exposed to a single 15‐ms or 25‐ms pulse of 2,450‐MHz microwaves which increased brain temperature by 2 °C or 4 °C, respectively. Immediately after exposure, the mice became hypokinetic but began recovering within 5 minutes. The 25‐ms pulse (18.7 j deposited in the brain) caused a significant decrease in acetylcholine content of the whole brain, probably owing to increased permeability of the membrane.
Endocrinological effects of strong 60‐Hz electric fields on rats
Authors: Free Michael J. , Kaune William T. , Phillips Richard D. , Cheng Hsien‐Chen
Published: February 2006

Adult male rats were exposed or sham‐exposed to 60‐Hz electric fields without spark discharges, ozone, or significant levels of other secondary variables. No effects were observed on body weights or plasma hormone levels after 30 days of exposure at an effective field strength of 68 kV/m. After 120 days of exposure (effective field strength = 64 kV/m), effects were inconsistent, with significant reductions in body weight and plasma levels of follicle‐stimulating hormone and corticosterone occurring in one replicate experiment but not in the other. Plasma testosterone levels were significantly reduced after 120 days of exposure in one experiment, with a similar but not statistically significant reduction in a replicate experiment. Weanling rats, exposed or sham‐exposed in electric fields with an effective field strength of 80 kV/m from 20 to 56 days of age, exhibited identical or closely similar growth trends in body and organ weights. Hormone levels in exposed and sham‐exposed groups were also similar. However, there was an apparent phase shift between the two groups in the cyclic variations of concentrations of hormones at different stages of development, particularly with respect to follicle‐stimulating hormone and corticosterone. We concluded that 60‐Hz electric fields may bring about subtle changes in the endocrine system of rats, and that these changes may be related to alterations in episodic rhythms.
Effects of millimeter‐wave radiation on monolayer cell cultures. I. Design and validation of a novel exposure system
Authors: Partlow L. M. , Bush L. G. , Stensaas L. J. , Hill D. W. , Riazi A. , Gandhi O. P.
Published: February 2006

A method has been devised whereby both the thermal and possible athermal biological effects resulting from microwave radiation can be assessed. Monolayer cultures of BHK‐21/C13 cells were grown on microwave‐transparent polystyrene coverslips, placed directly on the open end of a wave guide, and irradiated for 1 hour. In experiments seeking athermal biological effects of millimeter waves, culture medium was continuously recirculated over the cells to prevent temperature increases greater than 0.1 °C. Incorporation of 3H‐uridine into RNA and of 3H‐methionine into protein was quantified by measurement of optical densities of the autoradiographs in contiguous rectangular regions corresponding to portions of the cell monolayer immediately above the wave guide aperture and lying along its longer axis. Since power density was shown to vary with position along this axis according to a cosine2 relationship, it was possible to assess the extent of microwave effects on macromolecular synthesis at power densities ranging from zero at each edge to twice the average power density at the center of the waveguide.

Monolayer cultures maintained at 37.2 °C by recirculation of the medium did not show microwave‐induced changes in synthesis of RNA and protein (41.8 or 74.0 GHz at average power densities of 320 or 450 mW/cm2, respectively). Since macromolecular synthesis was examined both during and after irradiation, our results exclude both transient and persistent athermal biological effects of acute exposure to millimeter waves. In contrast, irradiation of cultures incubated in a small volume of nonrecirculated medium resulted in 1) marked heating of the monolayer, 2) a graded decline in macromolecular synthesis with increasing incident power, and 3), in some cases, destruction of the cell monolayer in the region immediately above the center of the waveguide aperture.
Development of xenopus laevis embryos in a static magnetic field
Authors: Mild Kjell Hansson , Sandström Monic , Løvtrup Søren
Published: February 2006

Xenopus laevis embryos were exposed to a DC magnetic field (2.5 kG) for periods up to 1 week. The previously reported stabilization of cell membranes by stationary magnetic fields could not be demonstrated.
Chronic exposure to a 60‐Hz electric field: Effects on neuromuscular function in the rat
Authors: Jaffe R. A. , Laszewski B. L. , Carr D. B.
Published: February 2006

Neuromuscular function in adult male rats was studied following 30 days of exposure to a 60‐Hz electric field at 100 kV/m (unperturbed field strength). Isometric force transducers were attached to the tendons of the plantaris (predominantly fast twitch), and soleus (predominantly slow twitch) muscles in the urethan‐anesthetized rat. Square‐wave stimuli were delivered to the distal stump of the transected sciatic nerve. Several measurements were used to characterize neuromuscular function, including twitch characteristics, chronaxie, tetanic and posttetanic potentiation, and fatigue and recovery. The results from three independent series of experiments are reported. Only recovery from fatigue in slow‐twitch muscles was consistently and significantly affected (enhanced) by electrifield exposure. This effect does not appear to be mediated by field‐induced changes in either neuromuscular transmission, or in the contractile mechanism itself. It is suggested that the effect may be mediated secondary to an effect on mechanisms regulating muscle blood flow or metabolism.
Effect of nonionizing radiation on the purkinje cells of the uvula in squirrel monkey cerebellum
Authors: Albert E. N. , Sherif M. F. , Papadopoulos N. J.
Published: February 2006

Pregnant squirrel monkeys were exposed to 2450‐MHz (CW) microwaves at an equivalent power density of 10 mW/cm2 (SAR 3.4 mW/g) for three hours daily in a cavity‐cage module. The exposure began when pregnancy was determined by a hormonal method, and continued through the offspring's first 9.5 months. After irradiation, the brains of the offspring were fixed with formaldehyde, and the inferior vermis of each cerebella was removed and processed for histologic observations. Purkinje cell density in the uvula was determined in sagittal serial sections. There was no significant difference between control and experimental animals in the number of Purkinje cells per mm of Purkinje cell line (linear density), as well as in the density of Purkinje cells in the Purkinje cell layer.
Biological effects of long‐term exposure of rats to 970‐MHz radiofrequency radiation
Authors: Smialowicz R. J. , Weil C. M. , Marsh P. , Riddle M. M. , Rogers R. R. , Rehnberg B. F.
Published: February 2006

Rats (N = 16) exposed individually in circularly polarized waveguides to 970‐MHz electromagnetic radiation (SAR=2.5 mW/g, 22 h daily for 70 consecutive days) had significantly higher serum levels of triglycerides, albumin, and total protein compared with sham‐irradiated controls. No difference was observed in the weights, hematologic profile, or in vitro lymphocyte responses to mitogens between these two groups. The higher serum levels of triglycerides in radiofrequency‐radiation‐exposed rats suggest a non‐specific stress reaction.
Effects of intermittent 60‐Hz high voltage electric fields on metabolism, activity, and temperature in mice
Authors: Rosenberg R. S. , Duffy P. H. , Sacher G. A.
Published: February 2006

Transient effects of 100‐kV/m extremely low frequency electric fields were studied in the white footed deermouse, Peromyscus leucopus. Gross motor activity, carbon dioxide production, oxygen consumption, and core body temperature were monitored before, during, and after intermittent field exposures (four hour‐long exposures, at one‐hour intervals). Thirty‐four mice were exposed in cages with plastic floors floating above ground potential, and 21 mice were exposed in cages with grounded metal floor plates. The first field exposure produced an immediate, transient increase of activity and gas measures during the inactive phase of the circadian cycle. All measures returned to baseline levels before the second exposure and were not significantly changed throughout the remainder of the exposures. The rapid habituation of field‐induced arousal suggests that significant metabolic changes will not be measured in experiments in which the interval between exposure and measurement is greater than two hours.
Longevity and food consumption of microwave‐treated (2.45 GHz Cw) honeybees in the laboratory
Authors: Westerdahl Becky Brown , Gary Norman E.
Published: February 2006

Adult honeybees, confined singly or in small clusters, were exposed for 0.5, 6, and 24 hours to 2.45‐GHz continuous wave microwave radiation at power densities of 3, 6, 12, 25, and 50 mW/cm2. Following exposure, bees were held in the incubator for 21 days to determine the consumption of sucrose syrup and to observe mortality. No significant differences were found between microwave‐treated and sham‐treated or control bees.
Inhibition and recovery of growth processes in roots of pisum sativum L. Exposed to 60‐Hz electric fields
Authors: Robertson Dominique , Miller Morton W. , Cox Christopher , Davis Henry T.
Published: February 2006

Roots of Pisum sativum L. were chronically exposed in aqueous inorganic nutrient medium to 60‐Hz electric fields between 140 and 490 V/m (growth medium conductivity ∼ 0.08 S/m). The growth rate, meristematic mitotic index, and growth rate recovery of the roots were determined. At 140 V/m there was no perturbation in growth rate or mitotic index. At 430 V/m the growth rate and the mitotic index were reduced. The mitotic index had a maximum depression (∼ 55% of control), which occurred at 4 h. The depression in growth rate was immediate and constant over time. When roots were exposed to an electric field at 430 V/m for 2 days, the growth rate was depressed by about 40%. When the field was terminated, the growth rate steadily increased and was almost normal after 5 days. At 490 V/m root growth rate was almost completely arrested. According to these results, there is a narrow range of induced membrane potentials that span the range from slightly altered to almost completely arrested growth rates.
Thermoregulatory physiologic responses in the human body exposed to microwave radiation
Authors: Way W. I. , Kritikos H. , Schwan H.
Published: February 2006

By introduction of an additional compartment in the hypothalamic region Stolwijk's thermo‐regulatory model has been modified to consider partial heating due to hot spots induced by microwaves. It was found that because of thermoregulatory action, the temperature of the hypothalamus will not increase drastically until the rate of energy deposition exceeds the threshold level of about 50 mW/g. The primary controlling mechanisms are blood flow and sweating. For an energy deposition rate of 10 mW/g in the hypothalamus the increase in blood flow in the skin is negligible and the temperature rise of the hypothalamus as compared with blood temperature is about 0.5 °C. It was found that exposure of the head to electromagnetic radiation, in general, causes a decrease in temperature of the trunk and skin. The results show that while the deposition of energy in the hypothalamus at the rate of 10 mW/g produced significant conductive and convective effects, the same total energy uniformly distributed over the cranial cavity produces less significant effects.
Chronic exposure to 60‐Hz electric fields: Effects on pineal function in the rat
Authors: Wilson Bary W. , Anderson Larry E. , Ian Hilton D. , Phillips Richard D.
Published: February 2006

As a component of studies to search for effects of 60‐Hz electric field exposure on mammalian endocrine function, concentrations of melatonin, 5‐methoxytryptophol, and serotonin‐Nacetyl transferase activity were measured in the pineal glands of rats exposed or sham‐exposed at 65 kV/m for 30 days. In two replicate experiments there were statistically significant differences between exposed and control rats in that the normal nocturnal increase in pineal melatonin content was depressed in the exposed animals. Concentrations of 5‐methoxytryptophol were increased in the pineal glands of the exposed groups when compared to shamexposed controls. An alteration was also observed in serotonin‐N‐acetyl transferase activity, with lower levels measured in pineal glands from exposed animals.
Growth and metabolism of rodents exposed to 60‐Hz electric fields
Authors: Hilton D. I. , Phillips R. D.
Published: February 2006

There have been a number of reports in the literature concerning growth‐related changes in various animal species exposed to high‐strength electric fields. Many of the laboratories reporting such effects have not documented and controlled for the secondary factors that are associated with generating high‐strength electric fields (ie, corona, ozone, harmonic distortion, cage vibration, spark discharge). We have designed an exposure system in which we eliminated or minimized these secondary factors, therefore enabling us to examine only the effects of electric fields per se. Sprague‐Dawley rats and Swiss‐Webster mice were exposed to 60‐Hz electric fields at kV/m for up to four months. In 17 individual experiments, we found a greater number of experiments in which the exposed rats had lower body weights than controls. This trend was not evident in data obtained from 14 individual mouse experiments. In more exhaustive growth studies, we found no significant differences in body weights, organ weights, or O2 consumption between exposed and sham‐exposed controls. Our failure to detect any major changes in growth was probably the result of eliminating or minimizing the secondary factors associated with electric field exposure.
Temporal variation of the static electric field inside an animal cage
Authors: Shigemitsu Tsukasa , Tsuchida Yoshikazu , Nishiyama Fumihiko , Matsumoto Goro , Nakamura Hiroshi , Shimizu Koichi
Published: February 2006

The temporal variation of a static electric field inside an animal cage was investigated with a newly developed small, simple field meter. The field inside the cage was found to be highly dependent on the surface conductivity of the dielectric material. As the surface of the cage became dirty because of animal occupancy, the static electric field inside it became considerably smaller from the moment the field was turned on. Clean cages also modified the static electric field inside them, the field decaying from an initial to a much lower value over several hours. The mechanism of field attenuation for both cases is surface leakage. Surface leakage for a clean cage takes place much more slowly than for a dirty cage. This was confirmed by measuring DC insulation resistance. To examine this phenomenon further, the field in a metal cage with high electrical conductivity was measured. The static electric field inside the metal cage was also found to be reduced. An improved cage design that avoids these problems, is suggested for the study of the biologic effects of static electric fields.
Power‐frequency electric fields averaged over the body surfaces of grounded humans and animals
Authors: Kaune William T.
Published: February 2006

Calculated electric‐field strengths averaged over the body surfaces of grounded humans, swine, rats, horses, and cattle exposed to vertical, uniform, power‐frequency electric fields are presented. To produce the same average fields over the body surfaces of grounded animals, as that experienced by a grounded man exposed to an unperturbed vertical field of 10 kV/m, the following unperturbed fields are required: swine, 19 kV/m; rat, 37 kV/m; horse, 18 kV/m; cow, 18 kV/m.
The dielectric method of investigating bound water in biological material: An appraisal of the technique
Authors: Grant E. H.
Published: February 2006

Three independent dielectric methods for the measurement of water of hydration (bound water) in a biological material are described and discussed comparatively. For well‐defined aqueous solutions of biological molecules, hydration can be obtained from direct observations made on the δ dispersion or from measurement of the dielectric values of the β dispersion. For whole tissue, however, neither of these two methods is applicable, and to deduce the hydration, it is necessary to use the third technique in which the volume of the hydrated biological particle is obtained by measuring the effect of it on the known dielectric properties of pure water. The hydration can then be calculated by deducting the volume of the anhydrous particle from the experimentally determined volume of the hydrated particle. Owing to possible systemmatic errors the uncertainty in the absolute hydration value associated with this technique is rather larger than that obtained with the other two dielectric methods. For studying the differences between hydration in similar tissues, however, this objection disappears.
Dielectric probe of the electric‐field‐sensitive peptide alamethicin
Authors: Schwarz G. , Savko P.
Published: February 2006

Dielectric constant and loss of alamethicin in solvents of various degrees of lipophilicity (namely mixtures of n‐octanol and dioxane) have been measured at frequencies from 5 kHz to 50 MHz. By means of a conventional Cole‐Cole approach, dielectric properties were evaluated to obtain information about the structural and dipolar properties of the peptide in view of its function as a voltage‐dependent pore former in membranes. The results for a pure octanol solvent (together with an apparent molecular weight determined by ultracentrifugation) indicate the existence of primarily monomeric particles of quite elongated shape and of comparatively high dipole moment. Adding dioxane was found to yield considerable aggregation and a decrease of polarity.
What are non‐thermal electric biological effects?
Authors: Fröhlich H.
Published: February 2006

A discussion of the general implication of the existance of non‐thermal biological effects of electromagnetic fields is presented.
Electromagnetic absorption in an inhomogeneous model of man for realistic exposure conditions
Authors: Gandhi O. P.
Published: February 2006

The advances made in quantifying electromagnetic absorption and its distribution for various exposure profiles are described. The conditions that have been studied extensively are: free‐space irradiation and its variations, such as the presence of ground and reflecting surfaces and other humans in close proximity. Using an inhomogeneous block model of man, work has recently been extended to leakage‐type near‐fields such as those from RF heat sealers and other electronic equipment. Projections are made for the extension of this work to evaluate coupled near‐fields, design of multielement near‐field applicators to obtain physician‐prescribed uniform or nonuniform rates of regional heating, and for the inverse scattering problem necessary for electromagnetic biomedical imaging. Accurate information about the dielectric properties of various tissues becomes increasingly important for proper inhomogeneous modeling of man.
Active electric properties of cardiac muscle
Authors: Geselowitz David B. , Miller W. T.
Published: February 2006

A model of electrical activity in the heart has been developed that treats the intracellular domain and the extracellular domain as electrical syncytia with anisotropic resistivities (bi‐syncytial model). At the microscopic level, propagation is assumed to proceed primarily along the axes of individual cells. Considerations at the macroscopic level relate the transmembrane current to the intracellular and extracellular resistivity and the transmembrane potential. The result is a relationship between instantaneous extracellular potentials and cardiac action potentials.
Analysis of inphase interaction pattern in EEG
Authors: Meleis Hanafy , Takashima Shiro , Harner Richard N.
Published: February 2006

Inphase interactions among EEG signals recorded using eight electrodes were investigated. The inphase interaction parameters are presented in two ways: (1) matrix form in which the number of inphase interactions are tabulated; and (2) histogram in which the number of inphase interactions are plotted pair‐wise between two sites as a function of phase delays in milliseconds. The highest number of interactions occurs between 0 and 8 ms in normal brains.

The values of interaction parameters are enhanced by various activities. For example, inphase interaction parameters increase in the motor area in the right hemisphere if the EEG is recorded during repeated left fist clenching. Inphase interactions are drastically altered by the presence of a tumor. We studied the inphase interactions of the EEG of a patient having an occipital tumor. The interaction parameters are greatly diminished in this area, indicating a severe impairment of neuronal communications between both hemispheres in the occipital region.

The confidence limits of the changes in inphase interaction parameters during fist clenching are tested statistically using the Student's t test. The test shows that the interaction parameters increase, in general, with 1–5% confidence limits in respective cortex areas as a result of fist clenching.
Biological effects of low‐temporal, average‐intensity, pulsed ultrasound
Authors: Carstensen Edwin L.
Published: February 2006

Studies with both plant and animal tissues show that, when the tissues contain micron‐sized, stabilized gas bodies, pulsed ultrasound can produce damage at very low time‐averaged intensities. However, it is the temporal peak intensity rather than the time‐averaged intensity that is closely correlated with the effects observed. The data suggest that there may be thresholds for damage at peak intensities within an order of magnitude of 10 W/cm2.
Wideband acoustic energy studies of pulmonary airways
Authors: Jacobs John E.
Published: February 2006

The impulse response of the pulmonary system has been measured by exciting the system with wideband acoustic noise introduced through the mouth. The transmitted sound is detected using microphones placed on the patient's back at appropriate locations. A specially designed analog correlator is used to obtain the impulse response of the pulmonary system through cross‐correlation techniques. Uniquely characteristic responses have been obtained from smoking and nonsmoking patient groups.
Investigation of the effects of continuous‐wave, pulse‐ and amplitude‐modulated microwaves on single excitable cells of chara corallina
Authors: Liu Li‐Ming , Garber Francine , Cleary Stephen F.
Published: February 2006

Single internodal excitable cells of Chara corallina were exposed to CW, pulse‐modulated and sinusoidally modulated S‐band microwave fields in a temperature‐controled waveguide exposure chamber. All electrical measurements were made external to the waveguide (ie, under no impressed microwave field). The dependent variables measured before, during, and after exposure to the S‐band microwave fields included: resting potential, amplitude of the action potential, rise and decay time of the action potential, conduction velocity, and excitability. Cells maintained at 22 ± 0.1 °C during exposure showed no consistent or statistically significant microwave‐dependent alterations in any of the dependent variables.
Temperature dependence of ultrasound‐induced cell killing: The role of membrane fluidity
Authors: Ben‐Hur E. , Green M.
Published: February 2006

Chinese hamster cells in suspension were exposed to 20 kHz ultrasound (US) at 54 W/cm2 and various temperatures between 2 and 44 °C. Activation energies were 2.6 and 24 kcal/mole below and above 35 °C, respectively. Procaine, a local anaesthetic drug known to increase membrane fluidity, enhanced cellular inactivation by US above 41 °C, increasing the activation energy to 62 kcal/mole. The inactivation of the bacterium Salmonella typhimurium by US was also dependent on the exposure temperature, with an activation energy of 2.9 kcal/mole between 2 and 44 °C. These data are most simply explained by the hypothesis that membranes are a major target for cellular inactivation by US and that the fluidity of the membranes is important in this respect.
Reduced weight in mice offspring after in utero exposure to 2450‐MHz (CW) microwaves
Authors: Berman Ezra , Carter Hershell B. , House Dennis
Published: February 2006

Time‐bred CD‐1 mice (100) were sham‐irradiated or irradiated with 2450‐MHz (CW) microwaves at 28 mW/cm2 for 100 minutes daily from the 6th through 17th day of gestation. The offspring were examined either as fetuses after hysterotomy on the 18th day of gestation or as naturally born neonates on the 1st and 7th day of age. Fetuses of half of the dams were examined on the 18th day of gestation. The incidence of pregnancy and the numbers of live, dead, resorbed, and total fetuses were similar in both groups. The mean weight was significantly lower (10%) in live microwave‐irradiated fetuses, and ossification of sternal centers was significantly delayed. In the offspring that were born naturally, the mean weight of microwave‐irradiated 7‐day‐old suckling mice was significantly lower (10%) than that of the sham‐irradiated group. Survival rates of neonates in these two groups were not different. These data demonstrate that the decreased fetal weight seen in microwave‐irradiated mice is retained at least 7 days after birth. Evidence from other published studies is presented to show that the retarded growth is persistent and might be interpreted as permanent stunting.
Low frequency amplitude modulated microwave fields change calcium efflux rates from synaptosomes
Authors: Lin‐Liu S. , Adey W. R.
Published: February 2006

Calcium(45Ca2 +) efflux from preloaded synaptosomes was studied with a continuous perfusion technique and the rate constants of a two‐phase efflux process calculated. When 16‐Hz sinusoidally amplitude modulated 450‐MHz microwave field (maximal incident intensity 0.5 mW/ cm2, modulation depth 75%) was applied during the second phase, the rate constant increased by 38%. Unmodulated or 60‐Hz modulated signals were not effective. This microwave fieldinduced change can be distinguished from CaCl2‐stimulated 45Ca2 + efflux which is most probably derived intracellularly. These data suggest that the microwave‐field‐induced change in calcium efflux probably did not involve intracellular calcium. Also, this change in the dynamic property of synaptosomes did not require gross anatomically intact tissue as a substrate for field tissue interaction.
Fluorescence depolarization studies of the phase transition in multilamellar phospholipid vesicles exposed to 1.0‐GHz microwave radiation
Authors: Allis John W. , Sinha Barbara L.
Published: February 2006

The phase transition in multilamellar dimyristoylphosphatidylcholine (DMPC) vesicles was studied during exposure to continuous wave 1.0‐GHz microwave radiation. Fluorescence depolarization measurements using a lipid‐seeking molecular probe, diphenylhexatriene (DPH). were performed as a function of temperature. Semilog plots of microviscosity versus temperature illustrate the phase transition which shows a 5°C shift when the vesicles are treated with chloroform as a positive control. No shift of the phase transition was found during exposure to microwave radiation at specific absorption rates between 1 and 30 W/kg. Samples were exposed in a rectangular transmission line (TEM cell), and specific absorption rates were calculated from electrical measurements of incident, reflected, and transmitted power. Samples were exposed to increasing intensities of radiation, while the temperature was maintained at either 23.5 or 25.5 °C; these temperatures represented the two ends of the phase transition region for these vesicles. No statistically significant difference was found between exposed and control samples. These results are in contrast to those of others using laser Raman spectroscopy to measure the phase transition in similar multilamellar vesicles exposed to microwave radiation.