摘要:

AbstractWe previously demonstrated that exposure of salivary gland cells of the dipteran,Sciara coprophila, to either asymmetrical or symmetrical changing magnetic fields results in an increase in the incorporation of radioactive uridine into RNA. The present report is an analysis of the grain count distribution over the X chromosome of Sciara in transcription autoradiograms following exposure of the salivary gland cells to two pulsed magnetic signals and a 72‐Hz sine wave signal. The results show augmented uptake of3H‐uridine into nascent RNA chains following short exposures of the cells to magnetic fields. Transcription is augmented in previously active loci, as well as at chromosome regions that are not detectable as active in control cells. The quantitative pattern of RNA synthesis in transcription autoradiograms is hypothesized to be signal specific on the basis of differences in grain counts over significantly labelled chromosome si

ISSN:0197-8462    

DOI:10.1002/bem.2250080102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractJapanese quail (Coturnix coturnix japonica) embryos were irradiated continuously in ovo with 2.45‐GHz continuous wave radiation during the first 12 days of embryogenesis at an incident power of 5 mW/cm2and a specific absorption rate of 4.03 mW/g. The internal temperature of irradiated and nonirradiated (sham) eggs was 37.5 ± 0.3 °C, which is the optimum temperature for incubating quail eggs. At 35 days after hatching irradiated and sham‐irradiated males were paired with irradiated or sham‐irradiated females and daily records of reproductive performance were collected through 224 days of age. Progeny were hatched from each of the male‐female pairs, and progeny reproductive performance was measured from 35 through 168 days of age. Hatchability was not affected by irradiation during embryogeny. Mortality after hatching, egg production, egg weight, fertility, hatchability of eggs produced, and reproductive performance of the progeny were not affected by irradiation during embryogeny. These observations indicate that irradiation of quail embryos with low‐level microwave radiation does not affect the reproductive capacity of the hatchlings or of progeny produced from quail irradiated during

ISSN:0197-8462    

DOI:10.1002/bem.2250080103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMeasurements have been made of the permittivity and conductivity of normal and wounded human skin material over the frequency range 10 MHz‐10 GHz. The permittivity of the wounded tissue was found to be about 12% higher than that of the normal tissue. A similar percentage increase was observed for the conductivity. These differences are attributed to the presence of a higher proportion of bulk water in the wounded materia

ISSN:0197-8462    

DOI:10.1002/bem.2250080104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFor the study of electromagnetic dosimetry and hyperthermia, it is necessary to simulate human biological materials. This can be done by chemical mixtures that are described in this paper. Formulas are presented for simulating bone, lung, brain, and muscle tissue in the frequency range of 100 MHz to 1 GHz. By using these preparations a realistic equivalent to the human body can be constructed.

ISSN:0197-8462    

DOI:10.1002/bem.2250080105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMale 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

ISSN:0197-8462    

DOI:10.1002/bem.2250080106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe 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

ISSN:0197-8462    

DOI:10.1002/bem.2250080107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractSerial longitudinal and transverse sections were prepared from roots ofCucumis sativusandCucurbita maximathat had been exposed/sham‐exposed to 60‐Hz electric fields for 0–2 days. Field exposures were selected to produce a 10–20% or a 70–80% growth inhibition in whole roots of both species. Cortical cell length and diameter were measured using a microscope and eyepiece micrometer; measurements were conducted “blind”. In both species, inhibition of cellular elongation was associated with exposure to electric fields (EF). Cellular radial expansion was apparently unaffected by exposure to electric fields. The diameters of radially unexpanded or fully expandedC. sativuscortical cells were about 25–30% smaller than those of comparable cells inC. maximaroots. Previous studies of the relationship between rates of root growth and applied EF strength showed that the response thresholds ofC. sativusandC. maximadiffered by a similar relative amount. These results are consistent with the postulate that EF‐induced effects in roots are elicited by induced transme

ISSN:0197-8462    

DOI:10.1002/bem.2250080108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA previous study showed a substantial increase in the colonic temperature of rhesus monkeys (Macaca mulatta) exposed to radiofrequency (RF) fields at a frequency near whole‐body resonance and specific absorption rates (SAR) of 2–3 W/kg. The present experiments were conducted to determine the metabolic anad vasomotor responses during exposures to similar RF fields. We exposed five adult male rhesus monkeys to 225 MHz radiation (E orientation) in an anechoic chamber. Oxygen consumption and carbon dioxide production were measured before, during, and after RF exposure. Colonic, tail and leg skin temperatures were continuously monitored with RF‐nonperturbing probes. The monkeys were irradiated at two carefully‐controlled ambient temperatures, either cool (20 °C) or thermoneutral (26 °C). Power densities ranged from 0 (sham) to 10.0 mW/cm2with an average whole‐body SAR of 0.285 (W/kg)/(mW/cm2). We used two experimental protocols, each of which began with a 120‐min pre‐exposure equilibration period. One protocol involved repetitive 10‐min RF exposures at successively higher power densities with a recovery period between exposures. In the second protocol, a 120‐min RF exposure permitted the measurement of steady‐state thermoregulatory responses. Metabolic and vasomotor adjustments in the rhesus monkey exposed to 225 MHz occurred during brief or sustained exposures at SARs at or above 1.4 W/kg. The SAR required to produce a given response varied with ambient temperature. Metabolic and vasomotor responses were coordinated effectively to produce a stable deep body temperature. The results show that the thermoregulatory response of the rhesus monkey to an RF exposure at a resonant frequency limits storage of heat in the body. However, substantial increases in colonic temperature were not prevented by such responses, even

ISSN:0197-8462    

DOI:10.1002/bem.2250080109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA simple method for measuring microwave power density is described. It is applicable to situations where exposure of samples in the near field of a horn is necessary. A transmitted power method is used to calibrate the power density entering the surface of the sample. Once the calibration is available, the power density is known in terms of the incident and reflected powers within the waveguide. The calibration has been carried out for liquid samples in a quartz cell. Formulas for calculating specific absorption rate (SAR) are derived in terms of the power density and the complex dielectric constant of the sample. An error analysis is also given.

ISSN:0197-8462    

DOI:10.1002/bem.2250080110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractSpecific absorption rates were measured in three locations of humans exposed in the far field at 160, 350, and 915 MHz. Values obtained for six males are compared with data for a full‐scale homogeneous model of ma

ISSN:0197-8462    

DOI:10.1002/bem.2250080111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY