摘要:

AbstractThe 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 potentia

ISSN:0197-8462    

DOI:10.1002/bem.2250010402

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe 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

ISSN:0197-8462    

DOI:10.1002/bem.2250010403

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe 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

ISSN:0197-8462    

DOI:10.1002/bem.2250010404

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

年代:1980

数据来源: WILEY

摘要:

AbstractAlthough exposure to nonionizing electromagnetic radiation has been reported to cause a variety of systemic alterations during embryonic development, there are few reports of the induction of specific physiologic or morphologic changes in the myocardium. This study was designed to examine the effects of microwave radiation on cardiogenesis in Japanese quail embryos exposed during the first eight days of development to 2.45‐GHz continuous‐wave microwaves at power densities of 5 or 20 mW/cm2. The specific absorption rates were 4.0 and 16.2 mW/g, respectively. The ambient temperature for each exposure was set to maintain the embryonated eggs at 37.5 °C. This did not preclude thermal gradients in the irradiated embryos since microwaves may not be uniformly absorbed. The test exposure levels did not induce changes in either the morphology of the embryonic heart or the ultrastructure of the myocardial cells. Analysis of the enzymatic activities of lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatine phosphokinase failed to reveal any statistically significant differences between the nonexposed controls and those groups exposed to either 5 or 20 mW/cm2. The data indicate that 2.45‐GHz microwave radiation at 5 or 20 mW/cm2has no effect on the measured variables of the Japanese quail myocardium exposed during the first eight days of devel

ISSN:0197-8462    

DOI:10.1002/bem.2250010405

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

年代:1980

数据来源: WILEY

摘要:

AbstractA 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 virulentStreptococcus 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 an

ISSN:0197-8462    

DOI:10.1002/bem.2250010406

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

年代:1980

数据来源: WILEY

摘要:

AbstractIn attempting to evaluate the mechanisms responsible for susceptibility to the inductive increase in splenic complement receptor‐positive (CR+) cells following exposure to 2450‐MHz microwaves, it was found that sensitivity to microwave‐induced CR+cell increases was under genetic control. In particular, evidence was accumulated suggesting that regulation was under the control of a gene or genes closely associated with but outside of the mouse major histocompatibility complex (H‐2). All responsive strains of mice tested were of the H‐2khaplotype, while mice of the H‐2a, H‐2b, H‐2dand H‐2i5haplotypes were refractory to the microwave‐induced increases in CR+cells. By utilizing certain H‐2kstrains of mice that were genetically unable to respond to endotoxin, we were able to show that these strains of mice responded to microwaves, but not to endotoxin, by increasing CR+cells. Microwave‐induced increases in CR+cells were not mimicked by the intraperitoneal injection of hydrocortisone. Athymic mice responded to microwave exposure, indicating that this event was not regulated by the T‐cell population. Mice less than eight weeks old were found not to be susceptible to exposure to 2450‐MHz microwaves. These studies indicate that microwaves do induce changes in the population of cells with specific cell‐surface receptors, that susceptibility to these changes is under genetic control, and that it is unlikely that endotoxin, corticosteroids, or regulatory T cells play a significant role in the mechanis

ISSN:0197-8462    

DOI:10.1002/bem.2250010407

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

年代:1980

数据来源: WILEY

摘要:

AbstractA 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 b

ISSN:0197-8462    

DOI:10.1002/bem.2250010408

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

年代:1980

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250010409

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

年代:1980

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250010401

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

年代:1980

数据来源: WILEY