摘要:

AbstractThe hypothesis that movement of biological ions may be predicted by cyclotron resonance theory applied to cell membranes is tested in these experiments. Diatoms (Amphora coffeaeformis) were chosen as the biosystem since they move or don't move, depending on how much calcium is transported across the membrane. The experiments demonstrate that a particular ion (calcium) is apparently moved across the cell membrane in response to the DC and AC values of magnetic flux densities (B) and the frequency derived from the cyclotron resonance theory. A clear resonance is shown and a rather sharp frequency response curve is demonstrated. The experiments also show a dose response as the AC value of the flux density is varied, and that odd harmonics of the basic cyclotron frequency are also effective.

ISSN:0197-8462    

DOI:10.1002/bem.2250080302

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

年代:1987

数据来源: WILEY

摘要:

AbstractEvaluations of reproductive and developmental toxicology, including teratology, were included as part of a broad screening study in Hanford Miniature swine (HMS) to detect effects of exposure to electric fields. One group (E) was exposed to a uniform, vertical, 60‐Hz, 30‐kV/m electric field for 20 h/day, 7 days/week sham‐exposed (SE) swine were housed in a separate, environmentally equivalent building. The first generation (F0) gilts were bred after 4 months of study; some were killed for teratologic assays at 100 days of gestation (dg), and the others produced an F1generation of offspring. The pooled incidence of terata in these litters (teratologic assays and live births) was similar in the E and SE groups. The F0females, which produced the F1generation, were bred again after 18 months of exposure and were killed at 100 dg. Malformation incidence in E litters (75%) was significantly greater than in SE litters (29%). No consistent differences in litter size, fetal mass, or mass of fetal organs were detected. The F1gilts were bred at 18 months of age; defective offspring were found in significantly more of the E litters (71 %) than in SE litters (33%). These F1females were bred again 10 months later and teratologic assays were performed on their second litters at 100 dg. The percentage of litters with malformed fetuses was essentially identical in the E and SE groups (70% and 73%, respectively). There appears to be an association between chronic exposure to a strong electric field and developmental effects in swine, although the change in incidence of malformations between generations and between the first and second breedings makes it impossible to conclude unequivocally that there is a cause‐and‐effect

ISSN:0197-8462    

DOI:10.1002/bem.2250080303

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

年代:1987

数据来源: WILEY

摘要:

AbstractPrevious studies have raised the possibility of reproductive and developmental changes in miniature swine chronically exposed to a strong 60‐Hz electric field. Two replicate experiments on rats were performed to determine if similar changes could be detected in animals exposed under a comparable regime, which was based on average, induced‐current densities and on the chronology of reproductive development, as dosimetrically and biologically scaled. Beginning at three months of age, female rats of the F0generation and their subsequent offspring were chronically exposed to a 60‐Hz electric field (100 kV/ m unperturbed) for 19 h/day for the duration of experimentation.After four weeks of exposure, F0female rats were mated to unexposed male rats during the field‐off period. No significant developmental effects were detected in their litters, confirming our previous results with swine and rats. The F0females were mated for a second time at 7.2 months of age, and the fetuses were evaluated shortly before term. In the first experiments, the incidence of intrauterine mortality was significantly less in exposed than in sham‐exposed litters, and there was a tendency (P = 0.12) for an increased incidence of malformed fetuses in exposed litters. Neither end point was significantly affected in the second experiment.Copulatory behavior of the female F1offspring, which were bred at three months of age, was not affected in either experiment. There was a statistically significant decrease in the fertility of F1exposed females and a significant increase in the fraction of exposed litters with malformed fetuses in the first experiment; both end points were essentially the same in the sham and exposed groups of the second experiment.That the significant effects detected in the first experiment were not seen in the second may be attributed to random or biological variation. Alternatively, the finding may indicate that the response threshold for induction of malformations lies near

ISSN:0197-8462    

DOI:10.1002/bem.2250080304

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe rate of the electromagnetic energy deposition and the resultant thermoregulatory response of a block model of a squirrel monkey exposed to plane‐wave fields at 350 MHz were calculated using a finite‐difference procedure. Noninvasive temperature measurements in live squirrel monkeys under similar exposure conditions were obtained using Vitek probes. Calculations exhibit reasonable correlation with the measured data, especially for the rise in colonic temperat

ISSN:0197-8462    

DOI:10.1002/bem.2250080305

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

年代:1987

数据来源: WILEY

摘要:

AbstractExperimental studies showed an increase in the growth ofBacillus subtilismutant 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 ofBacillus subtiliscan be altered as a result of magnetic‐fiel

ISSN:0197-8462    

DOI:10.1002/bem.2250080306

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis study was designed to determine the changes that occur in the thermoregulatory ability of the immature rat repeatedly exposed to low‐level microwave radiation. Beginning at 6–7 days of age, previously untreated rats were exposed to 2,450‐MHz continuous‐wave microwaves at a power density of 5 mW/cm2for 10 days (4 h/day). Microwave and sham (control) exposures were conducted at ambient temperatures (Ta) which represent different levels of cold stress for the immature rat (ie, “exposure” Ta= 20 and 30 °C). Physiological tests were conducted at 5–6 and 16–17 days of age, in the absence of microwaves, to determine pre‐ and postexposure responses, respectively. Measurements of metabolic rate, colonic temperature, and tail skin temperature were made at “test” Ta= 25.0, 30.0, 32.5, and 35.0 °C. Mean growth rates were lower for rats exposed to Ta= 20°C than for those exposed to Ta= 30°C, but microwave exposure exerted no effect at either exposure Ta. Metabolic rates and body temperatures of all exposure groups were similar to values for untreated animals at test Taof 32.5 °C and 35.0 °C. Colonic temperatures of rats repeatedly exposed to sham or microwave conditions at exposure Ta= 20 °C or to sham conditions at exposure Ta= 30 °C were approximately 1°C below the level for untreated animals at test Taof 25.0 °C and 30.0 °C. However, when the exposure Tawas warmer, rats exhibited a higher colonic temperature at these cold test Ta, indicating that the effectiveness of low‐level microwave treatment to alter thermoregulatory responses depends o

ISSN:0197-8462    

DOI:10.1002/bem.2250080307

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

年代:1987

数据来源: WILEY

摘要:

AbstractFemale CD‐1 mice were injected with an LD50dose ofStreptococcus pneumoniaeand 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

ISSN:0197-8462    

DOI:10.1002/bem.2250080308

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

年代:1987

数据来源: WILEY

摘要:

AbstractRats were trained to press levers to indicate the presence or absence of 60‐Hz vertical electric fields at intensities from 0 to 27 kV/m (rms). The probability of detecting the field increased as the strength of the field increased. The shape of the detection curve (psychometric function) for most subjects (Ss) was similar whether the discriminative stimulus was the electric field or a tone. Two protocols were used to estimate the minimum field intensity necessary to detect the field (Reiz Limen, RL). The RL was estimated to be 13.3 kV/m (rms) when using one protocol (the staircase method) and 7.9 kV/m (rms) when using another protocol (the method of constant stimuli

ISSN:0197-8462    

DOI:10.1002/bem.2250080309

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

年代:1987

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250080301

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

年代:1987

数据来源: WILEY