摘要:

AbstractThis report describes some experimental measurements of the internal field levels induced within isolated chick‐forebrains irradiated at 50, 147, and 450 MHz, under essentially the same conditions as those used in the in vitro calcium‐ion efflux experiments. Ratios of incident power at 50/147 MHz and 147/450 MHz that are needed to establish the same probe output are given and comparisons made with values predicted by different spherical models. Data predicted by the layered‐sphere model were found to be in close agreement with measured values for the 50/147‐MHz ratio. Agreement for the 147/450‐MHz ratio w

ISSN:0197-8462    

DOI:10.1002/bem.2250050302

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

年代:1984

数据来源: WILEY

摘要:

AbstractNumber of circulating hemocytes and hemolymph protein patterns of adult worker honey bees were analyzed as possible indicators of stress resulting from colony placement under a 765‐kV transmission line. Although exposure to 55, 80, and 95 μA total induced hive current (THC) produced colony behavioral disturbance, there were no consistent effects on mean hemocyte counts at 55‐ or 95‐μA THC. Age‐dependent declines in circulating hemocyte number were similar in all exposure groups. There were no consistent differences in tube‐gel electropherograms. No consistent differences were found in two‐density slab‐gel electropherograms based on ultrasensitive silver stain. The 67 positively charged and four negatively charged protein fractions from overwintering bees are two‐ to threefold more than currently reported

ISSN:0197-8462    

DOI:10.1002/bem.2250050303

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

年代:1984

数据来源: WILEY

摘要:

AbstractTimed‐pregnancy rats were exposed in a circular waveguide system starting on day 2 of gestation. The system operated at 2,450 MHz (pulsed waves; 8 μs PW; 830 pps). Specific absorption rate (SAR) was maintained at 0.4 W/kg by increasing the input power as the animals grew in size. On day 18 of gestation the dams were removed from the waveguide cages and euthanized; the fetuses were removed and weighed. Fetal brains were excised and weighed, and brain RNA, DNA and protein were determined. Values for measured parameters of the radiated fetuses did not differ significantly from those of sham‐exposed fetuses. A regression of brain weight on body weight showed no micrencephalous fetuses in the radiation group when using as a criterion a regression line based on two standard errors of the estimate of the sham‐exposed group. In addition, metrics derived from brain DNA (ie, cell number and cell size) showed no significant differences when radiation was compared to sham exposure. We conclude that 2,450‐MHz microwave radiation, at an SAR of 0.4 W/kg, did not produce significant alterations in brain organ

ISSN:0197-8462    

DOI:10.1002/bem.2250050304

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

年代:1984

数据来源: WILEY

摘要:

AbstractMicrowaves (pulsed, 2,450 MHz) at an average power density of 3 W/cm2were applied directly to the head for 5, 10, or 20 min, producing a peak specific absorption rate of 240 W/kg in the brain, which, after a 10‐min exposure, resulted in brain temperatures in excess of 43°C. A bolus of86Rb in isotonic saline was injected intravenously and an arterial sample was collected for 20 s to determine cardiac output. Compared with unexposed controls, uptake of86Rb increased most in those regions directly in the path of the irradiation, namely, the occipital and parietal cortex, as well as the dorsal hippocampus, midbrain, and basal ganglia. In a separate group of animals, regional brain‐vascular spaces were found to increase with brain temperature. These results support previous observations indicating that reliably demonstrable increases of blood‐brain barrier permeability are associated with intense, microwave‐induced hyperthermia, and that the observed changes are not due to field‐specific i

ISSN:0197-8462    

DOI:10.1002/bem.2250050305

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

年代:1984

数据来源: WILEY

摘要:

AbstractSeventeen birds from 12 flocks were exposed to microwave radiation under various combinations of power density and duration; three birds from two additional flocks served as sham‐exposed controls. Experiments were conducted outdoors at Manomet, Massachusetts (41°56′N, 70°35′W) under normal winter ambient temperatures. Although irradiated birds maintained their positions within a flock hierarchy with one exception, some appeared to have a change in their level of aggression after e

ISSN:0197-8462    

DOI:10.1002/bem.2250050306

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

年代:1984

数据来源: WILEY

摘要:

AbstractCultures of human tonsil lymphocytes were exposed in a Crawford cell to a 450‐MHz field (peak envelope intensity 1.0 mW/cm2), sinusoidally amplitude modulated (depth 80%) at frequencies between 3 and 100 Hz for periods up to 60 min. The Crawford cell was housed in a temperature‐controlled chamber (35°C) and control cultures were placed in the same chamber. Activity of cAMP‐dependent protein kinase relative to controls remained unaltered by fields modulated at 16 or 60 Hz with exposures of 15, 30, and 60 min. By contrast, total non‐cAMP‐dependent kinase activity fell to less than 50% of unexposed control levels after 15 and 30 min exposures, but, despite continuing field exposure, returned to control or preexposure levels by 45 and 60 min. A smaller reduction (20–25%) also occurred with 60‐Hz modulation and was also restricted to exposure durations of 15 and 30 min. CW 450‐MHz fields were without effect. Reduced enzyme activity occurred with 16‐, 40‐, and 60‐Hz modulation frequencies, but not with 3‐, 6‐, 80‐, or 100‐Hz modulation. The specific identity of this kinase is unknown. This rapid but transient reduction in lymphocyte protein kinase activity restricted to modulation frequencies between 16 and 60 Hz and to less than 30 min exposure is consistent with „windowing”︁ with respect to modula

ISSN:0197-8462    

DOI:10.1002/bem.2250050307

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe membrane potential of isolated cells ofChara brauniiorNitella flexiliswas monitored while the cells were exposed, at nominal power densities from 2 to 1,000 W/m2, to 147‐MHz radiation amplitude modulated at frequencies from 4 to 64 Hz. Phase‐sensitive detection was used to seek radiation‐correlated changes in the membrane potential, and none were apparent under any of the conditions used in this investig

ISSN:0197-8462    

DOI:10.1002/bem.2250050308

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

年代:1984

数据来源: WILEY

摘要:

AbstractSingle giant cells of the algaeChara brauniiandNitella flexiliswere exposed to bursts of electromagnetic radiation (monochromatic CW, bichromatic CW, or squarewave‐modulated) in the band 200–1,000 MHz while their vacuolar potentials were monitored using micropipettes. The slow hyperpolarizing response that was observed seemed to be linear in the power deposited in the vicinity of the cell, to be otherwise indifferent to irradiation frequency or modulation, and therefore to be thermal in ori

ISSN:0197-8462    

DOI:10.1002/bem.2250050309

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

年代:1984

数据来源: WILEY

摘要:

AbstractShort‐circuit currents, surface electric fields, and axial current densities were measured in electrically grounded guinea pigs exposed to a uniform, vertical, ELF electric field. These data are 70–110% of corresponding values obtained in grounded rats exposed to the same electric fi

ISSN:0197-8462    

DOI:10.1002/bem.2250050310

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

年代:1984

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250050301

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

年代:1984

数据来源: WILEY