ISSN:0197-8462    

DOI:10.1002/bem.2250090202

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

年代:1988

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250090203

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

年代:1988

数据来源: WILEY

摘要:

AbstractFertilized eggs ofGallus domesticuswere exposed continuously during their 21‐day incubation period to either 50‐ or 60‐Hz sinusoidal electric fields at an average intensity of 10 Vrms/m. The exposure apparatus was housed in an environmental room maintained at 37°C and 55–60% relative humidity (RH). Within 1.5 days after hatching, the chickens were removed from the apparatus and tested. The test consisted of examining the effect of 50‐ or 60‐Hz electromagnetic fields at 15.9 Vrms/m and 73 nTrms (in a local geomagnetic field of 38 μT, 85°N) on efflux of calcium ions from the chicken brain. For eggs exposed to 60‐Hz electric fields during incubation, the chicken brains demonstrated a significant response to 50‐Hz fields but not to 60‐Hz fields, in agreement with the results from commercially incubated eggs [Blackman et al., 1985a]. In contrast, the brains from chicks exposed during incubation to 50‐Hz fields were not affected by either 50‐ or 60‐Hz fields. These results demonstrate that exposure of a developing organism to ambient power‐line‐frequency electric fields at levels typically found inside buildings can alter the response of brain tissue to field‐induced calcium‐ion efflux. The physiological significance of this

ISSN:0197-8462    

DOI:10.1002/bem.2250090204

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper presents direct measurements of acoustic pressure wave propagation in cat brains irradiated with pulsed 2.45‐GHz microwaves. Short rectangular microwave pulses (2 μs, 15 kW peak power) were applied singly through a direct‐contact applicator located at the occipital pole of a cat's head. Acoustic pressure waves were detected by using a small hydrophone transducer, which was inserted stereotaxically into the brain of an anesthetized animal through a matrix of holes drilled on the skull. The measurements clearly indicate that pulsed microwaves induce acoustic pressure waves which propagate with an acoustic wave velocity of 1523

ISSN:0197-8462    

DOI:10.1002/bem.2250090205

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

年代:1988

数据来源: WILEY

摘要:

AbstractFemale DBA/2 mice at 8 weeks of age were implanted with P388 leukemia cells in groups of ten mice and exposed to a 60‐Hz 1.4‐μT, 200‐μT, or 500‐μT magnetic field 2‐3 hours after the implant for 6 hours daily, 5 days/week until all the exposed P388‐treated and nontreated mice died. Parallel exposed groups of non‐P388‐treated mice and P388‐treated mice exposed at 0 μT were included for study. No statistically significant differences (P>.05) in survival, spleen weight, or body weight resulted between P388‐treated or nontreated mice from exposure to the magnetic field. No effect on the incidence or progression of P38

ISSN:0197-8462    

DOI:10.1002/bem.2250090206

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

年代:1988

数据来源: WILEY

摘要:

AbstractStatic magnetic fields affect the diffusion of biological particles in solutions through the Lorentz force and Maxwell stress. These effects were analyzed theoretically to estimate the threshold field strength for these effects. Our results show that the Lorentz force suppresses the diffusion of charged particles such as Na+, K+, Ca2+, Cl‐, and plasma proteins. However, the threshold is so high, i.e., more than 104T, that the Lorentz force does not affect the ion diffusion at typical field strengths (a few Tesla at most). Since the threshold of gradient fields for producing a change in ion diffusion through the Maxwell stress is more than 105T2/m for paramagnetic molecules (FeCl3, O2) and plasma proteins, their diffusion would be unaffected by typical gradient fields (100 T2/m at most) and even by high gradient fields (less than 105T2/m) used in magnetic separation techniques. In contrast, movement of deoxygenated erythrocytes and FeCl3colloids (more than 103molecules) is influenced by the usual gradient fields due to a volume effec

ISSN:0197-8462    

DOI:10.1002/bem.2250090207

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe effects of exposure to clinical magnetic resonance imaging (MRI) on analgesia induced by the mu opiate agonist, fentanyl, was examined in mice. During the dark period, adult male mice were exposed for 23.2 min to the time‐varying (0.6 T/sec) magnetic field (TVMF) component of the MRI procedure. Following this exposure, the analgesic potency of fentanyl citrate (0.1 mg/kg) was determined at 5, 10, 15, and 30 min post‐injection, using a thermal test stimulus (hot‐plate 50°C). Exposure to the magnetic‐field gradients attenuated the fentanyl‐induced analgesia in a manner comparable to that previously observed with morphine. These results indicate that the time‐varying magnetic fields associated with MRI have significant inhibitory effects on the analgesic effects of specific mu‐opiate‐

ISSN:0197-8462    

DOI:10.1002/bem.2250090208

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

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious reports have shown that microwave exposure can decrease the beating rate of isolated rat hearts. These experiments were conducted at room temperature and with the hearts exposed to air. We observed arrhythmia frequently at room temperature, and the variation of heart beat was so large that it makes the results difficult to reproduce. Therefore, we employed a double‐circulating system to provide perfusion through the coronary artery and around the outside of the heart to maintain the rat hearts at 37.7°C. No arrhythmias were observed in our experiments, and the hearts were beating for at least 1 h. The effects of 16‐Hz modulated 2,450‐MHz pulsed microwaves (10 μs, 100 pps) on the beating rate of 50 isolated rat hearts were studied. Results showed no statistically significant changes of heart rate in exposed groups at SARs of 2 and 10 W/kg compared with the control group. The effect seen at 200 W/kg was shown to be similar to that resulting from heating th

ISSN:0197-8462    

DOI:10.1002/bem.2250090209

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

年代:1988

数据来源: WILEY

摘要:

AbstractA chicken tendon explant model system has been developed to investigate the effects of extremely‐low‐frequency (ELF), low‐amplitude, unipolar, square wave pulsed electric fields on fibroplasia in vitro. An electric field parameter set consisting of 1‐Hz, 1‐ms duration pulses, with a time‐averaged current density of 7 mA/m2(peak current density 7 A/m2) induced maximal (32%) increase in fibroblast proliferation in tendon explants exposed for 4 days. Exposure to the same field at an average current density of 1.8 mA/ m2had no effect on fibroblast proliferation, whereas exposure to current densities on>10 mA/m2inhibited proliferation and relative collagen synthesis, without affecting noncollagen protein synthesis. Fibroplasia was significantly increased in explants oriented parallel to applied electric fields having current densities of 3.5 or 7 mA/m2, but there was no detectable effect on explants oriented perpendicular to the same electric field. Fibroblast proliferation and relative collagen synthesis were inversely proportional to donor age for chickens in the 3‐ to 16‐week age group used in this study. For these dependent variables (proliferation and relative collagen synthesis), there was no interaction between donor age and ELF electric

ISSN:0197-8462    

DOI:10.1002/bem.2250090210

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

年代:1988

数据来源: WILEY

摘要:

AbstractExposure to extremely‐low‐frequency (ELF) electric or magnetic fields has been postulated as a potentially contributing factor in depression. Epidemiologic studies have yielded positive correlations between magnetic‐ and/or electric‐field strengths in local environments and the incidence of depression‐related suicide. Chronic exposure to ELF electric or magnetic fields can disrupt normal circadian rhythms in rat pineal serotonin‐N‐acetyltransferase activity as well as in serotonin and melatonin concentrations. Such disruptions in the circadian rhythmicity of pineal melatonin secretion have been associated with certain depressive disorders in human beings. In the rat, ELF fields may interfere with tonic aspects of neuronal input to the pineal gland, giving rise to what may be termed “functional pinealectomy.” If long‐term exposure to ELF fields causes pineal dysfunction in human beings as it does in the rat, such dysfunction may contribute to the onset of depression or may exacerbate existing d

ISSN:0197-8462    

DOI:10.1002/bem.2250090211

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

年代:1988

数据来源: WILEY