摘要:

AbstractNormal human lymphocytes were isolated from the peripheral blood of healthy donors. One‐ml samples containing (106) cells in chromosome medium 1A were exposed for 5 days to conventional heating or to continuous wave (CW) or pulsed wave (PW) 2450‐MHz radiation at non‐heating (37°C) and various heating levels (temperature increases of 0.5, 1.0, 1.5, and 2 °C). The pulsed exposures involved 1‐μs pulses at pulse repetition frequencies from 100 to 1,000 pulses per second at the same average SAR levels as the CW exposures. Actual average SARs ranged to 12.3 W/kg. Following termination of the incubation period, spontaneous lymphoblastoid transformation was determined with an image analysis system. The results were compared among each of the experimental conditions and with sham‐exposed cultures. At non‐heating levels, CW exposure did not affect transformation. At heating levels both conventional and CW heating enhanced transformation to the same extent and correlate with the increases in incubation temperature. PW exposure enhanced transformation at non‐heating levels. This finding is significant (P<.002). At heating levels PW exposure enhanced transformation to a greater extent than did conventionalor CW heating. This finding is significant at the .02 level. We conclude that PW 2450‐MHz radiation acts differently on the process of lymphoblastoid transformation in vitro compared with CW 2450‐MHz radiation at the same average SARs. ©

ISSN:0197-8462    

DOI:10.1002/bem.2250130402

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to reproduce and extend an earlier investigation of the effects of human exposure to combined, 60‐Hz electric and magnetic fields. This paper presents the neurobehavioral results. Thirty men participated in one training session and four testing sessions. Subjects were randomly assigned to two groups. The 18 subjects in Group I were exposed (9 kV/m, 20 μT) and sham exposed in two counterbalanced orders. In Group II, half of 12 subjects were exposed (9 kV/m, 20 μT) every session, and the remaining half were sham exposed every session. The study was doubly blinded. Measures of cardiac interbeat interval, event‐related brain potentials, and performance were obtained before, during, and after exposures. As in the earliers study, exposure to the combined field resulted in a statistically significantly slowing of heart rate, in changes in late components of eventrelated brain potentials, and in decreased errors on a choice reaction‐time task. In addition, field effects on several other measures approached statistical significance. The physiological measures obtained during exposure indicated that effects were greatest soon after the field was switched on, and again when it was switched off. The data indicate thatchangesin exposure level may be more important than duration of exposure for producing effects in human beings. © 1992 Wiley

ISSN:0197-8462    

DOI:10.1002/bem.2250130403

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

年代:1992

数据来源: WILEY

摘要:

AbstractA model has been developed that permits assessment of residential exposure to 60‐Hz magnetic fields emitted by appliances. It is based on volume‐ and time‐averaging of magnetic‐dipole fields. The model enables the contribution of appliances in the total residential exposure to be compared with that of other sources in any residence under study. Calculations based on measurements reported in the literature on 98 appliances revealed that appliances are not a significant source of whole‐body exposure, but that they may be the dominant source of exposure of the body's extremities. © 1992 Wiley

ISSN:0197-8462    

DOI:10.1002/bem.2250130404

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

年代:1992

数据来源: WILEY

摘要:

AbstractIsolated rat hearts and excised canine cardiac tissues were subjected to pulsed magnetic fields. The fields excited in coils by tandem pairings of sinusoidal pulses were presented at various inter‐pair delays and repetition rates. The waveform of the magnetic field was a single or multiple sinusoid followed after a variable delay by another single or multiple sinusoid. Small but reliable increases in the beating rate of rat heart were observed. Similar increases occurred in contraction rates of canine tissues. Both preparations exhibited a contraction‐rate dependency on the repetition rate of the paired magnetic pulses: 4.5–6 rep/s for canine tissue, and 20–25 and 40–55 reps/s for rat heart. Flux‐density thresholds for both preparations approximated 10 mT (100 gauss) rms. © 1992 Wil

ISSN:0197-8462    

DOI:10.1002/bem.2250130405

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe calculated distribution of electric fields induced in homogeneous human and rat models by a 60‐Hz magnetic field is compared with values measured in instrumented mannequins. The calculated values agree well with measured values. 1992 Wiley‐Liss,

ISSN:0197-8462    

DOI:10.1002/bem.2250130406

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

年代:1992

数据来源: WILEY

摘要:

AbstractRadio‐frequency electromagnetic radiation (RFR) at 915 and at 147 MHz, when sinusoidally amplitude modulated (AM) at 16 Hz, has been shown to enhance release of calcium ions from neuroblastoma cells in culture. The dose‐response relation is unusual, consisting of two power‐density “windows” in which enhanced efflux occurs, separated by power‐density regions in which no effect is observed. To explore the physiological importance of these findings, we have examined the impact of RFR exposure on a membrane‐bound enzyme, acetylcholinesterase (AChE), which is intimately involved with the acetylcholine (ACh) neurotransmitter system. Neuroblastoma cells (NG108), exposed for 30 min to 147‐MHz radiation, AM at 16 Hz, demonstrated enhanced AChE activity, as assayed by a procedure using14C‐labeled ACh. Enhanced activity was observed within a time window between 7.0 and 7.5 h after the cells were plated and only when the exposure occurred at power densities identified in a previous report as being effective for altering the release of calcium ions. Thus RFR affects both calcium‐ion release and AChE activity in nervous system‐derived cells in culture in a common dose‐dependent manne

ISSN:0197-8462    

DOI:10.1002/bem.2250130407

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

年代:1992

数据来源: WILEY

摘要:

AbstractSingle, 1.25‐GHz microwave pulses of 0.8‐ to 1.0‐μs duration were presented to each of four rats 100 ms before presentation of a startle‐inducing acoustic stimulus. This sequential pairing of microwave pulse and acoustic stimulus was found to modify the startle response. At an energy dose to the head of 22–43 mJ/kg per pulse (peak SAR, 23–48 kW/kg), the mean latency to the startle response was longer and the mean amplitude of the response was smaller with respect to control responses that occurred to acoustic stimuli alone. However, at a higher energy dose per microwave pulse in the range of 59–107 mJ/kg (peak SAR, 63–111 kW/kg), the mean latency and amplitude of the startle response were not statistically different from the respective means of control responses. 1992

ISSN:0197-8462    

DOI:10.1002/bem.2250130408

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

年代:1992

数据来源: WILEY

摘要:

AbstractAlternating currents can increase or decrease the ATP‐splitting activity of the membrane enzyme Na,K‐ATPase. Either change depends on the AC frequency, and the greatest effect appears to be in the ELF range at about 100 Hz. The threshold for enzyme inhibition by AC was determined, and it is estimated to be an internal electric field circa 5 μV/cm. The corresponding current‐density threshold approximates 8 nA/cm2. 1992 Wiley‐L

ISSN:0197-8462    

DOI:10.1002/bem.2250130409

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

年代:1992

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250130401

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

年代:1992

数据来源: WILEY