摘要:

AbstractWire codes, introduced by Wertheimer and Leeper as a surrogate for residential magnetic fields, divide imputed exposure into several categories based on the configurations of electrical wiring within 40 m of homes. Using the data set gathered by Savitz et al. in the Denver, Colorado, area of the United States, we determined which of the wiring attributes that contribute to Wertheimer‐Leeper coding areactuallyassociated with lowpower magnetic fields measured in bedrooms of subjects. The results led us to propose a considerably simplified three‐category form of the Wertheimer‐Leeper code that 1) drops the distinctions between thick and thin primary wires and between first‐span and other secondary lines, 2) adds a new distinction between open (i.e., conductors not in physical contact) and spun secondaries, and 3) explains as much of the between‐home variability in log‐transformed bedroom fields as does the five categories of the original Wertheimer‐Leeper code. The data necessary to classify residences using the modified code are considerably simpler to obtain and should lead to more reliable results. A separate reanalysis of the Denver data set of Savitz et al. shows that the modified code yields risk estimates that are both precise and markedly elevated for the highest exposure category, suggesting that this code may be useful in other studies. © 1994 W

ISSN:0197-8462    

DOI:10.1002/bem.2250150402

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

年代:1994

数据来源: WILEY

摘要:

AbstractEscherichia coliJM83 {F−ara Δ(lac‐proAB)rpsL[ϕ80dΔ(lacZ)M15]} in midlog growth phase at 30 °C were exposed to 60 Hz sinusoidal magnetic field of 3 mT of nonuniform diverging flux, inducing a nonuniform electric field with a maximum intensity of 32 μV/cm using an inductor coil. Exposed and unexposed control cells were maintained at 30.8 ± 0.1 °C and 30.5 ± 0.1 °C, respectively. Quadruplicate samples of exposed and unexposedE. colicells were simultaneously radiolabeled with35S‐L‐methionine at 10 min intervals over 2 hr. Radiochemical incorporation into proteins was analyzed via liquid scintillation counting and by denaturing 12.5% polyacrylamide gel electrophoresis. The results showed thatE. coliexposed to a 60 Hz magnetic field of 3 mT exhibited no qualitative or quantitative changes in protein synthesis compared to unexposed cells. Thus small prokaryotic cells (less than 2 μm × 0.5 μm) under constant‐temperature conditions do not alter their protein synthesis following exposure to 60 Hz magnetic fields at levels at 3 mT.

ISSN:0197-8462    

DOI:10.1002/bem.2250150403

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

年代:1994

数据来源: WILEY

摘要:

AbstractOur recent studies have shown a significant increase in the frequency of chromosomal aberrations in human amniotic cells after exposure to a sinusoidal 50 Hz, 30 μT (rms) magnetic field. To evaluate further interactions between chromosomes and electromagnetic fields, we have analyzed the effects of intermittent exposure. Amniotic cells were exposed for 72 h to a 50 Hz, 30 μT (rms) magnetic field in a 15 s on and 15 s off fashion. Eight experiments with cells from different fetuses were performed. The results show a 4% mean frequency of aberrations among exposed cells compared to 2% in sham‐exposed cells. The difference is statistically significant, withP<0.05 both excluding and including gaps. In another series of eight experiments, the cells were exposed in the same way but with the field on for 2 s and off for 20 s. Also in these experiments a similar increase in the frequency of chromosomal aberrations was seen, but only when the analysis included gaps. Continuous exposure for 72 h to 300 μT, 50 Hz, did not increase the frequency of chromosomal aberrations. The background electromagnetic fields at different locations within the two incubators used was carefully checked and was nowhere found to exceed 120 nT. Likewise, the background level of chromosomal aberrations in cells cultured at different locations in the incubators showed no significant interculture differences. © 1994 Wiley‐Li

ISSN:0197-8462    

DOI:10.1002/bem.2250150404

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe influence of 2.45 GHz microwave exposure (6 mW/g) on the diffusion processes in enzyme‐loaded unilamellar liposomes as bioreactors was studied. The enzyme carbonic anhydrase (CA) was entrapped into cationic unilamellar vesicles. Previous kinetic experiments showed a very low self‐diffusion rate of the substrate p‐nitrophenyl acetate (PNPA) across intact liposome bilayer. A twofold increase in the diffusion rate of PNPA through the lipid bilayer was observed after 120 min of microwave radiation compared to temperature control samples. The microwave effect was time dependent. The enzyme activity, as a function of increased diffusion of PNPA, rises over 120 min from 22.3% to 80%. The increase in stearylamine concentration reduces the enzyme activity from 80% to 65% at 120 min. No enzyme leakage was observed. © 1994 Wiley‐L

ISSN:0197-8462    

DOI:10.1002/bem.2250150405

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

年代:1994

数据来源: WILEY

摘要:

AbstractChemical and bacterial synthesis of a thermochemiluminescent polymer known as diazoluminomelanin (DALM) has been previously reported. This paper focuses on the intracellular synthesis of aminomelanin (AM) in mammalian cell lines and subsequent DALM synthesis from this core molecule. B16 melanoma cells, HL‐60 myeloid leukemia cells, and RAW 264.7 macrophages show AM and DALM production. Macroscopic image analysis of HL‐60 cell lysates containing DALM using the Quantitative Luminescence Imaging System (QLIS) showed increased chemiluminescence (CL) with increased microwave power input and increased temperature. This work represents a first step toward the goal of microscopic radiofrequency dosimetry of individual DALM‐loaded cells using image analysis. © 1994 Wiley‐L

ISSN:0197-8462    

DOI:10.1002/bem.2250150406

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn its integrated form, SV‐40 DNA offers an opportunity to observe the behavior of what is in effect a viral genome within a cellular genome, with transcriptional and translational products that can be clearly distinguished from those of the host cell. Exposure of SV40‐transformed human fibroblasts to a 60 Hz continuous‐wave sinusoidal electromagnetic (EM) field resulted in increased levels of virally derived mRNA and protein of large T‐antigen. These findings provide evidence that a foreign DNA integrated into cells can be affected by EM fields under conditions known to cause increased transcripts from endogenous cellular genes. © 1994 Wiley

ISSN:0197-8462    

DOI:10.1002/bem.2250150407

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe development of a wire code protocol based on a study of electrical installations in Melbourne, Australia, is described. Because of very significant differences between the Melbourne power distribution system and that used in Denver, Colorado, an approach different from that used by Wertheimer and Leeper was required. A combined practical and theoretical approach was used to determine a continuous exposure index, defined as a measure of the potential for exposure due to external electrical installations. The protocol was tested on a convenient sample of 41 homes in which the field was monitored over a 12 hour overnight period. A correlation of 0.85 (95% CI 0.74–0.92,P<.0001) was obtained between the measured time‐weighted average and the wire coding exposure index. To assess the efficacy of the wiring configuration index, a computer simulation of a case‐control study was then performed. It was concluded that, using the same basic reasoning of the Wertheimer and Leeper code, it is possible to develop a location‐specific code that provides a good correlation with the residential time‐weighted average and an acceptable degree of exposure misclassification. © 1994 Wiley

ISSN:0197-8462    

DOI:10.1002/bem.2250150408

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

年代:1994

数据来源: WILEY

摘要:

AbstractPregnant CD1 mice were exposed or sham‐exposed from day 0 to day 17 of gestation to a 50 Hz sinusoidal magnetic field at 20 mT (rms). Preimplantation and postimplantation survival were assessed and fetuses examined for the presence of gross external, internal, and skeletal abnormalities. There were no statistically significant field‐dependent effects on preimplantation or postimplantation survival, sex ratio, or the incidence of fetuses with internal or skeletal abnormalities. Magnetic field exposure was, however, associated with longer and heavier fetuses at term, with fewer external abnormalities. The results lend no support to suggestions of increased rates of spontaneous abortion or congenital malformation following prenatal exposure to power frequency magnetic fields. © 1994 Wiley‐Lis

ISSN:0197-8462    

DOI:10.1002/bem.2250150409

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

年代:1994

数据来源: WILEY

摘要:

AbstractTo investigate the potential of magnetic fields to act as a behavioral teratogen, pregnant CD1 mice were exposed or sham‐exposed for all of gestation to a 50 Hz/20 mT magnetic field. Maturation of offspring was assessed using a range of standard developmental indices (eye opening, pinna detachment, hair coat, tooth eruption, sexual maturity, and weight) and simple reflexive behaviors (air righting, surface righting, forepaw grasp, cliff avoidance, and negative geotaxis). Activity and coordination levels were explored in juvenile and adult mice using an open field arena, a head‐dip board, an accelerating Rotarod, and a residential activity wheel. All assessments were carried out without knowledge of exposure condition. Results from 168 sham‐exposed mice from 21 litters and from 184 exposed mice from 23 litters were compared using survival analysis techniques and multivariate regression methods. Three possible field‐dependent effects were found: Exposed animals performed the air righting reflex earlier (P<0.01); exposed males (but not females) were significantly lighter in weight (P= 0.008) at 30 days of age; and exposed animals remained on a Rota‐rod for less time as juveniles (P= 0.03). Some of these results have not been reported in other studies and may reflect spurious statistical significance, although some effect of magnetic field exposure cannot be ruled out. Overall, these results suggest that prenatal exposure to a 50 Hz magnetic field does not engender any gross impairments in the postnatal development or behavior of mice. This does not preclude such exposure affecting more subtle aspects of behavior. Published 1994 by Wiley

ISSN:0197-8462    

DOI:10.1002/bem.2250150410

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

年代:1994

数据来源: WILEY

ISSN:0197-8462    

DOI:10.1002/bem.2250150401

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

年代:1994

数据来源: WILEY