bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rat liver foci study on coexposure with 50 Hz magnetic fields and known carcinogens
Authors: Rannug Agneta , Holmberg Bo , Ekström Tomas , Mild Kjell Hansson 
Published: February 2006

AbstractA study was performed to investigate possible interactions by magnetic fields (MF) with the processes of initiation and promotion of chemically induced preneoplastic lesions in rat liver. Male Sprague‐Dawley rats were subjected to a 70% partial hepatectomy followed after 24 h by i.p. injection of diethylnitrosamine (DENA) as a tumour initiator. Starting one week after the DENA‐treatment phenobarbital (PB) was given to promote growth of enzymatically altered foci of liver cells. MF was applied immediately after the partial hepatectomy and continued until sacrifice after 12 weeks of PB exposure. Homogenous horizontal AC magnetic fields with a frequency of 50 Hz and flux densities of 0.5 μT or 0.5 mT were used. The rats coexposed with MF and DENA plus PB did not gain weight as much as the rats exposed to the chemical agents only. The MF‐exposure also resulted in a slight reduction in size and numbers of the focal lesions. The results suggest an interaction of MF with the processes of chemical carcinogenesis either as a result of stress or depending on effects on the proliferation of preneoplastic cells. © 1993 Wiley‐Liss, Inc.
Determination of the induced ELF electric field distribution in a two layer in vitro system simulating biological cells in nutrient solution
Authors: Wang W. , Litovitz T. A. , Penafiel L. M. , Meister R. 
Published: February 2006

AbstractIn‐vitro studies of biological effects of electromagnetic fields are often conducted with cultured cells either in suspension or grown in a monolayer. In the former case, the exposed medium can be assumed to be homogeneous; however, eventually the cells settle to the bottom of the container forming a two layer system with different dielectric and conductive properties. In the present work the effect of this separation on the electric field distribution is calculated and experimentally measured at selected positions for a commonly used exposure configuration. The settled cell suspension is modeled by a well‐defined two layer system placed in a rectangular container with the base of the container parallel to the direction of the magnetic field. Theoretical calculations based on numerical techniques are done for various two layer systems with different conductivities in each layer. The agreement between the theoretical calculations and the experimental measurements is within ± 1.5 mV/m, or 10% of the maximum induced field when the conductivity of the lower layer is ten times that of the upper layer. This result is well within experimental error. When the thickness of one of the layers is small compared to the thickness of the other layer, it is found that the electric field distribution is essentially that of the homogeneous case. The latter situation corresponds to a typical cell exposure condition. © 1993 Wiley‐Liss, Inc.
Inter‐beat intervals of cardiac‐cell aggregates during exposure to 2.45 GHz CW, pulsed, and square‐wave‐modulated microwaves
Authors: Seaman Ronald L. , Dehaan Robert L. 
Published: February 2006

AbstractInter‐beat intervals of aggregated cardiac cells from chicken embryos were studied during 190 s exposures to 2.45 GHz microwaves in an open‐ended coaxial device. Averaged specific‐absorption rates (SARs) and modulation conditions were 1.2–86.9 W/kg continuous‐wave (CW). 1.2–12.2 W/kg pulse modulation (PW, duty cycle ∽ 11%). and 12.0–43.5 W/kg square‐wave modulation (duty cycle = 50%). The inter‐beat interval decreased during microwave exposures at 42.0 W/kg and higher when CW or square‐wave modulation was used, which is consistent with established effects of elevated temperatures. However, increases in the inter‐beat interval during CW exposures at 1.2–12.2 W/kg, and decreases in the inter‐beat interval after PW exposures at 8.4–12.2 W/kg. are not consistent with simple thermal effects. Analysis of variance indicated that SAR. modulation, and the modulation‐SAR interaction were all significant factors in altering the interbeat interval. The latter two factors indicated that the cardiac cells were affected by athermal as well as thermal effects of microwave exposure. © 1993 Wiley‐Liss. Inc.
2D plasmon excitation and nonthermal effects of microwaves on biological membranes
Authors: Fisun O. I. 
Published: February 2006

AbstractThere are several experimental reports that have demonstrated a remarkable increase in conduction of ions along the interface between water and a polar‐lipid monolayer as contrasted with that in a bulk‐water phase. A simple model was developed for the collective ionic modes of a charged spherical membrane that takes the increase into account. Starting from the hydrodynamic equations for surface ions inside and outside a cell, the dispersion relation for intrinsic cellular electrical oscillations was obtained. Properties were calculated for surface‐plasmon modes as well as for a resonant response of a charged membrane bilayer to microwave pumping. © 1993 Wiley‐Liss, Inc.
The effect of moving air on detection of a 60‐Hz electric field
Authors: Stell Mark , Sheppard Asher R. , Adey W. Ross 
Published: February 2006

AbstractTwo potential mechanisms in detection of a 60‐Hz electric field by albino rats were examined: field‐induced movement of the vibrissae and field‐induced vibration of the skin. Specifically, the experiment tested field detection in a moving stream of air designed to mask field‐induced movement of the skin, fur, and vibrissae. Rats were trained to detect electric fields and were then tested at field intensities from 0–25 kV/m rms. As previously reported, rats demonstrate unmistakable behavioral evidence of field detection at all intensities above 7.5 kV/m. After establishing detection in still air, field detection was re‐examined in moving air (average air velocity approximately 2.8–6.8 m/s). The primary result is that the wind produced no change in detection at field intensities above threshold (> 7.5 kV/m). Indeed, at these intensities detection was virtually identical in still and moving air. A secondary finding is that moving air produced statistically significant (P < .05) but apparently contradictory effects on detection when the field intensity was below threshold. On no‐field trials the wind lowered scores (i.e., fewer presses on the field‐off lever); however, on subthreshold field trials, the wind actually increased detection scores (i.e., more presses on the field‐on lever). While this no‐field and subthreshold field result is interesting and deserves further study, we place primary emphasis on the finding that, if the field was detectable in still air, it was also detectable in moving air. This result leads us to believe that movement of the vibrissae, fur, or skin is not likely to be the main mechanism of electric‐field detection in our subjects. © 1993 Wiley‐Liss. Inc.
Effects of exposure to a circularly polarized 50‐Hz magnetic field on plasma and pineal melatonin levels in rats
Authors: Kato Masamichi , Honma Ken‐Ichi , Shigemitsu Tsukasa , Shiga Yoichi 
Published: February 2006

AbstractWe sought to determine whether a 6‐week exposure to a 50‐Hz rotating magnetic field influences melatonin synthesis by 11–18 week‐old Wistar‐King male rats. Rats were exposed continuously to a rotating magnetic field at 1, 5, 50, or 250 μT (spatial vector rms) for 6 weeks, except for twice‐weekly breaks of about 2 h for cleaning of cages and feeding. The rats were housed in exposure and sham‐exposure facilities, which were located in the same room, under a 12:12 light‐dark photoperiod (lights on at 06:00 h). The room was constantly illuminated by 4 small, dim red lights (< 0.07 lux in dark period). Levels of plasma and pineal gland melatonin were determined by radioimmunoassay. A significant decrease of melatonin was observed between the control group and groups exposed to a magnetic field at a flux density in excess of l μT during the night time, but no statistical differences were found among the exposed groups. These results indicate that subchronic exposure of albino rats to a 50‐Hz rotating magnetic field influences melatonin production and secretion by the pineal gland. © 1993 Wiley‐Liss, Inc.
50‐Hz magnetic field exposure system for small animals
Authors: Shigemitsu Tsukasa , Takeshita Kazuma , Shiga Yoichi , Kato Masamichi 
Published: February 2006

AbstractThe design, construction, and results of evaluation of an animal‐exposure system for the study of biological effects of extremely low frequency (ELF) magnetic fields are described. The system uses a square coil arrangement based on a modification of the Helmholtz coil. Due to the cubic configuration of this exposure system, horizontal and vertical magnetic fields as high as 0.3 mT can be generated. Circularly polarized magnetic fields can also be generated by changing the current and phase difference between two sets of coils. Tests were made for uniformity of the magnetic field, stray fields, sham‐exposure ratio of stray field, changes of temperature and humidity, light intensity and distribution inside the animal‐housing space, and noise due to air‐conditioning equipment. Variation of the magnetic field was less than 2% inside the animal housing. The stray‐field level inside the sham‐exposure system is less than 2% of experimental exposure levels. The system can be used for simultaneous exposure of 48 rats (2 to a cage) or 96 mice (4 to a cage). © 1993 Wiley‐Liss. Inc.
Repeatability of measurements of residential magnetic fields and wire codes
Authors: Dovan Thanh , Kaune William T. , Savitz David A. 
Published: February 2006

AbstractSeveral epidemiological studies have been based on wire codes (i.e., categories of electrical wiring configurations near residences) or on in‐home spot measurements of magnetic flux density (MFD) as surrogates for short‐ and long‐term exposure of children and adults to residential magnetic fields. We used wire code and MFD measurements that were made in 81 Colorado homes in 1985 and again in 1990 to assess their repeatability over periods of 0–24 h and 5 years. These homes, a subset of those lived in by subjects from the case‐control study of Savitz et al. [Am J Epidemiol 128:21–38, 1988]. were divided into four approximately equally sized groups that were differentiated by wire code and by case‐control status. Eight homes were assigned wire codes in 1990 that differed from the 1985 coding of Savitz and colleagues [1988]; of these, seven were coded as highcurrent configuration (HCC) and one as low‐current configuration (LCC) in 1985. Overall, 37 homes were coded as HCC in 1990 compared with 38 homes in 1985. Coding differences were due to differing distance measurements (four homes), differing “thick” vs. “thin” categorization of primary‐distribution line‐conductor sizes (two homes), differing “first‐span” vs. “second‐span” categorization of secondary wires (one home), and physical changes in proximate electrical wiring (one home). Coefficients of correlation between MFD spot measurements that were separated in time by 0–24 h range between 0.70 and 0.90. The coefficient between spot measurements made in 1985 and then again in 1990 is 0.70. These coefficients are similar for HCC and LCC homes and do not depend on whether residential appliances were turned on or off. The data show (at least for the portion of Colorado studied) that residential wire code and, more surprisingly, spot MFD measurements, are fairly reliable over 0–24‐h and 5‐year periods. © 1993 Wiley‐Liss, Inc.
Use of a spreadsheet program to calculate the electric field/current density distributions induced in irregularly shaped, inhomogeneous biological structures by low‐frequency magnetic fields
Authors: Hart Francis X. , Evely Kimberly , Finch Carla D. 
Published: February 2006

AbstractA commercially available spreadsheet program is used on a microcomputer to calculate the electric field/current density distributions induced in irregularly shaped, inhomogeneous objects by low‐frequency magnetic fields. A finite‐difference method is applied to an impedance grid that represents the object being modeled. This approach is validated by comparison with 1) the analytical results of an eccentric cylinder model and 2) measurements made on a square dish containing a saline solution and square, insulating inclusions. Application of the method is also made to a culture dish with a layer of sediment exposed to a horizontal magnetic field. © 1993 Wiley‐Liss, Inc.
Effects of pulsed magnetic fields on the developing mouse embryo
Authors: Frölen Hakon , Svedenstål Britt‐Marie , Paulsson Lars‐Erik 
Published: February 2006

AbstractThe influence of a pulsed magnetic field (PMF; sawtooth with 45‐μs linear rise time and 5‐μs decay time, peak strength of 15 μT, and frequency 20 pps) on the embryogenesis of CBA/S mice was investigated in five experiments based on a total of 707 exposed and 543 unexposed primigravidas. Sham and PMF exposures began on day 1 of gestation (experiments 1 and 2), on day 2 (experiment 3), on day 5 (experiment 4). and on day 7 (experiment 5): all exposures continued until day 19 post conception (p.c.) when they were terminated, at which time the following variables were measured: number of implants; number of placental resorptions; number of living fetuses; number of dead fetuses; number of malformations in living and dead fetuses; and length and body mass of living fetuses. Control dams were sham‐exposed concurrently with corresponding. PMF‐exposed dams. With the exception of experiment 5, in which exposure to PMF started on day 7 p.c., all groups of exposed mice had significantly more placental resorptions when compared with concurrent controls. The increased resorption rate was not reflected in a reduction in litter size or in the number of litters. A significant increase in malformed fetuses was not seen in any of the exposed groups, or when groups were pooled. Only in experiment 1 was the number of dead fetuses affected by exposure to PMF. The effect of PMF on the implantation rate was not significant. Body mass and length of exposed fetuses were significantly reduced only when the PMF treatment began on day 7 p.c. That PMF‐treated mice had significantly more placental resorptions when exposure began on day 5 p.c. or earlier (before implantation), but not when exposure began on day 7 (after implantation), may indicate a causative pre‐implantation effect. Because a PMF‐induced increase in the number of resorptions has not been observed in other strains of mice, the effect might be strain‐related. © 1993 Wiley‐Liss, Inc.
Effects of low‐frequency magnetic fields on fetal development in rats
Authors: Huuskonen Hannele , Juutilainen Jukka , Komulainen Hannu 
Published: February 2006

AbstractWe studied effects of alternating magnetic fields on the embryonic and fetal development of rats. Mated females of the Han:Wistar‐strain were sham exposed or exposed continuously to a 50‐Hz field or to a 20,000 pulse‐per‐second (pps) sawtooth magnetic field from day 0 to day 20 of pregnancy for 24 h/day until necropsied on day 20. The respective peak‐to‐peak intensities of the fields were 35.6 μT (sinewave) and 15.0 μT (sawtooth). Each treatment group contained 72 bred females. Control animals were kept under the same conditions without the magnetic field. No adverse effects were seen in the dams. The mean numbers of implantations and living fetuses per litter were statistically significantly increased in the 50‐Hz group. There were, however, three total resorptions of litters in dams of the control group, which contributed to the difference in the number of living fetuses. The corrected body‐mass gains (gains without uterine content) of dams were similar in all groups. Pregnancy rates, incidences of resorptions. late fetal deaths, and fetal body masses were similar in all groups. The incidence of fetuses with minor skeletal anomalies was statistically significantly increased in both exposed groups. Only one serious malformation (anophthalmia, sawtooth‐exposed group) and a few minor visceral malformations were found. In conclusion, the magnetic fields used in this study did not increase the incidence of major malformations or resorptions in Wistar rats. The increased number of skeletal anomalies and implantations we observed indicates, however, that some developmental effects in rats may attend exposure to time‐varying magnetic fields. © 1993 Wiley‐Liss. Inc.
Chicken embryo fibroblasts exposed to weak, time‐varying magnetic fields share cell proliferation, adenosine deaminase activity, and membrane characteristics of transformed cells
Authors: Parola Abraham H. , Porat Nurith , Kiesow Lutz A. 
Published: February 2006

AbstractChicken embryo fibroblasts (CEF) exposed to a sinusoidally varying magnetic field (SVMF) (100 Hz, 700 μT, for 24 h) showed a remarkable rise of segmental rotational relaxation rate of adenosine deaminase (ADA, EC 3.5.4.4) as determined by multifrequency phase fluorometry. Pyrene‐labeled, small subunit ADA was applied to cultured (normal) CEF, which have available and abundant ADA complexing protein (ADCP) on their plasma membranes. Sine‐wave‐modulated fluorometry of the pyrene yielded a profile of phase angle vs. modulation frequency. In SVMF‐treated cells and in Rous‐sarcoma‐virus (RSV) transformed cells the differential phase values at low modulation frequencies of the excitation are remarkably reduced. This effect is magnetic rather than thermal, because the temperature was carefully controlled and monitored; nevertheless to further check this matter we studied CEF, infected by the RSV‐Ts68 temperature‐sensitive mutant (36°C transformed, 41°C “revertant”). When grown at 36°C in the SVMF, cells did not show the slightest trend towards reversion, as would be expected had there been local heating. Concomitant with the increased segmental rotational relaxation rate of ADA, there was a decrease in fluorescence lifetime and a slight, yet significant, increase in membrane lipid “microfluidity.” These biophysical observations prompted us to examine the effect of SVMF on cell proliferation and ADA activity (a malignancy marker): higher rates of cell proliferation and reduced specific activity of ADA were observed. © 1993 Wiley‐Liss, Inc.
Early pregnancy loss and exposure to 50‐Hz magnetic fields
Authors: Juutilainen Jukka , Matilainen Pekka , Saarikoski Seppo , Läärä Esa , Suonio Sakari 
Published: February 2006

AbstractThe possibility of an association of early pregnancy loss (EPL) with residential exposure to ELF magnetic fields was investigated in a case‐control study. Eighty‐nine cases and 102 controls were obtained from the data of an earlier study aimed at investigating the occurrence of EPL in a group of women attempting to get pregnant. Magnetic‐field exposure was characterized by measurements in residences. Strong magnetic fields were measured more often in case than in control residences. In an analysis based on fields measured at the front door, a cutoff score of 0.5 A/m (0.63 μT) resulted in an odds ratio of 5.1 (95% confidence interval 1.0–25). The results should be interpreted cautiously due to the small number of highly exposed subjects and other limitations of the data. © 1993 Wiley‐Liss. Inc.
A 50‐Hz magnetic field induces structural and biophysical changes in membranes
Authors: Paradisi Silvia , Donelli Gianfranco , Santini Maria Teresa , Straface Elisabetta , Malorni Walter 
Published: February 2006

AbstractThe effects of a 50‐Hz extremely low frequency magnetic field on cultured K562 cells growing in suspension were studied by means of scanning electron microscopy and electron paramagnetic resonance spectroscopy. Exposure of K562 cells at 2.5 mT for periods to 96 hours induced significant changes in cell‐surface structure and physiology without modification of proliferative capability as indicated by quantitative analysis. Thus extremely low frequency fields seem able to induce injurious, sublethal cell alterations, and the plasma membrane seems to play an important role in this effect. © 1993 Wiley‐Liss, Inc.
Perturbations of plant leaflet rhythms caused by electromagnetic radio‐frequency radiation
Authors: Ellingsrud Svein , Johnsson Anders 
Published: February 2006

AbstractThe minute‐range up and down rhythms of the lateral leaflets of Desmodium gyrans has been studied when exposed to electromagnetic radiation in the radio‐frequency (RF) range. The RF radiation was applied as homogeneous 27.12 MHz fields in specially‐designed exposure cells(and in some cases as non‐homogeneous radiation of 27 MHz. amplitude modulated by 50 Hz, in front of commercial diathermy equipment). All fields were applied as pulses. We report effects in the leaflet rhythms such as temporary changes in the amplitude, period, and phase. The radiation could also cause temporary or complete cessations of the rhythms. The lowest dose (8 W/cm2) used was still effective. © 1993 Wiley‐Liss. Inc.
Behavioral effects of long‐term exposure to magnetic fields in rats
Authors: Trzeciak Henryk I. , Grzesik Jan , Bortel Maria , Kuśka Rafał , Duda Dorota , Michnik Jerzy , Małecki Andrzej 
Published: February 2006

AbstractMale rats and pregnant and nonpregnant female rats of the Wistar strain were sham‐exposed or exposed to static (0.49 T) or to extremely low frequency (50 Hz) magnetic fields (0.018 T) 2 h per day for 20 consecutive days. Measures of irritability, exploratory activity, and locomotion were made in that order before and after the 4th, 10th, and 17th 2‐h exposures. A reliable decrease in the irritability of rats after repeated exposure to a static or undulating field was found. No significant effects of treatment conditions on open‐field behavior and locomotor activity were observed. Pregnancy had no influence on the behavioral end points. These results indicate that irritability of rats may be used as a simple behavioral indicant of mammalian sensitivity to magnetic fields. © 1993 Wiley‐Liss. Inc.
Experimental search for combined AC and DC magnetic field effects on ion channels
Authors: Galt Sheila , Sandblom John , Hamnerius Yngve , Höjevik Per , Saalman Elisabeth , Nordén Bengt 
Published: February 2006

AbstractThe hypothesis that specific combinations of DC and low frequency AC magnetic fields at so‐called cyclotron‐resonance conditions could affect the transport of ions through ion channels, or alter the kinetics of ion channels (opening and closing rates), has been tested. As a model system, the ion channels formed by gramicidin A incorporated in lipid bilayer membranes were studied. No significant changes in channel conductance, average lifetime, or formation rate as a function of applied fields could be detected over a wide range of frequencies and field strengths. Experiments were carried out to measure the time‐resolved single‐channel events and the average conductances of many‐channel events in the presence of K+ and H+ ions. The channel blocking effect of Ca++ was also studied. © 1993 Wiley‐Liss. Inc.