共查询到20条相似文献,搜索用时 31 毫秒
1.
Sal'nikova LE Chumachenko AG Vesnina IN Lapteva NSh Kuznetsova GI Abilev SK Rubanovich AV 《Radiatsionnaia biologiia, radioecologiia / Rossi?skaia akademiia nauk》2010,50(6):656-662
For 99 healthy volunteers, the frequencies of spontaneous and y-induced (1 Gy in vitro) chromosome aberrations in blood lymphocytes were compared with the results of PCR-genotyping by 8 repair genes: XRCC1, XPD, ERCC1, APEXI, RAD23B, OGG1, ATM, Tp53 (in all, 10 polymorphic sites). The frequency of spontaneous aberrations of chromosome type increased additively with the number of copies of minor allele of excision repair gene XPD variant *2251G and *862A D (p = 0.025). The frequency of gamma-induced chromosome aberrations proved to be elevated for the carriers of a minor allele OGG1*977G (p = 0.011). The significantly elevated number of gamma-induced chromosome aberrations was also observed for the carriers of major alleles XRCC1*G1996 and XRCC1*C589 (p = 0.002). 相似文献
2.
3.
4.
Electromagnetic acceleration of electron transfer reactions 总被引:3,自引:0,他引:3
The Moving Charge Interaction (MCI) model proposes that low frequency electromagnetic (EM) fields affect biochemical reactions through interaction with moving electrons. Thus, EM field activation of genes, and the synthesis of stress proteins, are initiated through EM field interaction with moving electrons in DNA. This idea is supported by studies showing that EM fields increase electron transfer rates in cytochrome oxidase. Also, in studies of the Na,K-ATPase reaction, estimates of the speed of the charges accelerated by EM fields suggest that they too are electrons. To demonstrate EM field effects on electron transfer in a simpler system, we have studied the classic oscillating Belousov--Zhabotinski (BZ) reaction. Under conditions where the BZ reaction oscillates at about 0.03 cycles/sec, a 60 Hz, 28 microT (280 mG) field accelerates the overall reaction. As observed in earlier studies, an increase in temperature accelerates the reaction and decreases the effect of EM fields on electron transfer. In all three reactions studied, EM fields accelerate electron transfer, and appear to compete with the intrinsic chemical forces driving the reactions. The MCI model provides a reasonable explanation of these observations. 相似文献
5.
Kerr LN Boivin WS Boyd SM Coletta JN 《Biomedical instrumentation & technology / Association for the Advancement of Medical Instrumentation》2001,35(2):104-109
An energy-efficient lighting retrofit at the Food and Drug Administration (FDA) Winchester Engineering and Analytical Center (WEAC) presented the opportunity to measure the electromagnetic (EM) environments in several rooms before and after changing the fluorescent lighting systems and to compare the changes in EM fields with the proposed standard EM immunity levels. Three rooms, representing the types of work areas in the laboratory, were selected and measured before and after the lighting changeover. Electric and magnetic field measurements were taken in the extremely low frequency (ELF), very low frequency (VLF), and radio frequency (RF) ranges of the EM spectrum. In 2 rooms, ELF electric fields were reduced and VLF and RF electric fields were increased as a result of the changeover to high-frequency fixtures. A third room received low-frequency, energy-efficient fixtures during this changeover, and this change resulted in only a slight increase of the ELF electric fields. The ELF magnetic fields were greatly reduced in 2 but only slightly reduced in the third room. No significant change was seen in VLF or RF magnetic fields for any of these rooms. Some field-strength measurements exceeded the proposed immunity levels recommended in the draft International Electrotechnical Commission standard IEC 60601-1-2 (rev. 2). The data show that increasing the separation distance from the fluorescent light fixtures greatly reduces the field-strength levels, limiting the potential for EM interference. 相似文献
6.
Insights into electromagnetic interaction mechanisms 总被引:10,自引:0,他引:10
7.
Sine waves enhance cellular transcription 总被引:1,自引:0,他引:1
8.
Questions of safety of electromagnetic (EM) fields should be based on relevant biological properties, i.e., specific cellular reactions to potentially harmful stimuli. The stress response is a well documented protective reaction of plant and animal cells to a variety of environmental threats, and it is stimulated by both extremely low frequency (ELF) and radio frequency (RF) EM fields. It involves activation of DNA to initiate synthesis of stress proteins. Thermal and non-thermal stimuli affect different segments of DNA and utilize different biochemical pathways. However, both ELF and RF stimulate the same non-thermal pathway. Since the same biochemical reactions are stimulated in different frequency ranges with very different specific absorption rates (SARs), SAR level is not a valid basis for safety standards. Studies of EM field interactions with DNA and with model systems provide insight into a plausible mechanism that can be effective in ELF and RF ranges. 相似文献
9.
Yurekli AI Ozkan M Kalkan T Saybasili H Tuncel H Atukeren P Gumustas K Seker S 《Electromagnetic biology and medicine》2006,25(3):177-188
The ever increasing use of cellular phones and the increasing number of associated base stations are becoming a widespread source of nonionizing electromagnetic radiation. Some biological effects are likely to occur even at low-level EM fields. In this study, a gigahertz transverse electromagnetic (GTEM) cell was used as an exposure environment for plane wave conditions of far-field free space EM field propagation at the GSM base transceiver station (BTS) frequency of 945 MHz, and effects on oxidative stress in rats were investigated. When EM fields at a power density of 3.67 W/m2 (specific absorption rate = 11.3 mW/kg), which is well below current exposure limits, were applied, MDA (malondialdehyde) level was found to increase and GSH (reduced glutathione) concentration was found to decrease significantly (p < 0.0001). Additionally, there was a less significant (p = 0.0190) increase in SOD (superoxide dismutase) activity under EM exposure. 相似文献
10.
During the last decade, use of radio frequency (RF) applications like mobile phones and other wireless devices, has increased remarkably. This has triggered numerous studies related to possible health risks due to the exposure of RF electromagnetic (EM) fields. One safety aspect is the coupling of EM fields with active and passive implants in the human body. While interactions with active implants have been quite extensively researched, only a few studies have focused on passive implants. The present article reviews interaction mechanisms and studies of passive metallic, that is, conductive, implants in common external RF EM fields. It is found that implants have been mostly studied numerically, and experimental studies are rare. Furthermore, the studies cover mostly far-field conditions and only a few have studied implants in near fields. A summary of results indicates that a conductive object in tissues may cause notable local enhancement of the EM field and thus enhanced power absorption. The degree of enhancement depends, for example, on the orientation, the dimensions, the shape, and the location of the implant. However, in most of the cases, the field enhancement has not been strong enough to cause remarkable excess heating (more than 1 degrees C) of tissues. 相似文献
11.
12.
Regulating genes with electromagnetic response elements 总被引:6,自引:0,他引:6
A 900 base pair segment of the c-myc promoter, containing eight nCTCTn sequences, is required for the induction of c-myc expression by electromagnetic (EM) fields. Similarly, a 70 bp region of the HSP70 promoter, containing three nCTCTn sequences, is required for the induction of HSP70 expression by EM fields. Removal of the 900 base pair segment of the c-myc promoter eliminates the ability of EM fields to induce c-myc expression. Similarly, removal of the 70 bp region of the HSP70 promoter, with its three nCTCTn sequences, eliminates the response to EM fields. The nCTCTn sequences apparently act as electromagnetic field response elements (EMRE). To test if introducing EMREs imparts the ability to respond to applied EM fields, the 900 bp segment of the c-myc promoter (containing eight EMREs) was placed upstream of CAT or luciferase reporter constructs that were otherwise unresponsive to EM fields. EMREs-reporter constructs were transfected into HeLa cells and exposed to 8 microT 60 Hz fields. Protein extracts from EM field-exposed transfectants had significant increases in activity of both CAT and luciferase, compared with identical transfectants that were sham-exposed. Transfectants with CAT or luciferase constructs lacking EMREs remained unresponsive to EM fields, i.e., there was no increase in either CAT or luciferase activity. These data support the idea that EMREs can be used as switches to regulate exogenously introduced genes in gene therapy. 相似文献
13.
Experiments were conducted to see whether the cellular response to electromagnetic (EM) fields occurs through a detection process involving temporal sensing. L929 cells were exposed to 60 Hz magnetic fields and the enhancement of ornithine decarboxylase (ODC) activity was measured to determine cellular response to the field. In one set of experiments, the field was turned alternately off and on at intervals of 0.1 to 50 s. For these experiments, field coherence was maintained by eliminating the insertion of random time intervals upon switching. Intervals ≥ 1 s produced no enhancement of ODC activity, but fields switched at intervals ≥ 10 s showed ODC activities that were enhanced by a factor of approximately 1.7. These data indicate that it is the interval over which field parameters (e.g., amplitude or frequency) remain constant, rather than the interval over which the field is coherent, that is critical to cellular response to an EMF. In a second set of experiments, designed to determine how long it would take for cells to detect a change in field parameters, the field was interrupted for brief intervals (25–200 ms) once each second throughout exposure. In this situation, the extent of EMF-induced ODC activity depended upon the duration of the interruption. Interruptions ≥ 100 ms were detected by the cell as shown by elimination of field-induced enhancement of ODC. That two time constants (0.1 and 10 s) are involved in cellular EMF detection is consistent with the temporal sensing process associated with bacterial chemotaxis. By analogy with bacterial temporal sensing, cells would continuously sample and average an EM field over intervals of about 0.1 s (the “averaging” time), storing the averaged value in memory. The cell would compare the stored value with the current average, and respond to the EM field only when field parameters remain constant over intervals of approximately 10 s (the “memory” time). Bioelectromagnetics 18:388–395, 1997. © 1997 Wiley-Liss, Inc. 相似文献
14.
Carmody S Wu XL Lin H Blank M Skopicki H Goodman R 《Journal of cellular biochemistry》2000,79(3):453-459
A unique approach to clinical application of cytoprotection is offered by electromagnetic (EM) field induction of stress proteins. EM fields are noninvasive and easily applied, as compared with the current hyperthermia protocols. Fertilized dipteran eggs and cultured rodent cardiomyocytes (H9c2 cells) were used as models to test EM fields for their ability to induce increased hsp70 levels for effective cytoprotection. Eggs preconditioned with an 8 microT 60Hz EM field for 30 min had 114% increase in hsp70 levels, and an average 82% increase in survival, following a lethal temperature of 36.5 degrees C. Thermal preconditioning at 32 degrees C was not nearly as effective in dipteran eggs, inducing only a 44% increase in survival. Preconditioning of cultured murine cardiomyocytes (H9c2 cells) with an 8 microT 60 Hz field induced a 77% average increase in hsp70 levels. 相似文献
15.
16.
Zhuravel' DV Boreĭko AV 《Radiatsionnaia biologiia, radioecologiia / Rossi?skaia akademiia nauk》2002,42(6):636-638
The regularities of gamma-induced excision of transposon Tn10 in different rec-strains of E. coli cells after gamma-irradiation have been studied. The survival of cells and relative frequency of the Tn10 elimination as a function of the 137Cs gamma-radiation doses were investigated. RecN and recA-mutants of E. coli were used for study of the role of rec-genes in the gamma-induced transposon excision. It was shown that the induced excision in the recN mutant was reduced. The transposon excision in the recA mutant was not revealed. The obtained results let to conclude that recA, and recN genes are involved not only in DNA repair processes but also in the gamma-induced transposon excision in bacteria. 相似文献
17.
Dividing human peripheral lymphocytes from 10 normal adults (5 males and 5 females) as well as lymphoid cell lines from patients with the chromosomal instability syndromes were exposed to low-level 60-Hz sinusoidal electromagnetic fields (EMF). The current density of the electrical field was 30 microA/cm2 while the strength of the magnetic field was either 1 or 2 gauss. The cytological endpoints measured included the frequency of sister-chromatid exchanges per chromosome; the distribution of first-, second-, and third-division cells and chromosome breakage (lymphoblastoid cells only). No statistically significant differences, indicative of EMF effects were observed between the treated and control cells regarding SCE frequency, cell cycle progression or chromosome breakage. 相似文献
18.
19.
ERK1/2 phosphorylation, induced by electromagnetic fields, diminishes during neoplastic transformation 总被引:2,自引:0,他引:2
It has been suggested that electromagnetic (EM) fields can act as co-promoters during neoplastic transformation. To examine this possibility, we studied the effects of 0.8-, 8-, 80-, and 300-microT 60-Hz electromagnetic (EM) fields in INITC3H/10T1/2 mouse fibroblast cells. These cells are transformed carcinogenically by methylcholanthrene, but the neoplastic phenotype can be suppressed indefinitely by the presence of retinyl acetate (RAC) in the culture medium. The effects of EM field exposures were examined at three stages: (1) before initiation of transformation (i.e., RAC in the culture media); (2) early in the transformation process (4 days after withdrawal of RAC); and (3) at full of neoplastic transformation (10 days after withdrawal of RAC). EM field exposures induced significant increases in protein levels for hsp70 and c-Fos and in AP-1 binding activity. EM fields induced phosphorylation of MAPK/ERK1/2 before the onset of transformation, but these increases diminished during the transformation process. No phosphorylation in the other major extracellular stress pathway, SAPK/JNK, was detected in cells exposed to EM fields at any time before, during, or after neoplastic transformation. Human cells HL60, MCF7, and HTB124, exposed to EM fields, also showed MAPK/ERK1/2 phosphorylation. Cells treated with the phorbol ester, TPA, served as positive controls for AP-1 activation, c-Fos protein synthesis, and ERK1/2 phosphorylation. There was no indication that EM fields affected the rate of cell transformation or acted as a co-promoter, under the conditions of this study. 相似文献
20.
I. Nordenson K. Hansson Mild S. Nordström A. Sweins E. Birke 《Radiation and environmental biophysics》1984,23(3):191-201
Summary In vivo and in vitro studies of the clastogenic effects of power frequency electric fields and transient electric currents have been performed. For the in vivo investigation peripheral lymphocytes from twenty switchyard workers were screened for chromosome anomalies. The rates of chromatid and chromosome breaks were found to be significantly increased compared to the rates in 17 controls.Exposure of human peripheral lymphocytes, in vitro, to a 50-Hz current with 1 mA/cm2 current density did not induce any chromosome damage. Exposure to ten 3 µs-long spark discharge pulses with a peak field strength in the samples of 3.5 kV/cm, however, resulted in chromosome breaks at a frequency similar to that induced in lymphocytes in vitro by ionizing radiation at 0.75 Gy.The biological significance of chromosomal damage induced in somatic cells is discussed. 相似文献