Effect of extremely low frequency electromagnetic fields on bacterial membrane

Purpose: The effect of extremely low frequency electromagnetic fields (ELF-EMF) on bacteria has attracted attention due to its potential for beneficial uses. This research aimed to determine the effect of ELF-EMF on bacterial membrane namely the membrane potential, surface potential, hydrophobicity, respiratory activity and growth.

Materials and methods: Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were subjected to ELF-EMF, 50?Hz, 1?mT for 2?h. Membrane potential was determined by fluorescence spectroscopy with or without EDTA (Ethylenediaminetetraacetic acid) with DisC3(5) (3,3-dipropylthiacarbocyanine iodide), zeta potential measurements were performed by electrophoretic mobility, hydrophobicity of the membrane was measured with MATH (Microbial Adhesion to Hydrocarbons) test, respiratory activity was determined with CTC (5-Cyano-2,3-ditolyl tetrazolium chloride), colony forming unit (CFU) and DAPI (4′,6-diamidino-2-phenylindole, dihydrochloride) was used for growth determinations.

Results: ELF-EMF caused changes in physicochemical properties of both Gram-positive and Gram-negative bacteria. Hyperpolarization was seen in S. aureus and EDTA-treated E. coli. Surface potential showed a positive shift in S. aureus contrariwise to the negative shift seen in EDTA-untreated E. coli. Respiratory activity increased in both bacteria. A slight decrease in growth was observed.

Conclusion: These results show that ELF-EMF affects the crucial physicochemical processes in both Gram-positive and Gram-negative bacteria which need further research.     

Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria

Purpose: To determine the effect of extremely low frequency (<300 Hz) electromagnetic fields (ELF-EMF) on the growth rate of Gram-positive and Gram-negative bacteria and to determine any morphological changes that might have been caused by ELF-EMF. Materials and methods: Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application.

Results: A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides.

Conclusion: This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.     

Coupling of oxidative stress responses to tricarboxylic acid cycle and prostaglandin E2 alterations in Caenorhabditis elegans under extremely low-frequency electromagnetic field

Purpose: With all-pervasive presence of extremely low-frequency electromagnetic field (ELF-EMF) in modern life, ELF-EMF has been regarded as an essential factor which may induce changes in many organisms. The objective of the present study was to investigate the physiological responses of Caenorhabditis elegans (C. elegans) to 50?Hz, 3?mT ELF-EMF exposure.

Materials and methods: Worms were exposed to ELF-EMF from the egg stage until reaching the fourth larva (L4) stage. After exposure, expressions of the tricarboxylic acid (TCA) cycle enzymes were examined by qRT-PCR and western blot analysis. Two lipid metabolites were detected by GC-MS. Reactive oxygen species (ROS) level was detected by dichlorofluorescein staining and worm antioxidant system was investigated by enzymatic activity analysis, including detection of the superoxide dismutase and catalase (CAT) activity and the total antioxidant capacity (T-AOC).

Results: The TCA cycle enzyme, fumarase was found with decreased expression under ELF-EMF exposure. And arachidonic acid (ArA) and prostaglandin E₂(PGE₂) showed elevated concentrations, with increased expression of prostaglandin E₂ synthase (PGES-2) in ELF-EMF exposed worms. Significant elevation of ROS level was identified accompanied with the significant depression of T-AOC in response to ELF-EMF.

Conclusions: Our results suggested that exposure to 50?Hz, 3?mT ELF-EMF in C. elegans can elicit disruptions of the TCA cycle metabolism and PGE₂ formation, coupling ELF-EMF-induced oxidative stress responses. Our study probably will attract increasing attentions to the controllable application of ELF-EMF associated with health and disease.     

Effects of acute electromagnetic field exposure and movement restraint on antioxidant system in liver,heart, kidney and plasma of Wistar rats: A preliminary report

Purpose:?The aim of the present study was to evaluate the early effects of acute (2?h) exposure to extremely low frequency electromagnetic fields (ELF-EMF), as well as movement restraint (MR) and the combination of both on the antioxidant systems in the plasma, liver, kidney, and heart of rats.

Materials and methods:?Twenty-four adult male Wistar rats were divided in two groups, restrained and unrestrained. The restrained animals were confined into an acrylic tube for 120?min. Half of the animals of each group were exposed to ELF-EMF (60?Hz, 2.4?mT) during the period of restriction. Immediately after treatment, reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and thiobarbituric acid reactive substances (TBARS) were measured in tissues.

Results:?GSH concentration was significantly lower in the heart of all experimental animals when compared to the control group; furthermore, the decrease was higher in the liver of restrained animals. SOD activity was lower in the plasma of restrained and EMF exposed animals compared to unrestrained rats. There were no significant differences in CAT activity and TBARS levels among all the experimental groups vs. the control group.

Conclusion:?Two hours of 60?Hz EMF exposure might immediately alter the metabolism of free radicals, decreasing SOD activity in plasma and GSH content in heart and kidney, but does not induce immediate lipid peroxidation. Oxidative stress induced by movement restraint was stronger than that produced by EMF.     

Genetic damage in mammalian somatic cells exposed to extremely low frequency electro-magnetic fields: A meta-analysis of data from 87 publications (1990–2007)

Purpose: A meta-analysis was conducted to obtain a ‘quantitative’ estimate of the extent of genetic damage in mammalian somatic cells exposed to non-ionizing radiation emitted from extremely low frequency electro-magnetic fields (ELF-EMF) and to compare with that in unexposed control cells.

Methods: The methods used for the meta-analysis were recommended in several standard text books. Three specific variables related to ELF-EMF exposure characteristics were examined in the meta-analysis: (i) frequency (Hz), (ii) flux density (mT), and (iii) in occupationally exposed individuals.

Result and conclusions: (1) The difference between ELF-EMF-exposed and control cells as well as the ‘effect size’ due to ELF-EMF exposure were biologically small (although statistically significant) with very few exceptions. (2) At certain ELF-EMF exposure conditions there was a statistically significant increase in genetic damage assessed from some end-points. (3) The mean indices for chromosomal aberrations and micronuclei end-points in ELF-EMF-exposed and control cells were within the spontaneous levels reported in historical database. (4) Considerable evidence for publication bias was found in the meta-analysis.     

Effect of X-ray irradiation on expression of organic anion transporting polypeptides

Abstract

Purpose: Some members of the organic anion transporting polypeptide (OATP) family may play critical roles in determining the concentration of anticancer drugs in targeted organs/cells. The purpose of the present study was to investigate whether radiation can alter the expression of OATP in cancer cells so that OATP can be used as a specific drug target for anti-tumor treatment in combination with radiotherapy.

Materials and methods: Two cancer cell lines (HepG2 and MCF7) were irradiated with three doses of X-ray and the expression levels of six OATP were assessed.

Results: Expressions of several OATP were altered after irradiation. OATP1A2, an OATP that was found to transport anti-tumor drugs and was undetectable in untreated cells, showed dramatically elevated level of expression after irradiation in MCF7 cells. The combined treatment of X-rays and the OATP1A2 substrate methotrexate exerted a more significant effect on growth rate and cell death compared with radiation or methotrexate treatment alone. At certain time points, X-rays increased OATP1A2 level while suppressing the expression of efflux transporters.

Conclusions: Radiation may simultaneously increase the expression of uptake transporters and decrease the level of efflux transporters, suggesting OATP may be considered a novel target for delivery of anti-neoplastic agents in combination with radiotherapy.     

极低频磁场联合X线对人肝癌细胞株BEL-7402作用的机制研究

目的 研究极低频磁场联合X线对人肝癌细胞株BEL-7402的作用机制。方法 人肝癌细胞株BEL-7402经0、2、4、6、8、10 Gy X线照射后,用极低频磁场处理(100 Hz、0.7 mT、30 min、3 d)后,利用扫描电镜作形态观察,流式细胞仪、基因芯片研究细胞凋亡机制。结果 扫描电镜形态显示,极低频磁场联合X线组肝癌细胞株BEL-7402发生凋亡改变。流式细胞仪观察结果显示,当X线剂量是2、4、6、8、10 Gy, 极低频磁场联合X线凋亡率为10.0%、14.5%、4.3%、5.1%、7.1%,X线组凋亡率是0.1%、8.10%、0.1%、0.4%、 2.2% (P<0.05)。基因芯片结果显示,极低频磁场联合X线组共有1465条出现上调,1108条出现下调。其中比值≥2倍的基因共有336条,上调262条,下调74条。与凋亡相关基因共110条,上调基因71条,下调基因39条。涉及CDC25、CHK1、ATM、p38、PTEN、p53、G₁/S、Fas、G₂/M、Cell Cycle、Apoptosis、Caspase基因通路中的基因。极低频磁场加X线组差异表达结果中有13条同时出现在极低频磁场组。42条同时出现在X线组。结论 极低频磁场与X线通过不同的基因通路影响细胞凋亡。极低频磁场与X线对人肝癌细胞株BEL-7402凋亡有协同作用。     

Changes in mitochondrial functioning with electromagnetic radiation of ultra high frequency as revealed by electron paramagnetic resonance methods

Abstract

Purpose: To study the effects of electromagnetic radiation (EMR) of ultra high frequency (UHF) in the doses equivalent to the maximal permitted energy load for the staffs of the radar stations on the biochemical processes that occur in the cell organelles.

Materials and methods: Liver, cardiac and aorta tissues from the male rats exposed to non-thermal UHF EMR in pulsed and continuous modes were studied during 28 days after the irradiation by the electron paramagnetic resonance (EPR) methods including a spin trapping of superoxide radicals.

Results: The qualitative and quantitative disturbances in electron transport chain (ETC) of mitochondria are registered. A formation of the iron-nitrosyl complexes of nitric oxide (NO) radicals with the iron-sulphide (FeS) proteins, the decreased activity of FeS-protein N2 of NADH-ubiquinone oxidoreductase complex and flavo-ubisemiquinone growth combined with the increased rates of superoxide production are obtained.

Conclusions: (i) Abnormalities in the mitochondrial ETC of liver and aorta cells are more pronounced for animals radiated in a pulsed mode; (ii) the alterations in the functioning of the mitochondrial ETC cause increase of superoxide radicals generation rate in all samples, formation of cellular hypoxia, and intensification of the oxide-initiated metabolic changes; and (iii) electron paramagnetic resonance methods could be used to track the qualitative and quantitative changes in the mitochondrial ETC caused by the UHF EMR.     

Electromagnetic field-induced converse cell growth during a long-term observation

Abstract

Purpose: Professional and public concern about the potential adverse effects of man-made electromagnetic fields (EMF) on the human body has dramatically expanded in recent years. Despite numerous attempts to investigate this issue, the long-standing challenge of reproducibility surrounding alternating EMF effects on human health remains unresolved. Our chief aim was to investigate a plausible mechanism for this phenomenon.

Materials and methods: Growth of cultured human cancer cells, DU145 and Jurkat, exposed to power frequency magnetic field (MF) (60 Hz, 1 mT) for 3 days, was determined using a 2-(4-Iodophenyl)- 3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) assay and a trypan blue exclusion assay. This experiment was repeated at incubators long-term monitoring period up to 5.3 years. A periodogram analysis was performed to investigate periodic patterns in the MF and sham effects on cell growth.

Results: Unlike conventional assumptions, the MF effect on growth in both cell types was promotive or suppressive in a period-dependent manner. The converse cell growth induced by the MF was consistent in incubators, with little variation.

Conclusions: Spatiotemporal evidence suggests that the period-dependent converse cell growth by the MF may contribute to the poor reproducibility and explain the adverse effects observed in previous experimental and epidemiological investigations. Additionally, the novel approach of this study may be applied to design features required to experimentally determine the effects of EMF on living organisms in a convincing manner.     

Dcr3 inhibit p53-dependent apoptosis in γ-irradiated lung cancer cells

Purpose:?To identify genes responsible for the radiosensitivity, we investigated the role of the differential gene expression profiles by comparing radioresistant H1299 with radiosensitive H460 lung cancer cell lines.

Materials and methods:?mRNA profiles of lung cancer cell lines were assessed using microarray, and subsequent validation was performed with qRT-PCR (Quantitative real time-polymerase chain reaction). The expression levels of differentially expressed genes were determined by Western blot and the radioresistance of lung cancer cell lines was measured by clonogenic assay.

Results:?From the differentially expressed apoptosis-related genes between H1299 and H460, we found Dcr3 (Decoy receptor 3, also known as TNFRSF6B; Tumour necrosis factor receptor super family member 6B) expression was significantly (P?=?4.38 × 10^?7) higher in H1299 cells than H460 cells. Moreover, the Dcr3 mRNA expression level in the radioresistant cell lines (H1299, A549, DLD1, MB231, MB157) was increased in comparison to the radiosensitive cell lines (ME180, Caski, U87MG, MCF7, H460). Overexpression of Dcr3 increased the survival rate of radiosensitive H460, MCF7, and U87MG cells, and knockdown of Dcr3 abolished the radioresistance of A549 cells. The survival rate of p53 (Tumour protein 53)-deficient H1299 after gamma-irradiation was not affected by the suppression of Dcr3 expression. However, when we introduced p53 into H1299 cells, siDcr3 (siRNA of Dcr3) suppressed the radioresistance of H1299 cells by inducing p53-dependent Fas (Fas receptor, also known as TNFRSF6; Tumour necrosis factor receptor super family member 6)-mediated apoptosis pathway.

Conclusion:?Characterisation of gene expression profiles in two lung cancer cell lines revealed that Dcr3 expression and p53-dependent apoptosis signalling pathway regulate cellular response to ionising radiation.     

Altered mitochondrial function and genome frequency post exposure to γ-radiation and bystander factors

Purpose:?To further evaluate irregular mitochondrial function and mitochondrial genome damage induced by direct γ-irradiation and bystander factors in human keratinocyte (HPV-G) epithelial cells and hamster ovarian fibroblast (CHO-K1) cells. This is as a follow-up to our recent reports of γ-irradiation-induced loss of mitochondrial function and mitochondrial DNA (mtDNA) damage.

Materials and methods:?Mitochondrial function was evaluated post direct radiation and irradiated cell conditioned medium (ICCM) by determining: Activity of the individual complexes of oxidative phosphorylation (OxPhos); mtDNA-encoded protein synthesis; and mitochondrial genome frequency and mtDNA damage.

Results:?Mitochondria show a loss of OxPhos enzyme function as early as 4?h post treatment with recovery observed 12–96?h in some but not all complexes demonstrating a non-uniform sensitivity to γ-radiation. We also identified irregular mtDNA-directed protein synthesis. Long range Polymerase Chain Reaction (PCR) analysis identified mitochondrial genome damage and real-time PCR identified increases in mitochondrial genome frequency.

Conclusions:?The study reaffirms the sensitive nature of mitochondria to both low-level direct radiation exposure and radiation-induced bystander factor mediated damage. Furthermore, we report for the first time, the loss of function in the enzymes of OxPhos post exposure to bystander factors and identify altered mtDNA-directed protein synthesis post both direct radiation and bystander factors.     

Dominant negative Ubiquitin-conjugating enzyme E2C sensitizes cervical cancer cells to radiation

Abstract

Purpose: To find the radiation sensitivity of human cervical carcinoma cell lines and to investigate the effect of the dominant negative-Ubiquitin-conjugating enzyme E2C (DN-UBE2C) on cell proliferation and radiation response.

Materials and methods: Radiation sensitivities of human cervical cell lines (SiHa, HeLa, BU25TK, ME 180, and C33A) were analyzed by assessing their cell survival after irradiation by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Soft agar cloning assay, growth curve and radiation response of DN-UBE2C stably transfected SiHa and HeLa cell lines were assessed by MTS assay and Clonogenic assay.

Results: Difference in sensitivity to radiation was observed among the cervical cancer cell lines studied. SiHa was found to be the most resistant cell line whereas C33A cells were the most sensitive. The growth rate of SiHa and HeLa transfected with DN-UBE2C was significantly reduced compared to vector control. Furthermore, DN-UBE2C-mediated radiosensitivity was correlated with a significant decrease in resistance to radiation by SiHa and HeLa cells after transfection with the DN-UBE2C when compared to control cultures.

Conclusion: These results suggested that the Ubiquitin-conjugating enzyme E2C (UBE2C) gene is a potential therapeutic target for cervical cancer treatment.     

Mitophagy and mitochondrial morphology in human melanoma-derived cells post exposure to simulated sunlight

Purpose:?To assess changes in mitochondrial morphology and mitophagy induced by simulated sunlight irradiation (SSI) and how these changes are modulated by mitochondrial activity and energy source.

Materials and methods:?Human malignant amelanotic melanoma A375 cells were pre-treated with either a mitochondrial activity enhancer, uncoupler or were either melanin or glutamine supplemented/starved for 4 hours pre-exposure to sunlight. A Q-Sun Solar Simulator (Q-Lab, Homestead, FL, USA) was employed to expose cells to simulated sunlight. Confocal microscopy imaging of A375 cells co-loaded with mitochondria and lysosome-specific fluorescent dyes was used to identify these organelles and predict mitophagic events.

Results:?SSI induces pronounced changes in mitochondrial dynamics and mitophagy in exposed skin cells compared to control and these effects were modified by both glutamine and melanin.

Conclusions:?Mitochondrial dynamics and rate of mitophagy in melanoma cells are sensitive to even short bursts of environmentally relevant SSI. Mitochondrial dynamics, and its modulation, may also play a role in mitophagy regulation, cell survival and proliferation post SSI.     

Exploring the radiosensitizing potential of magnetotherapy: a pilot study in breast cancer cells

Abstract

Aim: To explore the influence of electromagnetic fields (EMFs) on the cell cycle progression of MDA-MB-231 and MCF-7 breast cancer cell lines and to evaluate the radiosensitizing effect of magnetotherapy during therapeutic co-exposure to EMFs and radiotherapy.

Material and methods: Cells were exposed to EMFs (25, 50 and 100?Hz; 8 and 10?mT). In the co-treatment, cells were first exposed to EMFs (50?Hz/10?mT) for 30?min and then to ionizing radiation (IR) (2?Gy) 4?h later. Cell cycle progression and free radical production were evaluated by flow cytometry, while radiosensitivity was explored by colony formation assay.

Results: Generalized G1-phase arrest was found in both cell lines several hours after EMF exposure. Interestingly, a marked G1-phase delay was observed at 4?h after exposure to 50?Hz/10?mT EMFs. No cell cycle perturbation was observed after repeated exposure to EMFs. IR-derived ROS production was enhanced in EMF-exposed MCF-7 cells at 24?h post-exposure. EMF-exposed cells were more radiosensitive in comparison to sham-exposed cells.

Conclusions: These results highlight the potential benefits of concomitant treatment with magnetotherapy before radiotherapy sessions to enhance the effectiveness of breast cancer therapy. Further studies are warranted to identify the subset(s) of patients who would benefit from this multimodal treatment.     

Growth of injected melanoma cells is suppressed by whole body exposure to specific spatial-temporal configurations of weak intensity magnetic fields

Purpose:?To measure the effect of exposure to a specific spatial-temporal, hysiologically-patterned electromagnetic field presented using different geometric configurations on the growth of experimental tumours in mice.

Methods:?C57b male mice were inoculated subcutaneously with B16-BL6 melanoma cells in two blocks of experiments separated by six months (to control for the effects of geomagnetic field). The mice were exposed to the same time-varying electromagnetic field nightly for 3?h in one of six spatial configurations or two control conditions and tumour growth assessed.

Results:?Mice exposed to the field that was rotated through the three spatial dimensions and through all three planes every 2 sec did not grow tumours after 38 days. However, the mice in the sham-field and reference controls showed massive tumours after 38 days. Tumour growth was also affected by the intensity of the field, with mice exposed to a weak intensity field (1–5 nT) forming smaller tumours than mice exposed to sham or stronger, high intensity (2–5?μT) fields. Immunochemistry of tumours from those mice exposed to the different intensity fields suggested that alterations in leukocyte infiltration or vascularisation could contribute to the differences in tumour growth.

Conclusions:?Exposure to specific spatial-temporal regulated electromagnetic field configurations had potent effects on the growth of experimental tumours in mice.     

The expression and intranuclear distribution of nucleolin in HL-60 and K-562 cells after repeated,short-term exposition to rotating magnetic fields

Purpose: The aim of the study was to analyze the influence of rotating magnetic fields (RMF) on the expression and intranuclear distribution of nucleolin, protein involved in ribosome biosynthesis, in HL-60 (acute promyelocytic leukemia) and K-562 (chronic myelogenous leukemia) established human cell lines.

Materials and methods: Cells were exposed to RMF for two chosen states of the magnetic field induction: B = 10 mT and B = 20 mT in experimental set-up for 30 min with 24-h intervals for four days. Cytospin slides were prepared and expression of nucleolin was detected using monoclonal antibodies. Parameters of fluorescence related to nucleolin were measured in at least 2000 tumor cells in each slide by a laser scanning cytometer with an argon laser. Percentages of cells in different phases of cell cycle were also analyzed.

Results: The repeated exposition of cells to RMF caused significant increase in nucleolin expression in the whole nucleus and in the nucleolin aggregates (NUA). The redistribution of nucleolin measured by changes in number of NUA was also observed. The exposition of both cell lines studied to RMF did not alter the cell cycle.

Conclusion: The nucleolin is responsive to RMF in HL-60 and K-562. The increase of its expression may indicate a reaction of cells to RMF and it may influence their other biological properties.     

Different responses of Drosophila subobscura isofemale lines to extremely low frequency magnetic field (50 Hz, 0.5 mT): fitness components and locomotor activity

Purpose: Extremely low frequency (ELF) magnetic fields as essential ecological factors may induce specific responses in genetically different lines. The object of this study was to investigate the impact of the ELF magnetic field on fitness components and locomotor activity of five Drosophila subobscura isofemale (IF) lines.

Materials and methods: Each D. subobscura IF line, arbitrarily named: B16/1, B24/4, B39/1, B57/2 and B69/5, was maintained in five full-sib inbreeding generations. Their genetic structures were defined based on the mitochondrial DNA variability. Egg-first instar larvae and 1-day-old flies were exposed to an ELF magnetic field (50?Hz, 0.5?mT, 48?h) and thereafter, fitness components and locomotor activity of males and females in an open field test were observed for each selected IF line, respectively.

Results: Exposure of egg-first instar larvae to an ELF magnetic field shortened developmental time, and did not affect the viability and sex ratio of D. subobscura IF lines. Exposure of 1-day-old males and females IF lines B16/1 and B24/4 to an ELF magnetic field significantly decreased their locomotor activity and this effect lasted longer in females than males.

Conclusions: These results indicate various responses of D. subobscura IF lines to the applied ELF magnetic field depending on their genetic background.     

The influence of differently polarised microwave radiation on chromatin in human cells

Purpose: To determine the possible biological effects of differently polarised microwave radiation on the chromatin state in human cells.

Materials and methods: Isolated human buccal epithelium cells were irradiated by microwaves of frequency f = 35 GHz and surface power density E = 30 μW/cm². The state of chromatin in human cells was determined by methods of light and electron microscopy. The state of cell membranes was evaluated by the method of vital indigo carmine staining.

Results: The microwave-induced condensation of chromatin in human cells is revealed. Degree of microwave-induced condensation depends on the state of polarisation of electromagnetic wave: In some cases left circularly polarised waves induce less effect than linearly polarised radiation. The linearly polarised electromagnetic waves induce cell membrane damage revealed by increase of cell staining. The data obtained are discussed in connection with mechanisms of biological effects of electromagnetic fields.

Conclusion: The data obtained in this work demonstrate important biological effects of monochromatic microwave irradiation at 35 GHz. Low-level microwave irradiation induces chromatin condensation in human cells and damages of cell membranes.