Cell stress response to combined ionizing and non-ionizing radiation and magnetic fields: a review based on human buccal epithelium cells

Background: The investigation of the low doses of ionizing radiation is still a great importance for identification of the threshold of harmful effect and potential hormetic effect of low doses. Objectives: The purpose of investigation was to evaluate the stress response in human buccal epithelium cells induced by low intensive neutron radiation. Materials and Methods: The level of chromatin condensation in interphase nuclei was applied for assessment of the cell reaction to stress. Exfoliated human buccal epithelium cells were collected, placed in the 3.03 mM phosphate buffer solution (pH=7.0) with addition of 2.89 mM CaCl2 and exposed to neutron radiation from 2 Pu-Be sources IBN-17. The heterochromatin granule quantity (HGQ) assessments were done after orcein staining that had been immediately performed after cell exposure to neutron radiation in the dose range from 2.3 mSv to 146.0 mSv. Also the effect of fast neutron radiation in the dose of 11.4 mSv on human buccal epithelium cells was investigated in 1-64 min after exposure. The HGQ in every variant of experiment was assessed in 30 nuclei in 3 separate experiments. The mean HGQ and standard error of mean were assessed in every experiment. Results: Neutron radiation induced the increase of HGQ. Partially slowed neutrons have less influence on neutron-induced HGQ increase than only fast neutrons especially with 1 min delay after exposure. Fast neutrons induce heterochromatinization in cell samples irradiated with doses 4.6–36.5 mSv. Further increase of dose has led to return of HGQ to control levels. After cell exposure to fast neutron flow (11.4 mSv) the peaks of chromatin condensation were observed for time intervals 2–8 and 32–64 min after cell exposure to radiation. Conclusions: Qualitative characteristic of neutron radiation (slow/fast neutrons) influences the rate of cell stress response as revealed by chromatin condensation in cell nuclei. It was demonstrated that there is a threshold dose above which cells are able to develop stress response to neutron radiation. The dose-response dependence is non-monotonous and is of wave-like form. Described phenomena may be explained by the effect of hormesis.

Modulation of the biological effects produced by ionizing radiation (IR) using microwave and magnetic fields has important theoretical and practical applications. Response of human buccal epithelium cells to different physical agents (single and combined exposure to 0.5–5 Gy γ-radiation (60Co); microwaves with the frequency of 36.64 GHz and power densities of 0.1 and 1 W/m2, and static magnetic field with the intensity of 25 mT) has been investigated. The stress response of the cells was evaluated by counting heterochromatin granules quantity (HGQ) in the cell nuclei stained with orcein. Membrane permeability was assessed by the percentage of cells stained with indigocarmine (cells with damaged membrane). The increase of heterochromatin granules quantity (HGQ), i.e. chromatin condensation was detected at the doses of 2 Gy and higher. Changes in the cell membrane permeability to indigocarmine expressed the threshold effect. Membrane permeability reached the threshold at the doses of 2–3 Gy for the cells of different donors and did not change with the increase of the dose of γ-radiation. Cells obtained from different donors revealed some individual peculiarities in their reaction to γ-radiation. The static magnetic field and microwaves applied before or after γ-radiation decreased its impact, as revealed by means of HGQ assessment.

Doxorubicin is an anthracycline antibiotic which inhibits DNA and RNA synthesis intercalating DNA double helix and inducing free radicals. Doxorubicin is used in the treatment of cancer diseases. The influence of Doxorubicin on human buccal cell was used as a model for the assessment of toxic effects in vitro. We studied the possibility of using the process of heterochromatinization in cell nuclei in toxicological investigations of drugs in vitro. The exfoliated buccal epithelium cells of two donors (men) - Donor A (24 years) and Donor B (23 years) were used. Cells were subjected to Doxorubicin in concentration 0.2; 2; 20, and 200 µg/ml for 2 h. A significant increase of chromatin condensation in a dose-dependent way was shown. Doxorubicin induced chromatin condensation for cells of donors A and B if ≥ 0.2 µg/ml, and ≥ 2 µg/ml, correspondingly. Cell viability assessed by combined staining with Hoechst 33342 and ethidium bromide revealed a significant increase of damaged cells if ≥ 2 µg/ml. Indigo carmine staining also revealed a significant increase in permeability of cell membranes if ≥ 20 µg/ml. In cells of donor A the intranuclear calcium concentration increased if Doxorubicin concentration was ≥ 0.2 µg/ml. In cells of donor B cytoplasmic and intranuclear calcium concentration decreased if Doxorubicin concentration ≥ 0.2 µg/ml. The comparison revealed high sensitivity of the method of chromatin changes registration in human buccal epithelium cells as a method of assessment of drug toxicity in vitro, and this method may be recommended for toxicological investigations.

ObjectivesThis study evaluated the effects of non-ionizing electromagnetic radiation on rat thyroid function and histopathology. Forty female and thirty male Sprague-Dawley rats (200–220 g, 2 months old) were exposed to 2.45 GHz Wi-Fi, mobile jammer radiation, or a sham condition. In Group A, male rats were exposed to Wi-Fi or mobile jammers for 2 h daily for two weeks. The devices were located within a one-meter radius of the animal cage, either on or off. In the Sham group, the experimental setup was like the other groups, but the irradiating devices were turned off. Group B included non-pregnant females, pregnant (exposed and control subgroups), and their offspring. Thyroid hormones in the serum were measured, and the histology was microscopically analyzed, focusing on areas of colloid and epithelium in the thyroid follicles.ResultsCompared to the control group, T4 hormone levels were significantly different in male rats exposed to mobile jammer radiation (p-value = 0.037). In group B, significant differences were found solely in the male offspring regarding T3 levels due to jammer exposure (average = 109.00 for male offspring in the experiment vs. average = 65.50 for those in the control, p-value < 0.001). Additionally, histopathological findings indicated significant differences as well. These results highlight a potential link between exposure to electromagnetic radiation and changes in thyroid endocrine and histological parameters. Our findings suggest that ongoing assessment of existing safety guidelines on non-ionizing radiation exposure is necessary, especially concerning its effects on thyroid hormone levels and follicular histology.

Biological systems are complex, variable and to a great extent adaptive to environmental and occupational challenge such as ionising radiation, making the mathematical modelling of their behaviour a diYcult task. The required models need to be based on useful experimental data describing global eVects on a cellular, tissue and organ level. High-throughput technologies such as proteomics have been shown to be powerful tools on many areas of modern biology. In radiation biology, especially facing the question of possible adverse health eVects following exposures to low doses of ionising and non-ionising radiation, new and sensitive approaches are slowly gaining support. Epidemiological studies suggest that doses of ionising radiation much lower than previously assumed may cause adverse eVects on human health. However, the epidemio

An increase of the negative charge of human nuclei has been revealed under conditions of the extremely-high frequency (EHF) irradiation during which the effect mentioned is greatly expressed for circular (right) polarization. At present, the universally adapted point of view explaining the mechanisms of SHF and EHF electromagnetic wave influence on live organisms has not been formed yet, though the trustworthiness of biological effects within the indicated bands is beyond any doubt. Research on the polarization characteristics of SHF and EHF influence on bio-objects at the cell level are of great interest. It is possible to suppose that the frequency and energetic properties of cell response will depend on electromagnetic field polarization characteristics (linear, right or left hand circular polarization). In experiments, SHF- and EHF-sources of electromagnetic radiation have been applied with the following parameters: the SHF-source had /spl lambda/ = 1.6 cm, output power P = 14 mW, power flow density - 700 /spl mu/W/cm/sup 2/, exposure time - 4 minutes. The EHF irradiation source (generator /spl Gamma/4 - 141) was fitted with a device for automatic frequency scanning over the range from 37 to 53 GHz (power flow density = 10 mW/cm/sup 2/, exposure time 20 seconds). Devices to obtain linear, right and left hand polarizations were used in both sources. Buccall epithelium cells were used as the object of the research. The cells were placed into the solution: 3.03 mM phosphate buffer, pH = 7.0, with addition of 2.89 mM CaCl/sub 2/. The effect of SHF and EHF fields of linear and circular (right and left) polarization was investigated. The influence criteria adopted was the electrophoretic mobility of the cells, i.e. the quantity of electronegative cell nuclei (ENN index, in percent) shifted in the electromagnetic field of a special camera with current 100 /spl mu/A and field voltage - 15 V/cm. Counting of ENN was carried out within 5 min. and 1 hour after irradiation. It was evident from the investigation that the SHF irradiation of all polarization types unchanged ENN index (in January-February). Under EHF irradiation condition (July - September) the of ENN index was maximized on 26.0% compared to control (36%). This process did not depend on the type of, polarization. In the experiments carried out late in February - March, when an organism is weakened and ENN index in control is low (32%) compared to standard norm, the EHF irradiation initiated also an index increase as for control, however, in this case at right polarization the increase was 25.3% and it was a maximal one. This tendency remained after 1 hour irradiation. The results obtained witness of the increase of cell ENN index under EHF irradiation and no changes under SHF irradiation. The data obtained witness of more expressed stimulating effect of EHF cell irradiation at right hand polarization. The effect is not stable and depends on the initial value of the ENN index.

Hippocampus, as an important organization of the nervous system, has a close relationship with the biology function of learning, memory and spatial cognition. It is very important to clarify the specific influence of non-ionizing radiation on the hippocampus. This paper summarized briefly the effects of nonionzing radiation on hippocampus and relevant research method. Key words: Nonionzing radiation; Hippocampus; Effects; Research method

On age-related changes of cell membrane permeability in human buccal epithelium cells

Background: Nowadays, the growing use of non-ionizing electromagnetic radiation has raised concerns about its potential health effects. Objective: In this work, an animal model exposed to Wi-Fi and jammer signals was used to examine the effects of non-ionizing electromagnetic radiation on kidney and liver function.Material and Methods:In this experimental study, twenty-one male Wistar Albino rats were separated into three groups: Wi-Fi, jammer, and sham groups. The animals were exposed to electromagnetic radiation for two hours per day for two weeks. Blood samples and kidney and liver tissues were collected and analyzed for various biochemical parameters.Results: The findings of this study showed a mild inflammatory response in both tissues after exposure to the fields. However, no notable or serious alterations were noted in the groups under study. The Wi-Fi and jammer signals had no significant impact on creatinine, albumin, blood urea nitrogen, cholesterol, high-density lipoprotein, triglycerides, albumin/globulin ratio, total bilirubin, direct bilirubin, and alkaline phosphatase levels. However, the jammer group revealed a notable decline in low-density lipoprotein compared to the sham group. Significant differences were observed in the levels of aspartate aminotransferase and alanine aminotransferase between the Wi-Fi and sham groups but not between the other groups. Conclusion: This work emphasizes the importance of considering individual organ characteristics in response to electromagnetic radiation exposure. Prolonged or closer exposure to the radiation source may significantly affect the organ function.

Exposure to sub-lethal doses of ionising and non-ionising electromagnetic radiation can impact human health and well-being as a consequence of, for example, the side effects of radiotherapy (therapeutic X-ray exposure) and accelerated skin ageing (chronic exposure to ultraviolet radiation: UVR). Whilst attention has focused primarily on the interaction of electromagnetic radiation with cells and cellular components, radiation-induced damage to long-lived extracellular matrix (ECM) proteins has the potential to profoundly affect tissue structure, composition and function. This review focuses on the current understanding of the biological effects of ionising and non-ionising radiation on the ECM of breast stroma and skin dermis, respectively. Although there is some experimental evidence for radiation-induced damage to ECM proteins, compared with the well-characterised impact of radiation exposure on cell biology, the structural, functional, and ultimately clinical consequences of ECM irradiation remain poorly defined.

Background. It is a point of discussion whether low-dose ionizing radiation has harmful or stimulating impact on cell. According to high relative biological effectiveness of neutron radiation there is a need of description of any process triggered in the cell by neutrons. Objective. The aim of current work is the investigation of the low dosed neutron radiation effects on human cells by indicators of cell stress such as state of chromatin and cell membrane permeability. Materials and methods. Human buccal epithelium cells from 3 male donors (21, 24, 25 years old) were exposed to fast neutron radiation in dose range 2.3–146.0 mSv from 239Pu-Be source. State of chromatin was evaluated by count of heterochromatin granules quantity in 100 nuclei stained with 2% orcein in 45% acetic acid; ratio of cells with increased membrane permeability stained with 5 mM indigocarmine in 300 cells. Results. Changes in level of heterochromatin granules quantity and in cell membrane permeability revealed wave-shaped dependency with maximum effects at 36.5 mSv. Further increase of dose resulted in return of both chromatin state and membrane permeability levels closely to control or even lower. Conclusion. Membrane restoration and chromatin decompaction under doses higher than 36.5 mSv together can be a sign of hormetic (stimulating) effect of low-dose neutron radiation.

Protection of live-line personnel against the possibly harmful effects of non-ionizing radiation — such as extra-low frequency electric and magnetic fields — is one of the keys of safe working. Limits of these fields are defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Exposures above limits may endanger the safety of the workers, so are not acceptable during any kind of live-line activity. Although magnetic fields have similar — even more dangerous — health-related risks than electric fields, these are usually not taken into account at all during the preparation and the execution of any live-line work. In the High Voltage Laboratory of Budapest University of Technology and Economics calculations, simulations and measurements were executed to inspect the critical exposures. Results have shown that in some cases induced current density in the human body may reach the limits, so protective actions are required to increase the safety of this method. Based on the results, an expert system can be developed to handle magnetic field-related risks before — even continuously during — any live-line activity. By the application of these improvements, exposures can always be kept under the limits during any kind of work. This paper not only focuses on the theoretical background of the analysis — the possible practical implementation is also introduced.

Body composition assessment (BCA) represents a valid instrument to evaluate nutritional status through the quantification of lean and fat tissue, in healthy subjects and sick patients. According to the clinical indication, body composition (BC) can be assessed by different modalities. To better analyze radiation risks for patients involved, BCA procedures can be divided into two main groups: the first based on the use of ionizing radiation (IR), involving dual energy X-ray absorptiometry (DXA) and computed tomography (CT), and others based on non-ionizing radiation (NIR) [magnetic resonance imaging (MRI)]. Ultrasound (US) techniques using mechanical waves represent a separate group. The purpose of our study was to analyze publications about IR and NIR effects in order to make physicians aware about the risks for patients undergoing medical procedures to assess BCA providing to guide them towards choosing the most suitable method. To this end we reported the biological effects of IR and NIR and their associated risks, with a special regard to the excess risk of death from radio-induced cancer. Furthermore, we reported and compared doses obtained from different IR techniques, giving practical indications on the optimization process. We also summarized current recommendations and limits for techniques employing NIR and US. The authors conclude that IR imaging procedures carry relatively small individual risks that are usually justified by the medical need of patients, especially when the optimization principle is applied. As regards NIR imaging procedures, a few studies have been conducted on interactions between electromagnetic fields involved in MR exam and biological tissue. To date, no clear link exists between MRI or associated magnetic and pulsed radio frequency (RF) fields and subsequent health risks, whereas acute effects such as tissue burns and phosphenes are well-known; as regards the DNA damage and the capability of NIR to break chemical bonds, they are not yet robustly demonstrated. MRI is thus considered to be very safe for BCA as well US procedures.

The influence of electromagnetic fields of wavelengths of 7.1 mm and 1.6 cm on human buccal epithelium cells was investigated. The low-level irradiation (200 /spl mu/W/cm/sup 2/) of cell samples induced an increase in cell membrane permeability and the decrease in electronegativity of cell nuclei.

The ability of M-protein-positive (M+) and M-protein-negative (M−) strains (including an M− mutant lacking the structural gene for M-protein) ofStreptococcus pyogenes to attach to human pharyngeal, buccal, and tongue epithelial cells was compared. We observed that M+ strains ofS. pyogenes attached in significantly higher numbers to human pharyngeal epithelial cells than to human buccal or tongue cells. M− strains did not exhibit high-level binding to any type of epithelial cell. Also, the adhesion of an M+ and an M− strain ofS. pyogenes was low to all types of rat epithelial cells tested. The apparent differences in the surface components between human pharyngeal and buccal epithelial cells were confirmed by studies utilizing radiolabeled lectins.Ulex europaeus lectin with a specificity for fucosyl residues, andTriticum vulgaris lectin with a specificity for N-acetyl glucosamine and N-acetyl neuraminic acid residues, bound in higher amounts to human pharyngeal cells than to buccal cells. Pretreatment of pharyngeal epithelial cells with microgram quantities of highly purified type 6 M-protein or miligram quantities of lipoteichoic acid (LTA) derived fromS. pyogenes decreased the subsequent attachment of the organism. However, the binding specificities of3H-LTA were different from those of intact streptococci;3H-LTA bound comparably to human pharyngeal, buccal, and tongue epithelial cells, and it bound in higher quantities to rat epithelial cells. Also, although the adsorption ofS. pyogenes cells to pharyngeal cells was inhibited by the presence of fucose and galactose, these sugars had little effect on the binding of3H-LTA to epithelial cells. In contrast, the high adhesion of M+ strains but not M− mutants to pharyngeal cells suggested that M-protein may play an important role. This possibility was supported by the observation that3H-labeled purified type 6 M-protein bound in higher concentrations to human pharyngeal epithelial cells than to human buccal cells. Furthermore, human pharyngeal epithelial cells were estimated to contain larger numbers of binding sites for M-protein than buccal cells, whereas the affinity of M-protein was similar to both cell types. These adsorption parameters are similar to those previously established for intact streptococcal cells.