Ornithine decarboxylase activity is affected in primary astrocytes but not in secondary cell lines exposed to 872 MHz RF radiation

Purpose: The effects of radiofrequency (RF) radiation on cellular ornithine decarboxylase (ODC) activity were studied in fibroblasts, two neural cell lines and primary astrocytes. Several exposure times and exposure levels were used, and the fields were either unmodulated or modulated according to the characteristics of the Global System for Mobile (GSM) communications.

Materials and methods: Murine L929 fibroblasts, rat C6 glioblastoma cells, human SH-SY5Y neuroblastoma cells, and rat primary astrocytes were exposed to RF radiation at 872 MHz in a waveguide exposure chamber equipped with water cooling. Cells were exposed for 2, 8, or 24 hours to continuous wave (CW) RF radiation or to a GSM type signal pulse modulated at 217 Hz, at specific absorption rates of 1.5, 2.5, or 6.0 W/kg. Cellular ODC activities of cell samples were assayed.

Results: ODC activity in rat primary astrocytes was decreased statistically significantly (p values from 0.003 to <0.001) and consistently in all experiments performed at two exposure levels (1.5 and 6.0 W/kg) and using GSM modulated or CW radiation. In the secondary cell lines, ODC activity was generally not affected.

Conclusions: ODC activity was affected by RF radiation in rat primary neural cells, but the secondary cells used in this study showed essentially no response to similar RF radiation. In contrast to some previous studies, no differences between the modulated and continuous wave signals were detected. Further studies with primary astrocytes are warranted to confirm the present findings and to explore the mechanisms of the effects.     

Aneuploidy studies in human cells exposed in vitro to GSM-900 MHz radiofrequency radiation using FISH

Purpose:?Since previous research found an increase in the rate of aneuploidies in human lymphocytes exposed to radiofrequencies, it seems important to perform further studies. The objective of this study was then to investigate whether the exposure to RF (radiofrequency) radiation similar to that emitted by mobile phones of a second generation standard, i.e., Global System for Mobile communication (GSM) may induce aneuploidy in cultured human cells.

Materials and methods:?The potential induction of genomic instability by GSM-900 MHz radiofrequency (GSM-900) was investigated after in vitro exposure of human amniotic cells for 24 h to average-specific absorption rates (SAR) of 0.25, 1, 2 and 4 W/kg in the temperature range of 36.3–39.7°C. The exposures were carried out in a wire-patch cell (WPC). The rate of aneuploidy of chromosomes 11 and 17 was determined by interphase FISH (Fluorescence In Situ Hybridisation) immediately after independent exposure of three different donors for 24 h. At least 100 interphase cells were analysed per assay.

Results:?No significant change in the rate of aneuploidy of chromosomes 11 and 17 was found following exposure to GSM-900 for 24 h at average SAR up to 4 W/kg.

Conclusion:?Our study did not show any in vitro aneuploidogenic effect of GSM using FISH and is not in agreement with the results of previous research.     

Proliferation and cytogenetic studies in human blood lymphocytes exposed in vitro to 2450 MHz radiofrequency radiation

Abstract. Aliquots of human peripheral blood collected from two healthy human volunteers were exposed in vitro to continuous wave 2450 MHz radiofrequency radiation (RFR), either continuously for a period of 90 min or intermittently for a total exposure period of 90 min (30 min on and 30 min off, repeated three times). Blood aliquots which were sham-exposed or exposed in vitro to 150 cGy gamma radiation served as controls. The continuous wave 2450 MHz RFR was generated with a net forward power of 34.5 W and transmitted from a standard gain rectangular antenna horn in a vertically downward direction. The mean power density at the position of the cells was 5.0 mW/cm 2. The mean specific absorption rate calculated by Finite Difference Time Domain analysis was 12.46 W/kg. Immediately after exposure, lymphocytes were cultured for 48 and 72 h to determine the incidence of chromosomal aberrations and micronuclei, respectively. Proliferation indices were also recorded. There were no significant differences between RFR-exposed and shamexposed lymphocytes with respect to; (a) mitotic indices; (b) incidence of cells showing chromosome damage; (c) exchange aberrations; (d) acentric fragments; (e) binucleate lymphocytes, and (f) micronuclei, for either the continuous or intermittent RFR exposures. In contrast, the response of positive control cells exposed to 150 cGy gamma radiation was significantly different from RFR-exposed and sham-exposed lymphocytes. Thus, there is no evidence for an effect on mitogen-stimulated proliferation kinetics or for excess genotoxicity within 72 h in human blood lymphocytes exposed in vitro to 2450 MHz RFR.     

Current physical activity is related to bone mineral density in males but not in females

The purpose of the present study was to investigate the association between high-, medium-, and low-impact physical activity in males and females at the time of peak bone mineral density in young adulthood. The cohort consisted of 62 male medical students (aged 28.1 +/- 3.9) and 62 female medical students (aged 25.1 +/- 3.9). The bone mineral density (aBMD, g/cm (2)) of the total body, femoral neck, and lumbar spine, and the bone mineral content (BMC, grams) and area (cm (2)) of the femoral neck and lumbar spine was measured using dual energy X-ray absorptiometry. Volumetric BMD (vBMD, mg/cm (3)) of the femoral neck and lumbar spine was estimated. The total amount of physical activity per week, which was recorded in a questionnaire, was divided into high-impact, medium-impact, and low-impact activity. In the male cohort, hours of high-impact physical activity per week was associated with aBMD and BMC of all sites (r=0.27 - 0.53, p<0.05) and bone area of the femoral neck (r=0.38, p<0.01). Total amount of physical activity per week was associated with aBMD of the total body and femoral neck, BMC of femoral neck and lumbar spine, femoral neck vBMD, and the lumbar spine area (p<0.05 for all). Using multiple linear regression, high-impact physical activity was independently associated with aBMD (beta=0.27, p<0.05) and BMC (beta=0.34, p<0.01) of the femoral neck. In the female cohort there was no association between amount or type of physical activity to aBMD, BMC, vBMD, or the bone area of any site. Instead body weight, lean body mass, or fat mass were significantly related to aBMD and all BMC sites in this group. The results of the present study suggest that present physical activity level has a stronger relation to different aspects of bone mass in the male compared to the female adult skeleton.     

Micronuclei in the peripheral blood and bone marrow cells of rats exposed to 2450 MHz radiofrequency radiation

Purpose : To determine the incidence of micronuclei in peripheral blood and bone marrow cells of rats exposed continuously for 24h to 2450 MHz continuous wave radiofrequency radiation (RFR) at an average whole-body specific absorption rate (SAR) of 12W/kg. Materials and methods : Eight adult male Sprague-Dawley rats were exposed to 2450 MHz RFR in circularly polarized waveguides. Eight sham-exposed rats were kept in similar waveguides without the transmission of RFR. Four rats were treated with mitomycin-C (MMC) and used as positive controls. All rats were necropsied 24h after the end of RFR and sham exposures, and after the 24h treatment with MMC. Peripheral blood and bone marrow smears were examined to determine the frequency of micronuclei (MN) in polychromatic erythrocytes (PCE). Results : The results indicated that the incidence of MN/2000 PCE were not significantly different between RFR- and sham-exposed rats. The group mean frequencies of MN in the peripheral blood were 2.3 ±0.7 in RFR-exposed rats and 2.1 ±0.6 in sham-exposed rats. In bone marrow cells, the average MN incidence was 3.8 ±1.0 in RFR-exposed rats and 3.4 ±0.7 in sham-exposed rats. The corresponding values in positive control rats treated with MMC were 23.5 ±4.7 in the peripheral blood and 33.8 ±7.4 in bone marrow cells. Conclusion : There was no evidence for the induction of MN in peripheral blood and bone marrow cells of rats exposed for 24h to 2450 MHz continuous wave RFR at a whole body average SAR of 12 W/kg.     

Induced antioxidant activity in hospital staff occupationally exposed to ionizing radiation

Abstract Purpose: Occupational exposure to low levels of ionizing radiation (IR) in radiology department staff may affect their antioxidant status. The aim of this study was to evaluate the oxidative stress parameters in radiology staff that are occupationally exposed to IR in a hospital setting. Materials and methods: The study population included 40 exposed radiology staff and 30 control subjects. The radiation doses of exposed staff ranged between 0.10 and 3.8 milligray (mGy) per month. The subjects' antioxidant status was determined by measuring the activities of copper zinc-superoxide dismutase (CuZn-SOD), selenium dependent glutathione peroxidase (Se-GPx), catalase (CAT) enzymes, and the levels of malondialdehyde (MDA) in erythrocytes. Results: Our results showed that the activities of erythrocyte CuZn-SOD and Se-GPx enzymes observed for the radiation exposed group were significantly higher than in the controls. The activity of CAT enzyme and MDA levels were significantly lower in the exposed group than in the controls. Moreover, we investigated the influence of confounding factors on antioxidant enzymes or lipid peroxidation (LP), but we could not find any associations between them. Conclusions: Our study indicates the presence of stimulant effect of chronic low-dose radiation in exposed individuals, resulting in enhanced resistance to oxidative stress.     

Micronuclei in the peripheral blood and bone marrow cells of rats exposed to 2450 MHz radiofrequency radiation.

PURPOSE: To determine the incidence of micronuclei in peripheral blood and bone marrow cells of rats exposed continuously for 24h to 2450 MHz continuous wave radiofrequency radiation (RFR) at an average whole-body specific absorption rate (SAR) of 12W/kg. MATERIALS AND METHODS: Eight adult male Sprague-Dawley rats were exposed to 2450 MHz RFR in circularly polarized waveguides. Eight sham-exposed rats were kept in similar waveguides without the transmission of RFR. Four rats were treated with mitomycin-C (MMC) and used as positive controls. All rats were necropsied 24h after the end of RFR and sham exposures, and after the 24h treatment with MMC. Peripheral blood and bone marrow smears were examined to determine the frequency of micronuclei (MN) in polychromatic erythrocytes (PCE). RESULTS: The results indicated that the incidence of MN/2000 PCE were not significantly different between RFR- and sham-exposed rats. The group mean frequencies of MN in the peripheral blood were 2.3+/-0.7 in RFR-exposed rats and 2.1+/-0.6 in sham-exposed rats. In bone marrow cells, the average MN incidence was 3.8+/-1.0 in RFR-exposed rats and 3.4+/-0.7 in sham-exposed rats. The corresponding values in positive control rats treated with MMC were 23.5+/-4.7 in the peripheral blood and 33.8+/-7.4 in bone marrow cells. CONCLUSION: There was no evidence for the induction of MN in peripheral blood and bone marrow cells of rats exposed for 24h to 2450 MHz continuous wave RFR at a whole body average SAR of 12 W/kg.     

Radiofrequency radiation does not significantly affect ornithine decarboxylase activity,proliferation, or caspase-3 activity of fibroblasts in different physiological conditions

Purpose: The aim of this study was to test the hypothesis that variations in the physiological state of cells explain inconsistent results from in vitro studies on biological effects of radiofrequency (RF) radiation.

Materials and methods: Murine L929 fibroblasts stimulated with fresh medium, stressed with serum deprivation or not subjected to stimulation or stress were exposed in a waveguide exposure chamber to 872 MHz continuous wave or pulse modulated (217 pulses per second) RF radiation at specific absorption rate of 5 W/kg. Ornithine decarboxylase (ODC) activity after 1-and 24-h exposures, proliferation during 48 h after 24 h exposure, and caspase-3 activity (a measure of apoptosis) after 1 h exposure were measured.

Results: The cells responded to fresh medium and serum deprivation, but no consistent effects of RF radiation were found. One statistically significant (p = 0.03) RF radiation-related difference was observed in ODC activity, but this is most likely a chance finding, as many statistical comparisons were performed, and the finding was not supported by any other data.

Conclusions: The results did not support effects on the endpoints studied. Furthermore, stressed and stimulated cells were not more sensitive than normal cells to possible RF radiation-induced effects.     

Gene expression analysis in human malignant melanoma cell lines exposed to carbon beams

PURPOSE: To elucidate the molecular changes in response to carbon beams (C-ions) in melanoma. MATERIALS AND METHODS: We examined expression profiles of 6 melanoma cell lines exposed to C-ions or X-rays with 2 Gy using single-color microarrays. RESULTS: Twenty-two genes, including nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (NFKBIA), responded to C-ions in all six cell lines, based on analysis of variance (ANOVA) filtering (p < 0.001). We found 173 genes that responded in common to C-ions in four cell lines. We identified many down-regulated genes including the cell cycle - related genes that were more responsive to C-ions than X-rays. In contrast, most of the up-regulated genes including the tumor protein p53 (p53) target genes responded to both C-ions and X-rays. C-ions induced G2/M arrest significantly more than X-rays at 30 h (p < 0.05). CONCLUSION: Our findings suggest that down-regulation of gene expression plays a key role in the response to C-ions. Regulation of cell cycle - related genes and induction of prolonged G2/M arrest may be responsible for the extra sensitivity to C-ions, whereas p53-related genes may have similar roles in the sensitivities to both C-ions and X-rays.     

Medium-mediated effects increase cell killing in a human keratinocyte cell line exposed to solar-simulated radiation

Purpose:?The objective of this study was to investigate whether cell culture medium is a biologically relevant exposure medium that can be employed in non-ionising photobiological investigations.

Methods:?The effect of solar-simulated irradiation on cell culture medium and its ability to elicit cell death was studied. The role of reactive oxygen species (ROS), cell secreted factors, and the contribution of individual components of the medium were investigated.

Results:?Cell death was found to be primarily mediated through the formation of ROS via riboflavin photosensitisation and degradation in the cell culture medium. Phenol red was found to significantly reduce the cell killing ability of riboflavin. Exposures in riboflavin-free medium resulted in significantly increased cell survival compared to identical exposures in riboflavin containing medium.

Conclusions:?This study has shown that solar radiation toxicity is augmented by cell culture medium due to the presence of riboflavin. Results suggest that exposures performed in phenol red-free medium may serve to increase phototoxic effects if riboflavin is present. Riboflavin-free media is recommended for solar radiation investigations to eliminate concerns regarding riboflavin photosensitisation and nutrient deprivation.     

Radiation-induced apoptosis in human non-small-cell lung cancer cell lines is secondary to cell-cycle progression beyond the G2-phase checkpoint

PURPOSE: To characterize the relationship between cell-cycle progression and radiation-induced apoptosis in NSCLC cell lines with different p53 status. MATERIALS AND METHODS: Cell lines with functional (H460, A549) and non-functional p53 (H661 and H520) were irradiated with 20 Gy. Multiparameter flow-cytometry was used to follow the progression of synchronized cells through the cell cycle after irradiation. RESULTS: Delayed apoptosis was observed after cell-cycle progression beyond the G2 block, either in the late G2/M-phase of the same cell cycle being irradiated (H661, H520) or in the G1-phase of the subsequent cell cycle (H460, A549). The apoptotic fraction in H661 and H520 was 60-80% at 144h after irradiation, higher than in A549 and H460 (5 and 35%, respectively). As an alternative to apoptosis in cells cycling beyond the G2 restriction point, hyperploid cells were generated by all cell lines. Inhibition of cell-cycle progression through the G2/M-phase efficiently reduced the induction of late apoptosis. After irradiation in S-phase, 50-60% of cells with functional p53 remained arrested at the G2 restriction point until 144 h post-irradiation, while only 20% of the H661 or H520 did so. CONCLUSIONS: These data characterize radiation-induced apoptosis in NSCLC cell lines as a removal pathway of clonogenically inactivated cells secondary to cell-cycle progression beyond G2/M, and is unlikely to be a critical factor for cellular radiation sensitivity.     

Radiation-induced apoptosis in human non-small-cell lung cancer cell lines is secondary to cell-cycle progression beyond the G2-phase checkpoint

Purpose : To characterize the relationship between cell-cycle progression and radiation-induced apoptosis in NSCLC cell lines with different p53 status. Materials and methods : Cell lines with functional (H460, A549) and non-functional p53 (H661 and H520) were irradiated with 20 Gy. Multiparameter flow-cytometry was used to follow the progression of synchronized cells through the cell cycle after irradiation. Results : Delayed apoptosis was observed after cell-cycle progression beyond the G2 block, either in the late G2/M-phase of the same cell cycle being irradiated (H661, H520) or in the G1-phase of the subsequent cell cycle (H460, A549). The apoptotic fraction in H661 and H520 was 60-80% at 144 h after irradiation, higher than in A549 and H460 (5 and 35%, respectively). As an alternative to apoptosis in cells cycling beyond the G2 restriction point, hyperploid cells were generated by all cell lines. Inhibition of cell-cycle progression through the G2/M-phase efficiently reduced the induction of late apoptosis. After irradiation in S-phase, 50-60% of cells with functional p53 remained arrested at the G2 restriction point until 144 h post-irradiation, while only 20% of the H661 or H520 did so. Conclusions : These data characterize radiation-induced apoptosis in NSCLC cell lines as a removal pathway of clonogenically inactivated cells secondary to cell-cycle progression beyond G2/M, and is unlikely to be a critical factor for cellular radiation sensitivity.     

Induction of adaptive response in human blood lymphocytes exposed to 900 MHz radiofrequency fields: Influence of cell cycle

Abstract

Purpose: To investigate the influence of cell cycle on the adaptive response (AR) induced by the exposure of human blood lymphocytes to radiofrequency fields (RF).

Materials and methods: Human peripheral blood lymphocytes in G₀-, G₁- or S-phase of the cell cycle were exposed for 20 hours to an adaptive dose (AD) of 900 MHz RF at an average specific absorption rate of 1.25 W/kg and then treated with a challenge dose (CD) of 100 ng/ml mitomycin C (MMC). Un-exposed and sham-exposed controls as well as cells treated with MMC alone were included in the study. The incidence of micronuclei (MN) was evaluated to determine the induction of AR.

Results: The results indicated that the cells which were exposed to AD of RF in G₀- and G₁-phase of the cell cycle did not exhibit AR while such a response was observed when the cells were exposed to AD of RF in S-phase of the cell cycle.

Conclusions: These results confirmed the observations reported in our previous investigation where AR was observed in human blood lymphocytes exposed to AD of RF in S-phase of the cell cycle and further suggested that the timing of AD exposure of RF is important to elicit AR.     

反义端粒酶RNA抑制胶质瘤细胞系BT—325细胞端粒酶活性表达

目的：观察反义端粒酶RNA对BT－325细胞的作用,探讨粒酶在恶性胶质瘤发生过程中的可能作用及反义端粒酶RNA在恶性胶质瘤基因治疗中的意义。方法：经脂质体介导的方法将pBBS 212-hTR(反义端粒酶RNA真核表达载体）导入BT－325细胞中,细胞克隆转移扩大培养后,采用TRAP－PAGE电泳,电镜和TUNEL技术检测BT－325／pBBS 212-hTR的细胞的端粒活性表达,细胞凋亡的情况。结果：与对照组比较,反义端粒酶RNA显著抑制BT－325细胞端粒酶活性,诱发细胞发生凋亡。结论：转染反义端粒酶RNA在封闭细胞粒酶活性表达的同时,可促进BT－325细胞凋亡,在研究恶性胶质瘤发病机制及治疗方面做了有益的探讨。     

Knee crepitus is prevalent in women with patellofemoral pain,but is not related with function,physical activity and pain

Objectives(i) To assess the reliability of knee crepitus measures, (ii) to investigate the association between knee crepitus and PFP; (iii) to investigate the relationship between knee crepitus with self-reported function, physical activity and pain.DesignCross-sectional.SettingLaboratory-based study.Participants165 women with PFP and 158 pain-free women.Main outcome measuresKnee crepitus test, anterior knee pain scale (AKPS) and self-reported worst knee pain in the last month, knee pain after 10 squats and knee pain after 10 stairs climbing.ResultsKnee crepitus clinical test presented high reliability Kappa value for PFP group was 0.860 and for pain-free group was 0.906. There is a significantly greater proportion of those with crepitus in the PFP group than in the pain-free group (OR = 4.19). Knee crepitus had no relationship with function (rpb = 0.03; p = 0.727), physical activity level (rpb = 0.010; p = 0.193), worst pain (rpb = 0.11; p = 0.141), pain climbing stairs (rpb = 0.10; p = 0.194) and pain squatting (rpb = 0.02; p = 0.802).ConclusionWomen who presents knee crepitus have 4 times greater odds to be in a group with PFP compared to those who do not. However, knee crepitus has no relationship with self-reported clinical outcomes of women with PFP.