Effects of GSM-900 microwaves on DMBA-induced mammary gland tumors in female Sprague-Dawley rats

The aim of this investigation was to test the hypothesis that sub-chronic whole-body exposure to GSM-900 microwaves had an effect on tumor promotion and progression. Mammary tumors were induced by ingestion of a single 10-mg dose of 7,12-dimethylbenz(a)anthracene (DMBA) in female Sprague-Dawley rats (Ico:OFA-SD; IOPS Caw). In two independent experiments, DMBA-treated animals were divided into four groups: sham-exposed (16) and exposed (three groups of 16 animals). The specific absorption rates (SARs), averaged over the whole body, were 3.5, 2.2 and 1.4 W/kg in the first experiment (May-July) and 1.4, 0.7 and 0.1 W/kg in the second experiment (September-November). Exposure started 10 days after DMBA treatment and lasted 2 h/day, 5 days/week for 9 weeks. Animals were exposed to plane waves with the electric field parallel to the long axis of the animals. Body weight and the number, location and size of the tumors were recorded at regular intervals. Rats were killed humanely 3 weeks after the end of exposure. The results are negative in terms of latency, multiplicity and tumor volume. With regard to tumor incidence, in the first experiment there was an increase in the rate of incidence at 1.4 W/kg but less at 2.2 W/kg and none at 3.5 W/kg. Overall, these results, which are rather inconsistent, do not bring new evidence of a co-promoting effect of exposure to GSM-900 signals using the DMBA rat model.     

Effects of exposure of newborn patched1 heterozygous mice to GSM, 900 MHz

Patched1 heterozygous knockout mice (Ptc1+/-), an animal model of multiorgan tumorigenesis in which ionizing radiation dramatically accelerates tumor development, were used to study the potential tumorigenic effects of electromagnetic fields (EMFs) on neonatal mice. Two hundred Ptc1+/- mice and their wild-type siblings were enrolled in this study. Newborn mice were exposed to 900 MHz radiofrequency radiation (average SAR: 0.4 W/kg for 5 days, 0.5 h twice a day) or were sham exposed. We found that RF EMFs simulating the Global System for Mobile Communications (GSM) did not affect the survival of the mice, because no statistically significant differences in survival were found between exposed and sham-exposed animals. Also, no effects attributable to radiofrequency radiation were observed on the incidence and histology of Ptc1-associated cerebellar tumors. Moreover, the skin phenotype was analyzed to look for proliferative effects of RF EMFs on the epidermal basal layer and for acceleration of preneoplastic lesions typical of the basal cell carcinoma phenotype of this model. We found no evidence of proliferative or promotional effects in the skin from neonatal exposure to radiofrequency radiation. Furthermore, no difference in Ptc1-associated rhabdomyosarcomas was detected between sham-exposed and exposed mice. Thus, under the experimental conditions tested, there was no evidence of life shortening or tumorigenic effects of neonatal exposure to GSM RF radiation in a highly tumor-susceptible mouse model.     

Comparison of bioactivity between GSM 900 MHz and DCS 1800 MHz mobile telephony radiation

An increasing number of studies find that pulsed Radio Frequency (RF), electromagnetic radiation of both systems of digital mobile telephony, established and commonly used in Europe during the last years, GSM 900 MHz (Global System for Mobile telecommunications) and DCS 1800 MHz (Digital Cellular System), exert intense biological action on different organisms and cells (Hardell et al., 2006; Hyland, 2000; Kundi, 2004; Panagopoulos et al., 2004, 2007). The two types of cellular telephony radiation use different carrier frequencies and give different frequency spectra, but they usually also differ in intensity, as GSM 900 MHz antennas operate at about double the power output than the corresponding DCS 1800 MHz ones. In our present experiments, we used a model biological system, the reproductive capacity of Drosophila melanogaster, to compare the biological activity between the two systems of cellular mobile telephony radiation. Both types of radiation were found to decrease significantly and non thermally the insect's reproductive capacity, but GSM 900 MHz seems to be even more bioactive than DCS 1800 MHz. The difference seems to be dependent mostly on field intensity and less on carrier frequency.     

Cytogenetic effects of 900 MHz (GSM) microwaves on human lymphocytes

The cytogenetic effects of 900 MHz radiofrequency fields were investigated with the chromosome aberration and sister chromatid exchange frequency methods. Three different modes of exposure (continuous, pseudo-random and dummy burst) were studied for different power outputs (0, 2, 8, 15, 25, 50 W). The specific absorption rates varied between 0 and 10 W/kg. We investigated the possible effects of the 900 MHz radiation alone as well as of combined exposure to the chemical or physical mutagens mitomycin C and X-rays. Overall, no indication was found of a mutagenic, and/or co-mutagenic/synergistic effect of this kind of nonionizing radiation.     

Phospholipase C activity in normal rat mammary tissues and in DMBA-induced rat mammary tumors

Employing phosphatidylinositol as the substrate, phospholipase C (PLC) activity was measured in various cellular fractions derived from DMBA-induced rat mammary tumors and mammary tissues from 12-14 day pregnant rats. In the 2,000g pellet, 10,000g pellet, 100,000g pellet and 100,000g supernatant fractions, PLC activity was more than 5 fold higher in the fractions derived from the neoplastic tissues. This was true whether PLC activity was expressed on the basis of protein content or 5' nucleotidase activities.     

Inhibitory effect of combined treatment with the aromatase inhibitor exemestane and tamoxifen on DMBA-induced mammary tumors in rats

The antitumor effect of exemestane (FCE 24304), an irreversible aromatase inhibitor, given alone or in combination with tamoxifen, was investigated in rats with 7, 12-dimethylbenzanthracene (DMBA)-induced mammary tumors. The compounds were given once daily, 6 days a week for 4 weeks. Exemestane, given at the dose of 20 mg/kg/day s.c., induced 26% complete (CR) and 18% partial (PR) tumor regressions, compared to 0% CR and 6% PR observed in controls. Tamoxifen, given at 1 mg/kg/day p.o., induced 16% CR and 13% PR. The combined treatment caused 41% CR and 16% PR, thus resulting in a higher antitumor effect than either single treatment. The apperance of new tumors was reduced by each single treatment and almost totally prevented by the combined treatment. Serum prolactin (PRL) levels, assayed 4 h after the last dose, were unchanged in the group treated with the combination, whereas tamoxifen alone caused a slight increase of serum PRL. These results indicate that estrogen deprivation through aromatase inhibition and estrogen receptor antagonism causes a better inhibition of DMBA-induced mammary tumors than either treatment modality alone.     

GSM and DCS wireless communication signals: combined chronic toxicity/carcinogenicity study in the Wistar rat

A total of 1170 rats comprised of 65 male and 65 female Han Wistar rats per group were exposed for 2 h/day, 5 days/ week for up to 104 weeks to GSM or DCS wireless communication signals at three nominal SARs of 0.44, 1.33 and 4.0 W/kg. A preliminary study confirmed that the highest exposure level was below that which was capable of causing a measurable increase in the core temperature of the rat. Additional groups for each modulation were sham exposed, and there was also an unrestrained, unexposed (cage) control group. Fifteen male and 15 female rats per group were killed after 52 weeks. From the remaining 50 male and 50 female rats per group, surviving animals were killed after 104 weeks. Evaluations during the study included mortality rate, clinical signs, recording of palpable masses, body weight, food consumption, ophthalmoscopic examination, and clinical pathological investigations. Terminal investigations included organ weight measurement and macroscopic and microscopic pathology examinations. There was no adverse response to the wireless communication signals. In particular, there were no significant differences in the incidence of primary neoplasms, the number of rats with more than one primary neoplasm, the multiplicity and latency of neoplasms, the number of rats with metastases, and the number of benign and malignant neoplasms between the rats exposed to wireless communication signals and rats that were sham exposed.     

Effects of 900 MHz Radiofrequency Radiation on Skin Hydroxyproline Contents

The present study aimed to investigate the possible effect of pulse-modulated radiofrequency radiation (RFR) on rat skin hydroxyproline content, since skin is the first target of external electromagnetic fields. Skin hydroxyproline content was measured using liquid chromatography mass spectrometer method. Two months old male wistar rats were exposed to a 900 MHz pulse-modulated RFR at an average whole body specific absorption rate (SAR) of 1.35 W/kg for 20 min/day for 3 weeks. The radiofrequency (RF) signals were pulse modulated by rectangular pulses with a repetition frequency of 217 Hz and a duty cycle of 1:8 (pulse width 0.576 ms). A skin biopsy was taken at the upper part of the abdominal costa after the exposure. The data indicated that whole body exposure to a pulse-modulated RF radiation that is similar to that emitted by the global system for mobile communications (GSM) mobile phones caused a statistically significant increase in the skin hydroxyproline level (p = 0.049, Mann–Whitney U test). Under our experimental conditions, at a SAR less than the International Commission on Non-Ionizing Radiation Protection safety limit recommendation, there was evidence that GSM signals could alter hydroxyproline concentration in the rat skin.     

Effects of GSM signals on auditory evoked responses

The article presents a study of the influence of radio frequency (RF) fields emitted by mobile phones on human cerebral activity. Our work was based on the study of Auditory Evoked Potentials (AEPs) recorded on the scalp of healthy humans and epileptic patients. The protocol allowed us to compare AEPs recorded with or without exposure to RFs. To get a reference, a control session was also introduced. In this study, the correlation coefficients computed between AEPs, as well as the correlation coefficients between spectra of AEPs were investigated to detect a possible difference due to RFs. A difference in the correlation coefficients computed in control and experimental sessions was observed, but it was difficult to deduce the effect of RFs on human health.     

Effect of long-term exposure of mice to 900 MHz GSM radiation on experimental cutaneous candidiasis

Mobile phones communicate with base stations using 900 MHz microwaves. The current study was aimed to survey the effects of long-term 900 MHz microwave exposure of mice on experimentally induced cutaneous candidiasis. Forty inbred, male, BALB/c mice were randomly divided into four groups. Cutaneous lesions with Candida albicans were experimentally induced on the lateral-back skin of the 20 mice. One group of the diseased mice were exposed (6 h per day and 7 d per week) to 900 MHz microwave radiation, while the other groups were not exposed. Two unexposed control groups were also included. The skin lesions were regularly monitored and the live candida cell density was enumerated using the colony-forming unit (CFU) assay. The process was repeated after a one week resting interval. One week later, all mice were challenged through intra tail veins using LD₉₀ dose of C. albicans. Mortality of the mice was recorded and the candida load of the kidney homogenates from died animals was counted. 900 MHz microwave exposed mice had 1.5 day and 3.7 day delays on wound healing in stages two. Live Candida inoculated Wave exposed (LCW) mice also showed higher yeast loads in skin lesions at days 5, 7 and 9 post inoculation. Survival analysis of live candida challenged mice showed the radiation exposed group is prone to death induced by systemic infection and candida enumeration from the kidney homogenates showed radiation exposed animals have had significantly higher yeast load in the tissue. In collection, long-term 900 MHz radiation exposure of mice led to longevity of skin wounds and susceptibility of the animals to systemic challenge and higher incidences of microorganisms in internal tissues.     

Impacts of exposure to 900 MHz mobile phone radiation on liver function in rats

Objective: To study the impacts of exposure to electromagnetic radiation(EMR) on liver function in rats. Methods: Twenty adult male Sprague-Dawley rats were randomly divided into normal group and radiated group. The rats in normal group were not radiated, those in radiated group were exposed to EMR 4 h/d for 18 consecutive days. Rats were sacrificed immediately after the end of the experiment. The serum levels of alanine aminotransferase(ALT) and aspartate aminotransferase(AST), and those of malondialdehyde(MDA) and glutathione(GSH) in liver tissue were evaluated by colorimetric method. The liver histopathological changes were observed by hematoxylin and eosin staining and the protein expression of bax and bcl-2 in liver tissue were detected by immunohistochemical method. Terminal-deoxynucleotidyl transferase mediated nick and labelling(TUNEL) method was used for analysis of apoptosis in liver. Results: Compared with the normal rats, the serum levels of ALT and AST in the radiated group had no obvious changes(P0.05), while the contents of MDA increased(P0.01) and those of GSH decreased(P0.01) in liver tissues. The histopathology examination showed diffuse hepatocyte swelling and vacuolation, small pieces and focal necrosis. The immunohistochemical results displayed that the expression of the bax protein was higher and that of bcl-2 protein was lower in radiated group. The hepatocyte apoptosis rates in radiated group was higher than that in normal group(all P0.01). Conclusion: The exposure to 900 MHz mobile phone 4 h/d for 18 days could induce the liver histological changes, which may be partly due to the apoptosis and oxidative stress induced in liver tissue by electromagnetic radiation.     

Effects of in vivo exposure to GSM-modulated 900 MHz radiation on mouse peripheral lymphocytes

The aim of this study was to evaluate whether daily whole-body exposure to 900 MHz GSM-modulated radiation could affect spleen lymphocytes. C57BL/6 mice were exposed 2 h/day for 1, 2 or 4 weeks in a TEM cell to an SAR of 1 or 2 W/kg. Untreated and sham-exposed groups were also examined. At the end of the exposure, mice were killed humanely and spleen cells were collected. The number of spleen cells, the percentages of B and T cells, and the distribution of T-cell subpopulations (CD4 and CD8) were not altered by the exposure. T and B cells were also stimulated ex vivo using specific monoclonal antibodies or LPS to induce cell proliferation, cytokine production and expression of activation markers. The results did not show relevant differences in either T or B lymphocytes from mice exposed to an SAR of 1 or 2 W/kg and sham-exposed mice with few exceptions. After 1 week of exposure to 1 or 2 W/kg, an increase in IFN-gamma (Ifng) production was observed that was not evident when the exposure was prolonged to 2 or 4 weeks. This suggests that the immune system might have adapted to RF radiation as it does with other stressing agents. All together, our in vivo data indicate that the T- and B-cell compartments were not substantially affected by exposure to RF radiation and that a clinically relevant effect of RF radiation on the immune system is unlikely to occur.     

The effect of dietary zinc - and polyphenols intake on DMBA-induced mammary tumorigenesis in rats

Background

The aim of the study was to investigate the effect of dietary supplementation with zinc and polyphenol compounds, i.e. resveratrol and genistein, on the effectiveness of chemically induced mammary cancer and the changes in the content of selected elements (Zn, Cu, Mg, Fe, Ca) in tumors as compared with normal tissue of the mammary gland.

Methods

Female Sprague-Dawley rats were divided into study groups which, apart from the standard diet and DMBA (7,12-dimethyl-1,2- benz[a]anthracene), were treated with zinc ions (Zn) or zinc ions + resveratrol (Zn + resveratrol) or zinc ions + genistein (Zn + genistein) via gavage for a period from 40 days until 20 weeks of age. The ICP-OES (inductively coupled plasma optical emission spectrometry) technique was used to analyze the following elements: magnesium, iron, zinc and calcium. Copper content in samples was estimated in an atomic absorption spectrophotometer.

Results

Regardless of the diet (standard; Zn; Zn + resveratrol; Zn + genistein), DMBA-induced breast carcinogenesis was not inhibited. On the contrary, in the Zn + resveratrol supplemented group, tumorigenesis developed at a considerably faster rate. On the basis of quantitative analysis of selected elements we found - irrespectively of the diet applied - great accumulation of copper and iron, which are strongly prooxidative, with a simultaneous considerable decrease of the magnesium content in DMBA-induced mammary tumors. The combination of zinc supplementation with resveratrol resulted in particularly large differences in the amount of the investigated elements in tumors as compared with their content in normal tissue.

Conclusions

Diet supplementation with zinc and polyphenol compounds, i.e. resveratrol and genistein had no effect on the decreased copper level in tumor tissue and inhibited mammary carcinogenesis in the rat. Irrespectively of the applied diet, the development of the neoplastic process in rats resulted in changes of the iron and magnesium content in the cancerous tissue in comparison with the healthy mammary tissue. The application of combined diet supplementation with zinc ions and resveratrol considerably promoted the rate of carcinogenesis and increased the number of DMBA-induced mammary tumors.     

Epithelial organoids and mononuclear phagocytes from DMBA-induced mammary tumors of the rat secrete collagenase in vitro

The production of collagenase has been examined in primary cultures of multicellular epithelial organoids and of stromal cells isolated from DMBA-induced mammary tumors of the rat. Plastic culture dishes and dishes coated with collagen fibrils were used to study the effect of such a substrate on collagenase release. Cultures of 51-μm epithelial organoids consisted of cuboidal cells and a myoepithelial-like cell type which formed a continuous layer under the cuboidal cells. A transient low production of collagenase with an apparent molecular weight (MW) of 72 kD was detected on both substrates. Upon separation by trypsin only cuboidal cells released collagenase. Cultures of 27-μm organoids contained only few myoepithelial-like cells. On plastic, they formed dense monolayers of cuboidal cells and released more collagenase than the greater aggregates. On collagen fibrils, these organoids formed cords and ridges and collagenase production was about 4- to 6-fold higher. These results indicate that collagenase release is influenced by the nature of the interaction of cuboidal cells with the substrate on which they grow. Similar organoids prepared from virgin mammary glands failed to secrete collagenase on either substrate. Primary cultures of stromal cells derived from tumor tissues comprised one basic cell type that expressed a series of properties characteristic for monocytes/macrophages. These cultures were capable of producing collagenase with an apparent MW of 56 kD. Collagenase with a similar size was detected in the extracts of 51 from 65 mammary tumors.     

Antitumor effect of a specific aromatase inhibitor, 1-methyl-androsta-1,4-diene-3,17-dione (atamestane), in female rats bearing DMBA-induced mammary tumors

Atamestane is a potent competitive inhibitor of estrogen biosynthesis (aromatase) in several species, in vitro and in vivo, and has no endocrine side effects. In this study, the efficacy of atamestane in suppressing tumor growth was evaluated in comparing with that of a non-steroidal aromatase inhibitor (CGS 16949A, Ciba-Geigy) and ovariectomy. Female Sprague-Dawley rats bearing DMBA-tumors were treated s.c. once daily either with 30 or 150 mg/kg atamestane or with 0.1 or 0.5 mg/kg CGS 16949A for 4 weeks. At these biologically equivalent doses both aromatase inhibitors effectively inhibited tumor growth: at the end of treatment they caused a marked reduction in tumor size (up to 70%), while ovariectomy led to a complete remission of tumor growth. The histo-morphological pictures of the mammary tumors from treated animals were qualitatively almost similar to those of the control. In hosts, neither compound exerted any influence on the weight of genital organs (ovary, uterus and vagina), although the peripheral LH levels were significantly elevated by the higher dose of the aromatase inhibitors. This effect on LH levels is probably due to the elimination of the negative feed-back effect of estrogens on gonadotropin secretion (counter regulation). The serum prolactin levels were decreased by the aromatase inhibitors, indicating a diminution of estrogen levels in the treated animals. The present results clearly demonstrate that, in spite of the counter regulation, a pure aromatase inhibitor such as atamestane in sufficiently high doses is able to inhibit the growth of DMBA-induced mammary tumors in intact female rats.     

Effects of microwave radiation (340 and 900 MHz) on different structural levels of erythrocyte membranes

By use of fluorescence probes 1-anilinonaphthalene-8-sulfonic acid, 2-toluidinylnaphthalene-6-sulfonate, pyrene, perylene and chemical label phosphatidylethanolamine 2,4,6-trinitrobenzele sulfonic acid, the effect of microwave radiation on the erythrocyte membrane was studied. The studies with the fluorescence probes were carried out on erythrocyte ghosts and with 2,4,6-trinitrobenzene sulfonic acid on whole erythrocytes. The fluorescence was measured during irradiation of the membranes with 340-MHz microwaves at an SAR of 100 W/kg. Trinitrophenylation of phosphatidylethanolamine from whole erythrocytes was performed simultaneously with microwave irradiation at 900 MHz (10 mW/cm2). It was shown that the microwave field decreased lipid viscosity, altered the structural state of lipid-protein contact regions, and decreased the protein shielding of lipids. These changes corresponded to those produced by thermal action of microwaves.