| 1. |
- Persson, Bertil R.R., et al.
(författare)
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Effects of microwaves from GSM mobile phones on the blood-brain barrier and neurons in rat brain
- 2005
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Ingår i: PIERS 2005 - Progress in Electromagnetics Research Symposium, Proceedings. - 1933077077 - 9781933077079 ; , s. 638-641
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Konferensbidrag (refereegranskat)abstract
- Our group has since 1988 studied the effects of different intensities and modulations of 915MHz RF in a rat model where the exposure takes place in a TEM-cell during various time periods and post exposure recovery times. The power fed into TEM-cells was 0.125, 1.25, 12.5 or 125mW corresponding to whole body SAR (determined experimentally): 0.2, 2, 20 or 200mW/kg. The rats were awake and not restrained during exposure and after the recovery period the animals were anaesthetized and sacrificed by perfusion-fixation with 4% formaldehyde. Paraffin embedded 5 μm. thick brain slices were stained for albumin by applying albumin antibodies (Dakopatts), by which albumin is revealed as brownish discolorations. Dark neurons were revealed by staining for RNA/DNA with cresyl violet. In series of more than 1800 Fisher rats, we have proven that sub thermal power levels from both pulse-modulated and continuous RF fields - including those from real GSM mobile phones - have the potency to significantly open the BBB for the animals' own albumin (but not fibrinogen) to pass out into the brain and to accumulate in the neurons and glial cells surrounding the capillaries. Albumin extravasations are most prominent at the lower SAR values. This dose-response behaviour suggests some kind of energy or electromagnetic field strength windowing effect. A linear dose-response relationship for dark neurons was found at 50 days after exposure, with most prominent occurrence at SAR 200mW/kg.
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| 2. |
- Persson, Bertil R, et al.
(författare)
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Blood-brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication
- 1997
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Ingår i: Wireless Networks. - 1022-0038. ; 3, s. 455-461
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Tidskriftsartikel (refereegranskat)abstract
- iological effects of radio frequency electromagnetic fields (EMF) on the blood-brain barrier (BBB) have been studied in Fischer 344 rats of both sexes. The rats were not anaesthetised during the exposure. All animals were sacrificed by perfusion–fixation of the brains under chloralhydrate anaesthesia after the exposure. The brains were perfused with saline for 3–4 minutes, and thereafter perfusion fixed with 4% formaldehyde for 5–6 minutes. Whole coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 m. Albumin and fibrinogen were demonstrated immunohistochemically and classified as normal versus pathological leakage. In the present investigation we exposed male and female Fischer 344 rats in a Transverse Electromagnetic Transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse-modulated with different pulse power and at various time intervals. The CW-pulse power varied from 0.001 W to 10 W and the exposure time from 2 min to 960 min. In each experiment we exposed 4–6 rats with 2–4 controls randomly placed in excited and non-excited TEM-cells respectively. We have in total investigated 630 exposed rats at various modulation frequencies and 372 controls. The frequency of pathological rats is significantly increased (p < 0:0001) from 62=372 (ratio: 0:170:02) for control rats to 244=630 (ratio: 0:390:03) in all exposed rats. Grouping the exposed animals according to the level of specific absorbed energy (J/kg) give significant difference in all levels above 1.5 J/kg. The exposure was 915 MHz microwaves either pulse modulated (PW) at 217 Hz with 0.57 ms pulse width, at 50 Hz with 6.6 ms pulse width or continuous wave (CW). The frequency of pathological rats (0:17) among controls in the various groups is not significantly different. The frequency of pathological rats was 170=481 (0:350:03) among rats exposed to pulse modulated (PW) and 74=149 (0:500:07) among rats exposed to continuous wave exposure (CW). These results are both highly significantly different to their corresponding controls (p < 0:0001) and the frequency of pathological rats after exposure to pulsed radiation (PW) is significantly less (p < 0:002) than after exposure to continuous radiation (CW).
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| 3. |
- Persson, Bertil R.R., et al.
(författare)
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A Model for Evaluating Therapeutic Response of Combined Cancer Treatment Modalities : Applied to Treatment of Subcutaneously Implanted Brain Tumors (N32 and N29) in Fischer Rats with Pulsed Electric Fields (PEF) and 60Co-gamma Radiation (RT)
- 2003
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Ingår i: Technology in Cancer Research and Treatment. - : SAGE Publications. - 1533-0346 .- 1533-0338. ; 2:5, s. 459-470
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study is to develop a mathematical model for evaluating therapeutic response of combined treatment modalities. The study was performed in rats of the Fischer-344 strain with rat glioma N32 or N29 tumors implanted subcutaneously on the thigh of the hind leg. Pulsed electric fields, PEF, with 16 exponentially decaying pulses with a maximum electric field strength of 140 V/mm and t1/e = 1 ms were first applied to the tumors. Then within 5 min radiation therapy with 60Co-gamma radiation, RT, was given in daily fractions of 5 Gy. The animals were arranged into one group of controls and 3 groups of different kind of treatments: PEF only, RT only or combination of PEF + RT. At about 4 weeks after inoculation, the tumors were given the treatment sessions during one week. In 2 experimental series with totally 52 rats with N32 tumors, of which 16 were controls, were given 4 sessions of PEF treatments and RT (totally 20 Gy). In a special experimental series with totally 56 rats with N32 tumors, of which 10 were controls, the different groups were given 1, 2, 3 or 4 treatment sessions respectively, Another strain of glioma tumor, N29 with 62 tumors of which 14 were controls was studied in 2 series given 4PEF + 4RT and 2PEF + 4RT respectively. Fitting the data obtained from consecutive measurements of tumor volume (TV) of each individual tumor to an exponential model TV = TV 0 · exp[TGR · t] estimated the tumor growth rate (TGR % per day) after the first day of treatment (t = 0). The TGR of N32 tumors treated with the combination of 4PEF + 4RT are significantly decreased compared to the controls (p < 0.0001), compared to RT alone (p < 0.0001) and compared to PEF alone (p < 0.001). The combined treatment of N32 gives significant effect on the tumor growth rate after 2, 3 and 4 treatment session while RT alone seems to be most efficient after one treatment of 5 Gy and PEF alone is most efficient after 2 treatments at 2 consecutive days. The TGR of N29 tumors treated with the combination of 4PEF + 4RT are significantly decreased compared to the controls (p < 0.05) but the combination of 2PEF + 4RT was more effective (p < 0.005). The specific therapeutic effect STE is defined as the difference between the average tumor growth rates of controls and exposed tumors divided by the average tumor growth rate of the controls. With 4PEF treatments alone the average STE value was 0.32 for N32 tumors and 0 for N29; for 4RT alone the STE values were 0.29 and 0.42 respectively, and for combined treatments 4PEF + 4RT 0.67 and 0.17 respectively. For the N29 tumors treated with 2PEF + 4RT the STE value was 0.53. The therapeutic enhancement ratio, TER, value increase with the number of treatment sessions and the TER of the combined treatments is above 1 in two of the N32 series, which indicates a synergistic effect of 4PEF + 4RT. This work demonstrate the use of our model for analyzing the combination PEF + RT, but it can also be used for evaluation the therapeutic effects of combining RT with chemotherapy or immunogene-therapy.
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| 4. |
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| 5. |
- Engström, Per E., et al.
(författare)
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Effect of high voltage electrical pulses on subcutaneous glioma tumours on rats
- 1998
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Ingår i: Bioelectrochemistry and Bioenergetics. - 0302-4598. ; 47:1, s. 163-166
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Tidskriftsartikel (refereegranskat)abstract
- The antitumour effect of applied high voltage exponential pulses was investigated on rats with subcutaneously implanted N32 brain tumours. Superficial tumours on the thigh were produced by the injection of 100 000 N32 glioma cells on Fischer-344 rats. Four weeks after inoculation, a solid tumour has grown to a size of about 1 cm located directly under the skin. Short electric high voltage pulses were given transdermally through stainless steel plate electrodes. Sixteen exponential pulses with initial field strength of 1300-1400 V/cm and a time constant of 1 ms were delivered with a BTX600 device at approximately one pulse per second. The treatment was repeated during 4 consecutive days. Tumour response was studied by measuring the length, width and thickness of the tumour with a slide-calliper and estimating the tumour volume as an ellipsoid. Animals (treated and controls) were sacrificed when the size of the tumour had reached a predetermined value (5 cm3). In the first experiment this occurred after 50±4 days for the treated animals, excluding cured, compared to 40±1.3 for their controls and in the second experiment after 64±24 days excluding cured animals compared to 37.6±3 for the controls. All treated animals showed an initial partial or complete tumour remission within a few days after the end of the 4-day treatment. Two out of ten treated animals were cured with no sign of recurrence after 100 days. Copyright (C) 1998 Elsevier Science S.A.
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| 6. |
- Nittby, Henrietta, et al.
(författare)
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Analgetic effects of non-thermal GSM-1900 radiofrequency electromagnetic fields in the land snail Helix pomatia
- 2012
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 88:3, s. 245-252
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Tidskriftsartikel (refereegranskat)abstract
- Purpose : To investigate whether mobile phone radiation might affect snail nociception, employing radiofrequency (RF) electromagnetic fields (EMF) which, to our knowledge, have hitherto not been studied in a snail model. Exposure to extremely low frequency (ELF) magnetic fields has however been shown to significantly affect nociceptive responses. Materials and methods : In the present study, we exposed 29 land snails of the strain Helix pomatia to global system for mobile communications (GSM) EMF at 1900 MHz at the non-thermal level 48 mW/kg for 1 hour each and 29 snails were sham controls. The experiments took place during the onset of summer, with all snails being well out of hibernation. Before and after GSM or sham exposure, the snails were subjected to thermal pain by being placed on a hot plate. The reaction time for retraction from the hot plate was measured by two blinded observers. Results : Comparing the reaction pattern of each snail before and after exposure, the GSM-exposed snails were less sensitive to thermal pain as compared to the sham controls, indicating that RF exposure induces a significant analgesia (Mann-Whitney p < 0.001). Conclusion : This study might support earlier findings, describing beneficial effects of EMF exposure upon nociception.
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| 7. |
- Nittby, Henrietta, et al.
(författare)
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Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex
- 2008
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Ingår i: The Environmentalist. - : Springer Science and Business Media LLC. - 0251-1088 .- 1573-2991. ; 28:4, s. 458-465
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Tidskriftsartikel (refereegranskat)abstract
- We have earlier shown that radio frequency electromagnetic fields can cause significant leakage of albumin through the blood-brain barrier of exposed rats as compared to non-exposed rats, and also significant neuronal damage in rat brains several weeks after a 2 h exposure to a mobile phone, at 915 MHz with a global system for mobile communications (GSM) frequency modulation, at whole-body specific absorption rate values (SAR) of 200, 20, 2, and 0.2 mW/kg. We have now studied whether 6 h of exposure to the radiation from a GSM mobile test phone at 1,800 MHz (at a whole-body SAR-value of 13 mW/kg, corresponding to a brain SAR-value of 30 mW/kg) has an effect upon the gene expression pattern in rat brain cortex and hippocampus-areas where we have observed albumin leakage from capillaries into neurons and neuronal damage. Microarray analysis of 31,099 rat genes, including splicing variants, was performed in cortex and hippocampus of 8 Fischer 344 rats, 4 animals exposed to global system for mobile communications electromagnetic fields for 6 h in an anechoic chamber, one rat at a time, and 4 controls kept as long in the same anechoic chamber without exposure, also in this case one rat at a time. Gene ontology analysis (using the gene ontology categories biological processes, molecular functions, and cell components) of the differentially expressed genes of the exposed animals versus the control group revealed the following highly significant altered gene categories in both cortex and hippocampus: extracellular region, signal transducer activity, intrinsic to membrane, and integral to membrane. The fact that most of these categories are connected with membrane functions may have a relation to our earlier observation of albumin transport through brain capillaries.
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| 8. |
- Nittby, Henrietta, et al.
(författare)
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Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability
- 2011
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Ingår i: The Environmentalist. - : Springer Science and Business Media LLC. - 0251-1088 .- 1573-2991. ; 31:2, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Since the late 1980s, our group has examined the effects of radiofrequency electromagnetic fields (RF-EMF), including pulse-modulated waves of the type emitted by mobile phones, upon the blood-brain barrier. In more than 2,000 rats, we have repeatedly demonstrated a passage of the rats' own albumin from the blood through the brain capillaries into the surrounding brain parenchyma at SAR values down to 0.1mW/kg. In most of these experiments, the animals were exposed in TEM-cells, ventilated by an external electrical fan at 50 Hz. In the present study, we examined whether the extremely low frequency (ELF) magnetic fields from the fan (50 Hz, 0.3-1.5 μT) might add to the RF effect. Sixty-four rats were divided into 4 groups: RF only, ELF only and RF + ELF exposure plus a sham group. The GSM-900 MHz RF exposure was at the very low, nonthermal, average whole-body SAR level 0.4 mW/kg. Demonstration of the normally occurring albumin extravasation in the basal hypothalamus is our inbuilt control proving that the staining is reliable. Two full series of staining of the whole material gave negative results for hypothalamus. Not until we changed to avidin, biotin, and antibodies from a third supplier, we received an acceptable staining. Twenty-five percent of the RF animals had a pathological albumin leakage, while the ELF and RF + ELF groups with three and two pathological findings, respectively, were not significantly different from the control group. We conclude that the use of external fans has had no major influence upon the result.
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| 9. |
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| 10. |
- Salford, Leif G., et al.
(författare)
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Experimental studies of brain tumour development during exposure to continuous and pulsed 915 MHz radiofrequency radiation
- 1993
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Ingår i: Bioelectrochemistry and Bioenergetics. - 0302-4598. ; 30:C, s. 313-318
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that electromagnetic fields (EMFs) act as a promoter late in the carcinogenesis process. To date, however, noconvincing laboratory evidence has been obtained indicating that EMFs cause tumour promotion at non-thermal exposure levels. The effects of EMF exposure in a rat brain glioma model were investigated. The exposure consisted of 915 MHz microwaves, both as continuous waves (1 W), and modulated with 4, 8, 16 and 200 Hz in 0.5 ms pulses and 50 Hz in 6 ms pulses (2 W per pulse). Fischer 344 rats of both sexes, weighing 150-250 g, were used in the experiments. 5000 RG2 cells in 5 μ1 nutrient solution were injected by the stereotaxic technique into the head of the right caudate nucleus in 37 experimental rats and 37 matched controls. The exposed animals were kept unanaesthetized in well ventilated transverse electromagnetic (TEM) cells producing 915 MHz continuous or modulated microwaves. Exposure was started on day five after inoculation. The animals were exposed for 7 hd d-1 for 5 d per week during two to three weeks. The controls were kept in an identical TEM cell without EMF exposure. All brains were examined histopathologically and the tumour size was determined. Our study does not show a significant difference in tumour size between animals exposed to 915 MHz microwaves, and those not exposed. Our preliminary results do not support that even an extensive daily exposure to EMF promotes tumour growth when given from the fifth day after the start of tumour growth in the rat brain until the death of the animal which by then has a large brain tumour. Further studies with higher specific absorption rate levels are in progress.
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