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(Database last updated on Mar 27, 2024)
| ID Number | 1677 | |
| Study Type | In Vitro | |
| Model | Millimeter wave (mmwave) exposure (60 and 94 GHz) to cells and analysis of stress gene expression and cell membrane permeability. | |
| Details | U-251 human astrocytoma cells containing a luciferase reporter gene driven by an hsp70 promoter were exposed to 60 GHz mm waves at an estimated (SAR) within the cell monolayer between 2.64 +/- 0.08 to 3.3 +/- 0.1 W/kg for either 16 or 33 hours. Heat shock (42°C) and proteotoxin treatments (MG132) served as positive controls. The authors report no statistically significant effects on luciferase activity, or endogenous CLU or HSP70 gene expression due to mm wave exposure. In a related study, the authors exposed U-251 cells as above to discrete frequencies that overlap with the spectral lines of oxyggen (59.16, 60.43, 61.15 GHz) or overlap regions (59.87, 60.83 GHz) and analyzed the expression of two endoplasmic reticulum endogenous ER-stress biomarkers (chaperones BiP/GRP78 and ORP150/GRP170). The authors report no change in expression. AUTHORS'S ABSTRACT: Le Quement et al. 2014 (IEEE #5715): Emerging high data rate wireless communication systems, currently under development, will operate at millimeter waves (MMW) and specifically in the 60 GHz band for broadband short-range communications. The aim of this study was to investigate potential effects of MMW radiation on the cellular endoplasmic reticulum (ER) stress. Human skin cell lines were exposed at 60.4 GHz, with incident power densities (IPD) ranging between 1 and 20 mW/cm(2) . The upper IPD limits correspond to the ICNIRP local exposure limit for the general public. The expression of ER-stress sensors, namely BIP and ORP150, was then examined by real-time RT-PCR. Our experimental data demonstrated that MMW radiations do not change BIP or ORP150 mRNA basal levels, whatever the cell line, the exposure duration or the IPD level. Co-exposure to the well-known ER-stress inducer thapsigargin (TG) and MMW were then assessed. Our results show that MMW exposure at 20 mW/cm(2) inhibits TG-induced BIP and ORP150 over expression. Experimental controls showed that this inhibition is linked to the thermal effect resulting from the MMW exposure. AUTHORS' ABSTRACT: Fall et al. 2016 (IEEE #6442): This paper aims at introducing a calibration procedure for experimental dosimetry in a millimeter wave reverberation chamber. The proposed procedure is based on surface temperature measurements performed on a parallelepiped phantom using an infrared camera. The temperature rise measurement is compared to the value predicted by an analytical model. The latter is based on heat transfer formulation using the statistically homogeneous and isotropic electromagnetic field generated in the reverberation chamber. Temperature measurements are performed, at 59.3 GHz, on a dielectric phantom constituted of distilled water with a concentration of 4% of agar. Good agreement is observed between experimental and theoretical models. The difference between the peak specific absorption rate values estimated by two different approaches is about 16%. AUTHORS' ABSTRACT: Haas et al. 2016 (IEEE #6443): Millimeter waves (MMW) will be increasingly used for future wireless telecommunications. Previous studies on skin keratinocytes showed that MMW could impact the mRNA expression of Transient Receptor Potential cation channel subfamily Vanilloid, member 2 (TRPV2). Here, we investigated the effect of MMW exposure on this marker, as well as on other membrane receptors such as Transient Receptor Potential cation channel subfamily Vanilloid, member 1 (TRPV1) and purinergic receptor P2X, ligand-gated ion channel, 3 (P2 × 3). We exposed the Neuroscreen-1 cell line (a PC12 subclone), in order to evaluate if acute MMW exposures could impact expression of these membrane receptors at the protein level. Proteotoxic stress-related chaperone protein Heat Shock Protein 70 (HSP70) expression level was also assessed. We used an original high-content screening approach, based on fluorescence microscopy, to allow cell-by-cell analysis and to detect any cell sub-population responding to exposure. Immunocytochemistry was done after 24 h MMW exposure of cells at 60.4 GHz, with an incident power density of 10 mW/cm2 . Our results showed no impact of MMW exposure on protein expressions of HSP70, TRPV1, TRPV2, and P2 × 3. Moreover, no specific cell sub-populations were found to express one of the studied markers at a different level, compared to the rest of the cell populations. However, a slight insignificant increase in HSP70 expression and an increase in protein expression variability within cell population were observed in exposed cells, but controls showed that this was related to thermal effect. AUTHORS' ABSTRACT: Zhadobov et al. 2016 (IEEE #6503): Due to shallow penetration of millimeter waves (MMW) and convection in liquid medium surrounding cells, the problem of accurate assessment of local MMW heating in in vitro experiments remains unsolved. Conventional dosimetric MMW techniques, such as infrared imaging or fiber optic (FO) sensors, face several inherent limits. Here we propose a methodology for accurate local temperature measurement and subsequent specific absorption rate (SAR) retrieval using microscale thermocouples (TC). SAR was retrieved by fitting the measured initial temperature rise to the numerical solution of an equivalent thermal model. It was found that the accuracy of temperature measurement depends on thermosensor size, that is, the smaller TC, the more accurate the temperature measurement. SAR determined using TC with lead diameters of 25 and 75mm demonstrated 98.5% and 80.4% match with computed SAR, respectively. However, both TC provided the same temperature rises in long run (>10 min). FO probe failed to measure adequately local heating both for short and long exposures due to the relatively large size of the probe sensor (400mm) and time constant (0.6 s). Calculated SAR in the cell monolayer was almost two times lower than that in the surrounding liquid. It was shown that the impact of the cell monolayer on heating due to its small thickness (5 to 10mm) can be considered as negligible. Moreover, we demonstrated the possibility of accurate measurement of MMW-induced thermal pulses (up to 10 8C) using 25mm TC. AUTHORS' ABSTRACT: Leduc and Zhadobov 2017 (IEEE #6688): This paper reports the first thermal model and detailed analysis of the heating of an electromagnetic (EM) skin-equivalent phantom with a finite thickness at 60 GHz. The 1-D heat transfer equation is solved analytically for homogeneous phantoms with finite thicknesses. The temperature rise dynamics and heating distribution within the phantom are calculated for several phantom thicknesses (5, 10, and 15 mm) using measured thermal properties of the phantom. Analytical results are confirmed by numerical analysis based on EM-thermal cosimulations. Furthermore, the numerical model is validated by measurements using an experimental setup based on the high-resolution infrared thermometry. The impact of uncertainty of EM and the thermal parameters of the numerical model upon heat deposition is also studied. Our results reveal that, for short exposure durations (i.e., less than 1 min), the surface temperature is well described by the semi-infinite and finitethickness phantom models, whereas, for longer exposures (more than 1 min), finite-thickness models must be used to properly account for heating accumulation close to the phantom boundaries. While the reported results cannot be directly used for predicting temperature increase in skin, they are of importance for temperature-based dosimetric assessment in the millimeterwave band using currently available homogeneous phantoms. AUTHORS' ABSTRACT: Haas et al. 2017 (IEEE #6717): Several forthcoming wireless telecommunication systems will use electromagnetic frequencies at millimeter waves (MMWs), and technologies developed around the 60-GHz band will soon know a widespread distribution. Free nerve endings within the skin have been suggested to be the targets of MMW therapy which has been used in the former Soviet Union. So far, no studies have assessed the impact of MMW exposure on neuronal metabolism. Here, we investigated the effects of a 24-h MMW exposure at 60.4 GHz, with an incident power density (IPD) of 5 mW/cm², on the dopaminergic turnover of NGF-treated PC12 cells. After MMW exposure, both intracellular and extracellular contents of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were studied using high performance liquid chromatography. Impact of exposure on the dopamine transporter (DAT) expression was also assessed by immunocytochemistry. We analyzed the dopamine turnover by assessing the ratio of DOPAC to DA, and measuring DOPAC accumulation in the medium. Neither dopamine turnover nor DAT protein expression level were impacted by MMW exposure. However, extracellular accumulation of DOPAC was found to be slightly increased, but not significantly. This result was related to the thermal effect, and overall, no evidence of non-thermal effects of MMW exposure were observed on dopamine metabolism. |
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| Findings | No Effects | |
| Status | Completed With Publication | |
| Principal Investigator | Univ Rennes, France | |
| Funding Agency | France, National Research Agency (ANR) | |
| Country | FRANCE | |
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