Sylvie Bourthoumieu

Apoptosis is Induced by Radiofrequency Fields through the Caspase-Independent Mitochondrial Pathway in Cortical Neurons

Abstract Joubert, V., Bourthoumieu, S., Leveque, P. and Yardin, C. Apoptosis is Induced by Radiofrequency Fields through the Caspase-Independent Mitochondrial Pathway in Cortical Neurons. Radiat. Res. 169, 38–45 (2008). In the present study, we investigated whether continuous-wave (CW) radiofrequency (RF) fields induce neuron apoptosis in vitro. Rat primary neuronal cultures were exposed to a CW 900 MHz RF field with a specific absorption rate (SAR) of 2 W/kg for 24 h. During exposure, an increase of 2°C was measured in the medium; control experiments with neurons exposed to 39°C were then performed. Apoptosis was assessed by condensation of nuclei with 4′,6-diamino-2-phenylindole (DAPI) staining observed with an epifluorescence microscope and fragmentation of DNA with TdT-mediated dUTP nick-end labeling (TUNEL) analyzed by flow cytometry. A statistically significant difference in the rate of apoptosis was found in the RF-field-exposed neurons compared to the sham-, 37°C- and 39°C-exposed neurons either 0 or 24 h after exposure using both methods. To assess whether the observed apoptosis was caspase-dependent or -independent, assays measuring caspase 3 activity and apoptosis-inducing factor (AIF) labeling were performed. No increase in the caspase 3 activity was found, whereas the percentage of AIF-positive nuclei in RF-field-exposed neurons was increased by three- to sevenfold compared to other conditions. Our results show that, under the experimental conditions used, exposure of primary rat neurons to CW RF fields may induce a caspase-independent pathway to apoptosis that involves AIF.

Microwave exposure of neuronal cells in vitro : Study of apoptosis

Purpose:The aim of this study was to investigate microwave (MW) effects on neuronal apoptosis in vitro. Materials and methods:Human neuroblastoma cells SH-SY5Y were exposed to a 900 MHz global system for mobile communication (GSM) or continuous-wave (CW) radiofrequency fields for 24 h in a wire-patch cell. The specific absorption rates (SAR) used were 2 W/kg for CW and 0.25 W/kg average for GSM. During CW exposure, an increase of 2°C was measured, and controls with cells exposed to 39°C were then performed. Apoptosis rate was assessed immediately or 24 h after exposure using three methods: (i) 4′,6-diamino-2-phenylindole (DAPI) staining; (ii) flow cytometry using double staining with TdT-mediated dUTP nick-end labeling (TUNEL) and propidium iodide (PI); and (iii) measurement of caspase-3 activity by fluorimetry. Results:No statistically significant difference in the apoptosis rate was observed between sham and 24 h MW-exposed cells, either GSM-900 at an average SAR of 0.25 W/kg, or CW 900 MHz at a SAR of 2 W/kg, either 0 h or 24 h post-exposure. Furthermore, for CW-exposure, apoptosis rates were comparable between sham-, CW-, 37°C- and 39°C-exposed cells. All three methods used to assess apoptosis were concordant. Conclusion:These results showed that, under the conditions of the present experiment, MW-exposure (either CW or GSM-900) does not significantly increase the apoptosis rate in the human neuroblastoma cell line SH-SY5Y.

Monozygotic twins concordant for blood karyotype, but phenotypically discordant: a case of "mosaic chimerism".

We report on 23 years old discordant monozygotic (MZ) twins, one with minor anomalies and mental delay, the other one being normal. Both had 46,XX,dup(11)(p12p15)/46,XX mosaicism in blood, with a similar proportion of abnormal cells (respectively, 16% and 17%). However, interphase fluorescence in situ hybridization (FISH) analysis performed on buccal smear and urinary sediment using specific probes located at the duplicated region showed that mosaicism was only present in the abnormal twin, with 68% abnormal cells. We hypothesize that the postzygotic chromosomal rearrangement may have occurred early in one embryo after the twinning event, and the blood mosaicism observed in both twins would have resulted from blood exchanges via placental anastomoses. This hypothesis of chimerism is strongly supported by twin‐to‐twin transfusion syndrome observed during fetal life of our twins. This case and those previously reported lead us to suggest that blood is particularly unsuitable for cytogenetic investigations of twins.

Dose dependent expression of HDAC4 causes variable expressivity in a novel inherited case of brachydactyly mental retardation syndrome

Histone deacetylase 4 (HDAC4) serves important roles in multiple human systems, including neurological, cardiac, and skeletal functions. Mutation or deletion of HDAC4 causes brachydactyly mental retardation syndrome (BDMR), a disorder that includes intellectual disability, behavioral abnormalities, autism spectrum disorder, and craniofacial and skeletal anomalies, including brachydactyly type E. We present a case of familial BDMR, including a parent with mild symptoms of the disorder and a child exhibiting a more severe phenotype. Cytogenetic testing showed a cryptic balanced translocation in the mother that resulted in a 2q37.1 monosomy and a 10q26.1 trisomy in the son. Gene expression analyses demonstrated 67% HDAC4 expression in the mother and 23% HDAC4 expression in the son relative to normal controls, lending evidence to the hypothesis that HDAC4 modulates severity of this disorder in a dosage‐dependent manner.

Cytogenetic Studies in Human Cells Exposed In Vitro to GSM-900 MHz Radiofrequency Radiation Using R-Banded Karyotyping

Abstract It is important to determine the possible effects of exposure to radiofrequency (RF) radiation on the genetic material of cells since damage to the DNA of somatic cells may be linked to cancer development or cell death and damage to germ cells may lead to genetic damage in next and subsequent generations. The objective of this study was to investigate whether exposure to radiofrequency radiation similar to that emitted by mobile phones of second-generation standard Global System for Mobile Communication (GSM) induces genotoxic effects in cultured human cells. The cytogenetic effects of GSM-900 MHz (GSM-900) RF radiation were investigated using R-banded karyotyping after in vitro exposure of human cells (amniotic cells) for 24 h. The average specific absorption rate (SAR) was 0.25 W/kg. The exposures were carried out in wire-patch cells (WPCs) under strictly controlled conditions of temperature. The genotoxic effect was assessed immediately or 24 h after exposure using four different samples. One hundred metaphase cells were analyzed per assay. Positive controls were provided by using bleomycin. We found no direct cytogenetic effects of GSM-900 either 0 h or 24 h after exposure. To the best of our knowledge, our work is the first to study genotoxicity using complete R-banded karyotyping, which allows visualizing all the chromosomal rearrangements, either numerical or structural.

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.

Study of p53 expression and post-transcriptional modifications after GSM-900 radiofrequency exposure of human amniotic cells†

The potential effects of radiofrequency (RF) exposure on the genetic material of cells are very important to determine since genome instability of somatic cells may be linked to cancer development. In response to genetic damage, the p53 protein is activated and can induce cell cycle arrest allowing more time for DNA repair or elimination of damaged cells through apoptosis. The objective of this study was to investigate whether the exposure to RF electromagnetic fields, similar to those emitted by mobile phones of the second generation standard, Global System for Mobile Communications (GSM), may induce expression of the p53 protein and its activation by post-translational modifications in cultured human cells. The potential induction of p53 expression and activation by GSM-900 was investigated after in vitro exposure of human amniotic cells for 24 h to average specific absorption rates (SARs) of 0.25, 1, 2, and 4 W/kg in the temperature range of 36.3-39.7 °C. The exposures were carried out using a wire-patch cell (WPC) under strictly controlled conditions of temperature. Expression and activation of p53 by phosphorylation at serine 15 and 37 were studied using Western blot assay immediately after three independent exposures of cell cultures provided from three different donors. Bleomycin-exposed cells were used as a positive control. According to our results, no significant changes in the expression and activation of the p53 protein by phosphorylation at serine 15 and 37 were found following exposure to GSM-900 for 24 h at average SARs up to 4 W/kg in human embryonic cells.

Chimerism in twins : Caution is needed in interpretation of karyotypes

Interpretation of cytogenetic analysis in twins needs particular care and attention, as shown by the case of Johannsen et al. [2003], in which a child’s ovarieswereunnecessarily removedbasedon misleading cytogenetic information. Briefly, the authors reported a case of suspected monozygotic (MZ) twins with discrepant sex phenotype at birth, whereas the amniocentesis and the ultrasound examination had pointed towards male sex of both twins. In fact, at birth one twin presented as a normal boy, and the other twin as a phenotypically normal female with 46,XY blood karyotype. Gonadal dysgenesis was diagnosed, and gonadectomy was performed in the phenotypically female twin to prevent the development of a gonadoblastoma. However, the histology of the gonads revealed normal infantile ovaries, and chromosomal analysis of fibroblasts from a skin biopsy demonstrated a 46,XX karyotype. This newborn was in fact a 46,XX female with a chimeric 46,XY blood cell line due to intrauterine transfusion from her twin brother.

aCGH may be useful in Case of Dominant Disorders Known to be Caused by Gene Mutations: Two Case Reports

We describe two cases where clinical diagnoses were carried out (Rett syndrome-like and Nicolaides-Baraitser syndrome) with no identified mutation respectively in the CDKL5 and the SMARCA2 genes. Conversely a chromosomal microdeletion with contiguous deletion of a part of these two genes was found by arrayCGH in each corresponding case. The aim of this report is then to highlight the possible implication of chromosomal microdeletions with contiguous gene deletions in dominant pathologies where no mutation is found in the causative gene.

Neuroprotective effect of erythropoietin against pressure ulcer in a mouse model of small fiber neuropathy.

An increased risk of skin pressure ulcers (PUs) is common in patients with sensory neuropathies, including those caused by diabetes mellitus. Recombinant human erythropoietin (rhEPO) has been shown to protect the skin against PUs developed in animal models of long-term diabetes. The aim of this work was to determine whether rhEPO could prevent PU formation in a mouse model of drug-inducedSFN. Functional SFN was induced by systemic injection of resiniferatoxin (RTX, 50 µg/kg, i.p.). RhEPO (3000 UI/kg, i.p.) was given the day before RTX injection and then every other day. Seven days after RTX administration, PUs were induced by applying two magnetic plates on the dorsal skin. RTX-treated mice expressed thermal and mechanical hypoalgesia and showed calcitonin gene-related peptide (CGRP) and substance P (SP) depletion without nerve degeneration or vascular dysfunction. RTX mice developed significantly larger stage 2 PUs than Vehicle mice. RhEPO prevented thermal and mechanical hypoalgesia and neuropeptide depletion in small nerve fibers. RhEPO increased hematocrit and altered endothelium-dependent vasodilatation without any effect on PU formation in Vehicle mice. The characteristics of PUs in RTX mice treated with rhEPO and Vehicle mice were found similar. In conclusion, RTX appeared to increased PU development through depletion of CGRP and SP in small nerve fibers, whereas systemic rhEPO treatment had beneficial effect on peptidergic nerve fibers and restored skin protective capacities against ischemic pressure. Our findings support the evaluation of rhEPO and/or its non-hematopoietic analogs in preventing to prevent PUs in patients with SFN.