Treatment with 3-Aminobenzamide Negates the Radiofrequency-Induced Adaptive Response in Two Cell Models

In previous investigations, we demonstrated that pre-exposure of different cell cultures to radiofrequency fields can reduce the damage induced by genotoxic agents, an effect resembling the so-called adaptive response. In this study, we pre-exposed human peripheral blood lymphocytes and Chinese hamster lung fibroblast cell line to 1950 MHz, UMTS (Universal Mobile Telecommunication System) signal, for 20 h, and then treated cultures with Mitomycin-C. After confirming the induction of an adaptive response in terms of the reduction of micronuclei formation, we observed that such a response was negated by treatments with 3-aminobenzamide. Since 3-aminobenzamide is an inhibitor of poly (ADP-ribose) polymerase enzyme, which is involved in DNA repair, these results support the possible involvement of DNA repair mechanisms in radiofrequency-induced adaptive response.

Cell electrotransfection and viability dependence on electrotransfection and viability dependence on electoporation medium

Electroporation is a physical method that uses electric fields to increase membrane permeability. The method is widely used for intracellular drug and gene delivery. In this study we aimed to investigate the importance of the medium for efficiency of cell electrotransfection and viability following the application of electric field pulses. The experiments were performed using 2 different cell lines: Chinese hamster ovary (CHO) and Chinese hamster lung fibroblast (DC-3F) and 2 different electroporation media: SMEM (medium conductivity equal to 1.3 S/m) and laboratory-made low-conductivity (0.1 S/m) electroporation (EP) medium. Cells suspended in these media were supplemented with plasmid (10 µg/ml) encoding luciferase and then were treated with 1, 5, or 10 high-voltage (1200 V/cm, 100 µs, at 1 Hz) pulses. Transfection efficiency was determined by luciferase activity 24 h after cell treatment, while cell viability was determined by clonogenic assay. Results showed significant differences between cell lines and used electroporation media. CHO transfection was higher when electroporation was performed in low conductivity EP medium. Low transfection efficiency in SMEM medium resulted from low viability. In contrast, transfection efficiency of DC-3F cells was higher in SMEM. Possible mechanisms governing these differences are discussed.

Safety Assessment of a Wheat Bran Extract Containing Arabinoxylan-Oligosaccharides: Mutagenicity, Clastogenicity, and 90-Day Rat-Feeding Studies

Wheat bran extract (WBE) is a food-grade preparation that is highly enriched in arabinoxylan-oligosaccharides. As part of the safety evaluation of WBE, its genotoxic potential was assessed in a bacterial reverse mutagenicity assay (Ames test) and a chromosome aberration assay on Chinese hamster lung fibroblast cells. These in vitro genotoxicity assays showed no evidence of mutagenic or clastogenic activity with WBE. The safety of WBE was furthermore evaluated in a subchronic toxicity study on rats that were fed a semisynthetic diet (AIN 93G) containing 0.3%, 1.5%, or 7.5% WBE for 13 weeks, corresponding to an average intake of 0.2, 0.9, and 4.4 g/kg body weight (bw) per day, with control groups receiving the unsupplemented AIN 93G, AIN 93G with 7.5% inulin, or AIN 93G with 7.5% wheat bran. Based on this rat-feeding study, the no-observed-adverse-effect level (NOAEL) for WBE was determined as 4.4 g/kg (bw)/d, the highest dose tested.