Genotoxic and antigenotoxic properties of selenium compounds in the in vitro

Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid) by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 μM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN) in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated

La disfemia en el aula: propuesta de intervención desde una educación inclusiva

Entre los 2 y los 5 años de edad, los niños empiezan a constituir un lenguaje cada vez más elaborado. Este proceso en muchos niños supone la aparición de disfluencias normativas. Sin embargo, en algunos casos, estas alteraciones pueden perdurar y llegar a cronificarse como disfemia. A través de cuentos clásicos se presenta una propuesta de proyecto de intervención inclusiva para el segundo ciclo de educación infantil dentro de un aula ordinaria que orienta al docente y previene las manifestaciones tempranas de la tartamudez para evitar su cronificación y contribuye a mejorar las habilidades lingüísticas, emocionales el autoconcepto de todos y cada uno de los alumnos del grupo-clase. Además, se pone de relevancia tanto las actuaciones del maestro como las de la familia del alumno que presente alguna alteración en el habla en una edad normativa. La propuesta didáctica se agrupa en 5 bloques: relajación, emociones, valores, articulación y expresión oral que se refieren al trabajo en diferentes áreas como posibles causas de la disfemia, aunque su origen sea desconocido. En todas las sesiones se trabaja la narración de cuentos clásicos y se fomenta la expresión y escucha activa

Assessment of Okadaic Acid Effects on Cytotoxicity, DNA Damage and DNA Repair in Human Cells

This is a manuscript version of the article.[Abstract] Okadaic acid (OA) is a phycotoxin produced by several types of dinoflagellates causing diarrheic shellfish poisoning (DSP) in humans. Symptoms induced by DSP toxins are mainly gastrointestinal, but the intoxication does not appear to be fatal. Despite this, this toxin presents a potential threat to human health even at concentrations too low to induce acute toxicity, since previous animal studies have shown that OA has very potent tumour promoting activity. However, its concrete action mechanism has not been described yet and the results reported with regard to OA cytotoxicity and genotoxicity are often contradictory. In the present study, the genotoxic and cytotoxic effects of OA on three different types of human cells (peripheral blood leukocytes, HepG2 hepatoma cells, and SHSY5Y neuroblastoma cells) were evaluated. Cells were treated with a range of OA concentrations in the presence and absence of S9 fraction, and MTT test and Comet assay were performed in order to evaluate cytotoxicity and genotoxicity, respectively. The possible effects of OA on DNA repair were also studied by means of the DNA repair competence assay, using bleomycin as DNA damage inductor. Treatment with OA in absence of S9 fraction induced not statistically significant decrease in cell viability and significant increase in DNA damage in all cell types at the highest concentrations investigated. However, only SHSY5Y cells showed OA induced genotoxic and cytotoxic effects in presence of S9 fraction. Furthermore, we found that OA can induce modulations in DNA repair processes when exposure was performed prior to BLM treatment, in co-exposure, or during the subsequent DNA repair process.This work was funded by a grant from the Xunta de Galicia (INCITE08PXIB106155PR). V. Valdiglesias was supported by a fellowship from the University of A CoruñaGalicia. Xunta; INCITE08PXIB106155P

Genotoxicity and cytotoxicity of zinc oxide and titanium dioxide in HEp-2 cells.

yesAims: The rapidly growing industrial and medical use of nanomaterials, especially zinc oxide and titanium dioxide, has led to growing concerns about their toxicity. Accordingly, the intrinsic genotoxic and cytotoxic potential of these nanoparticles have been evaluated. Materials & methods: Using a HEp-2 cell line, cytotoxicity was tested along with mitochondrial activity and neutral red uptake assays. The genotoxic potential was determined using the Comet and the cytokinesis-blocked micronucleus assays. In addition,tyrosine phosphorylation events were investigated. Results & conclusion: We found concentration- and time-dependent cytotoxicity and an increase in DNA and cytogenetic damage with increasing nanoparticle concentrations. Mainly for zinc oxide, genotoxicity was clearly associated with an increase in tyrosine phosphorylation. Our results suggest that both types of nanoparticles can be genotoxic over a range of concentrations without being cytotoxic.Embargo ended 3/11/ 201

Induction of Oxidative DNA Damage by the Marine Toxin Okadaic Acid Depends on Human Cell Type

This is a manuscript versión of the article.[Abstract] The marine toxin okadaic acid (OA) is the main representative of diarrhoeic shellfish poisoning (DSP) toxins. Its ingestion induces nausea, vomiting, diarrhoea and abdominal ache. It has also been found to trigger cellular and molecular effects at low concentrations. Its mechanism of action has not been described yet. Results of a previous study showed that OA can induce cytotoxic and genotoxic effects, both directly and indirectly, and modulations in DNA repair processes in three different types of human cells (leukocytes, SHSY5Y neuroblastoma and HepG2 cells). These effects varied depending on the type of cell and the concentration employed (Valdiglesias et al., 2010). On that basis, the ability of OA to induce oxidative DNA damage on the same cell types was investigated in the present study. To this end, the antioxidant enzymes catalase and N-acetylcysteine, and the human DNA- glycosylase hOGG1 were used in combination with the alkaline Comet assay. The cells were treated with a range of OA concentrations (5–1000 nM) in the presence and absence of S9 fraction. The results of this study showed that OA induces oxidative DNA damage directly in leukocytes, directly and indirectly in SHSY5Y cells, while it does not induce oxidative DNA damage in HepG2 cells. Combining the outcomes of both studies, the data showed that OA induces both cytotoxicity and genotoxicity, including DNA strand breaks and oxidative DNA damage, in the cells evaluated. However, the extent of these effects are cell type dependent.This work was funded by a grant from the Xunta de Galicia (INCITE08PXIB106155PR). V. Valdiglesias was supported by a fellowship from the University of A CoruñaGalicia. Xunta; INCITE08PXIB106155P