Verónica Labrador

Universidad Autónoma de Madrid, Madrid, Madrid, Spain

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Publications (13)28.9 Total impact

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    ABSTRACT: During the last twenty years, interest in light microscopy and imaging techniques has grown in various fields, such as molecular and cellular biology, developmental biology, and neurobiology. In addition, the number of scientific articles and journals using these techniques is rapidly increasing. Nowadays, most research institutions require sophisticated microscopy systems to cover their investigation demands. In general, such instruments are too expensive and complex to be purchased and managed by a single laboratory or research group, so they have to be shared with other groups and supervised by specialized personnel. This is the reason why microscopy and imaging facilities are becoming so important at research institutions nowadays. In this unit, we have gathered and presented a number of issues and considerations from our own experience that we hope will be helpful when planning or setting up a new facility.
    Current protocols in cytometry / editorial board, J. Paul Robinson, managing editor ... [et al.] 07/2011; Chapter 12:Unit 12.22.
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    ABSTRACT: Propyl p-hydroxybenzoate, commonly referred to as propylparaben, is the most frequently used preservative to inhibit microbial growth and extend shelf life of a range of consumer products. The objective of this study was to provide further insight into the toxicological profile of this compound, because of the current discrepancy in the literature with regard to the safety of parabens. The Vero cell line, derived from the kidney of the green monkey, was selected to evaluate the adverse effects of propylparaben by use of a set of mechanistically relevant endpoints for detecting cytotoxicity and genotoxic activities. Our results demonstrate that exposure to the compound for 24h causes changes in cell-proliferation rates rather than in cell viability. A significant and dose-dependent decline in the percentage of mitotic cells was observed at the lowest concentration tested, mainly due to cell-cycle arrest at the G0/G1 phase. Immunodetection techniques revealed that induction of DNA double-strand breaks and oxidative damage underlies the cytostatic effect observed in treated Vero cells. Additional studies are in progress to extend these findings, which define a novel mode of action of propylparaben in cultured mammalian cells.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 09/2010; 702(1):86-91. · 3.90 Impact Factor
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    ABSTRACT: Propyl p-hydroxybenzoate, commonly referred to as propylparaben, is the most frequently used preservative to inhibit microbial growth and extend shelf life of a range of consumer products. The objective of this study was to provide further insight into the toxicological profile of this compound, because of the current discrepancy in the literature with regard to parabens safety. The Vero cell line, derived from the kidney of green monkey, was selected to evaluate the adverse effects of propylparaben using a set of mechanistically relevant endpoints for detecting cytotoxicity and genotoxic activity. Our results demonstrate that exposure to the compound for 24 h causes changes on cell proliferation rates rather than on cell viability. A significant and dose-dependent decline in the percentage of mitotic cells was observed from the lowest concentration tested, mainly due to cell cycle arrest at the G0/G1 phase. Immunodetection techniques revealed that induction of DNA double-strand breaks and oxidative damage underlie the cytostatic effect observed in Vero-treated cells. Additional studies are in progress to extend these findings that define a novel mode of action of propylparaben in cultured mammalian cells.
    XII International Congress of Toxicology, Barcelona, Spain; 07/2010
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    ABSTRACT: The development of in vitro cytotoxicity assays is currently essential to evaluate the potential human and environmental health risks associated to chemical exposure, and to limit animal experimentation whenever possible. However, cytotoxicity assessments have been limited by their inability to measure morphological alterations, that can reveal subtle but extremely vital aspects of cell injury. This report presents a simple and cost-effective multi-assay approach, that includes biochemical and microscopical endpoints, to assess the underlying mechanisms involved in the toxic action of chemical compounds.
    Microscopy: science, technology, applications and education, Edited by A Méndez-Vilas, J Díaz, 01/2010: pages 2145-2153; Formatex., ISBN: 9788461461912
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    ABSTRACT: We reported recently that the anticonvulsant drug carbamazepine, at supratherapeutic concentrations, exerts antiproliferative effects in mammalian Vero cells, but the underlying mechanism has not been elucidated. This motivates us to examine rigorously whether growth arrest was associated with structural changes in cellular organization during mitosis. In the present work, we found that exposure of the cells to carbamazepine led to an increase in mitotic index, mainly due to the sustained block at the metaphase/anaphase boundary, with the consequent inhibition of cell proliferation. Indirect immunofluorescence, using antibodies directed against spindle apparatus proteins, revealed that mitotic arrest was associated with formation of monopolar spindles, caused by impairment of centrosome separation. The final consequence of the spindle defects induced by carbamazepine, depended on the duration of cell cycle arrest. Following the time course of accumulation of metaphase and apoptotic cells during carbamazepine treatments, we observed a causative relationship between mitotic arrest and induction of cell death. Conversely, cells released from the block of metaphase by removal of the drug, continued to progress through mitosis and resume normal proliferation. Our results show that carbamazepine shares a common antiproliferative mechanism with spindle-targeted drugs and contribute to a better understanding of the cytostatic activity previously described in Vero cells. Additional studies are in progress to extend these initial findings that define a novel mode of action of carbamazepine in cultured mammalian cells.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 02/2008; 637(1-2):124-33. · 3.90 Impact Factor
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    ABSTRACT: Adoption of the European law on chemical compounds (REACH) demands new experimental procedures on toxicology. Special encourage has been set onto the development of in vitro methods, so as to reduce animal testing to the minimum. Despite its intrinsic constraints, in vitro cell cultures appears a suitable approach for acute toxicity studies. To provide a reliable experimental method for the toxicological evaluation of chemicals, three different established cell lines (Vero monkey kidney fibroblasts, 3T3 mouse embryonic fibroblasts and HeLa epithelial tumour cells) were selected to develop a tier-wise battery of endpoints. In a first stage, studies on proliferation and viability were performed allowing us to select the most sensitive cell line for further experiments. Morphology studies at cellular and subcellular levels complete this first phase, after which the toxicological profile for the tested compounds can be established, as well as a preliminary mechanism of toxicity. Next, a second set of specific techniques will be accomplished depending on previous results, in order to determine the precise mode of action of the chemical compounds at cellular level. On the last stage of our proposal, a precise cellular response to the toxic agent, as well as the cellular targets, will be defined. Altogether, we will be able to highlight the most effective parameters among those used. The validity of the model is demonstrated with two known environmental pollutants, pentachlorophenol (PCP, CAS No. 87-86-5) and butylated hydroxianisole (BHA, CAS No. 25013-16-5), showing novel interesting results in both cases.
    44th Congress of the European Societies of Toxicology, Amsterdam, The Netherlands; 10/2007
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    ABSTRACT: El interés por conocer los potenciales efectos tóxicos que los productos de aseo personal ejercen sobre la salud humana y el medio ambiente ha crecido mucho en los últimos años. Al mismo tiempo, han surgido dudas razonables acerca del valor de predicción que tienen los resultados obtenidos en la evaluación individual de compuestos químicos, a la hora de definir el potencial tóxico de una mezcla. En este contexto, nuestro trabajo tiene por objeto conocer los efectos tóxicos y mutagénicos que presentan diferentes mezclas binarias de butilhidroxianisol (BHA) y propilparaben (pPHB), dos sustancias que frecuentemente son empleadas de forma simultánea en cosméticos, y cuyos efectos carcinogénicos son controvertidos. Para ello hemos empleado un conjunto de biomarcadores y dos modelos in vitro: células de mamífero en cultivo (Vero) y Salmonella typhimurium. El estudio mediante citometría de flujo de la proliferación de células Vero mostró un efecto citostático en todas las condiciones ensayadas. Para los compuestos individuales, se observó un incremento del número de células bloqueadas en la fase G0/G1. Sin embargo, aunque las mezclas binarias también mostraron diversas alteraciones sobre el ciclo celular, el principal efecto observado fue el incremento del número de células poliploides. Por el contrario, el ensayo de mutagenicidad en Salmonella thyphimurium se mostró insensible a los efectos de las diferentes mezclas. A la luz de estos resultados concluimos que las mezclas BHA- pPHB inducen alteraciones inesperadas sobre el control del ciclo celular de las células Vero, si atendemos a los resultados obtenidos con los compuestos por separado.
    XVII Congreso Español de Toxicología, Santiago de Compostela; 09/2007
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    ABSTRACT: Butylated hydroxyanisole (BHA) is perhaps the most extensively used synthetic antioxidant in the food and cosmetic industry, although considerable controversy exists in the literature regarding the safety of this compound. Most in vitro studies describing the effects of BHA have been performed in cancer cells, but it is unclear whether normal cells are equally susceptible to BHA exposure. The present study investigate the toxic potential of BHA in mammalian cells, using biochemical and morphological parameters, which reveal interference with structures essential for cell survival, proliferation and/or function. Cell growth inhibition was assessed by using colorimetric assays, whereas cellular alterations after BHA exposure, were evaluated using conventional light and fluorescence microscopy. Low doses of BHA exerted a significant cytotoxic effect, associated with loss of mitochondrial function. As the concentration of BHA was increased, morphological alterations in critical subcellular targets such as lysosomes, mitochondria and actin cytoskeleton, were observed. In parallel, BHA induced an irreversible loss of cell proliferative capacity, preceding apoptosis induction. Thus, the dose-dependent activity of BHA on Vero cells appears to be cytotoxic as well as cytostatic. Our observations, although simplified with respect to the in vivo situations, allowed the assessment of the specific damage at the cellular level, and provide some clue about the effects of BHA in non-tumoral mammalian cells.
    Cell Biology and Toxicology 06/2007; 23(3):189-99. · 2.34 Impact Factor
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    ABSTRACT: Butylated hydroxyanisole (BHA) is perhaps the most extensively used synthetic antioxidant in the food and cosmetic industry, although considerable controversy exists in the literature regarding the safety of this compound. Most in vitro studies describing the effects of BHA have been performed in cancer cells, but it is unclear whether normal cells are equally susceptible to BHA exposure. The present study investigate the toxic potential of BHA in mammalian cells, using biochemical and morphological parameters, which reveal interference with structures essential for cell survival, proliferation and/or function. Cell growth inhibition was assessed by using colorimetric assays, whereas cellular alterations after BHA exposure, were evaluated using conventional light and fluorescence microscopy. Low doses of BHA exerted a significant cytotoxic effect, associated with loss of mitochondrial function. As the concentration of BHA was increased, morphological alterations in critical subcellular targets such as lysosomes, mitochondria and actin cytoskeleton, were observed. In parallel, BHA induced an irreversible loss of cell proliferative capacity, preceding apoptosis induction. Thus, the dose-dependent activity of BHA on Vero cells appears to be cytotoxic as well as cytostatic. Our observations, although simplified with respect to the in vivo situations, allowed the assessment of the specific damage at the cellular level, and provide some clue about the effects of BHA in non-tumoral mammalian cells.
    Cell Biology and Toxicology 06/2007; 23(3):189-199. · 2.34 Impact Factor
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    ABSTRACT: The effects of pentachlorophenol have been studied on diverse biological systems both in vivo and in vitro, however the cellular basis of the pronounced cytotoxicity of this organochlorine compound is poorly understood. In this work, morphological and biochemical analyses were carried out to identify the primary targets of pentachlorophenol toxicity in mammalian cells. Our results show that pentachlorophenol is a very potent cytotoxic drug that displays an unusual and interesting mode of action in Vero cells. Although this compound is a powerful uncoupler of oxidative phosphorylation, we present the novel finding that lysosome destabilization is an early cytotoxic response that precedes the mitochondrial dysfunction. In addition, soon after exposure to moderate doses of pentachlorophenol, a significant number of cells initiate an apoptotic death process identified by the condensed and fragmented state of their nuclei. These results demonstrate that there are multiple potential targets of PCP-induced toxicity in mammalian cells, and the need to develop further experimental studies for the risk assessment of this environmental pollutant.
    Toxicology 06/2005; 210(1):37-44. · 4.02 Impact Factor
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    ABSTRACT: The occurrence and fate of additives in the aquatic environment is an emerging issue in environmental chemistry. This paper describes the ecotoxicological effects of the commonly used additive butylated hydroxyanisole (BHA) using a test battery, comprising of several different organisms and in vitro test systems, representing a proportion of the different trophic levels. The most sensitive system to BHA was the inhibition of bioluminescence in Vibrio fischeri bacteria, which resulted in an acute low observed adverse effect concentration (LOAEC) of 0.28 microM. The next most sensitive system was the immobilization of the cladoceran Daphnia magna followed by: the inhibition of the growth of the unicellular alga Chlorella vulgaris; the endpoints evaluated in Vero (mammalian) cells (total protein content, LDH activity, neutral red uptake and MTT metabolization), mitotic index and root growth inhibition in the terrestrial plant Allium cepa, and finally, the endpoints used on the RTG-2 salmonid fish cell line (neutral red uptake, total protein content, MTS metabolization, lactate dehydrogenase leakage and activity, and glucose-6-phosphate dehydrogenase activity). Morphological alterations in RTG-2 cells were also assessed and these included loss of cells, induction of cellular pleomorphism, hydropic degeneration and induction of apoptosis at high concentrations. The results from this study also indicated that micronuclei were not induced in A.cepa exposed to BHA. The differences in sensitivity for the diverse systems that were used (EC50 ranged from 1.2 to >500 microM) suggest the importance for a test battery approach in the evaluation of the ecological consequences of chemicals. According to the results, the levels of BHA reported in industrial wastewater would elicit adverse effects in the environment. This, coupled with its potential to bioaccumulate, makes BHA a pollutant of concern not only for acute exposures, but also for the long-term.
    Aquatic Toxicology 01/2005; 71(2):183-92. · 3.51 Impact Factor
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    ABSTRACT: In the present work, we have continued our studies on harmine phototoxicity in human tumour cells. The toxicity of harmine in the dark was analysed by a quantitative neutral red uptake assay, and subcellular sensitive targets following harmine photosensitization were de fi ned by electron microscopic analysis of HeLa cells. The results obtained indicated that this compound shows a clear dose-dependent cytotoxic effect in the dark. The combined treatment with suitable doses of harmine and UV radiation was very effective at an early stage, although maximal cell killing appeared 48 h after photodynamic activation. Ultrastructural examination of HeLa cells immediately after the photodynamic treatment revealed lysosomal destabilization and profound cytoplasmic vacuolization that evolved to cytolysis, which is typical of necrotic cell death. It is concluded that harmine could be a valuable photosensitizer whose biological applications merit further evaluation.
    Journal of Applied Toxicology 05/2004; 24(3):197-201. · 2.60 Impact Factor