Cuestiones de género: de la igualdad y la diferencia
A pesar de los importantes avances en cuanto a la participación de las mujeres en el desarrollo c... more A pesar de los importantes avances en cuanto a la participación de las mujeres en el desarrollo científico y tecnológico en nuestro país, persiste una clara infrarrepresentación femenina en las academias de ciencias e ingeniería. La brecha de género es también visible en los galardones otorgados por estas instituciones. En este trabajo se analiza la brecha de género en los premios otorgados por la Real Academia Galega de Ciencias (RAGC) en 30 de sus convocatorias en el periodo 2013-2021, enfocándonos en varios aspectos relevantes: la composición de los jurados, las candidaturas presentadas y las personas finalmente galardonadas. En la mayoría de los galardones analizados se pone de manifiesto un claro sesgo de género a favor de los varones que se va incrementando a medida que aumenta la cuantía del premio o la relevancia del galardón, con la consiguiente repercusión social en la valoración y visibilización del trabajo de las científicas.
Nanomaterials (NMs) are of significant relevance due to their unique physicochemical properties, ... more Nanomaterials (NMs) are of significant relevance due to their unique physicochemical properties, which have been extensively exploited for widespread applications in human healthcare and consumer goods, such as cosmetics and textiles [...]
DNA damage and repair activity are often assessed in blood samples from humans in different types... more DNA damage and repair activity are often assessed in blood samples from humans in different types of molecular epidemiology studies. However, it is not always feasible to analyse the samples on the day of collection without any type of storage. For instance, certain studies use repeated sampling of cells from the same subject or samples from different subjects collected at different time-points, and it is desirable to analyse all these samples in the same comet assay experiment. In addition, flawless comet assay analyses on frozen samples open up the possibility of using this technique on biobank material. In this article we discuss the use of cryopreserved peripheral blood mononuclear cells (PBMCs), buffy coat (BC) and whole blood (WB) for analysis of DNA damage and repair using the comet assay. The published literature and the authors’ experiences indicate that various types of blood samples can be cryopreserved with only a minor effect on the basal level of DNA damage. There is e...
Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multip... more Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ion...
Journal of Toxicology and Environmental Health, Part A, 2011
DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously... more DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously exposed to different chemical and physical genotoxic agents. To counteract the lesions induced by these agents, organisms have developed a number of highly conserved repair mechanisms involving numerous protein complexes grouped in several different repair pathways. The importance of studying the individual capacity to repair DNA damage lies in the observation that deficient repair mechanisms of the genome have been linked to the presence of large number of diseases and cancer, and alterations in these mechanisms may also alter the susceptibility of individuals exposed to a particular mutagen. This review focused on the current knowledge of different assays developed to evaluate DNA repair capacity (DRC). These assays, which are grouped into five major categories, have been successfully applied in (1) in vitro studies, (2) epidemiological studies in patients with cancer or other different pathologies, and (3) environmentally or occupationally exposed populations. Nevertheless, some of the limitations include high interlaboratory variability and difficulty to implement the assays on a large scale. The selection of an adequate DRC assay needs to be made on the basis of the objective raised for its application and taking into account a number of determining factors, namely, (1) speed and cost, (2) type of DNA repair to be evaluated, and (3) sample availability.
Okadaic acid (OA) is a marine toxin produced by dinoflagellate species which is frequently accumu... more Okadaic acid (OA) is a marine toxin produced by dinoflagellate species which is frequently accumulated in molluscs usual in the human diet. The exact action mechanism of OA has not been described yet and the results of most reported studies are often conflicting. The aim of this work was to evaluate the OA effects on morphology, cell cycle and apoptosis induction by means of light microscopy and flow cytometry, in three different types of human cells (leukocytes, HepG2 cells and SHSY5Y cells). Cells were treated with a range of OA concentrations in the presence and absence of S9 fraction. OA induced morphological changes in all the cell types studied, and cell cycle disruption only in leukocytes and neuronal cells. SHSY5Y cells were the most sensitive to OA assault. Results obtained in the presence and absence of metabolic activation were similar, suggesting that OA acts both directly and indirectly. Furthermore, OA was found to increase the subG(1) region in the flow cytometry cell cycle analysis, suggesting induction of apoptosis. These results were confirmed by the employment of specific methodologies for studying apoptosis such as caspase 3 activation and annexin V staining. Increases in the apoptosis rate were obtained in all the cells treated in the absence of S9 fraction, accompanied by increases in caspase 3 activation, suggesting that apoptosis induced by OA is a caspase 3-dependent process. Nevertheless, in the presence of S9 fraction no apoptosis was detected, indicating a metabolic detoxifying activity, although necrosis was observed in neuroblastoma cells.
Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a... more Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a variety of consumer products, including food industry in which they are employed as an additive. The potential toxic effects of these NPs on mammal cells have been extensively studied. However, studies regarding neurotoxicity and specific effects on neuronal systems are very scarce and, to our knowledge, no studies on human neuronal cells have been reported so far. Therefore, the main objective of this work was to investigate the effects of two types of TiO₂ NPs, with different crystalline structure, on human SHSY5Y neuronal cells. After NPs characterization, a battery of assays was performed to evaluate the viability, cytotoxicity, genotoxicity and oxidative damage in TiO₂ NP-exposed SHSY5Y cells. Results obtained showed that the behaviour of both types of NPs resulted quite comparable. They did not reduce the viability of neuronal cells but were effectively internalized by the cells and induced dose-dependent cell cycle alterations, apoptosis by intrinsic pathway, and genotoxicity not related with double strand break production. Furthermore, all these effects were not associated with oxidative damage production and, consequently, further investigations on the specific mechanisms underlying the effects observed in this study are required.
In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coas... more In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+)16(+)), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16(+)56(+) lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8(+), CD4(+)/CD8(+) ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.
Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly used nanomaterials in consumer ... more Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly used nanomaterials in consumer products and biomedical applications. As a result, human exposure to these NPs is highly frequent and they have become an issue of concern to public health. Although toxicity of ZnO NPs has been extensively studied and they have been shown to affect many different cell types and animal systems, there is a significant lack of toxicological data for ZnO NPs on the nervous system, especially for human neuronal cells and tissues. In this study, the cytotoxic and genotoxic effects of ZnO NPs on human SHSY5Y neuronal cells were investigated under different exposure conditions. Results obtained by flow cytometry showed that ZnO NPs do not enter the neuronal cells, but their presence in the medium induced cytotoxicity, including viability decrease, apoptosis and cell cycle alterations, and genotoxicity, including micronuclei production, H2AX phosphorylation and DNA damage, both primary and oxidative, on human neuronal cells in a dose- and time-dependent manner. Free Zn(2+) ions released from the ZnO NPs were not responsible for the viability decrease, but their role on other types of cell damage cannot be ruled out. The results obtained in this work contribute to increase the knowledge on the genotoxic and cytotoxic potential of ZnO NPs in general, and specifically on human neuronal cells, but further investigations are required to understand the action mechanism underlying the cytotoxic and genotoxic effects observed.
The marine toxin okadaic acid (OA) is the main representative of diarrhoeic shellfish poisoning (... more 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.
DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously... more DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously exposed to different chemical and physical genotoxic agents. To counteract the lesions induced by these agents, organisms have developed a number of highly conserved repair mechanisms involving numerous protein complexes grouped in several different repair pathways. The importance of studying the individual capacity to repair DNA damage lies in the observation that deficient repair mechanisms of the genome have been linked to the presence of large number of diseases and cancer, and alterations in these mechanisms may also alter the susceptibility of individuals exposed to a particular mutagen. This review focused on the current knowledge of different assays developed to evaluate DNA repair capacity (DRC). These assays, which are grouped into five major categories, have been successfully applied in (1) in vitro studies, (2) epidemiological studies in patients with cancer or other different pathologies, and (3) environmentally or occupationally exposed populations. Nevertheless, some of the limitations include high interlaboratory variability and difficulty to implement the assays on a large scale. The selection of an adequate DRC assay needs to be made on the basis of the objective raised for its application and taking into account a number of determining factors, namely, (1) speed and cost, (2) type of DNA repair to be evaluated, and (3) sample availability.
One of the most important groups of metabolic enzymesinvolved in the detoxification of a wide rang... more One of the most important groups of metabolic enzymesinvolved in the detoxification of a wide range of toxiccompounds is the cytochrome P450 (CYP) superfamily.This superfamily is subdivided into a number of familiesand subfamilies, based on nucleotide sequence homologywhere genes within a family have a minimum of 40% sequenceidentity [1]. They catalyse a large number of chemical reactionswith an almost unlimited number of biologically occurringand xenobiotic compounds and are preferentially expressedin liver, although some isozymes can be tissue-specific [2].Among this group of enzymes the isozyme CYP1B1 deservesspecial attention. CYP1B1 gene is located in chromosome2p22-p21 [3] and encodes a 543-amino acid protein. CYP1B1promoter contains a xenobiotic response element (XRE:5′-TNGCGTG-3′) and is regulated by aryl hydrocarbonreceptor [1]. This receptor belongs to the helix-loop-helixtranscription factors family and constitutes a cytosolicprotein that, after binding to some of its ligands, translocatesto the nucleus and dimerizes with a nuclear protein [4].This dimer interacts with the XRE and allows the complexto regulate the gene transcription [5]. Unlike CYP1A1, otherimportant gene of this family, the structure and function ofCYP1B1 promoter is similar to the constitutively expressedgenes [6], although it has been reported that its expressioncan also be induced by the binding of several substances asdioxins or polycyclic aromatic hydrocarbons to the arylhydrocarbon receptor [7].Attending to the fact that many carcinogenic agents mustbe bioactivated by means of phase I oxidative metabolismand that the CYP family is the predominant source of thismetabolic activity, its expression constitutes a determinanttoxicological factor [8]. Specifically, it has been shown that theCYP1B1 enzyme induces the metabolic activation of a widevariety of carcinogens as arylamines, nitroaromatic compoundsand polycyclic aromatic hydrocarbons [9]. Moreover, CYP1B1catalyses both the formation of certain pro-carcinogenpolycyclic aromatic hydrocarbons dihydrodiols and theiradditional oxidation to dihydrodiol epoxides, the ultimatecarcinogens [7], and is apparently more active than CYP1A1[10]. So, as in most cases metabolites resulting from its actionpossess more toxic characteristics than the original com-pounds, this metabolic pathway constitutes an activationprocess, and potential quantitative differences will be ofspecial relevance in the damage induced. In fact, CYP1B1is over-expressed in many tumours, and McFadyen andMurray [11] identified this enzyme as the main CYP presentin a wide range of human cancers of different histologicaltypes, being considered nowadays a neoplastic phenotypebiomarker.Several polymorphisms were identified in CYP1B1 gene;four of them are single nucleotide polymorphisms and giverise to amino acidic substitutions. CYP1B1*3 allele comesfrom a C-to-G transversion at position 1666 in exon 3(codon 432) generating an amino acid change from Leu toVal (NCBI database number rs1056836). In general, variantCYP1B1 isozymes are more active (2.4- to 3.4-fold) than thewild types [9,12]. Specifically, Li et al. [13] described a three-fold higher 4-hydroxylase activity for the CYP1B1*3 allele.On the other hand, Aklillu et al. [14] did not find differentialactivities between variants. Due to the fact that many workslink the presence of the variant allele of this gene to theoccurrence of a wide variety of cancers, the frequency ofthis polymorphism has been described in several studies inCaucasian populations (table 1), however, never in Spanishindividuals.In this study, we have analysed the frequency of CYP1B1codon 432 polymorphism in a population of 235 healthySpanish individuals (114 men and 121 women, mean age29.99 ± 11.09 years, range 17–59). DNA was extracted from300 µl of whole peripheral blood using Puregene™ DNAisolation kit (Gentra Systems, Minneapolis, MN, USA).
Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accum... more Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accumulated in several molluscs and other marine organisms and cause acute gastrointestinal symptoms after oral consumption by humans, called diarrheic shellfish poisoning. However other toxic effects beyond these gastrointestinal symptoms were also reported. Thus, OA was found to induce important chromosomal abnormalities and other genetic injuries that can lead to severe pathologies, including cancer. Furthermore, the relationship between OA and carcinogenic processes has been previously demonstrated in in vivo studies with rodents, and also suggested in human epidemiological studies. In this context, further research is required to better understand the underlying mechanisms of OA-related tumourigenesis. In a previous study, we identified 247 genes differentially expressed in SHSY5Y neuroblastoma cells exposed to 100nM OA at different times (3, 24 and 48h) by means of suppression subtractive hybridization. These genes were involved in relevant cell functions such as signal transduction, cell cycle, metabolism, and transcription and translation processes. However, due to the high potential percentage of false positives that may be obtained by this approach, results from SSH are recommended to be analyzed by an independent method. In the present study, we selected ten genes related to cancer initiation or progression, directly or indirectly, for further quantitative PCR analysis (ANAPC13, PTTG1, CALM2, CLU, HN1, MALAT1, MAPRE2, MLLT11, SGA-81M and TAX1BP1). Results obtained showed important alterations in the expression patterns of all the genes evaluated at one or more treatment times, providing, for the first time, a possible explanation at the molecular level of the potential relationship between the consumption of OA-contaminated shellfish and the incidence of different cancers in humans. Nevertheless, given the complexity of this process, more exhaustive studies are required before drawing any final conclusion.
Cuestiones de género: de la igualdad y la diferencia
A pesar de los importantes avances en cuanto a la participación de las mujeres en el desarrollo c... more A pesar de los importantes avances en cuanto a la participación de las mujeres en el desarrollo científico y tecnológico en nuestro país, persiste una clara infrarrepresentación femenina en las academias de ciencias e ingeniería. La brecha de género es también visible en los galardones otorgados por estas instituciones. En este trabajo se analiza la brecha de género en los premios otorgados por la Real Academia Galega de Ciencias (RAGC) en 30 de sus convocatorias en el periodo 2013-2021, enfocándonos en varios aspectos relevantes: la composición de los jurados, las candidaturas presentadas y las personas finalmente galardonadas. En la mayoría de los galardones analizados se pone de manifiesto un claro sesgo de género a favor de los varones que se va incrementando a medida que aumenta la cuantía del premio o la relevancia del galardón, con la consiguiente repercusión social en la valoración y visibilización del trabajo de las científicas.
Nanomaterials (NMs) are of significant relevance due to their unique physicochemical properties, ... more Nanomaterials (NMs) are of significant relevance due to their unique physicochemical properties, which have been extensively exploited for widespread applications in human healthcare and consumer goods, such as cosmetics and textiles [...]
DNA damage and repair activity are often assessed in blood samples from humans in different types... more DNA damage and repair activity are often assessed in blood samples from humans in different types of molecular epidemiology studies. However, it is not always feasible to analyse the samples on the day of collection without any type of storage. For instance, certain studies use repeated sampling of cells from the same subject or samples from different subjects collected at different time-points, and it is desirable to analyse all these samples in the same comet assay experiment. In addition, flawless comet assay analyses on frozen samples open up the possibility of using this technique on biobank material. In this article we discuss the use of cryopreserved peripheral blood mononuclear cells (PBMCs), buffy coat (BC) and whole blood (WB) for analysis of DNA damage and repair using the comet assay. The published literature and the authors’ experiences indicate that various types of blood samples can be cryopreserved with only a minor effect on the basal level of DNA damage. There is e...
Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multip... more Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ion...
Journal of Toxicology and Environmental Health, Part A, 2011
DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously... more DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously exposed to different chemical and physical genotoxic agents. To counteract the lesions induced by these agents, organisms have developed a number of highly conserved repair mechanisms involving numerous protein complexes grouped in several different repair pathways. The importance of studying the individual capacity to repair DNA damage lies in the observation that deficient repair mechanisms of the genome have been linked to the presence of large number of diseases and cancer, and alterations in these mechanisms may also alter the susceptibility of individuals exposed to a particular mutagen. This review focused on the current knowledge of different assays developed to evaluate DNA repair capacity (DRC). These assays, which are grouped into five major categories, have been successfully applied in (1) in vitro studies, (2) epidemiological studies in patients with cancer or other different pathologies, and (3) environmentally or occupationally exposed populations. Nevertheless, some of the limitations include high interlaboratory variability and difficulty to implement the assays on a large scale. The selection of an adequate DRC assay needs to be made on the basis of the objective raised for its application and taking into account a number of determining factors, namely, (1) speed and cost, (2) type of DNA repair to be evaluated, and (3) sample availability.
Okadaic acid (OA) is a marine toxin produced by dinoflagellate species which is frequently accumu... more Okadaic acid (OA) is a marine toxin produced by dinoflagellate species which is frequently accumulated in molluscs usual in the human diet. The exact action mechanism of OA has not been described yet and the results of most reported studies are often conflicting. The aim of this work was to evaluate the OA effects on morphology, cell cycle and apoptosis induction by means of light microscopy and flow cytometry, in three different types of human cells (leukocytes, HepG2 cells and SHSY5Y cells). Cells were treated with a range of OA concentrations in the presence and absence of S9 fraction. OA induced morphological changes in all the cell types studied, and cell cycle disruption only in leukocytes and neuronal cells. SHSY5Y cells were the most sensitive to OA assault. Results obtained in the presence and absence of metabolic activation were similar, suggesting that OA acts both directly and indirectly. Furthermore, OA was found to increase the subG(1) region in the flow cytometry cell cycle analysis, suggesting induction of apoptosis. These results were confirmed by the employment of specific methodologies for studying apoptosis such as caspase 3 activation and annexin V staining. Increases in the apoptosis rate were obtained in all the cells treated in the absence of S9 fraction, accompanied by increases in caspase 3 activation, suggesting that apoptosis induced by OA is a caspase 3-dependent process. Nevertheless, in the presence of S9 fraction no apoptosis was detected, indicating a metabolic detoxifying activity, although necrosis was observed in neuroblastoma cells.
Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a... more Titanium dioxide (TiO2) are among most frequently used nanoparticles (NPs). They are present in a variety of consumer products, including food industry in which they are employed as an additive. The potential toxic effects of these NPs on mammal cells have been extensively studied. However, studies regarding neurotoxicity and specific effects on neuronal systems are very scarce and, to our knowledge, no studies on human neuronal cells have been reported so far. Therefore, the main objective of this work was to investigate the effects of two types of TiO₂ NPs, with different crystalline structure, on human SHSY5Y neuronal cells. After NPs characterization, a battery of assays was performed to evaluate the viability, cytotoxicity, genotoxicity and oxidative damage in TiO₂ NP-exposed SHSY5Y cells. Results obtained showed that the behaviour of both types of NPs resulted quite comparable. They did not reduce the viability of neuronal cells but were effectively internalized by the cells and induced dose-dependent cell cycle alterations, apoptosis by intrinsic pathway, and genotoxicity not related with double strand break production. Furthermore, all these effects were not associated with oxidative damage production and, consequently, further investigations on the specific mechanisms underlying the effects observed in this study are required.
In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coas... more In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+)16(+)), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16(+)56(+) lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8(+), CD4(+)/CD8(+) ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.
Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly used nanomaterials in consumer ... more Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly used nanomaterials in consumer products and biomedical applications. As a result, human exposure to these NPs is highly frequent and they have become an issue of concern to public health. Although toxicity of ZnO NPs has been extensively studied and they have been shown to affect many different cell types and animal systems, there is a significant lack of toxicological data for ZnO NPs on the nervous system, especially for human neuronal cells and tissues. In this study, the cytotoxic and genotoxic effects of ZnO NPs on human SHSY5Y neuronal cells were investigated under different exposure conditions. Results obtained by flow cytometry showed that ZnO NPs do not enter the neuronal cells, but their presence in the medium induced cytotoxicity, including viability decrease, apoptosis and cell cycle alterations, and genotoxicity, including micronuclei production, H2AX phosphorylation and DNA damage, both primary and oxidative, on human neuronal cells in a dose- and time-dependent manner. Free Zn(2+) ions released from the ZnO NPs were not responsible for the viability decrease, but their role on other types of cell damage cannot be ruled out. The results obtained in this work contribute to increase the knowledge on the genotoxic and cytotoxic potential of ZnO NPs in general, and specifically on human neuronal cells, but further investigations are required to understand the action mechanism underlying the cytotoxic and genotoxic effects observed.
The marine toxin okadaic acid (OA) is the main representative of diarrhoeic shellfish poisoning (... more 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.
DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously... more DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously exposed to different chemical and physical genotoxic agents. To counteract the lesions induced by these agents, organisms have developed a number of highly conserved repair mechanisms involving numerous protein complexes grouped in several different repair pathways. The importance of studying the individual capacity to repair DNA damage lies in the observation that deficient repair mechanisms of the genome have been linked to the presence of large number of diseases and cancer, and alterations in these mechanisms may also alter the susceptibility of individuals exposed to a particular mutagen. This review focused on the current knowledge of different assays developed to evaluate DNA repair capacity (DRC). These assays, which are grouped into five major categories, have been successfully applied in (1) in vitro studies, (2) epidemiological studies in patients with cancer or other different pathologies, and (3) environmentally or occupationally exposed populations. Nevertheless, some of the limitations include high interlaboratory variability and difficulty to implement the assays on a large scale. The selection of an adequate DRC assay needs to be made on the basis of the objective raised for its application and taking into account a number of determining factors, namely, (1) speed and cost, (2) type of DNA repair to be evaluated, and (3) sample availability.
One of the most important groups of metabolic enzymesinvolved in the detoxification of a wide rang... more One of the most important groups of metabolic enzymesinvolved in the detoxification of a wide range of toxiccompounds is the cytochrome P450 (CYP) superfamily.This superfamily is subdivided into a number of familiesand subfamilies, based on nucleotide sequence homologywhere genes within a family have a minimum of 40% sequenceidentity [1]. They catalyse a large number of chemical reactionswith an almost unlimited number of biologically occurringand xenobiotic compounds and are preferentially expressedin liver, although some isozymes can be tissue-specific [2].Among this group of enzymes the isozyme CYP1B1 deservesspecial attention. CYP1B1 gene is located in chromosome2p22-p21 [3] and encodes a 543-amino acid protein. CYP1B1promoter contains a xenobiotic response element (XRE:5′-TNGCGTG-3′) and is regulated by aryl hydrocarbonreceptor [1]. This receptor belongs to the helix-loop-helixtranscription factors family and constitutes a cytosolicprotein that, after binding to some of its ligands, translocatesto the nucleus and dimerizes with a nuclear protein [4].This dimer interacts with the XRE and allows the complexto regulate the gene transcription [5]. Unlike CYP1A1, otherimportant gene of this family, the structure and function ofCYP1B1 promoter is similar to the constitutively expressedgenes [6], although it has been reported that its expressioncan also be induced by the binding of several substances asdioxins or polycyclic aromatic hydrocarbons to the arylhydrocarbon receptor [7].Attending to the fact that many carcinogenic agents mustbe bioactivated by means of phase I oxidative metabolismand that the CYP family is the predominant source of thismetabolic activity, its expression constitutes a determinanttoxicological factor [8]. Specifically, it has been shown that theCYP1B1 enzyme induces the metabolic activation of a widevariety of carcinogens as arylamines, nitroaromatic compoundsand polycyclic aromatic hydrocarbons [9]. Moreover, CYP1B1catalyses both the formation of certain pro-carcinogenpolycyclic aromatic hydrocarbons dihydrodiols and theiradditional oxidation to dihydrodiol epoxides, the ultimatecarcinogens [7], and is apparently more active than CYP1A1[10]. So, as in most cases metabolites resulting from its actionpossess more toxic characteristics than the original com-pounds, this metabolic pathway constitutes an activationprocess, and potential quantitative differences will be ofspecial relevance in the damage induced. In fact, CYP1B1is over-expressed in many tumours, and McFadyen andMurray [11] identified this enzyme as the main CYP presentin a wide range of human cancers of different histologicaltypes, being considered nowadays a neoplastic phenotypebiomarker.Several polymorphisms were identified in CYP1B1 gene;four of them are single nucleotide polymorphisms and giverise to amino acidic substitutions. CYP1B1*3 allele comesfrom a C-to-G transversion at position 1666 in exon 3(codon 432) generating an amino acid change from Leu toVal (NCBI database number rs1056836). In general, variantCYP1B1 isozymes are more active (2.4- to 3.4-fold) than thewild types [9,12]. Specifically, Li et al. [13] described a three-fold higher 4-hydroxylase activity for the CYP1B1*3 allele.On the other hand, Aklillu et al. [14] did not find differentialactivities between variants. Due to the fact that many workslink the presence of the variant allele of this gene to theoccurrence of a wide variety of cancers, the frequency ofthis polymorphism has been described in several studies inCaucasian populations (table 1), however, never in Spanishindividuals.In this study, we have analysed the frequency of CYP1B1codon 432 polymorphism in a population of 235 healthySpanish individuals (114 men and 121 women, mean age29.99 ± 11.09 years, range 17–59). DNA was extracted from300 µl of whole peripheral blood using Puregene™ DNAisolation kit (Gentra Systems, Minneapolis, MN, USA).
Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accum... more Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accumulated in several molluscs and other marine organisms and cause acute gastrointestinal symptoms after oral consumption by humans, called diarrheic shellfish poisoning. However other toxic effects beyond these gastrointestinal symptoms were also reported. Thus, OA was found to induce important chromosomal abnormalities and other genetic injuries that can lead to severe pathologies, including cancer. Furthermore, the relationship between OA and carcinogenic processes has been previously demonstrated in in vivo studies with rodents, and also suggested in human epidemiological studies. In this context, further research is required to better understand the underlying mechanisms of OA-related tumourigenesis. In a previous study, we identified 247 genes differentially expressed in SHSY5Y neuroblastoma cells exposed to 100nM OA at different times (3, 24 and 48h) by means of suppression subtractive hybridization. These genes were involved in relevant cell functions such as signal transduction, cell cycle, metabolism, and transcription and translation processes. However, due to the high potential percentage of false positives that may be obtained by this approach, results from SSH are recommended to be analyzed by an independent method. In the present study, we selected ten genes related to cancer initiation or progression, directly or indirectly, for further quantitative PCR analysis (ANAPC13, PTTG1, CALM2, CLU, HN1, MALAT1, MAPRE2, MLLT11, SGA-81M and TAX1BP1). Results obtained showed important alterations in the expression patterns of all the genes evaluated at one or more treatment times, providing, for the first time, a possible explanation at the molecular level of the potential relationship between the consumption of OA-contaminated shellfish and the incidence of different cancers in humans. Nevertheless, given the complexity of this process, more exhaustive studies are required before drawing any final conclusion.
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Papers by Vanessa Valdiglesias