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To modernize genotoxicity assessment and reduce reliance on experimental animals, new approach methodologies (NAMs) that provide human-relevant dose-response data are needed. Two transcriptomic biomarkers, GENOMARK and TGx-DDI, have shown a high classification accuracy for genotoxicity. As these biomarkers were extracted from different training sets, we investigated whether combining the two biomarkers in a human-derived metabolically competent cell line (i.e., HepaRG) provides complementary information for the classification of genotoxic hazard identification and potency ranking. First, the applicability of GENOMARK to TempO-Seq, a high-throughput transcriptomic technology, was evaluated. HepaRG cells were exposed for 72 h to increasing concentrations of 10 chemicals (i.e., eight known in vivo genotoxicants and two in vivo nongenotoxicants). Gene expression data were generated using the TempO-Seq technology. We found a prediction performance of 100%, confirming the applicability of GENOMARK to TempO-Seq. Classification using TGx-DDI was then compared to GENOMARK. For the chemicals identified as genotoxic, benchmark concentration modeling was conducted to perform potency ranking. The high concordance observed for both hazard classification and potency ranking by GENOMARK and TGx-DDI highlights the value of integrating these NAMs in a weight of evidence evaluation of genotoxicity.
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Perfilación de la Expresión Génica , Transcriptoma , Animales , Humanos , Perfilación de la Expresión Génica/métodos , Biomarcadores , Línea Celular , Daño del ADNRESUMEN
Fungi of the genus Alternaria are ubiquitous plant pathogens and saprophytes which are able to grow under varying temperature and moisture conditions as well as on a large range of substrates. A spectrum of structurally diverse secondary metabolites with toxic potential has been identified, but occurrence and relative proportion of the different metabolites in complex mixtures depend on strain, substrate, and growth conditions. This review compiles the available knowledge on hazard identification and characterization of Alternaria toxins. Alternariol (AOH), its monomethylether AME and the perylene quinones altertoxin I (ATX-I), ATX-II, ATX-III, alterperylenol (ALP), and stemphyltoxin III (STTX-III) showed in vitro genotoxic and mutagenic properties. Of all identified Alternaria toxins, the epoxide-bearing analogs ATX-II, ATX-III, and STTX-III show the highest cytotoxic, genotoxic, and mutagenic potential in vitro. Under hormone-sensitive conditions, AOH and AME act as moderate xenoestrogens, but in silico modeling predicts further Alternaria toxins as potential estrogenic factors. Recent studies indicate also an immunosuppressive role of AOH and ATX-II; however, no data are available for the majority of Alternaria toxins. Overall, hazard characterization of Alternaria toxins focused, so far, primarily on the commercially available dibenzo-α-pyrones AOH and AME and tenuazonic acid (TeA). Limited data sets are available for altersetin (ALS), altenuene (ALT), and tentoxin (TEN). The occurrence and toxicological relevance of perylene quinone-based Alternaria toxins still remain to be fully elucidated. We identified data gaps on hazard identification and characterization crucial to improve risk assessment of Alternaria mycotoxins for consumers and occupationally exposed workers.
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Micotoxinas , Perileno , Humanos , Alternaria/metabolismo , Micotoxinas/toxicidad , Micotoxinas/análisis , Mutágenos/toxicidad , Mutágenos/metabolismo , Lactonas/toxicidad , Lactonas/metabolismo , Medición de Riesgo , Contaminación de Alimentos/análisisRESUMEN
Human cytogenetic biomonitoring (HCB) has long been used to evaluate the potential effects of work environments on the DNA integrity of workers. However, HCB studies on the genotoxic effects of occupational exposure to extremely low-frequency electromagnetic fields (ELF-MFs) were limited by the quality of the exposure assessment. More specifically, concerns were raised regarding the method of exposure assessment, the selection of exposure metrics, and the definition of exposure group. In this study, genotoxic effects of occupational exposure to ELF-MFs were assessed on peripheral blood lymphocytes of 88 workers from the electrical sector using the comet and cytokinesis-block micronucleus assay, considering workers' actual exposure over three consecutive days. Different methods were applied to define exposure groups. Overall, the summarized ELF-MF data indicated a low exposure level in the whole study population. It also showed that relying solely on job titles might misclassify 12 workers into exposure groups. We proposed combining hierarchical agglomerative clustering on personal exposure data and job titles to define exposure groups. The final results showed that occupational MF exposure did not significantly induce more genetic damage. Other factors such as age or past smoking rather than ELF-MF exposure could affect the cytogenetic test outcomes.
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Monitoreo Biológico , Pruebas de Micronúcleos , Exposición Profesional , Humanos , Exposición Profesional/efectos adversos , Exposición Profesional/análisis , Masculino , Adulto , Persona de Mediana Edad , Femenino , Campos Magnéticos/efectos adversos , Campos Electromagnéticos/efectos adversos , Linfocitos/efectos de la radiación , Ensayo Cometa , Análisis Citogenético , Daño del ADNRESUMEN
Previous studies have shown that differences in experimental design factors may alter the potency of genotoxic compounds in in vitro genotoxicity tests. Most of these studies used traditional statistical methods based on the lowest observed genotoxic effect levels, whereas more appropriate methods, such as the benchmark dose (BMD) approach, are now available to compare genotoxic potencies under different test conditions. We therefore investigated the influence of two parameters, i.e. cell type and exposure duration, on the potencies of two known genotoxicants [aflatoxin B1 and ethyl methanesulfonate (EMS)] in the in vitro micronucleus (MN) assay and comet assay (CA). Both compounds were tested in the two assays using two cell types (i.e. CHO-K1 and TK6 cells). To evaluate the effect of exposure duration, the genotoxicity of EMS was assessed after 3 and 24 h of exposure. Results were analyzed using the BMD covariate approach, also referred to as BMD potency ranking, and the outcome was compared with that of more traditional statistical methods based on lowest observed genotoxic effect levels. When comparing the in vitro MN results obtained in both cell lines with the BMD covariate approach, a difference in potency was detected only when EMS exposures were conducted for 24 h, with TK6 cells being more sensitive. No difference was observed in the potency of both EMS and aflatoxin B1 in the in vitro CA using both cell lines. In contrast, EMS was more potent after 24 h exposure compared with a 3 h exposure under all tested conditions, i.e. in the in vitro MN assay and CA in both cell lines. Importantly, for several of the investigated factors, the BMD covariate method could not be used to confirm the differences in potencies detected with the traditional statistical methods, thus highlighting the need to evaluate the impact of experimental design factors with adequate approaches.
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Aflatoxina B1 , Proyectos de Investigación , Aflatoxina B1/toxicidad , Técnicas In VitroRESUMEN
Although the value of the regulatory accepted batteries for in vitro genotoxicity testing is recognized, they result in a high number of false positives. This has a major impact on society and industries developing novel compounds for pharmaceutical, chemical, and consumer products, as afflicted compounds have to be (prematurely) abandoned or further tested on animals. Using the metabolically competent human HepaRG™ cell line and toxicogenomics approaches, we have developed an upgraded, innovative, and proprietary gene classifier. This gene classifier is based on transcriptomic changes induced by 12 genotoxic and 12 non-genotoxic reference compounds tested at sub-cytotoxic concentrations, i.e., IC10 concentrations as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The resulting gene classifier was translated into an easy-to-handle qPCR array that, as shown by pathway analysis, covers several different cellular processes related to genotoxicity. To further assess the predictivity of the tool, a set of 5 known positive and 5 known negative test compounds for genotoxicity was evaluated. In addition, 2 compounds with debatable genotoxicity data were tested to explore how the qPCR array would classify these. With an accuracy of 100%, when equivocal results were considered positive, the results showed that combining HepaRG™ cells with a genotoxin-specific qPCR array can improve (geno)toxicological hazard assessment. In addition, the developed qPCR array was able to provide additional information on compounds for which so far debatable genotoxicity data are available. The results indicate that the new in vitro tool can improve human safety assessment of chemicals in general by basing predictions on mechanistic toxicogenomics information.
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Daño del ADN , Pruebas de Mutagenicidad/métodos , Mutágenos/toxicidad , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Línea Celular , Humanos , ToxicogenéticaRESUMEN
Prior to the downstream development of chemical substances, including pharmaceuticals and cosmetics, their influence on the genetic apparatus has to be tested. Several in vitro and in vivo assays have been developed to test for genotoxicity. In a first tier, a battery of two to three in vitro tests is recommended to cover mutagenicity, clastogenicity and aneugenicity as main endpoints. This regulatory in vitro test battery is known to have a high sensitivity, which is at the expense of the specificity. The high number of false positive in vitro results leads to excessive in vivo follow-up studies. In the case of cosmetics it may even induce the ban of the particular compound since in Europe the use of experimental animals is no longer allowed for cosmetics. In this article, an alternative approach to derisk a misleading positive Ames test is explored. Hereto we first tested the performance of five existing computational tools to predict the potential mutagenicity of a data set of 132 cosmetic compounds with a known genotoxicity profile. Furthermore, we present, as a proof-of-principle, a strategy in which a combination of computational tools and mechanistic information derived from in vitro transcriptomics analyses is used to derisk a misleading positive Ames test result. Our data shows that this strategy may represent a valuable tool in a weight-of-evidence approach to further evaluate a positive outcome in an Ames test.
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Simulación por Computador , Perfilación de la Expresión Génica/métodos , Pruebas de Mutagenicidad/métodos , Biología Computacional/métodos , Cosméticos , Exactitud de los Datos , Sensibilidad y EspecificidadRESUMEN
Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world. The vast majority of CRC cases have been linked to environmental causes rather than to heritable genetic changes. Over the last decades, epidemiological evidence linking the consumption of red and, more convincingly, of processed red meat to CRC has accumulated. In parallel, hypotheses on carcinogenic mechanisms underlying an association between CRC and the intake of red and processed red meat have been proposed and investigated in biological studies. The hypotheses that have received most attention until now include (1) the presence of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, two groups of compounds recognized as carcinogenic, (2) the enhancing effect of (nitrosyl)heme on the formation of carcinogenic N-nitroso compounds and lipid peroxidation. However, none of these hypotheses completely explains the link between red and processed red meat intake and the CRC risk. Consequently, scientists have proposed additional mechanisms or refined their hypotheses. This review first briefly summarizes the development of CRC followed by an in-depth overview and critical discussion of the different potential carcinogenic mechanisms underlying the increased CRC risk associated with the consumption of red and processed red meat.
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Neoplasias Colorrectales/epidemiología , Productos de la Carne/efectos adversos , Carne Roja/efectos adversos , Animales , Carcinógenos/análisis , Carcinógenos/toxicidad , Dieta , Modelos Animales de Enfermedad , Manipulación de Alimentos , Compuestos Heterocíclicos/análisis , Compuestos Heterocíclicos/toxicidad , Humanos , Peroxidación de Lípido , Hidrocarburos Policíclicos Aromáticos/análisis , Hidrocarburos Policíclicos Aromáticos/toxicidad , Factores de RiesgoRESUMEN
Food contact materials (FCM) are estimated to be the largest source of food contamination. Apart from plastics, the most commonly used FCM are made of printed paper and board. Unlike their plastic counterparts, these are not covered by a specific European regulation. Several contamination issues have raised concerns towards potential adverse health effects caused by exposure to substances migrating from printed paper and board FCM. In the current study, an inventory combining the substances which may be used in printed paper and board FCM, was created. More than 6000 unique compounds were identified, the majority (77%) considered non-evaluated in terms of potential toxicity. Based on a preliminary study of their physicochemical properties, it is estimated that most of the non-evaluated single substances have the potential to migrate into the food and become bioavailable after oral intake. Almost all are included in the FACET tool, indicating that their use in primary food packaging has been confirmed by industry. Importantly, 19 substances are also present in one of the lists with substances of concern compiled by the European Chemicals Agency (ECHA). To ensure consumer safety, the actual use of these substances in printed paper and board FCM should be investigated urgently.
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Seguridad de Productos para el Consumidor , Contaminación de Alimentos , Embalaje de Alimentos/métodos , Sustancias Peligrosas/efectos adversos , Tinta , Papel , Impresión , Lista de Verificación , Humanos , Medición de Riesgo , Pruebas de ToxicidadRESUMEN
An increasing body of evidence identifies pollutant exposure as a risk factor for cardiovascular disease (CVD), while CVD incidence rises steadily with the aging population. Although numerous experimental studies are now available, the mechanisms through which lifetime exposure to environmental pollutants can result in CVD are not fully understood. To comprehensively describe and understand the pathways through which pollutant exposure leads to cardiotoxicity, a systematic mapping review of the available toxicological evidence is needed. This protocol outlines a step-by-step framework for conducting this review. Using the National Toxicology Program (NTP) Health Assessment and Translation (HAT) approach for conducting toxicological systematic reviews, we selected 362 out of 8111 in vitro (17%), in vivo (67%), and combined (16%) studies for 129 potential cardiotoxic environmental pollutants, including heavy metals (29%), air pollutants (16%), pesticides (27%), and other chemicals (28%). The internal validity of included studies is being assessed with HAT and SYRCLE Risk of Bias tools. Tabular templates are being used to extract key study elements regarding study setup, methodology, techniques, and (qualitative and quantitative) outcomes. Subsequent synthesis will consist of an explorative meta-analysis of possible pollutant-related cardiotoxicity. Evidence maps and interactive knowledge graphs will illustrate evidence streams, cardiotoxic effects and associated quality of evidence, helping researchers and regulators to efficiently identify pollutants of interest. The evidence will be integrated in novel Adverse Outcome Pathways to facilitate regulatory acceptance of non-animal methods for cardiotoxicity testing. The current article describes the progress of the steps made in the systematic mapping review process.
Heart disease is a leading global cause of death. Recent research indicates that certain environmental chemicals can worsen heart problems. We're conducting a rigorous review of scientific studies to understand how these chemicals affect the heart. This will inform policymakers and promote non-animal testing methods for cardiotoxicity by providing a clear overview of the toxicological evidence. We have reviewed over 8,000 articles and focused on 362 studies about 129 chemicals, including heavy metals, air pollutants and pesticides, and their effects on the heart. The current manuscript describes the used methods and steps made in this process. The outcome of our systematic review of these 362 articles will be a comprehensive database that will aid the development of alternative testing methods for cardiotoxicity.
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Contaminantes Atmosféricos , Contaminantes Ambientales , Anciano , Humanos , Cardiotoxicidad , Informe de Investigación , Factores de Riesgo , Revisiones Sistemáticas como AsuntoRESUMEN
There is growing evidence indicating the substantial contribution of man-made products to an increase in the risk of diseases of civilization. In this article, the Belgian Scientific Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) Committee gives a critical view on the working of REACH. The current regulatory framework needs to further evolve taking into account data generated using modern science and technology. There is a need for improved assessment process not only before but also after entering the market. Objectivity, transparency, and the follow-up after market access can be optimized. Additionally, no guidance documents exist for regulation of mixture effects. Further, the lengthiness before regulatory action is a big concern. Decision-making often takes several years leading to uncertainties for both producers and end users. A first proposed improvement is the implementation of independent toxicity testing, to assure objectivity, transparency, and check and improve compliance. A "no data, no market" principle could prevent access of hazardous chemicals to the market. Additionally, the introduction of novel testing could improve information on endpoints such as endocrine disrupting abilities, neurotoxicity, and immunotoxicity. An adapted regulatory framework that integrates data from different sources and comparing the outputs with estimates of exposure is required. Fast toxicology battery testing and toxicokinetic testing could improve speed of decision-making. Hereby, several improvements have been proposed that could improve the current REACH legislation.
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Pruebas de Toxicidad , Humanos , Medición de Riesgo , Sustancias Peligrosas/toxicidad , Bélgica , Animales , Exposición a Riesgos Ambientales/legislación & jurisprudencia , Exposición a Riesgos Ambientales/efectos adversosRESUMEN
We recently discovered that sphaeropsidin A (SphA), a fungal metabolite from Diplodia cupressi, overcomes apoptosis resistance in cancer cells by inducing cellular shrinkage by impairing regulatory volume increase. Previously, we prepared a pyrene-conjugated derivative of SphA by a cross-metathesis reaction involving the phytotoxin's C15,C16-alkene. This derivative's evaluation in a cancer cell panel revealed a significant increase in potency, with the IC50 values 5-10× lower than those displayed by the original natural product. Herein, we describe the preparation and anticancer evaluation of fifteen novel C15,C16-alkene cross-metathesis analogues in which the pyrene moiety was replaced with other aromatic or non-aromatic hydrophobic groups. The idea for this replacement was to prepare a family of compounds that would not be predicted to be mutagenic compared with the original pyrene analogue. We predict several of our new compounds to be non-mutagenic, while retaining the high potency of the original pyrene-containing analogues. Examples of these potential lead compounds included those containing pentamethylphenyl and triphenylethylene pendant groups. As an additional feature of the current investigation, we prepared several deuterated pyrene-containing compounds to overcome intellectual property issues associated with non-patentability of the original pyrene derivative.
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The adverse outcome pathway (AOP) framework plays a crucial role in the paradigm shift of toxicity testing towards the development and use of new approach methodologies. AOPs developed for chemicals are in theory applicable to nanomaterials (NMs). However, only initial efforts have been made to integrate information on NM-induced toxicity into existing AOPs. In a previous study, we identified AOPs in the AOP-Wiki associated with the molecular initiating events (MIEs) and key events (KEs) reported for NMs in scientific literature. In a next step, we analyzed these AOPs and found that mitochondrial toxicity plays a significant role in several of them at the molecular and cellular levels. In this study, we aimed to generate hypothesis-based AOPs related to NM-induced mitochondrial toxicity. This was achieved by integrating knowledge on NM-induced mitochondrial toxicity into all existing AOPs in the AOP-Wiki, which already includes mitochondrial toxicity as a MIE/KE. Several AOPs in the AOP-Wiki related to the lung, liver, cardiovascular and nervous system, with extensively defined KEs and key event relationships (KERs), could be utilized to develop AOPs that are relevant for NMs. However, the majority of the studies included in our literature review were of poor quality, particularly in reporting NM physicochemical characteristics, and NM-relevant mitochondrial MIEs were rarely reported. This study highlights the potential role of NM-induced mitochondrial toxicity in human-relevant adverse outcomes and identifies useful AOPs in the AOP-Wiki for the development of AOPs for NMs.
This article investigates commonalities in the toxicity pathways of chemicals and nanomaterials. Nanomaterials have been found to affect the function of mitochondria, the powerhouses within every human cell. Mitochondrial dysfunction may cause harmful effects such as cellular damage and inflammation. By linking these findings to existing adverse outcome pathways for chemicals, the research provides valuable insights for assessing the risks associated with nanomaterial exposure. This work is crucial for understanding the potential health implications of nanomaterials and can contribute to informed decision-making in regulatory and risk assessment processes without the use of animals.
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Rutas de Resultados Adversos , Enfermedades Mitocondriales , Humanos , Hígado , Pruebas de Toxicidad , Medición de Riesgo/métodosRESUMEN
Transcriptomics-based biomarkers are promising new approach methodologies (NAMs) to identify molecular events underlying the genotoxic mode of action of chemicals. Previously, we developed the GENOMARK biomarker, consisting of 84 genes selected based on whole genomics DNA microarray profiles of 24 (non-)genotoxic reference chemicals covering different modes of action in metabolically competent human HepaRG™ cells. In the present study, new prediction models for genotoxicity were developed based on an extended reference dataset of 38 chemicals including existing as well as newly generated gene expression data. Both unsupervised and supervised machine learning algorithms were used, but as unsupervised machine learning did not clearly distinguish between groups, the performance of two supervised machine learning algorithms, i.e., support vector machine (SVM) and random forest (RF), was evaluated. More specifically, the predictive accuracy was compared, the sensitivity to outliers for one or more biomarker genes was assessed, and the prediction performance for 10 misleading positive chemicals exposed at their IC10 concentration was determined. In addition, the applicability of both prediction models on a publicly available gene expression dataset, generated with RNA-sequencing, was investigated. Overall, the RF and SVM models were complementary in their classification of chemicals for genotoxicity. To facilitate data analysis, an online application was developed, combining the outcomes of both prediction models. This research demonstrates that the combination of gene expression data with supervised machine learning algorithms can contribute to the ongoing paradigm shift towards a more human-relevant in vitro genotoxicity testing strategy without the use of experimental animals.
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Algoritmos , Perfilación de la Expresión Génica , Animales , Humanos , Biomarcadores , Perfilación de la Expresión Génica/métodos , Aprendizaje Automático Supervisado , Daño del ADNRESUMEN
Until today, it remains controversial whether long-term exposure to extremely low-frequency magnetic fields (ELF-MF) below the legislative exposure limits could result in adverse human health effects. In the present study, the effects of long-term in vitro MF exposure on three different study endpoints (cell viability, genetic damage, and sensitivity to damage induced by known mutagens) were investigated in the human B lymphoblastoid (TK6) cell line. Cells were exposed to 50 Hz MF at three selected magnetic flux densities (i.e., 10, 100, and 500 µT) for different exposure periods ranging from 96h up to 6 weeks. Cell viability following MF exposure was assessed using the ATP-based cell viability assay. Effects of MF exposure on cell genetic damage and cell sensitivity to mutagen-induced damage were evaluated using the in vitro alkaline comet assay and the in vitro cytokinesis block micronucleus assay. The results showed that long-term exposure up to 96h to 50 Hz MF at all tested flux densities could significantly increase TK6 cell viability. In contrast, long-term MF exposure did not affect cell genetic damage, and long-term pre-exposure to MF did not change cell sensitivity to damage induced by known mutagens. At certain time points, statistically significant difference in genotoxicity test results were observed between the MF-exposed cells and the control cells. However, these observations could not be confirmed in the repeat experiments, indicating that they are probably not biologically significant.
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By applying "New Approach Methodologies (NAMs)" based on innovative technologies such as computer modeling, high throughput testing, omics, and sophisticated cell cultures, the use of experimental animals in the life sciences can be reduced or sometimes even completely avoided. Stimulating NAMs may benefit from a bottom-up approach, i.e., local initiatives mapping the available NAMs and promoting their use. An example of such an initiative in Belgium is the RE-Place project, which collects the available NAMs in one central database, and links this knowledge with the names of experts and research centers. To this extent, a template was created to collect the information of interest in a fast and consistent manner. Based on this template, a web-based application was developed to facilitate the entry of information, which was evaluated in a pilot study by experts in the field of NAMs. After integration of their feedback, a revised version of the RE-Place online tool was launched to the public. Aspects such as user-friendliness, quality of submitted information, protection of personal data and Intellectual Property (IP) rights were all considered in the development process. Hurdles like incentives for collaboration were also taken into account. Information submitted with the online tool is directly integrated in the RE-Place open access database. By consulting the database, scientists from various disciplines can easily identify the different types of NAMs and the experts using them in Belgium. As such, the RE-Place database contributes to building trust in the use of NAMs and stimulating their use and regulatory uptake.
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Due to the link with serious adverse health effects, genotoxicity is an important toxicological endpoint in each regulatory setting with respect to human health, including for pharmaceuticals. To this extent, a compound potential to induce gene mutations as well as chromosome damage needs to be addressed. For chromosome damage, i.e., the induction of structural or numerical chromosome aberrations, several in vitro and in vivo test methods are available. In order to rapidly collect toxicological data without the need for test material, several in silico tools for chromosome damage have been developed over the last years. In this chapter, a battery of freely available in silico chromosome damage prediction tools for chromosome damage is applied on a dataset of pharmaceuticals. Examples of the different outcomes obtained with the in silico battery are provided and briefly discussed. Furthermore, results for coumarin are presented in more detail as a case study. Overall, it can be concluded that although they are in general less developed than those for mutagenicity, in silico tools for chromosome damage can provide valuable information, especially when combined in a battery.
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Cromosomas , Mutágenos , Aberraciones Cromosómicas , Daño del ADN , Humanos , Pruebas de Mutagenicidad , Mutágenos/química , Mutágenos/toxicidad , MutaciónRESUMEN
Several studies have revealed that manipulation of the renin angiotensin system results in reduced progression of nigrostriatal damage in different animal models of Parkinson's disease. In the present work, the effect of daily treatment of rats with the angiotensin II (Ang II) type 1 (AT(1) ) receptor antagonist candesartan (3 mg/kg per day, s.c.) initiated 7 days before the intrastriatal injection of 6-hydroxydopamine (6-OHDA) was investigated by means of tyrosine hydroxylase-positive cell counts in the substantia nigra, and dopamine and 3,4-dihydroxyphenylacetic acid measurements in the striatum. In this experimental set-up, candesartan protected dopaminergic neurons of the nigrostriatal tract against the neurotoxin-induced cell death. However, the beneficial effects of AT(1) receptor blockade were not confirmed when treatment was started 24 h after the lesion, suggesting that candesartan interferes with the early events of the 6-OHDA-induced cell death. Stimulation of the AT(1) receptor with Ang II increased the formation of hydroxyl radicals in the striatum of intact rats as measured by the in vivo microdialysis salicylate trapping technique. This Ang II-induced production of reactive oxygen species was suppressed by candesartan perfusion. Furthermore, the Ang II-induced production of reactive oxygen species was nicotinamide adenine dinucleotide phosphate - oxidase and protein kinase C dependent as it could be blocked in the presence of apocynin, an nicotinamide adenine dinucleotide phosphate - oxidase inhibitor, and chelerythrine, an inhibitor of protein kinase C. Together, these data further support the hypothesis that Ang II might contribute in an early stage to the neurotoxicity of 6-OHDA by reinforcing the cascade of oxidative stress.
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Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Bencimidazoles/farmacología , Neuronas Dopaminérgicas/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Oxidopamina/farmacología , Tetrazoles/farmacología , Animales , Compuestos de Bifenilo , Recuento de Células , Muerte Celular/efectos de los fármacos , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Cuerpo Estriado/patología , Dopamina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/patología , Masculino , Microdiálisis , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Wistar , Sustancia Negra/efectos de los fármacos , Sustancia Negra/metabolismo , Sustancia Negra/patologíaRESUMEN
Recently collected dietary exposure data on mineral oil saturated (MOSH) and aromatic (MOAH) hydrocarbons were used to evaluate the risks associated with exposure to mineral oil through food for the Belgian population. For MOSH, the no observed adverse effect level (NOAEL) value of 19 mg kg-1 bw day-1 based on the hepatic inflammation-associated granulomas found in a 90-day oral study in F-344 rats was used as point of departure (PoD). Due to existing toxicological uncertainties, the margin of exposure (MOE) approach was applied. In all investigated scenarios, the MOE values were well above 100, indicating that there is no direct health concern related to MOSH exposure for the Belgian population. Nevertheless, more appropriate risk assessment approaches for MOSH based on adequate PoD are needed. For dietary exposure to MOAH, which are potentially genotoxic and carcinogenic, no MOE values could be calculated due to the lack of adequate dose-response carcinogenicity data. In two investigated worst-case scenarios, a health concern related to MOAH exposure could not be excluded, highlighting that more data are needed to perform an adequate risk assessment. The possibility to use in vitro bioassays to collect such additional toxicological information for MOAH present in food samples was also investigated.