Assessment of Developmental Delay in the Zebrafish embryo Teratogenicity Assay

In this study we analyzed some aspects of the assessment of developmental delay in the zebrafish embryotoxicity/teratogenicity test and explored the suitability of acetylcholinesterase (AChE) activity as a biochemical marker and as a higher throughput alternative to morphological endpoints such as head-trunk angle, tail length and morphological score. Embryos were exposed from 4 to 52 h post-fertilization (hpf) to a selection of known embryotoxic/teratogen compounds (valproic acid, retinoic acid, caffeine, sodium salicylate, glucose, hydroxyurea, methoxyacetic acid, boric acid and paraoxon-methyl) over a concentration range. They were evaluated for AChE activity, head-trunk angle, tail length and several qualitative parameters integrated in a morphological score. In general, the different patterns of the concentration-response curves allowed distinguishing between chemicals that produced growth retardation (valproic and methoxyacetic acid) and chemicals that produced non-growth-delay related malformations. An acceptable correlation between the morphological score, AChE activity and head-trunk angle as markers of developmental delay was observed, being AChE activity particularly sensitive to detect delay in the absence of malformations

Zebrafish as a model for developmental toxicity assessment

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/67430The zebrafish embryo has emerged as promising alternative model for traditional in vivo developmental toxicological screening due to their advantageous characteristics as their small size and transparency. In this paper, we reviewed the applicability of the zebrafish embryo model in some relevant areas to human t oxicology as developmental toxicity, cardiovascular toxicity and neurotoxicity (behavioral assessment). Despite the promising results, further optimization and testing of more substances as well as a harmonized methodology is needed to streamline the metho ds and make the assay conducive to medium - throughput

Cardiovascular effects of PCB 126 (3,3',4,4',5-pentachlorobiphenyl) in zebrafish embryos and impact of co-exposure to redox modulating chemicals

The developing cardiovascular system of zebrafish is a sensitive target for many environmental pollutants, including dioxin-like compounds and pesticides. Some polychlorinated biphenyls (PCBs) can compromise the cardiovascular endothelial function by activating oxidative stress-sensitive signaling pathways. Therefore, we exposed zebrafish embryos to PCB126 or to several redox-modulating chemicals to study their ability to modulate the dysmorphogenesis produced by PCB126. PCB126 produced a concentration-dependent induction of pericardial edema and circulatory failure, and a concentration-dependent reduction of cardiac output and body length at 80 hours post fertilization (hpf). Among several modulators tested, the effects of PCB126 could be both positively and negatively modulated by different compounds; co-treatment with -tocopherol (vitamin E liposoluble) prevented the adverse effects of PCB126 in pericardial edema, whereas co-treatment with sodium nitroprusside (a vasodilator compound) significantly worsened PCB126 effects. Gene expression analysis showed an up-regulation of cyp1a, hsp70, and gstp1, indicative of PCB126 interaction with the aryl hydrocarbon receptor (AhR), while the transcription of antioxidant genes (sod1, sod2; cat and gpx1a) was not affected. Further studies are necessary to understand the role of oxidative stress in the developmental toxicity of low concentrations of PCB126 (25 nM). Our results give insights into the use of zebrafish embryos for exploring mechanisms underlying the oxidative potential of environmental pollutants

Modulation and Protection Effects of Antioxidant Compounds against Oxidant Induced Developmental Toxicity in Zebrafish

The antioxidant effect of compounds is regularly evaluated by in vitro assays that do not have the capability to predict in vivo protective activity or to determine their underlying mechanisms of action. The aim of this study was to develop an experimental system to evaluate the in vivo protective effects of different antioxidant compounds, based on the zebrafish embryo test. Zebrafish embryos were exposed to tert-butyl hydroperoxide (tBOOH), tetrachlorohydroquinone (TCHQ) and lipopolysaccharides from Escherichia coli (LPS), chemicals that are known inducers of oxidative stress in zebrafish. The developmental toxic effects (lethality or dysmorphogenesis) induced by these chemicals were modulated with n-acetyl l-cysteine and Nω-nitro l-arginine methyl ester hydrochloride, dimethyl maleate and dl-buthionine sulfoximine in order to validate the oxidant mechanism of oxidative stress inducers. The oxidant effects of tBOOH, TCHQ, and LPS were confirmed by the determination of significant differences in the comparison between the concentration-response curves of the oxidative stress inducers and of the modulators of antioxidant status. This concept was also applied to the study of the effects of well-known antioxidants, such as vitamin E, quercetin, and lipoic acid. Our results confirm the zebrafish model as an in vivo useful tool to test the protective effects of antioxidant compounds

Developmental effects and genotoxicity of ten water disinfection by-products in zebrafish

Disinfection by-products are contaminants produced during drinking water disinfection. Several DBPs have been implicated in a variety of toxic effects, mainly carcinogenic and genotoxic effects. Moreover, DBPs exposure has also been associated with an increased risk of developmental effects. In this study, the developmental toxicity and genotoxicity of 10 DBPs (4 trihalomethanes [THMs], 5 haloacetic acids [HAAs] and sodium bromate) in the zebrafish embryo model were evaluated. Embryos exposed for 72 hours were observed for different endpoints such as growth, hatching success, malformations and lethality. THMs exposure resulted in adverse developmental effects and a significant reduced tail length. Two HAAs, tribromoacetic acid and dichloroacetic acid, along with sodium bromate were found to cause a significant increase in malformation rate. Chloroform,chlorodibromomethane and sodium bromate produced a weak induction of DNA damage to whole embryos. However, developmental effects occurred at a range of concentrations (20 100 μg/mL)several orders of magnitude above the levels that can be attained in fetal blood in humans exposed to chlorinated water. In conclusion, the teratogenic and genotoxic activity observed by some DBPs in zebrafish reinforce the view that there is a weak capacity of disinfection products to cause developmental effects at environmentally relevant concentrations

La enseñanza de la Toxicología en Farmacia: los seminarios como herramienta para la evaluación continuada

Con la finalidad de adaptarnos al EEES, desarrollamos una herramienta que nos permitiera realizar un proceso de evaluación continua de la asignatura troncal de Toxicología. En el presente trabajo presentamos los resultados de este modelo en el que utilizamos los seminarios como elementos básicos de este proceso. Describimos cómo se estructuran y desarrollan estos seminarios, así como el modelo de evaluación de los mismos. Los seminarios fueron evaluados con una puntuación máxima del 30 % sobre la nota final de la signatura, y la participación en los mismos con un máximo del 10 %. Algunos de estos seminarios incorporaban evaluaciones realizadas antes del desarrollo de los mismos, que denominábamos «pre», y otras justo al final del desarrollo de los mismos, que denominábamos «post». Esta herramienta de evaluación continua se ha mostrado muy eficaz en lo que respecta al grado de participación y preparación de los alumnos. Además, ha supuesto un cambio significativo en el grado de implicación de los profesores, y una mejora de la comunicación alumno-profesor

Incorporación de pequeñas secuencias de cine comercial en la enseñanza de las drogodependencias. Ensayo piloto en la asignatura de Toxicología

El Grupo de Innovación Docente Orfila, en su propósito por mejorar la calidad de la docencia, está ensayando la utilización del cine con fines didácticos. El material desarrollado en este proyecto consiste en secuencias cortas de películas comerciales de 3 a 5 minutos de duración, que son utilizadas como elementos ilustrativos del proceso de adicción a las a drogas. Se seleccionan escenas de la filmografía y se adecúan al programa docente de la asignatura Toxicología. Se recoge la opinión de los profesores participantes, así como la de los alumnos, mediante una entrevista personal y una encuesta de opinión, respectivamente, de las que se deduce un alto grado de satisfacción

Triclabendazole sulfoxide causes stage-dependent embryolethality in zebrafish and mouse in vitro

Background Fascioliasis and paragonimiasis are widespread foodborne trematode diseases, affecting millions of people in more than 75 countries. The treatment of choice for these parasitic dis- eases is based on triclabendazole, a benzimidazole derivative which has been suggested as a promising drug to treat pregnant women and children. However, at the moment, this drug is not approved for human use in most countries. Its potential adverse effects on em- bryonic development have been scarcely studied, and it has not been assigned a pregnan- cy category by the FDA. Thus, to help in the process of risk-benefit decision making upon triclabendazole treatment during pregnancy, a better characterization of its risks during ges- tation is needed. Methodology The zebrafish embryo test, a preimplantation and a postimplantation rodent whole embryo culture were used to investigate the potential embryotoxicity/teratogenicity of triclabenda- zole and its first metabolite triclabendazole sulfoxide. Albendazole and albendazole sulfox- ide were included as positive controls. Principal Findings Triclabendazole was between 10 and 250 times less potent than albendazole in inducing dysmorphogenic effects in zebrafish or postimplantation rodent embryos, respectively. However, during the preimplantation period, both compounds, triclabendazole and tricla- bendazole sulfoxide, induced a dose-dependent embryolethal effect after only 24 h ofexposure in rodent embryos and zebrafish (lowest observed adverse effect concentra- tions = 10 μ M). Conclusions/Significance In humans, after ingestion of the recommended doses of triclabendazole to treat fascioliasis and paragonimiasis (10 mg/kg), the main compound found in plasma is triclabendazole sulf- oxide (maximum concentration 38.6 μ M), while triclabendazole concentrations are approxi- mately 30 times lower (1.16 μ M). From our results it can be concluded that triclabendazole, at concentrations of the same order of magnitude as the clinically relevant ones, does not entail teratogenic potential in vitro during the organogenesis period, but its first metabolite triclabendazole sulfoxide has a high embryotoxic capacity in vitro during the preimplantation stag

Cholangiocarcinoma in Magnetic Resonance Cholangiopancreatography and Fascioliasis in Endoscopic Ultrasonography

Fascioliasis is a worldwide zoonotic infection with Fasciola hepatica and Fasciola gigantica. The zoonoses are particularly endemic in sheep-raising countries and are also endemic in Iran. Typical symptoms that may be associated with fascioliasis can be divided by phases of the disease, including the acute or liver phase, the chronic or biliary phase, and ectopic or pharyngeal fascioliasis. Cholestatic symptoms may be absent, and in some cases diagnosis and treatment may be preceded by a long period of abdominal pain, eosinophilia and vague gastrointestinal symptoms. We report a case with epigastric and upper quadrant abdominal pain for the last 4 years, with imaging suggesting cholangiocarcinoma. Considering a new concept of endoscopic ultrasonography, at last F. hepatica was extracted with endoscopic retrograde cholangiography

Risk assessment for human embryonic development of triclabendazole residues in milk and cheese in the diet of a rural population in Cajamarca (Peru): A preliminary approach

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/103042Triclabendazole (TCBZ) is a veterinary drug used against Fasciola hepatica in cattle. The Cajamarca Valley in Peru is an endemic area of fascioliasis with a high infection rate in animals producing milk for human consumption. The administration of TCBZ during the lactating period can lead to TCBZ derivative residues in milk and cheese entering the human food chain. Milk-derivatives from treated animals have been found positive for TCBZ metabolites. One of these metabolites, triclabendazole sulfoxide (TCBZSO), is embryolethal during early developmental stages in vitro in mouse and zebrafish. In this study, we have calculated the estimated daily intake (EDI) of TCBZSO due to milk and cheese consumption among a rural population in Cajamarca in order to evaluate the associated risk for human embryonic development. Although the expected maximum plasma concentration of TCBZSO after a worst-case scenario simulation would be below the reported lowest observed adverse effect concentration (LOAEC) for embryolethality in vitro (10 μM), several limitations on the available information for exposure, bioavailability and interspecies differences still impede the accomplishment of an accurate risk assessment