Histopathological study on gills of Rhamdia quelen juveniles submitted to chronic toxicological test with ibuprofen

The present study aimed at evaluating histopathological changes in gills of Rhamdia quelenjuveniles submitted to different concentrations of ibuprofen (0.0; 0.5; 5.0 and 50.0 mg/L); concentrations were determined from LC50acute assays of 5.0mg/L(120h). For each concentration four replicates were made, with four copies each. The experiment had a total duration of 120 hours in a chronic toxicological trial. After completion, the animals were euthanized, laparotomized, and the gills were localized, isolated and fixed in 10% formaldehyde, preserved in 70% alcohol and subsequently submitted to histological routine technique for paraffin inclusion. Fivecuts (6μM) per specimen were made and stained with Hematoxylin and Eosin (H&E). The Average Alteration Score(AAS) and Histopathological Alteration Indices (HAI) were determined according to the degree of the lesion and then classified in stages I, II and III which produced respectively Lamellar derangement, Lamella’s epithelium rupture and aneurysm with more expressive alterations. For all concentrations the drug led to histological alterations for Rhamdia quelen, putting in evidence damages that go from moderate to severe in the gills of the analysed fishes. Ibuprofen caused branchial lesions in R.quelenwith a progressive effect in high concentrations, suggesting that the presence of this drug could cause abnormalities and favour mortality in this species.

Adaptation of the Systematic Review Framework to the Assessment of Toxicological Test Methods: Challenges and Lessons Learned With the Zebrafish Embryotoxicity Test

Systematic review methodology is a means of addressing specific questions through structured, consistent, and transparent examinations of the relevant scientific evidence. This methodology has been used to advantage in clinical medicine, and is being adapted for use in other disciplines. Although some applications to toxicology have been explored, especially for hazard identification, the present preparatory study is, to our knowledge, the first attempt to adapt it to the assessment of toxicological test methods. As our test case, we chose the zebrafish embryotoxicity test (ZET) for developmental toxicity and its mammalian counterpart, the standard mammalian prenatal development toxicity study, focusing the review on how well the ZET predicts the presence or absence of chemical-induced prenatal developmental toxicity observed in mammalian studies. An interdisciplinary team prepared a systematic review protocol and adjusted it throughout this piloting phase, where needed. The final protocol was registered and will guide the main study (systematic review), which will execute the protocol to comprehensively answer the review question. The goal of this preparatory study was to translate systematic review methodology to the assessment of toxicological test method performance. Consequently, it focused on the methodological issues encountered, whereas the main study will report substantive findings. These relate to numerous systematic review steps, but primarily to searching and selecting the evidence. Applying the lessons learned to these challenges can improve not only our main study, but may also be helpful to others seeking to use systematic review methodology to compare toxicological test methods. We conclude with a series of recommendations that, if adopted, would help improve the quality of the published literature, and make conducting systematic reviews of toxicological studies faster and easier over time.