The zebrafish embryo (ZFE) is a promising alternative non-rodent model in toxicology, and initial studies suggested its applicability in detecting hepatic responses related to drug-induced liver... Show moreThe zebrafish embryo (ZFE) is a promising alternative non-rodent model in toxicology, and initial studies suggested its applicability in detecting hepatic responses related to drug-induced liver injury (DILI). Here, we hypothesize that detailed analysis of underlying mechanisms of hepatotoxicity in ZFE contributes to the improved identification of hepatotoxic properties of compounds and to the reduction of rodents used for hepatotoxicity assessment. ZFEs were exposed to nine reference hepatotoxicants, targeted at induction of steatosis, cholestasis, and necrosis, and effects compared with negative controls. Protein profiles of the individual compounds were generated using LC-MS/MS. We identified differentially expressed proteins and pathways, but as these showed considerable overlap, phenotype-specific responses could not be distinguished. This led us to identify a set of common hepatotoxicity marker proteins. At the pathway level, these were mainly associated with cellular adaptive stress-responses, whereas single proteins could be linked to common hepatotoxicity-associated processes. Applying several stringency criteria to our proteomics data as well as information from other data sources resulted in a set of potential robust protein markers, notably Igf2bp1, Cox5ba, Ahnak, Itih3b.2, Psma6b, Srsf3a, Ces2b, Ces2a, Tdo2b, and Anxa1c, for the detection of adverse responses. Show less
Nanoparticles (NPs) exhibit special physicochemical properties compared to bulk particles. The difference in properties could, in principle, produce different effects on organisms. It is therefore... Show moreNanoparticles (NPs) exhibit special physicochemical properties compared to bulk particles. The difference in properties could, in principle, produce different effects on organisms. It is therefore important to determine the relationship between the physicochemical characteristics of NPs and their toxicity profile, by means of experimental testing. Experimental toxicity testing data can also be used to find the best dose metric for the responses induced by NPs, which was the purpose of the research presented in this thesis. Furthermore, this thesis aims to move forward from toxicity testing primarily in animal models to computational dose metric modeling. Show less
Cannabinoids are a group of terpenophenolic compounds and are naturally found in the cannabis plant (Cannabis sativa L). _9-Tetrahydrocannabinol (_9-THC) is the psychoactive cannabinoid. The high... Show moreCannabinoids are a group of terpenophenolic compounds and are naturally found in the cannabis plant (Cannabis sativa L). _9-Tetrahydrocannabinol (_9-THC) is the psychoactive cannabinoid. The high lipophilicity of _9-THC is a hindering factor in the further development of this compound into a large scale pharmaceutical product. In an effort to generate highly polar derivatives of _9-THC, we screened 206 alkane degrading bacterial strains. In total, eight derivatives were produced on milligram. All of these biotransformation products harbored modified alkyl chains, with hydroxy, carboxy and ester functionalities. We also investigated the potential of cell suspension culture of Catharanthus Roseus to transform _9-THC. Unlike bacterial strains, Catharanthus Roseus cells transformed _9-THC to its glycosylated and additionally hydroxylated derivatives. The behavioral effects of __9-THC are mediated by the centra l CB1 receptor in rats. CB1 receptors show high degree of sequence conservation in vertebrates. We used zebrafish embryos as a model to study the behavioral effects of cannabinoids. We conclude that cannabinoids have behavioural effects in zebrafish that are comparable to some of those reported in the literature for mammals. In particular, the acute exposure response resembles behavioural effects reported for adult. This suggests that some similarity in cannabinoid response pathways between zebrafish and mammals exists. We also performed the metabolomic profiling of zebrafish embryos treated with the concentrations of CB1 agonist and antagonist used in behavioural assays. The results of behavioural assays were successfully correlated with the metabolomic data of zebrafish embryos. Show less
Technological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in... Show moreTechnological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in applied biomedical research, using selected cases. We look at the use of zebrafish embryos as disease models, taking fetal alcohol syndrome and tuberculosis as examples. We discuss advances in imaging, in culture techniques (including microfluidics), and in drug delivery (including new techniques for the robotic injection of compounds into the egg). The use of zebrafish embryos in early stages of drug safety-screening is discussed. So too are the new behavioral assays that are being adapted from rodent research for use in zebrafish embryos, and which may become relevant in validating the effects of neuroactive compounds such as anxiolytics and antidepressants. Readouts, such as morphological screening and cardiac function, are examined. There are several drawbacks in the zebrafish model. One is its very rapid development, which means that screening with zebrafish is analogous to __screening on a run-away train.__ Therefore, we argue that zebrafish embryos need to be precisely staged when used in acute assays, so as to ensure a consistent window of developmental exposure. We believe that zebrafish embryo screens can be used in the pre-regulatory phases of drug development, although more validation studies are needed to overcome industry scepticism. Finally, the zebrafish poses no challenge to the position of rodent models: it is complementary to them, especially in early stages of drug research. Show less
