Rapid determination of polycyclic aromatic hydrocarbons (PAHs) in zebrafish eleutheroembryos as a model for the evaluation of PAH bioconcentration.

A simple and fast approach for a novel bioaccumulation test by exposing zebrafish eleutheroembryos to fluorene and anthracene (PAHs) at two concentration levels below 1% of their LC50 is presented. This alternative protocol sets an uptake period of 48 h at 26 °C for bioconcentration of the compounds tested and an additional 24h for depuration. Two different methods to estimate bioconcentration factors (BCFs) of PAHs were used. The first consists in the ratio between concentrations of the tested compounds in the zebrafish eleutheroembryos and the exposure media when a steady state during exposure is reached (BCFss). The second employs the concentration-time profile with the use of a least-square fit to a non-linear model (BCFk). A steady state (ss) was reached after 12h and 22 h for fluorene and anthracene exposure, respectively. Uptake and depuration rate constants obtained were similar for the two exposure levels tested, hence toxicokinetic rate constants appeared to be independent of the exposure level. Bioconcentration factors of 1164 and 817 for fluorene exposure at 0.99 ng mL(-1) and 7.9 ng mL(-1) and of 2089 and 2344 for anthracene at 0.63 ng mL(-1) and 6.1 ng mL(-1) were assessed. The good agreement of the obtained results with those reported in the literature proves the feasibility of the proposed method for estimation of both toxicokinetic parameters and bioconcentration factors. Furthermore, this protocol, has potential to be an alternative to the Organisation for Economic Cooperation and Development (OECD) 305 method, considerably reducing time and associated costs of the test suggested by European legislation.

Bioconcentration of pesticides in zebrafish eleutheroembryos (Danio rerio).

The feasibility of a bioaccumulation test based on the use of zebrafish eleutheroembryos as an alternative to adult-individual-based approaches for REACH application has been evaluated for three test compounds, chlorpyrifos, dicofol and atrazine. Following the OECD 305 guidelines, zebrafish eleutheroembryos (72 h after hatching, hpf) were separately exposed to the investigated pesticides at two nominal concentrations below 1% of its corresponding LC(50). The uptake experiments lasted for 48 h. Then, the exposure medium was replaced by a non-contaminated medium for depuration experiments (up to 72 h). Zebrafish eleutheroembryos (larvae 144 hpf, i.e. at the end of the depuration step) and their corresponding exposure media was sampled at ten different times during each experiment and the concentration of the investigated pesticide determined in both the organisms and in the exposure medium. The experimentally determined pesticide accumulation profiles in the eleutheroembryos demonstrated that atrazine has a very fast accumulation kinetic, reaching steady sate (SS) within 24h. Chlorpyrifos and dicofol did not reach the SS within the 48-h uptake experiments although they exhibit higher accumulations than the former pesticide. Two toxicokinetic models were used to calculate the bioconcentration factor (BCF) of the studied pesticide in zebrafish eleutheroembryos. In the former, the BCF was calculated under SS conditions (BCF(SS)). The second was used when the compounds did not reach the SS during the uptake experiment (BCF(k)). Log BCF values of 3.55 and 3.84 for chlorpyrifos; 0.6 and 1.17 for atrazine, and 3.90 for dicofol were experimentally calculated at selected exposure concentrations. These values have been compared with those reported in related bioaccumulation studies and official databases.

[Ovarian pregnancy. Four cases with review of the literature]. / La grossesse ovarienne. A propos de 4 observations avec revue de la littérature.

The authors report four cases of ovarian pregnancies operated in Central Maternity of Rabat (Pr Chaoui) during a period from 1979 to 1989. In the light of literature data, they have tried to trace out the particularities of this form of extra-uterine pregnancy. Clinical symptomatology of ovarian pregnancy very often remains similar to that of tubary GEU as well as the data of complementary exams with the exception sometimes of coelioscopy. The treatment, because of diagnostic delay, is annexectomy in all cases. But it is desirable to carry out a conservative treatment in the form of partial ovariectomy. Only pathological anatomy can give the diagnosis a sense of certainty.