Bioassays to assess the ecotoxicological impact of polyethylene microplastics and two organic pollutants, simazine and ibuprofen.

Research on the environmental impact of plastics, especially on the effect of microplastics (MPs), has become a priority issue in recent years, mainly in terrestrial ecosystems where there is a lack of studies. This work aims to assess the impact of two types of polyethylene MPs, white microbeads (W) and fluorescent blue microbeads (FB), and their interactions with two contaminants, ibuprofen (Ib) and simazine (Sz), on different organisms. A set of bioassays for Vibrio fischeri, Caenorhabditis elegans and Lactuca sativa was carried out, which helped to establish the ecotoxicological impact of those pollutants. C. elegans showed the least sensitivity, while V. fischeri and L. sativa showed a high toxicological response to MPs alone. We found that W and FB induced an inhibition of 27% and 5.79%, respectively, in V. fischeri, and the growth inhibition rates were near 70% in L. sativa for both MPs. MPs exhibited a potential role as contaminant vectors in V. fischeri since the inhibition caused by W-Ib or W-Sz complexes was near 39%. The W-Sz complex significantly reduced leaf development in L. sativa, and a reduction of 30% in seed germination was detected when the complex FB-Sz was tested. This study reveals the importance of designing a complete set of analyses with organisms from different trophic levels, considering the great variability in the effects of MPs and the high number of relevant factors.

Pharmacokinetics of doxycycline after oral administration of multiple doses in dogs.

The aim of this study was to determine the pharmacokinetic parameters of doxycycline in dogs and assess the efficacy of an oral drug dosage regimen of 10 mg/kg daily for 28 days through Pharmacokinetic/Pharmacodynamic (PK/PD) target analysis based on Monte Carlo simulation, using previously published data for the zoonotic pathogen Staphylococcus pseudintermedius. After a multiple-dosage regimen, the accumulation index was 1.88 ± 0.82. The Cmaxss and Cminss values were 5.18 ± 1.81 µg/ml and 1.91 ± 1.35 µg/ml, respectively. There were statistically significant differences for Cmax, Cmin at 24 hr, MRTt, AUCt and AUC∞ between days 1 and 28. The Cminss value was over the MIC of the principal pathogens, and Cmaxss was higher than the resistance values (>2 µg/ml). For AUC/MIC indices of 12, 25 and 40, the cumulative fraction responses (CFR) were 94.01%, 69.55% and 60.86%, respectively; for an MIC value of 2 µg/ml, the corresponding probability of target attainment (PTA) was 99.94%, 84.78% and 45.16%, respectively. Doxycycline was used against numerous localized infections in different organs and tissues. For the strains with MIC < 1 µg/mL, PTA was close to 100%, even for the most demanding ones, specifically 94.98% for an index of 40% and 99.9% for an index of 25.

Disposition of marbofloxacin in vulture (Gyps fulvus) after intravenous administration of a single dose.

The pharmacokinetics properties of marbofloxacin were studied in adult Eurassian Griffon vulture after single-dose intravenous (IV) administration of 2mg/kg. Drug concentration in plasma was determined by high-performance liquid chromatography and the data obtained were subjected to compartmental and non-compartmental kinetic analysis. Marbofloxacin presented a volume of distribution at steady-state (Vdss) of 1.51±0.22L and total plasma clearance (Cl) of 0.109±0.023L/hkg. The permanence of this drug was long in vultures (T(1/2)(λ)=12.51±2.52h; MRT(∞)=13.54±2.29h). The optimal dose of marbofloxacin estimated is 2.73mg/kg per day for the treatment of infections in vultures with MIC(90)=0.2µg/mL.