The aim of this study was to evaluate patients' knowledge and perception of the use of systemic antibiotics in the treatment of endodontic infections and to determine the possible contribution of patients to the development of bacterial resistance. Five hundred and fifty patients were asked to respond to a survey on the perception of systemic antibiotic use in the treatment of endodontic infections and antibiotic resistance during January 2022 and March 2023. Data were analyzed using descriptive statistics and Pearson's Chi-square test. 514 patients were included in the study, 65.9% of whom were women. While 34.6% of the population studied thought that it was always necessary to take antibiotics prior to endodontics, 49.4% considered that they were necessary after endodontics, regardless of the clinical symptoms (p>0.05). The prevalence of self-medication was 17.3% and women self-medicate more than men, with significant differences (p<0.05), although they have greater knowledge of antibiotic resistance than men (p>0.05). Forty-four percent of the population expect to take antibiotics when faced with dental pain, mainly women (p<0.05). The general population is contributing to the serious problem of bacterial resistance. It is necessary to promote educational strategies focused on the correct use of antibiotics in the community.

Objective: To determine blood lead levels (BLL) in a healthy paediatric population and to analyse related sociodemographic, dietary and haematological factors. Methods: A cross-sectional study was made of 1,427 healthy subjects aged 1-16 years from the city of Almería (south-eastern Spain). BLL, iron parameters and erythropoietin were determined, and sociodemographic and dietary data obtained. The study data were analysed by multiple logistic regression. Results: The mean BLL was 1.98±1.1 µg/dl (95% CI:1.91–2.04). For 5.7% of the population, mean BLL was 2-5 µg/dl, for 2.1% it was >5 µg/dl and for 0.15% it was >10 µg/dl. Multivariate analysis showed that immigrant origin (OR:11.9; p<0.0001), low level of parental education (OR:4.6; p<0.02) and low dietary iron bioavailability (OR: 3.2; p<0.02) were all risk factors for toxic BLL. Subjects with toxic and non-toxic BLL presented similar iron and erythropoiesis-related parameters, except erythrocyte protoporphyrin, which was significantly higher in the BLL >5 µg/dl group. Conclusions: BLL and the prevalence of toxic BLL in healthy subjects aged 1-16 years living in south-eastern Spain are low and similar to those found in other developed countries. The factors associated with toxic BLL are immigrant origin, low level of parental education and dietary iron deficiency. The toxicity of BLL was not related to changes in the analytical parameters studied.

A truss network was applied to analyze morphometric differentiation among three wild populations of Hoplias microlepis, captured in three different sites from two habitats of Guayas Hydrographic Basin: Daule-Peripa dam, Quevedo and Babahoyo rivers. This study can help to deepen to the knowledge of the species adaptation to different environments and highlights some factors which may be helpful for future management and conservation of the freshwater resources of Ecuador. A sample of 225 adult fish were collected, 49 morphometric characteristics and 6 meristic counts were analyzed, and a statistical model was built through multifactorial discriminant analysis. The standard length of Hoplias microlepis was 32.14 cm, total length 37.82 cm and sexual maturity index 4.39. The Hoplias microlepis with the greatest weight, length and sexual maturity index were in the dam where the food availability is better, and the fishing pressure is lower. Finally, the cluster analysis grouped the fish from the rivers in cluster 1 and those from the dam in cluster 2, being samples of dam clearly distinct from rivers, probably due to differences in the habitat condition. Fish body condition and morphological variation at different sites may be useful indicators for both, habitat disturbance and consequently its conservation, and the sustainability of fishery management plans.

Europium is one of the most reactive lanthanides and humans use it in many different applica-tions, but we still know little about its potential toxicity and cellular response to its exposure. Two strains of the eukaryotic microorganism model Tetrahymena thermophila adapted to high concentrations of two Eu(III) compounds (EuCl3 or Eu2O3) were obtained and compared to a control strain and cultures treated with both compounds. In this ciliate, EuCl3 is more toxic than Eu2O3. LC50 values show that this microorganism is more resistant to these Eu(III) compounds than other microorganisms. Oxidative stress originated mainly by Eu2O3 is minimized by overexpression of genes encoding important antioxidant enzymes. The overexpression of metallothionein genes under treatment with Eu(III) compounds supports the possibility that this lanthanide may interact with the -SH groups of the cysteine residues from metallothi-oneins and/or displace essential cations of these proteins during their homeostasis function. Both lipid metabolism (lipid droplets that fuse with europium-containing vacuoles) and au-tophagy are involved in the cellular response to europium stress. Bioaccumulation, together with a possible biomineralization to europium phosphate, seems to be the main mechanism of Eu(III) detoxification in these cells.