Effects of dexmedetomidine alone or in combination with opioids on intraocular pressure in healthy Beagle dogs.

OBJECTIVE: To evaluate the effects of dexmedetomidine alone or in combination with different opioids on intraocular pressure (IOP) in dogs. STUDY DESIGN: Experimental, prospective, crossover, randomized, blinded study. ANIMALS: A total of six Beagle dogs (two males and four females) aged 2 years and weighing 15.9 ± 2.9 kg (mean ± standard deviation). METHODS: Dogs were distributed randomly into seven treatments (n = 6 per treatment) and were administered dexmedetomidine alone (10 µg kg-1; Dex) or in combination with butorphanol (0.15 mg kg-1; DexBut), meperidine (5 mg kg-1; DexMep), methadone (0.5 mg kg-1; DexMet), morphine (0.5 mg kg-1; DexMor), nalbuphine (0.5 mg kg-1; DexNal) or tramadol (5 mg kg-1; DexTra). All drugs were administered intramuscularly. IOP was measured before drug injection (time 0, baseline) and every 15 minutes thereafter for 120 minutes (T15-T120). RESULTS: There were significant reductions in IOP compared with baseline in treatments Dex and DexMep at times T30-T120, and in treatment DexMet at T15-T90. IOP decreased compared with baseline in treatments DexBut, DexNal and DexTra at all evaluation times. No changes in IOP were seen in treatment DexMor. The mean IOP values in treatment DexMet at T105-T120 were higher than those for other treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine alone or in combination with butorphanol, meperidine, methadone, nalbuphine or tramadol resulted in decreased IOP for 120 minutes in dogs. The magnitude of the reduction was small and lacked clinical significance.

Investigating heavy metal bioaccumulation by macrofauna species from different feeding guilds from sandy beaches in Rio de Janeiro, Brazil.

The relationship between metal accumulation and feeding behavior of macrofauna species is a key concept to understand the bioavailability of different metals in the marine environment. We examined and compared the concentrations of eight heavy metals (Cr, Zn, Pb, Ni, Cu, Cd, Co and V) in different feeding guilds of macrofauna species, from a data set including 68 sandy beaches along the Rio de Janeiro coast. For this purpose, macrofauna species were classified in five feeding guild categories: carnivorous, herbivorous, detritivorous, suspensivorous and filter feeders. The coast of Rio de Janeiro was divided into seven regions according to environmental characteristics and historical human activities. For each region, generalized linear models were adjusted to test for differences between feeding guild abundances. Redundancy Analysis was performed to explore the relationship among the feeding guilds composition and the environmental variables. We found high variability in abundance and composition among feeding guilds, linked with environmental heterogeneity. In general, carnivorous species showed a higher heavy metal concentrations compared to other trophic guilds evaluated. However, bioaccumulation across the feeding guild was not the rule and patterns varied across regions. Our hypothesis is that variations are probably related to the different magnitudes of metal contamination along the coast as also in to the trophic structure found in each beach. This data highlighted the crucial role of the relationship between variability of environmental drivers and bioaccumulation in macrofauna species in sandy beaches ecosystem.

Spatiotemporal variability of solid waste on sandy beaches with different access restrictions.

Intense human use and high construction density in coastal areas are stressors to sandy beaches. Pollution by marine debris is a major problem on beaches worldwide. This study pioneered an assessment of marine debris characterization over time on beaches with different levels of access. In two periods and seasons, marine debris was sampled on nine sandy beaches of Rio de Janeiro, grouped by levels of access. The general marine debris density has decreased over time, accompanied by an improvement in public cleaning mechanisms. The most important predictor for the majority of marine debris items is related to accessibility; beaches with restricted access showed a reduction in the abundance of most items. High marine debris densities, even on beaches with restricted access, showed that all evaluated beaches can be sinks for marine debris circulating in marine waters. Beach cleaning strategy improvements will be inefficient unless integrated marine debris management is implemented.

Heavy metal contamination in sandy beach macrofauna communities from the Rio de Janeiro coast, Southeastern Brazil.

We evaluated concentrations of eight heavy metals Cr, Zn, Pb, Ni, Cu, Cd, Co and V, in tissues of representative macrofauna species from 68 sandy beaches from the coast of Rio de Janeiro state. The links between contamination levels and community descriptors such as diversity, evenness, density and biomass, were also investigated. Metal concentrations from macrofaunal tissues were compared to maximum permissible limits for human ingestion stipulated by the Brazilian regulatory agency (ANVISA). Generalized linear models (GLM's) were used to investigate the variability in macrofauna density, richness, eveness and biomass in the seven different regions. A non-metric multidimensional scaling analysis (n-MDS) was used to investigate the spatial pattern of heavy metal concentrations along the seven regions of Rio de Janeiro coast. Variation partitioning was applied to evaluate the variance in the community assemblage explained by the environmental variables and the heavy metal concentrations. Our data suggested high spatial variation in the concentration of heavy metals in macrofauna species from the beaches of Rio de Janeiro. This result highlighted a diffuse source of contamination along the coast. Most of the metals concentrations were under the limits established by ANVISA. The variability in community descriptors was related to morphodynamic variables, but not with metal contamination values, indicating the lack of direct relationships at the community level. Concentration levels of eight heavy metals in macrofauna species from 68 sandy beaches on Rio de Janeiro coast (Brazil) were spatially correlated with anthropogenic activities such as industrialization and urbanization.