The importance of cutaneous gas exchange during aerial and aquatic respiration in galaxiids.

The Canterbury mudfish Neochanna burrowsius was found to be a pseudo-aestivating galaxiid with a low metabolic rate and significant cutaneous oxygen uptake (c. 43%) in both air and water. Another galaxiid, inanga Galaxias maculatus, had a higher metabolic rate in both media but the proportion of oxygen uptake met by cutaneous respiration rose significantly from 38 to 63% when the fish were exposed to air. Besides its important role in oxygen uptake, the skin of both species also contributed significantly to excretion of carbon dioxide in air, indicating the critical role of the integument as a respiratory tissue. In air, G. maculatus may increase cutaneous gas exchange to meet metabolic demands owing to the reduced utility of the gills, but as emersed G. maculatus were only able to maintain metabolic rates at c. 67% of that measured in water, this strategy probably only permits short-term survival. By contrast, the low and unchanging metabolic rate in water and air in N. burrowsius is a feature that may facilitate tolerance of long periods of emersion in the desiccating environments they inhabit.

Behavioural and physiological responses to salinization and air exposure during the ontogeny of a freshwater South American snail.

Salinization is of global concern, threatening freshwater biodiversity. Salinity tolerance is highly variable and therefore needs to be evaluated on a species-specific basis. An estuarine population of Chilina dombeiana, a freshwater gastropod endemic to Chile and classified as vulnerable, has been recently found in the Biobío River's mouth, suggesting some degree of tolerance to brackish waters. This study evaluated the survival, behaviour (medium preference) and physiology of C. dombeiana when exposed to salinities higher than freshwater, thus elucidating the potential mechanisms used to survive salinization. Chilina dombeiana belongs to the Pulmonate group;, so we evaluated oxygen uptake in air and water, aiming to evaluate emersion as a potential avoidance response to a progressive salinity increase. Complete embryo development was observed for salinities ≤ 16 PSU (practical salinity units) but hatching rates above 50% were only achieved in freshwater (0 PSU). It was also found that salinity had stage-specific effects during embryonic development. In adults, acute exposure to brackish water (12 PSU) caused a decrease in oxygen consumption (compared to freshwater), in the ammonium excretion rates and in the percentage of muscular water content. Although C. dombeiana was able to take up oxygen in both mediums, survival in air decreased over time (days), which correlates with the behavioural preference to remain submerged, even at elevated salinities. Considering the survival of adults and embryos decreased as salinity increased and the lack of an avoidance behaviour or a physiological ability to maintain homeostasis at salinities higher than freshwater, our results suggest this snail could be adversely affected by salinization in the long term. Furthermore, given the ability of C. dombeiana to uptake oxygen in both mediums, it should be considered as a facultative air breather snail, rather than a strictly aquatic species.

Oxidative damages and antioxidant defences after feeding a single meal in rainbow trout.

Feeding and digestion are metabolically demanding causing a rise on metabolic rate called Specific Dynamic Action (SDA). Although SDA has been vastly reported in fish, its potential consequences on the oxidative-antioxidant balance has not been evaluated to date in fish, a model with a long alkaline tide associated with feeding as well. Using rainbow trout (Oncorhynchus mykiss) as a model species, the aims of the present study were to: (1) assess potential oxidative damages and changes in oxidative defences after feeding on a single meal, and (2) identify the timescale of such changes over a 96 h post-feeding period. Oxidative damage in proteins and lipids and the activities of four enzymatic antioxidant defences: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were measured in gill, stomach, intestine and liver. DNA damage was measured in red blood cells. Fish were sampled before and after 1.5, 6, 24, 48, 72 and 96 h of ingestion of a 3% body mass ration. Trends of post-prandial damage were present in all tissues, but only protein oxidation varied significatively during digestion in the stomach. The intestine and stomach presented the highest enzymatic activities, likely due to the high metabolic action that these tissues have during digestion, with peaks during post-feeding: at 24 h of SOD in stomach and at 48 h of CAT in intestine. Observed GPx peaks during post-feeding in gills are likely due to the exacerbated demands for ion fluxes and/or oxygen during feeding. The differential response of the antioxidant system observed in tissues of rainbow trout during digestion indicates a coordinated and tissue-specific antioxidant defence.

Chronic dialysis-associated anaemia in end-stage renal disease: analysis of management in two French centres.

BACKGROUND: Treatment of anaemia in renal-insufficient patients relies on the use of an erythropoiesis-stimulating agent (ESA). This study aimed to compare the impact of two different strategies of ESA prescribing on variation in haemoglobin (Hb) concentration in end-stage renal disease (ESRD) patients. METHODS: Patients with ESRD, on haemodialysis, and who had received ESA for >3 months were recruited. Different parameters were analysed: demographics, Hb level the last day of the year before dialysis, the most recent weekly ESA dose, risk factors for resistance and cost. Each institution continued its local practice for achieving the desired Hb level: increasing the ESA dose to overcome resistance in one centre and defining an upper ESA-dose limit in the other. RESULTS: A total of 185 patients were recruited. No significant differences in the biological parameters were found between the two populations. In both centres, Hb levels were comparable and mean levels exceeded 11 g/dL, despite the higher ESA doses given in one centre to achieve this target. This finding also held true for the subgroups with greater than or equal to two resistance factors. These two strategies led to large between-centre differences in treatment costs. CONCLUSION: The ESA-use strategy difference probably indicates that erythropoietin-resistance was not overcome with increased dosing. The Hb concentrations remained stable even when ESA doses were increased. On current evidence, the cheaper ESA-dose limitation strategy is preferable but randomized controlled studies, including comparisons of alternative ESA formulations are necessary.

Effects of pharmaceuticals used to treat salmon lice on non-target species: Evidence from a systematic review.

Aquaculture is currently one of the best prospects to help meet the growing need for protein in the human diet. However, aquaculture development and production result in consequences for the environment and also impact other productive activities. Salmon and trout cage culture has required the use of large quantities of pharmaceuticals in order to control outbreaks and the persistence of different pathogens, including sea lice (parasitic copepods), which cause economic losses of around 0.39 €â€¯Kg-1 of salmon produced. The pharmaceuticals currently used for the control of sea lice (cypermethrin, deltamethrin, azamethiphos, hydrogen peroxide) are applied by in situ immersion treatments, enclosing net pens using tarpaulin and then bathing fish with the pharmaceutical. After treatment the pharmaceuticals are released into the surrounding environment, exposing non-target species. Although the effects of such pharmaceutical exposure has been studied in some species, to date a systematic and exhaustive review of these potential effects has not yet been performed. In this study, an exhaustive review of the literature evaluating lethal and sub-lethal effects of anti-sea lice pharmaceuticals on non-target crustaceans and bivalves was performed, in order to assess the extent of the effects, toxicity, variables affecting such toxicity and identify potential synergistic effects previously unexplored. Our results show clear negative effects at concentrations lower than those used in treatments against sea lice in all of the species studied. Likewise, this study demonstrates knowledge gaps that need to be addressed in order to improve our understanding of the effects of these pharmaceuticals on non-target species, ecosystems in general and other productive activities.

Epoetin in haemodialysis patients: impact of change from subcutaneous to intravenous routes of administration.

BACKGROUND AND OBJECTIVE: Cases of erythroblastopenia, as an adverse effect to epoetin (EPREX), led to its use being restricted in Europe to the intravenous route (i.v.) since July 2002, in patients with chronic renal insufficiency. This work aimed at investigating the biological, pharmaceutical and economic impacts of this change in policy. METHODS: We retrospectively compared the characteristics of 99 haemodialysis patients treated with epoetin at the time of the recommendation (July 2002) and 5 months after the policy change (November 2002). RESULTS: In July 2002, 69 patients who were receiving EPREX subcutaneously (s.c./i.v. group) changed to the i.v. route of administration. Thirty other patients were already on i.v. epoetin (i.v. group). During the study period, the dose of epoetin increased significantly in the s.c./i.v. group but not in the i.v. group (46.83 +/- 10.20 UI/kg/week vs. 2.17 +/- 20.14 UI/kg/week respectively). This increased dosage was accounted for by a subgroup of 42 patients in the s.c./i.v. group while the others had dosage variations similar to those observed in the i.v. group. There were no significant clinical and biological changes associated with this change in route of administration. However, the change in policy led to the haemodialysis ward incurring an additional cost of 265,905 Euro (+32.7%) or an average annual extra cost of 1841 +/- 401 Euro per patient. CONCLUSION: Changing the route of administration of EPREX from the i.v. to the subcutaneous route required an increase in dosage and in substantial additional cost.