Experimental evidence for recovery of mercury-contaminated fish populations.

Anthropogenic releases of mercury (Hg)1-3 are a human health issue4 because the potent toxicant methylmercury (MeHg), formed primarily by microbial methylation of inorganic Hg in aquatic ecosystems, bioaccumulates to high concentrations in fish consumed by humans5,6. Predicting the efficacy of Hg pollution controls on fish MeHg concentrations is complex because many factors influence the production and bioaccumulation of MeHg7-9. Here we conducted a 15-year whole-ecosystem, single-factor experiment to determine the magnitude and timing of reductions in fish MeHg concentrations following reductions in Hg additions to a boreal lake and its watershed. During the seven-year addition phase, we applied enriched Hg isotopes to increase local Hg wet deposition rates fivefold. The Hg isotopes became increasingly incorporated into the food web as MeHg, predominantly from additions to the lake because most of those in the watershed remained there. Thereafter, isotopic additions were stopped, resulting in an approximately 100% reduction in Hg loading to the lake. The concentration of labelled MeHg quickly decreased by up to 91% in lower trophic level organisms, initiating rapid decreases of 38-76% of MeHg concentration in large-bodied fish populations in eight years. Although Hg loading from watersheds may not decline in step with lowering deposition rates, this experiment clearly demonstrates that any reduction in Hg loadings to lakes, whether from direct deposition or runoff, will have immediate benefits to fish consumers.

Informing the Exposure Landscape: The Fate of Microplastics in a Large Pelagic In-Lake Mesocosm Experiment.

Understanding microplastic exposure and effects is critical to understanding risk. Here, we used large, in-lake closed-bottom mesocosms to investigate exposure and effects on pelagic freshwater ecosystems. This article provides details about the experimental design and results on the transport of microplastics and exposure to pelagic organisms. Our experiment included three polymers of microplastics (PE, PS, and PET) ranging in density and size. Nominal concentrations ranged from 0 to 29,240 microplastics per liter on a log scale. Mesocosms enclosed natural microbial, phytoplankton, and zooplankton communities and yellow perch (Perca flavescens). We quantified and characterized microplastics in the water column and in components of the food web (biofilm on the walls, zooplankton, and fish). The microplastics in the water stratified vertically according to size and density. After 10 weeks, about 1% of the microplastics added were in the water column, 0.4% attached to biofilm on the walls, 0.01% within zooplankton, and 0.0001% in fish. Visual observations suggest the remaining >98% were in a surface slick and on the bottom. Our study suggests organisms that feed at the surface and in the benthos are likely most at risk, and demonstrates the value of measuring exposure and transport to inform experimental designs and achieve target concentrations in different matrices within toxicity tests.

Our Data, Our Question: Public-Centric Approaches to Administrative Data Analysis.

There is growing recognition of the importance of patient, public and community engagement in health research, which has not been used widely in analyzing health administrative datasets. In Ontario, health data are stewarded by ICES, whose strategic decision making is guided by a diverse Public Advisory Council (PAC). In a first foray into publicly led projects, the ICES PAC undertook an analysis project on mental health and addiction health service use. Public members guided the project through all stages of research. This generated critical lessons for ICES on improving participation, collaboration and trust.

Freshwater connectivity transforms spatially integrated signals of biodiversity.

Aquatic ecosystems offer a continuum of water flow from headwater streams to inland lakes and coastal marine systems. This spatial connectivity influences the structure, function and dynamics of aquatic communities, which are among the most threatened and degraded on the Earth. Here, we determine the spatial resolution of environmental DNA (eDNA) in dendritic freshwater networks, which we use as a model for connected metacommunities. Our intensive sampling campaign comprised over 420 eDNA samples across 21 connected lakes, allowing us to analyse detections at a variety of scales, from different habitats within a lake to entire lake networks. We found strong signals of within-lake variation in eDNA distribution reflective of typical habitat use by both fish and zooplankton. Most importantly, we also found that connecting channels between lakes resulted in an accumulation of downstream eDNA detections in lakes with a higher number of inflows, and as networks increased in length. Environmental DNA achieves biodiversity surveys in these habitats in a high-throughput, spatially integrated way. These findings have profound implications for the interpretation of eDNA detections in aquatic ecosystems in global-scale biodiversity monitoring observations.

Large Fractionation in Iron Isotopes Implicates Metabolic Pathways for Iron Cycling in Boreal Shield Lakes.

Stable Fe isotopes have only recently been measured in freshwater systems, mainly in meromictic lakes. Here we report the δ56Fe of dissolved, particulate, and sediment Fe in two small dimictic boreal shield headwater lakes: manipulated eutrophic Lake 227, with annual cyanobacterial blooms, and unmanipulated oligotrophic Lake 442. Within the lakes, the range in δ56Fe is large (ca. -0.9 to +1.8‰), spanning more than half the entire range of natural Earth surface samples. Two layers in the water column with distinctive δ56Fe of dissolved (dis) and particulate (spm) Fe were observed, despite differences in trophic states. In the epilimnia of both lakes, a large Δ56Fedis-spm fractionation of 0.4-1‰ between dissolved and particulate Fe was only observed during cyanobacterial blooms in Lake 227, possibly regulated by selective biological uptake of isotopically light Fe by cyanobacteria. In the anoxic layers in both lakes, upward flux from sediments dominates the dissolved Fe pool with an apparent Δ56Fedis-spm fractionation of -2.2 to -0.6‰. Large Δ56Fedis-spm and previously published metagenome sequence data suggest active Fe cycling processes in anoxic layers, such as microaerophilic Fe(II) oxidation or photoferrotrophy, could regulate biogeochemical cycling. Large fractionation of stable Fe isotopes in these lakes provides a potential tool to probe Fe cycling and the acquisition of Fe by cyanobacteria, with relevance for understanding biogeochemical cycling of Earth's early ferruginous oceans.

Basketball vs. Hockey-The Changing Face of Sport-Related Injuries in Canada.

OBJECTIVE: To characterize and compare the incidence of basketball-related, soccer-related, and hockey-related injuries over a 10-year period. DESIGN: Cohort analysis of sport-related injuries using multiple Ontario healthcare databases. SETTING: Emergency department visits in Ontario, Canada. PATIENTS: Any patient who sustained musculoskeletal injuries sustained while playing basketball, soccer, or hockey between 2006 and 2017 were identified. ASSESSMENT OF RISK FACTORS: Sport of injury, age, sex, rurality index, marginalization status, and comorbidity score. MAIN OUTCOME MEASURES: Annual Incidence Density Rates of injury were calculated for each sport, and significance of trends was analyzed by assessing overlap of 95% confidence intervals. RESULTS: One lakhs eighty five thousand eighty hundred sixty-eight patients (median age: 16 years, interquartile range 13-26) received treatment for sport-related injuries (basketball = 55 468; soccer = 67 021; and hockey = 63 379). The incidence of basketball-related and soccer-related injuries increased from 3.4 (3.3-3.5) to 5.6 (5.5-5.7) and 4.4 (4.3-4.5) to 4.9 (4.8-5) per 10 000 person years, respectively, whereas the incidence of hockey-related injuries decreased from 4.7 (4.6-4.8) to 3.7 (3.6-3.8). Patients with basketball injuries were more marginalized (3.01 ± 0.74) compared with patients with soccer and hockey injuries (2.90 ± 0.75 and 2.72 ± 0.69, respectively). CONCLUSIONS: Accurate regional epidemiologic information regarding sports injuries can be used to guide policy development for municipal planning and sport program development. The trends and demographic patterns described highlight general and sport-specific injury patterns in Ontario. Populations with the highest incidence of injury, most notably adolescents and men older than 50, may represent an appropriate population for injury risk prevention.

Identification of incident pancreatic cancer in Ontario administrative health data: A validation study.

PURPOSE: To validate three approaches for identifying incident cases of pancreatic cancer in Ontario administrative claims data. METHODS: We created a cohort using Ontario (Canada) administrative health data from 2002 to 2012 and identified cases of pancreatic cancer with three approaches, using the Ontario Cancer Registry (OCR) as the reference standard. In the any diagnosis approach, cases were defined by primary or secondary diagnostic codes for pancreatic cancer in outpatient or inpatient records. In the any inpatient diagnosis approach, cases were defined using only diagnoses in hospital discharge abstracts. In the algorithm approach, cases were identified by an algorithm that combined the first two approaches. Comparing each approach to the OCR, we calculated the expected value and 95% confidence interval (CI) of the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We also compared the event dates using each approach with those recorded in the OCR. RESULTS: Among a total of 12 060 837 patients in Ontario administrative health data sources, 13 999 incident pancreatic cancer cases were identified in the OCR. Sensitivity ranged from 72.5% (algorithm) to 97.5% (any diagnosis), and PPV ranged from 38.4% (any diagnosis) to 78.9% (any inpatient diagnosis). Specificity and NPV were ~100% for all approaches. The median absolute difference in cancer event date ranged 0 to 15 days. The any inpatient diagnosis method had the highest PPV (78.9%; 95% CI: 78.2-79.5%) and moderate sensitivity (86.6%; 95% CI: 86.0-87.2%). CONCLUSION: Inpatient diagnoses of pancreatic cancer in Ontario administrative heath data are suitable for pancreatic cancer case identification.

The systemic inflammatory response following hand instrumentation versus ultrasonic instrumentation-A randomized controlled trial.

OBJECTIVE: This study sought to investigate whether the immediate systemic inflammatory response following full-mouth debridement differs following use of hand compared with ultrasonic instruments. METHODS: Thirty-nine periodontitis patients were randomized to treatment with full-mouth debridement using either hand or ultrasonic instrumentation completed within 24 hr. Serum and periodontal clinical parameters were collected at baseline, day 1, day 7 and day 90 post-treatment. Differences in systemic inflammatory markers were assessed using general linear models at each timepoint, corrected for age, gender, smoking status, body mass index and baseline levels of each marker. RESULTS: Across all patients, serum C-reactive protein increased at day 1, with no differences between hand and ultrasonic groups (p(adjusted) = .22). There was no difference between groups in interleukin-6 (p(adjusted) = .29) or tumour necrosis factor α (p(adjusted) = .53) at day 1. Inflammatory markers returned to baseline levels by day 7. Treatment resulted in equal and marked improvements in clinical parameters in both groups; however, total treatment time was on average shorter for ultrasonic instruments (p(adjusted) = .002). CONCLUSIONS: Ultrasonic instrumentation resulted in shorter treatment time with comparable clinical outcomes. Levels of serum C-reactive protein at day 1 were similar following debridement with hand or ultrasonic instruments.

Association Between Surgical Approach and Major Surgical Complications in Patients Undergoing Total Hip Arthroplasty.

Importance: Controversy exists about the preferred surgical approach for total hip arthroplasty (THA). Objective: To determine whether an anterior approach is associated with lower risk of complications than either a lateral or posterior approach. Design, Setting, and Participants: Population-based retrospective cohort study of all adults in Ontario, Canada, who had undergone primary THA for osteoarthritis between April 1, 2015, and March 31, 2018. All patients were followed up over a 1-year period (study end date, March 31, 2019). Exposures: Surgical approach (anterior vs lateral/posterior) for THA. Main Outcomes and Measures: Major surgical complications within 1 year (composite of deep infection requiring surgery, dislocation requiring closed or open reduction, or revision surgery). Outcomes were compared among propensity-score matched groups using Cox proportional hazards regression. Results: Of the 30 098 patients (mean [SD] age, 67 years [10.7 years]; 16 079 women [53.4%]) who underwent THA, 2995 (10%) underwent the anterior approach; 21 248 (70%), the lateral approach; and 5855 (20%) the posterior approach performed at 1 of 73 hospitals by 1 of 298 surgeons. All patients were followed up for 1 year. Compared with those undergoing the lateral or posterior approach, patients undergoing an anterior approach were younger (mean age, 65 vs 67 years; standardized difference, 0.17); had lower rates of morbid obesity (4.8% vs 7.6%; standardized difference, 0.12), diabetes (14.2% vs 19.9%; standardized difference, 0.15), and hypertension (53.4% vs 62.9%; standardized difference, 0.19); and were treated by higher-volume surgeons (median range, 111 procedures; interquartile range, 69-172 vs 77 procedures, interquartile range, 50-119 in the prior year; standardized difference, 0.55). Compared with 2993 propensity-score matched patients undergoing a lateral or posterior approach, the 2993 matched patients undergoing anterior approaches had a significantly greater risk of a major surgical complication (61 patients [2%] vs 29 patients [1%]; absolute risk difference, 1.07%; 95% CI, 0.46%-1.69%; hazard ratio, 2.07; 95% CI, 1.48 to 2.88). Conclusions and Relevance: Among patients undergoing total hip arthroplasty, an anterior surgical approach compared with a posterior or lateral surgical approach was associated with a small but statistically significant increased risk of major surgical complications. The findings may help inform decisions about surgical approach for hip arthroplasty, although further research is needed to understand pain and functional outcomes.

Accumulation of Silver in Yellow Perch ( Perca flavescens) and Northern Pike ( Esox lucius) From a Lake Dosed with Nanosilver.

A total of 15 kg of silver nanoparticles (AgNPs) was added continuously over two ice-free field seasons to a boreal lake (i.e., Lake 222) at the IISD Experimental Lakes Area in Canada. We monitored the accumulation of silver (Ag) in the tissues of yellow perch ( Perca flavescens) and northern pike ( Esox lucius) exposed to the AgNPs under environmentally relevant conditions. The greatest accumulation was observed in the liver tissues of pike, and a single pike sampled in the second year of additions had the highest concentration observed in liver of 5.1 micrograms per gram of wet weight. However, the Ag concentrations in gill and muscle tissue of both pike and perch did not exceed 0.35 micrograms per gram of wet weight. Following additions of AgNP, the Ag residues in fish tissues declined, with a half-life of Ag in pike liver of 119 days. Monitoring using passive sampling devices and single-particle inductively coupled plasma mass spectrometry during the AgNP addition phase confirmed that Ag nanoparticles were present in the water column and that estimated mean concentrations of Ag increased over time to a maximum of 11.5 µg/L. These data indicate that both a forage fish and a piscivorous fish accumulated Ag in a natural lake ecosystem dosed with AgNPs, leading to Ag concentrations in some tissues of the piscivorous species that were 3 orders of magnitude greater than the concentrations in the water.

Chronic and pulse exposure effects of silver nanoparticles on natural lake phytoplankton and zooplankton.

The increasing use of silver nanoparticles (AgNPs) in consumer products raises concerns regarding the environmental exposure and impact of AgNPs on natural aquatic environments. Here, we investigated the effects of environmentally relevant AgNP concentrations on the natural plankton communities using in situ enclosures. Using twelve lake enclosures, we tested the hypotheses that AgNP concentration, dosing regimen, and capping agent (poly-vinyl pyrrolidone (PVP) vs. citrate) exhibit differential effects on plankton communities. Each of the following six treatments was replicated twice: control (no AgNPs added), low, medium, and high chronic PVP treatments (PVP-capped AgNPs added continuously, with target nominal concentrations of 4, 16, and 64 µg/L, respectively), citrate treatment (citrate-capped AgNPs added continuously, target nominal concentrations of 64 µg/L), and pulse treatment (64 µg/L PVP-AgNPs added as a single dose). Although Ag accumulated in the phytoplankton, no statistically significant treatment effect was found on phytoplankton community structure or biomass. In contrast, as AgNP exposure rate increased, zooplankton abundance generally increased while biomass and species richness declined. We also observed a shift in the size structure of zooplankton communities in the chronic AgNP treatments. In the pulse treatments, zooplankton abundance and biomass were reduced suggesting short periods of high AgNP concentrations affect zooplankton communities differently than chronic exposures. We found no evidence that capping agent affected AgNP toxicity on either community. Overall, our study demonstrates variable AgNP toxicity between trophic levels with stronger AgNP effects on zooplankton. Such effects on zooplankton are troubling and indicate that AgNP contamination could affect aquatic food webs.

Secondary Alveolar Bone Grafting (CLEFTSiS) 2007-2010.

Objective : To determine whether alveolar bone graft outcomes for unilateral and bilateral cleft lip and palate patients have continued to improve since the reorganization of cleft services in Scotland in 2000. Design : Retrospective analysis of postoperative anterior occlusal radiographs. Patients and Participants : Eighty-one of 106 patients who were eligible for alveolar bone grafting between 2007 and 2010 had suitable postoperative radiographs available. Interventions : Twenty-seven percent of the patients (n = 22) had presurgical orthodontic intervention. All patients underwent alveolar bone grafting with bone harvested from the iliac crest. Main Outcome Measures : The Kindelan bone-fill index was used to evaluate success. Weighted kappa statistics were used to assess intra- and interobserver reproducibility. A comparison was made with results from 2000 to 2004 to assess any improvement. Chi-square tests (or Fisher exact test) were used to determine whether outcomes differed depending on the laterality of the cleft, use of presurgical expansion, or age at bone grafting. Results : Interobserver scoring agreement was good (weighted kappa = .383). Intraobserver reproducibility was greater (weighted kappas of .835 and .620). Success was achieved in 99% of bone grafts, compared with 76% in the period from 2000 to 2004 (P < .001). There was no statistically significant relationship between the laterality of the cleft (P = 1.000), use of presurgical expansion (P = 1.000), or age at time of bone grafting and outcome (P = .259). Conclusion : Scottish secondary alveolar bone graft outcomes improved during 2007 to 2010 in comparison to the 2000 to 2004 results.

Secondary Alveolar Bone Grafting (CLEFTSiS) 2007-2010.

Objective To determine whether alveolar bone graft outcomes for unilateral and bilateral cleft lip and palate patients have continued to improve since the reorganization of cleft services in Scotland in 2000. Design Retrospective analysis of postoperative anterior occlusal radiographs. Patients and Participants Eighty-one of 106 patients who were eligible for alveolar bone grafting between 2007 and 2010 had suitable postoperative radiographs available. Interventions Twenty-seven percent of the patients (n = 22) had presurgical orthodontic intervention. All patients underwent alveolar bone grafting with bone harvested from the iliac crest. Main Outcome Measures The Kindelan bone-fill index was used to evaluate success. Weighted kappa statistics were used to assess intra- and interobserver reproducibility. A comparison was made with results from 2000 to 2004 to assess any improvement. Chi-square tests (or Fisher exact test) were used to determine whether outcomes differed depending on the laterality of the cleft, use of presurgical expansion, or age at bone grafting. Results Interobserver scoring agreement was good (weighted kappa = .383). Intraobserver reproducibility was greater (weighted kappas of .835 and .620). Success was achieved in 99% of bone grafts, compared with 76% in the period from 2000 to 2004 (P < .001). There was no statistically significant relationship between the laterality of the cleft (P = 1.000), use of presurgical expansion (P = 1.000), or age at time of bone grafting and outcome (P = .259). Conclusion Scottish secondary alveolar bone graft outcomes improved during 2007 to 2010 in comparison to the 2000 to 2004 results.

Crystal structure of a novel two domain GH78 family α-rhamnosidase from Klebsiella oxytoca with rhamnose bound.

The crystal structure of the GH78 family α-rhamnosidase from Klebsiella oxytoca (KoRha) has been determined at 2.7 Å resolution with rhamnose bound in the active site of the catalytic domain. Curiously, the putative catalytic acid, Asp 222, is preceded by an unusual non-proline cis-peptide bond which helps to project the carboxyl group into the active centre. This KoRha homodimeric structure is significantly smaller than those of the other previously determined GH78 structures. Nevertheless, the enzyme displays α-rhamnosidase activity when assayed in vitro, suggesting that the additional structural domains found in the related enzymes are dispensible for function.

Prescription Stimulant Use and Hospitalization for Psychosis or Mania: A Population-Based Study.

Small studies suggest that prescription stimulants can precipitate psychosis and mania. We conducted a population-based case-crossover study to examine whether hospitalization for psychosis or mania was associated with initiation of stimulant therapy. Between October 1, 1999 and March 31, 2013, we studied 12,856 young people who received a stimulant prescription and were subsequently hospitalized for psychosis or mania. Of these, 183 commenced treatment during 1 of 2 prespecified 60-day intervals (defined as the "risk interval" and "control interval," respectively) prior to admission. We found that stimulant initiation was associated with an increased risk of hospitalization for psychosis or mania in the subsequent 60 days (odds ratio, 1.86; 95% confidence interval, 1.39-2.56). The risk was marginally higher in patients treated with antipsychotic drugs (odds ratio, 2.06; 95% confidence interval, 1.38-3.28), but remained in patients with no such history (odds ratio, 1.66; 95% confidence interval, 1.09-2.66). One third of subjects received another stimulant prescription after hospital discharge. Of these, 45% were readmitted with psychosis or mania shortly thereafter. We conclude that initiation of prescription stimulants is associated with an increased risk of hospitalization for psychosis or mania. Resumption of therapy is common, which may reflect a lack of awareness of the potential causative role of these drugs.

The Use of Intraosseous Fluid Resuscitation in a Pediatric Patient with Ebola Virus Disease.

BACKGROUND: Vomiting, diarrhea, and severe dehydration are common manifestations of Ebola virus disease (EVD), leading to its high mortality. Mortality is especially high in patients older than 45 years, younger than 5 years, and in pregnant women and their fetuses. The majority of patients with EVD are not able to tolerate the quantities of oral hydration solutions necessary to rehydrate properly. Although some have speculated that IV and intraosseous lines are not practical in the austere, resource-constrained settings of an Ebola treatment unit during an epidemic, it is necessary to provide parenteral fluids and electrolyte replacements to significantly decrease mortality. Due to the inability to spend long periods of time working in hot environments wearing personal protective equipment, it is necessary to maximize the use of rapidly obtainable and safe parenteral access. CASE REPORT: The authors present a case of a 9-month-old patient with EVD in Sierra Leone in whom an intraosseous line was lifesaving. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians respond to international crises, such as the most recent Ebola epidemic in West Africa. It is important for such responders, as well as their responding organizations, to know and understand that intraosseous access is an important and safe modality to use in patients with EVD and in the austere settings often found in disaster settings.

Rheumatoid Arthritis Surveillance in Ontario: Monitoring the Burden, Quality of Care and Patient Outcomes through Linkage of Administrative Health Data.

Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease. Using the Ontario administrative health data housed at the Institute for Clinical Evaluative Sciences, researchers have quantified the population-level burden and epidemiology of RA, mapped its geographic distribution in relation to rheumatologist supply, studied trends in access to rheumatology care and treatment and evaluated patient outcomes. The findings highlight the excess morbidity and mortality associated with the growing burden of RA in the face of a strained rheumatology supply, and raise urgent questions about how best to meet the needs of Ontarians with RA.

Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems.

Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities.

Association between angiotensin converting enzyme inhibitor or angiotensin receptor blocker use prior to major elective surgery and the risk of acute dialysis.

BACKGROUND: Some studies but not others suggest angiotensin converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB) use prior to major surgery associates with a higher risk of postoperative acute kidney injury (AKI) and death. METHODS: We conducted a large population-based retrospective cohort study of patients aged 66 years or older who received major elective surgery in 118 hospitals in Ontario, Canada from 1995 to 2010 (n = 237,208). We grouped the cohort into ACEi/ARB users (n = 101,494) and non-users (n = 135,714) according to whether the patient filled at least one prescription for an ACEi or ARB (or not) in the 120 days prior to surgery. Our study outcomes were acute kidney injury treated with dialysis (AKI-D) within 14 days of surgery and all-cause mortality within 90 days of surgery. RESULTS: After adjusting for potential confounders, preoperative ACEi/ARB use versus non-use was associated with 17% lower risk of post-operative AKI-D (adjusted relative risk (RR): 0.83; 95% confidence interval (CI): 0.71 to 0.98) and 9% lower risk of all-cause mortality (adjusted RR: 0.91; 95% CI: 0.87 to 0.95). Propensity score matched analyses provided similar results. The association between ACEi/ARB and AKI-D was significantly modified by the presence of preoperative chronic kidney disease (CKD) (P value for interaction < 0.001) with the observed association evident only in patients with CKD (CKD - adjusted RR: 0.62; 95% CI: 0.50 to 0.78 versus No CKD: adjusted RR: 1.00; 95% CI: 0.81 to 1.24). CONCLUSIONS: In this cohort study, preoperative ACEi/ARB use versus non-use was associated with a lower risk of AKI-D, and the association was primarily evident in patients with CKD. Large, multi-centre randomized trials are needed to inform optimal ACEi/ARB use in the peri-operative setting.

Low-level experimental selenite additions decrease mercury in aquatic food chains and fish muscle but increase selenium in fish gonads.

We investigated whether low-level addition of selenium (Se) could decrease mercury (Hg) in freshwater fish without imposing Se toxicity. Using a regression design, selenite was added to large mesocosms in a lake to achieve target concentrations ≤1.6 µg/L. (198)Hg (spike Hg) was added to mesocosms to determine changes in Hg bioaccumulation. Adding Se decreased spike total Hg (THg) in fish muscle, ambient THg in fish liver, and bioaccumulation of spike THg in muscle and spike methylmercury (MeHg) in zooplankton and Chironomid larvae relative to controls. Se decreased Hg in the food web but not in water, indicating that the dominant effect of Se on Hg cycling occurs in the food web. Concentrations of Se in gonads of fish were positively correlated with Se concentrations in water but did not exceed reproductive toxicity thresholds after 8 weeks. We conclude that low-level addition of Se decreases MeHg bioaccumulation and increases Se in gonads of fish; however, additions of Se to freshwater systems to decrease Hg in fish should be treated with caution because Se in fish gonads were likely to exceed toxic concentrations if exposed to increased Se for a longer period of time.