Search

Interleukin 32 (IL-32) is a potent multi-isoform proinflammatory cytokine, which is upregulated in people with HIV (PWH) and is associated with cardiovascular disease (CVD) risk. However, the impact of IL-32 isoforms on CD4 T-cell cardiotropism, a mechanism potentially contributing to heart inflammation, remains unknown. Here we show that IL-32 isoforms β and γ induce the generation of CCR4+CXCR3+ double positive (DP) memory CD4 T-cell subpopulation expressing the tyrosine kinase receptor c-Met, a phenotype associated with heart-homing of T cells. Our ex vivo studies on PWH show that the frequency of DP CD4 T cells is significantly higher in individuals with, compared to individuals without, subclinical atherosclerosis and that DP cells from antiretroviral-naive and treated individuals are highly enriched with HIV DNA. Together, these data demonstrate that IL-32 isoforms have the potential to induce heart-homing of HIV-infected CD4 T cells, which may further aggravate heart inflammation and CVD in PWH. [ABSTRACT FROM AUTHOR]

Aluminum (Al) may play a role in the ocean's capacity for absorbing atmospheric CO2 via influencing carbon fixation, export, and sequestration. Aluminum fertilization, especially in iron (Fe)‐limited high‐nutrient, low‐chlorophyll ocean regions, has been proposed as a potential CO2 removal strategy to mitigate global warming. However, how Al addition would influence the solubility and bioavailability of Fe as well as the physiology of Fe‐limited phytoplankton has not yet been examined. Here, we show that Al addition (20 and 100 nM) had little influence on the Fe solubility in surface seawater and decreased the Fe bio‐uptake by 11–22% in Fe‐limited diatom Thalassiosira weissflogii in Fe‐buffered media. On the other hand, the Al addition significantly increased the rate of chlorophyll biosynthesis by 45–60% for Fe‐limited T. weissflogii and 81–102% for Fe‐limited Thalassiosira pseudonana, as well as their cell size, cellular chlorophyll content, photosynthetic quantum efficiency (Fv/Fm) and growth rate. Under Fe‐sufficient conditions, the Al addition still led to an increased growth rate, though the beneficial effects of Al addition on chlorophyll biosynthesis were no longer apparent. These results suggest that Al may facilitate chlorophyll biosynthesis and benefit the photosynthetic efficiency and growth of Fe‐limited diatoms. We speculate that Al addition may enhance intracellular Fe use efficiency for chlorophyll biosynthesis by facilitating the superoxide‐mediated intracellular reduction of Fe(III) to Fe(II). Our study provides new evidence and support for the iron–aluminum hypothesis. [ABSTRACT FROM AUTHOR]

Despite the growing prevalence of Bismuth (Bi), very little research has been carried to assess its potential toxic effects on aquatic organisms. This study aimed to address this gap by investigating the interactive effects of Bi exposure and elevated temperature on freshwater snails of the genus Lymnaea, specifically on their fatty acid (FA) profiles, oxidative stress markers (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST)) and lipid peroxidation (malondialdehyde (MDA) content). Bismuth exposure was introduced through two distinct routes: i) food via Bi-exposed biofilm (grown under 2 µM Bi), and ii) water (2 µM Bi). Exposed snails were maintained at two temperatures, 19°C and 25°C, over a duration of 14 days. Bismuth bioaccumulation occurred in Bi-exposed biofilm concurrently with a pronounced increase in polyunsaturated fatty acids (PUFA), likely as a protective mechanism to preserve cell structure and integrity. Bismuth bioaccumulation also occurred in snails with their FA composition largely reflecting the composition of their dietary source highlighting the direct link between diet and snail FA profiles. Additionally, the antioxidant enzymes studied exhibited diverse responses under Bi exposure and thermal stress, suggesting the induction of oxidative stress in snails. SOD activity increased at 25°C, suggesting a thermal stress. CAT activity remained high under all conditions, unaffected by temperature or Bi exposure. GPx levels increased in snails fed with Bi-laden biofilm, particularly at 19°C. GST activity showed great variability with a significant three-way interaction. The observed elevation in MDA levels among Bi-exposed snails suggested a potential deficiency in their antioxidant enzyme systems, leading to an increased susceptibility to lipid peroxidation. This research highlights the complex interaction between Bi contamination, temperature, and the physiological responses of aquatic organisms, and reveals the need for future research into the environmental impact of Bi in aquatic ecosystems. We further highlight the importance of food for Bi transfer to higher consumers and the importance of considering dietborne exposures in ecotoxicological studies. [ABSTRACT FROM AUTHOR]

Metal bioavailability in solution is mostly driven by two factors: complexation and competition. The first factor, complexation, contributes to decrease the overall reactivity of the metal by reducing the activity of the free metal ion, which is known as the common denominator of metal reactions involving either dissolved ligands or surface functional groups (abiotic or biotic). Ubiquitous in natural ecosystems, natural organic matter is, for several metals, the most important metal complexing ligand. The second factor, competition, contributes to decrease the availability of biotic ligands involved in the membrane transport of metals from the bulk solution to the intracellular medium. In freshwater systems, proton and hardness cation concentrations are the main parameters potentially modulating metal bioavailability. The above reflects the current accepted paradigm. In this paper, two knowledge gaps are identified: i) the role of natural organic matter other than metal complexation that may lead to an increase in metal bioavailability; and ii) the effects of multiple metals other than competition that may trigger biological feedback mechanisms which may, in turn, alter biotic ligand binding properties. More research efforts are needed to decipher the extent of these overlooked potential effects and to improve the predictability of metal bioavailability. [ABSTRACT FROM AUTHOR]

Natural dissolved organic matter (DOM) is a heterogeneous mixture of a variety of organic compounds, with a great importance for the environmental fate of metals and their ecotoxicity. However, its complex nature and variable composition make the understanding of its role a challenge. Lanthanum (La) has a strong affinity for DOM and is one of the rare earth elements that is widely used in many electronic and green technologies, and for which the demand may potentially increase for the foreseeable future. The present study examines the links between the optical and chemical properties of organic matter and its influence on the bioavailability and toxicity of La toward the green microalga Chlorella fusca. A total of four DOMs, two natural organic matter samples from Ontario (Luther Marsh and Bannister Lake) and two Suwannee River fulvic and humic acids, were characterized by absorbance and fluorescence spectroscopy as well as by asymmetrical flow field-flow fractionation. These suggest that Luther Marsh and the Suwannee River humic acid have higher molecular weight and are more aromatic, compared to the other two DOMs. The concentrations of free metal iosn La3+ were measured by an ion exchange technique and a partial ultrafiltration method, and related to biological response. Toxicity tests over 96 h at pH = 5.0 were separately conducted with and without 3mgC·L-1 of each DOM. All DOM samples reduced La bioavailability but as opposed to what can be expected based on the Biotic Ligand Model, the presence of DOM exacerbated the toxicity of La and its accumulation in algal cells when only the free La3+ ion concentration was considered. These results indicate that the role of natural organic matter in modulating metal bioavailability remains to be deciphered. [ABSTRACT FROM AUTHOR]

Environmental context: Natural dissolved organic matter strongly influences the biogeochemistry and bioavailability of trace metals in natural waters. Chemical equilibrium models are often used to predict the relative importance of the free metal cation, a recognised indicator of the metal's bioavailability. Here we show how the nature of the organic matter varies between two lakes, affecting the measured speciation of copper and nickel, a result that challenges existing chemical equilibrium models. Rationale: Thermodynamic models such as the Windermere Humic Aqueous Model (WHAM) are often used to estimate the binding of cations by dissolved organic matter (DOM) in natural aquatic systems. Such models require as input data the quantity of DOM but do not consider its quality. Using two well-characterised lakewater samples, we demonstrate, for realistic environmental conditions, that the conditional binding parameters for the complexation of Ni and Cu with natural DOM vary between lakes and we relate these differences to the spectroscopic quality of the DOM. Methodology: Waters from two lakes with contrasting types of DOM were titrated with Cu and Ni and the conditional binding parameters were calculated using a two-site ligand model, with associated conditional stability constants implemented in PHREEQC v.3.1.2, and compared between lakes and between metals. The titration curves for each lake were compared to those predicted by WHAM v7.05. Results: Binding affinities and capacities of DOM for Cu and Ni were found to differ not only between metals, but also between lakes. Discussion: Overall, the titration results suggest that the more aromatic humic-like DOM from allochthonous sources may have a significantly higher complexation affinity for Ni than the more protein-like DOM from autochthonous sources. The differing behaviour of Ni and Cu in the two lakes suggests that they are binding to different types of binding sites within the DOM matrix. More data with various natural DOM samples are needed to capture the diversity of metal–DOM interactions and to improve our ability to predict metal speciation in natural waters. Environmental context. Natural dissolved organic matter strongly influences the biogeochemistry and bioavailability of trace metals in natural waters. Chemical equilibrium models are often used to predict the relative importance of the free metal cation, a recognised indicator of the metal's bioavailability. Here we show how the nature of the organic matter varies between two lakes, affecting the measured speciation of copper and nickel, a result that challenges existing chemical equilibrium models. This article belongs to the collection Dedication to Prof. Edward Tipping. [ABSTRACT FROM AUTHOR]

Background: The bacteria Mycoplasma genitalium has been identified as a causative agent of urethritis in men, especially in gay, bisexual and other men who have sex with men (gbMSM). Canadian clinic-based data have identified a high prevalence of M. genitalium and resistance to antibiotic treatments. This article estimates the prevalence of M. genitalium infections among Montréal gbMSM, explores correlates for M. genitalium infection and estimates the prevalence of mutations associated with antimicrobial resistance (AMR). Methods: Engage Cohort Study is a multi-site longitudinal study on sexually active gbMSM, aged 16 years and older, recruited via respondent-driven sampling in Montréal, Toronto and Vancouver. Participants completed a questionnaire on behaviour and were tested for sexually transmitted and blood-borne infections at each visit. For this sub-study, Montréal participants with a follow-up visit that occurred between November 2018 and November 2019 were included. Results: A total of 2,064 samples were provided by 716 participants. Prevalence of M. genitalium infection was 5.7% at rectal and/or urethral sites, 4.0% at rectal site and 2.2% at urethral site. Correlates for M. genitalium infection were younger age and reporting six or more sexual partners in the past six months. Prevalence of macrolide resistance associated mutations (MRAM), quinolone resistance associated mutations (QRAM) and either MRAM or QRAM, was 82%, 29% and 85%, respectively. Conclusion: This first population-based study among gbMSM in Canada documents a high prevalence of urethral and rectal M. genitalium infection and high levels of AMR. Our results highlight the importance of access to testing and AMR detection when indicated. [ABSTRACT FROM AUTHOR]

Recent studies suggest aluminum (Al) likely plays a role in the ocean carbon cycle by altering the biological carbon fixation and carbon decomposition of marine diatoms. However, it remains speculative whether Al has similar effects on other ecologically important phytoplankton groups such as the globally important nitrogen-fixing cyanobacterium, Trichodesmium. Here we report the influence of Al on carbon fixation and decomposition in non-axenic cultures of Trichodesmium erythraeum IMS101 (CCMP 1985). By using radiocarbon, and adding oceanic relevant amounts of dissolved Al (yielding concentrations of 40 and 200 nM) along with non-Al-amended controls, we investigated the changes in particulate organic carbon (POC) of Trichodesmium (> 2 μm, Trichodesmium POC), and free-living bacteria (0.2–2 μm, bacterial POC), and dissolved organic carbon (< 0.2 μm, DOC) over a 116-day growth period. The results showed that the rates of increase of POC in the declining growth phase of T. erythraeum were significantly higher (by 11–14%) in the Al-enriched treatments than in the control, and this Al-enhanced carbon fixation is consistent with previous observations on marine diatoms. On the other hand, unlike diatoms, the POC from T. erythraeum decomposed faster in the Al-enriched treatments during the first decay phase when bacterial POC and DOC increased along with the decomposition of Trichodesmium POC. Further addition of the same amounts of Al (again calculated to increase the Al concentration by 40 and 200 nM) was performed on day 71. This treatment was designed to mimic Al supply from sediment after the settling of Trichodesmium colonies to the ocean bottom. Following this second addition, the decomposition rate of both Trichodesmium POC and DOC slowed down by 20–27% and 31–62%, respectively, during the second decay phase, when DOC and bacterial POC decreased. The study suggests that Al fertilization in the surface ocean via dust deposition may increase the net carbon fixation and associated nitrogen fixation by Trichodesmium, and thus the supply of new nitrogen to the euphotic zone, whereas Al from sediment may decrease the decomposition rate of decaying Trichodesmium settled to the ocean bottom. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fluorosis is an endemic disease due to an excess of fluoride intake via drinking water. In some regions of the world, removing fluoride from drinking water is a severe problem that is still to be solved. The present study focuses on the use of a natural clay to reduce fluoride concentration in Tunisian contaminated drinking water under relevant working conditions. RESULTS: Adsorption experiments were performed in batches using a fluoride aqueous solution. The Box–Behnken model design was used to define the working conditions in which three factors were controlled: clay dosage, contact time and agitation speed. The fixed parameters were the initial fluoride concentration and water pH as observed in Metlaoui, Tunisia in 2021, and experiments were performed at room temperature. Results show that 4 g(50 mL)−1 of clay dosage, 10 min of contact time and 280 rpm of agitation speed could provide 51% fluoride removal using an untreated natural clay. Then, various adsorbents based on this clay were synthesized (chitosan–clay, C6H17NO3Si–clay and thermally treated clays purified using different methods) and tested using the same approach. Among the adsorbents tested, the thermally treated purified clays were the most effective in removing fluoride under ambient conditions with a fluoride removal of 97.5%. Tests performed on drinking water showed that the safety fluoride concentration could be achieved without modifications of the water pH. CONCLUSIONS: The thermally treated clays investigated in this study were effective for fluoride removal under relevant conditions, which can pave the way for future field applications. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Background: Tecovirimat (TCV, TPOXX®) is an orthopox-specific antiviral drug indicated for the treatment of smallpox. There is also a mechanistic basis for its use in mpox infection. However, its approval was based on animal studies, and its efficacy and side-effect profile in human patients with disease is unknown. Methods: During the 2022 international mpox epidemic, clinicians in Canada were permitted by Health Canada to access TCV for severe cases of mpox disease. We describe the use of TCV in nine adults with severe mpox virus infection in Montréal, Canada. Results: Five patients were treated for severe and potentially life-threatening head and neck symptoms, while four were treated for genitourinary or anorectal disease. Two-thirds of patients were also treated for suspected bacterial superinfection. All patients recovered (median time to resolution of severe symptoms: nine days) without relapse or hospital readmission. No patients reported adverse events attributable to TCV and no patients stopped their treatment early. Conclusion: Our experience suggests that TCV is well tolerated and may accelerate recovery in severe cases. These preliminary, observational data may also be explained by concomitant treatment for superinfection and are limited by the absence of a control group. Controlled, clinical trials should be conducted to clarify the attributable benefit of TCV in severe mpox infection. [ABSTRACT FROM AUTHOR]

Whereas metal impacts on fluvial communities have been extensively investigated, effects of abiotic parameters on community responses to contaminants are poorly documented. Variations in photoperiod and temperature commonly occur over the course of a season and could affect aquatic biofilm communities and their responses to contaminants. Our objective was to characterize the influence of environmental conditions (photoperiod and temperature) on nickel (Ni) bioaccumulation and toxicity using a laboratory‐grown biofilm. Environmental parameters were chosen to represent variations that can occur over the summer season. Biofilms were exposed for 7 days to six dissolved Ni treatments (ranging from 6 to 115 µM) at two temperatures (14 and 20 °C) using two photoperiods (16:8 and 12:12‐h light:dark cycle). Under these different scenarios, structural (dry weight biomass and chlorophyll‐a) and functional biomarkers (photosynthetic yield and Ni content) were analyzed at four sampling dates, allowing us to evaluate Ni sensitivity of biofilms over time. The results highlight the effects of temperature on Ni accumulation and tolerance of biofilms. Indeed, biofilms exposed at 20 °C accumulated 1.6–4.2‐fold higher concentrations of Ni and were characterized by a lower median effect concentration value using photosynthetic yield compared with those exposed at 14 °C. In terms of photoperiod, significantly greater rates of Ni accumulation were observed at the highest tested Ni concentration for biofilms exposed to a 12:12‐h compared with a 16:8‐h light:dark cycle. Our study demonstrates the influence of temperature on biofilm metabolism and illustrates that environmental factors may influence Ni accumulation response and thus Ni responses of phototrophic biofilms. Environ Toxicol Chem 2022;41:1649–1662. © 2022 SETAC [ABSTRACT FROM AUTHOR]

Environmental context: Thiosulfate is present in natural waters, especially those influenced by sulfide oxidation, and it has a marked affinity for metals such as cadmium. Normally the binding of cadmium by thiosulfate would be expected to reduce the metal's bioavailability. However, here we demonstrate that algal uptake of cadmium is enhanced in the presence of thiosulfate, indicating that Cd can enter the alga via a novel route as an intact Cd-thiosulfate complex. Rationale: For a given free metal ion activity in the exposure solution, the Biotic Ligand Model assumes that metal uptake will be independent of the various ligands present in solution that are buffering [M z +]. In this context, we have evaluated cadmium bioavailability in the absence or presence of thiosulfate, using Chlamydomonas reinhardtii as the test alga. Methodology: Short-term exposures (≤41 min) were run with a fixed concentration of the free Cd2+ ion (3.0 ± 0.1 nM), buffered with either nitrilotriacetate or thiosulfate, to determine Cd uptake. Subsequent long-term exposures (72 h) over a range of free Cd2+ concentrations were used to determine the effects of Cd on algal growth. Results: Contrary to Biotic Ligand Model predictions, Cd uptake was enhanced when Cd2+ was buffered with thiosulfate. Removal of sulfate from this exposure medium increased Cd uptake; conversely, if [SO42−] was increased, Cd uptake decreased. In the absence of thiosulfate, Cd uptake was unaffected by changes in [SO42−]. In the long-term exposures, the cellular Cd quota needed to reduce algal growth by 50% was significantly higher in the presence of thiosulfate than in its absence. Discussion: In the presence of thiosulfate, Cd can enter the algal cell not only by cation transport but also by transport of the intact Cd-thiosulfate complex via the anion transporter responsible for sulfate uptake. We speculate that some of the Cd taken up by anion transport remains in complexed form and is less bioavailable than the Cd that enters the cell via cation transport. Environmental context. Thiosulfate is present in natural waters, especially those influenced by sulfide oxidation, and it has a marked affinity for metals such as cadmium. Normally the binding of cadmium by thiosulfate would be expected to reduce the metal's bioavailability. However, here we demonstrate that algal uptake of cadmium is enhanced in the presence of thiosulfate, indicating that Cd can enter the alga via a novel route as an intact Cd-thiosulfate complex. [ABSTRACT FROM AUTHOR]

Environmental context: The growth in demand for platinum has led to an increase in the presence of this metal in the environment but little is known about its toxicity to aquatic organisms. The presence of organic matter should contribute to decreasing metal bioavailability but the opposite was found for platinum. How ubiquitous natural organic matter can alter the accumulation and effects of platinum group elements remains to be fully elucidated. Rationale: There is a growing interest for platinum in ecotoxicology, mainly because of its use in automobile exhaust catalysts. When it reaches aquatic ecosystems, platinum can interact with ligands such as natural organic matter. According to the Biotic Ligand Model, the formation of such complexes should reduce metal bioavailability. As a consequence, toxicity should decrease in the presence of organic matter. Methodology: This study focused on the uptake of platinum by two microalgae species (Chlorella fusca and Chlamydomonas reinhardtii) and its subsequent inhibitory effects on growth (96 h). Cells were exposed to platinum (5–300 µg L−1) at three concentrations (0, 10 and 20 mg C L−1) of standard Suwannee River humic acid (SRHA). Platinum bound to humic acid was determined experimentally using partial ultrafiltration to relate metal uptake and toxicity to speciation. Results: Unexpectedly, results show that platinum toxicity, expressed as ultrafiltrable Pt (not bound to humic acid) and total Pt concentrations, is enhanced in the presence of humic acid for both algae. For C. fusca , the half maximal effective concentration (EC50) values decreased from 93 to 37 and 35 µg L−1 of ultrafiltrable Pt in the presence of 10 and 20 mg C L−1 SRHA and from 89 to 36 and 0.31 µg L−1 for C. reinhardtii. Discussion: In contradiction with the Biotic Ligand Model, the results show that the presence of SRHA can significantly and importantly increase platinum uptake and toxicity as determined in two unicellular green algae, C. reinhardtii and C. fusca. The present work raises the issue of the impact of platinum on microalgae under realistic environmental conditions (ubiquitous presence of organic matter), primary producers being of great ecological importance. Environmental context. The growth in demand for platinum has led to an increase in the presence of this metal in the environment but little is known about its toxicity to aquatic organisms. The presence of organic matter should contribute to decreasing metal bioavailability but the opposite was found for platinum. How ubiquitous natural organic matter can alter the accumulation and effects of platinum group elements remains to be fully elucidated. [ABSTRACT FROM AUTHOR]

This article examines how governance mechanisms were put in place in three organizational transformation projects undertaken in university hospital centers. Our focus is guided by a theoretical discourse on the place of rational choices on organizational design versus the desire to imitate other organizations. The article presents two complementary points of view: a longitudinal study and a recent a posteriori reflection with five key players. A first result highlights efforts invested in the preparation stages and that these nevertheless resulted in comparable performances: hence, the concept of equifinality. However, a second result reveals complementarity between equifinality and institutional isomorphism. [ABSTRACT FROM AUTHOR]

Aquatic ecotoxicological risks associated with tetravalent metallic elements such as thorium (Th) are still poorly understood. Periphytic biofilm represents an important food source in aquatic environments; thus, such risks could severely affect nutrient and energy cycling in these ecosystems. The present study investigated the potential for Th to change the fatty acid composition of biofilm communities. Bioaccumulation of Th and fatty acids were measured after 4 wk to 2 exposure conditions: a control (C0) and Th exposure (C10). Some major fatty acids such as C16:1n‐7 and docosahexaenoic acid C22:6n‐3 differed significantly between control and C10 conditions. To determine if Th can be trophically transferred and to investigate the impacts of nutritional quality changes on primary consumers, common pond snails (Lymnaea sp.) were fed for 4 wk with control and Th‐exposed biofilm. Thorium appeared to be trophically transferable to the grazers, although we cannot exclude that part of the Th accumulated by the snails may have been taken from the water through release from the biofilms. The composition of major fatty acids observed in the grazers was also significantly affected, notably by a decrease of total polyunsaturated fatty acids. These results indicate that very low Th concentrations can decrease the nutritional quality of organisms at the base of the food chain. Environ Toxicol Chem 2021;40:2220–2228. © 2021 SETAC [ABSTRACT FROM AUTHOR]

Recent studies indicate that aluminum (Al) could play an important role in the ocean carbon cycle by increasing phytoplankton carbon fixation and reducing organic carbon decomposition. However, how Al may influence the decomposition of organic carbon has not yet been explicitly examined. Here we report the effects of Al on carbon fixation by marine diatoms and their subsequent decomposition. By using radiocarbon as a tracer, the carbon fixation and decomposition of three model marine diatoms were examined in Aquil* media at different concentrations (0, 40, 200, and 2000 nM) of dissolved Al. Addition of Al enhanced net carbon fixation by the diatoms in the declining growth phase (by 9%–29% for Thalassiosira pseudonana, 15%–20% for T. oceanica, 15%–23% for T. weissflogii). Under axenic conditions the decomposition rates (d−1) of the diatom‐produced particulate organic carbon (POC) significantly decreased (by 21%–57% for T. pseudonana, 0%–41% for T. oceanica, 29%–58% for T. weissflogii) in the Al‐enriched treatments. In the presence of bacteria, the decomposition rates of T. weissflogii‐produced POC were still 37%–38% lower in Al‐enriched treatments compared to the control. Significant increases in cell size, cellular carbon content (pmol C/cell) and cellular carbon density (pmol C/μm3) of T. weissflogii were also observed in the Al‐enriched treatments compared to the control. The Al‐related increase in net carbon fixation and cell size, and the decrease in POC decomposition rate may facilitate carbon export to ocean depths. The study provides new evidence for the iron–aluminum hypothesis, which suggests that Al could increase phytoplankton uptake of atmospheric CO2 and influence climate change. [ABSTRACT FROM AUTHOR]

Recent industrial developments have resulted in an increase in the use of so‐called technology‐critical elements (TCEs), for which the potential impacts on aquatic biota remain to be evaluated. In the present study, quantitative ion character–activity relationships (QICARs) have been developed to relate intrinsic metal properties to their toxicity toward freshwater aquatic organisms. In total, 23 metal properties were tested as predictors of acute median effect concentration (EC50) values for 12 data‐rich metals, for algae, daphnids, and fish (with and without species distinction). Simple and multiple linear regressions were developed using the toxicological data expressed as a function of the total dissolved metal concentrations. The best regressions were then tested by comparing the predicted EC50 values for the TCEs (germanium, indium, gold, and rhenium) and platinum group elements (iridium, platinum, palladium, rhodium, and ruthenium) with the few measured values that are available. The 8 "best" QICAR models (adjusted r2 > 0.6) used the covalent index as the predictor. For a given metal ion, this composite parameter is a measure of the importance of covalent interactions relative to ionic interactions. Toxicity was reasonably well predicted for most of the TCEs, with values falling within the 95% prediction intervals for the regressions of the measured versus predicted EC50 values. Exceptions included Au(I) (all test organisms), Au(III) (algae and fish), Pt(II) (algae, daphnids), Ru(III) (daphnids), and Rh(III) (daphnids, fish). We conclude that QICARs show potential as a screening tool to review toxicity data and flag "outliers," which might need further scrutiny, and as an interpolating or extrapolating tool to predict TCE toxicity. Environ Toxicol Chem 2021;40:1139–1148. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Freshwater biofilms play an important role in aquatic ecosystems and are widely used to evaluate environmental conditions. Little is known about the effects of temperature and metals on biofilm fatty acid composition. In the present study, we exposed a natural biofilm cultured in mesocosms to a gradient of nickel (Ni) concentrations at 15 and 21 °C for 28 d. Metal bioaccumulation, algal taxonomic composition, and biofilm fatty acid profiles were determined. At both temperatures, bioaccumulated Ni increased with Ni exposure concentration and reached the highest values at 25 µM Ni, followed by a decrease at 55 and 105 µM Ni. In control biofilms, palmitic acid (16:0), palmitoleic acid (16:1n7), oleic acid (18:1n9), linoleic acid (18:2n6), and linolenic acid (18:3n3) were the dominant fatty acids at 15 and 21 °C. This composition suggests a dominance of cyanobacteria and green algae, which was subsequently confirmed by microscopic observations. The increase in temperature resulted in a decrease in the ratio of unsaturated to saturated fatty acids, which is considered to be an adaptive response to temperature variation. Polyunsaturated fatty acids (PUFAs) tended to decrease along the Ni gradient, as opposed to saturated fatty acids which increased with Ni concentrations. Temperature and Ni affected differently the estimated desaturase and elongase activities (product/precursor ratios). The increase in PUFAs at 15 °C was concomitant to an increase in Δ9‐desaturase (D9D). The estimated activities of D9D, Δ12‐desaturase, and Δ15‐desaturase decreased along the Ni gradient and reflected a decline in PUFAs. The elevated estimated elongase activity reflected the observed increase in saturated fatty acids at the highest Ni exposure concentration (105 µM). Our results suggest that fatty acids could be used as an endpoint to evaluate environmental perturbations. Environ Toxicol Chem 2020;39:1566–1577. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Objectives: Assess carotid artery strain and motion in people living with HIV as markers of premature aging using ultrasound noninvasive vascular elastography (NIVE).Methods: Seventy-four HIV-infected and 75 age-matched control subjects were recruited from a prospective, controlled cohort study from October 2015 to October 2017 (mean age 56 years ± 8 years; 128 men). NIVE applied to longitudinal ultrasound images of common and internal carotid arteries quantified the cumulated axial strain, cumulated shear strain, cumulated axial translation, and cumulated lateral translations. The presence of plaque was also assessed. An association between elastography biomarkers and HIV status was evaluated with Mann-Whitney tests and multivariable linear regression models.Results: A higher occurrence of carotid artery plaques was found in HIV-infected individuals (p = 0.011). Lower cumulated lateral translations were found in HIV-infected subjects on both common and internal carotid arteries (p = 0.037 and p = 0.026, respectively). These observations remained significant when considering multivariable models including common cardiovascular risk factors and clinical characteristics (p < 0.05). Lower cumulated axial strains were also observed in internal carotid arteries when considering both multivariable models (p < 0.05).Conclusion: Lower translation and strain of the carotid artery wall in HIV-infected individuals indicates increased vessel wall stiffness. These new imaging biomarkers could be used to characterize premature atherosclerosis development.Key Points: • Noninvasive vascular elastography (NIVE) based on ultrasound imaging quantifies translations and strains of carotid arteries. • Lower translation and strain of the carotid artery wall found in HIV-infected individuals indicate premature arterial stiffening, compared with age-matched controls. • Carotid artery plaques were more prevalent in HIV-infected individuals than in control subjects. [ABSTRACT FROM AUTHOR]

The environmental risk assessment of rare earth elements (REEs) requires data on their potential toxicity. In the present study, the toxicity of lanthanum (La) and cerium (Ce) was studied in relation to metal speciation in solution. For both La and Ce, the use of organic ligands demonstrated that the calculated free ion concentration was a good indicator of toxicity. Whether in the absence or presence of organic ligands, when based on free ion concentrations, the obtained half‐maximal effective concentrations were similar. When all generated data were pooled, Ce and La showed identical toxicity thresholds after 120 h of exposure with free ion concentration–based median effective concentration values (95% confidence intervals) of 0.48 (0.38–0.60) µM and 0.47 (0.36–0.61) µM for La3+ and Ce3+, respectively. The inhibition of algal growth was also correlated with the intracellular lanthanide concentrations, regardless of the ligand used. Finally, increasing the ambient calcium concentration protected the test algae by reducing the amount of lanthanide internalized into the cells. These results suggest that, at constant pH (5.5), REE accumulation and toxicity are linked to the free ion concentration and ambient calcium concentration, as predicted by the biotic ligand model. Environ Toxicol Chem 2020;39:996–1005. © 2020 SETAC [ABSTRACT FROM AUTHOR]

This article closely examines aspects of the Virtual Museum of Canada's website A Journey into Time Immemorial to investigate the relationship between the poetics of new media and contemporary curatorial practices in Indigenous cultural heritage. In this interactive cyber museum, detailed reconstructions of a longhouse village, engaging motion graphics and video interviews with Elders are combined to represent the historical practices of Stó:l̄-Coast Salish peoples and their enduring significance today. The objective of this research is to reflect on how computational tools and spatial design were used to express temporal aspects of tangible and intangible heritage preservation and transmission. [ABSTRACT FROM AUTHOR]

Environmental Chemistry [Published 13 December 2023] doi:10.1071/EN23021The authors advise that in the Materials and methods section of the paper, there is a spelling error in the subsection title 'Speciation simulations with the Windermere Humic Acid model'.The correct title for this subsection is 'Speciation simulations with the Windermere Humic Aqueous model'.By Kristin K. Mueller; Raoul-Marie Couture; Claude Fortin and Peter G. C. CampbellReported by Author; Author; Author; Author [Extracted from the article]

Environmental context: In natural waters, the impact of metals on biota is modulated by their binding with ligands. Ion-exchange techniques can provide information about metal-ligand complexes in solution, which can be linked to metal bioavailability in natural waters. We investigate modelling approaches to interpreting data from ion-exchange experiments to help elucidate the contribution of a particular complex to the overall metal uptake. The dynamic ion exchange technique (DIET) is proposed to provide speciation information, which can be used to establish links with metal bioavailability in natural waters. The experimental setup consists of a few milligrams of a sulfonic acid type ion exchange resin packed in a plastic microcolumn that is coupled to a peristaltic pump for a sample to interact with the resin which is subsequently eluted. The evolution of both the accumulated number of moles in the resin and the concentration of the effluent can provide information on the dissociation of different metal-ligand complexes when compared with the transport properties. This information can be converted into the lability degree of a given complex or the DIET concentration c DIET, which accounts for the labile fraction contributing to the metal accumulation by the resin column at the operation conditions. c DIET can be extended to columns containing chelating resins (such as those with Chelex) or to chromatography. A comprehensive modelling of the involved phenomena (such as diffusion, advection, reaction kinetics and electrostatic partitioning) leads to the quantitative interpretation of the accumulation time series (accumulation curves) or effluent evolution (breakthrough curves). Particularly simple analytical expressions can be used for short exposure times, when a (quasi) steady-state is attained. These models have been checked against the results from complexes of Cu and Ni with ligands, such as ethylenediamine, and ethylenediaminetetraacetic, iminodiacetic, glutamic, salicylic, malonic and malic acids, which yield complexes with contrasting charges. Caution is advised when estimating the free metal fraction from DIET measurements, as c DIET and the free metal concentration can be considered to be equal only in the case of extremely inert complexes. Environmental context. In natural waters, the impact of metals on biota is modulated by their binding with ligands. Ion-exchange techniques can provide information about metal-ligand complexes in solution, which can be linked to metal bioavailability in natural waters. We investigate modelling approaches to interpreting data from ion-exchange experiments to help elucidate the contribution of a particular complex to the overall metal uptake. [ABSTRACT FROM AUTHOR]

Silver nanoparticles, used mainly for their antibacterial properties, are among the most common manufactured nanomaterials. How they interact with aquatic organisms, especially how they cross biological membranes, remains uncertain. Free Ag+ ions, released from these nanoparticles, are known to play an important role in their overall bioavailability. In this project, we have studied the uptake of dissolved and nanoparticulate silver by liposomes. These unilamellar vesicles, composed of phospholipids, have long been used as models for natural biological membranes, notably to study the potential uptake of solutes by passive diffusion through the phospholipid bilayer. The liposomes were synthesized using extrusion techniques and were exposed over time to dissolved silver under different conditions where Ag+, AgS2O3−, or AgCl0 were the dominant species. Similar experiments were conducted with the complexes HgCl20 and Cd(DDC)20, both of which are hydrophobic and known to diffuse passively through biological membranes. The uptake kinetics of Ag+, HgCl20, and Cd(DDC)20 show no increase in internalized concentrations over time, unlike AgS2O3− and AgCl0, which appear to pass through the phospholipid bilayer. These results are in contradiction with our initial hypothesis that lipophilic Hg and Cd complexes would be able to cross the membrane, whereas silver would not. Encapsulated tritiated water inside the liposomes was shown to rapidly diffuse through the lipid bilayer, suggesting a high permeability. We hypothesize that monovalent anions or complexes as well as small neutral complexes with a strong dipole can diffuse through our model membrane. Finally, liposomes were exposed to 5-nm polyvinylpyrrolidone-coated silver nanoparticles over time. No significant uptake of nanoparticulate silver was observed. Neither disruption of the membrane nor invagination of nanoparticles into the liposomes was observed. This suggests that the main risk caused by AgNPs for nonendocytotic biological cells would be the elevation of the free silver concentration near the membrane surface due to adsorption of AgNPs and subsequent oxidation/dissolution. [ABSTRACT FROM AUTHOR]

Background: Although reverse sequence algorithms (RSA) for syphilis screening are performing well, they still have to rely on treponemal confirmatory tests at least for sera reactive by enzyme immunoassay/chemiluminescence immunoassay (EIA/CIA) and unreactive by rapid plasma reagin (RPR). Quebec’s laboratory network previously showed that 3.3% of EIA/CIA reactive and weakly-reactive RPR samples (RPR titer of 1 to 4) would have been misclassified as syphilis cases if a treponemal confirmatory test had not been performed. Objectives: To correlate the magnitude of signal-to-cutoff (S/CO) ratios of the 4 most used commercial first-line EIA/CIA kits in Quebec with syphilis confirmation results and establish a S/CO value above which treponemal confirmation would not be required. Methods: Serum samples from previously undiagnosed individuals (n = 7 404) obtained between January 2014 and February 2017 that were reactive by EIA/CIA and either negative by RPR or reactive with a low titer (1 to 4) were included in the study. All samples were tested with Treponema pallidum particle agglutination (TP-PA) and, if negative or inconclusive, with a line immunoassay (LIA). Syphilis infection confirmation was defined by a reactive TP-PA or LIA. Logistic regression analysis was used to determine S/CO values (95% CI lower bound = 0.98) above which confirmation would not be required. The four kits studied were Architect TP, BioPlex IgG, Syphilis EIA II, and Trep-Sure. Results: Of 2609 reactive EIA/CIA specimens tested for the determination of S/CO values, 1730 (66%) were confirmed as true syphilis cases. Confirmation rate was significantly higher in samples with low-titer positive RPR (92%) than with negative RPR samples (54%); p<0.01. A linear probability model (95% CI lower bound = 0.98) predicted the S/CO value above which a confirmation would no longer be needed for the Architect TP (16.4), Bioplex IgG (7.4) and Trep-Sure (24.6). No linearity was observed between the S/CO value of Syphilis EIA II and the confirmation rate. The validity of the predicted S/CO values was investigated using 4 795 specimens. The use of an S/CO value of 16.4 with the Architect TP kit and of 24.6 for the Trep-Sure kit would obviate the need for confirmation of 18.5% and 13.2% of sera from the all RPR subgroup, respectively. For the BioPlex IgG kit, 81.1% of sera would not require confirmation when using the S/CO value of 7.4 in the low titer RPR subgroup. Conclusion: Signal-to-cut-off values could be used to identify sera that do not require extra treponemal confirmation for 3 of the 4 most used first-line EIA/CIA kits in Quebec. Using these values in our current reverse screening algorithm (RSA) would avoid the need for confirmatory tests in 14 to 20% of sera, a proportion that could reach 75% among low-titer RPR. [ABSTRACT FROM AUTHOR]

Abstract: The use of fractionation protocols to determine metal subcellular distribution in aquatic organisms has gained much interest over the last 15 yr, however, accurate separations among the different components of cells are challenging. Subcellular fractions separated with such an approach are operationally defined and a potentially significant difference can exist between anticipated and resulting fractions. This study customizes and validates subcellular partitioning protocols, for three different freshwater organisms representing a diversity of challenges for subcellular fractionation: Daphnia magna, Chironomus riparius, and liver of Oncorhynchus mykiss. Several protocols involving different homogenization methods, centrifugation speeds, or conservation conditions were tested, and their efficiencies were assessed using enzymatic biomarker assays. Our work allowed us to identify critical steps to improve separations. First, for D. magna, a crustacean with a reinforced chitinous exoskeleton, the use of a strong homogenization method using a sonicator is necessary. Second, for both invertebrates, we observed the leaking of the mitochondrial matrix during cell fractionation, regardless of the homogenization strength and conservation conditions. Therefore, we propose that the mitochondria fraction should be referred to as the mitochondrial membrane fraction, and the cytosol fraction should be identified as the cytosol and mitochondrial matrix fraction. Third, the presence of a lipid‐rich layer during O. mykiss liver fractionation may lead to an overlap between mitochondria and cytosol and must be considered in the protocol development. Finally, lysosomes should not be pooled with the microsomes fraction without prior validation. Overall, this study provides a benchmark for future methodological studies on similar taxa. [ABSTRACT FROM AUTHOR]

The impact of cadmium on the diatom Nitzschia palea (Kützing) W. Smith 1856 was studied by examining the relation between valve deformities and response through biological processes and genetic expression. Cultures of N. palea were exposed to two Cd treatments (C1 = 2.4 ± 0.6 and C2 = 42.6 ± 4.2 µg Cd/L) along with a control (C0 = 0 µg Cd/L) for 28 days. Cadmium bioaccumulation, diatoms growth, photosynthetic efficiencies, valve deformities and genetic expression were investigated during the course of the experiment. Cadmium exposure had significant effects on bioaccumulation, growth, valve deformities and genetic expression. Maximal effects for all studied endpoints were recorded after 7 days of exposure for the C2 treatment, which corresponded to the sampling time and condition with maximum cadmium bioaccumulation. Abnormal raphe formations (deviation from its lateral position) were significantly more abundant in the C2 treatment compared to the control. Molecular responses were related to cadmium level based on the number of genes impacted, intensity of the response and the frequency of observations. The expression of genes involved in the regulation of mitochondrial metabolism, photosynthesis, oxidative stress and silica metabolism was affected by cadmium exposure. [ABSTRACT FROM AUTHOR]

Abstract: Selenium (Se) concentrations measured in lake planktonic food chains (microplankton <64 μm, copepods, and Chaoborus larvae) were strongly correlated with the concentrations of dissolved organic Se. These correlations were strengthened slightly by adding the concentrations of dissolved selenate to those of organic Se. To better understand the role of Se species and the influence of water chemistry on Se uptake, we exposed the green alga Chlamydomonas reinhardtii to selenite, selenate, or selenomethionine at various H+ ion and sulfate concentrations under controlled laboratory conditions. At low sulfate concentrations, inorganic Se species (selenate >> selenite) were more readily accumulated by this alga than was selenomethionine. However, at higher sulfate concentrations the uptake of selenite was higher than that of selenate, whereas the uptake of selenomethionine remained unchanged. Although the pH of the exposure water did not influence the uptake of selenate by this alga, the accumulation of selenomethionine and selenite increased with pH because of their relative pH‐related speciation. The Se concentrations that we measured in C. reinhardtii exposed to selenomethionine were 30 times lower than those that we measured in field‐collected microplankton exposed in the same laboratory conditions. This difference is explained by the taxa present in the microplankton samples. Using the present laboratory measurements of Se uptake in microplankton and of natural Se concentrations in lake water allowed us to model Se concentrations in a lake pelagic food chain. Environ Toxicol Chem 2018;37:2112–2122. © 2018 SETAC [ABSTRACT FROM AUTHOR]

In contrast to substantial studies and established knowledge of aluminum (Al) effects (mainly toxicity) on freshwater organisms and terrestrial plants, and even on human health, only a few studies of Al effects on marine organisms have been reported, and our understanding of the role of Al in marine biogeochemistry is limited. In this paper, we review the results of both field and laboratory experiments on the effects of Al on marine organisms, including Al toxicity to marine phytoplankton and the beneficial effects of Al on marine phytoplankton growth, and we discuss possible links of Al to the biological pump and the global carbon cycle. We propose a revised Iron (Fe) Hypothesis, i.e., the Fe-Al Hypothesis that introduces the idea that Al as well as Fe play an important role in the glacial-interglacial change in atmospheric CO2 concentrations and climate change. We propose that Al could not only facilitate Fe utilization, dissolved organic phosphorus utilization and nitrogen fixation by marine phytoplankton, enhancing phytoplankton biomass and carbon fixation in the upper oceans, but also reduce the decomposition and decay of biogenic matter. As a result, Al allows potentially more carbon to be exported and sequestered in the ocean depths through the biological pump. We also propose that Al binds to superoxide to form an Al-superoxide complex, which could catalyze the reduction of Fe(III) to Fe(II) and thus facilitate Fe utilization by marine phytoplankton and other microbes. Further ocean fertilization experiments with Fe and Al are suggested, to clarify the role of Al in the stimulation of phytoplankton growth and carbon sequestration in the ocean depths. [ABSTRACT FROM AUTHOR]

Abstract: Several cases have been described in the literature where different ligands enhanced lead (Pb) bioavailability over what would have been expected on the basis of equilibrium models such as the biotic ligand model (BLM). These exceptions compromise the development of BLMs for this metal, and mechanistic knowledge of the involved processes is still insufficient. The present study shows that the hydrophilic organic ligand citrate enhances Pb internalization by Chlamydomonas reinhardtii for both the wild and the wall‐less strains. Despite the high Pb internalization fluxes shown by this alga, which may be near the limits set by diffusion through the boundary layer, and its capacity to assimilate citrate (and potentially Pb‐citrate complexes), neither of these mechanisms could quantitatively account for the observed increase in Pb internalization in the presence of this ligand. However, algal‐driven pH increases in the boundary layer and concomitant changes in Pb speciation successfully explained the observed results. This study suggests that information on bulk solution chemistry is not enough to predict metal bioavailability for organisms that can substantially modify the chemical composition of their boundary layer, as observed for C. reinhardtii. [ABSTRACT FROM AUTHOR]

Aim To explore the characteristics that influence project management offices acceptance and adoption in healthcare sector. Background The creation of project management offices has been suggested as a promising avenue to promote successful organisational change and facilitate evidence-based practice. However, little is known about the characteristics that promote their initial adoption and acceptance in health care sector. This knowledge is important in the context where many organisations are considering implementing project management offices with nurse managers as leaders. Methods A descriptive multiple case study design was used. The unit of analysis was the project management offices. The study was conducted in three university-affiliated teaching hospitals in 2013-14 (Canada). Individual interviews ( n = 34) were conducted with senior managers. Results Results reveal that project management offices dedicated to project and change management constitute an innovation and an added value that addresses tangible needs in the field. Conclusion Project management offices are an innovation highly compatible with health care managers and their approach has parallels to the process of clinical problem solving and reasoning well-known to adopters. Implications for nursing management This knowledge is important in a context where many nurses hold various roles in project management offices, such as Director, project manager, clinical expert and knowledge broker. [ABSTRACT FROM AUTHOR]

Recent studies have suggested that low-molecular-weight (LMW) ligands can enhance trace metal uptake by marine diatoms. We have extended this work to freshwater phytoplankton and have investigated Cd bioavailability in the presence of LMW thiols, with two green algae ( Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata) and a cyanobacterium ( Anabaena flos-aquae). Using nitrilotriacetic acid (NTA) to hold the free Cd2+ concentration constant, we progressively added cysteine to the exposure medium and determined short-term Cd uptake rates for each organism; the Cd uptake rates remained constant and were unaffected even when the concentrations of the Cd-cysteine complexes exceeded that of the free Cd2+. Similar results were obtained with algae pre-acclimated to different nitrogen sources or low zinc concentrations, even though such treatments affect their ability to utilize amino acids or take up Cd. A lack of effect was also observed for the two green algae with penicillamine, mercaptosuccinic acid, dithiothreitol and glutathione. These results suggest that the Cd-thiol complexes do not contribute to Cd uptake. However, when the experiments were repeated with cysteine in the absence of NTA, at the same Cd2+ concentration, a significantly higher Cd uptake rate was observed in the presence of the L- or D-cysteine stereoisomers than in the presence of NTA. This enhancement of Cd uptake in the presence of cysteine alone was sensitive to the nitrogen nutrition of these microorganisms, and we suggest that the enhancement likely results from biologically-induced chemical oxidation of cysteine in the boundary layer adjacent to the algal cell. [ABSTRACT FROM AUTHOR]

An ion-exchange technique that employs a polystyrene sulphonate ion-exchange resin was developed for determining environmentally relevant free-ion concentrations of Ce, Eu,Laand Nd. Owingto the high affinity of rare earth elements (REE) for the selected resin, this method requires the addition of an inert salt to increase the concentration of the counter-ions (i.e. cations that are exchanged with REE bound to the resin). The use of a batch equilibration approach to calibrate the resin allowed the implementation of the ion-exchange technique at reasonably low ionic strength (I = 0.1 M). Several ligands were used to test the selectivity of the method, which proved to be highly selective for the free metal ion in presence of the tested cationic and anionic complexes (REE-nitrate, REE-malic acid and REE-nitrilotriacetic acid systems) and operational for very low proportions of REE3+, owing to the strong REE-resin interactions. The ion-exchange technique was also implemented to determine [Eu]inorg in the presence of natural humic matter (Suwannee River Humic Acid) and the results were compared with those obtained using equilibrium dialysis and those calculated with chemical equilibrium models. At pH 4.00, the measured [Eu]inorg values were in fairly good agreement with those predicted with the Windermere Humic Aqueous Model and Stockholm Humic Model, whereas the Non-Ideal Competitive Absorption model appeared to underestimate the [Eu]inorg. However, the inorganic europium concentrations were strongly underestimated (4 , [Eu]inorg, IET/[Eu]inorg, calc<18) with the three prediction models at higher pH (5.3 and 6.2). [ABSTRACT FROM AUTHOR]

Biofilms can make good bioindicators and biomarkers, offering a convenient tool to monitor metal contamination in streams that results from mine tailing sites. Biofilm metal content (Cu, Zn, Cd, Pb) as well as diatom diversity and the presence of teratologies (diatom abnormalities) were determined for biofilms from rivers with a variety of physicochemical properties across a metal contamination gradient. The results of metal accumulation were highly consistent from year to year, with significant relationships between calculated free metal ion concentrations and biofilm metal contents for samples from different rivers. This indicates the 'universal nature' of the metal accumulation process in biofilms. The authors observed that protons and major cations protected against metal accumulation. A very low number of diatom taxa were found at the most contaminated sites, and the highest proportions of deformities were observed at these sites. However, it was difficult to distinguish the effect of metal contamination from the effect of other parameters, especially pH. The results suggest that the development of biofilm-based proxies for metal bioavailability is useful and that incorporation of the effects of hardness and pH in this metal contamination monitoring tool is important. Environ Toxicol Chem 2016;35:1489-1501. © 2015 SETAC [ABSTRACT FROM AUTHOR]

In the fall of 2013, Mégaphone, an architectural-scale interactive "Speakers' Corner," was deployed outdoors after dusk in downtown Montréal, Canada. This urban art installation included a monumental media façade designed to display a transcription of some of the words uttered into the microphone by end users. Driven by the system's two temporal modalities--a performative "live mode" and an archival "sleep mode"--the video projections revealed the dual skins of a media façade that spanned almost an entire city block. This article examines how activists appropriated Mégaphone to transform an ordinary building into an urban mausoleum. [ABSTRACT FROM AUTHOR]

Predicting metal availability and toxicity for chronic (several hours or days) metal exposure scenarios, even for unicellular algae, is a major challenge to existing toxicity models. This is because several factors affecting metal uptake and toxicity, such as the release of metal-binding exudates, changes in the kinetics of metal uptake and toxicity over time, and algal physiological acclimation to internalized metals, are still poorly understood. The present study assessed the influence of these factors on Cd uptake and toxicity in laboratory batch cultures of the freshwater alga Pseudokirchneriella subcapitata. To do so, changes in the free Cd2+ concentrations caused by the release of metal-binding algal exudates were monitored,109Cd accumulation in algal cells was measured, and Cd-induced inhibition of algal growth as a function of exposure time (from 12 h to 96 h) was followed. Results indicate that metal-binding exudates may decrease the proportion of the free Cd2+ ion in solution up to 2-fold, a decrease that affects Cd uptake and toxicity. Pseudokirchneriella subcapitata has the capacity to decrease net Cd uptake rate on short time scales (<24 h), but this reduction in the Cd uptake rate disappeared after 24 h, and Cd toxicity occurred at relatively high Cd concentrations in solution. These data illustrate some of the pitfalls of standard algal toxicity assays, which were designed for acute exposures, and suggest how robust chronic bioassays might be developed. Environ Toxicol Chem 2015;34:1524-1532. © 2015 SETAC [ABSTRACT FROM AUTHOR]

We demonstrate autosomal-recessive Caspase Recruitment Domain-containing protein 9 (CARD9) deficiency in a patient with relapsing C. albicans meningoencephalitis. We identified a novel, hypomorphic mutation with intact Th17 responses, but impaired GM-CSF responses. We report complete clinical remission with adjunctive GM-CSF therapy, suggesting that a CARD9/GM-CSF axis contributes to susceptibility to candidiasis. [ABSTRACT FROM AUTHOR]

The effects of pH on metal uptake and toxicity in aquatic organisms are currently poorly understood and remain an evolving topic in studies about the biotic ligand model (BLM). In the present study, the authors investigated how pH may influence long-term (4 d) uranium (U) accumulation and chronic toxicity in batch cultures of the freshwater green alga Chlamydomonas reinhardtii. The toxicity expressed as a function of the free uranyl ion was much greater at pH 7 (effective concentration, 50% [EC50] = 1.8 × 10−9 M UO22+) than at pH 5 (EC50 = 1.2 × 10−7 M UO22+). The net accumulation rate of U in algal cells was much higher at pH 7 than at pH 5 for the same free [UO22+], but the cells exposed at pH 5 were also more sensitive to intracellular U than the cells at pH 7 with EC50s of 4.0 × 10−15 and 7.1 × 10−13 mol of internalized U cell−1, respectively. The higher cellular sensitivity to U at pH 5 than at pH 7 could be explained partly by the increase in cytosolic U binding to algal soluble proteins or enzymes at pH 5 as observed by subcellular fractionation. To predict U accumulation and toxicity in algae accurately, the important modulating effects of pH on U accumulation and U cellular sensitivity should be considered in the BLM. Environ Toxicol Chem 2014;33:1372-1379. © 2014 SETAC [ABSTRACT FROM AUTHOR]

The present review describes and discusses key interactions between mercury (Hg) and phytoplankton to highlight the role of phytoplankton in the biogeochemical cycle of Hg and to understand direct or indirect Hg effects on phytoplankton. Phytoplankton are exposed to various Hg species in surface waters. Through Hg uptake, phytoplankton affect the concentration, speciation, and fate of Hg in aquatic systems. The mechanisms by which phytoplankton take up Hg are still not well known, but several studies have suggested that both facilitated transport and passive diffusion could be involved. Once internalized, Hg will impact several physiological processes, including photosynthesis. To counteract these negative effects, phytoplankton have developed several detoxification strategies, such as the reduction of Hg to elemental Hg or its sequestration by intracellular ligands. Based on the toxicological studies performed so far in the laboratory, Hg is unlikely to be toxic to phytoplankton when they are exposed to environmentally relevant Hg concentrations. However, this statement should be taken with caution because questions remain as to which Hg species control Hg bioavailability and about Hg uptake mechanisms. Finally, phytoplankton are primary producers, and accumulated Hg will be transferred to higher consumers. Phytoplankton are a key component in aquatic systems, and their interactions with Hg need to be further studied to fully comprehend the biogeochemical cycle of Hg and the impact of this ubiquitous metal on ecosystems. Environ Toxicol Chem 2014;33:1211-1224. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Objective: The predictors of Fanconi syndrome (FS) accompanied by renal function decline with use of the antiretroviral tenofovir disoproxil fumarate (TDF) have not been assessed. In addition, the natural history of renal recovery from FS after TDF discontinuation is not well-described. Design: We prospectively enrolled HIV-infected patients receiving TDF with newly identified FS (defined as at least two markers of proximal tubulopathy and either a >25% decline in creatinine clearance (CrCl) from pre-TDF values or a CrCl <60 mL/min in those without a known pre-TDF CrCl) in a multicenter observational study. These case participants were matched 1∶2 to controls; characteristics between the two groups were compared. Case participants with known pre-TDF CrCl values were then followed over 48 weeks to assess renal recovery. Results: Nineteen cases and 37 controls were enrolled. In multivariable analysis, previous or concurrent use of lopinavir/ritonavir [OR 16.37, 95% CI (2.28, 117.68); P = 0.006] and reduced creatinine clearance prior to initiation of TDF [OR 1.44 for every 5 mL/min reduction, 95% CI (1.09, 1.92); P = 0.012; OR 19.77 for pre-TDF CrCl lower than 83 mL/min, 95% CI (2.24, 174.67); P = 0.007] were significantly associated with FS. Of the 14 cases followed for resolution, 7 (50%) achieved at least partial resolution (defined as recovering CrCl >70% of pre-TDF values) although most participants had full normalization of proximal tubulopathy markers within two months of TDF discontinuation. Conclusions: FS, defined by specific CrCl decreases and markers of tubulopathy, is more likely in those who have received or are currently receiving concomitant lopinavir/ritonavir or who had lower CrCl prior to TDF initiation. Half of those with protocol-defined FS had CrCl recover to near pre-TDF values during the first year after TDF discontinuation. [ABSTRACT FROM AUTHOR]

Background We examined the uptake and sorption of aluminium (Al) and fluoride (F) by green algae under conditions similar to those found in the effluents of the aluminium industry. We took into account the speciation of Al in the medium since Al can form stable complexes with F and these complexes may play a role in the uptake and sorption of Al. We compared the capacity of four species of green algae (i.e. Chlamydomonas reinhardtii, Pseudokirchneriella subcapitata, Chlorella vulgaris, and Scenedesmus obliquus) to accumulate and adsorb Al and F. The selected algae were exposed during 4 days, covering all growth phases of algae, to a synthetic medium containing Al and F at pH 7.0. During this period, dissolved Al as well as cellular growth were followed closely. At the end of the exposure period, the solutions were filtered in order to harvest the algal cells. The cells were then rinsed with enough ethylene diaminetetraacetic acid to remove loosely bound ions from the algal surface, determined from the filtrates. Finally, the filters were digested in order to quantify cellular uptake. Results Little difference in Al removal was observed between species. Aluminium sorption (15%) and uptake (26%) were highest in P. subcapitata , followed by C. reinhardtii (7% and 17% respectively), S. obliquus (13% and 5%), and C. vulgaris (7% and 2%). However, none of these species showed significant uptake or sorption of F. We also studied the influence of pH on the uptake and sorption of Al and F by P. subcapitata. We measured a combined uptake and sorption of Al of 50% at pH 7.5, of 41% at pH 7.0, and of 4% at pH 5.5. Thus, accumulation was reduced with acidification of the medium as expected by the increased competition with protons and possibly by a reduced bioavailability of the Al-F complexes which dominated the solution at low pH. Conclusion Out of the four tested species, P. subcapitata showed the highest sorption of aluminium and fluoride under our test conditions. These results provide key information on the development of an environmental biotechnology which can be applied to industrial effluents. [ABSTRACT FROM AUTHOR]

The unicellular alga Chlamydomonas reinhardtii has a very high rate of lead (Pb) internalization and is known to be highly sensitive to dissolved Pb. However, the transport pathway that this metal uses to cross cellular membranes in microalgae is still unknown. To identify the Pb transport pathway in C. reinhartdii, we performed several competition experiments with environmentally relevant concentrations of Pb (~10 nM) and a variety of divalent cations. Among the essential trace metals tested, cobalt, manganese, nickel and zinc had no effect on Pb internalization. A greater than tenfold increase in the concentrations of the major ions calcium and magnesium led to a slight decrease (~34 %) in short-term Pb internalization by the algae. Copper (Cu) was even more effective: at a Cu concentration 50 times higher than that of Pb, Pb internalization by the algae decreased by 87 %. Pre-exposure of the algae to Cu showed that the effect was not due to a physiological effect of Cu on the algae, but rather to competition for the same transporter. A reciprocal effect of Pb on Cu internalization was also observed. These results suggest that Cu and Pb share a common transport pathway in C. reinhardtii at environmentally relevant metal concentrations. [ABSTRACT FROM AUTHOR]

Despite 40+ years of research on aluminum (Al) toxicity in aquatic organisms, Al transport mechanisms through biological membranes, and the intracellular fate of Al once assimilated, remain poorly understood. The trivalent metal scandium shares chemical similarities with Al and, unlike Al, it has a convenient radioactive tracer (Sc-46) allowing for relatively simple measurements at environmentally relevant concentrations. Thus, we investigated the potential of Sc to substitute for Al in uptake and intracellular fate studies with the green alga Chlamydomonas reinhardtii. Short-term (<60 min) competitive uptake experiments indicated that Al does not inhibit Sc influx, implying that these metals do not share a common transport mechanism. Also, internalized Al concentrations were ~4 times higher than Sc concentrations after long-term (72 h) exposures under similar conditions (4.5 μM Al T or Sc T, 380 μM F T, pH 7.0, 3.8 pM Al calc3+ and 1.0 pM Sc calc3+). However, interesting similarities were observed in their relative subcellular distributions, suggesting possible common toxicity/tolerance mechanisms. Both metals mostly distributed to the organelles fraction and almost no association was found with the cytosolic proteins. The greatest difference was observed in the cellular debris fraction (membranes and nucleus) where Al was much more concentrated than Sc. However, it is not clear whether or not this fraction contained extracellular metal associated with the algal surface. To summarize, Sc does not seem to be an adequate substitute of Al for transport/uptake studies, but could be for investigations of toxicity/tolerance mechanisms in C. reinhardtii. Further work is needed to verify this latter suggestion. [ABSTRACT FROM AUTHOR]