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The present study aims to reduce the fluoride concentration of drinking water using a novel mild adsorbent based natural clay. The natural clay was dealuminated/realuminated and dehydroxylated by intense washing and heating processes. The developed adsorbent was confirmed by X-ray diffraction (XRD), thermal analyses (ATD-TG) and nuclear magnetic resonance solid-state with magic angle spinning (MAS NMR). MAS NMR results showed that distorted tetrahedral-Al coordination and penta-Al coordination sites were responsible for fluoride adsorption. Batch adsorption experiments were investigated without any adjustment of water pH. The effect of the clay dosage over the range of 0.5–2 g/50 mL of sample solution was studied. Results revealed that the aggregation of the clay particles in the water was successfully avoided thanks to the heating process. Kinetics and adsorption isotherms were also investigated. The adsorption equilibrium was achieved on a timescale of seconds. Adsorption kinetics data followed pseudo-first-order as well as pseudo-second-order models while isotherm experimental data followed the Freundlich model. The maximum adsorption capacity was relatively small (1.2 mg${\cdot }$g$^{-1}$). Tests performed on Tunisian contaminated drinking water showed that water potability with respect to fluoride was successfully achieved; suggesting that the dealuminated/realuminated dehydroxylated clay can be a promising fluoride adsorbent for drinking water.

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]

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]

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]