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Copper (Cu) is a cofactor in numerous key proteins and, thus, an essential element for life. In biological systems, Cu isotope abundances shift with metabolic and homeostatic state. However, the mechanisms underpinning these isotopic shifts remain poorly understood, hampering use of Cu isotopes as biomarkers. Computational predictions suggest that isotope fractionation occurs when proteins bind Cu, with the magnitude of this effect dependent on the identity and arrangement of the coordinating amino acids. This study sought to constrain equilibrium isotope fractionation values for Cu bound by common amino acids at protein metal-binding sites. Free and bound metal ions were separated via Donnan dialysis using a cation-permeable membrane. Isotope ratios of pre- and post-dialysis solutions were measured by MC-ICP-MS following purification. Sulfur ligands (cysteine) preferentially bound the light isotope (63Cu) relative to water (Δ65Cucomplex-free = − 0.48 ± 0.18‰) while oxygen ligands favored the heavy isotope (65Cu; + 0.26 ± 0.04‰ for glutamate and + 0.16 ± 0.10‰ for aspartate). Binding by nitrogen ligands (histidine) imparted no isotope effect (− 0.01 ± 0.04‰). This experimental work unequivocally demonstrates that amino acids differentially fractionate Cu isotopes and supports the hypothesis that metalloprotein biosynthesis affects the distribution of transition metal isotopes in biological systems. [ABSTRACT FROM AUTHOR]

Background: More than 700 million people worldwide suffer from diseases of the pancreas, such as diabetes, pancreatitis and pancreatic cancer. Often dysregulation of potassium (K+) channels, co-transporters and pumps can promote development and progression of many types of these diseases. The role of K+ transport system in pancreatic cell homeostasis and disease development remains largely unexplored. Potassium isotope analysis (δ41K), however, might have the potential to detect minute changes in metabolic processes relevant for pancreatic diseases. Methods: We assessed urinary K isotope composition in a case-control study by measuring K concentrations and d41K in spot urines collected from patients diagnosed with pancreatic cancer (n=18), other pancreas-related diseases (n=14) and compared those data to healthy controls (n=16). Results: Our results show that urinary K+ levels for patients with diseased pancreas (benign and pancreatic cancer) are significantly lower than the healthy controls. For δ41K, the values tend to be higher for individuals with pancreatic cancer (mean δ41K = -0.58 ± 0.33‰) than for healthy individuals (mean δ41K= -0.78 ± 0.19‰) but the difference is not significant (p=0.08). For diabetics, urinary K+ levels are significantly lower (p=0.03) and δ41K is significantly higher (p=0.009) than for the healthy controls. These results suggest that urinary K+ levels and K isotopes can help identify K disturbances related to diabetes, an associated factors of all-cause mortality for diabetics. Conclusion: Although the K isotope results should be considered exploratory and hypothesis-generating and future studies should focus on larger sample size and δ41K analysis of other K-disrupting diseases (e.g., chronic kidney disease), our data hold great promise for K isotopes as disease marker. [ABSTRACT FROM AUTHOR]

Background: More than 700 million people worldwide suffer from diseases of the pancreas, such as diabetes, pancreatitis and pancreatic cancer. Often dysregulation of potassium (K+) channels, co-transporters and pumps can promote development and progression of many types of these diseases. The role of K+ transport system in pancreatic cell homeostasis and disease development remains largely unexplored. Potassium isotope analysis (δ41K), however, might have the potential to detect minute changes in metabolic processes relevant for pancreatic diseases. Methods: We assessed urinary K isotope composition in a case-control study by measuring K concentrations and δ41K in spot urines collected from patients diagnosed with pancreatic cancer (n=18), other pancreas-related diseases (n=14) and compared those data to healthy controls (n=16). Results: Our results show that urinary K+ levels for patients with diseased pancreas (benign and pancreatic cancer) are significantly lower than the healthy controls. For δ41K, the values tend to be higher for individuals with pancreatic cancer (mean δ41K = -0.58 ± 0.33‰) than for healthy individuals (mean δ41K = -0.78 ± 0.19%) but the difference is not significant (p=0.08). For diabetics, urinary K+ levels are significantly lower (p=0.03) and δ41K is significantly higher (p=0.009) than for the healthy controls. These results suggest that urinary K+ levels and K isotopes can help identify K disturbances related to diabetes, an associated factors of all-cause mortality for diabetics. Conclusion: Although the K isotope results should be considered exploratory and hypothesis-generating and future studies should focus on larger sample size and δ41K analysis of other K-disrupting diseases (e.g., chronic kidney disease), our data hold great promise for K isotopes as disease marker. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chronic arsenic exposure has been associated with an increased risk of cardiovascular disease; diabetes; cancers of the lung, pancreas and prostate; and all-cause mortality in American Indian communities in the Strong Heart Study. OBJECTIVE: The Strong Heart Water Study (SHWS) designed and evaluated a multilevel, community-led arsenic mitigation program to reduce arsenic exposure among private well users in partnership with Northern Great Plains American Indian Nations. METHODS: A cluster randomized controlled trial (cRCT) was conducted to evaluate the effectiveness of the SHWS arsenic mitigation program over a 2-y period on a) urinary arsenic, and b) reported use of arsenic-safe water for drinking and cooking. The cRCT compared the installation of a pointof- use arsenic filter and a mobile Health (mHealth) program (3 phone calls; SHWS mHealth and Filter arm) to a more intensive program, which included this same program plus three home visits (3 phone calls and 3 home visits; SHWS Intensive arm). RESULTS: A 47% reduction in urinary arsenic [geometric mean (GM)=13.2 to 7.0 μg/g creatinine] was observed from baseline to the final follow-up when both study arms were combined. By treatment arm, the reduction in urinary arsenic from baseline to the final follow-up visit was 55% in the mHealth and Filter arm (GM=14.6 to 6.55 μg/g creatinine) and 30% in the Intensive arm (GM=11.2 to 7.82 μg/g creatinine). There was no significant difference in urinary arsenic levels by treatment arm at the final follow-up visit comparing the Intensive vs. mHealth and Filter arms: GM ratio of 1.21 (95% confidence interval: 0.77, 1.90). In both arms combined, exclusive use of arsenic-safe water from baseline to the final follow-up visit significantly increased for water used for cooking (17% to 53%) and drinking (12% to 46%). DISCUSSION: Delivery of the interventions for the community-led SHWS arsenic mitigation program, including the installation of a point-of-use arsenic filter and a mHealth program on the use of arsenic-safe water (calls only, no home visits), resulted in a significant reduction in urinary arsenic and increases in reported use of arsenic-safe water for drinking and cooking during the 2-y study period. These results demonstrate that the installation of an arsenic filter and phone calls from a mHealth program presents a promising approach to reduce water arsenic exposure among private well users. [ABSTRACT FROM AUTHOR]

Volcanic eruptions increase environmental heavy metal concentrations, yet little research has been performed on their extrapulmonary human health effects. We fortuitously collected biological samples in a cohort of Guatemalan sugarcane cutters in the area surrounding Volcán de Fuego before and after the June 2018 eruption. We sought to determine whether stratovolcanic activity was associated with changes in urinary concentrations of heavy metals in a cohort of sugarcane workers. In this exploratory analysis, we found significant increases in urinary arsenic, (β = 1.46, P < 0.0001), cadmium (β = 1.03, P < 0.0001), and lead (β = 0.87, P = 0.003) in participants with residential proximity to Volcán de Fuego as compared to participants farther away, suggesting that volcanic activity could be associated with acute heavy metal exposures. This natural experiment is, to our knowledge, the first of its kind and suggests a need for more research into heavy metal exposure-related health impacts of volcanic eruptions. [ABSTRACT FROM AUTHOR]

Background & aims: Gold nanoparticles (AuNPs) are useful tools for noninvasive drug delivery. AuNP nebulization has shown poor deposition results, and AuNP tracking postadministration has involved methods inapplicable to clinical settings. The authors propose an intratracheal delivery method for minimal AuNP loss and computed tomography scans for noninvasive tracking. Materials & methods: Through high-frequency and directed nebulization postendotracheal intubation, the authors treated rats with AuNPs. Results & conclusion: The study showed a dose-dependent and bilateral distribution of AuNPs causing no short-term distress to the animal or risk of airway inflammation. The study demonstrated that AuNPs do not deposit in abdominal organs and show targeted delivery to human lung fibroblasts, offering a specific and noninvasive strategy for respiratory diseases requiring long-term therapies. This study presents an alternative method for drug delivery involving gold nanoparticle aerosolization directly into the major airways. Direct nebulization prevents particle loss and avoids drug administration through the blood. The particles can be detected successfully via upper body scans, which are noninvasive and allow for on-demand monitoring. Nanoparticles are flexible tools that can be modified to target specific cells of interest and can be excreted upon completion of their function. These results could represent an alternative method of drug administration in patients needing repeated cytotoxic therapies with known off-target effects. [ABSTRACT FROM AUTHOR]

Soils in the Lower Swansea Valley, (United Kingdom) contain elevated level of metals, enough to cause direct or indirect effects on human health. This study assesses the severity of soil pollution and bioavailability of Cu and other metals (Ni, Zn, Co, Pb and Cr) in soils with various distances from a Ni refinery. We compare Cu concentrations in operationally defined soil fractions (bioavailable, bound to Fe/Mn oxide and incorporated in organic matter) with other metals (Ni, Zn, Pb, Co, Cr) usually occurring in ores used in metallurgic processes and report their pollution and geoaccumulation indices (PI and Igeo). Further, we use Cu stable isotope ratios (δ65Cu) to trace the fate and mobility of Cu in soils. Our data suggest a point source of contamination for some of the heavy metals including Ni (Igeo = 1.9), Zn (Igeo = 0.28) and Cu (Igeo = 3.6) near the Ni refinery. However, Co (Igeo = 0.15) and Pb (Igeo = 3.3) contaminations are likely to be linked to different sources. No elevated Cr levels (Igeo= -0.07) occur in any of the studied soils. All soil metals are predominantly associated with organic matter (>50%) which reduces their bioavailibility and thus their risk for ecological and human health. The Cu isotope data show that Cu in soil organic matter is enriched in 65Cu, while the lighter isotopes (63Cu) remain in the dissolved bioavailable Cu fraction (Δ65Cuorganic-bioavailable is +0.12 ± 0.13‰). This suggests the preferential complexation of 65Cu with soil organic matter after dissolution of Cu deposited to the soil. Thus, Cu isotope data can effectively indicate pathways of metal migration in polluted soils. [ABSTRACT FROM AUTHOR]

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The dissolution of elemental selenium [Se(0)] during chemical weathering is an important step in the global selenium cycle. While microorganisms have been shown to play a key role in selenium dissolution in soils, the mechanisms of microbial selenium solubilization are poorly understood. In this study, we isolated a Bacillus species, designated as strain JG17, that exhibited the ability to dissolve Se(0) under oxic conditions and neutral pH. Growth of JG17 in a defined medium resulted in the production and accumulation of extracellular compounds that mediated Se(0) dissolution. Analysis of the spent medium revealed the presence of extracellular sulfite, sulfide, and thiosulfate. Abiotic Se(0) dissolution experiments with concentrations of sulfite, sulfide, and thiosulfate relevant to our system showed similar extents of selenium solubilization as the spent medium. Together, these results indicate that the solubilization of Se(0) by JG17 occurs via the release of extracellular inorganic sulfur compounds followed by chemical dissolution of Se(0) by the reactive sulfur metabolites. Our findings suggest that the production of reactive sulfur metabolites by soil microorganisms and the formation of soluble selenosulfur complexes can promote selenium mobilization during chemical weathering. [ABSTRACT FROM AUTHOR]

Microbially-mediated iron (Fe) cycling controls the fate of organic matter, contaminants, and nutrients in terrestrial ecosystems including wetland soils. However, the effects of temperature variations due to seasonal differences on Fe(III) reduction rates and kinetics in such ecosystems remains poorly understood. To evaluate the potential temperature impact on dissimilatory microbial Fe(III) reduction it is crucial to determine environmentally-relevant reaction rates and kinetic parameters. Here, we investigate the relationship between soil temperature and microbial Fe(III) reduction kinetics in mineral soils from two subalpine wetlands with distinct hydrologic and edaphic conditions. We conducted flow-through experiments (FTR) at three temperatures (6, 12, and 18 °C) using intact soil cores collected from 30 cm [(higher organic carbon (Corg) and total nitrogen (TN)] and 70 cm (lower Corg and TN) soil depths in order to determine the apparent Fe(III) affinity constant (Km), apparent maximum Fe(III) reduction rates (Vmax) and temperature sensitivity (Q10 and Ea) of Fe(III) reduction. We used Fe(III)-NTA, a model compound for aqueous labile and complexed Fe present in natural organic matter. Our results show that changes in apparent Vmax and Km are driven primarily by temperature. Significant differences in apparent Vmax at 18 °C relative to 6 and 12 °C (P < 0.05) suggest that dissimilatory microbial Fe(III) reduction in wetland soils accelerates during warmer summer days. However, temperature alone fails to explain the large variability of the apparent parameters Q10 (1.5-8.9) and Ea (26-148 kJ mol−1) for the two wetland types and depths (30 and 70 cm). Strong relationship between both parameters of temperature sensitivity (Q10 and Ea) and reactive soil Fe content at 30 cm and Corg/TN at 70 cm depth demonstrate the notable impact of soil properties on the temperature sensitivity for mirobial Fe(III) reduction in these wetland soils. Our results emphasize the importance of soil temperature on Fe(III) reduction kinetics and must be considered when predicting dissimilatory Fe(III) reduction under different seasonal temperatures or in wetlands located at different temperature regimes. [ABSTRACT FROM AUTHOR]

To predict selenium cycling in sediments, it is crucial to identify and quantify the processes leading to selenium sequestration in sediments. More specifically, it is essential to obtain environmentally-relevant kinetic parameters for selenium reduction and information on how they spatially vary in sediments. The Salton Sea (California, USA) is an ideal model system to examine selenium processes in sediments due to its semi-enclosed conditions and increasing selenium concentration over the last century. Selenium enters the Salton Sea mainly as selenate and might be sequestered in the sediment through microbial reduction. To determine the potential selenium sequestration of Salton Sea littoral sediments and which sediment properties are controlling selenate reduction kinetics, we determined the centimeter-scale vertical distribution of potential selenate reduction rates and apparent kinetic parameters (maximum selenate reduction rates, Vmax, and selenate half-saturation concentration, Km) using flow-through reactor (FTR) experiments. We compared sediments from two littoral sites (South and North) and four depth intervals (0-2, 2-4, 4-6 and 6-8 cm). Furthermore, we characterized the selenium fractions in the sediment recovered from the FTR experiments to identify the processes leading to the sequestration of selenium. Our results reveal higher potential for selenium reduction and sequestration in the topmost sediment (0-2 cm) suggesting that microorganisms inhabiting surface sediment are well adapted to reduce selenate entering the Salton Sea. As apparent Km values (103-2144 µM) exceed the average selenium concentration in the overlying water (6-25 nM), in situ selenate reduction is limited by the low availability of selenate and the resident selenate-reducing microorganisms operate well below their Vmax (11 and 43 nmol cm−3 h−1). Selenium speciation after FTR experiments confirms the primary sequestration of reduced biomass-associated and elemental selenium (68-99% of total selenium) in the sediment. Further, the absence of correlation between the tested sediment physical (porosity, bulk density, clay content), chemical (Corg, Ntot, total selenium content) and biological characteristics (abundance of culturable selenate-reducers) with the kinetic parameters of selenate reduction indicates that these sediment characteristics cannot be used as predictors of apparent Vmax or Km. Conclusively, microbial selenate reduction is an important, if not the primary process, leading to the sequestration of reduced selenium in the Salton Sea sediments and making the surficial Salton Sea sediments an important selenium sink. [ABSTRACT FROM AUTHOR]

Introduction: There is no doubt that lifestyle factors can be detrimental to fertility. The aim of the present pilot study was to identify initial prevalence rates for behaviour-related fertility disorders in a clinical sample of couples wanting a child. Methods: Between February 2010 and August 2010, all patients coming for the first time to Heidelberg University's Women's Hospital for consultation on involuntary childlessness were asked to fill out a questionnaire designed by the authors of this article. The questionnaire was based on a review of the relevant literature, with special reference to the latest research findings on behaviour detrimental to fertility. Of the 156 couples addressed, 110 women and 100 men took part in the study. Results: For behaviour-related infertility, 9 % of the women and 3 % of the men in our sample were classified on the basis of BMI <18.5, sexual disorders, or abuse of anabolic steroids. If we include smokers, these figures increase: 11 % female smokers and 18 % male smokers. A further 19 % of the women practised sport to an excessive degree; and 26 % of the women and 53 % of the men had a BMI ≥25. Discussion: The prevalence of behaviour-related fertility disorders should not be underestimated. For the prevention of behaviour-related fertility disorders, it is important to inform the population about lifestyle-mediated fertility risks. [ABSTRACT FROM AUTHOR]

A combination of sequential extraction with stable isotope ratio measurements of Se might offer new insights into biogeochemical processes governing Se turnover in soils. Therefore, we determined the Se partitioning among three operationally defined sequential extracts (0.1 mol L-1 K2HPO4-KH2PO4 at pH 7,0.05 mol L-1 NaOH, cone. HNO3) and the stable isotope ratios of total Se (δ82/76Se values) in 10 topsoils under 5 different land uses (alluvial grasslands, forests, house gardens, parks, and roadside grassland) from the city of Bayreuth (ca. 73,000 inhabitants) in Germany. Furthermore, we determined S and Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. concentrations and stable isotope ratios of total S (δ34S values) to support our interpretation of the Se concentrations and isotope ratios because of the chemical similarity of Se and S. All topsoils had low total Se concentrations (0.09-0.52 mgkg-1). The largest contribution to total Se was extracted with NaOH comprising up to 42%,which is thought to be associated with organic matter and metal oxides. The (δ82/76Se values)Se values of total Se in the topsoils were dose to the bulk Earth composition with an average S Se value of-0.03 ± SD 0.38‰ suggesting that there was no or little Se isotope fractionation in soil. We attribute the small isotope fractionation to the low bioavailability of Se as a consequence of the presence of Fe oxides (adsorbing the dominating Se(IV) forms strongly), organic matter, and Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. (prevents biouptake of the Se(IV) forms) in the study soils. Small Se isotope fractionations of -0.59 to -0.35‰ in mainly forest soils and of 0.26 to 0.45‰ in mainly alluvial soils were presumably caused by soil/plant-recycling and Se contamination by river water, respectively. In spite of the similarities in the assimilation of S and Se by organisms, the total S and Se isotope ratios in soil were not correlated. Our results demonstrate that Se in urban soils developed from Se-poor substrates is minimally cycled through the biosphere likely because of low bioavailability and competition with Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. [ABSTRACT FROM AUTHOR]