Urinary Metal Levels and Coronary Artery Calcification: Longitudinal Evidence in the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Exposure to metals, a newly recognized risk factor for cardiovascular disease (CVD), could be related to atherosclerosis progression. OBJECTIVES: The authors hypothesized that higher urinary levels of nonessential (cadmium, tungsten, uranium) and essential (cobalt, copper, zinc) metals previously associated with CVD would be associated with baseline and rate of change of coronary artery calcium (CAC) progression, a subclinical marker of CVD in MESA (Multi-Ethnic Study of Atherosclerosis). METHODS: We analyzed data from 6,418 MESA participants with spot urinary metal levels at baseline (2000-2002) and 1 to 4 repeated, continuous measures of CAC over a 10-year period. We used linear mixed-effect models to assess the association of baseline urinary metal levels with baseline CAC and cumulative change in CAC over a 10-year period. Urinary metals (µg/g creatinine) and CAC were log transformed. Models were adjusted for baseline sociodemographic factors, estimated glomerular filtration rate, lifestyle factors, and clinical factors. RESULTS: At baseline, the median CAC was 6.3 (Q1-Q3: 0.7-58.2). Comparing the highest to lowest quartile of urinary cadmium, CAC levels were 51% (95% CI: 32%, 74%) higher at baseline and 75% (95% CI: 47%, 107%) higher over the 10-year period. For urinary tungsten, uranium, and cobalt, the corresponding CAC levels over the 10-year period were 45% (95% CI: 23%, 71%), 39% (95% CI: 17%, 64%), and 47% (95% CI: 25%, 74%) higher, respectively, with no difference for models with and without adjustment for clinical factors. For copper and zinc, the corresponding estimates dropped from 55% to 33% and from 85% to 57%, respectively, after adjustment for clinical factors. The associations of metals with CAC were comparable in magnitude to those for classical CVD risk factors. CONCLUSIONS: Exposure to metals was generally associated with extent of coronary calcification at baseline and follow-up. These findings support that metals are associated with the progression of atherosclerosis, potentially providing a novel strategy for the prevention and treatment of atherosclerosis progression.

Association of Urinary Metals With Cardiovascular Disease Incidence and All-Cause Mortality in the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: Exposure to metals has been associated with cardiovascular disease (CVD) end points and mortality, yet prospective evidence is limited beyond arsenic, cadmium, and lead. In this study, we assessed the prospective association of urinary metals with incident CVD and all-cause mortality in a racially diverse population of US adults from MESA (the Multi-Ethnic Study of Atherosclerosis). METHODS: We included 6599 participants (mean [SD] age, 62.1 [10.2] years; 53% female) with urinary metals available at baseline (2000 to 2001) and followed through December 2019. We used Cox proportional hazards models to estimate the adjusted hazard ratio and 95% CI of CVD and all-cause mortality by baseline urinary levels of cadmium, tungsten, and uranium (nonessential metals), and cobalt, copper, and zinc (essential metals). The joint association of the 6 metals as a mixture and the corresponding 10-year survival probability was calculated using Cox Elastic-Net. RESULTS: During follow-up, 1162 participants developed CVD, and 1844 participants died. In models adjusted by behavioral and clinical indicators, the hazard ratios (95% CI) for incident CVD and all-cause mortality comparing the highest with the lowest quartile were, respectively: 1.25 (1.03, 1.53) and 1.68 (1.43, 1.96) for cadmium; 1.20 (1.01, 1.42) and 1.16 (1.01, 1.33) for tungsten; 1.32 (1.08, 1.62) and 1.32 (1.12, 1.56) for uranium; 1.24 (1.03, 1.48) and 1.37 (1.19, 1.58) for cobalt; 1.42 (1.18, 1.70) and 1.50 (1.29, 1.74) for copper; and 1.21 (1.01, 1.45) and 1.38 (1.20, 1.59) for zinc. A positive linear dose-response was identified for cadmium and copper with both end points. The adjusted hazard ratios (95% CI) for an interquartile range (IQR) increase in the mixture of these 6 urinary metals and the corresponding 10-year survival probability difference (95% CI) were 1.29 (1.11, 1.56) and -1.1% (-2.0, -0.05) for incident CVD and 1.66 (1.47, 1.91) and -2.0% (-2.6, -1.5) for all-cause mortality. CONCLUSIONS: This epidemiological study in US adults indicates that urinary metal levels are associated with increased CVD risk and mortality. These findings can inform the development of novel preventive strategies to improve cardiovascular health.

An epigenome-wide study of selenium status and DNA methylation in the Strong Heart Study.

BACKGROUND: Selenium (Se) is an essential nutrient linked to adverse health endpoints at low and high levels. The mechanisms behind these relationships remain unclear and there is a need to further understand the epigenetic impacts of Se and their relationship to disease. We investigated the association between urinary Se levels and DNA methylation (DNAm) in the Strong Heart Study (SHS), a prospective study of cardiovascular disease (CVD) among American Indians adults. METHODS: Selenium concentrations were measured in urine (collected in 1989-1991) using inductively coupled plasma mass spectrometry among 1,357 participants free of CVD and diabetes. DNAm in whole blood was measured cross-sectionally using the Illumina MethylationEPIC BeadChip (850 K) Array. We used epigenome-wide robust linear regressions and elastic net to identify differentially methylated cytosine-guanine dinucleotide (CpG) sites associated with urinary Se levels. RESULTS: The mean (standard deviation) urinary Se concentration was 51.8 (25.1) µg/g creatinine. Across 788,368 CpG sites, five differentially methylated positions (DMP) (hypermethylated: cg00163554, cg18212762, cg11270656, and hypomethylated: cg25194720, cg00886293) were significantly associated with Se in linear regressions after accounting for multiple comparisons (false discovery rate p-value: 0.10). The top hypermethylated DMP (cg00163554) was annotated to the Disco Interacting Protein 2 Homolog C (DIP2C) gene, which relates to transcription factor binding. Elastic net models selected 425 hypo- and hyper-methylated DMPs associated with urinary Se, including three sites (cg00163554 [DIP2C], cg18212762 [MAP4K2], cg11270656 [GPIHBP1]) identified in linear regressions. CONCLUSIONS: Urinary Se was associated with minimal changes in DNAm in adults from American Indian communities across the Southwest and the Great Plains in the United States, suggesting that other mechanisms may be driving health impacts. Future analyses should explore other mechanistic biomarkers in human populations, determine these relationships prospectively, and investigate the potential role of differentially methylated sites with disease endpoints.

Arsenic speciation analysis in human urine for long term epidemiological studies: The Multi-Ethnic Study of Atherosclerosis (MESA).

Arsenic is a ubiquitous toxic metalloid causing serious health problems. Speciation analysis of arsenic in human urine provides valuable insights for large-scale epidemiological studies and informs on sources of exposure as well as human metabolism. The Multi-Ethnic Study of Atherosclerosis (MESA) is a valuable cohort for assessing chronic low-moderate arsenic exposure and health effects in an ethnically diverse US population. We present a state-of-the-art arsenic speciation analysis methodology and its application to 7677 MESA spot urine samples based on high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. This method is fast, robust and detects a total of 11 individual As species at method detection limits of 0.02-0.03 µg arsenic/L urine for each individual species. Our analytical approach features excellent mean method accuracy (98%) and precision (5%) for the main arsenic species in urine (arsenobetaine, methylarsonic acid, dimethylarsinic acid, and total inorganic As); intra- (3-6%) and inter-day coefficients of variability (5-6%); column recovery (96 ± 7%); and spike recovery (97 ± 6%). The main arsenic species were detectable in ≥95% of urine samples due to the implementation of an oxidation step. Each individual minor arsenic species was detectable in ≤25% of all urines, although at least one of them was detected in almost half the participants. We identified two minor urinary arsenic species as dimethylarsinoylacetic acid and dimethylarsinoylpropionic acid, potential metabolites of seafood-related arsenicals. We observed differences in individual As species excretion by race/ethnicity, with Asian-American participants featuring 3-4 times higher concentrations compared to other participants. We also found differences by site, body mass index, smoking status, rice intake, and water arsenic levels, potentially indicating different exposures or related to individual bio-metabolism. The proposed approach is suitable for epidemiological studies and the collected data will constitute the base for future research on potential health effects of chronic low-level arsenic exposure.

Influence of folic acid and vitamin B12 supplementation on arsenic methylation: A double-blinded, placebo-controlled trial in Bangladeshi children.

BACKGROUND: Inorganic arsenic is metabolized to monomethyl- (MMAs) and dimethyl- (DMAs) species via one-carbon metabolism (OCM); this facilitates urinary arsenic elimination. OCM is influenced by folate and vitamin B12 and previous randomized control trials (RCTs) showed that folic acid (FA) supplementation increases arsenic methylation in adults. This RCT investigated the effects of FA + B12 supplementation on arsenic methylation in children, a key developmental stage where OCM supports growth. METHODS: A total of 240 participants (8-11 years, 53 % female) drinking from wells with arsenic concentrations > 50 µg/L, were encouraged to switch to low arsenic wells and were randomized to receive 400 µg FA + 5 µg B12 or placebo daily for 12-weeks. Urine and blood samples were collected at baseline, week 1 (only urine) and week 12. Generalized estimated equation (GEE) models were used to assess treatment effects on arsenic species in blood and urine. RESULTS: At baseline, the mean ± SD total blood and urinary arsenic were 5.3 ± 2.9 µg/L and 91.2 ± 89.5 µg/L. Overall, total blood and urine arsenic decreased by 11.7% and 17.6%, respectively, at the end of follow up. Compared to placebo, the supplementation group experienced a significant increase in the concentration of blood DMAs by 14.0% (95% CI 5.0, 25.0) and blood secondary methylation index (DMAs/MMAs) by 0.19 (95% CI: 0.09, 0.35) at 12 weeks. Similarly, there was a 1.62% (95% CI: 0.43, 20.83) significantly higher urinary %DMAs and -1.10% (95% CI: -1.73, -0.48) significantly lower urinary %MMAs in the supplementatio group compared to the placebo group after 1 week. The direction of the changes in the urinary %iAs, %MMAs, and %DMAs at week 12 were consistent with those at week 1, though estimates were not significant. Treatment effects were stronger among participants with higher baseline blood arsenic concentrations. Results were consistent across males and females, and participants with higher and lower folate and B12 status at baseline. CONCLUSION: This RCT confirms that FA + B12 supplementation increases arsenic methylation in children as reflected by decreased MMAs and increased DMAs in blood and urine. Nutritional interventions may improve arsenic methylation and elimination in children, potentially reducing arsenic toxicity while also improving nutritional status.

Analysis of urinary potassium isotopes and association with pancreatic health: healthy, diabetic and cancerous states.

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.

Contribution of arsenic and uranium in private wells and community water systems to urinary biomarkers in US adults: The Strong Heart Study and the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Chronic exposure to inorganic arsenic (As) and uranium (U) in the United States (US) occurs from unregulated private wells and federally regulated community water systems (CWSs). The contribution of water to total exposure is assumed to be low when water As and U concentrations are low. OBJECTIVE: We examined the contribution of water As and U to urinary biomarkers in the Strong Heart Family Study (SHFS), a prospective study of American Indian communities, and the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective study of racially/ethnically diverse urban U.S. communities. METHODS: We assigned residential zip code-level estimates in CWSs (µg/L) and private wells (90th percentile probability of As >10 µg/L) to up to 1485 and 6722 participants with dietary information and urinary biomarkers in the SHFS (2001-2003) and MESA (2000-2002; 2010-2011), respectively. Urine As was estimated as the sum of inorganic and methylated species, and urine U was total uranium. We used linear mixed-effects models to account for participant clustering and removed the effect of dietary sources via regression adjustment. RESULTS: The median (interquartile range) urine As was 5.32 (3.29, 8.53) and 6.32 (3.34, 12.48) µg/L for SHFS and MESA, respectively, and urine U was 0.037 (0.014, 0.071) and 0.007 (0.003, 0.018) µg/L. In a meta-analysis across both studies, urine As was 11% (95% CI: 3, 20%) higher and urine U was 35% (5, 73%) higher per twofold higher CWS As and U, respectively. In the SHFS, zip-code level factors such as private well and CWS As contributed 46% of variation in urine As, while in MESA, zip-code level factors, e.g., CWS As and U, contribute 30 and 49% of variation in urine As and U, respectively. IMPACT STATEMENT: We found that water from unregulated private wells and regulated CWSs is a major contributor to urinary As and U (an estimated measure of internal dose) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide, even at levels below the current regulatory standard. Our findings indicate that additional drinking water interventions, regulations, and policies can have a major impact on reducing total exposures to As and U, which are linked to adverse health effects even at low levels.

Method validation for (ultra)-trace element concentrations in urine for small sample volumes in large epidemiological studies: application to the population-based epidemiological multi-ethnic study of atherosclerosis (MESA).

Analysis of essential and non-essential trace elements in urine has emerged as a valuable tool for assessing occupational and environmental exposures, diagnosing nutritional status and guiding public health and health care intervention. Our study focused on the analysis of trace elements in urine samples from the Multi-Ethnic Study of Atherosclerosis (MESA), a precious resource for health research with limited sample volumes. Here we provide a comprehensive and sensitive method for the analysis of 18 elements using only 100 µL of urine. Method sensitivity, accuracy, and precision were assessed. The analysis by inductively coupled plasma mass spectrometry (ICP-MS) included the measurement of antimony (Sb), arsenic (As), barium (Ba), cadmium (Cd), cesium (Cs), cobalt (Co), copper (Cu), gadolinium (Gd), lead (Pb), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), strontium (Sr), thallium (Tl), tungsten (W), uranium (U), and zinc (Zn). Further, we reported urinary trace element concentrations by covariates including gender, ethnicity/race, smoking and location. The results showed good accuracy and sensitivity of the ICP-MS method with the limit of detections rangings between 0.001 µg L-1 for U to 6.2 µg L-1 for Zn. Intra-day precision for MESA urine analysis varied between 1.4% for Mo and 26% for Mn (average 6.4% for all elements). The average inter-day precision for most elements was <8.5% except for Gd (20%), U (16%) and Mn (19%) due to very low urinary concentrations. Urinary mean concentrations of non-essential elements followed the order of Sr > As > Cs > Ni > Ba > Pb > Cd > Gd > Tl > W > U. The order of urinary mean concentrations for essential trace elements was Zn > Se > Mo > Cu > Co > Mn. Non-adjusted mean concentration of non-essential trace elements in urine from MESA participants follow the order Sr > As > Cs > Ni > Ba > Pb > Cd > Gd > Tl > W > U. The unadjusted urinary mean concentrations of essential trace elements decrease from Zn > Se > Mo > Cu > Co > Mn.

Urinary Metal Levels and Coronary Artery Calcification: Longitudinal Evidence in the Multi-Ethnic Study of Atherosclerosis (MESA).

Objective: Growing evidence indicates that exposure to metals are risk factors for cardiovascular disease (CVD). We hypothesized that higher urinary levels of metals with prior evidence of an association with CVD, including non-essential (cadmium , tungsten, and uranium) and essential (cobalt, copper, and zinc) metals are associated with baseline and rate of change of coronary artery calcium (CAC) progression, a subclinical marker of atherosclerotic CVD. Methods: We analyzed data from 6,418 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) with spot urinary metal levels at baseline (2000-2002) and 1-4 repeated measures of spatially weighted coronary calcium score (SWCS) over a ten-year period. SWCS is a unitless measure of CAC highly correlated to the Agatston score but with numerical values assigned to individuals with Agatston score=0. We used linear mixed effect models to assess the association of baseline urinary metal levels with baseline SWCS, annual change in SWCS, and SWCS over ten years of follow-up. Urinary metals (adjusted to µg/g creatinine) and SWCS were log transformed. Models were progressively adjusted for baseline sociodemographic factors, estimated glomerular filtration rate, lifestyle factors, and clinical factors. Results: At baseline, the median and interquartile range (25th, 75th) of SWCS was 6.3 (0.7, 58.2). For urinary cadmium, the fully adjusted geometric mean ratio (GMR) (95%Cl) of SWCS comparing the highest to the lowest quartile was 1.51 (1.32, 1.74) at baseline and 1.75 (1.47, 2.07) at ten years of follow-up. For urinary tungsten, uranium, and cobalt the corresponding GMRs at ten years of follow-up were 1.45 (1.23, 1.71), 1.39 (1.17, 1.64), and 1.47 (1.25, 1.74), respectively. For copper and zinc, the association was attenuated with adjustment for clinical risk factors; GMRs at ten years of follow-up before and after adjustment for clinical risk factors were 1.55 (1.30, 1.84) and 1.33 (1.12, 1.58), respectively, for copper and 1.85 (1.56, 2.19) and 1.57 (1.33, 1.85) for zinc. Conclusion: Higher levels of cadmium, tungsten, uranium, cobalt, copper, and zinc, as measured in urine, were associated with subclinical CVD at baseline and at follow-up. These findings support the hypothesis that metals are pro-atherogenic factors.

Endotracheal nebulization of gold nanoparticles for noninvasive pulmonary drug delivery.

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.

Enterotoxin tilimycin from gut-resident Klebsiella promotes mutational evolution and antibiotic resistance in mice.

Klebsiella spp. that secrete the DNA-alkylating enterotoxin tilimycin colonize the human intestinal tract. Numbers of toxigenic bacteria increase during antibiotic use, and the resulting accumulation of tilimycin in the intestinal lumen damages the epithelium via genetic instability and apoptosis. Here we examine the impact of this genotoxin on the gut ecosystem. 16S rRNA sequencing of faecal samples from mice colonized with Klebsiella oxytoca strains and mechanistic analyses show that tilimycin is a pro-mutagenic antibiotic affecting multiple phyla. Transient synthesis of tilimycin in the murine gut antagonized niche competitors, reduced microbial richness and altered taxonomic composition of the microbiota both during and following exposure. Moreover, tilimycin secretion increased rates of mutagenesis in co-resident opportunistic pathogens such as Klebsiella pneumoniae and Escherichia coli, as shown by de novo acquisition of antibiotic resistance. We conclude that tilimycin is a bacterial mutagen, and flares of genotoxic Klebsiella have the potential to drive the emergence of resistance, destabilize the gut microbiota and shape its evolutionary trajectory.

Arsenic Exposure, Blood DNA Methylation, and Cardiovascular Disease.

BACKGROUND: Epigenetic dysregulation has been proposed as a key mechanism for arsenic-related cardiovascular disease (CVD). We evaluated differentially methylated positions (DMPs) as potential mediators on the association between arsenic and CVD. METHODS: Blood DNA methylation was measured in 2321 participants (mean age 56.2, 58.6% women) of the Strong Heart Study, a prospective cohort of American Indians. Urinary arsenic species were measured using high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. We identified DMPs that are potential mediators between arsenic and CVD. In a cross-species analysis, we compared those DMPs with differential liver DNA methylation following early-life arsenic exposure in the apoE knockout (apoE-/-) mouse model of atherosclerosis. RESULTS: A total of 20 and 13 DMPs were potential mediators for CVD incidence and mortality, respectively, several of them annotated to genes related to diabetes. Eleven of these DMPs were similarly associated with incident CVD in 3 diverse prospective cohorts (Framingham Heart Study, Women's Health Initiative, and Multi-Ethnic Study of Atherosclerosis). In the mouse model, differentially methylated regions in 20 of those genes and DMPs in 10 genes were associated with arsenic. CONCLUSIONS: Differential DNA methylation might be part of the biological link between arsenic and CVD. The gene functions suggest that diabetes might represent a relevant mechanism for arsenic-related cardiovascular risk in populations with a high burden of diabetes.

Arsenolipids in salmon are partly converted to thioxo analogs during cooking.

BACKGROUND: Arsenic hydrocarbons, major arsenolipids occurring naturally in marine fish, have substantial cytotoxicity leading to human health-related studies of their distribution and abundance in foods. These studies have all investigated fresh foods; because most fish are cooked before being consumed, it is both food- and health-relevant to determine the arsenolipids present in cooked fish. METHODS: We used HPLC/mass spectrometry to investigate the arsenolipids present in salmon (Salmo salar) before and after cooking by either baking or steaming. RESULTS: In raw salmon (total As 2.74 mg kg-1 dry mass, of which 6% was lipid-soluble), major arsenolipids were three arsenic hydrocarbons (oxo-AsHC 332, oxo-AsHC 360, and oxo-AsHC 404, ca 55% of total arsenolipids) and a band of unidentified less-polar arsenolipids (ca 40%), trace amounts of another four arsenic hydrocarbons and two thioxo analogs were also detected. During the cooking process, 28% of the oxo-AsHCs were converted to their thioxo analogs. CONCLUSION: Our study shows that arsenic hydrocarbons naturally present in fresh fish are partly converted to their thioxo analogs during cooking by either baking or steaming. The greater lipophilicity of the thioxo analogs could alter the mode of toxicity of arsenic hydrocarbons, and hence future food regulations for arsenic should consider the influence of cooking on the precise type of arsenolipid in fish.

Exposure to e-cigarette aerosol over two months induces accumulation of neurotoxic metals and alteration of essential metals in mouse brain.

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

Effect of arsenic-containing hydrocarbon on the long-term potentiation at Schaffer Collateral-CA1 synapses from infantile male rat.

Arsenic-containing hydrocarbons (AsHCs) are common constituents of marine organisms and have potential toxicity to human health. This work is to study the effect of AsHCs on long-term potentiation (LTP) for the first time. A multi-electrode array (MEA) system was used to record the field excitatory postsynaptic potential (fEPSP) of CA1 before and after treatment with AsHC 360 in hippocampal slices from infantile male rats. The element content of Na, K, Ca, Mg, Mn, Cu, Zn, and As in the hippocampal slices were analyzed by elemental mass spectrometry after the neurophysiological experiment. The results showed that low AsHC 360 (1.5 µg As L-1) had no effect on the LTP, moderate AsHC 360 (3.75-15 µg As L-1) enhanced the LTP, and high AsHC 360 (45-150 µg As L-1) inhibited the LTP. The enhancement of the LTP by promoting Ca2+ influx was proved by a Ca2+ gradient experiment. The inhibition of the LTP was likely due to damage of synaptic cell membrane integrity. This study on the neurotoxicity of AsHCs showed that high concentrations have a strong toxic effect on the LTP in hippocampus slices of the infantile male rat, which may lead to a negative effect on the development, learning, and memory.

Arsenolipids in Plankton from High- and Low-Nutrient Oceanic Waters Along a Transect in the North Atlantic.

Although the natural occurrence of arsenic-containing lipids (arsenolipids) in marine organisms is now well established, the possible role of these unusual compounds in organisms and in the cycling of arsenic in marine systems remains largely unexplored. We report the finding of arsenolipids in 61 plankton samples collected from surface marine waters of high- and low-nutrient content along a transect spanning the Gulf Stream in the North Atlantic Ocean. Using high-performance liquid chromatography (HPLC) coupled to both elemental and molecular mass spectrometry, we show that all 61 plankton samples contained six identifiable arsenolipids, namely, three arsenosugar phospholipids (AsPL958, 10-13%; AsPL978, 13-25%; and AsPL1006, 7-10% of total arsenolipids), two arsenic-containing hydrocarbons (AsHC332, 4-10% and AsHC360, 1-2%), and a methoxy-sugar arsenolipid that contained phytol (AsSugPhytol, 1-3%). The relative amounts of the six arsenolipids showed clear dependence on the nutrient status of the ambient water with plankton collected from high-nutrient waters having less of the arsenosugar phospholipids and more of the three non-P containing arsenolipids compared to low-nutrient waters. By combining these first field data of arsenolipids in plankton with reported global phytoplankton productivity, we estimate that the oceans' phytoplankton transform per year 50 000-100 000 tons of arsenic into arsenolipids.

Capabilities of selenoneine to cross the in vitro blood-brain barrier model.

The naturally occurring selenoneine (SeN), the selenium analogue of the sulfur-containing antioxidant ergothioneine, can be found in high abundance in several marine fish species. However, data on biological properties of SeN and its relevance for human health are still scarce. This study aims to investigate the transfer and presystemic metabolism of SeN in a well-established in vitro model of the blood-brain barrier (BBB). Therefore, SeN and the reference Se species selenite and Se-methylselenocysteine (MeSeCys) were applied to primary porcine brain capillary endothelial cells (PBCECs). Se content of culture media and cell lysates was measured via ICP-MS/MS. Speciation analysis was conducted by HPLC-ICP-MS. Barrier integrity was shown to be unaffected during transfer experiments. SeN demonstrated the lowest transfer rates and permeability coefficient (6.7 × 10-7 cm s-1) in comparison to selenite and MeSeCys. No side-directed accumulation was observed after both-sided application of SeN. However, concentration-dependent transfer of SeN indicated possible presence of transporters on both sides of the barrier. Speciation analysis demonstrated no methylation of SeN by the PBCECs. Several derivatives of SeN detected in the media of the BBB model were also found in cell-free media containing SeN and hence not considered to be true metabolites of the PBCECs. In concluding, SeN is likely to have a slow transfer rate to the brain and not being metabolized by the brain endothelial cells. Since this study demonstrates that SeN may reach the brain tissue, further studies are needed to investigate possible health-promoting effects of SeN in humans.

Simultaneous quantification of enterotoxins tilimycin and tilivalline in biological matrices using HPLC high resolution ESMS2 based on isotopically 15N-labeled internal standards.

Non-ribosomal peptides are one class of bacterial metabolites formed by gut microbiota. Intestinal resident Klebsiella oxytoca produces two pyrrolobenzodiazepines, tilivalline and tilimycin, via the same nonribosomal biosynthesis platform. These molecules cause human disease by genotoxic and tubulin inhibitory activities resulting in apoptosis of the intestinal epithelium, loss of barrier integrity and ultimately colitis. Here we report a fast, reliable, HPLC-HR-ESMS2 method for quantifying simultaneously the bacterial enterotoxins tilimycin and tilivalline in complex biological matrices. We synthesized and applied stable isotopically labeled internal standards for precise quantification of the metabolites. Sample preparation was optimized using clinical and laboratory specimens including serum, colonic fluid and stool. The developed method overcame the disadvantage of low selectivity by applying high resolution mass spectrometry in MS2 mode. High sensitivity and low interference from matrices were achieved and validated. We show that the approach is suitable for detection and quantification of the enterotoxic metabolites produced in vivo, in infected human or animal hosts, and in bacterial culture in vitro.

Arsenocholine-O-sulfate: A novel compound as major arsenic species in the parasitic mushroom Tolypocladium ophioglossoides.

The As concentrations, along with 34 other elements, and the As speciation were investigated in wild-grown samples of the parasitic mushroom Tolypocladium ophioglossoides with inductively coupled plasma mass spectrometry (ICPMS) and high performance liquid chromatography coupled to ICPMS. The As concentrations were 0.070-3.44 mg kg-1 dry mass. More remarkable was the As speciation, where up to 56% of the extracted As were found to be an unknown As species, which was marginally retained under anion- and also cation-exchange conditions. After testing several different chromatographic settings, the compound was finally isolated and identified as 2-(sulfoxyethyl) trimethylarsonium ion (in short: arsenocholine-O-sulfate) with high resolution mass spectrometry. The compound was synthesized and further quantified in all investigated samples via ion-pair chromatography coupled to ICPMS. In addition to the high abundance of arsenocholine-O-sulfate in T. ophioglossoides, small amounts of this As species were also detected in one sample of the host mushroom, Elaphomyces asperulus. In a sample of another parasitic mushroom, Ophiocordyceps sinensis, arsenocholine-O-sulfate could not be detected, but the main species was another unknown compound that was oxidized to inorganic As(V) with hydrogen peroxide. This is the first discovery of arsenocholine-O-sulfate in nature. It is possible that it is present in many other organisms, at least in low concentrations, and just has not been detected there yet because of its unusual chromatographic behavior. The existence of arsenocholine-O-sulfate brings up questions again about the biotransformation pathways of As in the environment and the specific behavior of fungi.