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1,3-Butadiene (BD) is classified as a human carcinogen, and occupational exposure should be minimized. This study examined the effectiveness of personal protective equipment (PPE) during the clean-up and repair of a storage tank containing sludge contaminated with BD. A total of 66 workers participated, providing repeat urine samples before and after the shift. Overall, 1286 samples were analyzed for 1,2-dihydroxy-4-(N-acetylcysteinyl)butane (DHBMA) and the isomers 2-hydroxy-1-(N-acetylcysteinyl)-3-butene and 1-hydroxy-2-(N-acetylcysteinyl)-3-butene (MHBMA). Both DHBMA and MHBMA are urinary metabolites of BD and serve as biomarkers for recent BD exposure. Established correlations between the urinary concentrations of these biomarkers and airborne BD levels allowed for exposure assessment. However, conclusions regarding the exceedances of occupational exposure limits can vary depending on whether DHBMA or MHBMA levels are considered. This study investigated this discrepancy by estimating the apparent urinary half-lives of DHBMA and MHBMA using sequential individual post- and pre-shift samples. The results indicated that the longer urinary half-life of MHBMA (19.7 ± 3.1 h) led to its accumulation during the work week, in contrast to DHBMA, which has a shorter half-life (10.3 ± 1.9 h) and showed limited accumulation. When the kinetic information was used to adjust for the MHBMA build-up over the week, the discrepancy with DHBMA resolved, confirming that exposure limit values were not exceeded and validating the effectiveness of the PPE used. In the context of biomonitoring, this study provides valuable insights into biomarker selection based on specific objectives. MHBMA is recommended for scenarios with uncertain exposure timing and activities, whereas DHBMA is the preferred biomarker for evaluating the effectiveness of protective measures in known exposure settings. [ABSTRACT FROM AUTHOR]

1,3-Butadiene (BD) is classified as a human carcinogen, and occupational exposure should be minimized. This study examined the effectiveness of personal protective equipment (PPE) during the clean-up and repair of a storage tank containing sludge contaminated with BD. A total of 66 workers participated, providing repeat urine samples before and after the shift. Overall, 1286 samples were analyzed for 1,2-dihydroxy-4-(N-acetylcysteinyl)butane (DHBMA) and the isomers 2-hydroxy-1-(N-acetylcysteinyl)-3-butene and 1-hydroxy-2-(N-acetylcysteinyl)-3-butene (MHBMA). Both DHBMA and MHBMA are urinary metabolites of BD and serve as biomarkers for recent BD exposure. Established correlations between the urinary concentrations of these biomarkers and airborne BD levels allowed for exposure assessment. However, conclusions regarding the exceedances of occupational exposure limits can vary depending on whether DHBMA or MHBMA levels are considered. This study investigated this discrepancy by estimating the apparent urinary half-lives of DHBMA and MHBMA using sequential individual post- and pre-shift samples. The results indicated that the longer urinary half-life of MHBMA (19.7 ± 3.1 h) led to its accumulation during the work week, in contrast to DHBMA, which has a shorter half-life (10.3 ± 1.9 h) and showed limited accumulation. When the kinetic information was used to adjust for the MHBMA build-up over the week, the discrepancy with DHBMA resolved, confirming that exposure limit values were not exceeded and validating the effectiveness of the PPE used. In the context of biomonitoring, this study provides valuable insights into biomarker selection based on specific objectives. MHBMA is recommended for scenarios with uncertain exposure timing and activities, whereas DHBMA is the preferred biomarker for evaluating the effectiveness of protective measures in known exposure settings.

Exposure to the vinyl monomer acrylonitrile (AN) is primarily occupational. AN is also found in cigarette smoke. AN can be detoxified to form N -acetyl-S-(2-cyanoethyl)-cysteine (CEMA) or activated to 2-cyanoethylene oxide (CEO) and detoxified to form N -acetyl-S-(1-cyano-2-hydroxyethyl)-cysteine (CHEMA) and N -acetyl-S-(2-hydroxyethyl)-cysteine (HEMA). These urinary mercapturic acids (MAs) are considered to be potential biomarkers of AN exposure. This study assessed personal AN exposure, urinary MAs (CEMA, CHEMA, and HEMA), and cotinine (a biomarker of cigarette smoke) in 80 AN-exposed and 23 non-exposed factory workers from urine samples provided before and after work shifts. Unambiguous linear correlations were observed between levels of urinary CEMA and CHEMA with personal AN exposures, indicating their potential as chemically-specific biomarkers for AN exposures. AN exposure was the dominant factor in MA formation for AN-exposed workers, whereas urinary cotinine used as a biomarker showed that cigarette smoke exposure was the primary factor for non-exposed workers. The CHEMA/CEMA and (CHEMA+HEMA)/CEMA ratios in this human study differ from those in similar studies of AN-treated rats and mice in literature, suggesting a possible dose- and species-dependent effect in AN metabolic activation and detoxification. [Display omitted] • Systematic comparison of urinary CEMA, CHEMA, and HEMA between AN- and non-exposed workers. • Unambiguous linear correlation between urinary CEMA and CHEMA and personal AN exposures. • Revelation of CEMA and CHEMA as potential chemically-specific biomarkers for AN exposures. • Illustration of dose- and species-dependent in AN metabolic activation and detoxification. [ABSTRACT FROM AUTHOR]

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• 1,3-dichorobenzene is an occupationally relevant noxious agent in silicone rubber industry. • First method to quantify urinary mercapturates of 1,3-dichlorobenzene using online-SPE LC-MS/MS. • Authentic mercapturate standards and labelled analogues were self-synthesized. • The method is fully automated, precise, sensitive and accurate. • Post-shift urine of exposed workers shows that mercapturates are suitable biomarkers. 1,3-dichlorobenzene (1,3-DCB) is an aromatic solvent that might be formed during thermal decomposition of bis(2,4-dichlorobenzoyl)peroxide used as initiator in silicone rubber production with many workers exposed worldwide. During metabolism of 1,3-DCB, two isomeric mercapturic acids can be formed from ring oxidation of 1,3-DCB in the liver, namely 2,4-dichlorophenylmercapturic acid (24CPhMA) and 3,5-dichlorophenylmercapturic acid (35CPhMA). These urinary mercapturic acids might serve as biomarkers of the toxicologically relevant absorbed dose of 1,3-DCB and have not been determined so far. Thus, we were aimed to develop an analytical method for quantification of these biomarkers. Authentic standards of both mercapturic acids as well as deuterium-labelled analogues were self-synthesized. A method for the quantification of both CPhMAs in human urine using online-SPE LC/MS/MS was developed and validated with an LOQ of 0.1 ng mL−1 for both CPhMAs. The analytes were extracted from urine by online-SPE on a restricted access material phase, transferred to the analytical column and quantified by tandem mass spectrometry. Interday (n = 6) and Intraday (n = 10) precision for both CPhMAs ranged from 1.7 to 4.3 % with accuracies between 99.4 and 109.9 % at concentrations of 0.6 and 3 ng mL−1. We applied the method on post-shift urine samples of 16 workers of the silicone rubber industry with occupational exposure to 1,3-DCB. Both CPhMAs were above LOQ in 15 of 16 urine samples with median levels (range) for 24CPhMA and 35CPhMA of 1.64 ng mL−1 (<0.1 – 8.2 ng mL−1) and 3.98 ng mL−1 (0.36 – 24.1 ng mL−1), respectively. This is the first report on specific urinary mercapturic acids of 1,3-DCB in humans. Our results show that ring oxidation of 1,3-DCB is considered to be a toxicologically relevant metabolic pathway in humans. This might improve risk assessment of 1,3-DCB-emissions in silicone rubber industry. [ABSTRACT FROM AUTHOR]

Ochratoxin A (OTA) is a widespread food contaminant, with exposure estimated to range from 0.64 to 17.79 ng/kg body weight (bw) for average consumers and from 2.40 to 51.69 ng/kg bw per day for high consumers. Current exposure estimates are, however, associated with considerable uncertainty. While biomarker-based approaches may contribute to improved exposure assessment, there is yet insufficient data on urinary metabolites of OTA and their relation to external dose to allow reliable estimates of daily intake. This study was designed to assess potential species differences in phase II biotransformation in vitro and to establish a correlation between urinary OTA-derived glucuronides and mercapturic acids and external exposure in rats in vivo. In vitro analyses of OTA metabolism using the liver S9 of rats, humans, rabbits and minipigs confirmed formation of an OTA glucuronide but provided no evidence for the formation of OTA-derived mercapturic acids to support their use as biomarkers. Similarly, OTA-derived mercapturic acids were not detected in urine of rats repeatedly dosed with OTA, while indirect analysis using enzymatic hydrolysis of the urine samples prior to LC–MS/MS established a linear relationship between urinary glucuronide excretion and OTA exposure. These results support OTA-derived glucuronides but not mercapturic acids as metabolites suitable for biomonitoring.

Up to date, information on the validity of human biomonitoring (HBM) parameters of naphthalene exposure is poor. This study was performed to reveal the relation between occupational exposure to naphthalene and biological exposure markers. Therefore, ten lowly and highly exposed workers from the abrasives industry were selected to characterise a broad exposure range. Naphthalene in air was determined by personal air monitoring during one shift. For biological monitoring, pre- and post-shift urine samples collected on 2 days of a working week were analysed for 1,2-dihydroxynaphthalene (1,2-DHN), 1- and 2-naphthol, 1- and 2-naphthylmercapturic acid (NMA). The naphthalene concentration in air was in the range of 0.5 to 11.6 mg/m3. The biomarkers in urine showed post-shift concentration in the range of 114–51,809 µg/L for 1,2-DHN, 0.8–666 µg/L for 1–NMA, 2–2698 µg/L for 1-naphthol and 4–1135 µg/L for 2-naphthol, respectively. 2-NMA was not detected. The urinary levels increased significantly from pre- to post-shift for all analysed parameters and an accumulation over the working week was observed. Significant positive correlations were observed between 1,2-DHN, 1-NMA, 1- and 2-naphthol in post-shift urine samples and personal exposure to naphthalene in the air. 1-NMA and 1,2-DHN, 1- and 2-naphthol have been demonstrated as suitable biomarkers for naphthalene exposure monitoring. Of the determined biomarkers, 1,2-DHN is by far the metabolite with the highest concentration in the urine samples. [ABSTRACT FROM AUTHOR]

Acrylamide (AA) is a heat-induced food contaminant considered as genotoxic carcinogen. The present study investigated the influence of nutritional and lifestyle preferences on human AA exposure. A 10-day human study was performed with ten volunteers without nutritional preferences (omnivores) and ten vegans. Volunteers self-reported their daily routine and dietary habits. Overall mean AA intake, calculated from contents of diet duplicates, was 0.32 ± 0.19 µg/kg body weight (bw)/day with marked inter-day and inter-volunteer variabilities. Vegans ingested more AA (0.38 ± 0.23 µg/kg bw/day) than omnivore volunteers without dietary restrictions (0.26 ± 0.10 µg/kg bw/day). Excretion kinetics of urinary AA-related mercapturic acids N-acetyl-S-(2-carbamoylethyl)-l-cysteine and N-acetyl-S-(2-hydroxy-2-carbamoylethyl)-l-cysteine were essentially concordant with the respective dietary AA intake. Disproportionately enhanced AA-related biomarker excretion could be traced back to reportedly inadvertent, passive exposure to tobacco and/or fire smoke, as evidenced by the respective urinary exposure biomarkers, cotinine and N-acetyl-S-(2-cyanoethyl)-l-cysteine. Although the study is based on the comparison of small volunteer groups, the results confirm the association of AA exposure biomarkers with documented dietary preferences and lifestyle factors. Some additional contribution of endogenous background AA exposure was demonstrated individually. Disproportionately enhanced AA exposure is suggested to result from passive exposure to tobacco and/or barbecue smoke. [ABSTRACT FROM AUTHOR]

Highlights • Heated reactions with Gly-Amadori, 13C 5 -TTCA, cysteine, and glycine were studied. • Moderate dosage of glycine to cysteine was optimum in yielding meaty flavors. • TTCA/glycine reaction was better than Gly-Amadori/cysteine to yield meaty flavors. • Propose possible pathways of flavors formed in cysteine-xylose-glycine reactions. • 13C-labeling clarified roles of initial Maillard intermediates in flavor formation. Abstract Volatile compounds formed in model reactions involving synthesized initial Maillard intermediates Gly-Amadori and [13C 5 ]-2-threityl-thiazolidine-4-carboxylic acids ([13C 5 ]-TTCA) in different molar ratios and free cysteine and glycine were investigated by solid-phase microextraction/gas chromatography-mass spectrometry and gas chromatography-olfactometry. The 1:1 ratio composition pattern provided the highest yields of all the sulfur-containing compounds, the potent meaty flavors or their 13C-labeled/unlabeled fractions, indicating a moderate level of glycine relative to cysteine was optimum for maximally yielding meaty flavors in complex meat-like Maillard systems containing cysteine as well as glycine. In addition, the 1:1 ratio composition led to formation of 13C-labeled molecules of some key meaty flavors e.g. 2-furanthiol representing over 70%, indicating TTCA/glycine reaction was better than Gly-Amadori/cysteine to yield meaty flavors. Formation pathways of twenty-nine flavors were elucidated based on the detected isotope distribution patterns. In particular, 2-methyltetrahydrothiophen-3-one, 3-thiophenethiol, 2-ethylthiophene, 2,5-dimethylthiophene, and 5-methylthiophene-2-carboxaldehyde involved a new formation pathway. Thiophene-2-carboxaldehyde and 2-methylthieno[3,2- b ]thiophene showed two formation pathways. [ABSTRACT FROM AUTHOR]

Abstract Thirty-four novel, diaryl ω-(isothiocyanato)alkylphosphonates with chlorine atom and methoxy, dimethoxy, methylsulfanyl, or methoxycarbonyl groups at ortho , meta , or para positions of the phenyl ring, and with an unbranched alkyl chain (n = 2–6) were designed and synthesized in a one-pot reaction in 11–76% yields. All isothiocyanates thus generated were evaluated for the first time for antibacterial activity on Pseudomonas aeruginosa and Staphylococcus aureus bacterial strains, and had satisfactory antibacterial activity in most cases. The highest activity, similar to that of reference gentamicin activity against S. aureus , was seen in compounds 9 and 13 (1.5 ± 0.1 and 2.5 ± 0.2 μM, respectively), whereas for P. aeruginosa more than half of tested compounds proved to be more effective than gentamicin. Additionally, selected isothiocyanates (9 , 13 , 18 , and 23) were transformed in 52–73% yields into mercapturic acids 42 – 45 , which also exhibited satisfactory antibacterial effect against S. aureus strain. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Chronic benzene exposure is associated with hematotoxicity and the development of aplastic anemia and leukemia. However, the signaling pathways underlying benzene-induced hematotoxicity remain to be defined. Here, we investigated the role of protein phosphatase 2A (PP2A) in the regulation of benzeneinduced hematotoxicity in a murine model. Male mice with a hepatocyte-specific homozygous deletion of the Ppp2r1a gene (encoding PP2A Aα subunit) (HO) and matched wildtype (WT) mice were exposed to benzene via inhalation at doses of 1, 10, and 100 ppm for 28 days. Peripheral white blood cell counts and activation of bone marrow progenitors were attenuated in the HOmice, indicating that Ppp2r1a deletion protects against benzene-induced hematotoxicity. Moreover, elevation of urinary S-phenyl mercapturic acid, a benzene metabolite, was much greater inWTmice than inHOmice. Real-time exhalation analysis revealed more exhaled benzene but fewer benzene metabolites in HO mice than in WT mice, possibly because of the down-regulation of Cyp2e1, encoding cytochrome P4502E1, in hepatocytes of the HO mice. Loss-of-function screening disclosed that PP2A complexes containing the B56α subunit participate in regulating Cyp2e1 expression. Notably, PP2A-B56α suppressioninHepG2cellsresultedinpersistentγ-cateninphosphorylation at Ser33-Ser37-Thr41 in response to CYP2E1 agonists. In parallel, nuclear translocation of β-catenin was inhibited, concomitant with a remarkable decrease of Cyp2e1 expression. These findings support the notion that a regulatory cascade comprising PP2A-B56α, β-catenin, and Cyp2e1 is involved in benzene-induced hematotoxicity, providing critical insight into the role of PP2A in responses to the environmental chemicals. [ABSTRACT FROM AUTHOR]

This review on recent research advances of the lipid peroxidation product 4-hydroxy-nonenal (HNE) has four major topics: I. the formation of HNE in various organs and tissues, II. the diverse biochemical reactions with Michael adduct formation as the most prominent one, III. the endogenous targets of HNE, primarily peptides and proteins (here the mechanisms of covalent adduct formation are described and the (patho-) physiological consequences discussed), and IV. the metabolism of HNE leading to a great number of degradation products, some of which are excreted in urine and may serve as non-invasive biomarkers of oxidative stress.

The urinary metabolites cyanoethyl mercapturic acid (CEMA) and 3-hydroxypropyl mercapturic acid (3-HPMA) have been widely used as biomarkers of exposure to acrylonitrile and acrolein, respectively, but there are no published data on their consistency over time in the urine of cigarette smokers. We provided, free of charge over a 20 week period, Spectrum NRC600/601 research cigarettes to cigarette smokers in the control arm of a randomized clinical trial of the reduced nicotine cigarette. Urine samples were collected at weeks 4, 8, 12, 16, and 20 and analyzed for CEMA and 3-HPMA, and total nicotine equivalents (TNE) using validated methods. Creatinine-corrected intra-class correlation coefficients for CEMA, 3-HPMA, and TNE were 0.67, 0.46, and 0.68, respectively, indicating good longitudinal consistency for CEMA, while that of 3-HPMA was fair. A strong correlation between CEMA and TNE values was observed. These data support the use of CEMA as a reliable biomarker of tobacco smoke exposure. This is the first report of the longitudinal stability of the biomarkers of acrylonitrile and acrolein exposure in smokers. The data indicate that CEMA, the biomarker of acrylonitrile exposure, is consistent over time in cigarette smokers, supporting its use. While 3-HPMA levels were less stable over time, this biomarker is nevertheless a useful monitor of human acrolein exposure because of its specificity to this toxicant. [ABSTRACT FROM AUTHOR]

Highlights • Occupationally naphthalene exposed workers were monitored. • Naphthalene in the air and 5 naphthalene metabolites in urine were analysed. • 1,2-Dihydroxynaphthalene is the principal metabolite of naphthalene in human urine. • 1-naphthylmercapturic acid formation is a minor, but very specific pathway. • Further studies with 1,2-DHN and 1- naphthylmercapturic acid are needed. Abstract Naphthalene occurs together with polycyclic aromatic hydrocarbons (PAHs) at industrial workplaces and is ubiquitous in the environment. For biological monitoring of naphthalene exposures, up to now mainly 1- and 2-naphthol in urine have been used. Recently, we proposed 1,2-dihydroxynaphthalene (1,2-DHN) and the 1- and 2-naphthylmercapturic acid (1- and 2-NMA) as new urinary biomarkers to characterise a naphthalene exposure. In this study, in a collective of nine occupationally exposed workers handling with creosote the naphthalene metabolites 1,2-DHN, 1- and 2-NMA as well as 1- and 2-naphthol were analysed in order to evaluate the suitability of the different parameters for their application in biomonitoring studies. Additionally, air sampling was conducted to characterise the exposure in task related exposure situations at different workplaces. In the analysed 51 urine samples, 1,2-DHN was the main metabolite with concentrations ranging from 2.3 to 886 μg/g creatinine (crea) (median 34 μg/g crea). For the sum of 1- and 2-naphthol, concentrations in the range of 2.6–174 μg/g crea (median 15 μg/g crea) were observed. 1-NMA concentrations were in the range of < LOD-2.4 μg/g crea (61% > LOD), while 2-NMA was not detected in the analysed urine samples. The biomarkers 1,2-DHN, 1- and 2-naphthol as well as 1-NMA showed significant correlations, which pointed out to naphthalene as the common exposure source. The poor correlations between naphthalene in the air and the biomarkers in urine may be a result of the varying exposure situations and may indicate not solely inhalative, but additional dermal uptake. 1,2-DHN was the most sensitive and, together with 1-NMA, the most specific parameter of the biological monitoring of naphthalene exposure at workplaces. Further studies with this parameter are needed for individuals at different workplaces as well as for persons of the general population without occupational PAH exposure to characterise 1,2-DHN levels as well as to establish their relationship with the naphthalene exposure. [ABSTRACT FROM AUTHOR]

Glioblastoma is the most aggressive tumor of the central nervous system and is manifested by diffuse invasion of glioblastoma stem cells into the healthy tissue, chemoresistance and recurrence. Despite aggressive therapy, consisting of maximal surgical resection, radiotherapy and chemotherapy with temozolomide (Temodal®), life expectancy of patients with glioblastoma is typically less than 15 months. In general, natural isothiocyanates isolated from plants of the Cruciferae family are selectively cytotoxic to tumor cells. It has been demonstrated previously that diisothiocyanate-derived mercapturic acids are highly cytotoxic to colon cancer cells. In the present study, the application of diisothiocyanate-derived mercapturic acids led to a decrease in the viability of an established glioblastoma cell line, primary patient-derived sphere-cultured stem cell-enriched cell populations (SCs), and cells differentiated from SCs. Consequently, targeting glioblastoma cells by diisothiocyanate-derived mercapturic acids is a promising approach to restrict tumor cell growth and may be a novel therapeutic intervention for the treatment of glioblastoma. [ABSTRACT FROM AUTHOR]

Abstract: Aims: To compare the effects of (i) high versus low nicotine concentration e‐liquid, (ii) fixed versus adjustable power and (iii) the interaction between the two on: (a) vaping behaviour, (b) subjective effects, (c) nicotine intake and (d) exposure to acrolein and formaldehyde in e‐cigarette users vaping in their everyday setting. Design: Counterbalanced, repeated measures with four conditions: (i) low nicotine (6 mg/ml)/fixed power; (ii) low nicotine/adjustable power; (iii) high nicotine (18 mg/ml)/fixed power; and (iv) high nicotine/adjustable power. Setting: London and the South East, England. Participants: Twenty experienced e‐cigarette users (recruited between September 2016 and February 2017) vaped ad libitum using an eVic Supreme™ with a ‘Nautilus Aspire’ tank over 4 weeks (1 week per condition). Measurements: Puffing patterns [daily puff number (PN), puff duration (PD), interpuff interval (IPI)], ml of e‐liquid consumed, changes to power (where permitted) and subjective effects (urge to vape, nicotine withdrawal symptoms) were measured in each condition. Nicotine intake was measured via salivary cotinine. 3‐Hydroxypropylmercapturic acid (3‐HPMA), a metabolite of the toxicant acrolein, and formate, a metabolite of the carcinogen formaldehyde, were measured in urine. Findings: There was a significant nicotine concentration × power interaction for PD (P < 0.01). PD was longer with low nicotine/fixed power compared with (i) high nicotine/fixed power (P < 0.001) and (ii) low nicotine/adjustable power (P < 0.01). PN and liquid consumed were higher in the low versus high nicotine condition (main effect of nicotine, P < 0.05). Urge to vape and withdrawal symptoms were lower, and nicotine intake was higher, in the high nicotine condition (main effects of nicotine: P < 0.01). While acrolein levels did not differ, there was a significant nicotine × power interaction for formaldehyde (P < 0.05). Conclusions: Use of a lower nicotine concentration e‐liquid may be associated with compensatory behaviour (e.g. higher number and duration of puffs) and increases in negative affect, urge to vape and formaldehyde exposure. [ABSTRACT FROM AUTHOR]

A series of phosphonates, phosphinates and phosphine oxides isothiocyanate-derived mercapturic acids were synthesized. A temperature dependence dynamic proton decoupled 31 P NMR studies indicated that in most cases the compounds were obtained as a mixture of rotamers. Moreover, biologically relevant reversibility of mercapturic acids synthesis from the parental isothiocyanates was confirmed. All compounds were evaluated as highly active antiproliferative agents in vitro in human colon cancer cell lines (LoVo and its doxorubicin-resistant subline LoVo/DX). The cell cycle progression and caspase-3 activity analyses revealed compounds moderate activity as apoptosis inducers and their poor influence on cell cycle progression in the LoVo cells. Our results confirm that isothiocyanate-derived mercapturic acids present a reasonable alternative for the parental compounds, and can replace them in the future studies on isothiocyanates potential as anticancer agents. [ABSTRACT FROM AUTHOR]

Human telomeric DNA is transcribed into telomeric RNA in cells. Telomeric RNA performs the fundamental biological functions such as regulation and protection of chromosome ends. This digest highlights the human telomere RNA G-quadruplex structures, telomere RNA functions, G-quadruplex-binding small molecules, and future prospects. [ABSTRACT FROM AUTHOR]

This study was performed to assess the relation between occupational exposure to N,N-dimethylformamide after an 8 h work shift in the acrylic fibre industry and its three biological markers N-methylformamide (NMFtotal), N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC), and N-methylcarbamoyl adduct at haemoglobin (MCVal). External DMF exposure of 220 workers was determined during the whole shift. A standardised questionnaire was used to obtain information about the worker’s general health status, medical treatment, smoking habits, protective measures, and possible symptoms caused by DMF exposure. NMF and AMCC were analysed in post-shift urine samples and MCVal in blood. For longitudinal assessment the average AMCC concentration was determined over a period of 4 weeks (weekly sampling) in a sub-collective of 89 workers. The median of DMF concentration in air was 3.19 mg/m3 (range < 0.15-46.9 mg/m3). The biological markers showed a median of 4.80 mg/L (range  0.20-50.6 mg/L) for NMFtotal, 4.75 mg/g creatinine (range 0.06-49.6 mg/g creatinine) for AMCC, and 57.5 nmol/g globin (range 0.5-414 nmol/g) for MCVal. A significant linear relationship was observed between DMF in air and NMF as well as between DMF in air and AMCC in post-shift urine samples. The mean AMCC values measured weekly over a period of 4 weeks correlated significantly with MCVal adducts too. Excluding workers who had been using breathing masks on the day of the study led to even tighter correlations. The results of the present study demonstrate the applicability of the DMF biomonitoring parameters NMFtotal in post-shift urine for the present-day exposure assessment, AMCC in the post-shift urine after several shifts for assessment of the cumulative exposure of the previous working days, and MCVal for assessment of long-term exposure during previous weeks and months. The data of the present study enable now the estimation of valid equivalents of these biomonitoring parameters to the external DMF exposure. From the risk assessment point of view, the exposure limit values for AMCC and MCVal, which are directly linked to the presumed toxic intermediate MIC, exhibit a significant advance. [ABSTRACT FROM AUTHOR]

A potential contribution of H. pylori contamination to low-grade inflammation, oxidative stress (OS) and insulin resistance as well as correlations between these parameters in asymptomatic sedentary males was analysed. We enrolled 30 apparently healthy asymptomatic young subjects (18 H. pylori negative and 12 positive) and measured whole blood glucose, glycated haemoglobin, insulin, C-peptide, cortisol, aldosterone, testosterone, thyroid stimulating hormone, C-reactive protein, interleukins 6 and 10, TNF-alpha and comet assay. As markers of OS, we used urine levels of iso-PGF2-α and 1,4-dihydroxynonane mercapturic acid (DHN-MA). Twofold elevation of fasting insulin level and HOMA index in H. pylori-positive subjects (p < .05) was shown. Inflammatory parameters and monocyte DNA damage, urine levels of DHN-MA and iso-PGF2-α did not show significant differences between the groups. The early stage of H. pylori-triggered metabolic derangements in sedentary subjects include development of insulin resistance in H. pylori-positive subjects; however, there is no evidence of systemic inflammatory and OS-related changes. [ABSTRACT FROM AUTHOR]

Introduction: Acrolein is a highly ciliatoxic agent, a toxic respiratory irritant, a cardiotoxicant, and a possible carcinogen present in tobacco smoke including hookah tobacco.Methods: 105 hookah smokers and 103 non-smokers attended exclusively hookah smoking social events at either a hookah lounge or private home, and provided urine samples the morning of and the morning after the event. Samples were analyzed for 3-hydroxypropylmercapturic acid (3-HPMA), a metabolite of acrolein.Results: Geometric mean (GM) urinary 3-HPMA levels in hookah smokers and non-smokers exposed to secondhand smoke (SHS) increased significantly, 1.41 times, 95% CI = 1.15 to 1.74 and 1.39 times, 95% CI = 1.16 to 1.67, respectively, following a hookah social event. The highest increase (1.68 times, 95% CI = 1.15 to 2.45; p = 0.007) in 3-HPMA post a hookah social event was among daily hookah smokers (GM, from 1991 pmol/mg to 3348 pmol/mg). Pre-to-post event change in urinary 3-HPMA was significantly positively correlated with pre-to-post event change in urinary cotinine among hookah smokers at either location of hookah event, (ρ = 0.359, p = 0.001), and among non-smokers in hookah lounges (ρ = 0.369, p = 0.012).Conclusions: Hookah tobacco smoke is a source of acrolein exposure. Findings support regulating hookah tobacco products including reducing humectants and sugar additives, which are precursors of acrolein under certain pyrolysis conditions. We suggest posting health warning signs for indoor smoking in hookah lounges, and encouraging voluntary bans of smoking hookah tobacco in private homes.Implications: Our study is the first to quantify the increase in acrolein exposure in hookah smokers and non-smokers exposed to exclusively hookah tobacco SHS at hookah social events in homes or hookah lounges. Our findings provide additional support for regulating hookah tobacco product content, protecting non-smokers' health by posting health warning signs for indoor smoking in hookah lounges, and encouraging home bans on hookah tobacco smoking to safeguard vulnerable residents. [ABSTRACT FROM AUTHOR]

Glucobrassicin, a quantitatively significant constituent of Brassica vegetables, gives rise to indole-3-carbinol (I3C) and its dimer di-indolylmethane (DIM) when the vegetables are chewed. I3C and DIM have been extensively studied with respect to their anti-carcinogenic properties. However, the presumed intermediate isothiocyanate in their formation, indole-3-methyl isothiocyanate (IMITC), has to our knowledge never been observed, despite the fact that isothiocyanates derived from cruciferous vegetables are known to have anti-carcinogenic properties. Therefore, we investigated the formation and presence in human urine of IMITC by analyzing for its N -acetylcysteine conjugate, IMITC-NAC, in order to gain a more complete understanding of the biochemical pathways leading to formation of I3C and DIM upon consumption of vegetables rich in glucobrassicin. Standard IMITC-NAC was synthesized and its structure confirmed by NMR and MS. IMITC-NAC was identified in extracts of Brussels sprouts chopped in the presence of N -acetylcysteine. An LC-ESI–MS/MS-SRM method for analysis of IMITC-NAC, with [ 13 C, 15 N]IMITC-NAC as internal standard, was developed and validated. Then, ten subjects (7 females) consumed a salad of Brussels sprouts and cabbage (containing 100–500 μmol glucobrassicin) once daily for 3 days. Urine was collected at intervals up to 24 h after vegetable consumption. Levels of IMITC-NAC in the urine of these 10 subjects ranged from 0.2 to 30.2 pmol/mL urine. These results provide the first evidence for the presumed intermediacy of IMITC in the formation of I3C and DIM in humans who consumed Brussels sprouts and cabbage as a source of glucobrassicin. [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore the relation of controlled dietary acrylamide (AA) intake with the excretion of AA-related urinary mercapturic acids (MA), N-acetyl- S-(carbamoylethyl)- l-cysteine (AAMA) and N-acetyl- S-(1-carbamoyl-2-hydroxyethyl)- l-cysteine (GAMA). Excretion kinetics of these short-term exposure biomarkers were monitored under strictly controlled conditions within a duplicate diet human intervention study. One study arm (group A, n = 6) ingested AA via coffee (0.15-0.17 µg/kg bw) on day 6 and in a meal containing an upper exposure level of AA (14.1-15.9 μg/kg bw) on day 10. The other arm (group B) was on AA minimized diet (washout, 0.05-0.06 µg/kg bw) throughout the whole 13-day study period. On day 6, these volunteers ingested CD-AA (1 μg/kg bw). In both arms, urinary MA excretion was continuously monitored and blood samples were taken to determine hemoglobin adducts. Ingestion of four cups of coffee resulted in a slightly enhanced short-term biomarker response within the background range of group B. At the end of the 13-day washout period, group B excreted an AAMA baseline level of 0.14 ± 0.10 µmol/d although AA intake was only about 0.06 µmol/d. This sustained over-proportional AAMA background suggested an endogenous AA baseline exposure level of 0.3-0.4 µg/kg bw/d. The excretion of CD-AA was practically complete within 72-96 h which rules out delayed release of AA (or any other MA precursor) from deep body compartments. The results provide compelling support for the hypothesis of a sustained endogenous AA formation in the human body. [ABSTRACT FROM AUTHOR]

A three column-switching high-performance liquid chromatography (HPLC) using an electrochemical detector (ECD) equipped with a diamond electrode was established to determine 3-hydroxypropylmercapturic acid (3-HPMA) in urine. An extracted urine sample was consecutively fractionated using a strong anion-exchange column (first column) and a C8 column (second column) via a switching valve before application on an Octa Decyl Silyl (ODS) column (third column), followed by ECD analysis. The% recovery of 3-HPMA standard throughout the three-column process and limit of detection (LOD) were 94 ± 1% and 0.1 pmol, respectively. A solid phase extraction step is required for the sensitive analysis of 3-HPMA in urine by column-switching HPLC-ECD despite a decreased% recovery (55%) of urine sample spiked with 100 pmol of 3-HPMA. To test the utility of our column-switching HPLC-ECD method, 3-HPMA levels of 27 urine samples were determined, and the correlation between HPLC-ECD and LC-Electrospray ionization (ESI)-MS/MS method was examined. As a result, the median values of μmol 3-HPMA/g Creatinine (Cre) in urine obtained by column-switching HPLC-ECD and LC–MS/MS were 2.19 ± 2.12 μmol/g Cre and 2.13 ± 3.38 μmol/g Cre, respectively, and the calibration curve (y = 1.5171x − 1.007) exhibited good linearity within a defined range ( r 2 = 0.907). These results indicate that the combination of column-switching HPLC and ECD is a powerful tool for the specific, reliable detection of 3-HPMA in urine. [ABSTRACT FROM AUTHOR]

Prostate cancer (CaP) is often androgen-sensitive malignancy and regresses upon inhibition of androgen signaling. However, CaP, nearly always develops androgen resistance and progresses to aggressive and lethal androgen-independent CaP, which lacks satisfactory therapy. For metastatic CaP, patients are often treated with Taxotere (docetaxel), a cytoskeleton-targeted chemotherapy drug, that provides transient palliative benefit but to which patients rapidly develop drug-resistance. Combination chemotherapy may be used instead, but is more toxic and adds little clinically relevant benefit over docetaxel. Therefore, novel strategies to enhance docetaxel efficacy are needed to effectively treat patients with metastatic CaP. The mercapturic acid pathway, which metabolizes genotoxic and pro-apoptotic toxins, is over-expressed in CaP and plays an important role in carcinogenesis, metastasis and therapy-resistance of CaP. Vicenin-2, a flavonoid derived from Tulsi (holy basil) as an active compound, inhibits the growth of CaP and increases the anti-tumor activity of docetaxel in-vitro and in-vivo . Taken together, the combination of vicenin-2 and docetaxel could be highly effective in the treatment of advanced and metastatic CaP due to their multi-targeting anti-tumor potential. [ABSTRACT FROM AUTHOR]

The ability to detect and visualize cellular events and their associated target biological analytes through use of cell-permeable profluorogenic probes is dependent on the availability of activatable probes that respond rapidly and selectively to target analytes by production of fluorescent reporting molecules whose excitation and emission energies span a broad range. Herein is described a new probe, DCM-Cys, that preferentially reacts with cysteine to form a dicyanomethylene-4H-pyran (DCM) reporter whose red-energy fluorescence can be stimulated by two-photon, near-infrared excitation so as to provide visualization of cysteine presence inside living human cells with a high signal-to-background ratio. These aforementioned characteristics and the ability of DCM-Cys to provide selective, nanomolar-level in vitro cysteine detection, as demonstrated by its lack of significant response to other thiols and potential interfering agents from biological environments, are attributed to the molecular designs of the DCM-Cys probe and DCM reporter. Attachment of an acryl moiety to the DCM reporter via a self-eliminating, electron-withdrawing benzyl alcohol-carbamate linker offers a probe having selective, sensitive reaction with cysteine to rapidly produce a reporter whose energies of excitation and emission (λabsreport= 480 nm, λemisreport = 640 nm) are red -shifted from those of the DCM-Cys probe (λabsprobe = 440 nm, λemisprobe = 550 nm), thereby leading to low background signal from abundant probe and a large signal from the resulting reporter of cysteine presence. [ABSTRACT FROM AUTHOR]

Many dilute nectars consumed by bird pollinators contain secondary metabolites, potentially toxic chemicals produced by plants as defences against herbivores. Consequently, nectar-feeding birds are challenged not only by frequent water excess, but also by the toxin content of their diet. High water turnover, however, could be advantageous to nectar consumers by enabling them to excrete secondary metabolites or their transformation products more easily. We investigated how the alkaloid nicotine, naturally present in nectar of Nicotiana species, influences osmoregulation in white-bellied sunbirds Cinnyris talatala and Cape white-eyes Zosterops virens. We also examined the metabolic fate of nicotine in these two species to shed more light on the post-ingestive mechanisms that allow nectar-feeding birds to tolerate nectar nicotine. A high concentration of nicotine (50 µM) decreased cloacal fluid output and increased its osmolality in both species, due to reduced food intake that led to dehydration. White-eyes excreted a higher proportion of the ingested nicotine-containing diet than sunbirds. However, sugar concentration did not affect nicotine detoxification and elimination. Both species metabolised nicotine, excreting very little unchanged nicotine. Cape white-eyes mainly metabolised nicotine through the cotinine metabolic pathway, with norcotinine being the most abundant metabolite in the excreta, while white-bellied sunbirds excreted mainly nornicotine. Both species also utilized phase II conjugation reactions to detoxify nicotine, with Cape white-eyes depending more on the mercapturic acid pathway to detoxify nicotine than white-bellied sunbirds. We found that sunbirds and white-eyes, despite having a similar nicotine tolerance, responded differently and used different nicotine-derived metabolites to excrete nicotine. [ABSTRACT FROM AUTHOR]

Acrylamide is classified as a probable carcinogen to humans and generated from Maillard reaction. Currently, the short-term exposure to acrylamide was evaluated via external diet sources in vitro or two main mercapturic acid metabolites: N-acetyl- S-(2-carbamoylethyl)- l-cysteine (AAMA) and N-acetyl- S-(2-carbamoyl-2-hydroxyethyl)- l-cysteine (GAMA) in vivo. In the present work, we comprehensively profiled four mercapturic acid metabolites and evaluated their internal exposure in rats and Chinese adolescents. The cumulative excretion of mercapturic acid metabolites contributes 38.4-73.0 and 43.8-63.6 % of total in vivo metabolites of acrylamide in male and female rats, respectively, when 1, 10, and 50 mg/kg bw of acrylamide were orally administered. Toxicokinetic study revealed that the conversion of acrylamide into glycidamide and glutathione coupling process is highly related to the gender and oral gavage dose via evaluating kinetic parameters, accumulative excretion percentages, and molar ratios of oxidative to reductive metabolism. In human study, a total of 101 Chinese adolescents (41 men and 60 women) were enrolled and served with a meal of potato chips, corresponding to a single-dose (12.6 μg/kg bw) exposure to acrylamide. Toxicokinetic work showed that AAMA is an early and predominant metabolite appearing as a biomarker in urine. N-acetyl- S-(2-carbamoylethyl)- l-cysteine-sulfoxide (AAMA-sul), an oxidative product from AAMA, exhibits a higher peak concentration than GAMA and N-acetyl- S-(1-carbamoyl-2-hydroxyethyl)- l-cysteine (iso-GAMA) during the whole 48-h toxicokinetic period. The internal exposure via four mercapturic acid metabolites is associated with the gender and body mass index characteristics. Thus, current study aims at mercapturic acid metabolites as urinary biomarkers and provides comprehensive insights into the short-term internal exposure to acrylamide. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) has so far been considered to facilitate detoxification of soft organic electrophiles through covalent binding at its cysteine (Cys) thiol group, followed by stepwise catalyzed degradation and eventual elimination along the mercapturic acid pathway. Here we show that in contrast to expectation from HSAB theory, Michael-acceptor ketones, aldehydes and esters may form also single, double and triple adducts with GSH involving β-carbon attack at the much harder N-terminus of the γ-glutamyl (Glu) unit of GSH. In particular, formation of the GSH-N single adduct contradicts the traditional view that S alkylation always forms the initial reaction of GSH with Michael-acceptor carbonyls. To this end, chemoassay analyses of the adduct formation of GSH with nine α,β-unsaturated carbonyls employing high performance liquid chromatography and tandem mass spectrometry have been performed. Besides enriching the GSH adductome and potential biomarker applications, electrophilic N-terminus functionalization is likely to impair GSH homeostasis substantially through blocking the γ-glutamyl transferase catalysis of the first breakdown step of modified GSH, and thus its timely reconstitution. The discussion includes a comparison with cyclic adducts of GSH and furan metabolites as reported in literature, and quantum chemically calculated thermodynamics of hard-hard, hard-soft, and soft-soft adducts. [ABSTRACT FROM AUTHOR]

1. The mercapturic acid (MA) pathway is a metabolic route for the processing of glutathione conjugates to MA (N-acetylcysteine conjugates). AnN-acetyltransferase enzyme, NAT8, catalyzes the transfer of an acetyl group from acetyl-CoA to the cysteine amino group, producing a MA, which is excreted in the urine. We expressed human NAT8 in HEK293T cells and developed an HPLC-MS method for the quantitation of theS-aryl-substituted cysteine conjugates and their MA. 2. We measured the activity of the enzyme for acetylation of benzyl-, 4-nitrobenzyl-, and 1-menaphthylcysteine substrates. 3. NAT8 catalyzed the acetylation of all three cysteine conjugates with similar Michaelis–Menten kinetics. [ABSTRACT FROM PUBLISHER]