Globin adducts of various chemicals, persisting in organism over the whole lifetime of erythrocytes, have been used as biomarkers of cumulative exposures to parent compounds. After removal of aged erythrocytes from the bloodstream, cleavage products of these adducts are excreted with urine as alternative, non-invasively accessible biomarkers. In our biomonitoring studies on workers exposed to ethylene oxide, its adduct with globin, N-(2-hydroxyethyl)valine, and the related urinary cleavage product N-(2-hydroxyethyl)-L-valyl-L-leucine have been determined. To describe a toxicokinetic relationship between the above types of biomarkers, a general compartmental model for simulation of formation and removal of globin adducts has been constructed in the form of code in R statistical computing environment. The essential input variables include lifetime of erythrocytes, extent of adduct formation following a single defined exposure, and parameters of exposure scenario, while other possible variables are optional. It was shown that both biomarkers reflect the past exposures differently as the adduct level in globin is a mean value of adduct levels across all compartments (subpopulations of erythrocytes of the same age) while excretion of cleavage products reflects the adduct level in the oldest compartment. Application of the model to various scenarios of continuous exposure demonstrated its usefulness for human biomonitoring data interpretation.
- MeSH
- biologické markery * moč krev MeSH
- biologické modely MeSH
- biologický monitoring * MeSH
- erytrocyty * metabolismus účinky léků MeSH
- ethylenoxid toxicita farmakokinetika moč MeSH
- globiny metabolismus MeSH
- lidé MeSH
- počítačová simulace MeSH
- pracovní expozice * MeSH
- toxikokinetika MeSH
- valin analogy a deriváty farmakokinetika moč krev MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Závěrečná zpráva o řešení grantu Agentury pro zdravotnický výzkum MZ ČR
nestr.
Although the adducts with globin have been widely used in preventive medicine as biomarkers of long-term exposures to reactive chemicals, we were the first to explore their subsequent fate in the organism. We found in rats that hydrolytic cleavage of the globin adducts produces amino acid or dipeptide adducts that are excreted in urine. In our current project we will investigate urinary excretion of these cleavage products in humans. First, we plan to develop and implement into public health practice new strategies of biomonitoring of industrial toxicants ethylene oxide and N,N-dimethylformamide, based on analysis of urine instead of blood. Obtained data will be used to create a general statistical model allowing to interpret urinary levels of cleavage products from other chemicals including carcinogens. Implementation of a novel promising category of biomarkers that combine specificity for the parent xenobiotic, monitoring of long-term exposures, and non-invasive sampling will significantly contribute to prevention of health damage due to exposures to chemicals.
Přestože adukty s globinem jsou v preventivní medicíně široce využívány jako biomarkery dlouhodobé expozice reaktivním látkám, jejich další osud v organismu byl poprvé prozkoumán až v našem předchozím projektu. Prokázali jsme, že hydrolytickým štěpením globinových aduktů u potkanů vznikají adukty s aminokyselinami nebo s dipeptidy, vylučované močí. Nyní bude studováno vylučování těchto štěpných produktů u člověka. Budou vypracovány a do hygienické praxe v ČR zavedeny nové strategie biologického monitorování expozice průmyslovým škodlivinám ethylenoxidu a N,N-dimethylformamidu, kdy dosavadní odběry krve budou nahrazeny analýzou moče. Ze získaných údajů bude odvozen obecný matematicko-statistický model umožňující interpretovat nálezy štěpných produktů odvozených od dalších látek včetně karcinogenů, na něž se v projektu též zaměříme. Zavedení zcela nové kategorie biomarkerů specifických pro výchozí látky a vhodných pro hodnocení dlouhodobých expozic pomocí neinvazivního odběru vzorků bude významným přínosem pro prevenci poškození zdraví účinkem chemických látek v mezinárodním měřítku.
Biomonitoring of human exposure to reactive electrophilic chemicals such as ethylene oxide (EO) has been commonly based on the determination of adducts with N-terminal valine in blood protein globin, but a systematic search has also been undertaken to find surrogate markers enabling non-invasive sampling. Recently, N-(2-hydroxyethyl)-L-valyl-L-leucine (HEVL) has been identified as an ultimate cleavage product of EO-adducted globin in the urine of occupationally exposed workers. Herein, full validation of the analytical procedure consisting of solid-phase extraction of HEVL from urine samples (2 mL) followed by high-performance liquid chromatography-electrospray ionization-high-resolution mass spectrometry determination using deuterium-labeled HEVL as an internal standard (IS) is described. Method limit of quantitation is 0.25 ng/mL, and its selectivity is excellent as demonstrated by the invariable ratio of the qualifier and quantifier ion intensities across diverse urine samples and synthetic standard. The linear calibration model was applicable over the whole concentration range tested (0.25-10 ng/mL). The method accuracy assessed as a recovery of HEVL using a spiking experiment was 98-100%. Within-day precision of the method ranged from 1.8% to 3.0%, while the results from consecutive analytical runs conducted within 1 week or within 10-150 weeks differed in the range of 2.2-9.7%. The stability study on urine samples (-20°C up to 3 years, freeze-and-thaw up to 10 cycles) as well as on aqueous solutions (5°C up to 4 months) indicated no relevant changes in HEVL concentration (≤4%) over the time tested. Analytical responses of both HEVL and IS correlated with urinary creatinine as an index of matrix composition, but this matrix effect was mostly eliminated using the HEVL/IS peak area ratio, attaining the IS-normalized relative matrix effect <3%. In conclusion, the method complied successfully with the bioanalytical method validation criteria, making it a reliable tool for HEVL determination in human biomonitoring.
- MeSH
- dipeptidy * MeSH
- ethylenoxid * MeSH
- globiny MeSH
- leucin MeSH
- lidé MeSH
- reprodukovatelnost výsledků MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
OBJECTIVES: Isocyanates are known to induce occupational diseases. The aim of this work was to assess the health effects of exposure to isocyanates and to test the sensitivity of selected parameters for early detection of isocyanate-related allergic diseases. METHODS: In total, 35 employees from one factory were tested: 26 workers exposed to isocyanates (exposed group) and nine office workers (control group). All subjects filled in a questionnaire regarding possible health problems. Fractional exhaled nitric oxide (FeNO) and spirometry were measured for each subject at the same time during two consecutive working days. A urine sample was taken for a biological exposure test (BET). RESULTS: No significant difference was found between the exposed and control groups for spirometry parameters and FeNO. However, in the exposed group, FeNO was highly elevated (> 50 ppb) in five subjects (all reporting health problems at the workplace, all with normal spirometry and non-smokers). The BET revealed a significant difference (p < 0.001) between the exposed and control groups for 4,4 ́-methylenediphenyl diamine (MDA) in the urine. CONCLUSIONS: Our examination showed the usefulness of the BET in monitoring of workplace exposure to isocyanates and the importance of FeNO in monitoring of allergic inflammation of airways in non-smoking employees with normal spirometry.
- MeSH
- automobily MeSH
- isokyanatany analýza moč MeSH
- lidé MeSH
- nemoci z povolání * MeSH
- pracoviště MeSH
- pracovní expozice * škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Novel aminonaphthylcysteine (ANC) adducts, formed via naphthylnitrenium ions and/or their metabolic precursors in the biotransformation of naphthylamines (NA) and nitronaphthalenes (NN), were identified and quantified in globin of rats dosed intraperitoneally with 0.16 mmol/kg b.w. of 1-NA, 1-NN, 2-NA and 2-NN. Using HPLC-ESI-MS2 analysis of the globin hydrolysates, S-(1-amino-2-naphthyl)cysteine (1A2NC) together with S-(4-amino-1-naphthyl)cysteine (4A1NC) were found in rats given 1-NA or 1-NN, and S-(2-amino-1-naphthyl)cysteine (2A1NC) in those given 2-NA or 2-NN. The highest level of ANC was produced by the most mutagenic and carcinogenic isomer 2-NA (35.8 ± 5.4 nmol/g globin). The ratio of ANC adduct levels for 1-NA, 1-NN, 2-NA and 2-NN was 1:2:100:3, respectively. Notably, the ratio of 1A2NC:4A1NC in globin of rats dosed with 1-NA and 1-NN differed significantly (2:98 versus 16:84 respectively), indicating differences in mechanism of the adduct formation. Moreover, aminonaphthylmercapturic acids, formed via conjugation of naphthylnitrenium ions and/or their metabolic precursors with glutathione, were identified in the rat urine. Their amounts excreted after dosing rats with 1-NA, 1-NN, 2-NA and 2-NN were in the ratio 1:100:40:2, respectively. For all four compounds tested, haemoglobin binding index for ANC was several-fold higher than that for the sulphinamide adducts, generated via nitrosoarene metabolites. Due to involvement of electrophilic intermediates in their formation, ANC adducts in globin may become toxicologically more relevant biomarkers of cumulative exposure to carcinogenic or non-carcinogenic arylamines and nitroarenes than the currently used sulphinamide adducts.
- MeSH
- 1-naftylamin aplikace a dávkování metabolismus toxicita MeSH
- 2-naftylamin aplikace a dávkování metabolismus toxicita MeSH
- acetylcystein analogy a deriváty moč MeSH
- biologické markery krev moč MeSH
- cystein MeSH
- globiny metabolismus MeSH
- injekce intraperitoneální MeSH
- naftaleny aplikace a dávkování krev toxicita MeSH
- potkani Wistar MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
The plant extract aristolochic acid (AA), containing aristolochic acids I (AAI) and II (AAII) as major components, causes aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN), unique renal diseases associated with upper urothelial cancer. Recently (Chemical Research in Toxicology 33(11), 2804-2818, 2020), we showed that the in vivo metabolism of AAI and AAII in Wistar rats is influenced by their co-exposure (i.e., AAI/AAII mixture). Using the same rat model, we investigated how exposure to the AAI/AAII mixture can influence AAI and AAII DNA adduct formation (i.e., AA-mediated genotoxicity). Using 32P-postlabelling, we found that AA-DNA adduct formation was increased in the livers and kidneys of rats treated with AAI/AAII mixture compared to rats treated with AAI or AAII alone. Measuring the activity of enzymes involved in AA metabolism, we showed that enhanced AA-DNA adduct formation might be caused partially by both decreased AAI detoxification as a result of hepatic CYP2C11 inhibition during treatment with AAI/AAII mixture and by hepatic or renal NQO1 induction, the key enzyme predominantly activating AA to DNA adducts. Moreover, our results indicate that AAII might act as an inhibitor of AAI detoxification in vivo. Consequently, higher amounts of AAI might remain in liver and kidney tissues, which can be reductively activated, resulting in enhanced AAI DNA adduct formation. Collectively, these results indicate that AAII present in the plant extract AA enhances the genotoxic properties of AAI (i.e., AAI DNA adduct formation). As patients suffering from AAN and BEN are always exposed to the plant extract (i.e., AAI/AAII mixture), our findings are crucial to better understanding host factors critical for AAN- and BEN-associated urothelial malignancy.
- MeSH
- adukty DNA metabolismus MeSH
- DNA nádorová metabolismus MeSH
- karcinogeneze * chemicky indukované metabolismus MeSH
- karcinogeny toxicita MeSH
- krysa rodu rattus MeSH
- kyseliny aristolochové toxicita MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Publikační typ
- abstrakt z konference MeSH
