Ethylene oxide (EO), a carcinogenic chemical used as an industrial intermediate and sterilant, forms covalent adducts with DNA and proteins. The adduct with N-terminal valine [N-(2-hydroxyethyl)-l-valine, HEV] in blood protein globin has been employed as a principal biomarker of cumulative exposures to EO. However, as sampling of blood is inconvenient in routine occupational health practice, a non-invasive alternative to globin analysis has been investigated. Following identification of N-(2-hydroxyethyl)-l-valyl-l-leucine (HEVL) as ultimate cleavage product of EO-adducted globin excreted in the rat urine, here we report for the first time on the presence of HEVL in the urine of humans. In 18 sterilization workers, urinary HEVL ranged from 0.67 to 11.98 μg/g creatinine (mean ± SD: 5.04 ± 3.14 μg/g creat) and correlated with HEV: HEVL (μg/g creat) = 0.833 HEV (nmol/g globin) + 1.19 (R2 = 0.45). As unexpectedly high levels of urinary HEVL were found also in controls (mean ± SD: 0.97 ± 0.37 μg/g creat, n = 32), HEVL is not proposed for the accurate assessment of sub-ppm exposures to EO. On the other hand, non-invasive sampling and facile work-up procedure predetermine HEVL for screening purposes to identify subjects approaching to or exceeding occupational exposure limit for EO (1.8 mg/m3) to be re-examined by the more sensitive reference analysis for HEV.

• MeSH
• biologické markery moč   MeSH
• biologický monitoring metody   MeSH
• dospělí MeSH
• ethylenoxid moč   MeSH
• karcinogeny toxicita   MeSH
• lidé středního věku MeSH
• lidé MeSH
• pracovní expozice škodlivé účinky   MeSH
• valin moč   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Ethylene oxide (EO), an industrial intermediate and gaseous sterilant for medical devices, is carcinogenic to humans, which warrants minimization of exposure in the workplaces. The principal analytical strategy currently used in biomonitoring of exposure to EO consists in the conversion of N-(2-hydroxyethyl) adduct at the N-terminal valine (HEV) in globin to a specific thiohydantoin derivative accessible to GC-MS analysis (modified Edman degradation, MED). Though highly sensitive, the method is laborious and, at least in our hands, not sufficiently robust. Here we developed an alternative strategy of HEV determination based on acidic hydrolysis (AH) of globin followed directly by HPLC-ESI-MS2 analysis. Limit of quantitation is ca. 25 pmol HEV/g globin. Comparative analyses of globin samples from EO-exposed workers by both the AH-based and MED-based methods provided results that correlated well with each other (R2 > 0.95) but those obtained with AH were significantly more accurate (according to external quality control programme G-EQUAS) and repeatible (5% and 6% for intra-day and between-day analyses, respectively). In conclusion, the new AH-based method surpassed MED being similarly sensitive, much less laborious and more reliable, thus applicable as an effective tool for biomonitoring of EO in exposure control and risk assessment.

• MeSH
• bioindikátory MeSH
• ethylenoxid škodlivé účinky   krev   MeSH
• globiny analýza   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací * MeSH
• hodnocení rizik MeSH
• hydrolýza MeSH
• hygiena práce * MeSH
• inhalační expozice * škodlivé účinky   MeSH
• kyseliny chemie   MeSH
• lidé MeSH
• monitorování životního prostředí metody   MeSH
• pracovní expozice * škodlivé účinky   MeSH
• reprodukovatelnost výsledků MeSH
• valin analogy a deriváty   krev   MeSH
• vysokoúčinná kapalinová chromatografie * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Ethylene oxide (EO), a genotoxic industrial chemical and sterilant, forms covalent adducts with DNA and also with nucleophilic amino acids in proteins. The adduct with N-terminal valine in globin [N-(2-hydroxyethyl)valine (HEV)] has been used in biomonitoring of cumulative exposures to EO. Here we studied in rats the fate of EO-adducted N-termini of globin after life termination of the erythrocytes. Rat erythrocytes were incubated with EO to produce the HEV levels in globin at 0.4-13.2 µmol/g as determined after acidic hydrolysis. Alternative hydrolysis of the isolated globin with enzyme pronase afforded N-(2-hydroxyethyl)-L-valyl-L-leucine (HEVL) and N-(2-hydroxyethyl)-L-valyl-L-histidine (HEVH), the EO-adducted N-terminal dipeptides of rat globin α- and β-chains, respectively. The ratio of HEVL/HEVH (1:3) reflected higher reactivity of EO with the β-chain. The EO-modified erythrocytes were then given intravenously to the recipient rats. HEVL and HEVH were found to be the ultimate cleavage products excreted in the rat urine. Finally, rats were dosed intraperitoneally with EO, 50 mg/kg. Herein, the initial level of globin-bound HEVL (11.7 ± 1.3 nmol/g) decreased almost linearly over 60 days corresponding to the life span of rat erythrocytes. Daily urinary excretion of HEVL was almost constant for 30-40 days, decreasing faster in the subsequent phase of elimination. Recoveries of the total urinary HEVL from its globin-bound form were 84 ± 6% and 101 ± 17% after administrations of EO and the EO-modified erythrocytes, respectively. In conclusion, urinary HEVL appears to be a promising novel non-invasive biomarker of human exposures to EO.

• MeSH
• biologické markery moč   MeSH
• dipeptidy metabolismus   moč   MeSH
• erytrocyty MeSH
• ethylenoxid toxicita   MeSH
• globiny metabolismus   MeSH
• hydrolýza MeSH
• krysa rodu rattus MeSH
• leucin MeSH
• monitorování životního prostředí MeSH
• nebezpečné látky toxicita   MeSH
• valin chemie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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

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

BACKGROUND/AIMS: Reduction of renal blood flow (RBF) is commonly thought to be a causative factor of renal dysfunction in congestive heart failure (CHF), but the exact mechanism of the renal hypoperfusion is not clear. Apart from the activation of neurohormonal systems controlling intrarenal vascular tone, the cause might be altered reactivity of the renal vasculature to endogenous vasoactive agents. METHODS: To evaluate the role of this mechanism, we assessed by an ultrasonic transient-time flow probe maximum RBF responses to renal artery infusion of angiotensin II (ANG II), norepinephrine (NE) and acetylcholine (Ach) in healthy male rats and animals with compensated and decompensated CHF. CHF was induced by volume overload achieved by the creation of the aorto-caval fistula (ACF) in Hannover Sprague-Dawley rats. RESULTS: Maximum responses in RBF to ANG II were similar in rats studied five weeks (compensated phase) and 20 weeks (decompensated phase) after ACF creation when compared to sham-operated rats. On the other hand, NE elicited larger maximum decreases in RBF in rats with CHF (five and 20 weeks post-ACF) than in sham-operated controls. We observed greater maximum vasodilatory responses to Ach only in rats with a compensated stage of CHF (five weeks post-ACF). CONCLUSION: Greater renal vasoconstrictor responsiveness to ANG II or reduced renal vasodilatation in response to Ach do not play a decisive role in the development of renal dysfunction in ACF rats with compensated and decompensated CHF. On the other hand, exaggerated renal vascular responsiveness to NE may be here a contributing causative factor, active in either CHF phase.

• MeSH
• acetylcholin farmakologie   MeSH
• angiotensin II farmakologie   MeSH
• arteria renalis účinky léků   patofyziologie   MeSH
• krysa rodu rattus MeSH
• noradrenalin farmakologie   MeSH
• potkani Sprague-Dawley MeSH
• renální oběh fyziologie   MeSH
• srdeční selhání komplikace   MeSH
• vazodilatace účinky léků   MeSH
• vazokonstrikce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Treatment with pertussis toxin (PTX) which eliminates the activity of G(i) proteins effectively reduces blood pressure (BP) and vascular resistance in spontaneously hypertensive rats (SHR). In this study we have compared the functional characteristics of isolated arteries from SHR with and without PTX-treatment (10 microg/kg i.v., 48 h before the experiment). Rings of thoracic aorta, superior mesenteric artery and main pulmonary artery were studied under isometric conditions to measure the reactivity of these vessels to receptor agonists and to transmural electrical stimuli. We have found that the treatment of SHR with PTX had no effect on endothelium-dependent relaxation of thoracic aorta induced by acetylcholine. In PTX-treated SHR, the maximum contraction of mesenteric artery to exogenous noradrenaline was reduced and the dose-response curve to cumulative concentration of noradrenaline was shifted to the right. Similarly, a reduction in the magnitude of neurogenic contractions elicited by electrical stimulation of perivascular nerves was observed in the mesenteric artery from PTX-treated SHR. PTX treatment of SHR also abolished the potentiating effect of angiotensin II on neurogenic contractions of the main pulmonary artery. These results indicate that PTX treatment markedly diminishes the effectiveness of adrenergic stimuli in vasculature of SHR. This could importantly affect BP regulation in genetic hypertension.

• MeSH
• acetylcholin metabolismus   MeSH
• adrenergní látky metabolismus   MeSH
• angiotensin II metabolismus   MeSH
• aorta thoracica metabolismus   účinky léků   MeSH
• arteria mesenterica superior metabolismus   účinky léků   MeSH
• arteria pulmonalis metabolismus   účinky léků   MeSH
• arterie metabolismus   účinky léků   MeSH
• cévní endotel metabolismus   účinky léků   MeSH
• elektrická stimulace MeSH
• hypertenze farmakoterapie   metabolismus   MeSH
• inhibitory enzymů farmakologie   MeSH
• krevní tlak genetika   účinky záření   MeSH
• krysa rodu rattus MeSH
• noradrenalin metabolismus   MeSH
• pertusový toxin farmakologie   MeSH
• potkani inbrední SHR MeSH
• proteiny vázající GTP - alfa-podjednotky Gi-Go antagonisté a inhibitory   metabolismus   MeSH
• signální transdukce fyziologie   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

• MeSH
• Addisonova nemoc metabolismus   MeSH
• adrenokortikotropní hormon farmakologie   MeSH
• aldosteron metabolismus   MeSH
• angiotensin II farmakologie   MeSH
• dospělí MeSH
• kinetika MeSH
• krevní tlak účinky léků   MeSH
• lidé středního věku MeSH
• lidé MeSH
• theofylin analogy a deriváty   MeSH
• xanthinolniacinát farmakologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH

Recent studies have shown that the renal CYP450 (cytochrome P450) metabolites of AA (arachidonic acid), the vasoconstrictor 20-HETE (20-hydroxyeicosatetraenoic acid) and the vasodilator EETs (epoxyeicosatrienoic acids), play an important role in the pathophysiology of AngII (angiotensin II)-dependent forms of hypertension and the associated target organ damage. The present studies were performed in Ren-2 renin transgenic rats (TGR) to evaluate the effects of chronic selective inhibition of 20-HETE formation or elevation of the level of EETs, alone or in combination, on the course of hypertension and hypertension-associated end-organ damage. Both young (30 days of age) prehypertensive TGR and adult (190 days of age) TGR with established hypertension were examined. Normotensive HanSD (Hannover Sprague-Dawley) rats served as controls. The rats were treated with N-methylsulfonyl-12,12-dibromododec-11-enamide to inhibit 20-HETE formation and/or with N-cyclohexyl-N-dodecyl urea to inhibit soluble epoxide hydrolase and prevent degradation of EETs. Inhibition in TGR of 20-HETE formation combined with enhanced bioavailability of EETs attenuated the development of hypertension, cardiac hypertrophy, proteinuria, glomerular hypertrophy and sclerosis as well as renal tubulointerstitial injury. This was also associated with attenuation of the responsiveness of the systemic and renal vascular beds to AngII without modifying their responses to noradrenaline (norepinephrine). Our findings suggest that altered production and/or action of 20-HETE and EETs plays a permissive role in the development of hypertension and hypertension-associated end-organ damage in this model of AngII-dependent hypertension. This information provides a basis for a search for new therapeutic approaches for the treatment of hypertension.

• MeSH
• amidy farmakologie   terapeutické užití   MeSH
• angiotensin II farmakologie   MeSH
• antihypertenziva farmakologie   terapeutické užití   MeSH
• hypertenze komplikace   farmakoterapie   patofyziologie   MeSH
• krevní tlak účinky léků   MeSH
• krysa rodu rattus MeSH
• kyselina 8,11,14-eikosatrienová analogy a deriváty   metabolismus   MeSH
• kyseliny hydroxyeikosatetraenové biosyntéza   MeSH
• multiorgánové selhání etiologie   prevence a kontrola   MeSH
• noradrenalin farmakologie   MeSH
• potkani Sprague-Dawley MeSH
• potkani transgenní MeSH
• preklinické hodnocení léčiv metody   MeSH
• renální oběh účinky léků   MeSH
• sulfony farmakologie   terapeutické užití   MeSH
• vazokonstriktory farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH