Comparison of xenobiotic metabolism in phase I oxidation and phase II conjugation between rats and bird species.

There have been many reports regarding toxic chemicals in birds. Chemicals are mainly metabolized in the liver through phase I oxidation by cytochrome P450 (CYP) and phase II conjugation by conjugated enzymes, such as UDP-glucuronosyltransferase (UGT), sulfotransferase (SULT), glutathione-S-transferase (GST), etc. Xenobiotic metabolism differs among bird species, but little detailed information is available. In the present study, the four-ring polycyclic aromatic hydrocarbon (PAH), pyrene, was used as a model xenobiotic to clarify the characteristics of xenobiotic metabolism in birds compared with laboratory animals by in vivo and in vitro studies. Plasma, bile, and excreta (urine and feces) were collected after oral administration of pyrene and analyzed to clarify xenobiotic metabolism ability in chickens and quails. Interestingly, pyrenediol-glucuronide sulfate (PYDOGS) and pyrenediol-diglucuronide (PYDOGG) were present in chickens and quails but not in rats. In addition, the area under the curve (AUC), maximum plasma concentration (Cmax), and time to maximum plasma concentration (Tmax) of pyrene-1-sulfate (PYOS) were higher than those of the parent molecule, pyrene, while the elimination half-life (t1/2) and mean residence time (MRT) were faster than those of the parent pyrene. With regard to sulfation of 1-hydroxypyrene (PYOH), the maximum velocity (Vmax) and Michaelis constant (Km) of rat liver cytosol were greater than those of chicken and quail liver cytosol. Furthermore, Vmax/Km of UGT activity in rat liver microsomes was also greater than those of chicken and quail liver microsomes. Characterization of xenobiotic metabolism revealed species differences between birds and mammals, raising concerns about exposure to various xenobiotics in the environment.

Concentrations of Environmental Chemicals in Urine and Blood Samples of Children from San Luis Potosí, Mexico.

Human biomonitoring (HBM) is an appreciated tool used to evaluate human exposure to environmental, occupational or lifestyle chemicals. Therefore, the aim of this study was to evaluate the exposure levels for environmental chemicals in urine and blood samples of children from San Luis Potosí, Mexico (SLP). This study identifies environmental chemicals of concern such as: arsenic (45.0 ± 15.0 µg/g creatinine), lead (5.40 ± 2.80 µg/dL), t,t-muconic acid (266 ± 220 µg/g creatinine), 1-hydroxypyrene (0.25 ± 0.15 µmol/mol creatinine), PBDEs (28.0 ± 15.0 ng/g lipid), and PCBs (33.0 ± 16.0 ng/g lipid). On the other hand, low mercury (1.25 ± 1.00 µg/L), hippuric acid (0.38 ± 0.15 µg/g creatinine) and total DDT (130 ± 35 ng/g lipid) exposure levels were found. This preliminary study showed the tool's utility, as the general findings revealed chemicals of concern. Moreover, this screening exhibited the need for HBM in the general population of SLP.

Reduced Exposure to Harmful and Potentially Harmful Smoke Constituents With the Tobacco Heating System 2.1.

INTRODUCTION: Heating rather than burning tobacco reduces levels of harmful and potentially harmful constituents, and consumer products using this approach aim to reduce exposure to tobacco toxicants. The Tobacco Heating System (THS) version 2.1 has been enhanced from earlier prototypes with an improved heat control and sensorial experience and thereby user acceptance. Exposure measurements are required to determine whether it may be possible to reduce the individual health risk compared to smoking combustible cigarettes (CCs). METHODS: This controlled clinical study randomly assigned 40 smokers to either a group continuing to use of their own CC brand (n = 20) or a group switching to THS 2.1 (n = 20) for 5 days. Biomarkers of exposure were measured at baseline and on day 1 through day 5. Product consumption, Human Puffing Topography, the occurrence of adverse events, and an assessment of subjective effects, such as smoking satisfaction and enjoyment of respiratory tract sensations, were also determined. RESULTS: The group of smokers who switched to THS 2.1 adapted their puffing behavior initially through longer puff duration and more puffs. During the duration of the study, total puff volume returned to baseline levels and the mean daily product consumption increased but with similar nicotine exposure compared to baseline CC use. Biomarkers of exposure to tobacco smoke toxicants which inform product risk assessment were significantly reduced with THS use compared to the CC group. THS 2.1 users experienced less reinforcing effects with THS 2.1 than with their own cigarette brand. CONCLUSIONS: THS 2.1 is a promising alternative to smoking CCs. Notwithstanding possible use adaption through consumption or puffing behavior, the exposure to harmful smoke constituents was markedly reduced with the new heated tobacco platform. IMPLICATIONS: Exposure markers to harmful and potentially harmful smoke constituents were lowered with the THS 2.1. Heating tobacco instead of burning can offer a potentially lower risk of delivering nicotine compared to CCs.

Molecular detection and extraction of pyrene in plasma and tissues of Sprague-Dawley rats.

In this paper, an efficient method for determination of total pyrene concentration in the biological samples including plasma, liver, spleen, lung and kidney of Sprague-Dawley rats were investigated and established using steady-state fluorescence method. Equilibrium dialysis method was applied to determine plasma protein binding rate of pyrene. The results illustrated that the protein binding rate depends on the concentration of pyrene in plasma. Extraction of pyrene in plasma was studied by using biomedical nanopartical which was prepared from synthesized associating polymer poly(ethylene glycol) end-capped by hexadecane. The Critical Micelle Concentration (CMC) of the polymeric micelle in aqueous solution was determined to equal 0.0063 mg/mL using 1-pyrenemethanol as a fluorescent probe. The distribution of free pyrene and pyrene loaded nanoparticals in blood were determined. The results showed that over 95% of the free pyrene was distributed into the erythrocyte, and the pyrene-loaded nanoparticles were less distributed in to the erythrocyte than free pyrene, but it was higher than 60%. This study provides an efficient method to detect pyrene in different tissues as well as an extraction method at the molecular level, which might contribute to the development of modern molecular diagnosis and identification in vivo.

Rapid assessment of singlet oxygen-induced plasma lipid oxidation and its inhibition by antioxidants with diphenyl-1-pyrenylphosphine (DPPP).

Recent studies suggesting the involvement of singlet oxygen in the pathogenesis of multiple diseases have attracted renewed attention to lipid oxidation mediated by singlet oxygen. Although the rate constants for singlet oxygen quenching by antioxidants have been measured extensively, the inhibition of lipid oxidation mediated by singlet oxygen has received relatively less attention, partly because a convenient method for measuring the rate of lipid oxidation is not available. The objective of this study was to develop a convenient method to measure plasma lipid oxidation mediated by singlet oxygen which may be applied to a rapid assessment of the antioxidant capacity to inhibit this oxidation using a conventional microplate reader. Singlet oxygen was produced from naphthalene endoperoxide, and lipid hydroperoxide production was followed by using diphenyl-1-pyrenylphosphine (DPPP). Non-fluorescent DPPP reacts stoichiometrically with lipid hydroperoxides to give highly fluorescent DPPP oxide. It was found that plasma oxidation by singlet oxygen increased the fluorescence intensity of DPPP oxide, which was suppressed by antioxidants. Fucoxanthin suppressed the oxidation more efficiently than ß-carotene and α-tocopherol, while ascorbic acid and Trolox were not effective. The present method may be useful for monitoring lipid oxidation and also for rapid screening of the capacity of dietary antioxidants and natural products to inhibit lipid oxidation in a biologically relevant system.

Tentative reference values for environmental pollutants in blood or urine from the children of Kinshasa.

The DRC, as most of African nations, does not have a national biomonitoring programme and there is a lack of information on background levels of environmental pollutants in the general DRC population, particularly in children. The focus of the data presented in this report aims to establish the background levels of a range of environmental pollutants in urine or blood from the children population of Kinshasa. Based on the representative data collection of the Kinshasa population, the survey selected 125 children aged 1-14years and living in Kinshasa (6years on average, 56% of girls, 100% of non-smokers, without amalgam fillings and consumers of fish 3 times per week). Biomarkers of a range of metals (As, Cd, Hg and Pb), pyrene (PAH) and benzene were analyzed in the blood or urine samples. Globally, the results indicate that the exposure levels of children living in Kinshasa are 10 times higher than those published by the American, Canadian and German children surveys. This study provides the first Reference Values of environmental pollutants [As, Cd, Hg, Pb, pyrene (PAH) and benzene] in the Kinshasa children population and reveals elevated levels of all biomarkers studied. The data set of this study may allow environmental and health authorities of DRC to undertake a national biomonitoring programme, especially with four insights for the protection of human heath.

Characterization and tissue distribution of conjugated metabolites of pyrene in the rat.

Pyrene (PY) is a polycyclic aromatic hydrocarbon (PAH) that is often used as a biomarker for human and wildlife exposure to PAHs. As the metabolites of PAHs, similar to their parent compounds, pose public health risks, it is necessary to study their characteristics and tissue-specific distribution. The present study was performed to experimentally characterize PY metabolites and analyze the tissue-specific distribution of the conjugated metabolites after oral administration of PY to rats. PY metabolites, such as pyrenediol-disulfate (PYdiol-diS), pyrenediol-sulfate (PYdiol-S), pyrene-1-sulfate (PYOS), pyrene-1-glucuronide (PYOG) and 1-hydroxypyrene (PYOH), were detected in rat urine. Although glucuronide conjugate was the predominant metabolite, the metabolite composition varied among tissues. Interestingly, the proportion of PYOH was high in the large intestine. Furthermore, PYOH was the only PY metabolite detected in feces.

Lymphocyte oxidative stress/genotoxic effects are related to serum IgG and IgA levels in coke oven workers.

We investigated oxidative stress/genotoxic effects levels, immunoglobulin levels, polycyclic aromatic hydrocarbons (PAHs) levels exposed in 126 coke oven workers and in 78 control subjects, and evaluated the association between oxidative stress/genotoxic effects levels and immunoglobulin levels. Significant differences were observed in biomarkers, including 1-hydroxypyrene levels, employment time, percentages of alcohol drinkers, MDA, 8-OHdG levels, CTL levels and CTM, MN, CA frequency, and IgG, IgA levels between the control and exposed groups. Slightly higher 1-OHP levels in smoking users were observed. For the dose-response relationship of IgG, IgA, IgM, and IgE by 1-OHP, each one percentage increase in urinary 1-OHP generates a 0.109%, 0.472%, 0.051%, and 0.067% decrease in control group and generates a 0.312%, 0.538%, 0.062%, and 0.071% decrease in exposed group, respectively. Except for age, alcohol and smoking status, IgM, and IgE, a significant correlation in urinary 1-OHP and other biomarkers in the total population was observed. Additionally, a significant negative correlation in genotoxic/oxidative damage biomarkers of MDA, 8-OH-dG, CTL levels, and immunoglobins of IgG and IgA levels, especially in coke oven workers, was found. These data suggest that oxidative stress/DNA damage induced by PAHs may play a role in toxic responses for PAHs in immunological functions.

PAH exposure biomarkers are associated with clinico-chemical changes in the brick kiln workers in Pakistan.

In this study we investigated the clinico-chemical parameters and the level of exposure of brick kiln workers to polycyclic aromatic hydrocarbons (PAHs) in Punjab (Pakistan). The brick kiln workers and a non-occupationally exposed group were recruited for comparative analysis of urinary biomarkers of PAH exposure (i.e. 1-hydroxypyrene (1-OHPyr), α-naphthol and ß-naphthol) and blood level of superoxide dismutase (SOD), as a biomarker of oxidative stress and other hematologic parameters. Questionnaires were used to document information on socio-demographic characteristics of all the subjects. The analysis of urinary biomarkers showed higher median concentrations of 1-OHPyr, and α- and ß-naphthols in brick kiln workers (1.53, 3.65 and 1.53 µmol/mol-Cr, respectively) than non-occupationally exposed group (0.62, 0.64 and 0.66 µmol/mol-Cr, respectively). The 1-OHPyr in brick kiln workers was above the occupational exposure level. Among the clinical parameters of brick kiln workers, hemoglobin (Hb) and red blood cells (RBCs) were very low and closely associate with 1-OHPyr and ß-naphthol. Additionally, the white blood cells (WBCs) and superoxide dismutase (SOD) were also elevated in brick kiln workers, which suggested inflammatory symptoms and high oxidative stress. The results show that regardless of possibly being affected by the poor nutrition, the anemic state and hematological changes observed in brick kiln workers may be associated with their exposure to smoke present in the environment of brick kilns.

The carcinogen 1-methylpyrene forms benzylic DNA adducts in mouse and rat tissues in vivo via a reactive sulphuric acid ester.

The common polycyclic aromatic hydrocarbon 1-methylpyrene is hepatocarcinogenic in the newborn mouse assay. In vitro studies showed that it is metabolically activated via benzylic hydroxylation and sulphation to a reactive ester, which forms benzylic DNA adducts, N(2)-(1-methylpyrenyl)-2'-deoxyguanosine (MPdG) and N(6)-(1-methylpyrenyl)-2'-deoxyadenosine (MPdA). Formation of these adducts was also observed in animals treated with the metabolites, 1-hydroxymethylpyrene and 1-sulphooxymethylpyrene (1-SMP), whereas corresponding data are missing for 1-methylpyrene. In the present study, we treated mice with 1-methylpyrene and subsequently analysed blood serum for the presence of the reactive metabolite 1-SMP and tissue DNA for the presence of MPdG and MPdA adducts. We used wild-type mice and a mouse line transgenic for human sulphotransferases (SULT) 1A1 and 1A2, males and females. All analyses were conducted using ultra-performance liquid chromatography coupled with tandem mass spectrometry, for the adducts with isotope-labelled internal standards. 1-SMP was detected in all treated animals. Its serum level was higher in transgenic mice than in the wild-type (p < 0.001). Likewise, both adducts were detected in liver, kidney and lung DNA of all exposed animals. The transgene significantly enhanced the level of each adduct in each tissue of both sexes (p < 0.01-0.001). Adduct levels were highest in the liver, the target tissue of carcinogenesis, in each animal model used. MPdG and MPdA adducts were also observed in rats treated with 1-methylpyrene. Our findings corroborate the hypothesis that 1-SMP is indeed the ultimate carcinogen of 1-methylpyrene and that human SULT are able to mediate the terminal activation in vivo.

Lipid imbalance in individuals predisposed to rheumatoid arthritis: possible relationship with common infections.

Lipid balance was studied in female patients with late rheumatoid arthritis, their healthy female relatives liable to autoimmune diseases, and healthy women without family history of autoimmune diseases. Previous studies showed that the relatives of patients with rheumatoid arthritis suffered from frequent stubborn common infections, which prompted us to analyze the relationship between lipid metabolism and the infectious syndrome parameters. Blood serum and cells were collected for analysis when females had no clinical symptoms of infections (in all groups) or laboratory signs of inflammatory process (in the relatives and controls). Proatherogenic shifts in serum lipid composition presumably associated with frequent lasting infections were detected in individuals liable to rheumatoid arthritis development. Elevated cholesterol content in mononuclear leukocytes in this group could lead, in turn, to dysfunctions of these cells and augment the defects of anti-infection defense. The parameters of lipid balance in patients with late rheumatoid arthritis were close to the age-specific norm.

DDT, DDE, and 1-hydroxypyrene levels in children (in blood and urine samples) from Chiapas and Oaxaca, Mexico.

The aim of this study was to evaluate the DDT, DDE, and 1-hydroxypyrene exposure levels of children living in communities located in southeastern Mexico. The study communities were Lacanja and Victoria in Chiapas state and Ventanilla in Oaxaca state. Children living in Lacanja had total blood DDT levels (mean ± SD, 29,039.6 ± 11,261.4 ng/g lipid) that were significantly higher than those of children in Victoria (10,220.5 ± 7,893.1 ng/g lipid) and Ventanilla (11,659.7 ± 6,683.7 ng/g lipid). With respect to the 1-hydroxypyrene levels in urine samples, the levels in Lacanja (4.8 ± 4.1 µg/L or 4.5 ± 3.9 µmol/mol creatinine) and Victoria (4.6 ± 3.8 µg/L or 3.9 ± 3.0 µmol/mol Cr) were significantly higher than levels found in Ventanilla (3.6 ± 1.4 µg/L or 2.5 ± 0.5 µmol/mol Cr). In conclusion, our data indicate high levels of exposure in children living in the communities studied in this work. The evidence found in this study could be further used as a trigger to revisit local policies on environmental exposures.

Exposure to chemical mixtures in Mexican children: high-risk scenarios.

In developing countries, the management of environmental toxicants is inadequate, thus, humans may be exposed to levels higher than normal levels (background levels). Therefore, the aim of this study was to evaluate the exposure level of Mexican children to dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), lead, and polycyclic aromatic hydrocarbons [using 1-hydroxypyrene (1-OHP) as exposure biomarker] and to assess the percentage of children exposed to these four compounds at concentrations higher than normal in each community studied. We performed random sampling in eight communities in Mexico (five communities in Chiapas State and three communities in San Luis Potosi State). DDT and DDE were analyzed by gas chromatography/mass spectrometry, the quantification of lead in blood was performed using atomic absorption spectrophotometry, and 1-OHP analyses were performed using HPLC with a fluorescence detector. Elevated DDT, DDE, and 1-OHP levels were found in children living in the indigenous communities of Chiapas State, while higher blood lead levels were found in two communities in San Luis Potosí. Approximately 30 % of children living in Chiapas were exposed to all four compounds at concentrations above the guidelines for each compound, whereas 48 % of children studied were exposed to all four contaminants at concentrations higher than normal in a community in San Luis Potosí State. As expected, our results showed that in hot spots, children are exposed to levels higher than normal. Therefore, child environmental health programs are urgently needed.

Monitoring volume changes in red cell ghosts by means of a trapped fluorescent probe.

A method is described for monitoring changes in the volume of red cell ghosts by means of a fluorescent probe trapped inside them.. The fluorophore, 8-hydroxy-1,3,6-pyrenetrisulfonate, is partially quenched by the residual hemoglobin in the ghosts. When the ghosts swell, the hemoglobin concentration is reduced, the quenching is somewhat relieved and the fluorescence output increases. Opposite changes occur when the ghosts shrink. Fluorescence intensity is linearly related to ghost volume for both swelling and shrinking, but there is a larger change in fluorescence for shrinking from the isotonic volume than for an equivalent swelling. This method has been used to follow the swelling phase of dye-loaded ghosts suspended in a solution of a penetrating nonelectrolyte in isotonic saline.

Distribution of shape-changing compounds across the red cell membrane.

The effects of two oppositely charged pyrene derivatives, 1-pyrenebutyrylcholine (PBC) and 1-pyrenebutyric acid (PBA), on red blood cell shape have been examined. Both compounds convert normal biconcave erythrocytes into echinocytes. However, with extended incubation time at elevated temperature, the morphology of PBC-induced echinocytes is reversed. Examination of probe uptake confirmed that, in contrast to PBA, equilibration of PBC with intact cells occurs very slowly. For PBA-induced echinocytes, it was possible to quantitate the fraction of probe bound in each half of the bilayer from nanosecond fluorescence measurements. Analysis of the heterogeneous decay showed that 71% of the bound PBA was associated with a lifetime (tau) of 102 ns and 29% with tau = 8 ns. It is likely that the later, highly quenched, component corresponds to fluorophores bound at the cytoplasmic surface because of efficient energy transfer to hemoglobin and that the long component corresponds to probe bound exclusively at the outer surface. Evidence in support of this interpretation was obtained by showing that when the paramagnetic cation Mn2+ bound at the extracellular surface the 102-ns component is quenched. The excimer fluorescence of PBC bound to red cells was examined and found to show time and temperature dependencies which correlate with morphological effects. These results indicate that red cells become crenated with PBC molecules are highly concentrated in the outer bilayer half and that shape reversal is subsequently brought about as PBC permeates and accumulates in the inner bilayer half. Finally, hemolysis protection due to PBC or PBA binding was observed also to show striking correlations with cell shape, In summary, these findings support the hypothesis [Sheetz, M. P., & Singer, S. J. (1974) Proc. Natl. Acad. Sci. U.S.A. 71, 4457] that shape changes are induced in red cells by amphiphilic molecules as a consequence of their relative partitioning between the two halves of the bilayer.