Effects of genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 on urinary 1-hydroxypyrene levels in sugarcane workers

Sugarcane workers in Brazil are exposed to various genotoxic compounds, including polycyclic aromatic hydrocarbons (PAHs), derived from an incomplete combustion process of burnt sugarcane fields. The effects of the occupational exposure to sugarcane fields burning were measured in urine samples of sugarcane workers from the northwest of the State of S?o Paulo when exposed (harvesting) and when non-exposed (non-harvesting). The urinary levels of 1-hydroxypyrene (1-OHP) and the influence of the genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 were evaluated. Our results showed that the 1-OHP levels were significantly higher (P<0.0000) in the exposed sugarcane workers (0.318 mumol mol(-1) creatinine) than in the non-exposed workers (0.035 mumol mol(-1) creatinine). In an unvaried analysis, no influence regarding the polymorphisms was observed. However, multivariate regression analysis showed that the CYP1A1()4 polymorphism in the exposed group, and age and the GSTP1 polymorphism in the non-exposed group significantly influenced urinary 1-OHP excretion levels (P<0.10). The same group of sugarcane workers was significantly more exposed to PAHs during the harvesting period than during the non-harvesting period.     

Elevated concentrations of 1-hydroxypyrene in schoolchildren during winter in Christchurch, New Zealand

Particulate air pollution is significantly elevated during the winter in Christchurch, New Zealand, largely attributable to use of wood burners for domestic home heating, topography, and meteorological conditions. Polycyclic aromatic hydrocarbons (PAHs) are a key component of airborne particulate matter (PM) and urinary 1-hydroxypyrene (1-OHP) has previously been used to assess exposure of people to PAHs. We examined urinary 1-OHP in Christchurch male non-smoking schoolchildren (12-18 yr) on two occasions after high pollution events (48 and 72 microg PM(10)/m(3) 24-h average) and two occasions during periods of low pollution (19 and 12 microg PM(10)/m(3)). Concentrations of urinary 1-OHP were significantly elevated in the students during high pollution events (median (mean+/-SD) 0.043 (0.051+/-0.032) and 0.042 (0.060+/-0.092) micromol OHP/mol creatinine respectively) compared with low pollution periods (median (mean+/-SD) 0.019 (0.026+/-0.032) and 0.025 (0.028+/-0.018) micromol/mol creatinine respectively). The observed 1-OHP concentrations are at the lower end of those determined in children and non-occupationally exposed adults in international studies and suggest a generally low exposure to PAHs. The increased urinary 1-OHP concentrations following nights of elevated particulate concentrations in ambient air suggest increased exposure to ambient air pollution during winter time, and could potentially be used as a biomarker of exposure in this population.     

Urinary 1-hydroxypyrene, air pollution exposure and associated life style factors in pregnant women

1-hydroxypyrene (1-OHP) is a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs). PAHs are pollutants produced by the combustion of organic material, and could be found both indoors and outdoors. Prenatal exposure to these compounds has been associated with retarded intrauterine growth and respiratory problems in children. The objective of this study is to describe the 1-OHP levels in urine in pregnant women in the INMA cohort in Valencia, and to study the association with socio-demographic and lifestyle variables, as well as with indicators of air pollution. The study population is a sub-sample (n: 204) of a cohort of pregnant women in the multicentre INMA project in Valencia (Spain). Urine samples were taken in week 12 of gestation, and 1-OHP was analyzed, and adjusted for creatinine. Socio-demographic and lifestyle information was collected using a questionnaire. Data from the monitoring stations in Valencia were used to assign levels of exposure to nitrogen dioxide (NO2), sulphur dioxide (SO2), total suspended particulates (TSP) and carbon monoxide (CO). The median 1-OHP level was 0.061 muicrool/mol of creatinine. Women who smoked had higher 1-OHP levels (0.095 micromol/mol of creatinine) than non-smokers (0.050 micromol/mol of creatinine). The variables predicting 1-OHP levels on linear multivariate analysis were: tobacco consumption, consumption of fried and smoked foods. There was also a significant association with NO2 levels 4 and 5 days before the samples were taken. The 1-OHP levels found in pregnant women in Valencia were higher than those found among women in reports in USA. 1-hydroxypyrene could be a good marker of exposure to PAHs from tobacco and diet, and also a useful marker of short term exposure to air pollution.     

PAH exposure in a Ghanaian population at high risk for aflatoxicosis

It was postulated that a population in sub-Saharan Africa, known to be at high risk for aflatoxicosis due to frequent ingestion of aflatoxin (AF)-contaminated foods could also be exposed to polycyclic aromatic hydrocarbons (PAHs) from a variety of environmental sources. Previously, participants in this population were shown to be highly exposed to AFs, and this exposure was significantly reduced by intervention with NovaSil clay (NS). Objectives of this study were 1) to assess PAH exposure in participants from the AF study using urinary biomarker 1-hydroxypyrene (1-OHP); 2) examine the effect of NS clay and placebo (cellulose) treatment on 1-OHP levels; and 3) determine potential association(s) between AF and PAH exposures. A clinical trial was conducted in 177 Ghanaians who received either NS capsules as high dose or low dose, or placebo (cellulose) for a period of 3 months. At the start and end of the study, urine samples were analyzed for 1-OHP. Of the 279 total samples, 98.9% had detectable levels of 1-OHP. Median 1-OHP excretion in nonsmokers was 0.64 µmol/mol creatinine at baseline and 0.69 µmol/mol creatinine after 3 months. Samples collected at both time points did not show significant differences between placebo and NS-treated groups. There was no linear correlation between 1-OHP and AF-albumin adduct levels. Results show that this population is highly exposed to PAHs (and AFs), that NS and cellulose treatment had no statistically significant effect on 1-OHP levels, and that this urinary biomarker was not linearly related with AF exposure.     

Improved HPLC method for analysis of 1-hydroxypyrene in human urine specimens of cigarette smokers

A method for the rapid and sensitive analysis of 1-hydroxypyrene in human urine was improved by high performance liquid chromatography (HPLC) with fluorescence detection. The limit of detection decreased approximately threefold when triethylamine was added to the extracts prior to the chromatographic determination. The sensitivity was increased mainly due to triethylamine blockage of the secondary-retention effects. The analysis time was approximately 20 min per run. This method was applied to the analysis of 1-hydroxypyrene in 125 urine specimens collected from cigarette smokers who had non-occupational exposure to polycyclic aromatic hydrocarbons. The average concentrations of urinary 1-hydroxypyrene were 0.04 micromol/mol creatinine in non-smokers, 0.20 micromol/mol creatinine in light smokers, 0.46 micromol/mol creatinine in medium smokers, and 1.16 micromol/mol creatinine in heavy cigarette smokers. The levels of urinary 1-hydroxypyrene correlated strongly with cigarette intake (r2 = 0.93, P < 0.001).     

Urinary 1-hydroxypyrene and PAH exposure in 4-year-old Spanish children

Aims:

Exposure to polycyclic aromatic hydrocarbons (PAH), among the main compounds present in polluted urban air, is of concern for children's health. Childhood exposure to PAH was assessed by urinary monitoring of 1-hydroxypyrene (1-OHP), a pyrene metabolite, investigating its association with exposure to air pollution and other factors related to PAH in air.

Methods:

A group of 174 4-year-old children were recruited and a questionnaire on their indoor and outdoor residential environment was completed by parents. At the same time, environmental measurements of traffic-related air pollution (NO₂) were carried out. A urine sample was collected from each child in order to analyze 1-OHP using HPLC with fluorescence detection, correcting for creatinine concentrations. Non-parametric tests and regression analyses were used to identify environmental factors that influence 1-OHP excretion.

Results:

Mean urinary 1-OHP concentration was 0.061 μmol/mol creatinine, ranging from 0.004 to 0.314 μmol/mol. Non-parametric tests and regression analysis showed positive and significant associations (P ≤ 0.05) between 1-OHP and predicted residential exposure to NO₂ (which was based on outdoor environmental measurements and geo-statistical analysis), self-reported residential vehicle traffic, passive smoking and cooking appliance. 1-OHP levels tended to be higher among children living in urban areas (0.062 μmol/mol vs. 0.058 μmol/mol for children living in rural areas) but differences were not significant (P = 0.20).

Conclusion:

In Southern Spain, concentrations of urinary 1-OHP were in the lower range of those generally reported for children living in non-polluted areas in Western Europe and the USA. Traffic-related air pollution, passive smoking and cooking appliance influenced urinary 1-OHP level in the children, which should be prevented due to the health consequences of the inadvertent exposure to PAH during development.     

Indoor air pollution in a Mexican indigenous community: evaluation of risk reduction program using biomarkers of exposure and effect

Indoor air pollution can be an important risk factor for human health, considering that people spend more than 60% of their time indoors. Fifty percent of the world population and approximately 90% of the rural population in developing countries are using biomass as energy source. Latin America represents 12% of the global consumption of biomass; in Mexico, 27 million people use wood as an energy source. Therefore, in this study we evaluated a 3-stage risk reduction program. The stages were: 1) removal of indoor soot adhered to roofs and internal walls; 2) paving the dirt floors; and 3) introduction of a new wood stove with a metal chimney that expels smoke outdoors. The complete intervention program was applied. In 20 healthy subject residents from an indigenous community in San Luis Potosí, Mexico, we measured blood carboxyhemoglobin (% COHb), DNA damage (comet assay) in nucleated blood cells, and urinary 1-OHP levels before and after the program. Before intervention individuals had a geometric mean COHb level of 4.93% and 53% of the population presented levels above 2.5% considered a safe level. However, in all the studied individuals the levels of COHb were reduced to below 2.5% (mean level 1.0%) one month after the intervention. Moreover, when compared, DNA damage in people exposed before the intervention was higher (5.8+/-1.3 of Tail Moment) than when the program was introduced (2.8+/-0.9 of Tail Moment) (P>0.05) and a same trend was observed with urinary 1-OHP levels; 6.71+/-3.58 micromol/mol creatinine was the concentration before intervention; whereas, 4.80+/-3.29 micromol/mol creatinine was the one after the program. The results suggest that the intervention program offers an acceptable risk reduction to those families that use biomass for food cooking.     

Cytochrome P450 1B1 mRNA levels in peripheral blood cells and exposure to polycyclic aromatic hydrocarbons in Chinese coke oven workers

Cytochrome P450 1B1 (CYP1B1) is induced through the Ah receptor and is involved in the activation of polycyclic aromatic hydrocarbons (PAHs). To determine the validity of a quantitative analysis of CYP1B1 mRNA in peripheral human blood cells for the estimation of PAH exposure, a real-time quantitative polymerase chain reaction method was used to measure the relative levels of CYP1B1 mRNA in 37 Chinese coke oven workers and 13 control workers. A large inter-individual difference in the levels was observed. The average level of the CYP1B1 mRNA in workers at the top work site, where the PAH exposure level from the coke ovens was highest, was significantly higher than in workers at the middle site (P<0.01) or the controls (P=0.02). A non-significant positive correlation was found between the CYP1B1 mRNA levels and urinary 1-hydroxypyrene (R=0.22, P=0.13), and a significant correlation between these mRNA levels and urinary cotinine (R=0.33, P=0.02). It was interesting that a significant positive correlation between CYP1B1 mRNA and 1-hydroxypyrene was observed in subjects with the Leu/Leu type of CYP1B1 Leu432Val polymorphism (R=0.33, P=0.02, n=38) and a non-significant correlation in subjects with the Leu/Val and Val/Val types (R=-0.36, P=0.25, n=12), although the number of subjects in this strata analysis was small. Our preliminary study suggests that PAH exposure in coke ovens and smoking maybe associated with CYP1B1 mRNA levels in peripheral blood cells although mRNA is generally unstable and could be expressed following exposure to other agents.     

Exposure to indoor air pollutants (polycyclic aromatic hydrocarbons, toluene, benzene) in Mexican indigenous women

Indoor air pollution is considered to be a serious public health issue in Mexico; therefore, more studies regarding this topic are necessary. In this context, we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds in: (i) women who use firewood combustion (indoor) for cooking and heating using traditional open fire; (ii) women who use firewood combustion (outdoor) for cooking and heating using traditional open fire; and (iii) women who use LP gas as the principal energy source. We studied 96 healthy women in San Luis Potosi, México. Urine samples were collected, and analyses of the following urinary exposure biomarkers were performed by high-performance liquid chromatography: 1-hydroxypyrene (1-OHP), trans, trans-muconic acid, and hippuric acid (HA). The highest levels of 1-OHP, trans, trans-muconic acid, and HA were found in communities where women were exposed to indoor biomass combustion smoke (or products; geometric mean ± s.d., 3.98 ± 5.10 μmol/mol creatinine; 4.81 ± 9.60 μg/l 1-OHP; 0.87 ± 1.78 mg/g creatinine for trans, trans-muconic acid; and 1.14 ± 0.91 g/g creatinine for HA). Our findings indicate higher exposure levels to all urinary exposure biomarkers studied in women who use indoor firewood combustion for cooking and heating (using traditional open fire). PRACTICAL IMPLICATIONS: High mean levels of 1-hydroxypyrene, t,t-muconic acid, and hippuric acid were found in women who use firewood combustion (indoor) for cooking and heating using traditional open fire and taking into account that millions of women and children in Mexico are living in scenarios similar to those studied in this report, the assessment of health effects in women and children exposed to polycyclic aromatic hydrocarbons and volatile organic compounds is urgently needed. Moreover, it is immediately necessary an intervention program to reduce exposure.     

The exposure of temple workers to polycyclic aromatic hydrocarbons

Five temples, each a different size, were selected for this study. Two of the temples were located in Taichung City (in central Taiwan), and three were in Tainan City (in Southern Taiwan). Aerosols smaller than 10 microm aerodynamic diameter (PM(10)) were collected by using personal collection samplers during pilgrim days (the first and fifteenth day of each lunar month) and normal days (all other days). Regression analysis showed that about 1.6 microg/m(3) of PM(10) contributed to the workers' exposure in the temples for each joss stick increase in the censer. The concentrations of total polycyclic aromatic hydrocarbons (t-PAHs) and carcinogenic PAHs (car-PAHs) on pilgrim days were higher than those on normal days. Mean concentrations of urinary 1-hydroxypyrene (1-OHP) in the pre-shift and post-shift workers of the five temples on normal days were 1.20 and 1.61 microg/g creatinine, respectively. Furthermore, the post-shift concentrations of 1-OHP in the workers of temples on pilgrim days were all higher than those of the workers of corresponding temples on normal days. Significant relationships between the urinary concentrations of 1-OHP and the exposure concentrations of pyrene, total PAHs and BaP(eq) were found in the workers of the temples. Results of linear regression showed that the increase of unit concentration (1 ng/m(3)) of pyrene led to a 0.05 microg/g creatinine increase of urinary 1-OHP, while the increase of unit concentration (1 ng/m(3)) of BaP(eq) resulted in an increase of 0.03 microg/g creatinine of urinary 1-OHP.     

Aflatoxin and PAH exposure biomarkers in a U.S. population with a high incidence of hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is significantly elevated in a Hispanic community in Bexar County, Texas. Chronic exposure to dietary aflatoxins (AFs) is a major risk factor for HCC; increased risk has been linked to polycyclic aromatic hydrocarbon (PAH) co-exposure and hepatitis virus infection. The aims of this study were to assess AF and PAH exposures, investigate dietary factors that may contribute to increased AF exposure, and determine the prevalence of hepatitis virus infection in Bexar Co. Blood and urine samples were collected from 184 volunteers for biomarker analyses and hepatitis screening. Serum AFB₁-lysine adduct, urinary AFM₁ and 1-hydroxypyrene (1-OHP) levels were measured using high-performance liquid chromatography. The average AFB₁-lysine adduct level detected in 20.6% of serums was 3.84 ± 3.11 pg/mg albumin (range 1.01-16.57 pg/mg). AFM₁ was detected in 11.7% of urines, averaging 223.85 ± 250.56 pg/mg creatinine (range 1.89-935.49 pg/mg). AFM₁ detection was associated with increased consumption of corn tortillas (p = 0.009), nuts (p = 0.033) and rice (p = 0.037). A significant difference was observed between mean 1-OHP values of non-smokers (0.07 ± 0.13) and smokers (0.80 ± 0.68) μmol/mol creatinine (p < 0.01). A high hepatitis C virus positivity rate (7.1%) was observed. Findings suggest that the incidence and level of AF and PAH exposure were less than those observed in a high-risk population; however, participants consuming higher amounts of foods prone to AF contamination may be more vulnerable to exposure and interactions with other environmental/biological factors (i.e., HCV).     

Biomonitoring of the adverse effects induced by the chronic exposure to lead and cadmium on kidney function: usefulness of alpha-glutathione S-transferase

A successful prevention of renal diseases induced by occupational exposure to lead (Pb) and/or cadmium (Cd) largely relies on the capability to detect nephrotoxic effects at a stage when they are still reversible or at least not yet compromising renal function. Hence, the aim of this cross-sectional study was to evaluate the usefulness of a set of early biological markers of oxidative stress or nephrotoxicity for the biomonitoring of workers occupationally exposed to Pb and/or Cd in a non-ferrous metal smelter, and gender, age, socioeconomic status, smoking habits, and drug use-matched control individuals. In exposed subjects, mean levels of Pb in blood and urine were also 387.1+/-99.1 microg Pb/L (1.868+/-0.478 micromol Pb/L) and 217.7+/-117.7 microg Pb/g creatinine (1.051+/-0.568 micromol Pb/g creatinine), and mean levels of Cd in blood and urine were 3.26+/-2.11 microg Cd/L (0.029+/-0.019 micromol Cd/L) and 2.51+/-1.89 microg Cd/g creatinine (0.022+/-0.017 micromol Cd/g creatinine), suggesting thereby relatively low occupational exposure levels. Statistically significant variations in zinc protoporphyrin, malondialdehyde, retinol binding protein, alpha-glutathione S-transferase, and urinary protein levels were reported between the two groups, and were closely correlated with Pb and/or Cd exposure levels. Variations in alphaGST levels were closely associated with Pb exposure. Taken together, these results suggest the use of alpha-glutathione S-transferase excretion in urine as a hallmark of early changes in the proximal tubular integrity.     

Glutathione-S-transferase polymorphism, metallothionein expression, and mercury levels among students in Austria

BACKGROUND: Detoxification is an essential process in all living organisms. Humans accumulate heavy metals primarily as a result of lifestyle and environmental contamination. However, not all humans experience the estimated individual exposure. This suggests the presence of genetic regulatory mechanisms. OBJECTIVE: In order to identify genetic factors underlying the inter-individual variance in detoxification capacity for the heavy metal mercury, 192 students were investigated. We focused on the relationship between polymorphisms in glutathione-S-transferase (GST) genes and mercury concentrations in blood, urine, and hair. The correlation between blood mercury levels, GSTT1 and GSTM1 polymorphism, and gene expression of certain metallothionein subgroups (MT1, MT3) was evaluated in a further group of students (N=30). METHODS: Mercury levels in acid digested samples were measured by cold vapor AAS. Genotyping of the GSTT1 and GSTM1-gene deletion polymorphism was performed by means of PCR. Gene expression of several MT genes was analyzed in lymphocytes from fresh peripheral blood by semiquantitative RT-PCR. RESULTS: The following was noted: a) hair mercury concentrations are significantly increased in persons with the double deleted genotype (GSTT1-/- and GSTM1-/-) as compared to persons with the intact genotype, and b) MT1X expression is higher in persons with the intact genotype (GSTT1+/+ and GSTM1+/+). CONCLUSIONS: We conclude that the epistatic effect of the GSTT1 and the GSTM1 deletion polymorphism is a risk factor for increased susceptibility to mercury exposure. The relationship between MT gene expression and GST gene polymorphisms needs further investigation. If MT expression depends on GST polymorphisms it would have important implications on the overall metal detoxification capability of the human organism.     

Effect of genotoxic exposure to chromium among electroplating workers in Taiwan.

The objective of this study was to investigate the association between chromium (Cr) concentrations and sister chromatid exchanges (SCE) formation in Cr workers and to assess the effects of susceptible genes (glutathione S-transferase M1 and T1) on the frequency of deletion and SCE/cell. Urinary Cr concentration was significantly elevated in Cr workers (3.67 +/- 3.89 microg/g creatinine) compared to control group (1.21 +/- 1.16 microg/g creatinine, P < 0.01). There was also a significant difference of superoxide dismutase (SOD) levels between Cr workers (6.86 +/- 0.80 U/mg Hb) and controls (7.16 +/- 0.53 U/mg Hb, P < 0.01). The frequencies of SCE and high frequency cells (HFC) were significantly correlated with smoking habits and with duration of exposure to Cr. A significantly higher percentage (50%) of Cr workers had both the null GSTM1 and GSTT1 genotype as compared to 10% of the controls (P < 0.01). However, the chromosomal DNA damage effect of GSTM1 and GSTT1 genotypes, individually or in combination, was not revealed in Cr exposed workers.     

Urinary 1-hydroxypyrene in children living in city and rural residences in Denmark

AIMS: The present study aims to assess the biological uptake in children of polycyclic aromatic hydrocarbons measured as 1-hydroxypyrene in urine from children living in city and rural residences. METHODS: 103 children living in Copenhagen and 101 children living in rural residences of Denmark collected urine samples Monday to Friday morning. Each day, the family filled in a printed diary that included questions about the time and activity patterns of the child. Multiple regression analyses were used to identify predictors of the excreted 1-hydroxypyrene level. RESULTS: During the week, the children excreted on average 0.07 [95% CI: 0.01-0.41] micromol urinary 1-hydroxypyrene per mol creatinine. Children living in urban residences excreted 0.02 [95% CI: 0.01-0.05] micromol more 1-hydroxypyrene than children living in rural residences. This was confirmed in the multiple regression analysis showing a 29% (95% CI: 2-64%) higher excretion among urban children than rural children. Moreover, the regression analysis showed that for each hour per day spent outside the children excreted 58% (1.58 [1.22-2.03]) more 1-hydroxypyrene in urine. CONCLUSION: The present study indicates that children living in urban residences are more exposed to PAH than children living in rural residences. Time spent outdoors increased the excretion of 1-hydroxypyrene, which was most evident among urban children. Higher concentrations of ambient air pollution in urban areas may explain this finding. No influence of environmental tobacco smoke, cooking habits, and heating facilities was detected.     

Exposure to polycyclic aromatic hydrocarbons, arsenic and environmental tobacco smoke, nutrient intake, and oxidative stress in Japanese preschool children

The association between oxidative stress and exposure to environmental chemicals was assessed in a group of Japanese preschool children. The concentrations of 8-hydroxy-2′-deoxyguanosine (8-OHdG), 1-hydroxypyrene (1-OHP), inorganic arsenic (iAs) and monomethylarsonic acid (MMA), and cotinine in spot urine samples, collected from 134 children (3-6 yrs) from a kindergarten in Kanagawa, Japan, were measured as biomarkers of oxidative stress or exposure to environmental chemicals. For 76 subjects of the 134, intakes of anti-oxidant nutrients (vitamins A, C, and E, manganese, copper, zinc and selenium (Se)) were estimated from a food consumption survey carried out 2-4 weeks after urine sampling and by urine analysis (Se). The median (min-max) creatinine-corrected concentrations of urinary biomarkers were 4.45 (1.98-12.3), 0.127 (0.04-2.41), 4.78 (1.18-12.7), and 0.62 (< 0.6-19.0) μg/g cre for 8-OHdG, 1-OHP, iAs + MMA, and cotinine, respectively. Multiple regression analysis was carried out using 8-OHdG concentration as a dependent variable and urinary biomarkers of exposure and Se intake, intakes of vitamins and biological attributes of the subjects as independent variables. To explain 8-OHdG concentrations, intake of vitamin A and age were significant variables with negative coefficients, while 1-OHP concentration had a positive coefficient. These results indicated that oxidative stress of children is affected by chemical exposure at environmental levels, by nutrient intake and by physiological factors in a complex manner. On the other hand, unstable statistical results due to sub-grouping of subject, based on the availability of food consumption data, were found: the present results should further be validated by future studies with suitable research design.     

Urban benzene exposure and oxidative DNA damage: influence of genetic polymorphisms in metabolism genes

Benzene has been implicated as an environmental risk factor in leukaemia and other haematological diseases. Relationships between urban benzene exposure, oxidative DNA damage and polymorphisms in metabolism enzymes were examined in 40 volunteers living and working in Copenhagen. Personal exposures to benzene, toluene and methyl tert-butyl ether (MTBE) were monitored during a 5-day period. DNA damage was measured by 7-hydro-8-oxo-2'-deoxyguanosine (8-oxodG) in lymphocyte DNA and urine and by comet assay with use of fapyguanine glycosylase (FPG) and endonuclease III (ENDO). Excretion of the benzene metabolites trans,trans-muconic acid (ttMA) and S-phenylmercapturic acid (S-PMA) were measured in urine. Polymorphisms in glutathione-S-transferases T1 (GSTT1), M1 (GSTM1) and P1 (GSTP1) and NAD(P)H:quinone oxidoreductase (NQO) were determined. Median exposures to benzene, toluene and MTBE were 2.5, 18.7 and 0.86 microg/m(3). No significant correlations between external benzene exposure and any of the biomarkers were found. However, a significant correlation between S-PMA excretion and 8-oxodG in lymphocytes was found (R(s)=0.39). Men were found to excrete significantly more ttMA than the women did and ttMA excretion in men was found to be significantly associated with external benzene exposure (R=0.53, P=0.025). In addition, ttMA and S-PMA excretion was significantly higher in subjects with the NQO+/-genotype compared with subjects with the wild type (P=0.004 and P=0.011, respectively). Even though there are some limitations in this study due to the low range of benzene exposure and biomarker concentrations as well as a small number of subjects, these results could suggest that even at ambient concentrations exposure to benzene could have genotoxic effects in susceptible individuals.     

Associations among genetic susceptibility, DNA damage, and pregnancy outcomes of expectant mothers exposed to environmental tobacco smoke

This study determined the effects of environmental tobacco smoke (ETS) on fetal growth by measuring neonatal birth outcomes and the extent of maternal DNA damage, and investigating the relationships among gene polymorphisms, genotoxicity, and pregnancy outcomes of expectant mothers who had exposed to tobacco smoke. This prospective study enrolled 685 pregnant women who completed an initial questionnaire at three central Taiwan hospitals between 2003 and 2004. Genotype analyses of CYP1A1, GSTT1, GSTM1, and NAT2 were performed from 421 women. A total of 398 women completed the follow-up analysis and successfully delivered a live single baby (n=384). Comet assay was performed for 18 smokers, 143 ETS-exposed subjects and 130 non-smokers to measure DNA damage. Analytical findings indicated that the levels of DNA damage among smokers and ETS-exposed subjects were significantly higher than that of non-smokers. DNA damage score in the ETS-exposed group was 82.5+/-41.2 and 64.1+/-39.4 for the nonsmoking group (p<0.001). Risk of DNA damage (DNA strand breakage, sister chromatid exchange, cell transformation and escalation of cytotoxicity) for subjects exposed to ETS was 4.35 times (adjusted odds ratio; 95% CI, 1.54-12.28) greater than that of non-exposed to tobacco smoke at home. Average birth weight of neonates born to subjects with extremely serious DNA damage (within the 90th percentile, DNA damage score >or =129.5) was 141 g lighter than that of those with DNA damage score <129.5 (p=0.09). The degree of DNA lesion was not related to metabolic polymorphic genes. The results of this study suggest that comet assay are reliable biomarkers for monitoring pregnant women exposed to tobacco smoke and indicate fetal growth effects from environmental exposure to tobacco smoke.     

Association of GSTM1 and GSTT1 polymorphisms with DNA damage in coal-tar workers

DNA damage was evaluated by alkaline comet assay in peripheral blood lymphocytes of 115 coal-tar workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs) and 105 control subjects. The effect of polymorphisms of glutathione S-transferase (GST) genotypes on the DNA damage was assessed. The mean tail moment (TM) value in the coal-tar workers was significantly higher as compared to the control subjects (12.06 ± 0.55 versus 0.44 ± 0.31; P < 0.05). No significant association (P > 0.05) between the GSTT1 and GSTM1 genotypes and the TM values was found, however highest mean rank TM value was reported in GSTM1 null and GSTT1 null genotypes in both control and exposed subjects. Our results suggest that there is increased DNA damage in coal-tar workers due to PAHs exposure. Polymorphisms in GSTM1 and GSTT1 genes do not show significant effect (P > 0.05) on DNA damage.     

坎地沙坦对糖尿病肾病大鼠足细胞保护作用的研究

目的探讨糖尿病肾病（diabetic nephropathy,DN）大鼠足细胞超微结构及其相关分子nephrin表达的变化,以及坎地沙坦对其干预的影响,为DN的防治提供理论依据。方法选择健康雄性SD大鼠36只,按随机数字表法分为A组（正常对照组）、B组（DN组）和C组（DN＋坎地沙坦组）,每组12只。B、C组尾静脉注射链脲佐菌素（30 mg.kg-1）制备DN大鼠模型,于DN模型成模1周后将3组大鼠分别在代谢笼中喂养,C组给予坎地沙坦5 mg.kg-1.d-1灌胃,A组及B组给予等量生理盐水灌胃。用药后第4周和第7周检测各组大鼠的血糖、体质量2、4 h尿蛋白和内生肌酐清除率（Ccr）,于第7周取肾组织行光学显微镜及电子显微镜观察肾脏病理改变、RT-PCR法检测nephrin-mRNA表达。结果与A组比较：B组24 h尿蛋白排泄增多（P〈0.05）,Ccr在7周时下降（P〈0.05）;肾组织内nephrin-mRNA表达下调（P〈0.05）;肾组织足细胞足突宽度增加并出现融合,肾小球基底膜增厚。与B组比较：C组24 h尿蛋白排泄量降低（P〈0.05）,Ccr升高（P〈0.05）;肾组织内nephrin-mRNA表达增加（P〈0.05）,足细胞足突宽度及肾小球基底膜厚度变小。结论 DN时存在足细胞分子nephrin表达异常和超微结构改变,坎地沙坦对肾脏的保护作用机制可能是通过增加nephrin表达、改善足细胞超微结构而实现。