The association between benzo[a]pyrene-DNA adducts and body mass index,calorie intake and physical activity

Prior work suggests that body size and fat content may influence carcinogen-DNA adduct levels measured in white blood cells. Here we consider energy balance more broadly by assessing the impact of body mass index (BMI), physical activity and calorie intake on the presence of benzo[a]pyrene-DNA (BP-DNA) adducts in white blood cell DNA. Our cross-sectional study employed subjects from a separately conducted intervention trial. Physical activity and food intake data were collected at 12 and 15 months of follow-up, respectively. BP-DNA adducts were measured by high-performance liquid chromatography (HPLC) in white blood cell samples collected at 12 months of follow-up. Complete data on all variables were available from 143 subjects. Logistic regression showed that BMI was inversely associated with the presence of detectable adducts (OR = 0.90, p=0.02), and that hours of moderate-intensity physical activity were positively associated with the presence of detectable adducts (OR = 1.04, p=0.04). These results provide further evidence that body fat content influences carcinogen-DNA adduct levels, probably by altering the distribution of the lipophilic parent compound.     

Benzo(a)pyrene diolepoxide adducts to albumin in workers exposed to polycyclic aromatic hydrocarbons: association with specific CYP1A1, GSTM1, GSTP1 and EHPX genotypes

We investigated whether the presence of (+)-anti-benzo(a)pyrene diolepoxide adducts to serum albumin (BPDE-SA) among workers exposed to benzo(a)pyrene (BaP) and unexposed reference controls was influenced by genetic polymorphisms of cytochrome P4501A1 (CYP1A1), microsomal epoxide hydrolase (EHPX), glutathione S-transferases M1 (GSTM1) and P1 (GSTP1), all involved in BaP metabolism. Exposed workers had significantly higher levels of adducts (0.124 ± 0.02 fmol BPTmg^-1 SA, mean ± SE) and a higher proportion of detectable adducts (40.3%) than controls (0.051 ± 0.01 fmol BPT mg^-1 SA; 16.1%) (p = 0:014 and p = 0:012). Smoking increased adduct levels only in occupationally exposed workers with the GSTM1 deletion (GSTM1 null) (p = 0:034).

Smokers from the exposed group had higher adduct levels when they were CYP1A1 *1/*1 wild-type rather than heterozygous and homozygous for the variant alleles (CYP1A1 *1/*2 plus *2/*2) (p = 0:01). The dependence of BPDE-SA adduct levels and frequency on the CYP1A1 *1/*1 genotype was most pronounced in GSTM1-deficient smokers. Exposed workers with GSTM1 null/GSTP1 variant alleles had fewer detectable adducts than those with the GSTM1 null/GSTP1*A wild-type allele, supporting for the first time the recent in vitro finding that GSTP1 variants may be more effective in the detoxification of BPDE than the wild-type allele. Logistic regression analysis indicated that occupational exposure, wild-type CYP1A1*1/*1 allele and the combination of GSTM1 null genotype+EHPX genotypes associated with predicted low enzyme activity were significant predictors of BPDE-SA adducts. Though our findings should be viewed with caution because of the relatively limited size of the population analysed, the interaction between these polymorphic enzymes and BPDE-SA adducts seems to be specific for high exposure and might have an impact on the quantitative risk estimates for exposure to polycyclic aromatic hydrocarbons.     

Strong influence of dietary intake and physical activity on body fatness in elderly Japanese men: age-associated loss of polygenic resistance against obesity

Genome-wide association studies identified single nucleotide polymorphisms (SNPs) associated with body mass index (BMI) in middle-aged populations; however, it is unclear whether these SNPs are associated with body fatness in elderly people. We examined the association between genetic risk score (GRS) from BMI-associated SNPs and body fatness in elderly Japanese men. We also examined the contribution of GRS, dietary macronutrient intake, and physical activity to body fatness by different age groups. GRS was calculated from 10 BMI-associated SNPs in 84 middle-aged (30–64 years) and 97 elderly (65–79 years) Japanese men; subjects were divided into low, middle, and high GRS groups. Dietary macronutrient intake was assessed using a questionnaire, and physical activity was evaluated using both a questionnaire and an accelerometer. The middle-aged individuals with a high GRS had greater BMI; waist circumference; and total abdominal fat, visceral fat, and subcutaneous fat areas than the middle-aged individuals with low GRS, whereas the indicators were not different between the GRS groups in elderly individuals. Multiple linear regression analysis showed that GRS was the strongest predictor of BMI, total abdominal fat, and visceral fat in the middle-aged group, whereas fat, alcohol, and protein intakes or vigorous-intensity physical activity were more strongly associated with these indicators than was GRS in the elderly group. These results suggest that GRS from BMI-associated SNPs is not predictive of body fatness in elderly Japanese men. The stronger contribution of dietary macronutrient intake and physical activity to body fatness may attenuate the genetic predisposition in elderly men.     

Influence of GSTM1, GSTT1, GSTP1, and EPHX gene polymorphisms on DNA adduct level and HPRT mutant frequency in coke-oven workers

To evaluate the influence of individual susceptibility factors on the level of polyaromatic (PAH) hydrocarbon DNA adducts and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutants in peripheral lymphocytes, 70 coke-oven workers exposed to PAH were genotyped for four metabolic enzyme polymorphisms of potential importance in PAH metabolism. The examined genetic polymorphisms concerned glutathione S-transferases M1 (GSTM1; gene deletion; 96 workers), T1 (GSTT1; gene deletion), P1 (GSTP1; Ile→Val substitution at codon 104 or Ile→Val at codon 104 and Val→Ala at codon 113), and microsomal epoxide hydrolase (EPHX; Tyr→His substitution at codon 113 and His→Arg at codon 139). The workers were classified in a high- and low-exposure group on the basis of urinary concentration of 1-pyrenol. The GSTM1 null genotype increased the number of DNA adducts in smoking coke-oven workers with high PAH exposure. DNA adducts were affected by PAH-exposure in non-smokers and in GSTM1 null smokers and by smoking in GSTM1 null individuals. In a multiple linear regression analysis, the interaction of the GSTM1 genotype was statistically significant (p=0.04) with smoking (yes/no) and of borderline significance (p=0.06) with PAH-exposure (high/low). As smoking also increased urinary 1-pyrenol, the genotype modification seemed to concern DNA adducts due to smoking rather than occupational exposure. GSTT1 positive individuals showed an elevated level of DNA adducts in comparison with GSTT1 null subjects (p=0.04), and EPHX genotypes associated with slow hydroxylation reaction yielded a higher (p=0.05) HPRT mutant frequency than fast EPHX genotypes; these findings were, however, based on small numbers of subjects and need to be clarified in further studies. In conclusion, our findings indicate that homozygous deletion of GSTM1 results in an increased sensitivity to genotoxic PAHs in tobacco smoke, which is seen as an increase in aromatic DNA adducts in blood mononuclear cells.     

Reduction of 8-hydroxyguanine in human leukocyte DNA by physical exercise

We investigated the effect of physical exercise on the level of 8-hydroxyguanine (8-OH-Gua), a form of oxidative DNA damage, and its repair activity in human peripheral leukocytes. Whole blood samples were collected by venipuncture from 21 healthy male volunteers (10 trained athletes and 13 untrained men), aged 19-50 years, both before and after physical exercise. Trained athletes showed a lower level of 8-OH-Gua (2.4 ± 0.5/10⁶ Gua, p = 0.0032) before exercise when compared to that of untrained men (6.2 ± 3.5). The mean levels of 8-OH-Gua of untrained subjects decreased significantly (p = 0.0057) from 6.2 ± 3.5/10⁶ Gua (mean ± SD/10⁶ Gua) to 3.3 ± 1.4/10⁶ Gua after physical exercise. On the other hand, the mean levels of repair activity of untrained subjects significantly increased after exercise (p = 0.0093) from 0.037 ± 0.024 (mean DNA cleavage ratio ± SD) to 0.056 ± 0.036. In the trained athletes 8-OH-Gua level and its repair activity were not changed before and after the exercise. We also observed inter-individual differences in 8-OH-Gua levels and its repair activities. These results suggest that physical exercise causes both rapid and long-range reduction of oxidative DNA damage in human leukocytes, with individually different efficiencies.     

Preliminary studies on the effect of moderate physical activity on blood levels of glutathione

Molecular epidemiological approaches are being used to study how physical activity may protect against cancer. Prior epidemiological data suggest that physical activity protects against lung cancer; however, interpretation of these data is complicated by potential confounding by smoking. Glutathione (GSH) detoxifies cigarette smoke carcinogens and the paper tests whether physical activity levels are associated with blood GSH levels. Study subjects were enrolled in a chemoprevention trial testing whether antioxidant micronutrient supplementation reduces genetic damage from cigarette smoking. Physical activity data were collected by questionnaire from 178 subjects at 12 months of follow-up in the trial. Total GSH (tGSH), which is the sum of free and protein-bound GSH and glutathione disulfide levels, was measured using the 5,5'-dithiobis-(2-nitrobenzenoic acid) colormetric assay with red blood cell samples collected at the 12-month time point. In multivariate linear regression analyses that controlled for gender and cigarettes smoked per day, tGSH was positively associated with hours per week of moderate intensity activity (β=0.005, p=0.02). Hours per week of vigorous intensity activity were unassociated with tGSH and the effect of moderate activity remained after control for vigorous activity. The results are consistent with prior research showing differential effects of moderate and vigorous activity and suggest a mechanism through which physical activity may influence lung cancer risk.     

Physical activity and lung cancer among non-smokers: a pilot molecular epidemiological study within EPIC

The association between physical activity, potential intermediate biomarkers and lung cancer risk was investigated in a study of 230 cases and 648 controls nested within the European Prospective Investigation of Cancer and Nutrition. Data on white blood cell aromatic-DNA adducts by ³²P-post-labelling and glutathione (GSH) in red blood cells were available from a subset of cases and controls. Compared with the first quartile, the fourth quartile of recreational physical activity was associated with a lower lung cancer risk (odds ratio (OR) 0.56, 95% confidence interval (CI) 0.35–0.90), higher GSH levels (+1.87 μmol GSH g^?1 haemoglobin, p = 0.04) but not with the presence of high levels of adducts (OR 1.05, 95% CI 0.38–2.86). Despite being associated with recreational physical activity, in these small-scale pilot analyses GSH levels were not associated with lung cancer risk (OR 0.95, 95% CI 0.84–1.07 per unit increase in GSH levels). Household and occupational activity was not associated with lung cancer risk or biomarker levels.     

Quantitation of benzo[a]pyrene-DNA adducts by postlabeling with 14C-acetic anhydride and accelerator mass spectrometry

Quantitation of carcinogen-DNA adducts provides an estimate of the biologically effective dose of a chemical carcinogen reaching the target tissue. In order to improve exposure-assessment and cancer risk estimates, we are developing an ultrasensitive procedure for the detection of carcinogen-DNA adducts. The method is based upon postlabeling of carcinogen-DNA adducts by acetylation with 14C-acetic anhydride combined with quantitation of 14C by accelerator mass spectrometry (AMS). For this purpose, adducts of benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE) with DNA and deoxyguanosine (dG) were synthesized. The most promutagenic adduct of BPDE, 7R,8S,9R-trihydroxy-10S-(N(2)-deoxyguanosyl)-7,8,9, 10-tetrahydrobenzo[a]pyrene (BPdG), was HPLC purified and structurally characterized. Postlabeling of the BPdG adduct with acetic anhydride yielded a major product with a greater than 60% yield. The postlabeled adduct was identified by liquid chromatography-mass spectrometry as pentakis(acetyl) BPdG (AcBPdG). Postlabeling of the BPdG adduct with 14C-acetic anhydride yielded a major product coeluting with an AcBPdG standard. Quantitation of the 14C-postlabeled adduct by AMS promises to allow detection of attomolar amounts of adducts. The method is now being optimized and validated for use in human samples.     

In vitro genotoxicity of PAH mixtures and organic extract from urban air particles part I: acellular assay

Acellular assay of calf thymus DNA ± rat liver microsomal S9 fraction coupled with ³²P-postlabelling was used to study the genotoxic potential of organic compounds bound onto PM10 particles collected in three European cities—Prague (CZ), Kosice (SK) and Sofia (BG) during summer and winter periods. B[a]P alone induced DNA adduct levels ranging from 4.8 to 768 adducts/10⁸ nucleotides in the concentration dependent manner. However, a mixture of 8 c-PAHs with equimolar doses of B[a]P induced 3.7–757 adducts/10⁸ nucleotides, thus suggesting the inhibition of DNA adduct forming activity by interaction among various PAHs. Comparison of DNA adduct levels induced by various EOMs indicates higher variability among seasons than among localities. DNA adduct levels for Prague collection site varied from 19 to 166 adducts/10⁸ nucleotides, for Kosice from 22 to 85 and for Sofia from 6 to 144 adducts/10⁸ nucleotides. Bioactivation with S9 microsomal fraction caused 2- to 7-fold increase in DNA adduct levels compared to −S9 samples, suggesting a crucial role of indirectly acting genotoxic EOM components, such as PAHs. We have demonstrated for the first time a significant positive correlation between B[a]P content in EOMs and total DNA adduct levels detected in the EOM treated samples (R = 0.83; p = 0.04). These results suggest that B[a]P content in EOM is an important factor for the total genotoxic potential of EOM and/or B[a]P is a good indicator of the presence of other genotoxic compounds causing DNA adducts. Even stronger correlation between the content of genotoxic compounds in EOMs and total DNA adduct levels detected (R = 0.94; p = 0.005) was found when eight c-PAHs were taken into the consideration. Our findings support a hypothesis that a relatively limited number of EOM components is responsible for a major part of its genotoxicity detectable as DNA adducts by ³²P-postlabelling.     

A cross-sectional study of polycyclic aromatic hydrocarbon-DNA adducts and polymorphism of glutathione S-transferases among heavy smokers by race/ethnicity.

Differences in lung cancer risk by race/ethnicity have been observed among smokers. To determine whether these observations might reflect differences in the formation of carcinogen-DNA adducts, we analysed blood specimens (n=151) collected from smokers who were recruited for possible participation in an antioxidant vitamin intervention study. Mononuclear cells were analysed for polycyclic aromatic hydrocarbon (PAH)-DNA adducts by competitive enzyme-linked immunosorbent assay. Genotypes of glutathione S-transferase M1 and P1 (GSTM1 and GSTP1), enzymes involved in the detoxification of PAH metabolites, were determined by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism, respectively. GSTM1 was present in 65 out of 88 (73.4%), 16 out of 32 (50.0%) and 16 out of 29 (54.8%) of African-Americans, Caucasians and Latinos, respectively (p=0.022). Homozygosity for the GSTP1 codon 105 variant was found in 25.6%, 6.3% and 10.0% of African-Americans, Caucasians and Latinos, respectively (p=0.023). Regression analysis of the log-transformed adduct levels confirmed that Caucasian and Latino subjects had lower PAH-DNA adduct levels than African-American subjects, after adjustment for gender, education, alpha-tocopherol and beta-carotene levels, and GSTM1 status. Further adjustment for age and current smoking habits had no impact on these findings. Although crude analysis suggested that the GSTM1-positive genotype may be associated with lower PAH-DNA levels in Caucasians (but not in African-Americans or Latinos), a formal test for interaction between GSTM1 and ethnicity was not significant. We found no association between adduct levels and GSTP1 genotype. Although the mechanism is unclear, ethnic differences in DNA damage levels may in part explain why African-Americans have higher lung cancer incidence rates than other ethnic groups.     

A romatic DNA adduct levels in human peripheral blood lymphocytes and total white blood cells by 32P postlabelling: need for validation

Long lived lymphocytes tend to have higher 32P postlabelling measured levels of adducts than short lived granulocytes in environmental and life style associated i.e. smoking exposures. With the aim of investigating this issue for occupational exposure to PAH and contributing to further validation of some technical aspects of the 32P postlabelling assay, two Italian laboratories analysed PAH-DNA adducts from lymphocytes and total white blood cells WBC . Seventy seven blood samples from coke oven workers employed at a steel plant located in Taranto, Southern Italy, and 14 samples from control subjects were collected. At the University of Padua, DNA was purified from peripheral blood lymphocytes PBL . Two years later, at the University of Bari, white blood cells WBC were isolated from replicate blood samples stored at- 80 C and DNA purified by the same method. In both cases, the nuclease P1 modified postlabelling assay was used to determine aromatic DNA adduct levels. The mean adduct levels were 5.13 3.37 Padua and 2.48 1.27 Bari per 108 nucleotides. Both laboratories observed large inter individual variations of adduct levels ranging from 0.09 to 18.93 per 108 nucleotides. Both the correlation and the agreement of the two sets of data were assessed. Slight correlation r = 0.39; p 0.01 and a poor level of agreement were found, the intra class correlation coefficient being equal to 0.05. Better correlation coefficient r = 0.54, p 0.01 and intra class correlation coefficient r = 0.50 were observed comparing only the adduct levels determined on the diagonal zone DRZ . Our findings seem to confirm the same divergence reported in the literature on DNA adduct levels between lymphocytes and granulocytes.     

A romatic DNA adduct levels in human peripheral blood lymphocytes and total white blood cells by 32P postlabelling: need for validation

Long lived lymphocytes tend to have higher 32P postlabelling measured levels of adducts than short lived granulocytes in environmental and life style associated i.e. smoking exposures. With the aim of investigating this issue for occupational exposure to PAH and contributing to further validation of some technical aspects of the 32P postlabelling assay, two Italian laboratories analysed PAH-DNA adducts from lymphocytes and total white blood cells WBC. Seventy seven blood samples from coke oven workers employed at a steel plant located in Taranto, Southern Italy, and 14 samples from control subjects were collected. At the University of Padua, DNA was purified from peripheral blood lymphocytes PBL. Two years later, at the University of Bari, white blood cells WBC were isolated from replicate blood samples stored at- 80 C and DNA purified by the same method. In both cases, the nuclease P1 modified postlabelling assay was used to determine aromatic DNA adduct levels. The mean adduct levels were 5.13 3.37 Padua and 2.48 1.27 Bari per 108 nucleotides. Both laboratories observed large inter individual variations of adduct levels ranging from 0.09 to 18.93 per 108 nucleotides. Both the correlation and the agreement of the two sets of data were assessed. Slight correlation r = 0.39; p 0.01 and a poor level of agreement were found, the intra class correlation coefficient being equal to 0.05. Better correlation coefficient r = 0.54, p 0.01 and intra class correlation coefficient r = 0.50 were observed comparing only the adduct levels determined on the diagonal zone DRZ. Our findings seem to confirm the same divergence reported in the literature on DNA adduct levels between lymphocytes and granulocytes.     

Safrole-DNA adducts in human peripheral blood--an association with areca quid chewing and CYP2E1 polymorphisms

It has been recently demonstrated that safrole (4-allyl-1,2-methylenedioxybenzene)-DNA adducts are present in oral cancer tissue from patients who have chewed areca quid (AQ) containing high concentration of safrole. In this study, the presence of safrole-DNA adducts in peripheral white blood cells from 88 subjects with a known AQ chewing history and 161 matched controls were studied with the aim of identifying the adducts as a biomarker for safrole exposure. This study also analyzed the correlation between the level of safrole-DNA adducts and polymorphism of the CYP2E1 gene, alone and in combination with the GST M1 and GST T1-deletion polymorphisms. The results demonstrated the presence of safrole-DNA adducts in 83 (94.32%) of the DNA samples from subjects with current AQ chewing history and 21 (13.04%) of the control samples without known AQ chewing habit ( [Formula: see text] ). Individuals with at least one CYP2E1 c2 allele had a significant higher frequency of safrole-DNA adducts (odds ratio (OR), 4.00; 95% confidence interval (CI), 1.03-15.53) than those with the CYP2E1 c1c1 genotype while chewing less than 20 areca quids per day. In conclusion, this study demonstrates the presence of safrole-DNA adducts in peripheral blood lymphocytes (PBL), and the presence of these safrole-DNA adducts is correlated with AQ chewing. In addition, the CYP2E1 would seem to play an important role in the modulation of safrole-DNA adduct formation.     

Comparison of demography, diet, lifestyle, and serum lipid levels between the Guangxi Bai Ku Yao and Han populations

Bai Ku Yao is an isolated subgroup of the Yao minority in China. Little is known about dyslipidemia in this population. The aim of this study was to compare the effects of demography, diet, and lifestyle on serum lipid levels between the Bai Ku Yao and Han populations. A total of 1,170 subjects of Bai Ku Yao and 1,173 subjects of Han Chinese aged 15-89 years were surveyed by a stratified randomized cluster sampling. The levels of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A-I (apoA-I), and apoB were significantly lower in Bai Ku Yao than in Han. Physical activity level and total dietary fiber intake were higher, whereas body mass index (BMI), waist circumference, total energy intake, and total fat intake were lower in Bai Ku Yao than in Han. Hyperlipidemia was positively correlated with BMI, waist circumference, and total energy and total fat intakes and negatively associated with physical activity level and total dietary fiber intake in both populations, but it was positively associated with age and alcohol consumption only in Han. The differences in the lipid profiles between the two ethnic groups were associated with different dietary habits, lifestyle choices, and levels of physical activities.     

Carcinogen-DNA adducts as a biomarker for cancer risk

Carcinogen-DNA adducts are thought to be a useful biomarker in epidemiologic studies seeking to show that environmental exposures to xenobiotics cause cancer. This paper reviews the literature in this field from an epidemiologic perspective and identifies several common problems in the epidemiologic design and analysis of these studies. Carcinogen-DNA adducts have been used in studies attempting to link xenobiotic exposures to hepatocellular carcinoma, smoking related cancers and breast cancer. Adduct measurements have been useful in further implicating aflatoxin exposure in the etiology of hepatocellular carcinoma. For smoking related cancers, associations with carcinogen-DNA adducts are commonly seen in current smokers but less so in ex- or non-smokers. In breast cancer the associations have been inconsistent and weak and there is little evidence that carcinogen-DNA adducts implicate xenobiotic exposures in the etiology of breast cancer. Methodological issues common to these studies are the use of target versus surrogate tissues and how this choice impacts control selection, disease effects on adduct levels, the time period reflected by adduct levels, the use of inappropriate statistical analyses and small sample sizes. It is unclear whether the lack of association between carcinogen-DNA adducts and cancer reflects a lack of association between the xenobiotic exposure of interest and cancer or the effects of these methodological issues. A greater focus needs to be placed on designs that allow measurements of adduct levels in tissues collected years prior to cancer diagnosis, there is little need for further hospital based case-control studies in which adducts are measured at the time of or after diagnosis. New designs that address these issues are suggested in the paper.     

Differential Effects of Abdominal Adipose Tissue Distribution on Insulin Sensitivity in Black and White South African Women

Black South African women are more insulin resistant than BMI‐matched white women. The objective of the study was to characterize the determinants of insulin sensitivity in black and white South African women matched for BMI. A total of 57 normal‐weight (BMI 18–25 kg/m²) and obese (BMI > 30 kg/m²) black and white premenopausal South African women underwent the following measurements: body composition (dual‐energy X‐ray absorptiometry), body fat distribution (computerized tomography (CT)), insulin sensitivity (S_I, frequently sampled intravenous glucose tolerance test), dietary intake (food frequency questionnaire), physical activity (Global Physical Activity Questionnaire), and socioeconomic status (SES, demographic questionnaire). Black women were less insulin sensitive (4.4 ± 0.8 vs. 9.5 ± 0.8 and 3.0 ± 0.8 vs. 6.0 ± 0.8 × 10^?5/min/(pmol/l), for normal‐weight and obese women, respectively, P < 0.001), but had less visceral adipose tissue (VAT) (P = 0.051), more abdominal superficial subcutaneous adipose tissue (SAT) (P = 0.003), lower SES (P < 0.001), and higher dietary fat intake (P = 0.001) than white women matched for BMI. S_I correlated with deep and superficial SAT in both black (R = ?0.594, P = 0.002 and R = 0.495, P = 0.012) and white women (R = ?0.554, P = 0.005 and R = ?0.546, P = 0.004), but with VAT in white women only (R = ?0.534, P = 0.005). In conclusion, body fat distribution is differentially associated with insulin sensitivity in black and white women. Therefore, the different abdominal fat depots may have varying metabolic consequences in women of different ethnic origins.     

Dietary and Physical Activity Correlates of Long-Term Weight Loss

Covariations in body mass index (BMI), physical activity, macronutrient intake, and the frequency of consumption of specific foods were examined among 82 men and 75 women participating in a behavioral weight loss program over a period of 18 months. Results of repeated measures analyses of covariance showed that BMI change was inversely related to change in physical activity and change in frequency of vegetable consumption. BMI change was positively related to change in calorie intake from fat and change in frequency of consumption of beef, hot dogs, and sweets. Change in fat calories predicted BMI change better than change in total calories. In addition, change in the frequency of consumption of specific foods accounted for a larger percentage of the variance in BMI change than did change in macronutrients (10.4% vs. 5.2%). No differences were found between predictors of weight loss vs. weight maintenance.     

In vitro genotoxicity of PAH mixtures and organic extract from urban air particles part II: human cell lines

Principal aims of this study were at first, to find a relevant human derived cell line to investigate the genotoxic potential of PAH-containing complex mixtures and second, to use this cell system for the analysis of DNA adduct forming activity of organic compounds bound onto PM10 particles. Particles were collected by high volume air samplers during summer and winter periods in three European cities (Prague, Kosice, and Sofia), representing different levels of air pollution. The genotoxic potential of extractable organic matter (EOM) was compared with the genotoxic potential of individual carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) as well as their artificial mixtures. Metabolically competent human hepatoma HepG2 cells, confluent cultures of human diploid lung fibroblasts (HEL), and the human monocytic leukemia cell line THP-1 were used as models. DNA adducts were analyzed by ³²P-postlabeling. The total DNA adduct levels induced in HepG2 cells after exposure to EOMs were higher than in HEL cells treated under the same conditions (15–190 versus 2–15 adducts/10⁸ nucleotides, in HepG2 and HEL cells, respectively). THP-1 cells exhibited the lowest DNA adduct forming activity induced by EOMs (1.5–3.7 adducts/10⁸ nucleotides). A direct correlation between total DNA adduct levels and c-PAH content in EOM was found for all EOMs in HepG2 cells incubated with 50 μg EOM/ml (R = 0.88; p = 0.0192). This correlation was even slightly stronger when B[a]P content in EOMs and B[a]P-like adduct spots were analyzed (R = 0.90; p = 0.016). As THP-1 cells possess a limited metabolic capacity for most c-PAHs to form DNA reactive intermediates and are also more susceptible to toxic effects of PAHs and various EOM components, this cell line seemed to be an inappropriate system for genotoxicity studies of PAH-containing complex mixtures. The seasonal variability of genotoxic potential of extracts was stronger than variability among the three localities studied. In HepG2 cells, the highest DNA adduct levels were induced by EOM collected in Prague in the winter period, followed by Sofia and Kosice. However, in the summer sampling period, the order was quite opposite: Kosice > Sofia > Prague. When the EOM content per m³ of air was taken into consideration in order to compare real exposures of humans to genotoxic compounds in all three localities, extracts from respirable dust particles collected in Sofia exhibited the highest genotoxicity regardless of the sampling period. The results indicate that most of DNA adducts detected in cells incubated with EOMs have their origin in low concentrations of c-PAHs representing 0.03–0.17% of EOM total mass. Finally, our results suggest that HepG2 cells have a metabolic capacity for PAHs similar to human hepatocytes and represent therefore the best in vitro model for investigating the genotoxic potential of complex mixtures containing PAHs among the three cell lines tested in this study.     

Television viewing and obesity in 300 women: evaluation of the pathways of energy intake and physical activity

We assessed the roles of energy intake and physical activity in the relationships among television (TV) viewing, body composition, and obesity using high-quality measurement methods. Adult women (n = 300) reported TV viewing behavior, which was categorized into infrequent (≤ 1 h/day), moderate (2 h/day), and frequent (≥ 3 h/day) viewing. Body fat percentage (BF%) was assessed using plethysmography (Bod Pod) and BMI was calculated from height and body weight. Energy intake and physical activity, including time spent in sedentary, moderate, and vigorous physical activity (PA), were objectively measured using 7-day weighed food records and 7-day accelerometry, respectively. The mean BF% of frequent TV viewers (34.6 ± 6.9%) was significantly greater (F = 3.9, P = 0.0218) than those of moderate (31.5 ± 6.7%) and infrequent viewers (30.8 ± 7.0%); however, BMI did not differ across the TV viewing groups (F = 0.8, P = 0.4172). Controlling statistically for differences in age, education, time in sedentary activity, time in moderate activity, and energy intake, considered individually, had no influence on the relationships between TV viewing and BF%, nor TV and BMI. Moreover, the relationship between TV and BF% remained significant after adjusting for differences in BMI (F = 3.6, P = 0.0276). However, adjusting for total PA reduced the relationship between TV and BF% to nonsignificance (F = 2.5, P = 0.0810), as did time spent in vigorous PA (F = 2.2, P = 0.1307). These data suggest a strong relationship between TV viewing and BF%. This association appears to be due, in part, to differences in total PA, particularly vigorous PA, but not time spent in sedentary activity, moderate activity, or energy intake.     

Energy-Related Indicators and Breast Cancer Risk among White and Black Women

Energy-related indicators, including physical activity, energy intake, body mass index (BMI) and adult weight change, have been linked to breast cancer risk. Very few studies of these associations have been conducted among black women, therefore we used the Nashville Breast Health Study (NBHS) to determine whether similar effects were seen in black and white women. The NBHS is a population-based case-control study of breast cancer among women age 25 to 75 years conducted between 2001 and 2010 in and around the Nashville Metropolitan area. Telephone interviews and self-administered food frequency questionnaires were completed with 2,614 incident breast cancer cases ascertained through hospitals and the statewide cancer registry, and 2,306 controls selected using random digit dialing. Among premenopausal white and black women, there was little effect of adult exercise or other energy-related indicators on breast cancer risk, regardless of tumor estrogen receptor (ER) status. The beneficial effect of adult exercise on postmenopausal breast cancer appeared to be comparable between white and black women (highest tertile relative to none - white odds ratio [OR] 0.8, 95% confidence interval [CI] 0.6-1.0, p for trend=0.05; black OR 0.7, 95% CI 0.4-1.1, p for trend=0.07); however, among black women the reduction was limited to those with ER-positive disease. White and black women should be encouraged to engage in more physical activity to reduce their risk of postmenopausal breast cancer.