Yuquan Lu

Effects of cigarette smoking, XRCC1 genetic polymorphisms, and age on basal DNA damage in human blood mononuclear cells.

The aim of this study was to investigate the effects of smoking, polymorphisms of XRCC1 codons 194 and 399, and age on levels of basal DNA damage (as measured by an alkaline comet assay) on mononuclear cells in 122 healthy Japanese workers. In the whole group of 122 individuals, the tail moment (TM) values of current smokers (P < 0.001) or former smokers (P = 0.03) were significantly higher than those of nonsmokers. Individuals bearing the XRCC1 399Gln variant allele showed significant increases in TM values in all subjects or in referent subgroups stratified by age or smoking status except in the current smokers group; in contrast, the TM values of individuals bearing the XRCC1 194Trp variant allele were significantly lower than those of individuals bearing wild-type Arg/Arg genotypes. Furthermore, older subjects (> or =47 years old) had significantly higher TM values than younger subjects (<47 years old) in all subjects (P = 0.008). Multiple regression analysis indicated that smoking habits, polymorphisms of XRCC1 codons 194 and 399, and age were important variables affecting individuals basal DNA damage.

Exposure level to cigarette tar or nicotine is associated with leukocyte DNA damage in male Japanese smokers

We investigated the number of cigarettes smoked daily, years of smoking, cigarette pack-years, levels of daily exposure to cigarette tar (LECT, mg/day) or nicotine (LECN, mg/day) in 53 male Japanese smokers using a questionnaire and measured each participants baseline leukocyte DNA damage using the alkaline comet assay. The results showed that the baseline value of peripheral leukocyte DNA strand breaks was significantly associated with LECT (P < 0.05), LECN (P < 0.05), years of smoking or cigarette pack-years (P < 0.05) but not with the number of cigarettes smoked per day. Stepwise multiple regression analyses of factors including age, occupation, years of employment, alcohol drinking behaviour, physical activity, nutritional balance and cigarette smoking parameters showed that LECT was a positively significant predictor (Partial r = 0.0005, P < 0.05) of the comet tail moment. In consideration of the high correlation between LECT and LECN (Y(tar) = 12.53 X(nicotine) -7.23, r = 0.995, P < 0.0001), these results suggest that levels of exposure to cigarette tar or nicotine (mg/day) would be a sensitive parameter in appreciation of genotoxicity of cigarette smoking in these male Japanese smokers.

Effects of alcohol-drinking behaviour and ADH1B and ALDH2 polymorphisms on basal DNA damage in human mononuclear cells as determined by the comet assay.

The aim of this study was to investigate the effects of alcohol drinking and ADH1B and ALDH2 polymorphisms on basal DNA damage (measured by the alkaline comet assay) of mononuclear cells in 122 healthy Japanese workers. Our results showed that drinking frequency had a significant impact on the tail moment (TM) value, with the highest TM value observed in habitual drinkers. The presence of the ADH1B*2 or ALDH2*2 allele was associated with increased DNA damage in older habitual drinkers. Furthermore, habitual drinkers with a combined genotype of ADH1B*2/*2 and ALDH2*1/*2 demonstrated a significantly higher TM value than other groups. Moreover, the combination of drinking and smoking has a combined effect on DNA damage. Multiple regression analysis revealed that drinking frequency, smoking status, and ALDH2 polymorphisms significantly influence basal TM value, suggesting that these are important variables affecting individual basal DNA damage.

Effects of the XRCC1 gene-environment interactions on DNA damage in healthy Japanese workers

X‐ray repair crosscomplementing group 1 (XRCC1) has a central role in base excision repair (BER) and single‐strand break repair (SSBR). XRCC1 gene polymorphisms (codons 194, 280, and 399) have been identified, and in some cases have been reported to contribute to variations in DNA repair capacity and susceptibility to cancer. To further characterize the effects of XRCC1 gene polymorphisms and their possible interactions with environmental factors on individual levels of DNA damage, we investigated the XRCC1 genotypes of 222 healthy Japanese workers and analyzed data with respect to smoking, drinking habits, age, and health practice index (HPI). Our results showed that poor HPI would associate with a higher level of tail moment (TM). Individuals with one or two XRCC1R280H variant alleles exhibited significantly higher TM values, and these differences were enhanced by alcohol consumption and aging, whereas smoking and poor HPI may cover up the differences. On the other hand, using a stratified analysis, we found that the XRCC1R194W variant was associated with a higher TM value in the 40–50 year‐old age group, and the XRCC1R399Q variant was associated with a lower TM value in the ≤20 pack‐years group or in the 40–50 year‐old age group. These data suggest that XRCC1 polymorphisms could influence individual DNA repair capacity by interacting with lifestyle factors, and specifically, the data indicated that the XRCC1R280H allele may be more important than codon 194 or 399 alleles. Environ. Mol. Mutagen., 2008.

Is habitual alcohol drinking associated with reduced electrophoretic DNA migration in peripheral blood leukocytes from ALDH2-deficient male Japanese?

Alcohol drinking-derived acetaldehyde is believed to cross-link DNA and induce sister chromatid exchanges in peripheral blood lymphocytes. However, little population data are available to illustrate effects of alcohol-derived acetaldehyde on DNA migration as assayed by the comet assay in peripheral lymphocytes. In the present study, we investigated lifestyle behaviours, including alcohol consumption, in 150 Japanese males by questionnaire, determined their aldehyde dehydrogenase 2 (ALDH2) family genotypes by polymerase chain reaction and measured the DNA migration in peripheral blood leukocytes by the alkaline comet assay. The results showed that habitual alcohol drinking is significantly negatively associated with DNA migration in peripheral blood leukocytes (r = -0.321, P = 0.005) of ALDH2-deficient, but not of ALDH2-proficient genotypes (r = 0.048, P = 0.683). The amount of pure alcohol consumed per time by the subjects showed a similar phenomenon (r = -0.257, P = 0.025 for the ALDH2-deficient, but r = -0.061, P = 0.606 for the ALDH2-proficient genotype). Further stepwise multiple regression analysis showed that alcohol drinking frequency was a significant predictor of DNA migration for subjects with ALDH2-deficient genotype, but not for subjects with ALDH2-proficient genotype. In summary, the present result suggests that frequent alcohol drinking is significantly associated with a reduced electrophoretic DNA migration in peripheral blood leukocytes from ALDH2-deficient male Japanese subjects.

Single-cell gel electrophoresis (SCG)-A review and discussion.

Single-cell gel electrophoresis (SCG) is a simple, sensitive and effective technique. Being able to reflect quantitatively the genotoxicity of many hazardous agents, it is promising for application in environmental genotoxic monitoring and the study of carcinogenesis. In clinics, it can be used to evaluate the DNA repair ability and monitor DNA breaks during cancer therapy. As a biomarker, it has its own merits and limitations, being different from other biomarkers such as sister chromatid exchange (SCE) test and micronuclei (MN) assay. In many studies, it is more sensitive than SCE or MN. Combination studies with other biomarkers like SCE, MN, chromosomal aberration, bcl-2 and genetic polymorphisms have begun to demonstrate its great importance for the understanding of carcinogenesis and the genotoxicities of environmental factors.

Efforts to Ensure Safety of Hospital Pharmacy Personnel Occupationally Exposed to Antineoplastic Drugs During a Preparation Task

Purpose Antineoplastic drugs are often detected in the plasma and urine of medical staff, despite the adoption of safety measures. This study involves ambulatory chemotherapy, which was prepared on a rotating schedule at the Department of Pharmacy. The first objective of this study was to evaluate occupational exposure by measuring epirubicin in the urine and plasma and sister chromatid exchanges (SCE) in the peripheral lymphocytes of the involved pharmacists. The second, to improve a previously reported method for ease of occupational exposure evaluation. The third, to determine environmental contamination. Methods Pharmacists were categorized into three groups based on three patterns, depending on the other tasks they performed. They were alternately responsible for the preparation in each group with the recommended protections. Samples were collected at the end of each work day. High-performance liquid chromatography (HPLC) analysis along with fluorescence detection was performed at a flow rate of 200 mcL/min using 0.1% formic acid, methanol, and acetonitrile (75:5:20). Epirubicin in the samples was extracted by solid-phase extraction. Chromosomes were prepared according to a standard protocol. Results A final concentration of 2 ng/mL was the lower quantification limit. Epirubicin was not detected in the urine and plasma, and the SCE levels were within the normal limits for all the subjects. However, epirubicin was detected in samples collected from the preparation gloves. Conclusions For personnel safety, it is important to periodically evaluate protective measures. Pharmacists on a rotating schedule who work less than 6 hours per week on preparatory tasks were not unduly exposed to antineoplastics.

Differential DNA damage induced by H2O2 and bleomycin in subpopulations of human white blood cells

The purpose of this study was to characterize the differential sensitivities of various subpopulations of human white blood cells after exposure to H2O2 (an oxidant agent) and bleomycin (a radiomimetic glycopeptide), in vitro, using single-cell gel electrophoresis (SCGE). Human peripheral blood was fractionated into mononuclear cells, which were further separated into monocytes, CD4+ T-cells, CD8+ T-cells, B-cells and natural killer cells (NK cells). The separated fractions were exposed to different doses of H2O2 and bleomycin, and then used to measure levels of induced and basal DNA damage. There was a significant increase in the amount of DNA damage in CD4+ T-cells, CD8+ T-cells, NK cells and B-cells when treated with H2O2 and bleomycin, whereas monocytes had the lowest sensitivity to H2O2 compared with the other cell fractions, but no lower sensitivity to bleomycin. Furthermore, CD4+ T-cells and CD8+ T-cells had the highest levels of basal DNA damage. When basal DNA damage was taken into account, NK cells tended to show a higher sensitivity to H2O2 than CD4+ T-cells, CD8+ T-cells and monocytes. In addition, B-cells, which showed lower sensitivity to H2O2 than CD4+ T-cells, CD8+ T-cells and NK cells when exposed to lower doses of H2O2 (<10 microM), showed higher sensitivity to H2O2 at higher doses (>20 microM). On the other hand, B-cells showed the highest sensitivity to bleomycin.

Rejoining kinetics of bleomycin-induced DNA single-strand breaks in agarose-bound human blood cells.

The rejoining kinetics of individual DNA single-strand breaks (SSBs) are difficult to measure, in biomonitoring studies, because SSB rejoining is rapid and hard to control. We have detected early (0, 1, 2, 5, 10 and 30 min) events in SSB rejoining in human leukocytes, with the alkaline comet assay, at a low concentration of bleomycin (BLM; 0.5 μg/ml). Background Tail DNA% (percentage of DNA that remained in the comet tail) of the subjects was 1.23% (25th-75th percentile: 0.72-1.64). BLM treatment increased this to 62.4% (25th-75th percentile: 57.8-70.4) at t=0, decreasing to the background level by 30 min. Analysis of 45 subjects showed that the fastest return to the background level occurred in 5 min, whereas the slowest return took approximately 30 min. The early rejoining kinetics of SSBs may show multiple patterns, varying among individuals.

Cigarette smoking, alcohol drinking, and oral cavity and pharyngeal cancer in the Japanese: a population-based cohort study in Japan

The effects of cigarette smoking and alcohol drinking on the incidence of oral cavity and pharyngeal cancer (OCPC) in the Asian population have been poorly understood. To assess the effects of cigarette smoking, alcohol drinking, and facial flushing response on incidence of OCPC, a total of 95 525 middle-aged and older eligible individuals were followed in a large-scale population-based cohort study in Japan from 1990 to 2010. In this study, the person-years of observation were 698 006 in men and 846 813 in women, and a total of 222 cases (men=160, women=62) of OCPC were newly diagnosed during the study period. A multivariate Cox proportional-hazards model was used to assess the incidence risk of OCPC and subsites by cigarette smoking and alcohol drinking. The result showed that cigarette smoking and regular alcohol drinking were associated significantly with the incidence of OCPC in men. Compared with nonsmokers and nondrinkers, current male smokers showed a hazard ratio (HR) of 2.37 [95% confidence interval (CI)=1.51–3.70] and regular male drinkers showed an HR of 1.82 (95% CI=1.20–2.76). Cigarette smoking also increased the risk of OCPC among male heavy alcohol drinkers (HR=4.05, 95% CI=2.31–7.11). However, there was no significant association between facial flushing response and OCPC. In conclusion, cigarette smoking and alcohol drinking are independent risk factors for OCPC and its subsites in the male Japanese population.