[Value of DNA content in comet tail in predicting changes in blood cell counts in workers exposed to benzene]

Objective: To investigate the value of DNA content in comet tail (TailDNA) in predicting the changes in peripheral blood cell counts in workers exposed to benzene. Methods: In 2011, cluster sampling was used to select 150 male workers exposed to benzene in a petrochemical factory. Cubital venous blood and urine samples were collected for routine blood rest, comet assay, and measurement of s-phenylmercapturic acid (SPMA) and urine creatinine. The population was divided into groups according to urinary SPMA or TailDNA, and routine blood test results within 3 years were collected to analyze the changes in blood cell counts. Results: The low-SPMA group had significantly higher white blood cell and neutrophilcounts in all years than the high-SPMA group (P<0.05) . The low-Tail DNA group had a significant increase in platelet count from 2012 to 2014 (P<0.05) , while the high-Tail DNA group had no significant change (P>0.05) . During the 4-year period, the high-TailDNA group had a significantly lower red blood cell count than the low-TailDNA group (P<0.05) . The high-TailDNA group showed a gradual reduction in white blood cell count over time (β=-0.113, P<0.05) , and the low-TailDNA group showed no trend of the reduction in white blood cell count (P>0.05) . Conclusion: TailDNA can be used to predict the changes in blood cell counts in workers exposed to benzene.

[Association and interaction of heat shock proteins B1 gene and tumor-suppressor protein p53 gene with chromosome damage levels among coke oven workers]

Objective: To investigate the association and interaction of heat shock proteins B1(HSPB1)gene rs2868371 and tumor-suppressor protein p53(TP53)gene rs1042522 polymorphisms with chromosome damage levels among coke oven workers. Methods: We recruited 1 333 male workers from a state-run coke oven plant in Wuhan in September-October 2010. Among them, 949 who had worked in coke oven workplaces, including auxiliary facilities and bottom, side, and top ovens, were nominated as coke oven workers(i.e., exposed), and 384 administrative or medical staff whose workplaces were offices were used as controls. General characteristics and 5 ml of venous blood were collected from each participant. The plasma concentrations of benzo[a]pyrene-diolepoxide(BPDE)-albumin adducts and the lymphocytic micronucleus(MN)frequencies for each individual were detected by ELISA and cytokinesis-block micronucleus assay, respectively. Gene polymorphisms were genotyped using TaqMan assays via quantitative PCR(ABI Prism 7900HT), and the corresponding frequency ratios(FR)with 95% confidence intervals(CI)were computed for all assays. Results: In the exposed group, the MN frequencies were higher in HSPB1 rs2868371 GC, CC, and GC+ CC genotype carriers((3.88 ± 2.88)‰,(4.00 ± 2.66)‰, and(3.91 ± 2.83)‰, respectively)than in rs2868371 GG genotype carriers((3.52±2.67)‰; FR=1.10, 1.13, and 1.11; 95% CI: 1.02-1.19, 1.02-1.25, and 1.03-1.19, respectively), and the HSPB1 rs2868371C allele was associated with increased MN frequency(P_trend=0.006). Further, in the exposed group, the MN frequencies were lower in TP53 rs1042522 CG and CG+GG genotype carriers((3.63±2.61)‰ and(3.66±2.61)‰, respectively)than in TP53 rs1042522 CC genotype carriers(3.95±3.06)‰(FR=0.87 and 0.90; 95% CI: 0.83-0.96 and 0.84-0.97, respectively). The effect of gene-gene interaction between HSPB1, rs2868371, and TP53 rs1042522 on MN frequency was significant among coke oven workers(P=0.001). Further stratified analyses showed that the effects of the HSPB1 rs2868371C allele in increasing MN frequencies were robust in subjects aged >40 years(FR=1.07, 95% CI: 1.01-1.12), those working >20 years(FR=1.08, 95% CI: 1.02-1.14), those with BMI ≤24 kg/m²(FR=1.07, 95% CI: 1.01-1.13), drinkers(FR=1.09, 95% CI: 1.02-1.16), and workers with higher BPDE-albumin adduct levels(FR=1.07, 95% CI: 1.01-1.13)(P_trend=0.023, 0.013, 0.029, and 0.020, respectively). The decreasing effect of the TP53 rs1042522 G allele on MN frequencies was robust in subjects aged >40 years(FR=0.94, 95% CI: 0.89-0.99), those with BMI ≤24 kg/m²(FR=0.94, 95% CI: 0.88-0.99), and drinkers(FR=0.94, 95% CI: 0.88-1.00)(P_trend=0.031, 0.023, and 0.038, respectively). In addition, there were interactions between HSPB1 rs2868371 and age and between HSPB1 rs2868371 and working years in terms of MN frequency(P=0.030 and 0.013, respectively). Conclusion: In coke oven workers, the HSPB1 rs2868371 C and TP53 rs1042522 G alleles were associated with increased and decreased chromosome damage levels, respectively, and their interaction effect on chromosome damage levels was significant.