ABSTRACT
OBJECTIVE: To explore the effects of vinyl chloride monomer( VCM) on the expression of mir-122 in the liver tissue and serum of rat. METHODS: Specific pathogen free adult male SD rats were randomly divided into 4 groups with 24 rats in each group: the control group,the low-,medium- and high-dose groups. The 4 groups were intraperitoneally injected with VCM exposure levels at 0,5,25 and 125 mg / kg body weight 3 times per week,respectively. Eight rats per group were randomly selected and sacrificed after 6,8 and 12 weeks. Small RNA( < 200 nt) in the liver tissue and total RNA in the serum were isolated and purified. Real-time fluorescent quantitative polymease chain reaction technique was used to detect their expressions of mir-122. RESULTS: Compared with the control group and the low-dose group at the same time points,the relative expressions of mir-122 in the liver tissue of rats in the medium- and high-dose groups were significantly increased after exposed to VCM for 6 weeks( P < 0. 05),and then were significantly decreased after exposed to VCM for 12 weeks( P < 0. 05). The relative expressions of mir-122 in the liver tissue of rats in the medium- and highdose groups were decreased with VCM exposure time( P < 0. 05). Compared with the control group at the same time points,the relative expressions of mir-122 in serum of rats in the three dose groups were significantly increased after being exposed to VCM for 8 weeks( P < 0. 05),and then were significantly decreased after being exposed to VCM for 12 weeks(P < 0. 05). Among the three dose groups,the relative expressions of mir-122 in serum of rats after 12-week exposure were lower than those after 6-week and 8-week exposure in the same group respectively( P < 0. 05). CONCLUSION:s The VCM exposure significantly changes the expression of mir-122 in the liver tissue and serum of rat,which suggested that mir-122 may be one of the effect biomarkers for VCM exposure.
ABSTRACT
OBJECTIVES: The study was performed to investigate the changes of urinary thiodiglycolic acid (TDGA) concentration in workers exposed to vinyl chloride monomer (VCM) according to the time of sampling urine. METHODS: The personal exposure to airborne VCM was assessed and urinary TDGA concentration was sampled in 31 workers employed in a VCM and polyvinyl chloride (PVC) manufacturing factory. Urinary TDGA was sampled three times: before the start of the shift after 3 days off (TDGA1), after the end of the first-day shift (TDGA2) and before starting the following day shift after completing the oneday shift (TDGA3). Urinary TDGA in 30 workers who had not been exposed to airborne VCM was sampled after the end of the shift. A gas chromatography/pulsed flame photometric detector (GC/PFPD) was utilized to analyze TDGA concentration in urine after the urine was methylated with trimethylsilyldiazomethane(2.0M in diethyl ether). RESULTS: The creatinine level was 0.179+/-0.271 mg/g in the control workers and 0.218+/-0.443 mg/g in the workers before the start of the shift after 3 days off (TDGA1), showing no significant difference (p=0.7035). Urine samples were compared according to sampling time in order to investigate the change of urinary TDGA concentration in the case of continuous exposure to airborne VCM. In VCM-exposed workers, urinary creatinine concentration was 0.434+/-0.623 mg/g in TDGA2 and 0.767+/-1.056 mg/g in TDGA3, which indicated a gradual but significant increase (p=0.024). In terms of the statistical correlation between airborne VCM and urinary TDGA to evaluate exposure dose per day, of the three urinary TDGA concentrations, TDGA3 showed the highest degree of regression (R(2)=0.4215) with 8h-TWA airborne VCM concentration. CONCLUSION: Based on this result, the excretion half-life of urinary TDGA was assumed to be less than 3 days, because the concentration of urinary TDGA at 3 days after exposure to airborne VCM was decreased to the level of urinary TDGA concentration in the control workers. The concentration of urinary TDGA increased in the case of continuous shift, due to the accumulation of residual metabolites of TDGA. It was considered that TDGA3 can be applied as a useful biological index to evaluate the exposure dose of airborne VCM during one day because TDGA3 showed the highest correlation with the exposure dose of airborne VCM in the previous shift day.
Subject(s)
Humans , Creatinine , Half-Life , Polyvinyl Chloride , Vinyl ChlorideABSTRACT
OBJECTIVES: It is the objective of this research to identify the variation of thiodiglycolic acid (TdGA) in urine with vinyl chloride monomer (VCM) exposure levels through methylation. METHODS: After rats were exposed to vinyl chloride monomer of 4 levels, 0 mg/m3, 50 mg /m3, 150 mg/m3, 500 mg/m3, respectively, of which urine was sampled in each sampling time of 0 hour, 2 hours, 4 hours, 8 hours, 16 hours, 24 hours, 36 hours, 48 hours. After urine had been methylated with diazomethane in the preliminary experiment and the peak of 146 m/z had been verified, the main experiment was done. RESULTS: In the variation of TdGA with sampling times, concentration of TdGA increased rapidly in 4 hours and then decreased after 8 hours. When the variation of urinary .TdGA concentration in urine according to exposure level of VCM was verified through Kruskal-Wallis statistical method at each sampling time, the significant increment with the exposure levels at 2 hours, 4 hours, 8 hours after exposure was clarified. CONCLUSION: TdGA concentration in urine with increment of VCM exposure level increased, especially significantly at 2 hours, 4 hours, 8 hours of sampling time.