苯乙烯-DNA加合特性的研究

目的 研究苯乙烯的DNA加合特性。方法 采用紫外光谱移动法测定苯乙烯－7，8－氧化物（SO）、苯乙烯、苯乙醇酸（MA）、苯乙醛酸（PGA）、苯乙烯巯基尿酸（UMA）和DNA的加合反应；以^32P后标记法研究SO－DNA加合物；以气相色谱－质谱、核磁共振研究SO－DAN加合物的结构。结果 苯乙烯、MA、PGA和UMA不与DNA发生加合反应；SO分别在DNA脱氧鸟苷碱基上的O^6位、N^2位形成6种加合物。结论 苯乙烯进入机体后，通过其活性中间代谢物SO与DNA起加合作用，SO攻击DNA脱氧鸟苷碱基上的O^6位、N^2位形成加合物，如果在细胞复制前所形成的DNA加合物没有被修复或者被错误修复的话，就有可能导致基因突变，产生化学损伤。苯乙烯的其他代谢物未见此效应。     

巴豆醛-DNA加合特性的研究

目的 探讨巴豆醛和DNA加合特性,寻找优势反应核苷酸,初步确定对DNA损伤机制.方法 采用体外测试系统,应用高效液相色谱法对巴豆醛与4种单脱氧核苷酸的加合反应、加合物键型、反应级数进行研究.结果 经高效液相色谱仪(HPLC)分离检测,巴豆醛与脱氧鸟苷酸反应,确定了巴豆醛与4种单脱氧核苷酸结合的优势反应核苷酸.结论 巴豆醛能够与DNA的脱氧鸟苷酸结合而体现遗传特性,鸟苷的N2位可能是共价加合的位点.     

苯醌-脱氧鸟苷酸加合物的结构及化学特性初步研究

目的 测定苯醌(BQ)与脱氧鸟苷酸(dGMP)反应形成的加合物结构与化学特性。方法 高效液相色谱—质谱联机技术及紫外分光光度法。结果 苯醌与脱氧鸟苷酸反应形成两种可检测的加台物Ad1和Ad2，质谱显示Ad1的分子量为437，在不同pH条件下的特征紫外吸收光谱及结合键类型测定结果表明，Ad1为BQ与dGMP共价结合而成，推测结合位点在dGMP的N—1和N^2位，分子式为C16H16O8N5P。BQ与小牛胸腺DNA反应水解产物经高效液相色谱(HPLC)分离同样检出了与Ad1具有相同保留时间的化合物。Ad2分子量为241，其分子式为C11H702N5，可能是由BQ进攻dGMP的N—9位并脱掉糖基所得。结论 苯醌可在体外试管反应条件下形成DNA加合物，其中一种主要的加合物结构为(3’-经基)—1，N^2—苯乙烯基—2’—脱氧鸟苷—5’—磷酸。     

三种醛类化合物-DNA加合特性的研究

目的 探讨甲醛、乙醛和丙烯醛对DNA的损伤机制.方法 采用体外测试系统,应用高效液相色谱法(HPLC)对甲醛、乙醛、丙烯醛及其在人体内的代谢产物甲酸、乙酸、羟丙基巯基尿酸与4种单脱氧核苷酸的加合反应进行研究.结果 经HPLC分离检测,甲醛、醋醛与脱氧鸟苷酸发生加合反应,而丙烯醛、甲酸、醋酸和羟丙基巯基尿酸难以与脱氧鸟苷酸发生加合反应或加合物产量过低,初步确定了甲醛、乙醛与4种单脱氧核苷酸结合的优势反应核苷酸.结论 甲醛、乙醛能够与DNA的脱氧鸟苷酸结合而体现遗传特性.     

职业接触苯乙烯的生物限值研究

目的：研究职业接触苯乙烯的生物限值。方法：高效液相色谱法测定苯乙烯作业工人班前、班后尿中苯乙醛酸（PGA）和苯乙醇酸（MA）的含量，监测工人8h苯乙烯的接触水平，同时研究两者的相关性。结果：尿中的PGA和MA浓度与苯乙烯的接触量有明显的剂量－反应关系。根据作业场所空气中苯乙烯的国家卫生标准，按回归方程推导出职业接触苯乙烯的生物限值。结论：对职业接触苯乙烯的生物限值提出的推荐值：工作班末MA为220mmol/mol肌酐或300mg/g肌酐，下一班前为88mmol/mol肌酐或120mg/g肌酐；PGA班末为7mmol/mol肌酐或100mg/g肌酐，下一班前为30mmol/mol肌酐或40mg/g肌酐。     

BPDE—DNA加合物体外生成实验研究

目的：探讨体外合成苯并（a）芘与DNA形成加合物的条件.方法：以一定比例混合苯并（a）芘丙酮溶液、DNA溶液、S9混合液、于37℃孵育24 h后,紫外分光光度计扫描DNA图谱,得出DNA结构改变的信息;同时用HPLC检测反应体系中的苯并（a）芘含量、苯并（a）芘代谢物及DNA加合物酸水解后的产物.确定BPDE-DNA加合物生成,质谱验证生成物的结构.结果：反应后DNA紫外最大吸收峰红移;HPLC检测发现孵育后反应体系中苯并（a）芘含量降低,反应管有新的物质生成;质谱分析生成物的分子量同于目标产物.结论：一定条件下体外可合成苯并（a）芘-DNA加合物.     

苯乙烯遗传损伤研究进展

苯乙烯常温下为无色透明、具有芳香气味的液体,是合成橡胶和塑料的重要单体之一.因其主要中间代谢产物苯乙烯-7,8-氧化物(Styrene-7,8 -oxide,SO)为直接致癌物,国际癌症研究机构(IARC)将其列为G2B组.苯乙烯进入人体后,在肝混合氧化酶的作用下主要被氧化为SO,SO主要代谢过程为:①经P450酶系作用,在谷胱甘肽-S-转移酶的作用下,形成谷胱甘肽结合物,随后在肾脏及胰腺中γ-谷氨酰转肽酶作用下,断裂其谷氨酰基,继而在肝脏及肾脏中的半胱氨酰甘氨酸酶及氨肽酶的共同催化下,成为半胱氨酸结合物,随后在N-乙酰转移酶的催化下,生成苯乙烯巯基尿酸从尿中排出;②经P450酶系作用,在环氧化物水解酶作用下转变为苯乙烯乙二醇,并继续氧化为苯乙醇酸(Mandelic acid,MA)和苯乙醛酸,随尿排出,当接触高浓度苯乙烯时,部分MA还会转化成非特异性马尿酸,随尿排出;③经P488酶系作用,与DNA发生反应,生成DNA加合物或引起DNA链断裂,从而引发生物学效应[1].     

紫外光谱法测定混配农药的DNA加合作用

目的 研究混配农药的DNA加合作用。方法 采用紫外光谱移动法研究农药的DNA加合作用。结果 农药马拉硫磷、呋喃丹、氯氰菊本及其两两混配农药均可引起小牛胸腺DNA紫外光谱的改变。结论 农药马拉硫磷、呋喃丹、氯氰菊酯及其两两混配 经进入机体后，有与DNA形成加 的，如果在细胞复制前所形成的DNA加合物没有被修复或者被错误修复的活，则有可能导致基因突变，从而产生化学损伤。     

苯乙烯作业工人染色体畸变率与尿中代谢物相关性研究

目的　研究苯乙烯作业工人染色体畸变率与尿中代谢物苯乙醛酸 (PGA)、苯乙醇酸 (MA )浓度的关系。方法　对 10 0名接触苯乙烯的工人和 10 0名非苯乙烯作业的工人进行流行病学调查 ,测其班后尿中PGA、MA浓度 ,检测外周血淋巴细胞的染色体畸变率。结果　苯乙烯在一定浓度下可造成作业工人染色体畸变率增加 ,且经单因素分析 ,班后尿中MA +PGA浓度、工龄等因素与工人的染色体畸变率相关。结论　苯乙烯对接触者的染色体具有损伤作用 ,且与班后尿中MA +PGA浓度有很好的相关性。建议班后尿中MA +PGA浓度的卫生标准应低于 (0 4 4 2± 0 0 5 6 )g/L。     

不同膳食硒水平对甲基苄基亚硝胺（NMBzA）诱发大鼠食道上皮细胞DNA烷基化和

本文报道了硒对NMBzA诱发大鼠食道上皮细胞DNA加合物的形成，DNA加合物修复酶（甲基转移酶）的活性以及-cmyc的基因表达的影响，一次腹腔注射NMBzA 2.5mg/Kg体重，6小时后测定产食上皮细胞中O6－甲基脱氧鸟嘌呤核甙酸（O6－MedGua)和N7－甲基脱氧鸟嘌呤核甙酸（N7－MedGua)的含量，结果表明饲料中不同硒含量对DNA加合物无明显影响；对O6－MedGua DNA甲基转移酶活性也无明显作用，给大鼠每周一次灌胃NMBzA 3mg/kg体重，共8周诱发大鼠食道上皮细胞c-myc基因表达，结果膳食缺硒（＜0．02ppm)和补硒（2ppm)对 c-myc基因表达亦无影响.     

苯乙烯生物标志物的研究

目的 研究苯乙烯的生物标志物，为苯乙烯的生物监测提供理论依据。方法 采用高效液相色谱法对苯乙醇酸(MA)、苯乙醛酸(PGA)、苯乙烯巯基尿酸(MUA)进行监浏。结果 晨尿中MA、PGA、MUA和苯乙烯接触浓度间相关关系分别为y＝2．58x 70．82，y＝1．66. 37．42，y＝0．05x 0．555;班末尿中MA、PGA、MUA和苯乙烯接触浓度间相关关系分别为y＝1．85x 89．02，y=1．33x 4．32，y＝0．04x |0．68，均呈良好的相关性。结论 晨尿及班末尿中的MA、PGA、MUA测定均可作为苯乙烯的生物监测指标。     

Albumin and hemoglobin adducts as biomarkers of exposure to styrene in fiberglass-reinforced-plastics workers

Objective: The purpose of this work was to compare levels of styrene-7,8-oxide (SO) adducts of albumin (Alb) and hemoglobin (Hb) with those of two urinary metabolites of styrene, mandelic acid (MA) and phenylglyoxylic acid (PGA), among workers exposed to styrene in the reinforced-plastics industry and in unexposed subjects. We also wished to determine whether cigarette smoking influenced adduct levels among these subjects. Methods: A group of 22 male workers was selected on basis of an expectedly high level of exposure to styrene, and a group of 15 controls was selected from hospital blood donors and hospital staff. In the exposed group, MA and PGA were quantified by high-performance liquid chromatography (HPLC) analysis of urine samples collected prior to the work shift. The SO adducts were cleaved from cysteine residues by reaction with Raney nickel to give 1-phenylethanol (1-PE) and 2-phenylethanol (2-PE), which, after derivatization, were measured using gas chromatography-mass spectrometry (GC-MS) in the negative-chemical-ionization (NCI) mode. Results: The estimated mean levels of MA and MA+PGA were 74 and 159 mg/g creatinine, respectively. Using the levels of urinary metabolites, an average styrene concentration of about 100 mg/m³ in the workplace air was estimated. The mean levels of 2-PE and 1-PE adducts in exposed workers were 2.84 and 0.60 nmol/g Alb and 5.44 and 0.43 nmol/g Hb, respectively. When subjects were stratified by level of urinary metabolites [zero (controls), low-level exposure (MA+PGA ≤159 mg/g creatinine), and high-level exposure (MA+PGA> 159 mg/g creatinine)] and smoking status (smokers versus nonsmokers), a difference in Alb adduct levels was found among the groups (2-PE P=0.002, 1-PE P=0.052). The difference in 2-PE-Alb levels was related to exposure category, to smoking status, and to their interaction. Correlations at or near a 0.05 level of significance were observed among the workers (n=22) between individual levels of SO-protein adducts and MA+PGA (2-PE Alb, r=0.54, 2-PE Hb, r=0.40). Conclusion: Our data suggest that only exposure to relatively high levels of styrene allows a clear relationship to be detected between styrene exposure and SO adducts, due in part to the effects of cigarette consumption and to the high background levels of these adducts observed in unexposed subjects. Received: 3 February 1997 / Accepted: 9 June 1997     

体外甲基丙烯酸环氧丙酯-DNA加合物的研究

目的 探讨新诱变剂甲基丙烯酸环氧丙酯（ＧＭＡ）与ＤＮＡ形成加合物的类型和特性。方法 在体外条件下,dＡＭＰ、dＣＭＰ、dＧＭＰ、dＴＭＰ及小牛胸腺ＤＮＡ与ＧＭＡ发生反应,反应产物经紫外光谱、反相高效液相色谱（ＲＰ－ＨＰＬＣ）和质谱先进方法分析。结果 ＧＭＡ能与dＡＭＰ、dＣＭＰ、dＧＭＰ及小牛胸腺ＤＮＡ形成专一性共价结合。已 被证实１捉ＧＭＡ－ＤＮＡ加合物为Ｎ３－甲基丙烯酸－２羟丙－基－脱氧胞嘧啶核苷一磷     

Biological monitoring of exposure to low concentrations of styrene

A field study was conducted on 39 male workers exposed to styrene at concentrations below 40 ppm (time weighted average, TWA). Analyses were carried out on environmental air, exhaled air, blood, urine, and two major urinary metabolites of styrene: mandelic acid (MA) and phenylglycoxylic acid (PGA). Head space gas chromatography (GC) with a flame ionization detector (FID) was used for determination of styrene in blood and urine. Postexposure exhaled air was analyzed using capillary GC. Environmental styrene exposure was measured by personal sampling using carbon cloth personal samplers. Urinary metabolites of styrene were determined by high pressure liquid chromatograph (HPLC). When the end-of-shift breath, blood, and urine styrene levels were compared with environmental TWA values, blood styrene correlated best with styrene in air (r = 0.87), followed by breath styrene (r = 0.76). Poor correlation (r = 0.24) was observed between environmental styrene exposure and urine styrene. When styrene metabolites were compared with environmental styrene, the sum of urinary MA and PGA correlated better with styrene in air than MA or PGA alone. The correlations between urinary metabolites and environmental styrene improved when corrected for the specific gravity of urine. Even better correlations were observed when the urinary metabolites were corrected for creatinine. The correlation coefficients for environmental styrene and end-of-shift MA, PGA, and MA + PGA were 0.83, 0.84, and 0.86, respectively. The correlation coefficients between environmental styrene and next morning urinary metabolites fell to 0.47, 0.61, and 0.65 for MA, PGA, and MA + PGA, respectively. These results suggest that determination of the total MA and PGA in urine samples is preferred than separate measurements of MA or PGA. The good correlation between environmental exposure and styrene in the exhaled air also suggests that breath styrene level can be a useful indicator for low level styrene exposure, as the method is specific, noninvasive, and rapid. Urinary styrene seems to be a less reliable indicator for low level styrene exposure. © 1994 Wiley-Liss, Inc.     

Human exposure to styrene

Summary An industrial hygiene study of 10 glassfiber reinforced polyester plants (including 90 workers) was undertaken to investigate the styrene exposure in this industry and to estimate biological limit values (BLV's) for the urinary metabolites of styrene: mandelic (MA) and phenylglyoxylic acids (PGA). Time weighted average (TWA) styrene exposures were found ranging from 2 to 200 ppm. The urinary elimination of metabolites correlated well with exposure and the BLV's corresponding to an 8-h exposure at 100 ppm were consistent with earlier laboratory findings (end-of-shift sample: MA 1640, PGA 510, MA + PGA 2150; next-morning sample: MA 330, PGA 330, MA + PGA 660 mg/g creat.). Total metabolites (MA + PGA) in the next-morning sample or mandelic acid in the end-of-shift sample are recommended for routine monitoring of exposure to styrene. The study revealed the need for further research on how to reduce styrene exposure in this industry.     

苯乙烯对大鼠不同脑区多巴胺递质含量及单胺氧化酶活性的影响

目的观察苯乙烯在不同染毒期限和染毒剂量下对大鼠神经系统多巴胺递质含量及单胺氧化酶活性的影响。方法大鼠随机分为5组,每组12只动物,雌雄各半。苯乙烯急性染毒剂量为600mg/kg,亚急性染毒剂量为150~600mg/kg,恢复组在苯乙烯染毒后正常饲养3周,L-dopa组在苯乙烯染毒同时腹腔注射600mg/kgbw的L-dopa。方法监测动物尿中苯乙烯代谢物苯乙醇酸(MA)和苯乙醛酸(PGA)的含量作为苯乙烯染毒的内剂量,测定苯乙烯染毒大鼠不同脑区多巴胺(DA)含量及参与多巴胺代谢的单胺氧化酶(MAO)活性的变化。结果尿中的PGA和MA含量与染毒剂量均呈正相关,由于存在一定的环境本底,MA比PGA在作为苯乙烯染毒内剂量的指标上更有代表性。视网膜、垂体和纹状体中的DA含量在苯乙烯染毒下显著降低,垂体中的MAO活性增加,而纹状体和视网膜中的MAO活性减小。结论苯乙烯可以通过多巴胺通路产生对机体的神经损伤。     

Relation between colour vision loss and occupational styrene exposure level

Aims: To investigate the relation between colour vision loss and the exposure level of styrene. Exposure level included the current exposure concentration, past cumulative exposure, and the maximum exposure level in the past.

Methods: Colour vision was examined by the Lanthony desaturated panel D-15 test for 76 subjects exposed to styrene in a fibreglass reinforced plastics boat plant (as an exposed group) and 102 non-exposed subjects (as a control group). The current exposure level was expressed by the concentration of atmospheric styrene and end shift urinary mandelic acid (MA) and phenylglyoxylic acid (PGA) levels. The individual cumulative exposure index (CEI) was calculated, based on the exposure frequency and urinary MA concentrations measured for the past eight years.

Results: The Colour Confusion Index (CCI) of the exposed group showed a significant difference from the age matched controls. However, only a slight significant relation was found between CCI and the concentration of urinary MA plus PGA. In this study, the exposed group was further divided into two subgroups (as sub-MA+PGA groups) by the median of urinary MA plus PGA of each subject. The dividing line between the subgroups was 0.24 g/g creatinine, which was equivalent to an atmospheric concentration of styrene of about 10 ppm. The CCI values of both the sub-MA+PGA groups were significantly higher than that of the control group. The relation between CCI value and the maximum exposure concentration in the past eight years was examined. It was found that the CCI values of the group with the maximum exposure concentration of styrene over 50 ppm were significantly higher than that of the other groups.

Conclusions: Exposure to styrene would impair colour vision even if the exposure concentration was lower than 10 ppm. Furthermore, if the maximum concentration of styrene exposure transiently exceeded 50 ppm in the past, the styrene related damage might remain. Thus, the safe limit of exposure to styrene and the relation between exposure to styrene and the degree of damage to ocular structure, retina, optic nerve, and brain need to be re-examined.

     

Biological monitoring of styrene exposure and possible interference of acetone co-exposure

 The object of this study is the evaluation of some of the toxicokinetic effects of exposure to low concentrations of styrene, and the possible influence of simultaneous exposure to acetone. To this end we studied 19 workmen simultaneously exposed to both solvents. During a week of 4-h work shifts, the workmen underwent daily personal environmental monitoring and the collection of urine samples, at both the beginning and the end of the work period, for the determination of mandelic acid (MA) and phenylglyoxylic acid (PGA). The presence of the solvents in the atmosphere was evaluated using passive personal monitoring and gas chromatography. Average exposure to styrene and acetone were respectively 72.2 mg/m³ and 225.7 mg/m³. MA and PGA were quantified by high-performance liquid chromatography (HPLC). The daily urinary concentration averages, both at commencement and at the end of work shifts, of both the metabolites studied and of the sum of the two, were in statistically significant linear correlation with the average daily styrene exposure. Concentrations of MA and PGA in urine samples collected at the start of the work shift averaged 61.5 mg/g creatinine and 45.2 mg/g creatinine respectively, representing 41% and 72% of those at the end of the work shift which were 148.3 and 62.6 mg/g creatinine, respectively. With equal exposure to styrene, the average urinary concentrations of MA and PGA at both the beginning and end of the work shift increased significantly (P<0.001) during the working week. Moreover, we found that with equal exposure to styrene, urinary excretion of MA, PGA and MA+PGA at the end of the shift was inversely correlated with the intensity of acetone exposure (r=0.4659, 0.3410 and 0.4542 respectively, P<0.001). In conclusion, these results express slower urinary kinetics of styrene metabolites than is usually described in the literature, and favor a tendency to accumulate MA and PGA in the organism as a consequence of the retardation of urinary excretion kinetics. Acetone apparently represents one of the determining factors in this interference. Received: 3 July 1996/Accepted: 20 September 1996