毒性弥漫性甲状腺肿患者外周血淋巴细胞SCE须率的研究

姊妹染色单体交换（SCE）系一条染色体中 两条姊妹染色单体之间同源节段的互换。SCE 可以自发产生,各物种细胞中自发SCE频率 相对比较稳定。但若用诱变剂或致癌剂处理细 胞,则SCE频率可显著提高u1。已经证实,一 些物质的诱变、致癌力与诱发SCE能力之间 存在很高的相关性[=,330目前,国内SCE技术 已用于多种遗传病、肿瘤和病毒性传染病的病 因学研究,以及化学“三致即物质作用机理的研 究［[3,A)。对毒性弥漫性甲状腺肿患者细胞SCE 频率尚未见报道。为了从细胞及亚细胞水平探 索本症的病因．,作者对20例毒性弥漫性甲状腺 肿患者外周血淋巴细胞SCE频率和20例正 常人细胞SCE频率进行了分析研究,现报告 如下。     

不同添加物质对香烟烟雾水溶物引起的蚕豆根尖细胞微核率的影响

本课题研究了不同添加物质对香烟烟雾水溶物引起的蚕豆根尖细胞微核率的影响。结果表明亚硒酸钠、烟酰胺、绿茶浸出物和维生素C均能显著降低由香烟烟雾水溶物引起的微核率,上述物质可能具有减轻吸烟引起的遗传毒性损伤的作用。此外,本文还对上述结果的意义进行了讨论。     

石油作业习惯性流产女性细胞遗传毒性研究

目的:研究石油作业环境对女性习惯性流产的遗传毒性。方法:随机选择习惯性流产的石油作业女性38人和正常的育龄女性20人,检测其外周血淋巴细胞姐妹染色单体互换,记数SCE发生率。结果:观察组的外周血淋巴细胞SCE发生率为8.81±0.35,明显高于对照组(P0.05)。结论:SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标。石油作业环境对女性生育具有遗传毒性。     

石油作业习惯性流产女性细胞遗传毒性研究

目的：研究石油作业环境对女性习惯性流产的遗传毒性。方法：随机选择习惯性流产的石油作业女性38人和正常的育龄女性20人,检测其外周血淋巴细胞姐妹染色单体互换,记数SCE发生率。结果：观察组的外周血淋巴细胞SCE发生率为8．81＋0．35,明显高于对照组（P〈0．05）。结论：SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标。石油作业环境对女性生育具有遗传毒性。     

非诱变剂对姐妹染色单体交换的诱导效应

检测了16种非诱变剂对大麦根端分生细胞姐妹染色单体交换(SCE)的影响及其中9种成份对人外周血淋巴细胞SCE的影响。在大麦细胞中,用高浓度的葡萄糖、氯化钠、维生素、氨基酸及脱氧核糖核苷三磷酸(dNTP)处理均能显著提高SCE频率。维生素、氨基酸和dNTP对人外周血淋巴细胞中的SCE频率也有显著影响。实验结果表明,不只是诱变剂能提高SCE频率,非诱变剂在一定高剂量时也能提高SCE频率。非诱变剂影响SCE具有特殊的S CE增长曲线,SCE频率达一定值后不再随处理浓度的增大而提高。     

昆明山海棠遗传毒性评价——1.致突效应的研究

本文报道了中药昆明山海棠在Ames试验、人外周血淋巴细胞姐妹染色单体互换(SCE)及小鼠骨髓细胞染色体结构畸变分析中的遗传毒性效应。结果发现,昆明山海棠根部水提取物(THH)(200-800mg/皿)及乙醇抽提物(ATH)(100-200mg╱皿)在TA97、TA100均不同程度地诱发突变。THH在人体外周血淋巴细胞中显著诱发SCE(0.313-0.625mg/ml)。在小鼠骨髓细胞染色体结构分析中,THH未表现出明显的染色体断裂效应(2.5-14.3g/kg)。结果暗示,昆明山海棠对人类遗传物质具有潜在威胁,其临床应用应持谨慎态度。     

昆明山海棠遗传毒性评价I.致突效应的研究

本文报道了中药昆明山海棠在Ames试验、人外周血淋巴细胞姐妹染色单体互换（SCE）及小鼠骨髓细胞染色体结构畸变分析中的遗传毒性效应。结果发现,昆明山海棠根部水提取物（THH）(200~800mg/皿)及醇抽提物（ATH）（100~200mg/皿）在TA97、TA100均不同程度地诱发突变。THH在人体外周血淋巴细胞中显著诱发SCE（0.313~0.625mg/ml）。在小鼠骨髓细胞染色体结构分析中,THH未表现出明显的染色体断裂效应（2.5~14.3g/kg）。结果暗示,昆明山海棠对人类遗传物质具有潜在威胁,其临床应用应持谨慎态度。     

2,4,5一三氯苯氧乙酸诱发人体外周血淋巴细胞SCE率的观察

姐妹染色单体互换（简称SCE）技术能灵 敏地检验染色体变化,而人外周血的淋巴细胞 又是直接反映人类体细胞突变和癌变的方便材 料。因此,国内外不少实验室^[1,7,8]以SCE法对 若干人类遗传性疾病和环境中可疑致突变和癌 变物质进行了观察分析,获得了不少新资料。本 文报道了SCE法测试化学除草剂2,4,5一三氯 苯氧乙酸（2,4 , 5-Trichlorophenoxy acetic acid, 简称2,4,5-T）对人体淋巴细胞的遗传效应。     

香烟烟雾水溶物诱发蚕豆根尖细胞微核的研究

本文研究了不同浓度的香烟烟雾水溶物对蚕豆根尖细胞微核的诱变作用,结果表明, 上述水溶物能够引起蚕豆根尖细胞微核率发生敏感性变化,提示蚕豆根尖细胞微核技术可作为一种香烟遗传毒理学检垛方法使用。此外,还对使用该方法的意义以及添加VE对香烟烟雾水溶物微核率的影响进行了讨论。     

敌枯双、敌枯唑对体外培养细胞SCE的影响及其机制

自从BUdR/Giemsa技术用于检查SCE以来,已经用SCE分析法测试了许多化学物质的诱变性和致癌性,大多数促使SCE频率升高的化学物质都是诱变性致癌剂。因此,在遗传毒理学中已把SCE分析法作为诱变剂致癌剂的     

Cytogenetic effects of cigarette smoke condensates in vitro and in vivo

Summary Various cigarette smoke condensates (CSC) were analyzed with respect to the induction of sister-chromatid exchanges (SCE) in human lymphocytes in vitro. CSC from a reference cigarette, from three different tobaccos of the reference cigarette, and from a British cigarette induced similar SCE frequencies. CSC from the reference cigarette did not induce SCE in Chinese hamster bone marrow cells in vivo.     

Synergistic induction of hydroxyl radical-induced DNA single-strand breaks by chromium(VI) compound and cigarette smoke solution

Chromium(VI) compounds and cigarette smoke are known human carcinogens. We found that K2Cr2O7 and cigarette smoke solution synergistically induced DNA single-strand breaks (0.23+/-0.04 breaks per DNA molecule) in pUC118 plasmid DNA. K2Cr2O7 alone or cigarette smoke solution alone induced much less strand breaks (0.03+/-0.01 or 0.07+/-0.02 breaks per DNA molecule, respectively). The synergistic effect was prevented by catalase and by hydroxyl radical scavengers such as deferoxamine, dimethylsulfoxide, d-mannitol, and Tris, but not by superoxide dismutase. Ascorbic acid enhanced the synergism. Glutathione inhibited strand breakage only at high concentrations. Electron spin resonance (ESR) studies using a hydroxyl radical trap demonstrated that hydroxyl radicals were generated when DNA was incubated with K2Cr2O7 and cigarette smoke solution. Hydroxyl radical adduct decreased dose-dependently when strand breakage was prevented by catalase, deferoxamine, dimethylsulfoxide, d-mannitol or Tris, but not significantly by superoxide dismutase. We also used ESR spectroscopy to study the effects of different concentration of ascorbic acid and glutathione. The results showed that hydroxyl radical, which is proposed as a main carcinogenic mechanism for both chromium(VI) compounds and cigarette smoke solution was mainly responsible for the DNA breaks they induced.     

Analysis of sister chromatid exchanges in lymphocytes cultured from 71 healthy men

Sister chromatid exchanges (SCE) were analyzed in peripheral blood lymphocytes from a select group of 71 healthy men, 56 nonsmokers and 15 cigarette smokers. In addition to estimating baseline SCE, data were examined to seek relationships of SCE frequencies to age and smoking. The baseline value of 7.53 SCE per cell from the 56 nonsmokers was within the range (5.60 to 9.10 SCE/cell) reported for other human populations. No relationship was found between the mean SCE frequency per cell and age. However, a significant increase in the SCE mean value was observed in smokers as compared to nonsmokers. The results of this study are compared with those of other reports on SCE effects of age and smoking.Abbreviations BUdR 5-bromo,2-deoxyuridine - SCE sister chromatid exchange     

Sister-chromatid exchange and cell proliferation in cultured lymphocytes of passively and actively smoking restaurant personnel

Sister-chromatid exchange frequencies were measured in peripheral lymphocytes of 12 cigarette smokers, 20 passive smokers, and 14 non-smokers with no regular exposure to tobacco smoke. All active and passive smokers worked as waiters and waitresses in restaurants. The passive smokers showed neither an increased mean SCE value nor an increased number of high SCE frequency cells (HFCs) when compared to non-exposed non-smokers. The incidence of SCEs and HFCs was observed to be elevated (P less than 0.01; P less than 0.05, resp.) among the active smokers. The proliferation rate of lymphocytes in whole blood cultures from the different exposure groups was also studied. The proportion of cells in first mitosis was lower and the mean replication index (RI) higher among the smokers than among non-smoker controls. However, no significant correlation was observed between the individual mean SCE and the replication index.     

Sister-chromatid exchange in highly purified human CD4+ and CD8+ lymphocytes.

Sister-chromatid exchange (SCE) frequencies were determined in human peripheral blood CD₄⁺ and CD₈⁺ T lymphocyte subpopulations which were rapidly and highly purified from pooled T lymphocytes by immunological methods. The purified lymphocytes were stimulated with phytohemagglutinin (PHA) for 4 days. CD₄⁺ lymphocytes showed significantly higher SCE frequencies than autologous CD₈⁺ lymphocytes when measured simultaneously after identical bromodeoxyuridine (BrdU) incubation times. Differences in SCE frequencies between CD₄⁺ and CD₈⁺ lymphocytes were also detected when mitomycin C (MMC) was added to the cultures. Higher SCE frequencies in CD₄⁺ lymphocytes were associated with lower proliferating rate indices (PRI) as compared to autologous CD₈⁺ lymphocytes. Abnormalities in CD₄⁺ T lymphocyte function and number in peripheral blood have been observed in several diseases characterized by immunological disorders. Thus, our data may suggest a link between some immunological disturbances and abnormal SCE frequencies in T lymphocyte subsets.     

Sister-chromatid exchange in highly purified human CD4 and CD8 lymphocytes

Sister-chromatid exchange (SCE) frequencies were determined in human peripheral blood CD₄⁺ and CD₈⁺ T lymphocyte subpopulations which were rapidly and highly purified from pooled T lymphocytes by immunological methods. The purified lymphocytes were stimulated with phytohemagglutinin (PHA) for 4 days. CD₄⁺ lymphocytes showed significantly higher SCE frequencies than autologous CD₈⁺ lymphocytes when measured simultaneously after identical bromodeoxyuridine (BrdU) incubation times. Differences in SCE frequencies between CD₄⁺ and CD₈⁺ lymphocytes were also detected when mitomycin C (MMC) was added to the cultures. Higher SCE frequencies in CD₄⁺ lymphocytes were associated with lower proliferating rate indices (PRI) as compared to autologous CD₈⁺ lymphocytes. Abnormalities in CD₄⁺ T lymphocyte function and number in peripheral blood have been observed in several diseases characterized by immunological disorders. Thus, our data may suggest a link between some immunological disturbances and abnormal SCE frequencies in T lymphocyte subsets.     

Formation of 8-nitroguanine in tobacco cigarette smokers and in tobacco smoke-exposed Wistar rats

Our previous studies have shown that 8-nitroguanine (8-NO(2)-G) could serve as a specific biomarker of DNA damage induced by gaseous nitrogen oxides (NO(x)) exposure. To evaluate the effect of tobacco cigarette smoking on the DNA damage in peripheral lymphocytes of cigarette smoke ones, we randomly collected and determined the level of 8-NO(2)-G in DNA extracted from peripheral lymphocyte of 15 each of light-smoking healthy volunteer (L-S, less than one pack per day), moderate-smoking healthy volunteers (M-S, one to two pack per day for 5-10 years), heavy-smoking healthy volunteers (H-S, over two packs per day for 10 years), lung cancer patients with heavy smoking (cancer H-S) and non-smoking healthy controls. Both of the mean level of the 8-NO(2)-G levels in peripheral lymphocyte (0.90+/-1.0, 1.23+/-1.14, 1.43+/-0.79, 3.62+/-1.38 ng per microg DNA) and serum nitrite (38.99+/-9.58, 46.70+/-9.38, 55.46+/-10.45, 70.1+/-18.54 microM) of L-S, M-S, H-S and cancer H-S groups were higher than that of non-smoking healthy controls (0.02+/-0.04 and 18.96+/-4.31 for 8-NO(2)-G level and serum nitrite, respectively). Furthermore, in animal experiment, a dose-dependent increase in 8-NO(2)-G was observed in rat lung and peripheral lymphocyte DNA of Wistar rats after tobacco cigarette smoke exposure twice a day, for 1 month. The level of 8-NO(2)-G is 0.17+/-0.41, 1.65+/-3.15, 23.50+/-20.75 and 37.58+/-17.55 ng per microg lung DNA for rat exposed with tobacco cigarette smoke from 0, 5, 10, 15 cigarettes per day, respectively. It was also found that count of peripheral lymphocytes and nitrite concentration in serum of rat increased after the tobacco smoke exposure. It is postulated that tobacco cigarette smoking could induce DNA damage (8-NO(2)-G formation) by exo- and endogenous NO(x).     

Vitamin C prevents cigarette smoke induced oxidative damage of proteins and increased proteolysis

Aqueous extract of cigarette smoke (CS) contains some stable oxidants, which oxidize human plasma proteins, bovine serum albumin, amino acid homopolymers, and also cause extensive oxidative degradation of microsomal proteins. Similar observations are made when the aqueous extract of cigarette smoke is replaced by whole phase CS solution or whole phase cigarette smoke. CS-induced microsomal protein degradation is a two step process: (i) oxidation of proteins by the oxidants present in the CS and (ii) rapid proteolytic degradation of the oxidized proteins by proteases present in the microsomes. Using aqueous extract of CS equivalent to that produced from one-twentieth of a cigarette, the observed initial and postcigarette smoke treated values of different parameters of oxidative damage per milligram of microsomal proteins are respectively: 0.24 and 1.74 nmoles for carbonyl formation, 125.4 and 62.8 fluorescence units for tryptophan loss, 10.2 and 33.4 fluorescence units for bityrosine formation, and 58.3 and 12.2 nmoles for loss of protein thiols. When compared with sodium dodecyl sulphate polyacrylamide gel electrophoresis profiles of untreated microsomal proteins, the extent of microsomal protein degradation after treatment with whole phase CS solution or aqueous extract of CS is above 90%. Ascorbate (100 microM) almost completely prevents cigarette smoke-induced protein oxidation and thereby protects the microsomes from subsequent proteolytic degradation. Glutathione is partially effective, but other antioxidants including superoxide dismutase, catalase, vitamin E, probucol, beta-carotene, mannitol, thiourea, and histidine are ineffective. The gas phase cigarette smoke contains unstable reactive oxygen species such as superoxide (O2*-) and hydrogen peroxide (H2O2) that can cause substantial oxidation of pure protein like albumin but is unable to produce significant oxidative damage of microsomal proteins. Gas phase cigarette smoke-induced albumin oxidation is not only inhibited by ascorbate and glutathione but also by superoxide dismutase, catalase and mannitol. The stable oxidants in the cigarette smoke are not present in the tobacco and are apparently produced by the interaction of O2*-/H2O2/OH* of the gas phase with some components of the tar phase during/following the burning of tobacco.     

In vitro studies of biological effects of cigarette smoke condensate: II. Induction of sister-chromatid exchanges in human lymphocytes by weakly acidic,semivolatile constituents

Cigarette smoke condensate is known to enhance the frequency of sister-chromatid exchanges (SCE) in human lymphocytes in vitro and some of the activity has been found in the most volatile part of the particulate phase, the semivolatile fraction. In this study we have investigated the chemical composition and the SCE-inducing activity of the weakly acidic, semivolatile fraction of a cigarette smoke condensate. A number of individual weakly acidic compounds were also tested for their SCE-inducing effects.The weakly acidic fraction was separated by preparative gel chromatography into 11 subfractions (F1–F11). The chemical composition was determined by gas chromatography and gas chromatography-mass spectrometry. Measurements of the effects on SCE in human lymphocytes were used to evaluate the genotoxic effects. All fractions except F11 induced SCE in a dose-dependent way. The most active fraction was F4 which contained mainly alkyl-2-hydroxy-2-cyclopenten-1-ones.The individual compounds to be tested for induction of SCE were selected on the basis of their abundance in the weakly acidic subfractions and on the basis of their occurrence in the environment. Of 23 tested compounds, most of which were alkylphenols, 7 induced SCE, i.e., catechol, 2-(1-propenyl)phenol, cyclotene, maltol, isoeugenol, 2-methoxyphenol (guaiacol) and vanillin. Many of these are important flavor components that occur not only in tobacco and tobacco smoke but also in food, candies, beverages and perfumes.     

Spontaneous sister-chromatid exchange frequencies in human B and T lymphocytes at BrdU borderline concentrations for sister-chromatid differentiation

Human peripheral blood B and T lymphocytes, highly purified by immunologic methods, were supplemented with gamma-irradiated unseparated autologous mononuclear cells to restore helper functions and stimulated with pokeweed mitogen and phytohemagglutinin, respectively. Spontaneous sister-chromatid exchange (SCE) frequencies were investigated in proliferating B and T lymphocyte cultures labeled with the cell-type-specific borderline concentrations of 5-bromodeoxyuridine (BrdU) for sister-chromatid differentiation (SCD). B lymphocytes from 6 different donors showed mean values of 3.28-3.72 SCE events/cell. In T lymphocytes, mean values of 6.30-7.28 SCEs/cell were observed. The differences between the SCE distributions of the cell populations are highly significant. The results show that the differences in the spontaneous SCE frequencies between human B and T lymphocytes were not due to a difference in the uptake of BrdU.