镉和氯化汞致体细胞hprt基因位点突变的作用和突变频率的研究

目的 了解镉和汞对细胞hprt基因位点的影响，探讨化学诱变物致机体损伤早期检测的敏感指标。方法 采用多核细胞法研究化学诱变物氯化汞和镉对人血淋巴细胞hprt基因位点的影响及突变频率。结果 氯化汞可诱发大鼠血淋巴细胞hprt基因位点突变，突变频率随着染毒浓度的增加而升高，突变频率Y↑^（10^-3)与氯化汞浓度C（mg/kg)之间拟合成Y↑^=0.0423C 1.0463的直线回归方程，不同浓度金属镉也能致hprt基因突变，镉浓度与突变频率之间有剂量反应关系。结论 氯化汞和镉对血淋巴细胞hprt基因位点及突变频率有影响，hprt基因突变频率可作为接触环境致突变物人群检测的敏感指标。     

醋酸铅体外诱发人外周血淋巴细胞HPRT基因位点突变的研究

目的 了解醋酸铅对人外周血淋巴细胞HPRT基因位点的影响,以探讨铅的致突变性。方法 采用多核细胞法体外研究醋酸铅对人外周血淋巴细胞HPRT基因位点的影响及突变频率。结果 0．25mmol/L醋酸铅即可诱发人外周血淋巴细胞HPRT基因位点突变,且突变频率随着染毒浓度的增加而升高,突变频率Y(10^-3)与醋酸铅浓度C(mmol/L)之间存在一定的剂量-效应关系,直线方程分别为：Y=1．0566 0．1661C(r=0．9582)和Y=1．0762 0．1987C(r=0．9434)。结论 在一定条件下,醋酸铅对人外周血淋巴细胞HPRT基因位点及突变频率有影响,HPRT基因突变频率可望成为接触环境致突变物人群检测的敏感指标。     

氯化镉对V79细胞hprt基因位点突变频率的影响及锌的作用

目的了解氯化镉（CdCl2）对中国仓鼠肺成纤维细胞（V79细胞）hprt基因位点突变频率的影响及锌的拮抗作用。探讨镉的遗传毒性机制。方法采用克隆形成法了解CdCl2对V79细胞的慢性毒性作用;在此基础上采用克隆法研究不同浓度CACl2对V79细胞hprt基因位点突变频率的影响,并采用生理浓度的氯化锌（ZnCl2）与CdCl2同时作用后,观察锌对于镉致突变效应的影响。同时观察不同浓度CdCl2预先染毒24h后,对过氧化氢（H。（）。）所致hprt基因位点突变效应的影响及锌的拮抗作用。结果克隆形成实验中,CdCl2对V79细胞的毒性随染毒浓度增加而增高,呈线性关系;CdCl2可以引起V79细胞hprt基因位点突变频率增加,在0．1和8μmol／L染毒浓度处分别有两个峰值。CdCl2与H2O2联合作用表现为协同效应。ZnCl2可以拮抗这种效应。结论在本实验条件下,CdCl2可以导致V79细胞hprt基因位点突变,并可使其他致突变物的致突变性增强,而锌瓦‘以拮抗此效应。     

氯化镉诱发大鼠血淋巴细胞HPRT基因位点突变频率的研究

目的了解氯化镉对大鼠外周血淋巴细胞HPRT基因位点的影响,寻找化学诱变物致机体损伤的早期检测的指标.方法采用多核细胞法研究化学诱变物氯化镉对大鼠血淋巴细胞HPRT基因位点的影响及突变频率.结果氯化镉可诱发大鼠血淋巴细胞HPRT基因位点突变,突变频率随着染毒浓度的增加而升高,突变频率Y(×10-3)与氯化镉浓度C(mg/kg)之间存在剂量-效应关系.结论氯化镉对大鼠血淋巴细胞HPRT基因位点及突变频率有影响,HPRT基因突变频率检测有望作为早期的效应标志物,用于接触环境致突变物人群的分子流行病学调查.     

晚期混合裂变产物内照射诱发体细胞HPRT基因位点突变率与剂量率关系的研究

运用多核细胞法及胞质分裂阻断微核（CBMN）法对5组Wistar雄性大鼠外周血淋巴细胞HPRT基因位点突变频率及微核进行检测。实验组注射不同放射性比活度的晚期混合裂变产物，在达到累积剂量近似相等（约4.66cSv）时心脏穿刺取血。结果显示，在总累积剂量近似相等条件下，HPRT位点突变频率、微核细胞率、微核率均随剂量率的增加而增加，4个剂量率点间的HPRT位点突变频率、微核细胞率和微核率总体上均有显著差异（P＜0．01）。HPRT基因位点突变频率、微校率与剂量率之间的关系可分别用函数Y=a＋blnX表示。HPRT位点突变频率与微核率间存在线性相关。     

茶多酚对~(60)Coγ射线诱发小鼠外周血淋巴细胞Hprt基因突变的影响

目的探讨茶多酚(tea polyphenols,TP)对~(60)Coγ射线诱发小鼠外周血淋巴细胞Hprt基因突变的影响。方法小鼠分为正常对照组、照射组(1、2、4、8 Gy照射),TP保护组(高、中、低剂量组分别于8 Gy照射后TP灌胃725 mg/kg、145 mg/kg、29 mg/kg),每组6只,照射后当日给药,14天后心脏取血,应用多核细胞法检测Hprt基因位点突变频率。结果 0~8 Gy~(60)Coγ射线可诱发小鼠淋巴细胞Hprt基因发生突变,且随照射剂量增加突变频率随之增加,突变频率Y(10-3)与照射剂量D(Gy)间可拟合为Y=1.1795+0.6135D。TP保护组Hprt基因突变率与照射组细胞Hprt基因突变率相比明显下降(P0.01)。结论茶多酚对~(60)Coγ射线所诱发的小鼠外周血淋巴细胞Hprt基因突变具有保护效应。     

晚期混合裂变产物内照射诱发体细胞HPRT基因位点突变率与剂 …

运用多核细胞法及胞质分裂阻断微核（ＣＢＭＮ）法对５组Ｗｉｓｔａｒ雄性大鼠外周血淋巴细胞ＨＰＲＴ基因位点突变频率及微核进行检测。实验组注射不同放射性比活度的晚期混合裂变产物，在达到累积剂量近似相等（约４．６６ｃＳｖ）时心脏穿刺取血。结果显示，在总累积剂量近似相等条件下，ＨＰＲＴ位点突变频率、微核细胞率、微核率均随剂量率的增加而增加，４个剂量率点间的ＨＲＰＴ位点突变频率、微核细胞率和微核率总体上均有显     

蒙古族与回族人群甘露糖结合凝集素基因启动子单体型分析

目的分析内蒙古自治区蒙古族人群和宁夏回族自治区回族人群甘露糖结合凝集素（MBL）基因启动子区和5’端非翻译区的单核苷酸多态性（SNP）及其单体基因型。方法MBL基因SNP分析采用序列分析法；遗传学分析采用SHEsis软件。结果79例蒙古族人群中启动子-550位点H／H、H／L和L／L型分别占38．0％、45．6％和16．5％，等位基因变异频率为0．392；-221位点Y／Y和X／Y型分别占81．0％和19．0％，等位基因突变频率为0．095。69例回族人群中启动子一550位点H／H、H／L和L／L型分别占36．2％、44．9％和18．8％，等位基因变异频率为0．413；-221位点Y／Y和X／Y型分别占75．4％和24．6％，等位基因突变频率为0．123。启动子单体型有HYP、LYP和LXP3种，在蒙古族人群中的频率分别为0．608、0．297和0．095；回族人群中的频率分别为0．587、0．290和0．123。所有样本5’端非翻译区＋4位点均无突变即均为P型。蒙古族和回族-550位点和-221位点的变异频率差异无统计学意义（χ^2-550=0．131，P=0．718；χ^2-221=0．610，P=0．435）。结论（1）本研究中蒙古族和回族人群启动子单体型仅HYP、LYP和LXP3种。（2）启动子区-550位点的变异频率较高，-221位点变异频率较低，＋4位点无SNP发现。两组人群上述位点的变异频率差异无统计学意义。     

健康成人和放射工作者体细胞HPRT基因位点突变率的检测和比较

目的为了解健康成人和放射工作者体细胞ＨＰＲＴ基因位点突变率。方法应用人外周血淋巴细胞抗６－ＴＧ分析技术检测了３０例健康成人和３０例放射工作者体细胞ＨＰＲＴ位点突变频率。结果健康成人ＨＰＲＴ基因位点突变频率均值为０１６２８×１０－３,变化范围为０１３００×１０－４～０２９０３×１０－３,放射工作ＨＰＲＴ基因位点的突变频率均值为０２２２５×１０－３,变化范围为０３３７×１０－４～０４７８×１０－３。ｔ检验Ｐ＜００５,两者差异显著。从检测结果亦可看出,随着放射工龄的延长,ＨＰＲＴ基因位点突变频率也随之增加。结论体细胞ＨＰＲＴ基因位点突变频率可作为各种有害因素对机体遗传损伤的生物标识物之一。     

长春新碱诱发的人淋巴细胞遗传损伤的体外试验方法评价

目的 用3个遗传终点来评价人外周血淋巴细胞暴露于不同剂量长春新碱（VCR）后的遗传损伤。方法 外周血来自男女2名助血员，用终浓度为0．00（溶剂对照）、0．01、0．02、0．04、0．08μg／ml的VCR染毒24h，再用微核试验、彗星试验和hprt基因突变试验检测淋巴细胞的遗传损伤。微核试验以微核率、微核细胞率、核芽、核质桥、核分裂指数和凋亡细胞作为染色体损伤指标；彗星试验以平均尾长和平均尾相作为DNA损伤的指标；hprt基因突变试验以基因突变率作为评价指标。结果 3种试验均呈阳性。hprt基因突变率和凋亡细胞数从0．02μg／ml剂量开始与对照的差异有统计学意义（P〈0．05或P〈0．01），其余指标从最低剂量组开始就明显高于对照组，差异均有统计学意义（P〈0．01或P〈0．05），并存在剂量一效应关系。结论 VCR在体外可通过不同机制诱发人淋巴细胞的遗传损伤。     

Characterization of in vivo somatic mutations at the hypoxanthine phosphoribosyltransferase gene of a human control population.

The ability to recognize a change in mutation spectrum after an exposure to a toxic substance and then relate that exposure to health risk depends on the knowledge of mutations that occur in the absence of exposure. Toward this end, we have been studying both the frequency and molecular nature of mutations of the hypoxanthine phosphoribosyltransferase (hprt) gene in peripheral blood lymphocytes as surrogate reporters of genetic damage. We have analyzed mutants, one per donor to ensure independence, from a control population in which the quantitative effects of smoking and age on mutant frequency have been well defined. Analyses of cDNA and genomic DNA by polymerase chain reaction and sequencing have identified the mutations in 63 mutants, 45 from males and 18 from females, of which 34 were smokers and 29 were nonsmokers. Slightly less than half of the mutations were base substitutions; they were predominantly at GC base pairs. Different mutations at the same site indicated that there are features of the hprt polypeptide that affect the mutation spectrum. Two pairs of identical mutations indicated that there may also be hot spots. Mutations not previously reported have been detected, indicating that the mutation spectrum is only partly defined. The remainder of the mutations were deletions or insertions/duplications; deletions ranged from one base pair to complete loss of the locus. Despite a small average increase in mutant frequency for smokers, an increased proportion of base substitutions at AT base pairs in smokers (p = 0.2) hinted at a smoking-associated shift in the mutation spectrum.(ABSTRACT TRUNCATED AT 250 WORDS)     

晚期混合裂变产物内照射诱发大鼠外周血淋巴细胞hprt基因位点突变与染色体畸变的研究

应用多核细胞法研究晚期混合裂变产物内照射诱发大鼠外周血淋巴细胞ｈｐｒｔ 基因位点突变， 并与染色体畸变进行比较。结果表明， 淋巴细胞ｈｐｒｔ 基因位点突变不仅随内照射剂量增加而增加， 呈现出良好的正相关， 而且与染色体畸变之间亦呈现出较好的相关性。说明辐射诱发ｈｐｒｔ 基因位点突变和染色体畸变的剂量效应关系动力学相似。因此ｈｐｒｔ 基因位点突变有可能成为生物剂量计。     

Protective effects of melatonin against low- and high-LET irradiation

To investigate the protective effects of melatonin against high-LET ionizing radiation, V79 Chinese hamster cells were irradiated with 100 keV/microm carbon beam. Parallel experiments were performed with 200 kV X-rays. To avoid the impact from extra solvents, melatonin was dissolved directly in culture medium. Cells were cultured in melatonin medium for 1 hr before irradiation. Cell inactivation was measured with conventional colony forming assay, medium containing 6-thioguanine was used for the selection of mutants at hprt locus, and the cell cycle was monitored by flow cytometry. Both carbon beam and X-rays induced cell inactivation, hprt gene mutation and cell cycle G2 block dose-dependently. But carbon beam showed stronger effects as indicated by all three endpoints and the relative biological effectiveness (RBE) was 3.5 for cell killing (at 10% survival level) and 2.9 for mutation induction (at 5 x 10(-5) mutants/cell level). Melatonin showed protective effects against ionizing radiation in a dose-dependent manner. In terms of cell killing, melatonin only increased the survival level of those samples exposed to 8Gy or larger of X-rays or 6 Gy or larger of carbon beam. In the induction of hprt mutation and G2 block, melatonin reduced such effects induced by carbon beam but not by X-rays. The results suggest that melatonin reduces the direct interaction of particles with cells rather than an indirect interaction. Further studies are required to disclose the underlying mechanisms.     

DNA lesion and Hprt mutant frequency in rat lymphocytes and V79 Chinese hamster lung cells exposed to cadmium

Cadmium is a potential carcinogenic environmental and occupational pollutant. A wide variety of mutagens have been shown to cause DNA damage, but it is not yet clear whether the DNA damage is relative to inducement of mutations. DNA damage and the formation of mutations at the hypoxanthine guanine phosphoribosyl trans ferase (HPRT) induced by cadmium chloride (CdCl(2)) were investigated with rat lymphocytes and V79 Chinese hamster lung cells. The hprt mutant frequency (MF) assay was used as the method to measure gene mutation in the rat lymphocytes and V79 cells exposed to CdCl(2), and comet assay analysis was performed to detect DNA lesion and repair in CdCl(2)-induced V79 cells. The results showed that CdCl(2) treatment caused a strong genotoxic effect and a marginal effect on the frequency of gene mutations. The hprt mutant frequencies in the rat lymphocytes and V79 cells exposed to CdCl(2) were statistically higher than those of the negative control. There was statistical significance in TL, TD and percentage of comet cell with tails. CdCl(2) treatment can induce DNA single-strand breaks. There was a dose-dependent increase between CdCl(2) and DNA lesion. After cells were treated with CdCl(2) and hydrogen peroxide (H(2)O(2)), the TL and TD declined with repair time increasing, which indicated that DNA damages were repaired gradually. However, DNA repair with treatment of CdCl(2) was slower than that of H(2)O(2) in V79 cells, which suggests that CdCl(2) affected DNA repair of damaged cells. The study also showed that the hprt MF and comet assay can be used for genotoxicity testing of heavy metals. DNA damage detected with the comet assay may be relative to mutagenesis.     

石英对大鼠肺上皮细胞和成纤维细胞的增殖抑制及致hprt基因突变的研究

目的探讨石英对大鼠肺泡II型上皮细胞和成纤维细胞的增殖抑制及致hprt基因突变的差异。方法采用(MTT噻唑蓝)比色法检测大鼠肺成纤维细胞和肺泡II型上皮细胞的增殖抑制毒性。以含6-巯基鸟嘌呤(6-TG)的培养基筛选突变细胞克隆,检测hprt基因突变频率。结果在相同的染毒条件下,肺泡II型上皮细胞对石英刺激比成纤维细胞更易受损伤,上皮细胞半数增殖抑制浓度(IC50)约为140μg/cm2,成纤维细胞的IC50约为282μg/cm2。在致hprt基因突变方面,石英粉尘对两种细胞都有致突变作用。在同样剂量染毒条件下,肺泡Ⅱ型上皮细胞的hprt突变频率为84.2×10-6～156.6×10-6,较成纤维细胞(67.6×10-6～114.3×10-6)更容易发生hprt基因突变,差异有显著性(P<0.05)。结论石英对大鼠肺成纤维细胞和肺泡II型上皮细胞的细胞毒性及对hprt基因致突变作用强度存在明显差异。肺泡II型上皮细胞对石英刺激的反应敏感性高于成纤维细胞。     

炭黑颗粒诱发人B淋巴母细胞系遗传损伤的体外试验

目的 评价2种粒径炭黑诱发的人B淋巴母细胞的遗传损伤效应.方法 人B淋巴母细胞经终浓度为0(溶剂对照)、128、256、384、512 ug/ml的14、280 nm炭黑颗粒染毒24、48 h后,用微核试验、hprt基因突变试验和彗星试验进行检测.微核试验指标为微核率(MNR)、微核细胞率(MCR)、核芽(Buds)、核质桥(NPBs)、核分裂指数(NDI)和凋亡细胞.彗星试验指标为尾部DNA百分比(%tail ONA)和olive尾矩(OTM).hprt基因突变试验指标为基因突变率(Mf-hprt).结果 14 nm炭黑染毒48 h组,浓度为384、512 ug/ml时,%tail DNA、OTM分别为8.23%±0.19%、11.23%±0.42%和3.72±0.08、4.90±0.18,明显高于对照组(5.10%±0.08%和2.22±0.03),差异有统计学意义(P<0.01);凋亡细胞数分别为4.67±0.33、5.33±0.33,明显高于对照组(0.00±0.00),差异有统计学意义(P<0.05).hprt 基因突变试验结果 呈阴性.结论 14 nm超细炭黑细颗粒染毒48 h可诱发人B淋巴母细胞DNA损伤,但280 nm的炭黑颗粒未检测出类似效应.     

热休克预处理对X射线诱发淋巴细胞hprt基因突变的影响

目的 探讨热休克预处理对X射线诱发淋巴细胞hprt基因突变的影响。方法 在42℃、5% CO₂培养箱中对大鼠外周血淋巴细胞进行热休克处理90min。将细胞样本分为:对照组,热休克组,照射组,热休克+照射组,每组6个平行样本。每组样本再分成两组细胞,其中一组细胞加入终浓度为0.1mmol/L的6-TG,另一组不加6-TG。每组细胞经不同剂量(0.5Gy、1.0 Gy、1.5 Gy、2.0 Gy、2.5 Gy、3.0 Gy)X射线照射并恢复培养3h,6h,10h后,用多核细胞法检测大鼠外周血淋巴细胞hprt基因突变。结果 大鼠外周血淋巴细胞接受不同剂量X射线照射后恢复3h,6h,10h,热休克+照射组细胞hprt基因突变率与照射组细胞hprt基因突变率相比明显下降(P < 0.01)。结论 热休克预处理对X射线所致细胞hprt基因突变具有保护效应,对X射线所致细胞hprt基因突变的保护作用在低剂量照射比高剂量照射时更为明显,其保护效率与照射剂量之间为负相关系。