The role of polymorphic cytochrome P450 gene(CYP2B6)in B-chronic lymphocytic leukemia(B-CLL)incidence and outcome among Egyptian patients

Cytochromes P450(CYPs)play a prominent role in catalyzing phase I xenobiotic biotransformation and account for about 75%of the total metabolism of commercially available drugs,including chemotherapeutics.The gene expression and enzyme activity of CYPs are variable between individuals,which subsequently leads to different patterns of susceptibility to carcinogenesis by genotoxic xenobiotics,as well as differences in the efficacy and toxicity of clinically used drugs.This research aimed to examine the presence of the CYP2B6*9 polymorphism and its possible association with the incidence of B-CLL in Egyptian patients,as well as the clinical outcome after receiving cyclophosphamide chemotherapy.DNA was isolated from whole blood samples of 100 de novo B-CLL cases and also from 100 sex-and age-matched healthy individuals.The presence of the CYP2B6*9(G516T)polymorphism was examined by PCR-based allele specific amplification(ASA).Patients were further indicated for receiving chemotherapy,and then they were followed up.The CYP2B6*9 variant indicated a statistically significant higher risk of B-CLL under different genetic models,comprising allelic(T-allele vs.G-allele,OR=4.8,p<0.001)and dominant(GT+TT vs.GG,OR=5.4,p<0.001)models.Following cyclophosphamide chemotherapy,we found that the patients with variant genotypes(GT+TT)were less likely to achieve remission compared to those with the wild-type genotype(GG),with a response percentage of(37.5%vs.83%,respectively).In conclusion,our findings showed that the CYP2B6*9(G516T)polymorphism is associated with B-CLL susceptibility among Egyptian patients.This variant greatly affected the clinical outcome and can serve as a good therapeutic marker in predicting response to cyclophosphamide treatment.

注射用丹参总酚酸(冻干)对人CYP450酶和P-糖蛋白体外抑制作用及对大鼠CYP1A2和CYP3A体内诱导作用(英文)

目的探讨注射用丹参总酚酸(冻干)(SLI)对人CYP450酶和P-糖蛋白体外抑制作用以及对大鼠CYP1A2和CYP3A体内诱导作用。方法①应用P450-GloTMCYP450检测试剂盒,通过化学发光法测定SLI和经典抑制剂对细胞色素P4501A2(CYP1A2),CYP2D6,CYP3A4,CYP2C19和CYP2C9的IC50值,通过比较SLI和经典抑制剂对相应细胞色素P450亚型的IC50值来判断SLI对人CYP450酶的体外抑制作用。②Wistar大鼠分别iv给予SLI 3,10和30 mg·kg-1和诱导剂苯巴比妥钠20 mg·kg-1,采用探针底物法,通过比较代谢产物的生成速率来评价SLI对大鼠CYP1A2和CYP3A的诱导作用。③应用ATP酶检测试剂盒,通过化学发光法测定ATP酶活性来评价SLI是否为P-gp的底物或抑制剂。结果①CYP1A2,CYP2C9,CYP2C19,CYP2D6和CYP3A4抑制剂的IC50与SLI对其的IC50进行比较(CYP1A2:0.12μmol·L-1vs 840μmol·L-1;CYP2C9:3.362μmol·L-1vs 704μmol·L-1;CYP2C19:3.236μmol·L-1vs 306μmol·L-1;CYP2D6:0.117μmol·L-1vs 2660μmol·L-1;CYP3A4:0.078μmol·L-1vs 1780μmol·L-1)。②与空白对照组(86.4±6.3)nmol·g-1.min-1相比,SLI 3,10和30 mg·kg-1组CYP1A2活性分别为83.4±6.6,82.5±4.0和(83.4±6.6)nmol·g-1.min-1。与空白对照组(16.1±0.9)nmol·g-1.min-1比较,SLI 3,10和30 mg·kg-1组CYP3A活性分别为15.7±0.6,15.9±0.7和(15.9±1.0)nmol·g-1.min-1,无显著性差异。③以临床血药浓度为依据设计的一系列浓度的SLI 0.0002,0.0006,0.002,0.006,0.017,0.052,0.156和0.468 g.L-1的ATP酶活性分别与空白对照组进行比较(5.8,5.3,5.8,5.5,5.8,5.2,,5.8,5.3,vs 5.75μmol·g-1.min-1),无显著性差异。结论SLI临床给药剂量既不能体外抑制人CYP1A2,CYP2D6,CYP3A4,CYP2C19和CYP2C9酶活性,也不能诱导大鼠CYP1A2和CYP3A,同时也不是P-gp的体外抑制剂或底物。

3Gyγ射线照射和丝裂霉素C对大鼠肝脏细胞色素P450含量及其同工酶CYP2B1、CYP2E1活性的影响

为研究3Gyγ射线全身照射和丝裂霉素C(MitomycinC,MMC)对雄性(Sprague-Dawley,SD)大鼠肝脏细胞色素P450含量、CYP2B1、CYP2E1活性的影响,分别给大鼠腹腔注射1mg/kgd的MMC(分1d,连续3d及6d用药三组),3mg/kg的MMC1d,3Gyγ射线全身照射,3Gyγ射线全身照射加1d3mg/kgMMC,另设空白对照和溶剂对照。各组处理结束后24h,处死大鼠取肝脏,制备微粒体,测P450含量、CYP2B1、CYP2E1活性。实验结果表明,给MMC1mg/kgd,1d后P450含量、CYP2B1活性变化无统计学差异(p>0.05),CYP2E1活性明显上升(p<0.01);连续3d或6d后,P450含量、CYP2B1、CYP2E1活性均无明显变化(p>0.05)。给3mg/kg的MMC1d,对P450含量、CYP2B1活性影响无统计学差异(p>0.05),CYP2E1活性上升明显(p<0.01);3Gyγ射线全身照射后,P450含量、CYP2B1活性无明显变化(p>0.05),CYP2E1活性下降(p<0.05);分析发现,3mg/kgMMC与3Gyγ射线之间没有交互作用。结果提示,γ射线可以抑制雄性SD大鼠肝脏CYP2E1活性,MMC对CYP2E1活性有诱导作用,但多次刺激使其耐受,P450含量、CYP2B1活性对γ射线、MMC不敏感。

Influences of V5-epitope tag on the metabolic activation of AFB1 by human cytochrome P450 2A13

Objective： To explore the impact of V5-epitope tag inserted in the commercial pcDNA5/FRT/V5-His TOPO expression vector on the metabolic activation of AFB1 by human CYP2A13. Methods ： A C-terminal 6 × Histag was first introduced into CYP2A13 cDNA by PCR and subsequently transferred into the expressing vector pcDNA5/FRT. Another commercial pcDNA5/FRT/V5-His TOPO expression vector was used to develop the construct directly via PCR. Both of the constructs were then transfected into Flp-In CHO and allowed for the stable expression of CYP2A13. The mouse CYP2A5 and the vector alone were used as positive and negative control, respectively. The presence of CYP2A5 and CYP2A13 cDNA and their protein expression in the stable transfectant cells were deterrrfined by immunoblotting assay using a monoclonal antibody against 6 × Histag. The AFBl-induced cytotoxicity in these tranfected CHO cells were conducted by MTS assay and the IC50 of cell viability was used to compare the CYP enzyme metabolic activity in AFB1 metabolism among these cells. Results： In accordance with the Flp-In system working mechanism, all the transfectant cells presented same protein expression level. The CHO cells expressing CYP2A5 was more sensitive to AFB1 treatment than those cells expressing CYP2A13, there was about 30-fold ICs0 difference between the two cells （2.1 nmol/L vs 58 nmol/L）. Interestingly, CYP2A13 fused with V5-Histag had the lost of metabolic activity to AFB1 than that fused with Histag alone, the ICa, of the viability in CHO-2A13-His-V5 cells was about 20-fold less than CHO-2A13- His （〉 1 000 nmol/L vs 58 nmol/L）. However, there was no change between CYP2A5 fused with V5-Histag and Histag alone （2.4 nmol/L vs 2.1 nmol/L）. Conclusion： The results demonstrate that CYP2A13 fused with V5-epitope has a significant impact on its metabolic activation to AFB1, which indicated that it should be careful to select a new expressing vector for evaluating the enzyme activity in carcinogen metabolism.

Cytochrome P450 2E1 genetic polymorphism and gastric cancer in Changle,Fujian Province

AIM: Genetic polymorphism in enzymes of carcinogen metabolism has been found to have the influence on the susceptibility to cancer. Cytochrome P450 2E1 (CYP2E1) is considered to play an important role in the metabolic activation of procarcinogens such as N-nitrosoamines and low molecular weight organic compounds. The purpose of this study is to determine whether CYP450 2E1 polymorphisms are associated with risks of gastric cancer. METHODS: We conducted a population based case-control study in Changle county, Fujian Province, a high-risk region of gastric cancer in China. Ninety-one incident gastric cancer patients and ninety-four healthy controls were included in our study. Datas including demographic characteristics, diet intake, and alcohol and tobacco consumption of individuals in our study were completed by a standardized questionnaire.PCR-RFLP revealed three genotypes:heterozygote (C1/C2) and two homozygotes (C1/C1 and C2/C2) in CYP2E1. RESULTS: The frequency of variant genotypes (C1/C2 and C2/C2) in gastric cancer cases and controls was 36.3% and 24.5%, respectively. The rare homozygous C2/C2 genotype was found in 6 individuals in gastric cancer group(6.6%), whereas there was only one in the control group (1.1%). However, there was no statistically significant difference between the two groups (two-tailed Fisher's exact test P=0.066). Individuals in gastric cancer group were more likely to carry genotype C1/C2 (odds ratio, OR=1.50) and C2/C2 (OR=7.34) than individuals in control group (chi(2) =4.597, for trend P=0.032). The frequencies of genotypes with the C2 allele (C1/C2 and C2/C2 genotypes) were compared with those of genotypes without C2 allele (C1/C1 genotype) among individuals in gastric cancer group and control group according to the pattern of gastric cancer risk factors. The results show that individuals who exposed to these gastric cancer risk factors and carry the C2 allele seemed to have a higher risk of developing gastric cancer. CONCLUSION: Polymorphism of CYP2E1 gene may have some effect in the development of gastric cancer in Changle county, Fujian Province.

Three new alternative splicing variants of human cytochrome P450 2D6 mRNA in human extratumoral liver tissue

AIM: To identify the new alternative splicing variants of human CYP2D6 in human extratumoral liver tissue with RT-PCR and sequencing. METHODS: Full length of human CYP2D6 cDNAs was amplificated by reverse transcription-polymerase chain reaction (RT-PCR) from a human extratumoral liver tissue and cloned into pGEM-T vector. The cDNA was sequenced. Exons from 1 to 4 of human CYP2D6 cDNAs were also amplificated by RT-PCR from extratumoral liver tissues of 17 human hepatocellular carcinomas. Some RT-PCR products were sequenced. Exons 1 to 4 of CYP2D6 gene were amplified by PCR from extratumoral liver tissue DNA. Two PCR products from extratumoral liver tissues expressing skipped mRNA were partially sequenced. RESULTS: One of the CYP2D6 cDNAs had 470 nucleotides from 79 to 548 (3' portion of exons 1 to 5' portion of exon 4), and was skipped. Exons 1 to 4 of CYP2D6 cDNA were assayed with RT-PCR in 17 extratumoral liver tissues. Both wild type and skipped mRNAs were expressed in 4 samples, only wild type mRNA was expressed in 5 samples, and only skipped mRNA was expressed in 8 samples. Two more variants were identified by sequencing the RT-PCR products of exons 1 to 4 of CYP2D6 cDNA. The second variant skipped 411 nucleotides from 175 to 585. This variant was identified in 4 different liver tissues by sequencing the RT-PCR products. We sequenced partially 2 of the PCR products amplified of CYP2D6 exon 1 to exon 4 from extratumoral liver tissue genomic DNA that only expressed skipped mRNA by RT-PCR. No point mutations around exon 1, intron 1, and exon 4, and no deletion in CYP2D6 gene were detected. The third variant was the skipped exon 3, and 153 bp was lost. CONCLUSION: Three new alternative splicing variants of CYP2D6 mRNA have been identified. They may not be caused by gene mutation and may lose CYP2D6 activity and act as a down-regulator of CYP2D6.

Expression of cytochrome P450 2A13 in human non-small cell lung cancer and its clinical significance

Lung cancer is one of the most important causes of cancer-related mortality worldwide. Human cytochrome P450 2A13 enzyme （CYP2A13） is predominantly expressed in the respiratory tract and could catalyze various carcinogens. In this study, we quantified CYP2A13 expression in non-small cell lung cancer （NSCLC） tissues and examined the relation between CYP2A13 and clinicopathologic factors. Thirty-five paired lung cancer and normal tissues were studied for the expression of the CYP2A13 gene by using real-time PCR and Western blot- ting assays. We also investigated the relationship between CYP2A13 expression and clinicopathologic factors such as age, gender, histology and lymph node status in tumor tissues. SPSS （17.0） statistical software was applied for data analysis. The real-time PCR results showed that there was no significant difference in the CYP2A13 mRNA transcript levels between tumor and paired normal tissues in the 35 samples and in 12 paired squamous cell car- cinomas. In adenocarcinoma, the expression of CYP2A13 mRNA in tumor tissues was 12.5% of that in adjacent tissues （P 〈 0.05） and it was not associated with age, gender, histology and lymph node status of the patients. The amounts of CYP2A13 proteins detected by Western blotting assays correlated well with those of the correspond- ing mRNAs. In conclusion, the expression of CYP2A13 was downregulated in lung adenocarcinoma. CYP2A13 may be involved in the development and progression of lung adenocarcinoma.

Cytochrome P450 CitCYP97B modulates carotenoid accumulation diversity by hydroxylating β-cryptoxanthin in Citrus

Carotenoids in plant foods provide health benefits by functioning as provitamin A.One ofthe vital provitamin A carotenoids,β-cryptoxanthin,is typically plentiful in citrus fruit.However,little is known about the genetic basis of β-cryptoxanthin accumulation in citrus.Here,we performed a widely targeted metabolomic analysis of 65 major carotenoids and carotenoid derivatives to characterize carotenoid accumulation in Citrus and determine the taxonomic profile of b-cryptoxanthin.We used data from 81 newly sequenced representative accessions and 69 previously sequenced Citrus cultivars to reveal the genetic basis of β-cryptoxanthin accumulation through a genome-wide association study.We identified a causal gene,CitCYP97B,which encodes a cytochrome P450 protein whose substrate and metabolic pathways in land plants were undetermined.We subsequently demonstrated that CitCYP97B functions as a novel monooxygenase that specifically hydroxylates the β-ring of β-cryptoxanthin in a heterologous expression system.In planta experiments provided further evidence that CitCYP97B negatively regulates b-cryptoxanthin content.Using the sequenced Citrus accessions,we found that two critical structural cis-element variations contribute to increased expression of CitCYP97B,thereby altering β-cryptoxanthin accumulation in fruit.Hybridization/introgression appear to have contributed to the prevalence of two cis-element variations in different Citrus types during citrus evolution.Overall,these findings extend our understanding of the regulation and diversity of carotenoid metabolism in fruit crops and provide a genetic target for production of β-cryptoxanthin-biofortified products.

肝硬化模型大鼠CYP2B6和CYP3A酶活性变化

目的研究CYP2B6和CYP3A酶活性在肝硬化模型大鼠体内的变化。方法雄性SD大鼠分别采用每周2次ip给予30%CCl4连续7周、饮用含0.03%-0.04%硫代乙酰胺（TAA）液连续10周、复合法（sc给予用花生油配制的40%CCl4＋高脂饲料＋15%乙醇,共6周）及免疫法（sc给予牛血清白蛋白20-40 mg·kg-1,共11周）制备肝硬化模型后,联合ig给予安非他酮15 mg·kg-1和咪达唑仑10 mg·kg-1。测定给药前及给药后0.083,0.25,0.5,1,1.5,2,2.5,3,4,6,8,12和24 h的血药浓度。结果与正常对照组相比,四氯化碳组和TAA组的2个探针药曲线下面积（AUC）均显著性升高（P〈0.05）,峰浓度c max显著性升高（P〈0.01）,清除率Cl/F均显著性下降（P〈0.05）;复合法组2个探针药c max均显著性下降（P〈0.05）;免疫组2个探针药的药代参数均无统计学意义。结论 CCl4和TAA诱导的肝硬化模型大鼠体内CYP2B6和CYP3A酶活性降低。

银杏内酯B对CYP2C9底物双氯芬酸在大鼠体内药动学和药效学的影响

目的:在大鼠体内,以双氯芬酸为工具药,研究银杏内酯B对双氯芬酸药动学和药效学的影响,阐明银杏内酯B对大鼠肝细胞色素P450 2C9(CYP 2C9)是否有抑制或诱导作用。方法:通过观察大鼠连续给予银杏内酯B(剂量为12 mg·kg^(-1),ip,bid,连续7 d)前后对单次给予临床等效量的双氯芬酸(15 mg·kg^(-1),iv)的药时曲线及药动学参数的改变,评价其对双氯芬酸药动学的影响,并评价银杏内酯B连续给药后对单次给予双氯芬酸抗足跖肿胀作用药效学的影响。结果:连续给予银杏内酯B后,与用药前比较,双氯芬酸及其主要代谢物4-羟基双氯芬酸的血药浓度及其药动学参数未见显著性改变;双氯芬酸抗足跖肿胀作用亦未见显著性改变。结论:多剂量给予银杏内酯B对临床等效量双氯芬酸在大鼠体内药动学和药效学无显著影响;银杏内酯B对大鼠肝CYP 2C9无明显的抑制或诱导作用。

人肝微粒体中CYP2B6对氯胺酮代谢的催化作用

氯胺酮是临床常用静脉麻醉药，特别是广泛用于小儿短小手术的麻醉和术前基础麻醉。已知氯胺酮进入体内之后，大部分经肝脏细胞色素P450代谢，形成去甲氯胺酮。有必要进一步研究氯胺酮的代谢饥制和影响其代谢的遗传机制。

CYP2B和CYP3A参与药物代谢的影响因素及对氯胺酮代谢的影响

目的:为进一步研究氯胺酮在成瘾动物体内代谢动力学规律及细胞色素P_(450)活性的调控和相关性研究提供参考。方法:以"细胞色素P_(450)""性别""氯胺酮""CYP2B""CYP3A""Sex""Ketamine"等为关键词,组合查询1980-2016年在Pub Med、Elsevier、中国知网、万方、维普等数据库中的相关文献,对CYP2B和CYP3A参与药物代谢的诱导、抑制和性别等影响因素及对氯胺酮代谢的影响进行综述。结果与结论:共检索到相关文献256篇,其中有效文献62篇。CYP2B和CYP3A是重要的细胞色素P_(450),二者参与代谢了临床大多数药物,包括氯胺酮。诱导、抑制和性别差异等因素主要是通过改变细胞色素P_(450)的基因表达和蛋白表达来影响药物在动物体内代谢的。氯胺酮是一种被广泛滥用的药物,具有成瘾性和个体的耐受差异性。通过研究细胞色素P_(450)的基因表达和蛋白表达有利于指导研究氯胺酮在成瘾动物体内的特殊代谢动力学规律,以及为阐释成瘾动物体内的细胞色素P_(450)活性的调控机制和相关性研究提供理论支持。

细胞色素P4502E1(CYP2E1)与胃癌遗传易感性

为探讨细胞色素P4502E1(CYP2E1)基因变化与胃癌易感的关系,采用病例—对照分子流行病学研究方法和多聚酶链反应技术—限制性片段长度多态性(PCR—RFLP),对142例胃癌患者和167例正常对照者CYP2E1基因RsaⅠ酶切位点进行多态性分析。结果显示胃癌患者和正常对照人群在基因型和等位基因频率上均无显著的统计学差异;我国人群CYP2E1 RsaⅠ酶切位点多态性的分布频率与日本人群相近,与欧美人群差异较大。

重组CYP2D26主要B细胞表位在Ⅱ型自身免疫性肝炎小鼠模型构建中的效应研究

目的研究在大肠杆菌中以重组病毒样颗粒形式表达的人II型自身免疫性肝炎标志蛋白CYP2D6主要抗原表位aa262-270免疫小鼠后对构建小鼠自身免疫性肝炎模型的效应。方法设计人II型自身免疫性肝炎标志蛋白主要抗原表位aa262-270(WDPAQPPRD)的正负链寡核苷酸片段,经退火后插入表达乙肝核心蛋白HBcAg的质粒pNP中(pNP质粒由pThioHisA质粒插入HBcAg基因片段构建而成)。构建成质粒pNP-AIH2;转染大肠杆菌DH5α感受态细胞;以IPTG诱导重组蛋白表达,经硫酸铵沉淀、洗涤,密度梯度离心纯化和脱盐后,肌肉注射免疫小鼠3次,以ELISA和western blot检测免疫后小鼠特异性抗体的产生和水平,通过转氨酶检测和肝脏石蜡切片HE染色观察炎症反应。结果 SDS-PAGE结果显示重组菌诱导表达的目的蛋白分子量为19kD,与预期相符;电镜证实其以可溶性的病毒样颗粒形式存在;ELISA显示,免疫小鼠血清与包被的肝脏匀浆蛋白特异反应,检测到持续存在的特异抗体,滴度至少为1:2000;western blot检测表明,抗血清在分子量约为55kD的地方产生了一个特异的条带,与小鼠CYP2D6蛋白大小一致。与正常对照相比,实验组小鼠转氨酶水平未明显升高,肝切片HE染色没有观测到明显的病理特征。结论携带人II型自身免疫性肝炎标志蛋白CYP2D26主要表位的病毒样颗粒免疫小鼠后,可刺激产生较强的特异抗体水平,但在观测时间内,未见诱导小鼠产生明显的肝脏炎症反应。

ABCB1及CYP2C19基因多态性对氯吡格雷治疗的影响

氯吡格雷是一种人工合成的噻吩并吡啶类抗血小板药物，广泛应用于心脑血管病预防及治疗过程中。其本身为无作用的前体药物，口服后约85%的氯吡格雷被酯酶水解，只有15%的药物经肝脏的细胞色素P450酶系（cytochromeP450，CYP）转化成为活性成分后发挥作用[1]。吸收后的氯吡格雷经CYP活化过程分为两步[2]：第一步，氯吡格雷经细胞色素氧化酶P450-2C19（CYP2C19），细胞色素氧化酶P450-1A2（CYP1A2）和细胞色素氧化酶P450-2B6（CYP2B6）转化为2-氧-氯吡格雷，转化比例分别约为45%、36%、19%。第二步，2-氧-氯吡格雷经细胞色素氧化酶P450-3A4/5（CYP3A4/5），CYP2B6，CYP2C19和细胞色素P450-2C9（CYP2C9）转化为硫醇活化代谢产物，转化比例分别约为40%、33%、21%和7%。之后活化的氯吡格雷与血小板表面的二磷酸腺苷（ADP）P2Y12受体不可逆的结合，阻断ADP对腺苷环化酶的抑制作用，从而发挥抑制血小板聚集的功能。

抑制NF-κB的活化对免疫性肝损伤大鼠CYP1A2的影响

目的研究在免疫性肝损伤大鼠模型中,抑制核转录因子κB (nuclear factor kappa B,NF-κB)的活化对细胞色素P450总含量、亚型1A2(CYP1A2)表达、代谢活力的影响。方法采用尾静脉注射卡介苗(BCG)125 mg·kg^(-1) 14 d制备免疫性肝损伤大鼠模型。采用双光束紫外分光光度法测定肝匀浆中CYP450总含量;肝脏组织HE染色法和测定血清中ALT、AST水平,检测大鼠肝损伤情况; Western blot法检测大鼠肝组织中CYP1A2蛋白表达; HPLC法检测CYP1A2的探针药物茶碱的血浆药物浓度经时变化,从而反映CYP1A2的代谢活力。结果大鼠尾静脉注射BCG 14 d后,可引起肝组织炎性细胞浸润,肝重、脾重增加,血清转氨酶ALT及AST水平明显升高,CYP450总含量降低,CYP1A2表达和代谢活力明显降低。采用吡咯烷二硫氨基甲酸(PDTC)抑制NF-κB活化,可缓解CYP450总含量的降低,减缓CYP1A2蛋白表达和代谢活力的下调。结论免疫损伤刺激明显下调CYP1A2,钝化NF-κB活化可明显抑制免疫性肝损伤大鼠肝组织中CYP1A2的下调,NF-κB可能参与CYP1A2下调机制。

Use of cafeine as a probe for rapid determination of cytochrome P-450 CYP1A2 activity in humans

目的：建立快速测定细胞色素Ｐ４５０ＣＹＰ１Ａ２酶活性的高压液相色谱方法．方法：取３００μＬ血浆样品，用β羟乙基茶碱作内标，经５ｍＬ氯仿／异丙醇（９∶１）萃取处理后，用００５％的乙酸、乙腈和甲醇作为基本流动相，采用梯度洗脱程序在ＯＤＳ柱上分离待测组分，紫外检测波长２８２ｎｍ．结果：无内源性物质干扰测定．次黄嘌呤、内标和咖啡因快速基线分离，三者的保留时间均小于１３分钟．次黄嘌呤和咖啡因的检测下限均为０１μｍｏｌ·Ｌ－１，线性范围分别为１－１００μｍｏｌ·Ｌ－１和１－２００μｍｏｌ·Ｌ－１，相关系数分别为０９９９９和０９９８７，变异系数分别小于６％和１０％．两者的平均相对回收率为９６％－１０８％．结论：本方法快速、灵敏，可用于人群ＣＹＰ１Ａ２酶活性研究．

GSTT1,GSTM1 and CYP2E1 genetic polymorphisms in gastric cancer and chronic gastritis in a Brazilian population

AIM:To test the hypothesis that,in the Southeastern Brazilian population,the GSTT1,GSTM1 and CYP2E1 polymorphisms and putative risk factors are associated with an increased risk for gastric cancer. METHODS:We conducted a study on 100 cases of gastric cancer (GC),100 cases of chronic gastritis (CG),and 150 controls (C).Deletion of the GSTT1 and GSTM1 genes was assessed by multiplex PCR.CYP2E1/Pst1 genotyping was performed using a PCR-RFLP assay. RESULTS:No relationship between GSTT1/GSTM1 deletion and the c1/c2 genotype of CYP2E1 was observed among the three groups.However,a significant difference between CG and C was observed,due to a greater number of GSTT1/GSTM1 positive genotypes in the CG group.The GSTT1 null genotype occurred more frequently in Negroid subjects,and the GSTM1 null genotype in Caucasians,while the GSTM1 positive genotype was observed mainly in individuals with chronic gastritis infected with H pylori. CONCLUSION:Our findings indicate that there is no obvious relationship between the GSTT1,GSTM1 and CYP2E1 polymorphisms and gastric cancer.

Detection of CYP2E1,a Genetic Biomarker of Susceptibility to Benzene Metabolism Toxicity in Immortal Human Lymphocytes Derived from the Han Chinese Population

Objective Cytochrome P450 2E1 （CYP2E1） is an important metabolizing enzyme involved in oxidative stress responses to benzene, a chemical associated with bone marrow toxicity and leukemia, We aimed to identify the CYP2E1 genetic biomarkers of susceptibility to benzene toxicity in support of environmental and occupational exposure prevention, and to test whether a model using immortal human lymphocytes might be an efficient tool for detecting genetic biomarkers. Methods Immortalized human lymphocyte cell lines with independent genotypes on four CYP2E1 SNP sites were induced with 0.01% phenol, a metabolite of benzene. CYP2E1 gene function was evaluated by mRNA expression and enzyme activity. DNA damage was measured by Single-Cell Gel Electrophoresis （SCGE）. Results Among the four SNPs, cells with rs2070673TT and rs2030920CC showed higher levels of ~YP2E1 transcription and enzymatic activity than the other genotypes in the same SNP site. Cells with higher gene expression genotypes also showed higher comet rates compared with lower gene expression genotypes. Conclusion These results suggest that CYP2E1 rs2070673 and rs2030920 might be the genetic biomarkers of susceptibility to benzene toxicity and that the immortalized human lymphocytes model might be an efficient tool for the detection of genetic biomarkers of susceptibility to chemicals.

CYP2B6单核苷酸多态性与丙型肝炎病毒复发性的相关研究

聚乙二醇干扰素联合利巴韦林是目前治疗丙型肝炎病毒(hepatitis C virus,HCV)感染最常用方案,70%以上患者可达到有效的持续性病毒学应答(sustained virological response,SVR),但仍有部分患者在抗病毒治疗后出现复发,影响预后[1]。细胞色素P450家族2B6亚基(Cytochromes P4502B6,CYP2B6)的单核苷酸多态性(single nucleotide polymorphism,SNP)与HCV治疗反应相关[2],但是否与HCV复发相关目前未见报道。本研究主要探讨CYP2B6的SNP与HCV初次感染患者治疗后复发的相关性。