三硝基甲苯致突变作用的研究

本文以Ames试验法测定了三硝基甲苯(TNT)致突变性.用多氯联苯诱导制备大鼠(SD系)肝脏S9,作为代谢活化系。TA08和TA100菌株做为指示菌,以平皿掺入法测定回变菌落数。已知的致癌物NaN_3、敌克松、二氨基芴作为每次实验的阳性对照,试验中每浓度均设三个平行样品.在37℃,48h培养后计回变菌落数.Ames试验结果,TNT对TA98和TA100菌株均具有明显的致突变性。     

乙型肝炎病毒核心启动子缺失变异对病毒抗原表达的影响

目的为研究乙型肝炎病毒(HBV)核心启动子(CP)20/21bp部分缺失(nt1748/1747至nt1767)及同时存在的A1896点变异对病毒抗原表达的影响。方法利用前期构建的HBV全基因的重组载体转染HepG2细胞后,对病毒抗原进行ELISA检测及Western-blotting分析。结果变异株分泌到细胞外的HBsAg、HBeAg及细胞内的HBcAg表达量较野毒株均明显减少。结论HBVCP20/21bp部分缺失株及同时存在的A1896点变异株的病毒抗原表达较野毒株显著下降。     

人动脉粥样硬化斑块p53基因突变的初步报告

从甲醛固定的成人动脉粥样硬化斑块组织中提取ＤＮＡ，用ＰＣＲ扩增ｐ５３基因片段，将扩增的ｐ５３基因片段亚克隆至ＳＫ载体内，对扩增后的片段进行核苷酸序列分析。结果发现，动脉粥样硬化斑块中ｐ５３基因内第八外显子中第２７２位密码子的Ｔ变为Ｃ。免疫组化分析观察到斑块内有ｐ５３基因突变蛋白的表达。提示：ｐ５３基因突变可能与动脉粥样硬化的细胞增殖异常有关。     

多发性内分泌腺瘤病2A家系的RET原癌基因突变研究

目的 检测一个多发性内分泌腺瘤病2A(MEN 2A)型家系的RET原癌基因突变情况。方法 提取16名家系成员外周血基因组DNA，对RET原癌基因第ll外显子进行聚合酶链反应(PCR)，PCR产物进行直接基因测序。结果 家系中l例病理确诊嗜铬细胞瘤的患者存在RET原癌基因第ll外显子634密码子错义突变；另外筛查出2名家系成员为该突变基因携带者，其中l例经B超发现甲状腺结节性病灶伴血清降钙素升高。结论 MEN2A的诊断达到了基因水平，对家系基因筛查可以早期诊断该疾病。     

Hb KODAIRA II: A HIGH OXYGEN AFFINITY VARIANT WITH A NOVEL MUTATION IN THEβ-GLOBIN GENE AND PHENOTYPIC IDENTITY TO Hb KODAIRA

We report a case of α⁺-thalassemia (α⁺-thal) trait caused by a novel frameshift mutation in exon 2 of the α2-globin gene, specifically a deletion of a single nucleotide at amino acid codon 81 [HBA2 c.244delT]. The mutation results in a premature termination of translation at codon 83.     

Characterization of Clinical and Laboratory Profiles of the Deletional α2-Globin Gene Polyadenylation Signal Sequence (AATAAA > AATA– –) in an Indian Population

Abstract

α-Thalassemia (α-thal) is characterized by large deletions involving the variable regions of α2 and/or α1 genes. Nondeletional mutations and polyadenylation (polyA) signal sequence motif mutations are less common. In this retrospective study, we describe a fragment length analysis-based polymerase chain reaction (PCR) assay for screening the T^Indian (AATAAA?>?AATA–?–; HBA2: c.*93_*94delAA) polyA signal deletion along with its clinical and laboratory presentation in 21 patients. Most of the patients were diagnosed in early adulthood with a clinical presentation ranging from asymptomatic in the heterozygous state to severe Hb H disease with a prominent hemolytic component in the homozygous state. On genetic analysis, 14 patients were found to be homozygotes, five were compound heterozygotes and two were heterozygotes. Thus, the T^Indian polyA signal deletion is common in the Indian population and should be screened for in patients with nondeletional α-thal mutations.     

Half or more of the somatic mutations in cancers of self-renewing tissues originate prior to tumor initiation

Although it has been hypothesized that some of the somatic mutations found in tumors may occur before tumor initiation, there is little experimental or conceptual data on this topic. To gain insights into this fundamental issue, we formulated a mathematical model for the evolution of somatic mutations in which all relevant phases of a tissue’s history are considered. The model makes the prediction, validated by our empirical findings, that the number of somatic mutations in tumors of self-renewing tissues is positively correlated with the age of the patient at diagnosis. Importantly, our analysis indicates that half or more of the somatic mutations in certain tumors of self-renewing tissues occur before the onset of neoplasia. The model also provides a unique way to estimate the in vivo tissue-specific somatic mutation rates in normal tissues directly from the sequencing data of tumors. Our results have substantial implications for the interpretation of the large number of genome-wide cancer studies now being undertaken.