中国布鲁氏菌16 s-23 s rRNA间隔区多态性研究

目的利用16 s-23 s rRNA间隔区(ITS)的多态性,对中国布鲁氏菌种间或种内生物型进行鉴别,评价ITS作为基因标识物的意义,寻找适合布鲁氏菌分型研究的基因标识物。方法应用聚合酶链反应-单链构象多态性(PCR-SSCP)分析技术,对中国120株布鲁氏菌的ITS进行分析和筛选,测序结果与Genbank中的布鲁氏菌ITS序列进行比较分析。结果对16 s-23 s rRNA间隔区的SSCP结果分析,得到4种不同的带型(ⅠI、I、Ⅲ、Ⅳ),测序序列有3个位点的差异,达到99.87%的一致性。结论中国布鲁氏菌的ITS序列高度保守,具有一定探讨其作为布鲁氏菌属种内分型的基因标识的价值。     

肺腺癌p53基因突变与临床病理特征关系的研究

目的探讨p53基因在肺腺癌中突变的频率、位置和在肺腺癌发生发展中的作用及与其临床病理特征的关系。方法聚合酶链式反应一单链构象多态性（PCR－SSCP）检测31例肺腺癌的P53基因第5～8外显子突变。结果14例（45％）出现P53基因5～8外显子突变，其中7、8外显子突变占73％。P53基因突变男性显著高于女性（P—0．003），在肿瘤≤3cm的病例p53基因突变率显著低于肿瘤＞3cm的病例（P=0．005）。p53基因突变与吸烟史、年龄、组织学类型、分化程度、淋巴结状况、国际病理TNM分期及瘤栓无显著性差异（P＞0．05）。结论肺腺癌中P53突变率为45％，主要分布在第7、8外显子，P53基因突变参与肺腺癌癌变的始动和腺癌的进展。     

Cloning of the Rat Homologue of the von Hippel-Lindau Tumor Suppressor Gene and Its Non-somatic Mutation in Rat Renal Cell Carcinomas

Recently, von Hippel-Lindau ( VHL ) gene mutations were detected in non-inherited, sporadic human renal cell carcinomas (RCs) at a high frequency. In order to determine whether or not the VHL gene is also a critical gene in rat RCs, we cloned and sequenced the rat homologue of human VHL gene and searched for mutations of the VHL gene in rat RCs. Mutations in the VHL gene were not detected in spontaneous RCs of the Eker rat model or in ferric nitrilotriacetate-induced rat RCs using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method. These data indicate that mutation of the VHL tumor suppressor gene is not an event in rat renal carcinogenesis, at least in our present systems.     

Detection of Shigella gyrA mutations and correlations between gyrA mutations and quinolones resistance

Bacterial DNAgyrase is constituted by 2 A-sub-units and 2 B-subunits ,whichare encoded bygy-rAgene andgyrBgene ,respectively. Resistanceto quinolones in bacteriais mainly due tothe vari-ations of the bacterial DNAtopoisomerases ,typeⅡ(including DNAgyrase andtopoisomeraseⅣ) .This is because quinolones exert their antibacterialactivity by approachingthe bacterial DNAtopoiso-merases ,type Ⅱand disturbingtheir physiologicalfunctions. As variations occur in the bacterialDNA topoisomerase…     

Clear cell sarcoma of the stomach

AIMS: To investigate the role of the tumour suppressor gene PTEN in the tumorigenesis and growth of sporadic vestibular schwannomas, and to characterize the cellular distribution of the PTEN protein in relation to the MIB-1 proliferation index in these tumour. METHODS AND RESULTS: Immunoexpression of the PTEN protein was observed within the neoplastic Schwann cells in 21 out of 30 sporadic schwannomas examined (70%). PTEN expression was consistently stronger in Antoni A areas than in Antoni B areas. High levels of PTEN immmunoexpression in schwannomas were associated with an increased MIB-1 labelling index. Occasionally, vascular endothelial cells also showed PTEN immunoreaction. By polymerase chain reaction-single strand conformation polymorphism screening, no mutations were found in the complete protein coding region of the PTEN gene. CONCLUSIONS: The PTEN tumour suppressor gene is expressed in the majority of sporadic schwannomas. The maintained expression of the PTEN protein, together with the lack of detectable mutations in this gene, suggests that the function of the PTEN tumour suppressor gene is not altered in sporadic vestibular schwannomas.     

Molecular Diagnosis of Multiple Endocrine Neoplasia (MEN) in Paraffin-Embedded Specimens

In this article, we summarize our recent findings on rearranged during transfection (RET) mutations in a series of 46 sporadic as well as multiple endocrine neoplasia (MEN) type 2-associated tumors and present results of our family screening efforts to identify MEN 2 and MEN 1 gene carriers. A nonisotopic polymerase chain reaction-based single-strand conformation polymorphism (PCR-SSCP) analysis and heteroduplex gel electrophoresis method was used to screen DNA extracted from archival specimens of 22 patients with MEN 2-associated and 24 patients with sporadic tumors for mutations inRET exons 10, 11, 13, and 16. Point mutations were identified by nonisotopic cycle sequencing of PCR products using an automated DNA sequencer. We found six different missense germline mutations at cysteine residues encoded by exons 10 and 11 in all patients with MEN 2A or familial medullary thyroid carcinoma (FMTC). The frequency of mutations at codon 634 was higher in patients with MEN 2A than with FMTC and a₆₃₄ Cys→Arg mutation was associated with parathyroid disease. A germline Met→Thr point mutation at codon 918 of theRET tyrosine kinase domain encoded by exon 16 was identified in all MEN 2B patients. Nonpredicted inheritable medullary thyroid carcinomas (MTCs) were detected in two patients and a mosaic postzygotic mutation was found in one additional patient. Tumor-specific (somatic) Met→Thr point mutations at codon 918 were identified in 5 of 13 sporadic MTCs and 2 of 8 sporadic pheochromocytomas (PCCs). The remaining sporadic tumors lacked mutations in all fourRET exons tested. In exon 13, a nucleic acid polymorphism (CTT/CTG; Leu) at codon 769 was identified, which is present in approx 40% of the examined population. Our study demonstrates that the molecular methods used are not only suitable to identify asymptomatic individuals at risk for MEN 2A, FMTC, and MEN 2B, but also to distinguish sporadic from inherited tumors using archival tissue specimens; and that more tumors than clinically expected are inheritable, indicating the need for genetic analysis of all MTC and PCC patients.     

脂肪组织源性肿瘤与抑癌基因p53关系的研究

从蛋白表达及基因水平探讨脂肪组织源性肿瘤与p53基因的关系。方法　LSAB免疫组化法 ,PCR SSCP及DNA序列分析方法。结果　p53蛋白只在脂肪肉瘤中表达 ,阳性率为 4 8 0 8% ( 2 5 52 )。不同类型脂肪肉瘤 ,分化良好者阳性率 30 0 0 %( 9 30 ) ,低于分化较低者 (P <0 0 0 5) .p53第 6、7、8外显子PCR SSCP分析 ,2例多形性脂肪肉瘤出现异常泳动带。DNA序列分析证实 1例第 8外显子第 2 68位编码区出现错义突变 (AACATC) ,另 1例第 6外显子第 2 2 1位编码区出现可疑杂合同义突变 (GAGGAA)。结论　p53蛋白与脂肪肉瘤的形成及分化和恶性程度有关。p53蛋白表达可作为判断脂肪肉瘤分化程度及恶性程度参考指标之一。脂肪肉瘤中p53基因第 6、8外显子分别存在点突变。     

乳腺癌变过程中的P53基因点突变

目的：探讨乳腺癌变、发展与P53基因点突变的关系。方法：应用聚合酶链反应－单链构象多态性（PCR－SSCP）方法对87例癌前状态、癌症初期、癌症后期及正常乳腺组织的P53基因5－8外显子点突变进行检测。结果：3例癌前状态、8例癌症初期和14例癌症后期者发生点突变（突变率分别为15．8％、34．8％和63．6％）,三者（亦即乳腺癌变、发展过程）P53基因突变率（统计学结果）呈明显渐进性。结论：P53基因突变是乳腺癌的早期、多发事件,是引起乳腺癌变、发展的因素和标志之一。     

PCR-SSCP法检测非小细胞肺癌中E-cadherin基因突变的研究

目的 探讨E-cadherin基因突变在人非小细胞肺癌中的作用。方法 采用PCR－SSCP方法检测了53例非小细胞肺癌原发灶组织和5例肺部其他良恶性病变组织的E－cadherin基因突变的情况。结果 共有3例发生E-cadherin基因的突变。E-cadherin基因的突变与非小细胞肺癌的淋巴结转移情况有关（P＜0.005)，但与肿瘤的病理类型以及肿瘤的原发灶情况无关（P＞0.05)，而且在非小细胞肺癌与肺部其他病变之间，E-cadherin基因的突变无显著性差异。结论 E－cadherin基因能够较好地预测非小细胞肺癌的淋巴结转移情况。