从医学教育和医院管理看检验医师的定位和培养

近十年来,我国检验医学有了飞速地发展,检验诊断的新技术、新知识不断涌现,向临床提供的具有诊断价值的检验项目日益增多,具有高效、智能的全自动分析设备得到普遍应用,实验室信息系统(LIS)的使用进一步加快了与临床部门间快速地信息传输,许多临床疾病的诊断时间得以缩短,检验与临床的关系更趋紧密;高科技的自动化精密仪器替代了手工作坊式的操作,而对检验人员的素质也提出了新的要求,由此促进了检验医学高等教育规模不断扩大,临床检验人员的学历层次明显提高,对实验室的规范管理和质量意识的概念得到深入贯彻和实施,与国际接轨的实验室认…     

Spread of imipenem-resistant Acinetobacter baumannii of European clone II in Western China

The aim of this study was to investigate the distribution of resistance genes and the clonal relationship amongst imipenem-resistant Acinetobacter baumannii isolates from ten hospitals in Western China as well as to compare the molecular epidemiological data with those of isolates from two hospitals in Hangzhou and Beijing. Genes encoding OXA carbapenemases, metallo-β-lactamases, AmpC cephalosporinase and carbapenem resistance-associated outer membrane protein (CarO) were screened using polymerase chain reaction (PCR) and sequencing. PCR mapping was performed to determine whether insertion sequence ISAba1 elements preceded OXA carbapenemases and AmpC cephalosporinase. International clonal lineages were identified by sequence type multiplex PCR. Multilocus sequence typing (MLST) was performed to determine the sequence types (STs), and then eBURST algorithm was applied to assign clonal complexes (CCs). In this study, dissemination of acquired ISAba1 preceding the bla_OXA-23-like gene was the predominant enzymatic resistance mechanism amongst 272 imipenem-resistant isolates. Five isolates harboured the carO gene disrupted by insertion of ISAba1 and three isolates lacked carO. All of the 36 representative isolates belonged to European clone II. Ten STs, including three novel types, were identified. These STs were clustered into CC92 and two distinct singletons. These observations suggest that imipenem-resistant A. baumannii of European clone II, which carries acquired ISAba1 preceding the bla_OXA-23-like gene and belongs to CC92, has spread within Western China.     

Rare CpG island methylator phenotype in ulcerative colitis-associated neoplasias

BACKGROUND & AIMS: We previously reported that a high degree of age-related methylation was found in both the dysplastic and nondysplastic mucosa of patients with ulcerative colitis (UC). Whether this translates into hypermethylation in UC-associated cancers (UC-Cs) is not known. METHODS: We evaluated the methylation status of 11 genes (MINT1, 2, 31, hMLH1, p16, p14, MGMT, HPP1, SFRP1, ERalpha, and LINE-1) in 48 UC-Cs, 21 UC-associated dysplasias, and 69 sporadic colorectal cancers (S-CRCs) using a quantitative bisulfite pyrosequencing analysis. RESULTS: Methylation levels in UC-Cs were lower than S-CRCs for all the genes except MGMT. A methylation index based on the average of Z-scores, for type C (cancer-specific genes: MINT1, MINT2, MINT31, hMLH1, p16, and p14) was -.97 in UC-Cs and .92 in S-CRCs (P = .009). That of type A (age-related genes: HPP1, SFRP1, and ERalpha) was -1.97 in UC-Cs and 1.24 in S-CRCs (P < .001). We observed a significant difference in the incidence of CpG island methylator phenotype between UC-Cs and S-CRCs (8 of 48 [17%] and 26 of 69 [38%]; P = .022). UC-associated dysplasias had significantly higher methylation of type A gene than UC-Cs (Z-score: .07 and -1.97, respectively; P < .001). By contrast, global DNA methylation measured using a LINE-1 assay was significantly higher in UC-Cs than in S-CRCs (58.2% vs 51.0%, P < .001). CONCLUSIONS: DNA methylation alterations are uncommon in UC cancers. Given that both genetic and epigenetic changes are common in UC mucosa and dysplasias, we speculate that the genetic changes lead to a more aggressive clinical course than epigenetic changes.     

类风湿性关节炎疾病相关的特异性血清蛋白标志物

目的运用蛋白质指纹图谱技术筛选类风湿性关节炎(RA)患者血清中的特异性标志物,建立RA疾病相关的蛋白质组学诊断模型。方法采用弱阳离子纳米磁性微珠捕获血清蛋白,ProteinChip PBSII-C型蛋白质芯片阅读仪分别绘制性别年龄匹配的43例RA患者组及100例对照组(包括自身免疫性疾病对照组50例和正常对照组50例)的血清蛋白质指纹图谱,经Biomarker Wizard3.1软件分析蛋白峰后,再用Biomarker Patterns Software5.0软件筛查与RA疾病诊断密切相关的特异性血清蛋白标志物,建立RA诊断模型。结果在RA患者组中找到34个蛋白峰与对照组具有统计学差异(P<0.05),经Biomarker Patterns Software5.0软件识别,发现其中四个质荷比(m/z)分别为4966.89,5065.3,5636.97,7766.88的蛋白峰联合起来作为诊断模型,辨别RA患者及对照组的敏感性为86.36%,特异性为92.16%。对患者标本进行双盲验证,该诊断模型对RA的诊断敏感性为85.71%,特异性为87.76%。结论采用弱阳离子纳米磁性微珠与蛋白质芯片阅读仪联用的蛋白质指纹...     

Correlation between CpG methylation profiles and hormone receptor status in breast cancers

Introduction

Aberrant DNA methylation has been found frequently in human breast cancers, associated with the loss of expression of a number of regulatory genes for growth and correlated to clinical outcomes. The present study was undertaken to determine whether methylation of a set of growth-suppressor genes would correlate to the expression of estrogen receptors (ERs) and progesterone receptors (PRs).

Methods

We used a pyrosequencing methylation analysis to study the methylation of 12 known growth-suppressor genes in 90 pairs of malignant/normal breast tissues. We also examined the expression of ERs and PRs in those specimens by immunohistochemistry. Mutations of p53 in tumor cells were detected by direct sequencing.

Results

Twelve tumor-suppressor genes: ARHI, RASSF1A, HIN-1, RARβ2, hMLH1, 14-3-3 σ, RIZ1, p16, E-cadherin, RIL, CDH13, and NKD2 were selected for this methylation study. Five of them (RIL, HIN-1, RASSF1A, CDH13, and RARβ2) were frequently methylated in breast cancers (57%, 49%, 58%, 44%, and 17%, respectively) but not the normal breast (0–4%). Two panels of methylation profiles were defined. The methylation of the HIN-1/RASSFIA panel strongly correlated to the expression of ERs, PRs, and hormone receptors (HRs; which were defined as 'positive' if ERs and/or PRs were positive; p < 0.001). Conversely, the methylation of the RIL/CDH13 panel strongly correlated to negative ER, PR, and HR expression (p = 0.001, 0.025, and 0.001, respectively). The subset of triple-negative breast cancers (in other words, those with negative ER, PR, and HER-2/neu status) was positively associated with the methylation of the RIL/CDH13 panel and negatively associated with the HIN-1/RASSF1A panel. Mutations of p53 were found in nine breast tumors (11%), seven of which lacked methylation in both panels.

Conclusion

We have defined two panels (HIN-1/RASSFIA, and RIL/CDH13) of methylation profiles, which correlated, either positively or negatively, to HR status.     

Delta DNMT3B variants regulate DNA methylation in a promoter-specific manner

DNA methyltransferase 3B (DNMT3B) is critical in de novo DNA methylation during development and tumorigenesis. We recently reported the identification of a DNMT3B subfamily, DeltaDNMT3B, which contains at least seven variants, resulting from alternative pre-mRNA splicing. DeltaDNMT3Bs are the predominant expression forms of DNMT3B in human lung cancer. A strong correlation was observed between the promoter methylation of RASSF1A gene but not p16 gene (both frequently inactivated by promoter methylation in lung cancer) and expression of DeltaDNMT3B4 in primary lung cancer, suggesting a role of DeltaDNMT3B in regulating promoter-specific methylation of common tumor suppressor genes in tumorigenesis. In this report, we provide first experimental evidence showing a direct involvement of DeltaDNMT3B4 in regulating RASSF1A promoter methylation in human lung cancer cells. Knockdown of DeltaDNMT3B4 expression by small interfering RNA resulted in a rapid demethylation of RASSF1A promoter and reexpression of RASSF1A mRNA but had no effect on p16 promoter in the lung cancer cells. Conversely, normal bronchial epithelial cells with stably transfected DeltaDNMT3B4 gained an increased DNA methylation in RASSF1A promoter but not p16 promoter. We conclude that promoter DNA methylation can be differentially regulated and DeltaDNMT3Bs are involved in regulation of such promoter-specific de novo DNA methylation.     

Drug sensitivity prediction by CpG island methylation profile in the NCI-60 cancer cell line panel

Aberrant promoter hypermethylation and associated gene silencing are epigenetic hallmarks of tumorigenesis. It has been suggested that aberrant DNA methylation can affect the sensitivity of cancers to antineoplastic agents by altering expression of genes critical to drug response. To study this issue, we used bisulfite PCR to assess DNA methylation of 32 promoter-associated CpG islands in human cancer cell lines from the National Cancer Institute (NCI) drug-screening panel (NCI-60 panel). The frequency of aberrant hypermethylation of these islands ranged from 2% to 81% in NCI-60 cancer cells, and provided a database that can be analyzed for the sensitivity to approximately 30,000 drugs tested in this panel. By correlating drug activity with DNA methylation, we identified a list of methylation markers that predict sensitivity to chemotherapeutic drugs. Among them, hypermethylation of the p53 homologue p73 and associated gene silencing was strongly correlated with sensitivity to alkylating agents. We used small interfering RNA to down-regulate p73 expression in multiple cell lines, including the resistant cell lines TK10 (renal cancer) and SKMEL28 (melanoma). Down-regulating p73 substantially increased sensitivity to commonly used alkylating agents, including cisplatin, indicating that epigenetic silencing of p73 directly modulates drug sensitivity. Our results confirm that epigenetic profiles are useful in identifying molecular mediators for cancer drug sensitivity (pharmaco-epigenomics).