目的：探讨对氧磷酶1(paraoxonase1，PON1)基因启动子区甲基化水平和端粒长度与中国山东地区汉族人群脑梗死发病的相关性。方法：选取152例确诊脑梗死患者为病例组，152例健康人为对照组，提取外周静脉血基因组DNA，使用荧光定量甲基化特异性PCR(quantitative methylation-specific PCR，qMSP)测定受试者的血液PON1基因启动子甲基化水平及端粒长度。每个样本的甲基化程度以甲基化参考百分比(PMR)来表示。结果：病例组中PON1甲基化程度显著高于对照组(Z=−3.898，P=0.0001)，性别亚组显示差异主要在男性中更为显著(Z=−3.786，P=0.0002)。病例组患者的端粒长度显著低于对照组(Z=−11.843，P<0.0001)，且男女亚组中端粒长度均显著低于对照组(P<0.05)。然而，并没有发现PON1甲基化水平与端粒长度的相关性(病例组r=0.023，P=0.775；对照组r=−0.157，P=0.054)。结论：PON1启动子区高甲基化和端粒长度变短与脑梗死发病相关，是中国山东地区汉族人群脑梗死发病的危险因素。

Objective To construct a subtractive cDNAs library of genes down-regulated in hepatic stellate cells treated with glycyrrhizin using suppression subtractive hybridization(SSH) technique so as to illustrate the mechanism of glycyrrhizin in liver cirrhosis from the angle of molecular biology. Methods The mRNAs were isolated from hepatic stellate cells untreated and treated with glycyrrhizin and by reverse transcription the cDNAs were synthesized and designated as tester and driver,respectively.After restriction enzyme RsaI digestion,small sizes cDNAs were obtained.Tester cDNAs were subdivided into two portions and each was ligated with different cDNAs adaptor.After tester cDNAs were hybridized with driver cDNAs twice and underwent nested polymerase chain reaction(PCR) twice,the DNA fragments were subcloned into T/A plasmid vectors to set up the subtractive cDNAs library.Amplification of the library was carried out with DH5α.The cDNAs were sequenced and analyzed in GenBank with Blast search after colony PCR. Results The subtractive cDNAs library of genes down-regulated in hepatic stellate cells treated with glycyrrhizin was constructed successfully.The amplified library contained 15 positive clones.Colony PCR showed that these clones contained 200-1 000 bp inserts.Ten clones were analyzed by sequencing and bioinformatics.Four known genes genes were obtained,including damage-specific DNA binding protein 1(Ddb1),Toll/interleukin-1 receptor-like protein 3(TIL3),squalene epoxidase and actin-binding double-zinc-finger protein(abLIM). Conclusion A subtractive cDNAs library of genes down-regulated in hepatic stellate cells treated with glycyrrhizin using SSH technique is constructed successfully,which provides theoretic base for illustrating the regulatory mechanism of glycyrrhizin in liver cirrhosis.