定量分析铜绿假单胞菌第一类整合酶基因的表达

目的整合于是具有整合和表达外来耐药性基因盒能力的基因元件。在细菌耐药性基因的积累和传递中起重要作用。本研究通过定量分析第一类整合子整合酶基因（intI1）在细菌不同生存状态的表达水平，探讨整合子的作用机制。方法培养和提取两株第一类整合子阳性铜绿假单胞菌的液相培养菌、生物被膜菌、被膜脱落菌等三种生长状态的总RNA，采用竞争RT-PCR方法定量检测菌体在以上三种状态下intI1 mRNA的表达水平。结果铜绿假单胞菌的液相培养菌、生物被膜菌和被膜脱落菌都有intI1 mRNA表达；两株菌在三种状态下intI1 mRNA的表达量不同，其中生物被膜菌表达最高，被膜脱落菌次之，液相培养菌最低；生物被膜菌intI1 mRNA的量较液相培养物高约15倍，较被膜脱落菌高约4倍。结论铜绿假单胞菌intI1在生物被膜中mRNA表达上调，随着菌体从被膜脱落以及菌体持续的液相培养intI1表达下调。提示整合子在生物被膜菌中可进行活跃的基因盒的捕获、移动和积累。有利于细菌耐药性的提高及扩散。     

铜绿假单胞菌lasR/rhlR基因缺陷对小鼠腹腔生物被膜感染的影响

目的 探讨铜绿假单胞菌(PA)群体感应(QS)系统的lasR/rhlR基因缺陷对小鼠腹腔PA生物被膜(BF)感染的影响.方法 体外利用无菌引流管切片建立铜绿假单胞菌PAO1野生型和PAO1 lasR/rhlR基因缺陷型菌株生物被膜感染的载体,将两种感染载体和无菌载体分别移植至正常小鼠腹腔构建生物被膜感染模型,术后3d检...     

铜绿假单胞菌群体感应系统及其抑制剂的研究进展

铜绿假单胞菌耐药严重,形成的感染严重威胁患者健康.群体感应是细菌密度依赖的群体调控行为.细菌利用可扩散的信号分子监控周围同种或异种细菌的密度,调控特定基因的适时、协同表达.群体感应系统参与调控铜绿假单胞菌的致病性和耐药性,备受关注.深入研究铜绿假单胞菌的群体感应系统,可阐明该菌的群体行为调控机制及致病机制,由此研发铜绿假单胞菌群体感应系统的抑制剂,对缓解该菌的耐药并根除其感染具有重要意义.本文就铜绿假单胞菌群体感应系统及其抑制剂的研究进展做一综述.     

铜绿假单胞菌中Ⅰ类整合子及携带的耐药基因研究

目的 了解整合子在广州地区铜绿假单胞菌中的分布状况及其主要类型,研究Ⅰ类整合子的结构特征并探讨其与细菌多重耐药之间的相关性.方法 采用PCR检测3类整合子整合酶的编码基因,并扩增整合子的可变区,运用DNA测序技术分析整合子可变区的耐药基因及其排列顺序,利用生物信息学的方法对检测到的可变区基因序列进行比对分析.结果 在20株产金属β-内酰胺酶铜绿假单胞菌中,15株检测到Ⅰ类整合子,未检测到Ⅱ类和Ⅲ类整合子,其中一株铜绿假单胞菌整合子全长序列含有Ⅰ类整合子整合酶、Aac A4氨基糖甙乙酰转移酶、IMP-25金属β-内酰胺酶、OXA-30 β-内酰胺酶和Cat B3氯霉素乙酰转移酶的编码基因及其相应的基因重组位点,GenBank登录号为EU588392,其中IMP-25为一个新的金属β-内酰胺酶亚型.结论 广州地区铜绿假单胞菌中存在的整合子类型是Ⅰ类整合子,并且该整合子可变区携带多种耐药基因盒,其中一个是金属β-内酰胺酶新亚型IMP-25,在分子水平上阐述了I类整合子参与铜绿假单胞菌对抗生素的耐药性和多重耐药性.     

铜绿假单胞菌中整合子的分布及其可转移耐药性研究

目的 研究淮北地区Ⅰ类、Ⅱ类整合子在多重耐药铜绿假单胞菌(PA)中分布及其可转移耐药情况.方法 用聚合酶链反应(PCR)技术榆测多重耐药菌中整合子基因,并对整合酶基因阳性菌株进行转移接合试验;采用K-B法对接合转移成功菌株及接合子进行13种药物敏感试验.结果 多重耐药铜绿假单胞菌中Ⅰ类整合子检出率为86.1%,未检出Ⅱ类整合子,含整合酶基因的接合子在转移成功接合子中所占比率为35.7%.结论 淮北地区铜绿假单胞菌中整合子的分布以Ⅰ类整合子为主,且水平传播率达到35.7%,应引起高度重视.     

铜绿假单胞菌Ⅰ类整合子相关基因的解析和定位

目的对4株铜绿假单胞菌临床菌株携带的Ⅰ类整合子相关基因进行解析和定位,探讨Ⅰ类整合子相关基因在细菌耐药性形成和耐药基因播散中的作用。方法采用PCR扩增、DNA测序、DNA序列比对的方法对4株铜绿假单胞菌临床菌株携带的Ⅰ类整合子相关基因进行解析,采用接合试验对该类整合子进行定位分析。结果4株铜绿假单胞菌I类整合子都含有耐药基因,该耐药基因在相应菌株中发挥耐药作用;该菌整合子位于质粒上。结论Ⅰ类整合子耐药基因在铜绿假单胞菌耐药性形成和耐药基因的播散中发挥作用。     

5个恶唑烷酮类新化合物对铜绿假单胞菌群体感应系统的抑制研究

目的 以铜绿假单胞菌PAO1为模式菌,研究恶唑烷酮类新化合物对铜绿假单胞菌群体感应系统的抑制作用及其作用机制。方法 测定5个恶唑烷酮类新化合物对PAO1生物膜、绿脓菌素、运动能力抑制活性,采用qRT-PCR测试其对群体感应相关基因的下调作用,并评估化合物对秀丽隐杆线虫感染模型的保护活性。结果 化合物SIIA-MA2与SIIA-MA4对PAO1生物膜、绿脓菌素、运动能力具有较强的抑制活性,其作用机制均是并显著下调PAO1中10个已知的受群体感应系统正调控的基因。化合物SIIA-MA2与SIIA-MA4对秀丽隐杆线虫感染模型具有良好的体内保护活性,其中化合物SIIA-MA2对急性感染模型具有显著保护活性;化合物SIIA-MA4对慢性感染模型具有显著保护活性。结论 恶唑烷酮类新化合物SIIA-MA2和SIIA-MA4通过抑制PAO1群体感应系统发挥抗感染作用。     

多尼培南对铜绿假单胞菌生物被膜形成和群体感应系统的影响

目的：探究新型碳青霉烯类抗生素多尼培南（doripenem,DOR）对临床分离铜绿假单胞菌生物被膜形成的抑制作用,及对其群体感应系统相关基因LasR、RhlR、PqsA、PqsE、PqsR表达量的影响。方法：用结晶紫染色法测定30株临床分离铜绿假单胞菌形成生物被膜能力和多尼培南对生物被膜形成的抑制作用;微量肉汤稀释法测定最低抑菌浓度（minimal inhibitory concentration,MIC）和最低抑制生物被膜浓度（minimal biofilm inhibitory concentration,MBIC）;活菌计数法绘制多尼培南对生物被膜内细菌的杀菌曲线;采用实时定量荧光PCR （real-time PCR）法测定多尼培南对群体感应（quorum-sensing,QS）系统相关基因表达量的影响。结果：30株铜绿假单胞菌中的29株（97%）形成生物被膜;多尼培南具有较强的抗铜绿假单胞菌浮游菌和生物被膜抑制活性,MICR为0.5～1μg·mL-1,MBICR为1～4μg·mL-1;显著下调LasR、RhlR、PqsA、PqsE、PqsR的表达量。结论：临床分离铜绿假单胞菌具有高生物被膜形成率,多尼培南对铜绿假单胞菌生物被膜具有抑制作用,可能与其下调QS系统相关基因有关。     

D-环丝氨酸抑制铜绿假单胞菌群体感应活性研究

摘要：目的 以铜绿假单胞菌模式菌株PAO1为研究对象,研究抗结核药物D-环丝氨酸通过靶向抑制病原菌群体感应 (quorum-sensing,QS)系统实现抑制病原菌毒力发挥的新应用潜力。方法 用不同浓度的D-环丝氨酸处理铜绿假单胞菌,通过 系列表型实验结合荧光定量PCR以评估D-环丝氨酸对群体感应所调节的毒力因子和相应基因表达的影响,并利用秀丽隐杆线虫 感染模型评估D-环丝氨酸对铜绿假单胞菌毒力抑制的体内活性。结果 D-环丝氨酸表现出良好的铜绿假单胞菌生物膜、绿脓菌 素以及蛋白水解酶抑制活性,显著抑制了QS系统调控基因和下游功能基因的表达,并且可以显著提高秀丽隐杆线虫在铜绿假单 胞菌感染过程的存活率。结论 D-环丝氨酸可以有效抑制铜绿假单胞菌群体感应系统,有望开发成功的抗生素替代药物。     

一株铜绿假单胞菌携带多种耐药基因的研究

目的：了解分离自烧伤患者的铜绿假单胞菌携带的耐药基因情况。方法：应用聚合酶链反应对多重耐药的铜绿假单胞菌进行β-内酰胺酶基因、氨基糖苷类修饰酶基因、oprD2基因和消毒剂-磺胺耐药相关基因以及Ⅰ类整合酶基因检测和分析。结果：PCR结果显示TEM、GES型β-内酰胺酶基因，aac（6’）-Ⅰ、ant（2″）-Ⅰ氨基糖苷类修饰酶基因扩增阳性。oprD2基因扩增检测呈缺失型。qacEΔ1-sulⅠ、intⅠ1基因扩增阳性。结论：铜绿假单胞菌携带多种抗生素灭活酶及耐消毒剂和Ⅰ类整合酶基因。多重耐药铜绿假单胞菌的逐渐增多，严重威胁烧伤抗感染治疗。     

Characterization of the humanMDR1 gene

P-glycoprotein (Pgp), an ATP-dependent efflux transporter that protects the body from environmental toxins and xenobiotics, is encoded by the human MDR1 gene. Human MDR1 is located on chromosomal region 7q21. Although several different single nucleotide polymorphisms were shown to influence Pgp expression and activity, the reported length of the MDR1 gene in Genbank and other databases continues to evolve and varies between 6.3 kilobases (kb) and 210 kb. With DNA derived from human cell lines and tissues, we have characterized the MDR1 genomic sequence to be 209 kb.     

Novel nonsynonymous polymorphisms of the CYP1A1 gene in Japanese

We found five novel nonsynonymous polymorphisms of the human CYP1A1 gene from Japanese individuals. The five single nucleotide polymorphisms (SNP) in exon 7 (2346_2347 ins T, 2414T>A, 2461C>T, 2500C>T and 2546C>G causing premature stop codon, Ile(448)Asn, Arg(464)Cys, and Arg(477)Trp and Pro(492)Arg, respectively) were as follows:SNP, 030212Saito001; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5'-GTCAACCCATCT-/TGAGTTCCTACCT-3'.SNP, 030212Saito002; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5'-GTGAGAAGGTGAT/ATATCTTTGGCAT-3'.SNP, 030212Saito003; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5'-GAGACCGTTGCCC/TGCTGGGAGGTCT-3'.SNP, 030212Saito004; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5'-ATCCTGCTGCAAC/TGGGTGGAATTCA-3'.SNP, 030212Saito005; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5'-TGGACATGACCCC/GCATCTATGGGCT-3'.     

Clinical aspects of the MDR1 (ABCB1) gene polymorphism

Transporter proteins, in particular P-glycoprotein (Pgp), are important determinants in absorption, tissue targeting, and elimination of drugs. In addition to physiological and environmental factors, its expression and function are modified by genetic polymorphisms of the MDR1 gene. So far, several MDR1 SNPs have been identified, and mutations at positions 2677 and 3435 were associated with alteration of Pgp expression and/or function. In contrast to drug-metabolizing enzymes (eg, CYP2D6), for which loss of function mutations or gene amplification manifests as distinct phenotypes in the population, the impact of MDR1 polymorphisms on pharmacokinetics and pharmacodynamics of Pgp substrates is moderate. Clinical studies on the effects of the C3435T polymorphism and drug treatment with cardiac glycosides, the immunosuppressants cyclosporine and tacrolimus, HIV protease inhibitors, and tricyclic antidepressants are discussed.     

Variations of the bilirubin uridine-diphosphoglucuronosyl transferase 1A1 gene in healthy Taiwanese

The activity of uridine-diphosphoglucuronosyl transferase 1 (UGT1) may influence the concentration of serum bilirubin. Because UGT1 is too labile to be measured with classical biochemical methods, we analysed the whole UGT1A1 gene in 290 healthy Taiwanese adults by using the polymerase chain reaction method, and investigated the relationship between UGT1A1 genotypes and serum bilirubin levels. The results showed that slightly more than 50% of the subjects had one or more variant sites in UGT1A1 gene. The most common variant was A(TA)6TAA/A(TA)7TAA (6/7) in the promoter area, followed by heterozygous variation within the coding region, compound heterozygous and homozygous variations. Among the four variant sites within the coding region, 211 G to A was the predominate one, 1091 C to T was a novel variation, and 686 C to A was associated with 6/7. Subjects with 6/7 or heterozygous variation within the coding region or compound heterozygous (plus one homozygous) variation had significantly higher bilirubin levels than those with wild UGT1A1 gene. When the 290 subjects were stratified into six groups according to their serum bilirubin concentrations, the bilirubin levels were correlated well to the frequencies of variant UGT1A1 gene. Our results show that there is a strong association between UGT1A1 gene and bilirubin levels in healthy Taiwanese adults. The occurrence of A(TA)7TAA allele was relatively rare and the variation rate within the coding region was much higher in Taiwanese compared to that in Caucasians.     

Regulation of CYP1A1 gene expression by the antioxidant tert-butylhydroquinone.

CYP1A1, a major phase I enzyme, plays an important role in the metabolism of polycyclic aromatic hydrocarbons and in the chemical activation of xenobiotics to carcinogenic derivatives. The phenolic antioxidant tert-butylhydroquinone (tBHQ), often used as a food preservative, is generally considered to act only as a mono-functional inducer of phase II enzymes, thereby exerting chemo-protection. However, we recently observed that tBHQ elevated the activity of an aryl hydrocarbon receptor (AhR) response element (DRE)-driven luciferase reporter in human colon carcinoma cells (Caco-2). Therefore, we studied the effects of tBHQ on the activity of a DRE-driven reporter, CYP1A1 mRNA expression, and CYP1A enzyme activity in Caco-2 cells and human HepG2 hepatoma cells. We found tBHQ caused induction of reporter activity and CYP1A1 expression and activity in Caco-2 and HepG2 cells. Moreover, tBHQ combined with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increased reporter activity and mRNA expression in Caco-2 cells in an additive manner. By contrast, tBHQ decreased TCDD-mediated induction of reporter activity and CYP1A1 mRNA expression in HepG2 cells. Resveratrol, an AhR antagonist, repressed the induction of CYP1A1 by tBHQ. Cotransfection of HepG2 cells with a dominant negative AhR nuclear translocator mutant abolished the tBHQ-induced CYP1A1 reporter activity. These findings indicate that CYP1A1 may be induced by the antioxidant tBHQ via an AhR-dependent mechanism.     

Single-step identification of all length polymorphisms in the UGT1A1 gene promoter

AIM: To provide a sensitive genetic screening method for rapid identification of all known length polymorphisms in the promoter region of the uridine 5'-diphosphoglucose glucuronosyltransferase (UGT) 1A1 gene comprising (TA)5, (TA)7 and (TA)8 repeats as opposed to the non-mutated (TA)6 allele. METHODS: The UGT1A1 promoter genotype was assessed in 115 subjects by means of a newly developed pyrosequencing method. PCR-generated DNA templates of heterozygous (TA)5 and (TA)7 carriers were cloned into a TOPO TA vector and verified by sequencing. In addition, a (TA)8 segment was produced by cloning to demonstrate the ability of the method to detect this mutation. RESULTS: All length polymorphisms of the UGT1A1 promoter described in the literature were clearly identified. Fifteen subjects had Gilbert's syndrome with elevated serum bilirubin associated with a homozygous (TA)7TAA/(TA)7TAA genotype. Two subjects with the rare genotypes (TA)5TAA/(TA)6TAA and (TA)5TAA/(TA)7TAA were found, where only the latter one displayed elevated serum bilirubin levels. Allelic frequencies were 0.9%, 66.1% and 33% for the (TA)5TAA, (TA)6TAA and (TA)7TAA allele, respectively. CONCLUSION: Our method enables reliable genetic single-step screening for all known length polymorphisms in the UGT1A1 gene promoter that cause Gilbert's syndrome. This facilitates pharmacogenetic-guided dosing of drugs with known toxicity metabolized by UGT1A1.