结核病及其易感基因的最近研究进展

结核的发展是多原因综合作用结果,随着人类的基因组计划完成,多个易感性基因已经被发现,中国是结核病高发国家,进行结核病因学探讨,可有效地推动结核病防治,这些易感基因的发现和研究对于建立和健全结核预防和控制措施起到不可忽视的作用。据调查,全世界大约1/3人数感染过结核菌,年均约300万人死于结核病,此病是单个感染因素引起病死率最高的病种。而感染者中仅1/10患病,提示结核病易感性与个体差异可能相关。有研究表明结核病的遗传易感性或抗性由多个基因共同控制,结核病易感性差异可能是由少数几个主效基因或多个微效基因共同决定的。宿主对结核菌的易感程度受遗传背景影响,宿主的免疫基因改变可能影响抗结核的免疫能力,影响其T细胞的调节作用和巨噬细胞的吞噬和清除能力,从而结核病临床表现以及其特征被影响。     

结核易感基因-VDR基因的研究进展

随着人类基因组计划的完成和功能基因组学研究的进展,多种结核病易感基因被发现,其中VDR基因是主要的结核易感基因之一,国内外学者对其功能和作用机制进行了研究,并对其多态性在不同种族人群中进行了关联研究及家系连锁分析,探讨VDR基因的多态性与结核病易感性的关联,为揭示结核分枝杆菌感染的种族易感性差异机制奠定了理论基础.本文对这方面的研究进展做一综述.     

结核病易感基因的研究进展

结核病在全世界一直以来都是一种重要的感染性疾病,然而仅1／10的感染者发病。除环境和暴露因素外,宿主遗传因素对引发结核起到不可忽视的作用…。已有研究表明几个候选基因与结核病易感有关,如自然抗性相关巨噬细胞蛋白l（Nrampl或Sicl1a1）基因、维生素受体（VDR）基因、人类白细胞抗原（HLA）．DR2、甘露糖结合凝集素（MBL）基因等。这些易感基因的发现和研究对于建立和健全结核病预防和控制措施起到不可忽视的作用。     

ASAP1基因影响结核易感性的研究进展

近年来,通过全基因组关联分析筛选结核病易感基因取得了丰硕成果,其中ASAP1作为新发现的结核易感基因引起了国内外广泛的关注。同时,关于ASAP1基因多态性影响人类结核易感性的生物学机制得到了初步的科学实验验证,为进一步高效精准地预防、控制和治疗人类结核病提供了可能。本文对ASAP1基因的功能和其多态性与结核病的相关性研究进行综述,初步总结ASAP1蛋白影响结核遗传易感的机制,为今后启发研究者充分考虑病原体、宿主、环境多因素及他们的相互作用来科学研究结核病易感性奠定基础。     

溃疡性结肠炎基因多态性的研究进展

溃疡性结肠炎(ulcerative colitis,UC)的发病是多基因参与、作用于免疫系统和靶器官的疾病.对UC全基因组多态性的研究发现其存在许多易感基因,本文从UC高频易感基因及新发现易感基因等方面总结UC基因多态性研究进展.     

CD第一个易感基因NOD2及其与CD易感性的研究进展

目前认为克罗恩病(CD)是遗传易感者受环境因素作用而发病,其发病符合多基因病的遗传规律[1],其遗传易感性主要表现在家族聚集现象及双胞胎共患率上[2].近年来,随着人类基因组计划的进展和多基因病研究及统计学方法的发展,已发现了人类CD的第一个易感基因-NOD2基因,现命名为CARD15基因,本文就NOD2基因及其与CD易感性的研究进展作一综述.     

飞行时间质谱与TaqMan探针技术在结核病易感性相关基因单核苷酸多态性筛选中的应用

目的 对比分析飞行时间质谱技术（MALDI-TOF）和TaqMan探针筛选与结核病易感性相关单核苷酸多态性（SNP）位点的结果,以及联合应用的方法学和效果评价.方法 选取2010年10月至2011年4月在深圳市第三人民医院收治并确诊的结核病患者400例为结核病组,对照组为同时期收集的健康体检者300名,利用MALDI-TOF对选取的7个SNP位点（rs2227476、rs1800795、rs56077270、rs1800797、rs2227484、rs2227472和rs2227473）同时进行基因分型,初步筛选易感SNP位点;与结核病易感相关的单个SNP位点,采用基于TaqMan探针技术的实时荧光定量PCR对同样的标本再进行基因分型,比较两种方法的准确性与敏感度;以rs2227473位点为实例对分型结果的基因频率进行分析,确定肺结核的易感SNP.结果 MALDI-TOF分型成功率为99.7％（698/700）,TaqMan探针技术为98.4％（689/700）;在基因分型过程中,MALDI-TOF与TaqMan探针方法对1例标本的分型结果不一致,经过对此分型结果进行了测序验证,MALDI-TOF的分型结果正确,MALDI-TOF在准确性和敏感度比TaqMan法稍高.位点rs2227473基因频率分析中,结核病组G等位基因频率（90.3％,722/800）明显高于对照组（82.5％,495/600）（x2=6.911,P=0.009）.结论 上述肺结核易感基因的筛选方法是可行的;实例分析中,将两种方法联合应用,发现了IL-22基因rs2227473位点等位基因G可能与肺结核发病相关,两位点中等位基因A可能为保护性基因.     

胶原蛋白基因与颅内动脉瘤

颅内动脉瘤多因局部脑动脉管壁先天性缺陷和腔内压力增高引起.遗传、吸烟、高血压、脑动脉硬化及血管炎等因素与其发生、发展有关.近年来,随着基因芯片技术的应用,颅内动脉瘤相关致病基因的研究得到了进一步深入,发现了一些与颅内动脉瘤发生密切相关的易感基因,提示颅内动脉瘤可能是一种由多个基因共同作用的多基因疾病.     

弥漫性甲状腺肿伴甲状腺功能亢进症致病易感基因识别鉴定研究的现状

经过半个世纪对弥漫性甲状腺肿伴甲状腺功能亢进症(Graves’disease,GD,甲亢)候选基因在小样本人群中的研究,提供了不少相互矛盾的结果.在这些研究中,仅仅证实主要组织相容性复合物(MHC)是甲亢的一个致病易感位点,因为这个位点对甲亢发生影响较大.应用以低密度的微卫星标志进行全基因组连锁分析,虽然发现了一些甲亢的致病易感区段,但并未能识别真正的甲亢致病易感基因.随后由于大量单核苷酸多态性(SNP)的发现及其标签SNP(Tag SNP)技术的出现,人们对候选基因上的Tag SNP在大样本人群中的分析,发现了一些真正的甲亢致病易感基因,包括免疫相关的基因如MHC、CTLA4、SCGB3A2/UGRP1和FCRL3以及一个甲状腺特异的基因TSHR(促甲状腺素受体基因).同时,也发现了一些还有争议但需要进一步证实的甲亢易感基因如PTPN22和甲状腺球蛋白基因等.在不久的将来,全基因组关联分析和全基因组再测序技术,在甲亢易感基因识别鉴定中的应用,无疑将会促进大量甲亢易感基因的发现,加深人们对甲亢发病机制的理解.     

抗结核药物性肝损伤易感基因研究进展

结核病化疗疗程长,常用的抗结核治疗的一线药品(如异烟肼和利福平)均具有潜在的肝毒性,易引发抗结核药物性肝损伤(anti-tuberculosis drug-induced liver injury,ATLI),从而导致治疗效果低下和用药无效,继而诱发耐药结核病,增加治疗的困难及患者的负担。ATLI具有明显的个体差异性,而这种差异性很大程度上是由基因所引起的。但是国内尚没有对ATLI易感基因研究进展的相关综述,笔者通过对国内外ATLI易感基因的相关研究进展进行综述,为临床治疗及预防提供参考。     

基于网络的哮喘易感基因研究新策略

哮喘易感基因的研究正在世界各地许多实验室蓬勃开展,由于此种疾病的复杂性和异质性等原因,哮喘易感基因的鉴定依然任重而道远。目前的研究表明,哮喘所涉及的染色体达10多条,与其关联或连锁的候选易感基因多达170多个,但多数研究结果的一致性和重复性较差。分析其中的原因,除了哮喘的复杂性、种族的差异、病例的选择与分层的不同外,研究策略、技术路线和方法应该是导致结果不一致的主要原因之一。本文基于系统生物学理论与候选基因的方法,系统阐述一种哮喘易感基因研究的新策略。     

Ciprofloxacin: in vitro activity, mechanism of action, and resistance

Ciprofloxacin is a new fluoroquinolone that is highly active against many diverse microorganisms. At concentrations of less than 1 microgram/mL it is active against most gram-negative bacteria, including Enterobacteriaceae, Haemophilus, Neisseria, and other Pasteurellaceae, Vibrionaceae, and various species of Pseudomonas and Acinetobacter. Most staphylococci, including strains resistant to methicillin, are also susceptible to ciprofloxacin. Streptococci are not highly susceptible to ciprofloxacin, and obligate anaerobes are generally resistant to this and other quinolones. Ciprofloxacin, like other quinolones, inhibits DNA gyrase, but its bactericidal effects are not completely reversible by inhibitors of protein or RNA synthesis. Thus, unlike many other quinolones, ciprofloxacin may have multiple lethal effects. Resistance is less readily selected in vitro by ciprofloxacin than by nalidixic acid, and single-step mutants usually remain susceptible to clinically achievable concentrations. Resistance mediated by mutations in genes altering DNA gyrase and expression of outer membrane proteins has been described for ciprofloxacin and other quinolones. The antimicrobial spectrum and potency of ciprofloxacin, coupled with its rapid bactericidal effects, make this fluoroquinolone a promising new antimicrobial agent.     

Abrogation of disease development in plants expressing animal antiapoptotic genes

An emerging topic in plant biology is whether plants display analogous elements of mammalian programmed cell death during development and defense against pathogen attack. In many plant-pathogen interactions, plant cell death occurs in both susceptible and resistant host responses. For example, specific recognition responses in plants trigger formation of the hypersensitive response and activation of host defense mechanisms, resulting in restriction of pathogen growth and disease development. Several studies indicate that cell death during hypersensitive response involves activation of a plant-encoded pathway for cell death. Many susceptible interactions also result in host cell death, although it is not clear how or if the host participates in this response. We have generated transgenic tobacco plants to express animal genes that negatively regulate apoptosis. Plants expressing human Bcl-2 and Bcl-xl, nematode CED-9, or baculovirus Op-IAP transgenes conferred heritable resistance to several necrotrophic fungal pathogens, suggesting that disease development required host-cell death pathways. In addition, the transgenic tobacco plants displayed resistance to a necrogenic virus. Transgenic tobacco harboring Bcl-xl with a loss-of-function mutation did not protect against pathogen challenge. We also show that discrete DNA fragmentation (laddering) occurred in susceptible tobacco during fungal infection, but does not occur in transgenic-resistant plants. Our data indicate that in compatible plant-pathogen interactions apoptosis-like programmed cell death occurs. Further, these animal antiapoptotic genes function in plants and should be useful to delineate resistance pathways. These genes also have the potential to generate effective disease resistance in economically important crops.     

血压的性别差异及其生物学意义

目的 原发性高血压是世界上公认的多基因疾病.尽管人类基因组计划的完成大大加快了许多单基因疾病的基因的鉴定,但与原发性高血压相关基因的克隆仍然是生物医学研究面临的巨大挑战,其日益高涨的发病率及心血管并发症的高死亡率向人们提出了一个非常紧迫的问题,即怎样才能有效鉴定原发性高血压这个多基因疾病的相关基因.早在一百多年前,研究者就发现高血压有着明显的性别差异.并且,在许多少数民族人群中,男性与女性相比,不仅有着有着较高的平均生理血压值,而且还有着较高的高血压发病率.使男性有着较高生理血压值的基因或遗传多态性可能是高血压的易感因素,而激素相关基因或印迹基因则被认为参与了生理血压和高血压的性别差异的形成.此外,在临床实践中,血压的性别差异对促高血压药物或抗高血压药物的反应也有着显著的临床意义.因此,较好地了解血压的性别差异的分子遗传学可以有效地完成高血压形成相关基因鉴定,并最终促进高血压病的诊断和治疗的发展.本文主要揭示了血压的性别差异现象及其在基础血压研究和高血压相关的临床实践中的影响.

Abstract：

The ever-increasing incidence of hypertension and the high death rate of cardiovascular diseases raise an issue of how to efficiently identify genes associated with the polygenic diseases of hypertension. Significant gender differences in hypertension have been recognized over one hundred years. Males have higher average values of blood pressure as well as higher incidence of hypertension as compared to females in many ethnic groups. Genes or genetic polymorphisms governing the higher normal value of blood pressure in males may be the susceptible factors of hypertension. Hormone related genes or imprinting genes are considered as involvement in the development of gender differences of normal blood pressure and hypertension. The gender differences in responding to pro-hypertensive or anti-hypertensive agents have clinical implications in clinical practice. Additionally, better understanding the molecular genetics of normal blood pressure differences between genders may yield the identification of genes associated with the development of hypertension and eventually benefit to the diagnosis and therapeutics of hypertension.     

Genetic variation between susceptible and non-susceptible snails to Schistosoma infection using random amplified polymorphic DNA analysis (RAPDs)

Susceptibility of snails to infection by certain trematodes and their suitability as hosts for continued development has been a bewildering problem in host-parasite relationships. The present work emphasizes our interest in snail genetics to determine what genes or gene products are specifically responsible for susceptibility of snails to infection. High molecular weight DNA was extracted from both susceptible and non-susceptible snails within the same species Biomphalaria tenagophila. RAPD was undertaken to distinguish between the two types of snails. Random primers (10 mers) were used to amplify the extracted DNA by the polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and silver staining. The results suggest that RAPD represents an efficient means of genome comparison, since many molecular markers were detected as genetic variations between susceptible and non-susceptible snails.     

2型糖尿病易感基因定位研究

2型糖尿病是多基因复杂遗传疾病,使用关联分析、定位克隆、定位候选克隆和全基因组关联分析的方法可定位其易感基因.本文主要介绍近年2型糖尿病易感基因定位的研究进展.     

Optimizing therapy for infections caused by enterobacteriaceae producing extended-spectrum beta-lactamases

The spread of multidrug-resistant Enterobacteriaceae is complicating the treatment of nosocomial infections. In many parts of the world, resistance to third-generation cephalosporins exceeds 10% of total nosocomial isolates and 30% of isolates detected in the intensive care unit. This resistance is frequently due to the acquisition of plasmids containing genes encoding for extended-spectrum beta-lactamases (ESBLs). Furthermore, these mobile elements often carry genes encoding resistance to other drugs such as aminoglycosides. A high risk of poor clinical outcome has been observed in patients infected with ESBL producers receiving third-generation cephalosporins, even if the organism appears susceptible to the antibiotic. For this reason, clinical microbiology laboratories are advised to incorporate specific ESBL detection methodology into routine clinical practice. This should prevent erroneous use of cephalosporins for these infections. Most ESBL producers remain susceptible to carbapenems, and these agents are considered the drugs of choice against ESBL-producing organisms. Unfortunately, there is now an increasing occurrence of carbapenem resistance in the Enterobacteriaceae. In this context, clinical response to new antibiotics (e.g., tigecycline) and old antibiotics (e.g., colistin) with good in vitro activity against ESBL producers needs to be evaluated.     

Methionine adenosyltransferase 1A knockout mice are predisposed to liver injury and exhibit increased expression of genes involved in proliferation

Liver-specific and nonliver-specific methionine adenosyltransferases (MATs) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (AdoMet), the principal biological methyl donor. Mature liver expresses MAT1A, whereas MAT2A is expressed in extrahepatic tissues and is induced during liver growth and dedifferentiation. To examine the influence of MAT1A on hepatic growth, we studied the effects of a targeted disruption of the murine MAT1A gene. MAT1A mRNA and protein levels were absent in homozygous knockout mice. At 3 months, plasma methionine level increased 776% in knockouts. Hepatic AdoMet and glutathione levels were reduced by 74 and 40%, respectively, whereas S-adenosylhomocysteine, methylthioadenosine, and global DNA methylation were unchanged. The body weight of 3-month-old knockout mice was unchanged from wild-type littermates, but the liver weight was increased 40%. The Affymetrix genechip system and Northern and Western blot analyses were used to analyze differential expression of genes. The expression of many acute phase-response and inflammatory markers, including orosomucoid, amyloid, metallothionein, Fas antigen, and growth-related genes, including early growth response 1 and proliferating cell nuclear antigen, is increased in the knockout animal. At 3 months, knockout mice are more susceptible to choline-deficient diet-induced fatty liver. At 8 months, knockout mice developed spontaneous macrovesicular steatosis and predominantly periportal mononuclear cell infiltration. Thus, absence of MAT1A resulted in a liver that is more susceptible to injury, expresses markers of an acute phase response, and displays increased proliferation.     

Fine mapping of colon tumor susceptibility (Scc) genes in the mouse, different from the genes known to be somatically mutated in colon cancer.

The predisposition to colon cancer is multigenetically controlled in animals and probably also in humans. We have analyzed the multigenic control of susceptibility to 1,2-dimethylhydrazine-induced colon tumors in mice by using a set of 20 homozygous CcS/Dem recombinant congenic strains, each of which contains a different random subset of approximately 12.5% of genes from the susceptible strain STS/A and 87.5% of genes from the relatively resistant strain BALB/cHeA. Some CcS/Dem strains received the alleles from the susceptible strain STS/A at one or more of the multiple colon tumor susceptibility loci and are susceptible, whereas others are resistant. Linkage analysis shows that these susceptibility genes are different from the mouse homologs of the genes known to be somatically mutated in human colon cancer (KRAS2, TP53, DCC, MCC, APC, MSH2, and probably also MLH1). Different subsets of genes control tumor numbers and size. Two colon cancer susceptibility genes, Scc1 and Scc2, map to mouse chromosome 2. The Scc1 locus has been mapped to a narrow region of 2.4 centimorgans (90% confidence interval).     

Review of preclinical studies with ofloxacin.

Most Enterobacteriaceae, enteropathogens, and fastidious gram-negative bacteria are highly susceptible to ofloxacin, a new tricyclic fluoroquinolone. Aerobic gram-negative bacilli and gram-positive bacteria are generally not as susceptible to ofloxacin. Obligate anaerobes are generally resistant to ofloxacin, while many mycobacteria, chlamydiae, legionellae, and mycoplasmas are susceptible. Ofloxacin is generally less active than ciprofloxacin against gram-negative bacteria, is similarly active against gram-positive bacteria, mycobacteria, legionellae, and mycoplasmas, and is more active against chlamydiae. However, numerous animal studies have shown these two fluoroquinolones to be similar. Ofloxacin inhibits DNA synthesis, is rapidly bactericidal, and is 1,000-2,400 times more potent against prokaryotic gyrase than against eukaryotic gyrase. The bactericidal effect of ofloxacin is not completely neutralized by inhibitors of protein or RNA synthesis. Resistance to ofloxacin arises from mutations within chromosomal genes involved with DNA gyrase and drug permeation. Selection of resistant mutants by ofloxacin is not as frequent as that seen with nalidixic acid. However, due to the cross-resistance between ofloxacin and other fluoroquinolones, all of these drugs should be used judiciously to preserve their clinical utility.