肠道微生物代谢苷类化合物的研究进展CSCD

肠道微生物对苷类化合物的体内代谢十分重要,可分泌代谢酶进行脱糖基、脱甲基、脱羟基、水解和氧化还原等反应将苷代谢生成次级苷、苷元或其他代谢产物,从而促进苷类药物的吸收并发挥药效。本文论述了肠道微生物及代谢酶对苷类化合物代谢的意义,总结了肠道微生物对不同结构类型的苷类化合物的代谢规律及代谢产物,为了解苷类药物的疗效基础、作用机理及利用微生物转化开发苷类药物提供参考。     

核酸类物质脱嘌呤的反应特性、机制及影响因素

核酸的脱嘌呤反应是指核酸链上核糖与嘌呤之间的糖苷键断裂,从而产生游离嘌呤和无嘌呤位点的过程。脱嘌呤过程与基因突变和细胞老化等过程都有着密切的关系。文章主要叙述了酸性和生理条件下核酸脱嘌呤的反应特点及影响因素,并对脱嘌呤的机理进行了描述。同时,总结了致癌物对于脱嘌呤的促进作用并揭示了脱嘌呤与癌症等疾病的密切关系。此外,糖苷酶对于核酸脱嘌呤的催化作用也在文中进行了探讨。对于核酸脱嘌呤的系统研究可以为基因变异、核酸代谢等研究提供一定的理论基础,并且有助于癌症和痛风等疾病的研究。     

神经系统中的嘌呤信号

三磷酸腺苷(ATP)作用于嘌呤受体(P2受体),引起离子通道开放或通过第二信使调节神经细胞功能,不仅参与了特殊感觉、神经元与神经胶质细胞相互作用等生理活动,而且参与了神经损伤修复和疼痛等病理过程.神经系统中的嘌呤信号系统研究,不仅为解释神经系统生理功能及其病理过程提供了新的思路,而且为治疗神经系统损伤和疼痛等疾病开辟了新的希望.     

药物代谢酶及转运体与前列腺癌药物治疗

药物代谢酶是催化体内摄入的各种药物进行生物转化的一系列重要酶,属于生物转化酶系中的一类.虽然药物生物转化的主要场所在肝脏,但在肝外组织(如前列腺)亦存在,而且可影响药物在局部的生物转化率.药物转运体在药物的跨膜转运中发挥了重要的作用,影响了药物在体内的药代动力学进程,药物转运体在组织中分布广泛;本文着重阐述这些药物代谢酶及转运体在治疗前列腺癌药物中的作用,及它们在前列腺中的特异性表达,同时讨论了在不同的治疗策略中与药物代谢酶及转运体相关的靶向作用.     

基于稳定同位素的代谢组学临床研究进展

基于稳定同位素示踪的代谢组学不仅能检测疾病发生发展及治疗过程中相关代谢物的变化,还可以对生物体系的代谢物进行定量分析并描述代谢特性。目前,稳定同位素示踪的代谢组学技术可在受试者体内直接追踪到代谢网络的单个原子,更有利于发现与疾病病因和诊断及药物疗效评估相关的生物标志物。现就稳定同位素示踪代谢组学在临床研究中的应用做简要概述,以期为将来更好地开展代谢组学在临床方面的研究提供重要依据。     

含FLP“交换盒”结构的打靶载体构建及ES细胞打靶研究

利用小鼠HPRT基因组DNA片段和人工合成的含有FLP重组酶识别位点变异体FRT和F3RT序列的寡核苷酸 ,构建了针对小鼠HPRT基因位点的置换型打靶载体pSP HPRT Fneo F₃。经过限制酶酶切及部分测序鉴定其结构正确后 ,将线性化了的打靶载体以电穿孔法导入ES细胞内 ,经G418和 6 -TG双药筛选和分子鉴定 ,得到了 2个在HPRT位点整合有FLP重组酶“交换盒”F Neo F3结构的双交换重组ES细胞克隆 ,为建立基于FLP重组酶介导的盒式交换的高效、定点转基因体系创造了条件.     

代谢组学在临床研究中的应用及进展

代谢组学是"后基因组学"时期新兴的一门学科,也是系统生物学的重要组成部分。代谢组学通过全面、定量检测生物样本中多种类型小分子化合物,来了解在内在和外界因素作用下生物体内源性物质的变化及规律,特别适合于临床上研究机体因受到遗传、生长、生理、环境因素和异物、病源等刺激的影响而产生的变化。借助于代谢组学技术不仅能够描述疾病发生、发展以及治疗过程中机体代谢机能的状态和变化,为临床疾病的诊断、病理机制的探索、新治疗靶点的发现等提供新的途径和思路,还可以揭示外界干扰因素(药物/毒物、环境、饮食、生活方式等)对机体的影响,为药效评价和疾病病因的筛查提供基础数据。近年来,代谢组学在临床研究方面得到了广泛的应用,取得了巨大的进展并展现了鼓舞人心的应用前景。该文分别就代谢组学在描述疾病发展状态、研究疾病诊断方法、探索疾病发病原因和发病机理、药效学评价等几个方面的应用及进展进行回顾和综述。     

在生香毛霉酶促磷酸化体系中葡萄糖的醇解和嘌呤核苷酸代谢的调节

我们研究了生香毛霉(M·aromaticus Povah)酶促磷酸化体系中糖的酵解特性和葡萄糖、磷酸盐对嘌呤核苷酸代谢的调节作用。试验表明,生香毛霉具有较强的糖酵解酶系活力和发酵力。但是它的发酵能力易受菌体保存温度和放置时间的影响。     

动物体尿囊酸酶的研究进展

尿囊酸酶是嘌呤代谢途径的重要酶之一,与动物排泄物的产生直接有关.结合当前研究进展,总结了动物体尿囊酸酶的种属特异性、蛋白质及其基因结构和组织表达.并对尿囊酸酶的活性检测方法进行了简要介绍.     

嘌呤核苷及其衍生物的代谢工程

嘌呤核苷及其衍生物被广泛应用于食品和医药领域。利用诱变筛选技术可以获得嘌呤核苷类产品的工业生产菌株,但往往耗时,效率低,而且获得的某些高产菌株还存在不稳定的缺陷。菌株代谢调控与生理生化的研究为代谢工程优化嘌呤核苷类产品的合成提供了理论基础,利用代谢工程改造菌株合成嘌呤核苷也引起了研究人员的关注。系统地介绍了微生物嘌呤生物合成途径及其调控机制,综述了嘌呤核苷类产品及其衍生物的代谢工程研究进展,最后讨论了利用代谢工程改造菌株合成这些产品面临的问题及今后的研究方向。     

Human HPRT1 gene and the Lesch–Nyhan disease: Substitution of alanine for glycine and inversely in the HGprt enzyme protein

Lesch–Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report three novel independent mutations in the coding region of the HPRT1 gene from genomic DNA of (a) a carrier sister of two male patients with LND: c.569G>C, p.G190A in exon 8; and (b) two LND affected male patients unrelated to her who had two mutations: c.648delC, p.Y216X, and c.653C>G, p.A218G in exon 9. Molecular analysis reveals the heterogeneity of genetic mutation of the HPRT1 gene responsible for the HGprt deficiency. It allows fast, accurate detection of carriers and genetic counseling.     

Lesch-Nyhan disease in two families from Chiloé Island with mutations in the HPRT1 gene

Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report two independent point mutations leading to splicing errors: IVS 2 +1G>A, c.134 +1G>A, and IVS 3 +1G>A, c.318 +1G>A in the hypoxanthine-phosphoribosyltransferase1 (HPRT1) gene which result in exclusion of exon 2 and exon 3 respectively, in the HGprt enzyme protein from different members of two Chiloé Island families. Molecular analysis has revealed the heterogeneity of genetic mutation of the HPRT1 gene responsible for the HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.     

Lesch–Nyhan Syndrome in a Family with a Deletion Followed by an Insertion within the HPRT1 Gene

Lesch–Nyhan syndrome (LNS) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase(HGprt) is defective. The authors report a novel mutation which led to LNS in a family with a deletion followed by an insertion (INDELS) via the serial replication slippage mechanism: c.428_432delTGCAGinsAGCAAA, p.Met143Lysfs*12 in exon 6 of HPRT1 gene. Molecular diagnosis discloses the genetic heterogeneity of HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.     

Mutation in the Human HPRT1 Gene and the Lesch-Nyhan Syndrome

Lesch-Nyhan syndrome (LNS) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report a novel mutation which led to HGprt-related neurological dysfunction (HND) in two brothers from the same family with a missense mutation in exon 6 of the coding region of the HPRT1 gene: c.437T>C, p.L146S. Molecular diagnosis discloses the genetic heterogeneity of the HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.     

Gene deletion, a mechanism of induced mutation by arabinosyl nucleosides

9-β- -Arabinofuranosyl-2-fluoroadenine (F-ara-A) and 9-β- -arabinofuranosyladenine (ara-A) are purine nucleoside analogues which are incorporated into nucleic acids. This study demonstrates the mutagenic properties of F-ara-A and ara-A and provides evidence for mechanisms by which the arabinosyl nucleosides induce mutation. At the drug dosages that evoked exponential cell killing, F-ara-A and ara-A caused a significant increase in the number of 6-thioguanine-resistant mutants in Chinese hamster ovary cells. Southern analyses showed that 15 of 16 drug-induced mutants had lost all or part of the HPRT gene, whereas no loss of the gene was found in 4 spontaneous mutants. We conclude that both F-ara-A and ara-A induced mutation predominantly by causing deletion of genetic method. The remarkable frequency of gene deletion among these drug-induced mutations is discussed with respect to possible mechanisms of action of arabinosyl nucleosides in mutational studies.     

Novel mutation in the human HPRT1 gene and the Lesch-Nyhan disease

Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report a novel point mutation that led to HGprt-related neurological dysfunction (HND) in a family in which there was a missense mutation in exon 6 of the coding region of the HPRT1 gene: g.34938G>T, c.403G>T, p.D135Y. Molecular diagnosis is consistent with the genetic heterogeneity of the HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.     

Gene duplication and inactivation in the HPRT gene family

Hypoxanthine phosphoribosyltransferase (HPRT1) is a key enzyme in the purine salvage pathway, and mutations in HPRT1 cause Lesch-Nyhan disease. The studies described here utilized targeted comparative mapping and sequencing, in conjunction with database searches, to assemble a collection of 53 HPRT1 homologs from 28 vertebrates. Phylogenetic analysis of these homologs revealed that the HPRT gene family expanded as the result of ancient vertebrate-specific duplications and is composed of three groups consisting of HPRT1, phosphoribosyl transferase domain containing protein 1 (PRTFDC1), and HPRT1L genes. All members of the vertebrate HPRT gene family share a common intron-exon structure; however, we have found that the three gene groups have distinct rates of evolution and potentially divergent functions. Finally, we report our finding that PRTFDC1 was recently inactivated in the mouse lineage and propose the loss of function of this gene as a candidate genetic basis for the phenotypic disparity between HPRT-deficient humans and mice.