PURINE ANALOGUE METABOLISM IN TOXOPLASMA GONDIL

弓形虫中的嘌呤类似物代谢

• 批准号: 3144776
• 负责人: Mahmoud H el Kouni
• 金额: $ 14.03万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-07-01 至 1995-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3144776
• 关键词: AIDS; Toxoplasma gondii; adenosine kinase; antiprotozoal agents; biological transport; cell free system; chemical binding; chemical structure function; disease /disorder model; drug adverse effect; drug metabolism; encephalitis; enzyme substrate; fibroblasts; high performance liquid chromatography; host organism interaction; laboratory mouse; medical complication; nucleosides; nucleotide metabolism; purine analog; tissue /cell culture; toxoplasmosis

The parasitic protozoa Toxoplasma gondii cause toxoplasmic encephalitis which is the most common opportunistic infection of the CNS in AIDS patients. Pyrimethamine plus sulfadiazine is currently the only acceptable therapy. However, it is limited by host toxicity. The increasing high incidence of toxoplasmic encephalitis and the lack of satisfactory drugs necessitate the search for new drugs and targets for chemotherapy. Studies on the uptake and metabolism of purine antimetabolites offer an excellent opportunity for this quest. Purines are required for the highly active nucleic acids synthesis essential for these rapidly replicating parasites. Since, T. gondii lack de novo purine biosynthesis and rely on their host for the salvage of purines, interference with the uptake and/or salvage of purines by purine antimetabolites should inhibit parasite replication. Our long range objective is to identify specific inhibitors of purine uptake and metabolism in T. gondii as potential chemotherapeutic agents. Specific Aims are (1) Test purine analogues as substrates or inhibitors of adenosine kinase and purine phosphoribosyltransferase in cell free extracts, in order to formulate structure-activity relationships and identify compounds that selectively inhibit the T. gondii enzymes. (2) Evaluate the uptake and metabolic fate of promising purine analogues and their effects on nucleotide metabolism in infected cells and free parasites in vitro. (3) Determine the effect of nucleoside transport inhibitors on the uptake and metabolism of purine analogues in infected cells and free parasites in vitro. (4) Study the nature of nucleoside transport in infected cells and free parasites to determine if infection alters the sensitivity to and/or the number of binding sites of nucleoside transport inhibitors in infected cells; if there exist such binding sites on the parasite; and search for selective inhibitors of parasite purine transport. (5) Evaluate inhibitors as potential antitoxoplasmosis agents and possible protection against host-toxicity by nucleoside transport inhibitors in cell culture and in mice. The RH strain of T. gondii is maintained in mice. Free parasites and infected human foreskin fibroblasts will be used for in vitro investigations. HPLC will be used to analyze the metabolic effects. The in vivo pharmacological studies will be carried out in mice.

寄生原生动物弓形虫引起弓形虫性脑炎 这是艾滋病中通讯中心最常见的机会感染 患者。 嘧啶加和磺胺嗪目前是唯一可以接受的 治疗。 但是，它受宿主毒性的限制。 增加高 弓形脑炎的发生率和缺乏令人满意的药物 需要寻找新药和化学疗法的靶标。 研究 嘌呤抗代谢物的摄取和代谢提供了极好的 这个任务的机会。 高度活跃需要嘌呤 这些快速复制的寄生虫必不可少的核酸合成。 从那以后，T。Gondii缺乏从头嘌呤的生物合成，并依靠他们的宿主 为了挽救嘌呤，干扰了吸收和/或打捞 嘌呤抗代谢物的嘌呤应抑制寄生虫复制。 我们的 远程目标是确定嘌呤摄取的特定抑制剂 gondii的代谢和代谢为潜在的化学治疗剂。 具体目的是（1）测试嘌呤类似物作为底物或抑制剂 腺苷激酶和嘌呤磷酸糖基转移酶在无细胞中 提取物，以建立结构 - 活性关系和 鉴定有选择性抑制巨霉菌酶的化合物。 （2） 评估有前途的嘌呤类似物的吸收和代谢命运和 它们对感染细胞和游离寄生虫中核苷酸代谢的影响 体外。 （3）确定核苷转运抑制剂对 感染细胞和自由的嘌呤类似物的摄取和代谢 体外寄生虫。 （4）研究核苷转运的性质 感染细胞和游离寄生虫，以确定感染是否改变了 对核苷转运的结合位点的敏感性和/或 感染细胞的抑制剂；如果存在这样的绑定位点 寄生虫；并寻找寄生虫嘌呤转运的选择性抑制剂。 （5）将抑制剂评估为潜在的抗毒素剂，并可能 通过核苷转运抑制剂在细胞中的宿主毒性保护 文化和小鼠。 小鼠中gondii的RH菌株保持在小鼠中。 免费的寄生虫和感染的包皮成纤维细胞将用于 体外研究。 HPLC将用于分析代谢作用。 体内药理研究将在小鼠中进行。