Severe falciparum malaria: mechanisms of hypoargininemia

严重恶性疟疾：低精氨酸血症的机制

• 批准号: 6675531
• 负责人: Bert K Lopansri
• 金额: $ 13.47万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6675531
• 关键词: African; Plasmodium falciparum; aminoacid biosynthesis; aminoacid metabolism; arginine; argininemia; biotransformation; child (0-11); citrulline; clinical research; gene expression; human subject; leucine; malaria; mass spectrometry; nitric oxide synthase; ornithine; pathologic process; patient oriented research; plasma; polymerase chain reaction; reagent /indicator; urea cycle

DESCRIPTION (provided by applicant): The goal of this project is to investigate the role of L-arginine as substrate for nitric oxide synthesis in the pathophysiology of severe falciparum malaria. Globally, malaria causes more morbidity and mortality than any other parasitic disease with most deaths occurring in African children. Nitric oxide (NO) metabolites have been shown to be low in severe malaria. Studies performed by our group have shown that plasma arginine concentrations are markedly depressed in Tanzanian children with cerebral malaria when compared to healthy control children and children with uncomplicated malaria. Furthermore, arginine levels less than 45 mu-M in cerebral malaria were predictive of mortality. We hypothesize that low arginine in severe malaria may be due to one or a combination of the following: 1. reduced intestinal uptake, 2. reduced endogenous renal synthesis, 3. increased consumption of arginine in the urea cycle, or 4. increased catabolism of arginine by extrahepatic arginase induced in mononuclear cells and other cell types. These hypotheses will be investigated by three different approaches. The first approach will be to determine plasma levels of amino acids associated with the uptake, biosynthesis and catabolism of arginine, and levels of other essential and non-essential amino acids. Plasma samples will be analyzed using HPLC with pre-column derivatization and fluorescence detection. The second approach will be to determine the flux and metabolic fate of arginine in patients with severe malaria and to define how they differ from healthy controls. This will be accomplished by infusing non-radioactive tracers of arginine, citrulline, ornithine and leucine and measuring the metabolic byproducts of these tracers. HPLC separation coupled to mass spectrometric analysis of heavy isotope concentration in collected samples will be used. The third approach will be to directly determine the transcription of enzymes important for the uptake, biosynthesis, and catabolism of arginine. Collected peripheral blood mononuclear cell extracts will be analyzed using real time PCR. An enzymatic assay to measure arginase activity in mononuclear cell extracts will also be used. This project is essential for the overall goal of further defining the pathophysiology of severe malaria. The knowledge gained will facilitate the development of disease modifying strategies (e.g. arginine or other amino acid infusion) to reduce the morbidity and mortality of falciparum malaria.

描述（由申请人提供）：该项目的目的是研究L-精氨酸作为一氧化氮合成的底物在严重恶性疟疾的病理生理学中的作用。在全球范围内，疟疾会引起比任何其他寄生疾病的发病率和死亡率更多，而大多数死亡发生在非洲儿童中。一氧化氮（NO）代谢物已显示出严重的疟疾低。我们小组进行的研究表明，与健康对照的儿童和简单的疟疾儿童相比，坦桑尼亚儿童的血浆精氨酸浓度明显降低。此外，脑疟疾中的精氨酸水平小于45 mu-m是死亡率的。我们假设严重疟疾中的精氨酸低可能是由于一种或以下组合引起的：1。肠道摄取减少，2。内源性肾脏合成减少，3。尿素周期中精氨酸的消耗量增加，或4。在单核细胞和其他细胞类型中诱导的精氨酸分解酶增加了精氨酸的分解代谢。 这些假设将通过三种不同的方法进行研究。第一种方法是确定与精氨酸的摄取，生物合成和分解代谢以及其他必需氨基酸的水平相关的氨基酸的血浆水平。血浆样品将使用具有前柱前衍生化和荧光检测的HPLC进行分析。第二种方法是确定严重疟疾患者精氨酸的通量和代谢命运，并确定其与健康对照的不同。这将通过注入精氨酸，瓜氨酸，鸟氨酸和亮氨酸的非放射性示踪剂以及测量这些示踪剂的代谢副产品来实现。将使用收集样品中重量同位素浓度的质谱分析的HPLC分离。第三种方法是直接确定对精氨酸摄取，生物合成和分解代谢重要的酶的转录。将使用实时PCR分析收集的外周血单核细胞提取物。还将使用用于测量单核细胞提取物中精氨酸酶活性的酶试验。 该项目对于进一步定义严重疟疾的病理生理学的总体目标至关重要。获得的知识将促进改变疾病的策略（例如精氨酸或其他氨基酸输注），以降低恶性疟疾的发病率和死亡率。