Elango Rajavel, Humayun Mohammad A, Turner Justine M, Rafii Mahroukh, Langos Veronika, Ball Ronald O, Pencharz Paul B
BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada;
Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
J Nutr. 2017 Oct;147(10):1954-1959. doi: 10.3945/jn.116.244301. Epub 2017 Aug 30.
The total sulfur amino acid (TSAA) and minimum Met requirements have been previously determined in healthy children. TSAA metabolism is altered in kidney disease. Whether TSAA requirements are altered in children with chronic renal insufficiency (CRI) is unknown. We sought to determine the TSAA (Met in the absence of Cys) requirements and minimum Met (in the presence of excess Cys) requirements in children with CRI. Five children (4 boys, 1 girl) aged 10 ± 2.6 y with CRI were randomly assigned to receive graded intakes of Met (0, 5, 10, 15, 25, and 35 mg · kg · d) with no Cys in the diet. Four of the children (3 boys, 1 girl) were then randomly assigned to receive graded dietary intakes of Met (0, 2.5, 5, 7.5, 10, and 15 mg · kg · d) with 21 mg · kg · d Cys. The mean TSAA and minimum Met requirements were determined by measuring the oxidation of l-[1-C]Phe to CO (FCO). A 2-phase linear-regression crossover analysis of the FCO data identified a breakpoint at minimal FCO Urine samples collected from all study days and from previous studies of healthy children were measured for sulfur metabolites. The mean and population-safe (upper 95% CI) intakes of TSAA and minimum Met in children with CRI were determined to be 12.6 and 15.9 mg · kg · d and 7.3 and 10.9 mg · kg · d, respectively. In healthy school-aged children the mean and upper 95% CI intakes of TSAA and minimum Met were determined to be 12.9 and 17.2 mg · kg · d and 5.8 and 7.3 mg · kg · d, respectively. A comparison of the minimum Met requirements between healthy children and children with CRI indicated significant ( < 0.05) differences. These results suggest that children with CRI have a similar mean and population-safe TSAA to that of healthy children, suggesting adequate Cys synthesis via transsulfuration, but higher minimum Met requirement, suggesting reduced remethylation rates.
此前已确定健康儿童的总硫氨基酸（TSAA）和蛋氨酸最低需求量。肾脏疾病会改变TSAA代谢。慢性肾功能不全（CRI）患儿的TSAA需求量是否改变尚不清楚。我们试图确定CRI患儿的TSAA（无半胱氨酸时的蛋氨酸）需求量和最低蛋氨酸（有过量半胱氨酸时）需求量。5名年龄为10±2.6岁的CRI患儿（4名男孩，1名女孩）被随机分配，接受不同剂量的蛋氨酸（0、5、10、15、25和35mg·kg·d），饮食中不含半胱氨酸。然后，其中4名患儿（3名男孩，1名女孩）被随机分配，接受不同剂量的蛋氨酸（0、2.5、5、7.5、10和15mg·kg·d），同时摄入21mg·kg·d的半胱氨酸。通过测量l-[1-C]苯丙氨酸氧化为CO₂（FCO）来确定平均TSAA和最低蛋氨酸需求量。对FCO数据进行两阶段线性回归交叉分析，确定了最低FCO时的转折点。收集所有研究日以及之前健康儿童研究中的尿液样本进行硫代谢产物检测。CRI患儿的TSAA平均摄入量和人群安全摄入量（95%置信区间上限）分别确定为12.6和15.9mg·kg·d，最低蛋氨酸平均摄入量和人群安全摄入量分别为7.3和10.9mg·kg·d。在健康学龄儿童中，TSAA平均摄入量和95%置信区间上限分别确定为12.9和17.2mg·kg·d，最低蛋氨酸平均摄入量和95%置信区间上限分别为5.8和7.3mg·kg·d。健康儿童与CRI患儿最低蛋氨酸需求量的比较显示出显著差异（<0.05）。这些结果表明，CRI患儿的平均TSAA和人群安全TSAA与健康儿童相似，表明通过转硫途径可充分合成半胱氨酸，但最低蛋氨酸需求量更高，表明甲基化率降低。
