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目的探讨同时口服给予两种示踪剂1-13C-亮氨酸和α-15N-赖氨酸测量人体蛋白质需要量,结果是否一致。方法选取20名健康青年女性作为研究对象,预设6个膳食蛋白质水平,3个连续的实验周期,在每个实验周期给予日常膳食6d,在D7持续口服13C-亮氨酸和15N-赖氨酸4h,收集给予同位素过程中的静脉血、呼出气和尿液样本。测定血浆、呼出气和尿液中的13C、15N的丰度,计算13C-亮氨酸和15N-赖氨酸的氧化率,建立二项回归曲线计算蛋白质的需要量。结果通过13C-亮氨酸计算的蛋白质需要量是0.92 g/kg/d,无法通过15N-赖氨酸的氧化率建立二项回归曲线求得蛋白质需要量。结论口服途径以15N-赖氨酸作为示踪剂,不能较好的反映蛋白质摄入量的变化情况。
OBJECTIVE: To determine whether the two tracers 1-13C-leucine and α-15N-lysine are orally administered simultaneously to determine the human protein requirements. Methods Twenty healthy young women were selected as experimental subjects. Six dietary protein levels were preset for three consecutive experimental periods. The daily diet was given for 6 days in each experimental period. Oral administration of 13C-leucine and 15N-L-lysine Acid 4h, collected to give the isotope of venous blood, exhaled breath and urine samples. The abundances of 13C and 15N in plasma, exhaled breath and urine were measured, and the oxidation rates of 13C-leucine and 15N-lysine were calculated. The bi-regression curve was constructed to calculate the protein requirement. Results The estimated protein requirement by 13C-leucine was 0.92 g / kg / d, and the protein requirement was not established by establishing a binomial regression curve using the oxidation rate of 15N-lysine. Conclusion The oral route of 15N-lysine as a tracer, can not better reflect the changes in protein intake.