Read W W, McLaren D S, Tchalian M, Nassar S
J Clin Invest. 1969 Jun;48(6):1143-9. doi: 10.1172/JCI106071.
Investigations using ammonium citrate-(15)N and urea-(15)N showed that children in the acute stage of kwashiorkor and marasmus receiving a diet of adequate protein content retained a considerable percentage of the label from both compounds. Excretion of both total (15)N and urea-(15)N was subnormal and elimination was virtually completed 36 hr after administration of the isotope. During recovery from kwashiorkor total (15)N excretion had approached normal a month after commencement of rehabilitation. Urea-(15)N excretion was still slightly subnormal after 3 months. In marasmus urea-(15)N formed a normal proportion of total (15)N excretion after 1 month, although total (15)N excretion then was still low. Ammonia nitrogen was retained to a greater extent than urea nitrogen in all cases. As it is known that a considerable amount of urea is degraded to ammonia in the gastrointestinal tract, it seems probable that urea nitrogen became available for use after this degradation. Examination of blood from one marasmic child after feeding ammonia-(15)N and from another after intravenous injection of urea-(15)N showed incorporation of the label into blood cells and plasma proteins. This did not occur in well nourished controls. It is concluded that ammonia and urea as sources of nonessential nitrogen may play an important part in protein metabolism in the malnourished child.
使用柠檬酸铵 -（15）N和尿素 -（15）N进行的研究表明，处于夸希奥科病和消瘦症急性期的儿童，在摄入蛋白质含量充足的饮食后，两种化合物中的相当一部分标记物被保留了下来。总（15）N和尿素 -（15）N的排泄均低于正常水平，且在给予同位素后36小时内排泄基本完成。在夸希奥科病康复过程中，康复开始一个月后总（15）N排泄已接近正常。3个月后尿素 -（15）N排泄仍略低于正常水平。在消瘦症中，1个月后尿素 -（15）N在总（15）N排泄中所占比例正常，尽管此时总（15）N排泄仍较低。在所有情况下，氨氮的保留程度都比尿素氮大。由于已知相当数量的尿素在胃肠道中会降解为氨，所以尿素氮在这种降解后似乎有可能可供利用。对一名消瘦儿童喂食氨 -（15）N后以及对另一名儿童静脉注射尿素 -（15）N后的血液进行检测发现，标记物掺入了血细胞和血浆蛋白中。在营养良好的对照组中未出现这种情况。得出的结论是，氨和尿素作为非必需氮的来源，可能在营养不良儿童的蛋白质代谢中起重要作用。
