METABOLISM OF NON ESSENTIAL AMINO ACIDS IN HUMAN PREGNANCY

该研究将量化人类妊娠期间丝氨酸的动力学和代谢，并通过研究巨大儿和宫内发育迟缓的胎儿群体来研究丝氨酸与胎儿生长的可能关系。据推测，随着妊娠的进展和尿素合成速率的下降，肝内氮代谢发生了重大变化，其中来自尿原前体的氮量增加被转移到合成非必需氨基酸，如丝氨酸和甘氨酸，葡萄糖是丝氨酸碳的主要来源。进一步的假设是，大量的丝氨酸和甘氨酸可能被转移到胎儿体内。妊娠期糖尿病的特点是蛋白质分解增加，因此预计丝氨酸和甘氨酸的转化率会增加。调查计划继续研究正常孕妇、患有胰岛素依赖性糖尿病的孕妇、IUGR胎儿的孕妇、计划剖宫产的妇女和非妊娠对照组。对正常孕妇进行妊娠期连续研究。初步数据表明，妊娠与丝氨酸周转减少有关。在葡萄糖输注期间，丝氨酸周转率持续下降。这些变化对丝氨酸动力学的意义有待进一步评价。

The proposed study will quantify the kinetics and metabolism of serine during human pregnancy and examine its possible relation to fetal growth by examining such populations with fetal macrosomia and intrauterine growth retardation. It is hypothesized that as gestation advances and as the rates of urea synthesis decline, a significant change in the intrahepatic nitrogen metabolism occurs wherein increased amounts of nitrogen from ureagenic precursors are transferred to synthesize non-essential amino acids such as serine and glycine, and that glucose is a major source of serine carbon. It is further hypothesized that significant amounts of serine and glycine may be transferred to the fetus. Diabetes in pregnancy is characterized by increased protein breakdown, and thus it is expected that there is an increased rate of serine and glycine turnover. The plan of investigation continues to be to study normal pregnant women, pregnant women with insulin dependent diabetes, pregnant women with IUGR fetuses, women undergoing scheduled cesarean sections and non-pregnant controls. The normal pregnant women will be studied serially through pregnancy. Preliminary data suggest a pregnancy related decrease in serine turnover. During glucose infusion there was a consistent decrease in serine turnover. The significance of these changes in serine kinetics needs further evaluation.