GLUCONEOGENESIS IN THE VERY LOW BIRTH WEIGHT INFANT

目的是比较胚胎发育对肝脏的贡献， 早产儿单独给予葡萄糖与 葡萄糖和氨基酸、葡萄糖和脂质的组合，或 葡萄糖，氨基酸和脂质在生命的前5天。 的 要检验的假设是：氨基酸、脂质和 两者都能增强VLBW婴儿的胚胎发生; IV替代 氨基酸、脂质或两者用于葡萄糖降低高血糖症， 增加低血糖的风险。 (NRSU在第一部分中， 在三个可比较的组中估计了该项目的遗传变异 接受胃肠外营养的极早产儿， 使用[U13 C]葡萄糖（n = 8）、[2 - 13 C]甘油的三种独立方法 （n = 6）或[2H2O]（n = 6）。 20名婴儿胎龄27 +/-0.2 周（平均值+/-SE），出生体重996 +/-28 g，接受8 - 12小时 脂肪和氨基酸的胃肠外输注，而葡萄糖输注 速率降低到约一半的葡萄糖周转率， 高血糖症 结果表明，婴儿保持正常血糖 在整个研究期间。 [U-13 C]葡萄糖和 [2 - 13C]甘油示踪剂提供了相同的估计， 平均葡萄糖产量为72.3 +/-4.5和72.4 +/-9.1%。 甘油是主要的产酶底物。 [2H2O] 不包括甘油的贡献， 可与通过以下方法测量的非甘油贡献相比较： [2 - 13C]甘油法。 因此，在充分供应脂质4小时后， 和氨基酸，但减少葡萄糖的输送， 葡萄糖的主要来源是异生作用 生产和甘油的主要产酶底物。 （正在进行中）。 在该项目的第二部分中， 将测试施用脂质和氨基酸对胚胎发生的影响 分别使用[2 - 13C]甘油和[U-13C]葡萄糖。 一组极早产儿的初步结果 与项目第一部分中所包括的类似， 接受相同的肠外营养，但氨基酸 去除，表明去除氨基酸不会损害 异源发生 这些研究正在进行中。

The purpose is to compare the contribution of gluconeogenesis to hepatic glucose production of preterm infants given glucose alone vs. a combination of either glucose and amino acids, glucose and lipid or glucose, amino acids and lipid during the first 5 days of life. The hypotheses to be tested are: amino acids, lipid and a combination of both enhance gluconeogenesis in the VLBW infant; substitution of IV amino acids, lipid or both for glucose diminish hyperglycemia without increasing the risk of hypoglycemia. (NRSU protocol) In a first part of the project gluconeogenesis was estimated in three comparable groups of extremely premature infants receiving parenteral nurtition, employing three independent methods using [U13C]glucose (n=8), [2-13C]glycerol (n=6), or [2H2O] (n=6). Twenty infants gestational age 27 +/- 0.2 weeks (mean+/-SE), birth weight 996 +/- 28 grams, received a 8-12hrs parenteral infusion of lipid and amino acids, while the glucose infusion rate was reduced to about half the glucose turnover rate to revent hyperglycemia. The results demonstrate that the infants remained normoglycemic throughout the study periods. The [U-13C]glucose and the [2-13C]glycerol tracers provided equal estimates of gluconeogenesis averaging 72.3 +/- 4.5 and 72.4 +/- 9.1% of glucose production. Glycerol was the principal gluconeogenic substrate. The [2H2O] estimate, which does not include the contribution from glycerol, was comparable to the non-glycerol contribution measured by the [2-13C]glycerol method. Thus, after 4 hrs of adequate supply of lipids and amino acids but reduced glucose delivery, normoglycemia was maintained, gluconeogenesis was the principle source of glucose production and glycerol the primary gluconeogenic substrate. (Manuscript in progress). In the second part of the project, the impact of parenterally administrated lipids and amino acids on gluconeogenesis will be tested separately using [2-13C]glycerol and [U-13C]glucose, respectively. Preliminary results obtained in a group of extremely premature infants comparable to those included in the first part of the project and, receiving the same parenteral nutrition except the amino acids were removed, indicate that removal of amino acids does not impair gluconeogenesis. These studies are ongoing.