GLUCONEOGENESIS IN THE VERY LOW BIRTH WEIGHT INFANT

目的是比较糖异生对肝脏的贡献。 单独服用葡萄糖的早产儿与A组的葡萄糖产生 葡萄糖和氨基酸、葡萄糖和脂肪或 在生命的前5天，葡萄糖、氨基酸和脂肪。这个 需要检验的假设是：氨基酸、脂类和以下物质的组合 两者都能促进极低出生体重儿的糖异生；静脉注射的替代品 用于葡萄糖的氨基酸、脂肪或两者兼而有之可降低高血糖 增加低血糖的风险。(NRSU协议)在第一部分 在三个可比较的组中估计了项目的糖异生 极早产儿接受肠外营养的情况 使用[U13C]葡萄糖(n=8)、[2-13C]甘油的三种独立方法 N=6)或[2H2O](n=6)。20名胎龄27+/-0.2岁的婴儿 出生周(平均值+/-SE)，出生体重996+/-28克，接受8-12小时 静脉输注脂肪和氨基酸，同时输注葡萄糖 REvent的葡萄糖周转率降至约一半 高血糖症。 结果表明，婴儿的血糖保持在正常水平。 在整个研究期间。[U-13C]葡萄糖和 [2-13C]甘油示踪剂对糖异生作用提供了相同的估计 平均产糖量为72.3+/-4.5和72.4+/-9.1%。 甘油是主要的糖异生底物。[2H2O] 估计，其中不包括甘油的贡献，是 与非甘油贡献相当，由 [2-13C]甘油法。因此，在充足的脂质供应4小时后 和氨基酸，但减少了葡萄糖的供应，血糖正常 维持下去，糖异生是葡萄糖的主要来源 生产和甘油是主要的糖异生底物。 (手稿正在进行中)。 在项目的第二部分，肠外的影响 将测试给药的脂质和氨基酸对糖异生的影响。 分别使用[2-13C]甘油和[U-13C]葡萄糖。 在一组极早产儿中获得的初步结果 与项目第一部分中包括的项目相当， 接受相同的肠外营养，除了氨基酸是 去除，表示去除氨基酸不会损害 糖异生作用。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.