Miller R G, Jahoor F, Jaksic T
Cora and Webb Mading Department of Surgery, Baylor College of Medicine, Houston, TX, USA.
J Pediatr Surg. 1995 Jul;30(7):953-7; discussion 957-8. doi: 10.1016/0022-3468(95)90320-8.
Little is known about the amino acid (AA) biosynthetic capacity and requirements of premature infants. This study assessed the synthesis of seven biochemically nonessential AA from a universal precursor, glucose, in stable, parenterally fed, premature neonates. Seven infants (six boys, one girl) were studied at a mean age of 6.3 +/- 0.6 (SEM) days; mean gestational age was 29.7 +/- 1.3 (SEM) weeks, and mean birth weight was 1,222.8 +/- 176.5 (SEM) grams. All infants were parenterally fed a mixture of 7.5% to 12.5% dextrose and 2.2% Trophamine, with or without lipid. Mean caloric intake was 93 +/- 8.4 (SEM) kcal/kg/d, and total AA intake was standardized at 2.86 g/kg/d AA, plus supplemental cysteine (30 mg/g AA/d). Each infant received a 4-hour continuous, unprimed intravenous infusion of a stable isotope tracer of D(-)[U13C] glucose (200 mg/kg). Blood samples were obtained before and at the end of the infusion. Conversion of the glucose tracer into seven biochemically nonessential AA (cysteine [Cys], proline [Pro], aspartate [Asp], serine [Ser], glutamate [Glu], alanine [Ala], and glycine [Gly]) was assessed by measuring their isotopic enrichment in plasma, using gas chromatography/mass spectrometry (GC/MS), and expressed as mole percent excess (MPE) (mean +/- SEM). The isotopic enrichment of plasma glucose was also measured using GC/MS. Free plasma AA concentrations (mean +/- SD) were measured using an automated amino acid analyzer. Mean MPE for M + 1, M + 2 and M + 3 Cys, and for M + 1 and M + 3 Pro were not significantly different from 0; M + 2 Pro barely achieved statistical significance (P = .048).(ABSTRACT TRUNCATED AT 250 WORDS)
关于早产儿的氨基酸（AA）生物合成能力和需求，人们了解甚少。本研究评估了稳定的、经肠道外喂养的早产新生儿从通用前体葡萄糖合成七种生化非必需氨基酸的情况。对七名婴儿（六名男婴，一名女婴）进行了研究，平均年龄为6.3±0.6（标准误）天；平均胎龄为29.7±1.3（标准误）周，平均出生体重为1222.8±176.5（标准误）克。所有婴儿均通过肠道外给予7.5%至12.5%的葡萄糖和2.2%的酪蛋白水解物混合物，添加或不添加脂质。平均热量摄入为93±8.4（标准误）千卡/千克/天，总氨基酸摄入量标准化为2.86克/千克/天氨基酸，外加补充半胱氨酸（30毫克/克氨基酸/天）。每名婴儿接受4小时持续、无首剂的静脉输注稳定同位素示踪剂D(-)[U13C]葡萄糖（200毫克/千克）。在输注前和输注结束时采集血样。通过使用气相色谱/质谱法（GC/MS）测量血浆中七种生化非必需氨基酸（半胱氨酸[Cys]、脯氨酸[Pro]、天冬氨酸[Asp]、丝氨酸[Ser]、谷氨酸[Glu]、丙氨酸[Ala]和甘氨酸[Gly]）的同位素富集情况，评估葡萄糖示踪剂向这些氨基酸的转化，并表示为摩尔百分比过量（MPE）（平均值±标准误）。还使用GC/MS测量血浆葡萄糖的同位素富集情况。使用自动氨基酸分析仪测量游离血浆氨基酸浓度（平均值±标准差）。M+1、M+2和M+3半胱氨酸以及M+1和M+3脯氨酸的平均MPE与0无显著差异；M+2脯氨酸勉强达到统计学显著性（P = 0.048）。（摘要截断于250字）
