METABOLISM OF METHIONINE IN THE NEWBORN INFANT

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。本研究的目的是量化蛋氨酸（一种含硫必需氨基酸）在健康足月婴儿和低出生体重婴儿中的动力学和代谢。健康的足月婴儿将从正常的新生儿托儿所招募，而低出生体重（早产）婴儿将从新生儿重症监护病房招募。通过使用稳定的、非放射性的蛋氨酸、苯丙氨酸和尿素的同位素示踪剂，研究人员提出量化蛋氨酸的动力学及其与全身蛋白质分解（用苯丙氨酸Ra测量）和全身蛋白质氧化率（用尿素生产测量）的关系。在足月婴儿中，经过三小时的基础研究，将检查肠内给药营养（配方）对上述参数的影响。研究的总时间为7小时：3小时基础喂养和4小时间歇喂养（每30分钟一次）。呼吸量热测量将定期在足月婴儿中进行。每隔一段时间从留置静脉插管中抽取血液样本。LBW婴儿将在接受3.0 g/kg/d的肠外氨基酸治疗至少24小时，而不是肠内喂养的情况下进行研究。这些研究的重要意义在于，它们将产生重要的数据，可能为新生儿补充（或不补充）半胱氨酸（由蛋氨酸形成的硫氨基酸）提供依据。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to quantify the kinetics and metabolism of methionine (transsulfuration pathway), a sulfur containing essential amino acid, in healthy full term babies and in low birth weight infants. Healthy full term babies will be recruited from the normal newborn nursery while low birth weight (premature) infants will be recruited from the Neonatal Intensive Care Unit. By using stable, non-radioactive isotopic tracers of methionine, phenylalanine and urea, the investigators propose to quantify the kinetics of methionine and its relation to whole body protein breakdown (measured by phenylalanine Ra) and whole body rate of protein oxidation (measured by production of urea). In full term infants, after a three-hour basal study, the effect of enterally administered nutrients (formula) on the above parameters will be examined. The total duration of study will be seven hours: three hours basal and four hours of response to intermittent (every 30 minute) feeds. Respiratory calorimetry measurements will be done at periodic intervals in term infants. Blood samples from indwelling venous cannula will be drawn at periodic intervals. The LBW infants will be studied while they are receiving parenteral amino acid at 3.0 g/kg/d for at least 24 hours and not enterally fed. The studies are significant in that they will generate important data which may provide the rationale for supplementation (or not) of cysteine (sulfur amino acid, formed from methionine) in the newborn infant.