METABOLISM OF METHIONINE IN THE NEWBORN INFANT

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。本研究的目的是量化健康足月婴儿和低出生体重婴儿中蛋氨酸（转硫途径）（一种含硫必需氨基酸）的动力学和代谢。 健康足月婴儿将从正常新生儿保育室招募，而低出生体重（早产）婴儿将从新生儿重症监护室招募。通过使用蛋氨酸、苯丙氨酸和尿素的稳定的非放射性同位素示踪剂，研究人员建议量化蛋氨酸的动力学及其与全身蛋白质分解（通过苯丙氨酸Ra测量）和全身蛋白质氧化速率（通过尿素的产生测量）的关系。在足月婴儿中，在三小时的基础研究后，将检查肠内给予的营养素（配方）对上述参数的影响。研究的总持续时间为7小时：3小时基础和4小时对间歇性（每30分钟）进食的反应。将定期对足月婴儿进行呼吸量热测定。将定期从留置静脉插管中抽取血样。将在LBW婴儿接受3.0 g/kg/d胃肠外氨基酸至少24小时且未经肠喂养的情况下进行研究。 这些研究具有重要意义，因为它们将产生重要数据，这些数据可能为新生儿补充（或不补充）半胱氨酸（含硫氨基酸，由甲硫氨酸形成）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.