Cord Blood Tryptophan Concentrations and Total Cysteine Concentrations

Abstract

The paper we recently published in JPEN' and discussions about it since its publication raised our interest in the determination of cord blood tryptophan concentrations and total cysteine concentrations. Our initial attempts to analyze samples for these amino acids using standard techniques were unsuccessful. The modifications we have used are described below.Plasma samples were analyzed for total tryptophan by the fluorometric procedure of Denckla and Dewey' as modified by Bloxam and Warren' with further modifications for improved accuracy and precision by our phys-FIG. 1. Regression analysis of gestational age (weeks) at the time of sample and plasma tryptophan concentrations (~mole/dl).iological amino acid analysis laboratory. The major modifications include heating samples in closed vials and extending the heating period to 75 min in boiling water for maximum conversion of tryptophan to norharmon. The accuracy of our plasma tryptophan method was evaluated by comparing data from our method with data generated from a reverse-phase high performance liquid chromatography (HPLC) method. A paired t-test analysis showed no significant difference (p = 0.50) between pairs of tryptophan values obtained by the two analytical methods.Total plasma cyst(e)ine was determined by reverse phase HPLC with electrochemical detection. Dithiothreitol was added to plasma samples and thiols were detected TABLE I Age, tryptophan, and cysteine data FIG. 2. Regression analysis of gestational age (weeks) at the time of sample plasma total cyst{e)ine concentrations (~mole/dl).

Differential Distribution of Tryptophan-Metabolites in Fetal and Maternal Circulations During Normotensive and Preeclamptic Pregnancies

“…The levels of Trp we detected largely fall within ranges previously reported [10,[33][34][35][36]. For instance, the overall levels of Trp in maternal (~ 35.8 µM) and umbilical (~ 62 µM) sera detected in the current study is similar to the circulating total Trp-levels in maternal (~ 37.9 µM, ranging from 25 to 53 µM) and in umbilical (~ 78 µM, ranging from 56 to 101 µM) sera [10].…”

Influence of early postnatal nutritional management on oxidative stress and antioxidant defence in extreme prematurity

“…In leukocytes derived from tracheal aspirates of preterm newborns, the cellular glutathione concentration was found to be positively related to gestational age, and boys had even lower leukocyte glutathione concentration than girls 26. Furthermore, lower plasma cysteine concentrations were found in premature infants 48,49, suggesting a deficiency in extracellular substrate availability for cellular uptake and glutathione synthesis. To investigate cellular glutathione conservation through intracellular glutathione recycling in response to hyperoxia, Lavoie and Chessex 26 studied the glutathione‐reductase activity in cells from tracheal aspirates of newborns (gestational age 26–41 wk) on postnatal days 1, 2 and 6.…”

Influence of early postnatal nutritional management on oxidative stress and antioxidant defence in extreme prematurity

“…In leukocytes derived from tracheal aspirates of preterm newborns, the cellular glutathione concentration was found to be positively related to gestational age, and boys had even lower leukocyte glutathione concentration than girls [26]. Furthermore, lower plasma cysteine concentrations were found in premature infants [48,49], suggesting a deficiency in extracellular substrate availability for cellular uptake and glutathione synthesis. To investigate cellular glutathione conservation through intracellular glutathione recycling in response to hyperoxia, Lavoie and Chessex [26] studied the glutathione-reductase activity in cells from tracheal aspirates of newborns (gestational age 26 Á/41 wk) on postnatal days 1, 2 and 6.…”