Homocysteine levels during fasting and after methionine loading in adolescents with diabetic retinopathy and nephropathy

OBJECTIVE: To assess plasma homocysteine levels in adolescents and young adults with type 1 (insulin-dependent) diabetes with and without microvascular complications. STUDY DESIGN: Homocysteine levels were measured during fasting and after methionine loading in plasma of 61 patients with onset of diabetes before the age of 12 years and duration of disease longer than 7 years. They had an albumin excretion rate (AER) between 20 and 200 microg/min in 2 of 3 overnight urine collections in a period of 6 months and/or retinopathy. Patients with persistent microalbuminuria were divided into 2 groups: subjects with AER of 20 to 70 microg/min and patients with AER of 70 to 200 microg/min. Adolescents (n = 54) without signs of diabetic retinopathy or nephropathy and matched control subjects (n = 63) were also studied. RESULTS: Homocysteine concentrations before and after methionine load were higher in adolescents with diabetic complications than in healthy subjects (fasting values: 12. 4 +/- 7.9 micromol/L vs 7.8 +/- 4.2 micromol/L; P <.01; after methionine load: 28.1 +/- 13.2 micromol/L vs 16.6 +/- 7.3 micromol/L; P <.005). Values of 11.9 micromol/L or higher were considered to constitute fasting hyperhomocysteinemia. The increase of homocysteine concentrations was particularly evident in young diabetic patients with AER >70 microg/min (fasting values: 14.7 +/- 5.6 micromol/L; after methionine load: 34.2 +/- 12.6 micromol/L) and in patients with proliferative retinopathy (fasting values: 15.1 +/- 5.0 micromol/L; after methionine load: 36.8 +/- 12.5 micromol/L). CONCLUSIONS: Increased plasma homocysteine concentrations may contribute to increased morbidity and death from cardiovascular disease in adolescents and young adults with diabetic retinopathy and nephropathy.     

Leptin levels in breast-fed and formula-fed infants

Aim: Leptin, a hormone that regulates food intake and energy metabolism, is present in breast milk and thus may be involved in body composition differences between breastfed and formula-fed infants. The aim of this study was to evaluate whether diet and gender affect plasma leptin concentration in breastfed and formula-fed infants during the first months of life. Methods: Anthropometric and bioelectrical impedance measurements [total body water (TBW) calculated with the Fjeld equation] were made and venous blood plasma samples were analysed for leptin concentration in healthy, exclusively breastfed or formula-fed Italian infants in the first year of life. Infants were subdivided in two ways: three groups (periods) in relation to age, and five groups in relation to weight. Results: The average serum concentration of leptin was 7.35 ng ml -1 . Serum leptin values were higher in breastfed than in formula-fed infants. Breastfed infants in group 1 had a statistically higher serum leptin concentration (2500-3749 g). There were no significant differences in anthropometric measurements, body mass index or skinfold thickness between breastfed and formula-fed infants. In the periods I and II, breastfed infants had a significantly higher TBW than formula-fed infants. Males had a significantly higher TBW than females in periods I and II. Breastfed infants in group 2 (3750-4999 g) had a significantly higher TBW than formula-fed infants.

Conclusion: The data on TBW, weight and skinfold thickness suggest that the higher leptin concentration observed in breastfed infants in the first months of life may be due not only to adipose tissue production but also to human milk.     

Plasma lipids and apolipoproteins in breastfed and formula-fed Swedish infants

This study was carried out to compare plasma lipid pattern in breastfed and formula-fed infants and the effects of exchanging breast milk for formula and of introducing weaning foods. Healthy infants, exclusively breastfed at least until 3 mo, were at this age randomly assigned to infant formulas with similar fat composition. Formula was gradually introduced when breastfeeding was discontinued. One group continued to breastfeed beyond 6 mo of age. All infants received the same weaning foods and were studied between 3 and 12 mo of age. Decreased plasma concentrations of total and low-density lipoprotein cholesterol (TC, LDL-C), apolipoprotein B (apo B) and A1 (p < 0.001), and of high-density lipoprotein cholesterol (p < 0.05) were found when breast milk was exchanged for formula before 6 mo. At this age plasma TC, LDL-C and apo B were lower in formula-fed than in breastfed infants (p < 0.001). These plasma lipids then increased (p < 0.01) when the intake of formula decreased and that of weaning foods increased. However, plasma TC and/or LDL-C remained lower at 12 mo in formula-fed than in breastfed infants (p < 0.05). Our results indicate that the plasma lipid profile of infants is highly responsive to the dietary nutrient intake, as indicated by the decrease in plasma lipids and apolipoproteins when breast milk was exchanged for formula and by the increase in these concentrations when the intake of weaning foods gradually increased.     

Homocysteine and other vascular risk factors in patients with phenylketonuria on a diet

The aim of this study was to investigate the known risk factors, such as lipids, homocysteine and endothelin, for the development of coronary artery disease (CAD) in phenylketonuria (PKU) patients, depending on their diet. The PKU patients (n = 74) were divided into two groups. Group A (n = 34; mean age 6.78 +/- 1.5 y) adhered strictly to a diet and group B (n = 40; mean age 8.0 +/- 3.2 y) did not comply with the diet. The control group comprised 50 healthy non-PKU children. All groups were evaluated for blood levels of homocysteine and vitamin B6 by high-performance liquid chromatography, vitamin B12 and folate in serum by a radioassay, lipids by a routine method, and lipoprotein(a) and endothelin-1 with an immunoassay. Homocysteine levels (28.65 +/- 3.3 micromol l(-1)) were increased in group A compared with group B (6.86 +/- 1.6 micromol l(-1)) and the controls (6.9 +/- 2.0 micromol l(-1)) (p < 0.001). Vitamin B6 (10.7 +/- 10.9 nmol l(-1)), vitamin B12 (98.5 +/- 22.3 pmol l(-1)), folate (2.35 +/- 1.3 nmol l(-1)) and lipids were decreased in group A. The other vascular risk factors, which were not dependent on diet [lipoprotein(a) and endothelin-1], did not differ among the three groups. Conclusion: PKU patients on a strict diet had low vitamin B6, vitamin B12 and folate levels resulting in moderate hyperhomocysteinaemia. The evaluation of these vitamins at short intervals and their supplementation could be an early measure in the prevention of CAD.     

Selenium status of preterm infants: the effect of postnatal age and method of feeding

Indicators of selenium (Se) status were measured in a longitudinal study of 63 preterm and 46 term infants. Se levels in both groups were similar in the first few days of life. Preterm infants fed parenteral nutrition (PN) for several weeks developed very low plasma Se levels (<10/μg/l). In those receiving either breast milk or formula in conjunction with PN, plasma Se also declined over the first 6 weeks. In the breastfed term infants plasma levels increased by 50%, but there was no increase in the term formula-fed group. In healthy preterm infants who received mainly breast milk, plasma Se concentrations remained constant at newborn levels and were below those of breastfed term infants at 6 weeks. Erythrocyte GSHPx activity did not reflect plasma Se or Se intake. In conclusion, the type of feeding, and hence Se intake, influenced plasma Se concentration in preterm infants. Provision of enteral feeding in conjunction with PN was unable to prevent a decline in plasma Se and at 6 weeks levels were well below those of the reference breastfed term infants.     

The influence of metoclopramide on the composition of human breast milk.

The breast milk prolactin (PRL) has been claimed to play a role in the control of electrolyte composition of the milk. Since metoclopramide has been shown to increase milk production in humans, we have made an attempt to investigate the production, the PRL and sodium concentrations in milk with (group I) and without (group II) maternal metoclopramide treatment (5 days, 30 mg/day). Both groups consisted of 11 mothers and their full-term newborn infants. The daily milk production was significantly higher in the treated group (276.4 +/- 36.6 vs 150.9 +/- 25.3 ml/day, p less than 0.01). The PRL measured by RIA was similar in the milk samples of the metoclopramide treated and control groups (80.5 +/- 17.7 vs 90.7 +/- 27.3 ng/ml). The sodium concentration in the milk of mothers taking metoclopramide was 22.1 +/- 1.6 mmol/l and 24.3 +/- 3.2 mmol/l in the control group (p = 0.59). On the 5th postnatal day the plasma PRL of the newborns of mothers treated with metoclopramide does not differ from the values of the control babies (29.8 +/- 2.6 vs 30.7 +/- 2.4 ng/ml) indicating that the amount of metoclopramide transferred into the milk has no apparent influence on the hypothalamo-hypophyseal axis of the neonate. In conclusion: the maternal metoclopramide treatment augments the milk production without having any effect on the PRL and sodium concentration of human "mature" milk.     

Serum total homocysteine concentrations in children and adolescents in Jos, Nigeria

BACKGROUND: Although the elevation of circulating total serum homocysteine (tHcy) concentration in a fasting state is associated with an increased risk of occlusive vascular disease in adults, the levels in children in Nigeria are not known. AIM: The goals of this study were to describe the distribution of tHcy among a representative sample of children and adolescents in Jos, Nigeria, and to test for differences in tHcy among sex and age categories. METHODS: The sampling scheme, which included persons aged 10 to 19 years, was a stratified, multistage probability design. This cross sectional study involved 182 school children drawn from secondary schools in Jos, Nigeria between January and July 2003. Fasting venous samples were collected and assayed for tHcy, Total protein and Albumin. Anthropometric measurements were taken. RESULT: The mean tHcy concentrations were 2.7 +/- 2.4 (95% CI 2.4-2.9), 3.5 +/- 3.2 (3.3-3.8) and 3.6 +/- 3.2 (3.3-4.1), 4.1 +/- 3.6 (4.0-4.4) micromol/l for the girls and boys aged 10-14 and 15-19 years, respectively. Albumin levels correlate positively with plasma total homocysteine, tHcy (r = 0.45, P = 0.03). CONCLUSION: This study provided age-specific data regarding tHcy concentrations between 10-19 years population in Jos, Nigeria. The tHcy concentration increased as a function of age in both sexes.     

Vitamin K status of lactating mothers, human milk, and breast-feeding infants

Hemorrhagic disease of the newborn is a disease of breast-feeding newborns. There is little information on longitudinal breast milk concentrations of phylloquinone (vitamin K1) or the effects of maternal phylloquinone supplements on breast milk. In study part 1, 11 lactating mothers, who received 20 mg of phylloquinone orally, had rises in plasma (less than 1 to 64.2 +/- 31.5 ng/mL by 6 hours) and breast milk concentrations (from 1.11 +/- 0.82 to 130 +/- 188 ng/mL by 12 hours). In part 2, 23 lactating mothers and their infants were observed longitudinally along with a formula-fed control group of infants (n = 11). Mean breast milk concentrations of phylloquinone at 1, 6, 12, and 26 weeks were 0.64 +/- 0.43, 0.86 +/- 0.52, 1.14 +/- 0.72, and 0.87 +/- 0.50 ng/mL, respectively, in the infants fed human milk. Maternal phylloquinone intakes (72-hour dietary recalls) exceeded the recommended daily allowance of 1 microgram/kg per day. Infant phylloquinone intakes did not achieve the recommended daily allowance of 1 microgram/kg per day in any infant. Plasma phylloquinone concentrations in the infants fed human milk remained extremely low (mean less than 0.25 ng/mL) throughout the first 6 months of life compared with the formula-fed infants (4.39 to 5.99 ng/mL). In this small sample, no infant demonstrated overt vitamin K deficiency. Despite very low plasma phylloquinone concentrations, vitamin K supplements (other than in the immediate newborn period) cannot be recommended for exclusively breast-fed infants based on these data.     

Postnatal maternal cortisol levels predict temperament in healthy breastfed infants

BACKGROUND: The implications of the biologically active elements in breast milk for the breastfed infant are largely unknown. Animal models suggest that ingestion of glucocorticoids during the neonatal period influences fear behavior and modifies brain development. AIMS: To determine the association between postnatal maternal cortisol levels and temperament in breastfed infants. STUDY DESIGN: The relation between maternal cortisol and infant temperament was examined in breastfed and formula-fed infants. Plasma cortisol was used as a surrogate measure for breast milk cortisol levels (plasma and milk levels are correlated in the 0.6 to 0.7 range; [Patacchioli FR, Cigliana G, Cilumbriello A, Perrone G, Capri O, Alemà GS, et al. Maternal plasma and milk free cortisol during the first 3 days of breast-feeding following spontaneous delivery or elective cesarean section. Gynecologic and Obstetric Investigations 1992;34:159-163.]. If exposure to elevated cortisol levels during infancy influences temperament, then a relation between the two should be found among the breastfed infants, but not among the formula-fed infants. SUBJECTS: Two hundred fifty-three two-month-old infants and their mothers. OUTCOME MEASURES: Fearful temperament assessed with the Infant Behavior Questionnaire [Garstein MR, Rothbart MK. Studying infant temperament via the revised infant behavior questionnaire. Infant Behavior and Development 2003;26:64-86]. RESULTS: Among the breastfed infants, higher maternal cortisol levels were associated with reports of increased infant fear behavior (partial r=0.2; p<0.01). This relation did not exist among the formula-fed infants. Negative maternal affect at the time of assessment did not account for the positive association in the breastfed group. CONCLUSIONS: The findings are consistent with our proposal that exposure to cortisol in breast milk influences infant temperament. Biologically active components in breast milk may represent one avenue through which the mother shapes the development of the human infant during the postnatal period.     

Plasma homocysteine levels and folate status in children with sickle cell anemia.

PURPOSE: A sensitive inverse relationship between plasma homocysteine concentration and folate status has been demonstrated. Although children with sickle cell anemia (SCA) are at potential risk for folate deficiency, plasma homocysteine levels have not been reported in such patients. Therefore, a study was designed to assess plasma homocysteine levels as a marker of folate status. DESIGN: Plasma homocysteine concentrations were measured in 120 children with SCA (102 in steady state and 18 during an acute complication) who had never received supplemental folic acid. Folate status was directly assessed in 34 of these patients. RESULTS: Plasma homocysteine levels in the patients with SCA and control subjects were similar. The mean value +/- 1 SD was 5.8+/-2.5 micromol/L (range, 1.6 to 14.1 micromol/L) in the patients with SCA and 6.1+/-2.7 micromol/L (range, 1.7 to 15.3 micromol/L) in 73 pediatric control subjects. In a subpopulation of the study group (34 children), simultaneous serum folate, red cell folate, and total homocysteine concentrations were also measured. Their serum folate and red cell folate concentrations were normal: 12.4+/-10.0 nmol/L (range, 1 to 42 nmol/L) and 604+/-374.7 nmol/L (range, 205 to 1741 nmol/L), respectively. There was no correlation of plasma homocysteine concentration with various clinical or laboratory measures or with red cell folate concentration. CONCLUSION: Folate stores in children with SCA not receiving folic acid supplements are adequate despite an underlying hemolytic anemia.     

Molybdenum in the premature infant

The molybdenum (Mo) levels in the plasma and urine of 30 premature and 15 full-term infants have been compared with the Mo intakes and urine uric acid excretion (uric acid/creatinine ratio) produced by the Mo enzyme xanthine oxidase. The Mo intakes of full-term infants were 41 +/- 14 nmol/kg/day (mean +/- SEM). In the premature group breast milk supplied significantly less Mo (4.3 +/- 0.4 nmol/kg/day) than infant formulas (101 +/- 31 nmol/kg/day) or premature formula (255 +/- 13 nmol/kg/day). When fed breast milk, the preterm infants displayed similar or higher plasma and urine Mo and urine uric acid levels than formula-fed infants. For the whole preterm group a significant correlation was determined for urine Mo levels and Mo intakes as well as for plasma Mo and uric acid excretion. The bioavailability of breast milk Mo seems to be higher than formula Mo according to the Mo levels and to their statistical link with uric acid excretion which could be proposed as a functional index of Mo status. These parameters displayed similar values in breast milk-fed prematures and control full-term infants. The Mo needs of formula-fed premature newborns remain to be defined using complete balance trials.     

Infant feeding and early neonatal jaundice

The feeding patterns and third day serum bilirubin levels were evaluated in 30 newborn infants receiving formula feeds in the neonatal special care unit and in 30 breastfed babies. Initiation of milk feeds were delayed in breast-fed babies and the frequency of feeding was significantly lower than in the formula-fed infants. Supplementary water was given only in the breast-fed group. Serum bilirubin levels were significantly higher in breast-fed infants (9·74±3·17 ml/dl) than those on formula (6·59±3·50 mg/dl), t=3·69, p<0·001). There appeared to be no influence of supplementation with water.     

Abnormalities in zinc homeostasis in young infants with cystic fibrosis

Low plasma zinc concentrations have been reported in approximately 30% of young infants with cystic fibrosis identified by newborn screening. The objective of this study was to examine zinc homeostasis in this population by application of stable isotope methodology. Fifteen infants with cystic fibrosis (9 male, 6 female; 7 breast-fed, 8 formula-fed) were studied at a mean (+/-SD) age of 1.8 +/- 0.7 mo. On d 1, 70Zn was administered intravenously, and 67Zn was quantitatively administered with all human milk/formula feeds during the day. Three days later, a 3-d metabolic period was initiated, during which time intake was measured and complete urine and fecal collections were obtained. Fractional zinc absorption, total absorbed zinc, endogenous fecal zinc, and net absorbed zinc were measured; fecal fat excretion was also determined. Fractional absorption was significantly higher for the breast-fed infants (0.40 +/- 0.21) compared with the formula-fed group (0.13 +/- 0.06) (p = 0.01), but with the significantly higher dietary zinc intake of the formula-fed group, total absorbed zinc was higher for those receiving formula (p = 0.01). In 1 infants with complete zinc metabolic data, excretion of endogenous zinc was twofold greater for the formula-fed infants (p < 0.05); net absorption (mg zinc/d) was negative for both feeding groups: -0.04 +/- 0.52 for breast-fed; -0.28 +/- 0.57 for formula-fed. Endogenous fecal zinc losses correlated with fecal fat excretion (r = 0.89, n = 9, p = 0.001), suggesting interference with normal conservation of endogenously secreted zinc. These findings indicate impaired zinc homeostasis in this population and suggest an explanation for the observations of suboptimal zinc status in many young infants with cystic fibrosis prior to diagnosis and treatment.     

Plasma homocysteine levels in children and adolescents with type 1 diabetes

OBJECTIVE: Hyperhomocysteinemia has been established as a risk factor for cardiovascular disease. The objective was to investigate total plasma homocysteine concentrations in children and adolescents with type 1 diabetes and a control group. METHOD: Twenty-seven children with type 1 diabetes and 27 subjects of an age- and sex-matched control group were recruited. Fasting samples were collected for plasma total homocysteine, serum vitamin B12, folate, and creatinine. RESULTS: Fasting total homocysteine concentrations showed no difference between patients and controls (5.6 +/- 2.9 micromol/L vs 5.7 +/- 2.2 micromol/L; p greater than 0.05). The diabetic patients had significantly higher serum folate than the healthy controls (11.4 +/- 3.3 ng/mL vs 9.4 +/- 4.1 ng/mL; P = 0.02 and higher serum B12 than the control group (282.8 +/- 119 pg/mL vs 228.5 +/- 50.9 pg/mL; P = 0.03). Total plasma homocysteine concentration correlated with age (r = 0.44, P = 0.02), weight (r = 0.56, P = 0.002), body mass index (r = 0.57, P = 0.002), folate (r = -0.48, P = 0.01), and creatinine (r = 0.41, P = 0.03) in diabetic patients. In stepwise multivariate regression model for diabetics, the independent correlates for total plasma homocysteine concentration was folate (P = 0.002). CONCLUSION: We concluded that fasting plasma total homocysteine concentrations were within normal limits in children and adolescents with type 1 diabetes who were without any clinical evidence of microvascular and macrovascular complications.     

Hypoantigenic (HA) milk formula and blood cholesterol level in infants at 3 months of age

A preliminary observation is reported concerning total and high-density lipoprotein blood cholesterol levels in 36 infants at 3 months of age fed with a hypoantigenic milk formula. The values are compared with those of 66 breastfed and 76 conventional formula-fed infants. Total and high-density lipoprotein-cholesterol levels in hypoantigenic formula-fed infants (152 and 65. 7 mg dl^-1, respectively) were comparable to those of breastfed infants (148 and 61. 8 mg dl^-1) and significantly ( p <0. 05) higher than those of conventional formula-fed infants (130 and 42. 5 mg dl^-1).     

Homocysteine, MTHFR C677 T, vitamin B12, and folate levels in Thai children with ischemic stroke: a case-control study

Hyperhomocysteinemia has been identified as a risk factor for venous and arterial thrombosis especially in adult populations. Twenty-eight patients with an initial diagnosis of ischemic stroke and 100 controls, aged 相似文献   

Neural maturation of breastfed and formula-fed infants

Background: Human milk provides infants with a full complement of all polyunsaturated fatty acids, including docosahexaenoic acid (DHA) and arachidonic acid (AA). Formula milks only contain the precursors of DHA, AA and linoleic acid, and hence formula-fed infants must synthesize their own DHA and AA. Aim: To evaluate the effect of feeding—whether breastfeeding or formula-feeding—in early infancy upon subsequent neurodevelopment and achievement of optimum brain function. Subjects and methods: The study included 53 normal, healthy infants (30 exclusively breastfed infants and 23 exclusively formula-fed infants) at the age of 1 y (±1 mo). Each infant was subjected to a full physical and neurological examination together with neurophysiological studies including flash visual evoked potential (FVEP), brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP). Results: There was significant prolongation of P ₁₀₀ wave latency of FVEP in formula-fed infants, together with significant prolongation of absolute latency of waves I, III and V of BAEP in formula-fed infants compared with breastfed infants. There was significant prolongation in inter-peak latencies between cortical and Erb's components in formula-fed infants compared with breastfed infants.

Conclusion: We can conclude that VEP, BAEP and SSEP are more mature in breastfed infants relative to formula-fed infants at 1 y of age, and thus breast milk helps earlier development and maturation of some aspects of the nervous system than milk formulas.     

Vitamin D nutritional status of premature infants supplemented with 500 IU vitamin D2 per day

The vitamin D nutritional status of premature infants was assessed by determining plasma 25-hydroxyvitamin D concentrations before and during supplementation with 500 IU vitamin D2 per day. Fifty-one samples were collected from 25 healthy infants fed breast milk and a vitamin D3 fortified formula. Gestational age was 32.2 +/- 2.4 weeks (mean +/- 1 SD). 25-hydroxyvitamin D levels before supplementation correlated well with maternal values (r = 0.81). The infants' mean plasma concentration increased from 30.6 +/- 13.7 nmol/l (mean +/- 1 SD) after birth to 46.3 +/- 10.5 nmol/l after 9 +/- 1 days (p less than 0.0025), and to 65.3 +/- 16.6 nmol/l after 37 +/- 10 days of vitamin D2 treatment (p less than 0.0005). 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 were determined separately, and it appeared that the rise was accounted for by the D2 fraction while 25-hydroxyvitamin D3 concentrations were unchanged. The results demonstrate that vitamin D2 is well absorbed and hydroxylated in the 25 position by premature infants free of associated disease, and that a supplementation of 500 IU per day in addition to breast milk and a regular vitamin D fortified formula is adequate to rapidly establish 25-hydroxyvitamin D levels within the normal adult range.     

窒息新生儿血清同型半胱氨酸与叶酸的变化

目的：探讨血清中高同型半胱氨酸（Hcy）血症及低叶酸水平与新生儿窒息的发生是否具有相关性,并对性别、胎龄等因素对血清中同型半胱氨酸及叶酸水平是否有一定影响进行分析。方法：应用酶联免疫吸附实验方法检测血清中Hcy水平,应用放射免疫法测定血中叶酸浓度。结果：①与无窒息对照组相比, 新生儿窒息患儿血清Hcy水平显著升高,而叶酸水平显著降低;②窒息组男婴血清Hcy、叶酸水平分别为15.82 ±2.51 μmol/L; 2.49 ±0.19 ng/mL,女婴为10.50±2.19 μmol/L; 2.38±0.40 ng/mL,男、女婴之间比较差异无显著性;③窒息组足月儿血清Hcy、叶酸水平为12.34 ±2. 01 μmol/L,2.58 ±0.19 ng/mL;早产儿为21.25±5.01 μmol/L; 2.14±0.34 ng/mL。早产儿Hcy水平显著高于足月儿（P<0.05）。结论：①新生儿窒息与血清Hcy及叶酸水平具有显著相关性。②血清Hcy及叶酸水平在性别上无显著差异。③缺氧窒息合并早产者血清Hcy水平升高最为显著。     

Dietary glutamate is almost entirely removed in its first pass through the splanchnic bed in premature infants

Breast milk glutamate is a potential gluconeogenic substrate. However, in piglets, most dietary glutamate undergoes first pass extraction by the gut, limiting its contribution to glucose formation. The objectives of the study were to determine in preterm infants, whether dietary glutamate increases plasma [glutamate] in a dose-dependent fashion and whether glutamate carbon appears in plasma glucose to an appreciable extent. Five enterally fed infants (31 +/- 0 wk; 1555 +/- 131 g) (mean +/- SE) were studied twice (postnatal age 10 +/- 1 d and 17 +/- 1 d, respectively), while receiving an intragastric infusion of glutamate (labeled to 4% +/- by [U-13C] glutamate) at 2.4 (study 1) and 4.8 micromol/kg/min (study 2) for 1.5 h (n=2) or 5 h (n=3). Plasma [glutamate] was 82 +/- 8 microM at baseline, and 84 +/- 11 and 90 +/- 13 microM after glutamate supplementation at 2.4 and 4.8 micromol/kg/min, respectively, values not different from baseline. Plasma [glutamate] was not affected by the duration of the glutamate infusion (1.5 versus 5 h). Plasma 13C glucose enrichment was only 0.3% (after 5 h ingestion of glutamate labeled to 4%) indicating insignificant contribution of dietary glutamate carbon to glucose. Thus, in premature infants, splanchnic extraction is the major fate of dietary glutamate, which is not a significant gluconeogenic substrate in these infants.