Plasma homocysteine concentrations of preterm infants.

Mild hyperhomocysteinemia in adults is associated with an increased risk of vascular disease. Although information is available about plasma homocysteine concentrations in childhood, data are entirely lacking for preterm infants despite their known abnormalities of sulfur amino acid metabolism. We measured plasma total homocysteine concentrations of 9 preterm infants (gestational age 23-31 weeks) within 48 h of birth and over the subsequent 14 days of life, and 4 term infants (gestational age 36-39 weeks) on a single occasion within 72 h of birth. As measured within 48 h of birth, average plasma homocysteine and cysteine concentrations of the preterm infants were 3.8 +/- 0.3 and 122 +/- 8 microM, both significantly less than those of the term infants (6.1 +/- 1.3 and 187 +/- 39) and of normal adults (8.2 +/- 0.5 and 232 +/- 6). Plasma homocysteine (but not cysteine) appeared to gradually increase during the first 2 weeks of life (p = 0.053). Our results indicate that hyperhomocysteinemia does not normally occur in preterm infants.     

High total and free 1,25-dihydroxyvitamin D concentrations in serum of premature infants

We investigated the relationship between serum total and free 1,25-dihydroxyvitamin D (1,25-OH2D) and the biochemical regulation of 1,25-OH2D production in premature infants. We measured 1,25-OH2D, vitamin D binding protein and related biochemical parameters and calculated the free 1,25-OH2D index in serum of 17 premature infants (birthweight 810-1700 g; gestational age 31-36 weeks) on two different occasions defined by body weight (Study A: 1,750-1,850 g, Study B: 2,100-2,200 g). Dietary calcium (Ca) intake was 1,5 or 2,6 mmol/kg/d, phosphorus (P) intake 1,7 mmol/kg/d and vitamin D intake 1,000 IU/d. Biochemical results were similar in infants with different Ca intakes and all were within reference ranges. Concentrations of vitamin D binding protein (Study A 0.15 +/- 0.03 g/l, Study B 0.14 +/- 0.03 g/l; means +/- SD) were lower, concentrations of 1,25 (OH)2D (Study A 180 +/- 67 pmol/l, Study B 216 +/- 53 pmol/l) were higher, and consequently the free 1,25-OH2D index (Study A 6.6 +/- 2.7, Study B 8.8 +/- 2.6) was 4 to 6 times higher than in previously studied term infants. 1,25-OH2D and the free 1,25-OH2D index increased significantly with age and were not correlated with serum P or parathyroid hormone. The data indicate that in premature infants with normal biochemical parameters of Ca and P metabolism elevated concentrations of 1,25-OH2D signify an increased fraction of free 1,25-OH2D and that increased production of 1,25-OH2D is not due to hypophosphatemia or hyperparathyroidism.     

Plasma 1.25-Dihydroxyvitamin D Concentrations in Preterm Infants

ABSTRACT. 1.25-Dihydroxyvitamin D concentrations were measured in 10 preterm infants (mean gestational age 29 weeks, range 26-32; mean birthweight 1226 g, range 980-1700). Total parenteral nutrition was begun after birth and partial enteral feeding was started at 1 week of age. Total enteral feeding was achieved at a mean age of 26 days (range 16-47). The daily vitamin D₃ intake was about 400 I. U. No clinical, chemical or radiological signs of rickets were observed. The mean 1.25-dihydroxy vitamin D concentration ± SEM was 103.2±24.0 pmol/1 at 1 week (range 9.6-252.0), 141.6±26.4 at 3 weeks (range 31.2-324.0), 153.6±21.6 at 6 weeks (range 67.2- 256.8), 165.6±24.0 at 9 weeks (range 74.4-307.2) and 153.6±21.6 at 12 weeks (range 76.8-268.8) postnatal age. The mean values at 6, 9 and 12 weeks were significantly higher ( p resp. <0.01, <0.002 and <0.005) than in adults (88.8±7.2; n =27). 1.25-Dihydroxyvitamin D concentrations were highly variable and did not correlate with 25-hydroxyvitamin D concentrations, plasma calcium and phosphorus concentrations and plasma alkaline phosphatase levels, nor with illness nor postnatal age. The data demonstrate that preterm infants are capable of producing high plasma levels of 1.25-dihydroxy vitamin D.     

Plasma concentrations of vitamin D metabolites in unsupplemented breast-fed infants

Plasma concentrations of the vitamin D metabolites 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, 24,25-dihydroxyvitamin D and 25,26-dihydroxyvitamin D were determined in 12 solely breast-fed infants 4 days and 6 weeks after birth. They were not exposed to sunlight, but the mothers received an average of 600 IU vitamin D2 per day during the study period. The mothers' 25-hydroxyvitamin D levels did not change significantly (medians 42 and 58 nmol/l), but the median level dropped from 26 to 15 nmol/l in the infants (P less than 0.001). There was a close correlation between maternal and infant levels at 4 days (r = 0.95). The babies with the highest initial levels showed the most marked decrease by 6 weeks. The median concentrations of 24,25-dihydroxyvitamin D and 25,26-dihydroxyvitamin D decreased similarly from 1.7 to 0.8 and 0.63 to 0.35 nmol/l respectively, (P less than 0.001). The 1,25-dihydroxyvitamin D levels were within normal limits as were plasma calcium, phosphorus, and alkaline phosphatase. The data suggest that fetal stores of vitamin D may be rapidly depleted, and that breast milk may be inadequate as the only source of vitamin D, even for breast-fed infants of vitamin D-supplemented mothers.     

Trough lopinavir concentrations in preterm HIV-infected infants

Because of serious adverse effects, the Food and Drug Administration warns against using lopinavir in infants younger than 42 weeks postconception. However, there is an imperative for early treatment. We report on our use of LPV in 8 premature HIV-infected infants. The median age at initiation was 27 days. Trough values guided dosing. Five infants needed doses above 300 mg/m. Although no adverse events were noted, lopinavir usage requires caution and careful monitoring.     

Plasma testosterone in preterm infants with cryptorchidism.

Cryptorchidism is common in infants born preterm, yet the mechanism for its occurrence is still debated. In a study of 21 premature babies with cryptorchidism at 18 months post-term and 21 case matched controls, cryptorchid preterm infants failed to show the normal rise in plasma testosterone in the first postnatal week. This rise is thought to relate to residual maternal human chorionic gonadotrophin in the neonatal circulation. Infants with cryptorchidism also failed to show the later testosterone surge in the second month which has been related to endogenous gonadotrophin release. We speculate that inadequate stimulation of testosterone release by human chorionic gonadotrophin in the fetus might contribute to the pathogenesis of cryptorchidism in preterm infants. Our findings have implications for the medical treatment or possible prophylaxis of undescended testes in premature babies.     

Blood spot glucocorticoid concentrations in ill preterm infants.

The adrenocortical response to stress was studied longitudinally in 10 ill preterm infants using measurements of cortisol and 170H-progesterone concentrations in filter paper blood spots. Mean cortisol and 170H-progesterone concentrations reached a peak of 2200 nmol/l and 65 nmol/l, respectively, between the third and fifth days of life. These concentrations far exceeded those observed in older children and adults subjected to stress as a result of surgery. Further pulses of endogenous cortisol production of 4000 nmol/l or more occurred in association with clinical complications such as intraventricular haemorrhage. These results indicate that infants undergoing intensive care are unduly stressed. Consideration should be given to providing enough sedation and appropriate analgesia for ill preterm infants during painful procedures such as insertion of venous cannulae and arterial puncture.     

Gut hormone concentrations in preterm infants with necrotizing enterocolitis

Abstract Blood levels of gastrin, neurotensin and vasoactive peptide (VIP) were estimated in 14 premature infants with necrotizing enterocolitis (NEC) and in 12 controls. In comparison to the control group, infants with NEC had (a) significantly lower gastrin levels both before [9.3 (7.8) versus 33.7 (27.1)] and after [52.4 (48.1) versus 100.8 (50.9)] the development of NEC; (b) significantly lower neurotensin levels only after the development of NEC [37.8 (10.4) versus 54.5 (20.6)]; and (c) no significant difference in VIP values [25.4 (9.7) versus 18.9 (9.9) and 24.5 (15.7) versus 26.1 (19.1)]. It is concluded that NEC can adversely affect gastrin and neurotensin concentrations in the blood.     

早产儿维生素D需求

美国儿科学会建议新生儿、儿童、青少年尽早开始补充维生素D,推荐补充量为400IU/d,同时建议早产儿也应补充维生素D,但未指出早产儿维生素D的具体需要量.早产儿需要综合考虑胎儿及新生儿的健康需求,因此,调研维生素D的需要量,明确体内维生素D的状态,评价补充剂量的安全性及有效性对保证早产儿的健康有决定性意义.     

Plasma bilirubin level and oxidative stress in preterm infants

OBJECTIVE: To assess the hypothesis that changes in plasma total bilirubin levels (Btot) can influence the antioxidant system and oxidative stress in preterm infants. METHODS: Twenty two healthy preterm infants who presented with visible non-haemolytic hyperbilirubinaemia were studied at the mean (SD) age of 3.7 (1.5) days. Btot, plasma total hydroperoxide concentration (TH), plasma protein SH group concentration, and total antioxidant capacity of the plasma (TAC) were measured at study entry and after 24 hours. RESULTS: Btot did not correlate with TH, TAC, or protein SH group concentration, but a significant correlation was found between TH and TAC, TH and protein SH groups, and TAC and protein SH groups, both at study entry and after 24 hours. CONCLUSION: The decrease in plasma bilirubin was contemporary with an increase in plasma antioxidant capacity and decrease in oxidative stress in preterm infants. This may be the result of the pro-oxidant effect of haem oxygenase, mediated by iron release, which may outcompete the antioxidant properties of bilirubin.     

Plasma prolactin and clinical outcome in preterm infants.

Plasma prolactin was measured weekly in 280 preterm infants. The complex gestational age dependent pattern of postnatal prolactin release has been defined and reference standards provided. Plasma prolactin was higher in girls, with increasing divergence between the sexes from the third week onwards, and higher after two weeks, in infants of mothers with pregnancy related hypertension. Diet, assigned randomly, exerted a major effect on plasma prolactin, with significantly higher values in infants fed donor breast milk or standard formula than in those fed a protein, energy, and mineral enriched preterm formula. After adjusting for confounding factors, infants with the lowest plasma prolactin concentrations (less than 1000 mU/l, 32.9 micrograms/l) occurring usually at a nadir between days 5 and 12, showed a 120% increase in the duration of ventilatory assistance required, a 20% increase in the number of days to attain full enteral feeds, and a 30% decrease in length gain. We suggest preterm birth disrupts the normal perinatal pattern of prolactin release and that those infants who develop relatively low plasma concentration have an adverse outcome. Our data add to the broader debate on whether preterm infants require multiple endocrine replacement treatment.     

Plasma fibronectin concentrations in healthy and septic infants

The concentration of plasma fibronectin was determined by Laurell's electroimmunoasay [15] in 75 preterm or term newborns within the first 2 days of life, in 97 healthy infants aged from 3 days to 12 months, in 40 septic infants and in 38 healthy adult subjects. The mean fibronectin concentration in citrated plasma of normal adults was 318±84 ml/l. Healthy eutrophic term newborns 1–2 days old had approximately one-third of the fibronectin concentration of adults. There was no significant difference in the values between healthy term and eutrophic preterm newborns or between eutrophic and hypotrophic newborns. The plasma fibronectin increased strongly over the 1st month of life. No significant difference was observed between fibronectin levels in infant boys and girls. The values in septic newborns and septic older infants were significantly lower when compared with those of age-matched healthy controls. It is speculated that this deficiency, because of linkage to fibrin in disseminated intravascular coagulation or due to increased utilisation as a non-specific opsonin and sequestration at sites of tissue injury, may contribute to organ failure in septicaemia.Abbreviations SB surface binding - DIC disseminated intravascular coagulation     

Plasma 17OH-progesterone concentrations in newborn infants.

Plasma concentrations of 17OH-progesterone were determined in 60 normal newborn infants aged between 3 and 36 hours. Mean levels decreased rapidly during this time after removal of the placental contribution of this steroid. A further 70 normal infants, studied between ages 2 and 7 days, showed a mean plasma 17OH-progesterone concentration of 3.5 nmol/1 (1.2 ng/ml). By comparison, plasma concentrations in untreated infants with congenital adrenal hyperplasia were markedly raised. At 36 hours of age, there was an obvious difference between plasma levels of this steroid in normal and affected infants. Determination of plasma 17OH-progesterone concentrations are valuable in the evaluation of disorders of sexual differentiation and electrolyte balance in newborn infants, provided due care is given to the timing of sample collections.     

Cord blood concentrations of vitamin A in preterm infants.

Plasma vitamin A concentrations were measured in cord blood samples from 56 infants of gestational ages < 33 weeks. Outcome was followed prospectively. Mothers' dietary habits and use of multivitamins during pregnancy were evaluated by means of a questionnaire. Vitamin A concentrations less than 1.05 micromol/l (low) were measured in 22, but levels below 0.7 micromol/l (deficient) only in two cases. The concentrations were not correlated with the infants' gestational ages. Infants with low concentrations were significantly more often multiplets compared to those with normal levels and the vitamin A concentrations of the multiplets were significantly lower than those of the singletons. The outcome measures used and the mothers' dietary habits and multivitamin use were similar in cases with low and normal vitamin A concentrations. Multiple gestation seems to be correlated with low plasma vitamin A concentrations in preterm infants at birth, and a complete assessment of vitamin A status to detect possible deficiency might be indicated in these cases.