Investigation of urine proteome of preterm newborns with respiratory pathologies.

A serious problem during intensive care and nursing of premature infants is the invasiveness of many examination methods. Urine is an excellent source of potential biomarkers due to the safety of the collection procedure. The purpose of this study was to determine the features specific for the urine proteome of preterm newborns and their changes under respiratory pathologies of infectious and non-infectious origin. The urine proteome of 37 preterm neonates with respiratory diseases and 10 full-term newborns as a control group were investigated using the LC-MS/MS method. The total number of identified proteins and unique peptides was 813 and 3672 respectively. In order to further specify the defined infant-specific dataset these proteins were compared with urine proteome of healthy adults (11 men and 11 pregnant women) resulting in 94 proteins found only in infants. Pairwise analysis performed for label-free proteomic data revealed 36 proteins which reliably distinguished newborns with respiratory disorders of infectious genesis from those with non-infectious pathologies, including: proteins involved in cell adhesion (CDH-2,-5,-11, NCAM1, TRY1, DSG2), metabolism (LAMP1, AGRN, TPP1, GPX3, APOD, CUBN, IDH1), regulation of enzymatic activity (SERPINA4, VASN, GAPDH), inflammatory and stress response (CD55, CD 93, NGAL, HP, TNFR, LCN2, AGT, S100P, SERPINA1/C1/B1/F1).

Newborn Urinary Metabolic Signatures of Prematurity and Other Disorders: A Case Control Study.

This work assesses the urinary metabolite signature of prematurity in newborns by nuclear magnetic resonance (NMR) spectroscopy, while establishing the role of possible confounders and signature specificity, through comparison to other disorders. Gender and delivery mode are shown to impact importantly on newborn urine composition, their analysis pointing out at specific metabolite variations requiring consideration in unmatched subject groups. Premature newborns are, however, characterized by a stronger signature of varying metabolites, suggestive of disturbances in nucleotide metabolism, lung surfactants biosynthesis and renal function, along with enhancement of tricarboxylic acid (TCA) cycle activity, fatty acids oxidation, and oxidative stress. Comparison with other abnormal conditions (respiratory depression episode, large for gestational age, malformations, jaundice and premature rupture of membranes) reveals that such signature seems to be largely specific of preterm newborns, showing that NMR metabolomics can retrieve particular disorder effects, as well as general stress effects. These results provide valuable novel information on the metabolic impact of prematurity, contributing to the better understanding of its effects on the newborn's state of health.

Developmental pattern of urinary bile acid profile in preterm infants.

BACKGROUND: Bile acid metabolism in preterm infants is yet to be fully characterized. We compared the developmental pattern of urinary bile acid profiles in ten infants born at gestational ages from 25 to 33 weeks with previous data from full-term infants from birth to about 7 months of age. METHODS: Gas chromatography-mass spectrometry was performed on serial samples. RESULTS: Total urinary bile acid concentrations gradually increased until 1 to 2 months of age. After this peak of excretion (30 to 60 micromol/mmol creatinine), total urinary bile acid concentrations gradually decreased to less than 20 micromol/mmol creatinine. The percentage of usual bile acids (mainly cholic acid) relative to total urinary total bile acids gradually deceased from approximately 30% at birth to less than 15% at 7 months of age. On the other hand, 1beta-hydroxylated bile acids (mainly 1beta,3alpha,7alpha,12alpha-tetrahydroxy-5beta-cholan-24-oic acid) relative to total urinary bile acids were increased gradually from 60% at birth to reach 70% to 80% at 1 month of age. The percentage of 1beta-hydroxylated bile acids relative to total urinary bile acids then remained stable at a high percentage (70% to 90%) until the age of 7 months. CONCLUSION: Physiological cholestasis in preterm infants persists longer than in full-term infants. Moreover, as large amounts of cholic and 1beta,3alpha,7alpha,12alpha-tetrahydroxy-5beta-cholan-24-oic acids were detected in urine from preterm infants during this study, the 25-hydroxylation pathway may be particularly important for bile acid synthesis in early preterm infants.

Neonatal transient respiratory depression after maternal urapidil infusion for hypertension.

Urapidil is a potent antihypertensive drug that has been in clinical use for more than 20 years. It has been proven to be an effective and well-tolerated antihypertensive drug during pregnancy, but clinical experiences with urapidil have been described in only a limited number of studies. There have also been only limited observations on the (side-)effects of urapidil on the neonate. We describe here a case of postnatal transient respiratory depression following maternal administration of urapidil. We suggest that the fetal and neonatal effects of more recently implemented antihypertensive drugs, such as urapidil, should be included in a prospective evaluation of antihypertensive treatment of women during pregnancy. Infants of mothers who received urapidil should be carefully watched in the immediate postnatal phase as urapidil may still exert some significant effects on the neonate.

Urinary citrate in preterm and term babies.

OBJECTIVES: (1) To determine a normal range for urinary citrate for term babies. (2) To compare urinary citrate measured in ex preterm babies at term with this normal range. (3) To evaluate whether urinary citrate was related to presence of nephrocalcinosis (NC) and chronic Lung Disease (CLD) in these ex preterm babies. STUDY DESIGN: Urinary citrate was measured in 38 healthy term babies (mean birth weight 3.52 kg, mean gestation 41 weeks) at a mean postnatal age of 3 days (1-5 days) and in 53 ex preterm babies (<32 weeks gestation at birth) at term. These preterm babies were part of a larger study on NC in which two renal ultrasound scans were performed at 1 month and term. RESULTS: The normal range for urinary citrate in term babies was 0.025-2.97 (mean 1.03) mmol/l and citrate/creatinine ratio 0.0011-0.852 (mean 0.27). In the ex-preterm urinary citrate was not significantly different (mean 1.1 vs. 1.03, p=0.7232) but urine citrate/creatinine ratio was significantly higher (mean 1.27 vs. 0.27, p=0.0005). There was no significant difference in urinary citrate or ratios of citrate/creatinine and calcium/citrate in the 11 (20.7%) with NC or in the 17 (32%) babies with CLD. There was no significant relationship found between duration of TPN and urinary citrate measured at term. CONCLUSION: We have determined a normal range for urinary citrate in healthy term babies in the first week of life. The range was very wide. Ex preterm babies had similar values at term and there was no association between urinary citrate and NC or CLD.

Urinary citrate in preterm and term babies.

OBJECTIVES: (1) To determine a normal range for urinary citrate for term babies. (2) To compare urinary citrate measured in ex preterm babies at term with this normal range. (3) To evaluate whether urinary citrate was related to presence of nephrocalcinosis (NC) and chronic Lung Disease (CLD) in these ex preterm babies. STUDY DESIGN: Urinary citrate was measured in 38 healthy term babies (mean birth weight 3.52 kg, mean gestation 41 weeks) at a mean postnatal age of 3 days (1-5 days) and in 53 ex preterm babies (<32 weeks gestation at birth) at term. These preterm babies were part of a larger study on NC in which two renal ultrasound scans were performed at 1 month and term. RESULTS: The normal range for urinary citrate in term babies was 0.025-2.97 (mean 1.03) mmol/l and citrate/creatinine ratio 0.0011-0.852 (mean 0.27). In the ex-preterm urinary citrate was not significantly different (mean 1.1 vs. 1.03, p=0.7232) but urine citrate /creatinine ratio was significantly higher (mean 1.27 vs. 0.27, p=0.0005). There was no significant difference in urinary citrate or ratios of citrate/creatinine and calcium/citrate in the 11 (20.7%) with NC or in the 17 (32%) babies with CLD. There was no significant relationship found between duration of TPN and urinary citrate measured at term. CONCLUSION: We have determined a normal range for urinary citrate in healthy term babies in the first week of life. The range was very wide. Ex preterm babies had similar values at term and there was no association between urinary citrate and NC or CLD.

Urinary free cortisol (UFC) values in newborns under stress.

UNLABELLED: Children with adrenocortical insufficiency are commonly instructed to increase three to five times baseline glucocorticoid replacement dose during periods of stress such as surgery or febrile illness. The present study was undertaken to determine whether these recommendations reflect the actual change in urinary free cortisol (UFC) output during stress in neonates and to test the effect of stress on the diurnal variation of cortisol in this age group. DESIGN AND PATIENTS: Twenty-four hour urinary free cortisol (UFC) excretion was determined in 75 neonates during the first 2 days of life. Thirty were healthy and 45 were neonates with respiratory distress. In 60 babies the 24-h UFC was collected in 6-h fractions for the determination of diurnal variation of urinary cortisol. RESULTS: The mean change in UFC was 4.5 times higher in the sick babies than in the controls. A distinct diurnal variation of UFC was noted in both healthy and sick babies. CONCLUSIONS: In contrast with previous publications a distinct diurnal pattern was noted in the majority of neonates.

Eight-epi-PGF2alpha: a possible marker of lipid peroxidation in term infants with severe pulmonary disease.

A prostaglandin F2-like compound, 8-epi-PGF2alpha, formed from oxidation of arachidonate, has been proposed as an indicator of lipid peroxidation. We determined whether tracheal aspirate or urinary 8-epi-PGF2alpha levels would differ over time or between infants in a control group and infants with severe respiratory failure. We correlated tracheal aspirate 8-epi-PGF2alpha levels with the fraction of inspired oxygen and with mean airway pressures at 24 and 48 hours of life. Levels in tracheal aspirates were in the range of 0 to 36 pg/microg of fSC of IgA and were higher in infants with severe pulmonary disorders compared with those in infants in the control group (p < 0.02). Urinary concentrations did not discriminate between sick infants and infants in the control group.

Factors influencing the development of melatonin rhythmicity in humans.

The emergence of melatonin rhythmicity was studied in 163 infants between 46-55 weeks postconception by monitoring the excretion of the urinary melatonin metabolite 6-sulfatoxymelatonin (aMT.6S). From this population, we examined the effects of gender, season, multiple birth, home birth, previous sudden infant death syndrome in the family, premature labor, spontaneous rupture of membranes, preeclampsia, intrauterine growth restriction, and nursery lighting on pineal rhythmicity. As previously reported, rhythmic excretion of aMT.6S appeared between 49-55 weeks postconception (9-15 weeks of age) in singleton babies born at term in the hospital. Full-term infants who had a sibling die of sudden infant death syndrome had a pattern of melatonin rhythm development no different from that of the control full-term infants. In contrast, full-term infants born at home and full-term twins born in the hospital had significantly lower aMT.6S excretion than hospital-born singleton infants at the same ages despite similar body weights (e.g. at 52 weeks postconception; 1.8 +/- 0.4, 1.1 +/- 0.3, and 3.6 +/ -0.5 nmol/day, respectively). In full-term infants, there was no difference in the development of melatonin rhythmicity between the sexes, with season or method of delivery (vaginal vs. caesarean). The premature infants were divided into 5 groups (babies born after premature labor, premature rupture of membranes, preeclampsia, intrauterine growth restriction, and fetal distress). All premature infants had a delay in the appearance of aMT.6S rhythms in the urine in relation to chronological age. When the infants were compared on the basis of weeks since conception, those infants born after spontaneous premature labor excreted amounts of aMT.6S no different from those of full-term singleton infants during the period of study. In contrast, the premature rupture of membranes, preeclampsia, and fetal distressed infants excreted 50% less aMT.6S, and intrauterine growth restricted infants excreted 67% less at the same postconceptional ages. These differences were due to reduced nocturnal excretion of the metabolite. In an attempt to accelerate the development of melatonin rhythmicity, premature labor and premature rupture of membranes infants were randomly assigned to be totally deprived of light (using phototherapy eye shields) or partially deprived of light by moving them to a dimly lit room each night for the last 3-8 weeks of their stay in the hospital nursery. Babies born after premature labor produced normal amounts of aMT.6S between 46-52 weeks postconception, and this pattern was not affected by the nocturnal light deprivation. Infants born after premature rupture of membranes and totally deprived of light at night had aMT.6S excretion rhythms at 52 weeks postconception no different from those of full-term hospital-born infants or premature labor infants, whereas those in infants placed in dim light were similar to those in untreated premature rupture of membranes infants. These results suggest that premature birth alone is not the sole cause of altered rhythm development; other factors, such as preeclampsia, growth restriction, and nursery lighting, play an important role. The consequences of the delayed appearance of melatonin in infants are not known, but deserve further study.

High-resolution proton nuclear magnetic resonance studies of urine from asphyxiated newborn infants.

High-resolution proton nuclear magnetic resonance spectroscopy was used to study human urine obtained from 10 normal babies and twenty babies with various degrees of neonatal asphyxia, respiratory distress syndrome (RDS), and meconium aspiration syndrome (MAS). All sick babies showed different degrees of oxygen deficiency, indicated by an obvious increase of the lactate signal level in the urine spectra. Changes in the concentration of other urinary metabolites produced from the citric acid cycle were also observed. In extremely serious cases, the signals of some of the major components, including citrate, alpha-ketoglutarate, and succinate, simply disappeared. The spectra of urine, serum, and CSF of an infant suffering from SIDS showed common characteristics of the metabolites.

Urinary growth hormone excretion in preterm neonates.

We measured urinary growth hormone (U-GH), beta 2-microglobulin (U-B2) and serum growth hormone (S-GH) in preterm neonates on days 1, 4, 7, 14 and 28 of age. U-GH as well as U-B2 were high, particularly in the more premature and sick neonates with respiratory failure requiring mechanical ventilation. U-GH showed significant positive correlations with U-B2 throughout the study but with S-GH only on day 7. Therefore, we conclude that in preterm neonates, U-GH mainly reflects the degree of renal proximal tubular function, which is determined by the degree of renal maturation of the subject and of tubular injury due to disease states such as respiratory failure.

Urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) as early markers of renal tubular dysfunction in sick neonates.

Urinary beta 2-microglobulin, creatinine, N-acetyl-beta-D-glucosaminidase (NAG), sodium, potassium and plasma beta 2-microglobulin, and creatinine were measured in 34 healthy neonates (including 15 term, 12 prematures with a birth weight between 1.5 and 2.5 kg, 7 prematures with a birth weight less than 1.5 kg), 29 sick neonates (including 6 term, 10 prematures with a birth weight between 1.5 and 2.5 kg, 13 prematures with a birth weight less than 1.5 kg), and 13 term neonates born with meconium-stained amniotic fluid at 1, 3, and 5 days of age. Our data revealed that urinary beta 2-microglobulin, NAG, NAG index (NAG/creatinine), and the sodium concentration were significantly higher in sick preterm and term neonates than in healthy neonates (p less than 0.05). Urinary concentrations of beta 2-microglobulin and NAG were also higher in neonates born with meconium-stained amniotic fluid than in healthy neonates. We conclude that sick neonates have a higher incidence of acute tubular injury. The elevated levels of urinary beta 2-microglobulin and NAG in neonates born with meconium-stained amniotic fluid indicate the existence of tubular dysfunction, probably due to perinatal distress.

Atrial natriuretic factor and postnatal diuresis in respiratory distress syndrome.

To find out if atrial natriuretic factor plays a part in the control of urine output during the initiation alone or throughout postnatal diuresis in neonates with respiratory distress syndrome, atrial natriuretic factor concentrations and clinical and renal variables were measured prospectively three times during the first three days of life in 13 premature infants. Atrial natriuretic factor concentrations rose significantly between the first and second sample times as did the urine output and output:input ratio. By the time that the third sample was taken, atrial natriuretic factor concentration had decreased significantly since the second sample had been taken, while urine flow was maintained. All subjects initiated a spontaneous diuresis that was related to the second concentration of atrial natriuretic factor. With partial correlation analysis a significant relationship was shown between the concentration of atrial natriuretic factor and the maintenance of urine output throughout the study period. Individual hormone concentrations did not, however, correlate with simultaneous renal variables. Changes in the concentrations of atrial natriuretic factor coincided with initiation of spontaneous diuresis in babies with respiratory distress syndrome, and may have a role in the complex mechanisms that maintain this diuresis.

Decreased urinary citrate in premature infants with lung disease.

Urinary citrate prevents nephrocalcinosis in adults. Premature infants have a high incidence of nephrocalcinosis. We measured urinary citrate (Ucit) and creatinine (Ucre) concentrations in infants with and without lung disease. Ucit was lower in the infants requiring mechanical ventilation than in the controls (mean = 9.7 vs. 15, p = 0.05). Ucit/Ucre ratios were lower in hypercarbic (mean = 0.95 vs. 1.47 in normocarbic, p less than 0.05) and acidotic (mean = 0.57 vs. 1.44 in nonacidotic, p less than 0.004) premature infants. The lowered Ucit of premature infants with lung disease (and acidosis or hypercarbia) may predispose to nephrocalcinosis by increased urinary lithogenesis.

Urinary beta-2-microglobulin excretion in prematures with respiratory distress syndrome.

Urinary concentrations of beta 2-microglobulin (beta 2M) were studied in 25 prematures (less than or equal to 35 weeks) with respiratory distress syndrome (RDS), divided into two groups (group 1: ventilation greater than or equal to 2 days; group 2: oxygenotherapy less than or equal to 4 days), to assess the value of beta 2M in the detection of tubular damage in relation to the severity and management of the respiratory disease. The data were compared with those obtained from 10 healthy controls, matched for birth weight and gestational age. Measurements of beta 2M were made on urine collected on days 1, 3, and 5 until the recovery phase of RDS was reached. Urinary beta 2M values for infants with RDS were increased on days 1 and 3, with respect to the controls, and significantly increased in the ventilated group (8,814 +/- 4,768 vs. 2,594 +/- 3,231 micrograms/l, p less than 0.005 and 7,624 +/- 6,264 vs. 2,762 +/- 2,316 micrograms/l, p less than 0.05, respectively). Serum sodium and creatinine, creatinine clearance, fractional tubular sodium excretion and renal function index on day 1 were similar in prematures with or without RDS. However, the ventilated newborns presented higher urinary sodium excretions. On the 5th day, no significant differences in urinary beta 2M were found among the groups. The elevated levels of urinary beta 2M in the acute phase of RDS and in the more severe lung disease indicate the existence of subclinical tubular dysfunction, probably secondary to hypoxic stress and to negative hemodynamic effects of ventilatory management.

Measurement of urinary caffeine metabolites reflecting the "in vivo" xanthine oxidase activity in premature infants with RDS and in hypoxic states of children.

Grant et al. have demonstrated that after caffeine intake the ratio of 1-methyluric acid (MU) and 1-methylxanthine (MX) in the urine indicates the total xanthine oxidase (XO) activity of the organism. It has been stated - after having applied this method on premature infants with severe respiration distress syndrome (17 cases) and on children in need of intensive care (18 cases) in the critical phase and during the reparation of the same patients as well, furthermore on so-called shock-tolerant patients (6 cases) and on healthy children (15 cases) - that the total XO activity can increase extremely in severe acute clinical states but a considerable decrease can be detected during reparation while in shock-tolerant states it can become expressively low. The investigations explain properly the favourable XO inhibiting effect of allopurinol demonstrated in states of experimental and clinical shock. The low XO activity observed in shock-tolerant conditions may be the result of intrinsic compensatory mechanisms.

Renal function correlates of postnatal diuresis in preterm infants.

A characteristic pattern of fluid homeostasis occurs in the first week of life in many preterm infants. Initially, urine output is low independent of fluid intake, subsequently a diuresis occurs, and finally urine output begins to vary with intake. Renal clearance measurements were made during each of these three phases to elucidate the renal mechanisms involved. Periods during which the ratio of urine output to fluid intake was greater than or equal to 1 and urine output was greater than or equal to 3 mL/kg/h were defined as diuretic. Of 22 preterm infants studied from 12 to 120 hours of age, 17 had at least one period of diuresis. In these infants, urine output, fluid intake rate, output to intake ratio, glomerular filtration rate, and fractional sodium excretion were lowest at 12 to 24 hours of age. During diuresis, urine output tripled without a significant change in fluid intake so that output to intake increased to levels exceeding unity. Diuresis was associated with significant increases in glomerular filtration rate and fractional sodium excretion. By 108 to 120 hours of age, urine output decreased despite an increase in fluid intake. This was accompanied by a decrease in glomerular filtration rate. These results suggest that the initial antidiuretic phase is the result of a low fractional sodium excretion in the face of a low glomerular filtration rate. Subsequently, diuresis and natriuresis occur as a result of abrupt, nonmaturational increases in glomerular filtration rate and fractional sodium excretion. With cessation of diuresis, glomerular filtration rate and fractional sodium excretion decrease and water and electrolyte output begin to vary appropriately with intake.