Melania Puddu

Metabolomics in newborns with intrauterine growth retardation (IUGR): urine reveals markers of metabolic syndrome

To date, we have little knowledge on the overall metabolic status of neonates with intrauterine growth retardation (IUGR). In the last few years, the analysis of metabolomics has assumed an important clinical role in identifying “disorders” in the metabolic profile of patients. The aim of this work has been to analyze the urine metabolic profiles of neonates with IUGR and compare them with controls to define the metabolic patterns associated with this pathology. To our knowledge, this is the first study of metabolomics performed on neonates with IUGR. Recruited for the study were 26 neonates with IUGR diagnosed in the neonatal period and with weight at birth below the 10th percentile and 30 neonates of proper gestational weight at birth (controls). In the first 24 hours (prior to feeding) (T1) and about 4 days after birth (T2), a urine sample was taken non-invasively from each neonate. The samples were then frozen at −80°C up to the time of the analysis by proton nuclear magnetic resonance spectroscopy (1H-NMR). The data contained in the NMR spectra obtained from the single samples were statistically analyzed using the Principal Components Analysis and the Partial Least Squares-Discriminate Analysis. By means of a multivariate analysis of the NMR spectra obtained, it was possible to highlight the differences between the two groups (IUGRs and controls) owing to the presence of different metabolic patterns. The discriminants in the urine metabolic profiles derived essentially from significant differences in certain metabolites such as: myo-inositol, sarcosine, creatine and creatinine. The metabolomic analysis showed different urine metabolic profiles between neonates with IUGR and controls and made it possible to identify the molecules responsible for such differences.

Marked interindividual variability in renal maturation of preterm infants: lessons from autopsy

The kidney of low birthweight preterm infants is characterized by a reduced number of mature nephrons at birth. The aim of the present study was to determine whether, in preterms, active glomerulogenesis occurs in the postnatal period and whether it may compensate the reduced number of nephrons developed during the intrauterine life. Kidney samples were obtained at autopsy from 8 human fetuses, 12 premature infants, and 3 term newborns. Glomerulogenesis, as measured by radial glomerular count (RGC), was markedly decreased in all preterm infants as compared with term newborns. A marked interindividual variability was detected in the level of glomerulogenesis, which, in the vast majority of cases, did neither correlate with the gestational age at birth nor with birthweight. Active glomerulogenesis, as demonstrated by the presence of S-shaped bodies in the subcapsular region, was present in all preterm infants in the perinatal period, but it ceased in a preterm surviving for 3 months. Our data show that active glomerulogenesis continues even after birth for a short period, although it is not able to compensate a marked oligonephronia at birth. As a consequence, the incomplete nephrogenesis typical of all extremely low birthweight preterm infants possibly results in a persistent oligonephronia which should likelihood represent a major risk factors of progressive renal disease in adulthood.

The Kidney from Prenatal to Adult Life: Perinatal Programming and Reduction of Number of Nephrons during Development

Modified embryonic-fetal development resulting in low birth weight may lead to a reduced nephron endowment, hypertension and renal diseases in adulthood. Regarding the involvement of genetic factors, several environmental conditions may also contribute towards reducing the number of nephrons in the fetus and infant, subsequently constituting a health burden in later life. To date no methods of investigation for the early detection of a reduced nephron reserve are available. However, more structured studies should be implemented to investigate the role of angiotensin-converting enzyme inhibitors in managing proteinurias and glomerulosclerosis in children with renal conditions characterized by reduce nephron number and glomerular hypertrophic changes. In view of the current lack of specific methods of investigation and management, close monitoring of children and young adults at risk of reduced renal reserve should be carried out to enhance the early detection of potential changes in renal function.

Clinical metabolomics and urinary NGAL for the early prediction of chronic kidney disease in healthy adults born ELBW

Background: Clinical metabolomics is a recent “omic” technology which is defined as a global holistic overview of the personal metabolic status (fingerprinting). This technique allows to prove metabolic differences in different groups of people with the opportunity to explore interactions such as genotype-phenotype and genotype-environment type, whether normal or pathological. Aim: To study chronic kidney injury 1) using urine metabolomic profiles of young adults born extremely low-birth weight (ELBW) and 2) correlating a biomarker of kidney injury, urinary neutrophil gelatinase-associated lipocalin (NGAL), in order to confirm the metabolomic injury profile. Method: Urine samples were collected from a group of 18 people (mean: 24-year-old, std: 4.27) who were born with ELBW and a group of 13 who were born at term appropriate for gestational age (AGA) as control (mean 25-year-old, std: 5.15). Urine samples were analyzed by 1H-nuclear magnetic resonance spectroscopy, and then submitted to unsupervised and supervised multivariate analysis. Urine NGAL (uNGAL) was measured using ARCHITECT (ABBOTT diagnostic NGAL kit). Results: With a multivariate approach and using a supervised analysis method, PLS-DA, (partial least squares discriminant analysis) we could correlate ELBW metabolic profiles with uNGAL concentration. Conversely, uNGAL could not be correlated to AGA. Conclusions: This study demonstrates the relevance of the metabolomic technique as a predictive tool of the metabolic status of exELBW. This was confirmed by the use of uNGAL as a biomarker which may predict a subclinical pathological process in the kidney such as chronic kidney disease.

Soluble CD14 subtype (sCD14-ST) presepsin in critically ill preterm newborns: preliminary reference ranges

Soluble CD14 subtype (sCD14-ST), also named presepsin, is a 13 kDa truncated form of soluble CD14 (sCD14), consisting of 64 amino acid residues. Systemic inflammation and sepsis are characterized by an early, significant increase in sCD14-ST presepsin blood concentration and thus, this small polypeptide has been proposed as a novel, reliable biomarker for the management of sepsis. We enrolled twenty-six consecutive non-septic preterm newborns with gestational age (GA) between 26 and 36 weeks) admitted to NICU after the first day of life for various severe diseases. sCD14-ST presepsin was measure on whole blood samples by a rapid commercial available chemiluminescent enzyme immunoassay (CLEIA) based on a non-competitive CLEIA. The mean sCD14-ST presepsin blood level in 26 preterm newborns was 643.1 ng/L, with a standard deviation (SD) of 303.8 ng/L; the median value was 578 ng/L. Our results clearly suggest no correlation between GA and sCD14-ST presepsin blood level between 26 and 36 weeks and thus it is reasonable to adopt a unique reference range for preterm newborns.

Neonatal onset of nephrogenic syndrome of inappropriate antidiuresis

This paper describes the manifestaton in a child of a new syndrome characterized by unusual, severe, persistent hyponatremia associated with hyposmolarity, euvolemia, inappropriately concentrated urine and elevated natriuresis. This is the fourth case of this syndrome reported to date, and the first to be reported in a neonate. The clinical features resemble those typically observed in patients with inappropriate antidiuretic hormone secretion, although high arginine vasopressin (AVP) levels are lacking. The findings led the authors to hypothesise a nephrogenic syndrome of inappropriate antidiuresis (NSIAD). The previously described R137C gain-of-function mutation was detected by means of mutation analysis of the V2R gene. Our results indicate that NSIAD is already present during the neonatal period and that molecular analysis of the V2R receptor should therefore be carried out, in all newborns with prolonged euvolemic hyponatremia with hypo-osmolarity, high urinary sodium and normal/low or undetectable AVP levels.

Reduced brachial flow-mediated vasodilation in young adult ex extremely low birth weight preterm: a condition predictive of increased cardiovascular risk?

Background. Sporadic data present in literature report how preterm birth and low birth weight constitute the risk factors for the development of cardiovascular diseases in later life. Aim. To assess the presence of potential alterations to endothelial function in young adults born preterm at extremely low birth weight (<1000 g; ex ELBW). Method. Thirty-two ex-ELBW subjects (10 males [M] and 22 females [F], aged 17–28 years, mean [±DS] 20.1 ± 2.5 years) were compared with 32 healthy, age-matched subjects born at term (C, 9 M and 23 F). Exclusion criteria: 1) pathological conditions known to affect endothelial function; 2) administration of drugs known to affect endothelial function. Endothelial function was assessed by non-invasive finger plethysmography, previously validated by the US Food and Drug Administration (Endopath; Itamar Medical Ltd., Cesarea, Israel). Results. Endothelial function was significantly reduced in ex-ELBW subjects compared to C (1.94 ± 0.37 vs 2.68 ± 0.41, p < 0.0001). Moreover, this function correlated significantly with gestational age (r = 0.56, p < 0.0009) and birth weight (r = 0.63, p < 0.0001). Conclusions. The results obtained reveal a significant decrease in endothelial function of ex-ELBW subjects compared to controls, underlining a probable correlation with preterm birth and low birth weight. Taken together, these results suggest that an ELBW may underlie the onset of early circulatory dysfunction predictive of increased cardiovascular risk.

Could ADMA levels in young adults born preterm predict an early endothelial dysfunction

BACKGROUND Sporadic data present in literature report how preterm birth and low birth weight are risk factors for the development of cardiovascular diseases in later life. High levels of asymmetric dimethylarginine (ADMA), a strong inhibitor of nitric oxide synthesis, are associated with the future development of adverse cardiovascular events and cardiac death. AIMS 1) to verify the presence of a statistically significant difference between ADMA levels in young adults born preterm at extremely low birth weight (<1000 g; ex-ELBW) and those of a control group of healthy adults born at term (C) and 2) to seek correlations between ADMA levels in ex-ELBW and anthropometric and clinical parameters (gender, chronological age, gestational age, birth weight, and duration of stay in Neonatal Intensive Care Unit). METHODS Thirty-two ex-ELBW subjects (11 males [M] and 21 females [F], aged 17-29years, mean age 22.2 ± 2.3 years) were compared with 25 C (7 M and 18F). ADMA levels were assessed by high-performance liquid chromatography with highly sensitive laser fluorescent detection. RESULTS ADMA levels were reduced in ex-ELBW subjects compared to C (0.606+0.095 vs 0.562+0.101 μmol/L, p<0.05), and significantly correlated inversely with gestational age (r=-0.61, p<0.00001) and birth weight (r=-0.57, p<0.0002). CONCLUSIONS Our findings reveal a significant decrease in ADMA levels of ex-ELBW subjects compared to C, underlining a probable correlation with preterm birth and low birth weight. Taken together, these results may underlie the onset of early circulatory dysfunction predictive of increased cardiovascular risk.

Significant QT interval prolongation and long QT in young adult ex-preterm newborns with extremely low birth weight

Background. The survival rate for extremely low birth weight (ELBW) infants born preterm is on an increasing upward trend, despite the possibility of neuro-cerebral consequences in later life. To date, scarce information is available on the effect of extreme prematurity on cardiovascular system. Aim. To verify the presence of standard echocardiographic and ECG alterations in ex-ELBW young healthy adults. Method. A color Doppler echocardiogram and an ECG were performed on 24 ex-ELBW (4 males and 20 females; mean: 23.2 ± 3.3 years), compared with 24 healthy subjects born at term (C). ECG parameters examined: PR, QT, QTc, and QT dispersion (QTd). Gestational age, birth weight, and duration of stay in neonatal intensive care unit were obtained from clinical records. Results. Transthoracic echocardiography did not reveal differences between ex-ELBW and C, while a significant difference was displayed by ex-ELBW with regard to PR (141.5 ± 13.4 ms vs. 164.2 ± 24.0 ms, p < 0.0003), QTc (417.0 ± 23.6 ms vs. 369.9 ± 19.5 ms, p = 0.00001), and QTd (30.4 ± 14.1 ms vs. 24.6 ± 8.2 ms, p < 0.00001). In two patients (8.3%), QTc exceeded the upper limit of normal range. A statistically significant inverse correlation was observed between QTc and gestational age (r = −0.67, p < 0.0003). Conclusions. QTc and QTd in ex-ELBW were found to be at the upper limit of normal range and correlated with gestational age and birth weight; in two cases, QTc exceeded the upper limit. This study, irrespective of the pathophysiological mechanism involved, underlines a potential risk for ex-ELBW of developing ventricular arrhythmias when using drugs capable of prolonging QT interval. Summary. QTc and QTd in young adults previously born preterm with an ELBW (401–1000 g) were generally found to be at the upper limit of normal range and correlated with gestational age and birth weight. This finding underlines a potential risk for ex-ELBW of developing ventricular arrhythmias when using drugs capable of prolonging QT interval.

Metabolomics and fetal-neonatal nutrition: between "not enough" and "too much".

Metabolomics is a new analytical technique defined as the study of the complex system of metabolites that is capable of describing the biochemical phenotype of a biological system. In recent years the literature has shown an increasing interest in paediatric obesity and the onset of diabetes and the metabolic syndrome in adulthood. Some studies show that fetal malnutrition, both excessive and insufficient, may permanently alter the metabolic processes of the fetus and increase the risk of future chronic pathologies. At present then, attention is being focused mainly on the formulation of new hypotheses, by means of metabolomics, concerning the biological mechanisms to departure from fetal-neonatal life that may predispose to the development of these diseases.