Amino Acid and Acylcarnitine Profiles in Premature Neonates: A Pilot Study

Mandour, Iman; Gayar, Dina El; Amin, Maha M; Farid, T.; Ali, Aliaa Adel

doi:10.1007/s12098-013-0980-4

Cited by 20 publications

(18 citation statements)

References 21 publications

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“…Unlike Meyburg and Mandour (15,16), we found lower concentrations of almost all ACs in preterm than in term-born infants, except for the isomeric form deriving from BCAA catabolism. This finding could relate to low lipid levels at birth, and particularly to limited amounts of lipids in preterm newborn, as suggested by previous studies (19,20).…”

Section: Fatty Acid-derived Acylcarnitinescontrasting

confidence: 93%

“…The AC profiles of plasma samples differed slightly from those found in DBS, especially as regards the long-chain ACs. The levels of C 14 and C 16 were lower in plasma than in DBS. The differences related to the contribution of long-chain ACs of the erythrocyte membranes (8).…”

Section: Figurementioning

confidence: 75%

“…When the data were divided by GA group, most of the analytes differed significantly (with the exception of C 3 , C 4 , C 16:1 OH, Figure 1 Box and whisker plots of characteristic short-, medium-, and long-chain acylcarnitines (ACs) in dried blood spots (DBS): (a) free carnitine, (b) C 2 , (c) 2-methylbutyril, (d) C 6 , (e) C 8 , (f) C 10 , (g) C 12 , (h) C 14 , and (i) C 16 . The values are stratified by gestational age (GA) group, from G1 to G4.…”

Section: Acylcarnitine Profiles In Dbsmentioning

confidence: 99%

“…Meyburg compared AC cord blood levels in preterm and full-term infants, correlating them with BW (14), and investigated AC levels longitudinally in DBS of preterm newborn during the first 4 wk of life (15). Another study was recently conducted on amino acids and AC profiles in DBS from preterm newborn (16).…”

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confidence: 99%

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Analysis and interpretation of acylcarnitine profiles in dried blood spot and plasma of preterm and full-term newborns

et al. 2014

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Background: Acylcarnitines are biomarkers of fatty acid metabolism, and examining their patterns in preterm newborn may reveal metabolic changes associated with particular conditions related to prematurity. Isomeric acylcarnitines in dried blood spots (DBS) and plasma have never been assessed in preterm infants. Methods: We studied 157 newborn divided into four groups by weeks of gestational age (GA), as follows: 22-27 wk in group 1; 28-31 wk in group 2; 32-36 wk in group 3; and 37-42 wk in group 4. Samples were collected on the third day of life. Acylcarnitines were separated and quantified using ultra-performance liquid chromatography tandem mass spectrometry. results: Acylcarnitine concentrations correlated significantly with GA and birth weight in both DBS and plasma samples. Concentrations were lower in preterm newborn, except for acylcarnitines derived from branched-chain amino acids, which were higher and correlated with enteral feeding. On day 3 of life, no correlations emerged with gender, respiratory distress syndrome, bronchopulmonary dysplasia, surfactant administration, or mechanical ventilation. conclusion: We established GA-based reference ranges for isomeric acylcarnitine concentrations in preterm newborn, which could be used to assess nutritional status and the putative neuroprotective role of acylcarnitines.F atty acid metabolism takes place in the mitochondria, and β-oxidation is the main process by which fatty acids are oxidized by means of a sequential removal of two-carbon units from the acyl chain. Fatty acids are activated primarily in the cytosol by fatty acyl-CoA synthase to carnitine derivatives, then they are carried by specific acylcarnitine (AC) transferases and translocases into the mitochondrial matrix where β-oxidation can begin. In successive cycles of reactions, this process generates a series of ACs that are one two-carbon unit shorter and it continues until only two or three carbons are left (forming acetyl-CoA or propionyl-CoA, respectively). AC detection is of great interest for the purpose of assessing the carnitine pool, which is essential to the diagnosis of several metabolic disorders. AC profiling is a powerful tool for the neonatal screening and diagnosis of fatty acid oxidation and organic acid disorders (1). Alongside the importance of AC in tissues such as heart and muscle, recent data indicate an involvement of these compounds in neurological protection and disorders. ACs are believed to have both energy-providing and neuroprotective roles in the brain (2,3), based on the assumption that the fatty acid oxidation pathway is active in neurons, given the localization of carnitine palmitoyltransferase enzyme 1 (CPT1) (2,4). Investigating AC profiles in preterm infants may therefore reveal metabolic changes associated with perinatal brain injury.Mass spectrometry (MS) is commonly used to quantify ACs. Millington and co-workers pioneered tandem mass spectrometry (MS/MS) methods for assaying carnitine and ACs in urine and plasma samples (5), and in dried blood spots (DBS...

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Section: Fatty Acid-derived Acylcarnitinescontrasting

confidence: 93%

Section: Figurementioning

confidence: 75%

Section: Acylcarnitine Profiles In Dbsmentioning

confidence: 99%

mentioning

confidence: 99%

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Analysis and interpretation of acylcarnitine profiles in dried blood spot and plasma of preterm and full-term newborns

et al. 2014

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“…Interestingly, an investigation by Mandouret. et al already showed the longitudinal changes in AA and acylcarnitine profiles of preterm neonates over the first two weeks of life, indicating an age-related distribution of their concentrations, and pointing out the importance of using appropriate reference values when working with a prematurely born population [19].Thus, special protocols, which provide repeated tests for premature babies, for small-for-gestation-age babies, for term/preterm babies on TPN, and for infants after transfusion in the postnatal period, are required in order to reduce false-positive results and the additional confirmatory testing when not really necessary, but also to avoid false-negative results. As the best strategy to monitor the metabolic status of term/preterm babies on TPN, it is recommended to collect the first sample before TPN procedure, a second sample between 48 and 72 h of life, and the last sample at 72 h after the ending of parental nutrition [3].…”

Section: Discussionmentioning

confidence: 99%

A Case of Suspected Hyperphenylalaninemia at Newborn Screening by Tandem Mass Spectrometry during Total Parenteral Nutrition

et al. 2020

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Phenylketonuria (PKU) is a rare autosomal recessive condition affecting about 1 in 10,000 people in the Europe, with a higher rate in some countries, like Ireland and Italy. In Italy, newborn screening (NBS) by MS/MS allows the diagnostic suspicion of PKU and its variants (Hyperphenylalaninemia (HPA), Tetrahydrobiopterin (BH4) synthesis deficiency, and Tetrahydrobiopterin (BH4) recycling deficiency) through the quantification of Phenylalanine (Phe) and the Phenylalanine/Tyrosine (Phe/Tyr) ratio in dried blood Spot (DBS) samples. Here, we report a case of an HPA whose suspicion was possible with expanded NBS, even if the normal-weight newborn was in total parenteral nutrition (TPN). It is known that TPN may present metabolic alterations, mainly for amino acids at NBS in MS/MS, frequently causing false positives. Actually, TPN is considered a special protocol in NBS, requiring several sample collections. In particular, a DBS sample is required before TPN, at basal time point (48 h after birth) and 72 h after the end of the procedure. In the case we report, even if the first DBS sample (before TPN) resulted negative, the repeated NBS tests revealed increased levels of Phe and dramatically high Phe/Tyr ratio. Thus, the newborn was recalled, and the NBS test was repeated several times before that HPA suspicion was confirmed by other specific biochemical tests. This case highlights the importance of Phe/Tyr ratio, only detectable by MS/MS analysis, in supporting the diagnostic suspicion during amino acids administration in the neonatal period.

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Neonatal carnitine concentrations in relation to gestational age and weight

et al. 2020

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Background Free carnitine has been measured in the Dutch newborn screening (NBS) program since 2007 with a referral threshold of ≤5 μmol/L, regardless of gestational age or birthweight. However, several studies suggest that carnitine concentrations may depend on gestational age and birthweight. We evaluated differences in postnatal day‐to‐day carnitine concentrations in newborns based on gestational age (GA) and/or weight for GA (WfGA). Methods A retrospective study was performed using data from the Dutch NBS. Dried blood spot (DBS) carnitine concentrations, collected between the 3rd and 10th day of life, of nearly 2 million newborns were included. Individuals were grouped based on GA and WfGA. Median carnitine concentrations were calculated for each group. Mann‐Whitney U tests, and chi‐square tests were applied to test for significant differences between groups. Results Preterm, postterm, and small for GA (SGA) newborns have higher carnitine concentrations at the third day of life compared to term newborns. The median carnitine concentration of preterm newborns declines from day 3 onwards, and approximates that of term newborns at the sixth day of life, while median concentrations of postterm and SGA newborns remain elevated at least throughout the first 10 days of life. Carnitine concentrations ≤5 μmol/L were found less frequently in SGA newborns and newborns born between 32 and 37 weeks of gestation, compared to term newborns. Conclusions Median carnitine concentrations in NBS DBS vary with day of sampling, GA, and WfGA. It is important to take these variables into account when interpreting NBS results..

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Amino Acid and Acylcarnitine Profiles in Premature Neonates: A Pilot Study

Abstract: AA and AC showed an age-related distribution of their concentrations. This underlines the importance of using appropriate reference values when working with a prematurely born population.

Cited by 20 publications

References 21 publications

Analysis and interpretation of acylcarnitine profiles in dried blood spot and plasma of preterm and full-term newborns

Analysis and interpretation of acylcarnitine profiles in dried blood spot and plasma of preterm and full-term newborns

A Case of Suspected Hyperphenylalaninemia at Newborn Screening by Tandem Mass Spectrometry during Total Parenteral Nutrition

Neonatal carnitine concentrations in relation to gestational age and weight

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