A study of plasma free amino acid levels. II. Normal values for children and adults

Armstrong, Marvin D.; Stave, Uwe

doi:10.1016/0026-0495(73)90069-3

Cited by 173 publications

(72 citation statements)

References 7 publications

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“…Tyrosine in serum increased after 48 h of VIL treatment, but CSF tyrosine was not significantly altered. Tyrosine concentration was unaffected by 4 wk of VIL treatment. Mean serum phenylalanine concentrations were about 23% lower after administration of VIL whereas mean CSF levels were decreased by 40%.…”

Section: Resultsmentioning

confidence: 93%

Reduction of Cerebrospinal Fluid Phenylalanine after Oral Administration of Valine, Isoleucine, and Leucine

et al. 1982

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SummaryA supplement of the branched chain amino acids, valine, isoleucine, and leucine (VIL) was administered orally to patients with phenylketonuria, either together with unrestricted diet of natural protein or with a low phenylalanine diet. The VIL supplement brought about a significant reduction of the cerebrospinal fluidserum ratio of phenylalanine from a mean value of 0.254 without VIL to 0.204 with VIL. The reduction varied from 15-40% (mean 21%). Concentrations of glycine, lysine, methionine, threonine, tryptophan, and tyrosine were within normal limits in serum and cerebrospinal fluid of infants with phenylketonuria. No amino acid imbalance was created by the supplement and no adverse effects from VIL were observed. SpeculationThe branched chain amino acids and phenylalanine share a common transport system. High levels of phenylalanine in brain of children with phenylketonuria may be reduced by administration of a supplement of valine, isoleucine and leucine (VIL). Supplementation of the low-phenylalanine diet with VIL during the first 2 years of life may add a measure of protection to the developing brain beyond that which can be achieved by diet alone. In older children, VIL supplementation may permit liberalization of the diet without unfavorable behavioral consequences.Treatment for phenylketonuria (PKU) by means of a lowphenylalanine diet has become common practice since its first use in affected newborn infants (3). The treatment partially corrects the abnormal amino acid pattern, including the high concentration of phenylalanine and its metabolites, and allows relatively normal intellectual and physical development if the treatment is begun early enough (10). Initially it was assumed that treatment would be terminated when major phases of brain growth were completed. Evidence has accumulated which suggests that termination of treatment for the patient with classic PKU, at least during the school years, is unwise (13,15,16) and it may be prudent to continue the diet into adult years for women with PKU in order to avoid the teratogenic effects of phenylalanine (6).An animal model developed in this laboratory was used to demonstrate the effects of experimental hyperphenylalaninemia (PKU) (12). Methods to inhibit the deleterious effects of phenylalanine on the central nervous system were studied in the model. Administration of branched chain amino acids, valine, isoleucine, and leucine (VIL), to pregnant rats with experimentally induced PKU prevented the decrease in fetal brain weight characteristic of PKU animals (7). A striking finding was that phenylalanine levels in brain of PKU fetuses whose mothers received VIL supplement were lower than in PKU fetuses not exposed to VIL, although fetal blood phenylalanine levels were similar. Subsequent studies suggested that isoleucine was more effective than other amino acids in exerting a beneficial effect on fetal rat brain growth (1 1).Human trials followed. VIL was first used as a supplement to the low-phenylalanine diet of several older PKU children in w...

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Section: Resultsmentioning

confidence: 93%

Reduction of Cerebrospinal Fluid Phenylalanine after Oral Administration of Valine, Isoleucine, and Leucine

et al. 1982

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“…Quality assurance and validation testing were undertaken during transition between machines, using Sigma Aldrich standards and complying with external quality control programmes, as required for laboratory accreditation. Due to the fact that normal values of each amino acid vary with age, correlations were performed in two age groups of less than 6 and greater than 6 years, as per the two age-related normal ranges of our laboratory, which are based on Armstrong and Stave (1973) and Applegarth et al (1979). There were only four samples from infants <3 months old (three neonates) and their results were incorporated within the <6-year-old group of patients.…”

Section: Methodsmentioning

confidence: 99%

Amino Acid Profiles in Patients with Urea Cycle Disorders at Admission to Hospital due to Metabolic Decompensation

Rodney

Boneh

2012

JIMD Reports

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Urea cycle disorders (UCDs) result from inherited defects in the ammonia detoxification pathway, leading to episodes of hyperammonaemia and encephalopathy. The purpose of this study was to answer the question, "what is the likely plasma amino acid profile of a patient known to have a UCD presenting with hyperammonaemia during acute metabolic decompensation", in order to support informed decisions regarding management.We analysed the results of plasma ammonia levels and amino acid profiles taken simultaneously or within 30 min of each other during acute admissions of all patients with a UCD at the Royal Children's Hospital, Melbourne, over 28 years. Samples from 96 admissions (79, 9 and 8 admissions for OTC, CPS and ASS deficiencies, respectively) from 14 patients fulfilled these criteria. Amino acid levels were measured by ion exchange chromatography with post-column ninhydrin derivatisation and interpreted in relation to age-related reference ranges.Plasma concentrations of all measured essential amino acids were low or low-normal in almost all samples. There was a strong positive correlation between low plasma branched-chain amino acids and other essential amino acids, and a negative correlation between ammonia and phenylalanine to tyrosine (Phe:Tyr) ratio in patients with OTC deficiency, and between glutamine and Phe:Tyr ratio in all patients, indicating protein deficiency.Conclusion: At admission, protein deficiency is common in patients with a UCD with hyperammonaemia. These results challenge the current guideline of stopping protein intake during acute decompensation in UCDs. Supplementation with essential amino acids (particularly branched-chain amino acids) at these times should be considered.

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“…However, a new generation of instruments that employ very sensitive high-resolution mass spectrometry (HRMS) methods, including proton-transfer-reaction TOF (21 ) MS or secondary electrospray ionization (SESI)-Orbitrap MS, (22)(23)(24) now reach limits of detection in the low partsper-trillion by volume (pptv) range (25 ), which enables the detection of only partially volatile compounds. This applies to several PFAAs whose reference interval plasma concentrations are in the range of 10 -1000 mol/L (25)(26)(27) and whose Henry's law constants for aqueous solutions are as high as 10 5 -10 6 mol ⅐ m Ϫ3 ⅐ Pa Ϫ1 (28 ), which results in expected breath concentrations of only around 1-10 pptv.…”

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confidence: 99%

Real-Time Quantification of Amino Acids in the Exhalome by Secondary Electrospray Ionization–Mass Spectrometry: A Proof-of-Principle Study

et al. 2016

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BACKGROUND:Amino acids are frequently determined in clinical chemistry. However, current analysis methods are time-consuming, invasive, and suffer from artifacts during sampling, sample handling, and sample preparation. We hypothesized in this proof-of-principle study that plasma concentrations of amino acids can be estimated by measuring their concentrations in exhaled breath. A novel breath analysis technique described here allows such measurements to be carried out in real-time and noninvasively, which should facilitate efficient diagnostics and give insights into human physiology.

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A study of plasma free amino acid levels. II. Normal values for children and adults

Cited by 173 publications

References 7 publications

Reduction of Cerebrospinal Fluid Phenylalanine after Oral Administration of Valine, Isoleucine, and Leucine

Reduction of Cerebrospinal Fluid Phenylalanine after Oral Administration of Valine, Isoleucine, and Leucine

Amino Acid Profiles in Patients with Urea Cycle Disorders at Admission to Hospital due to Metabolic Decompensation

Real-Time Quantification of Amino Acids in the Exhalome by Secondary Electrospray Ionization–Mass Spectrometry: A Proof-of-Principle Study

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