scholarly journals Benchmark examination of blood amino acids patterns in phenylketonuric neonates and young children on phenylalanine-restricted dietary treatment

2020 ◽  
Author(s):  
Zhihui Wan ◽  
Eric Rosenbaum ◽  
Wei Liu ◽  
Boyan Song ◽  
Xiaofei Yue ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Young Children ◽  
Dietary Intervention ◽  
Dietary Treatment ◽  
Dried Blood Spots ◽  
Complete Restoration ◽  
Liquid Chromatography Tandem Mass ◽  
Amino Acid Homeostasis ◽  
Clinically Significant

Abstract Background Phe-restricted diets have been the basis of therapy for phenylketonurics; however, little is known how this treatment effects homeostasis of other important amino acids. This study aimed to describe blood amino acid patterns in neonates with phenylketonuria (PKU) and identify any effects of Phe restriction on these patterns in young children.Methods Neonate group (age 0-4 weeks): 45 PKU patients, 45 age-/sex-matched controls without PKU; 1-4 year-old group: 27 diet-treated PKU patients, 27 age-/sex-matched children without PKU. Concentrations of 11 amino acids were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) performed on dried blood spots.Results Elevated blood phenylalanine (Phe), arginine (Arg), citrulline (Cit), valine (Val) and methionine (Met) concentrations were observed in PKU neonates relative to controls (Phe, Arg, Cit, Val: P < 0.001; Met: P < 0.05), of which Phe, Arg, and Met levels could be either partially or completely restored with dietary intervention. Diet had no effect on elevated Cit and Val. Decreased blood tyrosine (Tyr) and proline (Pro) concentrations were observed in PKU neonates compared to controls (P < 0.001). Both amino acids could be near completely restored to normal with dietary treatment. No significant differences in alanine (Ala), leucine (Leu), ornithine (Orn) and glycine (Gly) concentrations were found in the PKU neonates and 1-4 year-old groups (P > 0.05).Conclusions Blood amino acid homeostasis is disrupted in neonates and young children with PKU. Although dietary intervention adjusts amino acid homeostasis in the direction of a healthy equilibrium, complete restoration is not achieved. This persistent disruption may represent a clinically significant barrier to achieving the best possible therapy for those with PKU. Use of laboratory technologies such as LC-MS/MS enable characterization of persistent blood amino acid disequilibrium in the treated phenylketonuric. Testing of this kind presents opportunity for customized treatment feedback that may allow even greater optimization of therapy for neonates and children with PKU.

scholarly journals Benchmark examination of blood amino acids patterns in phenylketonuric neonates and young children on phenylalanine-restricted dietary treatment

2020 ◽  
Author(s):  
Zhihui Wan ◽  
Eric Rosenbaum ◽  
Wei Liu ◽  
Boyan Song ◽  
Xiaofei Yue ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Young Children ◽  
Dietary Intervention ◽  
Dietary Treatment ◽  
Dried Blood Spots ◽  
Complete Restoration ◽  
Liquid Chromatography Tandem Mass ◽  
Amino Acid Homeostasis ◽  
Clinically Significant

Abstract Background Phe-restricted diets have been the basis of therapy for phenylketonurics; however, little is known how this treatment effects homeostasis of other important amino acids. This study aimed to describe blood amino acid patterns in neonates with phenylketonuria (PKU) and identify any effects of Phe restriction on these patterns in young children. Methods Neonate group (age 0–4 weeks): 45 PKU patients, 45 age-/sex-matched controls without PKU; 1–4 year-old group: 27 diet-treated PKU patients, 27 age-/sex-matched children without PKU. Concentrations of 11 amino acids were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) performed on dried blood spots. Results Elevated blood phenylalanine (Phe), arginine (Arg), citrulline (Cit), valine (Val) and methionine (Met) concentrations were observed in PKU neonates relative to controls (Phe, Arg, Cit, Val: P < 0.001; Met: P < 0.05), of which Phe, Arg, and Met levels could be either partially or completely restored with dietary intervention. Diet had no effect on elevated Cit and Val. Decreased blood tyrosine (Tyr) and proline (Pro) concentrations were observed in PKU neonates compared to controls (P < 0.001). Both amino acids could be near completely restored to normal with dietary treatment. No significant differences in alanine (Ala), leucine (Leu), ornithine (Orn) and glycine (Gly) concentrations were found in the PKU neonates and 1–4 year-old groups (P > 0.05). Conclusions Blood amino acid homeostasis is disrupted in neonates and young children with PKU. Although dietary intervention adjusts amino acid homeostasis in the direction of a healthy equilibrium, complete restoration is not achieved. This persistent disruption may represent a clinically significant barrier to achieving the best possible therapy for those with PKU. Use of laboratory technologies such as LC-MS/MS enable characterization of persistent blood amino acid disequilibrium in the treated phenylketonuric. Testing of this kind presents opportunity for customized treatment feedback that may allow even greater optimization of therapy for neonates and children with PKU.

scholarly journals Liver intracellular L-cysteine concentration is maintained after inhibition of the trans-sulfuration pathway by propargylglycine in rats

1997 ◽  
Vol 78 (5) ◽  
pp. 823-831 ◽  
Author(s):  
Ana Triguero ◽  
Teresa Barber ◽  
Concha GarcÍa ◽  
Inmaculada R. Puertes ◽  
Juan Sastre ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Degradation ◽  
Histological Examination ◽  
Blood Concentration ◽  
Urea Cycle ◽  
Blood Levels ◽  
Liver And Kidney ◽  
Amino Acid Homeostasis ◽  
Stimulation Of

To study the fate of l-cysteine and amino acid homeostasis in liver after the inhibition of the trans-sulfuration pathway, rats were treated with propargylglycine (PPG). At 4 h after the administration of PPG, liver cystathionase (EC 4.4.1.1) activity was undetectable, l-cystathionine levels were significantly higher, l-cysteine was unchanged and GSH concentration was significantly lower than values found in livers from control rats injected intraperitoneally with 0.15 M-NaCl. The hepatic levels of amino acids that are intermediates of the urea cycle, l-ornithine, l-citrulline and l-arginine and blood urea were significantly greater. Urea excretion was also higher in PPG-treated rats when compared with control rats. These data suggest a stimulation of ureagenesis in PPG-treated rats. The inhibition of γ-cystathionase was reflected in the blood levels of amino acids, because the L-methionine: l-cyst(e)ine ratio was significantly higher in PPG-treated rats than in control rats; blood concentration of cystathionine was also greater. Histological examination of liver and kidney showed no changes in PPG-treated rats when compared with controls. The administration of N-acetylcysteine (NAC) to PPG-treated rats reversed the changes in blood urea and in liver GSH. These data suggest that when liver l-cysteine production was impaired by the blockage of the trans-sulfuration pathway, the concentration of this amino acid was maintained mainly by an increase in protein degradation and by a depletion in GSH concentration that may spare l-cysteine.

scholarly journals Total 4EBP1 Is Elevated in Liver of Rats in Response to Low Sulfur Amino Acid Intake

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Angelos K. Sikalidis ◽  
Kevin M. Mazor ◽  
Minji Kang ◽  
Hongyun Liu ◽  
Martha H. Stipanuk
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dietary Treatment ◽  
Binding Activity ◽  
Initiation Factor ◽  
Sulfur Amino Acid ◽  
Sulfur Amino Acids ◽  
Protein Levels ◽  
Cellular Stresses

Translation initiation is known to be regulated by the binding of eukaryotic initiation factor 4E (eIF4E) by binding proteins (4EBPs), and there is evidence that amino acid deprivation and other cellular stresses upregulate 4EBP1 expression. To pursue the question of whether diets limited in an essential amino acid lead to induction of 4EBP1 expression in vivo, diets that varied in methionine and cystine content were fed to rats for 7 days, and 4EBP1 mRNA and protein levels and 4EBP1 phosphorylation state were determined. Total 4EBP1 mRNA and protein abundance increased in liver of rats with severely deficient intakes of sulfur amino acids (0.23% or 0.11% methionine without cystine) but not in animals with a less restricted intake of sulfur amino acids (0.11% methionine plus 0.35% cystine) but a similarly restricted intake of total diet (53 to 62% of control). The amount of 4EBP1 binding activity (α + β forms) was elevated in liver of rats fed sulfur amino acid-deficient diets, whereas the hyperphosphorylation of 4EBP1 was not affected by dietary treatment. Results suggest that changes in total 4EBP1 expression should be considered when examining mechanisms that attenuate protein synthesis during amino acid deficiency states.

The Gcn2–eIF2α pathway connects iron and amino acid homeostasis in Saccharomyces cerevisiae

2018 ◽  
Vol 475 (8) ◽  
pp. 1523-1534 ◽  
Author(s):  
Marcos Caballero-Molada ◽  
María D. Planes ◽  
Helena Benlloch ◽  
Sergio Atares ◽  
Miguel A. Naranjo ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Amino Acid ◽  
Iron Content ◽  
Amino Acid Biosynthesis ◽  
Initiation Factor ◽  
Acid Biosynthesis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Iron Sulfur ◽  
Amino Acid Homeostasis

In eukaryotic cells, amino acid biosynthesis is feedback-inhibited by amino acids through inhibition of the conserved protein kinase Gcn2. This decreases phosphorylation of initiation factor eIF2α, resulting in general activation of translation but inhibition of translation of mRNA for transcription factor (TF) Gcn4 in yeast or ATF4 in mammals. These TFs are positive regulators of amino acid biosynthetic genes. As several enzymes of amino acid biosynthesis contain iron–sulfur clusters (ISCs) and iron excess is toxic, iron and amino acid homeostasis should be co-ordinated. Working with the yeast Saccharomyces cerevisiae, we found that amino acid supplementation down-regulates expression of genes for iron uptake and decreases intracellular iron content. This cross-regulation requires Aft1, the major TF activated by iron scarcity, as well as Gcn2 and phosphorylatable eIF2α but not Gcn4. A mutant with constitutive activity of Gcn2 (GCN2c) shows less repression of iron transport genes by amino acids and increased nuclear localization of Aft1 in an iron-poor medium, and increases iron content in this medium. As Aft1 is activated by depletion of mitochondrial ISCs, it is plausible that the Gcn2–eIF2α pathway inhibits the formation of these complexes. Accordingly, the GCN2c mutant has strongly reduced activity of succinate dehydrogenase, an iron–sulfur mitochondrial enzyme, and is unable to grow in media with very low iron or with galactose instead of glucose, conditions where formation of ISCs is specially needed. This mechanism adjusts the uptake of iron to the needs of amino acid biosynthesis and expands the list of Gcn4-independent activities of the Gcn2–eIF2α regulatory system.

scholarly journals An investigation of amino acid and acylcarnitine levels in neonates from the Tibet Autonomous

2019 ◽  
Author(s):  
Chunyan Zhang ◽  
Drun Dha ◽  
Yuxuan Cheng ◽  
Ya Ma ◽  
Yan Meng ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dried Blood Spots ◽  
Recall Rate ◽  
Reference Intervals ◽  
Impact Factors ◽  
Autonomous Region ◽  
Tibet Autonomous Region ◽  
Statistical Screening ◽  
The Tibet Autonomous Region

Abstract Background: The purpose of the study was to establish reference values of amino acids and acylcarnitines in newborns of the Tibet Autonomous Region for the first time and to provide an experimental basis for the diagnosis of genetic metabolic diseases.Methods: We detected concentrations of 43 kinds of amino acids, acylcarnitines and succinylacetone in the dried blood spots of 15029 newborns using liquid chromatography tandem mass spectrometry. We compared the indexes between Tibet and our lab, where most data come from an inland area and Han Chinese people. Then we compared amino acid and acylcarnitine levels of seven regions in Tibet and explored their impact factors. The distribution of amino acid and acylcarnitines were different in Tibet.Results: Reference intervals of amino acids and acyl carnitines in neonates from the Tibet Autonomous Region were defined according to the (P 0.5% ~ P 99.5%) of the values. Given the third reference range, the recall rate of statistical screening was significantly reduced to 2.16%.Conclusions: This study has contributed to the field by determining the actual values of amino acids and acylcarnitines in newborns from the Tibet Autonomous Region, which could be used as reference for a newborn metabolic screening project in this area.

Validation of a rapid, comprehensive and clinically relevant amino acid profile by underivatised liquid chromatography tandem mass spectrometry

2020 ◽  
Vol 58 (5) ◽  
pp. 758-768 ◽  
Author(s):  
Rachel S. Carling ◽  
Kate John ◽  
Richard Churchus ◽  
Charles Turner ◽  
R. Neil Dalton
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Liquid Chromatography ◽  
Amino Acid ◽  
Amino Acid Profile ◽  
Ion Pair ◽  
Analysis Time ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

AbstractBackgroundQuantification of plasma amino acids is key to the diagnosis of inherited defects of amino acid synthesis, catabolism and transport, many of which present as clinical emergencies. The utility of this test is limited by the long analysis time and subsequent inability of laboratories to provide results in real-time. Traditionally, analysis has been performed by ion exchange chromatography (IEC) but recently there has been a move towards liquid chromatography tandem mass spectrometry (LC-MS/MS) which provides the potential for faster analysis. However, the necessity to derivatise the sample and/or utilise an ion-pair reagent, combined with lack of commercially available stable isotope internal standards (IS) has prevented laboratories fully exploiting the benefits of this methodology. We describe an underivatised LC-MS/MS method enabling patient results to be reported with an improved turnaround time (<1 h).MethodsMethanolic IS was added to plasma (10 μL) to precipitate protein. Following centrifugation amino acids were analysed by LC-MS/MS using selected reaction monitoring (SRM) for each analyte and corresponding IS.ResultsPatient samples (n = 57) and external quality assessment (EQA) material (n = 11) were analysed and results compared with IEC. Comparable accuracy and precision were obtained with 15-min analysis time.ConclusionsThis method enables the analysis of a clinically comprehensive amino acid profile without the need for derivatisation/ion-pair reagents and benefitting from improved analytical quantitation through multipoint calibration and use of stable isotope IS. The analysis time is fast in comparison to IEC, improves efficiency of laboratory workflow and enables stat analysis of clinically urgent samples.

scholarly journals Validation of Accuracy-based Amino Acid Reference Materials in Dried-Blood Spots by Tandem Mass Spectrometry for Newborn Screening Assays

1999 ◽  
Vol 45 (8) ◽  
pp. 1269-1277 ◽  
Author(s):  
Donald H Chace ◽  
Barbara W Adam ◽  
S Jay Smith ◽  
J Richard Alexander ◽  
Steven L Hillman ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Amino Acid ◽  
Tandem Mass Spectrometry ◽  
Newborn Screening ◽  
Dried Blood Spots ◽  
Tandem Mass ◽  
Blood Spots ◽  
Amino Acid Contents ◽  
Amino Acid Concentrations

Abstract Background: Advances in technology and the earlier release of newborns from hospitals have pressed the demand for accurate calibration and improved interlaboratory performance for newborn screening tests. As a first step toward standardization of newborn screening aminoacidopathy tests, we have produced six-pool sets of multianalyte dried-blood-spot amino acid reference materials (AARMs) containing predetermined quantities of five amino acids. We describe here the production of the AARMs, validation of their amino acid contents, and characterization of their homogeneity and their stability in storage. Methods: To each of six portions of a pool of washed erythrocytes suspended in serum we added Phe (0–200 mg/L), Leu (0–200 mg/L), Met (0–125 mg/L), Tyr (0–125 mg/L), and Val (0–125 mg/L). Six-pool sets (1300) were prepared, dried, and packaged. We used isotope-dilution mass spectrometry to estimate the endogenous amino acid concentrations of the AARMs and validate their final amino acid concentrations. We used additional tandem mass spectrometry analyses to examine the homogeneity of amino acid distribution in each AARM, and HPLC analyses to evaluate the stability of the amino acid contents of the AARMs. Results: The absolute mean biases across the analytic range for five amino acids were 2.8–9.4%. One-way ANOVAs of the homogeneity results predicted no statistically significant differences in amino acid concentrations within the blood spots or within the pools (P &gt;0.05). Regression slopes (0 ± 0.01) for amino acid concentrations vs storage times and their P values (&gt;0.05) showed no evidence of amino acid degradation at ambient temperatures, 4 °C, or −20 °C during the intervals tested. Conclusion: The validation, homogeneity, and stability of these blood spots support their use as a candidate national reference material for calibration of assays that measure amino acids in dried-blood spots.

scholarly journals LC–MS/MS Analysis of Thiol-Containing Amino Acids in Exosomal Fraction of Serum

2020 ◽  
Vol 58 (7) ◽  
pp. 636-640
Author(s):  
Mayu Onozato ◽  
Kana Kobata ◽  
Tatsuya Sakamoto ◽  
Hideaki Ichiba ◽  
Takeshi Fukushima
Keyword(s):  
Oxidative Stress ◽  
Mass Spectrometry ◽  
Amino Acids ◽  
Liquid Chromatography ◽  
Amino Acid ◽  
Human Serum ◽  
Precolumn Derivatization ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

Abstract It has been suggested that thiol-containing amino acids could be used as biomarkers for diseases associated with oxidative stress. We investigated the thiol-containing amino acids, homocysteine (Hcy), cysteine (Cys), glutathione (GSH) and γ-glutamylcysteine (γ-GluCys), in commercial human serum by using liquid chromatography–tandem mass spectrometry (LC–MS/MS) after precolumn derivatization with 4-fluoro-7-sulfobenzofurazan. This method was applied to determine the composition of thiol-containing amino acids in exosomes prepared from the serum. Hcy, Cys, GSH and γ-GluCys could be detected in the exosomal fraction, and the ratio of each thiol-containing amino acid was similar to those in the corresponding native serum. Cys (94.76%) was most enriched in the exosomal fraction, followed by GSH (2.97%), γ-GluCys (1.59%) and Hcy (0.68%). These findings suggest that thiol-containing amino acids, Hcy, Cys, GSH and γ-GluCys, are included in exosomes in human serum.

Inhibition of entry of some amino acids into the brain, with observations on mental retardation in the aminoacidurias

1974 ◽  
Vol 4 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Guadalupe Baños ◽  
P. M. Daniel ◽  
S. R. Moorhouse ◽  
O. E. Pratt
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mental Retardation ◽  
Amino Acid ◽  
Inborn Errors Of Metabolism ◽  
Dietary Treatment ◽  
Acid Transport ◽  
Inborn Errors ◽  
Partial Exclusion ◽  
The Brain

SYSNOPSISAbnormally high levels of various amino acids were maintained in the bloodstream of rats, causing saturation of amino acid transport into the brain and partial exclusion from the brain of other amino acids which are necessary for protein synthesis. Excluded amino acids could be made to enter the brain by raising their concentration in the bloodstream. The possible relevance of these findings to improvements in the dietary treatment of some inborn errors of metabolism is discussed.

Abstract P150: Weight-Loss Diets and 2-Year Change of Circulating Amino Acids in Two Randomized Intervention Trials

Circulation ◽  
2015 ◽  
Vol 131 (suppl_1) ◽  
Author(s):  
Yan Zheng ◽  
Uta Ceglarek ◽  
Tao Huang ◽  
Lerong Li ◽  
Jennifer Rood ◽  
...  
Keyword(s):  
Amino Acids ◽  
Weight Loss ◽  
Amino Acid ◽  
Weight Change ◽  
Plasma Levels ◽  
Dietary Intervention ◽  
Controlled Trial ◽  
Dietary Interventions ◽  
Amino Acid Profiles ◽  
Intervention Trials

Background: Emerging evidence has related circulating amino acids to diabetes and cardiovascular risk. Little is known about how diet modifications affect circulating amino acids. The present study aimed to examine the effects of weight-loss diets on long-term changes in plasma amino acids, and their relations with weight loss and metabolic outcomes. Methods and Results: We repeatedly measured plasma amino acid profiles over 2 years among overweight or obese participants from two randomized dietary interventional weight-loss trials: 774 from the Preventing Overweight Using Novel Dietary Strategies trial (POUNDS LOST) and 318 from Dietary Intervention Randomized Controlled Trial (DIRECT). The plasma levels of most amino acids decreased from baseline during follow-up in both trials. In the POUNDS LOST trial, compared to the high-protein diets, the average-protein weight-loss diets showed a greater effect on decreasing plasma levels of a diabetes-associated branched-chain amino acid (BCAA) valine and another amino acid methyl-histidine at 6 months, independent of weight change (p<0.002). Furthermore, the changes of plasma BCAA leucine/isoleucine, aromatic amino acid tyrosine and phenylalanine, and four other amino acids (alanine, sarcosine, hydroxyproline, and methionine) were positively related to concurrent weight loss, consistently in both trials (5-13g weight loss per 1 unit decease in log[amino acid in μmol/L], p<0.002). Moreover, the changes in tyrosine and alanine were positively related to changes in insulin resistance, independent of weight change, in both trials (p<0.05). Conclusion: Our findings underscore the potential importance of weight-loss dietary interventions in improvement of amino acid profiles and related cardiometabolic risk.

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