Corrigendum to "Optimization and validation of the Kairos Amino Acid Kit for plasma amino acid monitoring in inherited metabolic disorder patients" [Clin. Biochem. 138 (2025) 110960

Optimization and validation of the Kairos amino acid Kit for plasma amino acid monitoring in inherited metabolic disorder patients.

Associations among food and protein intake, serine dehydratase, and plasma amino acids.

Summary Temporal changes, as well as differences in distribution, in concentrations of 24 amino acids in plasma and whole blood of neonatal foals were determined from birth to 2 days of age. In addition, differences in concentrations of amino acids in plasma between mare and foal pairs were determined at birth. Significant (P < 0.05) hypoaminoacidemia existed for 15 amino acids in plasma of foals at birth, compared with mares (paired t-test). Concentrations of 7 amino acids (aspartate, glutamate, glutamine, glycine, hydroxyproline, phenylalanine, proline) in plasma of foals were higher (P < 0.05) at birth than in mares, and concentrations of 2 (taurine, tryptophan) were not different (P > 0.05). Significant (P < 0.05) temporal changes for concentrations of 19 of 24 amino acids in plasma were observed during the 48-hour period. Concentrations of 13 of the 19 amino acids in plasma that had significant changes were higher (P < 0.05) at 48 hours. Significant (P > 0.05) effect of time on concentration of 5 amino acids (alanine, methionine, phenylalanine, taurine, threonine) in plasma was not found after birth. Temporal changes in concentrations of 7 amino acids (alanine, asparagine, glutamine, histidine, hydroxyproline, methionine, and threonine) in whole blood were not significantly (P > 0.05) different from those in plasma. Temporal changes for concentrations of the remaining 17 amino acids in whole blood were significantly (P < 0.05) different, compared with plasma. Distribution of the concentrations of 18 amino acids between whole blood and plasma was significantly (P < 0.05) different. Concentrations of 5 amino acids (citrulline, cystine, glutamine, methionine, tryptophan) were significantly (P < 0.05) lower in whole blood than in plasma, whereas concentrations of 13 amino acids were significantly (P < 0.05) higher in whole blood vs plasma. Concentrations of 6 amino acids (asparagine, isoleucine, leucine, proline, serine, valine) in whole blood were not significantly different from concentrations in plasma. Significant differences in temporal patterns of concentrations of amino adds in plasma and whole blood may be attributable to nutritional or physiologic changes associated with parturition. Significant differences between concentrations of amino acids in whole blood and plasma may be attributable to ontogeny or specificity of transport systems across cell membranes.

Summary Concentrations of amino acids in plasma and whole blood in response to 10 hours of food deprivation were determined in healthy 2-day-old foals (n = 8) and were compared with control values in foals of the same age (n = 8) allowed free access to suckle. In addition, response of concentrations of amino acids in plasma to 15 minutes of free-access suckling was determined at the end of the 10-hour period in both groups. Response of 13 amino acids in plasma of food-deprived foals was significantly (P < 0.05) different, compared with that in control foals. Concentrations of 3 amino acids (alanine, glycine, and phenylalanine) in plasma increased significantly (P < 0.05), whereas concentrations of 7 amino acids (asparagine, citrulline, histidine, ornithine, proline, tryptophan, and tyrosine) in plasma decreased significantly (P < 0.05) during food deprivation. Response of concentrations of 2 amino acids (glycine and histidine) in whole blood was significantly (P < 0.05) different from that in plasma of food-deprived vs control foals. Refeeding of food-deprived foals resulted in significantly (P < 0.05) different responses for concentrations of all but 2 amino acids (cystine and taurine) in plasma, compared with responses in controls. Changes in concentrations of amino acids in plasma and whole blood of foals in response to food deprivation are similar to those in foals with septicemia and in children with grade 1 or 2 kwashiorkor. The significantly different response of food-deprived foals to refeeding may be attributable to increased protein intake or altered physiologic state.

BackgroundAmino acidopathies are a class of inborn errors of metabolism (IEM) that can be diagnosed by analysis of amino acids (AA) in plasma. Current strategies for AA analysis include cation exchange HPLC with post-column ninhydrin derivatization, GC-MS, and LC-MS/MS-related methods. Major drawbacks of the current methods are time-consuming procedures, derivative problems, problems with retention, and MS-sensitivity. The use of hydrophilic interaction liquid chromatography (HILIC) columns is an ideal separation mode for hydrophilic compounds like AA. Here we report a HILIC-method for analysis of 36 underivatized AA in plasma to detect defects in AA metabolism that overcomes the major drawbacks of other methods.MethodsA rapid, sensitive, and specific method was developed for the analysis of AA in plasma without derivatization using HILIC coupled with tandem mass-spectrometry (Xevo TQ, Waters).ResultsExcellent separation of 36 AA (24 quantitative/12 qualitative) in plasma was achieved on an Acquity BEH Amide column (2.1×100 mm, 1.7 μm) in a single MS run of 18 min. Plasma of patients with a known IEM in AA metabolism was analyzed and all patients were correctly identified.ConclusionThe reported method analyzes 36 AA in plasma within 18 min and provides baseline separation of isomeric AA such as leucine and isoleucine. No separation was obtained for isoleucine and allo-isoleucine. The method is applicable to study defects in AA metabolism in plasma.Electronic supplementary materialThe online version of this article (doi:10.1007/s10545-016-9935-z) contains supplementary material, which is available to authorized users.

Three experiments were conducted with 108 male Friesian calves to determine the effect of protein and energy in the diet on the concentration of free amino acids in the plasma. In experiments 1 and 2, the diets contained 12 to 21 per cent crude protein, with urea or meat meal as the protein supplement. The diets were fed with and without sulphur supplementation. In experiment 3, the metabolizable energy content of the diets was changed from 2.2 to 1.8 Mcal kg-1 by the addition of 20 to 60 per cent roughage from lucerne meal or ground straw to the diets. Blood samples were collected from all calves at 11 weeks of age, and the concentration of free amino acids in the plasma was measured. As the protein content of the diets increased, the percentage of essential amino acids of the total amino acids in the plasma increased. The percentage of essential amino acids was also greater in the calves fed meat meal than in those fed urea. These changes were mainly due to increased concentrations of the branched chain amino acids and decreased concentrations of glycine and glutamic acid. The supplementation of the diets containing urea with sodium sulphate increased the concentrations of cystine and methionine in the plasma. As the metabolizable energy intake of the calves increased there was an increase in the concentration of total amino acids in the plasma. Hence, the effect of protein and energy in the diet must be considered in studying the concentration of amino acids in the plasma.

Use of Free Amino Acid Concentrations in Blood Plasma of Chicks to Detect Deficiencies and Excesses of Dietary Amino Acids

Introducing the antibiotic therapy into clinical practice is one of the most important steps in the fight against infectious diseases. Antibacterial therapy is prescribed to more than 70 % of all patients in intensive care units. Carbapenems remain the “cornerstone” of antibiotic therapy for severe infections. The main problem on the use of antibiotics is a long-term alteration of the healthy microbiota and a horizontal transfer of resistance genes. The structure of the fund of free amino acids in biological fluids and tissues is an integral characteristic of metabolism, and the effect of antibacterial agents on their concentration in plasma has not been sufficiently studied.The aim of this study was to conduct a comparative analysis of the effects of meropenem and imipenem/cilastatin on the bacterial flora of the intestine and the pool of free amino acids in the blood plasma of rats.The experiments were carried out on white outbred rats kept on a standard vivarium diet and having free access to drinking water. Animals were divided into 3 groups: group 1 (n = 7) – animals were intraperitoneally injected with 0.9 % NaCl solution for 10 days; group 2 (n = 7) – animals were intraperitoneally injected with meropenem-TF (SOOO “TriplePharm”, Republic of Belarus) at a dose of 60 mg/kg body weight for 10 days, group 3 (n = 7) – animals were injected with imipenem in the same way for 10 days /cilastatin (SOOO “TriplePharm”, RB) at a dose of 120 mg/kg of body weight. Free amino acids in blood plasma were determined by chromatography.A comparative analysis of the pool of free amino acids in the plasma of rats after the administration of antibacterial drugs of the carbapenem group revealed a number of significant confidence (p < 0.05) differences in the both study groups. Thus, in the imipenem/cilastatin group, an increase in the total amount of proteinogenic amino acids, essential amino acids, the total amount of aromatic amino acids and a decrease in the nonessential-to essential amino acid ratio were determined. In the meropenem group, these abnormalities were not identified. However, the total amount of sulfur-containing amino acids decreased.The results obtained showed a significant change in the levels of the both individual amino acids and their total amount. A more pronounced change in the pool of free amino acids in the blood plasma after administrating imipenem/cilastatin is probably due to the presence of cilastatin (renal dehydropeptidase inhibitor) in the composition of the drug, as well as its more pronounced toxicity. When compared with meropenem, imipenem/cilastatin resulted in a greater growth of spore-forming anaerobes. In turn, meropenem more reduced the level of bifidobacteria, lactose-positive bacteria of the E. coli group than imipenem/cilastatin.

Early Amino Acid Administration for Premature Neonates

Early Changes in Plasma Amino Acid Concentrations during Aggressive Nutritional Therapy in Extremely Low Birth Weight Infants

High Levels of Dietary Amino and Branched-Chain α-Keto Acids Alter Plasma and Brain Amino Acid Concentrations in Rats

Little is known about the amino acid composition of horse sweat, but significant fluid losses can occur during exercise with the potential to facilitate substantial nutrient losses. Sweat and plasma amino acid compositions for Standardbred horses were assessed to determine losses during a standardised training regime. Two cohorts of horses 2013 (n=5) and 2014 (n=6) were assessed to determine baseline levels of plasma and sweat amino acids. An amino acid supplement designed to counter losses in sweat during exercise was provided after morning exercise daily for 5 weeks (2013, n=5; 2014, n=4). After the supplementation period, blood and sweat samples were collected to assess amino acid composition changes. From baseline assessments of sweat in both cohorts, it was found that serine, glutamic acid, histidine and phenylalanine were present at up to 9 times the corresponding plasma concentrations and aspartic acid at 0-2.2 μmol/l in plasma was measured at 154-262 μmol/l in sweat. In contrast, glutamine, asparagine, methionine and cystine were conserved in the plasma by having lower concentrations in the sweat. The predominant plasma amino acids were glycine, glutamine, alanine, valine, serine, lysine and leucine. As the sweat amino acid profile did not simply reflect plasma composition, it was proposed that mechanisms exist to generate high concentrations of certain amino acids in sweat whilst selectively preventing the loss of others. The estimated amino acid load in 16 l of circulating plasma was 3.8-4.3 g and the calculated loss via sweat during high intensity exercise was 1.6-3.0 g. Following supplementation, total plasma amino acid levels from both cohorts increased from initial levels of 2,293 and 2,044 µmol/l to post-supplementation levels of 2,674 and 2,663 µmol/l respectively (P<0.05). It was concluded that the strategy of providing free amino acids immediately after exercise resulted in raising resting plasma amino acid levels.

Polycystic Kidney Disease (PKD) is a severe, genetically inherited disease that leads to renal failure. Like several other chronic kidney diseases, male sex is a risk factor for accelerated PKD. Rat models of both Autosomal Recessive and Dominant forms of PKD (PCK and Han:SPRD rats, respectively) exhibit sex differences in disease progression. Previous studies have found that amino acids (AAs) and peptides are predominant constituents of cystic fluid. We hypothesized that AA homeostasis in male and female cystic fluid would demonstrate sexual dimorphism, and these differences may provide essential information about the progression of cystogenesis. We quantified the AAs in cystic fluid, plasma, and urine in PCK and control Sprague Dawley (SD) rats (only plasma and urine for SD rats). Of the 42 AAs that were measured, only asparagine, serine, aspartic acid, glutamic acid, beta-alanine, cystathionine, and leucine were NOT significantly different between SD and PCK plasma values. Interestingly, only 18 AAs were significantly different in urine of PCK rats compared to SD rats. In SD rats, between sexes, 26 AAs were significantly different in plasma and 5 were significantly different in urine. Among PCK rats, 13 AAs in plasma, 9 AAs in urine, and 4 AAs in cystic fluid were significantly different between sexes. The 4 AAs that differed between male and female cystic fluid were 1-methylhistidine, 3-methylhistidine, ethanolamine, and taurine. Moreover, taurine was the most abundant AA in cystic fluid. Taurine concentrations in both plasma (165 ± 9 vs. 128 ± 4 μM, N=6, p=0.003) and cystic fluid (7508 ± 469 vs. 4557 ± 788 μM, N=6, p=0.01) were significantly different between sexes in the PCK rats (male vs. female, respectively). Urine values for the PCK rats (9705 ± 1863 vs. 7570 ± 1631 μM, N=6) were not significantly different in males and females; however, the average urinary taurine excretion in PCK rats was nearly 4-fold greater than SD rats (8637 ± 1223 vs. 2219 ± 465 μM, N=12, p<0.0001). There were no significant differences in taurine concentrations between SD male and female rat plasma (202 ± 17 vs. 194 ± 7.0 μM, N=6) or urine (2044 ± 614 vs. 2395 ± 752 μM, N=6). Western blot of the taurine transporter, TauT, detected bands at 50 and 75 kDa, and both bands were significantly reduced by ~50% in PCK kidneys compared to SD kidneys. Lastly, immunolabeling in PCK kidney sections demonstrated that TauT is present at the apical membrane of cyst epithelia. These results point to a potential role for AAs, and specifically for taurine in cystogenesis, which likely varies by sex in diseased, but not healthy kidneys. R00 HL153686, BX004024, R01 DK126720, R01 DK129227. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

1. The effect of a protein-free meal and a protein-rich meal on the concentration of free amino acids in plasma and muscle tissue was studied in eight healthy subjects. The energy content of the protein-free meal was 3800 kJ. The protein-rich meal was identical in composition except that 50 g of bovine serum albumin was added. Plasma and samples from the quadriceps femoris muscle (percutaneous muscle biopsy) for amino acid determination were collection before and at 1, 3, 5 and 7 h after the meal. 2. After the protein-free meal the concentrations of most essential amino acids and of some non-essential amino acids in plasma decreased continuously below basal levels at 5-7 h. The muscle concentration of essential amino acids fell too, reaching its nadir 3-5 h after the meal. The decrease in plasma amino acid concentration was smaller than the decrease in muscle concentration for all essential amino acids except phenylalanine. 3. The concentrations of most amino acids in plasma increased transiently 1 and 3 h after the protein-rich meal; histidine and several non-essential amino acids fell below the basal levels at 5-7 h after the meal. In muscle, threonine, valine, leucine, lysine and alanine were increased at 1 and 3 h after the protein-rich meal; isoleucine, serine and glycine fell below the basal level after 5 and 7 h. For the essential amino acids except threonine and lysine, the increase in plasma concentration was greater than the increase in muscle concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein restriction ameliorates proteinuria in acute adriamycin (ADR) nephrosis and decreases the renal levels of xanthine oxidase (XO), a putative mediator of ADR nephrotoxicity. Hypothetically, the effect of protein restriction on renal XO levels may be due to variations in plasma and tissue proteic amino acids (AA). To elucidate this point, the levels of AA in plasma and in renal homogenates were determined in rats with ADR nephrosis and fed diets with different protein contents: (a) high (35%) casein; (b) standard (21%) casein; (c) low (9%) casein; (d) low casein plus a synthetic mixture of Val, Leu and Ile. The protein content of the diet determined certain marked variations in plasma AA: high levels of Val, Leu and Ile were found in rats fed on a high protein diet, while the same AA were low, in rats on low protein regimen. Supplementation of the low protein diet with a synthetic mixture of branched-chain AA (Val, Leu and Ile) normalized the plasma levels of these AA. In spite of these changes, tissue AA were similar in all groups, regardless of the protein contents of the diets. Furthermore, the levels of renal XO and proteinuria were unrelated to variations in plasma AA, since both parameters were low in protein-restricted and protein-restricted AA-supplemented rats while high in rats fed a high or normoproteic diet. These data demonstrate that low protein diets induce marked alterations in plasma AA composition which are similar in may respects to those found in protein malnutrition.(ABSTRACT TRUNCATED AT 250 WORDS)