Plasma Free Amino Acid Levels Research Articles

Plasma Free Amino Acid and Carnitine Levels in Pregnant Women with Hydatidiform Mole: A Case-Controlled Study

Background: To determine plasma free amino acid (FAA) and carnitine levels in pregnant women with hydatidiform mole (HM). Materials and Methods: Twenty-three pregnant women with HM, and 24 healthy pregnant wo-men as controls were enrolled in the study. FAA and carnitine concentrations were measured in plasma using liquid chromatography/tandem mass spectrometry (LC-MS). Results: The levels of alanine, arginine, and valine from the 14 amino acids examined were signif-icantly lower in the HM group than in the healthy group (p = 0.019, p = 0.009, and p = 0.03, respec-tively). In addition, several carnitines, C8DC, C16:1, and C18, of the 27 carnitines examined were significantly higher in the HM group than in the control group (p = 0.021, p = 0.03, and p = 0.021, respectively). Conclusions: This study demonstrated that a decrease in some plasma FAAs and an increase in some plasma carnitine levels might be effective in the pathogenesis of HM.

Upregulation of BRCA1 and 2 protein expression is associated with dysregulation in amino acids profiles in breast cancer

BackgroundThe prevalence of breast cancer (BC) is high among cancers in Egypt, ranking it the most common cause of cancer mortality in women. BRCA1 and BRCA2 tumor suppressors proteins have a specific relationship with BC. Plasma free amino acids levels (PFAAs) have been reported to exhibit altered profiles among cancer patients. Thus, the present study aims to examine the alteration of the PFAAs profiles and investigate their association with BRCA1 and 2 circulating levels in Egyptian females diagnosed with BC and in females with family history of BC to establish potential early detection strategies for BC.Methods and resultsThis study included 26 BC patients, 22 females with family history of BC (relatives) in addition to 38 healthy females as control group. Quantitative measurement of PFAAs was determined by the ion exchange separation method through high performance liquid chromatography. BRCA1 and BRCA2 concentrations were determined using ELISA. Our results showed PFAAs profiles in BC patients and in females with BC family history with significant upregulation in mean plasma levels of Alanine, Phenylalanine, Glutamate and Cysteine and downregulation of Taurine, Threonine, Serine, Glycine, Valine, Methionine and Histidine levels compared to controls. Also, a significant positive correlation was observed between plasma BRCA1 and Valine levels while a significant negative correlation was observed between BRCA2 and Lysine plasma levels.ConclusionPFAAs profile can potentially be used in early screening for BC patients and for susceptible females.

Tissue and plasma free amino acid detection by LC-MS/MS method in high grade glioma patients.

The changes in serum amino acid profiles are evaluated in different types of cancers and screening tests were developed for estimating the risk of cancer by rapid analysis of plasma free amino acid (PFAA) levels. There is scarce evidence about the metabolomics analysis of PFAA in malignant gliomas. The aim of the present study was to identify the most promising diagnostic amino acid biomarkers that could be objectively measured for high-grade glioma and to compare their level with the tissue counterpart. In this prospective study, we collected serum samples from 22 patients with the pathological diagnosis of high-grade diffuse glioma according to WHO 2016 classification and 22 healthy subjects, and brain tissue from 22 controls. Plasma and tissue amino acid concentrations were analyzed applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Serum alanine, alpha-aminobutyric acid (AABA), lysine (Lys) and cysteine concentrations were significantly higher in high-grade glioma patients despite low levels of alanine and Lys in the tumor tissue. Aspartic acid, histidine and taurine were significantly decreased in both serum and tumors of glioma patients. A positive correlation was detected between tumor volumes and serum levels of latter three amino acids. This study demonstrated potential amino acids which may have diagnostic value for high-grade glioma patients by utilizing LC-MS/MS method. Our results are preliminary to compare serum and tissue levels of amino acids in patients with malignant gliomas. The data presented here may provide feature ideas about the metabolic pathways in the pathogenesis of gliomas.

Plasma Free Amino Acid Levels in Uremic Rats Given High and Low Protein Diets or Intravenous Infusions of Amino Acid Solutions

Plasma free amino acids were measured in uremic and sham-operated rats fed for 10 days a high (24%) or a low (6%) protein diet or given total parenteral nutrition, either with a complete amino acid solution or a solution containing only the amino acids considered to be indispensable in uremia. The plasma levels of citrulline, glycine, hydroxyproline, and 1- and 3-methylhistidine were elevated in all uremic rats compared with the corresponding controls. Plasma tryptophan was reduced in three out of four uremic groups and the branched-chain amino acids and tyrosine were reduced in plasma of orally fed uremic rats but not after intravenous infusion. Plasma serine increased with increased plasma glycine levels. The ratio serine:glycine was, however, significantly smaller in the uremic rats. The ratios of plasma valine:glycine and indispensable:dispensable amino acids were affected by nitrogen intake as well as by uremia, whereas plasma citrulline:tryptophan was influenced only by the uremic state. This ratio was markedly elevated in all uremic groups. The alterations observed in the plasma free amino acid levels and ratios of the uremic rats were similar to those reported from clinical observations on patients with chronic renal failure.uremic rats plasma amino acids total parenteral nutrition protein diets

Characteristic changes in plasma glutamate levels and free amino acid profiles in Japanese patients with type 1 diabetes mellitus.

In addition to absolute insulin deficiency, dysregulated glucagon in type 1 diabetes is considered pathophysiologically important. Previously, we confirmed the presence of dysregulated glucagon in Japanese patients with type 1 diabetes, and found a significant correlation between plasma glucagon and blood urea nitrogen levels, suggesting an association between glucagon and amino acid metabolism. In this study, we evaluated plasma amino acid levels in Japanese patients with type 1 diabetes in the context of their functional relationship with glucagon. We assessed plasma free amino acid levels using liquid chromatography-mass spectrometry in 77 Japanese patients with type 1 diabetes, and statistically analyzed their characteristics and relationships with clinical parameters, including glucagon. Participants with type 1 diabetes showed a large decrease in glutamate levels together with a characteristic change in plasma free amino acid profiles. The network structural prediction analyses showed correlations between each amino acid and glucagon in type 1 diabetes. Participants with type 1 diabetes showed characteristic changes in plasma glutamate levels and free amino acid profiles compared with controls and type 2 diabetes patients. Glucagon showed a closer correlation with amino acids than with parameters of glucose metabolism, suggesting that type 1 diabetes includes dysregulation in amino acids through dysregulated glucagon from remaining pancreatic α-cells, together with that in glucose by insulin deficiency.

A Pilot Study for Investigation of Plasma Amino Acid Profile in Neurofibromatosis Type 1 Patients.

Neurofibromatosis, also known as Von Recklinghausen disease, is a systemic and progressive genetic disease that primarily affects the skin, eyes, nervous system, and bones. The disease can occur in a variety of ways and can vary in individuals. Metabolomic-based research using blood samples has enabled new diagnostic methods to be used in the diagnosis of various diseases, especially cancer. Among the metabolites, profiling of plasma free amino acids (PFAA) is a promising approach because PFAAs bind all organ systems and play an important role in the metabolism. This study aimed to determine the characteristics of PFAA profiles in neurofibromatosis patients and the possibility of using them for early detection and treatment of the disease. Patients with a diagnosis of Neurofibromatosis Type I confirmed by genetic analysis and healthy individuals of the same age group without any disease were included in the study. We analysed the nineteen plasma free amino acids (phenylalanine, proline, threonine, arginine, asparagine, cystine, valine, glutamate, tyrosine, serine, glutamine, glycine, tryptophane, leucine, lysine, methionine, isoleucine, aspartate and alanine) from neurofibromatosis Type I patients and control group by liquid chromatography tandem mass spectrometry (LC-MS/MS) in Metabolism Laboratory of Harran University Research and Application Hospital. The results of the plasma free amino acid levels were divided into 3 groups as essential, semi-essential, and non-essential. The differences in amino acid levels between groups were determined. The levels of eight amino acids (methionine, arginine, cystine, glutamine, proline, asparagine, serine, aspartate) were significantly altered in patients with neurofibromatosis type 1. In essential amino acids, methionine levels were significantly higher in the patient group than control group. While the levels of arginine and glutamine in semi-essential amino acids were statistically significantly higher in the patient group, a significant decrease was observed in cystine and proline levels compared to the control group's amino acid levels. In the non-essential amino acids group, asparagine, serine and aspartate amino acid levels were significantly higher in the patient group compared to the control group. The current research predicates that eight amino acids, namely methionine, arginine, cystine, glutamine, proline, asparagine, serine, aspartate can be considered to be valuable biomarkers for neurofibromatosis type I. This present study is the first to build models for neurofibromatosis Type I screening using plasma free amino acids and the amino acid profile will be able to guide the prediction of the complications that may occur during the course of the disease.

Assessment of Blood Plasma Free-amino Acid Levels in Infertile Men.

The objective of this study was to investigate the significance of the blood levels of free amino acids (AAs) in infertile men. Ninety-three men who underwent examinations for infertility were included. The concentrations of 20 AAs were measured and compared in four groups (normospermia, obstructive azoospermia, oligozoospermia, non-obstructive azoospermia) based on semen analysis and clinical parameters. When the 93 men were divided into normospermia, obstructive azoospermia, oligozoospermia, and non-obstructive azoospermia groups, no significant differences were found in the concentrations of the 20 AAs between them. We then compared 49 men diagnosed with normozoospermia or oligozoospermia according to the median sperm motility and morphology abnormalities rates (30% and 20%, respectively). Men with low motility rates had significantly lower levels of tryptophan and alanine, and men with high abnormal morphology rates had significantly lower levels of aspartate and glutamate. AAs are probably involved in the pathogenesis of male infertility, particularly oligozoospermia.

Evaluation of Plasma Free Amino Acid and Carnitine Levels in Patients with Cesarean Scar Pregnancy.

This study aimed to explore the plasma free amino acid (FAA) and carnitine levels in pregnant women with cesarean scar pregnancy (CSP), and to compare them with those of healthy pregnant women. This prospective and randomized controlled study was conducted in patients admitted to Harran University Medical Faculty Hospital Obstetrics Clinic between January 2018 and January 2019. A total of 60 patients were included in the study, and the patients were divided into two groups: the CSP group (n = 30) and the healthy pregnant group as the control group (n = 30). The blood samples were taken from the participants between 7 - 12 weeks of gestation. Twenty-seven carnitines and their esters and 14 FAAs were analysed by liquid chromatography - mass spectrometry (LC-MS/MS). The mean plasma concentrations of some carnitines, including C2, C5, C5-OH, C5-DC, C6, C8-1, C12, C14, C14-1, C14-2, C16, C16-1, C18, and C18-1 were significantly higher in the CSP group than in the control group. However, other carnitines, including C0, C3, C4, C4-DC, C5- 1, C6-DC, C8, C8-DC, C10, C10-1, C18-1-OH, and C18-2, were similar in both groups. The plasma levels of some FAAs, including Methyl Glutaryl, Leu, Met, Phe, Arg, Orn, and Glu values, were significantly higher in the CSP group than in the control group. However, there was no statistical significance in other FAA levels, including Val, Asa, Tyr, Asp, Ala, Cit, and Gly between the two groups. Additionally, Pearson's correlation analysis showed that there were significantly positive correlations between many FAA and carnitine values. Since several plasma carnitines and FAA levels were higher in the CSP group than in the control group, we think that scar pregnancy increases the metabolic need for myometrial invasion. Also, we think that these results may be useful in clinical practice for CSP diagnosis.

Dietary Insect Powder Protein Sources Improve Protein Utilization by Regulation on Intestinal Amino Acid-Chemosensing System.

Simple SummaryInsect powders, including Tenebrio molitor (TM), Musca domestica larvae (MDL) and Zophobas morio (ZM), as high-quality and renewable protein sources are commonly applied in livestock and poultry feed production. The molecular effect of insect protein on amino acid metabolism in pigs needs to be explored. We found that insect powder as a protein source in feed regulated the mTOR signal pathway and improved amino acid transportation in the intestine for growth promotion. Insect powder may be a potentially promising protein source for pig production.This study was conducted to evaluate the effects of dietary insect powder supplementation as a protein source on plasma amino acid profiles, intestinal amino acid transport and sensing in a piglet model. A total of 144 weanling piglets were randomly assigned to four experimental diets for two phases (Days 1–28 and Days 29–56), to assess the effects on amino acid profiles and transportation in the segments of the intestine. The groups were basal diet (control), control diet plus Tenebrio molitor (TM), control diet plus Musca domestica larvae (MDL) and control diet plus Zophobas morio (ZM). The plasma free amino acid levels were stable comparable among treatments, except that the lysine level was significantly reduced by dietary MDL and ZM supplementation in the first phase (p < 0.05). In the 1st phase, the sensitivity of intestinal segments to the regulation of the amino acid level by insect powder supplementation follows sequence: colon > ileum > jejunum, while the order switched to jejunum > colon > ileum in the 2nd phase. The relative RNA expressions of mitogen-activated protein 4 kinase 3 (MAP4K3), sodium dependent neutral amino acid transporter2 (SNAT2), the transient receptor potential cation channel subfamily V member 1 (TRPV1) and taste 1 receptor member 1/3 (T1R3) in the segments of the intestine were affected by different dietary insect powder supplementation. G protein-coupled receptor family C group 6 member A (GPRC6A) level in the jejunal and colonic mucosa was upregulated by MDL supplementation (p < 0.05). These results indicated that dietary insects improved the metabolism of the amino acid in the prophase (the 1st phase) through regulating the sensing gene and mTOR signal pathway in intestinal mucosa by targeting different receptors. The finding demonstrates that the insect powder is a potentially promising source for protein deposition.

A multicentre clinical validation of AminoIndex Cancer Screening (AICS)

AminoIndex Cancer Screening (AICS) is a novel cancer screening test based on plasma free amino acid (PFAA) levels. This system categorises subjects as rank A, B, or C in order of increasing probability of each cancer incidence. The current study aimed to validate the potential of AICS for cancer detection. AICS values were determined from the PFAA levels in subjects examined at Chiba Cancer Center Cohort, Mitsui Memorial Hospital, and Saihaku Hospital, and the cancer incidence was investigated. The sensitivities of rank C for cancer diagnosis within 1 year after AICS examination were 83.3% (10/12) for gastric, 50.0% (2/4) for lung, 46.2% (6/13) for colorectal, 50.0% (8/16) for prostate, 43.8% (7/16) for breast, and 50.0% (1/2) for uterine/ovarian cancer. The total cancer detection rate via AICS was 0.33% (34/10,245). The sensitivities during the maximum follow-up period of 6.2 years were 51.7% (15/29) for gastric, 18.2% (2/11) for lung, 28.6% (8/28) for colorectal, 36.4% (8/22) for prostate, 29.0% (9/31) for breast, and 33.3% (2/6) for uterine/ovarian cancers. In conclusion, AICS is a more useful method for evaluating the probability of cancer incidence than for predicting onset, suggesting that annual AICS should be recommended to detect any malignancy.

Alteration of plasma free amino acids’ level in oral squamous cell carcinoma patients using High Performance Liquid Chromatography

ObjectivesOral cancer inflicts a substantial challenge worldwide being a highly lethal and disfiguring disease. Delayed diagnosis keeps the mortality high. Plasma free amino acids (PFAAs) circulate throughout the body, participating in metabolism. Subsequently, changes in PFAA profile might mirror cancer induced protein metabolism. In this context, this study aims to quantify, compare and correlate PFAAs level in OSCC and control group using High performance liquid chromatography (HPLC). MethodsA total of 60 samples: 30 OSCC subjects and 30 age, sex matched healthy controls were taken. Following clinical examination and histopathological confirmation, 5 ml blood was collected in a tube containing EDTA and centrifuged. The PFAAs levels were quantified using HPLC. ResultsOut of 19 PFAAs, concentration of aspartate, glutamate and arginine were significantly decreased and of asparagine, glutamine and cysteine were significantly increased in OSCC group. Furthermore, comparing well (group I) and moderately (group II) differentiated OSCC group, the level of asparagine was significantly decreased, and of serine significantly increased in group II. Significant alterations were also observed, when group I and II were compared to control group in the following: aspartate, glutamate, asparagine, serine, arginine and cysteine. On comparing stage III, IV OSCC group to control group the levels of aspartate, glutamate, asparagine and cysteine showed significant alterations. ConclusionAltered protein metabolism, as shown in PFAA profile may be employed as a supplementary tool for diagnosing OSCC. Meticulous study of amino acid assays may facilitate in understanding the route of metabolic derangement in OSCC patients.

Perioperative dynamics and significance of plasma-free amino acid profiles in colorectal cancer

BackgroundFor early detection of cancer, we have previously developed the AminoIndex Cancer Screening (AICS) system, which quantifies 6 plasma-free amino acids (PFAAs) in blood samples. Herein, we examined the usefulness of the AICS in patients with colorectal cancer (CRC) by comparing the preoperative and postoperative PFAA profiles.MethodsOur study cohort consisted of 62 patients who had undergone curative resection for CRC at our cancer center, with no recurrence at the time of the study. Blood samples were collected from fasted patients within 1 week before the resection and at 0.5–6.5 years post-resection. Following plasmapheresis, the PFAA levels were measured via liquid chromatography/mass spectrometry, and the AICS values were computed (the higher the value, the greater the probability of cancer). Risk was calculated from the AICS value and ranked as A, B, or C, with rank C representing the highest risk. All patients in our study were rank B + C.ResultsThe postoperative AICS value was lower than the preoperative value in 57 of the 62 patients; the rank was also lower postoperatively (49 patients, p < 0.001). The decline in both was stage-independent, even occurring in patients with right-sided tumors or poorly differentiated adenocarcinomas. For comparative purposes, the levels of 2 tumor markers (carbohydrate antigen 19–9 and carcinoembryonic antigen) were also examined; these were within the reference ranges in 70–80% of patients preoperatively and in 80–90% postoperatively.ConclusionWe suggest that tumor-bearing conditions alter the PFAA profiles, which may be used to predict prognosis and monitor for recurrence in CRC patients after tumor resection.Trial registrationThis trial has been retrospectively registered at UMIN-CTR R000028005, Oct 06, 2016.

Plasma amino acid profile associated with fatty liver disease and co-occurrence of metabolic risk factors

Fatty liver disease (FLD) increases the risk of diabetes, cardiovascular disease, and steatohepatitis, which leads to fibrosis, cirrhosis, and hepatocellular carcinoma. Thus, the early detection of FLD is necessary. We aimed to find a quantitative and feasible model for discriminating the FLD, based on plasma free amino acid (PFAA) profiles. We constructed models of the relationship between PFAA levels in 2,000 generally healthy Japanese subjects and the diagnosis of FLD by abdominal ultrasound scan by multiple logistic regression analysis with variable selection. The performance of these models for FLD discrimination was validated using an independent data set of 2,160 subjects. The generated PFAA-based model was able to identify FLD patients. The area under the receiver operating characteristic curve for the model was 0.83, which was higher than those of other existing liver function-associated markers ranging from 0.53 to 0.80. The value of the linear discriminant in the model yielded the adjusted odds ratio (with 95% confidence intervals) for a 1 standard deviation increase of 2.63 (2.14–3.25) in the multiple logistic regression analysis with known liver function-associated covariates. Interestingly, the linear discriminant values were significantly associated with the progression of FLD, and patients with nonalcoholic steatohepatitis also exhibited higher values.

P2.05-010 Changes between Pre- and Post-Operative AICS (Lung) in NSCLC Patients: Predictability of High-Risk Cases with Recurrence

Plasma free amino acid (PFAA) levels are known to change in patients with malignant diseases. We have developed AminoIndexTM Cancer Screening (AICSTM) using “AminoIndex Technology”, which is a multivariate analysis of PFAA concentrations in various cancer patients and healthy controls. In Japan, AICSTM is now commercially available for simultaneous screening of seven cancer types, including lung cancer. The lung cancer specific AICS [AICS (lung)] are classified as rank A (AICS values: 0.0–4.9), rank B (5.0–7.9), or rank C (8.0–10.0); the closer to rank C, the higher risk of lung cancer.

The impact of moderate altitude on exercise metabolism in recreational sportsmen: a nuclear magnetic resonance metabolomic approach.

Although it is known that altitude impairs performance in endurance sports, there is no consensus on the involvement of energy substrates in this process. The objective of the present study was to determine whether the metabolomic pathways used during endurance exercise differ according to whether the effort is performed at sea level or at moderate altitude (at the same exercise intensity, using proton nuclear magnetic resonance, 1H NMR). Twenty subjects performed two 60-min endurance exercise tests at sea level and at 2150 m at identical relative intensity on a cycle ergometer. Blood plasma was obtained from venous blood samples drawn before and after exercise. 1H NMR spectral analysis was then performed on the plasma samples. A multivariate statistical technique was applied to the NMR data. The respective relative intensities of the sea level and altitude endurance tests were essentially the same when expressed as a percentage of the maximal oxygen uptake measured during the corresponding incremental maximal exercise test. Lipid use was similar at sea level and at altitude. In the plasma, levels of glucose, glutamine, alanine, and branched-chain amino acids had decreased after exercise at altitude but not after exercise at sea level. The decrease in plasma glucose and free amino acid levels observed after exercise at altitude indicated that increased involvement of the protein pathway was necessary but not sufficient for the maintenance of glycaemia. Metabolomics is a powerful means of gaining insight into the metabolic changes induced by exercise at altitude.

Central adiposity-induced plasma-free amino acid alterations are associated with increased insulin resistance in healthy Singaporean adults.

Recent metabolomics technique reveals a plasma-free amino acid (PFAA)-based metabolite signature that is suggestive of altered PFAAs being an early manifestation of obesity-related insulin resistance. However, the PFAA profiles within non-obese, but more insulin-resistant Asians are not well researched. Compared with Caucasians, Asian populations have more central adiposity, which is generally regarded as metabolically more adverse, but the underlying mechanisms remain unclear. In the present study, we examined whether PFAA profiling was at least one important factor mediating central adiposity and insulin resistance, and aid in cardiovascular risk assessment in healthy Asians with normal body weight. This was a cross-sectional study. A total of 190 healthy men (n=87 with a mean±s.d. body mass index (BMI) of 23.5±3.5 kg/m2) and women (n=103 with a mean±s.d. BMI of 21.4±3.7 kg/m2) residing in Singapore took part in this study. PFAA levels were measured by using an amino acid analyzer. Basic anthropometric measurements, fasting blood glucose, fasting serum insulin and lipid profiles were obtained using standard protocols. Seven out of 18 amino acids were significantly correlated with measures of obesity (for example, waist circumference; waist-to-hip ratio and BMI) in current participants. Among them, the plasma concentrations of five amino acids, including Phe, Tyr, Met, Ala and His were positively associated with waist-to-hip ratio. With the exception of His, which had no association with insulin resistance, Phe, Tyr, Met and Ala were significantly associated with hyperinsulinemia and insulin resistance (P<0.05). In contrast, no associations were observed between circulating BCAAs (that is, Val, Leu, Ile), measures of obesity and insulin resistance. However, significant inverse associations were observed between BCAAs and total cholesterol and high-density lipoprotein. We found that central adiposity was associated with alterations of specific amino acids. As a result, PFAAs may serve as metabolite predictors of hyperglycemia, hyperinsulinemia and dyslipidemia in healthy participants.

Alteration in plasma free amino acid levels and its association with gout

BackgroundStudies on the association of plasma-free amino acids with gout are very limited and produced conflicting results. Therefore, we sought to explore and characterize the plasma-free amino acid (PFAA) profile in patients with gout and evaluate its association with the latter.MethodsData from a total of 819 subjects (including 34 patients with gout) undergoing an annual health examination program in Shimane, Japan were considered for this study. Venous blood samples were collected from the subjects and concentrations of 19 plasma amino acids were determined by high-performance liquid chromatography–electrospray ionization–mass spectrometry. Student’s t-test was applied for comparison of variables between patient and control groups. The relationships between the presence or absence of gout and individual amino acids were investigated by logistic regression analysis controlling for the effects of potential demographic confounders.ResultsAmong 19 amino acids, the levels of 10 amino acids (alanine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, serine, tryptophan, valine) differed significantly (P < .001 to .05) between the patient and control groups. Univariate logistic regression analysis revealed that plasma levels of alanine, isoleucine, leucine, phenylalanine, tryptophan and valine had significant positive associations (P < .005 to .05) whereas glycine and serine had significant inverse association (P < .05) with gout.ConclusionsThe observed significant changes in PFAA profiles may have important implications for improving our understanding of pathophysiology, diagnosis and prevention of gout. The findings of this study need further confirmation in future large-scale studies involving a larger number of patients with gout.

Analysis of plasma free amino acid profiles in canine brain tumors.

Canine brain tumors are best diagnosed using magnetic resonance imaging (MRI). However, opportunities of MRI examination are restricted due to its limited availability in veterinary facilities; thus, numerous canine brain tumors are diagnosed at an advanced stage. Therefore, development of a noninvasive diagnostic biomarker is required for the early detection of brain tumors. In the present study, plasma free amino acid (PFAA) profiles between dogs with and without brain tumors were compared. A total of 12 dogs with brain tumors, diagnosed based on clinical signs, and on the results of intracranial MRI and/or pathological examination were evaluated. In addition, eight dogs diagnosed with idiopathic epilepsy and 16 healthy dogs were also included. A liquid chromatography system with automated pre-column derivatization functionality was used to measure the levels of 20 amino acids. As a result, the levels of three amino acids (alanine, proline and isoleucine) were increased significantly (1.6-, 1.5- and 1.6-fold, respectively) in the plasma of dogs with brain tumors as compared with the levels in control dogs (all P<0.05). Thus, the PFAA levels of dogs with brain tumors differed from those of healthy dogs. The present study demonstrated that analysis of PFAA levels of dogs with brain tumors may serve as a useful biomarker for the early detection of canine brain tumors.

Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis.

Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration.

Plasma amino acid profiles in healthy East Asian subpopulations living in Japan

ObjectivesProfiles of plasma free amino acids (PFAAs) have been utilized as biomarkers to detect various diseases. However, few studies have investigated whether ethnicity or specific subpopulations within East Asia influence PFAA concentrations.MethodsA total of 95 healthy volunteers living in Japan, including 31 Japanese individuals, 36 Korean individuals and 28 Chinese individuals, were enrolled. Participants’ PFAA levels were measured by high‐performance liquid chromatography mass spectrometry, and the effects of factors such as sex, age, body mass index (BMI) and subpopulation on PFAA profiles were analyzed.ResultsWith the exception of glutamine and α‐aminobutyric acid, there were no significant differences among the three examined subpopulations with respect to either the means or the distributions of PFAA concentrations. A multiple regression analysis revealed that most of the PFAA concentrations were significantly related to sex. Ornithine concentrations, glutamate concentrations, and glutamine and α‐aminobutyric acid concentrations were significantly associated with age, BMI, and Chinese subpopulation, respectively.ConclusionThe study results indicate that the contributions of subpopulation within East Asia to PFAA profiles are small, particularly relative to the contributions provided by sex. Am. J. Hum. Biol. 28:236–239, 2016. © 2015 The Authors American Journal of Human Biology Published by Wiley Periodicals, Inc.