Determination of amino acids in human biological fluids by high-performance liquid chromatography: critical review.

The quantitation and qualification of amino acids are most commonly used in clinical and epidemiological studies, and provide an excellent way of monitoring compounds in human fluids which have not been monitored previously, to prevent some diseases. Because of this, it is not surprising that scientific interest in evaluating these compounds has resurfaced in recent years and has precipitated the development of a multitude of new analytical techniques. This review considers recent developments in HPLC analytics on the basis of publications from the last few years. It helps to update and systematize knowledge in this area. Particular attention is paid to the progress of analytical methods, pointing out the advantages and drawbacks of the various techniques used for the preparation, separation and determination of amino acids. Depending on the type of sample, the preparation conditions for HPLC analysis change. For this reason, the review has focused on three types of samples, namely urine, blood and cerebrospinal fluid. Despite time-consuming sample preparation before HPLC analysis, an additional derivatization technique should be used, depending on the detection technique used. There are proposals for columns that are specially modified for amino acid separation without derivatization, but the limit of detection of the substance is less beneficial. In view of the fact that amino acid analyses have been performed for years and new solutions may generate increased costs, it may turn out that older proposals are much more advantageous.

Plasma free amino acid profiling as metabolomic diagnostic and prognostic biomarker in paediatric cancer patients: a follow-up study.

Amino acids (AAs) play a crucial role in cancer cell metabolism. Levels of 22 plasma AAs at the time of diagnosis and after treatment were established among 39 pediatric cancer patients and 33 healthy children. Glutamic acid levels decreased and tryptophan levels increased during treatment. Cancer patients presented significantly lower levels of glutamine and leucine post-treatment while levels of 12 other AAs were higher comparing to controls. Results suggest that plasma free AA profile may serve as a prognostic biomarker.

Amino acid profile after oral nutritional supplementation in hemodialysis patients with protein-energy wasting.

OBJECTIVES: Protein-energy wasting (PEW) is highly prevalent in patients on hemodialysis (HD). Oral nutritional supplementation (ONS) is recommended for malnourished patients on HD. The aim of this study was to evaluate ONS on plasma amino acid in HD patients with PEW. METHODS: Thirty-two HD patients with a mean age 59.1 ± 9.5 y with PEW were enrolled into the study. Patients were prescribed ONS (125 mL twice a day for 3 mo) together with dietary advice. The nutritional status was evaluated by means of body mass index, Subjective Global Assessment, and serum albumin and prealbumin levels. The percentages of body fat and lean body mass were measured by means of the near-infrared method. The lean body mass-to-body weight ratios were calculated. Tumor necrosis factor, interleukin-6 and high-sensitivity C-reactive protein, were measured by the enzyme-linked immunosorbent assay method. Serum concentrations of amino acids were measured by the high-performance liquid chromatography method. RESULTS: After 3 mo of ONS, a significant increase of both serum prealbumin and albumin was observed. The concentration of most of the amino acids increased independently on inflammation. CONCLUSIONS: Dietary advice, combined with ONS, is effective in HD patients with PEW. Both dietary advice and ONS are needed to be sure that patients consume an adequate daily amount of calories and protein.

Amino acid profiles as potential biomarkers for pediatric cancers: a preliminary communication.

AIM: Childhood cancer remains one of the main cause of death in the pediatric population. Amino acids (AAs) level alterations in plasma are considered to play a role in carcinogenesis and further course of the disease. METHODS: Seventy-seven children with cancer, including 47 with hematological and 30 with solid tumors were enrolled in this study and compared with healthy children. Twenty-two plasma-free AAs were determined by HPLC with fluorometric detection. RESULTS: The results revealed significant decrease in glutamine levels for oncological patients and significant increase in aspartic acid, glutamic acid, asparagine, serine, citrulline, alanine, GABA, tryptophan, methionine, valine, phenylalanine and isoleucine levels in cancer children versus control. CONCLUSION: Plasma-free AA profile as a biomarker, which combines metabolic and clinical data, as an innovative and interdisciplinary approach, may allow for faster detection of tumor occurrence, and in the future for monitoring patient during treatment, and possible prediction of cancer recurrence.