Amino acids in blood and urine

Gas chromatographic methods can aid in these diagnoses, for amino acids in blood and urine and for organic acids in urine. 

The study of amino acids is indeed facilitated by different factors the number of naturally occurring amino acids is relatively limited techniques of a fairly good selectivity are available for the characterization of amino acids finally, the concentration of amino acids in blood and urine is not notably influenced by the diet, within the limits of normal variations in protein intake (B17). Such factors do not exist in the case of organic acids a very large number of such acids must be considered as potential constituents of blood and urine no selective method of characterization is available finally, their concentration depends largely, for many, upon diet. Despite these differences, a parallelism can be shown between the historical development of our knowledge in the two fields. 

A Micromethod for the Clinical Chemistry Routine Analysis of Amino Acids in Blood and Urine by Capillary Gas-Liquid Chromatography of Isobutyl Esters N(0)-Heptafluorobutyrare Derivatives... 

Bhushan (1991) on amino acids and their derivatives their new review includes references through 1994. Jain (1996) has reviewed studies on the applications of TLC to amino acid analysis of biological fluids and tissues. Such analyses are important in making diagnoses of inborn errors of amino acid metabolism. It was noted by Jain (1996) that TLC has proved useful to screen and quantify abnormal amounts of free amino acids in blood and urine samples. Shalaby (1996) in his chapter on TLC in food analysis has provided some protocols on amino acid analysis following the hydrolysis of protein samples. Fried and Haseeb (1996) in their chapter on TLC in parasitology have provided some information on the analysis of free pool amino acids from tissues of parasites and from the hemo-lymph of mosquitoes infected with Plasmodium (the malaria organism). 

Soupart, P., Free amino acids of blood and urine in the human. In Amino Acid Pools (J. T. Holden, ed.), pp. 220-263. Elsevier, Amsterdam, 1962. 

Lactate and pyruvate in blood Ketone bodies in blood Amino adds in blood and urine Lactate and amino acids in CSF Organic acids in urine CTyMRl or MRS of brain... 

Trifluoroacetic acid is volatile, and thus readily removed. This acid was used by Albersheim and coworkers for the hydrolysis of plant cell-walls,39 and has since been employed for cell walls,40-43 plant mucilages,44 blood-group oligosaccharides,45 peptidogalactoman-nans,46 heparin,47 and disaccharides in blood and urine.48,49 It has also been suggested as an alternative to 6 M hydrochloric acid in the determination of amino sugars,50 and for the hydrolysis of polyalcohols produced by periodate oxidation of polysaccharides.503 Lee... 

C13. Christensen, P. J., Date, J. W., Schoenheyder, F., and Volqvartz, K., Amino-acids in blood plasma and urine during pregnancy. Scand. J. Clin, b Lab. Invest. 9, 54-61 (1957). 

If the history, physical findings, and laboratory results are suggestive but not conclusive of a particular mitochondrial disease (e.g., MELAS), then a second tier of tests is performed. These include blood and CSF lactate and pyruvate, as well as the lactate/pyruvate ratio timed or random measurement of amino acids in blood, urine, and CSF organic acids in urine and CSF and ketones and free and total carnitine in blood and urine. 

Levels of Other Amino Acids in Blood, Cerebrospinal Fluid, and Urine... 

Cal Kulis and other patients with cystinuria have a genetically determined defect in the transport of cystine and the basic amino acids, lysine, arginine, and ornithine, across the brush-border membranes of cells in both their small intestine and renal tubules. However, they do not appear to have any symptoms of amino acid deficiency, in part because the amino acids cysteine (which is oxidized in blood and urine to form the disulfide cystine) and arginine can be synthesized in the body (i.e., they are "nonessential" amino acids). Ornithine (an amino acid that is not found in proteins but serves as an intermediate of the urea cycle) can also be synthesized. The most serious problem for these patients is the insolubility of cystine, which can form kidney stones that may lodge in the ureter, causing bleeding and severe pain. 

Several examples of the applications of polarography in these fields have been already mentioned in Chapters VI and VII, viz. determinations of benzene, toluene, naphthalene and phenols in the atmosphere, breath, blood or urine, of amino acids (with particular interest to tyrosine, tryptophane, phenylalanine, histidine and histamine), of ketoacids, ketosteroids, carbon disulphide in air and blood, ethanol, acetoin, sugars and morphine in blood, of lactic acid, mandelic acid in bile and urine, adrenaline and thyroxine in iodinated proteins and last, but not least, of thiol compounds, both soluble and bound in biological materials. A few further examples will be given here. 

Amino acid determination in blood and urine may be helpful. Alanine is increased in many patients with a mitochondrial disorder (see above). Deficiency of E3 complex leads to branched-chain amino acid elevation. Severe generalised amino aciduria associated with DeToni-Fanconi-Debrd tubulopathy may indicate a respiratory chain defect. 

Although not strictly necessary, it is worthwhile to establish the lactate concentration in blood and urine, the organic acids in urine and the amino acids in serum, urine and CSR (for follow-up, therapy, tissue specificity). Determine pyruvate carboxylase activity. CT, computed tomography MRI, magnetic resonance imaging MRS, magnetic resonance spectroscopy... 

Another area of clinical interest which has benefited from the use of BCD is the study of tryptophan metabolism. Tryptophan is an essential amino acid which can be metabolized in a number of ways as illustrated in Figure 3. One of the minor pathways leads to the synthesis of the neurotransmitter 5-hydroxytryptamine (5HT), abnormal brain levels of which have been associated with a number of diseases including Down s syndrome[15] and depression [lb] As part of a study into the biochemistry of depressive illnesses, I investigated methods for the determination of tryptophan metabolites in blood and urine. HPLC proved to be a useful technique for separating these compounds, so the possibility of using BCD was examined [17]. 

An amino acid found in elevated amounts in blood and urine in the inborn errors of metabolism, non ketotic hyperglycinaemia, (which is possibly due to a deficiency in the enzyme glycine decarboxylase) and propionic acidaemia (ketotic hyperglycinaemia). It is also found in increased amounts in urine along with proline and hydroxyproline in another inborn error, familial iminoglycinuria. This is due to defective membrane transport of these amino acids. 

EtgPbS Anal. detn. in blood and urine by spectrophotometry Comparative toxicity Effect on amino acid metabolism Effect on porphyrin metabolism in vitro 756 98 99 176I+... 

Table 2.1.9 Changes of blood amino acids in various primary inherited defects and as a result of secondary changes. ASA Argininosuccinic acid, CPS carbamoyl phosphate synthase, LPI Lysinuric protein intolerance, MAD multiple acyl-CoA dehydrogenation, MSUD maple syrup urine disease, NAGS N-acetylglutamate synthase, NKH nonketotic hyperglycinemia, NTBC 2-(2-nitro-4-3 trifluoro-methylbenzoyl)-1,3-cyclohexanedione, OCT Ornithine carbamoyltransferase,...

When Rinaldo analyzed Ryan s blood serum, he found high concentrations of methylmalonic acid, a breakdown product of the branched-chain amino acids isoleucine and valine, which accumulates in MMA patients because the enzyme that should convert it to the next product in the metabolic pathway is defective. And particularly telling, he says, the child s blood and urine contained massive amounts of ketones, another metabolic consequence of the disease. Like Shoemaker, he did not find any ethylene glycol in a sample of the baby s bodily fluids. The bottle couldn t be tested, since it had mysteriously disappeared. Ri-naldo s analyses convinced him that Ryan had died from MMA, but how to account for the results from two labs, indicating that the boy had ethylene glycol in his blood Could they both be wrong ... 

According to a long-used classification amino acids are ketogenic if (like leucine) they are converted to acetyl-CoA (or acetyl-CoA and acetoacetate). When fed to a starved animal, ketogenic amino acids cause an increased concentration of acetoacetate and other ketone bodies in the blood and urine. On the other hand, glucogenic amino acids such as valine, when... 

For example, alkaponuria is characterized by homogentisic acid in urine phenylketonuria, which results in mental retardation, is characterized by quantities of phenylpyruvic acid in the urine. It is diagnosed in a suspected patient by determining the amount of this acid in the urine and the increased levels of phenylalanine in the plasma. Maple sugar disease is diagnosed the presence of large amounts of the branched chain amino acids, such as valine, leucine, and isoleucine in the blood and urine. 

In summary we underline the fact that as far as urine analysis is concerned, and this is also true for blood, the most satisfactory results published so far are those obtained with Moore and Stein s 1954 procedure (see (b) Dowex 50-X4 columns) whereas the two latest improvements in technique open the way to much wider investigation in this field of biochemical and medical research. The technique is also applicable for the determination of a single amino acid, adequate shortcuts and simplifications in the procedure being introduced accordingly. As examples, we shall mention that appropriate rapid operations have been described for the separation on ion exchange columns and subsequent determination of (3-alanine (C20), (3-aminoisobutyric acid (E5) or y-aminobutyric acid (W1). Similar adjustments may also be made for other amino acids, such as the basic amino acids, for instance, with Moore and Stein s 1954 procedure (M15). 

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