Normal Amino Acid Levels Research Articles

The Elusive Urea Cycle Disorders in the Adult Population: A Case of a 20-year-old Male Presenting With Post-Prandial “Fogginess”

Urea cycle disorders (UCDs) are rare inborn errors of metabolism that typically present in newborns. The prevalence is 1 in 10,000 births, with ornithine transcarbamylase (OTC) deficiency being the most common. In very rare cases, initial symptoms may present after age 6, often the result of a partial enzyme deficiency. Herein, we describe a case of a UCD in a gentleman at the age of 20. A 20 yo male with no medical history presented with intermittent post-prandial “fogginess” associated with diarrhea after eating specific types of foods. Initial lab testing, including electrolytes, glucose, kidney function and liver function testing was normal followed by negative stool studies including ova and parasites, giardia antigen, and culture. He was trialed on various restrictive diets limiting carbohydrates, dairy, and gluten. A low-protein, gluten-free diet provided the largest relief in symptoms. EGD demonstrated eosinophilic esophagitis for which he was started on a proton-pump inhibitor. Duodenal biopsy was negative for celiac disease and gastric biopsy was negative for H. pylori. An ammonia level obtained during an episode of cognitive dysfunction was elevated at 116 for which he was started on lactulose. Hepatitis serologies were negative. In the setting of his vague constellation of symptoms as well as hyperammonemia, serum amino acids were obtained and found to be relatively normal. Dysfunction of the urea cycle will foster an increased level of ammonia. Hyperammonemia causes vague clinical symptoms including nausea, diarrhea, fatigue, and cognitive dysfunction as we saw in our clinical case. Hyperammonemia can result from primary or secondary etiologies. Secondary causes include liver disease and gastrointestinal bleeding, which were not present in our case. Primary causes are further divided by the serum pH. Acidosis suggests fatty acid metabolic disorders whereas normal pH or alkalosis with normoglycemia, suggest urea cycle disorders. Plasma amino acid levels and genetic testing can then delineate which urea cycle disorder is present. With normal amino acid levels in our case, the differential includes OTC deficiency, carbamoyl phosphate synthetase deficiency, and N-acetyl glutamate synthetase deficiency. Though very rare in the adult population, UCDs should be considered in cases of vague gastrointestinal complaints and otherwise unexplained hyperammonemia.

Contrasting plasma free amino acid patterns in elite athletes: association with fatigue and infection.

AIM: There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis...

Determination of amino acids in human cerebrospinal fluid by gas chromatography

AbstractIn the present study, the use of gas chromatography (GC) for the determination of amino acids in human cerebrospinal fluid (CSF) is described. Although some amino acids may be determined using a packed column following the removal of glucose, the major interfering component, the inadequate resolution of other amino acids from remaining unidentified components results in poor quantitation. The use of wide bore columns improves reproducibility considerably, but still it does not provide sufficient resolution to enable quantitative determination of all amino acids in human CSF. Good reproducibility data, with CV values for all amino acids of 7% or less and recoveries generally between 80% and 100%, can only be obtained using the fused silica open tubular (FSOT) column. Normal amino acid levels are presented for 10 samples of human CSF, which compare well with data previously reported in the literature.

Amino acid and hormonal control of macromolecular turnover in perfused rat liver. Evidence for selective autophagy.

The control of RNA degradation by amino acids, insulin, and glucagon was investigated in perfused livers of fed rats previously labeled in vivo with [6-14C] orotic acid; rates were determined from the release of [14C]cytidine in the presence of 0.5 mM cytidine to suppress reutilization. Studies with cyclically perfused livers showed that plasma amino acids at 10 times (10X) normal concentrations inhibited RNA breakdown by 85%. Similar inhibition was obtained with a known regulatory amino acid mixture (Leu, Met, Pro, Trp, and His), whereas leucine alone (0.8 mM) decreased degradation by 47%. Perfusions carried out in the single-pass mode with graded levels of plasma amino acids revealed that the acceleration of RNA degradation over the full range of amino acid deprivation (0 to 10X normal levels) was the same as that for protein breakdown (3.19 and 3.15% h-1, respectively), and both were equally suppressed by insulin (2.4 micrograms h-1). Glucagon (10 micrograms h-1), though, was far less effective in stimulating RNA than protein turnover. A direct comparison of the two dose responses revealed a strong dissociation at 1 and 2 times normal amino acid levels. These findings support the notion that RNA and protein are degraded within a single macroautophagic compartment during amino acid and insulin deprivation. Glucagon, however, appeared to induce a second pathway in which the proportion of sequestered RNA to protein was selectively reduced. Electron micrographs showed that the ratio of vacuoles containing rough as compared with smooth endoplasmic reticulum was decreased by nearly 80% under these conditions.

Effect of Dietary Amino Acid Level, Folic Acid, Glycine, and Serine on Chick Performance and Blood Parameters

Studies of the interrelationships between dietary amino acid level, folic acid, glycine, and serine in chicks fed crystalline amino acid diets indicated that a folic acid deficiency exerted a greater detrimental effect on chick growth than did a deficiency of glycine and serine. The increased chick growth observed when a folic acid deficient diet containing normal levels of amino acids was supplemented with glycine and serine suggested that these amino acids were exerting a folic acid sparing effect. A similar sparing effect was not noted when the diet contained a high level of dietary amino acids which resulted in increased uric acid synthesis. Blood hemoglobin levels appeared to be influenced by a combination of factors including dietary folic acid and glycine levels and possibly growth rate of the chicks. Plasma glycine and serine concentrations were closely associated with the presence or absence of these amino acids in the diet and the level of the other amino acids in the diet. Within groups receiving the same level of dietary glycine and serine, lower plasma glycine was associated with higher levels of plasma uric acid.

Relative Utilization of Serine and Glycine by Chicks

Studies were conducted on the relative utilization of glycine and serine by chicks fed basal crystalline amino acid diets devoid of these amino acids. The crystalline amino acid mixture was fed at one and three times the requirement levels, thereby stimulating uric acid synthesis at differing rates. In addition, 5% l-glutamine replaced l-glutamic acid on an isonitrogenous basis in three diets containing normal levels of amino acids in the second study. Chicks fed diets devoid of glycine and serine grew less rapidly and less efficiently than chicks fed diets containing either serine or glycine plus serine. These decreases were roughly the same whether the diet contained normal or high levels of amino acids. Serine was as efficient as glycine in supporting chick growth and feed efficiency regardless of whether diets containing normal or high levels of amino acids were fed. Chicks fed diets containing high levels of amino acids grew approximately 81% as rapidly, but 24% more efficiently, than chicks fed normal levels of amino acids, and excreted approximately twice the amount of uric acid per gram of nitrogen consumed. In spite of increased uric acid excretion by chicks fed the high amino acid diets, the dietary void in glycine and serine was no more detrimental to chick growth or feed efficiency than that noted when normal levels of amino acids were fed. Feeding 5% l-glutamine rather than l-glutamic acid in the diet containing normal levels of amino acids had little effect on weight gain, feed efficiency or uric acid excretion. The absence of cystine from the amino acid mixture used in the third study did not have a marked influence on the relative utilization of glycine and serine by the chick.

Aminoaciduria in epilepsy

Summary Amino acid chromatograms of serum and urine were obtained from patients with epilepsy and encephalitis before, during, and after convulsions and were compared with those of normal children. Increased aminoaciduria with normal levels of amino acids in the serum was observed in 13 of 16 patients during periods of active convulsions and appears to be related to the severity of the seizures.

Seminal amino acid and carbohydrate pattern of bulls with normal and abnormal testes function.

Summary1. Methods of characterization and estimation by paper partition chromatography of carbohydrates and free amino acids in semen and accessory sex organ fluids of the bull are described. 2. Fructose was the only sugar found in semen and in fluids expressed from the accessory sex glands. The measurement by paper chromatography agrees well with the results of chemical methods. 3. The live amino acids found in free form in semen were glutamic acid, alanine, glycine, serine, and aspartic acid. They are apparently not utilized by spermatozoa during the process of fructolysis. 4. This pattern was similar in fluids obtained from seminal vesicles and the ampullae vasa deferentia except that alanine, not glutamic acid, was predominant. A trace of tyrosine was found in ampullar fluid. 5. Seminal fructose and amino acids were completely lost after castration. While testosterone therapy caused a rapid return of seminal fructose, the normal levels of amino acids were only partially restored. 6. Vasectomy, contrar...