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Results for “PHENYLPYRUVIC ACID”

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At least 343 records · Page 19Linked to original sources
PubMed1972

Aromatic acids derived from phenylalanine in the tissues of rats with experimentally induced phenylketonuria-like characteristics.

1. Aromatic acids were extracted from brain and liver of rats with phenylketonuria-like characteristics produced by administration of phenylalanine, either alone or in combination with p-chlorophenylalanine. The metabolism of the aromatic acids in these tissues was measured by gas chromatography. 2. At 1h after an intraperitoneal injection of l-phenylalanine (1g/kg) in 23-day-old rats, the phenyl-lactate concentration was 2.2mug/g in the liver and 0.43mug/g in the brain, and the concentration of o-hydroxyphenylacetate was 0.26mug/g in the liver. 3. Phenylacetate concentrations in brain and liver were 0.26 and 0.14mug/g respectively. 4. Suckling rats produced phenyl-lactate less rapidly than weanling rats, but accumulated higher concentrations in longer-term experiments. 5. Intraperitoneal injections of phenyl-lactic acid showed that this compound could directly penetrate the blood-brain barrier, and could produce similar brain/liver ratios of phenyllactate to those found after phenylalanine injection. 6. Qualitative and quantitative similarities in urinary excretion of aromatic acids between the rats used in this study and human patients with uncontrolled phenylketonuria indicate that a patient with a circulating phenylalanine concentration of the order of those achieved in the experimental animal may have aromatic acid concentrations in brain and liver comparable with those found in the rats used in the present study.

Animals↗
PubMed1981

Alternate mechanism for amino acid entry into Neurospora crassa: extracellular deamination and subsequent keto acid transport.

The growth of the pm nbg mutant strain of Neurospora crassa was inhibited by the amino acid analog para-fluorophenylalanine despite the fact that none of the three constitutive amino acid permeases is functional in this strain. This observation led to the detection of both a deaminase which was released into the growth medium in response to para-fluorophenylalanine and a keto acid transport system which allowed entry of the resulting keto acid into the cell. The transported keto acid was recovered in cellular protein, suggesting its regeneration as the amino acid. The cooperative activity of these two systems represents an additional mechanism for the intracellular accumulation of amino acids, which is distinct from the known amino acid permeases.

Amino Acids↗
PubMed1977

Metabolic studies on two patients with nonhepatic tyrosinemia using deuterated tyrosine loads.

Metabolic studies on two patients with defects in the tyrosine oxidation pathway are reported. Serum tyrosine was greatly elevated in both patients (1.37 and 1.52 mmol/liter, respectively) and both excreted large quantities of p-hydroxyphenylacetic acid, p-hydroxyphenyllactic acid, and p-hydroxyphenylpyruvic acid. Deuterated tyrosine loads were administered to both patients, before and after lowering of the serum tyrosine concentration by dietary treatment, and to a normal adult control subject. In one patient the excretion of the deuterated (D2)-tyrosine load was more than 300 times that found in the control subject whether the test was done at high or low serum tyrosine level and the pattern of metabolites indicated a persistent defect in p-hydroxyphenylpyruvic acid oxidase. Enzyme assays on needle liver biopsy supported this finding. In the second patient excretion of the D2 label was 300 times that of the control at high serum tyrosine levels, but only 5 times normal at low serum tyrosine levels. This finding was interpreted as indicating substrate inhibition of p-hydroxyphenylpyruvic acid oxidase. The primary defect has not been established in this patient, but the findings are compatible with a defect in hepatic-soluble tyrosine aminotransferase.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed1977

[Characteristics of tyrosine balance and oxidation in oligophrenia of different origin].

The author conducted a study of the tyrosine balance and the urine excretion of its metabolites: paraoxyphenylpyruvic and homogentistic acid in 39 oligophrenic patients of a nontypical and of 90 with an exogenous genesis. In exogenic forms of oligophrenia the oxidation of tyrosine was characterized by hypertyrosinemia, hypertyrosinuria, a drop of paraoxyphenylpyruvic acid excretion. In genotypical oligophrenia the most typical were high indices of tyrosinemia, tyrosinuria, excretion of paraphenylpyruvic acid and homogentistic acid.

Adolescent↗
PubMed1990

Examination of urine metabolites in the newborn period and during protein loading tests at 6 months of age--Part 1.

In the course of the collaborative study of children treated for PKU, urine samples from a total of 165 patients were analysed at six different times: in the newborn period before onset of therapy, after beginning of dietary management, during and immediately after a protein loading test at 6 months of age. In 95.9% of newborns with elevated Phe levels in plasma, metabolites of this amino acid as well as of Tyr could be detected. Of all metabolites phenylpyruvate always showed the highest concentration, followed by phenyllactate and o-hydroxy-phenylacetate. During the protein loading test an increase of the same metabolites occurred. At the age of 6 months the percentage of p-hydroxylated compounds related to the sum of all metabolites was lower than in the newborn period. Comparing the results of urine analyses at 6 months of age after the protein loading tests with the classification of HPA into the reaction types I-III, it can be clearly stated that patients with the milder forms II and III have already lower levels of Phe metabolites in urine before onset of therapy compared to the reaction type I. In retrospect 52% of the newborns could therefore be classified as reaction type I even before beginning of dietary management. The analysis of urinary Phe metabolites before the onset of therapy therefore provides sufficient information about the reaction type.

Creatinine↗
PubMed1997

Weak organic acid uptake in rat renal tubules in vitro: stimulation by pent-4-enoic acid.

A hypoglycemic agent, pent-4-enoic acid (4-PA; 0.1-1.0 mM), stimulated baseline uptake of a weak organic anion, fluorescein, in superficial proximal tubules of rat kidney and inhibited the rate of glucose production from pyruvate (but not lactate or endogenous substrates) by rat renal cortex fragment suspension. The stimulation of the fluorescein uptake was not observed in a low Na+ medium. Maleate (0.1-1.0 mM) and Cd2+ (0.1 mM), known similarly to 4-PA to induce the renal Fanconi syndrome, also stimulated the fluorescein uptake in the Na-dependent manner. Both 4-PA and Cd2+ and maleate elevated intracellular content of alpha-ketoglutarate and increased ammonia formation from endogenous substrates in the suspension of the rat renal cortex fragments. The stimulatory effects of 4-PA, maleate and Cd2+ on the fluorescein uptake were markedly attenuated by LiCl (5 mM), suggesting that the Na-coupled re-uptake of alpha-ketoglutarate is involved in energization of the fluorescein uptake in the exchange for the cytoplasmic dicarboxylate.

Animals↗