C. Van Der Heiden

Abnormal tyrosine and phenylalanine metabolism in patients with tyrosyluria and phenylketonuria; gas-liquid chromatographic analysis of urinary metabolites.

Abstract Gas-liquid chromatographic methods have been developed for the analysis of: urinary phenylalanine metabolites (I) in patients with phenylketonuria, tyrosine metabolites (II) in patients with a disturbed tyrosine metabolism at the level of p-hydroxyphenylpyruvate hydroxylase, and homogentisic acid in alkaptonuria. Metabolites I include: phenylpyruvic, -lactic, -acetic (free and conjugated), -mandelic, o-hydroxyphenylacetic and benzoic (free and conjugated) acids. Metabolites II include: p-hydroxyphenylpyruvic, -lactic, -acetic and p-hydroxymandelic acids. Urinary excretions of phenylalanine and its waste metabolites I in patients with phenylalanine hydroxylase deficiency, at high and moderate loads are given. In 3 patients with classical phenylketonuria the total excretion of phenylalanine and its waste metabolites were found to be 90, 81 and 82% of the phenylalanine intake. In 2 other patients, with a higher phenylalanine tolerance, 19 and 34% was found. The excretion intake ratio is proposed to be a better parameter for phenylalanine hydroxylation capacity than is plasma phenylalanine. Urinary excretions of tyrosine and its waste metabolites in 2 patients with (inherited) liver disease and tyrosyluria were studied and compared with the urinary findings in a patient who presumably had a primary p-hydroxyphenylpyruvate hydroxylase deficiency. In one of the patients with liver disease the excretion/load ratio was determined. It is suggested that this ratio is a better clinical parameter than is plasma tyrosine.

Gas chromatographic analysis of urinary tyrosine and phenylalanine metabolites in patients with gastrointestinal disorders.

Main urinary bacterial metabolites of phenylalanine (total benzoic and phenylacetic acids) and of tyrosine (total p-hydroxybenzoic acid and p-hydroxyphenylacetic acid) were determined by gas chromatography in controls and patients with cystic ubrosis of the pancreas, coeliac disease, intestinal resection and unclassified enteritis. In various patients, especially in the untreated coeliacs, high amounts of one or more of the abovementioned metabolites were found. In this paper results in controls and patients are presented and discussed.

Urinary and faecal excretion of metabolizes of tyrosine and phenylalanine in a patient with cystic fibrosis and severely impaired amino acid absorption

In a patient with severely impaired amino acid absorption and cystic fibrosis, the urinary excretion of metabolites of phenylalanine and tyrosine was found to be highly increased. Presumably, for the greater part, these metabolites are products of bacterial degradation of the amino acids in the intestinal lumen. The main urinary metabolites were phenylacetic (con j.+ free), benzoic (conj.+ free), p-hydroxyphenylacetic and p-hydroxybenzoic (conj.+ free) acids; the first two represent a considerable percentage of phenylalanine intake and the latter two that of tyrosine intake. Minor urinary metabolites, probably typical for tyrosine malabsorption, were p-hydroxyphenylpropionic and p-hydroxyphenylacrylic acids; the latter compound, however, occurs seldom or never. In the faeces were found small amounts of p-hydroxyphenylpropionic, p-hydroxyphenylacetic, p-hydroxybenzoic and p-hydroxyphenyllactic acids, all derived from tyrosine. Also small quantities of the phenylalanine metabolites phenylacetic and benzoic acid were present. Faecal excretion of the metabolites was clearly less than their urinary elimination. The analytical data obtained from urine and faeces indicate that the tyrosine ammonia-lyase pathway and possibly also the phenylalanine ammonia-lyase pathway are important metabolic routes of intestinal bacteria. The urinary excretion of phenyl acids and p-hydroxyphenyl acids may be an important parameter for phenylalanine and tyrosine malabsorption.

Automatic column chromatographic analysis of urinary and serum imidazoles in patients with histidinaemia and normals

A 412-h automatic column Chromatographic method for the analysis of imidazoles in patients with histidinaemia is reported. Imidazoles are separated on a cation exchanger by a gradient elution procedure. Continuous analysis of the column effluent is performed with a Technicon AutoAnalyzer using diazotized sulphanilic acid as a colour-producing reagent. The scope and the limits of the method are discussed and data for reproducibility and recoveries are given. Values for the urinary excretion of histidine, N-acetylhistidine, imidazolelactic acid, imidazolepvruvic acid and imidazoleacetic acid, together with the corresponding serum histidine concentrations have been determined in even patients with histidinaemia. Also the effect of a load with l-histidine in a patient treated with a diet low m histidine has been investigated. Quantitatively histidine and imidazolelactic acid are the most important excretory products and therefore are the most conclusive parameters for diagnosis when urine is analyzed. Also values for the urinary excretion of histidine, N-acetylhistidine, imidazolelactic acid and imidazoleacetic acid in normals are given. Increased urinary imidazoles in patients with diseases other than histidinaemia are commented upon.

Ring chromosome 2: Clinical, chromosomal, and biochemical aspects

SummaryA new case of ring chromosome 2 is described and compared with the five cases hitherto reported. The clinical picture includes a severe pre- and postnatal growth failure, microcephaly, psychomotor retardation, and some minor dysmorphic features. Cytogenetic studies revealed a ring 2 structure and aneuploidy. Banding analysis failed to demonstrate a substantial loss of chromosomal material. Enzymologic studies revealed a decrease of red cell acid phosphatase activity suggesting the localization of its gene in the 2p25→2pter region.

Some kinetic properties of liver ornithine carbamoyl transferase (oct) in a patient with oct deficiency

Some kinetic properties of liver OCT from a patient with OCT deficiency were studied. Contrary to controls, in which two pH optima were observed (pH 7.7 and pH 8.5), only the pH optimum of 8.5 could be demonstrated in our patient. From KM studies at pH 7.7 and pH 8.5, the most striking abnormalities in comparison with human controls were (a) a strongly increased KM (ornithine) at pH 7.7, but less pronounced at pH 8.5, (b) a higher VMAX at pH 8.5 compared with the VMAX at pH 7.7 and (c) the absence of substate inhibition at pH 8.5 to ornithine was elevated up to a concentration above approximately 1.5 mM.

Increased urinary imidazolepropionic acid, n-acetylhistamine and other imidazole compounds in patients with intestinal disorders

In 26 out of a large group of patients with gastrointestinal disorders abnormal urinary imidazole excretion patterns were found. Most frequently excessive or increased amounts of imidazolepropionic acid (ImPA) occurred, and as next N-acetylhistamine was excreted in excess. In a number of cases the latter was accompanied by a substance identified as N-propionylhistamine. It is suggested that these excretory products are bacterial metabolites of histidine, if not absorbed in the intestinal lumen. All 26 patients excreted increased amounts of bacterial metabolites of tyrosine and/or phenylalanine as well: p-OH-phenylacetic and/or p-OH-benzoic acids and phenylacetic and/or benzoic acids respectively. Many patients showed increased urinary 4-amino-5-imidazolecarboxamide, its riboside and an unknown related compound X, especially in a later (recovery) phase when imidazolepropionic acid and N-acetylhistamine already decreased. It is thought that these metabolites are not of bacterial origin.

Simultaneous occurrence of xanthine oxidase and sulfite oxidase deficiency. A molybdenum dependent inborn error of metabolism

In a 3-week old female child with clinical features including neurologic abnormalities and lens dislocation, xanthinuria co-existed with increased excretion of sulfur compounds (sulfite, S-sulfocysteine, taurine and thio-sulfate). Low xanthine oxidase and absent sulfite oxidase activities were found on liver biopsy. No abnormality was detected in either parent. Both the above enzymes are molybdenum-flavoproteins. Normal serum molybdenum concentration seemed to rule out dietary deficiency or impaired absorption. A defect in the incorporation of the metal into flavoproteins is postulated in this case.

Attempted dietary treatment of a boy with hyperammonemia due to ornithine transferase deficiency

Dietary treatment of a male patient suffering from the delayed-onset type of OCT deficiency was attempted. Control of the hyperammonemia was attempted by restriction of protein intake, guided by monitoring the plasma ammonia and regular checking of the serum amino acid levels. The influence of supplementary citric acid or lactulose therapy on the plasma ammonia level was investigated and found to be negligible. The therapeutic effect of supplying ornithine and arginine (an essential amino acid in urea cycle disorders) is described. Despite intensive dietary treatment over two and a half years, a incorrigible hyperammonemic crisis resulted in the sudden death of our patients.

Tyrosinemia and tyrosyluria in healthy prematures: Time courses not vitamin C-dependent

Tyrosyluria and for a part also tyrosinemia were studied in 60 healthy prematures of various birth weights and gestational ages. The first analyses were performed between the 6th and the 14th day after birth. A normal milk diet was given and the protein-intake was between 3 and 4 g/kg. After the first collection of urine half the patients received extra ascorbic acid, 100 mg/kg daily. Urinary analyses of tyrosine and p-hydroxyphenyl metabolites were performed once a week, until the excretion of p-hydroxyphenylpyruvic plus p-hydroxyphenyllactic acids was lower than 5 mmoles per gram creatinine. In 22 out of the 60 prematures (or 37%) a tyrosyluria of more than 5 mmoles/g creatinine and in 19 out of 44 (43%) patients analysed serum tyrosine was higher than 5 mg/100 ml at first analysis. No inverse correlation between tyrosyluria and tyrosinemia on the one hand and birth weight and gestational age on the other hand existed. But in children with a delayed intra-uterine development the incidence of tyrosyluria was higher as prematurity was more pronounced. Ascorbic acid had no effect on the rate of disappearance of tyrosyluria. It was concluded that the addition of extra vitamin C to the diet of prematures is not useful for the normalization of tyrosine metabolism.