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Results for “Xanthopterin”

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At least 109 records · Page 6Linked to original sources
PubMed1996

Tetrahydrobiopterin loading test in xanthine dehydrogenase and molybdenum cofactor deficiencies.

The objectives of this study were to find additional diagnostic information for the evaluation of xanthine dehydrogenase deficiency and molybdenum cofactor deficiency. Patients were given an oral loading test with 10 mg/kg 5,6,7,8-tetrahydrobiopterin. Urine excretion of pterin and isoxanthopterin was measured by HPLC. Control subjects had a fairly constant ratio of urinary pterin/isoxanthopterin before (0.57-5.32) and after (0.55-4.55) 5,6,7,8-tetrahydrobiopterin loading. These ratios were increased to 33 and 22 in a patient with hereditary xanthinuria and to 570 and 8030 in a patient with molybdenum cofactor deficiency. Obligate heterozygotes had an entirely normal test result. Evidence was obtained for the in vivo involvement of xanthine dehydrogenase in the conversion of pterin to isoxanthopterin. This test could be a sensitive marker for the establishment of residual enzyme activity.

Administration, Oral↗
PubMed1981

Pterin metabolism in normal subjects and hyperphenylalaninaemic patients.

The application of high performance liquid chromatography to the estimation of urinary pterins is illustrated by results from normal subjects and from patients with phenylketonuria, dihydropteridine reductase deficiency and biopterin synthetase deficiency. In normal subjects following a phenylalanine load the is a temporary increase in pterin elimination, the pattern being different to that seen in chronic hyperphenylalaninaemia.

Adult↗
PubMed1979

Urinary dihydroxanthopterin in the diagnosis of malignant hyperphenylalaninemia and phenylketonuria.

Assessment of urinary dihydroxanthopterin is proposed as a simple method of recognition of patients with malignant hyperphenylalaninemia (MHPA). High levels of urinary dihydroxanthopterin are found in untreated patients with phenylketonuria (PKU) or with dihydropteridine reductase (DHPR) deficiency. After dietary control of the serum phenylalanine level in PKU, the urinary dihydroxanthopterin falls to near normal levels. In DHPR deficiency urinary dihydroxanthopterin levels are high even when serum phenylalanine levels are in the range achieved on dietary treatment. Low levels would be expected in patients with defects in tetrahydrobiopterin synthesis even before dietary treatment. Confirmation of the diagnosis of different forms of MHPA then requires more detailed studies, but dietary treatment of other PKU patients can proceed with confidence.

Biopterins↗
PubMed1994

Antenatal diagnosis of tetrahydrobiopterin deficiency by quantification of pterins in amniotic fluid and enzyme activity in fetal and extrafetal tissue.

Prenatal diagnosis of tetrahydrobiopterin (BH4) deficiency was undertaken by evaluating the pterin patterns in amniotic fluid and the specific enzyme activities in fetal or extrafetal tissues. This allowed the prenatal diagnosis in 19 pregnancies at risk. In 8 families with a child already affected by dihydropteridine reductase deficiency 4 fetuses were diagnosed as homozygotes and 4 as heterozygotes for the defect. In 11 families with a child affected by 6-pyruvoyl tetrahydropterin synthase deficiency 4 fetuses were homozygous, 4 heterozygous and 3 normal. This study also advanced our knowledge of tetrahydrobiopterin metabolism during fetal development. The key enzymes involved in the biosynthesis of BH4 are expressed early and allow the fetus to be autotrophous for its cofactor requirement. In a twin pregnancy, both fetuses were diagnosed to be heterozygotes for dihydropteridine reductase deficiency and primapterin (7-biopterin) in amniotic fluid was increased. This indicates that pterin-4 alpha-carbinolamine dehydratase activity seems to be differently expressed during fetal life. As a consequence, pterins detected in amniotic fluid are of fetal origin and 6- and 7-substituted pterins can be present in amniotic fluid in higher proportions when compared with other body fluids.

Alcohol Oxidoreductases↗