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Biomedical subjects

D Rabier

Publications and source records attributed to D Rabier.

At least 127 records · Page 7Linked to original sources
PubMed1989

[Respiratory chain diseases in infancy. Clinical presentation and diagnosis].

Nineteen children with defects of the mitochondrial respiratory chain are described. First symptoms appeared during the first two years of their lives. Four types of clinical pictures were identified: 1/neonatal hypotonia. 2/cardiomyopathy. 3/progressive neurological deterioration. 4/multisystem disease. A study of pyruvate and fatty acids metabolism and a skeletal muscle biopsy were performed in all cases. Elevation of beta-hydroxybutyrate/acetoacetate and lactate were the most frequent biochemical abnormalities. Muscular biopsy in light microscopy showed in most cases abnormal lipid storage.

Biopsy↗
PubMed1988

[Cerebral edema with hyperammonemia in valpromide poisoning. Manifestation in an adult, of a partial deficit in type I carbamylphosphate synthetase].

A case of cerebral oedema developed during an apparently common attempted suicide with valpromide is reported. The most conspicuous biochemical abnormality was hyperammonaemia. The oedema proved refractory to the standard medical treatment of intracranial hypertension, and decompressive craniectomy was performed with only minor sequelae. The cerebral oedema cum hyperammonaemia syndrome led to the discovery, in this hitherto asymptomatic adult subject, of a 50 per cent deficiency in type a carbamyl phosphate synthetase liver activity. By completing such a deficiency, valproate may produce an extremely serious syndrome resembling the neonatal encephalopathy due to complete enzyme deficiencies in the urea cycle. All valpromide or valproate intoxications probably are cerebral oedemas with hyperammonaemia akin ti Reye's syndrome. All accidents of this type occurring during treatment or poisoning with valproate should be investigated for urea cycle enzyme abnormalities.

Adult↗
PubMed1988

Prenatal diagnosis of propionic acidemia in chorionic villi by direct assay of propionyl CoA carboxylase.

Prenatal diagnosis of propionic acidemia was achieved by the direct assay of propionyl CoA carboxylase in chorionic villi. The diagnosis was confirmed by determination of methylcitrate in amniotic fluid and measurement of propionyl CoA carboxylase in the liver from the abortion. Discrepancy between [14C]-propionate incorporation into protein of chorionic villi or cultured chorionic cells and propionyl CoA carboxylase activity is reported.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

Immunochemical analysis of nineteen ornithine transcarbamoylase deficiencies.

Western blot analysis of 19 human ornithine transcarbamoylase (OTC) deficiencies characterized by neonatal (13 patients: type I) or later onset of symptoms (6 patients: type II) are reported. All the patients studied here are hemizygous males. In the first group, most of the patients had no residual enzymatic activity (11 patients). In 8 cases this is correlated with a complete absence of protein, in 1 patient with a much reduced amount and in 2 others with 80% of an OTC-related protein of normal molecular weight. Only 2 patients with neonatal onset of symptoms had a detectable OTC activity which ranged from 0.5 to 1% of the control. Among the second clinical group of 6 patients with later onset of symptoms, the residual OTC activity was between 5 and 20% at pH 8.0; 3 of them had abnormal kinetics and 50% an OTC-related protein.

Humans↗
PubMed1988

[Genetic counseling in ornithine carbamoyltransferase deficiency].

Ornithine transcarbamylase (OTC) deficiency is an inborn error of urea cycle metabolism, responsible for lethal hyperammonemia in males and for severe symptoms in at least 20% of heterozygous females. The authors provide here additional data on the informativity of the protein loading test (PLT) for the detection of heterozygotes. They show that the risk of being a carrier for the mother of an affected boy falls from 2/3 a priori to only 1/8 if her PLT is negative. The risk for the mother of heterozygote girl falls from 1/2 a priori to 1/16 if her PLT is negative.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

[Prenatal diagnosis of enzymopathies of the urea cycle].

Seven defects of the urea cycle enzymes were obtained in 48 hours at-risk pregnancies. A new method for measuring ornithine transcarbamylase and carbamylphosphate synthetase-I was used for prenatal diagnosis of the related enzymopathies in chorionic villi.

Argininosuccinate Synthase↗
PubMed1986

Effects of organic acids on the synthesis of citrulline by intact rat liver mitochondria.

Citrulline synthesis, mostly regulated at the carbamoyl-phosphate synthase I (EC 6.3.4.16) step by the intramitochondrial concentration of ATP and/or N-acetylglutamate is tested with four organic acids: propionate, alpha-ketobutyrate, dipropyl-acetate and 4-pentenoate. In the presence of 10 mM succinate, as the oxidizable substrate, citrullinogenesis was only inhibited by propionate and 4-pentenoate. With 10 mM L-glutamate, a significant inhibition was observed with the four acids. After the addition of ATP and N-acetylglutamate to uncoupled mitochondria, no inhibition could be demonstrated with dipropylacetate and 4-pentenoate. However, a slight inhibition remained with propionate and alpha-ketobutyrate. When mitochondria were incubated with 10 mM L-glutamate, ATP decreased with propionate, dipropylacetate and 4-pentenoate. Under the same conditions, N-acetylglutamate synthesis was strongly inhibited by each organic acid. The decrease of N-acetylglutamate synthesis was related to the constant diminution of intramitochondrial acetyl-coenzyme A (CoA) and to the increase of propionyl-CoA with propionate and alpha-ketobutyrate. Acetyl-CoA and propionyl-CoA are respectively substrate and competitive inhibitor of the N-acetylglutamate synthase (EC 2.3.1.1). Each acid displayed its optimum inhibition at concentrations between 1 and 2 mM. At these acid concentrations, mitochondria had the lowest acetyl-CoA content and the highest propionyl-CoA content.

Acetyl Coenzyme A↗
PubMed1985

Impairment of citrulline synthesis during late pregnancy and lactation in rats.

Synthesis of citrulline by rat liver mitochondria was investigated during late pregnancy and early lactation. It was strongly decreased over all the period studied except during delivery, where a sudden rise was observed. The mitochondrial enzymes carbamoylphosphate synthetase I (ammonia) (EC 6.3.4.16) and ornithine carbamoyltransferase (EC 2.1.3.3) did not fall significantly during this period, although carbamoylphosphate synthetase I (ammonia) was slightly decreased antepartum. Citrulline synthesis was found significantly correlated to N-acetylglutamate concentration in mitochondria throughout the period considered. On the other hand, low levels of N-acetylglutamate could be explained by low activity of N-acetylglutamate synthase (EC 2.3.1.1).

Acetyltransferases↗
PubMed1985

Ornithine transcarbamylase and disaccharidase activities in damaged intestinal mucosa of children--diagnosis of hereditary ornithine transcarbamylase deficiency in mucosa.

Ornithine transcarbamylase (OTC) and disaccharidase activities were measured in the intestinal mucosa from 182 children. Sixty-nine had normal mucosa, whereas the others had different degrees of mucosal damage. Brush border disaccharidases are significantly decreased in all degrees of villous atrophy. In contrast, OTC is not affected in moderate atrophy and only slightly decreased in severe atrophy. Consequently, the OTC-to-lactase ratio increases with the degree of atrophy and permits discrimination between normal and damaged mucosa. The assay of OTC activity in intestinal mucosa for the diagnosis of hereditary deficiency in male hemizygote patients generally provides nonambiguously low results, whereas in heterozygote females the amount of residual activity is in the range of the results found in damaged mucosa.

Child↗