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Biomedical subjects

J O Sass

Publications and source records attributed to J O Sass.

At least 19 recordsLinked to original sources
PubMed2005

Possible genotype-phenotype correlations in children with mild clinical course of Canavan disease.

Canavan disease is characterised as a rare, neurodegenerative disease that usually causes death in early childhood. It is an autosomal recessive disorder due to an aspartoacylase (ASPA) deficiency. The causative gene has been mapped to chromosome 17 pter-p13. Here we describe three affected children from two Greek families with an unusually mild course of Canavan disease. All children presented with muscular hypotonia and macrocephaly. Diagnosis was based on elevated N-acetylaspartate in urine, reduced aspartoacylase activity in fibroblasts, and marked white matter changes on cerebral imaging. All three affected individuals exhibited continuous psychomotor development without any regression. Genetic analyses revealed compound heterozygous mutations (Y288 C; F295 S) in two individuals. The Y288 C variant was previously described in a child with macrocephaly, mild developmental delay, increased signal intensity in the basal ganglia, partial cortical blindness and retinitis pigmentosa, and slightly elevated N-acetylaspartate in the urine. Demonstration of the same variant in two unusually mildly affected Canavan disease patients and absence of this variant in 154 control chromosomes suggest a possible pathogenic role in mild Canavan disease. In the third individual, two homozygous sequence variants were identified, which comprise the known G274R mutation and a novel K213E variant.

Adolescent↗
PubMed2004

Trichothiodystrophy: quantification of cysteine in human hair and nails by application of sodium azide-dependent oxidation to cysteic acid.

The term "trichothiodystrophy" (TTD) covers several autosomal recessive diseases whose diagnostic hallmark is short, brittle hair low in sulfur and cystine because of impaired synthesis of high-sulfur matrix protein. Clinical symptoms associated with TTD represent a variable range of abnormalities in organs derived from ectoderm and neuroectoderm. Important laboratory tests of the hair for the diagnosis of TTD comprise polarizing microscopy ("tiger-tail" pattern), electron microscopy, and amino acids analysis of hydrolyzed hair with a special focus on cystine. However, only very few institutions determine the amino acid composition of human hair and nail clippings, which requires special sample preparation including hydrolysis. If no special precautions are taken, quantification of cysteine and cystine becomes inaccurate because of decomposition of these residues during hydrolysis. We therefore performed the sample work-up with azide-dependent oxidation which we have for the first time adapted for analysis of hair and nail clippings. With our control and parent data resembling published data on hair and nail samples, we obtained a decreased proportion of cysteine (half cystine, determined as cysteic acid) in materials obtained from a boy with TTD. Clearly, the method for the quantification of cysteine following sodium azide-dependent oxidation is a suitable and rather convenient approach to the quantification of cyst(e)ine and other amino acids in hair and nail proteins, and is a valuable contribution to the diagnosis of TTD.

Cysteic Acid↗
PubMed2004

Isobutyryl-CoA dehydrogenase deficiency: isobutyrylglycinuria and ACAD8 gene mutations in two infants.

Isobutyryl-CoA dehydrogenase (IBD) is an enzyme involved in the catabolism of the branched-chain amino acid valine. We report a third and a fourth child with IBD deficiency who were both detected during newborn screening with tandem mass spectrometry and so far do not receive any treatment. The diagnosis was confirmed by biochemical and molecular studies. One of the children is homozygous for the mutation M128I in the ACAD8 gene, which is predicted to affect the substrate binding cavity. The other child is compound heterozygous for a frameshift mutation F33fsins and a missense mutation V203I. It is as yet uncertain whether IBD deficiency may cause significant morbidity in affected children and whether treatment is necessary. In view of the limited experience worldwide, careful monitoring of the children is recommended.

Acyl-CoA Dehydrogenases↗
PubMed2001

Effects of all-trans-retinoic acid and all-trans-retinoyl glucuronide in two in vitro systems of distinct biological complexity.

In vitro systems are widely used to evaluate the embryotoxic potential of retinoids. The effective concentrations of these retinoids, however, are not consistent in the various in vitro systems used in evaluating embryotoxicity. This may be explained by the different level of complexity for each individual system, which may lead to different concentrations of the substances in the target tissues. To verify this hypothesis we have compared two in vitro systems of distinct biological complexity: the rat whole embryo culture system, and the mouse limb bud organ culture system. The lipid soluble, teratogenic retinoid all-trans-retinoic acid (ATRA), and all-trans-retinoyl-beta-D-glucuronide (ATRAG), an endogenous, water-soluble and biologically active retinoid with limited placental transfer, were compared with regard to their embryotoxic potential in vitro. In both in vitro systems, ATRAG showed a lower degree of embryotoxicity than ATRA. In the limb bud organ culture, ATRAG revealed only slightly less toxicity than ATRA, whereas the effective concentrations of the two compounds in the whole embryo culture system differed by almost two orders of magnitude. During incubation with ATRAG, ATRA is generated by hydrolysis and is found in culture media and exposed tissues. The presence of membrane barriers around the developing embryo in the whole embryo culture system possibly prevents the transfer of ATRAG to the embryo and, therefore, its exposure to the active hydrolysis product ATRA. From these results we conclude that analysis of retinoid concentrations in the culture media and in the exposed tissues is essential for the interpretation of results obtained from in vitro toxicity testing.

Animals↗
PubMed2000

Biological effects and metabolism of 9-cis-retinoic acid and its metabolite 9,13-di-cis-retinoic acid in HaCaT keratinocytes in vitro: comparison with all-trans-retinoic acid.

9-cis-Retinoic acid (9cRA), a geometric isomer of all-trans-retinoic acid (atRA), is an endogenous high-affinity ligand for retinoid X receptors and retinoic acid receptors activating them with high potency. 9,13-di-cis-Retinoic acid (9,13dcRA) has been described as a major plasma metabolite of 9cRA. In this study, the biological activity and the metabolism of 9cRA and 9,13dcRA were investigated and compared with those of atRA in a retinol-free culture system of HaCaT keratinocytes. 9cRA exhibited a slightly weaker activity overall than atRA in inhibiting cell proliferation, inducing cellular retinoic acid binding protein II (CRABP II) mRNA levels and upregulating cytokeratin 19 expression. 9,13dcRA regulated HaCaT keratinocyte activity only at the highest concentration tested (10(-6) M). In cultures of HaCaT keratinocytes with atRA and 9cRA, rapid intracellular accumulation of atRA was observed within 2 h, and atRA levels were higher with atRA treatment than with 9cRA treatment. 9,13dcRA remained relatively stable in the medium with intracellular 9,13dcRA levels below the level of detection. Taken together, 9cRA seems to be slightly less potent than atRA in regulating the biological activity of HaCaT keratinocytes, while its metabolite 9,13dcRA is effectively inactive at biologically relevant concentrations. Our data suggest a prodrug/drug relationship between 9cRA and atRA in human keratinocytes. 9,13dcRA seems to be a weaker prodrug of atRA or an inactive metabolic derivative.

Alitretinoin↗
PubMed2000

Elevated plasma bile acid concentrations in two sisters with tyrosinaemia type I.

A 21-month-old girl suffering from tyrosinaemia type I and undergoing treatment with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione (NTBC) presented with pruritus which rapidly ceased with administration of high doses of ursodeoxycholic acid. Determination of plasma bile acids revealed clearly elevated levels both in samples taken before and after the onset of NTBC therapy, thus indicating, that the increase was not related to the administration of this drug. This result is corroborated by data from the first patient's newborn sister, diagnosed with the same disease, who showed elevated plasma bile acid concentrations in all samples examined, except for the cord plasma. This is the first report on altered bile acid concentrations in tyrosinaemia type I, and underlines the need for thorough investigation of bile acid metabolism in this disease.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed2000

Paronychia with pyogenic granuloma in a child treated with indinavir: the retinoid-mediated side effect theory revisited.

BACKGROUND: The introduction of HIV-1 protease inhibitors into the treatment of patients infected with HIV-1 has had a major influence on clinical practice. However, the use of protease inhibitors is frequently associated with the development of resistance and several side effects and interactions with other drugs have been reported. OBSERVATIONS: We present the first pediatric patient with paronychia with pyogenic granuloma associated with the administration of the protease inhibitor indinavir. Clinical findings are discussed in view of a possible interference of indinavir with endogenous retinoid metabolism. CONCLUSION: Considerable evidence advocates the mediation of indinavir side effects by impaired oxidative metabolism of retinoic acid through the inhibition of cytochromes P450 3A by indinavir rather than by impaired formation of 9-cis-retinoic acid.

Adolescent↗
PubMed1999

Spectrum of CFTR mutations in the Middle North of Spain and identification of a novel mutation (1341G-->A). Mutation in brief no. 252. Online.

We have analyzed 39 unrelated cystic fibrosis (CF) families by denaturing gradient gel electrophoresis (DGGE) and direct sequencing in order to determine the spectrum of CF mutations in our population. This approach has allowed us to detect 72 out of the 78 CF chromosomes (92.3%). The DF508 mutation was found to be present in 51/78 (65.4%) CF chromosomes, in accordance with the predicted Northwest-Southeast gradient within the European population. Another 14 known mutations, and the novel 1341G-->A mutation were identified. Nine out of fifteen non DF508 mutations were present in a single chromosome. The 1341G-->A mutation, found in 2 unrelated patients, is a new mutation associated to severe phenotype, causing pancreatic insufficiency and chronic lung infections. Our data suggest a different distribution of non-DF508 mutations in our population when compared with previous studies carried out in Spanish CF families. Six out of the 14 non-F508 in our study were not present in a recent study carried out in 640 Spanish families with CE These six mutations account for 29.6% non DF508 chromosomes in our sample.

Cystic Fibrosis↗
PubMed1999

Plasma concentrations and renal clearance of orotic acid in argininosuccinic acid synthetase deficiency.

Argininosuccinic acid synthetase deficiency (ASD) is a rare disorder of urea cycle metabolism, with pronounced citrullinemia and orotic aciduria being characteristic biochemical features. To further investigate the role of plasma orotic acid and its possible use for monitoring the metabolic status in ASD, we determined plasma orotic acid, amino acid, and ammonium levels in plasma samples collected over a period of 3 years from a patient who is now 8 years of age. Orotic acid plasma concentrations varied widely from less than 1 micromol/l to more than 60 micromol/l. The renal clearance of orotic acid was eightfold the glomerular filtration rate, thus supporting an active mechanism underlying the excretion of this pyrimidine. Data obtained during a metabolic crisis yielded a statistically significant linear correlation of orotic acid plasma levels with those of glutamine and ammonium, which are generally accepted for assessment of the successful treatment of this disorder. Our data revealed no advantage of plasma orotic acid concentrations over the established amino acids (glutamine and arginine) and ammonium for determining acute treatment responses. Since several effects of high levels of orotic acid have been described in mammals, further research is necessary to assess a possible contribution of orotic acid to the pathogenesis of ASD and the use of plasma orotic acid levels in the long-term monitoring of these patients.

Amino Acids↗