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Biomedical subjects

Y Nordmann

Publications and source records attributed to Y Nordmann.

At least 145 records · Page 8Linked to original sources
PubMed1981

The inherited enzymatic defect in porphyria variegata.

Protoporphyrinogen oxidase activity and ferrochelatase activity have been measured in blood lymphocytes from patients with prophyria variegata, and from some members of the family of one patient; the mean activity of protoporphyrinogen oxidase from patients was about 50% of that in lymphocytes from normal subjects; similar results were obtained from asymptomatic carriers in two generations of the patient's family. This finding confirms that a protoporphyrinogen oxidase decreased activity reflects the primary genetic defect in Porphyria Variegata. Data of ferrochelatase activity have been found usually in the normal range and these results are discussed.

Female↗
PubMed1981

Congenital erythropoietic porphyria (Günther's disease): enzymatic studies on two cases of late onset.

Cosynthetase was measured in hemolysates of two patients with CEP that appeared in adulthood. The level of cosynthetase activity was found to be very low (mean 18% of normal), ruling out the hypothesis of heterozygous cases. Several obligatory heterozygous carrier were also studied in whom cosynthetase activity was found to be intermediate (mean 46.66% of normal) between the levels of normal controls and homozygous patients whereas PBG deaminase was always normal. The nature of the metabolic abnormality is undoubtedly a primary defect of the cosynthetase activity; some cases of late onset emphasize the heterogeneity of the disease.

Adult↗
PubMed1981

[Hereditary porphyria cutanea in children. Enzymatic studies (author's transl)].

A girl of 7 years presenting porphyria cutanea tarda was found to have a very low level of erythrocytary uroporphyrinogen decarboxylase. Tests on her brother, parents and maternal grand-parents, who were all free of the disease revealed the same level of enzyme in the mother and grandmother, through whom the hereditary factor was obviously transmitted. This supports evidence provided by juvenile cases and familial forms in the literature that heredity plays an important part in a disease which is often considered to be acquired or symptomatic. Despite clinical and biological resemblances, two types of porphyria cutanea can be distinguished: a sporadic form in which enzyme deficiency occurs only in the liver and is revealed by exogenous toxic factors such as alcohol or oestrogens and an hereditary form where the deficiency transmitted by a dominant autosomal mode is found in all hemasynthetising cells.

Child↗
PubMed1980

Studies of porphyrin synthesis in fibroblasts of patients with congenital erythropoietic porphyria and one patient with homozygous coproporphyria.

Partial deficiencies in enzymes activity of the heme biosynthesis pathway have been demonstrated in cultured skin fibroblasts and other tissues from patients suffering from congenital erythropoietic porphyria and hereditary coproporphyria. Using a new fluorimetric method, we have assessed quantitatively porphyrin biosynthesis from added delta-aminolevulinic acid in cultured fibroblasts of two congenital erythropoietic porphyria patients and one homozygous case of hereditary corproporphyria. The results were compared with those of the patients' parents and those of normal controls. All the porphyrins synthesized remained within the cells of normal subjects and of patients with congenital erythropoietic porphyria; these porphyrins were mostly (95%) protoporphyrin. The fibroblasts of the patient with homozygous hereditary coproporphyria synthesized the same amount of porphyrins, but only 25% were found within the cells, whereas 75% were found in the medium. The porphyrins found within the cells were coproporphyrin (25%) and protoporphyrin (75%); in the medium, only coproporphyrin was identified.

Cells, Cultured↗
PubMed1980

Some kinetic properties of human red cell uroporphyrinogen decarboxylase.

Several kinetic properties of uroporphyrinogen decarboxylase (uroporphyrinogen-III carboxy-lyase, EC 4.1.1.37) from human hemoglobin-free hemolysates were studied, using substrates of both isomeric series I and III (uroporphyrinogen, hepta and pentacarboxyl porphyrinogens). Enzyme affinity for series II isomers was always found to be higher than for corresponding series I isomers. Mixed substrate experiments using porphyrinogen (both labelled with 14C and unlabelled) showed: (a) a reciprocal inhibition of decarboxylation of series III porphyrinogens by series I porphyrinogens with the same number of carboxylic groups; (b) no inhibition of hepta- and pentacarboxylic series III porphyrinogens decarboxylation by uroporphyrinogen III. It is demonstrated that porphyrinogens of both isomeric series with the same number of carboxylic groups are decarboxylated at the same active center; in contrast, the sequential decarboxylation of uroporphyrinogen III to coproporphyrinogen III occurs at four different active centers. Relationship between the kinetic properties of uroporphyrinogen decarboxylase and biological data of porphyria cutanea are discussed.

Carboxy-Lyases↗
PubMed1980

Prenatal exclusion of congenital erythropoietic porphyria (Günther's disease) in a fetus at risk.

Amniotic fluid porphyrins, biosynthesis of porphyrins by amniotic cells, and uroporphyrinogen III cosynthetase were studied after the 17th week of a pregnancy at risk for congenital erythropoietic porphyria (CEP). Only coproporphyrin was found in amniotic fluid. A diagnosis of CEP was ruled out by the demonstration of normal cosynthetase activity; biosynthesis of porphyrins was identical, not only in the porpositus and in control amniotic cells, but also in patients with CEP and in control skin fibroblasts.

Amniotic Fluid↗
PubMed1978

Familial and sporadic porphyria cutanea: two different diseases.

Uroporphyrinogen (URO) decarboxylase was measured in hemoglobin-free erythrocytes from subjects with familial porphyria cutanea: the mean activity was about 50% of that found in erythrocytes from normal subjects. Asymptomatic carriers were always found in the family. No enzyme deficiency was found in erythrocytes from subjects with sporadic porphyria cutanea. The measurement of URO decarboxylase in erythrocytes seems to allow an easy distinction between these two groups of porphyria cutanea.

Adolescent↗
PubMed1978

The mitochondrial localization of coproporphyrinogen III oxidase.

The location of coproporphyrinogen III oxidase in mitochondria was studied in rat liver by using the digitonin method or hypo-osmotic media for fractionation. The enzyme was found in the intermembrane space with a fraction loosely bound to the inner membrane. This fraction was released by washing the inner-membrane-matrix complex with alkaline solutions or solutions of high ionic strength. The enzyme in both fractions had the same Km (0.16 micrometer) for coproporphyrinogen III. When incubation was performed in a medium that avoided destruction of enzyme membrane binding, a dramatic increase in activity was observed after sonication of whole mitochondria or of the inner-membrane-matrix complex.

Animals↗
PubMed1977

[Demonstration of hereditary enzyme defect in coproporphyria].

We measured lymphocytes Coproporphyrinogen III Oxidase activity in 17 subjects with hereditary coproporphyria. The mean activity was about 50% of that in lymphocytes from normal subjects. This finding suggests that decreased coproporphyrinogen III oxidase activity reflects the primary genetic defect in Hereditary Coproporphyria. The technique described allows easy detection of asymptomatic carriers.

Adolescent↗