Biomedical subjects
Publications and source records attributed to L Cathelineau.
Acute glucagon treatment of Rats has been found to increase in liver the intramitochondrial concentration of acetylglutamate which is an activator of carbamylphosphate synthetase l. A part of the stimulation of citrulline formation by glucagon is certainly related to this increase of acetylglutamate concentrations.
A new human enzymatic variant was found in a patient with ornithine carbamoyltransferase (carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) deficiency. This mutant enzyme has decreased affinity, with an abnormal Km value for ornithine (3-5-times greater than control at all pH values). The maximal velocity (V) varied with pH as a normal enzyme but the sigmoid curve obtained (V vs. pH) is shifted towards alkaline pH values. The pK of the functional catalytic group is 8.3 instead of 6.65 of a control enzyme. At its optimum pH the V of the mutant enzyme is greater than the V of the normal enzyme. Other mutant enzyme proteins with abnormal affinity for ornithine have already been described. They all are different from the reported here.
This is the report of the results obtained with continuous enteral feeding in congenital nephrotic syndrome (3 cases), cystinosis (3 cases) and renal failure (3 cases). Ages of patients at the beginning of treatment ranged from 10 days to 3 years. Enteral nutrition was given for periods ranging from 4 to 37 months; mean energetic intake was 116% of the levels recommended according to developmental age and protein diets were 138%; 115% and 84% of the recommended amounts in nephrotic syndromes, cystinosis and renal failure, respectively. This treatment obtained the survival of most patients. In congenital nephrotic syndromes, growth improved clearly with acceleration of the curve and restoration of plasma albumin level. In cystinosis, a better fluid and electrolyte balance was obtained and growth curve sometimes improved in a spectacular fashion. Finally, in renal failure, effect on growth was favourable in 2 cases and nil in the third: these findings show that normalization of energetic intakes does not induce normal growth in children with uremia.
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A rapid method of preparation of ornithine carbamyl transferase from rat liver is described. The enzyme preparation obtained is lacking in carbamyl phosphate synthetase activity. It may thus be used for the estimation of this enzyme on liver fragments obtained by needle biopsy of the liver in the diagnosis of neonatal hyperammonemia.
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Fifty cystic fibrosis (CF) patients, of whom 9 had multilobular cirrhosis, were observed regularly for a period of 3 years and various liver function tests, indicating cytolysis, cholestasis and cellular insufficiency were performed. Immunoglobulin and prothrombin were assayed. In 9 patients with cirrhosis, the tests were generally abnormal. Two distinct biochemical patterns of cirrhosis were distinguished, one clearly cholestatic and the other of a more cellular type. The distinction was made on the basis of the IgA : Transferrin ratio and of gamma-glutamyl-transpeptidase levels. In the non-cirrhotic patients, a temporary increase of cytolysis and cholestasis was observed in 50% of the cases.
The authors report two male cases of liver ornithine carbamyl transferase deficiency. In one the disease occurred at 8 years of age with hyperammoniemic coma leading to death in 48 hours. In the second case, symptoms appeared on the sixth day of life but the outcome was favorable. The child is normal at 15 months. In both cases, there was a residual 6-10% OCT activity. These observations are similar to two other male cases in the literature and are different from the male neonatal fatal form in which the deficiency is virtually total. They underline the genetically heterogeneous nature of OCT deficiencies and the fact that in this X-transmitted trait, hemizygotes can preserve a functional enzymatic activity compatible with life.
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