Levels Of Catabolites Research Articles

Activité mono amine oxydase dans les tumeurs de la crête neurale

Mono Amine Oxidase activity in 54 fragments of neural crest tumors from 33 children ( 24 neuroblastomas, 4 ganglioneuroblastomas, 5 ganglioneuromas) and from 3 adults ( 3 pheochromocytomas), has been studied by the authors. 1. A. The repartition of the enzyme is heterogeneous and the values obtained in different parts of the tumors sometimes vary in the proportion of 1 to 5. The estimation of proteins in the tissues, necessary for calculating the specific activity can introduce an important error. 2. B. It seems there is no direct relationship between the level of catabolic enzyme (MAO) in the tumor and the levels of catabolites (vanillyl mandelic acid and homovanillic acid) found in the urine. 3. C. Pheochromocytomas have a very low Mono Amine Oxidase activity compared with neuroblastomas. The possibility of a competitive inhibition between the substrate (kynuramine) and catecholamines liberated by disruption of tumor cells is not excluded. 4. D. No MAO activity was found in four neuroblastomas examined, perhaps for the following reasons: inhibition of the enzyme by tyramine or dopamine liberated by disruption of cells an inhibitor of unknown nature masking of the enzyme a different cellular type.