Galactose-1-phosphate uridyltransferase activities in erythrocytes from a patient with galactosemia: discrepancy between two methods.

When measuring with the spectrophotometric UDP-Glu consumption test, the galactose-1-phosphate uridyltransferase (Gal-PUT) activity in erythrocyte lysates from a 22-month-old infant with a late onset form of galactosemia was found to be approximately 25% of normal. With a radiochemical assay only a very low residual activity could be detected (+/- 1% of normal). Preincubation of the patient's lysate with purified NADase caused a marked decrease of residual Gal-PUT activity as judged from the data obtained with the consumption test. The radiochemical assay was not influenced by a similar pre-treatment. The high level of residual activity found with the consumption test in this patient was attributed to the consumption of UDP-Glu by other reactions than Gal-PUT. Because it is a direct, simple and generally applicable assay, the radiochemical procedure is suggested to be the best method for the more detailed enzymological characterisation of the Gal-PUT deficient state in galactosemics.

[Cell kinetics and radiosensitivity of Cercopithecus aethiops sabaceus lymphocytes stimulated by phytohemagglutinin]. / Cinétique cellulaire et radiosensibilité des lymphocytes de Cercopithecus aethiops sabaceus stimulés par la phytohémagglutinine.

The use of the BudR-Giemsa technique has shown that the peripheral blood lymphocytes of Cercopithecus aethiops sabaceus display a very fast answer to PHA-stimulation. At 32 h culture time numerous mitoses are already present and at 48 h more than 30% of the dividing cells are in second mitosis. Exposure to X-irradiation results in a higher incidence of unstable aberrations than in human lymphocytes.

Enzymes of galactose metabolism in human hair roots.

Micro-methods, making use of radioactive substrates, are described for the quantitative estimation of galactokinase and galactose-1-phosphate uridyl transferase activities in lysates of hair roots obtained from the human scalp. Enzyme assays can be carried out with fractions of one hair root. Both enzymes have been investigated with regard to stability, pH optimum and Michaelis-Menten constants. Along with similarities there were also certain differences as compared to galactokinase and galactose-1-phosphate uridyl transferase activities in other human tissues. The findings were used to optimise and standardise a radiochemical micro-assay for both enzymes in human hair root lysates, applicable to carrier detection studies in galactosaemia, an inborn error of carbohydrate metabolism. Because they can easily be obtained, hair roots are a very suitable biopsy material for both fundamental and diagnostic investigations of these enzymes.