Pathogenetic Factors in Experimental Galactose Cataract

Methaemoglobin Reduction: Studies Using Galactose as Substrate

“…No inhibition of G-6-PD activity could be demonstrated with galactose, galactose-l-phosphate, or glucose-l-P. The failure of Gal-1-P to inhibit G-6-PD activity in human erythrocytes is in contrast to the results of Lerman (1960). Inhibition of other steps in the hexose monophosphate pathway by galactose or its metabolites cannot be ruled out with certainty, but appears unlikely in view of the fact that methaemoglobin reduction accelerated promptly when glucose was added to cells incubated with galactose and methylene blue.…”

Methaemoglobin Reduction: Studies Using Galactose as Substrate

“…No inhibition of G-6-PD activity could be demonstrated with galactose, galactose-l-phosphate, or glucose-l-P. The failure of Gal-1-P to inhibit G-6-PD activity in human erythrocytes is in contrast to the results of Lerman (1960). Inhibition of other steps in the hexose monophosphate pathway by galactose or its metabolites cannot be ruled out with certainty, but appears unlikely in view of the fact that methaemoglobin reduction accelerated promptly when glucose was added to cells incubated with galactose and methylene blue.…”

The Value of Galactose Phosphate Determinations in the treatment of Galactosaemia

“…An analogous disturbance has been demonstrated in a mutant of E. coli deficient in uridyltransferase: on incubation of the culture with galactose, it evinces a prolonged lag phase before the onset of growth, which is preceded by intracellular accumulation of gal-i-P (Kurahashi and Wahba, 1958). Recently evidence has been presented which indicates that gal-i-P may exert an inhibitory effect on a number of enzymes-phosphoglucomutase, G-6-P phosphatase and dehydrogenase (Sidbury, 1957;Ginsburg and Neufeld, 1957;Lerman, 1960).…”

“…gal-i-P/g., whereas non-cataractous lenses of galactose-fed animals contained not more than 0-1 of this amount. Recently, Lerman (1960) has shown that an inhibition of lenticular G-6-P dehydrogenase and of glucose catabolism is demonstrable two to four days after instituting a high galactose diet, and that the ATP content of the tissues drops to very low levels. This interference with normal metabolism might well result from the accumulation of gal-i-P and probably accounts for the gradual opacification.…”

Methaemoglobin Reduction: Studies Using Galactose as Substrate

“…No inhibition of G-6-PD activity could be demonstrated with galactose, galactose-l-phosphate, or glucose-l-P. The failure of Gal-1-P to inhibit G-6-PD activity in human erythrocytes is in contrast to the results of Lerman (1960). Inhibition of other steps in the hexose monophosphate pathway by galactose or its metabolites cannot be ruled out with certainty, but appears unlikely in view of the fact that methaemoglobin reduction accelerated promptly when glucose was added to cells incubated with galactose and methylene blue.…”

The Value of Galactose Phosphate Determinations in the treatment of Galactosaemia

“…An analogous disturbance has been demonstrated in a mutant of E. coli deficient in uridyltransferase: on incubation of the culture with galactose, it evinces a prolonged lag phase before the onset of growth, which is preceded by intracellular accumulation of gal-i-P (Kurahashi and Wahba, 1958). Recently evidence has been presented which indicates that gal-i-P may exert an inhibitory effect on a number of enzymes-phosphoglucomutase, G-6-P phosphatase and dehydrogenase (Sidbury, 1957;Ginsburg and Neufeld, 1957;Lerman, 1960).…”

“…gal-i-P/g., whereas non-cataractous lenses of galactose-fed animals contained not more than 0-1 of this amount. Recently, Lerman (1960) has shown that an inhibition of lenticular G-6-P dehydrogenase and of glucose catabolism is demonstrable two to four days after instituting a high galactose diet, and that the ATP content of the tissues drops to very low levels. This interference with normal metabolism might well result from the accumulation of gal-i-P and probably accounts for the gradual opacification.…”

Methaemoglobin Reduction: Studies Using Galactose as Substrate

“…No inhibition of G-6-PD activity could be demonstrated with galactose, galactose-l-phosphate, or glucose-l-P. The failure of Gal-1-P to inhibit G-6-PD activity in human erythrocytes is in contrast to the results of Lerman (1960). Inhibition of other steps in the hexose monophosphate pathway by galactose or its metabolites cannot be ruled out with certainty, but appears unlikely in view of the fact that methaemoglobin reduction accelerated promptly when glucose was added to cells incubated with galactose and methylene blue.…”

The Value of Galactose Phosphate Determinations in the treatment of Galactosaemia

“…An analogous disturbance has been demonstrated in a mutant of E. coli deficient in uridyltransferase: on incubation of the culture with galactose, it evinces a prolonged lag phase before the onset of growth, which is preceded by intracellular accumulation of gal-i-P (Kurahashi and Wahba, 1958). Recently evidence has been presented which indicates that gal-i-P may exert an inhibitory effect on a number of enzymes-phosphoglucomutase, G-6-P phosphatase and dehydrogenase (Sidbury, 1957;Ginsburg and Neufeld, 1957;Lerman, 1960).…”

“…gal-i-P/g., whereas non-cataractous lenses of galactose-fed animals contained not more than 0-1 of this amount. Recently, Lerman (1960) has shown that an inhibition of lenticular G-6-P dehydrogenase and of glucose catabolism is demonstrable two to four days after instituting a high galactose diet, and that the ATP content of the tissues drops to very low levels. This interference with normal metabolism might well result from the accumulation of gal-i-P and probably accounts for the gradual opacification.…”