Blood Pressure Changes during Human Sleep

F. Snyder, J. A. Hobson, F. Goldfrank
1963 Science  
most postpubertal patients with this disease to metabolize galactose (3). In spite of the evidence that the Galtransferase and UDPGal-pyrophosphorylase activity of liver tissue increases with age, the data presented here demonstrate a decrease with age in the ability of liver tissue to utilize galactose. One possible explanation for the discrepancy between the enzyme levels and the activity of whole tissues, is that these particular enzymes are not rate-determining for the series of reactions
more » ... nverting galatose to glucose. The rate-limiting step may be the initial phosphorylation of galactose by the enzyme, galactokinase, according to the reaction, Galactoseadenosinetriphosphate (ATP) --> adenosinediphosphate -Gal-l-P, and, indeed, Kirkman and Kalckar (6) have presented some evidence that this is the case for red blood cells. If the diminished rate of galactose utilization demonstrated here in the adult liver were, in fact, due to a decrease in the phosphorylation of galactose (whether because of lowered galactokinase activity or lowered ATP availability, or for other reasons) this would imply a decreased rate of galactose-1phosphate production in the adult, and would be consistent with the speculation that the accumulated galactose-l-phosphate is the toxic agent. , ibid. 136, 150 (1962). Since the appearance of this report, studies on three additional galactosemic adults have shown that these patients were virtually unable to metabolize galactose. 4. B. Combes and G. S. Stakelin, J. Clin. Invest. 41, 750 (1963). 5. M. Spatz, personal communication. 6. H. N. Kirkmann, H. M. Kalckar, Ann. N.Y. Acad. Sci. 75, 274 (1958). 7. All animals were obtained from the animal colony of the National Institutes of Health, Bethesda, and had been maintained on conventional rat rations, under ordinary conditions. 8. The technique for assaying galactose was devised in this laboratory, and exploits the properties of the enzyme, galactose oxidase, described by
doi:10.1126/science.142.3597.1313 pmid:14074846 fatcat:v5illubmxnchjgg2qobqv7dkje