UTP Content Research Articles

Liver injury induced by 2-deoxy- d-galactose

Injections of 2-deoxy- d-galactose induce acute liver injury in guinea pigs. Ultrastructural changes is hepatocytes include a hypertrophy of the smooth and a reduction of the rough endoplasmic reticulum, fatty infiltration, and nucleolar fragmentation. Kupffer cells are enlarged and increased in number. The activities of sorbitol dehydrogenase, glutamate dehydrogenase, glutamate oxaloacetate transaminase, and the bilirubin concentration are greatly increased in plasma. The early metabolic events caused by 2-deoxy- d-galactose have been studied in freeze-clamped livers after administration of a single dose. Formation and accumulation of nonphysiologic UDP-2-deoxy-hexoses function as a trapping mechanism for uridine phosphate. Specific, enzymatic measurements reveal the rapid induction of UTP deficiency, associated with a depletion of UDP-glucose and UDP-galactose pools. Administration of the same dose per kilogram of body weight decreases the hepatic UTP content to 25% of normal for more than 7 hr in guinea pigs, and to 25–30% of normal for less than 2 hr in rats. The mechanisms compensating UTP deficiency are much more active in rat as compared to guinea pig liver. This difference accounts for the previously reported finding, that pure 2-deoxy- d-galactose does not provoke signs of liver injury in the rat. All of the ultrastructural and biochemical lesions induced by 2-deoxy- d-galactose have also been observed after administration of d-galactosamine, although both galactose analogs do not share any common metabolites. However, 2-deoxy- d-galactose is less efficient and therefore does not cause extensive hepatocellular necrosis.

The Composition of Soluble Nucleotides in the Developing Wheat Grain

A method is described for the extraction and measurement of soluble nucleotides from wheat grain. Nucleotides were separated (80-90% recovery) by paper chromatography followed by electrophoresis. The nucleotides extracted were ADP-glucose, ATP, ADP, AMP, and NAD; UDP-glucose, UTP, UDP, and UMP with smaller quantities of cytidine nucleotides.In grain sampled at 20 days after anthesis, 70% of the UDP-glucose was present in the endosperm and the remainder in the testa and pericarp; 90% of the ADP-glucose was found in the endosperm. Of the four uridine nucleotides UDP-glucose was the most plentiful and the level rose from about 330 mmumoles per g fresh weight on the third day after flowering to 430 mmumoles/g on day 12 and then fell steadily to about 140 mmumoles/g just before complete ripening. Levels of 250 mmumoles and 200 mmumoles per g fresh weight were recorded for UTP and UDP on day 12. Thereafter the content of UTP fell relatively more rapidly than either UDP or UDP-glucose.ATP was the most abundant adenine nucleotide and from 7 days after anthesis to day 40 the quantity per g fresh weight fell from about 350 mmumoles to 100 mmumoles. The level of ADP-glucose rose to a maximum of 140 mmumoles/g between days 15 and 21 and then fell slightly towards maturity while ADP varied between 50 and 80 mmumoles/g. On day 20, coinciding with the maximum rate of starch synthesis in the endosperm, the concentration of ADP-glucose in this tissue was about 0.3 mm, and that of UDP-glucose 0.7 mm.The relationship of these results to the mechanism of transfer of hexose units from sucrose to starch is discussed.