scholarly journals Pituitary Effect on Synthesis of Deoxyribonucleic Acid in Regenerating Rat Liver following Whole-body X-irradiation

Nature ◽  
1961 ◽  
Vol 192 (4809) ◽  
pp. 1309-1309 ◽  
Author(s):  
D. M. GOULD ◽  
K. W. FLOYD ◽  
R. W. WHITEHEAD ◽  
J. L. SANDERS
1961 ◽  
Vol 39 (6) ◽  
pp. 1043-1054 ◽  
Author(s):  
D. K. Myers ◽  
C. Anne Hemphill ◽  
Constance M. Townsend

Deoxycytidylate deaminase activity and net synthesis of deoxyribonucleic acid (DNA) in vivo were found to increase at approximately the same time during the early stages of liver regeneration. However, deaminase activity in the regenerating liver remained at a high level for 1 day after DNA synthesis had slowed down again during the later stages of regeneration. The increase in deaminase activity was restricted as a result of exposure to 600 r X radiation during early regeneration, but this effect only became evident 11–16 hours after the irradiation. Irradiation on the second day after partial hepatectomy, when deaminase levels in control regenerating livers were relatively constant, failed to affect the deaminase activity immediately but did produce a 40–50% decrease in activity 11–16 hours later. Other antimitotic agents, e.g., colchicine, had little effect on deaminase activity.


1959 ◽  
Vol 196 (6) ◽  
pp. 1231-1237 ◽  
Author(s):  
R. Gordon Gould ◽  
Virginia L. Bell ◽  
Edith H. Lilly

Whole body x-irradiation resulted in an increased cholesterol biosynthesis in rat liver and adrenal glands, as measured by the rate of incorporation of either acetate-1-C14 or H3OH in intact animals. The effect was significant 24 hours postirradiation but was much larger at 48 hours, and was proportional to dosage over the range 300–2400 r. In liver the increase in rate was about 100%/100 r. Intestine showed no effect and carcass only a slight increase. Mice showed a small increase in hepatic cholesterol biosynthesis but rabbits and guinea pigs no significant change. Rats injected with both acetate-1-C14 and H3OH gave reasonably constant ratios of C14 and H3 in liver and carcass cholesterol in control and irradiated animals, supporting the hypothesis that the use of acetate-1-C14 in whole animals under standard conditions is a reliable measure of cholesterol biosynthetic rate. The proximate cause of the increased rate of cholesterol synthesis is postulated to be the decreased concentration; in liver a decrease of 0.12 mg/gm was correlated with a doubling of the synthetic rate.


Nature ◽  
1962 ◽  
Vol 194 (4831) ◽  
pp. 883-884 ◽  
Author(s):  
R. FOSTER ◽  
MARGERY G. ORD

1976 ◽  
Vol 158 (2) ◽  
pp. 485-488 ◽  
Author(s):  
H Pösö ◽  
J Jänne

Repeated injections of 1,3-diaminopropane into rats after partial hepatectomy caused a repression-type inhibiton of liver ornithine decarboxylase (EC 4.1.1.17) and totally prevented the marked increases in liver putrescine and spermidine concentrations that normally occur in response to partial hepatectomy. The inhibition of polyamine synthesis by diaminopropane was accompanied by a profound decrease (about 80%) in the synthesis of DNA in the regenerating rat liver without any changes in the synthesis of RNA and total liver protein.


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