Importance of treatment regimen of interferon as an antitumor agent.

A highly purified hybrid human leukocyte interferon, IFN-alpha AD, produced in Escherichia coli, has been used to define optimum treatment conditions for L1210 leukemia in mice. Treatments prior to tumor inoculation were ineffective. Treatments from the third day post-tumor inoculation were most effective, and treatments every third day were more effective than were regimens involving more frequent treatments. IFN-alpha AD was effective in vivo against tumors formed from a line of L1210 cells resistant to IFN-alpha AD in cell cultures. These and other results indicate the importance and nature of indirect mechanisms of action for efficacy of interferons against tumors.

Protein synthesis and aging: studies with cell-free mammalian systems.

A cell-free system devoid of polysomes, which translates natural mRNA, has been prepared from rat liver. It contains ribosomal subunits, ribosomes, aminoacyl-tRNA synthetases, tRNAs, and protein factors necessary for translation. Protein synthesis required an energy-generating system, mRNA, and 3 mM Mg2+ concentration, and it was inhibited by 7-methylguanylic acid. The total extent and the rate of protein synthesis were approximately 30% greater when the translating system was prepared from livers of 3-month-old rats, as compared to 30-month-old rats. A ribosome-free fraction containing the protein factors required for translation was also prepared from 3-month-old and 30-month-old rat livers and brains, by extraction with 0.5 M KCl. The high-salt extracts were analyzed for elongation factors EF-1 and EF-2 in a poly(U) translating system. Although the activity of EF-2 was similar in preparations from young and old rats, the EF-1 activity in the 3-month-old rat livers and brains was 30 to 40% greater than in 30-month-old animals. The protein synthesizing activity of high salt-washed ribosomes stripped of endogenous peptidyl-tRNA and mRNA, from livers and brains of young and old animals, was the same.

[Effect of accelerations, additional weight load and hypokinesia on protein catabolism in the Japanese quail (Coturnix coturnix japonica)]. / Vliianie uskorenii, dopolnitel'noi vesovoi nagruzki i gipokinezii na katabolizm belkov u perepela iaponskogo (Coturnix coturnix japonica)

Activities of glutamate and xanthine dehydrogenases were measured in four groups of quails (coturnix coturnix japonica): 1) hypodynamic birds which were kept in an area which made 1/4 of the control, 2) birds exposed to an increased weight load, 3) birds exposed to 3g. and 4) control birds. The experimental birds were exposed to the above treatment for 1 to 6 hours a day during 8 days. The birds were fed on a forced basis to eliminate differences in food intake. The activity of glutamate dehydrogenase was measured in the liver and that of xanthine dehydrogenase was assayed in the liver, kidneys and femoral muscle. It was found that increased gravity, weight load and hypodynamics affected the first and last stages in protein catabolism.