Nucleosides and nucleotides: past, present, and future

Study of the P300 and cerebral maps in subjects with multi-infarct dementia treated with cytidine

A study of event-related P300 potential and cerebral EEG maps was performed in 20 patients affected by multi-infarct dementia (MID): 10 subjects were treated with placebo and 10 with cytidine. The trial was divided into three intervals. The patients, after a period of washout, were evaluated throughout the course of the trial by electrophysiological examination performed at baseline, after 90 min from the first IV injection, again after 30 days of IM therapy, and finally after 60 days of continued IM therapy. In the group treated with cytidine, the findings relevant to the study of the P300 showed a significant decrease in latency values compared to baseline (P less than 0.05 ANOVA) and an improvement. though not significant, in the amplitude values. Calculation of the mean relative power of EEG values showed a significant decrease in delta activity and an increase in alpha activity. In the subjects treated with placebo, no statistically significant variation was found in either P300 or EEG map recordings. On the basis of these investigations it has been demonstrated that the variations in the registrations can be correlated to the improved neuronal activity following treatment with cytidine.

Involvement of phosphate-modified ATP analogs in the reactions of oxidative phosphorylation

Various analogs of adenosine 5'-triphosphate with a modified terminal phosphate group have been tested in energy-requiring reactions with intact mitochondria and submitochondrial particles. It is shown that the fluorophosphate analog ATP(gamma F) is a strong inhibitor of mitochondrial respiration and of energy requiring reactions which involve the participation of high energy intermediates, generated aerobically by the respiratory chain. On the other hand, ATP(gamma F) does not affect the ATPase activity of intact or disrupted mitochondria and is less effective in inhibiting ATP-driven reactions. The imidophosphate analog AMP-P(NH)P also inhibits the partial reactions of oxidative phosphorylation, but does not affect ATP synthesis from ADP and Pi. In contrast to ATP(gamma F), it is strong inhibitor of both soluble and membrane-bound mitochondrial ATPases. The biological implication of the complementary effects of ATP(gamma F) and AMP-P(NH)P on mitochondria-catalysed reactions is discussed while suggesting the use of such nucleotide analogs as specific tools for the study of ATP-forming and ATP-utilizing reactions in mitochondria.

Influence of 9-beta-D-arabinofuranosyladenine on total protein synthesis and on differential gene expression of unique proteins in the rodent malarial parasite Plasmodium berghei

The antibiotic 9-beta-D-arabinofuranosyladenine is a drug with a broad spectrum of activity against animal viruses, with little or no effect on mammalian cells, when administered in vivo or in vitro. Here we report that the antibiotic markedly inhibited the incorporation of [35S]methionine into malarial protein. Inhibition was apparent when the parasites were either exposed to the drug in vivo during the course of infection or incubated with the drug in vitro. Moreover, the antibiotic induced pronounced changes in the spectrum of proteins synthesized. Some proteins that are prominently apparent in the control disappear from the drug-treated parasites; others specific for drug-treated parasites appear, indicating changes in the commitment for gene expression as manifested by the appearance of the final protein product. Proteins synthesized were analyzed by two-dimensional polyacrylamide gels; the first dimension used isoelectric focusing in cylinder gels and the second dimension used electrophoresis in a lithium dodecyl sulfate slab gel. Proteins were visualized by radioautography.