Two endogenous ligands for the brain benzodiazepine-binding sites were isolated from bovine brain through gel filtration, paper electrophoresis, and paper chromatography. These ligands were identified as inosine and hypoxanthine, and both had a higher affinity for the brain benzodiazepine-binding sites than for benzodiazepine sites in some peripheral tissues. They did not bind to any other rece...

The second base of codon 61 of a synthetic c-Ha-ras gene was replaced with a hypoxanthine residue in a site-specific manner. Transfection of this gene into NIH3T3 cells by the calcium phosphate procedure resulted in increased focus formation. Total DNA was extracted from transformed cells, and the sequences of the inserted c-Ha-ras DNA were analyzed by the polymerase chain reaction-single-stran...

Repair replication of DNA in cells exposed to UV, X-rays, or chemical carcinogens involves incorporation of both purine and pyrimidine precursors. Previous reports stating that purines are not involved in repair must be due to insufficient resolution in the reported experiments. Hypoxanthine was more efficiently incorporated by repair replication than other precursors such as adenine, deoxyaden...

The second base of codon 61 of a synthetic c-l la-ra.vgene was replaced with a hypoxanthine residue in a site-specific manner. Transfection of this gene into NIH3T3 cells by the calcium phosphate procedure resulted in increased focus formation. Total DNA was extracted from transformed cells, and the sequences of the inserted c-l la-ra.v DNA were analyzed by the polymerase chain reaction-single-...

Oxygen metabolites have been implicated in the pathogenesis of various types of acute tissue injury. One biologic source of oxygen metabolites is the reaction catalyzed by the enzyme xanthine oxidase. Because we previously demonstrated that the substrates for xanthine oxidase (hypoxanthine and xanthine) are elevated in the plasma of critically il l patients, we questioned whether the enzyme its...

CSF obtained for clinical purposes from newborn, children and adults has been analysed by high pressure liquid chromatography for hypoxanthine, xanthine, inosine, uridine and urate. Large rises in hypoxanthine and to a lesser extent xanthine occur for about 24 h after hypoxia. High concentrations were associated with later evidence of brain damage or subsequent death. Changes in CSF could be in...