No abstract

chromatography seem obvious. Automatic monitoring of column effluents by available methods are necessarily complicated by the presence of the eluting solute, usually present in much higher concentration than the substance being separated. Successful water elu-

A nontoxic intravenous l-amino acid mixture became markedly toxic when l-arginine and l-histidine were deleted from the mixture and was capable of producing convulsions and death in dogs. Associated with these infusions was a marked increase in blood ammonia levels that coincided with the signs of toxicity. Similar toxicity was produced by infusion of ammonium salts. Administration of l-arginine·HCl prior to or with the infused amino acid mixture prevented the toxicity and the blood ammonia rise. Subsequent injection of l-arginine·HCl produced a prompt fall in blood ammonia to normal levels. l-Ornithine·HCl or l-citrulline·HCl were similarly effective. d-Arginine·HCl and l-histidine·HCl were ineffectual. Urea production was more rapid when l-arginine was added to the infused amino acid mixture. The results suggest that the Krebs-Henseleit cycle is a functioning metabolic pathway that normally is a major deterrent to the accumulation of excessive blood ammonia when large amounts of amino acids are infused.

paper chromatography7'8 indicated that vanillin, syringalgave the following results: vanillin, 12.5%; syringaldehyde, dehyde, and p-hydroxybenzaldehyde were the only identi-12.5%; and p-hydroxybenzaldehyde, 1.7%. fiable phenolic aldehydes present in this fraction, and quantitative paper chromatography and spectrophotometry8Appleton, Wis.