HILTON ET natedl acetic acid was more inhibitory than TCA and was more readily antagonized by ,B-alanine.The inability of high concentrations of ,B-alanine completely to reverse the inhibitions produced by this class of compounds suggest that physical or chemical processes other than the fl-alanine pantothenic acid reaction(s) may be involved in the mechanisms of action. Nevertheless, the utilization of fl-alanine appears to be the most sensitive metabolic process involved under the experimental conditions employed; the enzymes involved in pantothenic acid synthesis should be investigated as a possible important site of action of these herbicidal compounds. Further investigations on this mechanism of action and its relative importance in species selectivity are in progress and will be the subject of future reports from this laboratory. SUMMARY Inhibition of yeast growth by chloro-substituted isobutyric, propionic, and acetic acids has been observed. An exogenous supply of 8-alanine has been shown to produce varying degrees of protection against these inhibitions.The results obtained suggest that these herbicides interfere with synthesis of pantothenic acid, presumablv by competition with ,p-alanine. LITERATURE CITED 1. KINGC, T. E. and CHELDELIN, V'. H. Pantothenic acid studies. IV. Propionic acid and 8-alanine utilization. Jour. Biol. Chem.

Paper chromatographic procedures may be used to detect cephalothin and its metabolite desacetylcephalothin in urine, plasma, synovial fluid, and cerebrospinal fluid. Protein-bound antibiotics are released from plasma, cerebrospinal fluid, and synovial fluid by dilution with an equal volume of dimethylformamide. Data are presented on the sample preparation, paper chromatographic system, and other specific techniques.

Thin-layer and paper chromatographic systems were used to detect and determine the concentration of cephaloglycin and its biologically active metabolites in serum and urine. Data are presented on the procedures, solvent systems, and specific techniques used in this evaluation.

Paper chromatographic procedures may be used to detect cephalothin and its metabolite desacetylcephalothin in urine, plasma, synovial fluid, and cerebrospinal fluid. Protein-bound antibiotics are released from plasma, cerebrospinal fluid, and synovial fluid by dilution with an equal volume of dimethylformamide. Data are presented on the sample preparation, paper chromatographic system, and other specific techniques.

No abstract