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Biomedical subjects

R J Greene

Publications and source records attributed to R J Greene.

26 records · Page 2Linked to original sources
PubMed1969

Reinforcing capabilities of television distortion.

The effectiveness of television distortion as a negative reinforcer was analyzed. Contingency arrangements involving television distortion were found to be capable of (a) accelerating the work rate of a naive, mildly retarded subject on a simulated production-line task involving card-sorting, and (b) reducing gross hyperactivity of a mildly retarded subject. An escape-avoidance contingency was arranged for the production-line behavior of the first subject and a punishment contingency for the hyperactive behavior of the second subject. Television distortion appears to be an effective and practical negative reinforcer for use in behavior modification.

Journal Article↗
PubMedDate not supplied

Confirmation of a carboxylic acid metabolite of polychlorotrifluoroethylene and a method for its GC-ECD analysis in biological matrices.

3.1 Oil, referred to as polychlorotrifluoroethylene (pCTFE), is a polymeric mixture consisting primarily of trimers and tetramers of chlorotrifluoroethylene (CTFE) end-capped with chlorine. Inhalation studies have associated dose-related body weight loss, increased organ weights, and abnormal hepatic enzyme activities with exposure to pCTFE. The carboxylic acid metabolites of pCTFE have been shown to cause hepatotoxicity in rats, which is manifested by increased liver weights and the proliferation of hepatic peroxisomes. A method was developed to derivatize these carboxylic acid metabolites. Tissue homogenates and feces were extracted with methanol, and urinary metabolites were extracted on octadecylsilane (ODS) solid-phase extraction columns. Aliquots of the extracts and whole blood were methylated with 3N methanolic HCl to transesterify the carboxylic acid metabolites to volatile methyl esters. The pCTFE methyl esters were analyzed by gas chromatography (GC) with electron capture detection (ECD). The on-column limit of detection was 5 pg for each methyl ester. Solid-phase extraction of spiked urine gave extraction efficiencies of 90.4% for the trimer acid and 84.7% for the tetramer acid. This method was successfully applied to toxicity studies in rats and nonhuman primates. The identities of the derivatized metabolites were confirmed by GC/MS.

Animals↗
PubMedDate not supplied

Determination of ethoxyquin in feeds by liquid chromatography: collaborative study.

Ethoxyquin is a chemical antioxidant used in feeds, ingredients, fats, and oils. A liquid chromatographic (LC) method for determination of ethoxyquin was developed. The method involves acetonitrile extraction of the sample and isocratic C18 reversed-phase chromatography with ammonium acetate buffer-acetonitrile as mobile phase and fluorescence detection. A collaborative study of the determination of ethoxyquin in various meals and extruded pet foods was conducted by The Iams Company Research Laboratory. Eleven laboratories analyzed 16 samples (including 2 blind duplicates) consisting of 7 meat meals and 9 extruded pet foods. Sample means ranged from 0.25 to 289 ppm. Repeatability standard deviations ranged from 0.08 to 3.2 ppm, and repeatability relative standard deviations ranged from 4.5 to 32%. Reproducibility standard deviations ranged from 0.12 to 13 ppm, and reproducibility relative standard deviations ranged from 4.5 to 55%. The LC method for determination of ethoxyquin in feeds has been adopted first action by AOAC INTERNATIONAL.

Acetonitriles↗