Steven A Stryker

Bristol-Myers Squibb, New York, New York, United States

Are you Steven A Stryker?

Claim your profile

Publications (2)7.95 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A method is described that allows non-invasive identification and quantitative assessment of lipid classes present in sebaceous excretions in rodents. The method relies on direct high-field proton NMR analysis of common group lipid protons in deuterated organic solvent extracts of fur. Extracts from as little as 15 mg of fur from rat, mouse and hamster provided acceptable results on a 600 MHz NMR equipped with a cryogenically cooled proton-observe probe. In rats, sex and age-related differences in lipid composition are larger than differences in fur collected from various body regions within an individual and much larger than inter-animal differences in age and sex-matched specimens. The utility of this method to non-invasively monitor drug-induced sebaceous gland atrophy in rodents is demonstrated in rats dosed with a steroyl coenzyme A desaturase (SCD1) inhibitor. In this model, a 35% reduction in sebum lipids, extracted from fur, was observed. Finally, structural elucidation of cholesta-7,24-dien-3β-ol ester as the most prominent, previously unidentified sebum sterol ester in hamster is described. The utility of this method for drug and cosmetic safety and efficacy assessment is discussed.
    Preview · Article · Apr 2014 · The Journal of Lipid Research
  • [Show abstract] [Hide abstract]
    ABSTRACT: The overnight (16-h) fast is one of the most common experimental manipulations performed in rodent studies. Despite its ubiquitous employment, a comprehensive evaluation of metabolomic and transcriptomic sequelae of fasting in conjunction with routine clinical pathology evaluation has not been undertaken. This study assessed the impact of a 16-h fast on urine and serum metabolic profiles, transcript profiles of liver, psoas muscle, and jejunum as well as on routine laboratory clinical pathology parameters. Fasting rats had an approximate 12% relative weight decrease compared to ad libitum fed animals, and urine volume was significantly increased. Fasting had no effect on hematology parameters, though several changes were evident in serum and urine clinical chemistry data. In general, metabolic changes in biofluids were modest in magnitude but broad in extent, with a majority of measured urinary metabolites and from 1/3 to 1/2 of monitored serum metabolites significantly affected. Increases in fatty acids and bile acids dominated the upregulated metabolites. Downregulated serum metabolites were dominated by diet-derived and/or gut-microflora derived metabolites. Major transcriptional changes included genes with roles in fatty acid, carbohydrate, cholesterol, and bile acid metabolism indicating decreased activity in glycolytic pathways and a shift toward increased utilization of fatty acids. Typically, several genes within these metabolic pathways, including key rate limiting genes, changed simultaneously, and those changes were frequently correlative to changes in clinical pathology parameters or metabolomic data. Importantly, up- or down-regulation of a variety of cytochrome P450s, transporters, and transferases was evident. Taken together, these data indicate profound consequences of fasting on systemic biochemistry and raise the potential for unanticipated interactions, particularly when metabolomic or transcriptomic data are primary end points.
    No preview · Article · Mar 2011 · Chemical Research in Toxicology