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  • Robert E. Kramer, PhD

     kramer, robert

    Office: North Wing N437
    Phone:(601) 984-1604
    E-mail: RKramer@umc.edu


    Current research

    The underlying theme of research in my laboratory is the control of cytochrome P450 enzymes. One focus within this theme is the regulation of cytochromes P450 within the adrenal cortex in relation to steroid hormone secretion. General aspects of adrenocortical function encompassed within that focus include the mechanisms of signal transduction for ACTH, angiotensin II and potassium; modulation of aldosterone secretion by factors such as extracellular pH, sodium ion concentration and osmolality, particularly in relation to the role of calcium in the steroidogenic actions of these agonists; regulation of the synthesis and activities of steroidogenic cytochromes P450, and differential control of adrenal androgen secretion.

    The roles of cytosolic and mitochondrial calcium in the transduction mechanisms of angiotensin and potassium are being examined in relation to the activation of mitochondrial cholesterol side chain cleavage and aldosterone synthase. The interactions between changes in cytosolic calcium, hydrogen and sodium ion concentrations in the regulation of mitochondrial hydroxylases is also an area of investigation.

    A second focus is the effect of organophosphorus insecticides on the development of hepatic cytochrome P450 systems. Objectives within this focus are to determine if the fetal/neonatal liver metabolizes agricultural chemicals such as methyl parathion, chlorpyrifos, and diquat; to identify the specific isozymes of cytochrome P450 involved; to define changes in the expression and activities of specific cytochrome P450 isozymes as well as the mechanisms involved; and, finally, to determine the consequences of such actions in adulthood.

    Selected publications

    • Kyle, P. B., Smith, S. V., Baker, R. C., and Kramer, R. E. (2012) Mass spectrometric detection of CYP450 adducts following oxidative desulfuration of methyl parathion, Journal of applied toxicology : JAT. PubMed article 
    • Kyle, P. B., Adcock, K. G., Kramer, R. E., and Baker, R. C. (2005) Use of liquid chromatography-tandem mass spectrometry for the analysis of pentoxifylline and lisofylline in plasma, Biomedical chromatography : BMC 19, 231-236. PubMed article 
    • Wellman, S. E., and Kramer, R. E. (2004) Absence of DNA binding activity of methyl parathion and chlorpyrifos, Toxicology mechanisms and methods 14, 247-251. PubMed article 
    • Rogers, P. D., Kramer, R. E., Crews, J. K., and Lewis, R. E. (2003) The activity of amphotericin B against Candida albicans is not directly associated with extracellular calcium concentration, The Journal of antimicrobial chemotherapy 51, 305-312. PubMed article 
    • Ma, T., Kramer, R. E., Baker, R. C., Fan, L. W., and Ho, I. K. (2003) Effects of chronic dermal exposure to nonlethal doses of methyl parathion on brain regional acetylcholinesterase and muscarinic cholinergic receptors in female rats, Journal of neuroscience research 71, 138-145. PubMed article 
    • Chudapongse, N., Kim, S. Y., Sasaki, K., Kramer, R. E., and Ho, I. K. (2003) Nonopioid receptor-mediated effects of U-50,488H on [Ca(2+)]i and extracellular dopamine in PC12 cells, Journal of neuroscience research 74, 598-604. PubMed article 
    • Chudapongse, N., Kim, S. Y., Kramer, R. E., and Ho, I. K. (2003) Nonspecific effects of the selective kappa-opioid receptor agonist U-50,488H on dopamine uptake and release in PC12 cells, Journal of pharmacological sciences 93, 372-375. PubMed article 
    • Kramer, R. E., Wellman, S. E., Zhu, H., Rockhold, R. W., and Baker, R. C. (2002) A comparison of cholinesterase activity after intravenous, oral or dermal administration of methyl parathion, Journal of biomedical science 9, 140-148. PubMed article 
    • Kramer, R. E., Wellman, S. E., Rockhold, R. W., and Baker, R. C. (2002) Pharmacokinetics of methyl parathion: a comparison following single intravenous, oral or dermal administration, Journal of biomedical science 9, 311-320. PubMed article 
    • Kramer, R. E., and Ho, I. K. (2002) Pharmacokinetics and pharmacodynamics of methyl parathion, Zhonghua yi xue za zhi = Chinese medical journal; Free China ed 65, 187-199. PubMed article 
    • Zhu, H., Rockhold, R. W., Baker, R. C., Kramer, R. E., and Ho, I. K. (2001) Effects of single or repeated dermal exposure to methyl parathion on behavior and blood cholinesterase activity in rats, Journal of biomedical science 8, 467-474. PubMed article
    • Kramer, R. E., Robinson, T. V., Schneider, E. G., and Smith, T. G. (2000) Direct modulation of basal and angiotensin II-stimulated aldosterone secretion by hydrogen ions, The Journal of endocrinology 166, 183-194. PubMed article