• The Development of a Novel Fluorescence Polarization Drug-Screening Assay for the Interaction Between GIT1 and GRB2

      Vaillancourt, Richard; Gonzales, Jared; Vaillancourt, Richard; College of Pharmacy, The University of Arizona (The University of Arizona., 2015)
      Objectives: To develop an assay to permit the identification of compounds that can inhibit the interaction between GIT1 and the amino-terminal SH3 domain (SH3-N) of GRB2. Methods: The GIT1 protein was expressed in Sf9 insect cells and purified using Talon resin beads. The SH3-N domain of GRB2 was expressed in the E. coli strain, BL21(DE3)pLysS, and purified using glutathione resin beads. The SH3-N domain was fluorescently tagged on cysteine 32 using Cyanine 3 maleimide. The fluorescence of the assay was measured by using a plate reader with excitation wavelength of 555 nm and emission wavelength of 570 nm. Results: The GIT1 protein was expressed in Sf9 cells and purified using the Talon beads. The SH3-N domain of GRB2 was expressed in BL21 cells and purified from the glutathione resin beads. The SH3-N domain was cleaved from GST by using thrombin, which was engineered into the GST fusion protein and were fluorescently labeled using Cyanine 3 maleimide. Conclusions: The fluorescence polarization assay that will detect the interaction between GIT1 and the SH3-N domain of GRB2 is still under development, but it has progressed towards completion since both components of the assay are in hand.
    • Evaluation of the Brainstem Spinal Cord Preparation in the Neonatal Rat as a Model for Prenatal Nicotine Exposure

      Vaillancourt, Richard; Fregosi, Ralph; Richard, Levine; Vaillancourt, Richard; Fregosi, Ralph; College of Pharmacy, The University of Arizona (The University of Arizona., 2012)
      Specific Aims: The goal of this project was to evaluate the use of a preparation of the brainstem and spinal cord of neonatal rats that has been widely used for observing and quantifying central nervous activity, as well as the response to pharmacological manipulation. To achieve this, we specifically aimed to remove the intact brainstem and spinal cord of newborn rats, and develop a preparation that would maintain physiological function and allow for recording of electrical activity. Methods: Multiple dissections were performed on neonatal rats. Conditions during the dissections were controlled to maintain physiological function. Once removed, the intact brainstem and spinal cord was placed in a preparation that allowed for manipulation and access to nerve rootlets. Finally, glass suction electrodes were used to record electrical activity directly from the nerve rootlets. Once recorded, the data were stored on a hard drive for further analysis. Main Results: We were successful in isolating the intact brainstem and spinal cord in neonatal rats while maintaining physiological conditions and nervous activity. The preparation allowed for easy access to nerve roots as well as customization for different experiments. We were also successful in recording nerve activity in the preparation and collection of data for use in future experiments Conclusions: We conclude that the brainstem spinal cord preparation described in this study is a valuable tool that allows for recording and analysis of nerve activity, and specifically for measurement of respiratory motor output. This is a preparation that can be used in a variety of experiments that attempt to observe or quantify the activity of central nerve cells and allows for pharmacological interventions that could be applied in various experiments.
    • Insulin Metabolism and Protein Degradation by HEPG2 Hepatocytes Treated with HIV-Protease Inhibitors

      Vaillancourt, Richard; Fawcett, Janet; Duckworth, William; Tsui, Brian; College of Pharmacy, The University of Arizona (The University of Arizona., 2007)
      Objectives: To explore the effects of human immunodeficiency virus protease inhibitors (HPI) on insulin metabolism and protein degradation in HepG2 hepatocytes in vitro. Methods: To see if HIV-protease inhibitors affect insulin degradation in a dose-dependent manner, HepG2 cells were incubated with various concentrations of tipranavir, indinavir, or atazanavir. After 125I-insulin was added, its degradation was measured by precipitation with trichloroacetic acid (TCA). To see the effect of HPIs on protein degradation, HepG2 cells labeled overnight with 3H-leucine were incubated with 50 mM of an HPI, followed by another HPI incubation including concentrations of insulin ranging from 10-12 to 10-6 M. Cells were solubilized and proteins were precipitated using TCA. Degradation was quantified as percent TCA soluble, normalized, plotted, and then compared using student’s t-test or one- way ANOVA. Results: Cellular insulin degradation was inhibited only by tipranavir at the highest concentrations of 75 and 100 mM (12.06 ± 1.07%, p=0.047 and 9.35 ± 0.44%, p=0.024, respectively) when compared to the control (17.01 ± 1.37%; n=3). None of the concentrations of indinavir or atazanavir decreased insulin degradation significantly. From the protein degradation experiments, the log EC50 of the control (no HPI) insulin dose-response curve was not statistically different compared to those of the individual HPIs. Conclusions: Except for high concentrations of tipranavir, it appears that HPI does not inhibit the cellular degradation of insulin. HPIs do not appear to inhibit the role of insulin in the inhibition of protein degradation significantly.