Kevin Nguyen

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In Streptomyces, a family of related butyrolactones and their corresponding receptor proteins serve as quorum-sensing systems that can activate morphological development and antibiotic biosynthesis. Streptomyces pristinaespiralis contains a gene cluster encoding enzymes and regulatory proteins for the biosynthesis of pristinamycin, a clinically important(More)
Transforming growth factor (TGF)-β1 has a biphasic effect on rat intestinal epithelial (RIE) cells. By itself, TGF-β1 functions as a tumor suppressor by inhibiting the growth, migration and invasion of RIE cells. We show in this study that in conjunction with epidermal growth factor (EGF), TGF-β1 helped to augment migration, invasion and(More)
There have been few studies on the specific signaling pathways involved in the transformation of epithelial cells by oncogenic protein tyrosine kinases. Here we investigate the requirement of MAP (MAPK) and phosphatidylinositol 3- (PI3K) kinases in the transformation of rat intestinal epithelial (RIE) cells by oncogenic forms of insulin receptor (gag-IR),(More)
In this work we present an inexpensive method of exploring a large immersive virtual environment (VE). More specifically, we describe a method of physically leaning to explore a VE on a Nintendo Wii Fit Balance Board, Wii-Leaning. In two experiments described in this paper, we directly compare our Wii-Leaning method to two other methods of exploring a large(More)
Antimicrobial preservatives are excipients added to multi-dose containers of both sterile and non-sterile drug products. Antimicrobial preservatives are used primarily to inhibit growth of microbial contamination occurring during the period of use. Demonstration of antimicrobial preservative effectiveness is required for these functional excipients. This(More)
Using loss-of-function mutants of Ros and inducible epidermal growth factor receptor-Ros chimeras we investigated the role of various signaling pathways in Ros-induced cell transformation. Inhibition of the mitogen-activated protein kinase (MAPK) pathway with the MEK (MAP/extracellular signal-regulated kinase kinase) inhibitor PD98059 had little effect on(More)
One way to permit free exploration of any sized virtual environment (VE) and provide some of the inertial cues of walking is to have users "walk in place" (WIP) [Williams et al. 2011]. With WIP, each step is treated as a virtual translation even though the participant remains in the same location. In our prior work [Williams et al. 2011], we had success in(More)
Time of arrival is a commonly used mechanism for geolocation. In many environments, multipath propagation of RF signals limits accuracy. Wide bandwidths reduce the impact of multipath propagation, but frequently results in interference from other devices. When the bandwidth is assembled from several measured sub-bands, there is an additional difficulty of a(More)