University of Memphis

About: University of Memphis is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 7710 authors who have published 20082 publications receiving 611618 citations. The organization is also known as: U of M.

Seeing The Big Picture: The Influence Of Industry, Diversification, And Business Strategy On Performance

Abstract: Much of the strategic management literature separates industry, corporate, and business levels of analysis, and empirical studies tend to examine these levels independently, not addressing how indu...

A gain-of-function mutation in the transcription factor Upc2p causes upregulation of ergosterol biosynthesis genes and increased fluconazole resistance in a clinical Candida albicans isolate.

Abstract: In the pathogenic yeast Candida albicans, the zinc cluster transcription factor Upc2p has been shown to regulate the expression of ERG11 and other genes involved in ergosterol biosynthesis upon exposure to azole antifungals. ERG11 encodes lanosterol demethylase, the target enzyme of this antifungal class. Overexpression of UPC2 reduces azole susceptibility, whereas its disruption results in hypersusceptibility to azoles and reduced accumulation of exogenous sterols. Overexpression of ERG11 leads to the increased production of lanosterol demethylase, which contributes to azole resistance in clinical isolates of C. albicans, but the mechanism for this has yet to be determined. Using genome-wide gene expression profiling, we found UPC2 and other genes involved in ergosterol biosynthesis to be coordinately upregulated with ERG11 in a fluconazole-resistant clinical isolate compared with a matched susceptible isolate from the same patient. Sequence analysis of the UPC2 alleles of these isolates revealed that the resistant isolate contained a single-nucleotide substitution in one UPC2 allele that resulted in a G648D exchange in the encoded protein. Introduction of the mutated allele into a drug-susceptible strain resulted in constitutive upregulation of ERG11 and increased resistance to fluconazole. By comparing the gene expression profiles of the fluconazole-resistant isolate and of strains carrying wild-type and mutated UPC2 alleles, we identified target genes that are controlled by Upc2p. Here we show for the first time that a gain-of-function mutation in UPC2 leads to the increased expression of ERG11 and imparts resistance to fluconazole in clinical isolates of C. albicans.

Potent protection against aflatoxin-induced tumorigenesis through induction of Nrf2-regulated pathways by the triterpenoid 1-[2-cyano-3-,12-dioxooleana-1, 9(11)-dien-28-oyl]imidazole

Abstract: Synthetic triterpenoid analogues of oleanolic acid are potent inducers of the phase 2 response as well as inhibitors of inflammation. We show that the triterpenoid, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), is a highly potent chemopreventive agent that inhibits aflatoxin-induced tumorigenesis in rat liver. The chemopreventive potency of CDDO-Im was evaluated by measuring inhibition of formation of putative preneoplastic lesions (glutathione S-transferase P positive foci) in the liver of rats exposed to aflatoxin B1. CDDO-Im produces an 85% reduction in the hepatic focal burden of preneoplastic lesions at 1 micromol/kg body weight and a >99% reduction at 100 micromol/kg body weight. CDDO-Im treatment reduces levels of aflatoxin-DNA adducts by approximately 40% to 90% over the range of 1 to 100 micromol/kg body weight. Additionally, changes in mRNA levels of genes involved in aflatoxin metabolism were measured in rat liver following a single dose of CDDO-Im. GSTA2, GSTA5, AFAR, and EPHX1 transcripts are elevated 6 hours following a 1 micromol/kg body weight dose of CDDO-Im. Microarray analysis using wild-type and Nrf2 knockout mice confirms that many phase 2 and antioxidant genes are induced in an Nrf2-dependent manner in mouse liver following treatment with CDDO-Im. Thus, low-micromole doses of CDDO-Im induce cytoprotective genes, inhibit DNA adduct formation, and dramatically block hepatic tumorigenesis. As a point of reference, oltipraz, an established modulator of aflatoxin metabolism in humans, is 100-fold weaker than CDDO-Im in this rat antitumorigenesis model. The unparalleled potency of CDDO-Im in vivo highlights the chemopreventive promise of targeting Nrf2 pathways with triterpenoids.

Lightweight deployment-aware scheduling for wireless sensor networks

Abstract: Wireless sensor networks consist of a large number of tiny sensors that have only limited energy supply. One of the major challenges in constructing such networks is to maintain long network lifetime as well as sufficient sensing areas. To achieve this goal, a broadly-used method is to turn off redundant sensors. In this paper, the problem of estimating redundant sensing areas among neighbouring wireless sensors is analysed. We present simple methods to estimate the degree of redundancy without the knowledge of location or directional information. We also provide tight upper and lower bounds on the probability of complete redundancy and on the average partial redundancy. With random sensor deployment, our analysis shows that partial redundancy is more realistic for real applications, as complete redundancy is expensive, requiring up to 11 neighbouring sensors to provide a 90 percent chance of complete redundancy. Based on the analysis, we propose a scalable Lightweight Deployment-Aware Scheduling (LDAS) algorithm, which turns off redundant sensors without using accurate location information. Simulation study demonstrates that the LDAS algorithm can reduce network energy consumption and provide desired QoS requirement effectively.

Perceived critical mass and the adoption of a communication technology

Abstract: Computer-based communication technologies are increasingly important to personal and organizational communication One important factor related to the adoption and diffusion of communication innovations is critical mass Critical mass influences the adoption and diffusion of interactive communication innovations, both through network externalities and through sustainability of the innovation Unfortunately, critical mass is difficult to measure and is typically only demonstrable after the critical mass point has been reached Potential adopters’ perceptions of critical mass also may be important to adoption decisions In this paper, we extend this thinking using a synthesis of the Theory of Reasoned Action and Diffusion of Innovation theory by developing a research model The model is empirically tested using survey data that are analyzed using partial least squares The focal innovation is instant messaging Results indicate that perceived critical mass influences use intentions directly and through perceptions of the characteristics of the innovation The perceived innovation characteristics impact attitude toward use, which in turn impacts use intentions The model predicts a sizable and significant portion of both attitudes and use intentions Further, perceived critical mass is able to explain a significant portion of the variance in each perceived innovation characteristic Implications for research and practice are discussed