Lappas C.M.,Lebanon Valley College
Food and Chemical Toxicology | Year: 2015
Due to their characteristic physical, chemical and optical properties, titanium dioxide and silver nanoparticles are attractive tools for use in a wide range of applications. The use of nanoparticles for biological applications is, however, dependent upon their biocompatibility with living cells. Because of the importance of inflammation as a modulator of human health, the safe and efficacious in vivo use of titanium dioxide and silver nanoparticles is inherently linked to a favorable interaction with immune system cells. However, both titanium dioxide and silver nanoparticles have demonstrated potential to exert immunomodulatory and immunotoxic effects. Titanium dioxide and silver nanoparticles are readily internalized by immune system cells, may accumulate in peripheral lymphoid organs, and can influence multiple manifestations of immune cell activity. Although the factors influencing the biocompatibility of titanium dioxide and silver nanoparticles with immune system cells have not been fully elucidated, nanoparticle core composition, size, concentration and the duration of cell exposure seem to be important. Because titanium dioxide and silver nanoparticles are widely utilized in pharmaceutical, commercial and industrial products, it is vital that their effects on human health and immune system function be more thoroughly evaluated. © 2015 Elsevier Ltd.
Lappas C.M.,Lebanon Valley College |
Lappas N.T.,George Washington University
Cellular Immunology | Year: 2012
d-Limonene, a cyclic terpene that is a major component of several plant essential oils, is used widely as an additive in perfumes, soaps, foods and beverages, and has also been shown to possess chemopreventative and chemotherapeutic activity. A limited number of studies have been conducted investigating the effect of d-limonene on immune system function. We show that d-limonene and its metabolites limonene-1-2-diol and perillic acid inhibit the production by CD3+CD4+ T cells of IFN-γ, IL-2, TNF-α, IL-4 and IL-13, and the production by CD3+CD8+ T cells of IFN-γ, IL-2, and TNF-α. Additionally, the upregulation of CD25, CD69 and CD40L by activated T lymphocytes is modulated by d-limonene, limonene-1-2-diol and perillic acid treatment. Furthermore, high concentrations of d-limonene, limonene-1-2-diol and perillic acid induce T lymphocyte cell death. These data suggest that d-limonene possesses immunomodulatory activity that must be considered when utilizing the compound for therapeutic or commercial purposes. © 2012 Elsevier Inc.
Hong W.,Hong Kong University of Science and Technology |
Hong W.,University of Nevada, Las Vegas |
Chan F.K.Y.,France Business School |
Thong J.Y.L.,Hong Kong University of Science and Technology |
And 2 more authors.
Information Systems Research | Year: 2014
This paper discusses the value of context in theory development in information systems (IS) research. We examine how prior research has incorporated context in theorizing and develop a framework to classify existing approaches to contextualization. In addition, we expound on a decomposition approach to contextualization and put forth a set of guidelines for developing context-specific models. We illustrate the application of the guidelines by constructing and comparing various context-specific variations of the technology acceptance model (TAM)-i.e., the decomposed TAM that incorporates interaction effects between context-specific factors, the extended TAM with context-specific antecedents, and the integrated TAM that incorporates mediated moderation and moderated mediation effects of context-specific factors. We tested the models on 972 individuals in two technology usage contexts: a digital library and an agile Web portal. The results show that the decomposed TAM provides a better understanding of the contexts by revealing the direct and interaction effects of contextspecific factors on behavioral intention that are not mediated by the TAM constructs of perceived usefulness and perceived ease of use. This work contributes to the ongoing discussion about the importance of context in theory development and provides guidance for context-specific theorizing in IS research. © 2014 INFORMS.
Lappas C.M.,Lebanon Valley College
Cellular and Molecular Immunology | Year: 2015
Cytokinins are plant hormones that play an integral role in multiple aspects of plant growth and development. The biological functions of cytokinins in mammalian systems are, however, largely uncharacterized. The naturally occurring cytokinin zeatin riboside has recently been demonstrated to activate the mammalian adenosine A2A receptor, which is broadly expressed by various cell types including immune system cells, with the activation of the A2AR playing a role in the regulation of cells involved in both innate and adaptive immunity. We show for the first time that zeatin riboside modulates mammalian immune system activity via an A2AR-dependent mechanism. Specifically, zeatin riboside treatment induces the production of cyclic adenosine monophosphate (cAMP) by T lymphocytes and inhibits the production by CD3 + CD4 + T cells of interferon (IFN)-γ, IL-2, tumor-necrosis factor (TNF)-α, IL-4 and IL-13, and the production by CD3 + CD8 + T cells of IFN-γ, IL-2 and TNF-α. Additionally, the upregulation of CD25, CD69 and CD40L by activated T lymphocytes is modulated by zeatin riboside. Zeatin riboside treatment also potently inhibits thioglycollate-induced peritoneal leukocytosis. The immunomodulatory activities of zeatin riboside are blocked by co-treatment with the selective A2AR antagonist ZM241385. These data suggest that zeatin riboside possesses therapeutic potential as a mammalian immunomodulatory agent. © 2015 CSI and USTC.
Perry N.,Lebanon Valley College
Ecological Economics | Year: 2010
Using the Noah's Ark problem - the problem of efficiently allocating limited funds to conserve biodiversity - the standard economic approach to endangered species conservation constructs a human-centered biodiversity by favoring species directly valuable to humans. I analyze this approach and draw on the functional ecology literature to offer an alternative emphasizing the role species play in their ecosystems. The aim is to create a working ecosystem on the Ark rather than a collection of charismatic and distinct species. To do so, I construct a new measure of a species' ecological importance and an ecological objective appropriate for cost-effective resource allocation. The ecological approach fundamentally changes the notion of species-value from a direct value based on a species' appearance or taxonomic difference to an indirect value based on a species' ecological role in its ecosystem. In the process, 'populations' of species become the fundamental unit of biodiversity rather than 'species', and abiotic processes also possess value. When compared to the economic approach, the ecological approach prioritizes different species for the Ark and achieves superior economic outcomes in all but the mythical Noah's Ark scenario where interactions are non-existent. The analysis challenges the approach of US endangered species legislation and I call for a reformulation based on endangered ecological interactions. © 2009 Elsevier B.V. All rights reserved.