Double suicide genes selectively kill human umbilical vein endothelial cells

<p>Abstract</p> <p>Background</p> <p>To construct a recombinant adenovirus containing CDglyTK double suicide genes and evaluate the killing effect of the double suicide genes driven by kinase domain insert containing receptor (KDR) promoter on human umbilical vein endothelial cells.</p> <p>Methods</p> <p>Human KDR promoter, <it>Escherichia coli </it>(<it>E. coli</it>) cytosine deaminase (CD) gene and the herpes simplex virus-thymidine kinase (TK) gene were cloned using polymerase chain reaction (PCR). Plasmid pKDR-CDglyTK was constructed with the KDR promoter and CDglyTK genes. A recombinant adenoviral plasmid AdKDR-CDglyTK was then constructed and transfected into 293 packaging cells to grow and harvest adenoviruses. KDR-expressing human umbilical vein endothelial cells (ECV304) and KDR-negative liver cancer cell line (HepG2) were infected with the recombinant adenoviruses at different multiplicity of infection (MOI). The infection rate was measured by green fluorescent protein (GFP) expression. The infected cells were cultured in culture media containing different concentrations of prodrugs ganciclovir (GCV) and/or 5-fluorocytosine (5-FC). The killing effects were measured using two different methods, i.e. annexin V-FITC staining and terminal transferase-mediated dUTP nick end-labeling (TUNEL) staining.</p> <p>Results</p> <p>Recombinant adenoviruses AdKDR-CDglyTK were successfully constructed and they infected ECV304 and HepG2 cells efficiently. The infection rate was dependent on MOI of recombinant adenoviruses. ECV304 cells infected with AdKDR-CDglyTK were highly sensitive to GCV and 5-FC. The cell survival rate was dependent on both the concentration of the prodrugs and the MOI of recombinant adenoviruses. In contrast, there were no killing effects in the HepG2 cells. The combination of two prodrugs was much more effective in killing ECV304 cells than GCV or 5-FC alone. The growth of transgenic ECV304 cells was suppressed in the presence of prodrugs.</p> <p>Conclusion</p> <p>AdKDR-CDglyTK/double prodrog system may be a useful method for suppressing tumor angiogenesis.</p

A terminal assessment of stages theory : introducing a dynamic states approach to entrepreneurship

Stages of Growth models were the most frequent theoretical approach to understanding entrepreneurial business growth from 1962 to 2006; they built on the growth imperative and developmental models of that time. An analysis of the universe of such models (N=104) published in the management literature shows no consensus on basic constructs of the approach, nor is there any empirical confirmations of stages theory. However, by changing two propositions of the stages models, a new dynamic states approach is derived. The dynamic states approach has far greater explanatory power than its precursor, and is compatible with leading edge research in entrepreneurship

Metal-macrofauna interactions determine microbial community structure and function in copper contaminated sediments

Peer reviewedPublisher PD

Professional superheroes: Are changes in higher education stretching hospitality management academics' professionalism to the limit?

The higher education sector in the UK has changed considerably over the last few decades, but particularly in the last ten years. As a result, working practices are such that hospitality management academics are ‘stretching’ their professional orientations in-order to accommodate increased bureaucratic and market-focused requirements, which in-turn impacts upon their professionalism. A typology is introduced in this empirical paper which is used to gain a deeper understanding of professionalism and professional orientations of this vocational academic group in the context of a changed higher education working environment

Exploring entrepreneurial learning: A comparative study of technology development projects

In this paper, we report findings from a comparative study of factors that influence the learning process that underlies entrepreneurial innovation, as entrepreneurs move from an initial intuition to a well-developed new product or service. Evidence from our comparative study highlights the self-reinforcing effect of prior related knowledge, perceived incentives and the degree of control on the allocation of entrepreneurs' limited time, attention and resources. Combining theory and evidence from our study, we propose an interpretative model that suggests that innovation in entrepreneurial ventures rests on self-reinforcing learning cycles that lead entrepreneurs to dedicate increasing resources to the exploration of some opportunities at the expense of others, following a sensemaking process affected by their previous knowledge and their degree of involvement in the projects

Determinants, causal connections and outcomes of corporate technology licensing : a systematic review and research agenda

Exchanges in markets for technology (MfT) have grown rapidly in recent years. MfT involve transactions for the use, diffusion and creation of technology. In this article we conduct a systematic review of the emerging market for technology literature and examine one of its most important aspects, corporate technology licensing. Using thematic analysis, we systematically review 78 papers published in 29 journals over 30 years covering the academic disciplines of technology/knowledge management, strategic management, entrepreneurship, innovation management and industrial economics. Based on this analysis, we present an organizing framework for the most prominent determinants, causal connections and outcomes of technology licensing research to date, and identify a research agenda highlighting important avenues for future research in this domai

Absorptive capacity and ambidexterity in R&D : linking technology alliance diversity and firm innovation

The aim of this study is to examine how firms realize the benefits associated with a diverse range of technology alliances. We propose and test the hypothesis that firms’ knowledge combination capabilities mediate the relationship between technology alliance diversity innovation. Using panel data for Spanish manufacturing companies during the period 2004-2011, we provide evidence that firms’ absorptive capacity and ambidexterity in R&D serve as mediating mechanisms between technology alliance diversity and innovative performance Our study advances the literature on technology alliances by showing how firms use their portfolios of technology alliances to form their combination capabilities, and subsequently, to enhance innovation outcomes

X-ray and cryo-EM structures of inhibitor-bound cytochrome bc₁ complexes for structure-based drug discovery

Cytochrome bc₁, a dimeric multi-subunit electron-transport protein embedded in the inner mitochondrial membrane, is a major drug target for the treatment and prevention of malaria and toxoplasmosis. Structural studies of cytochrome bc₁ from mammalian homologues co-crystallized with lead compounds have underpinned structure-based drug design to develop compounds with higher potency and selectivity. However, owing to the limited amount of cytochrome bc₁ that may be available from parasites, all efforts have been focused on homologous cytochrome bc₁ complexes from mammalian species, which has resulted in the failure of some drug candidates owing to toxicity in the host. Crystallographic studies of the native parasite proteins are not feasible owing to limited availability of the proteins. Here, it is demonstrated that cytochrome bc₁ is highly amenable to single-particle cryo-EM (which uses significantly less protein) by solving the apo and two inhibitor-bound structures to ∼4.1 Å resolution, revealing clear inhibitor density at the binding site. Therefore, cryo-EM is proposed as a viable alternative method for structure-based drug discovery using both host and parasite enzymes