Enterococcus faecalis Endocarditis Severity in Rabbits Is Reduced by IgG Fabs Interfering with Aggregation Substance

Background: Enterococcus faecalis is a significant cause of infective endocarditis, an infection of the heart endothelium leading to vegetation formation (microbes, fibrin, platelets, and host cells attached to underlying endothelial tissue). Our previous research determined that enterococcal aggregation substance (AS) is an important virulence factor in causation of endocarditis, although endocarditis may occur in the absence of AS production. Production of AS by E. faecalis causes the organism to form aggregates through AS binding to enterococcal binding substance. In this study, we assessed the ability of IgGs and IgG Fabs against AS to provide protection against AS + E. faecalis endocarditis. Methodology/Principal Findings: When challenged with AS + E. faecalis, 10 rabbits actively immunized against AS + E. faecalis developed more significant vegetations than 9 animals immunized against AS 2 E. faecalis, and 9/10 succumbed compared to 2/9 (p,0.005), suggesting enhanced aggregation by IgG contributes significantly to disease. IgG antibodies against AS also enhanced enterococcal aggregation as tested in vitro. In contrast, Fab fragments of IgG from rabbits immunized against purified AS, when passively administered to rabbits (6/group) immediately before challenge with AS + E. faecalis, reduced total vegetation (endocarditis lesion) microbial counts (7.9610 6 versus 2.0610 5, p = 0.02) and size (40 mg versus 10, p = 0.05). In vitro, the Fabs prevented enterococcal aggregation. Conclusions/Significance: The data confirm the role of AS in infective endocarditis formation and suggest that use of Fab

Enhancing knowledge exchange and combination through HR practices: reflexivity as a translation process

Knowledge-intensive firms (KIFs) need to encourage their employees to engage in knowledge exchange and combination (KEC) so as to create the new knowledge that is core to their success. Human resource management (HRM) has the potential to play a key role in encouraging KEC but relatively little is known about the microprocesses through which HRM and KEC are linked. Based on a sample of 498 knowledge workers in 14 KIFs in the pharmaceutical and ICT sectors in Ireland and the UK, this study focuses on the knowledge workers themselves and their perceptions of how HR practices influence KEC. In so doing, we drill down into the micro-foundations of the proposed linkages between HRM and knowledge creation, proffering reflexivity as a translation process in understanding these linkages

Global modeling of aerosol dynamics: Model description, evaluation, and interactions between sulfate and nonsulfate aerosols

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95258/1/jgrd12001.pd