Decoupling management and technological innovations: Resolving the individualism-collectivism controversy

This study aims to resolve the contradictory previous research findings on the relationship between individualism–collectivism and innovation. We draw on innovation theory and relate to the difference between non-technological (management) and technological innovation types as well as to the distinction between exploration and exploitation (invention and commercialization of technological innovations). Using Community Innovation Survey (CIS) 2006 micro data for innovation at the organizational level in 13 countries – along with Hofstede (1980, 2001), GLOBE (2005), and Schwartz (2006) scores for individualism–collectivism – we apply Hierarchical Linear Modeling (HLM). The results indicate that individualism is positively related to the invention phase, whereas collectivism is beneficial for the commercialization of innovative ideas. Furthermore, in collectivistic cultures, management innovation plays a more important stimulating role in enhancing technological innovation than it does in individualistic ones. This provides the managers with an idea of when innovation processes in their companies would be more favorable versus detrimental

A Rapid Fluorescence-Based Microplate Assay to Investigate the Interaction of Membrane Active Antimicrobial Peptides with Whole Gram-Positive Bacteria

Background: Membrane-active antimicrobial peptides (AMPs) are interesting candidates for the development of novel antimicrobials. Although their effects were extensively investigated in model membrane systems, interactions of AMPs with living microbial membranes are less known due to their complexity. The aim of the present study was to develop a rapid fluorescence-based microplate assay to analyze the membrane effects of AMPs in whole Staphylococcus aureus and Staphylococcus epidermidis. Methods: Bacteria were exposed to bactericidal and sub-inhibitory concentrations of two membrane-active AMPs in the presence of the potential-sensitive dye 3,3′-dipropylthiadicarbocyanine iodide (diSC3(5)) and the DNA staining dye propidium iodide (PI), to simultaneously monitor and possibly distinguish membrane depolarization and membrane permeabilization. Results: The ion channel-forming gramicidin D induced a rapid increase of diSC3(5), but not PI fluorescence, with slower kinetics at descending peptide concentrations, confirming killing due to membrane depolarization. The pore-forming melittin, at sub-MIC and bactericidal concentrations, caused, respectively, an increase of PI fluorescence in one or both dyes simultaneously, suggesting membrane permeabilization as a key event. Conclusions: This assay allowed the distinction between specific membrane effects, and it could be applied in the mode of action studies as well as in the screening of novel membrane-active AMPs

Structure and bactericidal activity of an antibiotic dodecapeptide purified from bovine neutrophils.

Cytoplasmic granules of neutrophils store a variety of cationic polypeptides, which exert in vitro a potent antibacterial action and are potentially involved in host defense mechanisms. From an acid extract of bovine neutrophil granules we have purified over 2,000-fold a dodecapeptide exhibiting bactericidal activity against both Escherichia coli and Staphylococcus aureus at 10(-7)-10(-5) M concentration. The purification procedure involved only two steps of ion-exchange and reversed-phase chromatography. The peptide, named bactenecin, has the amino acid sequence, Arg-Leu-Cys-Arg-Ile-Val-Val-Ile-Arg-Val-Cys-Arg, maintained in a cyclic structure by a disulfide bond between the two cysteine residues. Computer modeling of the dodecapeptide resulted in a conformation in which the chain adopts an antiparallel extended structure forming a gamma turn at residue 7

Exploring the biological properties and therapeutic potential of antimicrobial peptides

The researchers involved in the Trans2Care project at the Department of Medical and Biological Sciences of the University of Udine investigate the biological properties of the antimicrobial peptides (AMPs) of the immune system and their therapeutic potential for human and veterinary application. In addition to potent and broad-spectrum antimicrobial activities, some AMPs display anti-inflammatory and immunomodulatory effects and hold promise as novel antiinfective agents combining antibiotic and immunostimulating properties. A detailed knowledge of their physicochemical, biological and pharmacological properties and of their impact on clinical settings is an important prerequisite to this end. The Trans2Care project offers an invaluable opportunity to share knowledge, technical expertise and laboratory facilities to achieve a better understanding of the biological features and therapeutic potential of AMPs

Mechanistic and functional studies of the interaction of a proline-rich antimicrobial peptide with mammalian cells.

Mammalian antimicrobial peptides provide rapid defense against infection by inactivating pathogens and by influencing the functions of cells involved in defense responses. Although the direct antibacterial properties of these peptides have been widely characterized, their multiple effects on host cells are only beginning to surface. Here we investigated the mechanistic and functional aspects of the interaction of the proline-rich antimicrobial peptide Bac7(1-35) with mammalian cells, as compared with a truncated analog, Bac7(5-35), lacking four critical N-terminal residues (RRIR) of the Bac7(1-35) sequence. By using confocal microscopy and flow cytometry, we showed that although the truncated analog Bac7(5-35) remains on the cell surface, Bac7(1-35) is rapidly taken up into 3T3 and U937 cells through a nontoxic energy- and temperature-dependent process. Cell biology-based assays using selective endocytosis inhibitors and spectroscopic and surface plasmon resonance studies of the interaction of Bac7(1-35) with phosphatidylcholine/cholesterol model membranes collectively suggest the concurrent contribution of macropinocytosis and direct membrane translocation. Structural studies with model membranes indicated that membrane-bound Bac7(5-35) is significantly more aggregated than Bac7(1-35) due to the absence of the N-terminal cationic cluster, thus providing an explanation for hampered cellular internalization of the truncated form. Further investigations aimed to reveal functional implications of intracellular uptake of Bac7(1-35) demonstrated that it correlates with enhanced S phase entry of 3T3 cells, indicating a novel function for this proline-rich peptide

Covalent grafting of titanium with a cathelicidin peptide produces an osteoblast compatible surface with antistaphylococcal activity

Bacterial infection of orthopaedic implants, often caused by Staphylococcus species, may ultimately lead to implant failure. The development of infection-resistant, osteoblast-compatible biomaterials could represent an effective strategy to prevent bacterial colonization of implants, reducing the need for antibiotics. In this study, the widely used biomaterial titanium was functionalized with BMAP27(1-18), an \uf061-helical cathelicidin antimicrobial peptide that retains potent staphylocidal activity when immobilized on agarose beads. A derivative bearing a short spacer with a free thiol at the N-terminus was coupled to silanized titanium disks via thiol-maleimide chemistry. Tethering was successful, as assessed by Contact angle, Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), and X-ray Photoelectron Spectroscopy (XPS), with an average surface mass density of 456 ng/cm2 and a layer thickness of 3 nm. The functionalized titanium displayed antimicrobial properties against a reference strain of Staphylococcus epidermidis with well-known biofilm forming capability. Reduction of bacterial counts and morphological alterations of adhering bacteria, upon 2h incubation, indicate a rapid contact-killing effect. The immobilized peptide was not toxic to osteoblasts, which adhered and spread better on functionalized titanium when co-cultured with bacteria, compared to non-coated surfaces. Results suggest that functionalization of titanium with BMAP27(1-18) could be promising for prevention of bacterial colonization in bone graft applications

Bovine Neutrophil Antibiotic Peptides and Their Precursors: Structure and Role in Innate Immunity

Four peptides were characterized in extracts of bovine neutrophil granules: an Arg-rich dodecapeptide, maintained in a cyclic structure by a disulfide bridge; a Trp-rich tridecapeptide named indo- licidin; and two 43- and 59 amino acids long peptides, named Bac5 and Bac7, with frequent repeats of the triplets Arg-Pro-Pro and Pro-Arg-Pro, respectively. The full length cDNA of the first three of these peptides was characterized recently. Sequence analysis showed that the prosequences of the predicted precursors of all the three peptides are highly identical and exhibited also a remarkable similarity to cathelin, a porcine inhibitor of cathepsin L. Purified proBacö actually proved in in vitro assays to inhibit cathepsin L, but not other cysteine proteinases such as cathepsin B. Unlike proBacö, proBac7 is selectively chemotactic to monocytes. Several fragments of Bac5 and Bac7 (from 6 to 35 residues) were synthesized by the Fmoc method. The results of antibacterial assays show that the N-terminal portion, the most cationic one in both Bac5 and Bac7, is essential for the antimicrobial activity and that the minimal length necessary to arrest the growth of susceptible bacteria is 18-20 residues

Peptides and Peptidomimetics for Antimicrobial Drug Design

The purpose of this paper is to introduce and highlight a few classes of traditional antimicrobial peptides with a focus on structure-activity relationship studies. After first dissecting the important physiochemical properties that influence the antimicrobial and toxic properties of antimicrobial peptides, the contributions of individual amino acids with respect to the peptides antibacterial properties are presented. A brief discussion of the mechanisms of action of different antimicrobials as well as the development of bacterial resistance towards antimicrobial peptides follows. Finally, current efforts on novel design strategies and peptidomimetics are introduced to illustrate the importance of antimicrobial peptide research in the development of future antibiotics

Exponential random graph models for management research: a case study of executive recruitment

We introduce a recent development in the statistical analysis of relational data that offers rigorous discrimination of a variety of structural and behavioural effects of interest to management research. Exponential Random Graph Models (ERGMs) account for the highly interdependent nature of network data that is problematic for the predominant inferential statistical analysis used in management research. We illustrate the value of the approach with an application focused on executive recruitment by large UK firms, modelling migrations of managers among firms as a network of relationships. We find rigorous statistical support for the influences of industry origin in executive recruitment, particularly in relation to legal and accounting activities. The flexibility and sophisticated relational variables available in the models offer considerable analytical power of value to a wide range of management applications

Cathelicidin-like Helminth Defence Molecules (HDMs) Absence of Cytotoxic, Anti-microbial and Anti-protozoan Activities Imply a Specific Adaptation to Immune Modulation

Host defence peptides (HDPs) are expressed throughout the animal and plant kingdoms. They have multifunctional roles in the defence against infectious agents of mammals, possessing both bactericidal and immune-modulatory activities. We have identified a novel family of molecules secreted by helminth parasites (helminth defence molecules; HDMs) that exhibit similar structural and biochemical characteristics to the HDPs. Here, we have analyzed the functional activities of four HDMs derived from Schistosoma mansoni and Fasciola hepatica and compared them to human, mouse, bovine and sheep HDPs. Unlike the mammalian HDPs the helminth-derived HDMs show no antimicrobial activity and are non-cytotoxic to mammalian cells (macrophages and red blood cells). However, both the mammalian- and helminth-derived peptides suppress the activation of macrophages by microbial stimuli and alter the response of B cells to cytokine stimulation. Therefore, we hypothesise that HDMs represent a novel family of HDPs that evolved to regulate the immune responses of their mammalian hosts by retaining potent immune modulatory properties without causing deleterious cytotoxic effects. © 2013 Thivierge et al