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The present study aims to develop an implant coating releasing novel antimicrobial agents to prevent biomaterial-associated infections. The LL-37-derived synthetic antimicrobial and anti-biofilm peptides (SAAP)-145 and SAAP-276 exhibit potent bactericidal and anti-biofilm activities against clinical and multidrug-resistant Staphylococcus aureus strains by rapid membrane permeabilization, without inducing resistance. Injection of SAAP-145, but not SAAP-276, along subcutaneous implants in mice reduces S. aureus implant colonization by approximately 2 log, but does not reduce bacterial numbers in surrounding tissue. To improve their efficacy, SAAP-145 and SAAP-276 are incorporated in a polymer-lipid encapsulation matrix (PLEX) coating, providing a constant release of 0.6% daily up to 30 d after an initial burst release of >50%. In a murine model for biomaterial-associated infection, SAAP-145-PLEX and SAAP-276-PLEX coatings significantly reduce the number of culture positive implants and show ≥3.5 and ≥1.5 log lower S. aureus implant and tissue colonization, respectively. Interestingly, these peptide coatings are also highly effective against multidrug-resistant S. aureus, both reducing implant colonization by ≥2 log. SAAP-276-PLEX additionally reduces tissue colonization by 1 log. Together, the peptide-releasing PLEX coatings hold promise for further development as an alternative to coatings releasing conventional antibiotics to prevent biomaterial-associated infections. [ABSTRACT FROM AUTHOR]

The antibacterial activity of honey has been known since the 19th century. Recently, the potent activity of honey against antibiotic-resistant bacteria has further increased the interest for application of honey, but incomplete knowledge of the antibacterial activity is a major obstacle for clinical applicability. The high sugar concentration, hydrogen peroxide, and the low pH are well-known antibacterial factors in honey and more recently, methylglyoxal and the antimicrobial peptide bee defensin-1 were identified as important antibacterial compounds in honey. The antibacterial activity of honey is highly complex due to the involvement of multiple compounds and due to the large variation in the concentrations of these compounds among honeys. The current review will elaborate on the antibacterial compounds in honey. We discuss the activity of the individual compounds, their contribution to the complex antibacterial activity of honey, a novel approach to identify additional honey antibacterial compounds, and the implications of the novel developments for standardization of honey for medical applications. © 2011 IUBMB IUBMB Life, 2011.s [ABSTRACT FROM AUTHOR]

With the rise in prevalence of antibioticresistant bacteria, honey is increasingly valued for its antibacterial activity. To characterize all bactericidal factors in a medical-grade honey, we used a novel approach of successive neutralization of individual honey bactericidal factors. All bacteria tested, including Bacillus subtilis, methicillin-resistant Staphylococcus aureus, extended-spectrum β-lactamase producing Escherichia coli, ciprofloxacin-resistant Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus faecium, were killed by 10-20% (v/v) honey, whereas ≥40% (v/v) of a honey-equivalent sugar solution was required for similar activity. Honey accumulated up to 5.62 ± 0.54 mM H2O2 and contained 0.25 ± 0.01 mM methylglyoxal (MGO). After enzymatic neutralization of these two compounds, honey retained substantial activity. Using B. subtilis for activity-guided isolation of the additional antimicrobial factors, we discovered bee defensin-1 in honey. After combined neutralization of H2O2, MGO, and bee defensin-1, 20% honey had only minimal activity left, and subsequent adjustment of the pH of this honey from 3.3 to 7.0 reduced the activity to that of sugar alone. Activity against all other bacteria tested depended on sugar, H2O2, MGO, and bee defensin-1. Thus, we fully characterized the antibacterial activity of medical-grade honey. [ABSTRACT FROM AUTHOR]

1. In social insects, reproductive success and survival of the colony critically depend on the colony's ability to efficiently allocate workers to the various tasks which need to be performed. In bumblebees, workers show a large variation of body size within a colony. Large workers tend to leave the nest and forage for nectar and pollen, whereas small workers stay inside the nest and fulfill nest duties. It was speculated that size-related differences of the sensory system might contribute to alloethism found in bumblebee colonies. 2. In the first part, we investigated how body size determines eye morphology. We measured several eye parameters of Bombus terrestris workers and drones. In both, workers and drones, larger individuals had larger eyes with larger facet diameters, more ommatidia and larger ocelli. At similar body size, drones exhibited larger eyes and ocelli compared to workers. Due to theoretical considerations, we predict that large individuals with large eyes should be better able to operate in illumination conditions of lower intensity than small individuals, since ommatidial sensitivity is proportional to the square of facet diameter. 3. In the second part, we tested this prediction. In a behavioural experiment, we first caught bumblebees of various sizes in the field and then determined the lowest light intensity level at which they are just able to fly under controlled laboratory conditions. We tested workers of B. terrestris and B. pascuorum, and workers and drones of B. lapidarius. Large bumblebees were able to fly under lower light levels compared to small bees, with light intensity thresholds ranging from 1·1 to 5·5 lux. 4. Our results indicate that the increased light sensitivity of the visual system of large bumblebees allows them to fly under poor light conditions, for example, very early in the morning or late at dusk. This is of potential benefit to the survival of a bumblebee colony since flowers that open early in the morning usually have accumulated a relatively high amount of nectar and pollen throughout the night, and large bumblebees can utilize these resources earlier than most other bees. Thus, our findings have important implications for the understanding of the functional significance and evolution of alloethism in bumblebee colonies. [ABSTRACT FROM AUTHOR]

The participation of cell subpopulations in the expression of leucocyte migration inhibition factor (LMIF) in response to Concanavalin A and Protein A was evaluated for cells isolated from the peripheral blood of five healthy subjects. LMIF activity could not be attributed to the function of T cells, B enriched cells, or monocytes acting alone, or to a combination of B enriched cells and monocytes. The LMIF response was the result of a collaborative event that occurred between T cells and B enriched cells, or between T cells and monocytes. [ABSTRACT FROM AUTHOR]