Injectable gellan gum-based nanoparticles-loaded system for the local delivery of vancomycin in osteomyelitis treatment

Infection spreading in the skeletal system leading to osteomyelitis can be prevented by the prolonged administration of antibiotics in high doses. However systemic antibiotherapy, besides its inconvenience and often low efficacy, provokes numerous side effects. Thus, we formulated a new injectable nanoparticle-loaded system for the local delivery of vancomycin (Vanc) applied in a minimally-invasive way. Vanc was encapsulated in poly(Llactide- co-glycolide) nanoparticles (NPs) by double-emulsification. The size (258 ± 11 nm), polydispersity index (0.240 ± 0.003) and surface potential (-25.9 ± 0.2 mV) of NPs were determined by dynamic light scattering and capillary electrophoresis measurements. They have a spherical morphology and a smooth topography as observed using atomic force microscopy. Vanc loading and encapsulation efficiencies were 8.8 ± 0.1 and 55.2 ± 0.5 %, respectively, based on fluorescence spectroscopy assays. In order to ensure injectability, NPs were suspended in gellan gum and cross-linked with $Ca^{2+}$; also a portion of dissolved antibiotic was added to the system. The resulting system was found to be injectable (extrusion force 11.3 ± 1.1 N), reassembled its structure after breaking as shown by rheology tests and ensured required burst release followed by sustained Vanc delivery. The system was cytocompatible with osteoblast-like MG-63 cells (no significant impact on cells’ viability was detected). Growth of Staphylococcus spp. reference strains and also those isolated from osteomyelitic joints was inhibited in contact with the injectable system. As a result we obtained a biocompatible system displaying ease of application (low extrusion force), self-healing ability after disruption, adjustable drug release and antimicrobial properties

Mechanical and processing characterization of effective behavior of wood-plastic composites by analytical and numerical simulation.

The development of a new composite that is compounded of natural fibres and of a low price polymer, such as HDPE or PP, began in the last decade of the past century. While this is a rather new material no attempts have been made to analytically describe and simulate mechanical properties of this material. There is also a great lack of knowledge in describing fine tuned processing parameters. Therefore, in the first part of this article micromechanical approach based upon Generalised Method of Cells (GMC) is introduced to simulate properties of injection moulded wood-plastic composite compounded of polypropylene (PP) or polystyrene (PS) and of wood or cellulose short fibres. Materials have first been scanned with an optical and electron microscope to determine average fibre properties and their scatter. These values are then used to determine elastic and plastic response of the composite alongside with its tensile strength and maximum elongation, where the Tsai-Hill failure criterion has been used. The results of the simulation are then compared to experimental data in order to evaluate practical usage of this method. The second part of the article is focused on the simulation of injection moulding where test specimens were injected and the search for optimum injection parameters was performed. Various mechanical and rheological tests were performed and in addition practical industrial products were injected to observe the impact of various natural fibres on the filling of the mould cavity. Every experiment and process was then compared to the numerical simulation in order to evaluate applicability of numerical simulations under real conditions. On the basis of these experiments detailed mould design guidelines are given

Characterization of Roseofilum reptotaenium

Black band disease (BBD) is a pathogenic microbial consortium dominated in terms of biomass by phycoerythrin-rich, gliding, filamentous cyanobacteria. Studies of BBD using molecular methods have shown that the 16S rRNA gene sequence of \u27Oscillatoria\u27 sp. is consistently found in BBD samples worldwide. The purpose of this study is to erect a new genus, Roseofilum gen. et sp. nov., encompassing these and other previously reported strains. Using a polyphasic approach we characterized two strains of BBD Oscillatoria isolated from BBD infected corals in the Caribbean. These strains have the ability to tolerate sulphide, anoxia, and pH values in the range from 4.5 to 10, with optimal growth at pH 6 to 8. Growth occurs by photoautotrophy, including sulphide-insensitive oxygenic photosynthesis, and mixotrophy but not by heterotrophy under dark aerobic or anaerobic conditions. Both strains synthesize microcystin-LR. Results of infectivity experiments carried out under controlled laboratory conditions showed that both strains are capable of initiating an infection on healthy coral that resembles in situ BBD. 16S rRNA gene sequence data place these strains into a highly supported clade with other strains identified as Oscillatoria sensu lato, yet clearly genetically distinct from the type, Oscillatoria princeps. Further, while the BBD strains share more morphological similarity with members of Phormidium, they are also distinct from this genus based on sequence data. Based on morphology, ecology, physiology, and phylogenetic distinctiveness, we propose the novel epithet Roseofilum reptotaenium

Association of non-heterocystous cyanobacteria with crop plants

Cyanobacteria have the ability to form associations with organisms from all domains of life, notably with plants, which they provide with fixed nitrogen, among other substances. This study was aimed at developing artificial associations between nonheterocystous cyanobacteria and selected crop plants. We isolated several non-heterocystous cyanobacteria from various rice fields. The cultures were tested for their capacity to produce the plant hormone indole-3- acetic acid (IAA), and the possible role of IAA in the association of cyanobacteria with seedling roots was evaluated. Axenic cultures were co-inoculated with 10-day-old plant seedlings of Triticum aestivum, Vigna radiata and Pisum sativum and incubated for 1 week. Cyanobacterial association with the roots of these seedlings was quantified by measuring chlorophyll-a. Cyanobacterial associ by light microscopy as well as by confocal laser scanning microscopy (CLSM). Based on sequence analysis of the 16S rRNA gene, the isolates were identified as Synechocystis sp., Chroococcidiopsis sp., Leptolyngbya sp., and Phormidium sp. CLSM observations revealed the intimate association of cyanobacteria with the seedling roots as well as invasion of the roots and root cells. Strains producing IAA were more efficient in the colonization of the roots than those that lacked this ability. IAA-produ a tryptophan-dependent pathway, and these cyanobacteria showed IAA synthesis activity in the presence of roots in media lacking tryptophan. Based on the results of this study, we conclude that nonheterocystous cyanobacteria also have the potential for use in agriculture to improve the growth and yield of crop plants that do not naturally form associations with cyanobacteri