Formation of Pickering Emulsions Stabilized via Interaction between Nanoparticles Dispersed in Aqueous Phase and Polymer End Groups Dissolved in Oil Phase

The influence of end groups of a polymer dissolved in an oil phase on the formation of a Pickering-type hydroxyapatite (HAp) nanoparticle-stabilized emulsion and on the morphology of HAp nanoparticle-coated microspheres prepared by evaporating solvent from the emulsion was investigated. Polystyrene (PS) molecules with varying end groups and molecular weights were used as model polymers. Although HAp nanoparticles alone could not function as a particulate emulsifier for stabilizing dichloromethane (oil) droplets, oil droplets could be stabilized with the aid of carboxyl end groups of the polymers dissolved in the oil phase. Lower-molecular-weight PS molecules containing carboxyl end groups formed small droplets and deflated microspheres, due to the higher concentration of carboxyl groups on the droplet/microsphere surface and hence stronger adsorption of the nanoparticles at the water/oil interface. In addition, Pickering-type suspension polymerization of styrene droplets stabilized by PS molecules containing carboxyl end groups successfully led to the formation of spherical HAp-coated microspheres

Identification of Pyridinium with Three Indole Moieties as an Antimicrobial Agent

A novel pyridinium with three indole moieties, tricepyridinium, was obtained from the culture of an <i>Escherichia coli</i> clone incorporating metagenomic libraries from the marine sponge <i>Discodermia calyx</i>. For the important structural elements of tricepyridinium to be investigated for antibacterial activity, tricepyridinium and its analogues were chemically synthesized. Tricepyridinium had antimicrobial activity, but not against <i>E. coli</i>, and cytotoxicity against P388 cells. Additional bioassays with its synthetic analogues revealed that the intriguing combination of the indole moieties, most likely derived from three tryptamines, as well as the pyridinium moiety were chiefly responsible for its potent biological activities

Mycolic Acid Containing Bacterium Stimulates Tandem Cyclization of Polyene Macrolactam in a Lake Sediment Derived Rare Actinomycete

Two novel macrolactams, dracolactams A and B, were identified from a combined-culture of <i>Micromonospora</i> species and a mycolic-acid containing bacterium (MACB). Their structures and stereochemistries were completely assigned, based on spectroscopic analyses and chemical derivatization. Both dracolactams were probably generated from a common macrolactam precursor produced by the <i>Micromonospora</i> species. In this combined-culture system, MACB is likely to activate cryptic oxidase genes in the <i>Micromonospora</i> species and induce the downstream polyene macrolactam cyclization

Niizalactams A–C, Multicyclic Macrolactams Isolated from Combined Culture of <i>Streptomyces</i> with Mycolic Acid-Containing Bacterium

A terrestrial bacterium, <i>Streptomyces</i> sp. NZ-6, produced niizalactams A–C (<b>1</b>–<b>3</b>), unprecedented di- and tricyclic macrolactams, by coculturing with the mycolic acid-containing bacterium <i>Tsukamurella pulmonis</i> TP-B0596. Their complete structures, including absolute configurations, were elucidated on the basis of spectroscopic data and chemical derivatization. Their unique skeletons are proposed to be biosynthesized from a common 26-membered macrolactam intermediate by S_N2 cyclization or an intramolecular Diels–Alder reaction

Bioinspired Mineralization Using Chondrocyte Membrane Nanofragments

Biomineralization involves complex processes and interactions between organic and inorganic matters, which are controlled in part by the cells. The objectives of this study were, first, to perform a systematic and ultrastructural investigation of the initial mineral formation during secondary ossification center of mouse femur based on material science and biology viewpoint, and then develop novel biomaterials for mineralization based on the in vivo findings. First, we identified the very initial mineral deposition at postnatal day 5 (P5) at the medial side of femur epiphysis by nanocomputed tomography. Initial minerals were found in the surroundings of hypertrophic chondrocytes. Interestingly, histological and immunohistochemical analyses showed that initial mineralization until P6 was based on chondrocyte activity only, i.e., it occurred in the absence of osteoblasts. Moreover, electron microscopy-based ultrastructural analysis showed that cell-secreted matrix vesicles were absent in the early steps of osteoblast-independent endochondral ossification. Instead, chondrocyte membrane nanofragments were found in the fibrous matrix surrounding the hypertrophic chondrocytes. EDS analysis and electron diffraction study indicated that cell membrane nanofragments were not mineralized material, and could be the nucleation site for the newly formed calcospherites. The phospholipids in the cell membrane nanofragments could be a source of phosphate for subsequent calcium phosphate formation, which initially was amorphous, and later transformed into apatite crystals. Finally, artificial cell nanofragments were synthesized from ATDC5 chondrogenic cells, and in vitro assays showed that these nanofragments could promote mineral formation. Taken together, these results indicated that cell membrane nanofragments were the nucleation site for mineral formation, and could potentially be used as material for manipulation of biomineralization

Running it through the body

Video data from three large captures of choreographic dance making was analyzed to determine if there is a difference between participant knowledge – the knowledge an agent acquires by being the cause of an action – and observer knowledge – the knowledge an observer acquires through close attention to someone else’s performance. The idea that there might be no difference has been challenged by recent findings about the action observation network and tacitly challenged by certain tenets in enactive perception. We explored why a choreographer ‘riff’s’ when appropriating and evaluating the movements of his dancers. By recruiting his body to help him cognize he is able to understand the possibilities of movement better than observation. He acquires participant knowledge

Enhancement of Cell-Based Therapeutic Angiogenesis Using a Novel Type of Injectable Scaffolds of Hydroxyapatite-Polymer Nanocomposite Microspheres

<div><h3>Background</h3><p>Clinical trials demonstrate the effectiveness of cell-based therapeutic angiogenesis in patients with severe ischemic diseases; however, their success remains limited. Maintaining transplanted cells in place are expected to augment the cell-based therapeutic angiogenesis. We have reported that nano-hydroxyapatite (HAp) coating on medical devices shows marked cell adhesiveness. Using this nanotechnology, HAp-coated poly(l-lactic acid) (PLLA) microspheres, named nano-scaffold (NS), were generated as a non-biological, biodegradable and injectable cell scaffold. We investigate the effectiveness of NS on cell-based therapeutic angiogenesis.</p> <h3>Methods and Results</h3><p>Bone marrow mononuclear cells (BMNC) and NS or control PLLA microspheres (LA) were intramuscularly co-implanted into mice ischemic hindlimbs. When BMNC derived from enhanced green fluorescent protein (EGFP)-transgenic mice were injected into ischemic muscle, the muscle GFP level in NS+BMNC group was approximate fivefold higher than that in BMNC or LA+BMNC groups seven days after operation. Kaplan-Meier analysis demonstrated that NS+BMNC markedly prevented hindlimb necrosis (<em>P</em><0.05 vs. BMNC or LA+BMNC). NS+BMNC revealed much higher induction of angiogenesis in ischemic tissues and collateral blood flow confirmed by three-dimensional computed tomography angiography than those of BMNC or LA+BMNC groups. NS-enhanced therapeutic angiogenesis and arteriogenesis showed good correlations with increased intramuscular levels of vascular endothelial growth factor and fibroblast growth factor-2. NS co-implantation also prevented apoptotic cell death of transplanted cells, resulting in prolonged cell retention.</p> <h3>Conclusion</h3><p>A novel and feasible injectable cell scaffold potentiates cell-based therapeutic angiogenesis, which could be extremely useful for the treatment of severe ischemic disorders.</p> </div

SEM image of NS (A) and marked cell adhesiveness to NS <i>in vitro</i> (B).

<p>(A) NS are microspheres approximately 100 µm in diameter (a). The NS surface uniformly coated with nano-scale hydroxyapatite (HAp) crystals was observed at different magnifications (low and high magnification in b and c, respectively). SEM image of an NS cross-section indicating a single layer of nano-scale HAp particles on the NS surface (d). (B) Murine BMNCs were incubated with LA (a) or NS (b, c) at 37°C for 8 h. Large numbers of BMNCs adhered to NS (b, c) but not to LA (a). Scale bars: 100 µm (A-a, B-a, B-b), 5 µm (B-c), 1 µm (A-b), 100 nm (A-c, A-d). Abbreviations: SEM, scanning electron microscopy; NS, nano-scaffolds; LA, unmodified PLLA microspheres; BMNCs, bone marrow mononuclear cells.</p