Single-mode termination of phage transcriptions, disclosing bacterial adaptation for facilitated reinitiations.

Bacterial and bacteriophage RNA polymerases (RNAPs) have divergently evolved and share the RNA hairpin-dependent intrinsic termination of transcription. Here, we examined phage T7, T3 and SP6 RNAP terminations utilizing the single-molecule fluorescence assays we had developed for bacterial terminations. We discovered the phage termination mode or outcome is virtually single with decomposing termination.

Compatibility of termination mechanisms in bacterial transcription with inference on eukaryotic models.

Transcription termination has evolved to proceed through diverse mechanisms. For several classes of terminators, multiple models have been debatably proposed. Recent single-molecule studies on bacterial terminators have resolved several long-standing controversies.

Transcriptional pause extension benefits the stand-by rather than catch-up Rho-dependent termination.

Transcriptional pause is essential for all types of termination. In this single-molecule study on bacterial Rho factor-dependent terminators, we confirm that the three Rho-dependent termination routes operate compatibly together in a single terminator, and discover that their termination efficiencies depend on the terminational pauses in unexpected ways. Evidently, the most abundant route is that Rho binds nascent RNA first and catches up with paused RNA polymerase (RNAP) and this catch-up Rho mediates simultaneous releases of transcript RNA and template DNA from RNAP.

Rho-dependent transcription termination proceeds via three routes.

Rho is a general transcription termination factor in bacteria, but many aspects of its mechanism of action are unclear. Diverse models have been proposed for the initial interaction between the RNA polymerase (RNAP) and Rho (catch-up and stand-by pre-terminational models); for the terminational release of the RNA transcript (RNA shearing, RNAP hyper-translocation or displacing, and allosteric models); and for the post-terminational outcome (whether the RNAP dissociates or remains bound to the DNA). Here, we use single-molecule fluorescence assays to study those three steps in transcription termination mediated by E.

Porous calcium phosphate-collagen composite microspheres for effective growth factor delivery and bone tissue regeneration.

Microspheres are beneficial for filling defects of various shapes and provide a large surface area for cell attachment. Porous microspheres have attracted particular attention because they can deliver cells and bioactive molecules such as growth factors. In this study, BCP-collagen composite microspheres were developed for growth factor delivery in bone regeneration.

ATAD5 promotes replication restart by regulating RAD51 and PCNA in response to replication stress.

Maintaining stability of replication forks is important for genomic integrity. However, it is not clear how replisome proteins contribute to fork stability under replication stress. Here, we report that ATAD5, a PCNA unloader, plays multiple functions at stalled forks including promoting its restart.

Reduced fibrous capsule formation at nano-engineered silicone surfaces via tantalum ion implantation.

Although the design of more biocompatible polymeric implants has been studied for decades, their intended functionality continues to be impaired by the response of the host tissue to foreign bodies at the tissue-implant interface. In particular, the formation and contracture of fibrous capsules prevent the intimate integration of an implant with surrounding tissues, which leads to structural deformation of the implants and persistent discomfort and pain. We report a new surface nano-engineered silicone implant that reduces fibrous capsule formation and improves the biocompatibility of it via sputtering-based plasma immersion ion implantation (S-PIII).

In-vitro blood and vascular compatibility of sirolimus-eluting organic/inorganic hybrid stent coatings.

The surface characteristics of coronary stents play a pivotal role in inhibiting in-stent restenosis and late-stent thrombosis. In this study, a sol-gel-derived silica xerogel-chitosan hybrid coating was applied to Co-Cr stent and was reported, for the first time, as a biocompatible drug delivery tool in vascular stent application. A dense and uniform chitosan-silica xerogel hybrid coating (<1-μm thick) was applied on bare Co-Cr material.

Enhanced Osseointegration Ability of Poly(lactic acid) via Tantalum Sputtering-Based Plasma Immersion Ion Implantation.

Poly(lactic acid) (PLA) is the most utilized biodegradable polymer in orthopedic implant applications because of its ability to replace regenerated bone tissue via continuous degradation over time. However, the poor osteoblast affinity for PLA results in a high risk of early implant failure, and this issue remains one of the most difficult challenges with this technology. In this study, we demonstrate the use of a new technique in which plasma immersion ion implantation (PIII) is combined with a conventional DC magnetron sputtering.

Use of thioglycerol on porous polyurethane as an effective theranostic capping agent for bone tissue engineering.

Thiolated biodegradable polyurethane (TG-DPU) was synthesized using a one-pot reaction with thioglycerol adopted as a functionalized chain extender. After characterization of the chemical structure of TG-DPU using proton nuclear magnetic resonance spectroscopy, bone morphogenetic protein (BMP-2) was loaded in the TG-DPU under oxidative conditions to form disulfides between the free thiol of TG-DPU and BMP-2. The interaction between TG-DPU and BMP-2, so-called bioconjugates, was investigated using X-ray photoelectron spectroscopy analysis; the appearance of disulfide (S-S) linkage indicated the formation of a polymer/growth factor conjugate system.

Fluorine-ion-releasing injectable alginate nanocomposite hydrogel for enhanced bioactivity and antibacterial property.

The creation of a moist environment and promotion of cell proliferation and migration together with antibacterial property are critical to the wound-healing process. Alginate (Alg) is an excellent candidate for injectable wound dressing materials because it can form a gel in a mild environment. Taking advantage of its gelation property, an injectable nano composite hydrogel containing nano-sized (about 90 nm) calcium fluoride (CaF) particles was developed using in-situ precipitation process.

Chitosan-Based Dressing Materials for Problematic Wound Management.

Wound healing is a complex mechanism involving a variety of factors and is a representative process of tissue growth and regeneration in our body. Surface-based interactions between the dressing material and the wound may significantly influence the healing phase. Advances in understanding the mechanism of wound healing have led to the development of numerous dressing materials that can accelerate the healing process.

Effective Wound Healing by Antibacterial and Bioactive Calcium-Fluoride-Containing Composite Hydrogel Dressings Prepared Using in Situ Precipitation.

In this study, we report the development of a hyaluronic acid (HA)-based composite hydrogel containing calcium fluoride (CaF) with good biocompatibility and antibacterial properties for multifunctional wound dressing applications. CaF was newly selected for incorporation within HA because it can release both Ca and F ions, which are well-known ions for affecting cell proliferation and inhibiting bacterial growth, respectively. In particular, an in situ precipitation process enables easy control over the released amount of F ions by simply adjusting the precursor solutions (calcium chloride (CaCl) and ammonium fluoride (NHF)) used for the CaF precipitation.

Acceleration of the healing process of full-thickness wounds using hydrophilic chitosan-silica hybrid sponge in a porcine model.

In this study, we evaluated the surface characterization of a novel chitosan-silica hybridized membrane and highlighted the substantial role of silica in the wound environment. The chemical coupling of chitosan and silica resulted in a more condensed network compared with pure chitosan, which was eventually able to stably maintain its framework, particularly in the wet state. In addition, we closely observed the wound-healing process along with the surface interaction between chitosan-silica and the wound site using large-surface-area wounds in a porcine model.

Calcium Phosphate-Collagen Scaffold with Aligned Pore Channels for Enhanced Osteochondral Regeneration.

This study reports the development of a bilayered scaffold with aligned channels produced via a sequential coextrusion and unidirectional freezing process to facilitate upward bone-marrow stem-cell migration. The biomimetic scaffold with collagen and biphasic calcium phosphate (BCP) layers is successfully fabricated with matching of the cartilage and bone layers. The aligned structure results in an enhancement of the compressive strength, and the channels enable tight anchoring of the collagen layers on the BCP scaffolds compared with a randomly structured porous scaffold.

Polyurethane-silica hybrid foams from a one-step foaming reaction, coupled with a sol-gel process, for enhanced wound healing.

Polyurethane (PU)-based dressing foams have been widely used due to their excellent water absorption capability, optimal mechanical properties, and unequaled economic advantage. However, the low bioactivity and poor healing capability of PU limit the applications of PU dressings in complex wound healing cases. To resolve this problem, this study was carried out the hybridization of bioactive silica nanoparticles with PU through a one-step foaming reaction that is coupled with the sol-gel process.

Biomimetic Coating of Hydroxyapatite on Glycerol Phosphate-Conjugated Polyurethane via Mineralization.

In this study, glycerol phosphate was introduced into polyurethane (PU) to promote the coating stability of hydroxyapatite (HA) during its mineralization on the PU surface. Glycerol phosphate was successfully conjugated with the PU chain during polymerization. Phosphate groups in glycerol phosphate accelerated the nucleation of HA under calcium phosphate ion-rich conditions (concentrated simulated body fluid), resulting in the enhancement of structural stability.

The accelerating effect of chitosan-silica hybrid dressing materials on the early phase of wound healing.

Commercialized dressing materials with or without silver have played a passive role in early-phase wound healing, protecting the skin defects from infections, absorbing exudate, and preventing dehydration. Chitosan (CTS)-based sponges have been developed in pure or hybrid forms for accelerating wound healing, but their wound-healing capabilities have not been extensively compared with widely used commercial dressing materials, providing limited information in a practical aspect. In this study, we have developed CTS-silica (CTS-Si) hybrid sponges with water absorption, flexibility, and mechanical behavior similar to those of CTS sponges.

Phage lambda capsids as tunable display nanoparticles.

Nanoparticle technologies provide a powerful tool for the development of reagents for use in both therapeutic and diagnostic, or "theragnostic" biomedical applications. Two broad classes of particles are under development, viral and synthetic systems, each with their respective strengths and limitations. Here we adapt the phage lambda system to construct modular "designer" nanoparticles that blend these two approaches.

In vivo targeting of alveolar macrophages via RAFT-based glycopolymers.

Targeting cell populations via endogenous carbohydrate receptors is an appealing approach for drug delivery. However, to be effective, this strategy requires the production of high affinity carbohydrate ligands capable of engaging with specific cell-surface lectins. To develop materials that exhibit high affinity towards these receptors, we synthesized glycopolymers displaying pendent carbohydrate moieties from carbohydrate-functionalized monomer precursors via reversible addition-fragmentation chain transfer (RAFT) polymerization.

Mannose-functionalized "pathogen-like" polyanhydride nanoparticles target C-type lectin receptors on dendritic cells.

Targeting pathogen recognition receptors on dendritic cells (DCs) offers the advantage of triggering specific signaling pathways to induce a tailored and robust immune response. In this work, we describe a novel approach to targeted antigen delivery by decorating the surface of polyanhydride nanoparticles with specific carbohydrates to provide "pathogen-like" properties that ensure nanoparticles engage C-type lectin receptors on DCs. The surface of polyanhydride nanoparticles was functionalized by covalent linkage of dimannose and lactose residues using an amine-carboxylic acid coupling reaction.

Pathogen-derived oligosaccharides improve innate immune response to intracellular parasite infection.

Pathogen glycolipids, including Leishmania spp. lipophosphoglycan (LPG) and Mycobacterium tuberculosis mannosylated lipoarabinomannan (ManLAM), modulate essential interactions with host phagocytic cells. Polysaccharide and lipid components promote immunomodulation.

Highly conformal SiO2/Al2O3 nanolaminate gas-diffusion barriers for large-area flexible electronics applications.

The present study demonstrates a flexible gas-diffusion barrier film, containing an SiO(2)/Al(2)O(3) nanolaminate on a plastic substrate. Highly uniform and conformal coatings can be made by alternating the exposure of a flexible polyethersulfone surface to vapors of SiO(2) and Al(2)O(3), at nanoscale thickness cycles via RF-magnetron sputtering deposition. The calcium degradation test indicates that 24 cycles of a 10/10 nm inorganic bilayer, top-coated by UV-cured resin, greatly enhance the barrier performance, with a permeation rate of 3.

Synthesis of multivalent tuberculosis and Leishmania-associated capping carbohydrates reveals structure-dependent responses allowing immune evasion.

Mycobacterium tuberculosis and the protozoan parasites of the genus Leishmania are intracellular pathogens that can survive in macrophages--the very white blood cells of the immune system responsible for engulfing and ultimately clearing foreign invaders. The ability of these pathogens to hide within immune cells has made the design of effective therapies, including vaccines, to control tuberculosis and leishmaniasis particularly challenging. Herein we present the synthesis and development of carbohydrate-based probes to demonstrate that changes in pathogen-associated surface oligosaccharides are sufficient to alter cellular immune responses and thereby let a pathogen hide from immune surveillance.