Role of protein-cellulose nanocrystal interactions in the stabilization of emulsion

HYPOTHESIS

The interactions between two bio-based emulsifiers, namely cellulose nanocrystals (CNC) and the surface active sodium caseinate (CAS), can influence the formation and stability of oil-in-water emulsion (O/W).

EXPERIMENTS

After studying the interactions between CNC and CAS, in bulk, and at air-water and liquid-liquid interfaces, emulsions have been prepared through different routes of addition, at pH 7 and 3, at which CNC and CAS had repulsive and attractive interactions, respectively. The routes of addition were (1) CAS and CNC simultaneously, (2) CAS first followed by CNC in a subsequent emulsification step and (3) CNC first, followed by CAS. The emulsions were characterized by laser diffraction and optical microscopy.

FINDINGS

At pH 7, in the case of repulsive interactions, the surface activity of CAS was balanced by the irreversible adsorption of CNC, irrespectively of the route of emulsification. At pH 3, in the case of attractive interactions, using route (1), the aggregates CAS-CNC provided better emulsification than CNC and CAS alone. For emulsions prepared by route (2) and (3), gelling was observed which could be controlled through the order of addition. Emulsions prepared at pH 7 then adjusted to pH 3 exhibited an increase in viscosity, while the droplet size was not affected.

Life During Wartime: A Personal Recollection of the Circa 1990 Prestegard Lab and Its Contributions to Membrane Biophysics

A subjective account is presented of challenges and excitement of being a postdoctoral trainee in the lab of James H. Prestegard at Yale University in New Haven, Connecticut from 1989 to 1991. This includes accounts of the early development of bicelles and of oriented sample NMR results that contributed to our modern understanding of the properties of the water-lipid interface of disordered phase biological membranes.

Crack propagation in cortical bone is affected by the characteristics of the cement line: a parameter study using an XFEM interface damage model

Bulk properties of cortical bone have been well characterized experimentally, and potent toughening mechanisms, e.g., crack deflections, have been identified at the microscale. However, it is currently difficult to experimentally measure local damage properties and isolate their effect on the tissue fracture resistance. Instead, computer models can be used to analyze the impact of local characteristics and structures, but material parameters required in computer models are not well established. The aim of this study was therefore to identify the material parameters that are important for crack propagation in cortical bone and to elucidate what parameters need to be better defined experimentally. A comprehensive material parameter study was performed using an XFEM interface damage model in 2D to simulate crack propagation around an osteon at the microscale. The importance of 14 factors (material parameters) on four different outcome criteria (maximum force, fracture energy, crack length and crack trajectory) was evaluated using ANOVA for three different osteon orientations. The results identified factors related to the cement line to influence the crack propagation, where the interface strength was important for the ability to deflect cracks. Crack deflection was also favored by low interface stiffness. However, the cement line properties are not well determined experimentally and need to be better characterized. The matrix and osteon stiffness had no or low impact on the crack pattern. Furthermore, the results illustrated how reduced matrix toughness promoted crack penetration of the cement line. This effect is highly relevant for the understanding of the influence of aging on crack propagation and fracture resistance in cortical bone.

Polysaccharides at fluid interfaces of food systems

Fabrication of next generation polysaccharides with interfacial properties is driven by the need to create high performance surfactants that operate at extreme environments, as for example in complex food formulations or in the gastrointestinal tract. The present review examines the behaviour of polysaccharides at fluid food interfaces focusing on their performance in the absence of any other intentionally added interfacially active components. Relevant theoretical principles of colloidal stabilisation using concepts that have been developed for synthetic polymers at interfaces are firstly introduced. The role of protein that in most cases is present in polysaccharide preparations either as contaminant or as integral part of the structure is also discussed. Critical assessment of the literature reveals that although protein may contribute to emulsion formation mostly as an anchor for polysaccharides to attach, it is not the determinant factor for the long-term emulsion stability, irrespectively of polysaccharide structure. Interfacial performance of key polysaccharides is also assessed revealing shared characteristics in their modes of adsorption. Conformation of polysaccharides, as affected by the composition of the aqueous solvent needs to be closely controlled, as it seems to be the underlying fundamental cause of stabilisation events and appears to be more important than the constituent polysaccharide sugar-monomers. Finally, polysaccharide adsorption is better understood by regarding them as copolymers, as this approach may assist to better control their properties with the aim to create the next generation biosurfactants.

Nanofiber-based transforming growth factor-β3 release induces fibrochondrogenic differentiation of stem cells

Fibrocartilage is typically found in regions subject to complex, multi-axial loads and plays a critical role in musculoskeletal function. Mesenchymal stem cell (MSC)-mediated fibrocartilage regeneration may be guided by administration of appropriate chemical and/or physical cues, such as by culturing cells on polymer nanofibers in the presence of the chondrogenic growth factor TGF-β3. However, targeted delivery and maintenance of effective local factor concentrations remain challenges for implementation of growth factor-based regeneration strategies in clinical settings. Thus, the objective of this study was to develop and optimize the bioactivity of a biomimetic nanofiber scaffold system that enables localized delivery of TGF-β3. To this end, we fabricated TGF-β3-releasing nanofiber meshes that provide sustained growth factor delivery and demonstrated their potential for guiding synovium-derived stem cell (SDSC)-mediated fibrocartilage regeneration. TGF-β3 delivery enhanced cell proliferation and synthesis of relevant fibrocartilaginous matrix in a dose-dependent manner. By designing a scaffold that eliminates the need for exogenous or systemic growth factor administration and demonstrating that fibrochondrogenesis requires a lower growth factor dose compared to previously reported, this study represents a critical step towards developing a clinical solution for regeneration of fibrocartilaginous tissues. STATEMENT OF SIGNIFICANCE: Fibrocartilage is a tissue that plays a critical role throughout the musculoskeletal system. However, due to its limited self-healing capacity, there is a significant unmet clinical need for more effective approaches for fibrocartilage regeneration. We have developed a nanofiber-based scaffold that provides both the biomimetic physical cues, as well as localized delivery of the chemical factors needed to guide stem cell-mediated fibrocartilage formation. Specifically, methods for fabricating TGF-β3-releasing nanofibers were optimized, and scaffold-mediated TGF-β3 delivery enhanced cell proliferation and synthesis of fibrocartilaginous matrix, demonstrating for the first time, the potential for nanofiber-based TGF-β3 delivery to guide stem cell-mediated fibrocartilage regeneration. This nanoscale delivery platform represents an exciting new strategy for fibrocartilage regeneration.

Clade 2.3.2.1 H5N1 avian influenza viruses circulate at the interface of migratory and domestic birds around Qinghai Lake in China

During 2012-2015, six H5N1 avian influenza viruses were isolated from domestic birds and the environment around Qinghai Lake. Phylogenetic analysis of HA genes revealed that A/chicken/Gansu/XG2/2012 (CK/GS/XG2/12) belonged to clade 2.3.2.1a, while A/environment/Qinghai/1/2013 (EN/QH/1/13), A/chicken/Qinghai/QH1/2015 (CK/QH/QH1/15), A/chicken/Qinghai/QH2/2015 (CK/QH/QH2/15), A/chicken/Qinghai/QH3/2015 (CK/QH/QH3/15), and A/goose/Qinghai/QH6/2015 (GS/QH/QH6/15) belonged to clade 2.3.2.1c. Further analysis of the internal genes of the isolates found that the PB2 gene of EN/QH/1/13 had 99.6% nucleotide identity with that of A/tiger/Jiangsu/1/2013 (H5N1), which clustered into an independent branch with PB2 from multiple subtypes. PB2, PB1, and M genes of CK/QH/QH3/15 were from H9N2, suggesting it was a reassortant of H5N1 and H9N2. Animal studies of three selected viruses revealed that CK/GS/XG2/12, EN/QH/1/13, and CK/QH/QH3/15 were highly lethal to chickens, with intravenous pathogenicity indexes (IVPIs) of 2.97, 2.81, and 3.00, respectively, and systemically replicated in chickens. In a mouse study, three selected H5N1 viruses were highly pathogenic to mice and readily replicated in the lungs, nasal turbinates, kidneys, spleens, and brains. Therefore, isolates in this study appear to be novel reassortants that were circulating at the interface of wild and domestic birds around Qinghai Lake and are lethal to chickens and mice. These data suggest that more extensive surveillance should be implemented, and matched vaccines should be chosen for the domestic birds in this area.

Interfacial ordering of tristearin induced by glycerol monooleate and PGPR: A coarse-grained molecular dynamics study

We use coarse-grained molecular dynamics simulations to study the effect of surfactant structure on the ordering of bulk tristearin at an oil-water interface. In the absence of surfactant, tristearin acyl chains are marginally aligned normal to the interface. The surfactant glycerol monooleate (GMO), a common small-molecule monoacylglycerol (MW: 357 g/mol), preferentially adsorbs to the oil-water interface, displacing more of the tristearin as its concentration increases. The tristearin that remains at the interface is closely aligned normal to the interface. Adjacent to the interface, bulk tristearin increasingly aligns with its acyl chains entwined with the GMO acyl chain, which also preferentially aligns normal to the interface. In contrast, polyglycerol polyricinoleate (PGPR), a bulkier, polymeric surfactant (MW: 1398 g/mol for a molecule with five monomers), both displaces tristearin from the interface and reduces the alignment of the molecules that remain. We suggest that the similar fatty acid moieties of GMO (oleic acid) and tristearin (stearic acid) lead to liquid-state association and alignment, the latter of which can then serve as a template onto which tristearin crystals can nucleate. Conversely, by both displacing tristearin from the interface and reducing alignment below that of the surfactant-free system, PGPR eliminates the possibility of tristearin interfacial crystallisation.

Bionic reconstruction : Restoration of extremity function with osseointegrated and mind-controlled prostheses

Background

Loss of an extremity at any level has a major impact on a patient’s life. Using bionic reconstruction, extremity function can be restored and the patient reintegrated into daily life. Surgical procedures including selective nerve transfer and anchoring of prostheses into bone are combined with structured rehabilitation and modern prosthetic fitting. The patient is thereby able to use the prostheses intuitively and with multiple degrees of freedom.

Methods

This article presents the concept and approach for modern bionic reconstruction in detail and the relevant literature. The nerve transfer matrices for targeted muscle reinnervation (TMR) and the concept of osseointegration to optimally fit a patient with a modern prosthesis are described in detail. As a clinical example, the case of a patient who suffered from traumatic amputation and subsequently received TMR in combination with an osseointegrated implant and structured rehabilitation is presented.

Results

Using bionic reconstruction, basic hand functions can be restored and bimanual dexterity can expand the range of daily activities. Besides this approach to bionic reconstruction, its advantages and disadvantages are compared to hand transplantation. The limitations and perspectives of modern bionic reconstruction are also discussed.

Conclusions

Bionic reconstruction is a sophisticated method for restoring extremity function and nowadays can be considered a standard of care for all levels of upper extremity amputations. An interdisciplinary approach and structured rehabilitation are necessary to master prosthetic function to ultimately reintegrate patients into daily life.

Frontiers in Clinical Practice of Long-Term Care of Chronic Ventilatory Failure

Home mechanical ventilation (HMV) is an effective long-term treatment for chronic hypercapnic respiratory failure. In addition to the established practice of providing HMV for the treatment of chronic ventilatory failure in slowly progressive neuromuscular and chest wall disease, there is accumulating evidence for improvement of quality of life and prolongation of survival by HMV in highly prevalent diseases like chronic obstructive pulmonary disease and ever-increasing obesity hypoventilation syndrome as well as rapidly progressive neuromuscular disease. The key concepts for successful HMV are an experienced team selecting the right patients, timely initiation of adequate ventilation via an appropriate interface, and monitoring effectiveness during regular long-term follow-up. Coaching of patients with chronic respiratory failure on long-term HMV within a dedicated service and collaborations with community services for home care are essential. The current review describes various important practical aspects of HMV that remain frontiers in the implementation of the current knowledge in clinical practice and may help in providing effective HMV to all those in need.

A Comprehensive Review on Current Advances in Peptide Drug Development and Design

Protein-protein interactions (PPIs) execute many fundamental cellular functions and have served as prime drug targets over the last two decades. Interfering intracellular PPIs with small molecules has been extremely difficult for larger or flat binding sites, as antibodies cannot cross the cell membrane to reach such target sites. In recent years, peptides smaller size and balance of conformational rigidity and flexibility have made them promising candidates for targeting challenging binding interfaces with satisfactory binding affinity and specificity. Deciphering and characterizing peptide-protein recognition mechanisms is thus central for the invention of peptide-based strategies to interfere with endogenous protein interactions, or improvement of the binding affinity and specificity of existing approaches. Importantly, a variety of computation-aided rational designs for peptide therapeutics have been developed, which aim to deliver comprehensive docking for peptide-protein interaction interfaces. Over 60 peptides have been approved and administrated globally in clinics. Despite this, advances in various docking models are only on the merge of making their contribution to peptide drug development. In this review, we provide (i) a holistic overview of peptide drug development and the fundamental technologies utilized to date, and (ii) an updated review on key developments of computational modeling of peptide-protein interactions (PepPIs) with an aim to assist experimental biologists exploit suitable docking methods to advance peptide interfering strategies against PPIs.

Top-down Fabrication of Spatially Controlled Mineral-Gradient Scaffolds for Interfacial Tissue Engineering

Materials engineering can generally be divided into "bottom-up" and "top-down" approaches, where current state-of-the-art methodologies are bottom-up, relying on the advent of atomic-scale technologies. Applying bottom-up approaches to biological tissues is challenging due to the inherent complexity of these systems. Top-down methodologies provide many advantages over bottom-up approaches for biological tissues, given that some of the complexity is already built into the system. Here, we generate interfacial scaffolds by the spatially controlled removal of mineral content from trabecular bone using a chelating solution. We controlled the degree and location of the mineral interface, producing scaffolds that support cell growth, while maintaining the hierarchical structure of these tissues. We characterized the structural and compositional gradients across the scaffold using X-ray diffraction, microcomputed tomography (μCT), and Raman microscopy, revealing the presence of mineral gradients on the scale of 20 - 40 μm. Using these data, we generated a model showing the dependence of mineral removal as function of time in the chelating solution and initial bone morphology, specifically trabecular density. These scaffolds will be useful for interfacial tissue engineering, with application in the fields of orthopedics, developmental biology, and cancer metastasis to bone.

Prebiotic Oligomer Assembly: What Was the Energy Source?

Polymerization of nucleotides and amino acids to form large, complex, and potentially functional products was an early and essential event on the paths leading to life's origin. The standard Gibbs energies of the condensation reactions are uphill, however, and at equilibrium will yield only declining sequences of small, nonfunctional oligomers. Geochemically produced condensing agents such as carbonyl sulfide, cyanamide, and polyphosphates have been proposed to invert the unfavorable condensation Gibbs energies and thereby activate exergonic condensation. We argue, however, that although activators may provide modest yields of oligomers, the inherently episodic nature of their sources throttles their effectiveness, and the fundamental hydrolytic instabilities of oligonucleotides and peptides ultimately prevail to yield decreasing product sequences. Notably, the Gibbs energy governing oligomer formation is antientropic. Accordingly, we propose that declining progression can be surmounted in evaporating pools in which a favorable entropy change is produced when high surface/volume ratios concentrate reactants at the air/water interface in continuous cycles of wetting and drying. The severely reduced configurational freedom of the solutes then inverts the antientropic nature of the condensation reactions, pivoting them to exergonic states and thus to the production of ascending sequences of complex polymeric products.

Priorities for the design and control of upper limb prostheses: A focus group study

BACKGROUND

Common prosthetic options do not allow for enough independent control signals to control all the movements of the arm. Invasive approaches to obtain prosthetic control signals are being developed to provide people with upper limb loss improved prosthetic control and feedback.

OBJECTIVE/HYPOTHESIS

This study explored the prosthetic qualities that are important to users and examined the factors that play into the decision to consider invasive prosthetic interfaces that allow for enhanced prosthetic control.

METHODS

Individuals participated in semi-structured focus groups or in individual semi-structured interviews (N = 11). A semi-structured interview guide containing open-ended questions was used to learn about ideal prosthesis qualities and interest in prosthetic technology interfaces including targeted muscle reinnervation, peripheral nerve interface, and cortical interface. Qualitative content analysis with an inductive approach was used for transcript analysis.

RESULTS

Participants were most interested in improving the dexterity and durability of prosthetic options. Recovery time, anticipated risk, medical co-morbidities, and baseline functional status influenced willingness to consider invasive prosthetic interfaces. Participants were interested in learning more about all three invasive interfaces but had the most concerns about cortical interfaces.

CONCLUSIONS

Attitudes toward invasive control interfaces vary. Further education on invasive control interfaces and additional conversations between prosthetic developers and people with limb loss will help to develop effective prosthetic devices that potential consumers will use.

Corrosion fatigue in DLC-coated articulating implants: an accelerated methodology to predict realistic interface lifetime

We present a methodology to accelerate and estimate the lifetime of an interlayer under dynamic loading in body-like media. It is based on accelerating corrosion fatigue processes taking place at the buried interface of a Si-based adhesion-promoting interlayer in articulating implants on a CoCrMo biomedical alloy; the implants are coated with diamond-like carbon (DLC). The number of interface loading cycles to delamination is determined by reciprocal loading in corrosive fluid. Its dependence on the load is summarized in a Wöhler-like curve of a DLC/DLC-Si/CoCrMo system in body working conditions: cyclic stresses at 37 °C in phosphate buffered saline (PBS). The presence of oxygen as a contaminant strongly affects the lifetime of the interface under corrosion fatigue. The main parameters acting on the prediction, with a special emphasis on simulated in vivo conditions, are analyzed and discussed: the media (PBS, Milli-Q water, NaCl, Ringers' solution and bovine calf serum), the load, the frequency and the composition of the interface determined by X-ray photoelectron spectroscopy.

Temperature-Dependent HfO2/Si Interface Structural Evolution and its Mechanism

In this work, hafnium oxide (HfO₂) thin films are deposited on p-type Si substrates by remote plasma atomic layer deposition on p-type Si at 250 °C, followed by a rapid thermal annealing in nitrogen. Effect of post-annealing temperature on the crystallization of HfO₂ films and HfO₂/Si interfaces is investigated. The crystallization of the HfO₂ films and HfO₂/Si interface is studied by field emission transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscopy. The experimental results show that during annealing, the oxygen diffuse from HfO₂ to Si interface. For annealing temperature below 400 °C, the HfO₂ film and interfacial layer are amorphous, and the latter consists of HfO₂ and silicon dioxide (SiO₂). At annealing temperature of 450-550 °C, the HfO₂ film become multiphase polycrystalline, and a crystalline SiO₂ is found at the interface. Finally, at annealing temperature beyond 550 °C, the HfO₂ film is dominated by single-phase polycrystalline, and the interfacial layer is completely transformed to crystalline SiO₂.

Investigation of direct inkjet-printed versus spin-coated ZrO2 for sputter IGZO thin film transistor

In this work, a low leakage current ZrO2 was fabricated for sputter indium gallium zinc oxide (IGZO) thin-film transistor using direct inkjet-printing technology. Spin-coated and direct inkjet-printed ZrO2 were prepared to investigate the film formation process and electrical performance for different process. Homogeneous ZrO2 films were observed through the high-resolution TEM images. The chemical structure of ZrO2 films were investigated by XPS measurements. The inkjet-printed ZrO2 layer upon IGZO showed a superior performance on mobility and off state current, but a large Vth shift under positive bias stress. As a result, the TFT device based on inkjet-printed ZrO2 exhibited a saturation mobility of 12.4 cm2/Vs, an Ion/Ioff ratio of 106, a turn on voltage of 0 V and a 1.4-V Vth shift after 1-h PBS strain. Higher density films with less oxygen vacancy were responsible for low off state current for the printed ZrO2 device. The mechanism of deteriorated performance on PBS test can be ascribed to the In-rich region formed at the back channel which easily absorbs H2O and oxygen. The absorbed H2O and oxygen capture electrons under positive bias stress, serving as acceptors in TFT device. This work demonstrates the film formation process of direct inkjet-printed and spin-coated oxide films and reveals the potential of direct inkjet-printed oxide dielectric in high-performance oxide TFT device.

Selective adsorption of uranyl and potentially toxic metal ions at the core-shell MFe2O4-TiO2 (M=Mn, Fe, Zn, Co, or Ni) nanoparticles

Potentially toxic metal ions (Xⁿ⁺: Rb⁺, Sr²⁺, Cr³⁺, Mn²⁺, Ni²⁺, Zn²⁺, Cd²⁺) usually coexist with uranyl (UO₂⁺), which will have a great influence on the selective adsorption process. Here, the core-shell MFe₂O₄-TiO₂ (M = Mn, Fe, Zn, Co, or Ni) nanoparticles were synthesized and assessed as new selective adsorbents. The results reveal that TiO₂(101) preferentially grows along the MFe₂O₄(311)/(111) orientation. The M²⁺ ions as the mediators transfer the holes from MFe₂O₄ to TiO₂, at the conduction bands. On the TiO₂(101) surfaces and TiO₂(101)-TiO₂(101) gaps, the paired active electrons mainly complex with water molecules as hydroxyl radicals to capture Xⁿ⁺ ions, forming an ion layer to block UO₂²⁺ from being adsorbed. Simultaneously, it should be noted that an interesting adsorption pathway was UO₂²⁺ being horizontally and irreversibly adsorbed in the MFe₂O₄(311)/(111)-TiO₂(101) interface, and therein, the stable adsorption capacity was found to be 66.78 mg g^-1 in the MnFe₂O₄(311)/(111)-TiO₂(101) interface. Finally, a mechanism of hybrid orbitals between MnFe₂O₄-TiO₂ and UO₂⁺-Xⁿ⁺ was proposed.

Ligand binding domain interface: A tipping point for pharmacological agents binding with GluN1/2A subunit containing NMDA receptors

N-methyl D-aspartate (NMDA) receptors play a crucial role in normal brain function, pathogenesis of neurodegenerative and psychiatric disorders. Functional tetra-heteromeric NMDA receptor contains two obligatory GluN1 subunits and two identical or different non-GluN1 subunits that evolve from six different genes including four GluN2 (A-D) and two GluN3 (A-B) subunits. Since NMDA receptors confer varied physiological properties and spatiotemporal distributions in the brain, pharmacological agents that target NMDA receptors with specific GluN2 subunits have significant potential for therapeutic applications. In the present work, by using electrophysiology techniques, we have studied the role of ligand binding domain (LBD) interactions in determining the effect of well-characterized pharmacological agents including agonists, competitive antagonists, channel blockers and an allosteric modulator. Remarkably, point mutations at the distal end (site-II&III) of GluN1 LBD interface increased memantine potency up to sevenfold when co-expressed with wild type GluN2A receptors but exhibit no effect on Mg²⁺ activity. Conversely, mutations at the proximal end (site-I) of the LBD interface did not affect the memantine but altered Zn²⁺ and Mg²⁺ potency towards opposite directions. These results indicate that GluN1/2A LBD interface interactions play a key role in determining channel function. Further, subtle changes in LBD interaction can be readily translated to the downstream extracellular vestibule of channel pore to adopt a conformation that may affect memantine, Zn²⁺ and Mg²⁺ binding. Further studies on NMDA receptor LBD to transmembrane domain signal propagation mechanisms will help develop GluN2 subunit selective biomolecules that can be used for the treatment of neurological and psychiatric disorders.

Ultrastructure of early stages of Rozella allomycis (Cryptomycota) infection of its host, Allomyces macrogynus (Blastocladiomycota)

This study reconstructs early stages of Rozella allomycis endoparasitic infection of its host, Allomyces macrogynus. Young thalli of A. macrogynus were inoculated with suspensions of R. allomycis zoospores and allowed to develop for 120 h. Infected thalli at intervals were fixed for electron microscopy and observed. Zoospores were attracted to host thalli, encysted on their surfaces, and penetrated their walls with an infection tube. The parasite cyst discharged its protoplast through an infection tube, which invaginated the host plasma membrane. The host plasma membrane then surrounded the parasite protoplast and formed a compartment confining it inside host cytoplasm. The earliest host-parasite interface within host cytoplasm consisted of two membranes, the outer layer the host plasma membrane and the inner layer the parasite plasma membrane. At first a wide space separated the two membranes and no material was observed within this space. Later, as the endoparasite thallus expanded within the compartment, the two membranes became closely appressed. As the endoparasite thallus continued to enlarge, the interface developed into three membrane layers. Thus, host plasma membrane surrounded the parasite protoplast initially without the parasite having to pierce the host plasma membrane for entry. Significantly, host-derived membrane was at the interface throughout development.

Intermolecular crosslinking of abnormal prion protein is efficiently induced by a primuline-sensitized photoreaction

In prion diseases, infectious pathogenic particles that are composed of abnormal prion proteins (PrP^Sc) accumulate in the brain. PrP^Sc is biochemically characterized by its protease-resistance core (PrP^res), but its structural features have not been fully elucidated. Here, we report that primuline, a fluorescent dye with photosensitization activity, dramatically enhances UV-irradiation-induced SDS-resistant PrP^Sc/res oligomer formation that can be detected by immunoblot analysis of prion-infected materials. This oligomer formation occurs specifically with PrP^Sc/res but not with normal prion protein, and it was demonstrated using purified PrP^Sc/res as well as unpurified materials. The oligomer formation proceeded in both primuline-dose- and UV irradiation time-dependent manners. Treatment with urea or formic acid did not break oligomers into monomers. Neither did the presence of aromatic amino acids modify oligomer formation. Analysis with a panel of anti-prion protein antibodies showed that the antibodies against the N-terminal region of PrP^res were less reactive in the dimer than the monomer. These findings suggest that the primuline-sensitized photoreaction enhances intermolecular crosslinking of PrP^Sc/res molecules at a hydrophobic area of the N-terminal region of PrP^res. In the screening of other compounds, photoreactive compounds such as luciferin exhibited a similar but lower activity with respect to oligomer formation than primuline. The enhanced photoreaction with these compounds will be useful for evaluating the structural features of PrP^Sc/res, especially the interactions between PrP^Sc/res molecules.

Surface modified halloysite nanotubes: A flexible interface for biological, environmental and catalytic applications

Halloysite Nanotubes (HNTs) are clay minerals that possess unique chemical composition and a tubular structure due to which, they have recently emerged as a potential nanomaterial for umpteen applications. Over the years, the myriad applications of HNT have been realized through the surface modification of HNT, which involves the modification of nanotube's inner lumen and the outer surface with different functional compounds. The presence of aluminum and silica groups on the inner and outer surface of HNT enhance the interfacial relationship of the nanotube with different functional agents. Compounds such as alkalis, organosilanes, polymers, compounds of biological origin, surfactants and nanomaterials have been used for the modification of the inner lumen and the outer surface of HNT. The strategies change the constitution of HNT's surface either through micro-disintegration of the surface or by introducing additional functional groups on the surface, which further enhances their potential to be used as a flexible interface for different applications. In this review, the different surface modification strategies of the outer surface and the inner lumen that have been employed over the years have been discussed. The biological, environmental and catalytic applications of these surface modified HNTs with such versatile interface in the past two years have been elaborately discussed as well.

New developments in liquid-liquid extraction, surface modification and agglomerate-free processing of inorganic particles

This review describes new methods for the particle extraction through liquid-liquid interface (PELLI). The discovery of new surface modification techniques, advanced extractors and new adsorption mechanisms enabled novel applications of PELLI in nanotechnology of metals, quantum dots, oxides and hydroxides. Colloidal and interface chemistry of PELLI is emerging as a new area of technological and scientific interest. The progress achieved in the understanding of particle behavior and interactions at the liquid-liquid interface, phase transfer and interface reactions allowed for the development of new extraction mechanisms. An important breakthrough was the development of surface modification techniques for extraction of functional oxides. Especially important is the possibility of particle transfer from the synthesis medium to the device processing medium, which facilitates agglomerate-free processing of functional nanoparticles. Multifunctional extractor molecules were discovered and used as capping and reducing agents for particle synthesis or dispersing and charging agents for colloidal processing. The progress achieved in the development of extractors and extraction mechanisms has driven the advances in the surface modification and functionalization of materials. New PELLI techniques were used for the development of advanced materials and devices for optical, photovoltaic, energy storage, electronic, biomedical, sensor and other applications.

Characterization of the Interface Between Coating and Fibrous Layers of Paper

Coated paper is an example of a multi-layer porous medium, involving a coating layer along the two surfaces of the paper and a fibrous layer in the interior of the paper. The interface between these two media needs to be characterized in order to develop relevant modeling tools. After careful cutting of the paper, a cross section was imaged using focused ion beam scanning electron microscopy. The resulting image was analyzed to characterize the coating layer and its transition to the fibrous layer. Such image analysis showed that the coating layer thickness is highly variable, with a significant fraction of it being thinner than a minimum thickness required to keep ink from invading into the fibrous layer. The overall structure of the coating and fibrous layers observed in this analysis provide insights into how the system should be modeled, with the resulting conclusion pointing to a specific kind of multi-scale modeling approach.

Structure-Based Detection of Orthosteric and Allosteric Pockets at Protein-Protein Interfaces

Protein-protein interfaces represent challenging but very promising targets to discover novel drugs with exquisite specificity profiles. We herewith chart for the first time all biologically relevant protein-protein interfaces of known X-ray structure and detect potentially druggable cavities at and nearby the interface. These cavities are then converted in simple 3D pharmacophore queries for identifying potential modulators (inhibitors, stabilizers) of druggable interfaces.

Image and perception of physicians as barriers to inter-disciplinary cooperation? - the example of German occupational health physicians in the rehabilitation process: a qualitative study

BACKGROUND

In the German rehabilitation system, primary care physicians (PCPs), occupational health physicians (OPs), and rehabilitation physicians (RPs) fulfill different distinct functions and roles. While effective cooperation can improve outcomes of rehabilitation, the cooperation between these groups of stakeholders has been criticized as lacking or insufficient. This article proposes an approach to understand the low levels of cooperation by examining the role of group perception and group identity in intra-professional cooperation as a barrier to cooperation between physicians in different roles. Group perception was evaluated in terms of (1) negative views about another group of medical specialists and (2) differences between the perception of members and non-members of a medical specialty group. To examine this issue, we focused on the role of OPs in the German rehabilitation process.

METHODS

We implemented a qualitative study design with eight focus group discussions with PCPs, OPs, RPs, and patients (two focus group discussions per stakeholder group; 4-10 participants) and qualitative content analysis. We used the Social Identity Approach by Tajfel and Turner as a theoretical underpinning.

RESULTS

While all protagonists reported a positive perception of their own professional group, we found numerous negative perceptions about other groups, especially regarding OPs. Negative perceptions of OPs included 1) apparent conflict of interest between employer and employee, 2) lack of commitment to patient outcomes, 3) lack of useful specialized knowledge which could have a bearing on rehabilitation outcomes, and 4) distrust on the part of their patients. We also found divergent perceptions regarding roles, responsibilities, and capabilities among the specialist groups. Both negative and conflicting perceptions about roles were characterized as barriers to cooperation by study participants.

CONCLUSION

This example of cooperation between RPs, OPs, and PCPs suggests that negative and diverging perceptions about an out-group could create barriers in intra-professional and inter-disciplinary cooperation between physicians. These perspectives might also be useful in explaining problems at intersections between different specialties. We suggest examining the inter-group dimension of perception-based barriers to cooperation in future interventions to overcome problems caused by intra-professional and inter-disciplinary conflicts in addition to other barriers (i.e. organizational hurdles).