Interface Membrane Research Articles

Self-assembled amorphous manganese oxide/hydroxide spheres via multi-phase electrochemical interactions in reverse micelle electrolytes and their capacitive behavior

Amorphous matrices of three-dimensionally interconnected MnOx/MnOOH nano-spheres were electrochemically assembled onto a carbon substrate by a pulse galvanostatic method (PGM) in a nonionic reverse micelle electrolyte. The synthesized material showed a unique morphology which was attributed to a synergistic effect between the amphiphilic molecule based interface membrane as a soft template and the PGM approach. The transfer of the reactant was remarkably special because of the elusive thermodynamic and kinetic parameters of the interactions at the interface between the two different phases such as the polar phase–interface membrane, interface membrane–nonpolar phase and polar phase–electrode interactions. Further work involved investigations into the potential application of the assembled MnOx/MnOOH films as high performance supercapacitor electrode materials. The capacitive performance of the assembled MnOx/MnOOH was tested in a solution of 0.5 M Na2SO4. The highest specific discharge capacitance of 1659 F g−1 was achieved at a current density of 2 A g−1, and remained as high as 782 F g−1 even at a very large current density of 10 A g−1. The outstanding capacitance properties were ascribed to the ternary oxide composites forming highly porous nanostructures which guaranteed a large specific surface, full utilization of Mn oxides and a small amount of degradation of amorphous MnO2. The results indicate the feasibility of electrochemically synthesizing Mn oxides in unconventional micelle electrolytes, and their successful application in supercapacitors.

RANKL in the osteolysis of AES total ankle replacement implants

Peri-implant tissue reactions in failed total ankle replacement (TAR) are characterized by early developing peri-implant osteolysis. The hypothesis of the study was that this reaction is mediated by receptor activator of nuclear factor kappa B ligand (RANKL).Samples of peri-prosthetic tissues from failed TAR implants were stained for macrophages, RANKL, its receptor RANK and osteoprotegerin (OPG), and compared to control samples.The failed TAR implants were surrounded by implant capsule, synovial lining-like interface membrane or necrotic tissues. Infiltrating scavenger receptor I positive CD163+ macrophages were frequent, in particular around necrotic soft tissues or bone sequestrate, and possibly in part formed due to ischemia and mechanical factors. In contrast, implant-derived wear debris was scanty. Still many RANK+ macrophages were often seen in close contact with RANKL+ mesenchymal cells, whereas OPG was mostly located at a distance in vascular endothelial cells. Foreign body giant cells were frequent.RANKL seems to stimulate locally accumulated CD163+ RANK-expressing cells to fusion, which leads to the local formation of multinuclear foreign body giant cells (and probably of osteoclasts). Therefore, peri-implant osteolysis in early TAR implant failure seems to be caused by the RANKL-driven chronic foreign body inflammation directed against, not implant-derived particles, but against necrotic autologous tissues.

A comparison on gas separation between PES (polyethersulfone)/MMT (Na-montmorillonite) and PES/TiO2 mixed matrix membranes

Polyethersulfone (PES)-based mixed matrix membranes (MMMs) with the incorporation of inorganic fillers of different shapes (lamellar Na-montmorillonite (MMT) clays and spherical TiO2 nanoparticles) were prepared in this study, and the resulting MMMs were characterized by TGA, DSC, XRD, SEM, and TEM. It was found that inorganic filler agglomeration became more serious at higher-filler-content MMMs. In the case of PES/MMT MMMs, both the CO2 and CH4 permeabilities increased significantly with the increasing filler content and consequently the gas selectivity was greatly reduced. At high MMT loadings (⩾10 wt.%), Knudsen diffusion became the predominant gas transport mechanism. A different trend was achieved in the case of PES/TiO2 MMMs. The CO2/CH4 selectivity increased from 24.5 (pure PES membrane) to a maximum value of 38.5 at 4 wt.% TiO2 MMM and then decreased with a further increase in TiO2 content (e.g. 17.3 for 20 wt.%). The formation of interface voids and membrane defects in MMMs contributed to the high gas permeabilities and low gas selectivity.

Tumor necrosis factor-like weak inducer of apoptosis regulates particle-induced inflammatory osteolysis via the p38 mitogen-activated protein kinase signaling pathway.

Periprosthetic osteolysis is the predominant cause of artificial joint loosening. Previous studies have demonstrated that p38 mitogen-activated protein kinase (p38 MAPK) may be involved in periprosthetic osteolysis. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a member of the TNF family and is a multifunctional cytokine, which regulates cellular proliferation, angiogenesis, inflammation and apoptosis via the p38 MAPK signaling pathway. The present study investigated the expression levels of TWEAK and p38 MAPK in periprosthetic interface membranes and in RAW264.7 monocyte/macrophage cells, which were treated with titanium (Ti) particle stimulation, with or without a p38 inhibitor (SB203580). This was performed to determine whether TWEAK was involved in the particle-induced inflammatory osteolysis via the p38 MAPK signaling pathway. The expression levels of TWEAK, p38 MAPK and phosphorylated (p-)p38 MAPK were evaluated in the periprosthetic interface membrane tissues and the RAW cells by reverse transcription-quantitative polymerase chain reaction and western blotting. The contents of interleukin-6 and monocyte chemoattractant protein-1 in the supernatant were measured by ELISA. The results demonstrated that the expression levels of TWEAK and p-p38 MAPK increased in the periprosthetic interface membrane tissues and the RAW cells stimulated with Ti particles, suggesting that TWEAK was involved in particle-induced inflammatory osteolysis via the p38 MAPK signaling pathway.

A comprehensive microbiological evaluation of fifty-four patients undergoing revision surgery due to prosthetic joint loosening

The diagnosis of a chronic prosthetic joint infection (PJI) is challenging, and no consensus exists regarding how best to define the criteria required for microbiological identification. A general view is that culture of periprosthetic biopsies suffers from inadequate sensitivity. Recently, molecular analyses have been employed in some studies but the specificity of molecular analyses has been questioned, mainly due to contamination issues. In a prospective study of 54 patients undergoing revision surgery due to prosthetic joint loosening, we focused on two aspects of microbiological diagnosis of chronic PJI. First, by collecting diagnostic specimens in a highly standardized manner, we aimed at investigating the adequacy of various specimens by performing quantitative bacteriological culture. Second, we designed and performed real-time 16S rRNA gene PCR analysis with particular emphasis on minimizing the risk of false-positive PCR results. The specimens analysed included synovial fluid, periprosthetic biopsies from the joint capsule and the interface membrane, and specimens from the surface of the explanted prosthesis rendered accessible by scraping and sonication. No antibiotics were given prior to specimen collection. Based on five diagnostic criteria recently suggested, we identified 18 PJIs, all of which fulfilled the criterion of ≥2 positive cultures of periprosthetic specimens. The rate of culture-positive biopsies from the interface membrane was higher compared to specimens from the joint capsule and synovial fluid, and the interface membrane contained a higher bacterial load. Interpretational criteria were applied to differentiate a true-positive PCR from potential bacterial DNA contamination derived from the reagents used for DNA extraction and amplification. The strategy to minimize the risk of false-positive PCR results was successful as only two PCR results were false-positive out of 216 negative periprosthetic specimens. Although the PCR assays themselves were very sensitive, three patients with low bacterial numbers in periprosthetic specimens tested negative by real-time PCR. This overall lowered sensitivity is most likely due to the reduced specimen volume used for PCR analysis compared to culture and may also be due to interference from human DNA present in tissue specimens. According to the protocol in the present study, 16S rRNA gene real-time PCR did not identify more cases of septic prosthetic loosening than did culture of adequate periprosthetic biopsies.

Percutaneous interface biopsy in dry-aspiration cases of chronic periprosthetic joint infections: A technique for preoperative isolation of the infecting organism

Preoperative identification of the infecting micro-organism is of paramount importance in the treatment protocol for chronic periprosthetic joint infections, as it enables selection of the most appropriate antibiotic treatment. Preoperative joint aspiration, the most commonly used sampling technique, has proven to have a broad range of sensitivity values and the frequency of dry aspirations has not been well assessed. In such dry-tap cases a biopsy sample could be an option. The purpose of this study was to assess the diagnostic accuracy of percutaneous interface biopsy (PIB) in isolating the infecting organism in cases of chronic Periprosthetic Joint Infection (PJI) and dry-tap event. The basic technique is to harvest and culture a sample from the periprosthetic interface membrane by a percutaneous technique in the preoperative period. A retrospective study was done involving 24 consecutive patients suspected of PJI and where no fluid was obtained from the joint. Culture results from a percutaneous interface biopsy (PIB) were compared with intraoperative tissue cultures at the time of revision surgery. In all cases, a two-stage replacement was done. The sensitivity was 88.2%; specificity was 100%. Positive predictive value was 100%, while negative predictive value was 77.9%. Accuracy was 91.6%. No technique-related complication was observed. We conclude that PIB is a useful test for preoperative isolation of the infecting organism and could play a role in cases with dry-tap joint aspirations.

Pathways of macrophage apoptosis within the interface membrane in aseptic loosening of prostheses

Aseptic loosening is a major cause of failure of total hip arthroplasty (THA). Macrophage apoptosis in interface membrane has been proved to play an important role in the pathogenesis of aseptic loosening. The purpose of current study was to identify the apoptotic mechanism of macrophages in the interface membrane of aseptic loosening. We collected periprosthetic interface membrane from 23 patients undergoing the revision operations for aseptic loosening of hip joint prostheses. To serve as the control group, samples of capsule were collected from 18 patients undergoing the primary hip arthroplasties for osteoarthritis (OA). The ultrastructure of interface membrane was examined by transmission electron microscopy (TEM), and in situ apoptotic macrophage identification was performed by TUNEL staining. Furthermore, using immunohistochemical methods we investigated the expression of some apoptosis-related markers such as inducible nitric oxide synthase (iNOS), peroxynitrite (ONOO −), cleaved caspase-3/4/8/9, cytochrome c, glucose regulated protein 78 (GRP78), and growth arrest and DNA damage-inducible gene 153 (GADD153) in macrophages. These markers were regarded as apoptotic inducers or specific indicators of different apoptotic pathways such as death receptor pathway, mitochondrial pathway and endoplasmic reticulum (ER) stress pathway. TEM showed that a great deal of wear debris was phagocytosed by macrophages, which displayed morphological changes characteristic of apoptosis. The results of TUNEL staining demonstrated that there were more apoptotic macrophages in interface membrane. The expression levels of iNOS, ONOO −, cleaved caspase-3/4/8/9, cytochrome c, GRP78 and GADD153 in macrophages in interface membrane were significantly higher than those in the control samples ( p < 0.05). Our results suggest that death receptor pathway, mitochondria/cytochrosome c caspase-dependent pathway and ER stress pathway are involved in the process of macrophage apoptosis. A therapeutic target to modulate the apoptotic pathways in macrophages may be a strategy to prevent and treat aseptic loosening.

Comparison of Ho:YAG laser and coblation for interface tissue removal in minimally invasive hip refixation procedures

Aseptic loosening is the major failure mode for hip prostheses. Currently, loosened prostheses are revised during open surgery. Because of a high complication rate, this demanding procedure cannot be performed in patients with a poor general health. We are developing an alternative minimally invasive refixation procedure that leaves the prostheses in place, but relies on removing the interface membrane and replacing it with bone cement.The aim of this study was to evaluate two interface tissue removal techniques – Ho:YAG laser and coblation – based on two criteria: thermal damage and the ablation rate.In vitro a loosened hip prosthesis was simulated by implanting a prosthesis in each of 10 cadaver femora. Artificially created peri-prosthetic lesions were filled with chicken liver as an interface tissue substitute. We measured temperatures in vitro at different radial distances from the site of removal. Temperatures during removal were recorded both inside the interface tissue and in the surrounding bone.This study demonstrated that temperatures generated in the bone do not result in thermal damage (increasing less than 10°C relative to body temperature). Temperatures inside the interface tissue are sufficiently high to destroy the interface tissue (T>50°C, duration>1min). Using laser instead of coblation for the removal of interface tissue resulted in higher temperatures – thus a faster removal of interface tissue. This is in accordance with the ablation rate test.Ho:YAG laser is advantageous compared to coblation. We consider Ho:YAG laser a promising tool for interface tissue removal.

Interface membrane is the best sample for histological study to diagnose prosthetic joint infection

The objective of our study was to study which is the most accurate specimen for histological diagnosis of prosthetic joint infections (pseudocapsule or interface membrane). This is a prospective study including hip revision arthroplasties performed from January 2007 to June 2009. Specimens from pseudocapsule and from interface membrane were obtained from each patient. The histology was considered positive for infection when ≥5 neutrophils per high-power field ( × 40) were found. Definitive diagnosis of infection was considered when ≥2 cultures were positive for the same microorganism. According to the definition of infection, patients were classified in two groups: (A) patients with aseptic loosening in whom cultures obtained during surgery were negative and (B) patients with prosthetic joint infection. A total of 69 revisions were included in the study; 57 were classified in group A and 12 in group B. In group B, the percentage of positive interface membrane histology was significantly higher than the percentage of positive pseudocapsule histology (83 vs 42%, P=0.04, Fisher's exact test). The results suggest that periprosthetic interface membrane is the best specimen for the histological diagnosis of prosthetic joint infection.

Aging Effects to Solid Electrolyte Interface (SEI) Membrane Formation and the Performance Analysis of Lithium Ion Batteries

Aging Effects to Solid Electrolyte Interface (SEI) Membrane Formation and the Performance Analysis of Lithium Ion Batteries

Laminin-332-Rich Tumor Microenvironment for Tumor Invasion in the Interface Zone of Breast Cancer

Dense fibrosis, which is caused by desmoplastic reaction, is usually found in invasive ductal carcinoma and may represent the alteration of the tumor microenvironment preceding tumor invasion. Thus, the dense fibrotic zone around invasive ductal carcinoma can be considered to be the actual tissue site of tumor microenvironment, where the precedent alterations for tumor invasion occur. To characterize the dense fibrotic zone, we classified invasive ductal carcinoma tissue into a tumor zone, a normal zone, and the novel interface zone (IZ), which shows dense fibrosis. The postulated IZ is a 5-mm-wide belt that circles the tumor margin and overlaps with normal tissue. Of the extracellular matrix components, laminin-332 was specifically overexpressed in the IZ. Events that appear to be similar to the epithelial-mesenchymal transition, a novel source of myofibroblast formation from epithelial cells, were observed in the IZ, according to the following characteristics: overexpression of matrix metalloproteinase 3, membrane type 1-matrix metalloproteinase, snail, and zinc finger E-box-binding homeobox 1, and the gain of N-cadherin expression, as well as the down-regulation of miR200c. The myofibroblasts isolated from the IZ, which were designated interface zone-fibroblast, displayed laminin-332 and membrane type 1-matrix metalloproteinase overexpression, in contrast with both cancer-associated fibroblasts and normal breast fibroblasts. Taken together, our results suggest that the IZ, which shows dense fibrosis, may provide a specialized microenvironment for guiding tumor invasion: the fibrosis caused by laminin-332 overexpressing myofibroblast formation (interface zone-fibroblast) via epithelial-mesenchymal transition.

Surface-based analysis methods for high-resolution functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5–4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-mm sampling, complicates the analysis of fMRI, as one must now consider activity variations within the depth of the brain tissue. We present a set of surface-based methods to exploit the use of high-resolution fMRI for depth analysis. These methods utilize white-matter segmentations coupled with deformable-surface algorithms to create a smooth surface representation at the gray-white interface and pial membrane. These surfaces provide vertex positions and normals for depth calculations, enabling averaging schemes that can increase contrast-to-noise ratio, as well as permitting the direct analysis of depth profiles of functional activity in the human brain.

Fabrication of Thermo-Conductivity Film Using Anodic Aluminum Oxide Template and Silver Nanowires

This paper discussed fabrication of a very low thermal resistance of thermal interface membrane (TIM). It is assumed that anodic aluminum oxide (AAO) template with silver nanowires inside can function very well as TIM. The TIM was made of well-aligned silver nanowires are expected to reduce the thermal resistance between the heat sink and the electronic device, a chip for example. This work also calculated the pore density, surface area, and porosity of AAO, and thermal conductivity values of AAO with different diameter nanowires inside.

Diffusion potentials in porous mortar in a moisture state below saturation

Diffusion potentials (membrane potentials) were measured in mortar in a moisture state below saturation for the first time. In contrast to conventional diffusion cell setups, the experimental approach was based on embedded ion selective electrodes. A numerical model with coupled Nernst–Planck equations for the most abundant species in the pore solution allowed simulating ion transport processes and the correspondingly arising diffusion potentials. It was found that Portland cement mortar with a water/cement ratio of 0.6 does not exhibit any significant permselective behaviour – even not in an unsaturated state determined by self-desiccation. Apparently, the stable radius of water-filled capillaries is still large enough to allow ionic transport through those fractions of pore solution that are unaffected by double layer effects. In addition, the relative importance of liquid junction potentials at the reference electrode/sample interface and internal diffusion or membrane potentials are discussed with respect to application of direct potentiometry to cement based materials.

Ectopic expression of macrophage scavenger receptor MARCO in synovial membrane‐like interface tissue in aseptic loosening of total hip replacement implants

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor with a very limited expression in healthy tissues. It was hypothesized that foreign body wear debris induces it to participate in handling of implant-derived particles in human synovial membrane-like tissue around aseptically loosening total hip replacement implants. A DNA microarray study showed that MARCO was upregulated in human monocytes by polymethyl methacrylate particles in cell culture. MARCO mRNA and protein were strongly expressed in numerous CD68 positive macrophages and foreign body giant cells in interface membrane lining and stroma around cemented implants, but was only present in a few cells in synovial membrane from osteoarthritis patients. A 65-kDa MARCO-reactive band was only found in interface tissue extracts. This is the first work to show upregulation of MARCO mRNA by foreign bodies in vitro. This is paralleled in vivo as MARCO mRNA and protein were over-expressed in chronic foreign body synovitis. As scavenger receptor MARCO apparently participates in handling of wear particles, which due to their nondegradable, irritating nature initiate/perpetuate foreign body inflammation, and peri-implant osteolysis.

Molecular Dynamics Simulation of Anionic Surfactant Aggregation at the Oil/Water Interface

We performed molecular dynamics (MD) simulations to investigate the demixing process of a three-component system, i.e., oil, water, and an anionic surfactant from the initial"homogeneous phase"to"two separated phases"and the effect of sodium dodecyl benzene sulfonate (SDBS) in this process was investigated. The two oil/water phases reached equilibrium in a short simulation time and an evident oil/water interface was formed. In the presence of SDBS the separation time of oil and water gradually increased as the concentration of SDBS increased and SDBS formed an evident interface membrane when the system reached equilibrium. Simulation results show that the MD method can be used as an adjunct and can provide the necessary information for experiments on the microstructural properties of molecular structures.

Intra- and Intermembrane Pairwise Molecular Recognition between Synthetic Hydrogen-Bonding Phospholipids

Multivalency and preorganization are fundamental aspects of molecular recognition at the lipid membrane-water interface and can render weak monomeric binding interactions selective and robust; this concept is important throughout biology, biotechnology, and materials science. Though hydrogen bonding is typically weakened in water, intramembrane hydrogen bonding between native lipids has been well-studied and is thought to contribute to lipid bioactivity and membrane function. We hypothesized that avidity and preorganization effects at the lipid-water interface could overcome solvent competition and allow for selective hydrogen-bond recognition between small, unstructured components. We have found that electrostatically identical vesicular membranes composed of cyanuric acid and melamine functionalized phospholipids 1 and 2 undergo selective apposition, fusion and adhesion in suspension and on solid support, indicating that their well-known low-dielectric hydrogen bonding properties translate effectively to the lipid-water interface. This work is notable and of general interest given the few detailed studies of aqueous phase hydrogen-bonding systems; we have extensively characterized this system, gaining structural, functional, and thermodynamic data. Furthermore, we have found that the designed lipid-lipid headgroup interactions result in dramatic alteration of the lipid phase morphology, providing insight into the coupling of molecular interactions with assembly state. As such, this work contributes to our understanding of fundamental phenomena such as molecular recognition at the lipid-water interface membrane chemistry and further illustrates the general possibility of designing selective hydrogen-bonding adhesive interactions from simple starting materials at other polar-apolar interfaces; this could have numerous materials and biotechnological applications.

Degenerative changes of the interface membrane as a possible reason for prosthesis loosening.

The aim of the present study was to perform a comparative evaluation of septic and aseptic interface membranes, assessing histological features, inflammatory infiltrate, and expression of inflammatory cytokines. Septic and aseptic interface membranes from 102 patients were examined by histology, histochemistry, and immunohistochemistry (tissue arrays). The cell subpopulations were characterized by quantification of CD3, CD4, CD8, CD20, and CD163 positive cells. Additionally, a semiquantitative evaluation of inflammatory cytokines (TNFalpha, TGF-beta1, IL-1, IL-6, CRP, MMP-1, MMP-6) was performed to complete the analysis of inflammatory infiltrates. The histological analysis revealed three different types of aseptic interface membranes: wear particle, degenerative, and mixed type. The expression of inflammatory molecules did not differ between septic and wear particle interface membranes. Significantly lower expression of cytokines, MMPs and CRP was observed, however, in degenerative interface membranes compared to other types. No expression of TNFalpha was observed in the degenerative interface membranes. Over 88% of patients with degenerative interface membranes had had a clinical record of osteoarthritis. Aseptic interface membranes were represented by wear particle, degenerative and mixed type. The expression of inflammatory factors in wear particle type is similar to this in septic membranes and can contribute to the bone destruction and prosthesis loosening. These factors seem not to play a major role in the degenerative membranes.

Gene Therapy and Cement Injection for Restabilization of Loosened Hip Prostheses

Loosening of orthopedic hip prostheses is an increasing health problem. In elderly patients with comorbidity,revision surgery may lead to high mortality rates. A less invasive surgical technique is therefore required to reduce these patient risks. To this end a percutaneous gene therapy approach was designed to destroy the periprosthetic loosening membrane, and enable refixing of the hip prosthesis with percutaneous bone cement injections under radiological guidance. In this phase 1/2 dose-escalating gene therapy clinical trial, 12 patients were treated. Toxicity and hip function variables were monitored up to 6 months posttreatment. All patients completed the study and no dose-limiting toxicity was observed. Improvement in walking distance, independence,and pain was demonstrated particularly in patients receiving 3 x 10(10) and 1 x 10(11) viral particles. Taken together, these data show that this gene therapy approach targeted at the interface membrane around a loosened hip prosthesis is a feasible treatment option for elderly patients for whom surgical intervention is not appropriate.

Seppo Santavirta: The Life and Work of an Orthopaedic Surgeon and Scientist. A Tribute From His Friends

Seppo Santavirta: The Life and Work of an Orthopaedic Surgeon and Scientist. A Tribute From His Friends