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Abstract Background Continuous cross talk between MSCs and macrophages is integral to acute and chronic inflammation resulting from contaminated polyethylene particles (cPE); however, the effect of this inflammatory microenvironment on mitochondrial metabolism has not been fully elucidated. We hypothesized that (a) exposure to cPE leads to impaired mitochondrial metabolism and glycolytic reprogramming and (b) macrophages play a key role in this pathway. Methods We cultured MSCs with/without uncommitted M0 macrophages, with/without cPE in 3-dimensional gelatin methacrylate (3D GelMA) constructs/scaffolds. We evaluated mitochondrial function (membrane potential and reactive oxygen species—ROS production), metabolic pathways for adenosine triphosphate (ATP) production (glycolysis or oxidative phosphorylation) and response to stress mechanisms. We also studied macrophage polarization toward the pro-inflammatory M1 or the anti-inflammatory M2 phenotype and the osteogenic differentiation of MSCs. Results Exposure to cPE impaired mitochondrial metabolism of MSCs; addition of M0 macrophages restored healthy mitochondrial function. Macrophages exposed to cPE-induced glycolytic reprogramming, but also initiated a response to this stress to restore mitochondrial biogenesis and homeostatic oxidative phosphorylation. Uncommitted M0 macrophages in coculture with MSC polarized to both M1 and M2 phenotypes. Osteogenesis was comparable among groups after 21 days. Conclusion This work confirmed that cPE exposure triggers impaired mitochondrial metabolism and glycolytic reprogramming in a 3D coculture model of MSCs and macrophages and demonstrated that macrophages cocultured with MSCs undergo metabolic changes to maintain energy production and restore homeostatic metabolism.

Replacing liquid electrolyte (LE) with gel polymer electrolyte (GPE) can significantly improve the safety and long-term stability of lithium-ion batteries. However, the traditional pure polymethyl methacrylate (PMMA)-based GPE after immersion in the electrolyte has the problem of poor mechanical properties and easy damage. In this article, PMMA was used as the matrix, and low-density polyethylene particles were mixed to prepare a kind of structure-enhanced and heat-resistant GPE by phase inversion method. The prepared GPE has high ionic conductivity at room temperature. It can slow down the temperature rise of the battery by reducing the ionic conductivity at high temperatures, thereby improving the safe application performance of the battery. In addition, the symmetrical battery made of this material can maintain ultra-low overvoltage and run stably for at least 800 h in the overpotential test when the current density is 1 mA cm−2. This study provides new insights for the preparation of high-temperature safety GPE. [ABSTRACT FROM AUTHOR]

Background: Continuous cross talk between MSCs and macrophages is integral to acute and chronic inflammation resulting from contaminated polyethylene particles (cPE); however, the effect of this inflammatory microenvironment on mitochondrial metabolism has not been fully elucidated. We hypothesized that (a) exposure to cPE leads to impaired mitochondrial metabolism and glycolytic reprogramming and (b) macrophages play a key role in this pathway. Methods: We cultured MSCs with/without uncommitted M0 macrophages, with/without cPE in 3-dimensional gelatin methacrylate (3D GelMA) constructs/scaffolds. We evaluated mitochondrial function (membrane potential and reactive oxygen species—ROS production), metabolic pathways for adenosine triphosphate (ATP) production (glycolysis or oxidative phosphorylation) and response to stress mechanisms. We also studied macrophage polarization toward the pro-inflammatory M1 or the anti-inflammatory M2 phenotype and the osteogenic differentiation of MSCs. Results: Exposure to cPE impaired mitochondrial metabolism of MSCs; addition of M0 macrophages restored healthy mitochondrial function. Macrophages exposed to cPE-induced glycolytic reprogramming, but also initiated a response to this stress to restore mitochondrial biogenesis and homeostatic oxidative phosphorylation. Uncommitted M0 macrophages in coculture with MSC polarized to both M1 and M2 phenotypes. Osteogenesis was comparable among groups after 21 days. Conclusion: This work confirmed that cPE exposure triggers impaired mitochondrial metabolism and glycolytic reprogramming in a 3D coculture model of MSCs and macrophages and demonstrated that macrophages cocultured with MSCs undergo metabolic changes to maintain energy production and restore homeostatic metabolism. [ABSTRACT FROM AUTHOR]

Particle-induced osteolysis is a major cause of aseptic prosthetic loosening. Implant wear particles stimulate tissue macrophages inducing an aseptic inflammatory reaction, which ultimately results in bone loss. Fetuin-A is a key regulator of calcified matrix metabolism and an acute phase protein. We studied the influence of fetuin-A on particle-induced osteolysis in an established mouse model using fetuin-A-deficient mice. Ten fetuin-A-deficient (Ahsg−/−) mice and ten wild-type animals (Ahsg+/+) were assigned to test group receiving ultra-high molecular weight polyethylene (UHMWPE) particle implantation or to control group (sham surgery). After 14 days, bone metabolism parameters RANKL, osteoprotegerin (OPG), osteocalcin (OC), alkaline phosphatase (ALP), calcium, phosphate, and desoxypyridinoline (DPD) were examined. Bone volume was determined by microcomputed tomography (μCT); osteolytic regions and osteoclasts were histomorphometrically analyzed. After particle treatment, bone resorption was significantly increased in Ahsg−/− mice compared with corresponding Ahsg+/+ wild-type mice (p = 0.007). Eroded surface areas in Ahsg−/− mice were significantly increased (p = 0.002) compared with Ahsg+/+ mice, as well as the number of osteoclasts compared with control (p = 0.039). Fetuin-A deficiency revealed increased OPG (p = 0.002), and decreased levels of DPD (p = 0.038), OC (p = 0.036), ALP (p < 0.001), and Ca (p = 0.001) compared with wild-type animals. Under osteolytic conditions in Ahsg−/− mice, OPG was increased (p = 0.013), ALP (p = 0.015) and DPD (p = 0.012) were decreased compared with the Ahsg+/+ group. Osteolytic conditions lead to greater bone loss in fetuin-A-deficient mice compared with wild-type mice. Reduced fetuin-A serum levels may be a risk factor for particle-induced osteolysis while the protective effect of fetuin-A might be a future pathway for prophylaxis and treatment. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are critical emerging pollutants around the world. There is a growing interest in the effects of MP ingestion, non-digestion, and toxicity on aquatic organisms. Amphibian tadpoles are the vertebrate group that has received the least attention regarding this issue. The aim of the present study was to determine the ingestion of polyethylene MPs by Scinax squalirostris tadpoles by atomic force microscopy (AFM) and to evaluate the activities of carboxylesterase (CbE, using 4-naphthyl butyrate-NB-, and 1-naphthyl acetate –NA- as substrates) and alkaline phosphatase (ALP) under MP exposure. Enzyme activities were analyzed spectrophotometrically at 2 and 10 days of exposure. Tadpoles were exposed to two different treatments during 10 days: a negative control (CO, dechlorinated water) and MP (60 mg L−1). AFM images of the digestive contents of tadpoles revealed the presence of MPs. After 10 days of MP exposure, CbE (NB) activity was significantly higher and CbE (NA) activity was significantly lower in MP treatments than in controls. ALP activity decreased in MP treatments after 2 and 10 days of exposure. The detection of MP particles in the intestinal contents and the effects on metabolic enzymes in a common frog species evidenced the potential health risk of MP to aquatic vertebrates. Thus, the differential response in enzymes and substrates demonstrate the need for considering the complex effects of contaminants and nutrients on ecosystems for ecotoxicological risk characterization. [ABSTRACT FROM AUTHOR]

[Display omitted] • To attract polyethylene (PE) particles in water, a rugged solid-based platform was exploited. • For this, a circular polydimethylsiloxane-coated nickel foam (PDMS@NF) was fabricated. • Due to the strong hydrophobicity of PDMS@NF, the particle-capturing efficiency was 97.6%. • A laser illumination covering the whole PDMS@NF was adopted for Raman measurement. • The PE/PDMS peak ratios correlated well with the quantities of PE particles in water samples. Nickel foam (NF) was evaluated as a medium for the capture of polyethylene (PE) particles in water. NF is a hydrophobic and porous material with a large surface area, making it a promising candidate for attracting PE particles. However, the particle-capturing efficiency using bare NF was only 69.5%. To increase capturing efficiency, a circular polydimethylsiloxane (PDMS)-coated NF (PDMS@NF, diameter: 6 mm) was employed to enhance the hydrophobicity. The capturing efficiency using the PDMS@NF was substantially increased to 97.6 % owing to the increase in hydrophobicity. To quantify the captured PE particles on/in the PDMS@NF using Raman spectroscopy, a wide area illumination (WAI) scheme providing 6 mm-diameter laser illumination was adopted to fully cover the PDMS@NF for representative spectroscopic sampling and accurate quantification. The intensity ratios of PE to PDMS peaks in the collected spectra clearly increased with the quantity of dispersed PE particles (0.1 ∼ 4.0 mg range, R2: 0.992) in the water samples, and the limit of detection was 0.08 mg. Moreover, the capturing efficiencies for polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) particles (1 mg of each) using the PDMS@NF were also superior, ranging from 96.4 to 98.2 %. Therefore, the proposed scheme incorporating the PDMS@NF as a particle-capturing and Raman measurement platform has potential as a method for on-line detection of microplastics in water. [ABSTRACT FROM AUTHOR]

Wear debris generated from the bearing surfaces of joint arthroplasties leads to acute and chronic inflammation, which is strongly associated with implant failure. Macrophages derived from monocytes recruited to the local tissues have a significant impact on bone healing and regeneration. Macrophages can adopt various functional phenotypes. While M1 macrophages are pro-inflammatory, M2 macrophages express factors important for tissue repair. Here, we established a 3D co-culture system to investigate how the immune system influences the osteogenic differentiation of mesenchymal stem cells (MSCs) in the presence of micron-sized particles. This system allowed for the simulation of an inflammatory reaction via the addition of Lipopolysaccharide-contaminated polyethylene particles (cPE) and the characterization of bone formation using micro-CT and gene and protein expression. Co-cultures of MSCs with M2 macrophages in the presence of cPE in a 3D environment resulted in the increased expression of osteogenic markers, suggesting facilitation of bone formation. In this model, the upregulation of M2 macrophage expression of immune-associated genes and cytokines contributes to enhanced bone formation by MSCs. This study elucidates how the immune system modulates bone healing in response to an inflammatory stimulus using a unique 3D culture system.

Highlights • Two-fluid model with charge generation and transport model. • Validation of contact charging model against experiments involving polyethylene particles in bubbling fluidized beds. • Prediction of charge density in the fluidized bed with insulating particles. • Prediction of wall sheeting. Abstract A computational model for the prediction of triboelectric charging in gas-solid fluidized beds is developed in the context of the Euler-Euler two-fluid model with kinetic theory closures for the description of the particulate phase. Sub-model for charge transfer due to particle-wall collisions is obtained consistently with the boundary conditions of Johnson and Jackson (1987), and assuming the model of Matsusaka et al. (2000) for charge transfer during a single collision. Similarly, a sub-model for charge diffusion due to particle-particle collisions is developed based on the kinetic theory of granular flow of Jenkins and Savage (1983), and the aforementioned charging model. The Eulerian charging model is then coupled to the two-fluid model, with kinetic theory closures which are available in the OpenFOAM® computational toolbox for fluid dynamics. The model is tested to simulate the effect of polyethylene particle size (362, 462, 550 μm) in the electrification process, and is validated against experimental findings (Sowinski, 2012; Sowinski et al., 2012). The order of magnitude of charge densities in different regions of the bed, predicted by the model, was coherent with the experimental results. The model also predicted that particles larger than 425 μm would not stick to the column wall, which acceptably agreed with the experimental observation that particles larger than 600 μm did not adhere to the wall surface. [ABSTRACT FROM AUTHOR]

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The study of edaphic bacteria is of great interest, particularly for evaluating soil remediation and recultivation methods. Therefore, a fast and simple strategy to isolate various bacteria from complex soil samples using poly(ethyleneimine) (PEI)-modified polyethylene particles is introduced. The research focuses on the binding behavior under different conditions, such as the composition, pH value, and ionic strength, of the binding buffer, and is supported by the characterization of the surface properties of particles and bacteria. The results demonstrate that electrostatic forces and hydrophobicity are responsible for the adhesion of target bacteria to the particles. Distinct advantages of the particle-based isolation strategy include simple handling, enrichment efficiency, and the preservation of viable bacteria. The presented isolation method allows a subsequent identification of the bacteria using Raman microspectroscopy in combination with chemometrical methods. This is demonstrated with a dataset of five different bacteria ( Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens, Streptomyces tendae, and Streptomyces acidiscabies) which were isolated from spiked soil samples. In total 92% of the Raman spectra could be identified correctly. [ABSTRACT FROM AUTHOR]

A diffuser-incorporated near-infrared (NIR) trans-reflectance measurement is demonstrated for quantitative detection of polyethylene (PE) particles captured in perfluorohexane (PFH, C 6 F 14). PFH effectively captures PE particles through its hydrophobicity and absorbs little NIR radiation, recommending it for use in background-free NIR detection of captured PE particles. A reflective metal disk was used to push the captured PE particles in PFH toward the bottom of the vial that contained the sample, and the trans-reflectance measurement was performed by illuminating NIR radiation from the bottom of the vial at 45o. Reproducibility is limited by the variation in the positions of small PE-particle aggregates at the water/PFH interface and the difficulty in ensuring full NIR sampling (coverage) of large aggregates. An effective way to secure improved reproducibility under these circumstances is illumination of broader and more uniform NIR radiation for measurement. For this purpose, a polytetrafluoroethylene (PTFE) disk was uniquely incorporated as a diffuser for the trans-reflectance measurement. Compared to the measurement with no diffuser, the diffuser-incorporated scheme produced more distinct PE peaks of low-quantity samples (0.1 and 0.2 mg) and enhanced the reproducibility in measurements of all the samples (0.1–4.0 mg of PE). As a result, the correlation between peak intensity and particle quantity was excellent (R2: 0.997), and a limit of detection of 0.07 mg was achieved. [Display omitted] • A trans-reflectance NIR scheme was designed to quantify PE particles captured in PFH. • A reflective metal disk was used to push the captured PE particles down for measurement. • For broader and more uniform NIR illumination, a diffuser (PTFE disk) was incorporated. • Use of the diffuser was effective to improve the linearity and reproducibility of measurement. • The R2 over 0.1–4.0 mg range and limit of detection was 0.997 and 0.07 mg, respectively. [ABSTRACT FROM AUTHOR]

Wear particles generated with use of total joint replacements incite a chronic macrophage-mediated inflammatory reaction, which leads to implant failure. Macrophage activation may be polarized into two states, with an M1 proinflammatory state dominating an alternatively activated M2 anti-inflammatory state. We hypothesized that IL-4, an activator of M2 macrophages, could modulate polyethylene (PE) particle-induced osteolysis in an experimental murine model. Four animal groups included (a) calvarial saline injection with harvest at 14 days (b) single calvarial injection of PE particles subcutaneously (SC) without IL-4 (c) PE particles placed as in (b), then IL-4 given SC for 14 consecutive days and (d) PE particles as in (b) then IL-4 beginning 7 days after particle injection for 7 days. The calvarial bone volume to total tissue volume was measured using microCT and histomorphometry. Calvaria were cultured for 24 h to assess release of RANKL, OPG, TNF-α, and IL-1ra and isolation and identification of M1 and M2 specific proteins. MicroCT and histomorphometric analysis showed that bone loss was significantly decreased following IL-4 administration to PE treated calvaria for both 7 and 14 days. Western blot analysis showed an increased M1/M2 ratio in the PE treated calvaria, which decreased with addition of IL-4. Cytokine analysis showed that the RANKL/OPG ratio and TNF-α/IL-1ra ratio decreased in PE-treated calvaria following IL-4 addition for 14 days. IL-4 delivery mitigated PE particle-induced osteolysis through macrophage polarization. Modulation of macrophage polarization is a potential treatment strategy for wear particle induced periprosthetic osteolysis. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013. [ABSTRACT FROM AUTHOR]

Background: Micro-structural changes associated with ultra high molecular weight polyethylene particle (UHMWPE) induced osteolysis, the most frequent cause of aseptic loosening, have been intensively investigated in the mammalian calvarian model by histomorphometry and micro-computed tomography. However, little is known regarding the serological changes that occur during this process. Methods: Serological parameters for bone metabolism [calcium, phosphate, osteocalcin (OCN), deoxypyridinoline (DPD)/creatinine, alkaline phosphatase, osteoprotegerin and receptor activator of nuclear factor-κB] were analyzed in this animal model for particle induced osteolysis. Ten C57BL/6 mice were divided at random into sham operated and UHM-WPE implanted groups. Blood and urine samples were collected prior to and at 14 days after surgery. Results: Implantation of UHMWPE lead to a significant decrease in bone volume (p=0.027). Both groups (sham/UHMWPE) showed a significant increase in calcium (p=0.004/p=0.027) and phosphate (p=0.001/p=0.001), without correlation to particle implantation. Significantly higher concentrations of DPD/creatinine (p=0.034) and OCN (p=0.022) were found after implantation of UHM-WPE. In addition, parameters could not be correlated to particle induced osteolysis. Conclusions: DPD can be regarded as a valuable parameter for detecting UHMWPE induced osteolysis in the calvarian model. Further studies of serum parameters should focus on the clinical relevance in aseptic prosthetic loosening. Clin Chem Lab Med 2010;48:1641-6. [ABSTRACT FROM AUTHOR]

Abstract: Wear particles are believed to induce periprosthetic inflammation which contributes to periprosthetic osteolysis. TNFα plays a pivotal role in the pathogenesis of this process. The molecular mechanisms leading to the development of periprosthetic inflammation with upregulated TNFα expression in monocytic cells in response to different wear particles have yet to be defined. In this study we evaluated the effects of polyethylene- and TiAlV-particles on activation of NF-κB signalling pathways and TNFα biosynthesis and release in monocytic cells with respect to periprosthetic osteoclastogenesis. THP-1 monocytic cells were differentiated to macrophage-like cells and exposed to LPS-detoxified polyethylene and prosthesis-derived TiAlV-particles. TNFα release was analyzed in culture supernatant by ELISA. NF-κB activation was examined by electrophoretic mobility shift assay (EMSA), and NF-κB target promoter activities including transactivation of the TNFα promoter were determined by luciferase reporter gene assays. Differentiated THP-1 macrophages were exposed to increasing numbers of particles for 0, 60, 180 and 360min. Both, polyethylene- and TiAlV-particles induced a significant activation of both NF-κB and TNFα promoters at 180min. A significant TNFα release was detected after 360min exposure to polyethylene- and TiAlV-particles in a dose dependent manner. In comparison, LPS induced a much greater activation of NF-κB and TNFα promoters, and TNFα secretion into the supernatant was strongly induced. These results provide evidence that induction of the NF-κB signal transduction pathway in macrophages plays a major role in initiating and mediating the inflammatory response leading to periprosthetic osteolysis. [Copyright &y& Elsevier]

Abstract: Following infection, bacterial killing by polymorphonuclear leukocytes (neutrophils) is the main host defense against bacteria. Our hypothesis is that particles of ultra-high molecular weight polyethylene (UHMWP) may impair local neutrophil function and consequently reduce neutrophil bacterial killing. To determine how the in vitro phagocytic–bactericidal activity of neutrophils was affected by exposure to wear particles, tests were run comparing the effects of different particle composition, and different concentrations and sizes of UHMWP particles. There was a significant correlation between the number of particles and the decrease in neutrophil bactericidal activity (), and the greatest effect was obtained with a concentration of 107 UHMWP/ml. There was a significant decrease in neutrophil bactericidal activity by incubation with particles of 0.1–5μm (), but not with larger size. The results suggest that neutrophil functional defects triggered by the presence of UHMWP particles may potentially contribute to the susceptibility of loose implants to bacterial infections. [Copyright &y& Elsevier]

Abstract: We investigated the effect of a single subcutaneous dose of zoledronic acid on particle-induced osteolysis and observed excessive regional new bone formation. We utilized the murine calvarial osteolysis model and polyethylene particles in C57BL/J6 mice. Twenty-eight mice were used, seven per group. Specimens were stained with Giemsa dye. The osteoid tissue area was determined. Bone thickness was measured as an indicator of bone growth. Net bone growth was significantly increased in animals with zoledronic acid treatment: 0.02mm2±0.03mm2 in animals with particle implantation only (group 2), 0.25mm2±0.08mm2 with particle implantation and zoledronic acid treatment directly after surgery (group 3; ), and 0.21mm2±0.11mm2 with particle implantation and zoledronic acid treatment on the fourth postoperative day (group 4; ). The mean bone thickness was 0.2mm±0.04mm (range 0.17mm–0.31mm) in group 1 (sham controls) and 0.16mm±0.02mm (range 0.14mm–0.19mm) in group 2, 0.31mm±0.04mm (range 0.28mm–0.39mm) in group 3, and 0.29mm±0.02mm (range 0.28mm–0.34mm) in group 4. Student''s t-test revealed a statistically significant difference between groups 2 and 3 (), and groups 2 and 4 (). In conclusion, our observational study suggests that zoledronic acid may stimulate bone apposition locally in the process of particle-induced osteolysis. [Copyright &y& Elsevier]

A characteristic bony structure found at revision surgery for failed joint replacement, and implicated as being associated with poorer subsequent implant fixation, is a sclerotic bone rim (SB rim). This study is a histomorphometric analysis of the SB rim formed around an experimental canine micro-motion implant system under stable or unstable conditions with polyethylene (PE) particles, after 8 weeks. A point count histomorphometric analysis was performed to determine the cellular activity at the surface of the SB rim, and the morphology of the structure was determined by image analysis. A SB rim was found to form under both stable and unstable conditions, but with unstable conditions the rim was more distinct, thick, continuous, and was located near the drill hole, and had high and ongoing formative activity at both surfaces with little resorption. Under stable conditions, thinner second or third SB rims were observed. The difference in width and distance between implant and the SB rim is significant (p<0.05), as was the difference in fraction of resorption surfaces at the SB surface facing the implant. This study observed an in vivo primary bone response to controlled stable and unstable loaded implants. Sclerosis of trabeculae in a semi-continuous SB rim can serve to isolate the implant from the marrow space. The increases in SB rim width and continuity is consistent with the previously demonstrated knowledge that increase of total bone mass and low risk for trabeculae perforation is the consequence of low resorptive and high formative activity. [Copyright &y& Elsevier]

Static electricity is the cause of many problems in the process industries, in particular, when handling powders and granules. The methods usually used to reduce static electricity involve the addition of antistatic agents, the increase of relative humidity or ionisation. But these solutions can give rise to other problems. The purpose of this paper is, first, to study the kinetics of electrostatic charging of polyethylene granules and powders in a fluidised bed and, second, to study the elimination of the static electricity using the same particles with a special supersonic injector producing a neutral cloud of positive and negative ions. The experiments involve taking samples of particles at various times and various locations in the bed and measuring the charge-to-mass ratio by means of a Faraday pail connected to an electrometer. It is found that the electrostatic charge increases during fluidisation up to a limiting value. Concerning the charges elimination, it is shown that ions ejected from the eliminator cannot penetrate into the bulk of particles. Only the particles on the upper surface of the bed are discharged. Thus, the efficiency of the supersonic injector for overall charge neutralisation depends on the movement of the particles in the bed and, in particular, the rate of renewal of the upper surface of the fluidised bed. [Copyright &y& Elsevier]

The demonstration that one of the mechanisms of action of bisphosphonates (BPs) is the induction of osteoclast and macrophage apoptosis, suggests a potent therapeutic role for the BPs and other apoptosis-modulating agents in the management of periprosthetic osteolysis. The purpose of this study was to improve our understanding of the basic underlying molecular events leading to the inhibitory effect of pamidronate on the macrophage response to ultra-high-molecular-weight polyethylene (UHMWPE) particles. Murine J774 macrophages were incubated for 0–72 h in the presence of UHMWPE particles and/or pamidronate. TNF-α release was measured by ELISA while poly(ADP-ribose)polymerase (PARP) expression was measured by Western blot. DNA was analyzed on agarose. The appearance of PARP fragment and the fragmentation of DNA were used as markers of apoptosis. We observed a dose-dependent response to UHMWPE particles with TNF-α release reaching 4, 10, and 19 times control with 10, 25, and 125 particles/macrophage, respectively. UHMWPE particles (25 particles/macrophage) stimulate TNF-α release by a factor of 10, 7, and 6 after 24, 48, and 72 h, respectively, indicating a rapid stimulating effect of UHMWPE particles on TNF-α release. Our results also showed that at 10 particles/macrophage, pamidronate inhibits UHMWPE-induced TNF-α release by 12%, 14%, and 23% respectively after 24, 48, and 72 h (p<0.05 vs. 24 and 48 h). With 25 particles/macrophage, the inhibition of TNF-α reached 9%, 12%, and 15% after 24, 48, and 72 h (p<0.05 vs. 24 h), respectively. There is no significant difference between the inhibition by pamidronate of TNF-α release induced by 125 particles/macrophages at 24, 48, and 72 h. When cells are pre-incubated for 48 h with pamidronate prior to addition of UHMWPE particles for 24 h, we observed an increased inhibition of TNF-α compared to the co-incubation protocol. The inhibiting effect of pamidronate reaches 56% when pre-incubated with macrophages prior to incubation with 10 particles of UHMWPE/macrophage (p<0.05 vs. co-incubation).Co-incubation of pamidronate with UHMWPE particles also led to the appearance of the proteolytic PARP fragment after 24 h incubation. We also demonstrated the stimulation of DNA fragmentation (DNA laddering) after 48–72 h with pamidronate. The proteolytic cleavage of PARP, an early event in the induction of apoptosis, precedes the inhibition of UHMWPE particle-induced TNF-α release by pamidronate whereas the fragmentation of DNA, a late apoptotic event, parallels this inhibition. Our results suggest the induction of macrophage apoptosis is associated with the inhibitory effect of pamidronate on TNF-α release. There is a need for the development of medical management of periprosthetic osteolysis. The demonstration that drugs such as pamidronate induce specific apoptosis-related pathways in macrophages contributes data for a rational approach in the treatment and/or prevention of periprosthetic osteolysis. [Copyright &y& Elsevier]

Slugging experiments were performed in a fluidized bed of 7 cm ID and 50 cm in height to examine the maximum bed height with an expanded section. High-density polyethylene (HDPE) particles of 0.5 mm were employed as the bed materials. The slugging bed height was linearly increased with the gas velocity in the beds of uniform cross section as well as expanded section with different slope. From the results of this study, it was found that the existing correlation to predict the slugging bed height based on the heavier particles for the uniform cross section area was satisfactorily applied for the lighter particles of HDPE and for the expanded section, a slight modification was made for the particle of HDPE in the slugging bed. [ABSTRACT FROM AUTHOR]

[Display omitted] • 28-days PE-MP exposure alters the cell growth of freshwater primary producers. • M. aeruginosa reversed the adverse effects of PE-MPs on cell growth after 3–7 days of exposure. • After 28 days of PE-MP exposure, primary producers exhibited decreased gross photosynthesis. • PE-MPs mainly altered the cell respiration of freshwater primary producers. • 28-days PE-MP exposure decreased MC release without modifying MC synthesis. The ecological impacts of microplastic particles are primary environmental concerns. In this study, we selected three polyethylene particles (white, blue and fluorescent-blue microspheres, PE-MPs) and tested their effects on the growth and photosynthetic activity of the green algae Scenedesmus armatus and the cyanobacterium Microcystis aeruginosa after 28 days of exposure to 250, 500 and 1000 μg mL−1 concentrations. The white or fluorescent blue microspheres induced significant decrease on S. armatus cell growth in a concentration- and time-dependent manner, while blue microspheres did not induce significant differences in cell growth relative to that in the control. Although the M. aeruginosa strain initially underwent a reduction in exponential growth, the growth was able to recover and reach the value in the control group after the seventh day of exposure. In the same way, the three polyethylene-type microspheres had the ability to alter the photosynthetic activity of the S. armatus and M. aeruginosa strains after 28 days of exposure, mainly altering between 50–85 % of the light respiration depending on the strain and type of microplastic. Additionally, in all cases, microcystin release from M. aeruginosa after 28 days of exposure showed a moderate reduction of approximately 15 % compared to that in the control group, without the cellular synthesis of microcystin being altered. The interspecies differences in the magnitude of the effect produced by each type of microplastic highlight the need for further research on different chemical PE-MP compositions with additional test organisms to comprehensively understand MP pollution in aquatic-exposed organisms. [ABSTRACT FROM AUTHOR]

Wear debris generated from the bearing surfaces of joint arthroplasties leads to acute and chronic inflammation, which is strongly associated with implant failure. Macrophages derived from monocytes recruited to the local tissues have a significant impact on bone healing and regeneration. Macrophages can adopt various functional phenotypes. While M1 macrophages are pro-inflammatory, M2 macrophages express factors important for tissue repair. Here, we established a 3D co-culture system to investigate how the immune system influences the osteogenic differentiation of mesenchymal stem cells (MSCs) in the presence of micron-sized particles. This system allowed for the simulation of an inflammatory reaction via the addition of Lipopolysaccharide-contaminated polyethylene particles (cPE) and the characterization of bone formation using micro-CT and gene and protein expression. Co-cultures of MSCs with M2 macrophages in the presence of cPE in a 3D environment resulted in the increased expression of osteogenic markers, suggesting facilitation of bone formation. In this model, the upregulation of M2 macrophage expression of immune-associated genes and cytokines contributes to enhanced bone formation by MSCs. This study elucidates how the immune system modulates bone healing in response to an inflammatory stimulus using a unique 3D culture system. [ABSTRACT FROM AUTHOR]

Microplastics (MPs), as a new type of environmental pollutant, pose a serious threat to soil ecosystems. The activities of soil extracellular enzymes produced by microorganisms are the potential sensitive indicators of soil quality. However, little is known about the response mechanism of enzyme activities toward MPs on a long-term scale. Moreover, information on differences in enzyme activities across different soil aggregates is lacking. In this study, 150 days of incubation experiments and soil aggregate fractionation were combined to investigate the influence of MPs on extracellular enzyme activities in soil. 28% concentration of polyethylene with size 100 μm was adopted in the treatments added with MPs. The results show that MPs inhibited enzyme activities through changing soil nutritional substrates and physicochemical properties or through adsorption. Moreover, MPs competed with soil microorganisms for physicochemical niches to reduce microbial activity and eventually, extracellular enzyme activity. Enzyme activities in different aggregate-size fractions responded differently to the MPs exposure. The catalase in the coarse particulate fraction and phenol oxidase and β-glucosidase in the micro-aggregate fraction exerted the greatest response. With comparison, urease, manganese peroxidase, and laccase activities showed the greatest responses in the non-aggregated silt and clay fraction. These observations are believed to stem from differences in the key factors determining the enzyme activities in different aggregate-size fractions. The inhibitory pathway of microplastics on activities of extracellular enzymes in soil varies significantly across different aggregate fractions. Image 1 • Microplastics (MPs) significantly inhibited extracellular enzyme activities in soil. • MPs affected enzyme activities through adsorption and altering microenvironment. • Effect of MPs on enzyme activities varied across different soil aggregate levels. • DOC and OP were significant factors shaping enzyme activities in the presence of MPs. • Enzyme activities was more sensitive to MPs in the smaller soil aggregate fraction. [ABSTRACT FROM AUTHOR]

Highlights Microplastics can alter the physicochemical and biogeochemical processes in soil, but whether these alterations have further the effects on the transformation of soil heavy metal speciation, and if so, whether these effects vary across soil aggregate levels remain unknown. Herein, long-term soil culture experiments and soil fractionation are combined to investigate the effects of microplastics on chemical speciation of Cu, Cr, and Ni with different particle-size soil aggregates. Results show that microplastics in soil decrease the exchangeable, carbonate-bound, and Fe-Mn oxide-bound fractions of metals but increase their organic-bound fractions via direct adsorption and indirect effects on the soil microenvironment conditions. The findings suggest that microplastics can promote the transformation of heavy metal speciation from bioavailable to organic bound. Such promotion exerts notable differences across soil aggregate levels. The transformation of soil heavy metal speciation is greater in larger aggregates than in smaller aggregates in the early incubation period with microplastics but shows the opposite trend in the later incubation period. Therefore, this process is more sensitive to long-term microplastic pollution in smaller aggregates than in larger aggregates, most likely owing to the lag in the influence of microplastics on metal speciation transformation in the smaller aggregates. [ABSTRACT FROM AUTHOR]

Background: Wear particle-induced osteolysis could lead to the aseptic loosening of implants. Studies have suggested that endotoxins, such as lipopolysaccharides (LPS), may be the primary causes of wear particle-mediated osteolysis, and that osteolysis may originate from subclinical levels of bacterial infection. However, effective therapies against wear particles and gram-negative bacterial or LPS-induced bone resorption are limited. Materials and Methods: In the current study, the effect of berberine on LPS- and polyethylene (PE) particle-induced osteolysis in vivo was investigated using a mouse calvarial model. Osteoclast number per bone perimeter and eroded surface per bone surface were measured. Results: Berberine (10 mg/kg), injected either simultaneously with LPS or 3 d after LPS (25 mg/kg) treatment, blocked LPS-induced osteoclast recruitment and bone resorption in the mouse calvarial model. A daily single-dose of berberine (10 mg/kg), injected either simultaneously with PE particles or 4 d after treatment with PE particles, blocked PE particle-induced osteoclast recruitment and bone resorption. Berberine treatment markedly decreased LPS and PE particle-induced osteoclast recruitment and bone resorption in the murine calvarial model. Conclusion: These results suggest that berberine may have therapeutic effect for osteolysis induced by wear particles and LPS in gram-negative bacteria. [ABSTRACT FROM AUTHOR]