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Wear Particles (wear + particle)
Selected AbstractsActivation of NF-KB signalling and TNF,-expression in THP-1 macrophages by TiAlV- and polyethylene-wear particlesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2005Bernd Baumann Abstract Wear particles are believed to induce periprosthetic inflammation which contributes to periprosthetic osteolysis. TNF, plays a pivotal role in the pathogenesis of this process. The molecular mechanisms leading to the development of periprosthetic inflammation with upregulated TNF, 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-kB signalling pathways and TNF, 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. TNF, release was analyzed in culture supernatant by ELISA. NF-kB activation was examined by electrophoretic mobility shift assay (EMSA), and NF-kB target promoter activities including transactivation of the TNF, promoter were determined by luciferase reporter gene assays. Differentiated THP-1 macrophages were exposed to increasing numbers of particles for 0, 60, 180 and 360 min. Both, polyethylene- and TiAlV-particles induced a significant activation of both NF-kB and TNF, promoters at 180 min. A significant TNF, release was detected after 360 min exposure to polyethylene- and TiAlV-particles in a dose dependent manner. In comparison, LPS induced a much greater activation of NF-kB and TNF, promoters, and TNF, secretion into the supernatant was strongly induced. These results provide evidence that induction of the NF-kB signal transduction pathway in macrophages plays a major role in initiating and mediating the inflammatory response leading to periprosthetic osteolysis. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Gene expression in endoprosthesis loosening: Chitinase activity for early diagnosis?,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2008L. Morawietz Abstract The aim of the study was to identify markers for the early diagnosis of endoprosthesis loosening, for the differentiation between wear particle,induced and septic loosening and to gather new insights into the pathogenesis of endoprosthesis loosening. Gene expression profiles were generated from five periprosthetic membranes of wear particle,induced and five of infectious (septic) type using Affymetrix HG U133A oligonucleotide microarrays. The results of selected differentially expressed genes were validated by RT-PCR (n,=,30). The enzyme activity and the genotype of chitinase-1 were assessed in serum samples from 313 consecutive patients hospitalized for endoprosthesis loosening (n,=,54) or for other reasons, serving as control subjects (n,=,259). Eight hundred twenty-four genes were differentially expressed with a fold change greater than 2 (data sets on http://www.ncbi.nlm.nih.gov/geo/ GSE 7103). Among these were chitinase 1, CD52, calpain 3, apolipoprotein, CD18, lysyl oxidase, cathepsin D, E-cadherin, VE-cadherin, nidogen, angiopoietin 1, and thrombospondin 2. Their differential expression levels were validated by RT-PCR. The chitinase activity was significantly higher in the blood from patients with wear particle,induced prosthesis loosening (p,=,0.001). However, chitinase activity as a marker for early diagnosis has a specificity of 83% and a sensitivity of 52%, due to a high variability both in the disease and in the control group. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:394,403, 2008 [source] Characteristic modeling of the wear particle formation process from a tribological testing of polyethylene with controlled surface asperitiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Hsu-Wei Fang Abstract To study the ultra-high molecular weight polyethylene (UHMWPE) wear particles-induced osteolysis which leads to the failure of artificial joints, microfabricated surfaces with controlled asperities have been applied to generate narrowly distributed UHMWPE wear particles with various sizes and shapes. Our previous study further facilitated single wedge sliding tests to investigate the mechanism of the UHMWPE particle generation. In this study, the attempt was made to characterize the particle generation process into a mathematical model to predict particle volume with a given surface-texture dimensions and mechanical loading conditions. The particle-generation process is decomposed into two steps: (1) penetration of the cutting edge, and (2) lateral sliding of the cutting edge. By combining the indentation experimental data, the viscoelastic responses of UHMWPE was incorporated in the model. The effects of normal load, feature height, and cutting edge angle on the wear particle volume were illustrated from model predictions. Both experimental results and model predictions indicate the same trend of effects of surface-texture geometry and mechanical conditions on the volume of particles. The results of the model predictions are close to the experimental results of the particle generation. However, the particle volume predicted by the model is larger than the experimental results. It is believed that the reprocessing of the generated particles and viscoelastic recovery of UHMWPE in the experiments account for this difference. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 587,594, 2007 [source] Wear particle analysis of highly crosslinked polyethylene isolated from a failed total hip arthroplastyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008Yukihide Minoda Abstract Polyethylene wear particles are one of the most important factors affecting the results of total hip arthroplasty (THA). To reduce wear generation and to achieve better long-term results of THA, highly crosslinked polyethylene (HXPE) has recently been introduced and come into wide use. Thus far, however, there have been no reports on in vivo analysis of HXPE wear particles. We isolated HXPE wear particles from periprosthetic tissue of a failed THA and analyzed using scanning electron microscope. The number of particles was 5.33 × 107 g,1. Particle size (equivalent circle diameter) was 0.66 ± 0.40 ,m (mean ± standard error). Aspect ratio and roundness were 1.37 ± 0.26 and 1.44 ± 0.67, respectively. All the particles were round shaped, and "fibrils" or "shreds" were not detected. Thus far, this was the first report on in vivo wear particle analysis of HXPE. HXPE generated less, smaller, and rounder particles, compared with the corresponding reported values for particles generated from conventional polyethylene. These characteristics might affect macrophage response, osteolysis, and long-term results of THA with HXPE. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Standardized analysis of UHMWPE wear particles from failed total joint arthroplastiesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 5 2002Jay D. Mabrey Abstract Periprosthetic tissue obtained at revision surgery from eight total hip replacement cases was hydrolyzed, and polyethylene debris particles were isolated from each case. Individual particles were analyzed by scanning electron microscopy (SEM) and computerized image analysis in accordance with ASTM F1877-98, a standard for quantitative description of wear debris. For comparison, periprosthetic tissues from eight total knee revision and four total shoulder revision cases were processed and analyzed with identical methods. A total of 2599 hip, 4345 knee, and 1200 shoulder particles were analyzed. The morphologies of the isolated polyethylene particles from the total hip specimens were distinctly different from the total knee and total shoulder particles. The mean equivalent circle diameter (ECD) for hip particles was 0.694 ,m ± 0.005; knee particles measured 1.190 ,m ±0.009; and shoulder particles 1.183 ,m ± 0.017. The ECD was significantly different between hip particles and those from the shoulder and knee. The mean aspect ratio (AR) for the hip particles was 1.626 ± 0.015, compared to the knee particles at 1.935 ± 0.015 and shoulder particles at 2.082 ± 0.033. The AR was statistically different among all three groups. Other descriptors from the ASTM standard, elongation (E), form factor (FF), and roundness (R) were all significantly different among the three groups of joints. This study demonstrates the utility of ASTM F1877-98 in differentiating wear debris particles from different sources. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 475,483, 2002 [source] Stimulation of macrophage TNF, production by orthopaedic wear particles requires activation of the ERK1/2/Egr-1 and NF-,B pathways but is independent of p38 and JNKJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2008Michelle A. Beidelschies Bone loss that causes aseptic loosening of orthopedic implants is initiated by pro-inflammatory cytokines produced by macrophages in response to implant-derived wear particles. MAPK and NF-,B signaling pathways are activated by the particles; however, it is not clear which of the signaling pathways are important for the initial response to the wear particles and which are only involved at later steps in the process, such as osteoclast differentiation. Here, we show that the ERK1/2, p38, JNK, and NF-,B pathways are rapidly activated by the wear particles but that only the ERK1/2 and NF-,B pathways are required for the initial response to the wear particles, which include increases in TNF, promoter activity, TNF, mRNA expression, and secretion of TNF, protein. Moreover, ERK1/2 activation by wear particles is also required for increased expression of the transcription factor Egr-1 as well as Egr-1's ability to bind to and activate the TNF, promoter. These results, together with our previous studies of the PI3K/Akt pathway, demonstrate that wear particles coordinately activate multiple signaling pathways and multiple transcription factors to stimulate production of pro-inflammatory cytokines, such as TNF,. The current study also demonstrates that the signaling pathways are activated to a much greater extent by wear particles with adherent endotoxin than by "endotoxin-free" wear particles. These results, together with those demonstrating the requirement for ERK1/2/Egr-1 and NF-,B, show that activation of these signaling pathways is responsible for the ability of adherent endotoxin to potentiate cytokine production, osteoclast differentiation, and bone loss induced by wear particles. J. Cell. Physiol. 217: 652,666, 2008. © 2008 Wiley-Liss, Inc. [source] Involvement of complement receptor 3 (CR3) and scavenger receptor in macrophage responses to wear debrisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2006Diptendu S. Rakshit Abstract The ability of prosthetic wear debris to induce pro-inflammatory responses in macrophages is widely appreciated, but little is known about the molecular mechanisms involved in particle recognition. Specifically, the nature of the cell surface receptors that interact with wear debris is poorly understood. Elucidating the identities of these receptors and how they interact with different types of wear debris are critical to understanding how wear debris initiates periprosthetic osteolysis. We examined the involvement of opsonization, complement receptor 3 (CR3), and scavenger receptor A (SRA), in responses to polymethylmethacrylate (PMMA) and titanium wear particles. Serum dependence of pro-inflammatory responses to PMMA and titanium was tested, and serum proteins that adhered to these two types of particles were identified. Several serum proteins, including known opsonins such as C3bi and fibronectin, adhered to PMMA but not titanium, and serum was required for pro-inflammatory signaling induced by PMMA, but not by titanium. Phagocytosis of PMMA and titanium by macrophages was demonstrated by flow cytometry. Blocking CR3 specifically inhibited phagocytosis of PMMA by macrophages, whereas blocking SRA specifically inhibited titanium uptake. Direct involvement of CR3 and SRA in cell,particle interaction was assessed by expression of these receptors in nonphagocytic HEK293 cells. CR3 specifically induced cell binding to PMMA particles and adhesion to PMMA-coated plates, while SRA specifically induced binding to titanium particles and adhesion to titanium-coated plates. Taken together, these results suggest involvement of opsonization, complement, and integrin receptors, including CR3 and fibronectin receptors, in PMMA action, and an involvement of scavenger receptors in responses to titanium. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:2036,2044, 2006 [source] Activation of NF-KB signalling and TNF,-expression in THP-1 macrophages by TiAlV- and polyethylene-wear particlesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2005Bernd Baumann Abstract Wear particles are believed to induce periprosthetic inflammation which contributes to periprosthetic osteolysis. TNF, plays a pivotal role in the pathogenesis of this process. The molecular mechanisms leading to the development of periprosthetic inflammation with upregulated TNF, 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-kB signalling pathways and TNF, 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. TNF, release was analyzed in culture supernatant by ELISA. NF-kB activation was examined by electrophoretic mobility shift assay (EMSA), and NF-kB target promoter activities including transactivation of the TNF, promoter were determined by luciferase reporter gene assays. Differentiated THP-1 macrophages were exposed to increasing numbers of particles for 0, 60, 180 and 360 min. Both, polyethylene- and TiAlV-particles induced a significant activation of both NF-kB and TNF, promoters at 180 min. A significant TNF, release was detected after 360 min exposure to polyethylene- and TiAlV-particles in a dose dependent manner. In comparison, LPS induced a much greater activation of NF-kB and TNF, promoters, and TNF, secretion into the supernatant was strongly induced. These results provide evidence that induction of the NF-kB signal transduction pathway in macrophages plays a major role in initiating and mediating the inflammatory response leading to periprosthetic osteolysis. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] The effectiveness of polyethylene versus titanium particles in inducing osteolysis in vivo,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2004Marius von Knoch Abstract Bearing surface wear and periprosthetic osteolysis due to wear particles are among the most common reasons for joint replacement failure. A murine calvarial model of wear particle-induced osteolysis has been used to identify different biologic factors associated with this problem and to test nonsurgical methods of modulating the host response to particulate debris. This model has utilized titanium particles, however, in clinical practice the most common source of particulate debris is polyethylene particles from bearing surface wear. We now report a calvarial model of wear particle-induced osteolysis based on commercially available polyethylene particles. We found that compared to sham surgery osteoclast recruitment and bone resorption can be induced by introduction of the titanium particles or polyethylene particles. However, bone resorption was significantly higher with polyethylene particles compared to titanium particles (p = 0.02). We consider the polyethylene based murine calvarial model of wear particle-induced osteolysis a reliable and clinically relevant tool to understand the host factors and potential pharmacologic interventions that can influence wear debris generated osteolysis. This model might serve as an extension of the well-established titanium based bone resorption model. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] The role of osteoclast differentiation in aseptic loosening,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2002Edward M. Greenfields The major cause of orthopaedic implant loosening is thought to be accelerated osteoclastic bone resorption due to the action of cytokines produced in response to phagocytosis of implant-derived wear particles. This accelerated osteoclastic bone resorption could be due to increases in any of the following processes: recruitment of osteoclast precursors to the local microenvironment, differentiation of precursors into mature multinucleated osteoclasts, activation of mature osteoclasts, and/or survival of osteoclasts. Our studies have focused on differentiation and survival to complement work by others who have focused on recruitment of precursors and activation. Taken together, our studies and those of other investigators provide strong evidence that increased recruitment of osteoclast precursors and their subsequent differentiation play major roles in wear particle-induced osteolysis. In contrast, increased osteoclast activation and survival appear to play minor roles. These studies suggest that development of therapeutic interventions that reduce either recruitment or differentiation of osteoclast precursors would improve the performance of orthopaedic implants. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] A disc brake test stand for measurement of airborne wear particlesLUBRICATION SCIENCE, Issue 6 2009Jens Wahlström Abstract During braking, there is wear on both the rotor and the pads. This process generates particles that may become airborne. In field tests, it is difficult to distinguish these particles from others in the surrounding environment. Therefore, a laboratory test stand has been designed which allows control of the cleanliness of the surrounding air. The test stand consists of a front right brake assembly mounted in a sealed chamber. A braking load is applied by a pneumatic system and the rotor, which has been pre-conditioned with a rust layer to simulate a car standing parked overnight in a wet environment, is driven by an electric motor. The number and size of airborne wear particles are then measured. This experimental set-up has been verified by an initial test series performed at low braking loads. The results suggest that this test stand can be used to study rust layer removal from the rotor. Copyright © 2009 John Wiley & Sons, Ltd. [source] A fast method for computing time-dependent normal pressure distributions with cellular automatonPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Matthias Graf When two bodies slide against each other, one part of the dissipated energy causes a topography change. Tribological research on brake bads shows a rich dynamic of the boundary layer: plateau-like structures of a typical length scale grow with time due to agglomerating wear particles and collapse spontaneously at a stability limit [4], [1]. This time-dependent behaviour can be modeled with cellular automata, which consider local resolution of temperature, wear particle density and frictional power [4]. Beside this the instationary normal pressure distribution and the distinction between areas with and without contact is expected to have a significant influence [3]. This paper derives a fast scheme to estimate the time-variant pressure distribution of a deterministic and dynamic topography by a cellular automaton. The approach is discussed in the light of computational performance and the solution's characteristics. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fast element mapping of titanium wear around implants of different surface structuresCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2006Ulrich Meyer Abstract: The effect of unintended titanium release around oral implants remains a biological concern. The current study was undertaken to evaluate a new detection system of element mapping in biological probes. A new scanning electron microscopy-energy dispersive spectroscopy detection method was used to map the features of titanium contamination in peri-implant bone around implants with different surface structures. The amount of titanium wear was highest adjacent to titanium-plasma-sprayed surfaces, followed by sandblastered large grid acid-etched and smooth surfaces. A high sensitivity of titanium detection over large areas of bone tissue was observed. A high spatial resolution of titanium wear particles (20 nm) could be reached and correlated to the ultrastructural morphological features of peri-implant tissue. Cells adjacent to titanium wear revealed no signs of morphological alterations on a nanoscale level at early periods of implant/bone interaction. The new technique may serve as a fast and effective tool to evaluate titanium release effects in biological probes. [source] | ||||||||||||||||