Analysis of bearing wear, whole blood and synovial fluid metal ion concentrations and histopathological findings in patients with failed ASR hip resurfacings

Background Adverse Reaction to Metal Debris (ARMD) is still a major reason for revision surgeries in patients with metal-on-metal (MoM) hip replacements. ARMD consists of a wide range of alterations in periprosthetic tissues, most important of which are metallosis, inflammation, pseudotumors and necrosis. Studies investigating histopathological findings and their association to implant wear or indirect measures of wear have yielded inconsistent results. Therefore, we aimed to investigate bearing surface wear volume, whole blood and synovial fluid metal ion concentrations, histopathological findings in periprosthetic tissues and their associations. Methods Seventy-eight patients with 85 hips revised for ARMD were included in the study. Prior to revision surgery, all patients had whole blood chromium and cobalt ion levels assessed. In revision surgery, a synovial fluid sample was taken and analyzed for chromium and cobalt. Periprosthetic tissue samples were taken and analyzed for histopathological findings. Explanted implants were analyzed for bearing wear volume of both acetabular cup and femoral head components. Results Volumetric wear of the failed components was highly variable. The total wear volume of the head and cup had a strong correlation with whole blood chromium and cobalt ion concentrations (Cr: ρ = 0.80, p < 0.001 and Co: ρ = 0.84, p < 0.001) and a bit weaker correlation with fluid chromium and cobalt ion concentrations (Cr: ρ = 0.50, p < 0.01 and Co: ρ = 0.41, p = 0.027). Most tissues displayed only low-to-moderate amounts of macrophages and lymphocytes. Total wear volume correlated with macrophage sheet thickness (ρ = 0.25, p = 0.020) and necrosis (ρ = 0.35, p < 0.01). Whole blood chromium and cobalt ion concentrations had similar correlations. Lymphocyte cuff thickness did not correlate with either total wear volume or whole blood metal ion concentrations, but correlated with the grade of necrosis. Conclusions Bearing wear volume correlated with blood metal ion levels and the degree of necrosis and macrophage infiltration in periprosthetic tissues suggesting a dose-response relationship. Whole blood metal ion levels are a useful tool for clinician to estimate bearing wear and subsequent tissue response

Curcumin as Treatment for Bladder Cancer : A Preclinical Study of Cyclodextrin-Curcumin Complex and BCG as Intravesical Treatment in an Orthotopic Bladder Cancer Rat Model

Objective. To evaluate the antitumor effect of cyclodextrin-curcumin complex (CDC) on human and rat urothelial carcinoma cells in vitro and to evaluate the effect of intravesical instillations of CDC, BCG, and the combination in vivo in the AY-F344 orthotopic bladder cancer rat model. Curcumin has anticarcinogenic activity on urothelial carcinoma and is therefore under investigation for the treatment of non-muscle invasive bladder cancer. Curcumin and BCG share immunomodulating pathways against urothelial carcinoma. Methods. Curcumin was complexed with cyclodextrin to improve solubility. Four human urothelial carcinoma cell lines and the AY-27 rat cell line were exposed to various concentrations of CDC in vitro. For the in vivo experiment, the AY-27 orthotopic bladder cancer F344 rat model was used. Rats were treated with consecutive intravesical instillations of CDC, BCG, the combination of CDC+BCG, or NaCl as control. Results. CDC showed a dose-dependent antiproliferative effect on all human urothelial carcinoma cell lines tested and the rat AY-27 urothelial carcinoma cell line. Moreover, intravesical treatment with CDC and CDC+BCG results in a lower percentage of tumors (60% and 68%, respectively) compared to BCG (75%) or control (85%). This difference with placebo was not statistically significant (p=0.078 and 0.199, respectively). However, tumors present in the placebo and BCG-treated rats were generally of higher stage. Conclusions. Cyclodextrin-curcumin complex showed an antiproliferative effect on human and rat urothelial carcinoma cell lines in vitro. In the aggressive orthotopic bladder cancer rat model, we observed a promising effect of CDC treatment and CDC in combination with BCG.Peer reviewe

Predictors of osteoarthritis following operative treatment of medial tibial plateau fractures

Purpose: To determine factors influencing the development of posttraumatic osteoarthritis (OA) following medial tibial plateau fractures and to evaluate concomitant injuries associated with these fractures. Materials and methods: A chart review of patients with operatively treated medial tibial plateau fractures admitted to our Level I trauma centre from 2002 to 2008 was performed. Of 63 patients, 41 participated in a clinical and radiographic examination. The mean age was 47 years (range 16-78) and the mean follow-up time was 7.6 (range 4.7-11.7) years. All patients had preoperative computed tomography (CT) scans and postoperative radiographs. At the end of follow-up, standing radiographs, mechanical axis, and CT scans were evaluated. Results: Of the 41 patients, 24 had no or mild (Kellgren-Lawrence grade 0-2) OA and 17 had severe (grade 3-4) OA. Initial articular depression measured from preoperative CT scans was a significant predictor of OA (median 1.8 mm vs 4.5 mm, p = 0.009). Fracture line extension to the lateral plateau (p = 0.68) or fracture comminution (p = 0.21) had no effect on the development of posttraumatic OA, nor did articular depression at the end of follow-up (p = 0.68) measured from CT scans. Mechanical axis >4 degrees of varus and >= 2 mm articular depression or step-off were associated with worse WOMAC pain scores, but did not affect other functional outcome scores. Six patients (10%) had permanent peroneal nerve dysfunction. Ten patients (16%) required LCL reconstruction and nine (14%) ACL avulsions were treated at the time of fracture stabilisation. Conclusions: The amount of articular depression measured from preoperative CT scans seems to predict the development of posttraumatic OA, probably reflecting the severity of chondral injury at the time of fracture. Restoration of mechanical axis and articular congruence are important in achieving a good clinical outcome. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe

Evidential Proximity, Independence, and the evaluation of carcinogenicity

This paper analyses the methods of the International Agency for Research on Cancer (IARC) for evaluating the carcinogenicity of various agents. I identify two fundamental evidential principles that underpin these methods, which I call Evidential Proximity and Independence. I then show, by considering the 2018 evaluation of the carcinogenicity of styrene and styrene‐7,8‐oxide, that these principles have been implemented in a way that can lead to inconsistency. I suggest a way to resolve this problem: admit a general exception to Independence and treat the implementation of Evidential Proximity more flexibly where this exception applies. I show that this suggestion is compatible with the general principles laid down in the 2019 version of IARC's methods guide, its Preamble to the Monographs

Palmitate and thapsigargin have contrasting effects on ER membrane lipid composition and ER proteostasis in neuronal cells

The endoplasmic reticulum (ER) is an organelle that performs several key functions such as protein synthesis and folding, lipid metabolism and calcium homeostasis. When these functions are disrupted, such as upon protein misfolding, ER stress occurs. ER stress can trigger adaptive responses to restore proper functioning such as activation of the unfolded protein response (UPR). In certain cells, the free fatty acid palmitate has been shown to induce the UPR. Here, we examined the effects of palmitate on UPR gene expression in a human neuronal cell line and compared it with thapsigargin, a known depletor of ER calcium and trigger of the UPR. We used a Gaussia luciferase-based reporter to assess how palmitate treatment affects ER proteostasis and calcium ho-meostasis in the cells. We also investigated how ER calcium depletion by thapsigargin affects lipid membrane composition by performing mass spectrometry on subcellular fractions and compared this to palmitate. Sur-prisingly, palmitate treatment did not activate UPR despite prominent changes to membrane phospholipids. Conversely, thapsigargin induced a strong UPR, but did not significantly change the membrane lipid composition in subcellular fractions. In summary, our data demonstrate that changes in membrane lipid composition and disturbances in ER calcium homeostasis have a minimal influence on each other in neuronal cells. These data provide new insight into the adaptive interplay of lipid homeostasis and proteostasis in the cell.Peer reviewe

Systematic and detailed analysis of behavioural tests in the rat Middle Cerebral Artery Occlusion (MCAO) model of stroke: tests for long-term assessment

In order to test therapeutics, functional assessments are required. In pre-clinical stroke research, there is little consensus regarding the most appropriate behavioural tasks to assess deficits; especially when testing over extended times in milder models with short occlusion times and small lesion volumes. In this study we comprehensively assessed 16 different behavioural tests, with the aim of identifying those that show robust, reliable and stable deficits for up to 2 months. These tasks are regularly used in stroke research, as well as being useful for examining striatal dysfunction in models of Huntington’s and Parkinson’s disease. Two cohorts of male Wistar rats underwent the intraluminal filament model of MCAO (30min) and were imaged 24hrs later. This resulted in primarily subcortical infarcts, with a small amount of cortical damage. Animals were tested, along with sham and naïve groups at 24hrs, 7 days, and 1 and 2 months. Following behavioural testing, brains were processed and striatal neuronal counts were performed alongside measurements of total brain and white matter atrophy. The staircase, adjusting steps, rotarod and apomorphine induced rotations were the most reliable for assessing long-term deficits in the 30 min transient MCAO model of stroke

Host-specific factors affect the pathogenesis of adverse reaction to metal debris

BACKGROUND: Adverse Reaction to Metal Debris (ARMD) is a major reason for revision surgeries in patients with metal-on-metal (MoM) hip replacements. Most failures are related to excessively wearing implant producing harmful metal debris (extrinsic factor). As ARMD may also occur in patients with low-wearing implants, it has been suggested that there are differences in host-specific intrinsic factors contributing to the development of ARMD. However, there are no studies that have directly assessed whether the development of ARMD is actually affected by these intrinsic factors. METHODS: We included all 29 patients (out of 33 patients) with sufficient data who had undergone bilateral revision of ASR MoM hips (58 hips) at our institution. Samples of the inflamed synovia and/or pseudotumour were obtained perioperatively and sent to histopathological analysis. Total wear volumes of the implants were assessed. Patients underwent MARS-MRI imaging of the hips preoperatively. Histological findings, imaging findings and total wear volumes between the hips of each patient were compared. RESULTS: The difference in wear volume between the hips was clinically and statistically significant (median difference 15.35 mm^{3}, range 1 to 39 mm^{3}, IQR 6 to 23 mm^{3}) (p  0.05 for all comparisons). These features included macrophage sheet thickness, perivascular lymphocyte cuff thickness, presence of plasma cells, presence of diffuse lymphocytic infiltration and presence of germinal centers. CONCLUSIONS: Despite the significantly differing amounts of wear (extrinsic factor) seen between the sides, majority of the histological findings were similar in both hips and the presence of pseudotumour was symmetrical in most hips. As a direct consequence, it follows that there must be intrinsic factors which contribute to the symmetry of the findings, ie. the pathogenesis of ARMD, on individual level. This has been hypothesized in the literature but no studies have been conducted to confirm the hypothesis. Further, as the threshold of metal debris needed to develop ARMD appears to be largely variable based on the previous literature, it is likely that there are between-patient differences in these intrinsic factors, ie. the host response to metal debris is individual

An object oriented Python interface for atomistic simulations

Programmable simulation environments allow one to monitor and control calculations efficiently and automatically before, during, and after runtime. Environments directly accessible in a programming environment can be interfaced with powerful external analysis tools and extensions to enhance the functionality of the core program, and by incorporating a flexible object based structure, the environments make building and analysing computational setups intuitive. In this work, we present a classical atomistic force field with an interface written in Python language. The program is an extension for an existing object based atomistic simulation environment.&nbsp;</p