Influence of FeCl3 and H2O2 in corrosion testing of modular taper connections in total hip arthroplasty: An in vitro study.

Corrosion at the modular taper junctions in total hip arthroplasty is clinically relevant because wear particles and ions generated at this interface can lead to adverse local tissue reactions or even implant failure. In vitro tribo-corrosion tests are usually accomplished in saline solutions or calf serum (CS), but the addition of H2O2 and FeCl3 have been suggested to mimic inflammatory conditions in the joint. Inflammatory conditions may aggravate corrosive processes and, therefore, should lead in vitro to a more severe and realistic tribo-corrosive material attack. Corrosion testing at 12/14 tapers comprising a CoCrMo head taper and a Ti6Al4V trunnion was accomplished in five electrolytes (Ringer's solution (RS), RS with 30 mM H2O2 and/or 0.7 mM FeCl3 and CS) under dynamical loading for five million cycles. Resulting material loss was determined gravimetrically and by ion analysis. The tribo-corrosive material degradation was investigated by light and electron microscopy. FeCl3 enhanced the material loss from taper connections while H2O2 did not lead to a significant alteration of total material loss. In comparison to pure RS, corrosion testing in CS decreased material loss at the head taper while it increased material loss at the trunnion. The combination of FeCl3 and H2O2 led to an enhanced occurrence of micro cracks at the trunnion surface. Adding FeCl3 and optionally also H2O2 aggravates material loss in in vitro corrosion testing of taper junctions and leads to harsher and probably more realistic testing conditions. STATEMENT OF SIGNIFICANCE: Tribo-corrosive processes at taper connections in hip implants are complex and can lead to major clinical implications. Joint inflammation is assumed to aggravate taper corrosion in vivo, why FeCl3 and H2O2 have been proposed as additives to electrolytes to simulate inflammatory conditions in vitro. Often used fretting test setups, however, do not involve real taper geometries. Besides, testing is often accomplished in saline solutions or calf serum, which do not induce a clinically significant amount of corrosive material degradation. This study presents an approach to increase tribo-corrosive processes at realistic taper connections by adding FeCl3 and/or H2O2. Unlike H2O2, FeCl3 increased material loss from taper connections. The combination of both additives enhanced micro crack formation at the trunnion surfaces.

Adipose Triglyceride Lipase Loss Promotes a Metabolic Switch in A549 Non-Small Cell Lung Cancer Cell Spheroids.

Cancer cells undergo complex metabolic adaptations to survive and thrive in challenging environments. This is particularly prominent for solid tumors, where cells in the core of the tumor are under severe hypoxia and nutrient deprivation. However, such conditions are often not recapitulated in the typical 2D in vitro cancer models, where oxygen as well as nutrient exposure is quite uniform. The aim of this study was to investigate the role of a key neutral lipid hydrolase, namely adipose triglyceride lipase (ATGL), in cancer cells that are exposed to more tumor-like conditions. To that end, we cultured lung cancer cells lacking ATGL as multicellular spheroids in 3D and subjected them to comprehensive proteomics analysis and metabolic phenotyping. Proteomics data are available via ProteomeXchange with identifier PXD021105. As a result, we report that loss of ATGL enhanced growth of spheroids and facilitated their adaptation to hypoxia, by increasing the influx of glucose and endorsing a pro-Warburg effect. This was followed by changes in lipid metabolism and an increase in protein production. Interestingly, the observed phenotype was also recapitulated in an even more "in vivo like" setup, when cancer spheroids were grown on chick chorioallantoic membrane, but not when cells were cultured as a 2D monolayer. In addition, we demonstrate that according to the publicly available cancer databases, an inverse relation between ATGL expression and higher glucose dependence can be observed. In conclusion, we provide indications that ATGL is involved in regulation of glucose metabolism of cancer cells when grown in 3D (mimicking solid tumors) and as such could be an important factor of the treatment outcome for some cancer types. Finally, we also ratify the need for alternative cell culture models, as the majority of phenotypes observed in 3D and spheroids grown on chick chorioallantoic membrane were not observed in 2D cell culture.

Retrieval Analysis of Modern Knee Tumor Megaendoprosthesis Shows Considerable Volumetric Metal Wear Generated at the Rotating Hinge.

Frequently occurring damage, as well as elevated blood metal ion levels, are reported in relation to a tumor and revision system for total knee arthroplasty (TKA), which applies a rotating hinge coupling with a metal-on-metal (MoM) articulation. As the patient collective for this specific system is small, there is no data on wear generated from the couplings. In this study, wear volume and influencing parameters were investigated at 44 retrieved TKAs with MoM couplings. A scoring system rating frequently occurring abrasive wear between 0 (no wear) and 3 (distinct wear) was established. The wear score was correlated to time in vivo, bone resection length, patient weight and polyethylene inlay damage. Volumetric wear was estimated applying coordinate measurements. An elevated wear score of two or higher was found in 43% of cases. The mean wear rate accounted to 7.8 mm3/year. The main influencing coefficient for the extent of wear is time in vivo. We found a tendency for higher wear scores with higher inlay degradation scores. Patient weight and bone resection length did not impact coupling wear. Assessment of wear damage by a semi-quantitative scoring system has proven to be a reliable option for non-destructive coupling evaluation. The generated wear volume is high.

The avian chorioallantoic membrane as an alternative tool to study medullary thyroid cancer.

Preclinical trials of medullary thyroid cancer (MTC) therapeutics require both in vitro and in vivo analyses. Human tumour xenografted rodent models, which are considered the 'gold standard' to study and validate the efficacy and toxicity of lead compounds before translation to clinical trials, are very expensive, subject to organismal variability and ethical controversies. The avian chorioallantoic membrane (CAM) assay provides an alternative versatile, cost-effective and ethically less objectionable short-term, in vivo model for reliable screening of drugs. In this work, we grafted two MTC cell lines and patient-derived MTC tumour samples onto the avian CAM and characterised the resulted tumours histologically and immunohistochemically. Our findings provide the evidence that the CAM assay is a suitable model for studying the pathophysiology of MTC and can even be used as in vivo system for drug testing.