An investigation into the mechanical and biological properties of acrylic bone cement containing triphenyl bismuth (TPB) as an alternative radiopacifier

PhDTotal joint replacement is the most successful method of treating end-stage arthritis. It significantly improves the quality of life and the functional capability of patients suffering from arthritis. Currently an estimated 40,000 total joint arthroplasties are performed each year in the United Kingdom, and over 42% of these are performed in patients younger than 65 years. Poly(methylmethacrylate) bone cement is used to fill the space between the bone and the prosthesis in joint replacements and thus forms a mechanical bond between the two surfaces. The cement layer transfers the load from the prosthesis to the bone and increases the load bearing capacity of the implant-cement-bone system. Surgeons require bone cement to be radiopaque on radiographs in order to monitor the position of the implant after a joint replacement surgery. Therefore heavy metal salts such as barium sulphate and zirconium dioxide are added to bone cement to impart such radiopacity. The addition of these radiopacifiers, however, degrades the mechanical properties of the bone cement due to the lack of chemical bonding between the radiopacifier and the polymer matrix. Barium sulphate is known to adversely affect the mechanical strength and fracture toughness of bone cement. Various studies have also shown that barium sulphate and zirconium dioxide may contribute to the pathological bone resorption of aseptic loosening by enhancing macrophage-osteoclast differentiation. In this study an organo-bismuth compound, triphenyl bismuth (TPB) has been investigated as a potential radiopaque alternative to barium sulphate in bone cements. The inclusion of TPB has been shown to improve the mechanical properties of bone cement including fracture toughness. Furthermore, it has also been shown to cause less bone resorption, which is usually associated with aseptic loosening in joint replacement

Biofabrication for osteochondral tissue regeneration: bioink printability requirements

This work was funded by PAMI (ROTEIRO/0328/2013; Nº 022158), a Research Infrastructure of the National Roadmap of Research Infrastructures of Strategic Relevance for 2014–2020, co-funded by the FCT and European Union through the Centro2020.Biofabrication allows the formation of 3D scaffolds through a precise spatial control. This is of foremost importance when aiming to mimic heterogeneous and anisotropic architecture, such as that of the osteochondral tissue. Osteochondral defects are a supreme challenge for tissue engineering due to the compositional and structural complexity of stratified architecture and contrasting biomechanical properties of the cartilage-bone interface. This review highlights the advancements and retreats witnessed by using developed bioinks for tissue regeneration, taking osteochondral tissue as a challenging example. Methods, materials and requirements for bioprinting were discussed, highlighting the pre and post-processing factors that researchers should consider towards the development of a clinical treatment.info:eu-repo/semantics/publishedVersio

Comparison of flanged and unflanged acetabular cup design: An experimental study using ceramic and cadaveric acetabuli

Background and purpose Adequate depth of cement penetration and cement mantle thickness is important for the durability of cemented cups. A flanged cup, as opposed to unflanged, has been suggested to give a more uniform cement mantle and superior cement pressurization, thus improving the depth of cement penetration. This hypothesis was tested experimentally. Materials and methods The same cup design with and without flange (both without cement spacers) was investigated regarding intraacetabular pressure, cement mantle thickness, and depth of cement penetration. With machine control, the cups were inserted into open-pore ceramic acetabular models (10 flanged, 10 unflanged) and into paired cadaver acetabuli (10 flanged, 10 unflanged) with prior pressurization of the cement. Results No differences in intraacetabular pressures during cup insertion were found, but unflanged cups tended to migrate more towards the acetabular pole. Flanged cups resulted in thicker cement mantles because of less bottoming out, whereas no differences in cement penetration into the bone were observed. Interpretation Flanged cups do not generate higher cementation pressure or better cement penetration than unflanged cups. A possible advantage of the flange, however, may be to protect the cup from bottoming out, and there is possibly better closure of the periphery around the cup, sealing off the cement-bone interface

Staff SARS-CoV-2 Seroprevalence and Mental Health as Key Factors in University Response to COVID-19 Pandemic

Copyright © 2021 Lopes, Henriques, Santos-Dias, Nunes-da-Silva, Gonçalves, de Sousa, Abdulghani, Eletério, Braga, Soares, Branco, Canhão and Rodrigues.Background: In response to rapid global spread of the newly emerged coronavirus disease 2019 (COVID-19), universities transitioned to online learning and telework to decrease risks of inter-person contact. To help administrators respond to the COVID-19 pandemic and better understand its impacts, we surveyed SARS-CoV-2 seroprevalence among NOVA University employees and assessed community mental health. Methods: Data were collected from voluntary participants at six NOVA University locations, in the Lisbon metropolitan area, from June 15-30, 2020. All subjects provided written informed consent. Of 1,627 recruited participants (mean age 42.0 ± 12.3 years), 1,624 were tested. Prior to blood collection, participants completed a questionnaire that assessed: COVID-19 symptoms during the previous 14 days, chronic non-communicable diseases, chronic medication, anxiety, and depression symptoms. SARS-CoV-2 serology tests were then performed, and results communicated approximately 4 days after blood draw. Participants with positive serology tests were contacted to assess COVID-19 symptoms since February. Results: Estimated prevalence of SARS-CoV-2 IgG antibodies was 3.1% (n = 50), of which 43.5% reported symptoms in the previous 4 months. The Medical School had the highest seroprevalence (6.2%). Participants reported having at least one chronic disease (63.7%), depression-like symptoms (2.1%), and anxiety symptoms (8.1%). Rates of depression and anxiety symptoms were significantly higher in women, with sleep hours and occasional alcohol consumption negatively associated with depression. Male gender, older age, and sleep hours negatively associated with anxiety symptoms. School of employment and presence of comorbidities positively associated with anxiety. Conclusion: By measuring seroprevalence of SARS-CoV-2 antibodies among NOVA employees and assessing subjects' mental health, we aim to help administrators at European public universities in urban areas, such as Lisbon, Portugal, better understand the needs of their communities. This study resulted in implementation of a stricter contingency plan in the Medical School, while other schools continued to follow Government mitigation guidelines. These findings may also guide the development of tailored strategies to ensure physical and mental health of the academic community during this pandemic crisis. We conclude that, together with COVID-19 contingency plans, psychological support services and facilities to help people effectively face pandemic-associated challenges and minimise anxiety and depression should be implemented.publishersversionpublishe

Chronic arthritis leads to disturbances in the bone collagen network

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Static mechanical properties of acrylic bone cements containing an organobismuth compound as a radiopacifier

The inclusion of triphenyl bismuth (TPB) as an alternative radiopacifier in bone cements with good tensile properties was reported. Using Servohydraulic Testing Machine in accordance with ISO 5833 standard using cylindrical specimens where the ratio of the length to the diameter is 2:1, the compression testing was performed. It was observed that the addition of TPB does not degrade the flexural or compressive strengths of acrylic cements. It was shown that the ultimate compressive strengths of TPB-cements exceeded the minimum value of 70 MPa stated by ISO 5833 fro acrylic cements

Biomaterials for In Situ Tissue Regeneration: A Review

This review focuses on a somewhat unexplored strand of regenerative medicine, that is in situ tissue engineering. In this approach manufactured scaffolds are implanted in the injured region for regeneration within the patient. The scaffold is designed to attract cells to the required volume of regeneration to subsequently proliferate, differentiate, and as a consequence develop tissue within the scaffold which in time will degrade leaving just the regenerated tissue. This review highlights the wealth of information available from studies of ex-situ tissue engineering about the selection of materials for scaffolds. It is clear that there are great opportunities for the use of additive manufacturing to prepare complex personalized scaffolds and we speculate that by building on this knowledge and technology, the development of in situ tissue engineering could rapidly increase. Ex-situ tissue engineering is handicapped by the need to develop the tissue in a bioreactor where the conditions, however optimized, may not be optimum for accelerated growth and maintenance of the cell function. We identify that in both methodologies the prospect of tissue regeneration has created much promise but delivered little outside the scope of laboratory-based experiments. We propose that the design of the scaffolds and the materials selected remain at the heart of developments in this field and there is a clear need for predictive modelling which can be used in the design and optimization of materials and scaffolds

Physical and radiopaque characterisation of acrylic bone cements containing an organobismuth compound as a radiopacifier

The water sorption and desorption characteristics of triphenyl bismuth (TPB)-cements were studied. The radiopacity of TPB was evaluated in order to assess its contrast in comparison to BaSO4-containing cements. It was observed that TPB-cements absorb/ desorp less water than BaSO4 cements (BS) due to the hydrophobic nature of TPB. It was shown that the addition of TPB to acrylic cements results in the formation of homogeneous system as a result of its solubility in MMA

Microwave-Assisted Synthesis, Structural Characterization and Assessment of the Antibacterial Activity of Some New Aminopyridine, Pyrrolidine, Piperidine and Morpholine Acetamides

A series of new acetamide derivatives 22–28 of primary and secondary amines and para-toluene sulphinate sodium salt have been synthesized under microwave irradiation and assessed in vitro for their antibacterial activity against one Gram-positive and two Gram-negative bacterial species such as S. pyogenes, E. coli, and P. mirabilis using the Mueller-Hinton Agar diffusion (well diffusion) method. The synthesized compounds with significant differences in inhibition diameters and MICs were compared with those of amoxicillin, ampicillin, cephalothin, azithromycin and doxycycline. All of the evaluated acetamide derivatives were used with varying inhibition concentrations of 6.25, 12.5, 37.5, 62.5, 87.5, 112.5 and 125 µg/mL. The results show that the most important antibacterial properties were displayed by the synthetic compounds 22 and 24, both of bear a para-chlorophenyl moiety incorporated into the 2-position moiety of acetamide 1. The molecular structures of the new compounds were determined using the FT-IR and 1H-NMR techniques