Compact Polyelectrolyte Complexes: “Saloplastic” Candidates for Biomaterials

Precipitates of polyelectrolyte complexes were transformed into rugged shapes suitable for bioimplants by ultracentrifugation in the presence of high salt concentration. Salt ions dope the complex, creating a softer material with viscous fluid-like properties. Complexes that were compacted under the centrifugal field (CoPECs) were made from poly(diallyldimethyl ammonium), PDADMA, as polycation, and poly(styrene sulfonate), PSS, or poly(methacrylic acid), PMAA, as polyanion. Dynamic mechanical testing revealed a rubbery plateau at lower frequencies for PSS/PDADMA with moduli that decreased with increasing salt concentration, as internal ion pair cross-links were broken. CoPECs had significantly lower modulii compared to similar polyelectrolyte complexes prepared by the “multilayering ” method. The difference in mechanical properties was ascribed to higher water content (located in micropores) for the former and, more importantly, to their nonstoichiometric polymer composition. The modulus of PMAA/PDADMA CoPECs, under physiological conditions, demonstrated dynamic mechanical properties that were close to those of the nucleus pulposus in an intervertebral disk

Biomechanical evaluation of predictive parameters of progression in adolescent isthmic spondylolisthesis: a computer modeling and simulation study

<p>Abstract</p> <p>Background</p> <p>Pelvic incidence, sacral slope and slip percentage have been shown to be important predicting factors for assessing the risk of progression of low- and high-grade spondylolisthesis. Biomechanical factors, which affect the stress distribution and the mechanisms involved in the vertebral slippage, may also influence the risk of progression, but they are still not well known. The objective was to biomechanically evaluate how geometric sacral parameters influence shear and normal stress at the lumbosacral junction in spondylolisthesis.</p> <p>Methods</p> <p>A finite element model of a low-grade L5-S1 spondylolisthesis was constructed, including the morphology of the spine, pelvis and rib cage based on measurements from biplanar radiographs of a patient. Variations provided on this model aimed to study the effects on low grade spondylolisthesis as well as reproduce high grade spondylolisthesis. Normal and shear stresses at the lumbosacral junction were analyzed under various pelvic incidences, sacral slopes and slip percentages. Their influence on progression risk was statistically analyzed using a one-way analysis of variance.</p> <p>Results</p> <p>Stresses were mainly concentrated on the growth plate of S1, on the intervertebral disc of L5-S1, and ahead the sacral dome for low grade spondylolisthesis. For high grade spondylolisthesis, more important compression and shear stresses were seen in the anterior part of the growth plate and disc as compared to the lateral and posterior areas. Stress magnitudes over this area increased with slip percentage, sacral slope and pelvic incidence. Strong correlations were found between pelvic incidence and the resulting compression and shear stresses in the growth plate and intervertebral disc at the L5-S1 junction.</p> <p>Conclusions</p> <p>Progression of the slippage is mostly affected by a movement and an increase of stresses at the lumbosacral junction in accordance with spino-pelvic parameters. The statistical results provide evidence that pelvic incidence is a predictive parameter to determine progression in isthmic spondylolisthesis.</p

Current strategies for treatment of intervertebral disc degeneration: substitution and regeneration possibilities

Background: Intervertebral disc degeneration has an annual worldwide socioeconomic impact masked as low back pain of over 70 billion euros. This disease has a high prevalence over the working age class, which raises the socioeconomic impact over the years. Acute physical trauma or prolonged intervertebral disc mistreatment triggers a biochemical negative tendency of catabolic-anabolic balance that progress to a chronic degeneration disease. Current biomedical treatments are not only ineffective in the long-run, but can also cause degeneration to spread to adjacent intervertebral discs. Regenerative strategies are desperately needed in the clinics, such as: minimal invasive nucleus pulposus or annulus fibrosus treatments, total disc replacement, and cartilaginous endplates decalcification. Main Body: Herein, it is reviewed the state-of-the-art of intervertebral disc regeneration strategies from the perspective of cells, scaffolds, or constructs, including both popular and unique tissue engineering approaches. The premises for cell type and origin selection or even absence of cells is being explored. Choice of several raw materials and scaffold fabrication methods are evaluated. Extensive studies have been developed for fully regeneration of the annulus fibrosus and nucleus pulposus, together or separately, with a long set of different rationales already reported. Recent works show promising biomaterials and processing methods applied to intervertebral disc substitutive or regenerative strategies. Facing the abundance of studies presented in the literature aiming intervertebral disc regeneration it is interesting to observe how cartilaginous endplates have been extensively neglected, being this a major source of nutrients and water supply for the whole disc. Conclusion: Severalinnovative avenues for tackling intervertebral disc degeneration are being reported â from acellular to cellular approaches, but the cartilaginous endplates regeneration strategies remain unaddressed. Interestingly, patient-specific approaches show great promise in respecting patient anatomy and thus allow quicker translation to the clinics in the near future.The authors would like to acknowledge the support provided by the Portuguese Foundation for Science and Technology (FCT) through the project EPIDisc (UTAP-EXPL/BBBECT/0050/2014), funded in the Framework of the “International Collaboratory for Emerging Technologies, CoLab”, UT Austin|Portugal Program. The FCT distinctions attributed to J. Miguel Oliveira (IF/00423/2012 and IF/01285/ 2015) and J. Silva-Correia (IF/00115/2015) under the Investigator FCT program are also greatly acknowledged.info:eu-repo/semantics/publishedVersio

Accounting disclosures, accounting quality and conditional and unconditional conservatism

This study investigates the motives of UK listed companies when reporting high and low quality accounting disclosures. It also examines the relation between the quality of published financial statements and earnings management practises, for example, low quality accounting disclosures might be linked to earnings management. The paper further studies the relation between financial reporting quality and the timely disclosure of losses and difficult-to-verify accounting items, i.e. conservatism. The focus here is on conditional and unconditional conservatism, their association and the variables that influence the asymmetric disclosure of losses. The findings indicate that firms that display high quality accounting disclosures generally exhibit higher size, profitability and liquidity measures. Firms that experience a change in management or are audited by a Big-4 auditor also tend to report high quality disclosures. High quality disclosers tend to display higher capital needs and to engage less in earnings management. The study shows that they display greater conditional conservatism and less unconditional conservatism. The findings demonstrate that the conditional form of conservatism is negatively related to unconditional conservatism, as the former tends to enhance contracting efficiency, while the latter might facilitate managerial opportunism. The study provides evidence of asymmetric disclosure of losses for firms with high leverage. The same holds for high quality disclosers that display bad news. In contrast, firms that are in a growth phase are found to provide less conservative and less difficult-to-verify accounting information in order to influence their growth prospects. (C) 2011 Elsevier Inc. All rights reserved

Voluntary IFRS disclosures: Evidence from the transition from UK GAAP to IFRSs

Purpose: The purpose of this study is to investigate how the provision of voluntary International Financial Reporting Standard (IFRS) disclosures in the pre-adoption period has affected the IFRS transition process of UK listed firms. The study also seeks to identify the motivation of firms with financing needs to provide voluntary IFRS disclosures and determines whether the provision of voluntary IFRS disclosures in the pre-adoption period leads to more value relevant numbers. Design/methodology/approach: The study utilises logistic and linear regressions to test the hypothetical relations set up in the study. The categorisation of firms into voluntary and non-voluntary IFRS disclosers is based on the (non-mandatory) provision of material IFRS information prior to adoption about the upcoming adoption of IFRSs in 2005. Company categorization is particularly based on the construction of an index similar to the disclosure index formulated by the Center for International Financial Analysis and Research. Findings: With regard to IFRS transition, firms that provided voluntary IFRS disclosures prior to adoption display a greater positive change in equity and earnings. Non-voluntary IFRS disclosers exhibit a greater positive change in leverage and a decrease in liquidity. Voluntary IFRS disclosers exhibit higher equity and debt financing needs and tend to be audited by a big auditor and be cross-listed. Research limitations/implications: The study implies that the need to obtain financing on better terms would motivate managers to provide voluntary (IFRS) disclosures to show that they are familiar with the upcoming regulatory change and ready to implement it when it becomes effective. The provision of voluntary IFRS disclosures leads to more value relevant accounting measures, suggesting that less information asymmetry would lead to the disclosure of informative and higher quality accounting information assisting investors in making informed judgements. Originality/value: Knowing about different firms' transition experience would assist accounting standard setters in issuing explanatory IFRS guidance in order to lead to an efficient transition to IFRSs for countries that intend to adopt IFRSs or perform an accounting change. The examination of IFRS transition for firms that have experienced the change is important and would provide insight to firms considering this option. The findings further assist accounting academics and students, accountants and investors in their effort to study the motivation for providing voluntary disclosures as well as the magnitude and materiality of IFRS transition on companies' financial accounts. © Emerald Group Publishing Limited

Audit quality in common-law and code-law emerging markets: Evidence on earnings conservatism, agency costs and cost of equity

This study focuses on firms that are audited by a big auditor and examines the differentiation in the earnings management potential and the level of conservatism. It also investigates whether being audited by a big auditor would lead to lower agency costs and lower cost of equity. The study focuses on emerging common-law South Africa and code-law Brazil, and seeks to identify whether there are material differences given their dissimilar institutional characteristics. The study reports that even though firms may be audited by high quality auditors, their institutional differences influence significantly firms' earnings conservatism, agency costs and cost of equity. Client firms of big auditors in both common-law South Africa and code-law Brazil exhibit lower discretionary accruals. The study has found evidence of more conservative earnings for South Africa but insufficient levels for Brazil. For common-law South Africa, the presence of effective corporate governance mechanisms reduces agency costs. For code-law Brazil, the corporate governance mechanisms generally display an insignificant impact on reducing agency costs. For common-law South Africa, firm-level performance, growth and market determinants tend to lead to a lower cost of equity. For code-law Brazil, it is found that significant discretionary accruals, market beta and analyst forecast dispersion would result in higher uncertainty and would consequently raise the cost of equity. (C) 2012 Elsevier B.V. All rights reserved

Corporate philanthropy in the US stock market: Evidence on corporate governance, value relevance and earnings manipulation

This study examines the financial attributes of corporate philanthropy derived from the agency motives for corporate giving. Further, this study assesses the value relevance of corporate giving and investigates the impact of giving on investor perceptions and future profitability and growth. Also, it investigates the association between charitable spending and earnings manipulation. The findings indicate that the adoption of structured philanthropic initiatives and the use of in-kind contributions encourage corporate giving. Monitoring exercised by leverage and corporate governance affects corporate giving downwards. Firms that experience a management change are subject to more public scrutiny and tend to give more. Corporate giving is value relevant and is negatively related to analyst forecast error and positively to analyst coverage. Charitable firms tend to engage less in earnings manipulation. However, firms with significant growth options may direct slack resources to discretionary charitable causes. In-kind contributions are negatively related to managerial opportunism. (C) 2015 Elsevier Inc. All rights reserved

Environmental disclosure quality: Evidence on environmental performance, corporate governance and value relevance

This study focuses on common-law Malaysia, which is classified as an advanced emerging market. It assesses the association between environmental disclosure and environmental performance and examines the financial attributes of companies with different environmental disclosure scores. It investigates the relation between environmental disclosure quality and corporate governance, and also examines the extent to which effective environmental disclosures are value relevant and how they influence investor perceptions. The findings of the study show that environmental disclosure is positively linked to environmental performance. Company attributes, such as large size, the need for capital, profitability and capital spending, are positively associated with environmental disclosure quality. High quality environmental disclosers display effective corporate governance and would tend to face less difficulties in accessing capital markets. They generally are audited by a big 4 auditor or cross-listed on foreign stock exchanges and display significant levels of managerial and institutional ownership. High quality environmental disclosures are value relevant and improve investor perceptions. High quality disclosers overall belong to beverages, chemicals, food producers, forestry and paper, and industrial metals and mining. © 2012 Elsevier B.V