T1ρ-based fibril-reinforced poroviscoelastic constitutive relation of human articular cartilage using inverse finite element technology

BackgroundMapping of T1ρ relaxation time is a quantitative magnetic resonance (MR) method and is frequently used for analyzing microstructural and compositional changes in cartilage tissues. However, there is still a lack of study investigating the link between T1ρ relaxation time and a feasible constitutive relation of cartilage which can be used to model complicated mechanical behaviors of cartilage accurately and properly.MethodsThree-dimensional finite element (FE) models of ten in vitro human tibial cartilage samples were reconstructed such that each element was assigned by material-level parameters, which were determined by a corresponding T1ρ value from MR maps. A T1ρ-based fibril-reinforced poroviscoelastic (FRPE) constitutive relation for human cartilage was developed through an inverse FE optimization technique between the experimental and simulated indentations.ResultsA two-parameter exponential relationship was obtained between the T1ρ and the volume fraction of the hydrated solid matrix in the T1ρ-based FRPE constitutive relation. Compared with the common FRPE constitutive relation (i.e., without T1ρ), the T1ρ-based FRPE constitutive relation indicated similar indentation depth results but revealed some different local changes of the stress distribution in cartilages.ConclusionsOur results suggested that the T1ρ-based FRPE constitutive relation may improve the detection of changes in the heterogeneous, anisotropic, and nonlinear mechanical properties of human cartilage tissues associated with joint pathologies such as osteoarthritis (OA). Incorporating T1ρ relaxation time will provide a more precise assessment of human cartilage based on the individual in vivo MR quantification

The CTLA-4 and PD-1/PD-L1 inhibitory pathways independently regulate host resistance to Plasmodium-induced acute immune pathology.

The balance between pro-inflammatory and regulatory immune responses in determining optimal T cell activation is vital for the successful resolution of microbial infections. This balance is maintained in part by the negative regulators of T cell activation, CTLA-4 and PD-1/PD-L, which dampen effector responses during chronic infections. However, their role in acute infections, such as malaria, remains less clear. In this study, we determined the contribution of CTLA-4 and PD-1/PD-L to the regulation of T cell responses during Plasmodium berghei ANKA (PbA)-induced experimental cerebral malaria (ECM) in susceptible (C57BL/6) and resistant (BALB/c) mice. We found that the expression of CTLA-4 and PD-1 on T cells correlates with the extent of pro-inflammatory responses induced during PbA infection, being higher in C57BL/6 than in BALB/c mice. Thus, ECM develops despite high levels of expression of these inhibitory receptors. However, antibody-mediated blockade of either the CTLA-4 or PD-1/PD-L1, but not the PD-1/PD-L2, pathways during PbA-infection in ECM-resistant BALB/c mice resulted in higher levels of T cell activation, enhanced IFN-γ production, increased intravascular arrest of both parasitised erythrocytes and CD8(+) T cells to the brain, and augmented incidence of ECM. Thus, in ECM-resistant BALB/c mice, CTLA-4 and PD-1/PD-L1 represent essential, independent and non-redundant pathways for maintaining T cell homeostasis during a virulent malaria infection. Moreover, neutralisation of IFN-γ or depletion of CD8(+) T cells during PbA infection was shown to reverse the pathologic effects of regulatory pathway blockade, highlighting that the aetiology of ECM in the BALB/c mice is similar to that in C57BL/6 mice. In summary, our results underscore the differential and complex regulation that governs immune responses to malaria parasites

Sustainability and Corporate Social Responsibility in the Perspective of Social Economy Entities: A Bibliometric Study

We start from the conceptual interconnection between Sustainability and Corporate Social Responsibility, which, although continuously subject to controversy, both within the scope of its definition and in its performance, advocate, as the ultimate goal, human development and of the society in general, promoting the interests of the Communities on a permanent, long-term basis and without compromising the options of the future generations. In this context, we cannot fail to draw a parallel with the entities that constitute the Social Economy Sector. The activities they carry out are of economic and social nature and must be pursued in the general interest of their members, users and beneficiaries, thus in the general interest of the Community. These institutions also reveal concerns about the sustainability in all the dimensions involved (economic, social and environmental), in which the organizational performance is particularly important, as it becomes imperative to guarantee their continuity, fostering and promoting their social action. We will, therefore, start by framing what is meant by Sustainability, Corporate Social Responsibility and Social Economy, with a particular focus on the current requirements of stakeholders regarding the socially responsible behaviour of the institutions as these, in turn, will entail the adoption of more comprehensive management tools, also more efficient and transparent concerning all dimensions (economic, financial and social). It is within this framework that a project called “TFA—TheoFrameAccountability—Theoretical framework for the promotion of accountability in the social economy sector: The IPSS case” emerges, being promoted by the University of Aveiro, with the participation of National Confederation of Solidarity Institutions (CNIS—acronym in Portuguese), and the Polytechnic Institutes of Coimbra and Porto. This project aims to promote the accountability of the social economy sector (economic, financial and social aspects), in the Private Social Solidarity Institutions (IPSS—acronym in Portuguese), assisting them not only in fulfilling their legal obligations, but also facilitating the reporting of results of activities carried out in a more effective manner and promoting transfer of knowledge (for the IPSS and also for the academic community), thus contributing to the development and sustainability of these institutions. Thus, we develop an exploratory and descriptive analysis, of a quantitative-qualitative nature, in which the procedures of data collection determine the result of the search strategy by the defined descriptors. For this purpose, the analysis will focus on the following variables: number of articles published per year; methodologies used; theories of support; identification by sector/area of activity; countries of origin; more representative institutions; authors who publish more and journals with the largest number of publications. The main results indicate a growing concern about sustainability and a growing publication in this area. This paper presents a bibliometric study to evaluate the main trends of current research on sustainability and on corporate social responsibility, thus contributing to the construction of the theoretical basis underlying the “TFA—TheoFrameAccountability” project.info:eu-repo/semantics/publishedVersio