The effects of irradiation on the biological and biomechanical properties of an acellular porcine superflexor tendon graft for cruciate ligament repair

Acellular xenogeneic tissues have the potential to provide ‘off‐the‐shelf’ grafts for anterior cruciate ligament (ACL) repair. To ensure that such grafts are sterile following packaging, it is desirable to use terminal sterilization methods. Here, the effects of gamma and electron beam irradiation on the biological and biomechanical properties of a previously developed acellular porcine superflexor tendon (pSFT) were investigated. Irradiation following treatment with peracetic acid was compared to peracetic acid treatment alone and the stability of grafts following long‐term storage assessed. Irradiation did not affect total collagen content or biocompatibility (determined using a contact cytotoxicity assay) of the grafts, but slightly increased the amount of denatured collagen in and decreased the thermal denaturation temperature of the tissue in a dose dependant fashion. Biomechanical properties of the grafts were altered by irradiation (reduced ultimate tensile strength and Young's modulus, increased failure strain), but remained superior to reported properties of the native human ACL. Long term storage at 4°C had no negative effects on the grafts. Of all the conditions tested, a dose of minimum 25 kGy of gamma irradiation had least effect on the grafts, suggesting that this dose produces a biocompatible pSFT graft with adequate mechanical properties for ACL repair

The Mersey Estuary : sediment geochemistry

This report describes a study of the geochemistry of the Mersey estuary carried out between April 2000 and December 2002. The study was the first in a new programme of surveys of the geochemistry of major British estuaries aimed at enhancing our knowledge and understanding of the distribution of contaminants in estuarine sediments. The report first summarises the physical setting, historical development, geology, hydrography and bathymetry of the Mersey estuary and its catchment. Details of the sampling and analytical programmes are then given followed by a discussion of the sedimentology and geochemistry. The chemistry of the water column and suspended particulate matter have not been studied, the chief concern being with the geochemistry of the surface and near-surface sediments of the Mersey estuary and an examination of their likely sources and present state of contamination

Decellularization and Characterization of Porcine Superflexor Tendon: A Potential Anterior Cruciate Ligament Replacement

The porcine superflexor tendon (SFT) was identified as having appropriate structure and properties for development of a decellularised device for use in ACL reconstruction. SFTs were decellularised using a combination of freeze thaw and washes in hypotonic buffer and 0.1% (w/v) SDS in hypotonic buffer plus proteinase inhibitors followed by nuclease treatment and sterilisation using peracetic acid. The decellularised biological scaffold was devoid of cells and cell remnants and contained only 13 ng.mg-1 (dry weight) residual total DNA. Immunohistochemistry showed retention of collagens type I and III and tenascin-C. Quantitative analysis of sulphated sugar and hydroxyproline content revealed a loss of glycosaminoglycans compared to native tissue but no loss of collagen. The decellularised SFT was biocompatible in vitro and in vivo following implantation in a mouse subcutaneous model for 12 weeks. Uniaxial tensile testing to failure indicated that the gross material properties of decellularised SFT were not significantly different to native tissue. Decellularised SFTs had an ultimate tensile strength of 61.8 ± 10.3 MPa (± 95 % confidence limits), a failure strain of 0.29 ± 0.04 and a Young’s modulus of the collagen phase of 294.1 ± 61.9 MPa. Analysis of the presence of the alpha-Gal (galactose-α-1,3-galactose) epitope by immunohistochemistry, lectin binding and antibody absorption assay indicated that the epitope was reduced but still present post decellularisation. This is discussed in light of the potential role of non-cellular alpha-Gal in the acceleration of wound healing and tissue regeneration in the presence of antibodies to alpha-Gal

Developing sexual competence? Exploring strategies for the provision of effective sexualities and relationships education

School-based sexualities and relationships education (SRE) offers one of the most promising means of improving young people's sexual health through developing 'sexual competence'. In the absence of evidence on whether the term holds the same meanings for young people and adults (e.g. teachers, researchers, policy-makers), the paper explores 'adult' notions of sexual competence as construed in research data and alluded to in UK Government guidance on SRE, then draws on empirical research with young people on factors that affect the contexts, motivations and outcomes of sexual encounters, and therefore have implications for sexual competence. These data from young people also challenge more traditional approaches to sexualities education in highlighting disjunctions between the content of school-based input and their reported sexual experience. The paper concludes by considering the implications of these insights for developing a shared notion of what SRE is trying to achieve and suggestions for recognition in the content and approaches to SRE.</p

'Selling it as a holistic health provision and not just about condoms ?' Sexual health services in school settings: current models and their relationship with sex and relationships education policy and provision

In this article we discuss the findings from a recent study of UK policy and practice in relation to sexual health services for young people, based in - or closely linked with - schools. This study formed part of a larger project, completed in 2009, which also included a systematic review of international research. The findings discussed in this paper are based on analyses of interviews with 51 service managers and questionnaire returns from 205 school nurses. Four themes are discussed. First, we found three main service permutations, in a context of very diverse and uneven implementation. Second, we identified factors within the school context that shaped and often constrained service provision; some of these also have implications for sex and relationships education (SRE). Third, we found contrasting approaches to the relationship between SRE input and sexual health provision. Fourth, we identified some specific barriers that need to be addressed in order to develop 'young people friendly' services in the school context. The relative autonomy available to school head teachers and governors can represent an obstacle to service provision - and inter-professional collaboration - in a climate where, in many schools, there is still considerable ambivalence about discussing 'sex' openly. In conclusion, we identify areas worthy of further research and development, in order to address some obstacles to sexual health service and SRE provision in schools

How to correct small quantum errors

The theory of quantum error correction is a cornerstone of quantum information processing. It shows that quantum data can be protected against decoherence effects, which otherwise would render many of the new quantum applications practically impossible. In this paper we give a self contained introduction to this theory and to the closely related concept of quantum channel capacities. We show, in particular, that it is possible (using appropriate error correcting schemes) to send a non-vanishing amount of quantum data undisturbed (in a certain asymptotic sense) through a noisy quantum channel T, provided the errors produced by T are small enough.Comment: LaTeX2e, 23 pages, 6 figures (3 eps, 3 pstricks

Decellularization of human donor aortic and pulmonary valved conduits using low concentration sodium dodecyl sulfate

The clinical use of decellularised cardiac valve allografts is increasing. Long term data will be required to determine whether they outperform conventional cryopreserved allografts. Valves decellularised using different processes may show varied long-term outcomes. It is therefore important to understand the effects of specific decellularisation technologies on the characteristics of donor heart valves. Human cryopreserved aortic and pulmonary valved conduits were decellularised using hypotonic buffer, 0.1% (w/v) SDS and nuclease digestion. The decellularised tissues were compared to cellular cryopreserved valve tissues using histology, immunohistochemistry, quantitation of total DNA, collagen and glycosaminoglycan content, in vitro cytotoxicity assays, uniaxial tensile testing and subcutaneous implantation in mice. The decellularised tissues showed no histological evidence of cells or cell remnants and over 97% DNA removal in all regions (arterial wall, muscle, leaflet and junction). The decellularised tissues retained collagen IV and von Willebrand factor staining with some loss of fibronectin, laminin and chondroitin sulphate staining. There was an absence of MHC Class I staining in decellularised pulmonary valve tissues, with only residual staining in isolated areas of decellularised aortic valve tissues. The collagen content of the tissues was not decreased following decellularisation however the glycosaminoglycan content was reduced. Only moderate changes in the maximum load to failure of the tissues were recorded post-decellularisation. The decellularised tissues were non-cytotoxic in vitro, and were biocompatible in vivo in a mouse subcutaneous implant model. The decellularisation process will now be translated into a GMP compatible process for donor cryopreserved valves with a view to future clinical use

Mitigating Gender Bias in Machine Learning Data Sets

Artificial Intelligence has the capacity to amplify and perpetuate societal biases and presents profound ethical implications for society. Gender bias has been identified in the context of employment advertising and recruitment tools, due to their reliance on underlying language processing and recommendation algorithms. Attempts to address such issues have involved testing learned associations, integrating concepts of fairness to machine learning and performing more rigorous analysis of training data. Mitigating bias when algorithms are trained on textual data is particularly challenging given the complex way gender ideology is embedded in language. This paper proposes a framework for the identification of gender bias in training data for machine learning.The work draws upon gender theory and sociolinguistics to systematically indicate levels of bias in textual training data and associated neural word embedding models, thus highlighting pathways for both removing bias from training data and critically assessing its impact.Comment: 10 pages, 5 figures, 5 Tables, Presented as Bias2020 workshop (as part of the ECIR Conference) - http://bias.disim.univaq.i

Questioning policy, youth participation and lifestyle sports

Young people have been identified as a key target group for whom participation in sport and physical activity could have important benefits to health and wellbeing and consequently have been the focus of several government policies to increase participation in the UK. Lifestyle sports represent one such strategy for encouraging and sustaining new engagements in sport and physical activity in youth groups, however, there is at present a lack of understanding of the use of these activities within policy contexts. This paper presents findings from a government initiative which sought to increase participation in sport for young people through provision of facilities for mountain biking in a forest in south-east England. Findings from qualitative research with 40 young people who participated in mountain biking at the case study location highlight the importance of non-traditional sports as a means to experience the natural environments through forms of consumption which are healthy, active and appeal to their identities. In addition, however, the paper raises questions over the accessibility of schemes for some individuals and social groups, and the ability to incorporate sports which are inherently participant-led into state-managed schemes. Lifestyle sports such as mountain biking involve distinct forms of participation which present a challenge for policy-makers who seek to create and maintain sustainable communities of youth participants