Ellagic acid inhibits RANKL-induced osteoclast differentiation by suppressing the p38 MAP kinase pathway

Bone undergoes continuous remodeling by a coupled action between osteoblasts and osteoclasts. During osteoporosis, osteoclast activity is often elevated leading to increased bone destruction. Hence, osteoclasts are deemed as potential therapeutic targets to alleviate bone loss. Ellagic acid (EA) is a polyphenol reported to possess anticancer, antioxidant and anti-inflammatory properties. However, its effects on osteoclast formation and function have not yet been examined. Here, we explored the effects of EA on RANKL-induced osteoclast differentiation in RAW264.7 murine macrophages (in vitro) and human CD14+monocytes (ex vivo). EA dose-dependently attenuated RANKL-induced TRAP+ osteoclast formation in osteoclast progenitors with maximal inhibition seen at 1 µM concentration without cytotoxicity. Moreover, owing to perturbed osteoclastogenesis, EA disrupted actin ring formation and bone resorptive function of osteoclasts. Analysis of the underlying molecular mechanisms revealed that EA suppressed the phosphorylation and activation of the p38 MAP kinase pathway which subsequently impaired the RANKL-induced differentiation of osteoclast progenitors. Taken together, these novel results indicate that EA alleviates osteoclastogenesis by suppressing the p38 signaling pathway downstream of RANKL and exerts inhibitory effects on bone resorption and actin ring formation.RESCOM, University of Pretoria; the University of Pretoria’s Strategic Institutional Research Theme in Food, Nutrition and Well-being; and in part by the University of Pretoria Vice Chancellor’s Postdoctoral Research Fellowship.http://link.springer.com/journal/122722018-01-31hb2017Human NutritionPhysiolog

Ferulic acid impairs osteoclast fusion and exacerbates survival of mature osteoclasts

Elevated bone loss induced by osteoclasts is a critical and most commonly observed pathological complication during osteolytic diseases such as osteoporosis. Hence, attenuation of osteoclast formation or function is a classical therapeutic approach to regulate bone loss. In this study, we found that ferulic acid (FA), a natural compound potently inhibited osteoclast formation in human CD14+ peripheral blood monocytes (PBMCs) ex vivo with an IC50 of 39 μM.Moreover, due to impaired differentiation of osteoclast progenitors, actin ring formation and bone resorption activity were also perturbed. Investigation of underlying molecular mechanisms revealed that FA inhibited the RANKL-induced expression of dendritic cell-specific transmembrane protein (DC-STAMP), a critical regulator of osteoclast fusion. In addition, expression of matrix metalloproteinase-9 (MMP-9) and cathepsin K (CTSK), the key osteoclast specific lysosomal proteases involved in bone matrix resorption were severely aggravated by FA. A significant reduction in mature osteoclast numbers was detected in the presence of FA accompanied by increased caspase-3 activity and DNA-fragmentation, a characteristic hallmark of apoptosis. Collectively, these results suggested that FA inhibited osteoclast fusion by suppressing the expression of DC-STAMP and induced apoptosis in mature osteoclasts by the caspase-3 pathway.Grants from RESCOM, University of Pretoria; the University of Pretoria’s Strategic Institutional Research Theme in Food, Nutrition and Well-being; and in part by the University of Pretoria Vice Chancellor’s Postdoctoral Research Fellowship.http://link.springer.com/journal/106162017-10-31hb2016Human NutritionPhysiolog

Distance students’ readiness for an online information literacy programme : Unisa School of Accountancy as a case study

This dissertation reports on a study of the self-reported readiness of undergraduate first-year students at a very large distance teaching institution, the University of South Africa (Unisa). The Unisa library does not offer an online information literacy programme for distance students and has not conducted surveys on students’ needs and their readiness for using online information resources and an online learning management system. The main research question thus was: What are the information seeking behaviour and the readiness of Unisa distance students in using and accessing the library online resources? Sub-questions were: • What has been reported on information literacy and information literacy programmes for distance students, with special reference to online programmes? • What has been reported on virtual learning environments with specific reference to distance education? • What are the students’ self-rated perceptions of their information literacy skills? • What are the students’ information seeking behaviour and preferences in using online information resources? • What are the students’ self-rated perceptions in using an online learning management system in a virtual learning environment? The Unisa School of Accountancy served as case study. All students enrolled for first- year modules in the School of Accountancy (including the Departments of Auditing, Financial Accounting, Management Accounting and Taxation) were invited to participate in the survey. Data collection occurred in July and August 2015 by means of a self-administered, semi-structured online questionnaire survey. In total 587 students responded, resulting in 525 usefully completed questionnaires. Most of the students were geographically remote from the institution and the library and its branches. The study collected mostly descriptive quantitative data, with limited qualitative data. The quantitative data were analysed by means of a statistical package (SAS JMP version 12), and the qualitative data by means of thematic analysis. The questionnaire covered self-reported information seeking behaviour when using the library’s online resources, whether students had received training on information literacy skills, and if these skills were effective enough to assist them to locate and access the library’s diverse online information resources relevant to their studies. It also collected data on their readiness to use an online learning management system. The limitations of self-reporting are acknowledged; in this case it was considered appropriate to determine lack of skills. Although the findings cannot be generalised to all Unisa or all distance students, they can inform recommendations on the need for an online information literacy skills programme for distance students and methods to conduct similar studies of students’ readiness to use such a programme. Respondents lacked information literacy skills that could enable them to access or use the online library resources from a distance. They lacked skills in using the virtual learning environment system, experienced problems in accessing the library from a distance, could not use databases to access online full-text articles and were often not aware of the library website and how it could be used. It is recommended that the Unisa library consider developing an online information literacy programme that adheres to international standards and guidelines for information literacy, and that this be informed by the needs expressed by students from diverse disciplines and study years and their self-reported information-seeking behaviour. For distance students a programme must be available through a virtual learning environment and this must be linked to the library’s website and marketing efforts. KEYWORDS • Case study • Distance education • Distance libraries • Distance students • Information literacy skills • Information seeking behaviour • Online information literacy programmes • Online information seeking behaviourDissertation (MIS)-University of Pretoria, 2017.University of South Africa (UNISA)Information ScienceMISUnrestricte