The P2X7 Receptor: A Key Player in Immune-Mediated Bone Loss?

Inflammatory diseases are often multiorganic diseases with manifestations not related directly to the primary affected organ. They are often complicated by a generalized bone loss that subsequently leads to osteoporosis and bone fractures. The exact mechanism for the accompanying bone loss is not understood in full detail, but factors such as glucocorticoid treatment, immobilization, malnutrition, and insufficient intake of vitamin D play a role. However, it has become evident that the inflammatory process itself is involved and the resulting bone loss is termed immune-mediated bone loss. It stems from an increase in bone resorption and the pro-inflammatory cytokines tumor necrosis factor alpha and interleukin 1 beta and has been shown to not only mediate the inflammatory response but also to strongly stimulate bone degradation. The purinergic P2X7 receptor is central in the processing of these two cytokines and in the initiation of the inflammatory response, and it is a key molecule in the regulation of both bone formation and bone resorption. The aim of this review is therefore to provide evidence-based novel hypotheses of the role of ATP-mediated purinergic signalling via the P2X7 receptor in immune-mediated bone loss and -osteoporosis

The Direction of Causality between Insider Ownership and Market Valuation

The causal relationship between insider ownership and market valuation is tested on a database of the largest EU and US companies. Using a Granger causality test insider ownership (measured by the fraction of closely held shares) is found to have a negative effect on market valuation (measured as the simple Tobin's Q ratio). And market valuation is found to have a negative effect on insider ownership. Consistent with an overall non-linear relationship as hypothesised by Morck et al. (1988) and Stultz (1988), the negative effect from insider ownership to performance is found to be significant only for companies with high initial levels of insider ownership, but insignificant for companies with low initial concentration levels. Furthermore, the effect on market valuation turns out to depend on system affiliation: it is only significant in continental Europe where average insider ownership is much higher than in the Anglo-American world (UK and US)

Measuring inefficiency in the Norwegian bus industry using multi-directional efficiency analysis

To measure and analyze efficiency in the transportation industry, this paper introduces and demonstrates the advantages of multi-directional efficiency analysis (MEA) in the case of cost data with limited substitution possibilities. Norwegian bus data that has previously been analyzed using econometric models and data envelopment analysis is reconsidered using MEA. Findings show that using MEA makes it possible to disaggregate inefficiency into different components corresponding to different types of cost generating variables and thereby provides both managers of the bus companies and policy makers with more detailed information on possible improvements in performance. Specific results show that about 10% higher costs for companies operating in coastal areas are related to inefficient utilization of the fuel input. This suggests that part of the improvement potential of companies in coastal areas is caused by topographic factors and are thus beyond management control. Controlling for the costal effects shows that ownership has an effect on fuel utilization. The improvement potential in driver costs were found to be about 4% larger for public than for private companies