No abstract

The high degree of bone marrow cell (BMC) plasticity has prompted us to test its restoration possibility in inner ear repair. Our aim was to determine the potential of these cells to transdifferentiate into specialized cochlea cell types after acoustic injury and BMC mobilization. Lethally irradiated mice were transplanted with BMCs from green fluorescent protein (GFP) transgenic mice and subjected to acoustic deafening 3 months later. In a separate experiment, stem cell factor and granulocyte colony-stimulating factor were administered to test the effect of BMC mobilization on bone marrow-derived cell (BMDC) transdifferentiation. All mice showed almost complete chimerism 3 months after bone marrow transplantation. Upon acoustic trauma, robust BMDC migration was observed in the deafened cochlea. GFP+ cell migration was most prominent during the first week after acoustic deafening, and these cells accumulated significantly at the spiral ligament, perilymphatic compartment walls, and limbus regions. Most of the BMDCs expressed CD45 and CD68 and were identified as macrophages. Upregulation of stromal-derived factor 1 (SDF-1) was also observed in the spiral ligament during the first week after acoustic deafening. Cytokine treatment resulted in increased BMC mobilization in the systemic circulation. However, the presence of any stem cell progenitors or the differentiation of BMDCs into any cell types expressing cochlea sensory, supporting, fibrocytic, or neuronal markers were not detected in the deafened cochlea. In conclusion, we have demonstrated the homing capability of BMDCs to the deafened cochlea, and these cells displayed mature hematopoietic properties without spontaneous transdifferentiation to any cochlea cell types after acoustic trauma or bone marrow mobilization.

We adopt a social network perspective of accounting choices and argue that voluntary expensing of stock option grants by firms may be driven by social influence and learning within a network of director interlocks. We find that firms are more likely to expense stock option grants voluntarily when they have inside director interlocks with (1) other firms that do likewise, and (2) institutional investors of firms accused of financial reporting fraud. This study contributes to extant research by highlighting that a social network approach complements a cost-and-benefit approach (or an economic perspective) when examining the accounting practices of firms. Copyright (c) 2008 The Authors Journal compilation (c) 2008 Blackwell Publishing Ltd.

Plain language summary Managers of multinational firms often view the political and legal environment as an important driver of international performance. However, this view is normally directed toward the host country rather than the political and legal environment within the home country. This study focuses on the home country environment and finds that a stable political environment increases the effectiveness of a firm's overseas expansion efforts, even as it reduces overall firm performance. Meanwhile, an effective legal environment at home strengthens the effectiveness of a firm's overseas expansion efforts and overall firm performance. As such, the origin of a firm matters, as it influences a firm's ability to be successful. This has broad implications for managers and policy makers. Technical summary This study proposes that we need to examine jointly the direct and indirect effects of home country political and legal institutions on the performance of geographically diversified firms. We contend that home country political stability and regulatory effectiveness work through different mechanisms in influencing firms' performance directly and indirectly through their geographical diversification strategies. Specifically, we hypothesize that home country political stability directly reduces firm performance, but positively moderates the relationship between geographic diversification and performance. Meanwhile, we hypothesize that home country regulatory effectiveness directly enhances firm performance and positively moderates the relationship between geographic diversification and performance. The findings, based on more than 33,000 firm‐year observations from 33 home countries, support our hypotheses on home country political stability and regulatory effectiveness. Copyright © 2016 Strategic Management Society.