• Radiation Oncology Journal
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• v.32 no.3
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• pp.103-115
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• 2014

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

• Radiation Oncology Journal
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• v.36 no.3
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• pp.172-181
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• 2018

Successful anticancer strategies require a differential response between tumor and normal tissue (i.e., a therapeutic ratio). In fact, improving the effectiveness of a cancer therapeutic is of no clinical value in the absence of a significant increase in the differential response between tumor and normal tissue. Although radiation dose escalation with the use of intensity modulated radiation therapy has permitted the maximum tolerable dose for most locally advanced cancers, improvements in tumor control without damaging normal adjacent tissues are needed. As a means of increasing the therapeutic ratio, several new approaches are under development. Drugs targeting signal transduction pathways in cancer progression and more recently, immunotherapeutics targeting specific immune cell subsets have entered the clinic with promising early results. Radiobiological research is underway to address pressing questions as to the dose per fraction, irradiated tumor volume and time sequence of the drug administration. To exploit these exciting novel strategies, a better understanding is needed of the cellular and molecular pathways responsible for both cancer and normal tissue and organ response, including the role of radiation-induced accelerated senescence. This review will highlight the current understanding of promising biologically targeted therapies to enhance the radiation therapeutic ratio.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.317-328
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• 2021

This study aims to determine the factors that affect dividends initiation by initial public offering firms in Malaysia. The ownership structure is examined from a corporate governance theoretical perspective in order to evaluate the impacts of managerial, institutional, and family ownership on the dividend's initiation decision of IPO firms. This study employs a quantitative pooled cross-section of 372 Malaysian IPO companies active during the period of 2002-2013. The number of firms that went public each year varies, thus the pooled cross-section data takes place in this case rather than the panel data. The logistic model was employed to test the proposed hypotheses. The results revealed that the presence of institutional investors in the ownership structure make it more likely for IPO firms to initiate dividends. On the contrary, the presence of a family ownership structure in IPO companies as the controlling shareholder makes these companies less probable to initiate dividends. Managerial ownership was found to have no effect on the decision of initiating dividends by IPO firms. The findings of this study suggest that the existence of institutional and family ownerships are agency cost mitigators, as these ownership types could prompt IPOs firms to initiate dividends to overcome the agency conflicts.

• Information Systems Review
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• v.9 no.2
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• pp.41-66
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• 2007

The e-marketplace is a virtual marketplace where buyers and sellers meet in order to conduct transactions through the intermediation of market-makers. For the success of an e-marketplace, it is crucial for the market-maker to induce both buyers and sellers to make active transactions in it. However, their participation is frequently deterred by potential risk factors caused mainly by the inherent, structural complexity of the e-marketplace. Therefore, it is a critical challenge for the market-maker to identify and manage the transactional risk perceived by both the buyers and sellers. In this paper, we investigate the sources of buyers' and sellers' perceived risks and their mitigating factors in the e-marketplace. Specifically, we derive an analysis framework based on the economic theory of agency relationship. The framework includes four sources of the risks(perceived information asymmetry, fears of seller opportunism, fears of buyer opportunism, and concerns about market-maker's role incompleteness) and five mitigators of the risks(website informativeness, trust in market-maker, trust in seller, product diagnosticity, and social presence). Then, we empirically verify the framework through a case study on four successful e-marketplaces, and provide implications and strategies for the market-maker to effectively manage the transactional risks.