Editorial [Hot topic: Targets of Potential Radioprotective Drugs (Guest Editors: Martin)]

Among the four weapons of mass destruction and disruption (chemical, biological, radiological, and nuclear - CBRN), nuclear and radiological weapons are the most insidious. Serious debates are in progress about the danger- benefit equilibrium of even diagnostic and therapeutic radiological exposures. Although non-ionizing radiations like microwave are also harmful, the deleterious effects of ionizing radiation have been under the intense scrutiny by the scientific community, as well as the subject for deliberations of governments of the comity of nations. In the United States, considerable resources are being allocated by the departments of Defense (DoD), Homeland Security (DHS), and Health and Human Services (DHHS) in deciphering the mechanisms of radiation damage and develop drug(s) that can prevent these effects before, shortly after, and well after irradiation. The existing concepts of time, shielding, and distance are still the best practices of minimizing the deleterious effects of radiation exposure. Nevertheless, the development of a radiation countermeasure drug(s) is an important priority. Hence, the paucity of radiation countermeasures is a serious concern for physicians trying to protect the normal tissues surrounding a tumor during radiotherapy, for first responders who may have to enter a radiation field for rescue and recovery operations in a “dirty bomb” attack by extremists, and for astronauts who may be involved in extended extra-vehicular activities during space explorations. Depending on the dose and dose rate of ionizing radiation exposure, normal tissue radiation injury can vary from short-term lethality to long-term carcinogenesis and fibrosis based on the severity of the radiation-induced multi organ dysfunction syndrome (Rad-MODS). The earliest visible manifestation of radiation in humans is nausea and vomiting. Hematological, gastrointestinal, central nervous system, and cardio-pulmonary sub-syndromes are manifested on exposure to progressively increasing doses of radiation. However, these sub-syndromes are not mutually exclusive and quite often overlap. Several studies are in progress to determine the various targets of radiation damage in these organ systems. These studies described in this volume include non-free radical scavenging mechanisms that modify radiation damage (Kim and McBride), nitric oxidetetrahydrobiopterin based novel molecular mechanisms (Berbee et al.), cellular mechanisms of injury and repair of bone marrow (Kulkarni et al.), organ specific normal tissue radiation injury of lungs (Williams et al., Monceau et al.), kidney (Cohen et al.), brain (Robbins et al.), and heart (Boerma and Hauer-Jensen). This special thematic edition of “Targets for Potential Radioprotective Drugs” is an attempt to collate the state of the art knowledge in this area written by established scientists in their own fields of expertise. In addition to collating the current state of the knowledge, the authors have succeeded in intertwining the findings of their own research with those of others. The readers of this issue will acquire insight into mechanisms of radiation damage to various organ systems to be applied to the development of novel mechanisms-based radiation countermeasure drug(s).