James J. Conklin

Research issues for radiation protection for man during prolonged spaceflight

Publisher Summary This chapter describes radiation protection provided by any physical, chemical, biological, or pharmacological modality that accomplishes the goal of protecting the astronaut from radiation hazard or increases his ability to assist other astronauts or spacecraft. The thoughtful examination of these largely operational considerations has led to identification of medical and radiobiological research required to support the industrialization of near-earth space. The scope of these research efforts involves thematic issues defined after review of the available preliminary research from several scientific disciplines that relate to the problem of radiation protection in space. This chapter provides an overview of the areas of research requiring further investigation. The needs for research are driven by the planned orbits involving small designated astronaut populations and well-defined durations that may be specific to the military and also the use of geostationary orbits, permanent lunar basing, and the proposed Mars mission that form the primary basis for these operational considerations. There are many unknown questions about space radiation, particularly involving particles of high charge and energy and the interaction of other space stressors with radiation. There are many tools that can be applied with current and future technologies.

Immunologic and hematologic perturbations in models of combined injury.

Many aspects of the reports in the literature describing anergic conditions that exist post trauma are confirmed by data gathered by the Armed Forces Radiobiology Research Institute in a comprehensive program to study combined-injury effects. Dealing with one aspect of this study, this article discusses the synergism of trauma and illness coincident with such stressors as whole-body irradiation, thermal injury, and sepsis. Experimentally produced sepsis depresses and delays both cellular and humoral response patterns in canine and murine modeling systems. Lyphoid populations, dependent on the time of collection post trauma and the organ source, may present an intially augmented response pattern, which within 48 hours becomes depressed to below-normal levels. In addition, immunologic anergy can be induced by the presence of bacterial products such as exotoxin-A. Further mechanisms and regimens of prophylactic immunomodulation are under investigation.

Summary of Discussions Following Presentations on Marrow Response and Hemopoietic Syndromes

Van Bekkum initiated the discussion by noting that the incidence of lymphoproliferative syndromes was highest in the control group. Seed noted that the incidence of lymphoproliferative diseases is acutally lower in the irradiated group in their canine population. Seed also related that no myeloproliferative disease occurred except after irradiation in the canine system. These disorders increase enormously up to 44% under the dose level of 10R per day in the canine system, resulting in fatal leukemia.