Histopathological and Molecular Changes in Intestinal Tissue Following Proton Exposure in Varying Mouse Models

Most people are aware that radiation can have negative health consequences for human beings exposed to the phenomena. These negative outcomes are dependent upon dose, dose rate, the individual’s genetic makeup and other factors. Many people do not know, however, that radiation is present constantly in the background of space, posing significant risks for astronauts traveling beyond the low Earth orbit. Protons, one form of charged particle energy, account for the greatest composition of space radiation. Scientists must better understand the aforementioned risks in order to properly counsel astronauts and health care providers about the possibilities of diseases such as cancer following radiation exposure in space flight. Low dose radiation exposure to gamma rays and protons is a much more common exposure in daily life and for astronauts in flight as opposed to high doses like those used in radiation therapy for cancer treatment. The three strategies proposed here utilize an in vivo model, specifically mice, to better extrapolate awareness of the biological consequences of low dose radiation exposure to the space flight setting and determine at the genetic level how low dose exposures differ in the radiosensitive gastrointestinal tract from high dose exposures. The gastrointestinal tract is important to study with regard to space flight for many reasons including the sensitivity of the small intestine to ionizing radiation, the high frequency of colon cancer development in the Western world, and the fact that the brave men and women who don a space suit are typically middle aged and may harbor pre-cancerous lesions even prior to irradiation. Radiation could exacerbate a cancerous event in a cell. Determining exactly which genes are being up- or down-regulated in responses after varying radiation doses and qualities can establish connections between pathways previously unknown and hopefully elucidate molecular insight into the early disease processes associated with irradiation. The significance of this study is provided in that the knowledge obtained here can be used to better select low dose radiation exposure limits, discover effective counter-measures against the harmful effects of radiation, and potentially even discern novel and favorable uses of radiation for humans.

Name thesis:degree_name

Population Health Sciences (Doctoral)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Environmental Toxicology

Grantor

The University of Texas Medical Branch at Galveston

Author dc:creator

• Purgason, Ashley

Advisor dc:contributor.advisor

• Wu, Honglu

Committee members dc:contributor.committeemember

• Abdel-Rahman, Sherif
• Ullrich, Robert
• Yu, Yongjia
• Hamilton, Stanley R

• space radiation
• protons
• gastrointestinal tract
• gene expression
• apoptosis

Handle dc:identifier.uri

http://hdl.handle.net/2152.3/685

OAI identifier oai:identifier

oai:utmb-ir.tdl.org:2152.3/685