Date of Award

Fall 2017

Document Type

USM Access Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Douglas Currie

Second Advisor

David Champlin

Third Advisor

Rachel Larsen

Abstract

Long-term manned space exploration to the moon, Mars, and other areas beyond Earth's protective magnetic field poses possible acute and late central nervous systems (CNS) risks. Of particular concern for astronauts is exposure to high atomic number, high energy particles known as HZE particles, a component of galactic cosmic radiation (GCR). Although NASA has radiation safety requirements, the possible effects of GCR and HZE particles on the central nervous systems of astronauts remains unknown. Understanding the risks and effects of galactic cosmic radiation and HZE particles on the central nervous system will allow for safer space exploration.

Additionally, and perhaps more relevant, are the effects on the CNS of patients undergoing radiation therapy for cancer treatment or for medical procedures like CT scans. Radiation (using x-rays, gamma rays, and charged particles), along with chemotherapy, is widely used to treat primary and metastatic brain tumors. Despite advances in radiation therapy, significant negative impacts on the CNS still remain.

In this study, our aim was to understand the effects of x-ray radiation on neurite morphology and cytoskeleton structure using human SH-SYSY cells, a neuroblastoma cell line commonly used for neurite outgrowth studies. In addition, we monitored cytotoxicity via a metabolic proliferation assay in neuronal cells lines, as well as a primary glial cell line and glial cell line derived from a glioma.

Immunocytochemistry results suggests that neurite length of differentiated SHSYSY cells decreases with increases in radiation dose and exposure time. Phase contrast microscopy results are contradictory; suggesting no significant differences between treated and control groups with regards to dose and time. Phase contrast microscopy does reveal neurite complexity decreases in differentiated SH-SYSY cells with select dosages and times of exposure.

Cytotoxicity results are wildly disparate between cells lines. Data indicate radiation dose and time post-treatment affect metabolic activity. However, metabolic activity between cell lines and within a cell line can either increase or decrease in response to dose and time.

Comments

This thesis is restricted to USM access only.

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