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2005 RET Participant Lisa Hamilton

Lisa Hamilton
Antioch High School
AP Biology Teacher

Biomedical Optics Laboratory - Anita Mahadevan-Jansen, Ph.D.

Dr. Anita Mahadevan-Jansen allowed me to work in her optics lab over the course of approximately 4 weeks. This experience introduced me to the concepts of optical physics using fluorescence to detect absorption differences among malignant, benign, and normal breast tissue samples.

My first measurements involved using a nitrogen laser that emits a wavelength of light at 337 nm. The technique involved allowing the laser to actually touch the tissue allowing little, if any, ambient light to be absorbed. Lights were turned off and measurements were taken using a specific software program The software allowed for three measurements a baseline, fluorescence, and diffuse reflectance. Using MatLab to analyze data allowed detection of differences between the three different sample types. Once each sample had measurements at a minimum of three locations, samples were preserved in formalin solution.

Other measurements were taken using a fluorimeter and a collaborative software program. Samples were placed in the fluorimeter individually and scanned at various increments over a long period of time. The fluorimeter allows for many scans, each at a different wavelength. For example, each breast tissue sample was scanned at 61 different wavelengths. Each of the scans lasted approximately one minute in duration and produced its individual spectrum. Once all scans were complete, the spectra were viewed collectively using MatLab as an EEM (Excitation Emission Matrix).

Both instruments involved looking at absorption and emission. The nitrogen laser involved only one excitation wavelength, while the fluorimeter involved many excitation wavelengths. This technique allows for the determination of the optimal excitation wavelength necessary to produce to significant differences between normal and malignant breast tissue; differences created by the varying levels of NADH within cancerous versus normal tissues. Cancerous tissues are growing at a very rapid rate and compared to normal tissues and will therefore contain a greater amount of NADH due to an increased rate of cellular respiration.

I will use data from the nitrogen laser samples to engage students in learning about cellular respiration. I am in the process of creating a module that will facilitate a connection between the diagnostic use of lasers in cancer research and cellular respiration.