Quantitative imaging of living cells by deep ultraviolet microscopy

Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2006.Includes bibliographical references (p. 139-145).Developments in light microscopy over the past three centuries have opened new windows into cell structure and function, yet many questions remain unanswered by current imaging approaches. Deep ultraviolet microscopy received attention in the 1950s as a way to generate image contrast from the strong absorbance of proteins and nucleic acids at wavelengths shorter than 300 nm. However, the lethal effects of these wavelengths limited their usefulness in studies of cell function, separating the contributions of protein and nucleic acid proved difficult, and scattering artifacts were a significant concern. We have used short exposures of deep-ultraviolet light synchronized with an ultraviolet-sensitive camera to observe mitosis and motility in living cells without causing necrosis, and quantified absorbance at 280 nm and 260 nm together with tryptophan native fluorescence in order to calculate maps of nucleic acid mass, protein mass, and quantum yield in unlabeled cells. We have also developed a method using images acquired at 320nm and 340nm, and an equation for Mie scattering, to determine a scattering correction factor for each pixel at 260nm and 280nm. These developments overcome the three main obstacles to previous deep UV microscopy efforts, creating a new approach to imaging unlabeled living cells that acquires quantitative information about protein and nucleic acid as a function of position and time.by Benjamin J. Zeskind.Ph.D

Microwave Devices Employing Magnetic Waves

Contains research objectives and summary of research on two research projects.Joint Services Electronics Program (Contract DAAB07-76-C-1400

Microwave Devices Employing Magnetic Waves

Contains reports on three research projects.Joint Services Electronics Program (Contract DAAB07-76-C-1400)National Science Foundation (Grant ENG76-18359

Spatially resolved light propagation in tissue-like media

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references.The work presented in this thesis is part of a larger project designed to monitor and diagnose Alzheimer's disease non-invasively in vivo using spatially resolved nearinfrared (NIR) spectroscopy. Alzheimer's disease is one of the most common forms of senile dementia occurring in the elderly population, and at present has no cure. The first step in developing a monitoring instrument involves differentiating the optical properties of tissue. In this body of work, a protocol and algorithm for deriving the scattering and absorption coefficients for a spatially resolved reflectance apparatus was developed, characterized, and tested. In models with tissue-like properties, this protocol and algorithm works to derive the appropriate scattering and absorption information, which is the first step in developing a spatially resolved NIR detection device.by Julie E. Zeskind.M.Eng

Quantitative dispersion microscopy

Refractive index dispersion is an intrinsic optical property and a useful source of contrast in biological imaging studies. In this report, we present the first dispersion phase imaging of living eukaryotic cells. We have developed quantitative dispersion microscopy based on the principle of quantitative phase microscopy. The dual-wavelength quantitative phase microscope makes phase measurements at 310 nm and 400 nm wavelengths to quantify dispersion (refractive index increment ratio) of live cells. The measured dispersion of living HeLa cells is found to be around 1.088, which agrees well with that measured directly for protein solutions using total internal reflection. This technique, together with the dry mass and morphology measurements provided by quantitative phase microscopy, could prove to be a useful tool for distinguishing different types of biomaterials and studying spatial inhomogeneities of biological samples

Leveraging existing data sets to generate new insights into Alzheimer’s disease biology in specific patient subsets

To generate new insights into the biology of Alzheimer’s Disease (AD), we developed methods to combine and reuse a wide variety of existing data sets in new ways. We first identified genes consistently associated with AD in each of four separate expression studies, and confirmed this result using a fifth study. We next developed algorithms to search hundreds of thousands of Gene Expression Omnibus (GEO) data sets, identifying a link between an AD-associated gene (NEUROD6) and gender. We therefore stratified patients by gender along with APOE4 status, and analyzed multiple SNP data sets to identify variants associated with AD. SNPs in either the region of NEUROD6 or SNAP25 were significantly associated with AD, in APOE4+ females and APOE4+ males, respectively. We developed algorithms to search Connectivity Map (CMAP) data for medicines that modulate AD-associated genes, identifying hypotheses that warrant further investigation for treating specific AD patient subsets. In contrast to other methods, this approach focused on integrating multiple gene expression datasets across platforms in order to achieve a robust intersection of disease-affected genes, and then leveraging these results in combination with genetic studies in order to prioritize potential genes for targeted therapy

Microwave Devices Employing Magnetic Waves

Contains reports on six research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020)National Science Foundation (Grant ENG76-18359

Electronic and Optical Materials and Applications

Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020)United States Air Force (Contract F19628-79-C-0047

Microwave and Quantum Magnetics

Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Institutes of Health (Grant 1 P01 CA3 1303-01

Microwave and Quantum Magnetics

Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Institutes of Health (Grant 1 P01 CA3 1303-01