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Title Developing a time-dynamic, label-free assay for apoptosis based on optical Gabor filtering
Publication Date
Degree PhD
Discipline/Department Biomedical Engineering
Degree Level doctoral
University/Publisher Rutgers University

Apoptosis is a fundamental process in the homeostasis and development of mammals, dysfunction of its regulation is implicated in human disease, and it is of growing interest as a possible therapeutic target (especially in cancer). An apoptosis assay that is sensitive, quantitative, and label-free would therefore be useful in cancer drug discovery by offering a direct, time-dynamic in-situ assessment of apoptotic response to drug candidates. This thesis documents the development of optical Gabor filtering into an apoptosis assay. Optical Gabor filtering was developed as an improvement to optical scatter imaging (OSI) capable of optical scatter-based detection of object size and aspect ratio without the need for a predictive scatter model or extrinsic labeling. Two versions of the optical Gabor filtering instrument (LCD-based and DMD-based). By applying a series of Gabor filters with varying spatial frequencies and orientations, a series of filtered images can be generated and processed to extract morphological parameters of interest. The parameters of size, orientedness and aspect ratio are developed and tested using polystyrene microspheres, marine diatoms and collagen gelation, respectively. Orientedness and aspect ratio are employed as morphometric parameters to study dynamic morphological alterations in apoptosis. Aspect ratio measurements in apoptotic iBMK cells show a differential aspect ratio response to apoptosis induction by bax/bak expressing and bax/bak knockout cell variants. To determine the biological source of these variations, multimodal image acquisition of fluorescently-labeled mitochondria alongside Gabor filtered data is used in apoptotic endothelial cells. Results of this study show a drop in orientedness 1-2 h post-STS treatment in mitochondria-rich regions (reconnoitered by fluorescence) concomitant with mitochondrial fragmentation but absent elsewhere. This dynamic is similar but not identical to that observed from iBMK cells. OSI imaging of apoptotic BAEC also revealed that a previously reported drop in optical scatter image ratio in the first hour of apoptosis is also associated with mitochondria-rich regions. In the future, the differences between optical responses of BAEC and iBMK apoptotic cells will be elucidated with fluorescent tracking of mitochondria-rich areas in iBMK. Classification and other computational methods could also be employed to directly evaluate the optical Gabor-filtered data in the future.

Subjects/Keywords Apoptosis; Optoelectronic devices
Contributors Pasternack, Robert M, 1985- (author); Boustany, Nada N (chair); Yarmush, Martin l (internal member); Metaxas, Dimitris N (internal member); White, Eileen P (outside member)
Language en
Country of Publication us
Format xv, 156 p. : ill.
Record ID oai:example.org:rutgers-lib:34009
Other Identifiers rutgers-lib:34009; ETD_3261; doi:10.7282/T36M3651
Repository rutgers
Date Indexed 2019-08-21

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