Faculty Bibliography

Cell-based fluorescence imaging assays are heterogeneous and require the collection of a large number of images for detailed quantitative analysis. Complexities arise as a result of variation in spatial nonuniformity, shape, overlapping compartments and scale (size). A new technique and methodology has been developed and tested for delineating subcellular morphology and partitioning overlapping compartments at multiple scales. This system is packaged as an integrated software platform for quantifying images that are obtained through fluorescence microscopy. Proposed methods are model based, leveraging geometric shape properties of subcellular compartments and corresponding protein localization. From the morphological perspective, convexity constraint is imposed to delineate and partition nuclear compartments. From the protein localization perspective, radial symmetry is imposed to localize punctate protein events at submicron resolution. Convexity constraint is imposed against boundary information, which are extracted through a combination of zero-crossing and gradient operator. If the convexity constraint fails for the boundary then positive curvature maxima are localized along the contour and the entire blob is partitioned into disjointed convex objects representing individual nuclear compartment, by enforcing geometric constraints. Nuclear compartments provide the context for protein localization, which may be diffuse or punctate. Punctate signal are localized through iterative voting and radial symmetries for improved reliability and robustness. The technique has been tested against 196 images that were generated to study centrosome abnormalities. Corresponding computed representations are compared against manual counts for validation

OBJECTIVES: Gene therapy using cells as vectors to achieve secretion of therapeutic proteins may hold promise in the treatment of chronic diseases. Cell-based gene therapy with xenogeneic cells secreting antiinflammatory cytokines (IL-4, IL-13, or IL-1 receptor type II) has been found effective in mice with collagen-induced arthritis (CIA), a model for human rheumatoid arthritis. Autologous cells engineered to produce antiinflammatory cytokines were also effective in the mouse CIA model. In all these experiments, the cells were grafted into the subcutaneous tissue of the back, resulting in systemic treatment. To evaluate the feasibility of cell-based gene therapy confined to the joints, we performed intraarticular injections of autologous cells in a rhesus monkey with CIA, a model more similar to human RA. METHODS: We prepared ex vivo cultures of skin fibroblasts from the animal then transfected the cells with a plasmid carrying the lacZ gene. We injected these marker cells into metacarpophalangeal, metatarsophalangeal, and interphalangeal joints. RESULTS: Kinetic evaluation of synovial tissue X-gal labeling, which reflected reported gene expression by skin fibroblasts present within the synovium, showed significant labeling by transfected cells up to 6 days after intraarticular injection. Xenogeneic fibroblasts (Chinese hamster ovary cells) injected intraarticularly were also detected within synovial specimens; however, labeling intensity was less marked than with autologous cells. Our findings establish the feasibility of skin fibroblast grafting into the synovium. CONCLUSION: This preliminary study opens the door to studies of heterotopic autologous transfected cells for the treatment of CIA in monkeys by direct gene transfer within joints.

We describe the strategies and implementation details we employed to parallelize the SPIDER software package on distributed-memory parallel computers using the message passing interface (MPI). The MPI-enabled SPIDER preserves the interactive command line and batch interface used in the sequential version of SPIDER, thus does not require users to modify their existing batch programs. We show the excellent performance of the MPI-enabled SPIDER when it is used to perform multi-reference alignment and 3-D reconstruction operations on a number of different computing platforms. We point out some performance issues when the MPI-enabled SPIDER is used for a complete 3-D projection matching refinement run, and propose several ways to further improve the parallel performance of SPIDER on distributed-memory machines

BACKGROUND: Diabetics suffer from vascular dysfunction with increased risks of coronary artery disease and peripheral vascular disease secondary to an impaired ability to respond to tissue ischemia. Because endothelial progenitor cells are known to home to sites of ischemia and participate in new blood vessel growth, the authors examined the effects of diabetes on human endothelial progenitor cell function and peripheral tissue signaling in hypoxia, and determined whether these cells might be a useful cell-based therapy for diabetic vascular complications. METHODS: Circulating human endothelial progenitor cells from type 2 diabetic patients and controls were isolated and subjected to in vitro adhesion, migration, and proliferation assays (n = 5). Cell mobilization and recruitment were studied in vivo in diabetic and nondiabetic environments (n = 6). Exogenous human diabetic and normal cells were analyzed for therapeutic efficacy in a murine ischemia model (n = 6). RESULTS: Adhesion, migration, and proliferation of human diabetic endothelial progenitor cells in response to hypoxia was significantly reduced compared with controls. In diabetic mice, cell mobilization from the bone marrow and recruitment into ischemic tissue was significantly reduced compared with controls. Normal cells injected systemically as replacement therapy in a diabetic mouse increased but did not normalize ischemic tissue survival. CONCLUSIONS: These findings suggest that diabetes causes defects in both the endothelial progenitor cell and peripheral tissue responses to hypoxia. These changes in endothelial progenitor cell function and signaling offer a novel explanation for the poor clinical outcome of type 2 diabetics following ischemic events. Based on these findings, it is unlikely that endothelial progenitor cell-based cellular therapies will be able to prevent diabetic complications