Engineering mechanotransduction in mammalian cells using the Notch receptor

Mechanical forces are fundamental regulators of biology. Individual cells can detect environmental forces and transform them into intracellular biochemical actions, which impact gene expression, metabolism, and differentiation. In turn, this phenomenon of “mechanotransduction” at the cellular level affects tissue- and organ-level function and can shape disease progressions. Tools that enable researchers to genetically harness mechanotransduction would therefore be powerful for developing of novel tissue engineering and cell therapy technologies. However, synthetically engineering mechanotransduction in cells has remained difficult. In this thesis, we control how cells respond to molecular forces by engineering modular mechanosensitive receptors. Using a structured-guided approach, we engineered force-sensitive protein domains that, when inserted into synthetic Notch receptors, vary the input-output relationship between mechanical force and cellular action. We demonstrate that the mechanical strength of these domains can be systematically tuned through mutagenesis. We show that our synthetic mechanoreceptors enable the design of signaling networks where tensile forces in the environment are recorded as measurable and specifiable biochemical responses, such as myogenic differentiation in mouse embryonic fibroblasts. We then present additional technologies for modulating the Notch mechanoreceptor’s endogenous mechanical strength, ligand-mediated activation, and protease-regulated activation. Taken together, this dissertation introduces a mechanogenetic framework for synthetically controlling mechanotransduction in mammalian cells, informs the design of future synthetic force-sensitive pathways, and provides valuable tools for the study of Notch signaling in development and disease.2022-09-30T00:00:00

Exploratory Spatial Data Analysis of the Relationship between Sex Offender Residence and Treatment Service Accessibility in Kentucky.

Paper presented at the 2009 Applied Geography Conference by Timothy S. Hare, Paul D. Steele and Lincoln B. Sloas

Impact of antibiotic resistance on chemotherapy for pneumococcal infections

Over the past three decades, penicillin-resistant pneumococci have emerged worldwide. In addition, penicillin-resistant strains have also decreased susceptibility to other β-lactams (including cephalosporins) and these strains are often resistant to other antibiotic groups, making the treatment options much more difficult. Nevertheless, the present in vitro definitions of resistance to penicillin and cephalosporins in pneumococci could not be appropriated for all types of pneumococcal infections. Thus, current levels of resistance to penicillin and cephalosporin seem to have little, if any, clinical relevance in nonmeningeal infections (e.g., pneumonia or bacteremia). On the contrary, numerous clinical failures have been reported in patients with pneumococcal meningitis caused by strains with MICs ≥ 0.12 μg/ml, and penicillin should never be used in pneumococcal meningitis except when the strain is known to be fully susceptible to this drug. Today, therapy for pneumococcal meningitis should mainly be selected on the basis of susceptibility to cephalosporins, and most patients may currently be treated with high-dose cefotaxime (±) vancomycin, depending on the levels of resistance in the patient's geographic area. In this review, we present a practical approach, based on current levels of antibiotic resistance, for treating the most prevalent pneumococcal infections. However, it should be emphasized that the most appropriate antibiotic therapy for infections caused by resistant pneumococci remains controversial, and comparative, randomized studies are urgently needed to clarify the best antibiotic therapy for these infection