Evaluation of intestinal motility with Magnetic Resonance Enterography and computer post-processing

Small bowel motility is an essential, physiological process central to the processing of ingested food. The small bowel is however anatomically and functionally complex, varying greatly between individuals and located deep within the abdomen making it extremely difficult to access with instrumentation. As a consequence, and in spite of its known or suspected role in a range of diseases, there remain little in the way of objective tests to evaluate or even observe this process in vivo. This thesis details the validation and application of a novel computer post-processing technique that allows the quantification of Magnetic Resonance Enterography derived time-series image data. A background to small bowel physiology and existing techniques is first provided along with an introduction to the registration algorithm used throughout this thesis to quantify small bowel motility. The technique is then applied retrospectively to two Crohn’s disease patient cohorts to explore how this inflammatory bowel disease influences contractility. A prospective evaluation of segmental motility analysis is then presented drawing attention to large within subject variation, in a cohort of healthy volunteers, as a limitation for this technique. As an alternative, a global motility analysis approach is described and validated. Although global measures of motility appeared robust, factors influencing clinical application are further addressed by expanding the technique to allow motility analysis in free-breathing data. In the final piece of research presented, the application of the global technique to a cohort of Chronic Intestinal Pseudo-Obstruction patients is detailed. The thesis is concluded with a reflection of the results and a chapter dedicated to the commercial exploitation of the research to address the ongoing need for a robust test to quantise intestinal motility

Systematic exploration of essential yeast gene function with temperature-sensitive mutants

Conditional temperature-sensitive (ts) mutations are valuable reagents for studying essential genes in the yeast Saccharomyces cerevisiae. We constructed 787 ts strains, covering 497 (~45%) of the 1,101 essential yeast genes, with ~30% of the genes represented by multiple alleles. All of the alleles are integrated into their native genomic locus in the S288C common reference strain and are linked to a kanMX selectable marker, allowing further genetic manipulation by synthetic genetic array (SGA)–based, high-throughput methods. We show two such manipulations: barcoding of 440 strains, which enables chemical-genetic suppression analysis, and the construction of arrays of strains carrying different fluorescent markers of subcellular structure, which enables quantitative analysis of phenotypes using high-content screening. Quantitative analysis of a GFP-tubulin marker identified roles for cohesin and condensin genes in spindle disassembly. This mutant collection should facilitate a wide range of systematic studies aimed at understanding the functions of essential genes