Mark Johnston

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BACKGROUND Endoscopic ablation to treat Barrett's esophagus (BE) with high-grade dysplasia (HGD) is associated with a decreased incidence of esophageal adenocarcinoma. Endoscopic spray cryotherapy (CRYO) demonstrates promising preliminary data. OBJECTIVE To assess the safety and efficacy of CRYO in BE with HGD. DESIGN Multicenter, retrospective cohort(More)
S. cerevisiae senses glucose and galactose differently. Glucose is detected through sensors that reside in the cellular plasma membrane. When activated, the sensors initiate a signal-transduction cascade that ultimately inactivates the Rgt1 transcriptional repressor by causing degradation of its corepressors Mth1 and Std1. This results in the expression of(More)
In classification, machine learning algorithms can suffer a performance bias when data sets are unbalanced. Data sets are unbalanced when at least one class is represented by only a small number of training examples (called the minority class) while the other class(es) make up the majority. In this scenario, classifiers can have good accuracy on the(More)
Machine learning algorithms such as genetic programming (GP) can evolve biased classifiers when data sets are unbalanced. Data sets are unbalanced when at least one class is represented by only a small number of training examples (called the minority class) while other classes make up the majority. In this scenario, classifiers can have good accuracy on the(More)
BACKGROUND Barrett's esophagus is a histologically defined premalignant lesion of the esophagus in which normal squamous epithelium is replaced by intestinalized columnar epithelium. In a multistep progression from Barrett's esophagus to fully developed carcinoma, accelerated proliferation may indicate or precede genomic instability and, therefore, may be(More)
BACKGROUND Numerous ablative modalities have demonstrated varying degrees of efficacy in the eradication of Barrett's esophagus (BE). However, they are associated with either high cost, patient discomfort, complications, tedious application, residual underlying BE, or some combination of the above. The aim of this study was to evaluate the safety and the(More)
BACKGROUND Few options exist for patients with localized esophageal cancer ineligible for conventional therapies. Endoscopic spray cryotherapy with low-pressure liquid nitrogen has demonstrated efficacy in this setting in early studies. OBJECTIVE To assess the safety and efficacy of cryotherapy in esophageal carcinoma. DESIGN Multicenter, retrospective(More)
Efficient uptake of glucose is especially critical to Saccharomyces cerevisiae because its preference to ferment this carbon source demands high flux through glycolysis. Glucose induces expression of HXT genes encoding hexose transporters through a signal generated by the Snf3 and Rgt2 glucose sensors that leads to depletion of the transcriptional(More)
In the ideal case, the result of applying an edge detector to an image may lead to a set of connected curves that indicate the boundaries of objects, the boundaries of surface markings, as well as curves that correspond to discontinuities in surface orientation. Many edge detection algorithms act as a convolution matrix and are applied just on one pixel and(More)