Felix W. Leung

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Reflectance spectrophotometry in assessing gastroduodenal mucosal perfusion was evaluated. Ischemia without congestion, e.g., during hemorrhagic hypotension or celiac artery occlusion, was associated with a reduction in the indexes of mucosal hemoglobin concentration and of oxygen saturation. Ischemia with congestion, e.g., during portal vein occlusion, or(More)
BACKGROUND The direct and indirect costs of sedation limit access to screening colonoscopy amongst United States veterans. AIM To determine if offering the option of sedation on-demand reduces the need for sedation. Design A retrospective review of prospectively collected performance improvement data in an open access screening colonoscopy programme. (More)
  • F W Leung
  • The American journal of physiology
  • 1992
Exposure of the colonic mucosa to 10% acetic acid results in ischemia and damage of the exposed mucosa and hyperemia in the adjacent unexposed and undamaged mucosa. We hypothesize that this hyperemia is mediated in part by capsaicin-sensitive afferent nerves, and absence of the hyperemia is associated with aggravation of damage in the exposed mucosa. In(More)
Epidemiological and experimental evidence have shown that nicotine has harmful effects on the gastric mucosa. The mechanisms by which cigarette smoking or nicotine adversely affect the gastric mucosa have not been fully elucidated. In this report, clinical and experimental data are reviewed. The effects of nicotine from smoking on gastric aggressive or(More)
Reflectance spectrophotometry measures indices of mucosal hemoglobin concentration (IHB) and oxygen saturation (ISO2). In the rat colon, characteristic patterns of IHB and ISO2 are associated with ischemia with congestion (increased IHB and decreased ISO2) and ischemia without congestion (decreased IHB and decreased ISO2). Endoscopic measurements with(More)
BACKGROUND Water-aided methods for colonoscopy are distinguished by the timing of removal of infused water, predominantly during withdrawal (water immersion) or during insertion (water exchange). OBJECTIVE To discuss the impact of these approaches on colonoscopy pain and adenoma detection rate (ADR). DESIGN Systematic review. SETTING Randomized,(More)
BACKGROUND An observational study in veterans showed that a novel water method (water infusion in lieu of air insufflation) enhanced cecal intubation and willingness to undergo a repeat scheduled unsedated colonoscopy. OBJECTIVE To confirm these beneficial effects and significant attenuation of discomfort in a randomized, controlled trial (RCT). DESIGN(More)
OBJECTIVES Minimal sedation obviates patient recovery burdens, but intolerable pain limits success of cecal intubation. Painless or minimally uncomfortable insertion ensures success of cecal intubation, current patient satisfaction, and willingness to repeat future colonoscopy with minimal sedation. Water immersion (WI) and water exchange (WE), when(More)
Adenosine triphosphate-dependent potassium (K+ATP) channels in several types of vascular smooth muscles mediate the vasodilation induced by calcitonin gene-related peptide (CGRP). Upon stimulation, primary afferent nerve terminals in the gastric mucosa release CGRP which mediates a protective hyperemia. We tested the hypothesis that a potassium channel(More)
This report summarizes clinical and experimental data in support of the hypothesis that capsaicin-sensitive intestinal mucosal afferent mechanism plays a role in regulating body fat distribution. Epidemiological data have revealed that the consumption of foods containing capsaicin is associated with a lower prevalence of obesity. Rural Thai people consume(More)