Esophageal mucosal eicosanoids in gastroesophageal reflux disease and Barrett's esophagus.

OBJECTIVE: Eicosanoids (prostaglandins and leukotrienes) may contribute to the clinical manifestations of gastroesophageal reflux disease (GERD). In this cross-sectional study, our purpose was to assess the role of leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) in the clinical, endoscopic, and histological manifestations of GERD. METHODS: Using RIA, we measured ex vivo LTB4 and PGE2 content in esophageal mucosal biopsies from 141 patients with or without gastroesophageal reflux disease who underwent upper endoscopy. Patients were classified as normal symptomatic controls(n = 70), esophagitis stages 1-4 (n = 60), and Barrett's esophagus (n = 11), using clinical, endoscopic, histological, manometric, and esophageal 24-h ambulatory pH criteria. RESULTS: Mean LTB4 levels were significantly higher in both endoscopically and histologically identified erosive esophagitis and Barrett's esophagus patients, compared with normal controls. In contrast, PGE2 levels did not differ significantly among endoscopic or histological groups. When eicosanoid levels and composite symptom score (frequency score x severity score summed over five symptoms) were analyzed, no significant associations were found between LTB4 or PGE2 levels and the composite symptom score. There was no correlation between tissue eicosanoid levels and either the degree of esophageal acid exposure by ambulatory pH monitoring or the lower esophageal sphincter resting pressure as assessed by esophageal motility. Treatment with omeprazole 20 mg by mouth daily for 6 wk significantly reduced both LTB4 and PGE2 levels (p < 0.05) and was associated with significant improvement of symptoms and the endoscopic and histological appearance of the esophagus in 25 patients. CONCLUSIONS: These results suggest that LTB4, a prominent product of arachidonic acid metabolism in neutrophils, mediates the inflammatory phenomena of reflux esophagitis. The role of LTB4 and PGE2 in the induction of symptoms in patients with GERD and Barrett's esophagus remains unclear.

Numerical calculation of energy deposition by high-energy electron beams: III. Three-dimensional heterogeneous media.

The phase space time evolution model of Huizenga and Storchi and Morawska-Kaczynska and Huizenga has been modified to accommodate calculations of energy deposition by arbitrary electron beams in three-dimensional heterogeneous media. This is a further development aimed at the use of the phase space evolution model in radiotherapy treatment planning. The model presented uses an improved method to control the evolution of the phase space state. This new method results in a faster algorithm, and requires less computer memory. An extra advantage of this method is that it allows the pre-calculation of information, further reducing calculation times. Typical results obtainable with this model are illustrated with the cases of (i) a 20 MeV pencil beam in a water phantom, (ii) a 20 MeV 5 x 5 cm2 beam in a water phantom containing two air cavities, and (iii) a 20 MeV 5 x 5 cm2 beam in a water phantom containing an aluminium region. The results of the dose distribution calculations are in good agreement with and require significantly less computation time than results obtained with Monte Carlo methods.

[Technique for postoperative irradiation of patients with breast cancer using electron and cobalt beams]. / Technika napromieniania chorych na raka sutka wiazkami elektronów i promieniami gamma Co 60.

The method of chest wall and mammary lymph node irradiation using obliquely incident electron beams is presented. Dose distributions measured in Rando phantom and calculated by computer programme are discussed. The conditions for geting homogenous dose distribution within the target volume are given. The use of this technique is limited by the degree of curvature of the chest wall and depth of tumour volume where maximum obliquity occurs. In order to minimize the lung irradiation the use of compensating boluses is recommended.