1. Volume 133, Issue 1, Pages 164-174 (July 2007)
N-Nitrosamine Generation From Ingested Nitrate Via Nitric Oxide in Subjects With and Without Gastroesophageal Reflux 
Jack W. Winter, Stuart Paterson, Gordon Scobie, Angela Wirz, Tom Preston, Kenneth E.L. McColl 
Gastroenterology 
Volume 133, Issue 1, Pages (July 2007)
DOI: /j.gastro
Copyright © 2007 AGA Institute Terms and Conditions

2. Figure 1
Chemical reactions occurring when nitrite enters acidic gastric juice. Nitrite is converted to nitrous acid and nitrosating species (N2O3, NO+, and NOSCN). In the absence of ascorbic acid, these can react with nitrosatable species to form N-nitroso compounds in the luminal compartment. Ascorbic acid in the gastric juice prevents this luminal nitrosation by converting the nitrosating species to nitric oxide. However, nitric oxide can diffuse into the epithelial compartment, reacting with oxygen to form the nitrosating species N2O3, which exerts nitrosative stress within the epithelial compartment. Nitrite is formed in the epithelial compartment predominantly by the reaction of N2O3 with water, but also by the diffusion of nitrous acid (NO2).
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

3. Figure 2
Region of segmented Silastic tube attached to the pH catheter. Each section contains morpholine 25 mmol/L buffered at pH 7.4 and is 15 mm in length. Section 10 is apposed to probe 1 and sections 13 and 14 are apposed to probes 2 and 3, respectively.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

4. Figure 3
Plain posteroanterior chest radiograph of specialized esophagogastric tube in situ within the upper gastrointestinal tract of a human healthy volunteer. Sections 13 and 14 are apposed to probes 2 and 3 and lie on either side of the pH step-up point. Section 10 is apposed to probe 1 and is positioned 5 cm proximal to the pH step-up point. Section 19 is apposed to probe 4 and section 21 lies 12 cm inside the stomach, apposed to a radio-opaque marker.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

5. Figure 4
Median Silastic tube nitrite concentration by location for 15 healthy volunteers. Sections 1–13 lie above the pH step-up point and sections 14–21 lie below the pH step-up point. The grey broken vertical line between sections 13 and 14 represents the pH step-up point, and the surrounding rectangle represents the range of excursion of the pH step-up point with normal respiration. Results after administration of the control drink are represented by open boxes, and after administration of 2 mmoles nitrate by filled boxes. Whiskers represent interquartile ranges.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

6. Figure 5
Median Silastic tube N-nitrosomorpholine (nmor) concentration by location for 15 healthy volunteers. Sections 1–13 lie above the pH step-up point and sections 14–21 lie below the pH step-up point. The grey broken vertical line between sections 13 and 14 represents the pH step-up point, and the surrounding rectangle represents the range of excursion of the pH step-up point with normal respiration. Results after administration of the control drink are represented by open boxes, and after administration of 2 mmoles nitrate by filled boxes. Whiskers represent interquartile ranges.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

7. Figure 6
Fitted line plot comparing the percentage of time pH was less than 4, 5 cm above the gastroesophageal junction (marked by the clips at the top of the gastric folds), with the proportion of total nitrite formed within the esophageal sections.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

8. Figure 7
Fitted line plot comparing the percentage of time pH was less than 4, 5 cm above the gastroesophageal junction (marked by the clips at the top of the gastric folds), with the proportion of total N-nitrosomorpholine formed within the esophageal sections.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions

9. Figure 8
Median ratio of N-nitrosomorpholine:nitrite by location in the upper gastrointestinal tract in patients with Barrett’s esophagus.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2007 AGA Institute Terms and Conditions