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Submitted on: 01 January 2000.
Revised on: 06 February 2000.
Accepted on: 25 March 2000.
___________________GASTROENTEROLOGY CLINICS OF NORTH AMERICA
Submitted on: 17 August 2001.
Revised on: 15 November 2001.
Accepted on: 05 January 2002.
___________________GASTROENTEROLOGY CLINICS OF NORTH AMERICA
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Submitted on: 27 April 1999.
Revised on: 23 May 1999.
Accepted on: 28 June 1999.
___________________GASTROENTEROLOGY CLINICS OF NORTH AMERICA
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