https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-22 https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-26 https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-25 https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-27 https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-24 https://bmcgastroenterol.biomedcentral.com/articles/10.1186/1471-230X-8-23