title: Unravelling the ultrastructure of ascending colon fluids from patients with ulcerative colitis by cryogenic transmission electron microscopy.
abstract: OBJECTIVE
  Studies on the characterization of ascending colonic fluids are scarce, limited to physicochemical characterization of their composition, and little is known for the morphology of the produced colloidal phases. In an attempt to gain insights for their structure at the ultrastructural level, samples from the lumen of ascending colon were collected from patients with ulcerative colitis in remission.
  
  
  METHODS
  After ultracentrifugation, the supernatants of two samples (one with high and one with low cholesterol level) were visualized by means of cryogenic transmission electron microscopy.
  
  
  RESULTS
  In the supernatants with high cholesterol content, micellar-like structures, bilayer fragments, open vesicles, and uni-, bi- and trilamellar vesicles were abundant. In addition, crystals of cholesterol were frequently observed. In contrast, in the sample with low cholesterol content, oily solids, plates of cholesterol monohydrate and elongated structures were present. Few unilamellar vesicles were occasionally visualized.
  
  
  CONCLUSIONS
  The current study gives direct evidence, for the first time, of the existence of 'remnants' of lipolytic products in the fasted ascending colon. The impact of these structures to colonic absorption of drugs is an open question.
authors.affiliation: Department of Pharmacy, The Faculty of Health & Medical Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anette
authors.initials: A
authors.lastname: Müllertz
authors.forename: Dimitrios G
authors.initials: DG
authors.lastname: Fatouros
authors.forename: Maria
authors.initials: M
authors.lastname: Vertzoni
authors.forename: Christos
authors.initials: C
authors.lastname: Reppas
mesh_terms: D001826:Body Fluids / Q000737:chemistry*; D055598:Chemical Phenomena; D002784:Cholesterol / Q000737:chemistry; D003093:Colitis, Ulcerative / Q000473:pathology*; D003102:Colloids; D044682:Colon, Ascending / Q000473:pathology* / Q000503:physiopathology; D020285:Cryoelectron Microscopy; D005766:Gastrointestinal Contents / Q000737:chemistry / Q000648:ultrastructure*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D012995:Solubility
chemical_list: D003102:Colloids; D002784:Cholesterol
keywords: cholesterol; colon fluids; cryogenic transmission electron microscopy; ulcerative colitis; vesicles