title: Structural features of colloidal species in the human fasted upper small intestine.
abstract: OBJECTIVE
  This paper aims to study the features of colloidal species in the lumen of the upper small intestine of two healthy adults at fasted state by means of electron microscopy.
  
  
  METHODS
  Samples were aspirated from a location near the ligament of Treitz 30 min (volunteer no. 1, Aspirate30min sample) and 60 min (volunteer no. 2, Aspirate60min sample), after administration of 240 ml of an aqueous solution in the fasted state.
  
  
  RESULTS
  In the Aspirate30min sample micelles coexist with multi-, oligo- and unilamellar vesicles. Tubular structures and long structures were frequently visualised. In the Aspirate60min sample micelles, few unilamellar vesicles, long structures and tubular structures were the dominating structural features. In both samples, multivesicular structures and faceted vesicles (previously visualised at fed state) were absent. Structural features of both samples bear similarities with previously studied samples from the lower intestine in the fasted state. Micelles and unilamellar vesicles observed in both samples closely resemble morphological characteristics of those found in fluids simulating the colloidal species in fasted upper intestinal environment.
  
  
  CONCLUSIONS
  Features of colloidal species in contents of fasted small intestine have similarities with fluids simulating the contents in fasted upper small intestine and with contents of lower intestine in the fasted state.
authors.affiliation: Bioneer:FARMA, Department of Pharmaceutics and Analytical Chemistry, The Faculty of Pharmaceutical Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anette
authors.initials: A
authors.lastname: Müllertz
authors.forename: Christos
authors.initials: C
authors.lastname: Reppas
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Psachoulias
authors.forename: Maria
authors.initials: M
authors.lastname: Vertzoni
authors.forename: Dimitrios G
authors.initials: DG
authors.lastname: Fatouros
mesh_terms: D000328:Adult; D001647:Bile Acids and Salts / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry; D000067128:Extracellular Vesicles / Q000737:chemistry*; D005215:Fasting; D005766:Gastrointestinal Contents / Q000737:chemistry*; D006801:Humans; D007421:Intestine, Small / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D012995:Solubility; D013535:Suspensions
chemical_list: D001647:Bile Acids and Salts; D008055:Lipids; D008823:Micelles; D013535:Suspensions; D002784:Cholesterol
keywords: cryogenic transmission electron microscopy; fasted state; human intestinal contents; upper small intestine