title: Methods for exploring the semantics of the relationships between co-occurring UMLS concepts.
abstract: OBJECTIVE
  To characterize the relationships among UMLS concepts that co-occur as MeSH descriptors in MEDLINE citations (1990-1999).
  
  
  METHODS
  18,485 UMLS concepts involved in 7,928,608 directed pairs of co-occurring concepts were studied. For each directed pair of concepts C1-C2: (i) the "family" of C1 was built, using the UMLS Metathesaurus, and we tested whether or not C2 belonged to C1's family; (ii) we used the semantic categorization of Metathesaurus concepts through the UMLS Semantic Network and Semantic Groups to represent the semantics of the relationships between C1 and C2.
  
  
  RESULTS
  In 6.5% of the directed pairs, the co-occurring concept C2 was found within the "family" of C1. Detailed results are given. The most frequent co-occurrences involved "Chemicals and Drugs" and "Chemicals and Drugs", as well as "Disorders" and "Chemicals and Drugs".
  
  
  CONCLUSIONS
  This work takes advantage of both symbolic and statistical information represented in the UMLS, and analyzes their overlap. Further research is suggested.
authors.affiliation: U.S. National Library of Medicine, Bethesda, MD 20894, USA. burgun@nlm.nih.gov
authors.forename: A
authors.initials: A
authors.lastname: Burgun
authors.forename: O
authors.initials: O
authors.lastname: Bodenreider
mesh_terms: D016239:MEDLINE; D012660:Semantics; D013358:Subject Headings; D017432:Unified Medical Language System / Q000458:organization & administration