title: Morphometric analysis of lipoprotein-like particle accumulation in aging human macular Bruch's membrane.
abstract: OBJECTIVE
  To determine the size and regional distribution of lipoprotein-like particles (LLPs) that accumulate with age in Bruch's membrane (BrM).
  
  
  METHODS
  The quick-freeze/deep-etch method was used to prepare specimens of human BrM (age range, 27-78) for electron microscopic examination. Stereologic methods were used to analyze the resultant micrographs and determine the age-related changes of the LLP volume fraction and diameter distribution in various locations in BrM.
  
  
  RESULTS
  The volume fraction occupied by LLPs was found to increase monotonically with age in both the inner collagenous layer (ICL) and elastic layer (EL), but not in the outer collagenous layer (OCL). The mass of total LLP-associated lipids in BrM also increased with age. There was no significant increase in LLP size with age, but there was a modest increase in size with increased volume fraction of LLPs in BrM.
  
  
  CONCLUSIONS
  The pattern of accumulation of particles was consistent with a retinal pigment epithelium (RPE) source for the LLPs, which explains why once the EL and ICL were filled with particles, LLPs continued to accumulate near the RPE, but no further accumulation was found in the OCL. The quantity of LLP-associated lipids found in BrM accounts for a large portion of the accumulated lipids measured in this tissue.
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208-3107, USA.
authors.forename: Jiahn-Dar
authors.initials: JD
authors.lastname: Huang
authors.forename: Christine A
authors.initials: CA
authors.lastname: Curcio
authors.forename: Mark
authors.initials: M
authors.lastname: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology*; D016570:Bruch Membrane / Q000378:metabolism / Q000648:ultrastructure*; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D005136:Eye Proteins / Q000378:metabolism / Q000648:ultrastructure*; D005260:Female; D005613:Freeze Etching / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000378:metabolism / Q000648:ultrastructure*; D008266:Macula Lutea / Q000378:metabolism / Q000648:ultrastructure*; D008268:Macular Degeneration / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged
chemical_list: D005136:Eye Proteins; D008074:Lipoproteins