title: Differential vitreous dye diffusion following microplasmin or plasmin pre-treatment.
abstract: OBJECTIVE
  Plasmin and microplasmin are related enzymes that differ mainly in size. The differential effect of plasmin and microplasmin on vitreous structure, protein degradation, and dye diffusion through porcine vitreous was evaluated.
  
  
  METHODS
  The enzymatic effect was examined using a number of approaches on fresh porcine eyes: (1) structural integrity of vitreous after a 2-hr incubation using the electron microscope (EM); (2) effect on soluble proteins within the vitreous using gel electrophoresis after incubation at various time points over a 24-hr period; (3) fluorescein dye diffusion within the vitreous cavity measured over a 1-hr period following a 2-hr incubation. The chosen enzymatic activities for plasmin 0.5 IU and microplasmin 125 microg were within the clinical range, and were chosen for equipotence. A saline control was also used in all experiments.
  
  
  RESULTS
  Significant structural changes were seen with both microplasmin and plasmin when examined by EM. Gel electrophoresis showed that microplasmin and plasmin digested the same proteins, mainly molecular weights above 50 kDa. The enzymatic effect was noticeable earlier in microplasmin-treated eyes and was more significant by the end of the incubation period. Differential fluorescein diffusion rates were seen between normal saline, plasmin, and microplasmin within the vitreous cavity. The greatest diffusion rate was seen with microplasmin and was statistically significantly higher than plasmin.
  
  
  CONCLUSIONS
  Microplasmin and plasmin have a similar enzymatic effect on vitreous. However, an equipotent amount of microplasmin appears to have a more extended effect on vitreous gel. This may, in part, be related to its smaller size allowing it to diffuse more readily through the vitreous matrix.
authors.affiliation: Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Gad Elkareem
authors.forename: Ben
authors.initials: B
authors.lastname: Willikens
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Stassen
authors.forename: Marc D
authors.initials: MD
authors.lastname: de Smet
mesh_terms: D000818:Animals; D004058:Diffusion; D004591:Electrophoresis, Polyacrylamide Gel; D005341:Fibrinolysin / Q000494:pharmacology*; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D019793:Fluorescein / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D010446:Peptide Fragments / Q000494:pharmacology*; D013552:Swine; D014822:Vitreous Body / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D005343:Fibrinolytic Agents; D005456:Fluorescent Dyes; D010446:Peptide Fragments; C054561:microplasmin; D005341:Fibrinolysin; D019793:Fluorescein