title: Posterior vitreous detachment induced by nattokinase (subtilisin NAT): a novel enzyme for pharmacologic vitreolysis.
abstract: OBJECTIVE
  To investigate the effects of intravitreal injection of nattokinase (subtilisin NAT), a serine protease that is produced by Bacillus subtilis (natto), for induction of posterior vitreous detachment (PVD).
  
  
  METHODS
  Different doses of nattokinase (1, 0.1, or 0.01 fibrin-degradation units [FU]) or physiologic saline as a control were injected into the vitreous cavity of rabbit eyes. Scanning electron microscopy was used to observe the retinal surfaces of four rabbit eyes per concentration. Histologic alterations were assessed by light microscopy, using four eyes from each group. Electroretinography (ERG) was performed to observe retinal function, ranging from 1 hour to 1 week after the nattokinase (1 or 0.1 FU) or saline solution administration, using four eyes from each group at each time point. Also, findings in all rabbits were monitored by slit lamp examination and by indirect ophthalmoscopy with a 20-D lens.
  
  
  RESULTS
  Scanning electron microscopy showed smooth retinal surfaces, indicating the occurrence of PVD at 30 minutes after intervention in all the experimental eyes injected with 0.1 or 1.0 FU nattokinase, but none of the control eyes. Light microscopy and ERG analysis showed no critical change even after the use of 0.1 FU nattokinase, an amount sufficient to induce PVD. However, toxicity in the forms of preretinal hemorrhage and ERG changes was noted with the higher dose (1 FU) of nattokinase.
  
  
  CONCLUSIONS
  The results suggested that nattokinase is a useful enzyme for pharmacologic vitreolysis because of its efficacy in inducing PVD.
authors.affiliation: Department of Ophthalmology and Visual Science, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.
authors.forename: Akiomi
authors.initials: A
authors.lastname: Takano
authors.forename: Akira
authors.initials: A
authors.lastname: Hirata
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Nina
authors.initials: N
authors.lastname: Sagara
authors.forename: Yasuya
authors.initials: Y
authors.lastname: Inomata
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kawaji
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Tanihara
mesh_terms: D000818:Animals; D004596:Electroretinography; D007267:Injections; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D012160:Retina / Q000502:physiology / Q000648:ultrastructure; D013381:Subtilisins / Q000494:pharmacology* / Q000633:toxicity; D014822:Vitreous Body / Q000187:drug effects*; D020255:Vitreous Detachment / Q000139:chemically induced* / Q000473:pathology
chemical_list: D013381:Subtilisins; C053771:nattokinase