title: Inner ear damage and passage through the round window membrane of Pseudomonas aeruginosa exotoxin A in a chinchilla model.
abstract: By the use of computer-assisted morphometric analysis of the organ of Corti and/or measurements of action potential threshold changes, inner ear changes in chinchillas were evaluated 4 weeks after application on the round window membrane of a Pseudomonas aeruginosa exotoxin A solution. Severe inner ear damage was detected after application of 50 ng (5 microL at a concentration of 10 micrograms/mL) exotoxin A, whereas application of 5 ng exotoxin did not cause measurable inner ear damage. Perilymph concentrations of exotoxin A were measured with an enzyme-linked immunosorbent assay 1.5 to 19 hours after 50 ng, 0.5 micrograms, or 5 micrograms of exotoxin A was applied on the round window membrane. Only the highest concentration produced measurable levels of exotoxin in the inner ear fluids. It is concluded that exotoxin A present on the round window membrane of the chinchilla has the ability to penetrate into the inner ear and cause irreversible inner ear changes.
authors.affiliation: Department of Otorhinolaryngology, Karolinska Hospital, Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Lundman
authors.forename: P A
authors.initials: PA
authors.lastname: Santi
authors.forename: T
authors.initials: T
authors.lastname: Morizono
authors.forename: T
authors.initials: T
authors.lastname: Harada
authors.forename: S K
authors.initials: SK
authors.lastname: Juhn
authors.forename: D
authors.initials: D
authors.lastname: Bagger-Sjöbäck
mesh_terms: D036002:ADP Ribose Transferases; D000158:Acoustic Impedance Tests; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001427:Bacterial Toxins; D002682:Chinchilla; D003051:Cochlea / Q000503:physiopathology; D003936:Diagnosis, Computer-Assisted; D004195:Disease Models, Animal; D007758:Ear, Inner / Q000473:pathology; D004432:Ear, Middle / Q000187:drug effects* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005098:Exotoxins / Q000493:pharmacokinetics* / Q000633:toxicity*; D006198:Hair Cells, Auditory / Q000187:drug effects; D010033:Otitis Media / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D010539:Permeability; D011550:Pseudomonas aeruginosa; D015203:Reproducibility of Results; D012405:Round Window, Ear / Q000378:metabolism*; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D005098:Exotoxins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A