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First forty-eight hours of developing otitis media: An experimental study
Umeå University, Faculty of Medicine, Clinical Sciences.
2003 (English)In: Annals of Otology, Rhinology and Laryngology, ISSN 0003-4894, E-ISSN 1943-572X, Vol. 112, no 6, 558-566 p.Article in journal (Refereed) Published
Abstract [en]

The early inflammatory changes in the tympanic membrane were explored in 2 rat models. Acute otitis media was induced by instillation of Streptococcus pneumoniae type 3 into the middle ear cavity, and otitis media with effusion was induced by blockage of the eustachian tube. Otomicroscopic examination was performed before the rats were painlessly sacrificed at 3, 6, 9, 12, 18, 24, or 48 hours after initiation of the otitis media conditions. The tympanic membrane was studied by light and electron microscopy. Both acute otitis media and otitis media with effusion caused early inflammatory changes of the tympanic membrane, and the pars flaccida was the portion that reacted first. The inflammatory alterations were most pronounced in the acute otitis media model. The course of inflammation showed a bimodal pattern with an early deposition of a filamentous material with a band pattern, typical of fibrin. Despite a fluid-filled middle ear cavity, the inflammatory changes in the otitis media with effusion model were moderate, as was consistent with the clinical appearance of the tympanic membrane.

Place, publisher, year, edition, pages
2003. Vol. 112, no 6, 558-566 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:umu:diva-3348PubMedID: 12834127OAI: oai:DiVA.org:umu-3348DiVA: diva2:142010
Available from: 2004-01-19 Created: 2004-01-19 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Developing otitis media: experimental studies in particular regarding inflammatory changes in the tympanic membrane
Open this publication in new window or tab >>Developing otitis media: experimental studies in particular regarding inflammatory changes in the tympanic membrane
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Otitis media (OM), one of the commonest of childhood diseases, causes much suffering. OM exists in a variety of forms, two of which are acute otitis media (AOM) and otitis media with effusion (OME). The clinical courses of these conditions differ, AOM usually presenting with earache, fever and/or aural discharge, and the OME usually with hearing impairment. The tympanic membrane (TM) mirrors the events in the middle ear cavity, and pars flaccida (PF) is the initial site of inflammatory changes in the TM. PF is rich in mast cells (MCs), which by releasing various mediators, may trigger TM inflammation.

The aims of the present studies were to investigate early inflammatory changes in the TM in rat models of OM; after mast cell degranulation, in response to AOM, and OME, after myringotomy in AOM and in normal ears. Furthermore, we developed a new rat AOM model, that excludes surgical trauma and resembles the natural route of infection in man.

AOM and OME elicited the first inflammatory response in PF of the TM. The response to OME was discrete, but a slight increase in macrophages was found. During the first 48 hours of AOM, the inflammatory response was intense, following a bimodal pattern. This reaction is similar to that found after MC degranulation. In AOM, macrophages were the predominant cell in PF, while in pars tensa (PT), polymorphonuclear cells (mainly neutrophils) predominated.

When myringotomy was performed in AOM ears, the healing time was shorter than that of myringotomy in normal ears. The highly inflamed lamina propria seemed to promote healing.

During early AOM, as well as following myringotomy, fibrin extravasates into PF and PT. This fibrin deposition may be involved in regulating the inflammatory response.

Repeated nasal challenge with the otitis media pathogen Streptococcus pneumoniae provoked AOM and concomitant TM stimulation reduced the number of AOM cases. This new rat AOM model has the advantage of avoiding trauma in the middle ear cavity, while eliciting an intense inflammatory response in the middle ear cavity (MEC).

Publisher
56 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 871
Keyword
Otorhinolaryngology, otitis media with effusion, acute otitis media, myringotomy, tympanic membrane, rat, Streptococcus pneumoniae, compound 48/80, mast cell, Otorhinolaryngologi
National Category
Otorhinolaryngology
Research subject
Oto-Rhino-Laryngology
Identifiers
urn:nbn:se:umu:diva-180 (URN)91-7305-580-8 (ISBN)
Public defence
2004-02-13, Sal D (grå salen), 1D, Tandläkarhögskolan, Norrlands Universitetssjukhus, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2004-01-19 Created: 2004-01-19 Last updated: 2010-04-12Bibliographically approved

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