References of "Aas-Hansen, Øyvind"
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See detailDamage and functional recovery of the Atlantic cod (Gadus morhua) inner ear hair cells following local injection of gentamicin
Faucher, Karine ULg; Aas-Hansen, Øyvind; Damsgård, Borge et al

in International Journal of Audiology (2009), 48(7), 456-464

This study addresses the ultrastructural and functional damage and subsequent recovery of the inner ear in the Atlantic cod following intrasaccular gentamicin injection. Inner ear damage was assessed ... [more ▼]

This study addresses the ultrastructural and functional damage and subsequent recovery of the inner ear in the Atlantic cod following intrasaccular gentamicin injection. Inner ear damage was assessed using SEM and measurements of AEP following 250-Hz pure-tone stimuli. Data from gentamicin-treated fish were compared with control (no injection) and sham (injection of saline) fish. Control fish had normal response thresholds associated with welldeveloped hair cell bundles in their macula sacculi. Sham fish had higher response thresholds compared with control fish during the first week post-intervention, but response thresholds were subsequently normal. Treated fish displayed significant inner ear damage associated with an increased average AEP threshold on the third day following treatment. Thereafter, inner ear tissue displayed signs of progressive regeneration until it was comparable to controls from the 14th day. Response thresholds were similar to those of control fish from the 17th day following treatment. These observations suggest that the macula sacculi of Atlantic cod can regenerate towards a near-complete functional and ultrastructural recovery within 17-21 days following ototoxic gentamicin treatment. [less ▲]

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See detailIntrasaccular injection of aminoglycosides: a novel method for temporary damaging fish inner ear hair cells
Faucher, Karine ULg; Aas-Hansen, Øyvind; Damsgard, Borge et al

Poster (2008, October)

Fish models are increasingly being used for hearing research investigations. Aminoglycoside antibiotics that are used for damaging the inner ear hair cells can have systemic side effects leading to death ... [more ▼]

Fish models are increasingly being used for hearing research investigations. Aminoglycoside antibiotics that are used for damaging the inner ear hair cells can have systemic side effects leading to death of study animals. This study aimed to compare two methods: i) systemic (intravenous) and ii) local (intrasaccular) gentamicin administration for induction of inner ear hair cell damage in the Atlantic cod, Gadus morhua (L.). Hair cell damage was assessed using scanning electron microscopy; hair cell density, prevalence of immature hair cells and kinocilia length were measured. Gentamicin-treated fish were compared with control and sham fish. Intravenous gentamicin led to dose-dependent mortality caused by nephrotoxicity. The only visible effect after treatment was more immature hair cells and shorter kinocilia, the effect on hair cell density was equivocal. Following intrasaccular gentamicin treatment, fish mortality was negligible, and hair cells were damaged regardless of dose. Here, we observed decreased hair cell density, high prevalence of immature hair cells, and significantly shortened kinocilia. Conclusion: intrasaccular injection is preferable to intravenous injection of gentamicin for the study of ototoxicity in the Atlantic cod. [less ▲]

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See detailEffects of systemic versus local gentamicin on the inner ear in the Atlantic cod, Gadus morhua (L.), relevance for fish hearing investigations.
Faucher, Karine ULg; Aas-Hansen, Øyvind; Damsgard, B. et al

in Hearing Research (2008), 240(1-2), 12-21

Fish models are increasingly being used for hearing research investigations. Aminoglycoside antibiotics that are used for damaging the inner ear hair cells can have systemic side effects leading to death ... [more ▼]

Fish models are increasingly being used for hearing research investigations. Aminoglycoside antibiotics that are used for damaging the inner ear hair cells can have systemic side effects leading to death of study animals. This study aimed to compare two methods: (i) systemic (intravenous) and (ii) local (intrasaccular) gentamicin administration for induction of inner ear hair cell damage in the Atlantic cod, Gadus morhua (L.). Hair cell damage was assessed using scanning electron microscopy; hair cell density, prevalence of immature hair cells and kinocilia length were measured. Gentamicin-treated fish were compared with control and sham fish. Intravenous gentamicin led to dose-dependent mortality caused by nephrotoxicity. The only visible effect after treatment was more immature hair cells and shorter kinocilia, the effect on hair cell density was equivocal. Following intrasaccular gentamicin treatment, fish mortality was negligible, and hair cells were damaged regardless of dose. Here, we observed decreased hair cell density, high prevalence of immature hair cells, and significantly shortened kinocilia. Conclusion: intrasaccular injection is preferable to intravenous injection of gentamicin for the study of ototoxicity in the Atlantic cod. [less ▲]

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See detailAminoglycoside antibiotics and the sensory hair cells of inner ear and lateral line system in the Atlantic cod, Gadus morhua: effects on fish hearing threshold
Faucher, Karine ULg; Aas-Hansen, Øyvind; Damsgard, Borge et al

Poster (2007, April)

The aims of the present study were to investigate: a) the potential involvement of the fish lateral line system in hearing at 250 Hz and b) the possible regeneration of the inner ear hair cells in the ... [more ▼]

The aims of the present study were to investigate: a) the potential involvement of the fish lateral line system in hearing at 250 Hz and b) the possible regeneration of the inner ear hair cells in the Atlantic cod (Gadus morhua). The inner ear and lateral line system of the Atlantic cod were inactivated using ototoxic aminoglycoside antibiotics by injection (gentamicin) or bath (gentamicin and streptomycin), respectively. Hearing thresholds were measured in the fish using the Auditory Brainstem Response (ABR) technique at 10, respectively 17 - 20 days following antibiotic treatment. Results were compared between groups of individuals i) with inner ear damage, ii) with lateral line system altered, iii) placebo (immersion in fresh sea water) and iv) control. The sound stimuli applied were series of 2000 five-cycle (2-1-2) 250 Hz tone bursts delivered using a Brüel & Kjær (Nærum, Denmark) loudspeaker. ABRs were measured using a filter set at 30-3000 Hz, a gain of 100 000 and visual interpretation using the Bio-Logic AEP software. Sound stimulus level was reduced until threshold was attained. To check the tissue status of the inner ear and lateral line system, hair cells from sensory maculae were visualized using scanning electron microscope (SEM). Ten days after treatment, hearing thresholds of placebo and lateral line damaged cods did not differ from controls fish (p = 0.387 and p = 0.095, respectively), whereas the fish that received intravenous gentamicin injection had significantly elevated hearing thresholds compared to controls (p < 0.0001). SEM analyses further demonstrated that, 10 days following antibiotic treatment, cod inner ear hair cells were damaged, as well as lateral line hair cells and more particularly in the case of canal neuromasts. There was no hearing effect or microscopic tissue damage in untreated fish. From the 17th day after treatment, ABR measurements showed that some of the gentamicin treated fish had regained hearing thresholds comparable to the control cods (p = 0.535), and this was associated with an apparent regeneration of hair cells in the sensory maculae of their inner ear. This study indicates a capacity for inner ear hair cell regeneration in Atlantic cod, and illustrates the advantages of the ABR-method for investigation of fish hearing after intervention on the inner ear, and during the hair cell regeneration process. The present work further suggests that the lateral line system is not involved in cod hearing at 250 Hz. [less ▲]

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