Evoked potentials in the Atlantic cod following putatively innocuous and putatively noxious electrical stimulation: a minimally invasive approach

Aspects of peripheral and central nociception have previously been studied through recording of somatosensory evoked potentials (SEPs) to putative noxious stimuli in specific brain regions in a few freshwater fish species. In the present study, we describe a novel, minimally invasive method for recording SEPs from the central nervous system of the Atlantic cod (Gadus morhua). Cutaneous electric stimulation of the tail in 15 fish elicited SEPs at all stimulus intensities (2, 5, 10 and 20 mA) with quantitative properties corresponding to stimulus intensity. In contrast to previous fish studies, the methodological approach used in Atlantic cod in the current study uncovered a number of additional responses that could originate from multiple brain regions. Several of these responses were specific to stimulation at the highest stimulus intensities, possibly representing qualitative differences in central processing between somatosensory and nociceptive stimuli

Intrasaccular injection of aminoglycosides: a novel method for temporary damaging fish inner ear hair cells

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

Damage and functional recovery of the Atlantic cod (Gadus morhua) inner ear hair cells following local injection of gentamicin

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

Utvikling av «Hamle» – digital løsning for å redusere matsvinn.

Denne oppgaven er gitt av Smart Gjøvik, som et tverrfaglig bachelorprosjekt for to webutviklingsstudenter og en interaksjonsdesignstudent hos Norges TekniskNaturvitenskapelige Universitet i Gjøvik. Oppgaven er gitt på bakgrunn av at Gjøvik Kommune ønsker å redusere matsvinn, og prosjektet har basert seg på å utvikle en digital løsning som kan bidra til å redusere matsvinn hos husholdninger i hele Norge. Denne rapporten dokumenterer hvordan gruppen har utviklet et minimumprodukt kalt «Hamle» ved bruk av innsiktsarbeid, design og iterativ fullstack-apputvikling

Hearing loss and tinnitus in rock musicians: A Norwegian survey

Our focus in this study was to assess hearing thresholds and the prevalence and characteristics of tinnitus in a large group of rock musicians based in Norway. A further objective was to assess related factors such as exposure, instrument category, and the preventive effect of hearing protection. The study was a cross-sectional survey of rock musicians selected at random from a defined cohort of musicians. A random control group was included for comparison. We recruited 111 active musicians from the Oslo region, and a control group of 40 nonmusicians from the student population at the University of TromsØ. The subjects were investigated using clinical examination, pure tone audiometry, tympanometry, and a questionnaire. We observed a hearing loss in 37.8% of the rock musicians. Significantly poorer hearing thresholds were seen at most pure-tone frequencies in musicians than controls, with the most pronounced threshold shift at 6 kHz. The use of hearing protection, in particular custom-fitted earplugs, has a preventive effect but a minority of rock musicians apply them consistently. The degree of musical performance exposure was inversely related to the degree of hearing loss in our sample. Bass and guitar players had higher hearing thresholds than vocalists. We observed a 20% prevalence of chronic tinnitus but none of the affected musicians had severe tinnitus symptomatology. There was no statistical association between permanent tinnitus and hearing loss in our sample. We observed an increased prevalence of hearing loss and tinnitus in our sample of Norwegian rock musicians but the causal relationship between musical exposure and hearing loss or tinnitus is ambiguous. We recommend the use of hearing protection in rock musicians

Hearing in schoolchildren after neonatal exposure to a high-dose gentamicin regimen

OBJECTIVE: To assess the association between gentamicin exposure in the neonatal period and hearing in school age. METHODS: This study included children exposed to a high-dose (6 mg/kg) gentamicin regimen as neonates (2004–2012), invited for follow-up at school age, and a healthy age-matched control group. We assessed hearing with pure tone audiometry including the extended high-frequency (EHF) range. Outcomes were average hearing thresholds in the midfrequencies (0.5–4 kHz) and the EHFs (9–16 kHz). The measures of gentamicin exposure were cumulative dose and highest trough plasma concentration. We used linear regression models to assess the impact of gentamicin exposure, and other peri- and postnatal morbidities, on hearing thresholds. RESULTS: A total of 219 gentamicin-exposed and 33 healthy-control children were included in the audiological analysis. In the gentamicin cohort, 39 (17%) had a birth weight <1500 g. Median cumulative doses and trough plasma concentrations were 30 (interquartile range 24–42) mg/kg and 1.0 (interquartile range 0.7–1.2) mg/L, respectively. Median hearing thresholds for the midfrequencies and the EHFs were 2.5 (0 to 6.3) dB hearing level and −1.7 (−5.0 to 5.0) dB hearing level, both of which were within the normal range. In an adjusted analysis, increasing hearing thresholds were associated with lower birth weight and postnatal middle-ear disease but not level of gentamicin exposure. After adjusting for birth weight, there was no difference in hearing threshold between the gentamicin-exposed cohort and healthy controls. CONCLUSIONS: Exposure to a high-dose gentamicin regimen in the neonatal period was not associated with an increase in hearing thresholds in schoolchildren being able to complete audiometry