Unit:
Faculty of MedicineLibrary of the School of Health Sciences
Author:
Iliadou Eleftheria
Dissertation committee:
Αθανάσιος Μπίμπας, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Κωνσταντίνος Παστιάδης, Καθηγητής, Σχολή Μουσικών Σπουδών, ΑΠΘ
Christopher J. Plack, Καθηγητής, Division of Psychology, Communication and Human Neuroscience, University of Manchester και Department of Psychology, Lancaster University
Αριστείδης Ηλιόπουλος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Χρήστος Κόνσουλας, Αναπληρωτής Καθηγητής , Ιατρική Σχολή, ΕΚΠΑ
Colleen Le Prell, Καθηγήτρια, Department Head, Speech, Language, and Hearing, University of Texas
Αθανάσιος Τζουνόπολος, Καθηγητής, Pittsburgh Hearing Research Center, University of Pittsburgh and Carnegie Mellon University
Original Title:
Music induced hearing loss: Development of a temporary threshold shift paradigm and role of prestin as a biomarker.
Translated title:
Music induced hearing loss: Development of a temporary threshold shift paradigm and role of prestin as a biomarker.
Summary:
This is the dissertation of the PhD project entitled “Music Induced Hearing Loss: Development of a temporary threshold shift paradigm and role of prestin as a biomarker.” It consists of:
1. A general part (Chapter I, titled “Introduction – General considerations”)
2. A specific part (Chapters II-VII)
This PhD project aimed to determine the significance of a newly proposed biomarker, blood prestin, in noise-induced hearing loss (NIHL). Prestin is the 5th member of an 11-member membrane anion-transporter superfamily (solute carrier family 26 or SLC26). In the cochlea, prestin plays a crucial role in the electromotility of outer hair cells. It was recently shown that free serum prestin can be detected in the blood circulation of rodents and humans by means of Enzyme-linked Immunosorbent Assay (ELISA). This permeation of prestin to blood circulation is hypothesized to occur either directly through the blood-labyrinthine barrier or via engulfment by phagosomes.
The principal motivation for conducting this study was the determination of the role of blood prestin in NIHL and is based on previous findings that supported that blood prestin levels may be associated with the dynamic changes that occur in the cochlea after exposure to hazardous levels of noise. Blood prestin levels have shown variation after a single loud exposure, in rodents; in Parham et al. (2019), serum prestin levels increased immediately after 2 hours exposure to high-level noise and then decreased to near or below baseline at 14 days. In addition to these acute changes, in a recent human study by Parker et al. (2022), blood prestin levels of adults with normal hearing also showed weak negative correlation with average daily noise exposure levels.
1. To investigate changes in blood prestin levels in temporary NIHL in humans, it was decided to measure blood prestin levels in adults with normal hearing before and after exposure to high levels of music.
Prior to this, it was essential to:
- Map the current knowledge about blood prestin in animals and humans, and standardise the process of collecting blood samples and measuring prestin by means of ELISA, as well as assessing their test-retest and intra-rater reliability.
Given the limited existing knowledge on prestin blood levels in humans, a scoping review of relevant literature and an observational study on adults with normal hearing were initially conducted. This phase of the project aimed to identify regular blood prestin levels in individuals with normal hearing and their relationships with factors like age, sex, and chronic noise exposure. We showed that serum prestin levels did not differ significantly across time of day, and that our test-retest reliability between duplicates of the same sample was excellent. Neither lifetime noise exposure, age, nor sex correlated with serum prestin levels.
2. Develop a music exposure paradigm to safely induce Temporary Threshold Shift (TTS).
After a relevant scoping review on experimental studies on NIHL, for practical and ethical reasons, it was decided to focus on temporary rather than permanent hearing loss. A time-efficient music exposure paradigm, that was shown to induce substantial TTS and distortion product otoacoustic emission (DPOAE) amplitude shifts, without evidence of permanent hearing consequences, was developed. Seventeen participants with normal hearing were included in this phase of the study. All but two participants presented clinically significant TTS or decrease in their DP amplitude in at least one frequency. No participant showed any permanent threshold shift.
Once our methods were standardized and the reliability and safety of our paradigm were deemed satisfactory, according to the results of the abovementioned pilot study, I proceeded to assess blood prestin level in individuals with normal hearing before and after their exposure to our music paradigm. Fourteen adults with normal hearing were included in this stage. All participants presented TTS or a decrease in DP amplitude in at least one frequency after music exposure. Mean serum prestin level progressively increased following music exposure, reaching a maximum at 2 h and returned to pre-exposure level by 1 week. Our findings show that blood prestin level may change after exposure to high levels of music and suggest that the role of serum prestin level as a proxy marker for temporary cochlear dysfunction after exposure to hazardous levels of noise should be further explored.
Main subject category:
Health Sciences
Keywords:
Hearing, Music, Noise-induced hearing loss, Music-induced hearing loss, Audiometry, Biomarkers, Prestin
Number of references:
181
