Expression of antioxidant enzymes is regulated by transcription factor NF-E2-related factor (Nrf2) and induced by oxidative stress. Reactive oxygen species contribute to the formation of several types of cochlear injuries, including age-related hearing loss and gentamicin ototoxicity. In this study, we examined the roles of Nrf2 in age-related hearing loss and gentamicin ototoxicity by measuring auditory brainstem response thresholds in Nrf2-knockout mice. Although Nrf2-knockout mice maintained normal auditory thresholds at 3 months of age, their hearing ability was significantly more impaired than that of age-matched wild-type mice at 6 and 11 months of age. Additionally, the numbers of hair cells and spiral ganglion cells were remarkably reduced in Nrf2-knockout mice at 11 months of age. To examine the importance of Nrf2 in protecting against gentamicin-induced ototoxicity, 3-day-old mouse organ of Corti explants were cultured with gentamicin. Hair cell loss caused by gentamicin treatment was enhanced in the Nrf2-deficient tissues. Furthermore, the expressions of some Nrf2-target genes were activated by gentamicin treatment in wild-type mice but not in Nrf2-knockout mice. The present findings indicate that Nrf2 protects the inner ear against age-related hearing injuries and gentamicin ototoxicity by up-regulating antioxidant enzymes and detoxifying proteins.

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A large amount of energy produced by active aerobic metabolism is necessary for the cochlea to maintain its function. This makes the cochlea vulnerable to blockade of cochlear blood flow and interruption of the oxygen supply. Although certain forms of human idiopathic sudden sensorineural hearing loss reportedly arise from ischemic injury, the pathological mechanism of cochlear ischemia-reperfusion injury has not been fully elucidated. Recent animal studies have shed light on the mechanisms of cochlear ischemia-reperfusion injury. It will help in the understanding of the pathology of cochlear ischemia-reperfusion injury to classify this injury into ischemic injury and reperfusion injury. Excitotoxicity, mainly observed during the ischemic period, aggravates the injury of primary auditory neurons. On the other hand, oxidative damage induced by hydroxyl radicals and nitric oxide enhances cochlear reperfusion injury. This article briefly summarizes the generation mechanisms of cochlear ischemia-reperfusion injury and potential therapeutic targets that could be developed for the effective management of this injury type.

The modified COP-NLR score is a useful prognostic marker in patients with advanced head and neck cancer.

Objective The Geriatric Nutritional Risk Index (GNRI) is a simple and well‐established nutritional assessment tool and is a significant prognostic factor in various cancers. However, the role of the GNRI in predicting clinical outcomes in patients with advanced head and neck cancer (AHNC) has not been investigated. The aim of the present study was to examine the association between the GNRI and prognosis in patients with AHNC. Study Design Retrospective cohort study. Methods Data collected between 2002 and 2013 from Tsukuba University Hospital were reviewed. The GNRI was calculated according to the equation, 1.489 × serum albumin (g/l) + 41.7 × (body weight/ideal body weight). Characteristics and prognosis were compared among three risk groups: high (GNRI <82); intermediate (GNRI 82–98); and normal (GNRI >98). The primary endpoint was overall survival. Results A total of 248 AHNC patients were enrolled, among whom 134 (54%) exhibited no nutritional risk, 53 (21%) had an intermediate risk for malnutrition, and 61 (25%) exhibited a high risk for malnutrition. Three‐year survival rates according to the three‐group GNRI scores for normal, intermediate, and high risk were 76.6%, 56.3%, and 19.5%, respectively. As the three‐group GNRI score increased, the risk for mortality significantly increased (adjusted hazard ratio [HR] for intermediate to normal, 1.73 [95% CI, 1.02–2.92]; adjusted HR for high to normal, 4.31 [95% CI, 2.71–6.84]). Conclusions The GNRI could be considered a useful prognostic factor in patients with AHNC. Level of Evidence 4 Laryngoscope, 131:E151–E156, 2021