Exposure to blast shock waves via the ear canal induces deficits in vestibular afferent function in rats.

The ears are air-filled structures that are directly impacted during blast exposure. In addition to hearing loss and tinnitus, blast victims often complain of vertigo, dizziness and unsteady posture, suggesting that blast exposure induces damage to the vestibular end organs in the inner ear. However, the underlying mechanisms remain to be elucidated.

Txn2 haplodeficiency does not affect cochlear antioxidant defenses or accelerate the progression of cochlear cell loss or hearing loss across the lifespan.

Thioredoxin 2 (TXN2) is a small redox protein found in nearly all organisms. As a mitochondrial member of the thioredoxin antioxidant defense system, TXN2 interacts with peroxiredoxin 3 (PRDX3) to remove hydrogen peroxide. Accordingly, TXN2 is thought to play an important role in maintaining the appropriate mitochondrial redox environment and protecting the mitochondrial components against oxidative stress.

[Inner hair cells loss by carboplatin and the changes of cochlear compound action potential in chinchillas].

To measure the cochlear compound action potential (CAP) and the densities of hair cells (HCs) along the whole length of the basilar membrane (BM) in adult chinchillas. And to investigate the relationship between the severity of inner hair cells (IHCs) loss and the changes of CAP by using carboplatin-cochlear lesion model. Totally 18 chinchillas were recruited after ontological evaluation.

Activation of GABA receptors results in excitatory modulation of calyx terminals in rat semicircular canal cristae.

Previous studies have found GABA in vestibular end organs. However, existence of GABA receptors or possible GABAergic effects on vestibular nerve afferents has not been investigated. The current study was conducted to determine whether activation of GABA receptors affects calyx afferent terminals in the central region of the cristae of semicircular canals.

Gap Detection Deficits in Chinchillas with Selective Carboplatin-Induced Inner Hair Cell Loss.

Temporal resolution is essential for processing complex auditory information such as speech. In hearing impaired persons, temporal resolution, often assessed by detection of brief gaps in continuous sound stimuli, is typically poorer than in individuals with normal hearing. At low stimulus presentation levels, hearing impaired individuals perform poorly but the deficits are greatly reduced when the sensation level of the stimuli are adjusted to match their normal hearing peers.

Transcript Profiles of Stria Vascularis in Models of Waardenburg Syndrome.

Background: Waardenburg syndrome is an uncommon genetic condition characterized by at least some degree of congenital hearing loss and pigmentation deficiencies. However, the genetic pathway affecting the development of stria vascularis is not fully illustrated.

Methods: The transcript profile of stria vascularis of Waardenburg syndrome was studied using Mitf-M mutant pig and mice models.

Using auditory reaction time to measure loudness growth in rats.

Previous studies have demonstrated that auditory reaction time (RT) is a reliable surrogate of loudness perception in humans. Reaction time-intensity (RT-I) functions faithfully recapitulate equal loudness contours in humans while being easier to obtain than equal loudness judgments, especially in animals. In humans, loudness estimation not only depends on sound intensity, but on a variety of other acoustic factors.

Blast-induced hearing loss suppresses hippocampal neurogenesis and disrupts long term spatial memory.

Acoustic information transduced by cochlear hair cells is continuously relayed from the auditory pathway to other sensory, motor, emotional and cognitive centers in the central nervous system. Human epidemiological studies have suggested that hearing loss is a risk factor for dementia and cognitive decline, but the mechanisms contributing to these memory and cognitive impairments are poorly understood. To explore these issues in a controlled experimental setting, we exposed adult rats to a series of intense blast wave exposures that significantly reduced the neural output of the cochlea.

Functional Neuroanatomy of Salicylate- and Noise-Induced Tinnitus and Hyperacusis.

Tinnitus and hyperacusis are debilitating conditions often associated with aging or exposure to intense noise or ototoxic drugs. One of the most reliable methods of inducing tinnitus is with high doses of sodium salicylate, the active ingredient in aspirin. High doses of salicylate have been widely used to investigate the functional neuroanatomy of tinnitus and hyperacusis.

Involvement of Cholesterol Metabolic Pathways in Recovery from Noise-Induced Hearing Loss.

The objective of this study was to explore the molecular mechanisms of acute noise-induced hearing loss and recovery of steady-state noise-induced hearing loss using miniature pigs. We used miniature pigs exposed to white noise at 120 dB (A) as a model. Auditory brainstem response (ABR) measurements were made before noise exposure, 1 day and 7 days after noise exposure.

Efferent synaptic transmission at the vestibular type II hair cell synapse.

In the vestibular peripheral organs, type I and type II hair cells (HCs) transmit incoming signals via glutamatergic quantal transmission onto afferent nerve fibers. Additionally, type I HCs transmit via "non-quantal" transmission to calyx afferent fibers, by accumulation of glutamate and potassium in the synaptic cleft. Vestibular efferent inputs originating in the brainstem contact type II HCs and vestibular afferents.

2-Hydroxypropyl-β-cyclodextrin Ototoxicity in Adult Rats: Rapid Onset and Massive Destruction of Both Inner and Outer Hair Cells Above a Critical Dose.

2-Hydroxypropyl-β-cyclodextrin (HPβCD), a cholesterol chelator, is being used to treat diseases associated with abnormal cholesterol metabolism such as Niemann-Pick C1 (NPC1). However, the high doses of HPβCD needed to slow disease progression may cause hearing loss. Previous studies in mice have suggested that HPβCD ototoxicity results from selective outer hair cell (OHC) damage.

An Age-Related Hearing Protection Locus on Chromosome 16 of BXD Strain Mice.

Inbred mouse models are widely used to study age-related hearing loss (AHL). Many genes associated with AHL have been mapped in a variety of strains. However, little is known about gene variants that have the converse function-protective genes that confer strong resistance to hearing loss.

Interaction of auditory and pain pathways: Effects of stimulus intensity, hearing loss and opioid signaling.

Moderate intensity sounds can reduce pain sensitivity (i.e., audio-analgesia) whereas intense sounds can induce aural pain, evidence of multisensory interaction between auditory and pain pathways.

Role of Endoplasmic Reticulum Stress in Otitis Media.

Endoplasmic reticulum (ER) stress occurs in many inflammatory responses. Here, we investigated the role of ER stress and its associated apoptosis in otitis media (OM) to elucidate the mechanisms of OM and the signaling crosstalk between ER stress and other cell damage pathways, including inflammatory cytokines and apoptosis. We examined the expression of inflammatory cytokine- and ER stress-related genes by qRT-PCR, Western blotting, and immunohistochemistry (IHC) in the middle ear of C57BL/6J mice after challenge with peptidoglycan polysaccharide (PGPS), an agent inducing OM.

Dietary Restriction for The Treatment of Meniere's Disease.

Meniere's disease (MD) is an idiopathic inner ear disorder characterized by spontaneous recurrent vertigo, fluctuating sensorineural hearing loss (SNHL), aural fullness and tinnitus. Endolymphatic hydrops (EH) of the inner ear is currently considered the pathophysiological mechanisms that underlies typical symptoms of MD. MD diagnosis is based on the criteria of the Baràny Society.

How low must you go? Effects of low-level noise on cochlear neural response.

Prolonged exposure to low-level noise has often been used scientifically as well as clinically to induce neuroplastic changes within the central auditory pathway in order to reduce central gain, suppress tinnitus and hyperacusis, and modulate different features of central auditory processing. A fundamental assumption underling these studies is that the noise exposure levels are so low that they have no effect on the neural output of the cochlea. Therefore, functional changes occurring in the central auditory pathway must be the results of central rather than peripheral changes.

A novel intracochlear injection method for rapid drug delivery to vestibular end organs.

Background: Injection into the inner ear through the round window (RW) or a cochleostomy is a reliable method for delivering drugs or viruses to the cochlea. This method has been less effective for fast deliveries to vestibular end organs.

New Method: We describe a novel approach for rapid delivery of drugs to the vestibular end organ via the oval window (OW) and scala vestibuli in 1-3 month old C57BL/6 mice.

Therapeutic role of intravenous glycerol for Meniere's disease. Preliminary results.

Purpose: Osmotic diuretics such as glycerol are used for diagnostic purposes in patients with a suspect of Meniere's disease (MD). Scientific evidence in the animal model and in humans has shown that glycerol can induce a reduction in endolymphatic hydrops; however, its use for therapeutic purposes in MD has never been reported. The aim of this study was to evaluate the effectiveness on symptom control of intravenous glycerol in a sample of patients with definite unilateral MD not responsive to dietary restrictions.

Hyperacusis in Children with Attention Deficit Hyperactivity Disorder: A Preliminary Study.

The association between hyperacusis and developmental disorders such as autism spectrum disorders has been extensively reported in the literature; however, the specific prevalence of hyperacusis in attention deficit hyperactivity disorder (ADHD) has never been investigated. In this preliminary study, we evaluated the presence of hyperacusis in a small sample of children affected by ADHD compared to a control group of healthy children. Thirty normal hearing children with a diagnosis of ADHD and 30 children matched for sex and age were enrolled in the study.

Dynamic Changes in Synaptic Plasticity Genes in Ipsilateral and Contralateral Inferior Colliculus Following Unilateral Noise-induced Hearing Loss.

Unilateral noise-induced hearing loss reduces the input to the central auditory pathway disrupting the excitatory and inhibitory inputs to the inferior colliculus (IC), an important binaural processing center. Little is known about the compensatory synaptic changes that occur in the IC as a consequence of unilateral noise-induced hearing loss. To address this issue, Sprague-Dawley rats underwent unilateral noise exposure resulting in severe unilateral hearing loss.

Evolution of the Systems Pharmacokinetics-Pharmacodynamics Model for Antibody-Drug Conjugates to Characterize Tumor Heterogeneity and Bystander Effect.

The objective of this work was to develop a systems pharmacokinetics-pharmacodynamics (PK-PD) model that can characterize in vivo bystander effect of antibody-drug conjugate (ADC) in a heterogeneous tumor. To accomplish this goal, a coculture xenograft tumor with 50% GFP-MCF7 (HER2-low) and 50% N87 (HER2-high) cells was developed. The relative composition of a heterogeneous tumor for each cell type was experimentally determined by immunohistochemistry analysis.

Low-grade albuminuria is associated with hearing loss in non-diabetic US males: A cross-sectional analysis of 1999-2004 national health and nutrition examination survey.

High levels of albuminuria have been demonstrated to associate with hearing loss in non-diabetic people, while the clinical impact of low-grade albuminuria has attracted less attention. This cross-sectional population-based study aimed to examine whether hearing loss in non-diabetic United States (US) adults is independently associated with low-grade albuminuria or reduced estimated glomeruli filtration rate (eGFR).A total of 2518 participants aged 20 to 69 years were selected from the US National Health and Nutritional Examination Survey database.