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Otology
Published in Adnan Darr, Karan Jolly, Jameel Muzaffar, ENT Vivas, 2023
Jameel Muzaffar, Chloe Swords, Adnan Darr, Karan Jolly, Manohar Bance, Sanjiv Bhimrao
Background: ? Atrophy of stria vascularis (SV)? Loss of sensory hair cells? Loss of neural tissue? See Table 3.2Age-related hearing loss (typically affects basal turn IHCs first)Clinical diagnosis based on history with no other pathology to account for loss of hearingSchuknecht classification not really supported by animal or latest data K Steel: Presbyacusis presents with metabolic, neural, and/or sensory phenotypes
Genomics and Hearing Loss: Toward a New Standard of Care?
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
Gap junctions: The stria vascularis is a highly-specialized tissue producing the endolymph, which bathes the inner and outer hair cells and is crucial for the auditory sensory transduction. The endo-lymph has a high concentration of potassium, a low concentration of sodium and a high positive endocochlear potential. Numerous ions channels, pumps, and gap junctions are responsible for these gradients. The network of gap junctions, whose proteins are encoded by GJB2 and GJB6 (Gap Junction Protein Beta-2 and Beta-6, respectively) among others, facilitates ion transport between cells. Mutations in GJB2, coding for the connexin 26 protein, are the cause of up to 50% of cases of severe-to-profound autosomal recessive nonsyndromic hearing loss in Caucasian populations. These mutations are, however, less prevalent in some other parts of the world, accounting for a maximum of 15–20% of cases of childhood hearing loss in northern Europeans populations (Hutchin et al., 2005), while being extremely rare among individuals of African descent (Rudman et al., 2017). More than 330 different mutations have been identified in GJB2. Among them, the 35delG mutation is the most frequent pathogenic variant in the majority of Caucasian populations and may account for up to 70% of all GJB2 mutations. GJB2 can also cause autosomal dominant nonsyndromic hearing loss. Another gap junction protein, commonly involved in nonsyndromic hearing loss is GJB6, which codes for connexin 30, and resides in close proximity to GJB2 in the DFNB1 locus.
Anatomy
Published in Stanley A. Gelfand, Hearing, 2017
The stria vascularis contains a rich network of capillaries, and is attached to the spiral ligament on the lateral wall of the scala media. Structurally, the stria vascularis is composed of three layers having characteristic cell types (e.g., Slepecky, 1996). The hexagonal marginal cells face into the scala media. Next are irregular intermediate cells, which have projections into the marginal layer. Finally, there are rather flat basal cells, which are in contact with the spiral ligament. The stria vascularis maintains the electrochemical characteristics of the endolymph, and in particular is viewed as the source of its high concentration of potassium as well as the endocochlear potential discussed in Chapter 4 (see Wangemann and Schacht [1996] for an in-depth discussion).
MATE1 expression in the cochlea and its potential involvement in cisplatin cellular uptake and ototoxicity
Published in Acta Oto-Laryngologica, 2023
Sofia Waissbluth, Agustín D. Martínez, Cindel Figueroa-Cares, Helmuth A. Sánchez, Juan C. Maass
P5 to P7 animals were sacrificed by decapitation (n = 20 cochleae). Both cochleae were obtained by skull dissection and brain removal. Both inner ears located in the temporal bone were isolated, and cochleae were delicately extracted. The dissection was performed using a modified bath solution made with (in mM) 138 NaCl, 5 KCl, 6 Glucose and 10 HEPES, pH7.4. and previously filtered and stored at 4 °C. Briefly, the bony tissue is separated from the membranous labyrinth. Next, the tissue is fixed in the basal region and the membrane labyrinth is extended radially out and split from the central modiolus. Then, the sensory epithelium is separated from the stria vascularis and spiral ligament, and finally transferred to a coverslip previously treated with Geltrex (Gibco A1569601, Life Technologies). In some experiments, the stria vascularis was maintained. Once that tissue is attached to the substrate, the coverslip is covered with culture medium (Dulbecco’s Modified Eagle Medium, containing ampicillin (10 μg/ml) and supplemented with 5% FBS and 5% horse serum) and incubated for 24 h at 37 °C with 5% CO2 and 95% humidity. During imaging experiments, cultures were exposed to the same modified bath solution used during dissection.
Norrie disease with a spontaneously shrinking choroid plexus abnormality: a case report
Published in Ophthalmic Genetics, 2021
Subhi Talal Younes, James Mason Shiflett, Kristin Weaver, Andrew Smith, Betty Herrington, Charlotte Taylor, Kartik Reddy
Norrie disease is a member of the so-called NDP-related retinopathies (1). This class of genetic disorders includes persistent fetal vasculature, X-linked familial exudative vitreoretinopathy, NDP-related retinopathy of prematurity, and Coats Disease. These disorders are united by the common feature of impaired retinal vascular development, in particular, failed branching of the most distal vessels (2). Subsequent necrosis and inflammation lead to disorganized, dense, fibrovascular masses that form behind the retina. As this gliotic mass accumulates, it leads to worsening retinal detachment and, ultimately, complete blindness (3). The derangements of Norrie disease are not limited to the eye, as several different extra-ocular manifestations have been described (4). Most commonly, impaired maintenance of the stria vascularis in the cochlea leads to progressive sensorineural hearing loss later in life (5). Neurologically, intellectual disability (4) and seizure disorders can accompany the syndrome (6). Peripheral vascular disease manifesting as peripheral venous stasis ulcers and erectile dysfunction has also been described (4,7).
Preparation, characterization, and in vitro/vivo evaluation of dexamethasone/poly(ε-caprolactone)-based electrode coatings for cochlear implants
Published in Drug Delivery, 2021
Yanjing Luo, Anning Chen, Muqing Xu, Dongxiu Chen, Jie Tang, Dong Ma, Hongzheng Zhang
However, it has been reported that patients are likely to lose residual hearing at low frequencies within a few months after cochlear implantation (Jia et al., 2016). Two factors are considered to be important contributors to this residual hearing loss: (1) inflammatory responses caused by mechanical trauma during the implantation process, which can lead to cochlear fibrosis, and (2) fibrosis and new bone formation in the cochlea, which can increase electrode impedance, thus compromising the survival of auditory hair cells (HCs) and neurons (Fayad et al., 2009; Bas et al., 2012; Jia et al., 2013; Ceschi et al., 2014; Bas et al., 2017; Eftekhari et al., 2020; Kather et al., 2021). A possibility of damage to the stria vascularis (SV) has been previously reported, revealing a significant correlation between the residual hearing loss and blood vessel density in the SV (Tanaka et al., 2014). Therefore, to preserve residual hearing and avoid the obstruction of re-implantation, it is necessary to suppress the inflammatory response and prevent cochlear fibrosis after surgery.