Search results for "inner ear"
showing 10 items of 58 documents
A core cochlear phenotype in USH1 mouse mutants implicates fibrous links of the hair bundle in its cohesion, orientation and differential growth
2008
The planar polarity and staircase-like pattern of the hair bundle are essential to the mechanoelectrical transduction function of inner ear sensory cells. Mutations in genes encoding myosin VIIa, harmonin, cadherin 23,protocadherin 15 or sans cause Usher syndrome type I (USH1, characterized by congenital deafness, vestibular dysfunction and retinitis pigmentosa leading to blindness) in humans and hair bundle disorganization in mice. Whether the USH1 proteins are involved in common hair bundle morphogenetic processes is unknown. Here, we show that mouse models for the five USH1 genetic forms share hair bundle morphological defects. Hair bundle fragmentation and misorientation (25-52° mean ki…
Changes in the Three Dimensional Structure of Synaptic Ribbons in the Pineal Gland of the Guinea-Pig Caused by Constant Light
1997
Synaptic bodies (SBs) are dynamic synaptic organelles of afferent synapses of the retina, inner ear, lateral line organ and pineal gland in vertebrates. When investigated in a transmission electron microscope, their electron-dense rod-like, round or irregular profiles are surrounded by electron-lucent vesicles. The three-dimensional structure of pineal SBs is not precisely known. Pineal glands of two guinea-pigs (one kept under an LD cycle of 12:12 h; one kept in constant light for 8 weeks) were investigated. SBs were reconstructed in three dimensions to visualise morphological changes in constant light. Transmission electron microscope micrographs from up to 18 serial sections with a known…
Development and evolution of inner ear sensory epithelia and their innervation
2002
The development and evolution of the inner ear sensory patches and their innervation is reviewed. Recent molecular developmental data suggest that development of these sensory patches is a developmental recapitulation of the evolutionary history. These data suggest that the ear generates multiple, functionally diverse sensory epithelia by dividing a single sensory primordium. Those epithelia will establish distinct identities through the overlapping expression of genes of which only a few are currently known. One of these distinctions is the unique pattern of hair cell polarity. A hypothesis is presented on how the hair cell polarity may relate to the progressive segregation of the six sens…
A suggested role for secondary flow in the stimulation of the cochlear hair cell
1985
The mammalian Corti organ and the reptilian basilar papilla are structures with a curved surface, which vibrate in a fluid medium. This paper is concerned with the role played by the geometric shape of these organs in cochlear hydrodynamics. In association with vibrating structures such as these organs, it can be expected that a stationary current will be initiated due to a nonlinear phenomenon in the boundary layer known as secondary flow. This phenomenon may explain the source of the mechanical nonlinearity in the cochlea.
Intralabyrinthine neurinoma: Management, exeresis and auditory restoration with cochlear implant
2021
Abstract Background and objective Vestibular schwannoma is a benign tumour that originates in the eighth cranial nerve. It is termed intralabyrinthine schwannoma (ILS) when it develops in the inner ear, this being a rare origin. We present our experience in the management of three patients with ILS. Materials and methods The results of tumour excision and cochlear implantation were evaluated in three patients with ILS: two intracochlear schwannomas (ICS) and one intravestibular schwannoma (IVS). Results Prior to surgery, all patients presented progressive sensorineural hearing loss and tinnitus. Complete tumour resection and cochlear implantation was possible in all patients, with favourabl…
Vitamin A deficiency increases noise susceptibility in guinea pigs.
1990
The effect of vitamin A deficiency in guinea pigs on noise-induced temporary threshold shift (TTS) was evaluated after short (15 min) acoustic overstimulation with a moderate (90 dB) broad-band white noise. Some guinea pigs were fed ad libitum a purified diet deficient in vitamin A (VAD group) until biochemical signs of deficiency occurred. A second, control group (VA group) received the same diet as well as 100 IU vitamin A daily by pharyngeal tube. Cochlear potentials were recorded by special computerized equipment using implanted electrodes. Before acoustic stimulation, a baseline value was determined with a test stimulus [90 dBA (A-filter according to usual DIN instructions)] correspond…
Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.
2008
Objectives: Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Study Design: Prospective animal study in guinea pigs. Methods: Over a period of 7 days, male guinea pigs were supplied with minimum (…
Interactions in the network of Usher syndrome type 1 proteins
2004
International audience; Defects in myosin VIIa, harmonin (a PDZ domain protein), cadherin 23, protocadherin 15 and sans (a putative scaffolding protein), underlie five forms of Usher syndrome type I (USH1). Mouse mutants for all these proteins exhibit disorganization of their hair bundle, which is the mechanotransduction receptive structure of the inner ear sensory cells, the cochlear and vestibular hair cells. We have previously demonstrated that harmonin interacts with cadherin 23 and myosin VIIa. Here we address the extent of interactions between the five known USH1 proteins. We establish the previously suggested sans-harmonin interaction and find that sans also binds to myosin VIIa. We …
Use of Super Paramagnetic Iron Oxide Nanoparticles as Drug Carriers in Brain and Ear: State of the Art and Challenges
2021
International audience; Drug delivery and distribution in the central nervous system (CNS) and the inner ear represent a challenge for the medical and scientific world, especially because of the blood–brain and the blood–perilymph barriers. Solutions are being studied to circumvent or to facilitate drug diffusion across these structures. Using superparamagnetic iron oxide nanoparticles (SPIONs), which can be coated to change their properties and ensure biocompatibility, represents a promising tool as a drug carrier. They can act as nanocarriers and can be driven with precision by magnetic forces. The aim of this study was to systematically review the use of SPIONs in the CNS and the inner e…
Intratympanic gentamicin: a 1-day protocol treatment for unilateral Meniere's disease
2006
Abstract Purpose The objective of this study was to assess the usefulness of low-dose intratympanic gentamicin administration in patients with Meniere's disease (MD). Materials and Methods We carried out a retrospective review of the charts of 55 patients with definite MD in accordance with the AAO-HNS (American Academy of Otolaryngology–Head and Neck Surgery) Diagnostic Scale who were treated at Gruppo Otologico (Piacenza, Rome, Italy). The treatment protocol consisted of 3 intratympanic injections of gentamicin at a 12-hour interval between each administration. Results Results were resumed in accordance with AAO-HNS criteria and showed complete control of vertigo spells in 60% (class A), …