Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ear, Inner”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources
PubMed1993

[The localization and the function of carbonic anhydrase in the inner ear].

Carbonic anhydrase (CA) is distributed in a wide variety of animal cells and tissues, especially in cells and tissues involved in rapid exchange or transport of protons, bicarbonate, or other ions. Although localization of this enzyme and its physiological roles in the inner ear have been investigated extensively, full clarification has yet to be achieved. We have conducted a histochemical investigation of CA localization in the inner ear of the guinea pig by Hansson's method, with emphasis on improved fixation. The histochemical reaction for CA activity is localized in the outer and inner hair cells of the organ of Corti, Deiters' cells or nerve endings, inner pillar cells, Boettcher's cells, stria vascularis, spiral ligament, vasculo-epithelial zone and spiral ganglion cells. The physiological roles of CA in the inner ear, particularly in relation to the production or absorption of endolymph, are discussed in this report.

Animals↗
PubMed2005

Tbx1 is required for proper neural crest migration and to stabilize spatial patterns during middle and inner ear development.

Tbx1 belongs to the family of T-box containing transcription factors. In humans, TBX1 is implicated in the etiology of the DiGeorge syndrome. Inactivation of the Tbx1 gene in mice produces a variety of malformations including abnormal branching of the heart outflow tract, deficiencies in the branchial arch derivatives, agenesis of pharyngeal glands and abnormal development of the auditory system. We analyze here the middle and inner ear phenotypes of the Tbx1 null mice. The middle ear is strongly affected. Its skeletal components are malformed to varying degrees, some being slightly hypoplastic and others completely absent. However, a seemingly normal-looking tympanic membrane can still be recognized. Middle ear anomalies are associated with other skeletal deficiencies in the branchial arch-derived skeleton. These phenotypes derive from a combination of the failure of the posterior branchial arches to develop and the misrouting of neural crest cells. The inner ears of Tbx1(-/-) animals are hypoplastic. No vestibular or cochlear structures are detectable, but the endolymphatic duct, the cochleovestibular ganglia and residual sensory patches are still identifiable. Molecular analyses revealed a seemingly normal spatial distribution of a variety of patterning markers in the otic vesicles of Tbx1 null mutants at E9.0. However, 1 day later, several of these markers presented altered domains of expression in the otocysts of these mutant embryos, suggesting that Tbx1 is not required for the establishment of spatial patterns in the otocyst, but rather for their maintenance. The inability of the Tbx1(-/-) embryos to keep properly segregated functional domains in the otocyst is likely the cause of the strong inner ear phenotypes observed in these mutants.

Animals↗
PubMed2004

Caspases, the enemy within, and their role in oxidative stress-induced apoptosis of inner ear sensory cells.

This review covers the general roles of members of the cysteine protease family of caspases in the process of apoptosis (programmed cell death) looking at their participation in both the "extrinsic" cell death receptor and the "intrinsic" mitochondrial cell death pathways. It defines the difference between initiator and effector caspases and shows the progression of caspase activations that ends up in the apoptotic cell death and elimination of a damaged cell. The review then presents what is currently know about the participation of caspases in the programmed cell death of inner ear sensory cells during the process of normal development and maturation of the inner ear and their importance in this process as illustrated by the results of caspase-3 gene knockout experiments. The participation of specific caspases and the sequence of their activation in the elimination (apoptosis) of damaged sensory cells from adult inner ears after an injury that generates oxidative stress are reviewed. Both the possibility and the potential efficacy of caspase inhibition with a broad-spectrum pancaspase inhibitor as an interventional therapy to treat and rescue oxidative stress-damaged inner ear sensory cells from apoptosis are presented and discussed.

Adult↗
PubMed1997

[MRI of the regions of the inner ear and cerebellopontine angle using a 3D T2-weighted turbo spin-echo sequence. Comparison with conventional 2D T2-weighted turbo spin-echo sequences and T1-weighted spin-echo sequences].

PURPOSE: To assess the value of a three-dimensional (3D) T2-weighted turbo spin-echo sequence (3D T2-TSE) in comparison to conventional two-dimensional (2D) T2-weighted TSE and unenhanced and enhanced T1-weighted spin-echo sequences (SE) in imaging anatomic structures and pathologic changes of the inner ear and cerebellopontine angle. PATIENTS AND METHODS: The inner ear and cerebellopontine angle were investigated by MRI in three healthy volunteers and 18 patients performing a 2D T2-weighted turbo spin-echo sequence and a 3D T2-TSE in the axial plane. In the patient study, 2D T1-weighted SE sequences both before and after the i.v. injection of gadopentetate dimeglumine in both the axial and coronal plane were performed in addition. RESULTS: Only the 3D T2-TSE enabled an accurate imaging of the anatomic structures. In cases of pathology, the 3D T2-TSE provided additional information to the performed 2D sequences. The combination of the 3D T2-TSE with unenhanced and enhanced 2D T1-weighted SE enabled the most accurate diagnosis in cases of pathology. CONCLUSIONS: Accurate depiction of anatomic structures of the inner ear and cerebellopontine angle could be obtained by 3D T2-TSE only. The most accurate diagnosis in cases of pathology was provided by the combination of the 3D T2-TSE with unenhanced and enhanced 2D T1-weighted spin-echo sequences.

Adult↗
PubMedDate not supplied

Embryogenesis of the inner ear. II. The late differentiation of the mammalian crista ampullaris in vivo and in vitro.

The embryonic development of the crista ampullaris of the CBA/CBA mouse was followed both in organ culture of explanted inner ears of the 16th gestational day and in vivo from the 16th gestational day until the 21st day, an age corresponding to birth. Cytodifferentiation of the sensory epithelium of the crista ampullaris occurs during this period. At partus, there is a rather mature crista with well developed hair cells and 1-2 layers of supporting cells. Innervation and differentiation into type I and type II hair cells have started prior to partus but occur mainly post partum. The in vitro development followed that of the in vivo but with a slight delay, especially concerning the later stages of the in vitro development. At the time corresponding to partus, differentiation of hair cells is almost identical in the two groups but innervation is delayed in the in vitro group of inner ears. Because of the very high reproducibility/stability in vitro and morphologic maturation of both hair cells and gross structure of the crista ampullaris, organ culture of the 16th gestational day inner ear explant is a suitable model in the study of the late embryonic development under normal and pathological conditions.

Animals↗
PubMed2003

Inner ear hearing loss modulates ipsilateral temporal lobe activation by monaural speech stimuli.

We examined cortical activation by speech in patients with moderate inner ear hearing loss using PET to investigate the response of the language network to insufficient speech input. We made two word lists, well-perceived words and poorly-perceived words, and measured rCBF during monaural presentation of these words. Well-perceived words activated bilateral temporal lobes, bilateral inferior frontal gyri (IFG) and left angular gyrus (AG) regardless of the ear stimulated, Poorly-perceived words activated contralateral temporal lobe and bilateral IFG, while little or no activation was observed in the ipsilateral temporal lobe and left AG. Insufficient activation of the temporal lobe ipsilateral to the ear stimulated might correlated with less accurate word comprehension in patients with inner ear hearing loss.

Acoustic Stimulation↗
PubMed1996

Comparative electronmicroscopical investigations on the influences of altered gravity on cytochrome oxidase in the inner ear of fish: a spaceflight study.

The regional metabolic activity in the otolithic sensory epithelia of the inner ear of a cichlid fish (Oreochromis mossambicus) was investigated on light- and electronmicroscopical level using the cytochemical method for detection of cytochrome oxidase activity. In adult animals a characteristic distribution of mitochondria with high enzyme activity was found in sensory and non-sensory cells of otolithic sensory epithelia, which was correlated with regions with a high energy demand. These findings were the basis for studies on the influence of long-term altered gravity conditions in developing larvae: hypogravity (10(-4) g in spaceflight), normal gravity (1 g in a centrifuge in space and 1 g on earth) and hypergravity (3 g in a laboratory centrifuge). Cytochrome oxidase activity was quantified in different parts of the sensory hair cell synapse in the vestibular sensory epithelia utricle and saccule: apical and basal cytoplasm, postsynaptic area of the afferent synapse and presynaptic region of the efferent synapse. Our results show that the energy metabolism of utricle, but not of saccule is decreased after microgravity exposure during the 2nd German Spacelab Mission D-2. However, a general effect of the spaceflight is detectable in both sensory epithelia. Long-term exposure to increased acceleration (3 g) had no effects on cytochrome oxidase activity in inner ear sensory epithelia.

Animals↗
PubMed1991

Development of inner ear vessels. A scanning electron microscopic study.

The development of the inner ear vessels of guinea pigs were studied by SEM. Employing 32- to 55-gestational-day-old guinea pig embryos, corrosion casts of inner ear blood vessels were prepared using Mercox resin and then observed by scanning electron microscopy. Between the 35th and 40th gestational days, the vascular structure of the vestibule was sufficiently developed, but the capillary network in the wall of the cochlea remained immature. Thus, in the guinea pig, the development of the vestibular structure precedes the development of the cochlear vessels. Moreover, at both sites, the density of the embryonic blood vessels was high, and the vessels were believed to transport a large blood flow. From about the 40th day of gestation, the coiled vessels and the capillary network in the lateral wall of the cochlea underwent rapid development, and the vascular structure in both the vestibule and cochlea was nearly complete by the time of birth.

Animals↗
PubMed1990

Speculation into the etiologic role of viruses in the development of Bell's palsy and disorders of inner ear dysfunction: a case history and review of the literature.

It has long been postulated that Bell's palsy and a number of inner ear disorders may have as their basis a common underlying viral etiology. The change from one recognizable inner ear disorder into another is not unusual in the same patient and has been recognized by neurotologists. The case history of a patient who initially presented with an idiopathic facial palsy that years later developed into a spectrum of vestibular dysfunction associated with the clinical stigmata of herpes zoster is discussed. Although difficult to prove, support for this continuum theory is reviewed, taking into account known viral involvement in other cranial nerves and various histopathologic findings from disorders involving the inner ear and facial nerve.

Adult↗
PubMed1994

Case report: prolonged contrast enhancement of the inner ear on magnetic resonance imaging in Ramsay Hunt syndrome.

There have been recent reports of enhancement of the inner ear in acute labyrinthitis on gadolinium enhanced magnetic resonance imaging (MRI). However, none has described persistence of enhancement beyond 6 weeks. We report a case of Ramsay Hunt syndrome with labyrinthitis, sensorineural hearing loss and facial nerve palsy in which marked enhancement of the inner ear structures was observed on MRI 6 months after the onset of symptoms. Enhancement on delayed or repeated imaging after a period of months does not exclude labyrinthitis from the differential diagnosis of the small intracanalicular acoustic neuroma, and care should be taken not to confuse them.

Diagnosis, Differential↗
PubMed2003

TBX1 is required for inner ear morphogenesis.

TBX1 is thought to be a critical gene in the pathogenesis of del22q11/DiGeorge syndrome (DGS). Morphological abnormalities of the external ear and hearing impairment (conductive or sensorineural) affect the majority of patients. Here we show that homozygous mutation of the mouse homolog Tbx1 is associated with severe inner ear defects that prevent the formation of the cochlea and of the vestibulum. Consistent with phenotypic abnormalities, Tbx1 is expressed early in otocyst development in the otic epithelium and in the periotic mesenchyme. Tbx1 loss-of-function blocks inner ear development at early otocyst stage and after neurogenesis. Analysis of chimeras suggests that Tbx1 function is required in the otic epithelium cell autonomously, but abnormalities of the periotic mesenchyme indicate that the pathogenesis of the inner ear phenotype is complex. We propose a model where Tbx1 is required for expansion of a subpopulation of otic epithelial cells, which is required to form the vestibular and auditory organs. Our data suggest that Tbx1 deletion in del22q11 patients may cause not only external and middle ear defects but also sensorineural and vestibular phenotypes observed in these patients.

Animals↗
PubMed2005

Immunosuppressive treatment in bilateral vestibulopathy with inner ear antibodies.

CONCLUSIONS: Although vestibular recovery was observed after steroid treatment, it remains uncertain whether this improvement was spontaneous or due to medication. These data do not allow us to generally recommend corticosteroid treatment in patients with BVF and inner ear antibodies. OBJECTIVE: A retrospective study was performed based on the observation of two patients with suspected autoimmune bilateral vestibular failure (BVF) with normal hearing and antilabyrinthine or nervous tissue-specific serum antibodies who showed vestibular recovery after corticosteroid treatment. MATERIAL AND METHODS: Twelve patients with BVF and serum inner ear antibodies who had received imuunosuppressive treatment with corticosteroids were evaluated in terms of medical history, repetitive caloric irrigation and repetitive determination of inner ear antibodies. BVF was complete in four patients and incomplete in eight. RESULTS: After immunosuppressive therapy, four of the 12 patients showed a moderate recovery of the peak slow-phase velocity of horizontal nystagmus induced by bithermal caloric stimulation, which was only transient in two of them.

Adult↗
PubMed2004

Transcription profiling of inner ears from Pou4f3(ddl/ddl) identifies Gfi1 as a target of the Pou4f3 deafness gene.

Pou4f3 (Brn3.1, Brn3c) is a class IV POU domain transcription factor that has a central function in the development of all hair cells in the human and mouse inner ear sensory epithelia. A mutation of POU4F3 underlies human autosomal dominant non-syndromic progressive hearing loss DFNA15. Through a comparison of inner ear gene expression profiles of E16.5 wild-type and Pou4f3 mutant deaf mice using a high density oligonucleotide microarray, we identified the gene encoding growth factor independence 1 (Gfi1) as a likely in vivo target gene regulated by Pou4f3. To validate this result, we performed semi-quantitative RT-PCR and in situ hybridizations for Gfi1 on wild-type and Pou4f3 mutant mice. Our results demonstrate that a deficiency of Pou4f3 leads to a statistically significant reduction in Gfi1 expression levels and that the dynamics of Gfi1 mRNA abundance closely follow the pattern of expression for Pou4f3. To examine the role of Gfi1 in the pathogenesis of Pou4f3-related deafness, we performed comparative analyses of the embryonic inner ears of Pou4f3 and Gfi1 mouse mutants using immunohistochemistry and scanning electron microscopy. The loss of Gfi1 results in outer hair cell degeneration, which appears comparable to that observed in Pou4f3 mutants. These results identify Gfi1 as the first downstream target of a hair cell specific transcription factor and suggest that outer hair cell degeneration in Pou4f3 mutants is largely or entirely a result of the loss of expression of Gfi1.

Animals↗
PubMed1992

Distribution of the 275 kD hair cell antigen and cell surface specialisations on auditory and vestibular hair bundles in the chicken inner ear.

The 275 kD hair cell antigen (HCA) is a protein that is specifically associated with the apical surface of sensory hair cells in the chick inner ear. A comparative study of the vestibular and auditory organs of the inner ear, using both wholemounts and cryosections double labelled for the HCA and F-actin, reveals that two distinct types of hair cells can be distinguished on the basis of antibody staining in each of the vestibular epithelia. One type of hair cell has the HCA restricted to the base of the stereocilia bundle and is found in the striolae of the maculae and in a large, centrally located region of each ampulla. The other type of hair cell is found in the extrastriolar regions of the maculae and the peripheral regions of the ampullae and has the HCA distributed over the entire surface of the stereocilia bundle. In the basilar papilla, the auditory epithelium of the chick inner ear, the HCA is, as in the striolar regions of the maculae, restricted to the base of the hair bundles. In all sensory epithelia the HCA is also present on the apical, nonstereociliary surface of the hair cells. Ultrastructural examination of the basilar papilla and the striolar and the extrastriolar regions of the lagenar macula after staining with ruthenium red and tannic acid shows that there are four morphologically different types of interstereociliary connectors (oblique tip connectors, horizontal tip connectors, shaft connectors and basal connectors) associated with the hair bundles. Oblique tip connectors and basal connectors are found on hair cells from all regions and have a similar distribution. Horizontal tip connectors are seen only on hair cells in the basilar papilla and the striolar region of the lagenar macula. Shaft connectors extend all the way to the tips of extrastriolar hair cell bundles, but extend only a short way up the bundles of hair cells in the basilar papilla and striolar region of the lagenar macula. Immunogold labelling confirms the results obtained with immunofluorescence microscopy and demonstrates that the distribution of the HCA on the surface of adjacent stereocilia correlates closely with that of the shaft connectors; i.e., immunostaining is observed up to the tips of the extrastriolar hair cell bundles, but is restricted to the lower regions of hair cell bundles in the striolar region and basilar papilla.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1996

Expression of Na+/myo-inositol cotransporter mRNA in the inner ear of the rat.

We have demonstrated the cellular localization of Na+/myo-inositol cotransporter (SMIT) mRNA in the rat inner ear by in situ hybridization. In the cochlea, the most intense SMIT mRNA signals were observed in fibrocytes of the spiral ligament, moderate signals were found in the spiral limbus, inner hair cells and spiral ganglion cells, while the hybridization signals were almost undetectable in the marginal cells of the stria vascularis and outer hair cells. In the vestibular system, moderate hybridization signals were found in the sensory epithelium, fibrocytes and vestibular ganglion cells. These findings suggest that SMIT plays an important role in maintenance of intracellular ionic balance and cell volume in the inner ear, especially in the fibrocytes associated with generation of the ion gradients between the endolymph and perilymph.

Animals↗