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At least 217 records · Page 12Linked to original sources
PubMed2001

Isolation and purification of guinea pig inner ear antigens by preparative polyacrylamide gel electrophoresis.

OBJECTIVE: To isolate and purify the subcomponents of guinea pig inner ear antigens for further study on the autoimmunity of the inner ear. METHODS: Inner ear tissues were homogenized in phosphate buffered saline containing 0.1% SDS, and then frozen and defrosted repeatedly to extract inner ear antigens. Preparative polyacrylamide gel electrophoresis was used to separate the subcomponents of inner ear antigens. Following electrophoresis, the protein bands were localized by rapid staining and destaining. RESULTS: The major protein bands were clearly distinct when 3 mg of crude inner ear antigens was loaded, and the three major subcomponents (31, 42-45 and 60 kD proteins) accounted for about 25.99%, 21.91% and 21.10%, respectively. CONCLUSION: Preparative polyacrylamide gel electrophoresis can be used to purify the major subcomponents of inner ear antigens.

Animals↗
PubMed1995

Immunohistochemical localization of neurocalcin in the rat inner ear.

Localization in the rat inner ear of neurocalcin, a three EF-hand calcium-binding protein, was examined immunohistochemically. Neurocalcin-like immunoreactivity was restricted to neurons in neuroepithelial receptor organs, while hair cells and supporting cells showed no such immunoreactivity. In the organ of Corti, both afferent and efferent nerve terminals, which formed synapses on both inner and outer hair cells, showed distinct immunoreactions. Spiral ganglion neurons and cochlear nerves were immunopositive. In the cristae ampullaris, macula utriculi and macula sacculi, afferent nerve terminals forming nerve calices or terminal boutons were strongly immunopositive. Efferent nerve terminals making synapses either on nerve calices or on hair cells showed an intense immunoreactivity. Vestibular ganglion neurons were strongly immunopositive. In electron microscopy, immunoreaction products were diffuse in the cytoplasm of ganglion neurons and nerve terminals. Neurocalcin-like immunoreactivity occurred in association with microtubules, outer mitochondrial membranes, synaptic vesicles and synaptic membranes. It is thus likely that neurocalcin is involved in neural functions in each type of afferent and efferent transmission in the inner ear.

Animals↗
PubMed1998

[Determination of IL-6 in serum and perilymph during inner ear immune response].

During secondary inner ear immune responses against keyhole limpet hemocyanin (KLH), to understand the change of interleukin-6 (IL-6) levels in perilymph and serum, IL-6 levels in perilymph and serum were investigated using an immunoassay. No IL-6 levels were detectable at Day 0 in perilymph. The earliest perilymph IL-6 levels were observed after 6 h, peaking at 24 h, and then decreasing gradually. IL-6 level remnants were detected at 7 days in perilymph. In contrast, during this observation period, low IL-6 levels were only detectable in perilymph from control ears, disappearing after 72 h. IL-6 levels don't change in serum. Previous study has identified the endolymphatic sac (ES) lags behind the earlier appearance of intercellular adhesion molecule-1 (ICAM-1) in the spiral modiolar vein and spiral ligament during immune response. The present study not only provides further support for the existence of an inner ear immune response which is regulated by cytokines, but also supports that cytokines controlling expression of adhesion molecules are released probably by cells which located out of ES.

Adjuvants, Immunologic↗
PubMedDate not supplied

Alcohol and ultrastructural changes in the developing inner ear. An in vitro study.

Inner ear explants from the CBA/CBA mouse were used in an organ culture system. The explants were cultured from the 16th gestational day until one day post partum. They were exposed to 1.5% or 3% ethanol in organ culture medium in order to determine any possible toxic effects upon the differentiating sensory structures of the sensory epithelium of the inner ear, that could be correlated to fetal alcohol syndrome. The higher concentration of ethanol caused a general and possibly unspecific destruction of the sensory epithelium, while the lower concentration caused characteristic changes including intracellular edema or vacuolization, especially confined to hair cells. Pathologic changes seemed dose-related but not time-related.

Animals↗
PubMed1999

Math1: an essential gene for the generation of inner ear hair cells.

The mammalian inner ear contains the cochlea and vestibular organs, which are responsible for hearing and balance, respectively. The epithelia of these sensory organs contain hair cells that function as mechanoreceptors to transduce sound and head motion. The molecular mechanisms underlying hair cell development and differentiation are poorly understood. Math1, a mouse homolog of the Drosophila proneural gene atonal, is expressed in inner ear sensory epithelia. Embryonic Math1-null mice failed to generate cochlear and vestibular hair cells. This gene is thus required for the genesis of hair cells.

Animals↗
PubMed1976

[The activity and capacity of the inner ear (author's transl)].

The inner ear is an energy converter and a biochemical amplifier. The normal function of the stria vascularis and the organ of Corti is bound exclusively to the respiratory metabolism. Some but not all species are equiped by a glycolytic reserve metabolism for preservation of the sensory cells, as could be improved in amplitude-time-curves of cochlea microphonics in hypoxic conditiones. A promising therapy of inner ear disturbances following short timed oxygen deficiency depends on the moment of the treatment.

Animals↗
PubMed2004

Immune-mediated inner ear disease: 10-year experience.

BACKGROUND: Autoimmune inner ear disease (AIED) was first described in 1979 and the disease has become more widely recognized over the last decade. Limited information is available regarding clinical features of the disease, disease course, and response to treatment. OBJECTIVE: To analyze data from 42 patients with documented immune mediated inner ear disease to further define this syndrome. METHODS: A retrospective chart review was conducted on all patients considered to have AIED by the Otolaryngology division physicians and on all patients positive for antibody testing to inner ear antigens from 1990 to 1999. Patients who were antibody positive with a clinical diagnosis of AIED were included in this review. RESULTS: Patients with AIED presented with rapidly progressive, frequently bilateral (79%), often fluctuating sensironeural hearing loss. Mean age at presentation was 50 years (22-80) with no gender predilection. Tinnitus (83%), vestibular complaints (79%), and Menieres (50%) were common concomitant symptoms along with hearing loss. Seven of 42 (17%) of the patients had evidence for other systemic autoimmune disorders. In 4 of the patients the onset of vestibuloauditory complaints preceded the diagnosis of autoimmune disorder. Thirty-three of 42 demonstrated antibodies to inner ear antigens but other autoantibodies were infrequent except in patients with systemic autoimmune disorders. Twenty-three of 33 (70%) of patients treated with corticosteroids improved clinically, often short-term. Sixteen patients received treatment with other immunosuppressive drugs including methotrexate, cyclophosphamide, azathioprine, mycophenolic mofetil, and intravenous immunoglobulin (IVIg) generally with a limited modest response. Using clinical trial criteria for response, only 5/35 (14%) demonstrated improvement over a mean 34.4 months follow-up. CONCLUSIONS: Immune-mediated inner ear disease is not a uniform disease with simple diagnosis or treatment. The course of the disease often results in significant long-term disability due to hearing loss and response to aggressive immunosuppression including corticosteroids is poor.

Adrenal Cortex Hormones↗
PubMed2006

Immune-mediated inner-ear disorders in neuro-otology.

PURPOSE OF REVIEW: Immune-mediated inner-ear disorders may present to different medical disciplines and new research findings emerge rapidly. The purpose of this review is to draw the different strands together to produce an overview describing the clinical presentation of immune-mediated inner-ear disorders and to discuss useful diagnostic criteria with a focus on tissue-specific and tissue-non-specific antibodies. RECENT FINDINGS: The importance of diagnosing an immune-mediated inner-ear disorder is highlighted in the context of it being one of few forms of treatable inner-ear disorder with a good response to immunosuppressive therapy. Due to a lack of reliable tests, the criteria upon which the diagnosis of immune-mediated inner-ear disease is based are often arbitrary. Previous and current research focuses mainly on the investigation of the aetiology of immune-mediated disorders, studying the presence of autoantibodies and the antigens responsible for their production. The prognostic and therapeutic values of inner-ear-specific antibodies are still unclear. Various antigens have been suggested. However, most antigens identified have been ubiquitous proteins not specific to the inner ear and therefore lack logical association with localized inner-ear pathology. SUMMARY: Early diagnosis of immune-mediated inner-ear disorders with prompt treatment may prevent irreversible damage to inner-ear structures. Accordingly, it is important to include immune-mediated inner-ear disorders in the differential diagnosis of patients presenting with 'idiopathic' audiovestibular dysfunction. To enable early diagnosis, we recommend that the current available routine immunological laboratory tests (antinuclear, antineutrophil cytoplasmic, antiendothelial cell, antiphospholipid/anticardiolipin and antithyroid antibodies) are used when assessing a patient with suspected immune-mediated inner-ear disorder.

Animals↗
PubMed1993

Cloning genes from an inner ear cDNA library.

A rat inner ear complementary DNA (cDNA) library containing 1.9 x 10(6) recombinants was constructed and evaluated. Inserts averaged 2.0 (+/- 2.1) kilobases in length. A subset of inserts was screened for site of expression. Two cDNA transcripts were isolated based on cochlear expression restricted to the spiral ganglion. One transcript showed a high degree of homology to several long interspersed DNA elements, neuron-specific nuclear transcripts thought to be involved in gene regulation. The second transcript showed no homology to known sequences and appears to encode a neuron-specific protein of about 248 amino acids. The library can be used to identify proteins important for inner ear function and disease.

Animals↗
PubMed1992

Regional expression of three homeobox transcripts in the inner ear of zebrafish embryos.

The inner ear of all jawed vertebrates arises from the epithelium of the otic vesicle and contains three semicircular canals, otoliths, and sets of sensory neurons, all positioned precisely within the cranium to detect head orientation and movement. The msh-C gene and two new homebox genes, msh-D and a gene related to distal-less, dlx-3, are each expressed in distinct regions of the otic vesicle during its early development in zebrafish embryos. Cells in the ectoderm express dlx-3 before induction of the otic vesicle, suggesting that dlx-3 has an early function in this process. Later, cells aligned with the future axes of the semicircular canals specifically express either dlx-3 or msh-D. Even later, sensory hair cells express msh-C and msh-D, while other cells of the epithelium express dlx-3. The early expression of these genes could specify the orientation and morphogenesis of the inner ear, whereas their later expression could specify the fates of particular cell types.

Amino Acid Sequence↗
PubMed2000

Identification of beta-actin as a candidate autoantigen in autoimmune inner ear disease.

It has been shown that sera from patients with autoimmune inner ear disease contain antibodies to several inner ear antigens. We report here the characterization of the 42-43 kDa protein against which a significant number of patients' sera react strongly. After separation of inner ear proteins from guinea-pig cochleas by SDS-PAGE, the band corresponding to the 42-43 kDa protein was digested with trypsin and the peptide fragments were separated by high-performance liquid chromatography. Two fractions were then subjected to amino acid sequencing by the classical automated Edman degradation. The sequence of a stretch of 15 amino acids of the first fragment was identical to that of amino acids 148-162 of beta-actin. The sequence of the 10 amino acids of the second fragment was also identical to beta-actin. On Western blots, monoclonal antibody directed against beta-actin reacted with the inner ear 42-43 kDa proteins. The serum samples from the patients and the monoclonal antibody reacted with the non-muscle actin used as antigen in Western blotting. Immunoblot analysis of inner ear proteins after two-dimensional gel electrophoresis showed a spot, corresponding to the region of the 43 kDa as compared to the protein standards. On the basis of these data it is concluded that the target 42-43 kDa protein for antibodies in sera of patients with autoimmune inner ear disease is beta-actin, a molecule, which has important and numerous functions inside cells. This is the first report to identify the cytoskeletal protein beta-actin as a candidate autoantigen in autoimmune inner ear disease.

Actins↗
PubMed2005

Expression of the carrier protein apolipoprotein D in the mouse inner ear.

The cochlear portion of the inner ear converts movements produced by sound waves into electrical impulses. Transcripts enriched in the cochlea are likely to have an important role in hearing. In this paper, we report that microarray analyses of the Soares NMIE inner ear library revealed cochlear enriched expression of apolipoprotein D (apoD), a glycoprotein and member of the lipocalin family that transport small hydrophobic ligands. The cochlear enriched expression of Apod was validated by quantitative real time PCR analysis. To investigate the function of apoD in the inner ear the transcript and protein were localised in the cochlea. Apod messenger RNA (mRNA) expression was localised to the spiral ligament and spiral limbus, particularly in the suprastrial and supralimbral regions. The apoD protein was detected in the spiral ligament, spiral limbus and also in the outer hair cells of the organ of Corti. Investigation of cell lines exhibiting characteristics of hair and supporting cells revealed no Apod mRNA expression in these cells. This suggests transport of the protein within the cochlea, followed by internalisation into outer hair cells. The spiral limbus and ligament contain subpopulations of fibrocytes that are intimately involved in regulation of ion balance in the cochlear fluids and type I, II and III fibrocytes of the spiral ligament were all shown to be positive for apoD protein. On the basis of these results it was hypothesised that apoD could be involved in maintaining cochlear fluid homeostasis. To determine whether the apoD gene product was important for normal auditory function the hearing ability of an apoD knockout mouse was tested. The mouse was found to have a hearing threshold that was not significantly different to the control strain.

Animals↗
PubMed2000

Basic fibroblast growth factor inhibits cell proliferation in cultured avian inner ear sensory epithelia.

Postembryonic production of inner ear hair cells occurs after insult in nonmammalian vertebrates. Recent studies suggest that the fibroblast family of growth factors may play a role in stimulating cell proliferation in mature inner ear sensory epithelium. Effects of acidic fibroblast growth factor (FGF-1) and basic fibroblast growth factor (FGF-2) were tested on progenitor cell division in cultured auditory and vestibular sensory epithelia taken from posthatch chickens. The effects of heparin, a glycosaminoglycan that often potentiates the effects of the FGFs, were also assessed. Tritiated-thymidine autoradiographic techniques and 5-bromo-2;-deoxyuridine (BrdU) immunocytochemistry were used to identify cells synthesizing DNA. The terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end-label (TUNEL) method was used to identify apoptotic cells. TUNEL and overall counts of sensory epithelial cell density were used to assess possible cytotoxic effects of the growth factors. FGF-2 inhibited DNA synthesis in vestibular and auditory sensory epithelia and was not cytotoxic at the concentrations employed. FGF-1 did not significantly alter sensory epithelial cell proliferation. Heparin by itself inhibited DNA synthesis in the vestibular sensory epithelia and failed to potentiate the effects of FGF-1 or FGF-2. Heparin was not cytotoxic at the concentrations employed. Results presented here suggest that FGF-2 may be involved in inhibiting cell proliferation or stimulating precursor cell differentiation in avian inner ear sensory epithelia.

Animals↗
PubMed2001

CT and MR imaging of congential abnormalities of the inner ear and internal auditory canal.

The embryology of the inner ear must be known as many of the inner ear malformations present as a result of the arrest during the various stages of embryology. These malformations are described in this "embryologic" perspective and specific names for certain malformations are no longer used. Both CT and MR can be used to look at inner ear malformations but often both techniques are complementary. However, CT is preferred when associated middle- or external ear malformations must be excluded. Magnetic resonance is preferred when subtle changes in the membranous labyrinth or abnormalities of the nerves in the internal auditory canal must be visualised. The CT and MR technique must however be adapted as more and more subtle congenital malformations can only be seen when the right technique is used. The heavily T2-weighted gradient-echo or fast spin-echo MR techniques are mandatory if malformations of the inner ear must be excluded. The purpose of this paper is to describe the techniques used to study these patients and to give an overview of the most frequent and important congenital malformations which can be found in the inner ear and internal auditory canal/cerebellopontine angle.

Ear, Inner↗
PubMed2002

Cell density and N-cadherin interactions regulate cell proliferation in the sensory epithelia of the inner ear.

Sensory hair cells in the inner ears of nonmammalian vertebrates can regenerate after injury. In many species, replacement hair cells are produced by the proliferation of epithelial supporting cells. Thus, the ability of supporting cells to undergo renewed proliferation is a key determinant of regenerative ability. The present study used cultures of isolated inner ear sensory epithelia to identify cellular signals that regulate supporting cell proliferation. Small pieces of sensory epithelia from the chicken utricle were cultured in glass microwells. Under those conditions, cell proliferation was inversely related to local cell density. The signaling molecules N-cadherin, beta-catenin, and focal adhesion kinase were immunolocalized in the cultured epithelial cells, and high levels of phosphotyrosine immunoreactivity were present at cell-cell junctions and focal contacts of proliferating cells. Binding of microbeads coated with a function-blocking antibody to N-cadherin inhibited ongoing proliferation. The growth of epithelial cells was also affected by the density of extracellular matrix molecules. The results suggest that cell density, cell-cell contact, and the composition of the extracellular matrix may be critical influences on the regulation of sensory regeneration in the inner ear.

Animals↗
PubMed2004

Application of carbon dioxide and erbium:yttrium-aluminum-garnet lasers in inner ear surgery: an experimental study.

BACKGROUND: Surgery of the inner ear requires atraumatic techniques to preserve the sensory structures of the inner ear. With modern laser technology, surgery can be performed without mechanical contact, reducing the risk of direct mechanical trauma. However, energy transfer by laser light has the potential to induce damage by heating, pressure waves, or direct irradiation, depending on the properties of the laser and parameters of application. HYPOTHESIS: The application of laser systems in inner ear surgery may have an advantage over traditional techniques; the carbon dioxide laser in continuous mode with an automated scanning procedure and the erbium:yttrium-aluminum-garnet laser were compared with a mechanical technique, using a diamond drill. METHODS: A cochleostomy in the basal cochlear turn of guinea pigs was created. Thresholds in response to frequency-specific stimuli and clicks were established by recording compound action potentials, both before and after the procedure. RESULTS: The best results in terms of preservation of cochlear function were obtained with the diamond drill. However, a single ear had a complete loss after fracture of the cochlear wall. Mean threshold shifts observed with the carbon dioxide laser were slightly greater, showing mild high-frequency losses, although differences to the group of drilling were not statistically significant. Results with the erbium:yttrium-aluminum-garnet laser showed significantly higher degrees of hearing loss than the other two groups, predominantly in the high-frequency region. CONCLUSIONS: Mechanical opening of the inner ear using a microdrill can be performed with minimal hearing loss; however, it carries the risk of direct trauma to the inner ear. The carbon dioxide laser with a new scanning technology as a noncontact procedure is shown to be effective and safe. It can be regarded as a useful tool in inner ear surgery. The erbium:yttrium-aluminum-garnet laser has a greater potential to cause damage.

Aluminum↗
PubMed2002

Differential expression of alpha 3 and alpha 6 integrins in the developing mouse inner ear.

The development of the mammalian inner ear involves a complex series of cell-cell and cell-extracellular matrix interactions. These interactions are likely to be mediated by families of adhesion molecules, including the integrins. We have studied the expression of three integrin subunits known to be expressed on epithelia in a number of tissues (namely, alpha3, alpha6, and beta4) during the development of the murine inner ear. At E10.5, both alpha3 and alpha6 were expressed in the epithelial layers of the otocyst. The expression of alpha6 was concentrated in an anterioventral region of the epithelium and in a proportion of the cells forming the cochlear-vestibular and facial ganglia. By E12.5, alpha6 showed a more restricted expression, confined mainly to the pro-sensory epithelia and the neural processes from the cochlear-vestibular ganglion. In contrast, alpha3 was expressed in epithelia adjacent to the pro-sensory areas. This reciprocal expression pattern was maintained until birth. Between birth and P6, a switch in expression occurred such that alpha3 was upregulated and alpha6 was downregulated in the sensory epithelia of both the auditory and vestibular systems. At this stage, alpha3 was expressed in all the epithelia lining the scala media, thus defining the endolymph compartment. The expression of beta4 was restricted to epithelial/mesenchymal borders throughout the developmental stages studied, suggesting that alpha6 expression observed within the epithelium and neuronal tissue was alpha6beta1. The early expression and changing pattern of alpha3 and alpha6 integrins during development of the mammalian inner ear suggests that they may be involved in the molecular processes that define epithelial boundaries and guide sensory innervation.

Animals↗
PubMed1987

Collagen type II in the otic extracellular matrix. Effect on inner ear development.

Immunocytochemistry was used to demonstrate type II collagen distribution during normal development of the mouse inner ear and in two malformed inner ears. Patterns of inner ear abnormalities and type II collagen distribution were compared between the malformed labyrinth of a mouse mutation (disproportionate micromelia, Dmm) and otic explants exposed to the teratogenic action of an L-proline analog, L-azetidine-2-carboxylic acid (LACA). The results suggest that type II collagen is an important constituent of the developing inner ear's extracellular matrix. Disruptions of the spatial and temporal pattern of collagen type II can adversely affect morphogenesis of the inner ear. A common mechanism of action is postulated for the causation of both the genetic and teratogen-induced inner ear malformations (i.e. disruption of the secretion of collagens to the otic extracellular matrix).

Animals↗