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At least 1,009 records · Page 56Linked to original sources
PubMed2003

Sudden presentation of immune-mediated inner ear disease: characterization and acceptance of a cochleovestibular dysfunction.

Since the McCabe report, growing indirect evidence has accumulated to indicate the implication of immune mechanisms in the pathogenesis of immune-mediated inner-ear disease (IMIED). A clinical study of a group of patients affected by this condition was performed in order to characterize the immune group, based on a recently reported profile, and compared with the vascular, viral and idiopathic aetiologies of sudden deafness. Patients affected by immune-mediated inner-ear disease had the best and the earliest recovery rate of hearing (p = 0.0028 and p = 0.017, respectively). However, this group of patients also had the higher rate of recurrence (p = 0.034), supporting the typical clinical course of the autoimmune disorders. On the basis of the results the criteria used in the diagnosis of the sudden presentation of the immune-mediated inner ear disease could be accepted leading to the characterization of this condition. Likewise, the role of the supporting cells in the pathogenesis of the IMIED is discussed.

Adolescent↗
PubMed2004

The inner ear of the lungfish Protopterus.

The sensory end organs of the inner ear of the lungfish, Protopterus, were examined using scanning and transmission electron microscopy. The utricle has a structure and hair cell orientation pattern that are typical for vertebrates, although the hair cells are unusually large. There are the typical three semicircular canals extending from the utricle, with the typical hair cell orientations, but the lateral canal sensory crista looks like the "hemicrista" of some amphibians and amniotes, lacking a saddle-shaped flare on one wall of the ampulla. Unlike most vertebrates that have the saccule and lagena as two separate pouches ventral to the utricle, the lungfish has a single large ventral pouch that contains a single large pasty otoconial mass. This mass covers two hair cell patches, each like a striola with prominent hair cell ciliary bundles, that are presumed to represent saccular and lagenar maculae. However, these two major sensory patches are not completely separate maculae because they lie within a less densely populated field of smaller hair cells, which forms an extrastriolar region that surrounds and fills the region between the two striolae of higher hair cell density. The more caudal lagenar striola is a vertically elongated stripe with hair cell orientation vectors facing antiparallel on either side of a midline drawn vertically along the macula, resembling the macula lagena of some bony fishes but not of tetrapods. The more rostral saccular striola is a curving band with hair cell orientation vectors facing away from its midline, but because this macula curves in three dimensions, the vectors at the rostral end of this striola are oriented mediolaterally, whereas the vectors on the caudal half of this striola are oriented dorsoventrally. The presence of a macula neglecta was confirmed near the posterior canal as a tiny single patch of a few dozen hair cells with all the cell orientations directed caudally. The ciliary bundles on the cells in the striolar-like regions of all of three otolithic organs average over 80 cilia, a number far greater than for any other fish studied to date. The features of the single sacculolagenar pouch with separate striolar-like regions, the cellular orientation in the otolith organs, and the large cells and ciliary bundles in Protopterus also were observed in specimens of the other extant lungfish genera, Lepidosiren and Neoceratodus.

Animals↗
PubMedDate not supplied

Fibrinolytic activity in the inner ear of human beings and guinea pigs.

Fibrinolytic activity in the inner ear of human beings and guinea pigs was assayed qualitatively and quantitatively. It was found that fibrinolytic activity of the stria vascularis was caused by a conversion of plasminogen to plasmin by tissue plasminogen activator and was moderate in degree compared with that of other organs in both species. In human beings, endolymph showed higher plasminogen activator activity than that of CSF. Plasminogen activator activity was not detected in either endolymph or perilymph of guinea pigs. Thrombin infusion diminished plasminogen activator activity in the stria vascularis of guinea pigs.

Animals↗
PubMed1983

Influence of argon laser stapedotomy on inner ear function and temperature.

The influence of argon laser stapedotomy on inner ear function was investigated in guinea pigs. The cochlear microphonics (CM) and the compound action potential (CAP) served as parameters for the functional status of the cochlear. Transitory depression of both potentials was found during and after laser stapedotomy. The time course of CM and CAP depression and recovery is compared to endocochlear temperature changes. Possible implications for clinical use are discussed.

Action Potentials↗
PubMed2006

Zebrafish atoh1 genes: classic proneural activity in the inner ear and regulation by Fgf and Notch.

Hair cells of the inner ear develop from an equivalence group marked by expression of the proneural gene Atoh1. In mouse, Atoh1 is necessary for hair cell differentiation, but its role in specifying the equivalence group (proneural function) has been questioned and little is known about its upstream activators. We have addressed these issues in zebrafish. Two zebrafish homologs, atoh1a and atoh1b, are together necessary for hair cell development. These genes crossregulate each other but are differentially required during distinct developmental periods, first in the preotic placode and later in the otic vesicle. Interactions with the Notch pathway confirm that atoh1 genes have early proneural function. Fgf3 and Fgf8 are upstream activators of atoh1 genes during both phases, and foxi1, pax8 and dlx genes regulate atoh1b in the preplacode. A model is presented in which zebrafish atoh1 genes operate in a complex network leading to hair cell development.

Animals↗
PubMedDate not supplied

Organ culture of the late embryonic inner ear as a model for ototoxicity studies.

The 16th gestational day inner ear of the CBA/CBA mouse was used in an organ culture system as a model for ototoxicity studies. The specimens in culture were exposed to 1, 10, 100 and 1 000 micrograms/ml of gentamicin base during 1-5 days in culture. Minor changes were found after only one day of exposure. Pathological changes of vestibular hair cells characteristic for aminoglycoside antibiotics occurred after exposure to 1 and 10 micrograms/ml. Concentrations of 100 and 1 000 micrograms/ml caused a general toxicity with destruction of the whole morphology of the crista ampullaris. Hair cells were, however, more affected than were supporting cells. Initially, variation of hair cell damage occurred within each crista and between different cristae but this became less apparent after 5 days in culture. The 16th gestational day organ culture system can serve as a useful model system with many controlled experimental parameters in the testing of ototoxic drugs.

Animals↗
PubMed1983

X-ray microanalysis of developing and mature inner ear.

X-ray microanalysis technique is a new tool in inner ear research. According to the literature in this field only the energy dispersive type of analysis has been used. Data obtained from X-ray microanalysis are in agreement with results using other techniques, mainly fluid withdrawal from the endo- and perilymphatic spaces. The introduction of serial sectioning (16 microns thick sections) of the temporal bone for microanalysis now also permits analysis of embryonic material with its delicate structures too small for other techniques. The energy dispersive technique is thus suitable for analysis of both biological fluids and tissues. Studies have so far been focused on mainly normal conditions in the embryonic and adult labyrinth.

Aging↗
PubMedDate not supplied

Interleukin 8 can affect inner ear function.

The chemokine interleukin 8 (IL-8) was instilled into the round window niche of rats through a small perforation in the tympanic membrane in order to study its effect on inner ear function by electrophysiological and morphological techniques. The frequency-specific auditory brainstem response (ABR) was recorded at the frequencies 4, 8, 10, 12, 16 and 20 kHz just before and 1, 2, 5 and 14 days after instilling IL-8 to ascertain the hearing level during each interval. Morphological examination by light microscopy was performed during the same interval following the instillation of IL-8. On day 1, the rise in ABR threshold was within 5 dB SPL (non-significant elevation). However, a significant threshold elevation (above 5 dB SPL) occurred in high-frequency areas (16 and 20 kHz) on day 2, and in middle frequency areas (10 and 12 kHz) on day 5 with sensorineural hearing loss type intensity-latency curves. By day 14, the elevated thresholds had returned to pre-instillation levels. In the lowest areas (4 and 8 kHz), no significant threshold elevation was detected at any time during the observation period. By light microscopy, on day 1, clusters of inflammatory cells (predominantly neutrophils) were observed just outside the round window membrane (RWM), while only a few neutrophils were detected in the cochlea. These cells were still present outside the RWM on day 2. The neutrophils had disappeared by day 5 and only macrophages were present on the middle ear side of the RWM. However, throughout the observation period, the organ of Corti and stria vascularis appeared to be intact. These results suggest that IL-8 in the middle ear cavity is able to influence inner ear function.

Animals↗
PubMed2002

Effects of topical mitomycin on inner ear: a light and electron microscopic study.

Providing maintenance of myringotomy patency without use of ventilation tubes in the treatment of secretory otitis media has been one of the important study areas. For this reason, laser and Mitomycin C (MMC) are used together in experimental studies. But there has been no ultrastructural studies concerning whether leakage of MMC to middle ear during application of this procedure has an ototoxic effect or not and if so, to what extent. In this study, we searched the ultrastructural changes which occurred in the middle ear by direct applications of MMC to the middle ear for different time durations. The study was carried out over thirty adult guinea pigs without ear diseases. Bilateral myringotomy was performed and MMC was applied only to the right middle ear of each guinea pig. The first group received MMC once for 10 minutes, the second group received it once for 20 minutes, and the third group took it each day for 10 minutes during a one week period. The left ears of the samples were accepted as the control group. On the 8th day, sacrification was carried out. After electron and light microscopy examination, significant changes in the inner ear were observed in the third group though no significant change was observed for the first and the second groups. As a result it was concluded that the application of MMC to the middle ear once for a short duration causes no toxic effect on the inner ear.

Administration, Topical↗
PubMed1998

Changes in immunostaining of inner ears after antigen challenge into the scala tympani.

To study the mechanisms of immune responses and immune injuries in inner ears, labyrinthitis was induced by inoculation of keyhole limpet hemocyanin (KLH) into the scala tympani of systemically sensitized guinea pigs. Inner ears were then immunostained for KLH, immunoglobulin G (IgG), albumin, connexin26 (Cx26), and sodium-potassium adenosine triphosphate (Na,K-ATPase). Inflammatory cells containing KLH were observed in the scala tympani and in the collecting venule of the spiral modiolar vein (SMV). Spiral ligament, spiral limbus, and blood vessels including the SMV were diffusely positive for IgG and albumin. Immunoreactivity for Cx26 and Na,K-ATPase was decreased compared with the normal ears in the fibrocytes of the spiral ligament. These results suggest that inflammatory cells and blood constituents could extravasate into the cochlea from blood vessels and that fibrocyte damage in the spiral ligament could cause cochlear dysfunction.

Adjuvants, Immunologic↗
PubMed1996

Aspartate is enriched in sensory cells and subpopulations of non-neuronal cells in the guinea pig inner ear: a quantitative immunoelectron microscopic analysis.

The cellular and subcellular localization of aspartate in the guinea pig inner ear was studied by means of quantitative postembedding cytochemistry. High levels of aspartate immunoreactivity were found in neuronal compartments, including all types of hair cells, and afferent and efferent nerve fibers. In addition, sub-basilar tympanic cells, interdental cells, and the mesothelial cells in the Reissner's membrane were strongly immunoreactive. The present immunocytochemical results are consistent with the idea that aspartate is involved in neurotransmission in the inner ear, but also point to possible metabolic roles of aspartate.

Animals↗
PubMed2004

Inner ear changes with intracochlear gentamicin administration in Guinea pigs.

OBJECTIVES/HYPOTHESIS: Transtympanic administration of gentamicin is reported to be a useful treatment for vertigo in such conditions as Meniere's disease, and determining appropriate clinical dosage of gentamicin is difficult. The authors examined the relation between gentamicin dosages and inner ear function in guinea pigs. STUDY DESIGN: This study is a basic science project designed to examine cochlear and vestibular function in animal models. METHODS: Various concentrations of gentamicin solution were infused into the right inner ear of guinea pigs by osmotic pumps. Caloric nystagmus as a marker of vestibular function and the change in auditory brainstem response (ABR) threshold as a marker of cochlear function were observed. RESULTS: After 14 days of treatment, high gentamicin concentrations of 40 mg/mL caused canal paralysis and a rapid shift in ABR threshold. Animals exposed to low gentamicin concentrations of 4 mg/mL showed no obvious change in either vestibular or cochlear function. Animals exposed to moderate gentamicin concentrations of 12 mg/mL showed a moderate shift in ABR threshold and caloric malfunction. Histopathological examination revealed that after 14 days of treatment with 40 mg/mL gentamicin, severe cytoplasmic damage occurred in both vestibular and cochlear end organs. In animals treated with 12 mg/mL gentamicin, hair cells remained in the cochlear third turn and ampulla of the lateral semicircular canal. CONCLUSION: The authors established an animal model that showed the moderate damage of inner ear with moderate-dose gentamicin. The study results indicated that the appropriate administration of gentamicin could establish a stable effect on the inner ear. It may be important to select the protocol that delivers a stable dosage of gentamicin to treat patients with Meniere's disease safely and effectively.

Administration, Topical↗
PubMed1997

Induction of cell proliferation in avian inner ear sensory epithelia by insulin-like growth factor-I and insulin.

Postembryonic production of inner-ear hair cells occurs both normally and after insult in lower vertebrates and avians. To determine how this proliferation is controlled, several growth factors were tested for effects on progenitor-cell division in cultured avian vestibular sensory epithelium. Mitogenic effects of bombesin, epidermal growth factor, insulin-like growth factor-I (IGF-I), insulin, and transforming growth factor-alpha were assayed in organo-typic cultures of utricles from the mature, undamaged (normal) chicken inner ear. Tritiated thymidine and autoradiographic techniques and 5-bromo-2'-deoxyuridine (BrdU) immunocytochemistry were used to identify cells synthesizing DNA. IGF-I stimulated DNA synthesis in the vestibular sensory receptor epithelium in a dose-dependent manner. DNA synthesis was also stimulated by insulin. These results suggest that stimulation of the IGF-I receptors by IGF-I or insulin binding stimulates cell proliferation in the mature avian vestibular sensory epithelium.

Animals↗
PubMed2000

A transgenic insertional inner ear mutation on mouse chromosome 1.

OBJECTIVES/HYPOTHESIS: To clone and characterize the integration site of an insertional inner ear mutation, produced in one of fourteen transgenic mouse lines. The insertion of the transgene led to a mutation in a gene(s) necessary for normal development of the vestibular labyrinth. STUDY DESIGN: Molecular genetic analysis of a transgene integration site. METHODS: Molecular cloning, Southern and northern blotting, DNA sequencing and genetic database searching were the methods employed. RESULTS: The integration of the transgene resulted in a dominantly inherited waltzing phenotype and in degeneration of the pars superior. During development, inner ear fluid homeostasis was disrupted. The integration consisted of the insertion of a single copy of the transgene. Flanking DNA was cloned, and mapping indicated that the genomic DNA on either side of the transgene was not contiguous in the wild-type mouse. Localization of unique markers from the two flanks indicated that both were in the proximal region of mouse chromosome 1. However, in the wild-type mouse the markers were separated by 6.3 cM, indicating a sizable rearrangement. Analysis of the mutant DNA indicated that the entire region between the markers was neither deleted nor simply inverted. CONCLUSIONS: These results are consistent with a complex rearrangement, including at least four breakpoints and spanning at least 6.3 cM, resulting from the integration of the transgene. This genomic rearrangement disrupted the function of one or more genes critical to the maintenance of fluid homeostasis during development and the normal morphogenesis of the pars superior.

Animals↗
PubMedDate not supplied

Evidence of serum antibodies against inner ear tissues in the blood of patients with certain sensorineural hearing disorders.

In healthy human temporal bones, immunoglobulins (IgG, IgA) and the secretory component are demonstrated by two immunohistochemical methods in epithelial cells and in the lumen of the endolymphatic sac. The normal human inner ear does not otherwise show any localization of immunoglobulins. By means of indirect immunofluorescence, antibodies against healthy inner ear tissue were found in the serum of 15 out of 21 patients with double-sided progressive or fluctuating sensorineural hearing loss of undefined etiology. In 2 cases of Cogan's syndrome, it was also possible to demonstrate serum antibodies against epithelial structures of the cornea. The lymphocyte mitogen stimulation test performed with the fresh blood of 5 patients with positive detection of serum antibodies against healthy inner ear tissue was negative.

Autoantibodies↗
PubMed1998

3D MRI of the membranous labyrinth. An age related comparison of MR findings in patients with labyrinthine fibrosis and in persons without inner ear symptoms.

PURPOSE: We compared MRI of the membranous labyrinth in patients with chronic non-neoplastic inner ear disease and MR signs of labyrinthine fibrosis and controls depending on their age, in order to establish whether there were any MR differences regarding patient age groups, control age groups and between the patients and controls themselves. MATERIALS AND METHODS: Clinical ENT examinations as well as a T2* weighted 3D CISS (Constructive Interference in Steady State) sequence with a slice thickness of 0.7 mm were performed. Our collective was subdivided as follows: 0-19 years (10 controls, 3 patients with chronic non-neoplastic inner ear disease), 20-49 years (55 controls, 8 patients), 50 years and older (40 controls, 22 patients). Detectability of labyrinthine structures (e.g. cochlea, vestibule, semicircular canals) and filling defects were evaluated. RESULTS: In the 3 age-groups of the control collective no significant differences were observed in the membranous labyrinth. However differences concerning labyrinthine detectability emerged between controls and patients in both the 20-49 years and 50 years and older age groups. In the patient collective the 3 age groups showed no significant discrepancy in the mean number of lesions. CONCLUSION: Filling defects of the membranous labyrinth on 3D CISS MR images are pathological even in older persons. We would therefore recommend high resolution T2* weighted MRI in the case of suspected labyrinthine fibrosis.

Adolescent↗
PubMed2006

Inner ear hemorrhage in systemic lupus erythematosus.

A 33-year-old man had systemic lupus erythematosus (SLE) with anticardiolipin antibody. At the age of 40 years, he experienced bilateral hearing deterioration. The three-dimensional fluid-attenuated inversion recovery of magnetic resonance imaging showed high signals bilaterally in the cochlea and vestibule. He was diagnosed with bilateral inner ear hemorrhage on the basis of the presence of anticardiolipin antibody. This is the first published case of inner ear hemorrhage in a patient with SLE. Our findings suggest that inner ear hemorrhage is associated with hearing deterioration in some patients with SLE.

Adult↗
PubMedDate not supplied

The common cavity congenital deformity of the inner ear. An important precursor of meningitis described in 1838.

Congenital deformity of the osseous labyrinth of the inner ear is well recognized as being associated with a fistulous communication with the intracranial subarachnoid space in some cases, leading to meningitis or a spontaneous 'stapes gusher'. Such cases have been described inappropriately as 'Mondini's dysplasia'. We cite 2 patients who both died of meningitis and had an accurate postmortem anatomical appraisal of the deformed temporal bones, one recently described by us and one by Cock more than 150 years ago. The use of eponyms is to be deprecated but should faithfully reflect the original description. The 'common cavity' lesion of the inner ear is a most important precursor of otogenic meningitis readily assessed by computed tomography and needing surgery to prevent the egress of cerebrospinal fluid or ingress of pathogens causing meningitis.

Child↗