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PubMedDate not supplied

Ultrastructural localization of K+-dependent, ouabain-sensitive NPPase (Na-K-ATPase) in the guinea pig inner ear.

Ultrastructural localization of the phosphatase component of Na-K-ATPase in the inner ear of the guinea pig was studied utilizing p-nitrophenyl phosphate (NPP) as substrate. In the stria vascularis NPPase activity was restricted to the cytoplasmatic side of the basal plasma membranes of the marginal cells. In the spiral prominence enzyme activity was resolved only occasionally on the basolateral membranes of the spiral prominence epithelium, especially after longer incubation periods. The remaining inner ear tissue was unreactive. Possible transport mechanisms of potassium across the apical marginal cell membrane are discussed.

4-Nitrophenylphosphatase↗
PubMed2002

Development of the zebrafish inner ear.

Abstract Recent years have seen a renaissance of investigation into the mechanisms of inner ear development. Genetic analysis of zebrafish has contributed significantly to this endeavour, with several dramatic advances reported over the past year or two. Here, we review the major findings from recent work in zebrafish. Several cellular and molecular mechanisms have been elucidated, including the signaling pathways controlling induction of the otic placode, morphogenesis and patterning of the otic vesicle, and elaboration of functional attributes of inner ear.

Animals↗
PubMed1987

The use of immunofluorescence in the non-decalcified frozen guinea pig cochlea to detect autoantibodies in inner ear disorders.

Autoantibodies in the serum of patients with inner ear disorders have been detected using the immunofluorescence technique. In the present study the results of the use of frozen sections of non-decalcified guinea pig cochlea in the indirect immunofluorescence test are described. Human sera with positive anti-mitochondrial (AMA), anti-nuclear (ANAS) and anti-nucleolar (ANAN) antibodies were utilized, as well as a negative serum control and sera from three patients suffering from chronic progressive sensorineural hearing loss. The positive reactions obtained were clear and specific. Autofluorescence was minimal and non-specific reactions were negligible. The fine structure of the inner ear tissue and the cellular antigenicity present were well preserved.

Animals↗
PubMed1996

Inductive processes leading to inner ear formation during Xenopus development.

This study examines the spatial and temporal attributes of inner ear induction in Xenopus embryos. These results are compared to recent experiments concerning lens induction to assess whether head sensory structures share common ontogenetic features. Ectoderm from different regions and stages was transplanted to the presumptive ear region of hosts of either early (neural plate) or late (neural tube) stages. Explants of the presumptive ear ectoderm were also taken from embryos at these stages to establish the time of otic ectoderm specification. We find that ectodermal competence for otic vesicle formation extends through neural plate stages, far longer than for lens formation. Otic vesicle specification occurs substantially earlier, at neural plate stages, than lens specification. Competent ectoderm forms otic vesicles in a high fraction of cases when exposed to the ear-inducing environment of either neural plate stages or neural tube stages, a result which contrasts with lens induction where the neural tube stage embryo provides a much weaker inducing environment than earlier stages. Otic vesicles induced in neural tube stage hosts are primarily in contact with presumptive hindbrain, suggesting that this neural tissue may be sufficient for otic vesicle induction. These studies reveal overall similarities between lens and inner ear induction, but sufficient differences to propose that some facets of determination of these sensory tissues may occur by independent mechanisms and not via a common developmental state.

Animals↗
PubMed2000

Virtual endoscopy of the middle and inner ear with spiral computed tomography.

OBJECTIVE: To evaluate the inner anatomy of the auditory apparatus by means of virtual endoscopy of spiral computed tomography (CT) data sets. BACKGROUND: Virtual endoscopy permits simulation of the fiberoptic endoscopy perspective by processing CT or magnetic resonance images. METHODS: Seven formalin-fixed specimens of human mastoid were scanned with spiral CT with the following protocol: beam collimation 1 mm, pitch ratio 1, reconstruction spacing 0.2 to 0.5 mm, field of view 90 mm. For the generation of endoscopic views of the auditory spaces, the axial images were processed with Navigator software 2.0 running on UltraSparc I workstation. RESULTS: Virtual endoscopy allowed the demonstration of the external auditory canal, the head and handle of the malleus, the stapes and incudostapedial articulation, the corpus, the long process of the incus with its lenticular process and the short limb, the malleoincudal articulation, the rounded promontory, the round and oval windows, and Prussak's space. From inside the basal turn of the cochlea, virtual endoscopy showed the orifices of the fenestrae cochlea and vestibuli, the origin of the lateral and the anterior semicircular canals, and the basal turn of cochlea. The optimal perspectives that allowed demonstration of the anatomical details of the middle and inner ear are described. CONCLUSION: Virtual endoscopy allows the generation of inner views of the auditory spaces. This new method of image processing can be proposed as an integrative tool of spiral CT imaging.

Culture Techniques↗
PubMed1991

X-linked deafness, stapes gushers and a distinctive defect of the inner ear.

The association of X-linked mixed deafness with stapes gusher has been recognized for 20 years, and imaging studies by polytomography have shown dilatation of the lateral end of the internal auditory meatus (IAM) in some cases. We have made genetic linkage studies in 7 pedigrees in whom deafness was inherited in an X-linked manner. All patients had a full range of audiometric and vestibular function tests. Thin section high resolution CT in two planes was used to assess the state of the middle and inner ears. We found a distinctive inner ear deformity in some of the deaf males characterised not only by a wide bulbous IAM but more importantly, by deficient or absent bone between the lateral end of the IAM and the basal turn of the cochlea. We believe that this results in a communication between the subarachnoid space in the IAM and the perilymph in the cochlea, leading to perilymphatic hydrops and a "gusher" if the stapes is disturbed. Moreover, some of the obligate female carriers seem to have a milder form of the same anomaly associated with slight hearing loss. Genetic studies on some of the deaf males with apparently normal inner ear anatomy suggest a different locus on the X chromosome and hence a different pathogenesis for the deafness.

Audiometry↗
PubMed2002

Mpv37 mouse strain--a model for the relationship between the kidney and the inner ear.

Using the Mpv17-negative mouse strain, which developed inner ear and kidney dysfunction, we confirm a strong relationship between the kidney and the inner ear. Both organs have specialized epithelia involved in active ion transport, which are separated from the vessels by a basement membrane of similar composition. Our recent results indicate that the glomerular and the stria vascularis basement membrane are simultaneously affected in early stages. Concomitant deposits of IgG during the progressive development of the disease support the idea of a shared antigen. Understanding the pattern of the development of the degeneration will provide a basis towards understanding the essential role of the Mpv17 protein in the structures of both organs and may provide a basis for future therapeutic intervention.

Animals↗
PubMed1978

[Protects stapedectomy from increasing otosclerotic inner ear deafness? (author's transl)].

The favourable influence--first shown by Shambaugh--of fenestration operation used in cases of the otosclerosis which cause a rapid sensorineural hearing loss can also be stated for stapedectomy. A negative influence of stapedectomy on inner ear stability was not determined. Especially the ears whose inner ear function is very bad were favoured by this operation.

Bone Conduction↗
PubMed2004

[Evaluation of the inner ear fluorescence].

Searching for the methods, which may improve the visualisation of the membranous labyrinth, authors decided to evaluate autofluorescence of the membranous structures of the inner ear. The analysis of the inner ear autofluorescence parameters was performed. We assessed, whether the detected differences in autofluorescence between the bony elements and the membranous structures, allows the practical apply, owning to increased contrast in the operating microscope. The optimal wave length inducing autofluorescence of membranous labyrinth amounts to 465 nm. Obtained in these circumstances contrast of the membranous structures don't cause a significant improvement in their visualisation, comparing with the picture received in the traditional optical microscope.

Ear, Inner↗
PubMed1988

The effect of fibrin tissue adhesive on the middle and inner ears of chinchillas.

The purpose of this study was to examine potential toxic effects of fibrin tissue adhesive to the middle and inner ears. Using the chinchilla as our experimental model, we placed fibrin sealant on either the footplate or the round window membrane in one ear, and placed similar amounts of normal saline in the same area of the opposite ear. In addition, the fibrin adhesive was used to anchor a fascia lata graft for myringoplasty. Both fibrin adhesive and normal saline produced mild reactions in the middle and inner ears when they were placed on the round window membrane; little reaction occurred when fibrin adhesive was placed on the oval window or when it was used for myringoplasty.

Animals↗
PubMed2000

Basic and clinical physiology of the inner ear receptors and their neural pathways in the brain.

The six receptors of the inner ear (cochlea, two otolith organs and three semicircular canals) share a common transduction unit made up of a sensory hair cell, a first order sensory neuron and the synapse between them. Displacement of the stereocilia in a particular direction leads to excitation of the hair cell and activation of the neuron. Electrical and mechanical reflections of these stages of transduction can be recorded non-invasively in humans and in animals. These include cochlear microphonic potentials, otoacoustic emissions, auditory and vestibular evoked potentials. The ability to record these activities can be used to track the development of inner ear function in the fetus and neonate and to study the effects of various ototoxic agents (e.g. noise) and drugs.

Animals↗
PubMed1993

Microvascular system of the human fetal inner ear: a scanning electron microscopic study of corrosion casts.

The vascular system of the inner ear was investigated in 18-21 weeks old human fetuses, using the corrosion cast technique in scanning electron microscopy. At that developmental stage, vascularization of the cochlea and semicircular canals shows a pattern very similar to that described for adults. The most important differences which can be regarded as fetal features include: (1) denser limbus vessels, (2) the marginal vessels of the spiral lamina appearing as irregular network which shows a less clear arcade-like arrangement, (3) some radiating arterioles of the spiral lamina and marginal vessels possessing connections with the vascular system of the external wall, and (4) a dense, sinusoidal network of draining venules at scala tympani. These features apparently disappear during the final remodelling of the inner ear microvasculature in the last trimester.

Blood Vessels↗
PubMed2004

[CT of the temporal bone in the study of the inner ear structures in detection of the causes of neurosensory hypoacusis].

Computed tomograms of the inner ear structures (n=175) of 150 patients (age 0-75 years) with unaffected temporal bones were studied in detail. It is shown that polyposition CT of the temporal bone is a non-invasive method of visualization of the osseous labyrinth structures: cochlea, vestibule, semicircular canals, aqueducts of the labyrinth and internal acoustic meatus which are reflected on tomograms in 100% cases irrespective of the patient age. Their age-related features are analysed. CT imaging was made in 65 patients with neurosensory hypoacusis of inherited and acquired genesis. The following causes of neurosensory hypoacusis and deafness were revealed: congenital malformation of the labyrinth of Mondini type, common cavity of the labyrinth, cochlear hypoplasia, dysplasia of the vestibule and semicircular canals, a wide aqueduct of the vestibule, stenosis of the internal acoustic meatus, bulboform enlargement of the inner acoustic meatus, neurinoma (schwannoma) of the hearing nerve, Langerhans-cell histiocytosis with affection of the labyrinth capsule, atypical cholesteatoma. The detected changes in the inner ear structures determine further treatment policy.

Adolescent↗
PubMedDate not supplied

The low temperature vacuum embedding technique for X-ray microanalysis of the developing inner ear.

The method of low-temperature embedding in vacuo using methacrylate resins, was tested for X-ray microanalysis of the embryonic inner ear of the CBA/CBA mouse. Fetal inner ears were examined on gestational days 16 and 18. The technique was evaluated in comparison with earlier used preparation techniques for X-ray microanalysis. With plastic embedding, an improvement of the morphological resolution was achieved, which allows reliable structural identification on the subcellular level. Furthermore, the possibility of orientating of the specimen prior to sectioning provides a better controlled and less time-consuming sectioning.

Animals↗
PubMed2004

Interferon-gamma expression in the inner ear of rats following secondary immune reaction in the endolymphatic sac.

Recently, we demonstrated increased intercellular adhesion molecule-1 (ICAM-1) expression in the inner ear of systemically pre-sensitized rats after antigen [keyhole limpet hemocyanin (KLH)] challenge into the endolymphatic sac (ES), in good correlation with the cellular infiltration. Interferon-gamma (IFN-gamma) is an important cytokine that upregulates the expression of ICAM-1. Here, we report upregulation of IFN-gamma expression in the inner ear of systemically pre-sensitized rats after antigen (KLH) challenge into the ES. Immunoreactivity for IFN-gamma was detected in the spiral ligament, suprastrial region, spiral modiolar veins, spiral collecting venules, surface membrane of the perilymphatic compartment and perilymphatic space of immunized, but not control, rats. IFN-gamma expression was detected at 1.5 h post-challenge, peaked at 6 h and gradually returned to baseline levels after 7 days. Interestingly, the time kinetics of IFN-gamma expression were in good correlation with those of ICAM-1. These observations demonstrate that antigen challenge into the ES induces IFN-gamma expression, which can then upregulate ICAM-1 expression and induce cell infiltration, suggesting that IFN-gamma may play a crucial role in immune-mediated inner ear diseases.

Animals↗
PubMed1984

In vitro development of the embryonic mouse inner ear following exposure to trypsin.

Trypsin has been shown to disrupt normal in vitro morphogenesis of embryonic organ rudiments. Otic tissues derived from 11-, 12-, and 13-day-old mouse embryos were exposed to either Ca++- and Mg++-free PBS or 0.25% trypsin dissolved in Ca++- and Mg++-free PBS prior to explanation into organ culture. Trypsin treatment of otic explants disrupted the expression of the normal pattern of inner-ear development in vitro. There was a direct correlation between the embryonic age at time of exposure to trypsin and the severity of dysmorphogenesis of the inner ear. The younger explants showed abnormalities of both vestibular and auditory structures, whereas with increasing embryonic age, abnormalities were confined more to the auditory portion of the inner ear. The results suggest that integrity of the otocyst basal lamina and epitheliomesenchymal tissue interactions are important factors in early otic development. It is postulated that the major effect of trypsin on inner-ear morphogenesis is through disruption of these factors, which may act to regulate the progressive expression of early otic development.

Animals↗
PubMedDate not supplied

Free radicals in the guinea pig inner ear following gentamicin exposure.

The purpose of this study was to investigate the occurrence of free radicals, nitric oxide (NO), superoxide (O-2) and peroxynitrite, in the inner ear of the guinea pig following intratympanic injection with 5 mg of gentamicin (GM). Forty-eight hours after GM injection, varying degrees of degeneration of the inner ear were observed. Immunohistochemical study revealed immunoreactivity to NO synthase II (which generates NO) and to xanthine oxidase (which generates O-2) in both the vestibular organ and the organ of Corti. Immunohistochemical investigation, using a specific antinitrotyrosine antibody, also showed intense staining, suggesting formation of peroxynitrite in the inner ear through the reaction of NO with O-2. Scanning electron-microscopic study showed that the ototoxic effects could be blocked with N-nitro-L-arginine methylester, a competitive inhibitor of NO synthase, with superoxide dismutase, an O-2 scavenger, and with ebselen, a scavenger of peroxynitrite. On the basis of these findings, it can be concluded that NO together with O-2, which form more reactive peroxynitrite, play an important role in GM ototoxicity in the guinea pig.

Animals↗
PubMed1986

Melanin in the inner ear: micromorphological and microanalytical investigations.

Melanin-pigments are found in various parts of the inner ear, especially in the neighbourhood of those epithelia that are believed to be involved in the secretion and/or absorption of endolymphatic fluid. Microprobe analysis (LAMMA, X-ray) measurements were performed in different parts of the inner ear in tissues containing melanin. The tissues were shock-frozen, freeze-dried and embedded in Earle's medium (Spurr). The semi-thin sections used for microprobe analysis were cut dry in a conventional ultramicrotome and mounted on copper grids. Experimental manipulation of the endolymph ionic composition (increased Na+) stimulated the migration of melanosomes from the perinuclear region into the dendritic processes and the rearrangement of the dendritic processes in a close vicinity of the presumably transporting epithelia. The intracellular ion measurements showed the affinity of divalent ions for melanin (Mg++, Ca++, Sr++ and Ba++). It is proposed that melanin represents a physiologically important "reservoir" for essential trace elements and by its binding/release may play a key role in the enzymatically controlled processes of ionic pumps.

Animals↗