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At least 721 records · Page 40Linked to original sources
PubMed1978

[Oxygen supply of middle- and inner ear in experimental tubar occlusion (author's transl)].

1. The mucosa of the middle ear is not only supplied with oxygen from the blood but also from the air space of the middle ear. 2. Under physiological conditions, the perilymph is supplied partially with oxygen from the tympanic cavity. When the PO2 in the middle ear falls below 57 mm Hg, a net diffusion flux of oxygen from the perilymph to the middle ear induces a loss of oxygen from the inner ear. 3. A negative pressure of 25 mm Hg generated in the middle ear, causes a transudate. Subsequently, slight disturbances of microcirculation should occur in the mucosal membrane (pO2-histogram). More pronounced negative pressure lead to very distinct disturbances of microcirculation and local oxygen supply.

Animals↗
PubMed1986

The effect of butyl 2-cyanoacrylate on the middle and inner ear of the chinchilla.

Butyl 2-cyanoacrylate was placed on the oval and round window of the ear of the chinchilla and was also used as an adhesive for myringoplasty with autogenous muscle fascia. Butyl 2-cyanoacrylate was found to be difficult to manipulate and moderately toxic to the middle ear; there were occasional significant reactions in the inner ear.

Animals↗
PubMed1977

The effect of the removal of the endolymphatic duct and sac anlage upon organogenesis of the mammalian inner ear "in vitro": a preliminary report.

Preliminary observations of the effect of surgical excision of the endolymphatic duct and sac anlage in normal mouse embryo inner ear embryogenesis "in vitro" are reported. Otocysts of twelfth and thirteenth gestation day mouse embryos were grown in organ culture for 9 and 8 days respectively. The organ culture specimens of each gestational age group were further divided into otocysts with intact endolymphatic duct and sac anlages and otocysts that had their endolymphatic duct and sac anlages surgically excised prior to explantation. The resultant histological quantification of inner ear embryogenesis did not reveal any significant differences in morphogenesis, histodifferentiation of inner ear sensory structures or presence of endolymphatic hydrops in any of the organ culture specimens. It was concluded that in the system studied the absence of the endolymphatic duct and sac anlage did not have an effect on the organogenesis of the inner ear with the exception of the resultant lack of development of an endolymphatic duct and sac.

Animals↗
PubMed2005

Differential expression of genes within the cochlea as defined by a custom mouse inner ear microarray.

Microarray analyses have contributed greatly to the rapid understanding of functional genomics through the identification of gene networks as well as gene discovery. To facilitate functional genomics of the inner ear, we have developed a mouse inner-ear-pertinent custom microarray chip (CMA-IE1). Nonredundant cDNA clones were obtained from two cDNA library resources: the RIKEN subtracted inner ear set and the NIH organ of Corti library. At least 2000 cDNAs unique to the inner ear were present on the chip. Comparisons were performed to examine the relative expression levels of these unique cDNAs within the organ of Corti, lateral wall, and spiral ganglion. Total RNA samples were obtained from the three cochlear-dissected fractions from adult CF-1 mice. The total RNA was linearly amplified, and a dendrimer-based system was utilized to enhance the hybridization signal. Differentially expressed genes were verified by comparison to known gene expression patterns in the cochlea or by correlation with genes and gene families deduced to be present in the three tissue types. Approximately 22-25% of the genes on the array had significant levels of expression. A number of differentially expressed genes were detected in each tissue fraction. These included genes with known functional roles, hypothetical genes, and various unknown or uncharacterized genes. Four of the differentially expressed genes found in the organ of Corti are linked to deafness loci. None of these are hypothetical or unknown genes.

Animals↗
PubMed2006

Evolutionary changes in the cochlea and labyrinth: Solving the problem of sound transmission to the balance organs of the inner ear.

This review article examines the evolutionary adaptations in the vertebrate inner ear that allow selective activation of auditory or vestibular hair cells, although both are housed in the same bony capsule. The problem of separating acoustic stimuli from the vestibular end organs in the inner ear has recently reemerged with the recognition of clinical conditions such as superior canal dehiscence syndrome and enlarged vestibular aqueduct syndrome. In these syndromes, anatomical defects in the otic capsule alter the functional separation of auditory and vestibular stimuli and lead to pathological activation of vestibular reflexes in response to sound. This review demonstrates that while the pars superior of the labyrinth (utricle and semicircular canals) has remained fairly constant throughout evolution, the pars inferior (saccule and other otolith, macular, and auditory end organs) has seen considerable change as many adaptations were made for the development of auditory function. Among these were a relatively rigid membranous labyrinth wall, a variably rigid otic capsule, immersion of the membranous labyrinth in perilymph, a perilymphatic duct to channel acoustic pressure changes away from the vestibular organs, and different operating frequencies for vestibular versus auditory epithelia. Even in normal human ears, acoustic sensitivity of the labyrinth to loud clicks or tones is retained enough to be measured in a standard clinical test, the vestibular-evoked myogenic potential test.

Animals↗
PubMed2002

Estrogen receptors alpha and beta in the inner ear of the 'Turner mouse' and an estrogen receptor beta knockout mouse.

Estrogen receptors have earlier been shown in the normal mouse, rat and human inner ear. If estrogens are important in normal hearing and development of presbyacusis in the normal population is not known. However it is known that patients with Turner syndrome, where a lack of estrogens is one of the main characteristics, commonly develop an early presbyacusis. A 'Turner mouse' has been developed, as a model for the ear problems in Turner syndrome, and it shows otitis media and a premature aging of the hearing. Estrogen receptors exist in an alpha and a beta form. In this study inner ear tissue, from the Turner mouse and an estrogen receptor beta knockout mouse (betaERKO), was investigated regarding estrogen receptor alpha and beta using immunohistochemistry. Results show that the Turner mouse has the same pattern of inner ear labeling, both concerning the estrogen receptor alpha and beta, as that of a normal CBA/Ca mouse, with positive staining in the organ of Corti and spiral ganglion. The betaERKO mice show close to normal inner ear morphology and positive estrogen receptor alpha immunostaining at the same locations as the CBA/Ca mouse.

Animals↗
PubMedDate not supplied

Congenital malformation of the inner ear and recurrent meningitis. A case report.

Congenital deformities of the inner ear can be associated with meningitis and varying degrees of hearing loss or deafness. Recurrent periods of meningitis, sometimes lethal, are due to communication between the middle ear cavity and the subarachnoid space. Different types of congenital dysplasia have been classified earlier and we report a 3-year-old girl with unilateral deafness, episodes of meningitis and a malformation of the inner ear and the footplate of the stapes.

Child, Preschool↗
PubMed1993

Performance of the avian inner ear.

In spite of morphological similarities, the avian inner ear has apparently developed mechanisms of sound transduction that differ from the mammalian solution. This paper is a compilation of the present knowledge.

Acoustic Stimulation↗
PubMed1980

Scheibe dysgenesis of the inner ear.

A Scheibe-type dysgenesis of the inner ear was found in the temporal bones of an 85-year-old deaf-mute woman. Both temporal bones showed similar histopathological findings, which were confined mainly to the cochlea and saccule. The stria vascularis was atrophic and contained cysts with eosinophilic content throughout the cochlea. The scala media had disappeared owing to marked collapse of Reissner's membrane. The saccule showed collapse. Many eosinophilic spherical masses were observed in the area of the macula sacculi and attached to the saccular wall.

Aged↗
PubMed1997

Vasopressin and oxytocin receptor mRNAs are expressed in the rat inner ear.

The cause of endolymphatic hydrops, a characteristic finding in Menière's disease, is not known. To study the possible involvement of the neurohormones vasopressin and oxytocin in this condition, we investigated whether transcripts of the genes encoding the arginine vasopressin (AVP) and oxytocin receptors are expressed in the rat inner ear. Utilizing the reverse transcription-polymerase chain reaction (RT-PCR) method, primers specific for each receptor showed a single message band of the expected size in the rat inner ear. When the PCR products were cloned, the sequences were identical to those of the real-type (V2) AVP receptor and oxytocin receptor transcripts. The finding of vasopressin and oxytocin receptor mRNAs in the inner ear suggests that these neurohypophyseal hormones may have roles in the regulation of inner ear fluid. In particular, the presence of vasopressin receptor mRNA in the inner ear supports the hypothesis of a relationship between high plasma vasopressin levels and endolymphatic hydrops.

Animals↗
PubMed2001

Occurrence of NaK-ATPase isoforms during rat inner ear development and functional implications.

This study examined the presence of NaK-ATPase isoforms in the developing inner ear of the rat and studied the importance of functional subunit combinations in endolymph homeostasis. The findings were: (a) the combination alpha 1 beta 1 is found in epithelial, mesenchymal, and neural inner ear cells with an early starting expression 14 days postconception (dpc) in some endolymphatic sac cells; (b) from 1 day after birth (dab) expression of alpha 1 beta 2 is observed in marginal cells, vestibular dark cells, and certain vestibular nonsensory cells; (c) a transient expression of alpha 2 beta 1 is found in suprastrial fibrocytes and spiral ligament fibrocytes type II between 10 and 15 dab; (d) starting at 16 dpc the combination alpha 3 beta 1 is uniquely expressed in inner ear neural cells (as in other neural tissues). In conclusion, during development a switch from alpha 2 beta 1 towards alpha 1 beta 1 is observed in suprastrial fibrocytes and in spiral ligament fibrocytes type II. Thus, according to the biochemical characteristics of these combinations, a switch towards a NaK-ATPase with higher capacity takes place. In addition, prominent expression of the alpha 1 beta 2 combination in predominantly K+ ion transporting marginal and dark cells is in accordance with the characteristic of this combination and thus with the presumed function of these cells as important K+ suppliers for the endolymph. We believe this combination in certain vestibular nonsensory cells to be involved in K+ sensing. Early expression of the alpha 1 beta 1 combination in the endolymphatic sac, prior to that in the other parts of the inner ear, suggests that this structure may be involved to some extent in the development of the vestibulum and cochlea.

Animals↗
PubMedDate not supplied

Experimental studies on the role of vitamin A in the inner ear.

With the sole exception of the hair cells of the inner ear, where information is lacking, all special somatic afferent receptor cells have been shown to be dependent upon vitamin A for normal function. In view of the paucity of information on the role of vitamin A in the inner ear, three experiments were performed to examine this relationship. Temporal bone histopathology was studied in rats deprived of vitamin A. In a second experiment, vitamin A-deficient rats were maintained with vitamin A acid and the histopathology was studied under the light microscope. In the third experiment, a microfluorometric estimate of the content of vitamin A in the guinea pig cochlea was performed. A fluorescent compound with the exact spectral characteristics of vitamin A was found in the guinea pig cochlea at a concentration of 21.2 micrograms/gm, which is ten times the vitamin A concentration found in most other tissues.

Age Factors↗
PubMed1981

[Possible viral etiology of inner ear diseases (author's transl)].

After a short review of the possible viral etiology of inner ear diseases viral titers of 20 patients with inner ear problems are given. In the history of nearly all patients a viral infection was found. Inspite of some positive results in the titrations no significance was seen. Therefore we refute a relation between viral infection and inner ear troubles; for a practical point of view virological diagnostics is not indicated.

Antibodies, Viral↗
PubMedDate not supplied

Alpha B-crystallin in the mammalian inner ear.

To study the distribution of alpha B-crystallin, formalin-fixed preparations of the inner ear of the rat, cynomolgus monkey, rhesus monkey and human were stained immunohistochemically for alpha B-crystallin. In all cochleae investigated, intense staining for alpha B-crystallin was found in the inner and outer pillars as well as in the cells of Hensen and Claudius. In the primate inner ear, alpha B-crystallin was also present in the polygonal epithelial cells of Reissner's membrane, the interdental cells and some fibrocytes of the spiral limbus, epithelial cells of the outer spiral sulcus and the Schwann cells of the 8th nerve. In the primate stria vascularis, alpha B-crystallin was mainly seen in the basal cell layer and the adjacent cells of the connective tissue layer. alpha B-crystallin was found to be present in a large variety of cells in the inner ear surrounding the scala media.

Aged↗
PubMed1988

Barrier systems in the inner ear.

Because of the highly complicated function of the central nervous system and sensory organs, barrier systems have necessarily developed to ensure stability of the extracellular fluids bathing these organs. Several barrier systems which can influence the composition of the inner ear fluids are discussed. They are the 1) blood-labyrinth barrier, 2) cerebrospinal fluid-labyrinth barrier, and 3) middle ear-labyrinth barrier. The experimental data are shown to indicate that these barriers serve to protect the inner ear through selective permeability. Arachidonic acid metabolites, particularly compounds of the prostaglandin series, were identified in perilymph, and were increased by the administration of stress-related hormones, and decreased after aspirin injection. The inner ear fluid composition responds to the changes of the surrounding fluid containing compartments. However, the degree of response appears to depend on the level of changes induced in the surrounding compartments. The concept of a threshold concentration of toxic substances in middle ear effusion to induce inner ear damage is also proposed.

Body Fluid Compartments↗
PubMed1996

Intratympanic steroid treatment of inner ear disease and tinnitus (preliminary report).

Intratympanic instillation of Depo-Medrol (80 mg/cc), dexamethasone ophthalmic solution (1 mg/cc), or dexamethasone intravenous (4 mg/cc) solution produces improvement of cochlear function in certain patients with Meniere's disease, autoimmune inner ear disease and sudden sensorineural deafness. Tinnitus improved in 47%, most often in patients with Meniere's disease (9 of 15; 60%). The SRT improvement of greater than 10 dB or SD greater than 15% was documented in 41% (average improvement in SRT: 15 dB; SD: 24%). Patients with tinnitus and bilateral sensorineural hearing loss (i.e., presbycusis) did not benefit from the treatment. Prior to treatment with intratympanic medication, laser assisted tympanostomy with middle ear exploration, using otoendoscopy to determine the status of the round window niche and remove mucosal folds, helps in making the round window membrane accessible to local application of drops. Placing Gelfoam into the round window niche under direct vision, and using a Venturi Bobbin tube in the tympanic membrane, appears to be a satisfactory method for delivering medication to the inner ear fluids. The medication can be injected by the physician through the tube into the middle ear, or the patient can perform self-treatment at home, placing medication in the external auditory canal. A double-blind, cross-over study in patients with Meniere's disease is now in progress with Institutional Review Board (IRB) approval, which will be reported at a later date. This preliminary study has shown that intratympanic steroids may affect the symptoms of hearing loss and tinnitus in patients with various inner ear problems. Patients with Meniere's disease appear to respond in the highest percentage of cases. Hopefully, additional research will suggest the appropriate drugs which can be used to treat inner ear disease. Direct application of the drug to the round window membrane may increase the concentration in the inner ear fluids, thus avoiding the systemic effects.

Aged↗
PubMed1985

[Uptake and distribution of 14C-retinyl acetate in organs and sensory tissue (inner ear) of the guinea pig].

The uptake and chemical identification of 14C-retinyl acetate in the inner ear of the guinea-pig after oral administration is reported. For methodological reasons the experiment was carried out in vitamin A-deficient guinea-pigs. In the sensory tissues a time-dependent distribution was found similar to that in other organs. The chemical identification shows that the orally administered labeled retinyl acetate can be detected as retinyl palmitate in the membranous structures of the inner ear. This may be an indication for the ability of the inner ear tissues to esterize and probably store the transport form of vitamin A, retinol.

Administration, Oral↗
PubMed1995

Appearance of free radicals in the guinea pig inner ear after noise-induced acoustic trauma.

The emergence of superoxide anion radicals (O2-) in the guinea pig inner ear following acoustic trauma was investigated by histochemical methods. Five minutes after exposure to sound at 120-125 dB SPL for 3 h, an O2- reaction product was detected in the cochlea along the luminal membrane of the marginal cells of the stria vascularis. This reaction product could not be found at 30 min, but reappeared at 2 h. The first appearance of O2- is not explainable by our studies, but the second appearance may be related to recirculation of strial blood flow after blood flow stasis. The present observations raise the possibility that free radicals are produced in the inner ear after acoustic trauma and lead to inner ear damage.

Animals↗