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 793 records · Page 44Linked to original sources
PubMed2000

A library of bacteriophage-displayed antibody fragments directed against proteins of the inner ear.

Bacteriophage display of antibodies provides a method for the generation of immunological reagents against rare and uncharacterized antigens. To ascertain the usefulness of this approach for the characterization of inner-ear proteins, we produced a bacteriophage-displayed antibody-fragment library directed against proteins from the bullfrog's sacculus. This library was probed for bacteriophage that bound to proteins present in a lysate of hair cells, the sensory receptors of the inner ear. The predominant bacteriophage clone after selection expressed an antibody fragment that recognized a single protein in the inner ear. This antigen occurred in both the nonsensory and sensory epithelia of the sacculus. The specificity of the antibody fragment indicates that our bacteriophage-displayed library provides a useful source of immunological tools that should facilitate the identification and biochemical characterization of novel proteins in the inner ear.

Animals↗
PubMed1999

Mapping of estrogen receptors alpha and beta in the inner ear of mouse and rat.

The sex hormone estrogen is classically known to influence growth, differentiation and function of peripheral tissues of both the female and male reproductive tract, mediated through the estrogen receptors alpha and beta. The influence of estrogens on the ear and hearing is yet not fully investigated, though some studies have suggested that estrogens may influence hearing functions. The aim of this study was to map eventual estrogen receptors in the inner ear in mouse and rat. Paraffin embedded sections of mouse and rat inner ear were immunostained with antibodies against estrogen receptors alpha and beta. Estrogen receptors alpha and beta containing cells were found in the inner ear, showing a unique distribution pattern, both in the auditory pathways and in the water/ion regulating areas. The presence of estrogen receptors indicates that estrogens may have an effect on the inner ear and hearing functions.

Animals↗
PubMed1991

Expression of cytokeratin polypeptides during development of the rat inner ear.

The expression of cytokeratin polypeptides in the different epithelia of the developing inner ear of the rat from 12 days post conception to 20 days after birth was analysed immunohistochemically, using a panel of monoclonal antibodies. Throughout the development of the complex epithelial lining of the inner ear originating from the otocyst epithelium, only cytokeratins which are typical of simple epithelia were expressed. Cytokeratins 8, 18, and 19 were detectable shortly after the formation of the otocyst from the ectoderm (12 dpc), whereas cytokeratin 7 expression was delayed and first appeared in the vestibular portion and subsequently in the developing cochlear duct. During the development of the different types of specialized cells, differentiation-dependent modulation of the cytokeratin expression patterns was observed. In the mature inner ear, the specialized cell types displayed a function-related cytokeratin expression profile, both in the cochlear and vestibular portion. Cytokeratin expression in the flat epithelium of the vestibular portion suggests a more complex composition of this epithelium than has been established from routine morphology. Remarkably, the cochlear sensory cells were apparently devoid of cytokeratins, but no final conclusion could be drawn on the presence of cytokeratins in the sensory cells of the vestibular portion, because of the difficulty to delineate the cell borders between sensory cells and supporting cells.

Animals↗
PubMed2006

Basic helix-loop-helix gene Hes6 delineates the sensory hair cell lineage in the inner ear.

The basic helix-loop-helix (bHLH) gene Hes6 is known to promote neural differentiation in vitro. Here, we report the expression and functional studies of Hes6 in the inner ear. The expression of Hes6 appears to be parallel to that of Math1 (also known as Atoh1), a bHLH gene necessary and sufficient for hair cell differentiation. Hes6 is expressed initially in the presumptive hair cell precursors in the cochlea. Subsequently, the expression of Hes6 is restricted to morphologically differentiated hair cells. Similarly, the expression of Hes6 in the vestibule is in the hair cell lineage. Hes6 is dispensable for hair cell differentiation, and its expression in inner ear hair cells is abolished in the Math1-null animals. Furthermore, the introduction of Hes6 into the cochlea in vitro is not sufficient to promote sensory or neuronal differentiation. Therefore, Hes6 is downstream of Math1 and its expression in the inner ear delineates the sensory lineage. However, the role of Hes6 in the inner ear remains elusive.

Animals↗
PubMed2003

Real-time quantitative RT-PCR for low-abundance transcripts in the inner ear: analysis of neurotrophic factor expression.

Real-time quantitative reverse transcription-PCR is a highly sensitive technology that allows high throughput quantification of gene expression. Application of this technique to the inner ear is potentially very important, but is not straightforward because tissue harvesting can be challenging, RNA yield from individual inner ears is low, and cDNA synthesis from scant RNA can be inefficient. To overcome these challenges, we tested many parameters and reagents, and developed an approach to reliably quantitate small changes in low-abundance transcripts. Using this technique we demonstrate the presence and quantify amounts of the neurotrophic factors neurotrophin 3 (NT-3), brain-derived neurotrophic factor (BDNF) and glial cell-line-derived neurotrophic factor (GDNF), in the cochlea and vestibular end organs of postnatal murine inner ear (P26). We show that out of the factors tested, BDNF is the only one differentially expressed between the cochlea and vestibular end organs, being 23.4+/-0.3 times more abundant in the vestibular end organs. Within the cochlea, GDNF gene expression is 4.9+/-0.2 times greater than NT-3 expression. Within the combined vestibular end organs, BDNF expression is 43.0+/-1.5 times greater than NT-3 expression. Our results suggest that neurotrophic factors continue to play a role in the postnatal inner ear, in addition to their previously shown essential role during development.

Animals↗
PubMed1985

A glycol methacrylate method for the routine histologic evaluation of rat inner ear.

A method has been developed for the histologic evaluation of rat inner ear using glycol methacrylate (GMA) and steel knife sectioning. The necropsy, fixation, and histologic techniques described are not so complex and difficult as to preclude their routine use. The method is particularly useful in studies in which the entire inner ear of a large number of animals must be evaluated histologically.

Animals↗
PubMed1998

Programmed cell death in the developing epithelium of the mouse inner ear.

Programmed cell death is as essential to development as is proliferation. Thus, the objective of this study was to elucidate the spatiotemporal involvement of programmed cell death in the development of the inner ear epithelia. Programmed cell death is seen in situ as apoptosis. A time-sequence study was performed on the distribution of apoptosis during the development of the inner ear epithelia of the mouse using the TdT-mediated dUTP-biotin nick labeling (TUNEL) method to detect apoptosis histochemically. Apoptosis occurred during the early stages of development of the inner ear and took place earlier in the organs of equilibrium than in the cochlea. These periods corresponded to those of active proliferation of epithelial cells in the inner ear. Since cell-cell interactions change after the removal of neighboring cells by apoptosis, apoptosis may influence cytodifferentiation.

Animals↗
PubMed2003

The presence of opioid receptors in rat inner ear.

Opioid peptides have been identified in the inner ear but relatively little information is available about the expression and distribution of their receptors. The aim of the present study was therefore to identify and localize the mu (MOR), delta (DOR) and kappa (KOR) opioid receptor subtypes within the rat cochlea. The expression of these opioid receptor subtypes was determined by reverse transcriptase-polymerase chain reaction followed by nested polymerase chain reaction analysis. Amplification of RNAs from rat cerebral cortex (positive control) and rat cochlea with MOR, DOR and KOR primers resulted in products of the predicted lengths, 564, 356 and 276 bp, respectively. Restriction digestion confirmed the identity of these products. All three receptor subtypes were identified in the cochlea and further characterized by immunocytochemistry. DOR and KOR immunoreactivity was found in inner and outer hair cells, bipolar cells of the spiral ganglion and interdental cells of the limbus. In contrast, no MOR immunoreactivity was observed in the inner and outer hair cells, and interdental cells. All three types of receptor fibers were also detected in the bipolar cells and nerve fibers within the spiral ganglion. In addition, MOR- and KOR-containing nerve fibers were observed in the limbus. These findings are the first report of the presence of all three classical opioid receptors in the inner ear and suggest that these receptors may have both presynaptic and postsynaptic roles.

Animals↗
PubMedDate not supplied

Immunobiology of the inner ear.

Immunologic mechanisms may play an etiologic role in ear disease, and many disorders long considered idiopathic are now being examined for such an immunologic basis. While it is possible that many of these idiopathic diseases will ultimately prove not to be immunologically mediated, the outcome of these research endeavors will certainly clarify some of the basic mechanisms of host immunity involved in ear disease. The immunobiology of diseases that affect the inner ear is discussed from both experimental and clinical viewpoints.

Animals↗
PubMed1997

Effect of Pseudomonas aeruginosa exotoxin A on inner ear function.

Electrophysiological changes were studied in the albino rat following instillation of Pseudomonas aeruginosa exotoxin A into the middle ear cavity through the tympanic membrane. Hearing threshold was measured by a burst-elicited, frequency-specific auditory brainstem response (ABR) technique prior to exposure, then 24 and 48 h, 5 days, 2 and 4 weeks after the toxin instillation. A single dose (1 microgram/20 microliters) of Pseudomonas aeruginosa exotoxin A raised the ABR threshold over the whole frequency range, by 5-25 dB, particularly in the high tones. All threshold shifts were of combined conductive and cochlear type, reversible, with deterioration starting at 24-48 h and recovery at 2-4 weeks. Effusion of serous fluid occurred at 24 or 48 h, resulting in conductive hearing loss. Latency/intensity curves revealed a cochlear component in addition to conductive hearing loss. Morphological examination by SEM showed slight and inconsistent derangement of OHCs. It is concluded that Pseudomonas aeruginosa exotoxin A causes middle ear inflammation, facilitating penetration to the inner ear and that this toxin also reversibly affects cochlear function.

ADP Ribose Transferases↗
PubMed1998

Clinical diagnoses associated with histologic findings of fibrotic tissue and new bone in the inner ear.

Fibrotic tissue or new bone occurs following inner ear inflammation, fracture, or surgery. The prevalence is unknown and was investigated using the National Temporal Bone, Hearing and Balance Pathology Resource Registry database. A search yielded 264 temporal bones with diagnoses of otosclerosis, tumor, Meniere's disease, meningitis, labyrinthitis, chronic otitis media, autoimmune disease, temporal bone fracture, or sensorineural hearing loss. All autoimmune cases contained some new bone, whereas only 20% to 30% of the labyrinthitis/meningitis cases were reported to contain new bone. Otosclerosis, Meniere's disease, and otitis media had relatively few cases containing new bone. Although new bone may derive from surgical trauma, it is also likely to be a result of the disease process. It seems that all these disease processes may contain a common feature that acts as a stimulus to induce fibrosis or bone growth in the inner ear.

Autoimmune Diseases↗
PubMed1998

Molecular organization of a type of peripheral glutamate synapse: the afferent synapses of hair cells in the inner ear.

The synapses between sensory cells in the inner ear and the afferent dendrites of ganglion cells are well suited to investigations of fundamental mechanisms of fast synaptic signalling. The presynaptic elements can be isolated for electrophysiological and functional studies while the synapses can be easily recognized in the electron microscope due to their distinct morphological features. This allows for a broader range of correlative functional and structural analyses than can be applied to synapses in the central nervous system (CNS). As in most fast excitatory synapses in the CNS the transmitter in the afferent hair cell synapses appears to be glutamate or a closely related compound. Recent studies have revealed many of the key molecular players at this type of synapse and how they are spatially and functionally coupled. By use of high resolution immunogold cytochemistry it has been shown that AMPA glutamate receptors are specifically expressed in the postsynaptic specialization of afferent hair cell synapses (except at those established by outer hair cells in the organ of Corti) and that their density varies as a function of the distance from the release sites (demonstrated for the afferent contacts of inner hair cells). The glutamate transporter GLAST is localized in supporting cell membranes and concentrated in those membrane domains that face the synaptic regions. Glutamine synthetase and phosphate-activated glutaminase--which are responsible for the interconversion of glutamate and glutamine--are selectively localized in non-neuronal and neuronal elements, respectively. Taken together with quantitative immunogold data on the cellular compartmentation of glutamate and glutamine the above findings suggest that the sensory epithelia in the inner ear sustain a cycling of glutamate carbon skeletons. In this process, the supporting cells may carry out functions analogous to those of glial cells in the CNS. Functional and morphological analyses of the presynaptic membrane indicate that L-type Ca(2+)-channels and Ca(2+)-activated K(+)-channels are colocalized and clustered at the active zone. Influx through the L-type channels triggers synaptic release and their close spatial association with Ca(2+)-activated K(+)-channels appears to be critical for frequency tuning. The focal expression of different Ca(2+)-channels combined with a high intracellular buffering capacity permits several Ca(2+)-signalling pathways to operate in parallel without undue interference. The molecular organization of the afferent hair cell synapses reflects the functional demand for speed and precision and attests to the ability of the pre- and postsynaptic elements to target and anchor key proteins at specific membrane domains.

Animals↗
PubMedDate not supplied

Experimental cytomegalovirus infection: viremic spread to the inner ear.

The entry route of viruses into the inner ear is still controversial. Guinea pig cytomegalovirus (CMV) has been used to create an animal model of systemic infection as well as labyrinthitis. In this study, seronegative guinea pigs were administered intracardiac inoculations of varying doses of guinea pig CMV. After three or eight days, the animals were killed and necropsy specimens examined for viral antigen. In the specimens examined three days after inoculation, no label was seen in the cochlea. However, label was found in the spleen with doses of 100 microL, and also in the liver in animals inoculated with 300 microL of virus. After eight days, an animal that received 200 microL of the virus showed labeling in the modiolar blood vessels and perivascular infiltrates. Two of the four animals that received 300 microL of the virus showed labeling in spiral ganglion cells. None of the animals showed viral antigen within the stria vascularis, nor were there signs of acute labyrinthitis. At eight days, animals inoculated with greater than 100 microL of virus showed labeled cells in multiple organs. These data suggest that the entry route of guinea pig cytomegalovirus into the inner ear might involve viremic spread to modiolar blood vessels and subsequent spread to spiral ganglion cells.

Animals↗
PubMed1978

The effects of indomethacin on inner ear fluids and morphology.

Metabolic disturbances may affect inner ear fluid homeostasis in various ways. The membrane sodium-potassium pump must play a role in this homeostasis, and as this pump derives energy from A.T.P. it may also depend somewhat on the presence of prostaglandins, through their stimulatory effect on the adenylate cyclase system. Salicylates suppress prostaglandins; and Indomethacin is even more potent in this respect. Could the temporary ototoxic effects of salicylates and Indomethacin be due to prostaglandin suppression? Further, could energy system problems involving prostaglandins be related to the development of endolymphatic hydrops? These questions prompted this study. Sublethal doses of Indomethacin were given to 14 guinea pigs in order to maximally suppress prostaglandins. Samples of perilymph and endolymph were analyzed for sodium and potassium concentrations and compared to normal controls. No significant differences were found in either acute (two to 24 hour) or chronic (three week) experiments. Light microscopic examination of serially sectioned cochleae in similarly treated animals showed, in a few cases, somewhat questionable distension of Reissner's membrane. Electron microscopy or the organ of Corti did not demonstrate any abnormalities. The study suggests that Indomethacin does not produce significant inner ear electrolyte shifts or endolymphatic distension, at least over the short term.

Animals↗
PubMed1995

Amiloride-sensitive Na+ channel-like immunoreactivity in the luminal membrane of some non-sensory epithelia of the inner ear.

Some non-sensory epithelia of the inner ear were examined for the localization of immunoreactivity to polyclonal antibodies raised against amiloride-sensitive Na+ channels from the bovine kidney. The pre-embedding immunogold technique was used for this purpose. Labelings were found on the membrane of the endolymphatic surface of strial marginal cells, epithelial cells of spiral prominence and Reissner's membrane, and ampullar dark cells. In contrast, no labeling was found on the luminal membrane of mesothelial cells of Reissner's membrane, the cells lining the supra-strial perilymphatic space, transitional cells and ampullar ceiling cells. Since the antibodies used may also label non-selective cation channels and non-functional sodium channel precursors as suggested by others, it was not possible to determine the labelings are solely due to amiloride-sensitive Na+ channels. However, the observed result was consistent with the previous studies that amiloride blocks ion transport in strial marginal cells and the semicircular canal. It is therefore likely that the observed labeling includes amiloride-sensitive Na+ channels. These labeled ion channels in a variety of epithelial cells lining the endolymphatic space could be important in the inner ear fluid regulation.

Amiloride↗
PubMed1999

[Hair cell regeneration in a chicken's inner ear after damage due to exposure to industrial noise].

In mammals, the damage to the hair cells of the inner ear due to exposure to noise or other ototoxic agents is irreversible. In fish, reptiles and birds, however, the hair cells may regenerate, probably from the supporting cells. This regeneration process in the inner ear is being intensively examined in animals in the hope of curing the sensorineural hearing loss in human subjects in future. The aim of the study was to assess hair cell regeneration in the inner ear of chicks after exposure to industrial noise, depending on the level of exposure. The birds were exposed either to the noise at the level of 110 dB (A), 4 hours a day, for 5 consecutive days, or at the level of 125 dB (A), 8 hours a day, for 5 consecutive days. The results confirm that the regeneration starts immediately during the period of recovery from acoustic trauma, and the supporting cells are the main source for new, developing hair cells. Moreover, we found that the complete damage to hair cells is not necessary to the proliferation of supporting cells and that the intensity of proliferation of these cells depends on the level and time of exposure.

Animals↗
PubMed1990

Potentiation of inner ear damage following electron beam irradiation with CDDP administration.

This study was designed to examine the combined ototoxic effects of cisplatin, an antitumor platinum compound, administration and electron beam irradiation on the inner ear of guinea pigs, histopathologically. One group received saline solution 4 ml/kg/day and the other group received cisplatin of 2 mg/4 ml/kg/day for five consecutive days. The right temporal bones of all animals of both groups were exposed to the electron beam of 14 Gy/day 3 hours after the daily injection of saline or cisplatin. All animals were sacrificed for inner ear histopathological findings 21 days after the last injection. A combination of cisplatin administration and electron beam irradiation produced a severe potentiation of the outer hair cell damage with no inner hair cell damage. Therefore, in treatment of head and neck carcinomas, it is important to pay attention to inner ear damage caused by combination therapy of cisplatin and electron beam irradiation which involves the inner ear.

Animals↗
PubMed1995

Expression of S-100 protein in the human fetal inner ear.

The expression of S-100 protein was analyzed in the human fetal inner ear using immunohistochemical methods. In the 11-week-old human fetus, the cochlea was almost negative for S-100 protein, whereas in the 14- and 15-week-old fetuses, the spiral ligament, Reissner's membrane and spiral limbus were positive for the protein. These results suggest that S-100 protein may be a reliable marker for determining functional maturation of the fetal cochlea and the inner ear. In the 11-, 14- and 15-week fetuses, the epithelial cells of the endolymphatic sac were labelled with S-100 protein. These findings demonstrate that the endolymphatic sac, spiral limbus and spiral ligament in the fetal inner ear have a high activity of S-100 protein, with this presence possibly related to fluid and ion transport of endolymph.

Cochlea↗