Search results for "inner ear"
showing 10 items of 58 documents
Nitric oxide--a versatile key player in cochlear function and hearing disorders.
2012
Nitric oxide (NO) is a signaling molecule which can generally be formed by three nitric oxide synthases (NOS). Two of them, the endothelial nitric oxide synthase (eNOS) and the neural nitric oxide synthase (nNOS), are calcium/calmodulin-dependent and constitutively expressed in many cell types. Both isoforms are found in the vertebrate cochlea. The inducible nitric oxide synthase (iNOS) is independent of calcium and normally not detectable in the un-stimulated cochlea. In the inner ear, as in other tissues, NO was identified as a multitask molecule involved in various processes such as neurotransmission and neuromodulation. In addition, increasing evidence demonstrates that the NO-dependent…
Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig
1997
Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural anal…
Cadherin 23 is a component of the transient lateral links in the developing hair bundles of cochlear sensory cells
2005
AbstractCadherin 23 is required for normal development of the sensory hair bundle, and recent evidence suggests it is a component of the tip links, filamentous structures thought to gate the hair cells' mechano-electrical transducer channels. Antibodies against unique peptide epitopes were used to study the properties of cadherin 23 and its spatio-temporal expression patterns in developing cochlear hair cells. In the rat, intra- and extracellular domain epitopes are readily detected in the developing hair bundle between E18 and P5, and become progressively restricted to the distal tip of the hair bundle. From P13 onwards, these epitopes are no longer detected in hair bundles, but immunoreac…
Calcium-binding sites in the inner ear after pure-tone stimulation
1991
Five guinea pigs were exposed to an interrupted 90 dB SPL pure tone of 3.2 kHz for a total application time of 5 min. Following sound application all animals were decapitated and the cochleae were removed. After that, calcium-binding sites were located by the potassium pyroantimonate precipitation method. Another three animals served as control animals and did not receive the sound treatment. Findings confirmed previous studies showing the spatial arrangements of precipitate rich regions in the inner ear's two acellular structures (the basilar membrane and tectorial membrane) and the two cellular structures (the inner hair cells and Huschke's teeth). By using semiquantitative evaluation we …
Cause, pathogenesis, clinical manifestations and treatment of meniere's disease and endolymphatic hydrops
2019
Meniere's disease (MD) is characterized by the triad of fluctuating hearing loss, episodic vertigo and tinnitus, and by endolymphatic hydrops found on postmortem examinations. Since the description of endolymphatic hydrops by Hallpike and Cairns all the physiopathology of Meniere's symptoms have been based on assumption that the pathologic lesion was the cause of the symptoms. Paparella came out term and concept towards understanding of a disease was, "pathogenesis," which applies to all otological diseases, in general and in particular within this context of MD, which allows us to better understand this disease. After Schuknecht proposed the theory of membranous rupture causing the mixing …
Meniere's disease: Therapeutic options
2021
Meniere's disease (MD) is characterized by the triad of fluctuating hearing loss, episodic vertigo and tinnitus, and by endolymphatic hydrops found on postmortem examinations. Since the description of endolymphatic hydrops by Hallpike and Cairns, the physiopathology of Meniere's symptoms has been based on assumption that the pathologic lesion was the cause of the symptoms. Schuknecht proposed the theory of membranous rupture causing the mixing up of endolymph and perilymph leading to the occurrence of Meniere's symptoms. Lawrence confirmed this theory with research on experimental animals. In 1995 the AAO-HNS criteria defines "Possible MD (Grade D), Probable MD (Grade C), Definite MD (Grade…
Oxidative stress neuroinflammation and cellular stress response in sensorineural hearing loss: novel nutritional therapeutical approaches
2016
This study is intended to validate the hypothesis that changes in the redox state of glutathione, the major endogenous antioxidant, associated with the abnormal expression and activity of cytoprotective vitagenes, which in normal conditions are expressed only at low level may represent a critical factor, involved in the physiopathological changes associated to degenerative damage occurring in cochlear diseases. Moreover modulation of stress responsive vitagenes by nutritional antioxidants can be an effective therapeutic strategy to minimize consequences of oxidative stress associated to the pathogenesis and course of sensorineural hearing loss. One therapeutic approach can be antioxidant su…
Immunohistochemical localization of cyclooxygenase isoforms in the organ of Corti and the spiral ganglion cells of guinea pig cochlea.
2003
Prostaglandins have been used in experimental models and clinical studies for the therapy of sudden hearing loss and tinnitus with conflicting results. However, little is known about the rate-limiting enzymes of prostaglandin synthesis in the inner ear, the generally constitutively expressed cyclooxygenase 1 (COX-1) and the distress-inducible cycloxygenase 2 (COX-2). To extend our knowledge concerning the physiological expression and localization of these two enzymes, immunohistochemical stainings of the guinea pig cochlea were performed. Light microscopical analysis revealed a homogenous distribution of COX-1 within nearly all cell types of the organ of Corti, but no COX-1 expression in th…
Evidence for a possible NOS back-up system in the organ of Corti of the guinea pig
2003
Recently, the two Ca(2+)/calmodulin-regulated nitric oxide synthase isoforms, nNOS and eNOS, and NO itself have been identified in the cochlea of vertebrates using specific antibodies and a new fluorescence indicator. In order to acquire more information about the quantitative and spatial distribution of these two constitutively expressed NOS isoforms (cNOS) in the organ of Corti at the cellular and subcelluar levels, ultrathin sections of London resin (LR) White-embedded cochleae of the guinea pig were incubated with various concentrations of commercially available antibodies to nNOS and eNOS. The immunoreactivity was visualized by a gold-labeled secondary antibody and the amount of the im…
Association of Whirlin with Cav1.3 (α1D) Channels in Photoreceptors, Defining a Novel Member of the Usher Protein Network
2010
Contains fulltext : 88383.pdf (Publisher’s version ) (Closed access) PURPOSE: Usher syndrome is the most common form of hereditary deaf-blindness. It is both clinically and genetically heterogeneous. The USH2D protein whirlin interacts via its PDZ domains with other Usher-associated proteins containing a C-terminal type I PDZ-binding motif. These proteins co-localize with whirlin at the region of the connecting cilium and at the synapse of photoreceptor cells. This study was undertaken to identify novel, Usher syndrome-associated, interacting partners of whirlin and thereby obtain more insights into the function of whirlin. METHODS: The database of ciliary proteins was searched for proteins…