The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Ruediger Thalmann - One of the best experts on this subject based on the ideXlab platform.
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immunogold tem of otoconin 90 and otolin relevance to mineralization of Otoconia and pathogenesis of benign positional vertigo
Hearing Research, 2012Co-Authors: Leonardo R. Andrade, Bechara Kachar, Ulysses Lins, Marcos Farina, Ruediger ThalmannAbstract:Implementation of the deep-etch technique enabled unprecedented definition of substructural elements of Otoconia, including the fibrillar meshwork of the inner core with its globular attachments. Subsequently the effects of the principal soluble Otoconial protein, otoconin 90, upon calcite crystal growth in vitro were determined, including an increased rate of nucleation, inhibition of growth kinetics and significant morphologic changes. The logical next step, ultrastructural localization of otoconin 90, by means of immunogold TEM in young mature mice, demonstrated a high density of gold particles in the inner core in spite of a relatively low level of mineralization. Here gold particles are typically arranged in oval patterns implying that otoconin 90 is attached to a scaffold consisting of the hexagonal fibrillar meshwork, characteristic of otolin. The level of mineralization is much higher in the outer cortex where mineralized fiber bundles are arranged parallel to the surface. Following decalcification, gold particles, as well as matrix fibrils, presumed to consist of a linear structural phenotype of otolin, are aligned in identical direction, suggesting that they serve as scaffold to guide mineralization mediated by otoconin 90. In the faceted tips, the level of mineralization is highest, even though the density of gold particles is relatively low, conceivably due to the displacement by the dense mineral phase. TEM shows that individual crystallites assemble into iso-oriented columns. Columns are arranged in parallel lamellae which convert into mineralized blocks for hierarchical assembly into the complex Otoconial mosaic. Another set of experiments based on immunogold TEM in young mice demonstrates that the fibrils interconnecting Otoconia consist of the short chain collagen otolin. By two years of age the superficial layer of mouse Otoconia (corresponding to mid-life human) has become demineralized resulting in weakening or loss of anchoring of the fibrils interconnecting Otoconia. Consequently, Otoconia detached from each other may be released into the endolymphatic space by minor mechanical disturbances. In humans, benign positional vertigo (BPV) is believed to result from translocation of Otoconia from the endolymphatic space into the semi-circular canals rendering their receptors susceptible to stimulation by gravity causing severe attacks of vertigo. The combinations of these observations in humans, together with the presented animal experiments, provide a tentative pathogenetic basis of the early stage of BPV.
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Immunogold TEM of otoconin 90 and otolin – relevance to mineralization of Otoconia, and pathogenesis of benign positional vertigo
Hearing research, 2012Co-Authors: Leonardo R. Andrade, Bechara Kachar, Ulysses Lins, Marcos Farina, Ruediger ThalmannAbstract:Implementation of the deep-etch technique enabled unprecedented definition of substructural elements of Otoconia, including the fibrillar meshwork of the inner core with its globular attachments. Subsequently the effects of the principal soluble Otoconial protein, otoconin 90, upon calcite crystal growth in vitro were determined, including an increased rate of nucleation, inhibition of growth kinetics and significant morphologic changes. The logical next step, ultrastructural localization of otoconin 90, by means of immunogold TEM in young mature mice, demonstrated a high density of gold particles in the inner core in spite of a relatively low level of mineralization. Here gold particles are typically arranged in oval patterns implying that otoconin 90 is attached to a scaffold consisting of the hexagonal fibrillar meshwork, characteristic of otolin. The level of mineralization is much higher in the outer cortex where mineralized fiber bundles are arranged parallel to the surface. Following decalcification, gold particles, as well as matrix fibrils, presumed to consist of a linear structural phenotype of otolin, are aligned in identical direction, suggesting that they serve as scaffold to guide mineralization mediated by otoconin 90. In the faceted tips, the level of mineralization is highest, even though the density of gold particles is relatively low, conceivably due to the displacement by the dense mineral phase. TEM shows that individual crystallites assemble into iso-oriented columns. Columns are arranged in parallel lamellae which convert into mineralized blocks for hierarchical assembly into the complex Otoconial mosaic. Another set of experiments based on immunogold TEM in young mice demonstrates that the fibrils interconnecting Otoconia consist of the short chain collagen otolin. By two years of age the superficial layer of mouse Otoconia (corresponding to mid-life human) has become demineralized resulting in weakening or loss of anchoring of the fibrils interconnecting Otoconia. Consequently, Otoconia detached from each other may be released into the endolymphatic space by minor mechanical disturbances. In humans, benign positional vertigo (BPV) is believed to result from translocation of Otoconia from the endolymphatic space into the semi-circular canals rendering their receptors susceptible to stimulation by gravity causing severe attacks of vertigo. The combinations of these observations in humans, together with the presented animal experiments, provide a tentative pathogenetic basis of the early stage of BPV.
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Development and Maintenance of Otoconia
Annals of the New York Academy of Sciences, 2006Co-Authors: Ruediger Thalmann, Elena G Ignatova, David M Ornitz, Bechara Kachar, Isolde ThalmannAbstract:The first part of this review deals with recent advances in the understanding of biochemical mechanisms of Otoconial morphogenesis. Most important in this regard is the molecular characterization of otoconin 90, the principal matrix protein of mammalian calcitic Otoconia, which was found to be a homologue of the phospholytic enzyme PLA2. The unique and unexpected expression pattern of this protein required radical rethinking of traditional concepts. The new data, when integrated with existing information, provide a rational basis for an explanation of the mechanisms leading to crystal nucleation and growth. Based on this information, a hypothetical model is presented that posits interaction of otoconin 90 with microvesicles derived from the supporting cells as a key event in the formation of Otoconia. The second part of the review is directed at the controversial subject of maintenance of mature Otoconia and systematically analyzes the available indirect information on this topic. A synthesis of these theoretical considerations is viewed in relation to the pathogenesis of the important otoneurologic entities of BPPN and senile Otoconial degeneration. The last part of the review deals with several animal models that promise to help elucidate normal and abnormal mechanisms of Otoconial morphogenesis, including mineral deficiencies, mutations with selective Otoconial agenesis, as well as targeted disruption of essential genes.
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Molecular mechanisms underlying ectopic Otoconia-like particles in the endolymphatic sac of embryonic mice.
Hearing research, 2004Co-Authors: Elena G Ignatova, Isolde Thalmann, David M Ornitz, Ruediger ThalmannAbstract:Otoconin-90, the principal Otoconial matrix protein, provided a tool to investigate the molecular mechanism of Otoconial morphogenesis. The endolymphatic sac of the embryonic chick and guinea pig contain Otoconia. Here, we show that the embryonic mouse transiently expresses ectopic Otoconia in the endolymphatic sac. Massive precipitate of otoconin-90-positive material is detectable in the lumen of the endolymphatic sac between embryonic day 14.5 and 17.5 with frequent accretion into more heavily staining Otoconia-like particles. Otoconin-90 was also localized at the surface and the interior of epithelial cells lining the endolymphatic sac as well as incorporated into free floating cells. In contrast, in situ hybridization failed to detect mRNA in the endolymphatic duct and sac, even though the adjacent nonsensory vestibular structures are heavily stained. Because of ample expression of otoconin-90 protein in the absence of the corresponding mRNA, we conclude that the luminal otoconin-90 is imported via longitudinal flow from the vestibular compartments, where both mRNA and protein are strongly expressed. Because of absence of mRNA, the expression of the corresponding protein by the epithelia lining the endolymphatic sac can only be explained by a resorptive process, as previously proposed on the basis of the movement of luminal macromolecules. The data do not support the previous hypothesis that the transient expression of Otoconia-like particles of the endolymphatic sac represents a vestigial phenomenon from the amphibian stage, since amphibia express ample mRNA encoding otoconin-22 in the endolymphatic sac system.
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The Otoconia of the guinea pig utricle: internal structure, surface exposure, and interactions with the filament matrix.
Journal of structural biology, 2000Co-Authors: Ulysses Lins, Isolde Thalmann, Ruediger Thalmann, Marcos Farina, Mauricio Kurc, Gavin P. Riordan, Bechara KacharAbstract:A unique feature of the vertebrate gravity receptor organs, the saccule and utricle, is the mass of biomineral structures, the Otoconia, overlying a gelatinous matrix also called "Otoconial membrane" on the surface of the sensory epithelium. In mammals, Otoconia are deposits of calcium carbonate in the form of composite calcite crystals. We used quick-freezing, deep etching to examine the Otoconial mass of the guinea pig utricle. The deep-etching step exposed large expanses of intact and fractured Otoconia, showing the fine structure and relationship between their internal crystal structure, their surface components, and the filament matrix in which they are embedded. Each otoconium has a compact central core meshwork of filaments and a composite outer shell of ordered crystallites and macromolecular aggregates. A distinct network of 20-nm beaded filaments covers the surface of the Otoconia. The Otoconia are interconnected and secured to the gelatinous matrix by surface adhesion and by confinement within a loose interOtoconial filament matrix. The gelatinous matrix is a dense network made of yet another type of filament, 22 nm in diameter, which are cross-linked by shorter filaments, characteristically 11 nm in diameter. Our freeze-etching data provide a structural framework for considering the molecular nature of the components of the Otoconial complex, their mechanical properties, and the degree of biological versus chemical control of Otoconia biosynthesis.
Masaya Takumida - One of the best experts on this subject based on the ideXlab platform.
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Formation and fate of giant Otoconia of the guinea pig following streptomycin intoxication.
Acta oto-laryngologica, 1997Co-Authors: Masaya Takumida, De Ming Zhang, Koji Yajin, Yasuo HaradaAbstract:Formation and fate of abnormal (giant) Otoconia of the guinea pig following streptomycin intoxication were investigated using scanning electron microscopy. The giant Otoconia formed as multifaceted morphology in their early developmental period. They grew up the the transitional type and finally to the cylindrical type. It has been suggested that the giant Otoconia found following streptomycin intoxication may be formed mainly by dissolution of normal Otoconia due to the loss of environmental calcium, followed by recrystallization as giant crystals. These phenomena seemed to be closely related to the Otoconial dynamics which may regulate calcium ion homeostasis of the endolymph.
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Electron probe X-ray microanalysis of Otoconia in the guinea pig inner ear.
ORL; journal for oto-rhino-laryngology and its related specialties, 1997Co-Authors: Masaya Takumida, De Ming ZhangAbstract:By using the electron probe X-ray microanalysis technique, the elemental composition of Otoconia was analyzed in the normal adult pigmented guinea pig. In the X-ray spectra of Otoconia, the most abundant element was Ca, but significant peaks for P, S, Cl and K were also detected. The comparison of the elemental composition in the utricular and saccular Otoconia did not show any significant difference. Regression analysis revealed that the concentrations of Ca and K are related by a linear function in both the utricular and saccular Otoconia. Analysis of Otoconia of different sizes showed that there were no differences in Ca concentration in small, normal and large Otoconia. The comparison of other elemental compositions revealed that P, S, Cl and K in the central part of saccular small Otoconia showed higher concentrations than those of normal or large Otoconia. P, S, Cl and K in the utricular small Otoconia showed relatively higher concentrations. These findings may indicate that the small Otoconia are immature or newly generated.
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In vitro calcium ion turnover in Otoconia of the guinea pig
Auris nasus larynx, 1997Co-Authors: Masaya Takumida, De Ming Zhang, Koji YajinAbstract:In vitro calcium ion turnover into Otoconia of adult guinea pigs was investigated by the use of tetracycline. The incubation in tetracycline in vitro clearly demonstrated the deposition of tetracycline (fluorescence) on the outer surface of Otoconia. Levels of Ca2+ uptake in utricular Otoconia were higher than those in saccular Otoconia. In vitro uptake and/or exchange of Ca2+ was greater in fluid with a high K+/Na+ ratio than in fluid in which the ratio was low. It has been thus indicated that a high K+/Na+ ratio in normal endolymph should be more suitable for Ca2+ uptake and/or exchange to maintain the ionic environment in the inner ear. Sodium dodecyl sulfate treatment of Otoconia increased the Ca2+ uptake. The ability of the Otoconia to take up Ca2+ appears to decline with age. It has been indicated that the organic matrix of Otoconia may be one of the inhibitory factors for Ca2+ uptake in old animals.
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Electron probe X-ray microanalysis of Otoconia in guinea pig inner ear : A comparison between young and old animals
Acta oto-laryngologica, 1997Co-Authors: Masaya Takumida, De Ming ZhangAbstract:Using the electron probe X-ray microanalysis technique, the elemental composition of Otoconia was analysed in both young and old normal pigmented guinea pigs. Calcium concentration in both the utricular and the saccular Otoconia was lower in the old animals, which indicates that the loss of calcium from Otoconia and/or decrease in calcium ion uptake may occur in the old animals. The present study has established that calcium and other elements (P, S, Cl and K) in the Otoconia of the young animals are related via a linear function, indicating that P, S, Cl and K are present in the mineral phase of the Otoconia. The associations of Ca-P, Ca-K and Ca-S are not maintained in the old animals. It has been suggested that the aging phenomenon may influence the ionic metabolism in the vestibular end organs resulting in the altered mineral composition of Otoconia.
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Polychromatic labeling of Otoconia for the investigation of calcium turnover.
ORL; journal for oto-rhino-laryngology and its related specialties, 1997Co-Authors: Masaya Takumida, De Ming Zhang, Koji Yajin, Yasuo HaradaAbstract:The calcium ion turnover into Otoconia of adult guinea pigs was investigated by the use of different fluorochromes, i.e. tetracycline (TC), calcein (Cal) and alizarin complexone (AC). The administration of all fluorochromes induced yellow (TC), green (Cal) and red (AC) fluorescence on the outer surface of Otoconia, respectively. Sequential polychromatic labeling with AC followed by TC induced only red fluorescence after 1 week administration of TC, combined fluorescence after 2 weeks administration of TC and only yellow fluorescence after more than 3 weeks of administration of TC. The Otoconia labeled with both AC and TC showed red fluorescence on the side faces of Otoconia and yellow fluorescence on the terminal faces. These results may indicate the existence of a dynamic exchange of calcium ions in the Otoconia and this exchange is mainly restricted to the terminal faces. The sequential polychromatic labeling may thus be of great use for the further investigation of the calcium dynamics of Otoconia.
Jeffrey S Batten - One of the best experts on this subject based on the ideXlab platform.
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the morphogenic features of Otoconia during larval development of cynops pyrrhogaster the japanese red bellied newt
Hearing Research, 1995Co-Authors: Peter S Steyger, Michael L Wiederhold, Jeffrey S BattenAbstract:Otoconia are calcified protein matrices within the gravity-sensing organs of the vertebrate vestibular system. Mammalian Otoconia are barrel-shaped with triplanar facets at each end. Reptilian Otoconia are commonly prismatic or fusiform in shape. Amphibians have all three Otoconial morphologies, barrel-shaped Otoconia within the utricle, with prismatic and fusiform Otoconia in the saccule. Scanning electron microscopy revealed a sequential appearance of all three Otoconial morphologies during larval development of the newt, Cynops pyrrhogaster. The first Otoconia appear within a single, developing otolith, and some resemble adult barrel-shaped Otoconia. As the larvae hatch, around stages 39-42, the single otolith divides into two anatomically separate regions, the utricle and saccule, and both contain Otoconia similar to those seen in the single otolith. Throughout development, these Otoconia may have variable morphologies, with serrated surfaces, or circumferential striations with either separated facets or adjacent facets in the triplanar end-regions. Small fusiform Otoconia occur later, at stage 51, and only in the saccule. Prismatic Otoconia appear later still, at stage 55, and again only in the saccule. Thus, although prismatic Otoconia are the most numerous in adult newts, it is the last vestibular Otoconial morphology to be expressed.
Sherri M. Jones - One of the best experts on this subject based on the ideXlab platform.
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Mechanism Underlying the Effects of Estrogen Deficiency on Otoconia.
Jaro-journal of The Association for Research in Otolaryngology, 2018Co-Authors: Liping Yang, Yan Zhang, Sarath Vijayakumar, Sherri M. Jones, Yunxia Wang LundbergAbstract:Otoconia-related vertigo and balance deficits, particularly benign paroxysmal positional vertigo (BPPV), are common. Our recent studies in humans show that, while BPPV prevalence greatly increases with age in both genders, peri-menopausal women are especially susceptible. In the present study, we show that bilateral ovariectomized (OVX) mice have significant balance behavioral deficits, and that estrogen deficiency compromises Otoconia maintenance and anchoring by reducing the expression of Otoconial component and anchoring proteins. There is ectopic debris formation in the ampulla under estrogen deficiency due to aberrant matrix protein expression. Furthermore, phytoestrogen is effective in rescuing the Otoconia abnormalities. By comparing the expression levels of known estrogen receptor (Esr) subtypes, and by examining the Otoconia phenotypes of null mice for selected receptors, we postulate that Esr2 may be critical in mediating the effects of estrogen in Otoconia maintenance.
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Vestibular dysfunction, altered macular structure and trait localization in A/J inbred mice
Mammalian Genome, 2015Co-Authors: Sarath Vijayakumar, Yunxia Wang Lundberg, Teresa E. Lever, Jessica Pierce, Xing Zhao, David Bergstrom, Timothy A. Jones, Sherri M. JonesAbstract:A/J mice develop progressive hearing loss that begins before 1 month of age and is attributed to cochlear hair cell degeneration. Screening tests indicated that this strain also develops early onset vestibular dysfunction and has Otoconial deficits. The purpose of this study was to characterize the vestibular dysfunction and macular structural pathology over the lifespan of A/J mice. Vestibular function was measured using linear vestibular evoked potentials (VsEPs). Macular structural pathology was evaluated using light microscopy, scanning electron microscopy, transmission electron microscopy, confocal microscopy and Western blotting. Individually, vestibular functional deficits in mice ranged from mild to profound. On average, A/J mice had significantly reduced vestibular sensitivity (elevated VsEP response thresholds and smaller amplitudes), whereas VsEP onset latency was prolonged compared to age-matched controls (C57BL/6). A limited age-related vestibular functional loss was also present. Structural analysis identified marked age-independent Otoconial abnormalities in concert with some stereociliary bundle defects. Macular epithelia were incompletely covered by Otoconial membranes with significantly reduced opacity and often contained abnormally large or giant Otoconia as well as normal-appearing Otoconia. Elevated expression of key otoconins (i.e., otoconin 90, otolin and keratin sulfate proteoglycan) ruled out the possibility of reduced levels contributing to Otoconial dysgenesis. The phenotype of A/J was partially replicated in a consomic mouse strain (C57BL/6J-Chr 17^A/J/NaJ), thus indicating that Chr 17^A/J contained a trait locus for a new gene variant responsible to some extent for the A/J vestibular phenotype. Quantitative trait locus analysis identified additional epistatic influences associated with chromosomes 1, 4, 9 and X. Results indicate that the A/J phenotype represents a complex trait, and the A/J mouse strain presents a new model for the study of mechanisms underlying Otoconial formation and maintenance.
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Resting Discharge Patterns of Macular Primary Afferents in Otoconia-Deficient Mice
Journal of the Association for Research in Otolaryngology : JARO, 2008Co-Authors: Timothy A. Jones, Sherri M. Jones, Larry F. HoffmanAbstract:Vestibular primary afferents in the normal mammal are spontaneously active. The consensus hypothesis states that such discharge patterns are independent of stimulation and depend instead on excitation by vestibular hair cells due to background release of synaptic neurotransmitter. In the case of Otoconial sensory receptors, it is difficult to test the independence of resting discharge from natural tonic stimulation by gravity. We examined this question by studying discharge patterns of single vestibular primary afferent neurons in the absence of gravity stimulation using two mutant strains of mice that lack Otoconia (OTO−; head tilt, het-Nox3, and tilted, tlt-Otop1). Our findings demonstrated that macular primary afferent neurons exhibit robust resting discharge activity in OTO− mice. Spike interval coefficient of variation (CV = SD/mean spike interval) values reflected both regular and irregular discharge patterns in OTO− mice, and the range of values for rate-normalized CV was similar to mice and other mammals with intact Otoconia although there were proportionately fewer irregular fibers. Mean discharge rates were slightly higher in Otoconia-deficient strains even after accounting for proportionately fewer irregular fibers [OTO− = 75.4 ± 31.1(113) vs OTO+ = 68.1 ± 28.5(143) in sp/s]. These results confirm the hypothesis that resting activity in macular primary afferents occurs in the absence of ambient stimulation. The robust discharge rates are interesting in that they may reflect the presence of a functionally ‘up-regulated’ tonic excitatory process in the absence of natural sensory stimulation.
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Osteopontin is not Critical for Otoconia Formation or Balance Function
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Xing Zhao, Sherri M. Jones, Wallace B. Thoreson, Yunxia Wang LundbergAbstract:Unlike the structural and mechanical role of bone crystals, the inertial mass of Otoconia crystals provides a shearing force to stimulate the mechanoreceptors of the utricle and saccule (the gravity receptor organ) under the stimuli of linear motion. It is not clear whether Otoconia, composed primarily of CaCO_3 and glycoproteins, go through similar calcification processes as bone. We have recently shown that otoconin-90 (Oc90) regulates the growth of Otoconia crystals as osteopontin does bone crystals. Here, we analyzed the role of this non-collagenous bone matrix protein, osteopontin, in Otoconia formation and balance function utilizing its knockout mice, whose inner ear phenotype has not been examined. Despite the presence of the protein in wild-type Otoconia and vestibular hair cells, morphological, ultrastructural, and protein and calcium composition analyses of osteopontin null Otoconia show that the protein is not needed for crystal formation, and no evidence of compensatory protein deposition is found. Employment of a wide spectrum of balance behavioral tests demonstrates that the protein is not critical for balance function either, which is confirmed by the normal function of the gravity receptor organ directly measured with linear vestibular-evoked potentials (VsEPs). When compared with findings on other otoconins, the data manifest a hierarchy of importance of proteins in crystallization and indicate mechanistic similarities and differences between bone and Otoconia calcification.
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otoconin 90 deletion leads to imbalance but normal hearing a comparison with other Otoconia mutants
Neuroscience, 2008Co-Authors: Xing Zhao, Sherri M. Jones, Ebenezer N. Yamoah, Wang Y LundbergAbstract:Our sense of gravitation and linear acceleration is mediated by stimulation of vestibular hair cells through displacement of Otoconia in the utricle and saccule (the gravity receptor organ). We recently showed that otoconin-90 (Oc90) deletion led to formation of giant Otoconia. In the present study, we determined the extent to which the giant Otoconia affected balance and gravity receptor sensory input and compared the findings with other Otoconia mutants. We employed a wide spectrum of balance behavioral tests, including reaching and air-righting reflexes, gait, swimming, beam-crossing, rotorod latencies, and a direct measure of gravity receptor input, vestibular evoked potentials (VsEPs). All tests on homozygous adult mutants consistently ranked the order of imbalance as (from worst to best) Nox3(het)
wild type and C57Bl/6 mice using systematic statistical comparisons of the frequency of occurrence or the severity of abnormal functions. This order coincides with the degree of Otoconia deficiencies and is consistent with VsEP measures. Notably, all mice (except Nox3(het)) showed remarkable learned adaptation to peripheral vestibular deficits by staying on the rotating rod significantly longer in each successive trial, and the rate and extent of such learned improvements ranked the same order as their initial balance ability. Despite the vestibular morbidity, Oc90 null mice had normal hearing, as measured by auditory brainstem responses (ABRs) and distortion products of otoacoustic emissions (DPOAEs). The study demonstrates that the remnant Otoconia mass in Oc90 nulls does stimulate the gravity receptor organs, which was likely responsible for the improved balance performance relative to strains with absent Otoconia. Furthermore, the combination of direct electrophysiological measures and a series of behavioral tests can be used to interpret the imbalance severity arising from altered inputs from the gravity receptor end organ.
Yasuo Harada - One of the best experts on this subject based on the ideXlab platform.
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Formation and fate of giant Otoconia of the guinea pig following streptomycin intoxication.
Acta oto-laryngologica, 1997Co-Authors: Masaya Takumida, De Ming Zhang, Koji Yajin, Yasuo HaradaAbstract:Formation and fate of abnormal (giant) Otoconia of the guinea pig following streptomycin intoxication were investigated using scanning electron microscopy. The giant Otoconia formed as multifaceted morphology in their early developmental period. They grew up the the transitional type and finally to the cylindrical type. It has been suggested that the giant Otoconia found following streptomycin intoxication may be formed mainly by dissolution of normal Otoconia due to the loss of environmental calcium, followed by recrystallization as giant crystals. These phenomena seemed to be closely related to the Otoconial dynamics which may regulate calcium ion homeostasis of the endolymph.
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Polychromatic labeling of Otoconia for the investigation of calcium turnover.
ORL; journal for oto-rhino-laryngology and its related specialties, 1997Co-Authors: Masaya Takumida, De Ming Zhang, Koji Yajin, Yasuo HaradaAbstract:The calcium ion turnover into Otoconia of adult guinea pigs was investigated by the use of different fluorochromes, i.e. tetracycline (TC), calcein (Cal) and alizarin complexone (AC). The administration of all fluorochromes induced yellow (TC), green (Cal) and red (AC) fluorescence on the outer surface of Otoconia, respectively. Sequential polychromatic labeling with AC followed by TC induced only red fluorescence after 1 week administration of TC, combined fluorescence after 2 weeks administration of TC and only yellow fluorescence after more than 3 weeks of administration of TC. The Otoconia labeled with both AC and TC showed red fluorescence on the side faces of Otoconia and yellow fluorescence on the terminal faces. These results may indicate the existence of a dynamic exchange of calcium ions in the Otoconia and this exchange is mainly restricted to the terminal faces. The sequential polychromatic labeling may thus be of great use for the further investigation of the calcium dynamics of Otoconia.
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Incorporation of tetracycline into Otoconia of the guinea-pig following streptomycin intoxication.
Acta oto-laryngologica, 1996Co-Authors: De Ming Zhang, Masaya Takumida, Yasuo HaradaAbstract:The effects of streptomycin on the calcium ion turnover into Otoconia of adult guinea-pigs investigated by the use of tetracycline. The oral administration of tetracycline induced the deposition of tetracycline (fluorescence) on the outer surface of Otoconia indicating the existence of dynamic exchange and/or uptake of calcium ions in the Otoconia. The significant finding is that streptomycin specifically interfered with calcium uptake into the Otoconia which indicated that the decrease in calcium uptake caused by streptomycin may be closely related to the loss of Otoconia as well as to a decrease in the calcium contents of Otoconia. The decrease in calcium incorporation into Otoconia caused by streptomycin was recovered within 6 weeks after the last injection of streptomycin. The number of Otoconia with fluorescence in the central portion as well as their outer surface was increased. It is therefore suggested that the recovery of calcium uptake as well as new Otoconial regeneration may play an important role for the recovery from loss of Otoconia.
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incorporation of tetracycline into Otoconia of the guinea pig following streptomycin intoxication
Acta Oto-laryngologica, 1996Co-Authors: De Ming Zhang, Masaya Takumida, Yasuo HaradaAbstract:Zhang DM, Takumida M, Harada Y. Incorporation of tetracycline into Otoconia of the guinea-pig following streptomycin intoxication. Acta Otolaryngol (Stockh) 1996; 116: 812-816.The effects of streptomycin on the calcium ion turnover into Otoconia of adult guinea-pigs were investigated by the use of tetracycline. the oral administration of tetracycline induced the deposition of tetracycline (fluorescence) on the outer surface of Otoconia indicating the existence of dynamic exchange and/or uptake of calcium ions in the Otoconia. the significant finding is that streptomycin specifically interfered with calcium uptake into the Otoconia which indicated that the decrease in calcium uptake caused by streptomycin may be closely related to the loss of Otoconia as well as to a decrease in the calcium contents of Otoconia. the decrease in calcium incorporation into otocina caused by strepomycin was recovered within 6 weeks after the last injection of streptomycin. the number of Otoconia with fluorescence in the centr...
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Uptake of Tetracycline in Otoconia of the Guinea Pig
Acta oto-laryngologica, 1996Co-Authors: De Ming Zhang, Masaya Takumida, Yasuo HaradaAbstract:Calcium ion turnover in the Otoconia of adult guinea pigs was investigated by observing the uptake of tetracycline. Oral administration of tetracycline resulted in the deposition of tetracycline (fluorescence) on the outer surface of Otoconia, indicating the occurrence of dynamic exchange and/or uptake of calcium ions in the Otoconia. Prolonged administration of tetracycline induced with fluorescence deposition in the central portion as well as on the surface of the Otoconia. These findings suggest the occurrence of neogenesis, regeneration and/or growth of Otoconia even in adult animals.
