The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform

Tsutomu Nakashima - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional 3d visualization of endolymphatic hydrops after intratympanic injection of gd dtpa optimization of a 3d real inversion recovery turbo spin echo tse sequence and application of a 32 channel head coil at 3t
    Journal of Magnetic Resonance Imaging, 2010
    Co-Authors: Shinji Naganawa, Michihiko Sone, Shunichi Ishihara, Shingo Iwano, Tsutomu Nakashima
    Abstract:

    Purpose: To enable volume visualization of endolymphatic hydrops of Meniere's disease via a volume rendering (VR) technique, a three-dimensional (3D) inversion-recovery (IR) sequence with real reconstruction (3D-real IR) sequence after intratympanic injection of Gd-DTPA was optimized for higher spatial resolution using a 32-channel head coil at 3T. Materials and Methods: Pulse sequence parameters were optimized using a diluted Gd-DTPA phantom. Then, 11 patients who had been clinically diagnosed with Meniere's disease and a patient with sudden hearing loss were scanned. Images were processed using commercially available 3D-VR software. 3D-real IR data was processed to produce endolymph and perilymph fluid volume images in different colors. 3D-CISS data was processed to generate total fluid volume images. Results: While maintaining a comparable signal-to-noise ratio (SNR) and scan time, the voxel volume could be reduced from 0.4 × 0.4 × 2 mm3 with a 12-channel coil to 0.4 × 0.4 × 0.8 mm3 with a 32-channel coil. A newly-optimized protocol allowed the smooth, three-dimensional visualization of endolymphatic hydrops in all patients with Meniere's disease. Conclusion: Volumetrically separate visualization of endo-/Perilymphatic Space is now feasible in patients with Meniere's disease using an optimized 3D-real IR sequence, a 32-channel head coil, at 3T, after intratympanic administration of Gd-DTPA. This will aid the understanding of the pathophysiology of Meniere's disease. J. Magn. Reson. Imaging 2010;31:210–214. © 2009 Wiley-Liss, Inc.

  • imaging of endolymphatic and Perilymphatic fluid at 3t after intratympanic administration of gadolinium diethylene triamine pentaacetic acid
    American Journal of Neuroradiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, M Kawamura, Hiroshi Fukatsu, M. Sugiura, Tsutomu Nakashima
    Abstract:

    By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and Perilymphatic Space 24 hours after intratympanic administration of gadolinium contrast material. In patients with Meniere disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid Space of the labyrinth and the spatial relationship of the 2 Spaces.

  • separate visualization of endolymphatic Space Perilymphatic Space and bone by a single pulse sequence 3d inversion recovery imaging utilizing real reconstruction after intratympanic gd dtpa administration at 3 tesla
    European Radiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, Hiroko Satake, M Kawamura, Hiroshi Fukatsu, Tsutomu Nakashima
    Abstract:

    Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the Perilymphatic Space. Three-dimensional FLAIR can differentiate endolymphatic Space from Perilymphatic Space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of Perilymphatic Space (positive value), endolymphatic Space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic Space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing Perilymphatic Space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic Space, Perilymphatic Space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

  • visualization of endolymphatic hydrops in patients with meniere s disease
    Laryngoscope, 2007
    Co-Authors: Tsutomu Nakashima, Shinji Naganawa, Michihiko Sone, Makoto Sugiura, Masaaki Teranishi, Hideo Hayashi, Seiichi Nakata, Naomi Katayama, Ieda Maria Ishida
    Abstract:

    Objective: Recently, there have been many reports of intratympanic gentamicin therapy for the treatment of intractable Meniere's disease. Intratympanic administration of steroids has also been used to treat sudden sensorineural hearing loss. We attempted to visualize how the intratympanically administered drug enters the inner ear. Methods: Gadolinium hydrate diluted eightfold with saline was injected intratympanically through the tympanic membrane using a 23 G needle in nine patients with inner ear diseases. With a 3 Tesla magnetic resonance imaging (MRI) unit, three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging was performed. Results: 3D-FLAIR MRI clearly revealed that the gadolinium entered the Perilymphatic Space and delineated the Perilymphatic and endolymphatic Spaces of the inner ear. In patients with endolymphatic hydrops, the Perilymphatic Space surrounding the endolymph was small or had disappeared. Gadolinium appeared first in the scala tympani of the basal turn of the cochlea and the Perilymphatic Space of the vestibule. One day after the intratympanic injection of gadolinium, the gadolinium was observed in almost all parts of the perilymph. Six days after the intratympanic injection, the gadolinium had almost disappeared from the inner ear. Conclusion: We reported the first visualization of endolymphatic hydrops in patients with Meniere's disease. The relationship between the image of the endolymphatic Space and functional tests, such as electrocochleography and vestibular-evoked myogenic potential, must be examined in the near future. It is important for the development of intratympanic drug therapies for inner-ear diseases to investigate how the drugs enter and leave the inner ear.

Shinji Naganawa - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional 3d visualization of endolymphatic hydrops after intratympanic injection of gd dtpa optimization of a 3d real inversion recovery turbo spin echo tse sequence and application of a 32 channel head coil at 3t
    Journal of Magnetic Resonance Imaging, 2010
    Co-Authors: Shinji Naganawa, Michihiko Sone, Shunichi Ishihara, Shingo Iwano, Tsutomu Nakashima
    Abstract:

    Purpose: To enable volume visualization of endolymphatic hydrops of Meniere's disease via a volume rendering (VR) technique, a three-dimensional (3D) inversion-recovery (IR) sequence with real reconstruction (3D-real IR) sequence after intratympanic injection of Gd-DTPA was optimized for higher spatial resolution using a 32-channel head coil at 3T. Materials and Methods: Pulse sequence parameters were optimized using a diluted Gd-DTPA phantom. Then, 11 patients who had been clinically diagnosed with Meniere's disease and a patient with sudden hearing loss were scanned. Images were processed using commercially available 3D-VR software. 3D-real IR data was processed to produce endolymph and perilymph fluid volume images in different colors. 3D-CISS data was processed to generate total fluid volume images. Results: While maintaining a comparable signal-to-noise ratio (SNR) and scan time, the voxel volume could be reduced from 0.4 × 0.4 × 2 mm3 with a 12-channel coil to 0.4 × 0.4 × 0.8 mm3 with a 32-channel coil. A newly-optimized protocol allowed the smooth, three-dimensional visualization of endolymphatic hydrops in all patients with Meniere's disease. Conclusion: Volumetrically separate visualization of endo-/Perilymphatic Space is now feasible in patients with Meniere's disease using an optimized 3D-real IR sequence, a 32-channel head coil, at 3T, after intratympanic administration of Gd-DTPA. This will aid the understanding of the pathophysiology of Meniere's disease. J. Magn. Reson. Imaging 2010;31:210–214. © 2009 Wiley-Liss, Inc.

  • imaging of endolymphatic and Perilymphatic fluid at 3t after intratympanic administration of gadolinium diethylene triamine pentaacetic acid
    American Journal of Neuroradiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, M Kawamura, Hiroshi Fukatsu, M. Sugiura, Tsutomu Nakashima
    Abstract:

    By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and Perilymphatic Space 24 hours after intratympanic administration of gadolinium contrast material. In patients with Meniere disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid Space of the labyrinth and the spatial relationship of the 2 Spaces.

  • separate visualization of endolymphatic Space Perilymphatic Space and bone by a single pulse sequence 3d inversion recovery imaging utilizing real reconstruction after intratympanic gd dtpa administration at 3 tesla
    European Radiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, Hiroko Satake, M Kawamura, Hiroshi Fukatsu, Tsutomu Nakashima
    Abstract:

    Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the Perilymphatic Space. Three-dimensional FLAIR can differentiate endolymphatic Space from Perilymphatic Space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of Perilymphatic Space (positive value), endolymphatic Space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic Space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing Perilymphatic Space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic Space, Perilymphatic Space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

  • visualization of endolymphatic hydrops in patients with meniere s disease
    Laryngoscope, 2007
    Co-Authors: Tsutomu Nakashima, Shinji Naganawa, Michihiko Sone, Makoto Sugiura, Masaaki Teranishi, Hideo Hayashi, Seiichi Nakata, Naomi Katayama, Ieda Maria Ishida
    Abstract:

    Objective: Recently, there have been many reports of intratympanic gentamicin therapy for the treatment of intractable Meniere's disease. Intratympanic administration of steroids has also been used to treat sudden sensorineural hearing loss. We attempted to visualize how the intratympanically administered drug enters the inner ear. Methods: Gadolinium hydrate diluted eightfold with saline was injected intratympanically through the tympanic membrane using a 23 G needle in nine patients with inner ear diseases. With a 3 Tesla magnetic resonance imaging (MRI) unit, three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging was performed. Results: 3D-FLAIR MRI clearly revealed that the gadolinium entered the Perilymphatic Space and delineated the Perilymphatic and endolymphatic Spaces of the inner ear. In patients with endolymphatic hydrops, the Perilymphatic Space surrounding the endolymph was small or had disappeared. Gadolinium appeared first in the scala tympani of the basal turn of the cochlea and the Perilymphatic Space of the vestibule. One day after the intratympanic injection of gadolinium, the gadolinium was observed in almost all parts of the perilymph. Six days after the intratympanic injection, the gadolinium had almost disappeared from the inner ear. Conclusion: We reported the first visualization of endolymphatic hydrops in patients with Meniere's disease. The relationship between the image of the endolymphatic Space and functional tests, such as electrocochleography and vestibular-evoked myogenic potential, must be examined in the near future. It is important for the development of intratympanic drug therapies for inner-ear diseases to investigate how the drugs enter and leave the inner ear.

Michihiko Sone - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional 3d visualization of endolymphatic hydrops after intratympanic injection of gd dtpa optimization of a 3d real inversion recovery turbo spin echo tse sequence and application of a 32 channel head coil at 3t
    Journal of Magnetic Resonance Imaging, 2010
    Co-Authors: Shinji Naganawa, Michihiko Sone, Shunichi Ishihara, Shingo Iwano, Tsutomu Nakashima
    Abstract:

    Purpose: To enable volume visualization of endolymphatic hydrops of Meniere's disease via a volume rendering (VR) technique, a three-dimensional (3D) inversion-recovery (IR) sequence with real reconstruction (3D-real IR) sequence after intratympanic injection of Gd-DTPA was optimized for higher spatial resolution using a 32-channel head coil at 3T. Materials and Methods: Pulse sequence parameters were optimized using a diluted Gd-DTPA phantom. Then, 11 patients who had been clinically diagnosed with Meniere's disease and a patient with sudden hearing loss were scanned. Images were processed using commercially available 3D-VR software. 3D-real IR data was processed to produce endolymph and perilymph fluid volume images in different colors. 3D-CISS data was processed to generate total fluid volume images. Results: While maintaining a comparable signal-to-noise ratio (SNR) and scan time, the voxel volume could be reduced from 0.4 × 0.4 × 2 mm3 with a 12-channel coil to 0.4 × 0.4 × 0.8 mm3 with a 32-channel coil. A newly-optimized protocol allowed the smooth, three-dimensional visualization of endolymphatic hydrops in all patients with Meniere's disease. Conclusion: Volumetrically separate visualization of endo-/Perilymphatic Space is now feasible in patients with Meniere's disease using an optimized 3D-real IR sequence, a 32-channel head coil, at 3T, after intratympanic administration of Gd-DTPA. This will aid the understanding of the pathophysiology of Meniere's disease. J. Magn. Reson. Imaging 2010;31:210–214. © 2009 Wiley-Liss, Inc.

  • imaging of endolymphatic and Perilymphatic fluid at 3t after intratympanic administration of gadolinium diethylene triamine pentaacetic acid
    American Journal of Neuroradiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, M Kawamura, Hiroshi Fukatsu, M. Sugiura, Tsutomu Nakashima
    Abstract:

    By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and Perilymphatic Space 24 hours after intratympanic administration of gadolinium contrast material. In patients with Meniere disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid Space of the labyrinth and the spatial relationship of the 2 Spaces.

  • separate visualization of endolymphatic Space Perilymphatic Space and bone by a single pulse sequence 3d inversion recovery imaging utilizing real reconstruction after intratympanic gd dtpa administration at 3 tesla
    European Radiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, Hiroko Satake, M Kawamura, Hiroshi Fukatsu, Tsutomu Nakashima
    Abstract:

    Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the Perilymphatic Space. Three-dimensional FLAIR can differentiate endolymphatic Space from Perilymphatic Space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of Perilymphatic Space (positive value), endolymphatic Space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic Space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing Perilymphatic Space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic Space, Perilymphatic Space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

  • visualization of endolymphatic hydrops in patients with meniere s disease
    Laryngoscope, 2007
    Co-Authors: Tsutomu Nakashima, Shinji Naganawa, Michihiko Sone, Makoto Sugiura, Masaaki Teranishi, Hideo Hayashi, Seiichi Nakata, Naomi Katayama, Ieda Maria Ishida
    Abstract:

    Objective: Recently, there have been many reports of intratympanic gentamicin therapy for the treatment of intractable Meniere's disease. Intratympanic administration of steroids has also been used to treat sudden sensorineural hearing loss. We attempted to visualize how the intratympanically administered drug enters the inner ear. Methods: Gadolinium hydrate diluted eightfold with saline was injected intratympanically through the tympanic membrane using a 23 G needle in nine patients with inner ear diseases. With a 3 Tesla magnetic resonance imaging (MRI) unit, three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging was performed. Results: 3D-FLAIR MRI clearly revealed that the gadolinium entered the Perilymphatic Space and delineated the Perilymphatic and endolymphatic Spaces of the inner ear. In patients with endolymphatic hydrops, the Perilymphatic Space surrounding the endolymph was small or had disappeared. Gadolinium appeared first in the scala tympani of the basal turn of the cochlea and the Perilymphatic Space of the vestibule. One day after the intratympanic injection of gadolinium, the gadolinium was observed in almost all parts of the perilymph. Six days after the intratympanic injection, the gadolinium had almost disappeared from the inner ear. Conclusion: We reported the first visualization of endolymphatic hydrops in patients with Meniere's disease. The relationship between the image of the endolymphatic Space and functional tests, such as electrocochleography and vestibular-evoked myogenic potential, must be examined in the near future. It is important for the development of intratympanic drug therapies for inner-ear diseases to investigate how the drugs enter and leave the inner ear.

M Kawamura - One of the best experts on this subject based on the ideXlab platform.

  • Imaging of Endolymphatic and Perilymphatic Fluid at 3T After Intratympanic Administration of Gadolinium-Diethylene-Triamine Pentaacetic Acid
    2015
    Co-Authors: S. Naganawa, M Kawamura, M. Sugiura, H. Fukatsu, M. Sone, T. Nakashima
    Abstract:

    SUMMARY: By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and Perilymphatic Space 24 hours after intratym-panic administration of gadolinium contrast material. In patients with Ménière disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid Space of the labyrinth and the spatial relationship of the 2 Spaces. After intratympanic injection of gadolinium-diethylene-triamine pentaacetic acid (Gd-DTPA) in an animal study, Gd-DTPA was absorbed through the round window mem-brane andwas distributedmainly into the Perilymphatic Space of the labyrinth.1 Enlarged endolymphatic Space in patients with Ménière disease has been successfully recognized as an areawith low signal intensity partly surrounded by high-signal intensity Perilymphatic fluid on 3D-fluid-attenuated inver-sion recovery (FLAIR) images obtained after intratympanic injection of Gd-DTPA.2 However, the boundary between the cochlear endolymphatic Space and surrounding bone was no

  • imaging of endolymphatic and Perilymphatic fluid at 3t after intratympanic administration of gadolinium diethylene triamine pentaacetic acid
    American Journal of Neuroradiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, M Kawamura, Hiroshi Fukatsu, M. Sugiura, Tsutomu Nakashima
    Abstract:

    By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and Perilymphatic Space 24 hours after intratympanic administration of gadolinium contrast material. In patients with Meniere disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid Space of the labyrinth and the spatial relationship of the 2 Spaces.

  • separate visualization of endolymphatic Space Perilymphatic Space and bone by a single pulse sequence 3d inversion recovery imaging utilizing real reconstruction after intratympanic gd dtpa administration at 3 tesla
    European Radiology, 2008
    Co-Authors: Shinji Naganawa, Michihiko Sone, Hiroko Satake, M Kawamura, Hiroshi Fukatsu, Tsutomu Nakashima
    Abstract:

    Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the Perilymphatic Space. Three-dimensional FLAIR can differentiate endolymphatic Space from Perilymphatic Space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of Perilymphatic Space (positive value), endolymphatic Space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic Space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing Perilymphatic Space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic Space, Perilymphatic Space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

Vicente Honrubia - One of the best experts on this subject based on the ideXlab platform.

  • synaptophysin immunohistochemistry during vestibular hair cell recovery after gentamicin treatment
    Audiology and Neuro-otology, 2003
    Co-Authors: Ivan A Lopez, Carlos Ayala, Vicente Honrubia
    Abstract:

    In the present study, morphometric and immunohistochemical techniques were used to evaluate the degree of synaptic recovery in the chinchilla crista sensory epithelia during various post-gentamicin-treatment periods of hair cell loss and recovery. For this purpose, two groups of animals were treated with Gelfoam pellets impregnated with 50 micro g of gentamicin implanted in the Perilymphatic Space within the otic capsule of the superior semicircular canal. Animals were sacrificed 1, 2 and 4 weeks after treatment. The degree of synaptic reinnervation was evaluated in the horizontal crista of the first group of animals using immunohistochemical techniques and antibodies against synaptophysin, a marker for synaptic reinnervation and synaptogenesis. Quantification of immunoreactivity in this group was made in the mid-region of the crista using the NIH 'Image' program. The second group of animals was used for quantification of the number of hair cells and supporting cells in the horizontal crista. In the normal sensory epithelium, synaptophysin immunoreactivity was found in the areas corresponding to the known distribution of afferent and efferent nerve terminals. Immunoreactivity was predominantly located within the afferent calyces of type I hair cells. No immunoreactivity was found in the supporting cells. Seven days after treatment there was a significant loss of hair cells and synaptophysin-stained area (SSA). In the mid-region of the crista the loss of synaptophysin immunoreactivity was quantitatively the greatest within the central zone of this region (93%) while the loss of hair cells was the smallest. These results suggest that afferent and efferent nerve terminals were also severely affected by the ototoxic treatment. Four weeks after treatment corresponding to the end of the recovery phase of gentamicin ototoxicity, there was a proportional increase in the number of hair cells and of the degree of SSA in the mid-region of the crista. The number of hair cells recovered to 58% with a recovery of SSA to 54% of normal. These results suggest that a greater fraction of synaptophysin expression within the sensory epithelium depends on the presence of afferent calyceal endings, which are greatly affected by gentamicin. Also, these results demonstrate a significant level of reinnervation of the newly regenerated hair cells, forecasting the potential for functionality of the regenerated hair cells.

  • glutamate like immunoreactivity during hair cell recovery after gentamicin exposure in the chinchilla vestibular sensory periphery
    Laryngoscope, 1999
    Co-Authors: Kenley W Chin, Ivan A Lopez, Seungchul Lee, Vicente Honrubia
    Abstract:

    Objective: Determine the expression of glutamate by immunohistochemistry in normal and recovering vestibular hair cells in the chinchilla crista ampullaris after gentamicin ototoxicity. Study Design: In five groups of three animals each, ototoxicity was produced by placing gentamicin (50 μg)-impregnated Gelfoam pellets within the Perilymphatic Space of the superior semicircular canal. Animals were sacrificed at 1, 2, 4, 8, and 16 weeks after treatment. A group of normal (n=3) animals was also processed. Methods: For the detection of glutamate the inner ears of these animals were dissected, and the horizontal cristae ampullaris embedded in plastic. Two-micron-thick tissue sections were obtained and incubated with monoclonal antibodies against glutamate. The immunoreaction was detected using the avidinbiotinylated-complex technique and diaminobenzidine was the chromogen. Results: Normal sensory epithelia demonstrated type I and type II hair cells with moderate glutamate-like immunoreactivity. Supporting cells demonstrated no glutamate-like immunoreactivity. Afferent nerve fibers and calyxes surrounding type I hair cells demonstrated strong glutamate-like immunoreactivity. At 1 and 2 weeks after treatment the few type II hair cells surviving ototoxic treatment (15%-18%) contained moderate glutamate-like immunoreactivity, supporting cells showed no immunoreactivity, and nerve terminals and fibers displayed strong immunoreactivity. At 4 and 8 weeks after treatment, recovered hair cells (80%) had greater glutamate-like immunoreactivity when compared with normal hair cells, supporting cells displayed no glutamate-like immunoreactivity, and afferent fibers contained strong glutamate-like immunoreactivity. At 16 weeks, glutamate-like immunoreactivity in hair cells returned to normal level. Conclusion: Glutamate may be used as an indicator of hair cell differentiation and as an index of the molecular recovery of hair cells after ototoxicity.

  • hair cell recovery in the chinchilla crista ampullaris after gentamicin treatment a quantitative approach
    Otolaryngology-Head and Neck Surgery, 1998
    Co-Authors: Ivan A Lopez, Vicente Honrubia, Seungchul Lee, Karl Beykirch
    Abstract:

    Abstract The mechanisms for hair cell recovery were investigated after intraotic application of 50 μg gentamicin into the Perilymphatic Space of the superior semicircular canal of the chinchilla. Histologic evaluation of one normal group and four posttreatment groups (7, 14, 28, and 56 days) was made with light and transmission electron microscopic techniques. The numeric changes of hair cells and supporting cells was quantified with the dissector technique. At 7 and 14 days after treatment, no type I hair cells were present, and 85% and 88% of type II hair cells were lost. Supporting cells decreased to 76% at 7 days, but they recovered to 91% at 14 days. Recovery of the epithelia was evident 28 days after treatment; 83% were type II hair cells, and 3% were type I hair cells. The supporting cell number remained close to normal (86%). Between 14 and 28 days after treatment, there was an increase of 1758 of type II hair cells, representing approximately 125 new hair cells per day. At the same time interval the number of supporting cells remained near normal. These results suggest that new hair cells might be the result of supporting cell mitotic division and differentiation. (Otolaryngol Head Neck Surg 1998;119:255-62.)

  • histological evidence for hair cell regeneration after ototoxic cell destruction with local application of gentamicin in the chinchilla crista ampullaris
    Hearing Research, 1995
    Co-Authors: Hasan Tanyeri, Ivan A Lopez, Vicente Honrubia
    Abstract:

    Abstract Two experiments were conducted to study the ototoxic effects of local gentamicin (GM) administration and the subsequent hair cell (HC) regeneration process in the chinchilla cristae ampullares (CA). In the first experiment, 3 different doses of GM (0.1, 0.2 and 1.2 mg) were administered by surgical implantation of GM-soaked Gelfoam® pledgets in the Perilymphatic Space in the otic capsule of the left superior semicircular canal. The CA was histologically processed for light-microscopic examination. In the second experiment, 6 groups of 2 chinchillas each were treated with 0.1 mg of GM. To document cell proliferation and HC regeneration, Alzet® micro-osmotic pumps were implanted in each chinchilla to deliver bromodeoxyuridine (BrdU) at 125 μg/h for 1 week. Chinchillas were subsequently killed at 1 and 4 days and 1, 2, 4 and 8 weeks post-treatment (PT). The CA was processed for light microscopy and BrdU immunocytochemistry. In the first experiment the smallest dose produced damage restricted to HCs alone, while the medium and large doses produced severe damage in the sensory epithelium, including supporting cells and HCs. Results in the second experiment demonstrated that at 1 and 4 days PT and HCs showed extensive damage, including clumping of nuclear material. By 4 days PT the supporting cell nuclei lost their monolayer configuration. Calyceal terminals appeared empty, and vacuolized remnants of nerve calyces were evident in the basal portion. At 1 week PT complete disappearance of HCs from the sensory epithelium was evident, and there was cytoplasmic extrusion into the endolymphatic Space. At 2 weeks PT there was complete HC loss, the supporting cell nuclei were scattered randomly in the crista, and the nerve fibers were retracted from the sensory epithelium. At 4 weeks PT there was evidence of sensory epithelium repair and HC regeneration. Short cells resembling type-II HCs were evident in the surface of the sensory epithelium. At 8 weeks PT the number of HCs increased in a uniform fashion on the surface of the sensory epithelium, and the supporting cell nuclei were realigned on the basal membrane. Nerve fibers with growth cones penetrated the basal membrane. Supporting cell proliferation was evident by the presence of mitotic figures and BrdU immunoreactivity in the chromatin material of dividing cells at 2 weeks PT. The labeling was more evident in newly formed cells at 4 and 8 weeks PT. These results demonstrate that in chinchillas the vestibular organs have the capacity of self-repair and the process includes HC regeneration after local administration of GM. The overall process involves changes in different cells in the sensory epithelium and neural elements, all of which show modifications with an orderly pattern.