Σάββατο 21 Ιανουαρίου 2017

Auditory-visual integration in fields of the auditory cortex

Publication date: Available online 21 January 2017
Source:Hearing Research
Author(s): Michinori Kubota, Shunji Sugimoto, Yutaka Hosokawa, Hisayuki Ojima, Junsei Horikawa
While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.



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Auditory-visual integration in fields of the auditory cortex

Publication date: Available online 21 January 2017
Source:Hearing Research
Author(s): Michinori Kubota, Shunji Sugimoto, Yutaka Hosokawa, Hisayuki Ojima, Junsei Horikawa
While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.



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Auditory-visual integration in fields of the auditory cortex

S03785955.gif

Publication date: Available online 21 January 2017
Source:Hearing Research
Author(s): Michinori Kubota, Shunji Sugimoto, Yutaka Hosokawa, Hisayuki Ojima, Junsei Horikawa
While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.



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Auditory-visual integration in fields of the auditory cortex

S03785955.gif

Publication date: Available online 21 January 2017
Source:Hearing Research
Author(s): Michinori Kubota, Shunji Sugimoto, Yutaka Hosokawa, Hisayuki Ojima, Junsei Horikawa
While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.



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Auditory-visual integration in fields of the auditory cortex

S03785955.gif

Publication date: Available online 21 January 2017
Source:Hearing Research
Author(s): Michinori Kubota, Shunji Sugimoto, Yutaka Hosokawa, Hisayuki Ojima, Junsei Horikawa
While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.



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The alcohol-sensitive period during early octavolateral organ development in zebrafish (Danio rerio).

Related Articles

The alcohol-sensitive period during early octavolateral organ development in zebrafish (Danio rerio).

J Neurosci Res. 2017 Jan 20;:

Authors: Zamora LY, Miguel KC, Lu Z

Abstract
Fetal alcohol exposure can cause Fetal Alcohol Spectrum Disorders (FASD), completely preventable developmental disabilities characterized by permanent birth defects. However, specific gestational timing when developing organs are most sensitive to alcohol exposure is unclear. In this study, we examined the temporal effects of embryonic alcohol exposure on octavolateral organs in zebrafish (Danio rerio), including inner ears and lateral line neuromasts that function in hearing, balance, and hydrodynamic detection, respectively. To determine an alcohol-sensitive period in the first 24 hours post fertilization (hpf), Et(krt4:EGFP)(sqet4) zebrafish that express green fluorescent protein in sensory hair cells were treated in 2% alcohol for 2, 3, and 5-hours. Octavolateral organs of control and alcohol-exposed larvae were examined at 3, 5, and 7 days post fertilization (dpf). Using confocal and light microscopy, we found that alcohol-exposed larvae had significantly smaller otic vesicles and saccular otoliths than control larvae at 3 dpf. Only alcohol-exposed larvae from 12-17 hpf had smaller otic vesicles at 5 dpf, smaller saccular otoliths at 7 dpf and fewer saccular hair cells, neuromasts and hair cells per neuromast at 3 dpf. In addition, auditory function was assessed by microphonic potential recordings from inner ear hair cells in response to 200-Hz stimulation. Hearing sensitivity was reduced for alcohol-exposed larvae from 7-12 and 12-17 hpf. Our results show that 12-17 hpf is an alcohol-sensitive time window when morphology and function of zebrafish octavolateral organs are most vulnerable to alcohol exposure. This study implies that embryonic alcohol exposure timing during early development can influence severity of hearing deficits. © 2017 Wiley Periodicals, Inc.

PMID: 28105691 [PubMed - as supplied by publisher]



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Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Ménière's Disease Patients.

Related Articles

Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Ménière's Disease Patients.

Front Neurol. 2016;7:239

Authors: Ueberfuhr MA, Wiegrebe L, Krause E, Gürkov R, Drexl M

Abstract
Tinnitus is one of the three classical symptoms of Ménière's disease (MD), an inner ear disease that is often accompanied by endolymphatic hydrops. Previous studies indicate that tinnitus in MD patients is dominated by low frequencies, whereas tinnitus in non-hydropic pathologies is typically higher in frequency. Tinnitus of rather low-frequency (LF) quality was also reported to occur for about 90 s in normal-hearing participants after presentation of intense, LF sound (120 dB SPL, 30 Hz, 90 s). LF sound has been demonstrated to also cause temporary endolymphatic hydrops in animal models. Here, we quantify tinnitus in two study groups with chronic (MD patients) and presumably transient endolymphatic hydrops (normal-hearing participants after LF exposure) with a psychophysical procedure. Participants matched their tinnitus either with a pure tone of adjustable frequency and level or with a noise of adjustable spectral shape and level. Sensation levels of matching stimuli were lower for MD patients (mean: 8 dB SL) than for normal-hearing participants (mean: 15 dB SL). Transient tinnitus after LF-exposure occurred in all normal-hearing participants (N = 28). About half of the normal-hearing participants matched noise to their tinnitus, the other half chose a pure tone with frequencies below 2 kHz. MD patients matched their tinnitus with either high-frequency pure tones, mainly above 3 kHz, or with a noise. Despite a significant proportion of MD patients matching low-pass (roaring) noises to their tinnitus, the range of matched stimuli was more heterogeneous than previous data suggested. We propose that in those participants with noise-like tinnitus, the percept is probably generated by increased spontaneous activity of auditory nerve fibers with a broad range of characteristic frequencies, due to an impaired ion balance in the cochlea. For tonal tinnitus, additional mechanisms are conceivable: focal hair cell loss can result in decreased auditory nerve firing and a central auditory overcompensation. Also, normal-hearing participants after LF-exposure experience alterations in spontaneous otoacoustic emissions, which may contribute to a transient tonal tinnitus.

PMID: 28105023 [PubMed - in process]



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Alterations in the balance of tubulin glycylation and glutamylation in photoreceptors leads to retinal degeneration.

Related Articles

Alterations in the balance of tubulin glycylation and glutamylation in photoreceptors leads to retinal degeneration.

J Cell Sci. 2017 Jan 19;:

Authors: Grau MB, Masson C, Gadadhar S, Rocha C, Tort O, Sousa PM, Vacher S, Bieche I, Janke C

Abstract
Tubulin is subject to a wide variety of posttranslational modifications, which as part of the tubulin code are involved in the regulation of microtubule functions. Glycylation has so far predominantly been found in motile cilia and flagella, and absence of this modification leads to ciliary disassembly. Here we demonstrate that the connecting cilia of photoreceptors, which are non-motile sensory cilia, are also dependent on glycylation. In contrast to many other tissues, only one glycylase, TTLL3, is expressed in retina. Ttll3(-/-) mice lack glycylation in photoreceptors, which results in shortening of connecting cilia and slow retinal degeneration. Moreover, absence of glycylation results in increased levels of tubulin glutamylation in photoreceptors, and inversely, hyperglutamylation in the pcd mouse abolishes glycylation. This suggests that both posttranslational modifications compete for modification sites, and that unbalancing the glutamylation/glycylation equilibrium on axonemes of connecting cilia, notwithstanding by which enzymatic mechanism, invariably leads to retinal degeneration.

PMID: 28104815 [PubMed - as supplied by publisher]



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[Simultaneous triple semicircular canal plugging and cochlear implantation in advanced Meniere's disease].

Related Articles

[Simultaneous triple semicircular canal plugging and cochlear implantation in advanced Meniere's disease].

Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2017 Jan 07;52(1):25-30

Authors: Zhang DG, Xu L, Han YC, Lyu YF, Luo JF, Li YW, Wang RJ, Fan ZM, Wang HB

Abstract
Objective: To evaluate the feasibility of combining simultaneous triple semicircular canal plugging (TSCP) and cochlear implantation (CI) to treat vertigo and hearing loss in advanced Meniere's disease(MD) patients, so as to provide an alternative surgical procedure for treating this disorder. Methods: Data from seven patients, who were referred to our hospital and diagnosed with unilateral MD strictly meeting the criteria issued by Chinese Academy of Otolaryngology-Head and Neck Surgery Committee (2006), from Jan. 2015 to Jan. 2016, were retrospectively analyzed in this work. Seven patients, in whom the standardized conservative treatment had been given for at least one year and frequent vertigo still occurred, underwent simultaneous TSCP and CI under general anesthesia via mastoid approach. Postoperative follow-up time was more than six months. Vertigo control and auditory function were measured. Pure tone audiometry, speech perception scores, caloric test, head impulse test (HIT), and vestibular evoked myogenic potential (VEMP) were performed for evaluation of audiological and vestibular functions. Results: All patients had bilateral severe sensorineural hearing loss preoperatively. One side hearing loss was due to MD and another side was due to reasons including sudden sensorineural hearing loss, mumps and other unknown reason. The total control rate of vertigo in seven MD patients was 100.0% in the six-month follow-up, with complete control rate of 85.7% (6/7) and substantial control rate of 14.3% (1/7). Improved hearing threshold and speech perception scores were observed in all study participants. Postoperative average aided hearing threshold was 32.5 dBHL, the average monosyllabic word score was 42.6% and speech perception scores of sentences tested in quiet was 52.3%. Tinnitus improved in five cases, and no significant change in two patients. Post-operatively, all patients suffered from temporary vertigo and balance disorders. Vertigo was disappeared in all patients within 3-5 days, while, an average recovery time of balance disorders was 19.7 days. Six months after treatment, loss of semicircular canal function by caloric test was found in the operation side of all patients and no change in cVEMP or oVEMP test was noted. All patients had no facial paralysis, cerebrospinal fluid leakage, and other complications. Conclusions: A combined approach of TSCP and CI which could control vertigo effectively and improve hearing loss and tinnitus represents an effective and safe therapy for some advanced MD patients.

PMID: 28104012 [PubMed - in process]



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The alcohol-sensitive period during early octavolateral organ development in zebrafish (Danio rerio).

Related Articles

The alcohol-sensitive period during early octavolateral organ development in zebrafish (Danio rerio).

J Neurosci Res. 2017 Jan 20;:

Authors: Zamora LY, Miguel KC, Lu Z

Abstract
Fetal alcohol exposure can cause Fetal Alcohol Spectrum Disorders (FASD), completely preventable developmental disabilities characterized by permanent birth defects. However, specific gestational timing when developing organs are most sensitive to alcohol exposure is unclear. In this study, we examined the temporal effects of embryonic alcohol exposure on octavolateral organs in zebrafish (Danio rerio), including inner ears and lateral line neuromasts that function in hearing, balance, and hydrodynamic detection, respectively. To determine an alcohol-sensitive period in the first 24 hours post fertilization (hpf), Et(krt4:EGFP)(sqet4) zebrafish that express green fluorescent protein in sensory hair cells were treated in 2% alcohol for 2, 3, and 5-hours. Octavolateral organs of control and alcohol-exposed larvae were examined at 3, 5, and 7 days post fertilization (dpf). Using confocal and light microscopy, we found that alcohol-exposed larvae had significantly smaller otic vesicles and saccular otoliths than control larvae at 3 dpf. Only alcohol-exposed larvae from 12-17 hpf had smaller otic vesicles at 5 dpf, smaller saccular otoliths at 7 dpf and fewer saccular hair cells, neuromasts and hair cells per neuromast at 3 dpf. In addition, auditory function was assessed by microphonic potential recordings from inner ear hair cells in response to 200-Hz stimulation. Hearing sensitivity was reduced for alcohol-exposed larvae from 7-12 and 12-17 hpf. Our results show that 12-17 hpf is an alcohol-sensitive time window when morphology and function of zebrafish octavolateral organs are most vulnerable to alcohol exposure. This study implies that embryonic alcohol exposure timing during early development can influence severity of hearing deficits. © 2017 Wiley Periodicals, Inc.

PMID: 28105691 [PubMed - as supplied by publisher]



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Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Ménière's Disease Patients.

Related Articles

Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Ménière's Disease Patients.

Front Neurol. 2016;7:239

Authors: Ueberfuhr MA, Wiegrebe L, Krause E, Gürkov R, Drexl M

Abstract
Tinnitus is one of the three classical symptoms of Ménière's disease (MD), an inner ear disease that is often accompanied by endolymphatic hydrops. Previous studies indicate that tinnitus in MD patients is dominated by low frequencies, whereas tinnitus in non-hydropic pathologies is typically higher in frequency. Tinnitus of rather low-frequency (LF) quality was also reported to occur for about 90 s in normal-hearing participants after presentation of intense, LF sound (120 dB SPL, 30 Hz, 90 s). LF sound has been demonstrated to also cause temporary endolymphatic hydrops in animal models. Here, we quantify tinnitus in two study groups with chronic (MD patients) and presumably transient endolymphatic hydrops (normal-hearing participants after LF exposure) with a psychophysical procedure. Participants matched their tinnitus either with a pure tone of adjustable frequency and level or with a noise of adjustable spectral shape and level. Sensation levels of matching stimuli were lower for MD patients (mean: 8 dB SL) than for normal-hearing participants (mean: 15 dB SL). Transient tinnitus after LF-exposure occurred in all normal-hearing participants (N = 28). About half of the normal-hearing participants matched noise to their tinnitus, the other half chose a pure tone with frequencies below 2 kHz. MD patients matched their tinnitus with either high-frequency pure tones, mainly above 3 kHz, or with a noise. Despite a significant proportion of MD patients matching low-pass (roaring) noises to their tinnitus, the range of matched stimuli was more heterogeneous than previous data suggested. We propose that in those participants with noise-like tinnitus, the percept is probably generated by increased spontaneous activity of auditory nerve fibers with a broad range of characteristic frequencies, due to an impaired ion balance in the cochlea. For tonal tinnitus, additional mechanisms are conceivable: focal hair cell loss can result in decreased auditory nerve firing and a central auditory overcompensation. Also, normal-hearing participants after LF-exposure experience alterations in spontaneous otoacoustic emissions, which may contribute to a transient tonal tinnitus.

PMID: 28105023 [PubMed - in process]



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Alterations in the balance of tubulin glycylation and glutamylation in photoreceptors leads to retinal degeneration.

Related Articles

Alterations in the balance of tubulin glycylation and glutamylation in photoreceptors leads to retinal degeneration.

J Cell Sci. 2017 Jan 19;:

Authors: Grau MB, Masson C, Gadadhar S, Rocha C, Tort O, Sousa PM, Vacher S, Bieche I, Janke C

Abstract
Tubulin is subject to a wide variety of posttranslational modifications, which as part of the tubulin code are involved in the regulation of microtubule functions. Glycylation has so far predominantly been found in motile cilia and flagella, and absence of this modification leads to ciliary disassembly. Here we demonstrate that the connecting cilia of photoreceptors, which are non-motile sensory cilia, are also dependent on glycylation. In contrast to many other tissues, only one glycylase, TTLL3, is expressed in retina. Ttll3(-/-) mice lack glycylation in photoreceptors, which results in shortening of connecting cilia and slow retinal degeneration. Moreover, absence of glycylation results in increased levels of tubulin glutamylation in photoreceptors, and inversely, hyperglutamylation in the pcd mouse abolishes glycylation. This suggests that both posttranslational modifications compete for modification sites, and that unbalancing the glutamylation/glycylation equilibrium on axonemes of connecting cilia, notwithstanding by which enzymatic mechanism, invariably leads to retinal degeneration.

PMID: 28104815 [PubMed - as supplied by publisher]



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[Simultaneous triple semicircular canal plugging and cochlear implantation in advanced Meniere's disease].

Related Articles

[Simultaneous triple semicircular canal plugging and cochlear implantation in advanced Meniere's disease].

Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2017 Jan 07;52(1):25-30

Authors: Zhang DG, Xu L, Han YC, Lyu YF, Luo JF, Li YW, Wang RJ, Fan ZM, Wang HB

Abstract
Objective: To evaluate the feasibility of combining simultaneous triple semicircular canal plugging (TSCP) and cochlear implantation (CI) to treat vertigo and hearing loss in advanced Meniere's disease(MD) patients, so as to provide an alternative surgical procedure for treating this disorder. Methods: Data from seven patients, who were referred to our hospital and diagnosed with unilateral MD strictly meeting the criteria issued by Chinese Academy of Otolaryngology-Head and Neck Surgery Committee (2006), from Jan. 2015 to Jan. 2016, were retrospectively analyzed in this work. Seven patients, in whom the standardized conservative treatment had been given for at least one year and frequent vertigo still occurred, underwent simultaneous TSCP and CI under general anesthesia via mastoid approach. Postoperative follow-up time was more than six months. Vertigo control and auditory function were measured. Pure tone audiometry, speech perception scores, caloric test, head impulse test (HIT), and vestibular evoked myogenic potential (VEMP) were performed for evaluation of audiological and vestibular functions. Results: All patients had bilateral severe sensorineural hearing loss preoperatively. One side hearing loss was due to MD and another side was due to reasons including sudden sensorineural hearing loss, mumps and other unknown reason. The total control rate of vertigo in seven MD patients was 100.0% in the six-month follow-up, with complete control rate of 85.7% (6/7) and substantial control rate of 14.3% (1/7). Improved hearing threshold and speech perception scores were observed in all study participants. Postoperative average aided hearing threshold was 32.5 dBHL, the average monosyllabic word score was 42.6% and speech perception scores of sentences tested in quiet was 52.3%. Tinnitus improved in five cases, and no significant change in two patients. Post-operatively, all patients suffered from temporary vertigo and balance disorders. Vertigo was disappeared in all patients within 3-5 days, while, an average recovery time of balance disorders was 19.7 days. Six months after treatment, loss of semicircular canal function by caloric test was found in the operation side of all patients and no change in cVEMP or oVEMP test was noted. All patients had no facial paralysis, cerebrospinal fluid leakage, and other complications. Conclusions: A combined approach of TSCP and CI which could control vertigo effectively and improve hearing loss and tinnitus represents an effective and safe therapy for some advanced MD patients.

PMID: 28104012 [PubMed - in process]



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Co segregation of the m.1555A>G mutation in the MT-RNR1 gene and mutations in MT-ATP6 gene in a family with dilated mitochondrial cardiomyopathy and hearing loss: A whole mitochondrial genome screening.

Related Articles

Co segregation of the m.1555A>G mutation in the MT-RNR1 gene and mutations in MT-ATP6 gene in a family with dilated mitochondrial cardiomyopathy and hearing loss: A whole mitochondrial genome screening.

Biochem Biophys Res Commun. 2017 Jan 16;:

Authors: Alila-Fersi O, Chamkha I, Majdoub I, Gargouri L, Mkaouar-Rebai E, Tabebi M, Tlili A, Keskes L, Mahfoudh A, Fakhfakh F

Abstract
Mitochondrial disease refers to a heterogeneous group of disorders resulting in defective cellular energy production due to dysfunction of the mitochondrial respiratory chain, which is responsible for the generation of most cellular energy. Because cardiac muscles are one of the high energy demanding tissues, mitochondrial cardiomyopathies is one of the most frequent mitochondria disorders. Mitochondrial cardiomyopathy has been associated with several point mutations of mtDNA in both genes encoded mitochondrial proteins and mitochondrial tRNA and rRNA. We reported here the first description of mutations in MT-ATP6 gene in two patients with clinical features of dilated mitochondrial cardiomyopathy. The mutational analysis of the whole mitochondrial DNA revealed the presence of m.1555A>G mutation in MT-RNR1 gene associated to the m.8527A>G (p.M>V) and the m.8392C>T (p.136P>S) variations in the mitochondrial MT-ATP6 gene in patient1 and his family members with variable phenotype including hearing impairment. The second patient with isolated mitochondrial cardiomyopathy presented the m.8605C>T (p.27P>S) mutation in the MT-ATP6 gene. The three mutations p.M1V, p.P27S and p.P136S detected in MT-ATP6 affected well conserved residues of the mitochondrial protein ATPase 6. In addition, the substitution of proline residue at position 27 and 136 effect hydrophobicity and structure flexibility conformation of the protein.

PMID: 28104394 [PubMed - as supplied by publisher]



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Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults

Publication date: March 2017
Source:Gait & Posture, Volume 53
Author(s): Braveena K. Santhiranayagam, W.A. Sparrow, Daniel T.H. Lai, Rezaul K. Begg
Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an ‘indicative’ toe height at the individual’s average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.



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Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults

Publication date: March 2017
Source:Gait & Posture, Volume 53
Author(s): Braveena K. Santhiranayagam, W.A. Sparrow, Daniel T.H. Lai, Rezaul K. Begg
Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an ‘indicative’ toe height at the individual’s average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.



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Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults

Publication date: March 2017
Source:Gait & Posture, Volume 53
Author(s): Braveena K. Santhiranayagam, W.A. Sparrow, Daniel T.H. Lai, Rezaul K. Begg
Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an ‘indicative’ toe height at the individual’s average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.



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Intraoperative Electrocochleography: A Window Into Endolymphatic Hydrops in a Patient With an Endolymphatic Sac Tumor.

Objectives: Intraoperative electrocochleography (ECochG) provides valuable information regarding inner ear function during surgical procedures. Here, we report findings from ECochG collected at three time intervals during the management of a patient with symptoms of inner ear hydrops. Patients: A 38-year-old man with an endolymphatic sac tumor who demonstrated classic Meniere's symptoms. Interventions: Endolymphatic shunt, tumor biopsy, and definitive resection of an endolymphatic sac tumor. Main Outcome Measures: Intraoperative ECochG measurements at three time intervals, using frequency-specific tone bursts and clicks. Results: Across time intervals, the amplitude of ECochG summation potential (SP) responses decreased for tone bursts of all frequencies. On the other hand, the SP response to the click stimulus, and the ratio of the SP to action potential (AP), basically remained unchanged across time points. Conclusions: Results suggest that the absolute amplitude of the SP response to frequency-specific tone bursts may be more sensitive to inner ear hydrops than the traditionally used SP/AP ratio as a response to click stimuli. Copyright (C) 2017 by Otology & Neurotology, Inc. Image copyright (C) 2010 Wolters Kluwer Health/Anatomical Chart Company

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Long-Term Hearing Results After Ossiculoplasty.

Objectives: To determine if the OOPS index is predictive of long-term hearing results after ossiculoplasty. Study Design: Case series with retrospective chart review. Setting: Tertiary care otology practice. Patients: Adult and pediatric patients (3-88 years of age). Interventions: Ossiculoplasty with cartilage tympanoplasty, with or without mastoidectomy. Outcome Measures: Primary outcome measures included short-term hearing results (pure-tone average air-bone gap [PTA-ABG] measured between 60 days and 1 year after surgery), long-term hearing results (PTA-ABG measured >=5 years after surgery), and the rate of successful ABG closure to

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