Wyniki wyszukiwania - Biblioteka Nauki

1

Analysis of a dynamic response of the cochlea using fluid-structure interaction model

100%

Kamieniecki K. , Piechna J. , Borkowski P.

Engineering Transactions

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2016

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tom Vol. 64, iss. 4

573--579

EN

A one-dimensional (1D) model of the cochlea of the inner ear has been built and validated against the previously built three-dimensional (3D) fluid-structure interaction (FSI) model of the cochlea. The 1D model has been used to assess the influence of the round window impedance on the pressure distribution in the cochlea. It was shown that high impedance, which enables compression reflection pressure wave at the round window, leads to the biggest pressure difference between the scala vestibule and the scala tympani in the cochlea, which may lead to a stronger excitation of the basilar membrane.

2

On the place code for pitch: a psychophysiological paradox in the classical concept

88%

Zwislocki J. J.

Archives of Acoustics

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2007

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tom Vol. 32, No. 3

447--454

EN

The place of maximum excitation in the cochlea has been believed to be the code for the pitch of tones since mid 19-th century. More recent physiological experiments have revealed that, in a healthy cochlea, the maximum is displaced gradually toward the cochlear base (input) as the sound pressure is increased, whereas the pitch remains practically constant. This paradox suggests that the maximum excitation may not be the adequate code for the pitch after all. In the presence of hearing loss of cochlear origin, the pitch appears higher than normal. As the sound pressure level is increased, it changes gradually back to normal. By contrast, the maximum of cochlear excitation in the presence of cochlear damage, although displaced toward the cochlear base, remains independent of sound pressure level. In both situations, normal and pathological, the apical cut off of cochlear excitation depends on the sound pressure level in the same way as does the pitch. Could the cut off be the adequate place code for the pitch?

3

Expression of ENaC, SGK1 and Nedd4 isoforms in the cochlea of guinea pig

75%

Zhong S.-X. , Hu G.-H.

Folia Histochemica et Cytobiologica

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2014

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tom 52

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nr 2

4

Air-conducted cervical and ocular vestibular evoked miogenic potentials in patients with Susac’s syndrome

75%

Lachowska M. , Zakrzewska-Pniewska B. , Nojszewska M. , Niemczyk K.

Polski Przegląd Otorynolaryngologiczny

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2018

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tom 7(2)

8-15

EN

Aim: To evaluate acoustically evoked cervical and ocular vestibular miogenic potentials (AC cVEMP and oVEMP) in patients with Susac’s syndrome. We did not seek for a diagnostic replacement test in those patients, but we investigated if the combined application of AC cVEMP and oVEMPs might be helpful as an additional source of information about the disease. Material and methods: To record VEMPs, the EMG standardization method was used to continuously monitor and minimize the variability of the recordings. The stimuli were presented unilaterally one ear at a time. The waveforms were analyzed for the response, latency and amplitude. Susac’s syndrome is a rare disease and two patients were analyzed in this study. Results: In patient #1 stimulation resulted in responses on both sides with latencies within normal and symmetry limits for both c- and oVEMPs; however, the responses presented small amplitudes for cVEMPs. In patient #2, only cVEMPs were present. The P1 latencies were within normal values but amplitudes were low, in addition showing asymmetry between sides, with right side amplitude being smaller. Conclusion: The information provided by the combined application of AC cVEMP and oVEMP might be useful in the diagnostics of Susac’s syndrome revealing additional information about the affected vestibular system and be of help in the treatment and rehabilitation planning.

5

The effect of pressure on potassium currents in the inner hair cells isolated from guinea-pig cochlea

63%

Kimitsuki T.

Acta Neurobiologiae Experimentalis

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2013

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tom 73

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nr 4

EN

An increase in hydrostatic pressure in the endolymphatic system causes hydrops-related inner ear diseases such as Meniere's disease or low tone sensorineural hearing loss. In the present study, we investigated the effects of pressure exerted on potassium currents in acutely isolated inner hair cells of the guinea-pig cochlea using whole-cell voltage-clamp techniques. By applying negative or positive pressure via the patch pipette using a syringe, intracellular hydropressure was changed between -40 cm H2O to +20 cm H2O. Negative pressure potentiated the amplitude of potassium currents, whereas positive pressure suppressed the amplitude of potassium currents. Gadolinium, a blocker of stretch-activated cation channels, did not influence pressure-dependent changes in potassium currents; however, cinnarizine blocked pressure-dependent changes in potassium currents. The current changes were not dependent on the sign of the pressure change, that is, similar increases in negative pressures (between -10 cm H2O and -40 cm H2O) and similar decreases in positive pressures (between +10 cm H2O and +20 cm H2O) were observed.

6

The expression of endothelin type A and B receptors in the lateral wall of the mouse cochlea

63%

Luo Y. , Tang Y. , Xia Q. , Liu J.

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tom 12

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nr 4

595-603

EN

Endothelin (ET), originally characterized as a vasoconstrictive peptide, has been found to have many different biological functions, including acting as a local hormonal regulator of pressure, fluid, ions and neurotransmitters in the inner ear. The objective of this study was to examine and quantify the mRNA expression of the endothelin type A and B receptors (ETAR and ETBR) in the strial vascularies (StV) and non-strial tissues (NSt) of the cochlear lateral wall using the real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. The mouse tissue samples were harvested and RNA was extracted. RT was performed to obtain cDNA, and then the mRNA expression of each gene was measured via real-time PCR. We found that both receptor subtypes were expressed in the cochlear lateral wall, with a predominance of ETAR over ETBR. We showed that the mRNA expression of the two receptor subtypes was higher in the StV with a 1.8 times higher level of ETAR and an 8.1 times higher level of ETBR mRNAs than in the adjacent NSt of the lateral wall tissue. This study shows the existence and the quantity of ET receptor subtypes in the StV and NSt of the mouse cochlea. Our results suggest that an endothelin-mediated response via two different receptors, ETAR and ETBR, may play an important role in the physiological functions of the cochlear lateral wall by maintaining the homeostatic environment of the cochlea.

7

Bone conduction stimulation of the otic capsule: a finite element model of the temporal bone

63%

Borkowski P. , Marek P. , Niemczyk K. , Lachowska M. , Kwacz M. , Wysocki J.

Acta of Bioengineering and Biomechanics

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2019

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tom Vol. 21, no. 3

75--86

EN

Bone conduction stimulation applied on the otic capsule may be used in a conductive hearing loss treatment as an alternative to the bone conduction implants in clinical practice. A finite element study was used to evaluate the force amplitude and direction needed for the stimulation. Methods: A finite element model of a female temporal bone with a precisely reconstructed cochlea was subjected to a harmonic analysis assuming two types of stimulation. At first, the displacement amplitude in the form of air conduction stimulation was applied on the stapes footplate. Then the force amplitude was applied on the otic capsule in the form of bone conduction stimulation. The two force directions were considered: 1) the primary direction, when a typical opening is performed during mastoidectomy, and was coincident with the axis of an imaginary cone, inscribed in the opening, and 2) the direction perpendicular to the stapes footplate. The force amplitude was set so that the response from the cochlea corresponded to the result of air conduction stimulation applied on the stapes footplate. Results: The amplitude and phase of vibration and the volume displacement on the round window membrane were considered as well as vibrations of the basilar membrane, spiral lamina, and promontory. Conclusions: The cochlear response was comparable for the two types of stimulation. The efficiency of bone conduction stimulation depended on the force direction. For the primary direction, the force was a few times smaller than for the direction perpendicular to the stapes footplate.

8

The origins of the cochlea and impedance matching hearing in synapsids

63%

Laaß M.

Acta Palaeontologica Polonica

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2016

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tom 61

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nr 2

EN

The origin of tympanic hearing in early synapsids is still controversial, because little is known about their inner ear and the function of their sound conducting apparatus. Here I describe the earliest known tympanic ear in the synapsid lineage, the ear of Pristerodon (Therapsida, Anomodontia) from the Late Permian of South Africa, which was virtually reconstructed from neutron tomographic data. Although Pristerodon is not a direct ancestor of mammals, its inner ear with distinctive cochlear cavity represents a connecting link between the primitive therapsid inner ear and the mammalian inner ear. The anatomy of the sound conducting apparatus of Pristerodon and the increased sound pressure transformer ratio points to a sensitivity to airborne sound. Furthermore, the origins of the cochlea and impedance matching hearing in synapsids coincided with the loss of contact between head and substrate, which already took place at least in Late Permian therapsids even before the postdentary bones became detached from the mandible.

9

Drug-mediated ototoxicity and tinnitus: alleviation with melatonin

51%

Reiter R. J. , Tan D.-X. , Korkmaz A. , Fuentes-Broto L.

Journal of Physiology and Pharmacology

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2011

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tom 62

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nr 2

EN

This review evaluates the published basic science and clinical reports related to the role of melatonin in reducing the side effects of aminoglycosides and the cancer chemotherapeutic agent cisplatin, in the cochlea and vestibule of the inner ear. A thorough search of the literature was performed using available databases for the purpose of uncovering articles applicable to the current review. Cochlear function was most frequently evaluated by measuring otoacoustic emissions and their distortion products after animals were treated with cytotoxic drugs alone or in combination with melatonin. Vestibular damage due to aminoglycosides was evaluated by estimating hair cell loss in explanted utricles of newborn rats. Tinnitus was assessed in patients who received melatonin using a visual analogue scale or the Tinnitus Handicap Inventory. Compared to a mixture of antioxidants which included tocopherol, ascorbate, glutathione and N-acetyl-cysteine, melatonin, also a documented antioxidant, was estimated to be up to 150 times more effective in limiting the cochlear side effects, evaluated using otoacoustic emission distortion products, of gentamicin, tobramycin and cisplatin. In a dose-response manner, melatonin also reduced vestibular hair cell loss due to gentamicin treatment in explanted utricles of newborn rats. Finally, melatonin (3 mg daily) limited subjective tinnitus in patients. These findings suggest the potential use of melatonin to combat the ototoxicity of aminoglycosides and cancer chemotherapeutic agents. Additional studies at both the experimental and clinical levels should be performed to further document the actions of melatonin at the cochlear and vestibular levels to further clarify the protective mechanisms of action of this ubiquitously-acting molecule. Melatonin’s low cost and minimal toxicity profile supports its use to protect the inner ear from drug-mediated damage.