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Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise.

Infrasound (i.e., <20 Hz for humans; <100 Hz for chinchillas) is not audible, but exposure to high-levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4 kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24h. For each animal, the tympanic membrane (TM) in one ear was perforated ( approximately 1 mm(2)) prior to exposure to attenuate infrasound transmission to that …

Anatomical restrictions in the transsphenoidal, transclival approach to the upper clival region: a cadaveric, anatomic study.

OBJECTIVE: Tumours in the clival region are difficult to remove surgically. Before the 1970s, clival tumours had very high mortality and morbidity rates. METHODS: An anatomic dissection was performed on 24 spheno-occipital bone blocks obtained from 28 adult cadavers. The internal carotid artery, paraclival carotid tubercle, sixth cranial nerve and dorsum sellae in the upper clival region were analyzed qualitatively and quantitatively. For the histological evaluation, 4 samples were decalcified and sagittal sections were cut. From the eight blocks obtained, 32 incisions were made in the axial

A test for the diagnosis of dead regions in the cochlea.

Hearing impairment may sometimes be associated with complete loss of inner hair cells (IHCs) over a certain region of the basilar membrane. We call this a 'dead region'. Amplification (using a hearing aid) over a frequency range corresponding to a dead region may not be beneficial and may even impair speech intelligibility. However, diagnosis of dead regions is not easily done from the audiogram. This paper reports the design and evaluation of a method for detecting and delimiting dead regions. A noise, called 'threshold equalizing noise' (TEN), was spectrally shaped so that, for normally hear…

Схемы нейронного дегенерации в кохлее человека и слуховом нерве: последствия для имплантации кохлеара.

Хотя личность всех переменных, которые могут повлиять на распознавание речи после кохлеарной имплантации, неизвестна, степень сохранения спиральных клеток ганглиона, как правило, считается первостепенной. Обобщается ряд экспериментов в наших лабораториях, направленных на количественную оценку выживших клеток спиральных ганглионов у глубоко глухих, оценку прогнозируемой ценности различных клинических параметров и оценку последствий имплантации во внутреннем ухе. Гистологическое исследование внутренних ушей пациентов, которые были оглушены в течение жизни, показало, что причина глухоты составляе

Совпадение в аннотации оригинала
Although the identity of all the variables that may influence speech recognition after cochlear implantation is unknown, the degree of prese … received implants during life. A characteristic pattern of damage to the lateral cochlear wall and basilar membrane was identified in the upper basal turn. New bone formation and perielectrode fibrosis was common after cochlear implantation. Despite this significant trauma and reaction, there is no firm evidence that further degeneration of the spiral ganglion ca …

The cellular basis of hearing: the biophysics of hair cells.

A crucial event in the hearing process is the transduction of mechanical stimuli into electrical signals by hair cells, the sensory receptors of the internal ear. Stimulation results in the rapid opening of ionic channels in the mechanically sensitive organelles of these cells, their hair bundles. These transduction channels, which are nonselectively permeable, are directly excited by hair-bundle displacement. Hair cells are selectively responsive to particular frequencies of stimulation, both due to the mechanical properties of their hair bundles and because of an ensemble of ionic channels t

Sulforaphane attenuates cisplatin-induced hearing loss by inhibiting histone deacetylase expression.

INTRODUCTION: Cruciferous vegetables are a rich source of sulforaphane (SFN), which acts as a natural HDAC inhibitor (HDACi). Our previous s … on CIHL. We observed auditory brainstem response (ABR) threshold shifts and immunostained cochlear basilar membranes of rats. For in vitro experiments, we treated HEI-OC1 cells and rat cochlear organotypic cultures with SFN (5, 10, and 15 μM) and cisplatin (10 μM). Immunofluorescence, cell viability, and protein analysis were performed to further analyze the prot …

Predictive value of laboratory tests in "autoimmune" inner ear disease: preliminary report.

The purpose of this prospective, controlled study was to estimate the prevalence of immune-mediated (autoimmune) inner ear disease in a high-risk patient population, in order to determine the predictive value of a positive lymphocyte transformation test. The high-risk group was defined as any dizzy patient with unilateral or bilateral-asymmetric sensorineural hearing loss, who had not previously received immunotherapy. From more than 400 consecutive patients with a chief complaint of dizziness, 58 were entered into the study over an 8-month period. The control group consisted of 15 normal volu

Auditory filter nonlinearity in mild/moderate hearing impairment.

Sensorineural hearing loss has frequently been shown to result in a loss of frequency selectivity. Less is known about its effects on the level dependence of selectivity that is so prominent a feature of normal hearing. The aim of the present study is to characterize such changes in nonlinearity as manifested in the auditory filter shapes of listeners with mild/moderate hearing impairment. Notched-noise masked thresholds at 2 kHz were measured over a range of stimulus levels in hearing-impaired listeners with losses of 20-50 dB. Growth-of-masking functions for different notch widths are more p

[The damaging effects of two exposures to 100 dB white noise on myelination of the auditory nerve in mouse cochleae mechanism of repeated noise exposure on myelin sheath of cochlear auditory nerve in mice].

Objective:This study aims to investigate the mechanism and potential effects of two exposures to 100 dB sound pressure level（SPL） broadband … ure. The cochleae of all three groups were then collected for immunofluorescence observation of the basilar membrane and transmission electron microscopy to observe changes in the structure of the auditory nerve myelin sheath. Results:In the single noise exposure group, ABR thresholds at all frequencies were significantly elevated compared to the control group at …

Calcium-dependent inactivation of calcium channels in cochlear hair cells of the chicken.

Voltage-gated calcium channels support both spontaneous and sound-evoked neurotransmitter release from ribbon synapses of cochlear hair cells. A variety of regulatory mechanisms must cooperate to ensure the appropriate level of activity in the restricted pool of synaptic calcium channels ( approximately 100) available to each synaptic ribbon. One potential feedback mechanism, calcium-dependent inactivation (CDI) of voltage-gated, L-type calcium channels, can be modulated by calmodulin-like calcium-binding proteins. CDI of voltage-gated calcium current was studied in hair cells of the chicken's

Physiopathological significance of distortion-product otoacoustic emissions at 2f1-f2 produced by high- versus low-level stimuli.

Distortion product otoacoustic emissions emitted by the cochlea at 2f1-f2 in response to pairs of pure tones at f1 and f2 (DPOAE) form a class of otoacoustic emissions and as such, are viewed as a reliable tool for screening outer hair cell (OHC) dysfunctions on a pass/fail basis. However, the persistence of residual DPOAEs from impaired cochleae at high stimulus levels has suggested that above 60-70 dB SPL, instead of reflecting "active" cochlear motion, DPOAEs might represent another "passive" modality: they would thus become unsuitable for analyzing cochlear function. The present work repor

KMUP-1 inhibits L-type Ca²⁺ channels involved the protein kinase C in rat basilar artery myocytes.

This study investigated whether KMUP-1, a xanthine-based derivative, inhibits L-type Ca(2+) currents (I(Ca,L)) in rat basilar artery smooth muscle cells (RBASMCs). We used whole cell patch-clamp recording to monitor Ba(2+) currents (I(Ba)) through L-type Ca(2+) channels (LTCCs). Under voltage-clamp conditions, holding at -40 mV, KMUP-1 (1, 3, 10 μM) inhibited I(Ba) in a concentration-dependent manner and its IC(50) value was 2.27 ± 0.45 μM. A high concentration of KMUP-1 (10 μM) showed without modifying the I(Ba) current-voltage relationship. On the other hand, the protein kinase C (PKC) activ

Relevance of magnetic resonance imaging for ventricular endoscopy.

OBJECTIVE: Endoscopic procedures may represent an alternative to microsurgery or shunt operations in intra- or paraventricular pathologies. However, the operative results mainly depend on the selection of suitable patients. In the present study of 30 patients with occlusive hydrocephalus, the relevance of differentiated magnetic resonance (MR) imaging for evaluation of the pathophysiological and anatomic prerequisites was investigated. PATIENTS AND METHODS: Apart from conventional axial T(2) -weighted turbo spin echo (TSE) sequences (TR/TE 2126/100 ms) and T(1) -weighted spin echo (SE) sequen

Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea.

Receptor potentials of hair cells and spike discharges of cochlear nerve fibres were recorded with micropipettes from the free-standing region of the basilar papilla of anaesthetized alligator lizards in response to tones. In this region the hair-cell stereocilia are free-standing, i.e. they protrude directly into endolymph and are not in contact with a tectorial membrane. The frequency selectivity of hair-cell responses was measured by means of isovoltage contours of the d.c. (V0) and fundamental-a.c. (V1) component of the receptor potential, i.e. iso-V0 and iso-V1 contours. The frequency sel

Electrocochleography Latency: Correlation With Electrode Position During Cochlear Implantation.

OBJECTIVES: Cochlear implant (CI) candidates increasingly exhibit some degree of residual hearing, which should be preserved despite the imp … arrays). Despite high inter-individual variability, our results align with documented delays in the basilar membrane observed in other studies. However, we could not identify a significant association between CML and residual hearing. CONCLUSIONS: Our study demonstrates that objectively extracted CML encodes the intracochlear electrode location in CI patients but …

Cochlear compound action potentials from high-level tone bursts originate from wide cochlear regions that are offset toward the most sensitive cochlear region.

Little is known about the spatial origins of auditory nerve (AN) compound action potentials (CAPs) evoked by moderate to intense sounds. We … The apical shift was surprising because it is opposite the shift expected from AN tuning curve and basilar membrane motion asymmetries. For almost all high-level tone bursts, CAP spatial origins extended over 2 octaves along the cochlea. Surprisingly, CAPs evoked by high-level low-frequency (including 2 kHz) tone bursts showed little CAP contribution from CF regi …

[Morphological changes on cochlear hair cells of rats in simulated weightlessness and inboard noise].

OBJECTIVE: To observe the morphological changes on cochlear hair cells of rats in simulated weightlessness and inboard noise and to investig … r exposure respectively, and immunofluorescence staining and scanning electron microscopy (SEMs) of basilar membrane were applied after exposure. RESULTS: ABR threshold shifts of each group were higher after exposure. There was difference between ABRs of the experiment groups before and after exposure (P<0.05). IF showed that the inner hair cells (IHCs) missing w …

Comparison of venoarterial versus venovenous access in the cerebral circulation of newborns undergoing extracorporeal membrane oxygenation.

This study was designed to compare venoarterial (VA) with venovenous (VV) access in the cerebral circulation of newborn infants during extracorporeal membrane oxygenation (ECMO). Among 14 infants with VA ECMO, 7 had no intracranial complications (group 1), while the others (group 2) developed intracranial hemorrhage (ICH). In contrast, among 19 infants with VV ECMO, only 1 developed ICH. Serial echocardiograms were performed before and after 1, 6, 12, and 24 h and 2 and 3 days of ECMO. The mean cerebral blood flow (CBF) velocities were measured in the anterior cerebral artery (ACA), right and

Anatomical observations during microvascular decompression for idiopathic trigeminal neuralgia (with correlations between topography of pain and site of the neurovascular conflict). Prospective study in a series of 579 patients.

BACKGROUND: The Micro-Vascular Decompression (MVD) procedure - developed for conservative treatment of idiopathic Trigeminal Neuralgia (TN) is based on the NeuroVascular Conflict (NVC) theory. Although MVD has become very popular over the last twenty years, its principles and value remain controversial. Detailed anatomical observations during posterior fossa exploration in patients with idiopathic TN may help to understand better the role of NVCs. METHOD: In this article, the authors report the anatomical observations made under the operating microscope in a consecutive series of 579 patients

Memantine inhibits α3β2-nAChRs-mediated nitrergic neurogenic vasodilation in porcine basilar arteries.

Memantine, an NMDA receptor antagonist used for treatment of Alzheimer's disease (AD), is known to block the nicotinic acetylcholine receptors (nAChRs) in the central nervous system (CNS). In the present study, we examined by wire myography if memantine inhibited α3β2-nAChRs located on cerebral perivascular sympathetic nerve terminals originating in the superior cervical ganglion (SCG), thus, leading to inhibition of nicotine-induced nitrergic neurogenic dilation of isolated porcine basilar arteries. Memantine concentration-dependently blocked nicotine-induced neurogenic dilation of endotheliu