Search Results
Results 301 - 350 of 653
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Kavaliers M - - 1999
The attenuation of opioid analgaesia is a well established effect of extremely low frequency (ELF) magnetic fields with light having a modulatory role in these effects such that when the ELF exposures are carried out in the dark, the inhibitory effects on analgesia are reduced. Here, we considered the light ...
Hamernik R P - - 1999
The auditory system 'toughened' by an interrupted noise exposure has been shown in several reports, to be less affected by (or protected from) a subsequent high level noise exposure. A group of chinchillas (n = 12) was exposed to an interrupted noise at 95 dB SPL, 0.5 kHz octave band, ...
Goel A - - 1999
Subtemporal craniotomy centred on the external ear canal and its basal extension, involving resection of the roots of the zygomatic arch, roof of the external ear canal and superior third to half of the mastoid bone was used to treat surgically 24 meningiomas located in the petroclival region, having their ...
Chen G D - - 1999
In previous studies from our lab, broadband noise induced hearing loss has been found to be potentiated by simultaneous carbon monoxide (CO) exposure. In the present study, octave-band noise induced auditory impairment was studied with the presence of CO at levels of 1500, 1200, 700, 500 and 300 ppm and ...
McFadden S L - - 1999
OBJECTIVE: To determine if chinchillas exhibit sex differences in 1) basic auditory sensitivity and 2) susceptibility to cochlear damage and hearing loss from high-level impulse noise. DESIGN: The auditory sensitivity of 73 chinchillas was assessed by measuring evoked potentials from electrodes implanted in the inferior colliculus (IC-EVPs) and cubic (2f1-f2) ...
Ahroon W A - - 1999
The auditory system, toughened by an interrupted noise exposure, has been shown in several reports to be less affected by (or protected from) a subsequent high-level noise exposure. Exposure to 115 dB peak SPL, 1 kHz narrow band (400 Hz) transients presented l/s, 6 h/day, to four groups of chinchillas ...
Gerhardt K J - - 1999
OBJECTIVE: To evaluate, in two separate experiments, the effects of intense noise exposures delivered to fetal sheep in utero during a time of rapid auditory development. DESIGN: In the first experiment, auditory brain stem response (ABR) thresholds to clicks and tone bursts were recorded from chronically instrumented fetal sheep in ...
Ueda H - - 1999
Whether click-evoked otoacoustic emissions (CEOAEs) have frequency specificity is an issue still subject to debate. In order to resolve this issue, changes in the frequency components of the CEOAE power spectrum, together with changes in compound action potential (CAP) thresholds before and after pure-tone exposure in guinea pigs, were examined. ...
Wilson B W - - 1999
Experiments using the dwarf Siberian hamster Phodopus sungorus were carried out to determine possible neuroendocrine consequences of one-time and repeated exposures to 60 Hz magnetic fields (MF). Animals were maintained in either a short-light (SL, 8 h light:16 h dark) or long-light (LL, 16 h light:8 h dark) photoperiod. Acute ...
Adair E R - - 1999
Thermoregulatory responses of heat production and heat loss were measured in two different groups of seven adult volunteers (males and females) during 45-min dorsal exposures of the whole body to 450 or 2450 MHz continuous-wave radio frequency (RF) fields. At each frequency, two power densities (PD) were tested at each ...
Eddins A C - - 1999
The aim of this study was to evaluate the reduction in 2f1-f2 distortion product otoacoustic emission (DPOAE) amplitude resulting from prolonged noise exposures. A group of five chinchillas was exposed continuously to an octave-band noise centered at 4.0 kHz for a total of 42 days, 6 days at each of ...
Zhai S - - 1998
The effects of impulse noise (firecrackers at 170 dB SPL, 1, 10, 20 rounds) on auditory cortical response threshold (CRT) and activity of succinic dehydrogenase (SDH) and acetylcholinesterase (AchE) in the inner ear were studied in 37 guinea pigs. The results showed that extent of damage in the cochlea was ...
Patuzzi R - - 1998
The onset and recovery of temporary threshold shift (TTS) in one human subject (the author) has been studied during and after pure-tone overstimulation lasting between minutes and days. Under the conditions of these experiments the time courses appeared reproducible, and thresholds always recovered to normal within 3 days. The onset ...
Hashimoto H - - 1998
A conceptual design was developed for a cosmo-biology experiment. It is intended to expose simulated interstellar ice materials deposited on dust grains to the space environment. The experimental system consists of a cryogenic system to keep solidified gas sample, and an optical device to select and amplify the ultraviolet part ...
Hamernik R P - - 1998
A parametric study of the reduction of threshold shift (toughening phenomena) that takes place during the course of an interrupted noise exposure is described. 266 chinchillas randomly assigned to one of 32 experimental groups were exposed to one of the following: a 400-Hz narrow-band impact noise having a center frequency ...
Goldwin B - - 1998
The cause of noise-induced hearing loss remains unclear despite years of both epidemiologic and experimental investigation. Among the many possible pathophysiologic mechanisms that may contribute to noise-induced temporary or permanent threshold shifts are insufficiencies in cochlear blood flow. Although the literature is inconsistent, several histologic and physiologic studies demonstrate signs ...
Horner K C - - 1998
Many studies on anaesthetized animals and a few on awake animals have suggested that the cholinergic olivocochlear efferent feedback to outer hair cells can participate in the protection of the cochlea from acoustic overexposure. Lithium is known to stimulate acetylcholine synthesis and release in the brain and it is likely ...
McFadden S L - - 1998
Like many aging humans, the aging chinchilla tends to lose high-frequency sensitivity at a faster rate than low-frequency sensitivity. This feature, combined with its excellent low-frequency hearing, makes the chinchilla attractive as an animal model for studying the relationship between noise-induced hearing loss (NIHL) and age-related hearing loss (AHL). In ...
Malchaire J - - 1998
The objective of this study is to analyze the evolution of the vibration perception threshold (VPT) following a short duration exposure to vibration. The literature reports experiments with 3 to 10 min exposure to vibration after which a steady state is not necessarily reached. The temporary threshold shift (TTS) of ...
Kjellberg Anders - - 1998
The contribution of noise exposure to fatigue at work was studied in a survey study and three field studies. The survey study was based on a questionnaire covering symptoms and work place exposure answered by 50 000 state employees. Noise exposure was also estimated from their type of job and ...
Hellström P A - - 1998
Three groups of young people, in all 10 males and 11 females, with different music listening habits listened to their own choice of music from a portable cassette player for one hour. The sound pressure level from the music was measured with a probe-provided miniature microphone in the external auditory ...
Levine S - - 1998
The Equal Energy Hypothesis (EEH) is based on the assumption that hearing loss from a given exposure is proportional to the total energy of the exposure. A corollary of this assumption is the power of the exposure and the duration of the exposure are interchangeable. Studies of impulse and impact ...
Hsu W J - - 1998
Seven ears of Sprague-Dawley rats were exposed to 20 microliters Staphylococcus aureus exotoxin suspension by injection via the tympanic membrane into the round window niche. Another 6 ears were exposed to 20 microliters broth as controls. ABR was performed in the interval 2-31.5 kHz immediately before and 1, 2, 5, ...
Kujawa S G - - 1997
The inner ear can be made less vulnerable to acoustic injury by a "conditioning" treatment involving exposure to a moderate-level acoustic stimulus before the acoustic overexposure. The present study was designed to explore the role of the olivocochlear (OC) system in this "protection." Guinea pigs were divided into a number ...
Hu B H - - 1997
Reactive oxygen species, which are cytotoxic to living tissues, are thought to be partly responsible for noise-induced hearing loss. In this study R-phenylisopropyladenosine (R-PIA), a stable non-hydrolyzable adenosine analogue which has been found effective in upregulating antioxidant enzyme activity levels, was topologically applied to the round window of the right ...
Huang X - - 1997
Auditory brainstem responses (ABRs) were obtained from nine late gestational age fetal sheep in utero before and after a 16-h exposure to low-pass (cut-off frequency 1.0 kHz) and high-pass (cut-off frequency 1.0 kHz) noises (approximately 120 dB sound pressure level, recorded in air). Bone-conduction ABRs were elicited by broadband clicks ...
Wenzl T B - - 1997
A measurement survey was undertaken to estimate exposures to 25 hertz (Hz) magnetic fields of maintenance workers on electrified rail lines near Philadelphia, Pa. Because of the mix of frequencies expected, a strategy was developed using new instrument to capture magnetic field waveforms, which were then analyzed by fast Fourier ...
Soutto M - - 1997
In the present study we show that thymus type II thyroxine deiodinase activity exhibits a nyctohemeral profile, with basal values during the day and high values at night. This rhythmic character is dependent on neuroadrenergic input since exposure to continuous light at night completely abolished the nocturnal rise of the ...
Hu B H - - 1997
It has been found that 'conditioning' noise exposures can render the inner ear more resistant to traumatic noise exposures. To explore the possible mechanisms underlying this phenomenon, filamentous actin (F-actin), labeled by rhodamine-phalloidin, was examined in the chinchilla cochlea using confocal fluorescence microscopy. The conditioning noise was 0.5 kHz octave ...
Szymko Y M - - 1997
Alternating potentials produced in Hensen's cells of Mongolian gerbils by sinusoidal stimuli were enhanced or depressed after exposure to broad-band sound of moderately high intensity, depending on exposure- and stimulus intensities. Since Hensen's cell responses have been shown to be identical in phase and directly proportional in magnitude to outer ...
Müller M - - 1997
The time course of recovery of compound action potential (CAP) thresholds was observed in individual adult pigeons after severe acoustic trauma. Each bird had electrodes implanted on the round window of both ears. One ear was exposed to a tone of 0.7 kHz at 136-142 dB SPL for 1 hr ...
Ueda H - - 1997
To test if click-evoked otoacoustic emissions (CEOAEs) have frequency specificity, continuous changes in CEOAEs (especially frequency components of the CEOAE power spectrum) after pure-tone exposure in guinea pigs were examined. Pure-tone stimuli (0.5 kHz, 120 dB SPL; 2 kHz, 115 dB SPL; 4 kHz, 110 dB SPL) were given in ...
McFadden S L - - 1997
Remote masking (RM), the phenomenon whereby an intense high-frequency masking noise elevates thresholds for low-frequency signals, has been shown to be sensitive to various types of hearing loss in humans. We performed two experiments to evaluate the chinchilla as a model of RM and to examine changes in RM associated ...
Luxenberg JS - - 1997
A variety of modifications of the living environment have been proposed as beneficial for minimizing the psychological and behavioral symptoms of dementia, as well as promoting maximal functional independence. Potential modifications include physical design elements such as wandering pathways, electronically controlled exits, and secured outdoor courtyards as well as alterations ...
Quaranta A - - 1997
Remote masking (RM), the phenomenon whereby an intense high-frequency masker elevates thresholds for low-frequency signals, has been shown to be sensitive to various types of hearing loss in humans and to temporary threshold shifts in chinchillas. In this experiment, RM was evaluated in chinchillas with permanent threshold shift (PTS). Thresholds ...
Zheng X Y - - 1997
Previous work has shown that the cochlear efferent system may play a role in protecting the ear from noise-induced temporary threshold shifts (TTS) following exposures to a single tone or series of moderate-level noises ('toughening'). However, whether the olivocochlear bundle (OCB) is important in decreasing noise-induced permanent threshold shifts (PTS) ...
Litovitz T A - - 1997
We have previously demonstrated that microwave fields, amplitude modulated (AM) by an extremely low-frequency (ELF) sine wave, can induce a nearly twofold enhancement in the activity of ornithine decarboxylase (ODC) in L929 cells at SAR levels of the order of 2.5 W/kg. Similar, although less pronounced, effects were also observed ...
McFadden S L - - 1997
Studies have shown that loss of auditory sensitivity caused by exposure to high-level acoustic stimuli can be significantly reduced by pre-exposing the subject to moderate-level acoustic stimuli. Although the protective effects of such 'conditioning' exposures have been well documented, very little is known about the persistence of conditioning-induced protection, or ...
Penafiel L M - - 1997
The effect of 835 MHz microwaves on the activity of ornithine decarboxylase (ODC) in L929 murine cell was investigated at an SAR of approximately 2.5 W/kg. The results depended upon the type of modulation employed. AM frequencies of 16 Hz and 60 Hz produced a transient increase in ODC activity ...
Prato F S - - 1997
Exposure to extremely low frequency (ELF) magnetic fields has been shown to attenuate endogenous opioid peptide mediated antinociception or "analgaesia" in the terrestrial pulmonate snail, Cepaea nemoralis. Here we examine the roles of light in determining this effect and address the mechanisms associated with mediating the effects of the ELF ...
Saito Y - - 1996
To evaluate the effect of bright light on the sympathetic nervous system in human, muscle sympathetic nerve activity (MSNA) was recorded from the peroneal nerve in five healthy subjects. Each subject was exposed to bright light of 5000 lx for 20 min. After the bright light exposure, MSNA became significantly ...
Duan M L - - 1996
The forward masking curve of the auditory brainstem response (ABR) at selected frequencies together with the quantification of hair cell loss through the analysis of cochlear surface morphology was studied in guinea pigs before and after acoustic trauma resulting in either a temporary or a permanent threshold shift. In the ...
Ahroon W A - - 1996
Chinchillas were exposed to 1, 10, or 100 reverberant impulses at 150, 155, or 160 dB peak SPL. The impulses were generated by one of two different shock tubes, each producing blast waves having a different spectral composition, with one emphasizing low frequencies (< 0.5 kHz) and the other midfrequencies ...
Clark J A - - 1996
Guinea pigs were exposed to pure tones of 10 kHz at intensities between 98 and 115 dB SPL for 5-30 min, to produce varying degrees of acoustic trauma. Changes in auditory thresholds were measured electrophysiologically, and the animals were immediately fixed for scanning electron microscopy. Correlation between morphological changes to ...
Gastal M O - - 1996
The courtship of 5 jacks was evaluated weekly for 12 mo. The characteristics of sexual behavior were recorded before the collection of 2 ejaculates, at 4-h intervals, into an artificial vagina in the presence of a female in either natural or induced estrus. The maximum time given to the jack ...
Li S - - 1996
PURPOSE: We recently found that continuous light exposure at a moderate intensity triggered apoptosis of photoreceptor cells. Since intermittent light exposure is known to cause more severe retinal damage than is continuous light exposure, we sought to determine if intermittent light exposure also triggered apoptosis of photoreceptor cells. METHODS: Lewis ...
Rajan R - - 1996
1. An additivity model for the accretion of cochlear sensorineural hearing losses has been described from studies in the guinea pig cochlea. Among other aspects, the model allows determination of how residual hearing losses after an initial exposure (E1) affect hearing losses to be expected to a subsequent second exposure ...
Hotta S - - 1996
Electrophysiological methods were applied to 160 healthy adult male guinea pigs in order to investigate the effects of pure-tone exposure for 24 h on the inner ear. A reduction in cochlear microphonics (CM), action potential (AP) and endocochlear potential was observed following exposure to 110 dB at 100 Hz, 100 ...
Boettcher F A - - 1995
Distortion-product otoacoustic emissions (DPOAEs) and the endocochlear potential (EP) were recorded in adult Mongolian gerbils exposed to noise for either 1 or 12 days. The exposure was an octave band of noise centered at 4 kHz at 80 dB SPL with a duty cycle of 6 h on, 18 h ...
Holmberg K - - 1995
Annoyance and discomfort during exposure to high-frequency noise from an ultrasonic washer have been examined in the experiments carried out with 10 subjects. After a short exposure during which the subjects rated their annoyance and discomfort, a broad-band noise was matched to the ultrasound. The subjects were exposed to three ...
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