[Standardization of the diagnosis and therapeutic evaluation is the basis of clinical research].
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Humans↗
Biomedical subjects
R Gu
Publications and source records attributed to R Gu.
[Effects of short-term tone exposure on DPOAEs].
Test parameter combinations are known to affect DPOAE measurement. The present study was attempted to find out if different test parameter combinations affect DPOAEs' utility in reflecting the change of cochlear function. Pure tones of moderate intensity (82 dB SPL) and short duration (3 min) were introduced into rabbit's ear canal to cause temporary change of cochlear mechanics, and the change of amplitude of 2f1-f2 DPOAE representing 10 kHz over 10 minutes after the exposure was monitored using equal- and different primary level combinations. It was found that, under the same exposure condition, 2f1-f2 DPOAEs induced by primaries of different levels (L2 = L1 - 12 dB) had showed more initial reduction in amplitude and slower recovery than that induced by primaries of equal levels (L1 = L2). The difference may indicate that there are multiple physiological processes that contribute to the generation of 2f1-f2 DPOAE and that change of DPOAE test parameters may selectively reveal different DPOAE generating processes.
Acoustic Stimulation↗
[Topographic mapping of slow cortical response in guinea pigs].
Auditory slow cortical responses (SCR) were studied in 10 awake guinea pigs using topographic mapping techniques. Fourteen electrodes were installed through the guinea pig skull and fixed with dental cement. Auditory SCRs were recorded via 13 leads and brain maps were realized on a concerto system. The results showed that SCRs were relatively stable at the temporal lobe, with a stable positivity (31.25-37.50 ms TP) followed by a negativity (62.50-72.50 ms TN). Variability was seen at other leads. The foci of maximum positivity and negativity were seen at the temporal cortex. The results suggest that there are multiple contributions to SCRs which partially overlap in time, and that auditory cortex contribute significantly more than other sources. SCRs also received auditory information in parallel from the brainstem. The focus of AM-evoked SCRs was seen located at temporal lobe while that of FM-evoked SCRs at temporal and frontal lobes. It suggests that intensity analysis is essentially completed at the temporal cortex whereas precise frequency discrimination relies on function of higher integrating centers.
Animals↗
[SERS and electrochemistry studies on the structure of thiourea adsorption layer on silver electrode].
The structure of thiourea adsorption layer on silver electrode was studied by SERS and electrochemistry. It was found that the thiourea can be adsorbed on the electrode surface and can inhibit the reaction of hydrogen separation. And a change in structure of the thiourea adsorption layer on electrode surface took place at the voltage of about -0.6V. The further SERS experiment showed that the thiourea adsorption layer has a loose structure at about -0.9V and a compact structure at about -0.3V - -0.5V. The transition region is at about -0.6V - -0.8V.
English Abstract↗
[SERS and electrochemistry studies on the inhibition of thiourea and phenyl-thiourea on iron].
An iron electrode was obtained by depositing a thin layer of iron on active silver electrode with overpotential deposition method. The E - I curve and SERS spectra of thiourea (TU) and phenyl-thiourea (PTU) adsorbed on the iron electrode surface were studied by means of electrochemistry and SERS spectroscopy. The results showed that both TU and PTU can be adsorbed on the iron electrode surface and the inhibition of PTU is better than TU in 0.1mol/L KCl solution. The adsorption mode of TU and PTU is similar in the interaction of S atom and iron surface. The cause of better inhibition effect of PTU lies in that the PTU can be more easily adsorbed on iron electrode because of more negative charge in its S atom and benzene ring in PTU is arranged away from the iron surface to form a rather compact adsorption layer due to steric hindrance.
English Abstract↗
Analysis of small hair bundles in the utricles of mature guinea pigs.
HYPOTHESIS: This study aimed to determine whether hair cells with immature hair bundles exist in the normal utricular maculae of mature guinea pigs. BACKGROUND: A low rate of hair cell "turnover" occurs in the vestibular organs of normal adult birds. Small immature-appearing hair cells have been identified in the utricles of juvenile guinea pigs, but their existence in the vestibular system of mature mammals has not been confirmed. METHODS: Nine utricles from 14- to 16-week-old guinea pigs were processed for scanning electron microscopy. A systematic search for small hair bundles was made. These bundles were classified as either "newborn-like" or "intermediate" depending on specific characteristics of the apical cell surface, the stereocilia, and the kinocilium. RESULTS: A mean of 7 newborn-like and 41 intermediate hair bundles per utricle were identified. The average hair cell count for the guinea pig utricular macula was 7,200; thus, these small hair bundles comprise 0.7% of the total. CONCLUSIONS: The small hair bundles are interpreted as developing vestibular hair cells, produced to replace hair cells lost to normal processes. This is thought to represent a biologic phenomenon that is in some ways similar, but in other ways distinct, from hair cell regeneration after trauma.
Animals↗
Effects of high intensity impulse noise on ionic concentrations in cochlear endolymph of the guinea pig.
OBJECTIVE: To investigate the effect of acoustic overstimulation on concentrations of cations in cochlear endolymph and analyze the relationship between the ionic changes in endolymph and the hearing loss. METHODS: The endocochlear potentials (EP), K+, Na+ and Ca2+ concentration in cochlear endolymph were examined in vivo for normal and 167 +/- 2 dB SPL impulse noise exposed groups of guinea pig bored on time course by means of double-barreled ion-selective microelectrodes. Brain stem auditory evoked potential (BAEP) was used to evaluate the auditory function. Ca(2+)-ATPase activity was demonstrated cytochemically in the lateral cochlear wall as induced by Ando et al with slight modification. RESULTS: The K+ and Ca2+ concentration exhibited significant changes in 8-hour groups (P < 0.05 for K+ and P < 0.01 for Ca2+). Then the K+ concentration was eventually resumed to the initial levels in accordance with the EP recovery in 7 days, while during the same period Ca2+ concentration was always significantly higher than that in control group (P < 0.01). The BAEP threshold shifts were correlated well with changes in ionic concentrations, especially Ca2+ (P < 0.001), in the endolymph induced by acoustic trauma. Although the normal positive EP was observed 7 days after noise exposure, the function of the vascular stria was not completely restored as revealed by the fact that the Ca(2+)-ATPase was diffused to the apical membrane surface. CONCLUSIONS: Endolymph compartment intrinsic mechanism for maintaining ionic composition is seriously deteriorated after high impulse noise stimulation. The changes of the unique environment of endolymph may play an important role in the mechanism of sensorineural hearing loss induced by acoustic trauma.
Animals↗
Growth factors as potential drugs for the sensory epithelia of the ear.
The highly ordered structures of the hearing and balance organs of vertebrate ears go through a coordinated sequence of cellular and morphogenetic events. It is to be expected that protein growth factors and other extracellular signals will regulate many events during embryonic development of the ear, including the induction of the ear, the specific induction of sensory epithelia, the proliferation of the cells that form the sensory epithelia, the differentiation of the sensory and supporting cells, and the attraction and maintenance of innervation. After embryonic development, growth factors will support cell survival and innervation of new sensory cells. In damaged sensory epithelia, supplementation of the normal growth factors in these tissues has the potential to influence cellular responses to trauma, to reduce cell death and to promote the replacement of dead cells through renewed proliferation and differentiation, so as to improve hearing and balance health via preventive and restorative treatments. Assessment of the influences of specific growth factors on the sensory epithelia of vertebrate ears is at an early stage: this paper provides a brief account of what we know from studies of normal and experimentally manipulated epithelia, discusses the current questions and suggests directions for future studies.
Animals↗
An RT-PCR analysis of mRNA for growth factor receptors in damaged and control sensory epithelia of rat utricles.
Sensory epithelia from normal rat utricles and those cultured with and without neomycin treatment were assayed for the presence of growth factor receptor mRNAs by RT-PCR (reverse transcriptase-polymerase chain reaction). Both undamaged and damaged utricles showed mRNA for Insulin receptor, IGF-I receptor, FGF receptor 1, EGF receptor, and PDGF alpha receptor. Neomycin-damaged sensory epithelia showed less PDGF alpha receptor mRNA than undamaged epithelia, suggesting that this message by expressed at higher copy levels in hair cells than in supporting cells. Consistent with that hypothesis, immunohistochemistry revealed much stronger PDGF alpha receptor staining in the hair cells than in the supporting cells. Preliminary evidence suggests that IGF-I receptor message also may be lowered in neomycin-damaged epithelia.
Animals↗
An observation on otoacoustic emission and ultrastructure of cochlea in experimental autoimmune inner ear disease.
OBJECTIVE: To acquire the detailed knowledge of immune lesion of inner ear. METHODS: A simultaneous study on physiology and ultrastructure was carried out in guinea pigs immunized with homogenous inner ear antigen. The specific antibody was analysed by a modified immunotransfer electrophoresis method. RESULTS: Three positive bands (with molecular weights of 68.0 kD, 62.7 kD and 60.1 kD) were found in all the sera of immunized animals but not in the control animals. Threshold shift of auditory brainstem response over 10dB HL was found in 42% of secondary system immunized animals and 32% of secondary endolymphatic sac (e.sac) immunized animals. Amplitude of distortion production otoacoustic emission dropped obviously in the above two groups. Transmission electron microscope showed the mitochondria of outer hair cells in the cochlea was impaired in animals with auditory disorder. CONCLUSIONS: The research suggests that the immune reaction against homogenous inner ear antigen results in dysfunction of hydroxycorticosteroid during the early stage.
Animals↗
Recent advances of otology in China.
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Aminoglycosides↗
[Electrical response recording of cochlear hair cells in vivo].
Intracellular recordings were made on cells of Corti organ from low-frequency region (third turn) of guinea pig cochlea, the recording sites being confirmed by HRP injection and subsequent histology. Response characteristies of the hair cells were studied. The Inner hair cells (IHCs) possessed relatively low resting membrane potentials in contrast to higher ones of OHCs. The receptor potentials from both cell types, in response to tone bursts, consisted of a combination of AC and DC components. For the low-frequency region, the receptor potentials were dominated by AC component. The causes of recording failure were discussed.
Animals↗
[Dysfunction of medial olivocochlear system and its audiological test].
The function of medial olivocochlear system (MOC) in patients with three kinds of auditory diseases was tested in order to investigate the relationship between MOC and retrocochlear impairment. Suppressive effect of evoked otoacoustic emissions (OAEs) by contralateral white noise was used as the indicator to evaluate the function of MOC in patients with: (1) sensorineural deafness with definite otoacoustic emissions, (2) hyperacusis and (3) tinnitus. Dysfunction of MOC was found in nine cases out of sixteen patients with sensorineural deafness and six cases out of fifteen patients with tinnitus. Two cases of hyperacusis also showed MOC dysfunction. It was concluded that MOC dysfunction may exist in some patients with sensorineural hearing loss and tinnitus, and in patients with hyperacusis as well. It seemed likely that dysfunction of MOC may played a role in causing tinnitus and hyperacusis in these patients. Testing the function of MOC may provide a helpful way for differential diagnosis of cochlear and retrocochlear impairment in auditory system.
Adolescent↗
[Nasal septal deviation in fetuses].
To investigate the etiology of nasal septal deviation, twenty-four fetal sinonasal specimens aged between 8-40 weeks of gestation were studied under light microscopy. Sixteen fetal heads aged between 32-40 weeks were examined using 2.7 mm 5 degrees Wolf endoscope. Five of 24 fetal sinonasal specimens were confirmed histopathologically to have deviated nasal septum. 1 of 16 fetal heads was considered to have nasal septal deviation. The existence of nasal septal deviation in fetuses was confirmed. To explain the embryogenesis, we suggested that maldevelopment of vomeropalatal complex is responsible for the formation of nasal septal deviation in fetuses.
Female↗
Two types of calcium channels in bullfrog saccular hair cells.
Ca2+ channels were studied in cell-attached recordings from the basolateral membrane of the bullfrog saccular hair cells with the EPC-9 patch-clamp system. Pipettes contained 110 mM Ba2+ and the membrane potential was zeroed with isotonic potassium aspartate. Data acquisition and analysis were performed using E9SCREEN and M2LAB software. L-type channel was distinguished by a single-channel conductance of 26 pS, activation range between -10 and +40 mV and intense activity even at a holding potential of -40 mV. The L-type channel showed characteristic bursts of brief openings (mode 1) interrupted occasionally by longer openings (mode 2). Bay K 8644 promoted the mode 2 activity and nifedipine inhibited L-type channel activity. Another type of calcium channels, 20 pS channel, was detected by -50 to +10 mV depolarizing steps from a holding potential of -40 or -80 mV. This channel was insensitive to dihydropyridines and resembled the N-type channel.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
[Calcium channels in bullfrog saccular hair cells].
In order to understand the cochlear physiology at a cellular and molecular level, Ca2+ channels were studied in cell-attached recordings from the basolateral membrane of the bullforg saccular hair cells with the EPC-9 patch-clamp system. Pipettes contained 110 mM Ba2+ and the membrane potential was zeroed with isotonic potassium aspartate. Data acquisition and analysis were performed using E9SCREEN and M2LAB software. L-type channel was distinguished by a single-channel conductance of 26 pS, activation range between -10 and +40 mV and intense activity even at a holding potential of -40 mV. The L-type channel showed characteristic bursts of brief openings (mode 1) interrupted occasionally by longer openings (mode 2). Bay K 8644 promoted the mode 2 activity and nifedipine inhibited L-type channel activity. Another type of calcium channels, 20 pS channel, was detected by -50 to +10 mV depolarizing steps from a holding potential of -40 mV or -80 mV. This channel was insensitive to dihydropyridines and resembled the N-type channel.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
Changes in the endocochlear potential and cochlear blood flow induced by ATP infusion and arterial occlusion.
To assess the relationship between cochlear blood flow (CBF) and auditory function, a procedure of intravital microscopy for observations of the lateral wall vessels of the cochlea coupled with the simultaneous measurement of the endocochlear potential (EP) was established in guinea pigs with gradual ischemia of the cochlea. It was found that occlusions of both common carotid arteries and one of the vertebral arteries produced a minor reduction in CBF with no significant alteration in the EP. When intravenous infusion of ATP induced sharp and severe decreases in CBF, the EP varied only slightly from the baseline in some animals while there were no alteration in others. Furthermore, ATP infusions combined with arterial occlusions caused even more severe declines in CBF and a moderate decrease in the EP. The results indicate that not only does the CBF satisfy the basic needs of the processes of cochlear function, but also has a regulatory mechanism to ensure the normal function of the cochlea in the ischemia condition. It was also found that the changes in the stria vascularis vessels induced by decreases in blood pressure (BP) and heart rates were more severe than those of the spiral ligament vessels. This phenomenon indicated that the stria vascularis vessels were more sensitive to decreases of BP and heart rates.
Adenosine Triphosphate↗
[Audiological test results of the autoimmune sensorineural hearing loss].
Audiological test results of 71 cases (130 ears) of clinically diagnosed autoimmune sensorineural hearing loss were analysed. Their audiograms can be divided into 4 types: low-frequency loss (55 ears), flat-type (26 ears), bell-type (17 ears) and high-frequency loss (32 ears). The test results of TEOAE, ABR, and -SP/AP amplitude ratio showed that the site of lesions in most of the low-frequency loss were retrocochlear, and most of the other three types were cochlear. Since about 1/3 of cases were chiefly involved retrocochlearly, the term "Autoimmune inner ear diseases" should not be used to substitute "Autoimmune sensorineural hearing loss".
Adolescent↗