Objective To establish the mice model of AHL, to investigate the relationship between AHL and the cytoactive factors of the cochlear hair cells in C57BL/6J mice, and to classify the presbycusis models of the C57BL/6J mice. Methods C57BL/6J mice were divided into 6 experimental groups by age (A: 3 months old(m), B: 8 m, C: 9 m, D: 10 m, F: 17 m, G: 18 m) . The auditory functions mice were measured by auditory brainstem response (ABR) with the stimulus click and toneburst at 6 kHz and 8 kHz. 3 months later, Groups C , G, E and H were tested again for ABR. After ABR testing, the cytoactive of the hair cells was detected by succinate dehydrogenase staining and surface preparation technique(two mice from each group except groups C and G). Results The ABR thresholds elevated with age, and the marked change of the cochlea was the degeneration of the cytoactive of the cochlear hair cells, especially those of the outer hair cells. In the beginning, the basement of the basal membrane suffered from the mitochondrion degeneration in the outer hair cells, then it spread to the top region. Subsequently, the inner hair cells were involved. Conclusion C57BL/6J mouse was a typical animal model for the AHL,and the main change of the cochlea was the degeneration of the hair cells, especially the outer hair cells. Thus, C57BL/6J mice can be used as a suitable animal model for the study of presbycusis.

OBJECTIVE: To evaluate clinical value of electrocochleography in diagnosing the Meniere's disease. METHOD: Patients were saperated as having definite, probable and possible Meniere's disease according to the 1995 AAOHNS guidelines. Then set the probable and possible Meniere's disease as a suspected group. We used four different stimulus (clicks, 1000 Hz tone burst, 2000 Hz and 4000 Hz tone burst) to record electrocochleo-graphy. Those patients in each group received electrocochleography examination, and summating potential (SP)/action potential (AP) ratios were calculated. A prolonged action potential latency shift (AP shift) evoked by rarefaction and condensation clicks was also measured. RESULT: The click SP/AP positive rate in definite Meniere's disease group was 41.2%, tone burst at 1,000 Hz. 2,000 Hz,4,000 Hz were respectively 80.4%, 72.5%, 37.3%, AP shift positive rate was 45.1%. Using McNemar test, the positive rate of tone burst 1000 Hz (chi2 = 15.04, P < 0.01) and that of tone burst 2,000 Hz (chi2 = 8.65, P < 0.01) were statistically significant different when compared with that of click SP/AP, besides the tone burst at 1,000 Hz yielded has the highest sensitivity. The click SP/AP positive rate in suspected group and definite group were respectively 12% and 45.1% (chi2 = 6.610, P < 0.05) and AP shift positive rate of them were respectively 8.0% and 41.2% (chi2 = 10.460, P < 0.01). By chis-quare test, the positive rates of click SP/AP and AP shift between these two groups were statistically significant different. CONCLUSION Electrocochleography is a reliable test in the diagnosis of Meniere's disease. Compared with clicks, tone burst significantly has a higher sensitivity, especially at 1000Hz and 2000Hz frequencies. A prolonged action potential latency shift evoked by rarefaction and condensation clicks is also a useful addition to diagnosis Meniere' disease.
Adolescent ; Adult ; Aged ; Audiometry, Evoked Response ; Female ; Humans ; Male ; Meniere Disease ; diagnosis ; Middle Aged ; Young Adult

The distribution of the Na-K-2Cl co-transporter (NKCC1) in the cochlear K+ cycling pathway in cochlea and cochlear histological changes in the NKCC1 knockout mice were investigated. By using immunohistochemistry and toluidine blue staining, the localization of NKCC1 in cochlea of the C57BL/6J mice and the cochlear histological changes in the NKCC1 knockout mice were observed. It was found that the NKCC1 was expressed mainly in the stria marginal cells and the fibrocytes in the inferior portion of the spiral ligament in the adult C57BL/6J mice. Subpopulation of the fibrocytes in the suprastrial region and the limbus was also moderately immunoreactive. While in the cochlea of the NKCC1 knockout mice, Reissner's membrane was collapsed and scala media disappeared, accompanied with the loss of inner hair cells, outer hair cells and the support cells. The tunnel of Corti was often absent. All the findings suggested the localization of NKCC1 in the cochlea was closely correlated with cochlear K+ cycling. Loss of NKCC1 led to the destruction of the cochlear structures, and subsequently influenced the physiological function of cochlea.

Objective To estimate the impact of the image quality of conebeam CT on the accelerator for the Bowtie filter. Methods This study used the system of conebeam CT on the accelerator,and scaned the phantom of Catphan 500 in the multiplicate scanning conditions with and without the Bowtie filter. The scanning conditions were : voltage :120 kV, 100 kV, 80 kV, electricity:25 mA, 40 mA, 64 mA,time of exposure :40 MHz, collimator: M20, L20, scanning angle :358°. We transmitted the scanning data in the treatment planning systems of Philips Pinnacle 8. 0, and estimated the influence of the image quality.Results With and without the Bowtie filter, all of the images had high geometric precision, and the maximum difference of the nominal and actual distance at the horizontal, vertical and arrowy directions in the transection were 0. 50% and 0. 56% ( t = 0. 44, P ＞ 0. 05 ), 0. 44% and 0. 48% ( t = 1.01, P ＞ 0. 05 ),0. 50% and 0. 56% (t = 1.06,P ＞0. 05 ), respectively. The spatial resolution was 0. 167 cm, immutably.The ununiformity with the Bowtie filter was decreased of 28.0% -76.0% (t=2.53,P＜0. 05)、2.8%-50.0% (t= 3.02,P＜0.01 ) than those without the Bowtie filter, and the contrast-to-noise ratio was increased of 4.0% -41.6% (t=2.70,P＜0.05)、4.0% -50.0% (t=2.14,P＜0.05), using the collimators of M20 and L20, respectively. The Bowtie filter could display clearly the edge of scanning phantom, and improve the CT number of the image edge of phantom. And the linearity of CT number was also improved. Couclusions With the Bowtie filter, the image uniformity, the precision and linearity of CT number and the contrast-to-noise ratio were improved obviously, the edge artifacts were decreased, and the geometric precision and the spacial resolution did not change.

Objective To study the expression of plasma membrane Ca2 + -ATPase isoforms 1 -4 and the splice variants at sites A and C in the neonatal rat vestibular organ.Methods Ten rats at postnatal 2 days (P2 ) were decapitated and their vestibular organs (macula utriculi and macula sacculi)were isolated.The total proteins of the vestibular organs were extracted.The expression of PMCA1-4 splice variants at sites A and C was detected by RT-PCR.Results The splice variants of PMCA1-4 at sites A and C in macula utriculi and macula sacculi of neo-natal rat vestibular organs were PMCA1x/b,PMCA2w/(a,b),PMCA3z/(a,b,c)and PMCA4 (x,z)/b.Conclusion The splice variants at sites A and C among PMCA1,PMCA2,PMCA3 and PMCA4 were different in the vestibu-lar organs of neonatal rats,which could be explained that macula utriculi and macula sacculi had different require-ments of Ca2 + turning for these PMCA isoforms.

Objective To study the expression of plasma membrane Ca2+-ATPase isoforms 1~3 (PMCA 1~3 )in the basilar membrane (BM)of the neonatal rat cochlea by Western blot.The PMCA2 content in single BM of the neonatal rat was also examined.Methods Four rats at postnatal 2 days (P2)and 8 days (P8)were respective-ly decapitated and their BMs were isolated.The total proteins of BMs were extracted.The 20μg total proteins were respectively loaded to the gel.The expression of PMCA1-3 was detected by Western blot.Likewise,3μg total proteins from P2 and P8 rat BM were loaded.The expression of PMCA2 was detected by Western blot.Four rats at P8 were decapitated and their BM was isolated.The 5μg,10μg and 20μg total proteins of P8 rat BM were added to the gel and 100 ng,400 ng and 800 ng bovine serum albumin (BSA)were also loaded as reference.After electro-phoresis,the gel was separated into two parts.One part was used for SYPRO staining and the other part was used for PMCA2 detection by Western blot.Results In the 20μg BM total proteins of P2 and P8 rats,the expression of PMCA1 was weak (0.126±0.024,0.131±0.012,respectively),PMCA2 was strong (4.16±0.528,4.25±0.319, respectively),and PMCA3 was barely expressed (0 ).There was a statistical difference among PMCA1 ,PMCA2 and PMCA3(P<0.05).In the 3μg BM total proteins of P2 and P8 rats,the expression of PMCA2 in P8 (4.571± 0.336)was higher than P2 (3.622±0.285).There was a statistical difference(P<0.05).The PMCA2 content in the BM of a P8 rat was about 2 .5 ng.Conclusion There was a different-level expression of PMCA1~3 in the neonatal rat BM with highest expression of PMCA2 ,which could be explained that cochlear hair cells had different requirements of Ca2+ turning for these PMCA isoforms.

This study examined the expression pattern of programmed cell death 5 (PDCD5) in cochlear hair cells and spiral ganglion neurons (SGNs) and its association with age-related hearing loss in mice. Sixty C57BL/6J (C57) mice at different ages were divided into four groups (3, 6, 9 or 12 months). PDCD5 expression was detected by using immunohistochemistry, real-time PCR and Western blot. Morphological change of the cochleae was also evaluated by using immunoassay. The results showed that the expression of PDCD5 had a gradual increase with ageing in both protein and RNA levels in C57 mice, as well as gradually increased apoptosis of cochlear hair cells and SGNs. In addition, we also found that caspase-3 activity was enhanced and its expression was enhanced with ageing. It is implied that overexpression of PDCD5 causes the increase in caspase-3 activity and the subsequent increase of apoptosis in cochlear hair cells and SGNs, and thereby plays a role in the pathogenesis of presbycusis. Thus, PDCD5 may be a new target site for the treatment and prevention of age-related hearing loss.

OBJECTIVE: L-type voltage-gated calcium channel subunit alpha1D-/- mice (homozygous mutant, knockout), alpha1D+/- (heterozygous) and alpha1D+/+ (wild-type) have played role in L-type voltage-gated calcium channel alpha1D subunit in auditory function of inner ear as well as sinoatrial node function of the mice. METHOD: Hearing threshold and endocochlear potential (EP) were measured in the alpha1D knockout mice, heterozygous mice and wild-type mice by auditory brainstem response(ABR), EP recordings and Electrocardiograph (ECG) respectively. To assessment of the vestibular function of the mice, the ability of Balancing was performed by a swim test and a horizontal cylinder test. RESULT: The auditory function of alD+/+ mice were normal, the mean value for ABR thresholds in response to click sound stimulus was (34.8 +/- 5.7) dB SPL,EP was (105.3 +/- 3.1) mV. The mean value for ABR thresholds in response to click sound stimulus was elevated in alpha1D+/- mice was (54.4 +/- 12.4) dB SPL, relative to that observed in alpha1D+/+ mice significantly increased (P < 0.05); EP of alpha1D+/- mice was about (75.8 +/- 9.9) mV. alpha1D-/- mice were completely deaf, the ABR wave form was not observed for even 100 dB SPL sound stimuli used and EP was still remain in (48.6 +/- 19.3) mV. alpha1D knockout mice were deaf and demonstrated no vestibular defect. alpha1D+/- and alpha1D-/- mice show significant sinus bradycardia with significant prolongation of the RR interval (146 +/- 1.4 and 244 +/- 2.9, respectively) comparing to the alpha1D+/+ wild-type mice (117 +/- 0.4) in the same littermates. In addition, the homozygous alpha1D-/- show a significant prolongation of the PR interval (53 +/- 0.5) compared to that of the a1D+/+ wild-type mice (38 +/- 0.3). CONCLUSION L-type voltage-gated calcium channel alpha1D subunit plays a critical role in calcium homeostasis in the inner ear. Mice lacking of alpha1D calcium channel gene would lead to influence auditory function and sinoatrial node dysfunction subsequently.
Animals ; Auditory Threshold ; Calcium Channels, L-Type ; genetics ; Deafness ; genetics ; physiopathology ; Electrocardiography ; Evoked Potentials, Auditory, Brain Stem ; Mice ; Mice, Knockout ; Sinoatrial Node ; physiopathology

The distribution of the Na-K-2Cl co-transporter (NKCC1) in the cochlear K+ cycling pathway in cochlea and cochlear histological changes in the NKCC1 knockout mice were investigated. By using immunohistochemistry and toluidine blue staining, the localization of NKCC1 in cochlea of the C57BL/6J mice and the cochlear histological changes in the NKCC1 knockout mice were observed. It was found that the NKCC1 was expressed mainly in the stria marginal cells and the fibrocytes in the inferior portion of the spiral ligament in the adult C57BL/6J mice. Subpopulation of the fibrocytes in the suprastrial region and the limbus was also moderately immunoreactive. While in the cochlea of the NKCC1 knockout mice, Reissner's membrane was collapsed and scala media disappeared, accompanied with the loss of inner hair cells, outer hair cells and the support cells.The tunnel of Corti was often absent. All the findings suggested the localization of NKCC1 in the cochlea was closely correlated with cochlear K+ cycling. Loss of NKCC1 led to the destruction of the cochlear structures, and subsequently influenced the physiological function of cochlea.

This study examined the expression pattern of programmed cell death 5 (PDCD5) in cochlear hair cells and spiral ganglion neurons (SGNs) and its association with age-related hearing loss in mice.Sixty C57BL/6J (C57) mice at different ages were divided into four groups (3,6,9 or 12 months).PDCD5 expression was detected by using immunohistochemistry,real-time PCR and Western blot.Morphological change of the cochleae was also evaluated by using immunoassay.The results showed that the expression of PDCD5 had a gradual increase with ageing in both protein and RNA levels in C57 mice,as well as gradually increased apoptosis of cochlear hair cells and SGNs.In addition,we also found that caspase-3 activity was enhanced and its expression was enhanced with ageing.It is implied that overexpression of PDCD5 causes the increase in caspase-3 activity and the subsequent increase of apoptosis in cochlear hair cells and SGNs,and thereby plays a role in the pathogenesis of presbycusis.Thus,PDCD5 may be a new target site for the treatment and prevention of age-related hearing loss.