Protection of cochlear function from aminoglycosides ototoxicity by manganese superoxide dismutase gene in aging rat / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>determine the feasibility of manganese superoxide dismutase (MnSOD) gene therapy for protecting the cochlear function against aminoglycoside-induced oxidative stress in aging rats.</p><p><b>METHODS</b>The aging model of SD rats were obtained with 8 weeks daily of D-gal (150 mg/kg per day) hypodermic injection. In the 9th week, amikacin (500 mg/kg per day) were injected intramuscularly into some aging SD rats. The viral particles of recombinant adeno-associated viral vector II/MnSOD (6 microl, 5 x 10(11) vector genomes/ml) were injected into the perilymph through the round window membrane (RWM). The feasibility of MnSOD gene therapy against aminoglycoside-induced oxidative stress in aging rats was evaluated with the methods of caspase-3 protein analysis, apoptosis detection with immunohistochemical, the detection of MnSOD concentration, stretched preparation of basilar membrane and evaluation of hearing threshold with ABR-click.</p><p><b>RESULTS</b>Compared with the control group, the concentration of MnSOD of cochlear tissue was increased (P < 0.05), and the active fragment expression of caspase-3, the numbers of apoptosis bodies and the hearing threshold were decreased (P < 0.05).</p><p><b>CONCLUSIONS</b>MnSOD could play a partly role to treat cochlear aminoglycoside-induced oxidative damage in aging rats.</p>

Sensitivity to the ototoxicity of kanamycin of the rat model for mimetic aging in the inner ear / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To research the animal model with mimetic aging effect in the inner ear predispose to the ototoxicity of kanamycin.</p><p><b>METHODS</b>Fifty wistar rats were randomly divided into four groups: group A (D-galactose group, n = 14) were treated with hypodermic 5% D-galactose (150 mg x kg(-1) x d(-1)) for 8 weeks and then with intraperitoneal saline for 10 days; group B (D-galactose and kanamycin group, n = 14) were given the same dose of D-galactose but kanamycin (500 mg x kg(-1) x d(-1)) instead of saline; group C (kanamycin group, n = 12) were treated with saline for 8 weeks and then with intraperitoneal kanamycin for 10 days;group D (control group, n = 10) were given saline only. Auditory brainstem response (ABR) was used to detect the hearing threshold of rats and colorimetry was used to analyze the activity of the GSH-PX. The inner ear tissue was harvested and the mitochondrial DNA was amplified to identify the 4834 bp deletion mutation by nested primer polymerase chain reaction (nested PCR) technique.</p><p><b>RESULTS</b>The incidence of mitochondrial DNA 4834 bp deletion mutation was 100% (28/28) in group A, 92.86% (26/28) in group B and 0% in group C or group D. The activity of GSHPX in group A was (59.07 +/- 8.70)U, (63.29 +/- 12. 40)U in group B, (136.67 +/- 9.53)U in group C and (142.10 +/- 7.02)U in group D. The difference between group A and D was significant (P = 0.000) while the difference between group A and B was not significant (P = 0.307), which was similarly as between group C and group D (P = 0.151). ABR threshold was (5.36 +/- 3.08) dB peSPL in group A, (61.79 +/- 11.20) dB peSPL in group B, (34.17 +/- 4.69) dB peSPL in group C and (6.50 +/- 3.37) dB peSPL in group D. No difference was found between group A and D (P = 0.398) while the difference in shift of ABR threshold between group B and group C (or group D) was significant (P = 0.000).</p><p><b>CONCLUSIONS</b>The mimetic aging effect in the inner ear of the rat can be induced by D-galactose, and these rats present high incidence of mtDNA4834 deletion which can greatly enhance the sensitivity of the inner ear to the kanamycin.</p>

Oxidative stress experimental model of rat with stria vascularis marginal cells injury induced by hydrogen peroxide in vitro / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To set up the oxidative stress experimental model of rat cochlea with stria vascularis marginal cells injury induced by hydrogen peroxide in vitro.</p><p><b>METHODS</b>Cultured marginal cells of rat were treated by 200, 300, 400, 600 and 800 micromol/L hydrogen peroxide (H(2)O(2)) for 0.5, 1, 2, 4, 16 and 24 hours, respectively. Cell viability was assessed by the CCK-8 assay. The content of the lipid peroxidation production malondialdehyde (MDA) were detected in H(2)O(2) induced marginal cells injury with different concentration H(2)O(2). Apoptosis was assessed by flow cytometry by propidium sodium staining. The expression of the cleaved-caspase-3 was assessed by Western blot.</p><p><b>RESULTS</b>Being exposed to H(2)O(2), marginal cells displayed nuclear pyknosis and margination, cytoplasmic condensation, cell shrinkage and formation of membrane and bounded apoptotic bodies. A time-dependent and dose-dependent decrease of cellular viability was detected with the treatment of H(2)O(2). Cellular maleic dialdehyde was generated in proportion to the concentration of H(2)O(2) at 2 hours and the number of apoptotic cells increased significantly (P < 0. 05). Western blot showed the expression of the cleaved-caspase-3 increased when 200 micromol/L, 300 micromol/L and 400 micromol/L H(2)O(2) treated cultured marginal cells. Thereafter the expression of the cleaved-caspase-3 decreased with 600 micromol/L H(2)O(2) and with 800 micromol/L H(2)O(2) the expression of cleaved-caspase-3 was weak.</p><p><b>CONCLUSIONS</b>The findings indicated that the experimental model can be established successfully using cultured cells exposed to H(2)O(2) and activation of caspase-3 is associated with hydrogen peroxide induced rat marginal cells the oxidative stress injury.</p>

Timed balance test and static posturography in the patients with unilateral vestibular hypofunction / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the balance function of the patients with unilateral vestibular hypofunction (UVH) by timed balance tests and static posturography (SPG).</p><p><b>METHODS</b>Sixty-five subjects with UVH and 92 healthy subjects were taken the timed balance tests under differential stance including (1) standard Romberg test, (2) feet apart stance test, (3) tandem and (4) unilateral standing tests with eyes open and eyes closed. The average timing that subjects kept balance before falling in each standing conditions was recorded by stopwatch as the timed result. The body sway velocity during the test (1) and (2) were also recorded by the SPG.</p><p><b>RESULTS</b>The timed results of the tandem and unilateral standing with eyes open and eyes closed in the UVH group were decreased (P < 0.001) compared with the control group. The body sway velocity of the standard Romberg test and foot apart stance with eyes open was not different between the UVH group and control group (P-value was 0.118 and 0.110 for the two tests respectively), and the difference was significant in the eyes closed condition (P < 0.001). For the two groups, the body sway velocity of foot apart standing was decreased than that of the standard Romberg test with eyes open and eyes closed (P < 0.05 or P < 0.001). Significant correlations were not found between the timed results and sway velocity results in both two groups respectively (P > 0.05).</p><p><b>CONCLUSIONS</b>According to clinical assessment of balance function in UVH, the tandem and unilateral stance test could provide the additional information about the upright stance to the SPG measurement. The effect of foot position on the results of SPG should been considered in clinic.</p>

Comparison of three methods for isolation of nucleic acids from membranate inner ear tissue of rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Mitochondrial DNA mutations have been found in sensorineural deafness. The aim of this study was to compare three methods for extraction of nucleic acid from membranate inner ear tissue of rats.</p><p><b>METHODS</b>Alkaline denaturation, a conventional phenol-chloroform method and Trizol reagent were respectively used to extract the slight nucleic acid from membranate inner ear tissue of rats. We assessed the amount and quality of nucleic acid using a UV-spectrometer and polymerase chain reaction (PCR).</p><p><b>RESULTS</b>The yield and purity (OD260/OD280) of DNA from inner ear tissue using the phenol-chloroform method was the highest of the three methods. Mitochondrial DNA (mtDNA) fragment can be amplified by PCR from nucleic acid prepared by all methods, while no nuclear DNA (nDNA) fragment can be amplified by method of alkaline denaturation. Both nuclear and mitochondrial genes could be amplified by reverse transcriptional PCR from the RNA prepared by Trizol reagent.</p><p><b>CONCLUSION</b>Adequate amount and high-quality of mtDNA, nDNA and RNA were obtained from unilateral membranate inner ear tissue of rats. Method of alkaline denaturation could be chosen when mtDNA without nDNA was needed, while phenol-chloroform method was suitable for extracting total DNA (including nDNA and mtDNA); method with Trizol reagent was suitable for extracting total RNA and total DNA.</p>