D-AP5 blocks the increase of intracellular free Ca2+ induced by glutamate in isolated cochlear IHCs / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the effect of D-AP5 (D-2-amino-5-phosphonopentanoate, a specific NMDA-antagonist) on the increase of intracellular free Ca2+ concentration ([Ca2+]i) induced by glutamate in isolated cochlear inner hair cells (IHCs), and to detect the autoreceptors of the IHC membrane.</p><p><b>METHODS</b>When a laser scanning confocal microscope (LSCM) was used, the exogenous glutamate (Glu)-induced changes in [Ca2+]i of isolated IHCs and OHCs of guinea pig cochlea were observed with fluo-3, a fluorescent probe for [Ca2+]i. After D-AP5 or CNQX (6--cyano--7--nitroguinoxaline--2, 3--dione, a specific AMPA- antagonist) was administered, the exogenous glutamate (Glu)-induced changes in [Ca2+]i of isolated IHCs were recorded.</p><p><b>RESULTS</b>In the presence of a low concentration Glu (3.85 mumol/L), there was an increase of [Ca2+]i in IHCs, whereas there was no change in OHCs. When 50 mumol/L of D-AP5 was administrated in advance, Glu did not induce a corresponding increase in [Ca2+]i in IHCs, and 50 mumol/L of CNQX did not completely block the increase of [Ca2+]i in IHCs.</p><p><b>CONCLUSIONS</b>These results suggest that the autoreceptors existing in the IHC membrane are mainly of NMDA type, while there are relatively few AMPA receptors. Exogenous Glu is capable of increasing [Ca2+]i in IHCs by acting on the NMDA autoreceptor of IHCs in a positive feedback manner.</p>

Deletions are easy detectable in cochlear mitochondrial DNA of Cu/Zn superoxide dismutase gene knockout mice / 中华医学杂志(英文版)

<p><b>OBJECTIVES</b>To investigate the tissue specificity of reactive oxygen species (ROS) damage to mitochondrial DNA (mtDNA) and to determine whether cochlear mtDNA is a sensitive target for ROS damage.</p><p><b>METHODS</b>10 Cu/ZnSOD gene (Cu/Zn superoxide dismutase gene, Sod1) knockout mice and 16 wild-type mice were analyzed by nested polymerase chain reaction (PCR).</p><p><b>RESULTS</b>Three deletions were detected in various tissues of Sod1 knockout mice. MtDNA3867bp and mtDNA3726bp deletions were the most visible, and mtDNA4236bp deletion was barely detected in these tissues. There were obvious differences in the ratio of deleted mtDNA/total mtDNA in different tissue. Deleted mtDNA was most abundant in the liver and kidney and less in cochlea, heart and brain. The lowest was in spleen and skin. The ratio in various tissues was 3 - 20 times in Sod1 knockout mice over wild-type mice. In cochlea, the ratio was about 15.</p><p><b>CONCLUSIONS</b>Without the protection of Sod1, ROS can lead to mtDNA deletions in various tissues with significant tissue specificity. Cochlear mtDNA is a sensitive target for ROS damage.</p>

Screening for mitochondrial DNA mutation in two pedigrees with nonsyndromic inherited sensorineural hearing loss / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic mechanism of maternal nonsyndromic inherited sensorineural hearing loss(SNHL), to identify the incidence of the 7445(G) mutation in such pedigrees and sporadic patients with SNHL, and to provide the theoretical evidence for the diagnosis of this disease.</p><p><b>METHODS</b>Blood samples were obtained from 2 pedigrees and 14 sporadic patients with SNHL. DNA was extracted from the isolated leukocytes. The mitochondrial DNA (mtDNA) fragments were amplified by PCR. The 1555(G), 3243(G) and 7445(G) mutation was detected by Alw 26 I, Apa I and Xba I restriction endonuclease digestion respectively. The sequence of 12S rRNA, tRNA(Leu(UUR)) and tRNA(Ser(UCN)) was examined.</p><p><b>RESULTS</b>Restriction endonuclease digestion analysis showed that 12 individuals from 2 pedigrees carried homoplasmic 7445(G) mutation, which was of maternal inheritance. Six individuals from 2 pedigrees and 14 sporadic patients did not have 7445(G) mutation. All individuals did not have 1555(G) and 3243(G) mutation. The sequence analysis further showed that none of them carried homoplasmic 1555(G) and 3243(G) mutation, 12 individuals had (nt)7445 A--> G substitution in tRNA(Ser(UCN)) gene.</p><p><b>CONCLUSION</b>The incidence of 7445(G) mutation in such pedigrees is higher than that in sporadic patients. Screening for mtDNA 7445(G) mutation combined with 1555(G) examination is of much value to clinical use.</p>

Cochlear mitochondrial DNA3867bp deletion in aged mice / 中华医学杂志(英文版)

<p><b>OBJECTIVES</b>To study the status of cochlear mitochondrial DNA (mtDNA) and to determine the location of mtDNA deletion in aged mice.</p><p><b>METHODS</b>We detected cochlear mtDNA in 2, 7 - 10 and 17 - 19 month old mice by nested polymerase chain reaction (PCR) and DNA sequencing.</p><p><b>RESULTS</b>mtDNA3867bp deletions were found in the cochleae of aged mice. The deletion occurred within nt9103-nt12970 and were flanked by 15 base pair direct repeats. Comparing the incidence of mtDNA3867bp deletions, 17 - 19 month old mice (7/8) were significantly higher than 7 - 10 month old mice (4/16). The deletion was not observed in 2 month old mice (0/7). The ratio of deleted mtDNA/total mtDNA in 17 - 19 month old mice was higher than in 7 - 10 month old mice (P < 0.001).</p><p><b>CONCLUSION</b>Cochlear mtDNA 3867bp deletion in aged mice may be related to presbycusis.</p>

STUDY OF VESTIBULAR AQUEDUCT WITH COMPUTED TOMOGRAPHY IN MENIERE′S DISEASE / 解放军医学杂志

Objective To study the vestibular aqueduct(VA) with CT in Meniere,s disease(MD). Method The experiment consisted of three groups: normal ear group, non-MD vertigo group and MD group. VA in each group was examined with CT, and the width of the external aperture of VA was measured.Result VA in normal ear group and non-MD vertigo group was well visualized,and non-visualization rate was 9.1%. VA non-visualization rate in MD group was 75%, external aperture was narrowed in VA patients. Conclusion non-visualization or narrowing of the enterhal aperture can be considered as one of the diagnostic sings of MD.

Herpesviridae and laryngeal neoplasia / 临床耳鼻咽喉头颈外科杂志

Objective:To investigate the relationship between herpesviridae and malignant or benign laryngeal diseases.Method:128 paraffin-embedded laryngeal squamous cell carcinoma and laryngeal epithelium hyperplastic lesions were detected by polymerase chain reaction (PCR) and PCR-ISH for herpesviridae. Result:HSV-1 was detected in 10 cases by PCR,among them 3 were laryngeal squamous cell carcinoma (LSCC),1 was carcinoma in situ(CIS),4 were laryngeal polyps and 2 were laryngeal keratosis. Except 1 LSCC and 1 CIS, 8 of 10 cases were positive while detected by PCR-ISH. In benign diseases, signals were shown from basal layer to superficial cell; in malignant lesions, the signals were scattered in the diseases.Conclusion:Most of laryngeal diseases were not related to herpesviridae, but HSV-1 may acts as initiator in the development of a few cases.

Isolation of outer hair cells from varying turns of the guinea-pig cochlea / 临床耳鼻咽喉头颈外科杂志

Objective:To probe the method of isolating outer hair cells (OHC) from each of four turns of the guinea-pig cochlea. Method:From eight guinea pigs the organ of Corti from each of four turns of the cochlea were dissected, and then treated using enzyme. Result:A fair amount of living OHCs from each of four turns were obtained. The length of OHCs from each of four turns were 23.81,34.50,60.48 and 71.37 μm. Conclusion:The key to success in isolating OHCs from each of four turns of the cochlea is to know very well the anatomical characteristics of each of four turns of the cochlea and be operated in accordance with normal rules.

STUDY OF VESTIBULAR AQUEDUCT WITH COMPUTED TOMOGRAPHY IN MENIERE′S DISEASE / 解放军医学杂志

Objective To study the vestibular aqueduct(VA) with CT in Meniere , s disease(MD). Method The experiment consisted of three groups: normal ear group, non-MD vertigo group and MD group. VA in each group was examined with CT, and the width of the external aperture of VA was measured.Result VA in normal ear group and non MD vertigo group was well visualized,and non visualization rate was 9.1%. VA non visualization rate in MD group was 75%, external aperture was narrowed in VA patients. Conclusion non visualization or narrowing of the enterhal aperture can be considered as one of the diagnostic sings of MD.

IDENTIFICATION OF THE HUMAN SERUM ANTIBODIES TO THE MEMBRANOUS LABYRINTH PROTEIN OF THE INNER EAR / 解放军医学杂志

The aim of the study was to establish the clinical method for the detection of the human serum antibodies reacting to the membranous labyrinth protein using the Western immunoblotting labeled with boition streptavidin. Different control experiments were conducted, which included the human serum empty control, the biotin labeled antibody empty control, the avidin blocking control, the serum control of patient with autoimmune sensorineural hearing loss and that of patient with autoimmune disease. By comparing the different expressions in these experiments, it was suggested that the reacting band at 65kD, and the dark reacting bands at 82kD or within 56~48kD or 33~30kD should be identified as positive reaction of the human serum antibodies to the membranous labyrinth protein. The positive rates of 65kD were 30.4%~82.6% with the confidence intervals of 95%, and 23.8%~87.0% with the confidence intervals of 99%. The confidence intervals were 18%~72% and 13.4%~77.6% respectively, for 95% and 99% positive rates of the latter 3 bands combined. The reacting bands at 134kD and 70kD indicated affinity to avidin and streptavidin, which did not relate to positive reaction.

PEDIGREE ANALYSIS OF OTOSCLEROSTIC FAMILIES / 解放军医学杂志

This paper presented the hereditary pattern of otosclerosis in families. Among 1500 cases there were 13 patients, belonging to 6 families, and 20 ears were surgically treated. There was often a marked similarity in clinical features of affected siblings within the same family.The clinical characteristics are as following: (1) The age at inset of hearing loss seems similar. There is a difference of 1 or 2 years in two families znc 3 to 10 years in the other four. (2) The side of first hearing loss is the same in affected individuals of 6 families. (3) The propositi are females in 5 families (83.3%). (4) Auditory curve of hearing loss is similar in 4 familiers, and different in the other two. (5) The footplate lesions are similar in macroscopic features, thin footplate in two fimalies and thick footplate in the other four.

VESTIBULAR FUNCTION BY THE AIR CALORIC TEST / 解放军医学杂志

40 normal persons were subjected to the air caloric test, 10 of whom also to the Hallpike water caloric test. The results showed no substantial differences between the air and water caloric stimulation. The normal values were obtained. There were no differences between right and left labyrinthes. The warm stimulation was more intense than the cold. Speed of slow component is the most important parameter of electronystagmograph.