The study on 235delC mutation of GJB2 gene in patients with idiopathic sudden hearing loss / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To analyze the rate of 235delC mutation in GJB2 gene in patients with idiopathic sudden hearing loss, and to explore its possible correlation with pathogenesis of idiopathic sudden hearing loss.@*METHOD@#Two hundred and thirty-four patients with diagnosis of idiopathic sudden hearing loss in otolaryngology department were recruited as experimental group. Eighty people with normal hearing level were enrolled as control group. Their peripheral blood samples were obtained and genomic DNA was extracted. Using polymerase chain reaction, the coding region of GJB2 gene was amplified, and 235delC mutation is screened for in GJB2 gene by restriction endonuclease. At same time the clinical data of 234 patients was collected to analyze.@*RESULT@#In 234 cases of idiopathic sudden hearing loss, 5 cases were found to have heterozygous 235delC mutation, none of them harbored homozygous 235delC mutation, the 235delC mutation rate was 2.1% (5/234). No 235delC mutation was found in control group. The rate of 235delC mutation in two group showed no statistically significant difference (P > 0.05).@*CONCLUSION@#This research shows that the rate of 235delC mutation in GJB2 is low in patients with idiopathic sudden hearing loss, and suggest that 235delC mutation possible has no correlation with idiopathic sudden hearing loss.

Muscarinic acetylcholine receptor subtype expression in type vestibular hair cells of guinea pigs / 华中科技大学学报（医学）（英德文版）

Recent studies have demonstrated that five subtypes (M1-M5) of muscarinic acetylcholine receptor (mAChR) are expressed in the vestibular periphery. However, the exact cellular location of the mAChRs is not clear. In this study, we investigated whether there is the expression of M1-M5 muscarinic receptor mRNA in isolated type II vestibular hair cells of guinea pig by using single-cell RT-PCR. In vestibular end-organ, cDNA of the expected size was obtained by RT-PCR. Moreover, mRNA was identified by RT-PCR from individually isolated type II vestibular hair cells (single-cell RT-PCR). Sequence analysis confirmed that the products were M1-M5 mAChR. These results demonstrated that M1-M5 mAChR was expressed in the type II vestibular hair cells of the guinea pig, which lends further support for the role of M1-M5 mAChR as a mediator of efferent cholinergic signalling pathway in vestibular hair cells.

Comparative morphology of the two type's hair cells from saccule and utricle under inverted phase contrast microscope / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To explore more reliable standards for identifying vestibular hair cells of saccule and utricle prepared in studies with patch clamp technique under inverted phase contrast microscope.@*METHOD@#The length and width of two type's hair cell's were measured besides the length of cilia, and all datas were analyzed statistically.@*RESULT@#The width and length of cilia of two types hair cells in saccule and utricle from guinea pig were similar. The length of type I was longer than that of type II, so the ratio between length and width was larger and the ratio of the length between cilia and cell body was small.@*CONCLUSION@#Two type's hair cells of saccule and utricle from guinea pig may be distinguished through the ratio of cell body's length and width even the ratio of the length between cilia and cell body, besides the standards before.

Comparative morphology of the two types hair cells from saccule and utricle under inverted phase contrast microscope / 临床耳鼻咽喉头颈外科杂志

Objective:To explore more reliable standards for identifying vestibular hair cells of saccule and utricle prepared in studies with patch clamp technique under inverted phase contrast microscope. Method:The length and width of two types hair cells were measured besides the length of cilia,and all datas were analyzed statistically.Result:The width and length of cilia of two types hair cells in saccule and utricle from guinea pig were similar. The length of type Ⅰ was longer than that of type Ⅱ,SO the ratio between length and width was larger and the ratio of the length between cilia and cell body was small.Conclnsion:Two type'S hair cells of saccule and utricle from guinea pig may be distinguished through the ratio of cell body's length and width even the ratio of the length between cilia and cell body,besides the standards before.

Investigation on degeneration of outer hair cells in guinea pig / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate the degeneration mechanics of outer hair cells in guinea pig.@*METHOD@#The mechanics of outer hair cells isolated by enzyme were observed under inverted microscope for 6-8 h continuously.@*RESULT@#Over half of living outer hair cells could keep good conditions in 6 hours. During the degeneration there was always a longitudinal fold line from tip to base. Presence or absence of calcium, as well as lossing of stereociliary bundle, couldn't change the conditions of out hair cells.@*CONCLUSION@#Neither calcium nor stereociliary bundle is the decisive cause in keeping outer hair cells alive, and its degeneration may be basically related with something surrounding the cell.

Promoter hypermethylation of DNA repair gene MGMT in laryngeal squamous cell carcinoma / 华中科技大学学报（医学）（英德文版）

The relationship between hypermethylation of CpG islands in the promoter regions of O6-methylguanine DNA methyltransferase (MGMT) genes and laryngeal squamous cell carcinoma was explored. Methylation-specific PCR and semi-quantitative RT-PCR were used to study the promoter methylation and mRNA expression of the MGMT gene in laryngeal carcinoma tissues, tissues adjacent to the tumor and normal laryngeal tissues. Hypermethylation of MGMT gene was detected in 16 samples of 46 (34.8%) laryngeal squamous cell carcinoma samples. However, the MGMT hypermethylation was not detected in all tissues adjacent to the tumors and normal tissues. No significant difference in MGMT gene hypermethylation was found in samples with different histological grades (chi2 = 3.130, P = 0.077) or in samples from patients with different TNM status (chi2 = 3.957, P = 0.138). No expression of MGMT mRNA was detected in all hypermethylated laryngeal carcinoma tissues. The expression of MGMT mRNA was detected in all unmethylated laryngeal carcinoma tissues, tissues adjacent to the tumors and normal tissues. It suggests that MGMT gene promoter hypermethylation is associated with MGMT gene transcription loss in laryngeal carcinoma tissues and possibly plays an important role in carcinogenesis of laryngeal tissues.

Promoter Hypermethylation of DNA Repair Gene MGMT in Laryngeal Squamous Cell Carcinoma / 华中科技大学学报（医学）（英德文版）

The relationship between hypermethylation of CpG islands in the promoter regions of O6methylguanine DNA methyltransferase (MGMT)genes and laryngeal squamous cell carcinoma was explored. Methylation-specific PCR and semi-quantitative RT-PCR were used to study the promoter methylation and mRNA expression of the MGMT gene in laryngeal carcinoma tissues, t issues adjacent to the tumor and normal laryngeal tissues. Hypermethylation of MGMT gene was detected in 16 samples of 46 (34.8 %) laryngeal squamous cell carcinoma samples. However, the MGMT hypermethylation was not detected in all tissues adjacent to the tumors and normal tissues. No significant difference in MGMT gene hypermethylation was found in samples with different histological grades (x2= 3. 130, P=0. 077) or in samples from patients with different TNM status (x2=3. 957, P=0. 138). No expression of MGMT mRNA was detected in all hypermethylated laryngeal carcinoma tissues. The expression of MGMT mRNA was detected in all unmethylated laryngeal carcinoma tissues, tissues adjacent to the tumors and normal tissues. It suggests that MGMT gene promoter hypermethylation is associated with MGMT gene transcription loss in laryngeal carcinoma tissues and possibly plays an important role in carcinogenesis of laryngeal tissues.

Properties of ACh-sensitive BK channels in mice type Ⅱ vestibular hair cells and its modulation by calcium / 中国病理生理杂志

AIM: To explore the properties of the acetylcholine(ACh)-sensitive potassium channel in type Ⅱ vestibular hair cells(VHCs Ⅱ) in mice saccular macula and the modulation effect of calcium ions.METHODS: Under the whole-cell patch mode,the pharmacology properties of ACh-sensitive potassium channel and the modulation of calcium ions on ACh-sensitive potassium channel were investigated.RESULTS: Following extracellular perfusion of ACh,VHCs Ⅱ displayed a slow and sustained outward current,which was sensitive to tetraethylammonium(TEA,5 mmol/L) and charybdotoxin(CTX,100 nmol/L),but not sensitive to 4-aminopyride(4-AP,15 ?mol/L).ACh-sensitive potassium current was inhibited by intracellular application of ethylene glycol-bis(B-aminoethylether)-N,N,N',N'-tetraacetic-acid(EGTA,5 mmol/L) and extracellular perfusion of Cd2+ and Ni2+,respectively.Intracellular application of heparin(8 g/L) failed to inhibit ACh-sensitive potassium current.CONCLUSION: Extracellular application of ACh activates the big conductance,calcium-dependent potassium current(BK) in VHCs Ⅱ of mice,which is potently modulated by extracellular Ca2+ ions.However,intracellular IP3-dependent Ca2+ ions release mechanism is not involved in the activation of the ACh-sensitive BK channel.