Mutation Screening In Myosin6Gene In Nonsyndromic Hearing Impairment And The Effects Of Erythropoietin On Deaf

Research background:Hearing loss is a common disease in the human population which can cause obstacles in language communication and severely effect human health and life quality.It is estimated that one in every1000new born babies is congenital deaf and60%of which is suffering from hereditary hearing loss, however70%of those is caused by NSHI (nonsyndromic hearing impairment).Hereditary factor maybe be overlooked among lots of reasons that can cause hearing loss. At present many genetic mutation have found to be relevant to the hearing loss. Among62known nonsyndromic hearing loss genes, there are37recssive genes and25dominant genes. Hearing loss caused by genetic factors and environment factors varies among the same race and different races. The cause of prelinguistic deafness and its pathogenesis has become a hot issue among the Otolaryngology, Childcare experts, Eugenics physicians and other scholars.Objective:To ascertain the frequency and characteristics of myosin6gene mutations in Chinese children with prelingual nonsyndromic hearing impairment.Methods:Most of the cases were collected within Guandong provenience, including41hereditary prelingual deafness children and their mother, and50normal hearing children were used as control, total132cases. Genomic DNA Was extracted from the patients and subjected to the PCR to amplify selected exons of myosin6gene, and then the amplified products were screened for base variations by denaturing Gradient Gel electrophoresis (DGGE). The bands with abnormal performance were sequenced to confirm the mutation.Results:One patient and the other two patient’s mother were confirmed the mutation of Myo6.10sample:T to C substitution was detected at nucleotide738in exon9as hetrozygous state (738T�'T/C).17sample:A to G substitution was detected at nucleotide739in exon9as hetrozygous state (739A�'A/G), Its encoded amino acid has been changed from lie to Val which is missense mutation. T to C substitution was detected at nucleotide1292in exon13as hetrozygous state(1292T�'T/C), its encoded amino acid has been changed from leu to pro which is missense mutation.33sample:T to C substitution was detected at nucleotide711in exon9as hetrozygous state(711T�'T/C), A to G substitution was detected at nucleotide3281in exon32as homozygous state(3281A�'G), Its encoded amino acid has been changed from Asp to Gly which is missense mutation. And Sample17and sample33are mother and son.Conclusions:The Homozygous missense of Myo6gene (3281A�'G) is probably a novel mutation to cause prelingual nonsyndromic hearing impairment, which is autosomal recessive inheritance. Background:Deafness can be divided into conductive deafness、 sensorineural deafness and mixed deafness. Conductive deafness can be implemented hearing reconstruction operation to save and restore hearing. Sensorineural deafness is a common refractory crippling disease, due to the lack of effective therapy, disabled persons is not in the minority.In recent years it has been confirmed, Glutamate excitotoxicity is one of the major pathological mechanisms that cause neuronal injury in nervous diseases, the important mechanism of cochlear ischemia or noise damage is excitotoxicity by glutamate damage. One is the acute swelling of the neuron dendrites mediated by Glu binding to ionotropic receptors in the postsynaptic membrane;the other consists of a cascade of subsequent metabolic events, such as the neuronal apoptosis triggered by excessive Ca2+influx. Excessive accumulation of extracellular glutamate may lead to hyperexcitability of neurons.Therefore, minimizing neuronal apoptosis is the most direct and effective therapeutic approach.Objective:To observe the Glu—induced excitotoxic damage to the cochlear afferent neurons in guinea pig cochlear. To reveal if erythropoietin(EPO) has the protective effects on the glutamate induced excitotoxic damage of cochlear afferent neurons(type I spiral ganglion cell)after perilymphatic perfusion of glutamate.Method:26guinea pigs were divided into4groups.The first group (8animals, EPO group):glutamate (20mmol/1,10ul) was injected into the left scala tympani,EPO(0.1U/ml, flow rate0.5ul/h) was then continuously delivered to the same scala tympani60minutes post glutamate injection via mini-osmotic pump for14days;the second group (8animals, Glu group): the scala tympani perfusion of glutamate (20mmol/1,10ul) as experimental control;the third group (5animals, HBSS group):Hank’s balanced salt solution(HBSS) was continuously perfused into the left seal tympani via a mini-osmotic pump for the normal control;the fourth group(5animals, blank group):as the blank control group without any perilymphatic reperfusion. The CAP thresholds of the first three groups were recorded at1day and4weeks post-perilymphatic perfusion. Blank group were sacrificed after CAP recording.Results:1One days after tympani perfusion,the CAP threshold of group EPO and group Glu increased, with a significant difference between the HBSS and Blank groups (P<0.01). The CAP threshold of group EPO response has not declined4weeks later;there is no significant difference in CAP response threshold between HBSS group and Blank group (P>0.05).Conclusion:1.Glutamate application via scala tympani could result in excitoxic damage of cochlear type I spiral ganglion cells of guinea pigs.2. Local application of EPO did not play a protective effect on cochlear ganglion cell against glutamate neurotoxicity. Background:The age group most commonly affected by tracheobronchial foreign body (FB) aspirations (FBA) is children under the age of3years, in whom7%of deaths are related to FBA. The enhanced risk of aspiration in the0-to3-year-old age group is attributed to inadequately developed posterior dentition, immature neuromuscular mechanisms of deglutition and airway protection and the ubiquitous tendency of children of this age to put objects into their mouths. Failure to provide adequate supervision of a vulnerable child and allowing children easy access to small objects are also contributory factors. Potential differences in susceptibility within these first3years of life have not been studied extensively. The aim of this prospective study was to characterize the similarities and differences in children who experienced FBA at different times during the first3years of life.Objective:To investigate the clinical pathological features of aspirated tracheobronchial foreign body (FB) cases in children under the age of3years and to improve the level of diagnosis and treatment.Methods:A retrospective study was conducted examining316children under the age of3years who had been treated for tracheobronchial FB in Shenzhen children’s hospital between January2004and December2008. We analyzed the patients for gender, age, FB localization, treatment history, the history of foreign body aspiration (FBA), the type of foreign body and the cause of death. In addition, each patient was analyzed for FB-related complication, the results of bronchoscopic removal and the presence of foreign bodies in the airways.Results:Fifty-two infants under the age of one year (median age=10m, group A),199children between the ages of1and2years (median age=17m, group B) and65children between the ages of2and3years (median age=30m, group C) were included in this study. There were38(73.1%) patients with a confirmed history of FBA in group A, a higher percentage than that observed in group B (55.8%) or group C (53.8%)(P<0.05). Earthnuts were the most common cause of FB (171cases,54.1%).Melon seeds (including sunflower seeds, watermelon seeds and pumpkin seeds) were the second most common cause of FB (62cases,19.6%). Animal sources (including16pig bones,8fish bones,7chicken bones and4other animal-based foods) comprised11.1%(35cases) of FB cases and were the third most common cause of FB. The percentage of animal-based FBs observed in group A was higher than in groups B and C (P<0.01). Five inorganic FBs (a pushpin, a rubber band, a screw, a small stone and a plastic toy) were also observed and were the least common type of FB. There were no significant differences in the distribution of FBs between the left(41.8%) and right (40.5%) bronchia. There is no difference in the distribution of FBs among the three groups either.The data show that the youngest cohort of patients (0-1years) is the most likely to be sent to the hospital to receive treatment within24hours of aspiration(50%)(P<0.01). Five patients(1.58%) died as the result of FBA.Conclusions:FBAs of animal-derived FBs (especially animal bones) are very common in infants in southern China. Children between the ages of1and2years are most likely to suffer from FBA. FBA in children under the age of3years carries significant hazards, including morbidity and mortality. Asphyxia and/or cardiopulmonary arrest is prone to occur shortly after FBA in infants, but these events can occur days later in older children after FBA because of delays in the diagnosis and/or treatment of this condition.