Biomedical subjects

Guangqian Xing

Publications and source records attributed to Guangqian Xing.

8 recordsLinked to original sources

PubMed2007

Mitochondrial rRNA and tRNA and hearing function.

The human ear is a delicate sensory apparatus of hearing for normal communication, and its proper functioning is highly dependent on mitochondrial oxidative phosphorylation. The first mitochondrial point mutation for nonsyndromic and aminoglycoside-induced hearing loss was identified in 1993. Since then a number of inherited mitochondrial mutations have been implicated in hearing loss. Most of the molecular defects responsible for mitochondrial disorder-associated hearing loss are mutations in the 12S rRNA gene and tRNA genes. In this review, after a short description of normal hearing mechanisms and mitochondrial genetics, we outline the recent advances that have been made in the identification of deafness-associated mitochondrial mutations, and discuss how mitochondrial dysfunction contributes to hearing loss.

Aminoglycosides↗

PubMed2006

Clinical and genetic features in a Chinese pedigree with autosomal dominant auditory neuropathy.

BACKGROUND: A variety of processes and etiologies are thought to be involved in the pathophysiology of auditory neuropathy (AN). However, little is known about the clinical and molecular characteristics of hereditary AN. OBJECTIVE: To explore the clinical and genetic findings of a Chinese family with AN. METHODS: Seven patients in three consecutive generations of the pedigree were selected. Detailed history collection, physical examination, and audiological evaluations including pure-tone audiometry, acoustic immittance, auditory brainstem responses, cochlear microphonics, and evoked otoacoustic emissions, and mitochondrial DNA analysis were performed. RESULTS: All subjects involved are offspring of a female ancestor in the pedigree. In 6 of them, the hearing impairment started before the age of 9. Audiograms showed bilateral, symmetric, and profound deafness. Other audiological examinations revealed absent acoustic reflexes and auditory brainstem responses, and preserved evoked otoacoustic emissions and cochlear microphonics. One subject was characterized by normal audiological findings except high-frequency hearing loss with later onset. Hearing deterioration was found in 2 subjects who were followed for 26 months. Physical examination and mitochondrial DNA analysis yielded normal results. CONCLUSIONS: Clinical features in the pedigree are consistent with type II AN. Pedigree analysis and molecular findings indicate an autosomal dominant inheritance.

Adolescent↗

PubMed2006

Mitochondrial 12S rRNA A827G mutation is involved in the genetic susceptibility to aminoglycoside ototoxicity.

We have analyzed the clinical and molecular characterization of a Chinese family with aminoglycoside-induced and non-syndromic hearing impairment. Clinical evaluations revealed that only those family members who had a history of exposure to aminoglycoside antibiotics subsequently developed hearing loss, suggesting mitochondrial genome involvement. Sequence analysis of the mitochondrial 12S rRNA and tRNA(Ser(UCN)) genes led to the identification of a homoplasmic A827G mutation in all maternal relatives, a mutation that was identified previously in a few sporadic patients and in another Chinese family with non-syndromic deafness. The pathogenicity of the A827G mutation is strongly supported by the occurrence of the same mutation in two independent families and several genetically unrelated subjects. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly conserved in mammals. It is possible that the alteration of the tertiary or quaternary structure of this rRNA by the A827G mutation may lead to mitochondrial dysfunction, thereby playing a role in the pathogenesis of hearing loss and aminoglycoside hypersensitivity. However, incomplete penetrance of hearing impairment indicates that the A827G mutation itself is not sufficient to produce clinical phenotype but requires the involvement of modifier factors for the phenotypic expression. Indeed, aminoglycosides may contribute to the phenotypic manifestation of the A827G mutation in this family. In contrast with the congenital or early-onset hearing impairment in another Chinese family carrying the A827G mutation, three patients in this pedigree developed hearing loss only after use of aminoglycosides. This discrepancy likely reflects the difference of genetic backgrounds, either mitochondrial haplotypes or nuclear modifier genes, between two families.

Aminoglycosides↗

PubMed2006

Maternally inherited non-syndromic hearing loss associated with mitochondrial 12S rRNA A827G mutation in a Chinese family.

We explored the clinical and molecular characterization of a Chinese family with non-syndromic hearing impairment. Clinical evaluations revealed a possible maternal inheritance pattern, and showed an extremely similar phenotype of hearing loss including the age of onset, severity, and audiometric configuration. Sequence analysis of the mitochondrial 12S rRNA and tRNA(Ser(UCN)) genes led to the identification of a homoplasmic A827G mutation in all maternal relatives, which was absent in other family members and 40 Chinese controls. This mutation has previously been reported sporadically in a few individuals with aminoglycoside-induced and non-syndromic hearing loss. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly evolutionarily conserved in mammals. The occurrence of the A827G mutation in these genetically unrelated subjects strongly suggests that this mutation is involved in the pathogenesis of hearing impairment. However, incomplete penetrance of hearing loss indicates that the A827G mutation alone is not sufficient to produce clinical phenotype but requires the involvement of modifier factors for the phenotypic expression, even though aminoglycosides and GJB2 gene may not contribute to the penetrance of the A827G mutation in this Chinese family. In contrast with the variable phenotype of hearing loss associated with other mitochondrial mutations, all of the patients in our family exhibited strikingly similar clinical features. This discrepancy likely reflects the difference of genetic backgrounds between this pedigree and others.

Asian People↗

PubMed2005

[Effect of nasal endoscopy-assisted adenoidectomy on the development of pediatric chronic sinusitis and otitis media with effusion].

OBJECTIVE: To discuss the effect of nasal endoscopy-assisted adenoidectomy with debrided on the development of pediatric chronic sinusitis and otitis media with effusion. METHOD: Fifteen cases of hypertrophied adenoid with pediatric chronic sinusitis and/or otitis media with effusion were treated with nasal endoscopy-assisted adenoidectomy and medicines followed. RESULT: No remainder of adenoid was left, no complication occurred and snoring disappeared in all patients. Pediatric chronic sinusitis and/or otitis media with effusion recovered with medicines after adenoidectomy. CONCLUSION: Nasal endoscopy-assisted adenoidectomy with debrided was an minimally invasive and effective treatment for hypertrophied adenoid, as well as contributed to the development of pediatric chronic sinusitis and otitis media with effusion.

Adenoidectomy↗

PubMed2004

Cosegregation of C-insertion at position 961 with the A1555G mutation of the mitochondrial 12S rRNA gene in a large Chinese family with maternally inherited hearing loss.

Mutations in the mitochondrial DNA have been shown to be one of the most important causes of sensorineural hearing loss. Here, we report the characterization of a large Chinese family (507 members in six generations) with maternally inherited non-syndromic hearing loss. Members of this family showed variable severity and age-of-onset of hearing impairment. In particular, the average age at onset of hearing loss in this family changed from 49 years (generation III) to 3 years (generation VI). Sequence analysis of the complete mitochondrial genome in this pedigree revealed the presence of a homoplasmic A1555G mutation in the 12S rRNA gene and other nucleotide changes. Of these changes, a C insertion at position 961 in the 12S rRNA gene is of special interest as mutations at this position have been found to be associated with aminoglycoside induced deafness in several genetically unrelated families. These data imply that the C insertion at position 961 in the 12S rRNA gene, acting as a secondary factor, could play a role in the phenotypic expression of the deafness associated A1555G mutation.

Age of Onset↗

PubMed2003

[Simultaneous posterior and horizontal canal benign paroxysmal positional vertigo].

OBJECTIVE: To explore effective methods for the diagnosis and treatment of simultaneous posterior and horizontal canal benign paroxysmal positional vertigo (combined BPPV, C-BPPV). METHOD: Epley's maneuver and Barbecue rotation were applied to four cases of C-BPPV separately with an interval of one day. RESULTS: Positional vertigo in all subjects disappeared completely after treatment and yielded excellent resolution of symptoms during period of follow-up. CONCLUSION: Clinical features in C-BPPV are combinations of both posterior and horizontal canal BPPV. Combined particle repositioning procedures of Epley's maneuver and Barbecue rotation is a successful method for treating the disorder.

Adult↗

PubMed2002

[Therapeutic trial with corticosteroid for auditory neuropathy].

OBJECTIVE: To explore the feasibility of corticosteroid for the treatment of auditory neuropathy. METHODS: Six patients with auditory neuropathy, diagnosed in the first affiliated hospital of Nanjing medical university between July 1998 and December 2001, were treated with corticosteroid therapy for one month (30-40 mg of prednisone daily for the first fifteen days, and 20 mg daily for following fifteen days). Prednisone was tapered gradually if a positive response to therapy was obtained. Hearing improvement was defined as 15 dB or more threshold drops in at least two of the standard audiometric frequencies in the same ear during the trial period. RESULTS: After one month's steroid treatment, significant hearing improvement was evident in two patients with raised speech discrimination scores from 48% to 95% and from 72% to 100%, respectively. In these two cases, prednisone was used continually up to 14 and 16 weeks, respectively, and the patients still had excellent pure tone hearing abilities and speech discriminations during follow-up of three years and four months, respectively. In other four patients, positive response for corticosteroid was not found within the period of one-month trail. CONCLUSION: Immunological damages of hearing system might play part role in the pathophysiological mechanisms of auditory neuropathy, and corticosteroids are potentially useful drugs for these cases.

Adolescent↗