Audiology by Alexandros G. Sfakianakis

Τρίτη 15 Νοεμβρίου 2016

Molecular Impairment Mechanisms of Novel OPA1 Mutations Predicted by Molecular Modeling in Patients With Autosomal Dominant Optic Atrophy and Auditory Neuropathy Spectrum Disorder.

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Molecular Impairment Mechanisms of Novel OPA1 Mutations Predicted by Molecular Modeling in Patients With Autosomal Dominant Optic Atrophy and Auditory Neuropathy Spectrum Disorder.

Otol Neurotol. 2016 Apr;37(4):394-402

Authors: Namba K, Mutai H, Takiguchi Y, Yagi H, Okuyama T, Oba S, Yamagishi R, Kaneko H, Shintani T, Kaga K, Matsunaga T

Abstract
HYPOTHESIS: Different missense mutations of the optic atrophy 1 gene (OPA1) identified in optic atrophy patients with auditory neuropathy spectrum disorder (ANSD) induce functional impairment through different molecular mechanisms.
BACKGROUND: OPA1 is the gene responsible for autosomal dominant optic atrophy (ADOA), but some of its mutations are also associated with ANSD. OPA1 is a member of the GTPase family of proteins and plays a key role in the maintenance of mitochondrial activities that are dependent on dimer formation of the protein. There are many reports of OPA1 mutations, but the molecular mechanisms of their functional impairments are unclear.
METHODS: The sequences of coding regions in OPA1 were analyzed from blood samples of ADOA patients with ANSD. Molecular modeling of the protein's ability to form dimers and its GTP-binding ability were conducted to study the effects of structural changes in OPA1 caused by two identified mutations and their resultant effects on protein function.
RESULTS: Two heterozygous mutations, p.T414P (c.1240A>C) and p.T540P (c.1618A>C), located in the GTPase and middle domains of OPA1, respectively, were identified in two patients. Molecular modeling indicated decreased dimer formation caused by destabilization of the association structure of the p.T414P mutant, and decreased GTP-binding caused by destabilization of the binding site structure in the p.T540P mutant.
CONCLUSION: These two different conformational changes might result in decreased GTPase activities that trigger ADOA associated with ANSD, and are likely to be associated with mild clinical features. Molecular modeling would provide useful information in clinical practice.

PMID: 26905822 [PubMed - indexed for MEDLINE]

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Clinical characteristics and treatment outcomes for benign paroxysmal positional vertigo comorbid with hypertension.

Clinical characteristics and treatment outcomes for benign paroxysmal positional vertigo comorbid with hypertension.

Acta Otolaryngol. 2016 Nov 14;:1-3

Authors: Tan J, Deng Y, Zhang T, Wang M

Abstract
CONCLUSIONS: Patients with BPPV comorbid with hypertension (h-BPPV) tend to receive a delayed diagnosis of BPPV. Comorbidity with hypertension did not influence the efficacy of the repositioning maneuver; however, comorbidity with hypertension was associated with an increased recurrence rate of BPPV.
OBJECTIVES: To determine the clinical characteristics and outcomes of h-BPPV, as well as the clinical differences between h-BPPV and idiopathic BPPV (i-BPPV).
METHODS: The authors reviewed the medical records of 41 consecutive patients with h-BPPV (the h-BPPV group) from March to December 2014 and 47 patients with i-BPPV (the i-BPPV group) during the same period.
RESULTS: There were no significant differences in age, sex ratio, or the affected side between the h-BPPV and i-BPPV groups. The proportion of patients reporting an initial episode of positional vertigo was significantly lower in the h-BPPV group (51.22% vs 74.47%; p = .024). Patients in the h-BPPV group reported a longer median episode duration than did those in the i-BPPV group (60 days vs 15 days; p = .017). The results of treatment using repositioning maneuvers were similar between the two groups. At follow-up, 13 patients in the h-BPPV group were diagnosed with recurrent BPPV compared with six in the i-BPPV group (p = .031).

PMID: 27841099 [PubMed - as supplied by publisher]

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Hearing loss in children with otitis media with effusion: a systematic review.

Hearing loss in children with otitis media with effusion: a systematic review.

Int J Audiol. 2016 Nov 14;:1-12

Authors: Cai T, McPherson B

Abstract
OBJECTIVES: Otitis media with effusion (OME) is the presence of non-purulent inflammation in the middle ear. Hearing impairment is frequently associated with OME. Pure tone audiometry and speech audiometry are two of the most primarily utilised auditory assessments and provide valuable behavioural and functional estimation on hearing loss. This paper was designed to review and analyse the effects of the presence of OME on children's listening abilities.
DESIGN: A systematic and descriptive review.
STUDY SAMPLE: Twelve articles reporting frequency-specific pure tone thresholds and/or speech perception measures in children with OME were identified using PubMed, Ovid, Web of Science, ProQuest and Google Scholar search platforms.
RESULTS: The hearing loss related to OME averages 18-35 dB HL. The air conduction configuration is roughly flat with a slight elevation at 2000 Hz and a nadir at 8000 Hz. Both speech-in-quiet and speech-in-noise perception have been found to be impaired.
CONCLUSIONS: OME imposes a series of disadvantages on hearing sensitivity and speech perception in children. Further studies investigating the full range of frequency-specific pure tone thresholds, and that adopt standardised speech test materials are advocated to evaluate hearing related disabilities with greater comprehensiveness, comparability and enhanced consideration of their real life implications.

PMID: 27841699 [PubMed - as supplied by publisher]

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