Book review.

Book review.

Int J Audiol. 2015 Dec;54(12):997

Authors: Honaker J

PMID: 26848999 [PubMed - as supplied by publisher]

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Book review.

Book review.

Int J Audiol. 2015 Dec;54(12):997

Authors: Honaker J

PMID: 26848999 [PubMed - as supplied by publisher]

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Sagittal plane momentum control during walking in elderly fallers

Publication date: March 2016
Source:Gait & Posture, Volume 45
Author(s): Masahiro Fujimoto, Li-Shan Chou
ObjectiveThe purpose of this study was to examine sagittal plane momentum control during walking with the use of center of mass (COM) velocity and acceleration.MethodsCOM control in the antero-posterior direction during walking of healthy young and elderly adults, and elderly fallers (n=15/group) was examined. Using a single-link-plus-foot inverted pendulum model, boundaries for the region of stability were determined based on the COM position at toe-off and its instantaneous velocity or the peak acceleration prior to toe-off (ROSv or ROSa, respectively).ResultsAlthough no significant difference in forward COM velocity was detected between healthy young and elderly subjects, the peak forward COM acceleration differed significantly, suggesting age-related differences in momentum control during walking. Elderly fallers demonstrated significantly slower forward COM velocities and accelerations and placed their COM significantly more anterior than healthy young and elderly subjects at toe-off, which resulted in their COM position-velocity combination located within the ROSv. Similar results were obtained in the ROSa, where elderly fallers demonstrated a larger stability margin than healthy young and elderly subjects.InterpretationsSignificantly slower peak COM accelerations could be indicative of a poor momentum control ability, which was more pronounced in elderly fallers. Examining COM acceleration, in addition to its velocity, would provide a greater understanding of person's momentum control, which would allow us to better reveal underlying mechanisms of gait imbalance or falls.



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Confirmation of PDZD7 as a Nonsyndromic Hearing Loss Gene.

Objective: PDZD7 was identified in 2009 in a family with apparent nonsyndromic sensorineural hearing loss. However, subsequent clinical reports have associated PDZD7 with digenic Usher syndrome, the most common cause of deaf-blindness, or as a modifier of retinal disease. No further reports have validated this gene for nonsyndromic hearing loss, intuitively calling correct genotype-phenotype association into question. This report describes a validating second case for biallelic mutations in PDZD7 causing nonsyndromic mild to severe sensorineural hearing loss. It also provides detailed audiometric and ophthalmologic data excluding Usher syndrome in both the present proband (proband 1) and the first proband described in 2009 (proband 2). Design: Proband 1 was sequenced using a custom-designed next generation sequencing panel consisting of 151 deafness genes. Bioinformatics analysis and filtering disclosed two PDZD7 sequence variants (c.1648C>T, p.Q550* and c.2107del, p.S703Vfs*20). Segregation testing followed in the family. For both probands, audiograms were collected and analyzed for progressive hearing loss and detailed ophthalmic evaluations were performed including electroretinography. Results: Proband 1 demonstrated a prelingual, nonsyndromic, sensorineural hearing loss that progressed in the higher frequencies between 4 and 9 years old. PDZD7 segregation analysis confirmed biallelic inheritance (compound heterozygosity). Mutation analysis determined the c.1648C>T mutation as novel and reported the c.2107del deletion as rs397516633 with a calculated minor allele frequency of 0.000018. Clinical evaluation spanning well over a decade in proband 2 disclosed bilateral, nonprogressive hearing loss. Both probands showed healthy retinas, excluding Usher syndrome-like changes in the eye. Conclusions: PDZD7 is confirmed as a bona fide autosomal recessive nonsyndromic hearing loss gene. In both probands, there was no evidence of impaired vision or ophthalmic pathology. As the current understanding of PDZD7 mutations bridge Mendelian and complex phenotypes, the authors recommend careful variant interpretation, since PDZD7 is one of many genes associated with both Usher syndrome and autosomal recessive nonsyndromic hearing loss. Additional reports are required for understanding the complete phenotypic spectrum of this gene, including the possibility of high-frequency progression, as well as noise-induced hearing loss susceptibility in adult carriers. This report rules out all forms of Usher syndrome with an onset before 12 and 15 years old in probands 1 and 2, respectively. However, due to the young ages of the probands, this report is uninformative regarding older patients. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

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