Hearing Aid Use in Older Adults With Postlingual Sensorineural Hearing Loss: Protocol for a Prospective Cohort Study.

BACKGROUND: Older adults with postlingual sensorineural hearing loss (SNHL) exhibit a poor prognosis that not only includes impaired auditory function but also rapid cognitive decline, especially speech-related cognition, in addition to psychosocial dysfunction and an increased risk of dementia. Consistent with this prognosis, individuals with SNHL exhibit global atrophic brain alteration as well as altered neural function and regional brain organization within the cortical substrates that underlie auditory and speech processing. Recent evidence suggests that the use of hearing aids might ameliorate this prognosis. OBJECTIVE: The objective was to study the effects of a hearing aid use intervention on neurocognitive and psychosocial functioning in individuals with SNHL aged ≥55 years. METHODS: All aspects of this study will be conducted at Swinburne University of Technology (Hawthorn, Victoria, Australia). We will recruit 2 groups (n=30 per group) of individuals with mild to moderate SNHL from both the community and audiology health clinics (Alison Hennessy Audiology, Chelsea Hearing Pty Ltd). These groups will include individuals who have worn a hearing aid for, at least, 12 months or never worn a hearing aid. All participants would be asked to complete, at 2 time points (t) including baseline (t=0) and follow-up (t=6 months), tests of hearing and psychosocial and cognitive function and attend a magnetic resonance imaging (MRI) session. The MRI session will include both structural and functional MRI (sMRI and fMRI) scans, the latter involving the performance of a novel speech processing task. RESULTS: This research is funded by the Barbara Dicker Brain Sciences Foundation Grants, the Australian Research Council, Alison Hennessy Audiology, and Chelsea Hearing Pty Ltd under the Industry Transformation Training Centre Scheme (ARC Project #IC140100023). We obtained the ethics approval on November 18, 2017 (Swinburne University Human Research Ethics Committee protocol number SHR Project 2017/266). The recruitment began in December 2017 and will be completed by December 2020. CONCLUSIONS: This is the first study to assess the effect hearing aid use has on neural, cognitive, and psychosocial factors in individuals with SNHL who have never used hearing aids. Furthermore, this study is expected to clarify the relationships among altered brain structure and function, psychosocial factors, and cognition in response to the hearing aid use. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12617001616369; https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12617001616369 (Accessed by WebCite at http://www.webcitation.org/70yatZ9ze). INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/9916.

The photoadaptive response to ultraviolet exposure in human skin using ultraviolet spectrophotometry.

BACKGROUND: Both pigmentation and non-pigmentary processes contribute to the development of photoadaptation yet the exact contribution of either in the resting state and in response to ultraviolet (UV) radiation is unclear. The purpose of this study was to estimate independently these changes occurring in the epidermis following repeated exposure to UV in two groups with differing degrees of constitutive pigmentation. METHODS: We describe a mathematical model for explaining the spectral absorbance of excised human epidermis based on the absorbance of constituent chromophores. The model was applied to spectral absorbance data measured on samples of epidermis excised from pre-irradiated skin and from skin obtained following UV irradiation on 3 successive days. RESULTS: We found that in Asian skin there was only a mild photoadaptive response, principally by a small increase in pigmentation. On the other hand, the significant adaptive response in Caucasian skin was through hyperplasia of the epidermis, with tanning contributing only to a much smaller degree. CONCLUSION: This study has enabled us to study independently the pigmentary and non-pigmentary pathways and has shown that in those people with a lower degree of constitutive pigment, the primary mechanism of photoadaptation is via the non-pigmentary route.

Eumelanin and pheomelanin concentrations in human epidermis before and after UVB irradiation.

Pheomelanin is widely thought to be causally related to susceptibility to the harmful effects of ultraviolet radiation: epidemiological studies show that those with a higher ratio of pheomelanin to eumelanin in hair have higher rates of melanoma, and work in mouse and cell culture shows that pheomelanin generates excess free radicals after UVR exposure. By contrast, based on measurements of eumelanin and pheomelanin in human skin, before and following irradiation, we now report that both pheomelanin and eumelanin are positively related to skin colour, and by inference, inversely with cancer susceptibility. The ratio of melanin classes is similar in people with widely different cancer rates and UVR sensitivity. Although our numbers are small, our results extend previous work in man, and lead us to speculate that factors other than the amount of pheomelanin may be important in determining UVR susceptibility in persons with red hair.

The time course of photoadaptation and pigmentation studied using a novel method to distinguish pigmentation from erythema.

The dynamics of human pigmentation in response to ultraviolet radiation (UVR) remain poorly characterized. In part, this is attributable to methodological issues relating to the overlap in spectra of hemoglobin and melanin. We describe a new method, based on the recording of reflectance properties following iontophoresis of a potent vasoconstrictor, noradrenaline. This removes the influence of blood, allowing measurement of pigmentation, represented as L* on the L*a*b* scale. Blood flow was separately assessed using laser Doppler flowmetry. We show that there is a clear dose response with the dose of UVR administered, that pigmentation peaks at 1 wk and declines over the following 10 wk, but does not return to baseline within this period. We show clear differences in the degree, but not the temporal pattern of pigmentation between different pigmentary groups. We also report that the relation between facultative pigment and constitutive pigment is incomplete, with a wide scatter of responses for the development of pigmentation irrespective of constitutive levels. For comparison we also document overall photoadaptation and relate changes in pigmentation to the overall changes in photoadaptation.

New pressure flow cell to monitor BaSO4 precipitation using synchrotron in situ angle-dispersive X-ray diffraction.

A flow cell has been commissioned to monitor in situ precipitation reactions under non-ambient conditions. The majority of high-pressure systems use anvils and presses to obtain high pressures around a small reaction area; however, this prototype is unique in that solutions may be examined as they flow through the cell under pressure. The cell is made of single-crystal silicon, which is capable of withstanding the high pressures created by liquid flow within the cell. With the capability of reaching pressures of up to 4 x 10(7) Pa, the cell is ideal for work on geological and oilfield systems. Here it is used to examine the formation of barium sulfate scale in situ under non-ambient conditions using angle-dispersive XRD on beamline X17b1 at the NSLS.