Aerial low-frequency hearing in captive and free-ranging harbour seals (Phoca vitulina) measured using auditory brainstem responses

The contribution of air conduction auditory brainstem response (AC-ABR) testing in the paediatric population is widely accepted in clinical audiology. However, this does not allow for differentiation between conductive and sensorineural hearing loss. The purpose ofthis paper is to review the role of bone conduction auditory brainstem responses (BC-ABR). It is argued that despite such technical difficulties as a narrow dynamic range, masking dilemmas, stimulus artifact and low frequency underestimation of hearing loss, considerable evidence exists to suggest that BC-ABR testing provides an important contribution in the accurate assessmentof hearing loss in infants. Modification of the BC-ABR protocol is discussed and the technical difficulties that may arise are addressed, permitting BC-ABR to be used as a tool in the differential diagnosis between conductive and sensorineural hearing. Two relevant case studies are presented to highlight the growing importance of appropriate management in early identification of hearing loss. It can be concluded that BC-ABR should be adopted as a routine clinical diagnostic tool.

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Contaminant-associated disruption of vitamin A and its receptor (retinoic acid receptor α) in free-ranging harbour seals (Phoca vitulina)

Aquatic Toxicology ◽

10.1016/j.aquatox.2006.12.017 ◽

2007 ◽

Vol 81 (3) ◽

pp. 319-328 ◽

Cited By ~ 52

Author(s):

L MOS ◽

M TABUCHI ◽

N DANGERFIELD ◽

S JEFFRIES ◽

B KOOP ◽

...

Keyword(s):

Retinoic Acid ◽

Vitamin A ◽

Retinoic Acid Receptor ◽

Phoca Vitulina ◽

Acid Receptor ◽

Harbour Seals ◽

Retinoic Acid Receptor Α ◽

Free Ranging

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Low-Level 0.5 and 1 Khz Auditory Brainstem Responses a Search for the Low-frequency point in the Two-point ABR Audiogram

Scandinavian Audiology ◽

10.3109/01050398909070743 ◽

1989 ◽

Vol 18 (3) ◽

pp. 177-183 ◽

Cited By ~ 10

Author(s):

Oddbjørn Fjermedal ◽

Einar Laukli

Keyword(s):

Low Frequency ◽

Auditory Brainstem ◽

Auditory Brainstem Responses ◽

Low Level

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Effects of High-Pass Filtering on the Waveform and Threshold of Auditory Brainstem Responses to Tone Pips Answer to the comments of Dr. Kileny on the paper: 'Auditory Brainstem Responses to Middle- and Low-Frequency Tone Pips'

International Journal of Audiology ◽

10.3109/00206098609078378 ◽

1986 ◽

Vol 25 (2) ◽

pp. 124-128

Author(s):

M. Maurizi ◽

G. Paludetti ◽

F. Ottaviani ◽

M. Rosignoli

Keyword(s):

Low Frequency ◽

Auditory Brainstem ◽

Auditory Brainstem Responses ◽

Frequency Tone ◽

High Pass

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Thyroid hormone dynamics during the nursing period in harbour seals, Phoca vitulina

Canadian Journal of Zoology ◽

10.1139/z97-156 ◽

1998 ◽

Vol 76 (1) ◽

pp. 48-55 ◽

Cited By ~ 4

Author(s):

Martin Haulena ◽

David J Aubin ◽

Padraig J Duignan

Keyword(s):

Thyroid Hormones ◽

Post Partum ◽

Phoca Vitulina ◽

Postnatal Period ◽

Lactation Period ◽

Harbour Seals ◽

Total Thyroxine ◽

Phocid Seals ◽

Free Ranging ◽

Circulating Levels

The postnatal period in phocid seals is metabolically demanding, requiring mobilization of maternal energy stores, which are then transferred via the milk for subsequent deposition in the pup. Thyroid hormones may be important modulators of these processes, and so we monitored circulating levels of free and total thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3) in 13 free-ranging female harbour seals (Phoca vitulina) and their pups for up to 25 days post partum. Early total and free T4 levels, percentage of free T4, total and free T3 levels, rT3 levels, and rT3:T3 ratios were significantly higher in pups than in mothers. Total and free T4 levels, percentage of free T4, free T3 and rT3, levels, and rT3:T3 ratios in pups decreased significantly over the lactation period, while maternal total and free T4 levels increased significantly. Our findings highlight the dynamic nature of thyroid hormones and their involvement in regulating metabolism throughout this important period. This is the first report examining free T3 and rT3 levels in phocid seals.

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