Biomedical subjects

Agneta Viberg

Publications and source records attributed to Agneta Viberg.

3 recordsLinked to original sources

PubMed2004

The guide to plotting a cochleogram.

The cochleogram is commonly used for illustrating hair cell loss after insult, yet standardized procedures for plotting either individual or averaged cochleograms are lacking despite more than 40 years of use. Due to the intra-species variation in basilar membrane (BM) length, it is important that length is plotted on the cochleogram in percent and not millimeter. It is also of interest to correlate the location of lesion to frequency by using a frequency-place equation. However, there is no consensus as which equation is most suitable for the species under study. This is an important issue since two different equations can result in significantly different frequency-place maps for the same cochlea. The purpose of this presentation is to suggest procedures for standardizing the cochleogram. The guidelines include: (i) basilar membrane length should be plotted as percent instead of millimeter due to the biological variation that exists in BM length within a particular species and strain, and the total length in millimeter stated on the cochleogram; (ii) the equations used for frequency-place maps should be stated on the cochleogram; (iii) different basilar membrane lengths should be normalized to percent before averaged cochleograms are made. These procedures are illustrated and discussed.

Animals↗

PubMed2003

Auditory peripheral influences on calcium binding protein immunoreactivity in the cochlear nucleus during aging in the C57BL/6J mouse.

The C57BL/6J (C57) mouse was selected as a suitable model for early presbyacusis to determine if there were correlations between peripheral pathology (spiral ganglion loss, inner and outer hair cell loss) and calcium binding immunoreactivity in the cochlear nucleus during aging. The quantitative stereological method, the optical fractionator, was used for determining the total number of neurons and calcium binding immunopositive neurons (calbindin, parvalbumin and calretinin) during aging in the posteroventral- and dorsal cochlear nucleus (PVCN and DCN) in C57 mice. Comparing 30-month-old to 1-month-old C57 mice, a percent increase in parvalbumin and calbindin immunoreactivity was evident in both the PVCN and DCN. Correlations were made between peripheral pathology (spiral ganglion and inner and outer hair cell loss) and calcium binding protein expression. Significant correlations between cochlear pathology and the percentage of parvalbumin and calretinin immunoreactive neurons were demonstrated in the DCN. Moreover, significant correlations were found between cochlear pathology and parvalbumin and calbindin in the PVCN. In summary, the findings imply that degenerative changes in the auditory periphery can modulate neuronal homeostasis by increasing calcium binding proteins in the PVCN and DCN during aging. Taken together, these findings suggest a role for calcium binding proteins in protecting against age-induced calcium toxicity.

Aging↗

PubMed2002

Extra inner hair cells in the developing rabbit cochlea.

Development of the rabbit inner ear was analysed with respect to the presence of extra inner hair cells (XIHCs) in phalloidin-impregnated cochleas of newborn rabbits 0, 3 and 5 days of age. The number of XIHCs ranged from four to 77. The distribution was asymmetrical with a peak in the apical 3 mm of the cochlea. There was no general disorganisation in the vicinity of the XIHCs, and the numbers were highly symmetrical between the two ears. The number was significantly larger (P<0.001) in newborns than in adults. There was no correlation between number of XIHCs and cochlear length, making it unlikely that the presence of XIHCs is due to lack of space in the ordinary row of IHCs. The possible relation of the XIHCs to growth factors, molecular genetics and regeneration is discussed.

Age Factors↗