Using a reference population yardstick to calibrate and compare genetic diversity reported in different studies: an example from the brown bear.

In species with large geographic ranges, genetic diversity of different populations may be well studied, but differences in loci and sample sizes can make the results of different studies difficult to compare. Yet, such comparisons are important for assessing the status of populations of conservation concern. We propose a simple approach of using a single well-studied reference population as a 'yardstick' to calibrate results of different studies to the same scale, enabling comparisons. We use a well-studied large carnivore, the brown bear (Ursus arctos), as a case study to demonstrate the approach. As a reference population, we genotyped 513 brown bears from Slovenia using 20 polymorphic microsatellite loci. We used this data set to calibrate and compare heterozygosity and allelic richness for 30 brown bear populations from 10 different studies across the global distribution of the species. The simplicity of the reference population approach makes it useful for other species, enabling comparisons of genetic diversity estimates between previously incompatible studies and improving our understanding of how genetic diversity is distributed throughout a species range.

Vestibular implants: the first steps in humans.

Currently there is no efficient treatment for patients with severe bilateral vestibular function impairment. Presence of oscillopsia is their main complaint. It has a significant negative impact on their quality of life. Recently it has been shown that angular vestibulo-ocular reflex can be partially restored in animals. In humans it is possible to elicit a nystagmic response by electric stimulation of ampullary parts of the vestibular nerve. Controlled eye movements can be generated by frequency and intensity modulation of the restored baseline firing rate of the vestibular nerve. During adaptation phase to the electric stimulus, patients experience nystagmus with associated inconveniences. By repetition of "on/off periods" the duration of the adaptation phase can be significantly decreased. Results show that permanent electric stimulation is necessary to maintain this "optimal" adaptation state.

[Development of a vestibular implant for the rehabilitation of bilateral deafness]. / Développement d'un implant vestibulaire pour la réhabilitation des déficits vestibulaires bilatéraux.

The development of a vestibular implant for the rehabilitation of bilateral vestibular loss is funded on a concept comparable to that of the cochlear implant used in the rehabilitation of bilateral deafness. This paper carries an overview of the main aspects of such a development and describes the first experiments done in human subjects in Geneva.

Histopathology of cochlear implants in humans.

The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users.

Isolated vestibular areflexia after blunt head trauma.

The sudden unilateral loss of vestibular function is a frequent cause of vertigo. This condition is called vestibular neuronitis or vestibular neuritis. Its cause remains unknown, but many authors consider it to be a sequel of vestibular viral infection. We report the history and clinical findings of 5 patients in whom a unilateral vestibular loss occurred after head trauma. None of these patients complained of hearing loss. In all cases, the vertigo gradually subsided over days or weeks. The follow-up showed the partial recovery of vestibular function in 2 cases, while vestibular areflexia persisted in 3. The clinical course and findings were similar in every respect to those in patients with classic idiopathic vestibular neuronitis.

[Adenoma of the middle ear]. / Adénome de l'oreille moyenne.

We report a case of middle ear adenoma, a rare epithelial tumour composed of adenomatous and neuroendocrine cells. These tumours have been designated by many different names, leading to controversy regarding their histogenesis and classification. The diagnosis was based on light microscopy and immunohistochemistry. A positive immunoreaction was evidenced for antibodies to keratin and chromogranin. The tumour was removed surgically. No additional therapy is recommended in the literature.

[Long-term results of canal wall down mastoidectomy]. / Résultats à long terme de l'évidement pétro-mastoïdien en technique ouverte.

INTRODUCTION: This study evaluates the anatomical and functional long-term results of canal wall down mastoidectomy. METHOD: We analyse the results of 259 primary, one stage canal wall down mastoidectomies with type III, IV or V ossiculoplasty performed between 1974 and 1998. The indication for surgery was chronic active otitis with cholesteatoma or resistant to conservative treatment. RESULTS: In the long term, 1-24 (mean 7) years after surgery, 95% of the ears showed a dry, self-cleaning cavity and were disease-free. Hearing was preserved or improved in 70% of cases. Surgical revision due to of residual cholesteatoma was necessary in 16 cases (6%). The number of postoperative outpatient visits necessary to treat multiple minor problems was up to 10 visits per patient during the first 6 months after surgery and then gradually decreased over the years. DISCUSSION: The results achieved with canal wall down mastoidectomy are satisfactory in the long term, but the cavities required a high degree of postoperative outpatient care.