Biomedical subjects

W Gstoettner

Publications and source records attributed to W Gstoettner.

43 records · Page 3Linked to original sources

PubMed1991

Saccular afferents to second-order cochlear neurons. An horseradish peroxidase and immunocytochemical study.

Previous studies have described a primary afferent vestibular projection to second-order cochlear neurons originating from the saccular maculae. As could be shown in the guinea pig by means of anterograde transport of horseradish peroxidase and immuno-cytochemistry, these saccular afferents terminated at cells immunoreactive to glutamate and aspartate but not to gamma-aminobutyric acid (GABA). These were intermingled among the fibers of the acoustic striae and situated between the dorsal cochlear nucleus and the octopus cell area. Within the acoustic striae, these saccular afferents appear to have a close relationship to GABA-immunoreactive structures, such as boutons en passant and terminal boutons. This striking relationship, along with cytoarchitectural criteria and the saccular input to these second-order cochlear neurons, gave reason to discern them as a separate cell group.

Afferent Pathways↗

PubMed1989

Saccular afferent fibers to the cochlear nucleus in the guinea pig.

After tracing the vestibular nerve of the guinea pig with horseradish peroxidase (HRP), a conspicuous fiber bundle was found that passed to the ipsilateral cochlear nucleus. HRP-labeled fibers were seen to leave the descending vestibular nucleus at a level caudal to subgroup "y" in a lateral direction. Travelling close to the restiform body, the axons terminated at cells lying between the dorsal and posteroventral cochlear nucleus. These cells could be distinguished cytoarchitecturally from surrounding cells of the cochlear nuclei. Several electrophysiological investigations have assumed that there is a direct connection between the vestibular and the cochlear system. Compared to these, the fibers under consideration might be the morphological basis for such a "vestibulo-cochlear anastomosis."

Animals↗

PubMed1988

Projection of primary vestibular afferent fibres to the cochlear nucleus in the guinea pig.

After tracing the superior branch of the vestibular nerve and the macula sacculi by means of the neuronal tracers horseradish peroxidase (HRP) and wheat germ conjugated horseradish peroxidase (WGA-HRP), a conspicuous fibre bundle running into the cochlear nucleus could be observed. The HRP-labeled axons travel caudally through the descending vestibular nucleus, enter the cochlear nucleus at a level caudal to subgroup y and terminate at cells situated between the dorsal and posteroventral cochlear nucleus. Considering recent electrophysiological studies, it is reasonable to imply that these fibres are involved with the transduction of acoustic stimuli.

Afferent Pathways↗

PubMed1987

Vestibular nuclear complex in the guinea pig: a cytoarchitectonic study and map in three planes.

Cytoarchitectonic and fiberarchitectonic criteria were used in the preparation of a detailed map illustrating the vestibular nuclear complex of the guinea pig. The brainstems used for this study were serially cut at 16 micron in the transverse, the sagittal, or the horizontal plane. The sections were studied after being stained alternately with a combined cell and fiber staining method and a Nissl stain. The basic cytoarchitectonic features of the four main vestibular nuclei, their extent, as well as their relationship to the surrounding structures are described. Additionally, the location, topographical features, and the cytoarchitecture of the small groups (f,g,l,x,y,z) associated with the vestibular nuclei are reported. Group f is especially well developed and easily distinguishable in the guinea pig. Furthermore, a hitherto undescribed cell cluster found dorsal to the dorsal border of the superior vestibular nucleus is presented. The results and especially the differences from the descriptions of other species are discussed.

Animals↗

PubMedDate not supplied

Short-term effect of auditory feedback on fundamental frequency after cochlear implantation.

The present study evaluates the short-term effect of cochlear implantation on the fundamental frequency (FO) of 13 deaf patients. All patients were provided with the Combi 40+ cochlear implant. Voice recording was made pre- and 3 months post-implantation. The FO was analysed using X-Tools software. The results showed that 38 per cent of our subjects had a statistically significant decrease of their mean F0 (p=0.001) at 3 months following implantation. It was also observed that the patients tended to have a lower F0 postoperatively approaching the normal range of F0. A large variability in F0 was noticed among the deaf subjects but no correlation with the duration of deafness was seen. There was also no correlation between speech recognition and speech production.

Adult↗

PubMedDate not supplied

Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices.

Cochlear implantation has been performed for almost two decades at the Vienna University Hospital. Until 1994, single-channel implants were used (Ball-Electrode, SC6/2SC6, Vienna/Epoxy, Med-E1, Innsbruck, Austria). The development of multi-channel devices (Combi 40/40+), which provide significantly improved speech recognition performance, led to the reimplantation of some patients who had previously received single-channel implants. It was of particular interest to find out if there was a deterioration of the central "learning process" by the reimplantation from the analogue single-channel device to the tonotopic pulsatile multi-channel stimulation. In this study, we attempted to demonstrate that single-channel implants have an impact on the neural organisation of the auditory system. Two groups of post-lingually deaf adult patients were tested. Group A had previously received single-channel implants and were reimplanted with the new Combi 40/40+ cochlear implant (Med-E1, Innsbruck, Austria) in the same ear. Group B was implanted only with the Combi 40/40+. Six different speech recognition tests were subsequently performed on all patients, and the two groups performed similarly. Furthermore, it was discovered that group A obtained significant speech recognition improvement (p<0.05) with monosyllabic words and number tests 1 month following reimplantation.

Acoustic Stimulation↗

PubMedDate not supplied

Carcinomas unresponsive to either cisplatinum or anti-EGFR therapy can be growth inhibited by combination therapy of both agents.

BACKGROUND: Previously we demonstrated that the antitumor efficacy of monoclonal antibodies against the EGFR (epidermal growth factor receptor) of human tumor xenografts mainly depends on the EGFR content of tumors rather than on the tumors' entity. In this study we wanted to elucidate whether the described cumulative effect of cisplatin and Anti-EGFR therapy also depends on the EGFR expression. MATERIALS AND METHODS: Xenotransplanted carcinomas with different EGFR levels were treated with monoclonal antibodies against the EGFR (EMD 72000 and EMD 55900), cisplatinum and a combination of both. RESULTS: Each monoclonal antibody alone led to an EGFR-dependent significant tumor growth reduction. Cisplatinum alone had no growth inhibitory effects on tumors with high content in contrast to those with low EGFR content. The combination of antibodies with cisplatinum resulted in an EGFR-independent tumor growth inhibition which was stronger than observed in the case of monotherapy. DISCUSSION: The obtained results may address upcoming phase I/II trials to use Anti-EGFR/Cisplatinum therapy regardless of the EGFR content of tumors.

Adenocarcinoma↗