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Biomedical subjects

T Stöver

Publications and source records attributed to T Stöver.

At least 19 recordsLinked to original sources
PubMed2006

[In vitro neurite outgrowth induced by BDNF and GDNF in combination with dexamethasone on cultured spiral ganglion cells].

BACKGROUND: The efficacy of cochlear implant performance depends, among many other factors, on the number of excitable spiral ganglion cells (SGCs) and the nerve-electrode interface. In earlier animal studies it has been demonstrated that neurotrophic factors are effective to improve SGC survival after experimentally induced deafness. With regard to their anti-inflammatoric and anti-proliferative effects, glucocorticoids (e. g. dexamethasone) are potentially interesting therapeutic agents to reduce connective tissue formation around the inserted electrode. The biological effects of a combined intervention of neurotrophic factors with steroids on SGCs are unknown. Therefore the objective of the study was to investigate possible trophic or even toxic effects of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) and dexamethasone on neurite outgrowth of cultivated SGCs. METHODS: By using dissociated postnatal spiral ganglion cells (p3-5) for cultivation in the present study, the influence of the mentioned factors in various concentrations and combinations on neurite outgrowth of SGCs was analysed. RESULTS: Our results indicate significant trophic effects for BDNF (50 ng/ml) and a combination of BDNF with dexamethasone (100 ng/ml) on SGC neurite outgrowth. In contrast, single application of GDNF or dexamethasone in different concentrations caused no significant changes on neurite outgrowth when compared to the control condition. CONCLUSIONS: Neurite outgrowth induced by neurotrophic factors could not be observed to be reduced when dexamethasone is given at the same time. Therefore the demonstrated results provide a basis for further animal studies in this field of research.

Animals↗
PubMed2006

[Parapharyngeal abscess and osteomyelitic destruction of the odontoid process].

We report the case of a 55 year old man with osteomyelitic destruction of the odontoid process and a parapharyngeal abscess. The patient was admitted with diagnosis of meningitis and degenerative cervical spine disease without compression of spinal cord or nerve roots but progressive impairment of cervical spine mobility. Inflammatory parameters in serum and cerebrospinal fluid were detected and antibiotic therapy was initiated resulting in subjective improvement of symptoms. When impairment of cervical spine motility persisted and gait disturbance developed, a parapharyngeal abscess and an osteomyelitic destruction of the odontoid process caused by infection with staphylococcus aureus was diagnosed. After cleavage of the abscess and four months of antibiotic therapy the gait disturbance disappeared and mild impairment of cervical spine motility persisted.

Anti-Bacterial Agents↗
PubMed2006

[Neurotrophic factor expression in vestibular schwannoma. An overview].

The vestibular schwannoma is a benign, slow-growing neoplasm that originates from the neurolemmal sheath of the vestibular branch of the VIIIth cranial nerve. This tumor entity accounts for 6 % of all intracranial tumors and the annual incidence of newly diagnosed vestibular schwannoma is reported as 13 per million. The molecular pathogenesis of both sporadic vestibular schwannoma and those occurring in neurofibromatosis type II appears to be associated with an aberration of a tumor suppressor gene on chromosome 22q12. The biological background for the various growth patterns of vestibular schwannoma is, however, largely unknown. This differing clinical and biological behaviour of vestibular schwannoma may be explained by the presence of neurotrophic factors. The results of recent immunohistochemical studies demonstrate the co-expression of transforming growth factor (TGF)-beta 1 and glial cell line-derived neurotrophic factor (GDNF) in vestibular schwannoma and suggest a trophic synergism of both neurotrophic factors in this tumor. Moreover, expression of numerous different neurotrophic factors has been shown in studies of nerve growth factor (NGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), neuregulin (NRG) and erythropoietin (EPO) indicating a biological role in development, maintainance or growth of vestibular schwannoma. In this article, we summarize the findings on neurotrophic factor expression and discuss their characteristics and biological role in vestibular schwannoma.

Adult↗
PubMed2006

[Neurotrophic factors of the GDNF family and their receptors are detectable in spiral ganglion cells of normal hearing as well as of deafened rats].

BACKGROUND: Recent studies have shown that neurotrophic factors like BDNF, NT-3 and GDNF induce protective effects on spiral ganglion cells after noise- or drug-induced hearing loss. According to these studies it is suggested that deafness leads to a lack of neurotrophic factor or relating receptor expression in spiral ganglion cells, that has to be compensated by local cochlear application of these factors. METHODS: In the present study we examined the expression pattern of members of the GDNF family (GDNF, Neurturin, Artemin, Persephin) and their relating receptors (Ret, GFRalpha1 - 3) as well as BDNF and trkB on spiral ganglion cells of normal hearing and experimentally deafened rats (10 % neomycine). Indirect immunofluorescence was carried out to determine protein expression of these factors and their receptors 26 days following deafening. RESULTS: Our results demonstrate neurotrophic factor and receptor expression on spiral ganglion cells of normal hearing as well as experimentally deafened animals. CONCLUSIONS: Our data indicate that within a period of 26 days after deafening no detectable reduction of the GDNF-family member expression and their receptors was ascertainable on spiral ganglion cells by immunohistochemistry. Thus, a lack of neurotrophic factor expression is unlikely to be the only cause of spiral ganglion cell loss following deafening.

Animals↗
PubMed2006

[Embryonal rhabdomyosarcoma of the orbita].

A 2(1/2) year old girl was presented with an acute, painless orbital swelling without signs of local or systemic inflammation. CT and MRT scanning revealed a tumor which by open biopsy disclosed embryonal rhabdomyosarcoma. By means of this case we present the current diagnostic and therapeutic approaches for childhood soft tissue sarcomas. At present our patient receives a poly-chemotherapy which has already shown a good response. For local tumor control, a complete surgical resection as well as radiotherapy may be indicated and have to be considered carefully with respect to the possible late effects. This case demonstrates that in a child with a unilateral, progressive orbital tumor, the differential diagnosis of a soft tissue sarcoma has to be ruled out.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

[Peripheral facial palsy as the first symptom of a metastatic bronchogenic carcinoma].

BACKGROUND: We present a case of a facial palsy as the initial symptom of a bronchogenic carcinoma. METHODS: Case-report. A 56-year-old patient presented with a peripheral facial palsy. The clinical picture as well as the temporal bone CT were without pathological findings. A 10-day rheologic therapy as well as anti-viral medication were not successful. Five days after rheological therapy had been completed, the patient presented a swelling of the neck. In the computer tomography we found a bilateral thrombosis of the internal jugular vein. In addition, the clinical picture of a left-sided glossopharyngeal palsy appeared. The following thorax CT as well as the diagnostic extirpation of an enlarged cervical lymph node lead to the diagnosis of a metastasized smallcell neuro-endocrine bronchogenic carcinoma with a compression of the right primary bronchus and the vena cava superior as well as an upper inflow congestion. In the cMRT we furthermore found a metastasis in the area of the foramen stylomastoideum. The patient underwent emergency radiation and chemotherapy. RESULTS: According to the present findings, this metastasis lead to the facial palsy as the initial symptom of the bronchogenic carcinoma. CONCLUSION: Therefore, therapy resistant facial palsy should be further diagnosed in detail, especially examined by imaging procedures.

Brain Neoplasms↗
PubMed2006

[Exostosis of the internal auditory canal in a patient with myotonic dystrophy].

A 53-year-old patient with myotonic dystrophy presented to our clinic with progressive bilateral hearing loss. The ENT status and particularly the otological examination were without pathological signs. Pure tone audiograms showed a bilateral moderate to severe sensorineural hearing loss. Routinely performed computed tomography of the temporal bones revealed the rare picture of exostosis of the internal auditory canals and the medial surface of the petrous bones. To our knowledge, this is the first report describing exostosis of the internal auditory canal in a patient with myotonic dystrophy, although at present it remains unclear in how far there is a causal connection between these two pathologies.

Audiometry, Pure-Tone↗
PubMed2004

[Characterisation of the gene expression profiles in the inner ear and the colliculus inferior of normal and deafened rats by gene-array-technology].

BACKGROUND: The phenotype of deafness and its mechanisms are morphologically and electrophysiologically well characterised. However, the molecular mechanisms and the consequences of deafness are poorly understood. METHODS: In this study we investigated changes in gene expression profiles in subfractions of the cochlea and the colliculus inferior, a non-cochlear tissue, of normal and deafened (10 % Neomycin) rats using the gene-array-technology. RNA was prepared from modiolus (Mo) und sensorineural epithel/lateral wall (SnE/Lw) und Colliculus inferior (IC), reverse transcribed with gene specific primers, labeled with (32)P-dATP and hybridised with its complementary sequences of 1200 rat ESTs. RESULTS: Similar gene expression profiles were detected in Mo- and SnE/Lw in normal as well in deafened rats differing significantly from those found in IC. In deafened animals differences in mRNA levels were determined in IC for 8 genes, in Mo für 17 genes and in SnE/Lw for 25 genes in comparison to those of normal rats. By using gene-arrays many genes described in the literature previously could be detected. Otherwise most of the genes found in the cochlea are unknown. CONCLUSIONS: The gene-array-technology is a valuable tool in otological research for gene expression analysis and, therefore, for comprehensive understanding of molecular processes in the inner ear. Furthermore gene screening for candidate genes could be a big step ahead in developing therapies of diseases of the inner ear.

Animals↗
PubMed2004

[The interesting case -- case number 61].

A 58-year-old patient presented after having undergone radiation therapy, afterloading therapy and chemotherapy of a T4 nasopharynx carcinoma. On the basis of the MRI findings, local tumour recurrence was suspected. The samples taken from the nasopharynx and the left maxillary sinus confirmed this diagnosis. Neuroradiological imaging showed that the tumour extended into the area around the left skull base and also revealed an irregular formation located in the left temporal flap. Therefore not only tumour resection (Fisch approach type C) but also a temporal craniotomy was indicated in order to determine the degree of intracerebral tumour extension. The dura mater, which had been intact, was intraoperatively opened and revealed vital brain tissue, i. e. tumour infiltration had not reached the brain. It was concluded that the radiological findings probably indicated a postradiogenic necrosis of the temporal flap. The presented case illustrates the rare differential diagnostic procedure carried out in a patient with radiogenic necrosis while taking into account the possibility of local tumour infiltration into the brain parenchyma.

Brachytherapy↗
PubMed2004

[The interesting case -- case no. 65].

Bilateral Osteomyelitis following frontal sinusitis is a rare complication in the antibiotic era. The main risk of a progredient course is mainly the formation of external subperiostal, epidural, subdural abscesses or brain abscesses with potentially life-threatening complications. This is a report on a patient who presented in our department with progredient cephalgia and swelling in the area around the glabella and frontal sinus. Macroscopical examination revealed septum deviation to the right side and nasal polyposis of the right nasal passage. A computed tomography of the paranasal sinuses showed subtotal soft tissue obstruction of all sinuses with the exception of the sphenoidal sinus. Bilateral osteolysis of the ventral osseous borders of the frontal sinus with accompanying osteosclerosis was also observed. The therapy consisted of radical frontal sinus surgery via Unterberger approach. This case demonstrates a rare case of bilateral frontal osteomyelitis together with the necessary diagnostic and therapeutic measures. The management consisted of the removal of all osteomyelitic bone and antibiotic therapy. Differential diagnostic procedures must be carried out in order to exclude orbital and intracranial complications. Regular follow-up examinations and a CT scan of the paranasal sinuses are part of the standard therapy.

Adult↗
PubMed2004

Co-expression of transforming growth factor-beta1 and glial cell line-derived neurotrophic factor in vestibular schwannoma.

HYPOTHESIS: Transforming growth factor-beta1, glial cell line-derived neurotrophic factor, and their receptors are expressed in vestibular schwannoma, and the expression data correlate with the proliferation activity (Ki-67 labeling index) and the clinical growth rate of vestibular schwannoma tissue. BACKGROUND: Glial cell line-derived neurotrophic factor is a potent growth factor for the central and peripheral nervous system. Recent results demonstrate that glial cell line-derived neurotrophic factor requires transforming growth factor-beta to exert its trophic effect on neural tissue. A functional role, including that in Schwann cell proliferation, is discussed for both transforming growth factor-beta1 and glial cell line-derived neurotrophic factor. METHODS: Immunohistochemical analysis for transforming growth factor-beta1 and glial cell line-derived neurotrophic factor and their receptors TbetaR II, GFRalpha-1, and Ret was performed on formalin-fixed, paraffin-embedded archival surgical specimens. The Ki-67 labeling index (mean Ki-67 labeling index and highest Ki-67 labeling index for Antoni Type A and Type B regions) and the clinical growth rate of vestibular schwannoma were determined and correlated with the expression patterns of the examined neurotrophic factors and their receptors. RESULTS: Results demonstrate co-expression of transforming growth factor-beta1 and glial cell line-derived neurotrophic factor with higher levels in Antoni Type A than in Antoni Type B regions. Ninety-five percent of vestibular schwannomas exhibited transforming growth factor-beta1 immunoreactivity, and glial cell line-derived neurotrophic factor expression was found in 100% of vestibular schwannoma specimens. Fifty percent of vestibular schwannoma displayed TbetaR II immunostaining, 100% showed positive reactions for GFRalpha-1, and 86% showed positive reactions for Ret. Statistical analysis revealed no significant correlation in neurotrophin expression related to sex, age, tumor size, clinical growth rate, or Ki-67-labeling indices. CONCLUSIONS: Expression of transforming growth factor-beta1 and glial cell line-derived neurotrophic factor may suggest a biological role for both growth factors in vestibular schwannomas. Trophic transforming growth factor-beta/glial cell line-derived neurotrophic factor synergism seems possible and is underscored by co-expression of both neurotrophic factors and their receptors.

Glial Cell Line-Derived Neurotrophic Factor↗
PubMed2003

Technical report: modification of a cochlear implant electrode for drug delivery to the inner ear.

OBJECTIVE: To investigate the possibility of modifying a cochlear implant electrode for the purpose of drug delivery to the cochlea. BACKGROUND: Animal experiments suggest that local therapy of the inner ear could be a promising new approach to the interventional treatment of inner ear disease, and that pharmacologic intervention could possibly enhance cochlear implant performance. One of the key aspects is the deployment of a means of drug delivery to the human inner ear. METHODS: The tip of the Contour electrode array was cut to open the lumen of the array, and a connecting piece was developed to connect the electrode to a pump. The feasibility of using the array for drug delivery was tested using both an Alzet mini-osmotic pump and a mechanical pump. The connection was tested for its stability in terms of leakage and resistance to tractive forces. The system was also applied to temporal bones to evaluate its applicability to the human cochlea. RESULTS: The modified Contour electrode is easy to handle in temporal bones and can be used to simulate drug delivery to the inner ear. The connection to the pump was sealed for all tested pump rates and resisted tractive forces up to 50 N. CONCLUSIONS: The described modified electrode could provide a safe and easy-to-handle means of combining electrical stimulation with the beneficial effects of a local drug therapy applied to the inner ear.

Cochlear Implantation↗
PubMed2003

[Cochlear implants in adults: indications and realizations. Part I: Diagnosis, operation techniques and results].

From the technical point of view, cochlear implant (CI) surgery in adults is a well established procedure. Pre- and postoperative evaluation, surgical approach and rehabilitation programs are standardized, presenting CI as a low risk procedure with rare complications similar to those of middle ear surgery. Modern advanced CI devices offer technical reliability and multiple speech encoding strategies and recently, even small processors which are worn behind the ear. Further technical advances are continuously available, even for implanted patients. Upgrading is usually easy because the outer parts of the implant are exchangeable and software upgrades can be transmitted transcutaneously to the implant. Assuming that medical and rehabilitation requirements are available, there are only very few indications against CI in adults. Candidate patients should therefore be transferred to CI-centres where a decision can be taken depending on presurgical evaluation results.

Adult↗
PubMed2003

[Cochlear implants in adults: indications and realization. Special cases and technical parameters of the implantation systems].

From the technical point of view, cochlear implant (CI) surgery in adults is a well established procedure. Pre- and postoperative evaluation, surgical approach and rehabilitation programs are standardized, presenting CI as a low risk procedure with rare complications similar to those of middle ear surgery. Part 1 described the diagnostics, surgical procedure and possible complications. The second part will cover the contraindications, special cases as well as the technical parameters of the modern implant system.

Adult↗
PubMed2002

Telomerase activity, telomere length, and apoptosis: a comparison between acquired cholesteatoma and squamous cell carcinoma.

BACKGROUND: Cholesteatoma disease is characterized by accumulation of keratinizing epithelium. Several molecular markers of tumor formation have been found in cholesteatoma (e.g. upregulation of matrix metalloproteinases, c and activation of angiogenesis). Other molecular findings clearly distinguish between cholesteatoma and malignant tumors (e.g., lack of chromosomal instability, intact checkpoint responses). To further distinguish the molecular mechanisms in cholesteatoma from malignant tumors, the authors determined telomerase activity and telomere length in both tissue types. METHODS: To evaluate the role of telomerase activation and telomere length in cholesteatoma, 29 cholesteatoma samples and 9 squamous cell carcinomas were analyzed for telomerase activity and telomere length. In addition, the rate of apoptosis was determined in both groups, using the TdT-mediated dUTP nick end labeling technique. RESULTS: As previously described, a high proportion of squamous cell carcinoma exhibited telomerase activity (6/9, 66%). By contrast, a significantly lower rate of telomerase activity was found in cholesteatoma samples (1/29, 3.4%, p = 0.0002). Despite the differences in telomerase activity, the telomere length was similar in cholesteatoma (mean length 7.43 kb) and in squamous cell carcinoma (mean length 7.99 kb; difference not significant, p = 0.1364). The low rate of telomerase activity in cholesteatoma was accompanied by significantly higher rates of apoptosis in cholesteatoma (mean 30%) compared with squamous cell carcinoma tissue (mean 3%, p = 0.0031). CONCLUSIONS: Taken together, these data show that telomerase activation is a rare event in cholesteatoma and that the absence of telomerase activity is accompanied by high rates of apoptosis in cholesteatoma. It is proposed that the absence of telomerase limits the proliferative capacity of cholesteatoma by induction of apoptosis, whereas the presence of telomerase allows immortal growth of squamous cell carcinoma.

Adult↗