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Biomedical subjects

G Répássy

Publications and source records attributed to G Répássy.

At least 19 recordsLinked to original sources
PubMed2005

D2 autoreceptor inhibition reveals oxygen-glucose deprivation-induced release of dopamine in guinea-pig cochlea.

Dopamine (DA), released from the lateral olivocochlear (LOC) efferent terminals, the efferent arm of the short-loop feedback in the cochlea, is considered as a protective factor in the inner ear since it inhibits auditory nerve dendrite firing in ischemia- or noise-induced excitotoxicity leading to sensorineural hearing loss (SNHL). In the present study we investigated the effect of oxygen-glucose deprivation (OGD), an in vitro ischemia model, on guinea-pig cochlear [(3)H]DA release in a microvolume superfusion system. We found that OGD alone failed to induce a detectable elevation of [(3)H]DA level, but in the presence of specific D(2) receptor antagonists, sulpiride and L-741,626, it evoked a significant increase in the extracellular concentration of [(3)H]DA. D(2) negative feedback receptors are involved not exclusively in the regulation of synthesis and vesicular release of DA, but also in the activation of its reuptake. Thus, D(2) receptor antagonism interferes with the powerful reuptake of DA from the extracellular space. To explore the underlying mechanism of this DA-releasing effect we applied nomifensine and found that the effect of OGD on cochlear DA release in the presence of D(2) antagonists could be inhibited by this selective DA uptake inhibitor. This finding indicates that the OGD-evoked DA release was mainly mediated through the reverse operation of the DA transporter. The two structurally different D(2) antagonists also augmented the electrical field stimulation-evoked release of DA proving the presence of D(2) autoreceptors on dopaminergic LOC terminals. Our results confirm the presence and role of D(2) DA autoreceptors in the regulation of DA release from LOC efferents, and suggest a protective local mechanism during ischemia which involves the direct transporter-mediated release of DA. Increasing the release of the protective transmitter DA locally in the inner ear may form the basis of future new therapeutic strategies in patients suffering from SNHL.

Animals↗
PubMed2003

The effect of leukocyte interleukin injection (Multikine) treatment on the peritumoral and intratumoral subpopulation of mononuclear cells and on tumor epithelia: a possible new approach to augmenting sensitivity to radiation therapy and chemotherapy in oral cancer--a multicenter phase I/II clinical Trial.

OBJECTIVES/HYPOTHESIS: The main objective of this study was to investigate the effect of the administration of a novel immunoadjuvant, leukocyte interleukin injection, as part of an immuno-augmenting treatment regimen on the peritumoral and intratumoral subpopulations of the tumor infiltrating mononuclear cells and on the epithelial and stromal components, when administered to patients with advanced primary oral squamous cell carcinoma classified as T2-3N0-2M0, as compared with disease-matched control patients (not treated with leukocyte interleukin injection). STUDY DESIGN: Multicenter Phase I/II clinical trial. Fifty-four patients from four clinical centers were included in the dose-escalating study (27 in each group [leukocyte interleukin injection-treated and control groups]). Cumulative leukocyte inter-leukin injection doses were 2400, 4800, and 8000 IU (as interleukin-2 equivalent). METHODS: Paraffin-embedded tumor samples obtained at surgical resection of the residual tumor (between days 21 and 28 after treatment initiation) were used. Histological analysis, necrosis evaluation, and American Joint Committee on Cancer grading were performed from H&E-stained sections. Immunohistochemical analysis was performed on three different tumor regions (surface, zone 1; center, zone 2; and tumor-stroma interface, zone 3). Trichrome staining was used to evaluate connective tissue, and morphometric measurements were made using ImagePro analysis software. Cell cycling was determined by the use of Ki-67 marker. RESULTS: Leukocyte interleukin injection treatment induced a shift from stromal infiltrating T cells toward intraepithelial T cells and posted a significant (P <.05) increase in intraepithelial CD3-positive T cells independent of the leukocyte interleukin injection dose, whereas the increase in CD25 (interleukin-2 receptor alpha [IL-2Ralpha])-positive lymphoid cells was significant only at the lowest leukocyte interleukin injection dose (P <.05). Furthermore, both low- and medium-dose leukocyte interleukin injection treatment induced a significant (P <.05) increase in the number of cycling tumor cells, as compared with control values. CONCLUSION: The results could be highly beneficial for patients with oral squamous cell carcinoma. First, leukocyte interleukin injection treatment induces T-cell migration into cancer nests and, second, noncycling cancer cells may enter cell cycling on administration of leukocyte interleukin injection. This latter effect may modulate the susceptibility of cancer cells to radiation therapy and chemotherapy. The findings may indicate a need to re-evaluate the way in which follow-up treatment (with radiation therapy and chemotherapy) of patients with head and neck cancer is currently approached.

Adjuvants, Immunologic↗
PubMed2001

A new aspect of aminoglycoside ototoxicity: impairment of cochlear dopamine release.

Aminoglycoside ototoxicity is a well-documented process via several pathophysiological pathways. The protective role of cochlear dopamine, released from the lateral olivocochlear efferents, was implicated previously in case of ischemia or acoustic trauma, as it postsynaptically inhibits the effect of excessively released glutamate from the hair cells. In our in vitro superfusion experiments we showed that neomycin dose- dependently inhibits the dopamine release from isolated guinea pig cochlea, while gentamicin and kanamycin was ineffective on it. After chronic application of neomycin the dopamine outflow did not change significantly, suggesting an adaptive process. In our experiments we have found a possibly new action site of one of the aminoglycoside antibiotics, neomycin.

Animals↗
PubMed2001

Apoptotic and mitotic activity in squamous cell carcinoma cells after combined modality treatment with gamma-irradiation and dibromodulcitol.

A-431 squamous cell carcinoma cells were treated in vitro with either 4 Gy radiation of 15 (or 45) microg/ml dibromodulcitol (DBD), as well as with combined 4 Gy irradiation and DBD, with the latter as either a pretreatment or post-treatment. DBD alone or in combination with radiation had a greater effect on cell proliferation than the effect of radiation alone. The difference is due to a higher level of apoptosis induced by DBD, especially in conjunction with radiation. Such a combination may therefore be useful in the treatment of squamous cell carcinoma, which in general responds poorly to radiation therapy.

Antineoplastic Agents, Alkylating↗
PubMed2001

Evidences of vascular origin of cochleovestibular dysfunction.

OBJECTIVES: When the vascular disorder of the cochleovestibular system is mentioned, the diagnosis is based on exclusion of other diseases. Since arteries of the cochleovestibular system cannot be directly visualized, physicians must deduce from the vascular risk factors and the vascular lesion of other territories to the vascular cochleovestibular disease. MATERIALS AND METHODS: Authors analyzed the data of 19 patients with vertigo. Detailed blood tests, complete neurootological and audiological examination including ABR, carotid and vertebral artery Doppler sonography, MRI and MRA was performed. RESULTS: Cochleovestibular examination and ABR showed abnormalities in 73.7%, either carotid and vertebral artery Doppler or MRI showed abnormalities in 57.9%. MRA was abnormal in 47.4%. In most of the patients multiple risk factors of cerebrovascular disorder could be found. CONCLUSIONS: The cochleovestibular system disorders can be considered to be of vascular origin if the examinations exclude other diseases, if the patients have vascular risk factors and if other territories of brain accessible for imaging methods show vascular disorders.

Carotid Arteries↗
PubMed2001

Progression difference between cancers of the larynx and hypopharynx is not due to tumor size and vascularization.

A recent survey of head and neck cancer indicated a sharp difference in survival between cancer of the hypopharynx and cancers formed in other head and neck sites. We have analyzed tumor size relative to clinical stage and vascularization as possible causes for such a difference in a series of 21 patients with cancer of the laryngopharynx (11 glottic and 10 hypopharyngeal). We found that the volume of the smallest cancers of the larynx at stage 2 is significantly larger than the volume of the cancers of the hypopharynx at stage 4 (P < 0.05). Next, we have determined by immunohistochemistry and morphometry the microvessel density, microvessel perimeter, and vascular endothelial growth factor (VEGF) expression of laryngo-hypopharyngeal cancers. Analysis of these data indicates that there is no difference in vascularization and VEGF expression between these two tumor types. These data strongly suggest that the invasive but not the angiogenic phenotype of hypopharyngeal cancer cells could be responsible for the more aggressive biologic behavior of this head and neck cancer subtype.

Analysis of Variance↗
PubMed2001

Air caloric computer system application in monitoring vestibular function changes after cochlear implantation.

INTRODUCTION: The computer-based ENG system's analytical routine refinements are available only in research laboratories. The computer-based system contains a stimulator for saccadic eye-movement and an air caloric stimulator interconnected to the registration program and analysis software. Several authors have reported the preoperative and postoperative vestibular functions in cochlear implant patients. The safe examination of the operated ear and comparison of the preoperative and postoperative average slow phase velocities of the caloric nystagmus is possible using the air caloric computer system. METHODS: The authors have used a computer-based ENG system with caloric air stimulation, which is very useful for examination of the operated ear. The vestibular system of patients with total deafness was examined before and after the cochlear implantation. The results of 60 vestibular examinations of 64 patients are reported. RESULTS: The vestibular function in the operated ear was found unchanged in 20 patients. In 14 patients the vestibular function was worse. In 16 patients the postoperative vestibular responsiveness improved. The detailed data analysis of 10 patients in whom preoperative and postoperative vestibular examination was similar was performed by the authors. The preoperative and postoperative average slow phase velocity values and the relative canal paresis was observed. The values demonstrated that the caloric responsiveness of the operated ear improved in few cases. CONCLUSIONS: The computer-based air caloric system is a useful and safe method in evaluation of the vestibular system changes after ear surgery. The reason of the improvement of vestibular responsiveness is not clear. The results need further investigation to solve the problem of vestibular responsiveness improvement after cochlear implantation.

Adolescent↗
PubMed2000

Veratridine-evoked release of dopamine from guinea pig isolated cochlea.

Dopamine released from the lateral olivocochlear efferent system is thought to inhibit the toxic effect of the extreme glutamate outflow from the inner hair cells during ischemia or acoustic trauma. Using in vitro microvolume superfusion, we have studied the release of [(3)H]dopamine from the lateral olivocochlear efferent bundle of guinea pig in response to accumulation of [Na(+)](i), under condition characteristics of ischemia. Veratridine, that acts only on excitable membranes as a specific activator of voltage-sensitive sodium channels, significantly increased the electrically evoked release of [(3)H]dopamine, which was completely inhibited by tetrodotoxin. Dizocilpine (MK-801), a non-competitive NMDA-receptor antagonist, and GYKI-52466, a selective non-NMDA-receptor antagonist, had no effect on veratridine-induced [(3)H]dopamine release. Our data provide further evidence that the cochlear release of dopamine is of neural origin and possibly independent on a local effect of glutamate. The veratridine-induced transmitter release in the cochlea will be a very useful method in studying the effect of drugs on ischemic injury.

Animals↗
PubMed2000

Reoperations after cochlear implantation.

During the 14-year history of cochlear implantation at Semmelweis University, 95 implantations were performed. There were 15 reoperations, and 2 patients had been operated 3 times. All of the reoperated patients received round window or intracochlear MedE1 devices. Successful reinsertion of the electrode was performed without significant difficulty, though in some cases osteoneogenesis was found in the round window or in the scala tympani. None of the patients suffered any inner ear abnormalities due to the first implant, and even the patient with a third implant in the same ear had excellent results and obtained better discrimination scores with the new device. In the authors' opinion, on the basis of the accumulated experience of nearly 100 implantations and 15 reoperations, replacement of the early generation extracochlear implants is most advisable and can be accomplished without adverse effects.

Cochlear Implantation↗
PubMed2000

Characteristic distribution patterns of tenascin in laryngeal and hypopharyngeal cancers.

OBJECTIVES: Progression of malignant neoplasias is accompanied by alteration of the extracellular matrix (ECM) composition. Tenascin is known as a member of the adhesion-modulating family of ECM macromolecules; thus its expression and distribution may have significant influence on tumor cell proliferation and invasiveness. STUDY DESIGN: The present study was carried out to determine the distribution pattern of tenascin in laryngeal and hypopharyngeal cancer samples. METHODS: In double and triple immunofluorescent staining reactions the detection of tenascin was combined with labelings for cytokeratin (marker protein of epithelial cells), for CD-34 (endothelial cell surface glycoprotein), and for a reaction with Ki-67 monoclonal antibody (nuclear antigen in proliferating cells). RESULTS: In laryngeal cancers, in early stages of tumor growth a markedly enhanced production of tenascin at the tumor host interphase was observed. In the later stages of tumor progression, a high number of blood vessels located in the tumorous tissues were also strongly labeled for tenascin. Around these vessels a significant number of proliferating tumor cells could be detected. In contrast, in hypopharyngeal cancers this vasculature-associated staining pattern could be observed from the very early stage of tumor development. In laryngeal and in hypopharyngeal cancers, tenascin upregulation strongly correlated with metastasis formation, early tumor recurrence, and lethal outcome of the disease. CONCLUSIONS: Clinical and immunohistologic data indicate that the accumulation of tenascin in the tumor blood vessels is an unfavorable prognostic indicator in laryngeal and hypopharyngeal cancers.

Adult↗
PubMed1999

Electronystagmographic analysis of optokinetic nystagmus for the evaluation of ocular symptoms in myasthenia gravis.

Ocular symptoms of 17 myasthenia gravis (MG) patients were examined by electronystagmographic registration of optokinetic nystagmus. The aim of this study was to replace the subjective methods used previously with a more reliable quantitative technique and thus assess ophthalmoplegia and diplopia, important initial symptoms in MG. Slow phase angular speed values of foveolar type optokinetic nystagmus in the horizontal plane at 10, 20 and 30 degrees/s target speed were determined. Measurements were performed before and after administration of Mestinon, a reversible cholinesterase inhibitor. Twelve healthy volunteers were examined as controls under standard conditions. Results showed significant differences between MG patients and control group. Slow-phase angular speed was significantly larger after Mestinon administration (p < 0.001). It is concluded, that the exhaustion of external ocular muscles in MG can be well characterized by the determination of the slow phase angular speed values of optokinetic nystagmus (OKN). The examination of OKN was also recommended for the evaluation of ocular symptoms in other neurological disorders.

Adult↗
PubMed1999

Cochlear implantation influences contralateral hearing and vestibular responsiveness.

A cochlear implant program has been carried out at the ORL Clinic of Semmelweis University in Budapest since 1985. Different devices and techniques have been used in pre- and postlingual children and adults. Over the last 6 years contralateral hearing improvement has been observed in 18 patients. This phenomenon can usually be demonstrated 6 months after the operation. Since our first observation several other authors have confirmed this phenomenon. However, the underlying mechanism is still obscure; both the efferent innervation and the plasticity of the brain may be important factors. The vestibular function of cochlear implant candidates was checked routinely pre- and postoperatively and changes in vestibular responsiveness were observed. Over the last 3 years air-caloric stimulation has been performed by means of a computer-based ENG system. In most patients the vestibular function was unchanged after the implantation. but in some cases a significant improvement in vestibular responsiveness was noted. Here we briefly describe cases of re-implantation carried out at the clinic. All the patients obtained better speech discrimination scores after having been implanted with intracochlear devices. None of the patients suffered any inner ear abnormality due to the first implant.

Adult↗
PubMed1998

Expression of invasion markers CD44v6/v3, NM23 and MMP2 in laryngeal and hypopharyngeal carcinoma.

Twelve laryngeal squamous cell carcinoma cases (7 laryngeal and 5 hypopharyngeal cancer; 15 samples) were analysed by immunohistochemistry for the expression of invasion markers CD44v6/v3, NM23 and matrix metalloproteinase, MMP2. The laryngeal epithelium showed CD44v6+/v3+/NM23-/MMP2- phenotype. When tumors were grouped into TNM categories the phenotype of the T2 and T3 tumors was similar, characterised by decreased CD44v3+ and lack of MMP2 expressions. Meanwhile the NM23 expression was more frequent in T3 tumors. In T4 stage the frequency of NM23 and MMP2 positive cases increased (5/6 and 4/6, respectively) but there was no correlation with the appearence of lymph node metastasis. Comparison of the phenotype of laryngeal and hypopharyngeal tumors, irrespective of the TNM stages, revealed characteristic differences: T2 stage laryngeal tumors showed decreased CD44v3 and occasional NM23 and MMP2 positivity, while in T3 stage these tumors were characterised by increased frequency of NM23 positivity. The phenotype of the hypopharyngeal tumors was significantly different with a high frequency of MMP2 positive cases (5/6) and NM23+/low CD44v3+ phenotype. The sharp differences in the phenotypes of laryngeal and hypopharyngeal carcinomas were connected to the differences in their invasive capacity unlike to the size of the tumors, since the T4 stage hypopharyngeal tumors had a significantly smaller size than laryngeal ones, even at lower stages.

Antigens, Neoplasm↗
PubMed1998

Apoptosis in the human inner ear. Detection by in situ end-labeling of fragmented DNA and correlation with other markers.

The aim of this study was to obtain baseline data on the recently described special form of single cell death, apoptosis, in normal human inner ears. For this purpose, in situ end-labeling of the fragmented DNA was applied, in conjunction with apoptosis-related markers, to detect cellular elements showing programmed cell death in decalcified and paraffin-embedded tissues. Over 20 specimens were analyzed which were obtained from autopsy cases with no history of acoustic lesions confirmed by histopathology. Based on staining results, we saw no apoptotic signs in the majority of normal adult inner ears. An apoptotic cell captured in the Reissner's membrane of the cochlea from an old patient may, however, indicate an age-related subtle cell loss with the process of apoptosis. Nevertheless, the fact that more apoptosis was not found in our cases suggests that this phenomenon does not contribute significantly to the tissue homeostasis in the adult inner ear under normal conditions. These data are in accordance with our immunohistochemical findings on the p53 nucleoprotein, and proliferating cell nuclear antigen expression since there was no staining in any of the cellular elements, including the mesenchymal cells. This reflects a stationary and stable condition of cells of the vestibular and the cochlear structures, probably to maintain their integrity and the fine sensory functions. As opposed to the above findings, during inner ear development, the epithelial cells lining the cochlear lumen, the ossifying cartilage of the temporal bone, and the mesenchymal cells show different degrees of proliferation in combination with single cell death as signs of maturation of the vestibular and the cochlear apparatus. In addition, apoptosis has been demonstrated in cells of the cochlear stria vascularis from an adult patient treated with high doses of cisplatin, vinblastine and bleomycin prior to death. Furthermore, a wide range of apoptosis could be induced experimentally in a normal ear by an external perfusion of actinomycin D (ActD), which is known to produce programmed cell death in many cell types of different origins. The potential role of cytostatic agents in the apoptotic process of the inner ear needs, however, to be confirmed in large-scale specimens from patients treated with genotoxins. The fact, however, that apoptotic cells are also seen in association with ActD indicates that the fine sensory structure of the cochlea may also be a target for certain chemotherapeutic agents when administered in high doses.

Adult↗
PubMed1998

Otoacoustic emission in myasthenia gravis patients and the role of efferent activation.

We performed transient evoked otoacoustic emission (TEOAE) measurements on 29 ears of myasthenia gravis (MG) patients. The purpose of the study was to support the role of acetylcholine (ACh) in the efferent innervation of cochlear outer hair cells (OHCs). Another aim was to establish additional diagnostic tools for the early determination of MG. Initially, threshold audiometry and impedance measurements showed normal values on the ears examined. The main finding was that TEOAE values were significantly lower in MG patients than in healthy controls. Mestinon, a reversible cholinesterase inhibitor, resulted in a significant increase in mean values of TEOAEs, although these values were still lower than normal. The results suggest that in MG, acetylcholine receptor (AChR) autoantibodies inhibit the function of OHC AChRs. Thus, the TEOAE generated by the active movements of OHCs is decreased in MG. Mestinon prevents the degradation of ACh, and thus stimulates efferent function and increases TEOAE values. The results obtained in this study support the role of ACh in the efferent function of OHC, as well as the impaired function of hair cell AChRs in MG patients. Consequently, measuring TEOAEs may be useful in the early diagnosis of some forms of MG. These results reinforce the importance of collaboration between neurologists and otolaryngologists in the management of diseases with pathological neurotransmission.

Adult↗
PubMed1998

Fibrin deposition in squamous cell carcinomas of the larynx and hypopharynx.

Extravascular fibrin deposition is frequently observed within and around neoplastic tissue and has been implicated in various aspects of tumor growth. The distribution of fibrin deposits was investigated in squamous cell carcinomas representing different stages of tumor progression of the larynx (n = 25) and hypopharynx (n = 9) by immunofluorescent techniques. Double and treble labelings were used to detect fibrinogen and fibrin in combination with marker antigens for tumor cells (cytokeratin), endothelial cells (von Willebrand factor), macrophages (recognized by KiM7), as well as factor XIII subunit A (FXIIIA) and tenascin (an embryonic extracellular matrix protein newly expressed during tumorigenesis). All tissue samples showed specific staining for fibrinogen/fibrin. Fibrin deposition was localized almost exclusively in the connective tissue compartment of tumors with characteristic accumulation at the interface of connective tissue and the tumorous parenchyma. In certain tumor samples showing highly invasive characteristics, fibrin deposits were observed in close association with tumor blood vessels in the tumor cell nodules. The overlapping reactions with polyclonal antibody to fibrinogen/fibrin and monoclonal antibody to fibrin indicate the activation of the coagulation cascade resulting in in situ thrombin activation and fibrin formation. Fibrin was crosslinked and stabilized by FXIIIA as revealed by urea insolubility test. Accumulation of phagocytozing macrophages detected by Ki M7 monoclonal antibody could be seen in areas of fibrin deposition. The blood coagulation factor XIIIA was detected in and around the cells labeled with Ki M7 antibody. Tenascin and fibrin deposits were found in the same localization in the tumor stroma and in association with tumor blood vessels within the tumor cell nodules. Neither fibrin nor tenascin were detected in the histologically normal tissue adjacent to tumors. The close association between fibrin deposits and macrophage accumulation strongly suggests the active participation of tumor-associated macrophages in the formation of stabilized intratumoral fibrin that facilitates tumor matrix generation and tumor angiogenesis.

Adult↗