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M Ptok

Publications and source records attributed to M Ptok.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Maturation of postsynaptic acetylcholine receptors in cochlear outer hair cells].

Sound transduction in the inner ear is controlled by olivocochlear efferents terminating predominantly at outer hair cells (OHC). Development of efferent fibers and thereby of postsynaptic OHC receptors was studied immunohistochemically in 13 cochleae from fetal guinea pigs. The gestational ages of the animals ranged from gestational day (GD) 35 to GD 56. To visualize nicotinic acetylcholine receptors (nAChR), sera were used from myasthenia gravis patients with confirmed nAChR antibodies. At GD 53 no staining was observed, whereas at GD 58 a striking nAChR-immunoreactivity was found. In cochleae from adult animals postsynaptic receptors were visualized at the bases of all three rows of OHCs. The region of the inner hair cells (IHC) was not stained. The present results indicate that nAChRs in guinea pig cochleae develop between GD 53 and GD 58. Maturation of the postsynaptic nAChRs coincides with development of OHC motile properties.

Acetylcholine↗
PubMed1994

[Changes in transitory evoked otoacoustic emissions and acoustic distortion products in disorders of eustachian tube ventilation].

Middle ear impedance plays an important role in the retrograde middle ear transfer and interpretation of otoacoustic emissions (OAE). Changes of emission spectra and reproducibility or absence of sound emissions can be caused by middle ear dysfunction. To avoid misinterpretation, especially in infant screening, we combined measurements of transiently-evoked otoacoustic emissions (TEOAE), distortion products (DPOAE) and middle ear pressure. With a single acoustic probe ear canal baro-pressure was adjusted individually to the middle ear pressure, allowing OAE to be measured at maximum compliance of the middle ear. Fifty children (ages, 3-8 years) were examined with hypoventilation of the middle ear. Twenty-five normally hearing adults were also studied. Positive and negative middle ear pressures significantly attenuated the amplitude of low-frequency OAE (< 2 kHz), whereas high-frequency emissions were stable. Individual adaptations of static ear canal pressure eliminated these alterations of TEOAE and DPOAE.

Acoustic Impedance Tests↗
PubMed1994

[Functional screening evaluation of hearing aids].

A complaint about a malfunctioning hearing aid (HA) usually will require thorough testing of all aspects of hearing aid functions by the hearing aid dispenser. However, ENT physicians can also detect defects easily by following the simple screening procedure described here. Before testing the HA function, the following questions should be answered: Are the body of the hearing aid and ear mold intact? Is the ear canal free of irritation and is the acoustic isolation of the ear canal by the HA sufficient? A rough estimate of HA function can be accomplished by covering the HA with the hand. If the HA is switched on, a feedback, high-pitched sound should be produced. HA amplification can be assessed by using a stethoclip. After the examination is completed, all switches should be put back into their previous positions. Although these basic procedures are not equivalent to diligent and comprehensive acoustical testing, they are still useful for the otologist to detect major faults in the HA before referring the patient to the hearing aid dispenser.

Adolescent↗
PubMed1993

Relationship of monoclonal antibody (KHRI 3 epitope) to cochlear supporting cell microvilli in the guinea pig.

As reported previously, monoclonal antibodies can be generated that bind against guinea pig cochlear structures. Preliminary immunohistochemical characterization revealed that one of these monoclonal antibodies (KHRI 3) most probably binds against a surface structure of guinea pig cochlear supporting cells. This study was undertaken to further characterize the KHRI 3 epitope in the cochlea. Since KHRI 3 immunolabeling appeared to be punctate and epitope expression was most pronounced in the reticular lamina, we hypothesized that KHRI 3 epitopes are related to microvilli. To prove this hypothesis immunoelectron microscopy was used. Also investigated was how epitope expression is altered in the reticular lamina microvilli following drug or noise-induced changes. When immunocytochemical results were compared to scanning electron microscopy findings, a striking correlation could be seen between changes in KRHI 3 immunolabeling and changes in the distribution of microvilli. These findings support the assumption that KHRI 3 epitopes are related to microvilli of inner ear supporting cells.

Animals↗
PubMed1993

Distribution of KHRI 3 epitopes in the inner ear.

Murine monoclonal antibodies against cochlear structures were previously generated to obtain probes for elucidating the function of cochlear cell subsets. Preliminary immunocytochemical characterization showed that the monoclonal antibody KHRI 3 binds to supporting cells but not sensory cells in the guinea pig cochlea. We have now investigated KHRI 3 epitopes in other species and other parts of the inner ear. The KHRI 3 epitope appears to be species-specific since no immunolabeling was seen in rat inner ear nor in chick inner ear. In immunocytochemical assays in the guinea pig vestibular tissues KHRI 3 stained saccular wall cells and transitional epithelial cells in the utricle and ampules as well as clusters of cells in the endolymphatic sac. In Western blots KHRI 3 stained a broad 70-75 kDa band in lanes loaded with guinea pig cochlea homogenates--as seen previously--as well as in lanes loaded with vestibular tissue homogenates. The immunolabeling patterns suggest that KHRI 3 epitopes are cell membrane components or related to membrane structures. Thus the monoclonal antibody KHRI 3 appears to define a nonsensory cell subset in the guinea pig inner ear that can be identified by expression of KHRI 3 epitopes.

Animals↗
PubMed1993

[Spectral analysis of sounds produced by musical instruments and other sounding bodies for hearing screening of children].

Some time ago audiological screening in infants was mostly performed using musical instruments or equivalents. The use of acoustic evoked potentials and oto-acoustic emissions changed the strategies of hearing assessment in newborns and infants, however, musical instruments are still in use. An adequate interpretation of screening results obtained with musical instruments necessitates a profound knowledge of frequencies and intensities derived from these instruments. In this study spectral analyses of sounds from these instruments were performed. The results may be of value for those using musical instruments as a tool for audiological screening. In addition, the results show that with some instruments intensities able to cause inner ear damage can be generated.

Child↗
PubMed1993

[Evaluation of laryngeal sound generation with FFT analysis of glottic impedance in patients with recurrent nerve paralysis].

The electroglottogram (EEG) is known to be related to the motion of vocal folds. The major hypothesis is that the EGG is related to the area of contact of the vocal folds. EGG is thought to be incapable of measuring or monitoring non-contact type vibratory events in the larynx. Recently it was demonstrated by fast Fourier transformation (FFT) analysis of EGG curves that the resulting EGG can be interpreted as a sum of a 'laryngeal fundamental with overtones'. This necessitates a new interpretation of normal EGG waveshape. This study was undertaken to prove the hypothesis that (pathological) EGG curves contain information even about non-contact type vibratory events in the larynx during phonation when analyzed by FFT. Patients with vocal fold paralysis were asked to phonate sustained vowels (/a/, /e/, /i/, /o/, /u/). Voice sounds and EGG signals were recorded simultaneously, routed to a frequency analyzer and subjected to real-time FFT analysis. In all cases original EGG signals would have been classified as pathological. However, in all recordings the laryngeal fundamental frequency and--in some patients--overtones with their intensities could be extracted and compared to harmonics extracted from voice sound. This is the first report of FFT analysis of EGG signals in patients with vocal fold paralysis. It is proposed that vocal folds vibratory events may be of non-contact type and that they can be monitored by analysis of glottic impedance.

Adult↗
PubMed1993

[Pseudoglottis after laryngeal trauma with bilateral recurrent laryngeal nerve paralysis].

Voice is produced by a steady flow of air from the lungs, which is segmented at the laryngeal level into a series of air puffs. The segmentation is facilitated by periodic vocal fold vibrations under physiological conditions. In some cases, as in partial laryngectomy, segmentation of air stream is caused by vibrations of the false vocal folds. Here we report a case of an air stream segmentation mechanism at the laryngeal level producing an acceptable voice quality after fracture of the larynx and bilateral vocal fold paralysis. A lateral fixation of the left vocal fold was performed because of dyspnea. Six years later the patient was reexamined, at which time he had fairly intelligible speech and did not complain about dyspnea or aspiration. The voicing source was found to be a round soft tissue lump of approximately 1.5 cm diameter. This tissue was formed from the former left arytenoid area. During phonation the right arytenoid cartilage approximated to the petiolus, while the left neoarytenoid closed the residual opening of the larynx. However, during voicing, this latter tissue exhibited a vertical vibratory pattern similar to false vocal fold vibration and mucosal vibration of true vocal folds at high pitch. It seems reasonable to speculate that the mass of the tissue lump had become well balanced so that the very low pitch of the false vocal fold and a high pitch as in head register phonation could be avoided. Since the patient suffered from a pronounced gag reflex during examination, stroboscopy was videorecorded and analyzed off-line.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Voice rehabilitation after laryngectomy with voice prostheses. Results of a prospective follow-up study].

Although the results of surgical rehabilitation by means of voice prostheses are on the average better than rehabilitation via oesophageal speech, the tracheoesophageal puncture (TEP)-technique has so far not been widely used in Germany. The majority of hospitals still prefer the "traditional" method of voice rehabilitation using oesophageal speech. The present prospective study was undertaken to compare the results of postlaryngectomy vocal rehabilitation, if patients were offered the surgical voice rehabilitation via voice prosthesis as an alternative to oesophageal speech. Taking into account all the patients who underwent laryngectomy from 1989 until 1990 in Tübingen, primary surgical voice rehabilitation was performed in 44 out of 54 patients (81.5%). Interestingly enough, 34 patients who underwent laryngectomy were able to perform communication via the telephone on the day of their discharge. Moreover, one-third of the laryngectomised patients showed a significant increase in speech intelligibility within the first six months after laryngectomy. 36 patients with laryngectomy were able to attain proficiency 6 months after surgery. In 12 patients the prosthesis had to be removed, since either phonation was impossible or patients successfully learned and preferred oesophageal speech. In conclusion, independent of the method of voice rehabilitation (prosthesis, electrolarynx, oesophageal speech), our results support the hypothesis that a voice rehabilitation regimen will yield a higher rehabilitation rate of patients if rehabilitation via surgical voice is offered as an alternative to learning the oesophageal voice. Therefore, it seems to be advisable that patients are allowed to have the choice between surgical rehabilitation and oesophageal speech restoration.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1992

[Computer-assisted ENT medical literature search and literature management--a report of experiences].

The increasing number of medical articles calls for a computer-aided system for literature database programs, literature retrieval and bibliography systems. We report an assessment of a dedicated modem line to DIMDI of Cologne (an institute offering a variety of biomedical, psychological and other literature databases), Medline on Silverplatter, Current Contents on disk and the Papyrus bibliography system. The databases with retrieval software are installed on a IBM-compatible PC (386 with an 80MB hard disc) and 4 CD-ROM players. Medline contains bibliographic citations and abstracts of biomedical literature; Current Contents on disk with its weekly update provides citations of articles published very recently; and the Papyrus bibliography system maintains a permanent collection of reference citations. When linked to a word processor, Papyrus can automatically read the manuscript, create a bibliography and produce a new copy of the manuscript in which the citations have been appropriately edited, and the references can be printed in any desired format. Although not without drawbacks, the configuration described here proved to be a valuable, time-saving tool to access citations precisely.

Computer Systems↗
PubMed1991

Monoclonal antibodies to inner ear antigens: II. Antigens expressed in sensory cell stereocilia.

To develop biological reagents for investigating structure-function relationships in the organ of Corti, we have raised monoclonal antibodies, (MAb) to inner ear tissues. Our first series of antibodies prepared after intrasplenic immunization of mice with guinea pig tissues, identified antigens restricted to supporting cell structures, but no hair cell specific antibodies were developed [Zajic et al., Hear. Res. 52, 59-72, 1991]. In this report we describe the isolation, binding specificity and initial characterization of the stereocilia-binding monoclonal antibodies, KHRI-4, and KHRI-5. Mice were immunized with avian, amphibian and mammalian sensory hair cell-containing tissues and antibodies were screened for selective binding to cochlear extracts in ELISA. In the inner ear, KHRI-4 and KHRI-5 bind specifically to stereocilia in both avian and mammalian cochlear and vestibular tissue preparations using immunofluorescence and immunoperoxidase assays. In other tissues only certain cells of mesothelial origin, such as smooth muscle in gut and the arteriolar vasculature, were stained by KHRI-4 indicating that the antigenic structure defined by this antibody has limited distribution. KHRI-5 binding could be detected in other tissues only at high antibody concentrations suggesting that the gene product identified by this antibody is also weakly expressed in other cell lineages. Western blot analysis showed that KHRI-4 and -5 detect different protein complexes. KHRI-4 identifies an antigenic structure common to gut, cochlea, vestibular tissue and cultured fibroblasts consisting of a approximately 195 and a 230 kDa heterodimer designated p195/230. KHRI-5 binds to a prominent approximately 200-210 kDa band in Western blots of cochlear tissues, gut and fibroblasts. In immunoprecipitation experiments, KHRI-5 precipitated three proteins of Mr approximately 200-210, 230 and 260 kDa indicating that the approximately 200-210 kDa protein carrying the epitope for this antibody is a member of a heterotrimer complex. Our results show that these protein complexes are structural components of stereocilia and that the same proteins are arrayed in conjunction with the actin stress fibers of cultured mesothelial cells. Thus, they are likely to be important for maintaining the actin structure of stereocilia essential to transduction in sensory hair cells.

Animals↗
PubMed1991

Monoclonal antibodies to inner ear antigens: I. Antigens expressed by supporting cells of the guinea pig cochlea.

Murine monoclonal antibodies against guinea pig cochlear epithelium were generated with the goal of identifying cochlea-specific antigens and elucidating their function. To compensate for the limited amount of cochlear tissue, intrasplenic immunization was used. Hybridoma supernatants were screened by ELISA for antibody production and for binding to homogenates from cochlea, liver, lung, kidney and brain. Hybrids producing antibody to cochlea were subcloned and tested immunocytochemically against frozen sections and surface preparations of paraformaldehyde-fixed cochlear tissue. KHRI-1, a low titer IgM antibody stained only Hensen cells. KHRI-2, also an IgM antibody, stained tectorial membrane, cells of the spiral limbus, cells bordering the space of Nuel, Hensen cells and the root cells of the spiral prominence. KHRI-3, an IgG1 antibody, stained the phalangeal processes of outer pillar cells and the apical portion of phalangeal processes of Deiters' cells in a distinctive wine goblet pattern on surface preparations. KHRI-3 antibody also reacted with peripheral nerves and pia mater of brain in unfixed frozen sections but the antigenic site was not stable to fixation in contrast to the epitope detected in the cochlea. In Western blots of detergent extracts from cochlea KHRI-3 stained a broad tissue-specific band of Mr 70-75 kDa; a narrower band of Mr 68-70 kDa was identified by KHRI-3 in extracts of tongue and brain. KHRI-1 and KHRI-2 did not detect any proteins in Western blots. The monoclonal antibodies KHRI-1, -2, and -3 which define epitopes expressed by discrete populations of supporting cells in the inner ear should be useful in characterizing the nature and function of cellular structures in the cochlea.

Animals↗
PubMed1990

[Subjective and objective voice assessment following partial resection of the larynx].

There is no generally accepted, standardized approach for evaluation of voice quality and of intelligibility after partial laryngectomy. A voice evaluation which considers some aspects of voice quality is possible by assessing physical and acoustic voice parameters. But this approach does not consider how the patient subjectively assesses his postoperatively altered voice and how the patient believes he is understood by various communication partners. In this study objective and subjective variables of the voice quality of 32 patients with partial laryngectomies were measured. First, selected physical and acoustic variables of voice quality were quantified. Second, subjective criteria of voice quality and of intelligibility were assessed by a questionnaire. A significant correlation between variables of objective and subjective voice quality was found. The maximum vocal intensity, the maximum pitch, and the intensity range correlated significantly with the subjective assessment of intelligibility. No relationship was found between the acoustic variables and the subjectively perceived degree of vocal disability.

Humans↗