Phosphatidylserine-positive particles in the apical domain of sensory hair cells

Apical membrane recycling has been proposed to be important for normal hair cell function. The current study reports an in vitro work that demonstrates the presence of phosphatidylserine (PS) and PS-positive vesicles labeled by Annexin V in the apical portion of hair cells. The following characteristics of the PS-positive vesicles were noticed using scanning confocal fluorescence microscopy:(1) variable sizes around 200 nm; (2) variable distribution patterns (either uniformly along individual stereocilia in the hair bundle or irregular) in the stereocilia from cell to cell; (3) variable sizes and numbers at locations along the border of the cuticular plate (CP), with a large number of them located at the vestigal kinocilial location; (4) motility with some of the vesicles during the observation period; (5) increase in PS labeling and the number of PS-positive vesicles after loud sound stimulation; and (6) decreased PS labeling and PS-positive vesicle numbers following treatment with LY-294002, a PI3 -kinase inhibitor. These results suggest that the presence of PS-positive vesicles at the apical area of hair cells may be indicative of vesicle shedding or transportation of a protein or rafts.     

Effects of Piezosurgery® on the cochlear outer hair cells

Conclusions. The absence of audiologic side effects highlights the reduced trauma of the piezoelectric cut, demonstrates the superiority of the Piezosurgery® device in terms of safety and protection of anatomical structures and confirms its applicability in all the otologic techniques tested. Objectives. The aim of the present study was to estimate the effect of Piezosurgery® on the cochlea and in particular on the cochlear outer hair cells. Patients and methods. We selected 60 patients with a history of otologic surgery with Piezosurgery®. Before and 6 months after surgery, all the patients underwent the following instrumental examinations: pure-tone audiometry, tympanometry, transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs) and auditory brainstem response (ABR). Results. Piezosurgery® showed its safety on the inner ear and in particular on the cochlear outer hair cells: for each instrumental examination (pure-tone audiometry, tympanometry, TEOAE, DPOAEs and ABR), no patients presented postoperative worsening.     

Regenerated hair cells in the European starling: Are they more resistant to kanamycin ototoxicity than original hair cells?

Previous work from our laboratory [Marean et al. (1993) Hear. Res. 71, 125–136] has shown that a 10 day dose of 200 mg/kg/day kanamycin produced damage to the basal 34% of the starling basilar papilla. We also observed that repeating the dosing schedule following a 4 month survival period resulted in significantly less damage to the regenerated auditory epithelium. The present study investigated whether or not this apparent resistance was the result of a tendency for regenerated hair cells to be less susceptible to kanamycin ototoxicity, or if other, systemic factors may be involved. Eight European starlings were given subcutaneous injections of 200 mg/kg/day kanamycin for 10 days. Serum levels of kanamycin were measured at the time of sacrifice for all birds, and the basilar papillae of all birds were examined by scanning electron microscopy (SEM). Two of these birds (Group 1) were sacrificed immediately following the dosing period. Two of the birds were allowed to survive for 60 days (Group 2). Two of the birds were redosed with 200 mg/kg/day for 10 days after 60 days survival (Group 3). Finally, two birds were redosed with 250 mg/kg/day until serum levels of kanamycin were the same as Group 1 when sacrificed (> 9 μg/ml). The SEM results showed that the regenerated auditory epthelium of the birds dosed a second time sustained less damage compared to previously untreated ears, even though the dosing regimen was the same (Group 3 versus Group 1). The regenerated auditory epethelium of birds dosed a second time sustained the same damage as previously untreated animals when the dosage was increased to attain similar serum levels (Group 4 versus Group 1). These results suggest metabolic changes occur in the starling in response to the initial dose of kanamycin which do not necessarily involve changes in hair cell resistance to ototoxicity.     

Is the clinical application of stem cells within reach?

Welche M?glichkeiten erscheinen realistisch in der Diskussion um den Nutzen von Stammzellen in der Therapie bisher unheilbarer Erkrankungen? Da sich der Stand der Forschung st?ndig wandelt, werden hier neben einem kurzen überblick über die Arten von Stammzellen aktuelle Forschungsergebnisse kritisch besprochen. Die Darstellung ihrer Auswirkungen auf die Therapie der Zukunft und bisheriger M?glichkeiten soll einen Beitrag dazu leisten, dass neue Ergebnisse in das bisher Erreichte eingeordnet werden k?nnen. Priv.-Doz.Dr. Stefan DazertLeitender Oberarzt, HNO-Klinik der Ruhr-Universit?t, St. Elisabeth-Hospital, Bleichstr. 15, 44787 Bochum, E-Mail: stefan.dazert@ruhr-uni-bochum.de     

in vitro differentiation of adipose-derived stem cells into hair cell-like cells in guinea pigs

Objective Adipose-derived stem cells(ADSCs) are suggested to possess a highly plastic ability to differentiate into several specific cell types in addition to adipocyte lineages, including germ layer tissue-specific cell lineages such as chondrocyte, myocyte, neuronal, and osteoblast lineages. The aim of this study is to establish an in vitro culture technique for ADSCs in an adult guinea pig model that facilitate their differentiation into hair cell-like cells. Materials and Methods Cells from inguinal fat pads in adult guinea pigs were cultured with β-mercaptoethanol, RA, Forskorin, Heregulin, bFGF, BDNF and EGF. Cellular differentiation was examined using immunocytochemistry techniques. Results The ADSCs demonstrated hair cell immunophenotypes with expression of epitopes of the hair cell marker protein myosin Ⅶa. Conclusion ADSCs from adult guinea pig adipose tissue can differentiate into hair cell-like cells when cultured in vitro. ADSCs may serve as seed cells for tissue engineering.     

Is uvulopalatopharyngoplasty still an option for the treatment of obstructive sleep apnea?

Uvulopalatopharyngoplasty (UPPP) has been widely described as a surgical option for the treatment of obstructive sleep apnea syndrome. Several studies have demonstrated variable success rates, and different criteria have been used to define success of surgery. The aim of the present study was to assess the efficiency of UPPP by polysomnography and to correlate it to the clinical findings. Also, we correlated to the various studies dealing with this topic, considering the different criteria adopted in each of this. Sixty-four patients were included in the study. The efficiency of surgery for UPPP was analyzed to the variables such as body mass index, age, preoperative polysomnography results and follow-up period. Based on the criteria for postoperative cure, the success rate was 44 %. Younger patients presented a better success rate than older ones. No other correlation was found between clinical findings and UPPP success. UPPP can be curative in some patients, but combination with other treatment modalities must be considered. This should be mentioned to the patients, since in many cases the sites of airway collapse may be multiple and no clinical aspect (except for age) is indicative of good prognosis.     

Technique for the assessment of vestibular compensation--clinical observation/quantitative neuro-otometry?]

PROBLEM: Reliable evaluation of vestibular compensation in indispensable to determine whether labyrinth surgery or vestibular neurectomy is indicated. It is also important for postoperative follow-up. Vestibular compensation can manifest itself differently in distinct frequency ranges. METHOD: Twenty volunteers were examined in five distinct situations of daily vestibular stimulation. Measurement of angular and linear head acceleration was performed using accelerometers fixed on the volunteers' head. A 200 Hz AD fed data to a PC database. FFT was used for data analysis. RESULTS: Stimulus frequency of the vestibular system varies between 0.01 and 2 Hz. Most of the patients suffering from vestibular lesions showed a reduced vestibulo ocular reflex (VOR) below 0.1 Hz. In all cases of unilateral vestibular function loss, there was a correlation between the symptoms during movement and the corresponding frequency range of the distinct motion pattern. Rotatory vestibular pendular testing was used to document vestibular disorders in patients who had normal findings in routine vestibular testing. DISCUSSION: Clinical use of rotatory vestibular pendular testing results must be performed using broad stimulus frequency spectra (0.01-0.06 Hz). This method must be used in preoperative examination before labyrinth surgery as well as in estimating individual tolerance for vestibular stimulation in daily situations.     

How can the cochlear amplifier be realized by the outer hair cells which have nothing to push against?

D-Methionine has recently been advocated as a protectant against cisplatin toxicity. The use of systemic D-methionine as a protector was studied in 58 guinea pigs. Kinetics and distribution of [11CH(3)]D-methionine was analysed by positron emission tomography. Cisplatin and the monohydrated complex of cisplatin was quantified in blood ultrafiltrate using reversed-phase liquid chromatography with post-column derivatisation. Administration of 300 mg/kg of D-methionine caused a 30% decrease in the area under the concentration-time curve (AUC) of cisplatin. The toxic effect of cisplatin was studied after dose adjustment of cisplatin, i.e. with similar cisplatin AUC in the group receiving D-methionine and the saline control group. A significant ototoxic effect, measured as difference in pre- and 96 h post-treatment electrophysiological hearing threshold (auditory brainstem response), was observed at stimulus frequencies of 30 and 20 kHz. There was no difference between the groups in the extent of threshold shift. Quantitative outer hair cell counts showed a similar loss of cells in the two groups. All animals had a significant increase in plasma-creatinine but there was no difference between the groups. The results indicate that protection from cisplatin ototoxicity by systemic D-methionine can be explained by a lowered systemic exposure to the drug.     

Does the geometrical arrangement of the outer hair cell stereocilia perform a fluid-mechanical function?

CONCLUSIONS: Our experiments qualitatively show that the geometrical structure of the inner ear may have the features of a micro-pump. To further substantiate this hypothesis, additional experiments, particularly on in vivo preparations, are needed. OBJECTIVE: To introduce some new ideas about the functional purpose of the geometric arrangement of the outer hair cell stereocilia. Analogies to some recently developed valveless micro-pumps are pointed out. To illustrate these points, comparative experiments were performed using a simplified macro model. METHODS: Specific structures of the organ of Corti were simulated in a partially open, partially closed acrylic tank. This rough approximation allows the visualization of fluid flows that are generated as a result of the relative motions between the tectorial membrane and the reticular lamina. RESULTS: It was shown that the arrangement of the cochlear elements not only forces fluid to flow in a one-way direction, but also generates a fluid stream that flows through the "outlets" between each two V or W formations of stereocilia. These fluid streams are directed towards the inner hair cells.     

Does the geometrical arrangement of the outer hair cell stereocilia perform a fluid-mechanical function?

Conclusions. Our experiments qualitatively show that the geometrical structure of the inner ear may have the features of a micro-pump. To further substantiate this hypothesis, additional experiments, particularly on in vivo preparations, are needed. Objective. To introduce some new ideas about the functional purpose of the geometric arrangement of the outer hair cell stereocilia. Analogies to some recently developed valveless micro-pumps are pointed out. To illustrate these points, comparative experiments were performed using a simplified macro model. Methods. Specific structures of the organ of Corti were simulated in a partially open, partially closed acrylic tank. This rough approximation allows the visualization of fluid flows that are generated as a result of the relative motions between the tectorial membrane and the reticular lamina. Results. It was shown that the arrangement of the cochlear elements not only forces fluid to flow in a one-way direction, but also generates a fluid stream that flows through the “outlets” between each two V or W formations of stereocilia. These fluid streams are directed towards the inner hair cells.     

Is packing of the nose up-to-date ?

BACKGROUND: Generally accepted standards regarding the materials which should be used for packing, how long the packing should be left in place or the indications for nasal packing are lacking. Nasal packing is used primarily to control bleeding in endonasal surgery, to stabilize the cartilaginous and bony skeleton and to prevent synechiae or restenosis. For the latter some authors recommend to pack the nose for several days. We want to prove the acceptance according to time, particularly wether there is an increase in discomfort. PATIENTS: Prospective study in 60 patients who underwent septoplasty and submucosal resection of inferior turbinates (n = 30) or endonasal sinus surgery (n = 30, in 15 cases septoplasty was performed too). The nose was packed for 4 or 5 days. Using a visual analog scale (0 - 10) the patient's condition was examined regarding: stuffy nose, headache, sleeping disorders, overall judgement. RESULTS: In two patients the packing had to be removed early (once because of the development of swelling of the lower lid and cheek; once because of lacking acceptance). The average condition of the remaining 58 patients showed no worsening during time for all 4 features. Analyzing the individual, only two patients (3.5 %) showed continuous increasing of complaints. CONCLUSIONS: According to this investigation, nasal packing for 4 or 5 days is well accepted by most of the patients, if you be able to make clear its sense to the patient. Nevertheless, looking for alternative operative techniques or nasal packing materials is mandatory to improve the patient's comfort postoperatively.     

Is the Trachea a Marker of the Type of Environmental Pollution?

OBJECTIVES/HYPOTHESIS: The differentiated character of changes in the mucous relief of the trachea as induced by air containing pollutants from the wastes of nickel-, mercury-, and cement-producing plants and by Candida albicans occurring in the waste disposal site of a large town are identified. The trachea was chosen because it is the entrance gate for the penetration of polluted air into the lungs. Changes on the trachea influence the character and extent of changes in lungs. STUDY DESIGN: Histological study with Viennese grey strain laboratory rabbits and rats caught directly on an investigated site. METHODS: We present new results of the functional morphology of the respiratory system as the results of scanning and transmission electron microscopy studies that can reveal character and range of damage of mucosal relief of trachea relevant to the functional dynamics of mucociliary clearance. Under physiological conditions this mechanism allows that only respirable dust particles enter the deep respiratory tract. RESULTS: In case of a damaged tracheal relief because of exposure to various aerosols, the functional morphology is changed, which aids in understanding the mechanisms damaging to mucociliary clearance induced by living in heavily polluted areas. CONCLUSION: Understanding of these morphological changes on base of detailed electron microscopic findings sheds new light on elaborating novel diagnostic methods for clinical practice.     

Is electronystagmography of diagnostic value in the elderly?

Is electronystagmography of diagnostic value in the elderly? We aimed to determine the diagnostic value of electronystagmography (ENG) in a community‐based sample of dizzy subjects over 65 years old. A total of 96 asymptomatic controls and 149 dizzy subjects underwent ENG. Clinical diagnoses were made on standardized criteria. ENG results were classed as normal or abnormal, according to reference ranges derived from the controls. Rates of ENG abnormality in different diagnostic categories, sensitivities, specificities and predictive values were calculated. Central vascular disease was common (105 out of 149 subjects); peripheral vestibular disease was not (14). Spontaneous nystagmus had a positive predictive value of 95% for central vascular disease, but was only 18%‐sensitive, and was usually detectable clinically. ENG had no other significant diagnostic value. ENG failed to discriminate dizzy subjects from controls and failed to differentiate various dizziness syndromes. ENG was of no practical value in this community‐derived sample of dizzy elderly subjects.