The influence of cholesterol on the motility of cochlear outer hair cells and the motor protein prestin.

CONCLUSIONS: We provide evidence that cholesterol reduces electromotility in a dose-dependent matter. The data show that cholesterol modulates electromotility mainly by influencing the motor protein prestin, less by affecting the passive membrane properties. OBJECTIVES: Elevated serum cholesterol is linked to inner ear disorders and may influence hearing by altering membrane properties of outer hair cells (OHCs) and by affecting the motor protein prestin. In this study we wanted to determine whether cholesterol modulates the electromotility of OHCs and if this modulation results from effects on the membrane properties or on the motor protein prestin. MATERIALS AND METHODS: The motile responses of 12 isolated OHCs were investigated at increasing concentrations of 0, 0.1, and 1 mM extracellular cholesterol using the patch clamp technique and continuous video image analysis. To study effects on prestin, experiments were performed in 12 cells with half activated protein function and concentrations of 0 and 1 mM cholesterol. RESULTS: Cholesterol at a concentration of 0.1 mM had no effect on motility. A concentration of 1 mM reduced maximal evoked shortening significantly by 29% in the depolarizing and by 9% in the hyperpolarizing direction. Investigating half activated motor proteins, 1 mM cholesterol reduced movements significantly by 18%, elongations decreased nonsignificantly by 5%.

[Persistent pharyngeocutaneous fistula after transcervical resection of a diverticulum of the hypopharynx]. / Persistierende pharyngokutane Fistel nach Resektion eines Hypopharynxdivertikels.

CASE: A 26-year-old white male patient had undergone resection of a diverticulum of the hypopharynx and myotomy of the cricopharyngeal muscle elsewhere. A transcervical approach had been chosen owing to the presence of an arteria lusoria and the associated risk of vessel injury. The patient had subsequently had recurrent fistulas through the skin incision, which had not resolved despite four further operations. He presented in our department with significant weight loss and persistent retrosternal pain. Esophageal manometry revealed that resting muscle tone in the upper esophageal sphincter was still significantly elevated. Assuming that the earlier myotomy had not been completely successful, we decided to complete this operation as revision surgery. The pharynx was closed with a running suture using the Conley technique. The fistula healed, and there were no further recurrences. CONCLUSION: Complete and careful dissection of all muscle fibers back to the mucosa is essential, as well as complete removal of the diverticulum if this operation is to be successful when performed by the transcutaneous approach. Recurrent diverticula are not the only possible complication; persistent pharyngeocutaneous fistulas can also arise.

[Fibrinogen/LDL apheresis for treatment of sudden hearing loss: an observational study on 152 patients]. / H.E.L.P.-Apherese bei der Behandlung des Hörsturzes: Eine Anwendungsbeobachtung an 152 Patienten.

Disturbances of cochlear microcirculation are among the most discussed causes of sudden sensorineural hearing loss. Increased levels of cholesterol and fibrinogen seem to act as risk factors for inner ear disorders. Fibrinogen/LDL apheresis greatly reduces the concentration of plasma fibrinogen thus leading to improved cochlear blood flow. In a retrospective case series remission rates of 152 patients suffering from sudden sensorineural hearing loss and resistant to former treatment were investigated after treatment with a single apheresis. Complete remission was reported in 11% of patients, partial remission in 43%. 37% had no change of hearing threshold and 2% reported a decrease in hearing. Rates of complete remissions decreased from 22% within the first 2 weeks after onset of hearing loss to 14% after 6 weeks. In the same period of time rates of partial remissions decreased from 33% to 13%. The present study shows that apheresis achieved complete or partial remission in 54% of patients even after unsuccessful treatment with another therapy and the therapeutic window lies by approximately 6 weeks.

Subpixel tracking for the analysis of outer hair cell movements.

CONCLUSION: Videomicroscopy with subpixel analysis is an excellent system for quantification of outer hair cell (OHC) movements. The resolution of a few nanometers is accurate enough to show induced differences of electromotility. OBJECTIVE: Electromotility of OHCs is a voltage-dependent process resulting from a membrane protein named prestin. Voltage sensitivity is conferred to prestin by intracellular anions. Reduction of these anions reduces electromotility. Videomicroscopy and subpixel tracking combine video-based analysis with a resolution of few nanometers. The aim of this study was to show the feasibility of a system for quantification of OHC movements. MATERIALS AND METHODS: Electromotility was investigated under normal and reduced intracellular chloride conditions. Cells were stimulated by the patch-clamp technique. Voltage steps were 500 ms long, ranging from -170 to +30 mV in 10 mV steps. RESULTS: As in previous studies our results show the following. The direction of OHC movement depends on the polarity of voltage steps, length changes are not equal for symmetrical voltage steps of opposite polarity, average shortening for a depolarizing step (-70 mV to +30 mV) is about 13 nm/mV. Hyperpolarization (-70 mV to -170 mV) on average evokes elongations of about 3 nm/mV. Half maximal chloride concentration reduces motility by 14%; half maximal electromotility is reached by a 94% reduction of chloride.

Intratympanic treatment of acute acoustic trauma with a cell-permeable JNK ligand: a prospective randomized phase I/II study.

OBJECTIVES: Intratympanic administration of a cell-permeable JNK ligand has been shown to prevent hearing loss after acute acoustic trauma in animal models. CONCLUSIONS: Functional and morphological analysis of the treated ears revealed that AM-111 had an excellent otoprotective effect, even when administered hours after the noise exposure. Blocking the signal pathway with D-JNKI-1 is therefore a promising way to protect the morphological integrity and physiological function of the inner ear in various conditions involving acute sensorineural hearing loss. SUBJECTS AND METHODS: For the first application of AM-111 in humans, we organized a clinical phase I/II trial in patients with acute acoustic trauma after exposure to firecrackers in Berlin and Munich on New Year's Eve 2005/2006. We randomly selected 11 patients for intratympanic treatment with AM-111 at a concentration of 0.4 mg/ml or 2 mg/ml within 24 h after noise exposure. Pure tone audiometry and otoacoustic emissions were assessed before treatment and on days 3 and 30 thereafter. RESULTS: Based on clinical experience and on a calculation using an empirically derived exponential hearing recovery function AM-111 seems to have had a therapeutic effect. A total of 13 adverse events were reported in 5 study participants. None of the adverse events were serious or severe.

Studies on the immunogenicity of hCEA in a transgenic mouse model.

BACKGROUND AND AIMS: Immunization protocols in mice have shown that the tumor-associated antigen hCEA could be a target for active immunization; however, human CEA is foreign to mice. Success may depend in part on a simple anti-xenoresponse. Using hCEA-transfected syngeneic tumor cells in hCEA-transgenic mice should bypass this problem and allow testing for new vaccination strategies. MATERIALS AND METHODS: We established a hCEA transgenic model of the haplotype H2(d), which may differ from other haplotypes in cytokine production and in effectiveness of antigen presentation, and tested two vaccination protocols in wild-type and transgenic mice. RESULTS: Syngeneic wild-type mice built up an immune response with high antibody titers; only 65% of animals developed solid tumors after tumor challenge. In contrast, hCEA-transgenic mice developed no antibody response and accepted the tumor in more than 90% of cases, thus demonstrating the role of human CEA as a foreign antigen. Accordingly, active immunization using tumor lysate or lymphocytes loaded with hCEA resulted in a CTL response and tumor-rejection in up to 80% of wild-type mice. hCEA-transgenic mice could be induced with both immunization protocols to build up a CTL response, although the number of CTL were much lower and the cytotoxic response weaker than in wild-type mice. In vivo hCEA-transgenic mice rejected hCEA-positive tumors only after immunization with the tumor lysate in about 60% whereas there was no rejection of tumors after immunization with the human hCEA-loaded autologous lymphocytes. CONCLUSION: The findings clearly show the importance of transgenic models when testing the effects of immunization towards human tumor associated antigens such as hCEA because results differ in wild-type and transgenic mice.