Exploratory tympanotomy in sudden sensorineural hearing loss for the identification of a perilymphatic fistula - retrospective analysis and review of the literature.

OBJECTIVE: The diagnostic value of exploratory tympanotomy in sudden sensorineural hearing loss remains controversial. This study and review were performed to identify the incidence of perilymphatic fistula in patients with sudden sensorineural hearing loss. The effectiveness of tympanotomy for sealing of the cochlear windows in cases with perilymphatic fistula was evaluated. METHODS: A search in common databases was performed. Overall, 5034 studies were retrieved. Further, a retrospective analysis on 90 patients was performed. RESULTS: Eight publications dealing with tympanotomy in patients with sudden sensorineural hearing loss were identified. In 90 patients diagnosed with sudden sensorineural hearing loss and undergoing exploratory tympanotomy, 10 patients (11 per cent) were identified with a perilymphatic fistula, and this corresponds to the results obtained from our review (13.6 per cent). CONCLUSION: There was no significant improvement after exploratory tympanotomy and sealing of the membranes for patients with a definite perilymphatic fistula.

Development of a Novel Imaging Agent for Determining Albumin Uptake in Solid Tumors.

PURPOSE: The purpose of this study was to investigate the albumin-binding compound 111In-C4-DTPA as an imaging agent for the detection of endogenous albumin accumulation in tumors. METHODS: 111In-C4-DTPA was injected in healthy nude mice for pharmacokinetic and biodistribution studies (10 min, 1, 6, 24, and 48 h, n = 4) and subsequently in tumor-bearing mice for single-photon emission computed tomography/X-ray-computed tomography (SPECT/CT) imaging studies. Four different human tumor xenograft models (LXFL529, OVXF899, MAXFTN401, and CXF2081) were implanted subcutaneously unilaterally or bilaterally (n = 4-8). After intravenous administration of 111In-C4-DTPA, SPECT/CT images were collected over 72 h at 4-6 time points. Additionally, gamma counting was performed for the blood, plasma, lungs, heart, liver, spleen, kidneys, muscle, and tumors at 72 h post-injection. RESULTS: 111In-C4-DTPA bound rapidly to circulating albumin upon injection, and the radiolabeled albumin conjugate thus formed was stable in murine and human serum. SPECT/CT images demonstrated a time-dependent uptake with a maximum of 2.7-3.8% ID/cm3 in the tumors at approximately 24 h post-injection and mean tumor/muscle ratios in the range of 3.2-6.2 between 24 and 72 h post-injection. The kidneys and bladder were the predominant elimination organs. Gamma counting at 72 h post-injection showed 1.3-2.5% ID/g in the tumors and mean tumor/muscle ratios in the range of 4.9-9.4. CONCLUSION: 111In-C4-DTPA bound rapidly to circulating albumin upon injection and showed time-dependent uptake in the tumors demonstrating a potential for clinical application as a companion imaging diagnostic for albumin-binding anticancer drugs.

Scanning laser optical tomography in a neuropathic mouse model : Visualization of structural changes.

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wild-type mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wild-type mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.

[Scanning laser optical tomography in a neuropathic mouse model : Visualization of structural changes. German version]. / Scannende laseroptische Tomographie in einem neuropathischen Mausmodell : Visualisierung von strukturellen Veränderungen.

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wildtype mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wildtype mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.

[Reactions in the organ of Corti to electrical stimulation : StED technology for detecting changes]. / Reaktionen im Corti-Organ auf elektrische Stimulation : StED-Technologie zum Nachweis von Veränderungen.

Increasing numbers of cochlear implant patients have residual hearing. Despite surgical and pharmacological efforts to preserve residual hearing, a significant number of these patients suffer a late, unexplained loss of residual hearing. Surgical trauma can be excluded as the cause. To investigate this phenomenon and because cells in their native environment react differently to stimuli (such as electrical current) than isolated cells, whole-organ explants from cochleae may be a better model. For early detection of synaptic changes in the organ of Corti, a high-resolution microscopic technique such as stimulated emission depletion (StED) can be used. The aim of this study was establishment of a qualitative and quantitative technique to determinate changes in the organ of Corti and its synapses after electrical stimulation. Explanted organs of Corti from postnatal rats (P2-4) were cultured on a coverslip for 24 h and subsequently exposed to biphasic pulsed electrical stimulation (amplitude 0.44-2.0 mA, pulse width 400 µs, interpulse delay 120 µs, repetition 1 kHz) for another 24 h. For visualization, the cytoskeleton and the ribbon synapses were stained immunocytochemically. For an early detectable response to electrical stimulation, the number of synapses was quantified. Organs of Corti without electrical stimulation served as a reference. Initial research has shown that electrical stimulation can cause changes in ribbon synapses and that StED can detect these alterations. The herein established model could be of great importance for identification of molecular changes in the organ of Corti in response to electrical or other stimuli.

Biological therapies in otology.

Hearing loss is present in millions of people worldwide. Current treatment for patients with severe to profound hearing loss consists of cochlear implantation. Providing the cochlear nerve is intact, patients generally benefit greatly from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. Ongoing research in cell transplantation and gene therapy promises to lead to new developments that will improve the function of cochlear implants. Translation of these experimental approaches is presently at an early stage. This review focuses on the application of biological therapies in severe hearing loss and discusses some of the barriers to translating basic scientific research into clinical reality. We emphasize the application of these novel therapies to cochlear implantation.

[Biological therapies in otology. German version]. / Biologische Therapien in der Otologie.

Millions of people worldwide suffer from hearing loss. Current treatment for patients with severe to profound hearing loss consists of cochlear implants. Providing the cochlear nerve is intact, patients generally benefit enormously from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. New therapeutic concepts based on cell transplantation and gene therapy are developing rapidly, at least in the research sector. Compared to the wealth of basic research available in this area, translation of these new experimental approaches into clinical application is presently at a very early stage. The current review focuses on translatable treatment concepts and discusses the barriers that need to be overcome in order to translate basic scientific research into clinical reality. Furthermore, the first examples of clinical application of biological therapies in severe hearing loss are presented, particularly in connection with cochlear implants.

Polymer Coatings of Cochlear Implant Electrode Surface - An Option for Improving Electrode-Nerve-Interface by Blocking Fibroblast Overgrowth.

Overgrowth of connective tissue and scar formation induced by the electrode array insertion increase the impedance and, thus, diminish the interactions between neural probes as like cochlear implants (CI) and the target tissue. Therefore, it is of great clinical interest to modify the carrier material of the electrodes to improve the electrode nerve interface for selective cell adhesion. On one side connective tissue growth needs to be reduced to avoid electrode array encapsulation, on the other side the carrier material should not compromise the interaction with neuronal cells. The present in vitro-study qualitatively and quantitatively characterises the interaction of fibroblasts, glial cells and spiral ganglion neurons (SGN) with ultrathin poly(N,N-dimethylacrylamide) (PDMAA), poly(2-ethyloxazoline) (PEtOx) and poly([2-methacryloyloxy)ethyl]trimethylammoniumchlorid) (PMTA) films immobilised onto glass surfaces using a photoreactive anchor layer. The layer thickness and hydrophilicity of the polymer films were characterised by ellipsometric and water contact angle measurement. Moreover the topography of the surfaces was investigated using atomic force microscopy (AFM). The neuronal and non-neuronal cells were dissociated from spiral ganglions of postnatal rats and cultivated for 48 h on top of the polymer coatings. Immunocytochemical staining of neuronal and intermediary filaments revealed that glial cells predominantly attached on PMTA films, but not on PDMAA and PEtOx monolayers. Hereby, strong survival rates and neurite outgrowth were only found on PMTA, whereas PDMAA and PEtOx coatings significantly reduced the SG neuron survival and neuritogenesis. As also shown by scanning electron microscopy (SEM) SGN strongly survived and retained their differentiated phenotype only on PMTA. In conclusion, survival and neuritogenesis of SGN may be associated with the extent of the glial cell growth. Since PMTA was the only of the polar polymers used in this study bearing a cationic charge, it can be assumed that this charge favours adhesion of both glial cells and SG neurons glial cells and SGN.

Prevalence and audiological profiles of GJB2 mutations in a large collective of hearing impaired patients.

Mutations in the GJB2 gene are known to represent the commonest cause of hereditary and congenital hearing loss. In this study, a complete sequencing of the GJB2 gene in a cohort of 506 patients from a single, large cochlear implant program in Europe was performed. Audiological testing for those patients who could actively participate was performed using pure tone audiometry (PTA). Those unable to undergo PTA were measured using click-auditory brainstem response (ABR). Data analysis was performed to determine genotype-phenotype correlations of the mutational status vs. audiological profiles and vs. age at the time of presentation. An overall prevalence of biallelic mutations of 13.4% was found for the total collective. When subsets of younger patients were examined, the prevalence increased to 27% of those up to age 18 and 35% of those up to age 5 at the time of testing, respectively. This increase was found to be highly significant (p < 0.001). Analysis of the mean PTA thresholds revealed a strong correlation between allele combination status and mean PTA (p = 0.021). The prevalence of simple heterozygotes was found to be approximately 10.1%, which is around 3.3 times the value expected in the general population. As GJB2 follows a recessive pattern of inheritance, the question arises as to why such a large fraction of simple heterozygotes was observed among the hearing impaired patients included in this study.

High-frequency jet ventilation for endolaryngotracheal surgery--chart review and procedure analysis from the surgeon's and the anaesthesiologist's point of view.

OBJECTIVE: High-frequency jet ventilation (HFJV) arose as a ventilation alternative in laryngotracheal surgery as it offers the surgeon a better overview and more space for microsurgical manipulations. On the contrary, anaesthesiologic monitoring is limited and (relative) contraindications exist. The aim of this study was to evaluate the procedure. Contraindications and limitations are discussed from the surgeon's and the anaesthesiologist's point of view, and relevant aspects of oncologic surgery are identified. DESIGN: Retrospective chart review and analysis of clinical experiences. SETTING: University Teaching hospital. PATIENTS AND MAIN OUTCOME MEASURES: Eighty adult patients (97 cases) treated at our institution between June 2012 and September 2013 were included. HFJV was performed using thin, subglottically placed catheters. The analysis focuses on complications and practical steps. RESULTS: Indications were benign (63%) and malignant pathologies (37%). The CO2 laser was used in 34 cases (35%). The mean operating time averaged 53 min (3-404 min) and the mean duration of anaesthesia was 81 min (16-438 min). Two thirds of the operated patients had a body mass index higher than 25 kg/m(2) . Eighty-four per cent were classified as ASA I and II according to the American Society of Anesthesiologists. All pathologies could well be exposed by the surgeon. Two reversible desaturations to 70% were documented. In another case, emergency re-intubation was necessary as the saturation dropped below 50%. In 8 (8%) cases, elective re-intubation to conventional tubes was performed during the course of the operation as HFJV did not establish optimal oxygenation conditions. No severe intra-operative bleeding was observed. CONCLUSIONS: High-frequency jet ventilation represents a safe ventilation approach for laryngotracheal surgery in experienced hands. Due to the better overview, it offers a better orientation on anatomical structures and on the pathology. Special attention has to be laid on obesity, reflux and cardiopulmonary diseases. However, individual decisions can be made under consideration of all co-morbidities. A close pre- and intra-operative interdisciplinary work up is required.

An optimized protocol for human M2 macrophages using M-CSF and IL-4/IL-10/TGF-ß yields a dominant immunosuppressive phenotype.

Monocytes are highly abundant circulatory effector cells and play a vital role in driving or resolving inflammatory processes depending on their activation phenotype. We investigated and compared a panel of polarization protocols of blood-derived monocytes to achieve a stable, optimal and effective regimen for in vitro induction of immunosuppressive human macrophages, evaluating their surface receptor expression, cytokine profile, scavenging function and ability to suppress T-cell proliferation. Importantly, we assessed the effect of copolarization or secondary pro-inflammatory stimulation of a primary anti-inflammatory activation phenotype. A combination of IL-4/IL-10/TGF-ß yielded a relatively stable and dominant immunosuppressive phenotype characterized by higher IL-10 production and down-regulated TNF-α, IL-6, CD86, CD274 and MHC II expression. Functionally, IL-4/IL-10/TGF-ß-stimulated macrophages (M2) had a potent deactivating effect on a subsequent pro-inflammatory LPS/IFNγ-activated macrophage (M1) stimulation and significantly suppressed T-cell proliferation. Monocytes derived from patients with chronic inflammatory diseases could be induced to be anti-inflammatory using this protocol. Pre-differentiation with GM-CSF or M-CSF was further demonstrated to enhance final M1/M2 activation status. Our findings indicate a robust polarization protocol for generation of specific immunosuppressive human monocyte-derived macrophages.

In vivo evaluation of a novel albumin-binding prodrug of doxorubicin in an orthotopic mouse model of prostate cancer (LNCaP).

PSA, which is overexpressed in prostate carcinoma, represents a molecular target for selectively releasing an anticancer agent from a prodrug formulation. In this study, we report on the in vivo antitumor efficacy of an efficacious albumin-binding prodrug of doxorubicin (PSA9) that incorporates p-aminobenzyloxycarbonyl (PABC) as a self-immolative spacer in addition to the heptapeptide, Arg-Ser-Ser-Tyr-Tyr-Ser-Leu, which serves as a substrate for PSA. The prodrug is cleaved very efficiently by PSA releasing H-Ser-Leu-PABC-doxorubicin and subsequently doxorubicin in PSA-positive cell lysates and prostate tumor homogenates as the final cleavage product. PSA9 at 3 × 6 mg kg(-1) doxorubicin equivalents (intravenous) was compared with conventional doxorubicin at equitoxic doses (at 3 × 3 mg kg(-1); intravenous) in an orthotopic mouse model of prostate cancer using LNCaP lentiviral luciferase-neomycin cells transduced with luciferase. Whereas doxorubicin did not show any efficacy against the primary tumor or metastases, the prodrug reduced the primary tumor by 30-50% and circulating PSA levels, and in addition, showed a pronounced reduction in lung and bone metastases by ∼77% and ∼96%, respectively, and a positive trend regarding the activity against liver and lymph-node metastases compared with control and doxorubicin-treated animals. The incorporation of PABC as a self-immolative spacer together with a PSA substrate demonstrates superior antitumor effects over doxorubicin attributed to an efficient cleavage by PSA releasing doxorubicin as the final active agent in prostate tumor homogenates. Using this approach for developing effective prodrugs against prostate cancer, is worthy of further preclinical optimization.

Prodrugs of anthracyclines in cancer chemotherapy.

Designing and developing truly tumor-specific prodrugs remains a challenge in the field of cancer chemotherapy. Active targeting strategies, on the one hand, aim at exploiting membrane-associated receptors or antigens for drug delivery; on the other hand, the enhanced vascular permeability and retention of macromolecules in tumor tissue substantiates the concept of passive targeting. Consequently, research efforts have concentrated on conjugating anticancer agents with a wide spectrum of carriers including antibodies, peptides, serum proteins, and synthetic polymers. Conversely, low-molecular weight prodrugs of anticancer agents have been developed that do not bear an active or passive targeting moiety, but are activated by tumor-associated enzymes at the tumor site. Anthracyclines probably represent the class of anticancer agents that has been most widely used for the development of prodrugs. This overview gives an update of the various low- and high-molecular weight prodrugs of anthracyclines, e.g. with antibodies, peptides, carbohydrates, serum proteins or synthetic polymers, that have been developed over the past 20 years and that exemplify the salient features of a respective drug delivery system. A detailed description will be dedicated to anthracycline prodrugs that have reached an advanced stage of preclinical testing or that have entered clinical trials.

[Paediatric cochlear implantation in the first year of life: preliminary results]. / Kochleaimplantation bei Kindern im 1. Lebensjahr: Vorläufige Ergebnisse.

BACKGROUND: The success of cochlear implants in children was followed by a stepwise reduction in age at time of surgery. As a result of newborn hearing-screening (NHS) and the reliable audiologic diagnostic procedure, the question is raised as to whether an implantation before the age of 1 year is effective and safe in terms of surgery and rehabilitation. METHOD AND PATIENTS: This retrospective study included 27 children implanted before the age of 1 year (Gr. 1) and 89 children implanted between the age of 1 and 2 years (Gr. 2). Patient related data were analysed for individual history, surgery, rehabilitation and speech understanding. RESULTS: The incidence of complications was not increased in Gr. 1. The fitting of a speech processor was effective and uneventful in all children. The development of hearing and speech understanding showed better results after 2 years in Gr. 1. This development is more obvious for absolute age and not to rehabilitation time. CONCLUSION: In order to achieve an optimal timing for the development of speech understanding, cochlear implantation should be performed before the age of 2 years. This study revealed no additional risks for children in Gr. 1, but the development of speech understanding was better. As a consequence, cochlear implantation should be considered for very young children with an identified bilateral profound hearing loss.