Annelies Schrott-Fischer

Carbon dots for copper detection with down and upconversion fluorescent properties as excitation sources.

Carbon dots were synthesized by a simple and green strategy for selective and sensitive Cu(2+) ion detection using both down and upconversion fluorescence. These fluorescent nanosensors show low cytotoxicity and are applied for intracellular sensing and imaging of Cu(2+) in biological systems.

Human cochlea: anatomical characteristics and their relevance for cochlear implantation.

This is a review of the anatomical characteristics of human cochlea and the importance of variations in this anatomy to the process of cochlear implantation (CI). Studies of the human cochlea are essential to better comprehend the physiology and pathology of mans hearing. The human cochlea is difficult to explore due to its vulnerability and bordering capsule. Inner ear tissue undergoes quick autolytic changes making investigations of autopsy material difficult, even though excellent results have been presented over time. Important issues today are novel inner ear therapies including CI and new approaches for inner ear pharmacological treatments. Inner ear surgery is now a reality, and technical advancements in the design of electrode arrays and surgical approaches allow preservation of remaining structure/function in most cases. Surgeons should aim to conserve cochlear structures for future potential stem cell and gene therapies. Renewal interest of round window approaches necessitates further acquaintance of this complex anatomy and its variations. Rough cochleostomy drilling at the intricate “hook” region can generate intracochlear bone‐dust‐inducing fibrosis and new bone formation, which could negatively influence auditory nerve responses at a later time point. Here, we present macro‐ and microanatomic investigations of the human cochlea viewing the extensive anatomic variations that influence electrode insertion. In addition, electron microscopic (TEM and SEM) and immunohistochemical results, based on specimens removed at surgeries for life‐threatening petroclival meningioma and some well‐preserved postmortal tissues, are displayed. These give us new information about structure as well as protein and molecular expression in man. Our aim was not to formulate a complete description of the complex human anatomy but to focus on aspects clinically relevant for electric stimulation, predominantly, the sensory targets, and how surgical atraumaticity best could be reached. Anat Rec, 2012.

High‐resolution X‐ray tomography of the human inner ear: synchrotron radiation‐based study of nerve fibre bundles, membranes and ganglion cells

The combination of osmium tetroxide staining and high‐resolution tomographic imaging using monochromatic X rays allows visualizing cellular structures of the human inner ear, that is, the organ of Corti, the stria vascularis and further soft tissues of the membranous labyrinth, in three‐dimensional space with isotropic micrometre resolution. This approach permits to follow the course of nerve fibre bundles in a major part of the specimen and reveals the detailed three‐dimensional arrangement of individual ganglion cells with distinct nuclei by means of X‐ray tomography for the first time. The non‐destructive neuron cell counting in a selected volume of 125 μm × 800 μm × 600 μm = 0.06 mm3 gives rise to the estimate that 2000 ganglion cells are present along 1 mm organ of Corti.

Morphology of bony tissues and implants uncovered by high-resolution tomographic imaging

Abstract Synchrotron radiation-based micro computed tomography contributes to the increasing demand for uncovering non-destructively the microscopic morphology of bony tissues and their interface regions with implants using isotropic spatial resolution in three-dimensional space. Using the microscopic ring structure of otoliths, the coherence-related interplay between density resolution and spatial resolution is demonstrated. The monochromatised, highly intense synchrotron radiation allows analysis of the morphology of arthritic joints without significant beam-hardening artefacts in a quantitative manner. It further enables intensity-based segmentation of metallic implants within bone and thereby to quantitatively study the bone morphology around different kinds of middle and inner ear implants. This knowledge permits improving medical interventions and optimising the implants design with respect to surface modification, mechanical properties, and shape.

Possible role of gap junction intercellular channels and connexin 43 in satellite glial cells (SGCs) for preservation of human spiral ganglion neurons : A comparative study with clinical implications.

Human spiral ganglion (SG) neurons show remarkable survival properties and maintain electric excitability for a long time after complete deafness and even separation from the organ of Corti, features essential for cochlear implantation. Here, we analyze and compare the localization and distribution of gap junction (GJ) intercellular channels and connexin 43 (Cx43) in cells surrounding SG cell bodies in man and guinea pig by using transmission electron microscopy and confocal immunohistochemistry. GJs and Cx43 expression has been recognized in satellite glial cells (SGCs) in non-myelinating sensory ganglia including the human SG. In man, SG neurons can survive as mono-polar or “amputated” cells with unbroken central projections following dendrite degeneration and consolidation of the dendrite pole. Cx43-mediated GJ signaling between SGCs is believed to play a key role in this “healing” process and could explain the unique preservation of human SG neurons and the persistence of cochlear implant function.

Activated and non-activated eosinophils in patients with chronic rhinosinusitis.

Nasal polyps develop out of an oedematous swelling of the mucous membrane, which is probably a localized mediator-dependent reaction of the mucous membrane in the lamina propria. Among other things, eosinophil cationic protein (ECP) is released from activated eosinophils. In previous studies, ECP was considered as measuring the degree of allergic dermatological illnesses and therapy was given accordingly. A group of 54 patients with massive polyposis requiring functional endoscopic sinus surgery was examined. After surgery they were treated with local and systemic cortisone. Polypous tissue samples were collected and counted for the number and ratio of activated and non-activated eosinophils, and the serum titre of ECP was measured simultaneously using a fluoroimmunoassay (test kit, Kabi Pharmacia, Sweden). The aim of the study was to evaluate the activity of the disease and to gain hints for a specific therapy. The presence of these eosinophils was demonstrated by immunohistochemical methods, using EG1 antibodies against non-activated and EG2 antibodies against activated (i.e. secreted form of ECP) eosinophils. Depending on the duration of treatment with systemic and local corticosteroids, there was a considerable decrease in activated eosinophils and the level of serum ECP. Consequently, cortisone can be applied in the treatment of eosinophilic nasal polyps. As the number of activated eosinophils in the tissue is an indicator for the activity of the chronic inflammation it can be deduced from our study that local and/or systemic cortisone application successfully stops the growth of eosinophilic nasal polyps. The number and ratio of activated and non-activated eosinophils seem to be reliable indicators for the activity of chronic polyposis.

Structure and locomotion of adult in vitro regenerated spiral ganglion growth cones - A study using video microscopy and SEM

Neuronal development and neurite regeneration depends on the locomotion and navigation of nerve growth cones (GCs). There are few detailed descriptions of the GC function and structure in the adult auditory system. In this study, GCs of adult dissociated and cultured spiral ganglion (SG) neurons were analyzed in vitro utilizing combined high resolution scanning electron microscopy (SEM) and time lapse video microscopy (TLVM). Axon kinesis was assessed on planar substratum with growth factors BDNF, NT-3 and GDNF. At the nano-scale level, lamellipodial abdomen of the expanding GC was found to be decorated with short surface specializations, which at TLVM were considered to be related to their crawling capacity. Filopodia were devoid of these surface structures, supporting its generally described sensory role. Microspikes appearing on lamellipodia and axons, showed circular adhesions, which at TLVM were found to provide anchorage of the navigating and turning axon. Neurons and GCs expressed the DCC-receptor for the guidance molecule netrin-1. Asymmetric ligand-based stimulation initiated turning responses suggest that this attractant cue influences steering of GC in adult regenerating auditory neurites. Hopefully, these findings may be used for ensuing tentative navigation of spiral ganglion neurons to induce regenerative processes in the human ear.

Murine malaria is associated with significant hearing impairment

BackgroundPlasmodium falciparum malaria has been suspected to cause hearing loss. Developmental, cognitive and language disorders have been observed in children, surviving cerebral malaria. This prospective study aims to evaluate whether malaria influences hearing in mice.MethodsTwenty mice were included in a standardized murine cerebral malaria model. Auditory evoked brainstem responses were assessed before infection and at the peak of the illness.ResultsA significant hearing impairment could be demonstrated in mice with malaria, especially the cerebral form. The control group did not show any alterations. No therapy was used.ConclusionThis suggests that malaria itself leads to a hearing impairment in mice.

Super-resolution structured illumination fluorescence microscopy of the lateral wall of the cochlea: the Connexin26/30 proteins are separately expressed in man.

Globally 360 million people have disabling hearing loss and, of these, 32 million are children. Human hearing relies on 15,000 hair cells that transduce mechanical vibrations to electrical signals in the auditory nerve. The process is powered by the endo-cochlear potential, which is produced by a vascularized epithelium that actively transports ions in conjunction with a gap junction (GJ) system. This “battery” is located “off-site” in the lateral wall of the cochlea. The GJ syncytium contains the GJ protein genes beta 2 (GJB2/connexin26 (Cx26)) and 6 (GJB6/connexin30 (Cx30)), which are commonly involved in hereditary deafness. Because the molecular arrangement of these proteins is obscure, we analyze GJ protein expression (Cx26/30) in human cochleae by using super-resolution structured illumination microscopy. At this resolution, the Cx26 and Cx30 proteins were visible as separate plaques, rather than being co-localized in heterotypic channels, as previously suggested. The Cx26 and Cx30 proteins thus seem not to be co-expressed but to form closely associated assemblies of GJ plaques. These results could assist in the development of strategies to treat genetic hearing loss in the future.

Apoptosis of the fibrocytes type 1 in the spiral ligament and blood labyrinth barrier disturbance cause hearing impairment in murine cerebral malaria

BackgroundExperimental murine malaria has been shown to result in significant hearing impairment. Microscopic evaluation of the temporal bones of these animals has revealed regular morphology of the cochlea duct. Furthermore, the known vascular pathologic changes being associated with malaria could not be found. Immunohistochemistry for ICAM1 showed a strong marking in the stria vascularis, indicating a disturbance of the endocochlear potential. The aim of this study was to evaluate the role of apoptosis and the disturbance of the blood labyrinth barrier in the murine malaria associated hearing impairment.MethodsThe temporal bones of seven mice with cerebral malaria-four with hearing impairment, three without hearing impairment-were evaluated with immunohistochemistry for cleaved caspase 3 to detect apoptosis and connexin 26, a gap junction protein being a cornerstone in the endocochlear potassium recirculation. Furthermore five animals with cerebral malaria were treated with Evans blue prior to sacrification to detect disturbances of the blood labyrinth barrier.ResultsCleaved caspase 3 could clearly be detected by immunohistochemistry in the fibrocytes of the spiral ligament, more intensively in animals with hearing impairment, less intensively in those without. Apoptosis signal was equally distributed in the spiral ligament as was the connexin 26 gap junction protein. The Evans blue testing revealed a strong signal in the malaria animals and no signal in the healthy control animals.ConclusionMalfunction of the fibrocytes type 1 in the spiral ligament and disruption of the blood labyrinth barrier, resulting in a breakdown of the endocochlear potential, are major causes for hearing impairment in murine cerebral malaria.