Alterations in pathogen-specific cellular and humoral immunity associated with acute peripheral facial palsy of infectious origin.

BACKGROUND: Peripheral facial palsy (PFP) is a common neurologic symptom which can be triggered by pathogens, autoimmunity, trauma, tumors, cholesteatoma or further local conditions disturbing the peripheral section of the nerve. In general, its cause is often difficult to identify, remaining unknown in over two thirds of cases. As we have previously shown that the quantity and quality of pathogen-specific T cells change during active infections, we hypothesized that such changes may also help to identify the causative pathogen in PFPs of unknown origin. METHODS: In this observational study, pathogen-specific T cells were quantified in blood samples of 55 patients with PFP and 23 healthy controls after stimulation with antigens from varicella-zoster virus (VZV), herpes-simplex viruses (HSV) or borrelia. T cells were further characterized by expression of the inhibitory surface molecule CTLA-4, as well as markers for differentiation (CD27) and proliferation (Ki67). Pathogen-specific antibody responses were analyzed using ELISA. Results were compared with conventional diagnostics. RESULTS: Patients with PFP were more often HSV-seropositive than controls (p = 0.0003), whereas VZV- and borrelia-specific antibodies did not differ between groups. Although the quantity and general phenotypical characteristics of antigen-specific T cells did not differ either, expression of CTLA-4 and Ki67 was highly increased in VZV-specific T cells of 9 PFP patients, of which 5 showed typical signs of cutaneous zoster. In the remaining 4 patients, a causal relationship with VZV was possible but remained unclear by clinical standard diagnostics. A similar CTLA-4- and Ki67-expression profile of borrelia-specific T cells was also found in a patient with acute neuroborreliosis. DISCUSSION: In conclusion, the high prevalence of HSV-seropositivity among PFP-patients may indicate an underestimation of HSV-involvement in PFP, even though HSV-specific T cell characteristics seem insufficient to identify HSV as a causative agent. In contrast, striking alterations in VZV- and borrelia-specific T cell phenotype and function may allow identification of VZV- and borrelia-triggered PFPs. If confirmed in larger studies, antigen-specific immune-phenotyping may have the potential to improve specificity of the clinical diagnosis.

Immunohistochemistry Reveals TRPC Channels in the Human Hearing Organ-A Novel CT-Guided Approach to the Cochlea.

TRPC channels are critical players in cochlear hair cells and sensory neurons, as demonstrated in animal experiments. However, evidence for TRPC expression in the human cochlea is still lacking. This reflects the logistic and practical difficulties in obtaining human cochleae. The purpose of this study was to detect TRPC6, TRPC5 and TRPC3 in the human cochlea. Temporal bone pairs were excised from ten body donors, and the inner ear was first assessed based on computed tomography scans. Decalcification was then performed using 20% EDTA solutions. Immunohistochemistry with knockout-tested antibodies followed. The organ of Corti, the stria vascularis, the spiral lamina, spiral ganglion neurons and cochlear nerves were specifically stained. This unique report of TRPC channels in the human cochlea supports the hypothesis of the potentially critical role of TRPC channels in human cochlear health and disease which has been suggested in previous rodent experiments.

[Outpatient Antibiotic Prescription Rates and Mastoiditis in Children and Adolescents, Saarland, 2014-2019]. / Ambulante Antibiotika-Verordnungsrate und Mastoiditis-Fälle bei Kindern und Jugendlichen im Saarland, 2014­2019.

BACKGROUND: Infections of the respiratory tract are the main indication for outpatient antibiotic therapy in children and adolescents. In recent years the antibiotic prescription rate (APR) in the pediatric population has decreased significantly. OBJECTIVES: The aim of the retrospective mastoiditis audit in the PaedineSaar network is to investigate the incidence of inpatient acute mastoiditis (AM) in Saarland (2014-2019) regarding to the decreasing APRs in children, as well as to gather data of the clinical course of AM. METHODS: All inpatient AM cases 2014-2019 were analyzed retrospectively from 6 hospitals for pediatrics and/or otorhinolaryngology in Saarland and Trier. Children and adolescents aged 0-17 years and residing in Saarland were included in the study. RESULTS: 2014-2019 53 inpatient treated AM cases have been recorded. During the study period there was no significant increase of AM incidence (mean incidence 2014-2019: 6.1/100,000). 34% (18/53) of the patients received prehospital antibiotic treatment (main indication: acute otitis media (AOM) 15/18, 83%). At least one complication occurred in 30% of the patients (16/53). There was a slight trend to more complications in children without oral antibiotic treatment before admission (14/35 (40%) vs. 2/18 (11%) p=0.056). CONCLUSIONS: The incidence of AM leading to inpatient treatment in children in Saarland did not increase 2014-2019 despite a significant and sustained decline in the outpatient APRs. The results of this audit should be used for the development of a more standardized approach concerning the diagnostics and treatment of children with AM.

Neural Crest Stem Cells in Juvenile Angiofibromas.

The etiology of juvenile angiofibroma (JA) has been a controversial topic for more than 160 years. Numerous theories have been proposed to explain this rare benign neoplasm arising predominately in adolescent males, focusing mainly on either the vascular or fibrous component. To assess our hypothesis of JA's being a malformation arising from neural crest cells/remnants of the first branchial arch plexus, we performed immunohistochemical analyses of neural crest stem cells (NCSC) and epithelial-mesenchymal transition (EMT) candidates. Immunoexpression of the NCSC marker CD271p75 was observed in all investigated JA's (n = 22), mainly around the pathological vessels. Close to CD271p75-positive cells, high MMP3-staining was also observed. Additionally, from one JA with sufficient material, RT-qPCR identified differences in the expression pattern of PDGFRß, MMP2 and MMP3 in MACS®-separated CD271p75positive vs. CD271p75 negative cell fractions. Our results, together with the consideration of the literature, provide evidence that JA's represent a malformation within the first branchial arch artery/plexus remnants deriving from NCSC. This theory would explain the typical site of tumor origin as well as the characteristic tumor blood supply, whereas the process of EMT provides an explanation for the vascular and fibrous tumor component.

Optoacoustically induced auditory brainstem responses in the mouse model enhanced through an absorbing film.

SIGNIFICANCE: Optoacoustic stimulation offers an alternative stimulation strategy for the hearing organ. To serve as the base for a novel auditory prosthesis, the optoacoustic stimulation must be biocompatible and energy-saving. AIM: Enhancing the efficiency of optoacoustic stimulation while reducing the energy input in a suited animal model. APPROACH: Optoacoustically induced auditory brainstem responses (oABRs) were recorded after the pulsed laser irradiation of the tympanic membrane (TM) in mice. The results were compared with the ABRs induced through acoustic click stimulation. In addition, self-adhesive absorbing films were applied on the TM before the optoacoustic stimulation to investigate their effect on the resulting ABRs. RESULTS: Using an absorbing film on the TM during optical stimulation led to considerably enhanced oABR wave I amplitude values compared with the stimulation of the bare TM. When using our stimulation strategy, we induced oABR waves in the 50% to 60% range of the acoustical stimulation reached with 80-dB SPL click stimuli. CONCLUSIONS: The mouse model can be used for certain developmental work for an optoacoustic auditory prosthesis. Using absorbing films on the TM during optical stimulation considerably enhances oABR wave I amplitude. Optimization of the stimulation strategy could further enhance the efficiency within biocompatibility margins.

Wavelength-specific optoacoustic-induced vibrations of the guinea pig tympanic membrane.

SIGNIFICANCE: Optoacoustic-induced vibrations of the hearing organ can potentially be used for a hearing device. To increase the efficiency of such a hearing device, the conversion of the light energy into vibration energy within each type of irradiated tissue has to be optimized. AIM: To analyze the wavelength-dependency of optoacoustic-induced vibrations within the tympanic membrane (TM), and to define the most efficient and best-suited optical stimulation parameters for a novel auditory prosthesis. APPROACH: Single nanosecond laser pulses, continuously tunable in a range of visible to near-infrared, were used to excite the guinea pig TM. The induced vibrations of the hearing organ were recorded at the malleus using a laser Doppler vibrometer. RESULTS: Our results indicate a strong wavelength-dependency of the vibration's amplitude correlating with the superposition of the absorption spectra of the different specific tissue components. CONCLUSIONS: We investigated the spectrum of the vibrations of the hearing organ that were induced optoacoustically within a biological membrane embedded in air, in an animal model. First applications for these results can be envisioned for the optical stimulation of the peripheral hearing organ as well as for research purposes.

[Prospektives Audit des Gentamicin Drug Monitorings in einem Kinderkrebszentrum]. / Prospective Audit of Gentamicin Drug Monitoring Practice in a Pediatric Cancer Center.

BACKGROUND: Many pediatric cancer centers still use Gentamicin as first line combination treatment in patients with fever and neutropenia. Since 2011, our center has implemented a dosing regimen with 250 mg/m2 BSA (max. 10 mg/kg, max. 400 mg) as a single daily infusion according to the German guideline. PATIENTS AND METHODS: In this prospective audit (February 2011 to December 2019), 105 Gentamicin treatment cycles were analyzed in 66 pediatric cancer patients, focusing on adherence to the dosing regimen and the drug monitoring results. RESULTS: Adherence to the dosing regimen was high (89%). In 64% of all cycles, the Cmax (drawn 1 h after the 2nd dose) reached the target of 10-20 µg/ml. Cmax significantly correlated with dosing in mg/m2 BSA (p=0,007), but not with dosing in mg/kg (p=0,366). Age below 6 years did not influence these results. The Gentamicin Ctrough (drawn 8-10 h after the second dose) was < 2 µg/ml in 93% of all cycles without any dose correlation. None of the patients experienced Gentamicin-associated nephrotoxicity. DISCUSSION AND CONCLUSION: This prospective audit of single daily infusion Gentamicin in pediatric cancer patients without impaired renal function elicits the feasibility and safety of the dosing regimen in mg/m2 BSA according to the German guideline. Since indications for first-line gentamicin are limited, a multicenter prospective study would be advantageous to confirm these observations.

Cytotoxicity studies of an optoacoustic stimulation strategy for the development of laser-based hearing aids.

SIGNIFICANCE: Worldwide, ∼460 million people suffer from disabling hearing impairment. Many of these patients are still not sufficiently supplied with currently available auditory technologies. Optical stimulation of the hearing organ offers a promising alternative for a new generation of auditory prostheses. AIM: To assess the biocompatibility margins of our laser pulse amplitude strategy in vitro, we designed a protocol and present the effects on normal human dermal fibroblasts, human chondrocytes, and human osteoblasts. APPROACH: Laser pulses of 532 nm were applied over 120 s using our laser pulse amplitude modulation strategy. We then assessed cell viability and cytotoxicity through fluorescence staining and quantitative polymerase chain reaction-analysis regarding 84 key player-genes for cytotoxicity and stress response. RESULTS: The first in vitro biocompatibility margins for our stimulation parameters applied to cells of the peripheral hearing organ were between 200 and 223 mW (3348 J/cm2). After irradiation with a subphototoxic laser power of 199 mW (2988 J/cm2), only the fibroblasts showed a significant upregulation of GADD45G. CONCLUSION: Further studies are underway to optimize parameters for the optoacoustic stimulation of the auditory system. Our protocol and results on laser-tissue interactions can be useful for translational laser applications in various other irradiated biological tissues.

First biocompatibility margins for optical stimulation at the eardrum via 532-nm laser pulses in a mouse model.

Hearing impairment affects ∼460 million people worldwide. Conservative therapies, such as hearing aids, bone conduction systems, and middle ear implants, do not always sufficiently compensate for this deficit. The optical stimulation is currently under investigation as an alternative stimulation strategy for the activation of the hearing system. To assess the biocompatibility margins of this emerging technology, we established a method applicable in whole-mount preparations of murine tympanic membranes (TM). We irradiated the TM of anesthetized mice with 532-nm laser pulses at an average power of 50, 89, 99, and 125 mW at two different locations of the TM and monitored the hearing function with auditory brainstem responses. Laser-power-dependent negative side effects to the TM were observed at power levels exceeding 89 mW. Although we did not find any significant negative effects of optical stimulation on the hearing function in these mice, based on the histology results further studies are necessary for optimization of the used parameters.

Cochlea-Specific Deletion of Cav1.3 Calcium Channels Arrests Inner Hair Cell Differentiation and Unravels Pitfalls of Conditional Mouse Models.

Inner hair cell (IHC) Cav1.3 Ca2+ channels are multifunctional channels mediating Ca2+ influx for exocytosis at ribbon synapses, the generation of Ca2+ action potentials in pre-hearing IHCs and gene expression. IHCs of deaf systemic Cav1.3-deficient (Cav1.3-/-) mice stay immature because they fail to up-regulate voltage- and Ca2+-activated K+ (BK) channels but persistently express small conductance Ca2+-activated K+ (SK2) channels. In pre-hearing wildtype mice, cholinergic neurons from the superior olivary complex (SOC) exert efferent inhibition onto spontaneously active immature IHCs by activating their SK2 channels. Because Cav1.3 plays an important role for survival, health and function of SOC neurons, SK2 channel persistence and lack of BK channels in systemic Cav1.3-/- IHCs may result from malfunctioning neurons of the SOC. Here we analyze cochlea-specific Cav1.3 knockout mice with green fluorescent protein (GFP) switch reporter function, Pax2::cre;Cacna1d-eGFP flex/flex and Pax2::cre;Cacna1d-eGFP flex/-. Profound hearing loss, lack of BK channels and persistence of SK2 channels in Pax2::cre;Cacna1d-eGFP flex/- mice recapitulated the phenotype of systemic Cav1.3-/- mice, indicating that in wildtype mice, regulation of SK2 and BK channel expression is independent of Cav1.3 expression in SOC neurons. In addition, we noticed dose-dependent GFP toxicity leading to death of basal coil IHCs of Pax2::cre;Cacna1d-eGFP flex/flex mice, likely because of high GFP concentration and small repair capacity. This and the slower time course of Pax2-driven Cre recombinase in switching two rather than one Cacna1d-eGFPflex allele lead us to study Pax2::cre;Cacna1d-eGFP flex/- mice. Notably, control Cacna1d-eGFPflex/- IHCs showed a significant reduction in Cav1.3 channel cluster sizes and currents, suggesting that the intronic construct interfered with gene translation or splicing. These pitfalls are likely to be a frequent problem of many genetically modified mice with complex or multiple gene-targeting constructs or fluorescent proteins. Great caution and appropriate controls are therefore required.

A Self-Adhesive Elastomeric Wound Scaffold for Sensitive Adhesion to Tissue.

Pressure sensitive adhesives based on silicone materials are used particularly for skin adhesion, e.g., the fixation of electrocardiogram (ECG) electrodes or wound dressings. However, adhesion to sensitive tissue structures is not sufficiently addressed due to the risk of damage or rupture. We propose an approach in which a poly-(dimethylsiloxane) (PDMS)-based soft skin adhesive (SSA) acts as cellular scaffold for wound healing. Due to the intrinsically low surface free energy of silicone elastomers, functionalization strategies are needed to promote the attachment and spreading of eukaryotic cells. In the present work, the effect of physical adsorption of three different proteins on the adhesive properties of the soft skin adhesive was investigated. Fibronectin adsorption slightly affects adhesion but significantly improves the cellular interaction of L929 murine fibroblasts with the polymeric surface. Composite films were successfully attached to explanted tympanic membranes. This demonstrates the potential of protein functionalized SSA to act as an adhesive scaffold in delicate biomedical applications.

Frequency-specific activation of the peripheral auditory system using optoacoustic laser stimulation.

Hearing impairment is one of the most common sensory deficits in humans. Hearing aids are helpful to patients but can have poor sound quality or transmission due to insufficient output or acoustic feedback, such as for high frequencies. Implantable devices partially overcome these issues but require surgery with limited locations for device attachment. Here, we investigate a new optoacoustic approach to vibrate the hearing organ with laser stimulation to improve frequency bandwidth, not requiring attachment to specific vibratory structures, and potentially reduce acoustic feedback. We developed a laser pulse modulation strategy and simulated its response at the umbo (1-10 kHz) based on a convolution-based model. We achieved frequency-specific activation in which non-contact laser stimulation of the umbo, as well as within the middle ear at the round window and otic capsule, induced precise shifts in the maximal vibratory response of the umbo and neural activation within the inferior colliculus of guinea pigs, corresponding to the targeted, modelled and then stimulated frequency. There was also no acoustic feedback detected from laser stimulation with our experimental setup. These findings open up the potential for using a convolution-based optoacoustic approach as a new type of laser hearing aid or middle ear implant.

Laser-induced tissue remodeling within the tympanic membrane.

The tympanic membrane (TM) separates the outer ear from the tympanic cavity. Repeated pathologies can permanently decrease its tension, inducing conductive hearing loss and adhesive processes up to cholesteatoma. The current main therapy is its surgical reconstruction. Even though lasers have been proposed to tighten atrophic TMs, details of this effect, specifically histological analyses, are missing. We therefore used laser pulses to induce TM collagen remodeling in an animal model to compare the histological and electrophysiological effects of different applied laser intensities before entering clinical studies. We irradiated Fuchsin-stained areas of the TM in anesthetized mice with 532-nm laser-pulses of 10 mW for 30 s (0.3 J), 25 mW for 30 s (0.75 J) or 50 mW for 30 s (1.5 J) monitoring hearing with auditory brainstem responses (ABRs). The mice were sacrificed after 2 to 8 weeks and histologically analyzed. An increase in the TM thickness within the defined, stained, and irradiated areas could be observed after 4 weeks. Polarized light microscopy and transmission electron microscopy demonstrated the tissue volume increase majorly due to new collagen-fibrils. Directly after irradiation, ABR thresholds did not increase. We herein demonstrate a controlled laser-induced collagen remodeling within defined areas of the TM. This method might be the prophylactic solution for chronic inflammatory ear pathologies related to decreased TM tension.

Non-penetrating round window electrode stimulation for tinnitus therapy followed by cochlear implantation.

One main theory behind the origin of tinnitus is based on the idea that alterations of the spontaneous electrical activity within the auditory system lead to abnormal firing patterns in the affected nervous structures [1]. A possible therapeutic option is the use of electrical stimulation of the auditory nerve for the recovery or at least limitation of the abnormal firing pattern to a level that can be easily tolerated by the patient. The Tinnelec Implant consists of a single non-penetrating stimulation electrode connected to a Neurelec cochlear implant system. As a first feasibility study, before starting implantations in hearing patients, we thought to assess the potential of the Tinnelec stimulation to treat tinnitus in unilateral deaf patients, analysing hereby its effectivity and risks. Three patients suffering from unilateral tinnitus resistant to pharmacological treatment and ipsilateral severe to profound sensorineural hearing loss/deafness were implanted with a Tinnelec system between September 2007 and July 2008, at the ENT Department of Hannover Medical School. The stimulation strategy was chosen to induce alleviation of the tinnitus through suppression, masking and/or habituation and the response of each patient on the treatment was monitored using a visual analogue scale (VAS) on loudness and annoyance of tinnitus, mood of the patient, as well as the tinnitus handicap inventory (THI). All patients had a benefit from the electrical stimulation for their tinnitus (THI-score improvement of 20-70), however, not all participants profited from the Tinnelec system in same way and degree. In one patient, despite good results, the device had to be replaced with a conventional cochlear implant because of Tinnelec-independent increase in hearing loss on the contralateral ear. Additionally, due to the extension of cochlear implant indications, the devices of the other two patients have been meanwhile replaced with a conventional cochlear implant to benefit additionally from hearing improvement. As demonstrated in the present study, sensorineural tinnitus in humans may be suppressed/masked/habituated by electrical stimulation. The main advantage of the Tinnelec implant would be the option to treat patients with normal and usable hearing, stimulating the affected ear with the cochlear non-penetrating stimulation electrode of the device, and extend the treatment in cases of progressive hearing loss by explanation and reimplantation with a penetrating electrode addressing tinnitus as well as the hearing impairment. The present study is the first report on a long-term follow-up on tinnitus patients implanted with Tinnelec. Further clinical studies to implant tinnitus patients with residual or normal hearing on the affected ear are on the way.

Optical cochlear implant: evaluation of insertion forces of optical fibres in a cochlear model and of traumata in human temporal bones.

Optical stimulation for hearing restoration is developing as an alternative therapy to electrical stimulation. For a more frequency-specific activation of the auditory system, light-guiding fibres need to be inserted into the coiled cochlea. To enable insertion with minimal trauma, glass fibres embedded in silicone were used as models. Thus, glass fibres of varying core/cladding diameter with and without silicon coating (single as well as in bundles) were inserted into a human scala tympani (ST) model. Insertion cochlear model force measurements were performed, and the thinner glass fibres that showed low insertion forces in the model were inserted into cadaveric human temporal bones. Silicone-coated glass fibres with different core/cladding diameters and bundle sizes could be inserted up to a maximum depth of 20 mm. Fibres with a core/cladding diameter of 50/55 µm break during insertion deeper than 7-15 mm into the ST model, whereas thinner fibres (20/25 µm) could be inserted in the model without breakage and in human temporal bones without causing trauma to the inner ear structures. The insertion forces of silicone-coated glass fibres are comparable to those measured with conventional cochlear implant (CI) electrodes. As demonstrated in human temporal bones, a minimal traumatic implantation of an optical CI may be considered feasible.

New genetic findings in parotid gland pleomorphic adenomas.

BACKGROUND: Despite numerous studies, the tumor biology of pleomorphic adenomas, the most common salivary gland tumors, is still not completely defined. In order to identify further candidate genes important for tumor biology of pleomorphic adenomas, extended cytogenetic and molecular analysis are mandatory. METHODS: We performed a detailed molecular cytogenetic analysis using comparative genomic hybridization (CGH) followed by fluorescence in situ hybridization (FISH) with probes for chromosome X, 16p, 17, and 20 on a large cohort of pleomorphic adenomas (n = 29). RESULTS: We could confirm previously described deletions in pleomorphic adenomas affecting 16p, 17, 20q, and 22 by FISH and/or CGH analysis. Moreover, our CGH study revealed novel candidate regions on 8p23.1pter, 9p, 10q25.1q25.3, and 11q24qter in the series of analyzed pleomorphic adenomas. CONCLUSION: Our present study reveals new insights in novel candidate regions implicated in pleomorphic adenoma tumorigenesis which should be considered in further molecular studies.

Ossiculoplasty in missing malleus and stapes patients: experimental and preliminary clinical results with a new malleus replacement prosthesis with the otology-neurotology database.

OBJECTIVE: To present the preliminary results of new malleus replacement prosthesis combined with a total ossicular prosthesis in middle ear reconstruction in patients missing the malleus and stapes. STUDY DESIGN: Prospective experimental and nonrandomized clinical study. SETTING: Tertiary referral center. METHODS: An original titanium malleus replacement prosthesis (MRP) was designed to be inserted into the external auditory canal and to replace a missing malleus for various middle ear pathologies. The MRP was tested experimentally and clinically. The vibratory properties of the new prosthesis were measured using laser Doppler vibrometry. Ninety patients with missing malleus and stapes, undergoing 92 ossicular reconstructions were enrolled in this study from September 1994 to March 2012. Comparative analyses were made between a group of 34 cases of ossicular reconstructions with total prosthesis (TORP) positioned from the tympanic membrane to the stapes footplate (TM-to-footplate assembly) and a group of 58 cases of ossicular reconstructions with TORP positioned from a newly designed malleus replacement prosthesis (MRP) to the stapes footplate (MRP-to-footplate assembly). Preoperative and postoperative audiometric evaluation using conventional audiometry, that is, air-bone gap (ABG), bone-conduction thresholds (BC), and air-conduction thresholds (AC) were assessed. RESULTS: Experimentally, the vibratory properties of the MRP are promising and remain very good even when the MRP is cemented into the bony canal wall mimicking its complete osseous-integration, if this were to occur. This finding supports the short-term clinical results as in the TM-to-footplate group; the 3-month postoperative mean ABG was 23.3 dB compared with 12.5 dB in the MRP-to-footplate group (difference, 10.8; 95% confidence interval, 4.0-17.6); 37.0% of patients from the TM-to-footplate group had a postoperative ABG of 10 dB or less, and 48.1% of patients had a postoperative ABG of 20 dB or less, as compared with 58.1% and 79.1%, respectively, in the MRP-to-footplate group. The average gain in AC was 11.0 dB in the TM-to-footplate group as compared with 21.3 dB in the MRP-to-footplate group (difference, -10.3; 95% confidence interval, -18.2 to -2.4). CONCLUSION: The results of this study indicate that superior postoperative hearing thresholds could be achieved using a MRP-to-footplate assembly, compared with a TM-to-footplate assembly in patients with an absent malleus undergoing ossiculoplasty. The postoperative AC thresholds, after 3 months and 1 year, are significantly lower in patients treated with the MRP-to-footplate assembly.

Stable release of BDNF from the fibroblast cell line NIH3T3 grown on silicone elastomers enhances survival of spiral ganglion cells in vitro and in vivo.

The treatment of choice for profound sensorineural hearing loss (SNHL) is direct electrical stimulation of spiral ganglion cells (SGC) via a cochlear implant (CI). The number and excitability of SGC seem to be critical for the success that can be achieved via CI treatment. However, SNHL is associated with degeneration of SGC. Long-term drug delivery to the inner ear for improving SGC survival may be achieved by functionalisation of CI electrodes with cells providing growth factors. Therefore, the capacity of brain-derived neurotrophic factor (BDNF)-secreting NIH3T3 cells grown on cylindrically shaped silicone elastomers (SE) to exert local and sustained neuroprotective effects was assessed in vitro and in vivo. An in vitro model to investigate adhesion and cell growth of lentivirally modified NIH3T3 cells synthesising BDNF on SE was established. The bioactivity of BDNF was characterised by co-cultivation of SGC with cell-coated SE. In addition, cell-coated SE were implanted into deafened guinea pigs. The recombinant NIH3T3 cells proliferated on silicone surfaces during 14 days of cultivation and expressed significantly increasing BDNF levels. Enhanced survival rates and neurite outgrowth of SGC demonstrated the bioactivity of BDNF in vitro. Implantation of SE with adhering BDNF-secreting NIH3T3 cells into the cochleae of systemically deafened guinea pigs induced a significant increase in SGC survival in comparison to SE without cell coating. Our data demonstrate a novel approach of cell-based long-term drug delivery to support SGC survival in vitro and in vivo. This therapeutic strategy--once transferred to cells suitable for clinical application--may improve CI performance.

Cochlear implantation in unilateral deaf subjects associated with ipsilateral tinnitus.

OBJECTIVE: In subjects who are deaf and who also have tinnitus in the affected ear, tinnitus treatments based on acoustic input are impossible. On the other hand, tinnitus suppression using electric stimulation has been reported to be successful. Therefore, a study was initiated to investigate the potential of cochlear implantation (CI) in unilateral deaf subjects regarding tinnitus suppression, device acceptance, and restoration of spatial hearing. METHOD: Five subjects with severe to profound unilateral deafness having also ipsilateral tinnitus were enrolled. In monthly visits, the speech processor program was optimized, and the hearing performance as well as tinnitus were monitored. In addition, it was investigated whether the CI improves hearing in adverse listening situations when combined with the normal hearing side. RESULTS: In 3 participants, the tinnitus was significantly suppressed while wearing the device. In the other 2 participants, the tinnitus could be reduced in certain situations. Speech perception tests revealed a significant benefit with the CI in combination with the normal-hearing side for 3 participants. All participants accepted the device in a clinical setting; adaptation of the frequency allocation was not required. CONCLUSION: Improvements were found regarding the hearing and the tinnitus. Not all participants benefit from the CI to the same degree and in the same situations.The results indicate that cochlear implantation in subjects with unilateral severe to profound hearing loss and ipsilateral tinnitus may be beneficial on a case-to-case basis. Further work needs to be performed to define the appropriate indication criteria.

Artemin improves survival of spiral ganglion neurons in vivo and in vitro.

Artemin and its receptors are upregulated in the auditory nerve of deafened rats as a possible intrinsic protective mechanism against ototoxicity-related apoptosis. Consequently, we examined the effect of artemin on spiral ganglion neurons in vitro and in vivo. Spiral ganglion neurons were isolated from neonatal rats and cultured in serum-free medium supplemented with artemin and/or brain-derived neurotrophic factor (BDNF). In vitro, the survival rate of spiral ganglion neurons cultivated with artemin or BDNF was significantly improved compared with negative controls. In addition, artemin was delivered to the inner ear of deafened guinea pigs for 28 days. In-vivo artemin was as effective as BDNF in spiral ganglion neuron protection. Therefore, artemin promotes the survival of spiral ganglion neurons in vitro and in vivo.