Development and Function of the Voltage-Gated Sodium Current in Immature Mammalian Cochlear Inner Hair Cells

Inner hair cells (IHCs), the primary sensory receptors of the mammalian cochlea, fire spontaneous Ca2+ action potentials before the onset of hearing. Although this firing activity is mainly sustained by a depolarizing L-type (CaV1.3) Ca2+ current (ICa), IHCs also transiently express a large Na+ current (INa). We aimed to investigate the specific contribution of INa to the action potentials, the nature of the channels carrying the current and whether the biophysical properties of INa differ between low- and high-frequency IHCs. We show that INa is highly temperature-dependent and activates at around −60 mV, close to the action potential threshold. Its size was larger in apical than in basal IHCs and between 5% and 20% should be available at around the resting membrane potential (−55 mV/−60 mV). However, in vivo the availability of INa could potentially increase to >60% during inhibitory postsynaptic potential activity, which transiently hyperpolarize IHCs down to as far as −70 mV. When IHCs were held at −60 mV and INa elicited using a simulated action potential as a voltage command, we found that INa contributed to the subthreshold depolarization and upstroke of an action potential. We also found that INa is likely to be carried by the TTX-sensitive channel subunits NaV1.1 and NaV1.6 in both apical and basal IHCs. The results provide insight into how the biophysical properties of INa in mammalian cochlear IHCs could contribute to the spontaneous physiological activity during cochlear maturation in vivo

Increasing the attractiveness of surgical disciplines for students: Implications of a robot-assisted hands-on training course for medical education

BackgroundStructured implementation of robot-assisted surgery in the field of medical education is lacking. We assessed students' interest in robot-assisted surgery and tested if the implementation of a hands-on robotic course into the curriculum could increase the interest to join a surgical discipline in general and especially in female students, since women are clearly underrepresented in surgical disciplines.MethodsAfter a prostate cancer focused seminar, 100 students were 1:1 randomized into two groups. Group B: Baseline characteristics and professional interest were assessed prior and after a hands-on robotic course, using a da Vinci® console with simulator (da Vinci® Surgical training, Intuitive Surgical Inc., USA). Group A served as post-interventional consistency control group, received the questionnaire only once after the hands-on training.ResultsThe male to female ratio of students was 54% and 46%. The interest to turn into urology/surgery, categorized as yes”, “no”, “maybe” changed from 18 to 16%, 36 to 30% and 46 to 54% respectively after the hands-on robotic course (p < 0.001). Also, the positive attitude towards the surgical field significantly increased (20 vs. 48%; p < 0.001). Comparing male and female students, virtually identical proportions (23 vs. 23%) opted for joining urology or surgery as a discipline, whereas rejection (45 vs. 25%) and perchance (32 vs. 50%) of that notion differed between genders (p = 0.12).ConclusionOur results demonstrate great demand for implementing robotic training into medical education for an up-to-date curriculum. Although the decision process on career choice is widely multifactorial, stereotypes associated with surgical disciplines should be eliminated. This could have a particularly positive effect on the recruitment of female medical students since women are clearly underrepresented in surgical disciplines although currently and with increasing proportions, more female students are enrolled in medical schools then male

OSBPL2 encodes a protein of inner and outer hair cell stereocilia and is mutated in autosomal dominant hearing loss (DFNA67)

Background: Early-onset hearing loss is mostly of genetic origin. The complexity of the hearing process is reflected by its extensive genetic heterogeneity, with probably many causative genes remaining to be identified. Here, we aimed at identifying the genetic basis for autosomal dominant non-syndromic hearing loss (ADNSHL) in a large German family. Methods: A panel of 66 known deafness genes was analyzed for mutations by next-generation sequencing (NGS) in the index patient. We then conducted genome-wide linkage analysis, and whole-exome sequencing was carried out with samples of two patients. Expression of Osbpl2 in the mouse cochlea was determined by immunohistochemistry. Because Osbpl2 has been proposed as a target of miR-96, we investigated homozygous Mir96 mutant mice for its upregulation. Results: Onset of hearing loss in the investigated ADNSHL family is in childhood, initially affecting the high frequencies and progressing to profound deafness in adulthood. However, there is considerable intrafamilial variability. We mapped a novel ADNSHL locus, DFNA67, to chromosome 20q13.2-q13.33, and subsequently identified a co-segregating heterozygous frameshift mutation, c.141-142delTG (p.Arg50Alafs∗103), in OSBPL2, encoding a protein known to interact with the DFNA1 protein, DIAPH1. In mice, Osbpl2 was prominently expressed in stereocilia of cochlear outer and inner hair cells. We found no significant Osbpl2 upregulation at the mRNA level in homozygous Mir96 mutant mice. Conclusion: The function of OSBPL2 in the hearing process remains to be determined. Our study and the recent description of another frameshift mutation in a Chinese ADNSHL family identify OSBPL2 as a novel gene for progressive deafness.</p

Cerebrospinal Fluid Biomarkers of Alzheimer's Disease Show Different but Partially Overlapping Profile Compared to Vascular Dementia

Vascular factors increase the risks of developing Alzheimer's disease (AD) and they contribute to AD pathology. Since amyloid beta (Aβ) deposits can be observed in both diseases, there is an overlap which impedes a clear discrimination and difficult clinical diagnosis. In the present study, we compared cerebrospinal fluid (CSF) profiles of neurodegenerative and inflammatory biomarkers in a patient cohort of controls (n = 50), AD (n = 65) and vascular dementia (VaD) (n = 31) cases. Main results were validated in a second cohort composed of AD (n = 26), rapidly progressive AD (rpAD) (n = 15), VaD (n = 21), and cognitively unimpaired patients with vascular encephalopathy (VE) (n = 25) cases. In the study, cohort significant differences were detected in tau, p-tau, and Aβ1-42 (Aβ42) levels between AD and VaD patients, but not for the neuron-specific enolase (NSE), S100B protein, 14-3-3 and YKL-40. Differential tau, p-tau, and Aβ42 levels between AD and VaD were confirmed in the validation cohort, which additionally showed no differences between AD and rpAD, nor between VaD and VE. The evaluation of the biomarker performance in discrimination between AD and VaD patients revealed that the best diagnostic accuracy could be obtained when tau, p-tau, and Aβ42 were combined in form of Aβ42/p-tau (AUC 0.84–0.90, sensitivity 77–81%, specificity 80–93%) and (tau × p-tau)/Aβ42 ratio (AUC 0.83–0.87, sensitivity 73–81%, specificity 78–87%). Altogether, our studies provided neurodegenerative biomarker profiles in two cohorts of AD and VaD patients favoring the combination of CSF biomarker to differentiate between diseases

Abstracts from the 8th International Conference on cGMP Generators, Effectors and Therapeutic Implications

This work was supported by a restricted research grant of Bayer AG

table e-1

Performed CSF tests and surveillance dat

Data from: Validation and utilization of amended diagnostic criteria in Creutzfeldt-Jakob Disease surveillance

Objective: To validate an amended protocol for clinical diagnosis of sporadic Creutzfeldt-Jakob Disease (sCJD) including Real-Time Quaking-induced Conversion (RT-QuIC) and to observe its utilization in CJD surveillance. Methods: In the framework of a prospective epidemiological study, all neuropathological confirmed sCJD cases that received CSF RT-QuIC analysis during diagnostic work up (n=65) and a control group of non- CJD cases (n=118) were selected to investigate the accuracy of an amended diagnostic protocol. The patients had been referred to the German National Reference Center for Transmissible Spongiform Encephalopathies. The influence of the amended protocol on incidence figures was evaluated in the context of three years of surveillance activity (screened cases using 14-3-3 test: n=18.789, highly suspicious cases of CJD: n=704). Annual incidences were calculated using current criteria and the amended protocol. Results: The amended protocol showed a sensitivity of 97% and a specificity of 99%. When it was applied to all suspected cases that were referred to the reference center, the assessed incidence of CJD increased from 1.7 to 2.2 per million in 2016. Conclusion: CJD surveillance remains challenging as information from external healthcare institutions can be limited. RT-QuIC shows excellent diagnostic accuracy when applied in the clinical setting to symptomatic patients. Data for RT-QuIC alone, when applied as a general screening test, are not available yet. We propose an amended research protocol which improves early and accurate clinical diagnosis of sCJD during surveillance activities. The utilization of this protocol will probably lead to a significant increase of the incidence rate