Mechanotransduction and hyperpolarization-activated currents contribute to spontaneous activity in mouse vestibular ganglion neurons

The hyperpolarization-activated, cyclic nucleotide–sensitive current, Ih, is present in vestibular hair cells and vestibular ganglion neurons, and is required for normal balance function. We sought to identify the molecular correlates and functional relevance of Ih in vestibular ganglion neurons. Ih is carried by channels consisting of homo- or heteromeric assemblies of four protein subunits from the Hcn gene family. The relative expression of Hcn1–4 mRNA was examined using a quantitative reverse transcription PCR (RT-PCR) screen. Hcn2 was the most highly expressed subunit in vestibular neuron cell bodies. Immunolocalization of HCN2 revealed robust expression in cell bodies of all vestibular ganglion neurons. To characterize Ih in vestibular neuron cell bodies and at hair cell–afferent synapses, we developed an intact, ex vivo preparation. We found robust physiological expression of Ih in 89% of cell bodies and 100% of calyx terminals. Ih was significantly larger in calyx terminals than in cell bodies; however, other biophysical characteristics were similar. Ih was absent in calyces lacking Hcn1 and Hcn2, but small Ih was still present in cell bodies, which suggests expression of an additional subunit, perhaps Hcn4. To determine the contributions of hair cell mechanotransduction and Ih to the firing patterns of calyx terminals, we recorded action potentials in current-clamp mode. Mechanotransduction currents were modulated by hair bundle defection and application of calcium chelators to disrupt tip links. Ih activity was modulated using ZD7288 and cAMP. We found that both hair cell transduction and Ih contribute to the rate and regularity of spontaneous action potentials in the vestibular afferent neurons. We propose that modulation of Ih in vestibular ganglion neurons may provide a mechanism for modulation of spontaneous activity in the vestibular periphery

RNA polymerase II primes Polycomb-repressed developmental genes throughout terminal neuronal differentiation

Polycomb repression in mouse embryonic stem cells (ESCs) is tightly associated with promoter co-occupancy of RNA polymerase II (RNAPII) which is thought to prime genes for activation during early development. However, it is unknown whether RNAPII poising is a general feature of Polycomb repression, or is lost during differentiation. Here, we map the genome-wide occupancy of RNAPII and Polycomb from pluripotent ESCs to non-dividing functional dopaminergic neurons. We find that poised RNAPII complexes are ubiquitously present at Polycomb-repressed genes at all stages of neuronal differentiation. We observe both loss and acquisition of RNAPII and Polycomb at specific groups of genes reflecting their silencing or activation. Strikingly, RNAPII remains poised at transcription factor genes which are silenced in neurons through Polycomb repression, and have major roles in specifying other, non-neuronal lineages. We conclude that RNAPII poising is intrinsically associated with Polycomb repression throughout differentiation. Our work suggests that the tight interplay between RNAPII poising and Polycomb repression not only instructs promoter state transitions, but also may enable promoter plasticity in differentiated cells

Effectively Measuring Exercise-Related Variations in T1ρ and T2 Relaxation Times of Healthy Articular Cartilage.

BACKGROUND: Determining the compositional response of articular cartilage to dynamic joint-loading using MRI may be a more sensitive assessment of cartilage status than conventional static imaging. However, distinguishing the effects of joint-loading vs. inherent measurement variability remains difficult, as the repeatability of these quantitative methods is often not assessed or reported. PURPOSE: To assess exercise-induced changes in femoral, tibial, and patellar articular cartilage composition and compare these against measurement repeatability. STUDY TYPE: Prospective observational study. POPULATION: Phantom and 19 healthy participants. FIELD STRENGTH/SEQUENCE: 3T; 3D fat-saturated spoiled gradient recalled-echo; T1ρ - and T2 -prepared pseudosteady-state 3D fast spin echo. ASSESSMENT: The intrasessional repeatability of T1ρ and T2 relaxation mapping, with and without knee repositioning between two successive measurements, was determined in 10 knees. T1ρ and T2 relaxation mapping of nine knees was performed before and at multiple timepoints after a 5-minute repeated, joint-loading stepping activity. 3D surface models were created from patellar, femoral, and tibial articular cartilage. STATISTICAL TESTS: Repeatability was assessed using root-mean-squared-CV (RMS-CV). Using Bland-Altman analysis, thresholds defined as the smallest detectable difference (SDD) were determined from the repeatability data with knee repositioning. RESULTS: Without knee repositioning, both surface-averaged T1ρ and T2 were very repeatable on all cartilage surfaces, with RMS-CV SDD) average exercise-induced in T1ρ and T2 of femoral (-8.0% and -5.3%), lateral tibial (-6.9% and -5.9%), medial tibial (+5.8% and +2.9%), and patellar (-7.9% and +2.8%) cartilage were observed. DATA CONCLUSION: Joint-loading with a stepping activity resulted in T1ρ and T2 changes above background measurement error. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY STAGE: 1 J. MAGN. RESON. IMAGING 2020;52:1753-1764.GlaxoSmithKline National Institute of Health Research (NIHR) Cambridge Biomedical Research Centr

Electrophysiological Properties of Embryonic Stem Cell-Derived Neurons

In vitro generation of functional neurons from embryonic stem (ES) cells and induced pluripotent stem cells offers exciting opportunities for dissecting gene function, disease modelling, and therapeutic drug screening. To realize the potential of stem cells in these biomedical applications, a complete understanding of the cell models of interest is required. While rapid advances have been made in developing the technologies for directed induction of defined neuronal subtypes, most published works focus on the molecular characterization of the derived neural cultures. To characterize the functional properties of these neural cultures, we utilized an ES cell model that gave rise to neurons expressing the green fluorescent protein (GFP) and conducted targeted whole-cell electrophysiological recordings from ES cell-derived neurons. Current-clamp recordings revealed that most neurons could fire single overshooting action potentials; in some cases multiple action potentials could be evoked by depolarization, or occurred spontaneously. Voltage-clamp recordings revealed that neurons exhibited neuronal-like currents, including an outward current typical of a delayed rectifier potassium conductance and a fast-activating, fast-inactivating inward current, typical of a sodium conductance. Taken together, these results indicate that ES cell-derived GFP+ neurons in culture display functional neuronal properties even at early stages of differentiation

Dynamic contrast-enhanced MRI of synovitis in knee osteoarthritis: repeatability, discrimination and sensitivity to change in a prospective experimental study

Abstract: Objectives: Evaluate test-retest repeatability, ability to discriminate between osteoarthritic and healthy participants, and sensitivity to change over 6 months, of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) biomarkers in knee OA. Methods: Fourteen individuals aged 40–60 with mild-moderate knee OA and 6 age-matched healthy volunteers (HV) underwent DCE-MRI at 3 T at baseline, 1 month and 6 months. Voxelwise pharmacokinetic modelling of dynamic data was used to calculate DCE-MRI biomarkers including Ktrans and IAUC60. Median DCE-MRI biomarker values were extracted for each participant at each study visit. Synovial segmentation was performed using both manual and semiautomatic methods with calculation of an additional biomarker, the volume of enhancing pannus (VEP). Test-retest repeatability was assessed using intraclass correlation coefficients (ICC). Smallest detectable differences (SDDs) were calculated from test-retest data. Discrimination between OA and HV was assessed via calculation of between-group standardised mean differences (SMD). Responsiveness was assessed via the number of OA participants with changes greater than the SDD at 6 months. Results: Ktrans demonstrated the best test-retest repeatability (Ktrans/IAUC60/VEP ICCs 0.90/0.84/0.40, SDDs as % of OA mean 33/71/76%), discrimination between OA and HV (SMDs 0.94/0.54/0.50) and responsiveness (5/1/1 out of 12 OA participants with 6-month change > SDD) when compared to IAUC60 and VEP. Biomarkers derived from semiautomatic segmentation outperformed those derived from manual segmentation across all domains. Conclusions: Ktrans demonstrated the best repeatability, discrimination and sensitivity to change suggesting that it is the optimal DCE-MRI biomarker for use in experimental medicine studies. Key Points: • Dynamic contrast-enhanced MRI (DCE-MRI) provides quantitative measures of synovitis in knee osteoarthritis which may permit early assessment of efficacy in experimental medicine studies. • This prospective observational study compared DCE-MRI biomarkers across domains relevant to experimental medicine: test-retest repeatability, discriminative validity and sensitivity to change. • The DCE-MRI biomarker Ktransdemonstrated the best performance across all three domains, suggesting that it is the optimal biomarker for use in future interventional studies

Programme minima concerning education of metrology

Zgodnie z obecnymi przepisami dla studiów magisterskich obowiązują minima programowe. Minima programowe, odnoszące się do poszczególnych kierunków studiów, określają liczbę godzin dydaktycznych dla danych przedmiotów. Metrologia została ujęta w grupie przedmiotów technicznych przy stosunkowo niedużej liczbie godzin. Powoduje to, że ze względu na specyfikę tego przedmiotu celowe jest ukierunkowanie kształcenia na zagadnienia, których przydatność jest najszersza, a jednocześnie nie podlega szybkiej dezaktualizacji.In compliance with the present regulation the master's degree studies should obseve programme minima. These minima, related to the individual lines of studies, determine the number of lectures for a given subject of studies. Metrology has been included in the group of technical subjects at a relatively small number of lectures. Therefore, in view of specificity of this subject it is advisable to concentrate education on problems of highest usefulness that will not go our of date soon

The problems of the estimation in the indirect measurements

Omówiono zagadnienia związane z oszacowaniem dokładnosci pomiarów pośrednich, w trakcie których nalezy przeprowadzic pomiary znacznej liczby wielkosci mierzonych bezpośrednio. Zwrócono szczególna uwagę na określenie końcowego wyniku tych pomiarów.In the paper were presented the problems connected with the estimation of the indirect measuring accuracy, during which exist the measure of many amount of direct measuring quantities. The main attention was given to final measure result in this measurements

Measurements of layer thickness for diagnostics of surface

W pracy przedstawiono zagadnienia, dotyczące pomiaru grubości warstw wierzchnich, przeprowadzane z wykorzystaniem przetworników indukcyjnych. Opisano badania, dotyczące przetwornika indukcyjnego transformatorowego. Na potrzeby pomiarów wykonano przetworniki pomiarowe, dla których przeprowadzono badania ich przydatności w diagnostyce wybranych warstw wierzchnich.Questions relating to the measurement of a top layer thickness were introduced in the work. Measurements carried out with the use of inductive transducers are taken into account. Problems were illustrated by examples of possible applications in diagnostics of protective coatings in car and airplanes industry. In Chapters 2 and 3 there is shown the construction of typical inductive transducer (Fig.1) and some sources of measuring errors. Model of transformer transducers (Fig. 2 and 3) and construction of applied measuring transducer (Fig. 4) were introduced in Chapters 4 and 5. Measuring transducers for which the investigations were conducted were made on needs of measurements. In Chapter 6 there are described results of investigations (Fig. 7 and 8), relating to the inductive transformer transducer. In conclusions the utility of transformer transducers for diagnostics of chosen top layers was defined

Algorytm identyfikacji pojazdów poprzez urządzenia Bluetooth wykorzystujący narzędzia Big Data

Nowadays, vehicles are equipped with various on-board devices that work in Bluetooth technology and log on to the ITS infrastructure whenever passing by Bluetooth readers. The location of Bluetooth readers is an important issue for travel time prediction in urban areas. Bluetooth technology is used to enhance travel time prediction accuracy and is additional to vehicle license number identification. The algorithms for travel time prediction are used by such technologies e.g., TRAX to offer the road user an alternative route to traverse the most congested regions of the city in the most efficient way. In this paper we present the implementation of the algorithm that enables us to match Bluetooth on-board devices, and also cell phones that are mounted or are just in vehicles of road users. Since the ITS is a source of an enormous and increasing amount of data for this purpose we engage Big Data tools such as Apache HaDoop and Apache Spark. To build Map-Reduce tasks we use Hive-SQL. The algorithm is tested on ITS data from the city of Wroclaw. The results of the algorithm may be used to locate stolen vehicles.Współczesne pojazdy wyposażane są w wiele różnych urządzeń Bluetooth, które logują się do infrastruktury ITS za każdym razem gdy przejeżdżają one w zasięgu czytników Bluetooth. Położenie czytników Bluetooth jest zagadnieniem istotnym dla metod predykcji czasu przejazdu w regionach zurbanizowanych. Technologia Bluetooth jest użyta do poprawy dokładności czasu przejazdu i jest uzupełnieniem dla identyfikacji pojazdów po numerach rejestracyjnych. Algorytmy do predykcji czasu przejazdu są używane do proponowania użytkownikom trasy alternatywnej w celu przejazdu przez najbardziej zatłoczone regiony miasta w sposób najbardziej efektywny. W artykule jest prezentowana implementacja algorytmu, który pozwala połączyć urządzenia Bluetooth i telefony znajdujące się w pojazdach z samymi pojazdami. Do tego celu angażuje się narzędzia Big Data takie jak Apache HaDoop i Apache Spark. Do zbudowania zadań Map-Reduce używa się Hive-SQLa. Algorytm był testowany na danych z wrocławskiego ITS. Wyniki działania algorytmu mogą być użyte do lokalizowania skradzionych pojazdów

Design and development of a road traffic redirection system

Nowadays, the crucial issue of guidance systems based on a GPS signal is that they are not able to redirect road users, taking into account the current state of traffic (and the predicted state within the time of the travel) in the city. In this paper we present a three layer architecture of a computer system capable of redirecting users of an urban road system via routes with a lighter traffic load in order to reach their declared destination in the city. A basic layer is a multiprocessor calculation server running Dijkstra path search tasks, the middle layer - the one which is visible to the road user - is a replicable proxy server that collects route requests from road users. The third layer is a mobile application. The prototype of such a system was developed by the ArsNumerica Group. The crucial feature of the system is feedback from road users that allows us to adjust the whole Intelligent Transportation System in the city to changes in traffic flow at various road links introduced by the redirection process applied to many users. The performance test strategy to prove the efficiency of the architecture was carried out for the city of Wrocław