Automatic inference of ICD-10 codes from German ophthalmologic physicians' letters using natural language processing

Physicians' letters are the optimal source of diagnoses for registries. However, most registries demand for diagnosis codes such as ICD-10. We herein describe an algorithm that infers ICD-10 codes from German ophthalmologic physicians' letters. We assess the method in three German eye hospitals. Our algorithm is based on the nearest-neighbor method as well as on a large thesaurus for ICD-10 codes. This thesaurus was embedded into a Word2Vec space created from anonymized physicians' reports of the first hospital. For evaluation, each of the three hospitals sent all diagnoses taken from 100 letters. The inferred ICD-10 codes were evaluated for correctness by the senders. A total of 3332 natural language terms had been sent in (812 hospital one, 1473 hospital two, 1047 hospital three). A total of 526 non-diagnoses were excluded upfront. 2806 ICD-10 codes were inferred (771 hospital one, 1226 hospital two, 809 hospital three). In the first hospital, 98% were fully correct and 99% correct at the level of the superordinate disease concept. The percentages in hospital two were 69% and 86%. The respective numbers for hospital three were 69% and 91%. Our simple method is capable of inferring ICD-10 codes for German natural language diagnoses, especially when the embedding space has been built with physicians' letters from the same hospital. The method may yield sufficient accuracy for many tasks in the multi-centric setting and can easily be adapted to other languages/specialities.

Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X

In this paper, we present the design and commissioning results of the upgraded collective Thomson scattering diagnostic at the Wendelstein 7-X stellarator. The diagnostic has a new radiometer designed to operate between the second and third harmonics of the electron cyclotron emission from the plasma at 171-177 GHz, where the emission background has a minimum and is of order 10-100 eV. It allows us to receive the scattered electromagnetic field with a significantly improved signal-to-noise ratio and extends the set of possible scattering geometries compared to the case of the original instrument operated at 140 GHz. The elements of the diagnostic are a narrowband notch filter and a frequency stabilized probing gyrotron that will allow measuring scattered radiation spectra very close to the probing frequency. Here, we characterize the microwave components applied to the radiometer and demonstrate the performance of the complete system that was achieved during the latest experimental campaign, OP2.1.

Discrimination between the effects of pulsed electrical stimulation and electrochemically conditioned medium on human osteoblasts

BACKGROUND

Electrical stimulation is used for enhanced bone fracture healing. Electrochemical processes occur during the electrical stimulation at the electrodes and influence cellular reactions. Our approach aimed to distinguish between electrochemical and electric field effects on osteoblast-like MG-63 cells. We applied 20 Hz biphasic pulses via platinum electrodes for 2 h. The electrical stimulation of the cell culture medium and subsequent application to cells was compared to directly stimulated cells. The electric field distribution was predicted using a digital twin.

RESULTS

Cyclic voltammetry and electrochemical impedance spectroscopy revealed partial electrolysis at the electrodes, which was confirmed by increased concentrations of hydrogen peroxide in the medium. While both direct stimulation and AC-conditioned medium decreased cell adhesion and spreading, only the direct stimulation enhanced the intracellular calcium ions and reactive oxygen species.

CONCLUSION

The electrochemical by-product hydrogen peroxide is not the main contributor to the cellular effects of electrical stimulation. However, undesired effects like decreased adhesion are mediated through electrochemical products in stimulated medium. Detailed characterisation and monitoring of the stimulation set up and electrochemical reactions are necessary to find safe electrical stimulation protocols.

Sequential host-bacteria and bacteria-bacteria interactions determine the microbiome establishment of Nematostella vectensis

BACKGROUND

The microbiota of multicellular organisms undergoes considerable changes during host ontogeny but the general mechanisms that control community assembly and succession are poorly understood. Here, we use bacterial recolonization experiments in Nematostella vectensis as a model to understand general mechanisms determining bacterial establishment and succession. We compared the dynamic establishment of the microbiome on the germfree host and on inert silicone tubes.

RESULTS

Following the dynamic reconstruction of microbial communities on both substrates, we show that the initial colonization events are strongly influenced by the host but not by the silicone tube, while the subsequent bacteria-bacteria interactions are the main driver of bacterial succession. Interestingly, the recolonization pattern on adult hosts resembles the ontogenetic colonization succession. This process occurs independently of the bacterial composition of the inoculum and can be followed at the level of individual bacteria. To identify potential metabolic traits associated with initial colonization success and potential metabolic interactions among bacteria associated with bacterial succession, we reconstructed the metabolic networks of bacterial colonizers based on their genomes. These analyses revealed that bacterial metabolic capabilities reflect the recolonization pattern, and the degradation of chitin might be a selection factor during early recolonization of the animal. Concurrently, transcriptomic analyses revealed that Nematostella possesses two chitin synthase genes, one of which is upregulated during early recolonization.

CONCLUSIONS

Our results show that early recolonization events are strongly controlled by the host while subsequent colonization depends on metabolic bacteria-bacteria interactions largely independent of host ontogeny. Video Abstract.

Induced neural phase precession through exogeneous electric fields

The gradual shifting of preferred neural spiking relative to local field potentials (LFPs), known as phase precession, plays a prominent role in neural coding. Correlations between the phase precession and behavior have been observed throughout various brain regions. As such, phase precession is suggested to be a global neural mechanism that promotes local neuroplasticity. However, causal evidence and neuroplastic mechanisms of phase precession are lacking so far. Here we show a causal link between LFP dynamics and phase precession. In three experiments, we modulated LFPs in humans, a non-human primate, and computational models using alternating current stimulation. We show that continuous stimulation of motor cortex oscillations in humans lead to a gradual phase shift of maximal corticospinal excitability by ~90°. Further, exogenous alternating current stimulation induced phase precession in a subset of entrained neurons (~30%) in the non-human primate. Multiscale modeling of realistic neural circuits suggests that alternating current stimulation-induced phase precession is driven by NMDA-mediated synaptic plasticity. Altogether, the three experiments provide mechanistic and causal evidence for phase precession as a global neocortical process. Alternating current-induced phase precession and consequently synaptic plasticity is crucial for the development of novel therapeutic neuromodulation methods.

Universal DNA methylation age across mammalian tissues

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

Contributions of deep learning to automated numerical modelling of the interaction of electric fields and cartilage tissue based on 3D images

Electric fields find use in tissue engineering but also in sensor applications besides the broad classical application range. Accurate numerical models of electrical stimulation devices can pave the way for effective therapies in cartilage regeneration. To this end, the dielectric properties of the electrically stimulated tissue have to be known. However, knowledge of the dielectric properties is scarce. Electric field-based methods such as impedance spectroscopy enable determining the dielectric properties of tissue samples. To develop a detailed understanding of the interaction of the employed electric fields and the tissue, fine-grained numerical models based on tissue-specific 3D geometries are considered. A crucial ingredient in this approach is the automated generation of numerical models from biomedical images. In this work, we explore classical and artificial intelligence methods for volumetric image segmentation to generate model geometries. We find that deep learning, in particular the StarDist algorithm, permits fast and automatic model geometry and discretisation generation once a sufficient amount of training data is available. Our results suggest that already a small number of 3D images (23 images) is sufficient to achieve 80% accuracy on the test data. The proposed method enables the creation of high-quality meshes without the need for computer-aided design geometry post-processing. Particularly, the computational time for the geometrical model creation was reduced by half. Uncertainty quantification as well as a direct comparison between the deep learning and the classical approach reveal that the numerical results mainly depend on the cell volume. This result motivates further research into impedance sensors for tissue characterisation. The presented approach can significantly improve the accuracy and computational speed of image-based models of electrical stimulation for tissue engineering applications.

Experimental and numerical methods to ensure comprehensible and replicable alternating current electrical stimulation experiments

Electrical stimulation has received increasing attention for decades for its application in regenerative medicine. Applications range from bone growth stimulation over cartilage regeneration to deep brain stimulation. Despite all research efforts, translation into clinical use has not yet been achieved in all fields. Recent critical assessments have identified limited documentation and monitoring of preclinical in vitro and in vivo experiments as possible reasons hampering clinical translation. In this work, we present experimental and numerical methods to determine the crucial quantities of electrical stimulation such as the electric field or current density. Knowing the stimulation quantities contributes to comprehending the biological response to electrical stimulation and to finally developing a reliable dose-response curve. To demonstrate the methods, we consider a direct contact electrical stimulation experiment that stands representative for a broad class of stimulation experiments. Electrochemical effects are addressed and methods to integrate them into numerical simulations are evaluated. A focus is laid on affordable lab equipment and reproducible open-source software solutions. Finally, clear guidelines to ensure replicability of electrical stimulation experiments are formulated.

Immune Metabolism in TH2 Responses: New Opportunities to Improve Allergy Treatment - Disease-Specific Findings (Part 1)

PURPOSE OF REVIEW

Recent high-level publications have shown an intricate connection between immune effector function and the metabolic state of the respective cells. In the last years, studies have begun analyzing the metabolic changes associated with allergies. As the first part of a two-article series, this review will briefly summarize the basics of immune metabolism and then focus on the recently published studies on metabolic changes observed in allergic patients.

RECENT FINDINGS

In the last 3 years, immune-metabolic research in allergology had a clear focus on asthma with some studies also reporting findings in food allergy and atopic dermatitis. Current results suggest asthma to be associated with a shift in cellular metabolism towards increased aerobic glycolysis (Warburg metabolism), while also displaying substantial changes in fatty acid- and amino acid metabolism (depending on investigated patient collective, asthma phenotype, and disease severity). Understanding immune-metabolic changes in allergies will allow us to (I) better understand allergic disease pathology and (II) modulate immune-metabolic pathways to improve allergy treatment.

Advanced technique for measuring relative length changes under control of temperature and helium-gas pressure

We report the realization of an advanced technique for measuring relative length changes ΔL/L of mm-sized samples under the control of temperature (T) and helium-gas pressure (P). The system, which is an extension of the apparatus described in the work of Manna et al. [Rev. Sci. Instrum. 83, 085111 (2012)], consists of two ⁴He-bath cryostats, each of which houses a pressure cell and a capacitive dilatometer. The interconnection of the pressure cells, the temperature of which can be controlled individually, opens up various modes of operation to perform measurements of ΔL/L under the variation of temperature and pressure. Special features of this apparatus include the possibility (1) to increase the pressure to values far in excess of the external pressure reservoir, (2) to substantially improve the pressure stability during temperature sweeps, (3) to enable continuous pressure sweeps with both decreasing and increasing pressure, and (4) to simultaneously measure the dielectric constant of the pressure-transmitting medium, viz., helium, ε_r ^He(T,P), along the same T-P trajectory as that used for taking the ΔL(T, P)/L data. The performance of the setup is demonstrated by measurements of relative length changes (ΔL/L)_T at T = 180 K of single crystalline NaCl upon continuously varying the pressure in the range 6 ≤ P ≤ 40 MPa.

Long-term stimulation with alternating electric fields modulates the differentiation and mineralization of human pre-osteoblasts

Biophysical stimulation by electric fields can promote bone formation in bone defects of critical size. Even though, long-term effects of alternating electric fields on the differentiation of osteoblasts are not fully understood. Human pre-osteoblasts were stimulated over 31 days to gain more information about these cellular processes. An alternating electric field with 0.7 V_rms and 20 Hz at two distances was applied and viability, mineralization, gene expression, and protein release of differentiation factors were analyzed. The viability was enhanced during the first days of stimulation. A higher electric field resulted in upregulation of typical osteogenic markers like osteoprotegerin, osteopontin, and interleukin-6, but no significant changes in mineralization. Upregulation of the osteogenic markers could be detected with a lower electric field after the first days of stimulation. As a significant increase in the mineralized matrix was identified, an enhanced osteogenesis due to low alternating electric fields can be assumed.

Using a Digital Twin of an Electrical Stimulation Device to Monitor and Control the Electrical Stimulation of Cells in vitro

Electrical stimulation for application in tissue engineering and regenerative medicine has received increasing attention in recent years. A variety of stimulation methods, waveforms and amplitudes have been studied. However, a clear choice of optimal stimulation parameters is still not available and is complicated by ambiguous reporting standards. In order to understand underlying cellular mechanisms affected by the electrical stimulation, the knowledge of the actual prevailing field strength or current density is required. Here, we present a comprehensive digital representation, a digital twin, of a basic electrical stimulation device for the electrical stimulation of cells in vitro. The effect of electrochemical processes at the electrode surface was experimentally characterised and integrated into a numerical model of the electrical stimulation. Uncertainty quantification techniques were used to identify the influence of model uncertainties on relevant observables. Different stimulation protocols were compared and it was assessed if the information contained in the monitored stimulation pulses could be related to the stimulation model. We found that our approach permits to model and simulate the recorded rectangular waveforms such that local electric field strengths become accessible. Moreover, we could predict stimulation voltages and currents reliably. This enabled us to define a controlled stimulation setting and to identify significant temperature changes of the cell culture in the monitored voltage data. Eventually, we give an outlook on how the presented methods can be applied in more complex situations such as the stimulation of hydrogels or tissue in vivo.

Small-scale agricultural grassland management can affect soil fungal community structure as much as continental scale geographic patterns

A European transect was established, ranging from Sweden to the Azores, to determine the relative influence of geographic factors and agricultural small-scale management on the grassland soil microbiome. Within each of five countries (factor ‘Country’), which maximized a range of geographic factors, two differing growth condition regions (factor ‘GCR’) were selected: a favorable region with conditions allowing for high plant biomass production and a contrasting less favorable region with a markedly lower potential. Within each region, grasslands of contrasting management intensities (factor ‘MI’) were defined: intensive and extensive, from which soil samples were collected. Across the transect, ‘MI’ was a strong differentiator of fungal community structure, having a comparable effect to continental scale geographic factors (‘Country’). ‘MI’ was also a highly significant driver of bacterial community structure, but ‘Country’ was clearly the stronger driver. For both, ‘GCR’ was the weakest driver. Also at the regional level, strong effects of MI occurred on various measures of the soil microbiome (i.e. OTU richness, management-associated indicator OTUs), though the effects were largely regional-specific. Our results illustrate the decisive influence of grassland MI on soil microbial community structure, over both regional and continental scales, and, thus, highlight the importance of preserving rare extensive grasslands.

Unusual total knee immobilization in an elderly patient due to inferior patella dislocation: Case report and review of the literature

Inferior dislocation of the patella is a rare cause of a blocked knee and occurs typically in elderly patients. In most cases the mechanism is an osteophyte on the superior pole of the patella that becomes entrapped into the femoral trochlea, keeping the patella horizontally rotated and inferior localized. Advanced age and osteoarthritic changes of the knee are the main risk factors. Reduction should be performed under general anesthesia. We describe a case of an elderly lady with a type II inferior patella dislocation after direct blunt trauma. The therapy entailed reduction, knee arthroscopy, arthroscopic resection of osteophytes and smoothening of the articular surface. No recurrence occurred and range of motion was satisfactory at time of follow-up.

Ambiguity in the interpretation of the low-frequency dielectric properties of biological tissues

The frequency-dependent behaviour of the dielectric properties of biological tissues in the frequency range below 1 kHz has been under debate since the past century. Here, we reanalyse the raw data of the main resource of the dielectric properties of biological tissues in impedance representation. Employing a Kramers-Kronig validity test and parameter estimation techniques, we can describe the data by two physical parametric models that correspond to opposing biophysical interpretations: on the one hand the data can be explained only by intrinsic tissue properties, but on the other hand evidence for electrode-specific effects can be found for all tissues under investigation. The first interpretation would justify the continued use of a parametric model comprising four Cole-Cole dispersions, which describe the dielectric properties from extremely low to very high frequencies. As an alternative that is in accordance with the second interpretation, we suggest to omit the slowest of the four dispersions in the model and increase the static conductivity to account for a frequency-independent conductivity below 1 kHz.

Computational study on electromechanics of electroactive hydrogels for cartilage-tissue repair

BACKGROUND AND OBJECTIVE

The self-repair capability of articular cartilage is limited because of non-vascularization and low turnover of its extracellular matrix. Regenerating hyaline cartilage remains a significant clinical challenge as most non-surgical and surgical treatments provide only mid-term relief. Eventually, further pain and mobility loss occur for many patients in the long run due to further joint deterioration. Repair of articular cartilage tissue using electroactive scaffolds and biophysical stimuli like electrical and osmotic stimulation may have the potential to heal cartilage defects occurring due to trauma, osteoarthritis, or sport-related injuries. Therefore, the focus of the current study is to present a computational model of electroactive hydrogels for the cartilage-tissue repair as a first step towards an optimized experimental design.

METHODS

The multiphysics transport model that mainly includes the Poisson-Nernst-Planck equations and the mechanical equation is used to find the electrical stimulation response of the polyelectrolyte hydrogels. Based upon this, a numerical model on electromechanics of electroactive hydrogels seeded with chondrocytes is presented employing the open-source software FEniCS, which is a Python library for finite-element analysis.

RESULTS

We analyzed the ionic concentrations and electric potential in a hydrogel sample and the cell culture medium, the osmotic pressure created due to ionic concentration variations and the resulting hydrogel displacement. The proposed mathematical model was validated with examples from literature.

CONCLUSIONS

The presented model for the electrical and osmotic stimulation of a hydrogel sample can serve as a useful tool for the development and analysis of a cartilaginous scaffold employing electrical stimulation. By analyzing various parameters, we pave the way for future research on a finer scale using open-source software.

Numerical Simulations as Means for Tailoring Electrically Conductive Hydrogels Towards Cartilage Tissue Engineering by Electrical Stimulation

Cartilage regeneration is a clinical challenge. In recent years, hydrogels have emerged as implantable scaffolds in cartilage tissue engineering. Similarly, electrical stimulation has been employed to improve matrix synthesis of cartilage cells, and thus to foster engineering and regeneration of cartilage tissue. The combination of hydrogels and electrical stimulation may pave the way for new clinical treatment of cartilage lesions. To find the optimal electric properties of hydrogels, theoretical considerations and corresponding numerical simulations are needed to identify well-suited initial parameters for experimental studies. We present the theoretical analysis of a hydrogel in a frequently used electrical stimulation device for cartilage regeneration and tissue engineering. By means of equivalent circuits, finite element analysis, and uncertainty quantification, we elucidate the influence of the geometric and dielectric properties of cell-seeded hydrogels on the capacitive-coupling electrical field stimulation. Moreover, we discuss the possibility of cellular organisation inside the hydrogel due to forces generated by the external electric field. The introduced methodology is easily reusable by other researchers and allows to directly develop novel electrical stimulation study designs. Thus, this study paves the way for the design of future experimental studies using electrically conductive hydrogels and electrical stimulation for tissue engineering.

Gut Dysbiosis With Bacilli Dominance and Accumulation of Fermentation Products Precedes Late-onset Sepsis in Preterm Infants

BACKGROUND

Gut dysbiosis has been suggested as a major risk factor for the development of late-onset sepsis (LOS), a main cause of mortality and morbidity in preterm infants. We aimed to assess specific signatures of the gut microbiome, including metabolic profiles, in preterm infants <34 weeks of gestation preceding LOS.

METHODS

In a single-center cohort, fecal samples from preterm infants were prospectively collected during the period of highest vulnerability for LOS (days 7, 14, and 21 of life). Following 16S rRNA gene profiling, we assessed microbial community function using microbial metabolic network modeling. Data were adjusted for gestational age and use of probiotics.

RESULTS

We studied stool samples from 71 preterm infants with LOS and 164 unaffected controls (no LOS/necrotizing enterocolitis). In most cases, the bacteria isolated in diagnostic blood culture corresponded to the genera in the gut microbiome. LOS cases had a decelerated development of microbial diversity. Before onset of disease, LOS cases had specific gut microbiome signatures with higher abundance of Bacilli (specifically coagulase-negative Staphylococci) and a lack of anaerobic bacteria. In silico modeling of bacterial community metabolism suggested accumulation of the fermentation products ethanol and formic acid in LOS cases before the onset of disease.

CONCLUSIONS

Intestinal dysbiosis preceding LOS is characterized by an accumulation of Bacilli and their fermentation products and a paucity of anaerobic bacteria. Early microbiome and metabolic patterns may become a valuable biomarker to guide individualized prevention strategies of LOS in highly vulnerable populations.

Requirements for Documenting Electrical Cell Stimulation Experiments for Replicability and Numerical Modeling∗

Thorough documentation of biological experiments is necessary for their replicability. This becomes even more evident when individual steps of in vitro wet-lab experiments are to be incorporated into computer simulation models. In the highly interdisciplinary field of electrical stimulation of biological cells, not only biological but also physical aspects play a crucial role. Simulations may help to identify parameters that influence cells and thereby reveal new insights into mechanisms of the cell biological system. However, missing or misleading documentation of the electrical stimulation step within wet-lab experiments may lead to discrepancies between reported and simulated electrical quantities. In addition, this threatens the replicability of electrical stimulation experiments. Thus, we argue that a minimal set of information is needed to enable a translation of electrical stimulation experiments of biological cells into computer simulation experiments and to support replicability. This set includes detailed information about the electronic devices and components, their set-up as well as the applied stimulus and shall be integrated into an existing guideline for cell biological experiments. Ideally, the documentation should also contain measured properties of the cellular and experimental environment. Furthermore, a realization of our proposed documentation requirements within electronic lab notebooks may provide a crucial step toward a more seamless integration of wet-lab data into simulations. Based on two exemplary studies, we demonstrate the relevance of our claim.

Numerical simulation of the electric field distribution in an electrical stimulation device for scaffolds settled with cartilaginous cells

Electrical stimulation is a promising approach to enhance cell viability and differentiation. We aim to develop a stimulation device for the investigation and realization of cartilaginous cell engineering. The stimulation setup is capable of applying well-defined electric fields to several scaffolds at the same time. The setup consists of a flat plate with multiple test tubes for the scaffolds. A flexible printed circuit board containing a separate pair of electrodes for each tube is fixed at the bottom of the plate. In this context, numerical simulation using Finite Element Method (FEM) is a valuable tool to gain a better understanding of the electric field distribution in such devices. The thin insulating layer of the flexible printed circuit board allows sufficient field strength to be achieved at moderate input voltages but presents challenges for modelling. In simulations, thin layers would usually require a fine discretization with many degrees of freedom (DOF). This leads to large models, which are expensive regarding memory and computation time. Based on the 'contact impedance' boundary condition available in COMSOL Multiphysics® 5.4, an alternative approach is proposed that can model thin layers in capacitively coupled setups. The resulting electric field distribution in the new stimulation setup is presented and discussed.

AMS-100: The Next Generation Magnetic Spectrometer in Space - An International Science Platform for Physics and Astrophysics at Lagrange Point 2

The next generation magnetic spectrometer in space, AMS-100, is designed to have a geometrical acceptance of 100 m2 sr and to be operated for at least ten years at the Sun-Earth Lagrange Point 2. Compared to existing experiments, it will improve the sensitivity for the observation of new phenomena in cosmic rays, and in particular in cosmic antimatter, by at least a factor of 1000. The magnet design is based on high temperature superconductor tapes, which allow the construction of a thin solenoid with a homogeneous magnetic field of 1 Tesla inside. The inner volume is instrumented with a silicon tracker reaching a maximum detectable rigidity of 100 TV and a calorimeter system that is 70 radiation lengths deep, equivalent to four nuclear interaction lengths, which extends the energy reach for cosmic-ray nuclei up to the PeV scale, i.e. beyond the cosmic-ray knee. Covering most of the sky continuously, AMS-100 will detect high-energy gamma rays in the calorimeter system and by pair conversion in the thin solenoid, reconstructed with excellent angular resolution in the silicon tracker.

Re-Differentiation Capacity of Human Chondrocytes in Vitro Following Electrical Stimulation with Capacitively Coupled Fields

Treatment of cartilage lesions remains a clinical challenge. Therefore, biophysical stimuli like electric fields seem to be a promising tool for chondrocytic differentiation and treatment of cartilage lesions. In this in vitro study, we evaluated the effects of low intensity capacitively coupled electric fields with an alternating voltage of 100 mVRMS (corresponds to 5.2 × 10-5 mV/cm) or 1 VRMS (corresponds to 5.2 × 10-4 mV/cm) with 1 kHz, on human chondrocytes derived from osteoarthritic (OA) and non-degenerative hyaline cartilage. A reduction of metabolic activity after electrical stimulation was more pronounced in non-degenerative cells. In contrast, DNA contents in OA cells were significantly decreased after electrical stimulation. A difference between 100 mVRMS and 1 VRMS was not detected. However, a voltage-dependent influence on gene and protein expression was observed. Both cell types showed increased synthesis rates of collagen (Col) II, glycosaminoglycans (GAG), and Col I protein following stimulation with 100 mVRMS, whereas this increase was clearly higher in OA cells. Our results demonstrated the sensitization of chondrocytes by alternating electric fields, especially at 100 mVRMS, which has an impact on chondrocytic differentiation capacity. However, analysis of further electrical stimulation parameters should be done to induce optimal hyaline characteristics of ex vivo expanded human chondrocytes.

P1824Aortic wall shear stress in bicuspid aortic valve disease - 10-year follow-up

Introduction

Bicuspid aortic valve (BAV) disease leads to deviant complex helical flow patterns in the aorta - especially in the mid-ascending (AoA) part. In association with congenital BAV, aortic wall alterations such as aortic dilatation and dissection may occur. Among others, wall shear stress (WSS) could be one parameter to contribute to the prediction of the long-term outcome of patients with BAV. 4D-flow in cardiovascular magnetic resonance has been established as a valid method to estimate WSS.

Purpose

The aim of this study is to reevaluate WSS and comparing it to values generated in the same patient cohort with bicuspid aortic valve disease in 2008. No one of the above had aortic dilation in 2008 but proven helical flow pattern. The long term follow-up study might show changes in WSS over the period of ten years.

Methods

Ten complete 4D flow datasets of patients (age at follow-up: median 34.5 years; range 19–41 years) with bicuspid aortic valve disease without enlargement of the aorta were obtained in 2008 and reevaluated in 2018/2019 in the same patient collective. Mean WSS values were calculated with identical specific software tools. All data were analyzed by two experienced investigators.

Results

Aortic diameters at the level of the mid AoA did not change significantly in the 10-year period. The WSS values were lower in 2018 at all levels of the ascending aorta (Table 1). Indexed aortic diameters at the level of the mid ascending aorta did not change, median difference 0.06 cm/m2 (range −0.1 cm/m2 to 0.2 cm/m2; p=0.28), absolute values of indexed AoA diameters in 2018/2019 ranged from 1.27 cm/m2 to 2.2 cm/m2 (median 1.76 cm/m2).

Table 1 WSS magnitudinal [N/m2] 2008 (n=10) 2018 (n=10) Median difference p-value median range median range Level aortic bulb 0.95 0.80–1.46 0.42 0.34–0.82 −0.53 <0.01 Level mid ascending aorta 0.72 0.40–0.98 0.39 0.34–0.59 −0.33 <0.01 Level brachiocephalic trunc (BCT) 0.71 0.38–1.03 0.40 0.37–0.61 −0.31 <0.01

Conclusions

Indexed AoA diameters in BAV disease did not change significantly over a 10-year period. WSS of AoA was less compared to values generated in 2008. This might be explained by a slight alteration in hemodynamic flow patterns by the aging aorta, but not by changes of the aortic diameters. Possibly a drop of WSS in BAV could serve as a marker for a benign long term course.

[Medical confidentiality]

Medical confidentiality is a fundamental prerequisite in the patient-physician relationship based on trust and goes back to the Hippocratic oath. It is clearly defined in the German Constitution as well as the medical professional code of conduct. A breach of confidentiality can result in criminal sanctions and professional consequences as well as civil claims for damages and compensation by the affected patients. In routine clinical practice situations repeatedly occur which lead to uncertainty regarding the limits of confidentiality, the right to silence and the obligation to disclosure. The purpose of this article is to explain the legal foundations of medical confidentiality, the right to silence and the obligation to disclosure and to provide practical support for critical questions in routine clinical practice.

Numerical Simulation of Electroactive Hydrogels for Cartilage-Tissue Engineering

The intrinsic regeneration potential of hyaline cartilage is highly limited due to the absence of blood vessels, lymphatics, and nerves, as well as a low cell turnover within the tissue. Despite various advancements in the field of regenerative medicine, it remains a challenge to remedy articular cartilage defects resulting from trauma, aging, or osteoarthritis. Among various approaches, tissue engineering using tailored electroactive scaffolds has evolved as a promising strategy to repair damaged cartilage tissue. In this approach, hydrogel scaffolds are used as artificial extracellular matrices, and electric stimulation is applied to facilitate proliferation, differentiation, and cell growth at the defect site. In this regard, we present a simulation model of electroactive hydrogels to be used for cartilage–tissue engineering employing open-source finite-element software FEniCS together with a Python interface. The proposed mathematical formulation was first validated with an example from the literature. Then, we computed the effect of electric stimulation on a circular hydrogel sample that served as a model for a cartilage-repair implant.

Subject specificity of the correlation between large-scale structural and functional connectivity

Structural connectivity (SC), the physical pathways connecting regions in the brain, and functional connectivity (FC), the temporal coactivations, are known to be tightly linked. However, the nature of this relationship is still not understood. In the present study, we examined this relation more closely in six separate human neuroimaging datasets with different acquisition and preprocessing methods. We show that using simple linear associations, the relation between an individual's SC and FC is not subject specific for five of the datasets. Subject specificity of SC-FC fit is achieved only for one of the six datasets, the multimodal Glasser Human Connectome Project (HCP) parcellated dataset. We show that subject specificity of SC-FC correspondence is limited across datasets due to relatively small variability between subjects in SC compared with the larger variability in FC.

Differentiation of Alzheimer's disease based on local and global parameters in personalized Virtual Brain models

Alzheimer's disease (AD) is marked by cognitive dysfunction emerging from neuropathological processes impacting brain function. AD affects brain dynamics at the local level, such as changes in the balance of inhibitory and excitatory neuronal populations, as well as long-range changes to the global network. Individual differences in these changes as they relate to behaviour are poorly understood. Here, we use a multi-scale neurophysiological model, “The Virtual Brain (TVB)”, based on empirical multi-modal neuroimaging data, to study how local and global dynamics correlate with individual differences in cognition. In particular, we modeled individual resting-state functional activity of 124 individuals across the behavioural spectrum from healthy aging, to amnesic Mild Cognitive Impairment (MCI), to AD. The model parameters required to accurately simulate empirical functional brain imaging data correlated significantly with cognition, and exceeded the predictive capacity of empirical connectomes.

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Modeled local and global dynamics correlate with individual cognition in Alzheimer's.

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Proof of concept of The Virtual Brain to characterize individual dynamics

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Brain-behaviour relations depend on the network modeled (whole brain or limbic).

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Model parameters predict cognition better than metrics of neuroimaging data.

Childhood maltreatment, postnatal distress and the protective role of social support

The postpartum period is a vulnerable period for women with a history of childhood maltreatment. This study investigated the association between childhood maltreatment and postnatal distress three months postpartum and examined the role of social support provided by different sources (intimate partner, parents, parents-in-law, and friends). Analyses are based on N=66 women, who were screened for maltreatment experiences shortly after parturition with the Childhood Trauma Questionnaire. Their levels of postnatal distress (symptoms of depression, anxiety, and stress; assessed with the Hospital Anxiety and Depression Scale and the 4-Item version of the Perceived Stress Scale) and postpartum social support (measured with the Postpartum Social Support Questionnaire) were assessed three months postpartum. Adjusting for educational level and the experience of a recent stressful event, childhood maltreatment was directly associated with higher levels of postnatal distress. Social support provided by friends moderated this association in a heteroscedastic regression analysis. No moderating effect was observed for support provided by the own parents, the intimate partner, or parents-in-law. The association between childhood maltreatment and postnatal distress was not mediated by social support. Additional analyses revealed no main, moderating, or mediating effects of satisfaction with support. Results suggest that support provided by friends may promote resilience during the postpartum period in women with a history of childhood maltreatment. Efforts to better understand the role of postpartum support and mechanisms that may enhance a mother's ability to develop and maintain supportive friendships may be promising for guiding preventive interventions.

Homer1 (VesL-1) in the rat esophagus: focus on myenteric plexus and neuromuscular junction

Homer1, a scaffolding protein of the postsynaptic density (PSD), enriched at excitatory synapses is known to anchor and modulate group I metabotropic glutamate receptors (mGluRs) and different channel- and receptor-proteins. Homer proteins are expressed in neurons of different brain regions, but also in non-neuronal tissues like skeletal muscle. Occurrence and location of Homer1 and mGluR5 in myenteric plexus and neuromuscular junctions (NMJ) of rat esophagus have yet not been characterized. We located Homer1 and mGluR5 immunoreactivity (-iry) in rat esophagus and focused on myenteric neurons, intraganglionic laminar endings (IGLEs) and NMJs, using double- and triple-label immunohistochemistry and confocal laser scanning microscopy. Homer1-iry was found in a subpopulation of vesicular glutamate transporter 2 (VGLUT2) positive IGLEs and cholinergic varicosities within myenteric ganglia, but neither in nitrergic nor cholinergic myenteric neuronal cell bodies. Homer1-iry was detected in 63% of esophageal and, for comparison, in 35% of sternomastoid NMJs. Besides the location in the PSD, Homer1-iry colocalized with cholinergic markers, indicating a presynaptic location in coarse VAChT/CGRP/NF200- immunoreactive (-ir) terminals of nucleus ambiguus neurons supplying striated esophageal muscle. mGluR5-iry was found in subpopulations of myenteric neuronal cell bodies, VGLUT2-ir IGLEs and cholinergic varicosities within the myenteric neuropil and NMJs of esophagus and sternomastoid muscles. Thus, Homer1 may anchor mGluR5 at presynaptic sites of cholinergic boutons at esophageal motor endplates, in a small subpopulation of VGLUT2-ir IGLEs and cholinergic varicosities within myenteric ganglia possibly modulating Ca²⁺-currents and neurotransmitter release.