bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement properties of the one-minute sit-to-stand test in children and adolescents with cystic fibrosis: A multicenter randomized cross-over trial
Authors: Combret Yann , Boujibar Fairuz , Gennari Charlotte , Medrinal Clément , Sicinski Sophie , Bonnevie Tristan , Gravier Francis-Edouard , Laurans Muriel , Marguet Christophe , Le Roux Pascal , Lamia Bouchra , Prieur Guillaume , Reychler Grégory 
Published: February 2021

Background
Functional exercise capacity assessment is recommended in children with cystic fibrosis (CF). The six-minute walk test (6MWT) is a valid evaluation of exercise capacity but can be technically complex. Inversely, the sit-to-stand test (STST) is a simple method to evaluate exercise capacity, and is validated in healthy children and adults with CF. This study aimed to evaluate STST measurement properties in children and adolescents with CF.

Methods
In this multicenter study, children with CF (6 to 18 years) performed two iterations of both the STST and the 6MWT in a randomized order. Criterion validity was determined by assessing correlations between STST repetitions and 6MWT distance (6MWD). Intra-rater reliability, test-retest repeatability, mean bias and limits of agreement were also assessed. Relationships with other outcomes (i.e. respiratory and quadriceps muscle strength) and cardio-respiratory responses were analysed for both tests.

Results
Thirty-six children with CF were included (mean age 12.0 ±3.5 years and FEV1 95.8 ±25.0%). On average, 39.6 ±10.5 repetitions were performed during the STST and mean 6MWD was 596.0 ±102.6 meters. STST number of repetitions was significantly correlated with 6MWD (r = 0.48; p<0.01). Both tests had very good intra-rater reliability (ICCSTST = 0.91 (95%CI 0.76–0.96) and ICC6MWT = 0.94 (95%CI 0.85–0.97)), and a significant test-retest learning effect. The number of STST repetitions was not correlated with quadriceps or respiratory muscle strength test, and the STST induced fewer cardio-respiratory responses than the 6MWT.

Conclusions
The STST is an easy-to-use functional test with moderate criterion validity when compared to the 6MWT in children with CF, probably because both tests measure different components of functional exercise capacity. The STST is useful when the 6MWT is unfeasible, however further investigations are required to explore the clinical implications of STST results in children with CF.

Clinical trial registration
NCT03069625.
Development of a biodegradable microstent for minimally invasive treatment of Fallopian tube occlusions
Authors: Dierke Ariane , Borowski Finja , Großmann Swen , Brandt-Wunderlich Christoph , Matschegewski Claudia , Rosam Paula , Stiehm Michael , Bock Andrea , Schmitz Klaus-Peter , Siewert Stefan , Pilz Nico , Reister Paul , Schümann Kerstin , Grabow Niels , Schmitz Klaus-Peter , Einenkel Rebekka , Zygmunt Marek , Hinze Ulf , Chichkov Boris , Keiler Jonas , Wree Andreas 
Published: February 2021

Abstract
Obstructions of the Fallopian tube represent one of the most common reasons for an unfulfilled desire to have children. Microstent technology opens up new therapeutic possibilities to restore the natural lumen of the Fallopian tube within a single treatment. Within the current work we developed a self-expandable biodegradable microstent for gynecological applications. Based on a novel microstent design, prototypes were manufactured from poly-L-lactide tubing by means of fs-laser cutting. Microstent prototypes were characterized morphologically by means of scanning electron microscopy and biaxial laser scanning. As manufactured, a microstents outside diameter of about 2.3 mm and a strut thickness / width of about 114 μm / 103 μm was measured. Mechanical characterization of microstents included bending as well as crimping and release behavior. After crimping to a minimum diameter of 0.8 mm and consecutive release, a microstent recovery to a diameter of 1.8 mm was found. Therefore, proof-of-concept for the self-expandable microstent could be successfully provided.
Automated incisional hernia characterization by non-rigid registration of CT images – a pilot study
Authors: Voß Samuel , Lösel Philipp D. , Heuveline Vincent , Saalfeld Sylvia , Berg Philipp , Kallinowski Friedrich 
Published: February 2021

Abstract
Incisional hernia repair makes use of prosthetic meshes to re-establish a biomechanically stable abdominal wall. Mesh sizing and fixation have been found to be essential for the clinical outcome. Comparative CT images a) under rest versus b) under Valsalva maneuver (exhalation against closed airways) provide useful information for hernia characterization. However, this process incorporates several manual measurements, which led to observer variability. The present study suggests using an image registration approach of the CT data to reliably and reproducibly extract hernia quantities. The routine is implemented in the software framework MATLAB and works fully automatic. After CT data import, slice by slice undergo non-rigid B-spline grid registration. Local displacement and strain are extracted from the transformation field. The qualitative results correspond to the clinical observation. Maximum displacement of 3.5 cm and maximum strain of 25 % are calculated for one patient’s data set. Current approaches do not provide this type of information. Further research will focus on validation and possibilities to include this new kind of knowledge into the design process of prosthetic meshes.
Developments in Modelling Bone Screwing
Authors: Wilkie Jack , Docherty Paul D. , Möller Knut 
Published: February 2021

Abstract
INTRODUCTION: A torque-rotation model of the bone-screwing process has been proposed. Identification of model parameters using recorded data could potentially be used to determine the material properties of bone. These properties can then be used to recommend tightening torques to avoid over or under-tightening of bone screws. This paper improves an existing model to formulate it in terms of material properties and remove some assumptions. METHOD: The modelling methodology considers a critical torque, which is required to overcome friction and advance the screw into the bone. Below this torque the screw may rotate with elastic deformation of the bone tissue, and above this the screw moves relative to the bone, and the speed is governed by a speed-torque model of the operator’s hand. The model is formulated in terms of elastic modulus, ultimite tensile strength, and frictional coefficient of the bone and the geometry of the screw and hole. RESULTS: The model output shows the speed decreasing and torque increasing as the screw advances into the bone, due to increasing resistance. The general shape of the torque and speed follow the input effort. Compared with the existing model, this model removes the assumption of viscous friction, models the increase in friction as the screw advances into the bone, and is directly in terms of the bone material properties. CONCLUSION: The model presented makes significant improvements on the existing model. However it is intended for use in parameter identification, which was not evaluated here. Further simulation and experimental validation is required to establish the accuracy and fitness of this model for identifying bone material properties.
Robot-assisted Ultrasound-guided Tracking of Anatomical Structures for the Application of Focused Ultrasound
Authors: Unger Michael , Berger Johann , Gerold Bjoern , Melzer Andreas 
Published: February 2021

Abstract
High intensity focused ultrasound is used as a surgical tool to treat completely non-invasively several diseases. Examples of clinical applications are uterine fibroids, prostate cancer, thyroid nodules, and varicose veins. Precise targeting is key for improving the treatment outcome. A method for an automated, robot-assisted tracking system was developed and evaluated. A wireless ultrasound scanner was used to acquire images of the target, in this case, a blood vessel. The active contour approach by Chan and Vese was used to segment and track while moving the scanner along the target structure with a collaborative robotic arm. The performance was assessed using a custom made Agar phantom. The mean tracking error, which is defined as the remaining distance of the lesion to the images’ centre line, was 0.27 mm ± 0.18 mm.
Development of a multi-well-chip for studying 2D and 3D tumor cell migration and spheroid growth in electrical fields
Authors: Kemkemer Ralf , Naggay Benjamin K. , Schmidt Tobias B. , Ende Karen 
Published: February 2021

Abstract
Endogenous electrical fields play an important role in various physiological and pathological events. Yet the effects of electrical cues on processes such as wound healing, tumor development or metastasis are still rarely investigated, though it is known that direct current electrical fields can alter cell migration or proliferation in vitro. Several 2D experimental models for studying cell responses to direct current electrical fields have been presented and characterized but suitable experimental models for electrotaxis studies in 3D are rare. Here we present a novel, easy-to-produce, multi-well-based galvanotactic-chamber for the use in 2D and 3D cell experiments for investigations on the influence of electrical fields on tumor cell migration and tumor spheroid growth. Our presented system allows the simultaneous application of electrical field to cells in four chambers, either cultured on the bottom of the culture-plate (2D) or embedded in hydrogel filled channels (3D). The set-up is also suitable for, live-cell-imaging. Validation tests show stable electrical fields and high cell viabilities inside the channel. Tumor spheroids of various diameters can be exposed to direct current electrical fields up to one week.
Initial study on removing cellular residues from hydrostatic high-pressure treated allogeneic tissue using ultrasound
Authors: Drobek Christoph , Waletzko Janine , Dau Michael , Frerich Bernhard , Weißmann Volker , Schwerdt Daniela , Seehafer Stefan , Mau Robert , Seitz Hermann , Jonitz-Heincke Anika , Bader Rainer 
Published: February 2021

Abstract
Hydrostatic high-pressure technology (HHD) devitalizes tissue quickly and gently, without negatively affecting the structural properties. HHD-treated tissues must be cleaned from devitalized cells. A partially automated, gentle, reproducible and timesaving rinsing test setup utilizing ultrasound is demonstrated in this study. The test setup is used to clean HHD-treated bone allografts of tissue residues and prevent microbiological contamination. A rinsing procedure is investigated. Residual DNA content determination is utilized to analyze cleaned bone allograft tissue for rinsing procedure evaluation.
A pilot study: development of bonepreserving- biomimetic artificial femoral head cover
Authors: Siroros Nad , Liu Yu , Lecouturier Sophie , Tingart Markus , Eschweiler Jörg 
Published: February 2021

Abstract
Patients with hip arthrosis are increasing each year where total hip replacement is an effective solution when other non-invasive or surgical methods are no longer an effective solution. A pilot study of a new bone-preserving-biomimetic artificial femoral head cover was initiated. The purpose of the new implant is to be an alternative to the current hip arthroplasties. A special polyurethane (PU) femoral head cover was mechanically tested. Experiments were performed to investigate the implants mechanical behaviour and response to tensile load and study on the locking mechanism design concept of the prosthesis. The femoral head cover had a 45 mm outer diameter. Two suture techniques were selected to represent possible locking mechanisms. The experiment consisted of five cyclic loadings followed by a pull-to-failure test. The results show that each specimen has a consistency response and different suture technique results in a different outcome. This experiment intended to study the response of specimens as a whole part, not the material itself. Factors are influencing the outcome such as the femoral head cover positioning and suture rupture pattern. From this pilot study, some points need to be further considered. The information obtained in this experiment would influence further development achieving towards the goal of this alternative hip arthrosis treatment.
Wearable Impedance Pneumography
Authors: Klum Michael , Urban Mike , Pielmus Alexandru-Gabriel , Orglmeister Reinhold 
Published: February 2021

Abstract
Respiratory diseases are a leading cause of death worldwide. The prevalence of sleep apnea, its cardiovascular consequences, postoperative respiratory instability and severe respiratory syndromes further highlight the importance of respiratory monitoring. Typical methods, however, rely on obtrusive nasal cannulas and belts. Impedance pneumography (IP) is a promising bioimpedance application which aims to estimate respiratory parameters from the thorax impedance. Currently, IP configurations require large inter-electrode distances, diminishing its applicability in a wearable context. We propose an IP configuration with 55 mm spacing using our recently presented sensor patch. In a study including 10 healthy subjects, respiratory rate (RR) and flow are estimated in the supine, lateral and prone position. Using time-delay neural network regression, RR errors below 1 bpm, flow correlations of 0.81 and relative flow errors of 38 % with respect to a pneumotachometer reference were achieved. We conclude that high accuracy RR estimation is possible in a 55 mm IP configuration. Respiratory flow can be roughly estimated. Further research combining several biosignals for a more robust, wearable flow estimation is recommended.
Metabolic Imaging by Simultaneous FLIM of NAD(P)H and FAD
Authors: Becker Wolfgang , Braun Lukas , Suarez-Ibarrol Rodrigo , Miernik Arkadiusz 
Published: February 2021

Abstract
We describe a metabolic imaging system based on simultaneous recording of lifetime images of NAD(P)H and FAD. The system uses one-photon excitation by ps diode lasers, scanning by galvanometer mirrors, confocal detection, and two parallel TCSPC FLIM recording channels. Two lasers, with wavelengths of 375nm and 410 nm, are multiplexed to alternatingly excite NAD(P)H and FAD. One FLIM channel detects in the emission band of NAD(P)H, the other in the emission band of FAD. For both channels, the data analysis delivers images of the amplitudes of the decay components, a1 and a2. We show that these are robust parameters to characterize the metabolic state of cells. FLIM results obtained from excised human-bladder tissue were in perfect agreement with histology.
Detecting Bacteria on Wounds with Hyperspectral Imaging in Fluorescence Mode
Authors: Hornberger Christoph. , Herrmann Bert. H. , Daeschlein Georg , Podewils Sebastian von , Sicher Claudia , Kuhn Jana , Masur Kai , Meister Mareike , Wahl Philip 
Published: February 2021

Abstract
Chronic non-healing wounds represent an increasing problem. In order to enable physicians and nurses to make evidence based decisions on wound treatment, the professional societies call for supporting tools to be offered to physicians. Oxygen supply, bacteria colonization and other parameters influence the healing process. So far, these parameters cannot be monitored in an objective and routinely manner. Existing methods like the microbiological analysis of wound swabs, mean a great deal of effort and partly a long delay. In this paper 42 fluorescence images from 42 patients with diabetic foot ulcer, recorded with a hyperspectral imaging system (TIVITA®), converted for fluorescence imaging, were analysed. Beside the fluorescence images, information about the bacterial colonization is available from microbiological analysis of wound swabs. After preprocessing, principal component analysis, PCA, is used for data analysis with a 405 nm excitation wavelength, the emission wavelength range 510 - 745 nm is used for analysis. After dividing the data into a training and a test dataset it could be shown, that bacteria are detectable in the wound area. A quantification in bacterial colonization counts (BCC) was not in the focus of the research in this study stage.
Neurophotonic Scanning System – Towards Automatic Infrared Neurostimulation
Authors: Wegner Celine , Schlett Paul , Hofmann Ulrich G. , Höth Julian , Klotzbücher Thomas , Buckert Thomas , Krüger Thilo B. 
Published: February 2021

Abstract
Intraoperative neuromonitoring is without doubt important for all surgical interventions, where nerve structures are at risk. Mapping techniques for the identification of motor nerves and cortex are available. They rely on manual identification using an electrical stimulation probe. A landmark-based visualization of the results is currently not possible. To overcome these limitations, we are developing a system for automatic stimulation and display of functional tissue. Infrared neurostimulation (INS) was proposed to be a feasible alternative to electrical stimulation of nerves. It provides contactless and artifact-free activation of nerves. For our preclinical experiments we used an infrared diode laser system with a wavelength of 1470 nm. For automatic screening, we developed a scanning system and suitable scan-algorithms in order to provide optimal scanning parameters. Recording of compound muscle action potentials (CMAP) was performed with a differential amplifier and appropriate neurophysiologic software. Subunits of the system were combined via multiple interfaces. A control-software merges all relevant functions of the individual parts and parallel use. Marking of tissue was realized with a red pilot laser deflected by the same scanning system. With this work we could show, that a system for automatic laser deflection with parallel neurophysiologic recording and subsequent highlighting of irradiated tissue is possible. This system can serve as a tool for further systematic investigations in the field of INS.
Fully Data-Driven Pseudohealthy Synthesis for Planning Valve-Sparing Aortic Root Reconstruction using Conditional Variational Autoencoders
Authors: Hagenah Jannis , Mehdi Mohamad , Ernst Floris 
Published: February 2021

Abstract
Aortic root aneurysm is treated by replacing the dilated root by a grafted prosthesis which mimics the native root morphology of the individual patient. The challenge in predicting the optimal prosthesis size rises from the highly patient-specific geometry as well as the absence of the original information on the healthy root. Therefore, the estimation is only possible based on the available pathological data. In this paper, we show that representation learning with Conditional Variational Autoencoders is capable of turning the distorted geometry of the aortic root into smoother shapes while the information on the individual anatomy is preserved. We evaluated this method using ultrasound images of the porcine aortic root alongside their labels. The observed results show highly realistic resemblance in shape and size to the ground truth images. Furthermore, the similarity index has noticeably improved compared to the pathological images. This provides a promising technique in planning individual aortic root replacement.
Sensation thresholds in electrocutaneous stimulation
Authors: Dölker Eva-Maria , Mubin Alkisah binti , Supriyanto Eko , Haase Elke , Krzywinski Sybille , Haueisen Jens 
Published: February 2021

Abstract
Acoustic or visual warning signals for workers in hazardous situations might fail under loud and/or lowvisibility work situations. A warning system should be developed that uses electrocutaneous stimulation through textile electrodes. Previous work investigated suitable stimulation parameters using TENS electrodes. The aim of this study was to compare TENS and textile cuff electrodes in terms of sensation thresholds, qualitative and spatial sensation. A study on 30 healthy volunteers (f=13, m=17) of mean age of 26.7 years was conducted applying bi-phasic rectangular current pulses to electrodes attached to the upper right arm. The study revealed that perception, attention and intolerance thresholds, qualitative and spatial perception are comparable indicating that future studies with the textile cuff electrodes can be generally based on the previous results with TENS electrodes.
Method for assessment of matching of total ankle joint endoprostheses based on CT data
Authors: Martin Heiner , Wittmüß Josephine , Mittlmeier Thomas , Grabow Niels 
Published: February 2021

Abstract
The investigation of matching of endoprosthesis tibial components to the bone cross section is of interest for the manufacturer as well as for the surgeon. On the one hand, a systemic design of the prosthesis and the assortment is possible, on the other hand, a better matching implantation is enabled on the basis of experience of this study. CT sections were segmented manually using a CAD system and fitted by spline functions, then superseded with cross sections of the tibial component of a modified Hintermann H3 prosthesis. The principal moments of inertia, the direction of the principal axes and the area of the section were evaluated. Based on the relative differences of the principal moments of inertia, recommendations for application of the different prosthesis size and its selection with the surgery can be made.
Fibrosis: Altered gene expression in TGF-β stimulated human fibroblasts of the Tenon
Authors: Brietzke Andreas , Guthoff Rudolf , Stahnke Thomas , Grabow Niels 
Published: February 2021

Abstract
Despite decades of research, fibrosis still remains a significant challenge for medicine in many different fields. Although there is a general model of fibrosis, the causes and characteristics of the various pathologies are as diverse as the variety of organs and tissues that can be affected by fibrosis. Moreover, fibrosis also impedes the long-term prospects of success in implantation surgery. One possibility to address this challenge is the development of biocompatible implants featuring drug delivery systems loaded with antifibrotic pharmaceuticals. Due to diverse regulatory mechanisms in organs, tissues and also cell types, these active substances must consequentially be designed for diverse specific applications. Compared to fibrosis in organs like lung or liver, these mechanisms were poorly addressed in ophthalmologic research, but it is known that transforming growth factor beta (TGF-β) plays a key role. This gene expression study revealed 30 genes being upregulated more than two fold in TGF-β1 treated human primary tenon fibroblasts (hTF). Furthermore, 15 genes were found to be downregulated more than two fold. Tumor necrosis factor (TNF), vascular endothelial growth factor A (VEGFA) and inhibin beta (INHBE) were particular strongly regulated in TGF-β1 treated hTFs.
MagCPP: A C++ toolbox for Combining Neurofeedback with Magstim transcranial magnetic stimulators
Authors: Oppermann Hannes , Wichum Felix , Haueisen Jens , Klemm Matthias , Esch Lorenz 
Published: February 2021

Abstract
Transcranial magnetic stimulation (TMS) is an established method to treat various neurological diseases, such as depression, Alzheimer’s disease, and tinnitus. New applications for TMS are closed loop neurofeedback (NF) scenarios, which require software control of the TMS system, instead of the currently used manual control. Hence, the MagCPP (https://github.com/MagCPP) toolbox was developed and is described in this work. The toolbox enables the external control of Magstim TMS devices via a C++ interface. Comparing MagCPP to two other toolboxes in a TMS application scenario with 40% power, we found that MagCPP works faster and has lower variability in repeated runs (MagCPP, Python, MATLAB [mean±std in seconds]: 1.19±0.00, 1.59±0.01, 1.44±0.02). An integration of MagCPP in a real-time data processing platform MNE-CPP with an optional GUI demonstrates its ability as part of a closed-loop NF-scenario. With its performing advantages over other toolboxes, MagCPP is a first step towards a complete closed loop NF scenario and offers possibilities for novel study designs.