BACKGROUND:Thermal damage to the muscle layer during mucosal application of argon plasma coagulation (APC) may be avoided by creating a fluid cushion within the submucosal layer, but the minimum injection volume needed or the ideal injection fluid are yet to be established. We conducted a systematic ex vivo study with this aim.METHODS:All experiments were performed in an ex vivo porcine gastrointestinal tract model. Five different fluids (saline, Glyceol, Gelafundin, Voluven, and Eleview) of different volumes were injected into the submucosa of different parts of the gastrointestinal tract. APC was applied to the mucosa at different power settings. Immediately after APC treatment, the temperature was measured through a thermocouple placed inside the fluid cushion, just on top of the muscle layer. The minimum volume of fluid needed to protect the muscle layer from thermal damage was determined.RESULTS:There was no difference in the temperature measured among the different injection fluids at the surface of the muscle, in all the locations, at equal injection volumes and power settings. The minimum amounts of fluid needed to protect the muscle layer were 2 and 3 mL for power settings of 30-90 W and 90-120 W, respectively.CONCLUSIONS:Normal saline and 4 commercially available submucosal injection fluids possess similar thermal protective effects. To reduce the likelihood of thermal damage to deeper layers when APC is applied, a minimum injection volume of 3 mL is recommended if less than 90 W power will be utilized over 3 sec.

To reduce manufacturing costs, a new simple radio frequency (RF) surgical generator based on a push-pull oscillator is developed for cutting tissue. In order to systematically design and test feedback controllers keeping the generator’s output voltage constant, we will present two different models of the considered RF generator. The first one is a nonlinear state space model derived using the generator’s equivalent circuit diagram and Kirchhoff’s laws and the second one is a Hammerstein model. The models are based on physical principles and are successfully validated on a generator prototype, ensuring a good match with the static and dynamic behavior of the considered RF generator. The obtained state space model is well suited to simulate the RF generator, while the Hammerstein model is appropriate to design controllers for the generator’s output voltage.

BACKGROUND:Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI) which is a significant medical, social, and economic problem. Low spatial pressure resolution, common occurrence of artifacts, and uncertainties in data location limit the diagnostic value of UPP. To overcome these limitations, high definition urethral pressure profilometry (HD-UPP) combining enhanced UPP hardware and signal processing algorithms has been developed. In this work, we present the different signal processing steps in HD-UPP and show experimental results from female minipigs.METHODS:We use a special microtip catheter with high angular pressure resolution and an integrated inclination sensor. Signals from the catheter are filtered and time-correlated artifacts removed. A signal reconstruction algorithm processes pressure data into a detailed pressure image on the urethra's inside. Finally, the pressure distribution on the urethra's outside is calculated through deconvolution. A mathematical model of the urethra is contained in a point-spread-function (PSF) which is identified depending on geometric and material properties of the urethra. We additionally investigate the PSF's frequency response to determine the relevant frequency band for pressure information on the urinary sphincter.RESULTS:Experimental pressure data are spatially located and processed into high resolution pressure images. Artifacts are successfully removed from data without blurring other details. The pressure distribution on the urethra's outside is reconstructed and compared to the one on the inside. Finally, the pressure images are mapped onto the urethral geometry calculated from inclination and position data to provide an integrated image of pressure distribution, anatomical shape, and location.CONCLUSIONS:With its advanced sensing capabilities, the novel microtip catheter collects an unprecedented amount of urethral pressure data. Through sequential signal processing steps, physicians are provided with detailed information on the pressure distribution in and around the urethra. Therefore, HD-UPP overcomes many current limitations of conventional UPP and offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct anatomical location. This could enable the development of focal therapy approaches in the treatment of SUI.

Background: Bipolar vessel sealing is an efficient electrosurgical procedure for the occlusion of blood vessels particularly during minimally invasive surgery. Reliable knowledge of the thermal spread is crucial for a safe application of bipolar vessel sealing instruments when operating close to thermo-sensitive structures, such as nerves. The evolution of the thermal spread over time and space depends on a variety of parameters, such as the biological tissue, the energy applied to the tissue, and the geometry of the vessel sealing instrument. Mathematical modeling has proven useful for the prediction of the thermal spread. It is, thus, a promising tool for the systematic analysis of the influence of geometrical changes on the thermal spread.Results: We present an experimentally validated in silico study to evaluate the impact of geometry variations on the progression of chicken egg white coagulation and the final shape of coagulated egg white as an approximation of the temporal and spatial evolution of the thermal spread during bipolar vessel sealing. Egg white has similar thermal and electrical properties to human tissue, with the advantage being that the spatial and temporal evolution of the thermal spread can be visually gauged. The simulations were performed using a mathematical model based on the finite element analysis of chicken egg white. The progression of egg white coagulation was predicted for two different peak voltages and various electrode geometries. Starting with two planar electrodes, one electrode was gradually changed to adopt a wedge shape. These changes to the geometry showed a distinct influence on the progression of egg white coagulation in the simulations. The predictions were successfully validated using an experimental setup with two different electrodes representing the extreme geometries.Discussion: The predicted spatial temperature distributions were experimentally validated for two geometries. Our simulation study shows that the geometry has a pronounced influence on the thermal spread and, thus, is a suitable parameter to reduce thermal damage. The in silico optimization of instrument designs is a suitable tool to accelerate the development of new vessel sealing instruments, with only a few promising designs having to be tested as prototypes.

Zielsetzung: Bipolare Instrumente haben für die Gefäßversiegelung eine große Bedeutung. Neben Instrumentengeometrie und -materialien spielt die speziell an die jeweilige Anwendung angepasste Regelung der Elektroparameter eine erhebliche Rolle. Durch Unterstützung eines mathematischen Modells sollen neue Modes zur schonenden und raschen bipolaren Versiegelung entwickelt werden. In dieser tierexperimentellen Studie werden Aktivierungsdauer, thermischer Lateralschaden sowie die klinische Kurz- und Langzeit-Erfolgsrate inklusive des Surrogatmarkers Berstdruck des neuen Gewebeversiegelungsmodes thermoSEAL mit dem Standard-BiClamp-Mode verglichen.

Introduction Recently, a new urodynamic method for the assessment of stress urinary incontinence called high definition urethral pressure profilometry (HD‐UPP) has been introduced. This method combines a novel microtip catheter with advanced signal processing to enable spatial data location and the reconstruction of a pressure image inside the urethra. In order to assess the reproducibility of HD‐UPP data, we statistically evaluate HD‐UPP datasets and compare them to data from a double balloon air‐charged system. Materials and Methods Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, urodynamic features are extracted, and compared to the air‐charged system. Reproducibility of HD‐UPP data is assessed by statistically evaluating consecutive, intra‐individual datasets. Results HD‐UPP delivers results in agreement with previous comparisons of microtip and air‐charged systems. The average deviation of two consecutive, intra‐individual pressure images is very low at 7 cm H 2 O. Conclusions HD‐UPP provides physicians with detailed information on the pressure distribution inside the urethra. Through comparison with an air‐charged catheter, it is shown that HD‐UPP delivers results in agreement with previous studies on the comparison of microtip and air‐charged catheters. It provides excellent reproducibility, as the difference between sequentially measured profiles from the same minipig is significantly lower than the one between profiles from different minipigs.

Macrophages are cells with remarkable plasticity. They integrate signals from their microenvironment leading to context-dependent polarization into classically (M1) or alternatively (M2) activated macrophages, representing two extremes of a broad spectrum of divergent phenotypes. Thereby, macrophages deliver protective and pro-regenerative signals towards injured tissue but, depending on the eliciting damage, may also be responsible for the generation and aggravation of tissue injury. Although incompletely understood, there is emerging evidence that macrophage polarization is critical for these antagonistic roles. To identify activation-specific expression patterns of chemokines and cytokines that may confer these distinct effects a systems biology approach was applied. A comprehensive literature-based Boolean model was developed to describe the M1 (LPS-activated) and M2 (IL-4/13-activated) polarization types. The model was validated using high-throughput transcript expression data from murine bone marrow derived macrophages. By dynamic modeling of gene expression, the chronology of pathway activation and autocrine signaling was estimated. Our results provide a deepened understanding of the physiological balance leading to M1/M2 activation, indicating the relevance of co-regulatory signals at the level of Akt1 or Akt2 that may be important for directing macrophage polarization.

Objectives: Macrophages are cells with remarkable plasticity. They are able to integrate signals from their microenvironment leading to context dependent differentiation into classically activated macrophages (M1) or alternatively activated macrophages (M2). Within the liver, macrophages are known to mediate important hepatoprotective and pro-regenerative effects but may also be responsible for impaired hepatocyte function and liver injury in response to microbial pathogens. The mechanisms responsible for this controversial role of liver macrophages are still incompletely understood.

Radiofrequency-induced thermofusion is a frequently used electrosurgical procedure for the sealing of blood vessels. A disadvantage of vessel sealing instruments is that the generated thermal energy spreads to the surrounding tissue and may irreversibly damage it. This is particularly problematic when operating close to sensitive structures such as nerves. Given their advantages, there is nonetheless a lot of interest in using bipolar vessel sealing for surgical procedures. To select instruments that may be safely used in such cases, it is important to reliably quantify the thermal spread to the surrounding tissue. Mathematical models can help to evaluate the transient behavior, that is the evolution of the thermal spread over time, more precisely. A finite element model allows for a detailed analysis of inhomogeneities in the spatial temperature distribution. As a first step towards a finite model of the bipolar vessel sealing process, a model of the coagulation of chicken egg white is presented here. Egg white has thermal and electrical properties that are very similar to tissue, making it suitable as a substitute for the analysis of the coagulation process. It has the additional advantage, that the spatial and temporal evolution of the thermal spread can be visually gauged. The presented model describes the experimentally observed spatial temperature distribution, the shape of the coagulated egg white, and the formation of hotspots. Furthermore, it is shown that the model can correctly predict the shape of the coagulated egg white in further experiments.

Urethral Pressure Profilometry (UPP) is a tool in the diagnosis of urinary incontinence. The pressure profile along the urethra is measured by a special catheter in order to assess the contraction strength of the sphincter muscle. However, the diagnostic value of pressure profilometry is limited. We seek to increase the diagnostic value by providing a detailed spatial reconstruction of the pressure profile on the outside surface of the urethra. We use deconvolution in order to solve the inverse problem of determining the pressure distribution on the outside of a tube from measured data on the inside. Therefore, we propose a parametric Point-Spread-Function (PSF) and optimize its parameters using a Finite-Element (FE) model. Simulation results verifying accuracy and robustness of this method conclude this work.

This study systematically analyses the effects on performance (effectiveness and efficiency) as well as experience (satisfaction) when using a Posture Assistance Device (PAD). Therefore an evaluation of the presented PAD was made by a multiple measurement approach in laboratory setting. In a within subject design two tasks were performed in two conditions with and without PAD. The results show advantages of the PAD regarding all criteria. Objective measurement by sEMG showed a reduction of the electrical activity of the analyzed trapezius and delta muscle when using the PAD (human efficiency). Furthermore the results show that the usage of the PAD improves the performance by decreasing the time (use efficiency) and errors (effectiveness) in both tasks. The ratings of the subjects show a satisfied attitude towards the PAD, too.

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Incontinence: Evaluation (Urodynamic Testing)1 Apr 2015PD24-01 PROOF-OF-CONCEPT FOR DATA FUSION OF URETHRAL PRESSURE DATA AND MRI Mario Klünder, Susanne Will, Karl-Dietrich Sievert, Bastian Amend, Ronny Feuer, Oliver Sawodny, Ulrich Kramer, Arnulf Stenzl, and Michael Ederer Mario KlünderMario Klünder More articles by this author , Susanne WillSusanne Will More articles by this author , Karl-Dietrich SievertKarl-Dietrich Sievert More articles by this author , Bastian AmendBastian Amend More articles by this author , Ronny FeuerRonny Feuer More articles by this author , Oliver SawodnyOliver Sawodny More articles by this author , Ulrich KramerUlrich Kramer More articles by this author , Arnulf StenzlArnulf Stenzl More articles by this author , and Michael EdererMichael Ederer More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1456AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urethral Pressure Profile (UPP) is the instrument to verify stress urinary incontinence (SUI) whereby a catheter with pressure sensing capability is retracted through the urethra to obtain the UPP. Using a novel microtip catheter and a specifically-developed signal reconstruction algorithm, a detailed map of the spatial pressure distribution inside the urethra can be illustrated. Little is known about the effect of anatomical or pathological conditions in the sphincter structure, however, MRI provides data of the anatomy and surrounding tissue without being able to quantify its pressure effects. Data fusion of MRI and UPP can provide the physician with a better understanding of the conditions in and around the urethra to improve the diagnosis and select the optimal treatment. METHODS A microtip catheter prototype was used with a total of 9 pressure sensors and an acceleration sensor to determine the orientation of the catheter during the measurement on a sedated female minipig. The UPP data was processed through a special signal reconstruction algorithm to obtain the spatial pressure distribution inside the urethra. In another female minipig, which underwent MRI in a 3T MR scanner, slices were placed orthogonally with the urethra. The enlarged images were sharpened and colored for better contrast. Finally, fusion of both datasets was carried out using Matlab®. RESULTS MRI images were stacked at slice thickness intervals. The bladder neck was identified and aligned in both MRI and UPP data. Through the catheter's acceleration sensor, UPP data was precisely oriented, (e.g. the dorsal side in UPP data aligned with the dorsal side in MRI). The 3D-plot can be freely rotated so that the physician can attain a detailed understanding of both the anatomy around the urethra (MRI) and the corresponding 3D-UPP. CONCLUSIONS MRI images were stacked at slice thickness intervals. The bladder neck was identified and aligned in both MRI and UPP data. Through the catheter's acceleration sensor, UPP data was precisely oriented, (e.g. the dorsal side in UPP data aligned with the dorsal side in MRI). The 3D-plot can be freely rotated so that the physician can attain a detailed understanding of both the anatomy around the urethra (MRI) and the corresponding pressure distribution inside (UPP). © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e486 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mario Klünder More articles by this author Susanne Will More articles by this author Karl-Dietrich Sievert More articles by this author Bastian Amend More articles by this author Ronny Feuer More articles by this author Oliver Sawodny More articles by this author Ulrich Kramer More articles by this author Arnulf Stenzl More articles by this author Michael Ederer More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Urethral Pressure Profilometry (UPP) is a tool in the diagnosis of urinary incontinence. The pressure profile along the urethra is measured by a special catheter in order to assess the contraction strength of the sphincter muscle. The use of microtip catheters with several pressure sensors and an integrated acceleration sensor enables signal reconstruction of the pressure distribution on the urethra's inside. Experimental data from minipigs exhibit artifact patterns in the pressure data. It is shown that these artifacts are caused by vascular pulsation in the sphincter structure. We therefore investigate different methods exploiting the time-correlation of the artifacts to eliminate pulse-induced artifacts in the pressure data without compromising the actual signal. Evaluation of these methods applied to experimental data conclude this work showing that both an Input-Model and Principal Component Analysis Decorrelation are effective at removing the artifacts.

The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.

Bipolar electrothermal vessel sealing is a widely used method for the sealing of blood vessels and tissue of up to several millimeters diameter. Despite their wide-spread usage, instruments and generator modes are often traditionally developed and enhanced. A systematic investigation of the thermofusion process and the subsequent derivation of new model-based control strategies have the potential to improve the vessel sealing process and reduce unwanted side-effects. Based on a previously developed mathematical model of bipolar vessel sealing, optimization based control strategies are developed that could possibly reduce the thermal damage to the lateral tissue. Assuming that it is sufficient to ensure a certain tissue temperature for successful thermofusion, it is shown that the lateral damage could be significantly reduced by optimizing the generator voltage. Furthermore it is shown, that an optimized voltage trajectory may still reduce the lateral damage to some extent if it is assumed that tissue desiccation is required. Additionally, optimally pulsed voltage strategies are presented and compared to currently employed typical generator modes. The results illustrate that optimized control strategies can potentially reduce the thermal damage to the lateral tissue and thus make bipolar vessel sealing more suitable for surgical procedures in the vicinity of sensitive structures, particularly nerves.

Introduction Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI). SUI is a significant medical, social, and economic problem, affecting about 12.5% of the population. A novel microtip catheter was developed for UPP featuring an inclination sensor and higher angular resolution compared to systems in clinical use today. Therewith, the location of each measured pressure sample can be determined and the spatial pressure distribution inside the urethra reconstructed. In order to assess the performance and plausibility of data from the microtip catheter, we compare it to data from a double balloon air charged system. Materials and Methods Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, plotted and compared against data from the air‐charged catheter. Results The microtip catheter delivers results in agreement with previous comparisons of microtip and air‐charged systems. It additionally provides a new level of detail in the reconstructed UPPs which may lead to new insights into the sphincter mechanism of minipigs. Conclusions The ability of air‐charged catheters to measure pressure circumferentially is widely considered a main advantage over microtip catheters. However, directional pressure readings can provide additional information on angular fluctuations in the urethral pressure distribution. It is shown that the novel microtip catheter in combination with a signal reconstruction algorithm delivers plausible data. It offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct location within the anatomical location of the pelvic floor. Neurourol. Urodynam. 35:888–894, 2016 . © 2015 Wiley Periodicals, Inc.

The efficient redesign of bacteria for biotechnological purposes, such as biofuel production, waste disposal or specific biocatalytic functions, requires a quantitative systems-level understanding of energy supply, carbon and redox metabolism. The measurement of transcript levels, metabolite concentrations and metabolic fluxes per se gives an incomplete picture. An appreciation of the interdependencies between the different measurement values is essential for systems-level understanding. Mathematical modeling has the potential to provide a coherent and quantitative description of the interplay between gene expression, metabolite concentrations and metabolic fluxes. Escherichia coli undergoes major adaptations in central metabolism when the availability of oxygen changes. Thus, an integrated description of the oxygen response provides a benchmark of our understanding of carbon, energy and redox metabolism. We present the first comprehensive model of the central metabolism of E. coli that describes steady-state metabolism at different levels of oxygen availability. Variables of the model are metabolite concentrations, gene expression levels, transcription factor activities, metabolic fluxes and biomass concentration. We analyze the model with respect to the production capabilities of central metabolism of E. coli. In particular, we predict how precursor and biomass concentration are affected by product formation.

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Incontinence Evaluation1 Apr 2014PD11-11 MODELING IN URODYNAMICS TO IDENTIFY DEFECTS IN THE URINARY SPHINCTER IN SITU Mario Klünder, Oliver Sawodny, Karl-Dietrich Sievert, Arnulf Stenzl, Ronny Feuer, and Michael Ederer Mario KlünderMario Klünder More articles by this author , Oliver SawodnyOliver Sawodny More articles by this author , Karl-Dietrich SievertKarl-Dietrich Sievert More articles by this author , Arnulf StenzlArnulf Stenzl More articles by this author , Ronny FeuerRonny Feuer More articles by this author , and Michael EdererMichael Ederer More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.544AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urethral pressure profilometry is a common urodynamic tool used in the diagnosis of urinary incontinence. Raw data acquired from catheters is often difficult to interpret diagnostically, because potential angular fluctuations in the pressure profile may not be detected due to limited resolution and details may be concealed by sensor noise. We propose a new method that uses a mathematical model of the urethra to reconstruct the spatial pressure profile exerted by the sphincter in high detail definition. The proposed method addresses three shortcomings of urodynamics: Obtaining the spatial pressure profile on the outside of the urethra, dealing with low angular resolution, and sensor noise. METHODS We use a microtip-catheter with eight pressure sensors on the circumference in order to at least double the angular resolution compared to catheters in use today. An inclination sensor is located close to the eight sensors that determines the orientation of the catheter during retraction. The urethra is modeled as a linear elastic hollow cylinder and discretized via the Finite-Element-Method. We use an inverse algorithm to calculate the pressure profile on the outside circumference of the cylinder from pressure on the inside. Sensor size and –positions as well as areal sensitivity characteristics are taken into account explicitly. We use the catheter on a test stand, which features a silicone tube to simulate the urethra. RESULTS Simulation results show an accurate recovery of the pressure profile on the outside of the urethra. Numeric stability even in presence of sensor noise is ensured through regularization. Using the inverse algorithm, the pressure distribution around the tube can be recovered and points of interest located. The figure shows simulation results with the deformed outside and the inside of the urethra colored according to the pressure level. CONCLUSIONS With a mathematical model of the urethra and an inverse algorithm the pressure profile of the urethra is reconstructed through the use of a novel microtip catheter that provides sufficient data inside the urethra. Simulation and data results from the test stand demonstrate the accuracy of the proposed method. A reliable spatial reconstruction of the sphincter pressure profile may add diagnostic power in future clinical application. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e290 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Mario Klünder More articles by this author Oliver Sawodny More articles by this author Karl-Dietrich Sievert More articles by this author Arnulf Stenzl More articles by this author Ronny Feuer More articles by this author Michael Ederer More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...