Reduced preoperative serum choline esterase levels and fecal peritoneal contamination as potential predictors for the leakage of intestinal sutures after source control in secondary peritonitis.

BACKGROUND: The high rate of stoma placement during emergency laparotomy for secondary peritonitis is a paradigm in need of change in the current fast-track surgical setting. Despite growing evidence for the feasibility of primary bowel reconstruction in a peritonitic environment, little data substantiate a surgeons' choice between a stoma and an anastomosis. The aim of this retrospective analysis is to identify pre- and intraoperative parameters that predict the leakage risk for enteric sutures placed during source control surgery (SCS) for secondary peritonitis. METHODS: Between January 2014 and December 2020, 497 patients underwent SCS for secondary peritonitis, of whom 187 received a primary reconstruction of the lower gastro-intestinal tract without a diverting stoma. In 47 (25.1%) patients postoperative leakage of the enteric sutures was directly confirmed during revision surgery or by computed tomography. Quantifiable predictors of intestinal suture outcome were detected by multivariate analysis. RESULTS: Length of intensive care, in-hospital mortality and failure of release to the initial home environment were significantly higher in patients with enteric suture leakage following SCS compared to patients with intact anastomoses (p < 0.0001, p = 0.0026 and p =0.0009, respectively). Reduced serum choline esterase (sCHE) levels and a high extent of peritonitis were identified as independent risk factors for insufficiency of enteric sutures placed during emergency laparotomy. CONCLUSIONS: A preoperative sCHE < 4.5 kU/L and generalized fecal peritonitis associate with a significantly higher incidence of enteric suture insufficiency after primary reconstruction of the lower gastro-intestinal tract in a peritonitic abdomen. These parameters may guide surgeons when choosing the optimal surgical procedure in the emergency setting.

Anthropomorphic Polydimethylsiloxane silicone-based phantom for Diffuse Optical Imaging.

This work presents a method for constructing phantoms suitable for diffuse optical mammography. They are based on Polydimethylsiloxane silicones, with the characteristic of being anthropomorphic, and having similar mechanical and optical properties as a real breast. These phantoms are useful for testing the performance of diffuse optical imaging devices in the near infrared, both in transmittance and reflectance geometries, since they can be constructed containing inclusions, to simulate breast tumors. An alternative component to be used as scattering agent, that is easier to handle than traditional scattering agents, is also studied. The optical properties of the phantoms were tested varying the concentration of scattering and absorbing agents, while their mechanical properties were modified by adding a silicone fluid to the basic mixture. Finally, the phantoms were tested by Diffuse Optical Imaging experiments, and these images were compared to the ones obtained by conventional ultrasound techniques. Results show that the constructed anthropomorphic phantoms properly reproduce the optical and mechanical characteristics of human breasts, and are suitable to be used in Diffuse Optical Imaging.

Commercial α1-antitrypsin preparations markedly differ in their potential to inhibit the ATP-induced release of monocytic interleukin-1ß.

The acute phase protein α1-antitrypsin (AAT) inhibits numerous proteases, specifically neutrophil elastase. Patients with an AAT deficiency due to mutations frequently develop early onset emphysema. The commercial preparations of human plasma AAT are clinically used as biopharmaceuticals to protect the lung tissue of AAT-deficient patients from damage caused by neutrophil elastase. Accordingly, preparations of AAT are validated for their anti-elastase activity. However, several anti-inflammatory effects of AAT were described, some of them being independent from its anti-protease function. We recently demonstrated that AAT isolated from the blood of healthy persons efficiently inhibits the ATP-induced release of interleukin-1ß by human monocytes. This finding is of therapeutic relevance, because IL-1ß plays an important role in numerous debilitating and life-threatening inflammatory diseases. As anti-inflammatory functions of AAT are of increasing clinical interest, we compared the potential of two widely used AAT preparations, Prolastin® and Respreeza®, to inhibit the ATP-induced release of IL-1ß using human monocytic U937 cells. We detected marked functional differences between both medicaments. The AAT preparation Respreeza® is less active compared to Prolastin® regarding the inhibition of the ATP-induced release of monocytic IL-1ß. Chemical oxidation of Respreeza® restored this anti-inflammatory activity, while destroying its anti-protease function. Our data suggest that the anti-inflammatory potential and the anti-protease function of AAT can be fully uncoupled. In the light of the increasing clinical interest in anti-inflammatory functions of AAT, commercial AAT preparations should be carefully reinvestigated and optimized to preserve the dual anti-protease and anti-inflammatory activity of native AAT.

Sensitivity analysis of a strongly-coupled human-based electromechanical cardiac model: Effect of mechanical parameters on physiologically relevant biomarkers.

The human heart beats as a result of multiscale nonlinear dynamics coupling subcellular to whole organ processes, achieving electrophysiologically-driven mechanical contraction. Computational cardiac modelling and simulation have achieved a great degree of maturity, both in terms of mathematical models of underlying biophysical processes and the development of simulation software. In this study, we present the detailed description of a human-based physiologically-based, and fully-coupled ventricular electromechanical modelling and simulation framework, and a sensitivity analysis focused on its mechanical properties. The biophysical detail of the model, from ionic to whole-organ, is crucial to enable future simulations of disease and drug action. Key novelties include the coupling of state-of-the-art human-based electrophysiology membrane kinetics, excitation-contraction and active contraction models, and the incorporation of a pre-stress model to allow for pre-stressing and pre-loading the ventricles in a dynamical regime. Through high performance computing simulations, we demonstrate that 50% to 200% - 1000% variations in key parameters result in changes in clinically-relevant mechanical biomarkers ranging from diseased to healthy values in clinical studies. Furthermore mechanical biomarkers are primarily affected by only one or two parameters. Specifically, ejection fraction is dominated by the scaling parameter of the active tension model and its scaling parameter in the normal direction ( k ort 2 ); the end systolic pressure is dominated by the pressure at which the ejection phase is triggered ( P ej ) and the compliance of the Windkessel fluid model ( C ); and the longitudinal fractional shortening is dominated by the fibre angle ( ϕ ) and k ort 2 . The wall thickening does not seem to be clearly dominated by any of the considered input parameters. In summary, this study presents in detail the description and implementation of a human-based coupled electromechanical modelling and simulation framework, and a high performance computing study on the sensitivity of mechanical biomarkers to key model parameters. The tools and knowledge generated enable future investigations into disease and drug action on human ventricles.

Does heart surgery change the capacity of α1-antitrypsin to inhibit the ATP-induced release of monocytic interleukin-1ß? A preliminary study.

Heart surgery involving cardiopulmonary bypass induces systemic inflammation that is, at least in part, caused by extracellular ATP originating from damaged cells and by proteases secreted by activated neutrophils. The anti-protease α1-antitrypsin (AAT) forms complexes with several proteases including neutrophil elastase, resulting in a mutual loss of activity. We demonstrated recently that AAT inhibits the ATP-induced release of the pro-inflammatory cytokine interleukin-1ß by human monocytes by a mechanism involving activation of metabotropic functions at nicotinic acetylcholine receptors. Interleukin-1ß importantly contributes to the pathogenesis of sterile inflammatory response syndrome. Thus, AAT might function as an endogenous safeguard against life-threatening systemic inflammation. In this preliminary study, we test the hypothesis that during cardiopulmonary bypass, AAT is inactivated as an anti- protease and as an inhibitor of ATP-induced interleukin-1ß release. AAT was affinity-purified from the blood plasma of patients before, during and after surgery. Lipopolysaccharide-primed human monocytic U937 cells were stimulated with ATP in the presence or absence of patient AAT to test for its inhibitory effect on interleukin-1ß release. Anti-protease activity was investigated via complex formation with neutrophil elastase. The capacity of patient AAT to inhibit the ATP-induced release of interleukin-1ß might be slightly reduced in response to heart surgery and complex formation of patient AAT with neutrophil elastase was unimpaired. We conclude that surgery involving cardiopulmonary bypass does not markedly reduce the anti-inflammatory and the anti-protease activity of AAT. The question if AAT augmentation therapy during heart surgery is suited to attenuate postoperative inflammation warrants further studies in vivo.

Phosphocholine - an agonist of metabotropic but not of ionotropic functions of α9-containing nicotinic acetylcholine receptors.

We demonstrated previously that phosphocholine and phosphocholine-modified macromolecules efficiently inhibit ATP-dependent release of interleukin-1ß from human and murine monocytes by a mechanism involving nicotinic acetylcholine receptors (nAChR). Interleukin-1ß is a potent pro-inflammatory cytokine of innate immunity that plays pivotal roles in host defence. Control of interleukin-1ß release is vital as excessively high systemic levels cause life threatening inflammatory diseases. In spite of its structural similarity to acetylcholine, there are no other reports on interactions of phosphocholine with nAChR. In this study, we demonstrate that phosphocholine inhibits ion-channel function of ATP receptor P2X7 in monocytic cells via nAChR containing α9 and α10 subunits. In stark contrast to choline, phosphocholine does not evoke ion current responses in Xenopus laevis oocytes, which heterologously express functional homomeric nAChR composed of α9 subunits or heteromeric receptors containing α9 and α10 subunits. Preincubation of these oocytes with phosphocholine, however, attenuated choline-induced ion current changes, suggesting that phosphocholine may act as a silent agonist. We conclude that phophocholine activates immuno-modulatory nAChR expressed by monocytes but does not stimulate canonical ionotropic receptor functions.

Intravenous immunoglobulin in necrotizing fasciitis - A case report and review of recent literature.

INTRODUCTION: Necrotizing fasciitis (NF) is an inflammatory disease of the soft tissue, which causes local tissue destruction and can lead to lethal septic shock. The therapy consists of early surgical treatment of the septic focus and an accompanying broad spectrum antibiotic therapy. Recent literature considers the additional use of immunoglobulin therapy in severe soft skin and tissue infections. PRESENTATION OF CASE: In this report, we describe the case of a 33-year-old male patient treated at a university hospital intensive care unit because of an NF of his left leg. The patient rapidly developed a complicated septic disease after a minor superficial trauma. Despite intense microbiological diagnosis, no causative pathogens were identified. After non-responding to established broad anti-infective treatment, the patient received intravenous immunoglobulin, that rapidly improved his clinical condition. DISCUSSION: NF represents a disease processes, which is characterized by fulminant, widespread necrosis of soft tissue, systemic toxicity, and high mortality (>30%). Beside the surgical debridement and broad spectrum antibiotic therapy IVIg therapy might be an additional option in the treatment of NF. But the current literature supporting the use of IVIG in NF is largely based on retrospective or case-controlled studies, and only small randomized trials. CONCLUSION: The demonstrated case suggests that IVIg treatment of patients with NF can be considered in case of hemodynamic unstable, critically ill patients. Although randomized controlled trials are missing, some patients might benefit from diminishing hyperinflammation by immunoglobins.

Proliferation of CD8-positive T cells in blood vessels of rat renal allografts.

It is still disputed in which anatomical compartments of allograft recipients T-cells proliferate. After experimental renal transplantation, host monocytes and lymphocytes accumulate in the lumina of graft blood vessels. In this study, we test the hypothesis that T lymphocytes proliferate in the vascular bed of the graft. Kidneys were transplanted in the Dark Agouti to Lewis rat strain combination, an established experimental model for acute rejection. Isogeneic transplantation was performed as a control. Cells in the S-phase of mitosis were detected in situ three days posttransplantation by pulse-labeling with BrdU and by immunohistochemical detection of the proliferating cell nuclear antigen (PCNA). More than 20% of all T-cells in the lumina of allograft blood vessels incorporated BrdU and approximately 30% of them expressed PCNA. In the blood vessels of isografts as well as in other organs of allograft recipients, only few BrdU(+) cells were detected. A majority of the BrdU(+) cells in graft blood vessels expressed CD8. In conclusion, we demonstrate that CD8(+) T lymphocytes proliferate in the lumina of the blood vessels of renal allografts during the onset of acute rejection.

Rabbit-specific ventricular model of cardiac electrophysiological function including specialized conduction system.

The function of the ventricular specialized conduction system in the heart is to ensure the coordinated electrical activation of the ventricles. It is therefore critical to the overall function of the heart, and has also been implicated as an important player in various diseases, including lethal ventricular arrhythmias such as ventricular fibrillation and drug-induced torsades de pointes. However, current ventricular models of electrophysiology usually ignore, or include highly simplified representations of the specialized conduction system. Here, we describe the development of an image-based, species-consistent, anatomically-detailed model of rabbit ventricular electrophysiology that incorporates a detailed description of the free-running part of the specialized conduction system. Techniques used for the construction of the geometrical model of the specialized conduction system from a magnetic resonance dataset and integration of the system model into a ventricular anatomical model, developed from the same dataset, are described. Computer simulations of rabbit ventricular electrophysiology are conducted using the novel anatomical model and rabbit-specific membrane kinetics to investigate the importance of the components and properties of the conduction system in determining ventricular function under physiological conditions. Simulation results are compared to panoramic optical mapping experiments for model validation and results interpretation. Full access is provided to the anatomical models developed in this study.

All-trans retinoic acid results in irregular repair of septa and fails to inhibit proinflammatory macrophages.

All-trans retinoic acid (ATRA) is controversially discussed in emphysema therapy. We re-evaluated ATRA in the elastase model and hypothesised that beneficial effects should be reflected by increased alveolar surface area, elastin expression and downregulation of inflammatory mediators and matrix metalloproteinases (MMPs). Emphysema was induced by porcine pancreatic elastase versus saline in Sprague-Dawley rats. On days 26-37, rats received daily intraperitoneal injections with ATRA (500 µg · kg(-1) body weight) versus olive oil. Lungs were removed at day 38. Rat alveolar epithelial L2 cells were incubated with/without elastase followed by ATRA- or vehicle-treatment, respectively. ATRA only partially ameliorated structural defects. Alveolar walls exhibited irregular architecture: increased arithmetic mean thickness, reduction in surface coverage by alveolar epithelial cells type II. ATRA only partially restored reduced soluble elastin. It tended to increase the ratio of ED1(+):ED2(+) macrophages. Bronchoalveolar lavage (BAL) cells exhibited a proinflammatory state and high expression of interleukin-1ß, cytokine-induced neutrophil chemoattractant-1, tumour necrosis factor-α, nuclear factor-κB, MMP-2, MMP-9, MMP-12, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in emphysema, with ATRA exerting only few effects. MMP-7 was highly induced by ATRA in healthy but not in emphysematous lungs. ATRA reduced both MMP-2 and TIMP-1 activity in BAL fluid of emphysematous lungs. ATRA-therapy may bear the risk of unwanted side-effects on alveolar septal architecture in emphysematous lungs.

Integrated approach for the study of anatomical variability in the cardiac Purkinje system: from high resolution MRI to electrophysiology simulation.

The ordered electrical stimulation of the ventricles is achieved by a specialized network of fibres known as the Purkinje system. The gross anatomy and basic functional role of the Purkinje system is well understood. However, very little is known about the detailed anatomy of the Purkinje system, its inter-individual variability and the implications of the variability in ventricular function, in part due to limitations in experimental techniques. In this study, we aim to provide new insight into the inter-individual variability of the free running Purkinje system anatomy and its impact on ventricular electrophysiological function. As a first step towards achieving this aim, high resolution magnetic resonance imaging (MRI) datasets of rat and the rabbit ventricles are obtained and analysed using a novel semi-automatic image processing algorithm for segmentation of the free-running Purkinje system. Segmented geometry from the MRI datasets is used to construct a computational model of the Purkinje system, which is incorporated in to an anatomically-based ventricular geometry to simulate ventricular electrophysiological activity.

The systems biology approach to drug development: application to toxicity assessment of cardiac drugs.

Side effects account for most of the instances of failure of candidate drugs at late stages of development. These development failures contribute to the exorbitant cost of bringing new compounds to market: a single withdrawal can represent a loss of more than $1 billion. Many unwanted actions of drugs affect the heart, resulting in potentially proarrhythmic alteration of ion channel function. Because these can be fatal, potential electrophysiological cardiotoxicity is among the most stringent exclusion criteria in the licensing process.

Extratumoral spiral fixed wire marking of small pulmonary nodules for thoracoscopic resection.

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) for pulmonary nodules close to the visceral pleura is an established procedure. Different methods have been developed to mark these nodules when resecting small nodules distant to the pleural surface. The possibility of tumor cell spread due to nodule penetration is a major drawback. Furthermore, guide wire-based marking systems have revealed the problem of accidental wire dislocation prior to resection. METHODS: In this study, a new marker system for computed tomography-guided extranodular spiral fixed wire marking (ESFWM) was evaluated in an attempt to maintain tumor integrity while reducing the risk of wire dislocation. RESULTS: Our study included 42 patients with 44 marked nodules. 40 nodules were resected by VATS in 38 of these patients. The remaining 4 patients required conversion to thoracotomy due to adhesions and a non-deflated lung. Wire dislocation and nodule penetration occurred only once. CONCLUSION: The new lung marker system revealed a very low risk of wire dislocation. Peritumoral marking allows the safe resection of subpleural nodules without a risk of tumor cell spread.

Expression of neuropeptide Y and its receptors Y1 and Y2 in the rat heart and its supplying autonomic and spinal sensory ganglia in experimentally induced diabetes.

Diabetic cardiomyopathy, involving both cardiomyocytes and the sensory and autonomic cardiac innervation, is a major life-threatening complication in diabetes mellitus. Here, we induced long-term (26-53 weeks) diabetes in rats by streptozotocin injection and analyzed the major cardiac neuropeptide signaling system, neuropeptide Y (NPY) and its receptors Y1R and Y2R. Heart compartments and ganglia supplying sympathetic (stellate ganglion) and spinal sensory fibers (upper thoracic dorsal root ganglia=DRG) were analyzed separately by real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Ventricular, but not atrial innervation density by NPY-immunoreactive fibers was diminished, and preproNPY expression was transiently (26 weeks) reduced in left atria, but remained unchanged in sympathetic neurons and was not induced in DRG neurons. In all ganglia and heart compartments, Y1R expression dominated over Y2R, and Y1R-immunoreactivity was observed on cardiomyocytes and neuronal perikarya. Atrial, but not ventricular Y1R expression was up-regulated after 1 year of diabetes. Collectively, these data show that a disturbance of the cardiac NPY-Y1R/Y2R signaling system develops slowly in the course of experimentally induced diabetes and differentially affects atria and ventricles. This is in parallel with the clinically observed imbalances of the cardiac autonomic innervation in diabetic cardiac autonomic neuropathy.

Keratinocyte growth factor prevents intra-alveolar oedema in experimental lung isografts.

Primary graft dysfunction, characterised by intra-alveolar oedema, is a major obstacle in pulmonary transplantation. The present study evaluates the potential of keratinocyte growth factor (palmiferin; DeltaN23-KGF) for the prevention of oedema in lung transplants. Intratracheal instillation of 5 mg x kg(-1) DeltaN23-KGF was performed in Lewis rats on days 3 and 2 before explantation. Control animals obtained an equivalent volume of vehicle. Left lungs were isogeneically transplanted and the graft recipients were sacrificed 1 day later for stereological analysis of intra-alveolar oedema and bronchoalveolar lavage. The total protein and phospholipid content, as well as surfactant proteins, were measured. Surfactant activity was analysed with a pulsating bubble surfactometer. In grafts from control treated donors, the fraction of intra-alveolar oedema amounted to 3.4+/-1.1% of the total parenchymal volume. Treatment of donor lungs with DeltaN23-KGF reduced oedema to a fraction of 1.6+/-0.8%. In the lavage fluid of pulmonary grafts from DeltaN23-KGF-treated donors, the total protein content was decreased compared with vehicle-treated lung transplants, whereas phospholipids did not differ. The protein fraction contained increased amounts of surfactant protein-C after DeltaN23-KGF treatment and surfactant function was improved. Treatment of donor lungs with palifermin protects against intra-alveolar oedema formation upon transplantation. This effect appears to be mediated by an improved surfactant homeostasis.

Lung transplantation in the Fischer 344-->Wistar Kyoto rat strain combination is not suitable to study bronchiolitis obliterans.

BACKGROUND: To elucidate the pathogenesis of bronchiolitis obliterans (BO) a reliable animal model is needed. According to the literature, lung transplantation from Fischer 344 (F344) to Wistar Kyoto (WKY) rats is the only model that reliably results in BO without a further stimulus. METHODS: We performed orthotopic left lung transplantation in F344 to WKY rats and in both isogeneic rat strain combinations. Suture and cuff techniques for anastomosis were compared. The time course of rejection and the morphology of the bronchial anastomoses were documented by repeated flat-panel volumetric computed tomography (fpVCT) in the living animal. Graft histopathology was analyzed 3 months post-transplant. RESULTS: According to the graft outcome, as revealed by fpVCT, grafts were sub-divided into two groups: In Group 1, infiltrates due to acute rejection occurred early after transplantation and resolved thereafter. Graft histopathology showed minor changes but no BO. In Group 2, acute rejection caused total atelectasis that never resolved. After 3 months, grafts were shrunken and exhibited tissue remodeling with some similarities to BO. No correlation between graft outcome and anastomotic technique was apparent. CONCLUSIONS: Modeling lung transplantation using the F344-to-WKY combination is without clinical relevance because BO does not develop in grafts with life-sustaining function. Consecutive fpVCT is useful to monitor pathologic changes in rat pulmonary grafts.

Improved watershed transform for medical image segmentation using prior information.

The watershed transform has interesting properties that make it useful for many different image segmentation applications: it is simple and intuitive, can be parallelized, and always produces a complete division of the image. However, when applied to medical image analysis, it has important drawbacks (oversegmentation, sensitivity to noise, poor detection of thin or low signal to noise ratio structures). We present an improvement to the watershed transform that enables the introduction of prior information in its calculation. We propose to introduce this information via the use of a previous probability calculation. Furthermore, we introduce a method to combine the watershed transform and atlas registration, through the use of markers. We have applied our new algorithm to two challenging applications: knee cartilage and gray matter/white matter segmentation in MR images. Numerical validation of the results is provided, demonstrating the strength of the algorithm for medical image segmentation.

Effective mass of two-dimensional 3He.

We use structural information from diffusion Monte Carlo calculations for two-dimensional 3He to calculate the effective mass. Static effective interactions are constructed from the density and spin-structure functions using sum rules. We find that both spin and density fluctuations contribute about equally to the effective mass. Our results show, in agreement with recent experiments, a flattening of the single-particle self-energy with increasing density, which eventually leads to a divergent effective mass.

GeRTiSS: Generic Real Time Surgery Simulation.

Minimally invasive surgery is a technique that permits interventions through very small incisions. This minimises the patients' trauma and permits a faster recovery in comparison with classical surgery. The disadvantage of this surgery technique, though, is its complexity, requiring a high training effort of the surgeon. In this paper, we present a general surgery simulator for training surgeons in minimally invasive surgery. The application allows to create environments and interaction modes very similar to those encountered in real surgical interventions. The virtual environments are optionally composed of an actual patient's organs the intervention on which one desires to practice in a beforehand manner, or of synthetically generated organs with arbitrary pathologies. The intervention is carried out by means of haptic interfaces with force feedback, providing the surgeon with a sense of touch, a fundamental element of all types of surgery.

Zero-temperature equation of state of two-dimensional 3He.

The equation of state of two-dimensional 3He at zero temperature has been calculated using the diffusion Monte Carlo method. By means of a combination of the fixed-node and released-node techniques, it is shown that backflow correlations provide a very accurate equation of state. The results prove unambiguously the non-self-bound character of two-dimensional 3He due to its Fermi statistics. We present solid evidence that the gas phase, predicted for the two-dimensional system, can be extrapolated to the case of 3He adsorbed on a strong substrate such as graphite.