Towards Realistic 3D Models of Tumor Vascular Networks

For reliable in silico or in vitro investigations in, for example, biosensing and drug delivery applications, accurate models of tumor vascular networks down to the capillary size are essential. Compared to images acquired with conventional medical imaging techniques, digitalized histological tumor slices have a higher resolution, enabling the delineation of capillaries. Volume rendering procedures can then be used to generate a 3D model. However, the preparation of such slices leads to misalignments in relative slice orientation between consecutive slices. Thus, image registration algorithms are necessary to re-align the slices. Here, we present an algorithm for the registration and reconstruction of a vascular network from histologic slices applied to 169 tumor slices. The registration includes two steps. First, consecutive images are incrementally pre-aligned using feature- and area-based transformations. Second, using the previous transformations, parallel registration for all images is enabled. Combining intensity- and color-based thresholds along with heuristic analysis, vascular structures are segmented. A 3D interpolation technique is used for volume rendering. This results in a 3D vascular network with approximately 400-450 vessels with diameters down to 25-30 µm. A delineation of vessel structures with close distance was limited in areas of high structural density. Improvement can be achieved by using images with higher resolution and or machine learning techniques.

[Future of University Medicine: How Important are Research and Teaching? - An Inventory]

The requirements and challenges for the university hospitals in Germany are changing. Especially in surgical subjects, it is more and more difficult to adequately serve these three pillars of university medicine - clinic, research and education. This survey was intended to determine the status quo of general and visceral surgery at universities, in order to provide a basis for proposed solutions.For this online survey, 1505 visceral surgeons at the 38 university clinics were contacted. The questionnaire contained 29 questions on the structure of the clinic, scientific motivation, opportunities for time-off and the appreciation of academic achievements. The type and scope of student courses and the preparation for them were also determined. With regard to patient care, the type and number of services and the course of surgical training were examined. Based on the data published on the websites of the individual clinics on the number, gender, position and academic title of the doctors, a demographic analysis of university visceral surgeons could also be created.Of 1505 surgeons successfully contacted, 352 took part in the survey, which corresponds to a response rate of 23.4%. Of the participants, 93.5% were scientifically active, the majority being in the field of clinical data collection. Many indicated that they were also active in translational and/or experimental research, while educational research was rarely named. 45% confirmed that they could perform scientific work during their normal working hours. The reward for this activity was mostly in the form of time-off for congresses and clinical appreciation. Most participants stated that they were involved in 3-4 student courses per week, with 24.4% reporting that they were not adequately prepared for them.The compatibility of the classic three pillars of clinic, research and teaching continues to be of great relevance. There is a high level of motivation among the participating visceral surgeons not to neglect research and teaching, despite increasing economic pressure in the field of patient care. However, arrangements must be created in order to reward and promote commitment in research and teaching in a structured way.

Identifying radiomics signatures in body composition imaging for the prediction of outcome following pancreatic cancer resection

Background

Computerized radiological image analysis (radiomics) enables the investigation of image-derived phenotypes by extracting large numbers of quantitative features. We hypothesized that radiomics features may contain prognostic information that enhances conventional body composition analysis. We aimed to investigate whether body composition-associated radiomics features hold additional value over conventional body composition analysis and clinical patient characteristics used to predict survival of pancreatic ductal adenocarcinoma (PDAC) patients.

Methods

Computed tomography images of 304 patients undergoing elective pancreatic cancer resection were analysed. 2D radiomics features were extracted from skeletal muscle and subcutaneous and visceral adipose tissue (SAT and VAT) compartments from a single slice at the third lumbar vertebra. The study population was randomly split (80:20) into training and holdout subsets. Feature ranking with Least Absolute Shrinkage Selection Operator (LASSO) followed by multivariable stepwise Cox regression in 1000 bootstrapped re-samples of the training data was performed and tested on the holdout data. The fitted regression predictors were used as "scores" for a clinical (C-Score), body composition (B-Score), and radiomics (R-Score) model. To stratify patients into the highest 25% and lowest 25% risk of mortality compared to the middle 50%, the Harrell Concordance Index was used.

Results

Based on LASSO and stepwise cox regression for overall survival, ASA ≥3 and age were the most important clinical variables and constituted the C-score, and VAT-index (VATI) was the most important body composition variable and constituted the B-score. Three radiomics features (SATI_original_shape2D_Perimeter, VATI_original_glszm_SmallAreaEmphasis, and VATI_original_firstorder_Maximum) emerged as the most frequent set of features and yielded an R-Score. Of the mean concordance indices of C-, B-, and R-scores, R-score performed best (0.61, 95% CI 0.56-0.65, p<0.001), followed by the C-score (0.59, 95% CI 0.55-0.63, p<0.001) and B-score (0.55, 95% CI 0.50-0.60, p=0.03). Kaplan-Meier projection revealed that C-, B, and R-scores showed a clear split in the survival curves in the training set, although none remained significant in the holdout set.

Conclusion

It is feasible to implement a data-driven radiomics approach to body composition imaging. Radiomics features provided improved predictive performance compared to conventional body composition variables for the prediction of overall survival of PDAC patients undergoing primary resection.

Vessel Delineation Using U-Net: A Sparse Labeled Deep Learning Approach for Semantic Segmentation of Histological Images

Semantic segmentation is an important imaging analysis method enabling the identification of tissue structures. Histological image segmentation is particularly challenging, having large structural information while providing only limited training data. Additionally, labeling these structures to generate training data is time consuming. Here, we demonstrate the feasibility of a semantic segmentation using U-Net with a novel sparse labeling technique. The basic U-Net architecture was extended by attention gates, residual and recurrent links, and dropout regularization. To overcome the high class imbalance, which is intrinsic to histological data, under- and oversampling and data augmentation were used. In an ablation study, various architectures were evaluated, and the best performing model was identified. This model contains attention gates, residual links, and a dropout regularization of 0.125. The segmented images show accurate delineations of the vascular structures (with a precision of 0.9088 and an AUC-ROC score of 0.9717), and the segmentation algorithm is robust to images containing staining variations and damaged tissue. These results demonstrate the feasibility of sparse labeling in combination with the modified U-Net architecture.

Tumor ratio of unsaturated to saturated sulfatide species is associated with disease-free survival in intrahepatic cholangiocarcinoma

PURPOSE

Cholangiocarcinoma (CCA) is a malignancy arising from the bile duct epithelium and has a poor outcome. Sulfatides are lipid components of lipid rafts, and are implicated in several cancer types. In the liver, sulfatides are specifically present in the bile ducts. Here, sulfatide abundance and composition were analyzed using mass spectrometry imaging in intrahepatic CCA (iCCA) tumor tissue, and correlated with tumor biology and clinical outcomes.

METHODS

Sulfatides were analyzed in iCCA (n = 17), hepatocellular carcinoma (HCC, n = 10) and colorectal liver metastasis (CRLM, n = 10) tumor samples, as well as tumor-distal samples (control, n = 16) using mass spectrometry imaging. Levels of sulfatides as well as the relative amount in structural classes were compared between groups, and were correlated with clinical outcomes for iCCA patients.

RESULTS

Sulfatide localization was limited to the respective tumor areas and the bile ducts. Sulfatide abundance was similar in iCCA and control tissue, while intensities were notably higher in CRLM in comparison with control (18-fold, P < 0.05) and HCC tissue (47-fold, P < 0.001). Considerable variation in sulfatide abundance was observed in iCCA tumors. A high ratio of unsaturated to saturated sulfatides was associated with reduced disease-free survival (10 vs. 20 months) in iCCA. The sulfatide pattern in HCC deviated from the other groups, with a higher relative abundance of odd- versus even-chain sulfatides.

CONCLUSION

Sulfatides were found in tumor tissue of patients with iCCA, with sulfatide abundance per pixel being similar to bile ducts. In this explorative study, sulfatide abundance was not related to overall survival of iCCA patients. A high ratio of unsaturated to saturated sulfatides was associated with earlier tumor recurrence in patients with iCCA.

Golgi Protein 73 (GP73) Serum Levels Predict Outcome after Resection of Biliary Tract Cancer

Simple Summary

Biliary tract cancer (BTC) represents a rare liver malignancy with unfavorable outcome. It is often challenging to identify the ideal surgical candidates and present stratification algorithms are rarely based on the individual tumor biology. In the present manuscript, we evaluated a role of serum Golgi protein 73 (GP73) in patients with resectable BTC. We could show that elevated levels of GP73 before surgery identified a subgroup of BTC patients with a significantly reduced overall survival after tumor resection. Therefore, measurement of GP73 serum levels might become a novel tool in the challenging preoperative stratification process of patients with resectable BTC.

Abstract

Background: Tumor resection represents the only potentially curative therapy for patients with biliary tract cancer. Nevertheless, disease recurrence is observed in about 50% of patients, leading to a 5-years survival rate of less than 50%. The Golgi protein 73 (GP73), a type II Golgi transmembrane protein, exerts important functions of intracellular protein processing and transportation. Circulating GP73 has recently been suggested as a prognostic marker following resection of hepatocellular carcinoma (HCC) but its role in the context of BTC has remained unknown. In this study, we evaluate a potential role of circulating GP73 as a novel biomarker in patients with resectable BTC. Methods: GP73 serum levels were measured by immunoassay in n = 97 BTC and n = 40 HCC patients as well as n = 31 healthy controls. Results were correlated with clinical data. Results: Serum GP73 levels were significantly elevated in BTC patients compared to healthy controls but lower compared to HCC patients. The combination of GP73/CA19-9 showed a sensitivity and specificity of 83.5% and 90.3% regarding the differentiation of BTC patients and healthy controls. BTC patients with baseline GP73 levels above the ideal cut-off value (42.47 ng/mL) showed a significantly reduced median overall survival (193 days) compared to patients with preoperative GP73 levels below this cut-off (882 days). These results were confirmed in uni- and multivariate Cox-regression analysis including several clinicopathological parameters such as age, ECOG performance status, tumor stage as well as established tumor markers and parameters of liver and kidney function. Conclusions: GP73 represents a previously unrecognized biomarker in the patients with resectable BTC that identifies patients with an impaired postoperative outcome. If larger clinical trials confirmed these findings, measurement of GP73 serum levels might become a novel tool in the challenging preoperative stratification process of patients with resectable BTC.

Using the Global Trigger Tool in surgical and neurosurgical patients: A feasibility study

BACKGROUND

The Global Trigger Tool (GTT) has become a worldwide used method for estimating adverse events through a retrospective patient record review. However, little is known about the facilitators and the challenges in the GTT-implementation process. Thus, this study followed two aims: First, to apply a comprehensive set of feasibility criteria to qualitatively and systematically assess the GTT-implementation process in three departments of German university hospitals. Second, to identify the facilitators and the obstacles met in the GTT-implementation process and to derive recommendations for supporting other hospitals in implementing the GTT in clinical practice.

METHODS

The study used a qualitative documentary method based on process documentation, with written and verbal feedback from the reviewer, as well as evaluating the study sites during the implementation process. The study was conducted in three departments, each in a different German university hospital. The authors applied a comprehensive set of 22 feasibility criteria assessing the level of challenge in GTT implementation. The results were synthesized and they focused on the facilitators and the challenges.

RESULTS

Of these 22 feasibility criteria, nine were assessed as a low-level challenge, eleven regarded as a moderate-level challenge, and two with a problematic level of challenge. In particular, the lack of time and staff resources, the quality of the information in the patient records, organizational procedures, and local issues, posed major challenges in the implementation process. By contrast, the use of local coordinators and an external expert made important contributions to the GTT implementation.

CONCLUSIONS

Considering the facilitators and the obstacles beforehand may help with the implementation of the GTT in routine practice. In particular, early and effective planning can reduce or prevent critical challenges in terms of time, staff resources, and organizational aspects.

3D-Printed Replica and Porcine Explants for Pre-Clinical Optimization of Endoscopic Tumor Treatment by Magnetic Targeting

Simple Summary

Animal models are often needed in cancer research but some research questions may be answered with other models, e.g., 3D replicas of patient-specific data, as these mirror the anatomy in more detail. We, therefore, developed a simple eight-step process to fabricate a 3D replica from computer tomography (CT) data using solely open access software and described the method in detail. For evaluation, we performed experiments regarding endoscopic tumor treatment with magnetic nanoparticles by magnetic hyperthermia and local drug release. For this, the magnetic nanoparticles need to be accumulated at the tumor site via a magnetic field trap. Using the developed eight-step process, we printed a replica of a locally advanced pancreatic cancer and used it to find the best position for the magnetic field trap. In addition, we described a method to hold these magnetic field traps stably in place. The results are highly important for the development of endoscopic tumor treatment with magnetic nanoparticles as the handling and the stable positioning of the magnetic field trap at the stomach wall in close proximity to the pancreatic tumor could be defined and practiced. Finally, the detailed description of the workflow and use of open access software allows for a wide range of possible uses.

Abstract

Background: Animal models have limitations in cancer research, especially regarding anatomy-specific questions. An example is the exact endoscopic placement of magnetic field traps for the targeting of therapeutic nanoparticles. Three-dimensional-printed human replicas may be used to overcome these pitfalls. Methods: We developed a transparent method to fabricate a patient-specific replica, allowing for a broad scope of application. As an example, we then additively manufactured the relevant organs of a patient with locally advanced pancreatic ductal adenocarcinoma. We performed experimental design investigations for a magnetic field trap and explored the best fixation methods on an explanted porcine stomach wall. Results: We describe in detail the eight-step development of a 3D replica from CT data. To guide further users in their decisions, a morphologic box was created. Endoscopies were performed on the replica and the resulting magnetic field was investigated. The best fixation method to hold the magnetic field traps stably in place was the fixation of loops at the stomach wall with endoscopic single-use clips. Conclusions: Using only open access software, the developed method may be used for a variety of cancer-related research questions. A detailed description of the workflow allows one to produce a 3D replica for research or training purposes at low costs.

Comparative Analysis of Circulating Biomarkers for Patients Undergoing Resection of Colorectal Liver Metastases

Surgical tumor resection has evolved as a potentially curative therapy for patients with resectable colorectal liver metastases (CRLM). However, disease recurrence is common and the available preoperative stratification strategies are often imprecise to identify the ideal candidates for surgical treatment, resulting in a postoperative 5-year survival rate below 50%. Data on the prognostic value of CEA, CA19-9 and other common laboratory parameters after CRLM resection are scarce and partly inconclusive. Here, we analyzed the prognostic potential of circulating CEA and CA19-9 in comparison to other standard laboratory markers in resectable CRLM patients. Serum levels of tumor markers and other laboratory parameters were analyzed in 125 patients with CRLM undergoing tumor resection at a tertiary referral center. Results were correlated with clinical data and outcome. Both tumor markers were significantly elevated in CRLM patients compared to healthy controls. Interestingly, elevated levels of CEA, CA19-9 and C-reactive protein (CRP) were associated with an unfavorable prognosis after CRLM resection in Kaplan-Meier curve analysis. However, only CEA and not CA19-9 or CRP serum levels were an independent prognostic marker in multivariate Cox regression analysis. Our data demonstrate that circulating levels of CEA rather than CA19-9 might be a valuable addition to the existing preoperative stratification algorithms to identify patients with a poor prognosis after CRLM resection.

Magnetic Fluid Hyperthermia as Treatment Option for Pancreatic Cancer Cells and Pancreatic Cancer Organoids

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a cancer with a meager prognosis due to its chemotherapy resistance. A new treatment method may be magnetic fluid hyperthermia (MFH). Magnetoliposomes (ML), consisting of superparamagnetic iron oxide nanoparticles (SPION) stabilized with a phospholipid-bilayer, are exposed to an alternating magnetic field (AMF) to generate heat. To optimize this therapy, we investigated the effects of MFH on human PDAC cell lines and 3D organoid cultures.

MATERIAL AND METHODS

ML cytotoxicity was tested on Mia PaCa-2 and PANC-1 cells and on PDAC 3D organoid cultures, generated from resected tissue of patients. The MFH was achieved by AMF application with an amplitude of 40-47 kA/m and a frequency of 270 kHz. The MFH effect on the cell viability of the cell lines and the organoid cultures was investigated at two different time points. Clonogenic assays evaluated the impairment of colony formation. Altering ML set-ups addressed differences arising from intra- vs extracellular ML locations.

RESULTS

Mia PaCa-2 and PANC-1 cells showed no cytotoxic effects at ML concentrations up to 300 µg(Fe)/mL and 225 µg(Fe)/mL, respectively. ML at a concentration of 225 µg(Fe)/mL were also non-toxic for PDAC organoid cultures. MFH treatment using exclusively extracellular ML presented the highest impact on cell viability. Clonogenic assays demonstrated remarkable impairment as long-term outcome in MFH-treated PDAC cell lines. Additionally, we successfully treated PDAC organoids with extracellular ML-derived MFH, resulting in notably reduced cell viabilities 2h and 24 h post treatment. Still, PDAC organoids seem to partly recover from MFH after 24 h as opposed to conventional 2D-cultures.

CONCLUSION

Treatment with MFH strongly diminished pancreatic cancer cell viability in vitro, making it a promising treatment strategy. As organoids resemble the more advanced in vivo conditions better than conventional 2D cell lines, our organoid model holds great potential for further investigations.

Minimally Invasive Thoracoabdominal Esophagectomy Is Superior to Minimally Invasive Gastrectomy in Terms of Health-Related Quality of Life

Background and Objectives: There are two operative approaches for adenocarcinomas of the esophagogastric junction: thoracoabdominal esophagectomy or transhiatal extended gastrectomy. Both procedures can be performed minimally invasively. Dependent on the exact localization of the tumor, both approaches are feasible. Aim of this study was to compare the health-related quality of life (HRQOL) of patients after minimally invasive esophagectomy (MIE) with patients who underwent minimally invasive gastrectomy (MIG). Methods: All patients who underwent MIE or gastrectomy for malignoma since 2014 were identified from our clinical database. The identified patients were contacted and asked to fill out a quality of life questionnaire (QLQ) for general and gastrointestinal QOL (European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-OG25). Results: Global HRQOL scores were higher in patients after MIE than after MIG. After MIE, global HRQOL scores were close to the control population. In cancer-specific syndromes, patients after MIE reported lower symptom scores for financial problems, eating, reflux, and eating with others than patients after MIG. Conclusion: In terms of HRQOL, MIE proved superior to MIG in long-term follow-up in this study. Patients after MIE reported a HRQOL close to that of a healthy reference population.

Circulating levels of microRNA193a-5p predict outcome in early stage hepatocellular carcinoma

While tumor resection and liver transplantation (LT) represent potentially curative therapeutic options for patients with early-stage hepatocellular carcinoma (HCC), the identification of the ideal surgical candidates has remained challenging. Just recently, miRNA-193a-5p was described as a tumor suppressor in murine and human HCC but only little is known about circulating miRNA-193a-5p in HCC patients. Here, we evaluated serum levels of miR-193a-5p by qPCR in 41 HCC patients undergoing tumor resection (n = 33) or LT (n = 8) and 20 controls. Circulating relative miR-193a-5p levels were significantly elevated in HCC patients compared to healthy controls. While relative miR-193a-5p levels were comparable between patients of different underlying disease etiology and tumor size, high relative miR-193a-5p levels were predictive for the patients' postoperative outcome, which was confirmed in uni- and multivariate Cox-regression analysis. As such, HCC patients with a preoperative relative miR-193a-5p level above the ideal cut-off value (3.57) had a median overall survival (OS) of only 451 days compared to 1158 days in patients with a relative miR-193a-5p level below this cut-off value. Our data support a novel function of miR-193a-5p as a biomarker in early-stage HCC patients that might help to identify the best surgical candidates in terms of postoperative outcome.

See (n)One, Do (n)One, Teach (n)One: Reality of Surgical Resident Training in Germany

Introduction

Due to technological changes, working time restrictions and the creation of specialized centers, surgical training has changed. A competence-based learning technique of surgical skills is the sub-step practice approach, which has been proven important in nationwide opinion surveys. The aim of this prospective multi-center trial was to determine the status quo of the sub-step concept in Germany.

Methods

Over 6 months, the voluntarily participating centers evaluated the following index procedures: laparoscopic cholecystectomy (LCHE), laparoscopic and open sigmoid resection, minimally invasive inguinal hernia repair, thyroid resection and pylorus-preserving pancreaticoduodenectomy (PPPD). Patients with private insurance were excluded. The detailed sub-steps were documented as well as the reason why these were not performed. In addition, an online survey regarding the sub-step concept was performed before and after the study.

Results

In total, 21 centers included 2969 surgical procedures in 2018 for final analyses. While 24.4% of the procedures were performed by residents, sub-steps were performed in 22.2%. LCHE was most often performed completely by residents (43.3%), and PPPD revealed the highest rate of performed sub-steps (43.3%). Reasons for not assisting sub-steps to residents were often organizational and other reasons. After an initial increase, the number of performed sub-steps decreased significantly during the second half of the survey. The opinion survey revealed a high importance of the sub-step concept. The number of resident procedures was overestimated, and the number of performed sub-steps was underestimated. After the study, these estimations were more realistic.

Conclusion

Even though the sub-step practice concept is considered highly important for surgical education, it needs to be put into practice more consequently. The current data suggest a low participation of surgical residents in the operating room, although the participating hospitals are most likely highly interested in surgical education, hence their voluntary participation. Conceptual changes and a control of surgical education are needed.

Electronic supplementary material

The online version of this article (10.1007/s00268-020-05539-6) contains supplementary material, which is available to authorized users.

Circulating levels of soluble urokinase plasminogen activator receptor predict outcome after resection of biliary tract cancer

Background & Aims

Surgical resection is the only potentially curative therapy for patients with biliary tract cancer (BTC), but 5-year survival rates after tumor resection have remained below 30%, corroborating the need for better stratification tools to identify the ideal surgical candidates. The soluble urokinase plasminogen activator receptor (suPAR) represents a mediator of inflammation and has been associated with distinct types of cancer. In this study, we evaluated a potential role of suPAR as a novel biomarker in patients undergoing BTC resection.

Methods

Tumor expression of uPAR was analyzed by immunohistochemistry in 108 BTC samples. Serum levels of suPAR were analyzed by ELISA in a training and validation cohort comprising a total of 117 patients with BTC and 76 healthy controls.

Results

High tumoral uPAR expression was associated with an adverse outcome after BTC resection. Accordingly, circulating levels of suPAR were significantly elevated in patients with BTC compared to healthy controls, as well as in patients with primary sclerosing cholangitis. Using a small training set, we established an optimal prognostic suPAR cut-off value of 3.72 ng/ml for patients with BTC. Importantly, preoperative suPAR serum levels above this cut-off value were associated with significantly impaired overall survival in both the training and validation cohort. Multivariate Cox-regression analysis including various clinicopathological parameters such as tumor stage, markers of inflammation and organ dysfunction, as well as tumor markers, revealed circulating suPAR levels as an independent prognostic marker following BTC resection. Finally, high preoperative suPAR levels were indicative of acute kidney injury after tumor resection.

Conclusion

Circulating suPAR represents a previously unrecognized biomarker in patients with resectable BTC, which might help to preoperatively identify the ideal candidates for liver surgery.

Lay summary

Surgical resection represents the only curative treatment option for patients with biliary tract cancer, but not all patients benefit to the same extent in terms of overall survival. Here, we provide evidence that serum levels of an inflammatory mediator (suPAR) are indicative of a patient's postoperative outcome and might thus help to identify the ideal surgical candidates.

•

Biliary tract cancer is associated with poor outcomes and increasing incidence.

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Surgical resection is the only potentially curative treatment option for patients with biliary tract cancer.

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The identification of ideal surgical candidates has remained challenging.

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Circulating suPAR represents a novel diagnostic and prognostic biomarker in resectable patients.

•

SuPAR might be useful to identify patients with biliary tract cancer who will benefit most from tumor resection.

What can we learn from other countries-lessons from the CAJC Happiness Report

Most countries have their own programs and requirements for surgical residency. To investigate the differences as well as the advantages and disadvantages of the programs and to explore the happiness of the residents in the different countries, the Surgical Working Group of “Young Surgeons” of the German Society for General and Visceral Surgery has designed a questionnaire. It focuses on three parts: structural and legal requirements, operating room (OR)- and non-OR-related content of the program, and contentment of the residents. In this opinion paper, first the results are shared by the description of the programs in nine different countries. It is shown that the requirements to become a surgeon differ highly between the different countries. Nonetheless, a structured curriculum, the possibility of feedback or a surgical mentoring program, and transparency regarding the OR schedule seem to be important to all residents to reach job satisfaction.

Modeling of magnetoliposome uptake in human pancreatic tumor cells in vitro

The internalization kinetics resulting from magnetic nanoparticle interactions with tumor cells play an important role in nanoparticle-based cancer treatment efficiency. Here, the uptake kinetics of magnetoliposomes (ML) into human pancreatic tumor cells (MiaPaCa-2 and BxPC-3) are quantified using magnetic particle spectrometry. A comparison to the uptake kinetics for healthy L929 cells is given. The experimental results are used for the development of an uptake kinetics model describing the three relevant internalization processes: ML adsorption to the cell membrane, endo- and exocytosis. By fitting of experimental data, the rate constant of each internalization process is determined enabling the prediction of internalized ML at any incubation time. After seven hours incubation time, MiaPaCa-2 internalized three times more ML than BxPC-3 and L929 cells even though their ML adsorption rate constants were nearly the same. As the interaction of the ML with the cell membrane is non-specific, the uptake kinetics mirror the individual cell response to ML internalization. With a new mathematical term to cover the exocytosis contribution to the overall internalization process, the extended uptake kinetics model offers new possibilities to analyze the specific internalization mechanism for other nanoparticle and cell types.

CXCR6 Inhibits Hepatocarcinogenesis by Promoting Natural Killer T- and CD4+ T-Cell-Dependent Control of Senescence

BACKGROUND & AIMS

Inflammation in the liver provokes fibrosis, but inflammation is also important for tumor surveillance. Inhibitors of chemokine pathways, such as CXCL16 and CXCR6 regulation of lymphocyte trafficking, are being tested as antifibrotic agents, but their effects on the development of hepatocellular carcinoma (HCC) are unclear. We assessed the roles of CXCR6-dependent immune mechanisms in hepatocarcinogenesis.

METHODS

C57BL/6J wild-type (WT) mice and CXCR6-deficient mice (Cxcr6^eGfp/eGfp) were given injections of diethylnitrosamine (DEN) to induce liver cancer and α-galactosylceramide to activate natural killer T (NKT) cells. We also performed studies in mice with conditional, hepatocyte-specific deletion of NEMO, which develop inflammation-associated liver tumors (Nemo^LPC-KO and Nemo^LPC-KOCxcr6^eGfp/eGfp mice). We collected liver tissues from patients with cirrhosis (n = 43), HCC (n = 35), and neither of these diseases (control individuals, n = 25). Human and mouse liver tissues were analyzed by histology, immunohistochemistry, flow cytometry, RNA expression arrays (from sorted hepatic lymphocytes), and matrix-assisted laser desorption/ionization imaging. Bone marrow was transferred from Cxcr6^eGfp/eGfp or WT mice to irradiated C57BL/6J mice, and spleen and liver cells were analyzed by flow cytometry. CD4⁺ T cells or NKT cells were isolated from the spleen and liver of CD45.1⁺ WT mice and transferred into CXCR6-deficient mice after DEN injection.

RESULTS

After DEN injection, CXCR6-deficient mice had a significantly higher tumor burden than WT mice and increased tumor progression, characterized by reduced intrahepatic numbers of invariant NKT and CD4⁺ T cells that express tumor necrosis factor and interferon gamma. Livers of Nemo^LPC-KOCxcr6^eGfp/eGfp mice had significantly more senescent hepatocytes than livers of Nemo^LPC-KO mice. In studies of bone-marrow chimeras, adoptive cell transfer experiments, and analyses of Nemo^LPC-KO mice, we found that NKT and CD4 T cells promote the removal of senescent hepatocytes to prevent hepatocarcinogenesis, and that this process required CXCR6. Injection of WT with α-galactosylceramide increased removal of senescent hepatocytes by NKT cells. We observed peritumoral accumulation of CXCR6-associated lymphocytes in human HCC, which appeared reduced compared with cirrhosis tissues.

CONCLUSIONS

In studies of mice with liver tumors, we found that CXCR6 mediated NKT-cell and CD4⁺ T-cell removal of senescent hepatocytes. Antifibrotic strategies to reduce CXCR6 activity in liver, or to reduce inflammation or modulate the immune response, should be tested for their effects on hepatocarcinogenesis.

Polypropylene mesh implantation for hernia repair causes myeloid cell-driven persistent inflammation

Polypropylene meshes that are commonly used for inguinal hernia repair may trigger granulomatous foreign body reactions. Here, we show that asymptomatic patients display mesh-associated inflammatory granulomas long after surgery, which are dominated by monocyte-derived macrophages expressing high levels of inflammatory activation markers. In mice, mesh implantation by the onlay technique induced rapid and strong myeloid cell accumulation, without substantial attenuation for up to 90 days. Myeloid cells segregated into distinct macrophage subsets with separate spatial distribution, activation profiles, and functional properties, showing a stable inflammatory phenotype in the tissue surrounding the biomaterial and a mixed, wound-healing phenotype in the surrounding stromal tissue. Protein mass spectrometry confirmed the inflammatory nature of the foreign body reaction, as characterized by cytokines, complement activation, and matrix-modulating factors. Moreover, immunoglobulin deposition increased over time around the implant, arguing for humoral immune responses in association with the cell-driven inflammation. Intravital multiphoton microscopy revealed a high motility and continuous recruitment of myeloid cells, which is partly dependent on the chemokine receptor CCR2. CCR2-dependent macrophages are particular drivers of fibroblast proliferation. Thus, our work functionally characterizes myeloid cell-dependent inflammation following mesh implantation, thereby providing insights into the dynamics and mechanisms of foreign body reactions to implanted biomaterials.

Combining Bulk Temperature and Nanoheating Enables Advanced Magnetic Fluid Hyperthermia Efficacy on Pancreatic Tumor Cells

Many efforts are made worldwide to establish magnetic fluid hyperthermia (MFH) as a treatment for organ-confined tumors. However, translation to clinical application hardly succeeds as it still lacks of understanding the mechanisms determining MFH cytotoxic effects. Here, we investigate the intracellular MFH efficacy with respect to different parameters and assess the intracellular cytotoxic effects in detail. For this, MiaPaCa-2 human pancreatic tumor cells and L929 murine fibroblasts were loaded with iron-oxide magnetic nanoparticles (MNP) and exposed to MFH for either 30 min or 90 min. The resulting cytotoxic effects were assessed via clonogenic assay. Our results demonstrate that cell damage depends not only on the obvious parameters bulk temperature and duration of treatment, but most importantly on cell type and thermal energy deposited per cell during MFH treatment. Tumor cell death of 95% was achieved by depositing an intracellular total thermal energy with about 50% margin to damage of healthy cells. This is attributed to combined intracellular nanoheating and extracellular bulk heating. Tumor cell damage of up to 86% was observed for MFH treatment without perceptible bulk temperature rise. Effective heating decreased by up to 65% after MNP were internalized inside cells.

[What Do Young Surgeons Want? Modern Requirements for Senior Surgeons]

Due to the shortage of surgical specialists, the question arises as to what surgical residents want and how the fascination of general and visceral surgery may be highlighted. The surgical working group "Young Surgeons" (CAJC) of the German Society for General and Visceral Surgery (DGAV) has organised and subdivided the aspects of an attractive surgical workplace and provides solutions. On the one hand, there is the structured and transparent residency which includes a defined curriculum, assistance of sub-steps during surgery, residency dialogues held on a regular basis, logbooks, the possibility of training and simulation in the clinic as well as permission to participate in further education and training. This has to go hand in hand with a "livable surgery" that is characterised by the compatibility of family and work, better planning of the routine in the clinic, a positive feedback culture, work-life balance, new work (time) models and more time for teaching and research. For many of these aspects, the head of surgery has to be the central role model to initiate structural changes in the clinic, especially as many of these key points may be easily implemented. In this way, the attraction of surgery can be rapidly enhanced and a "livable surgery" may be lived.

Establishment of a biophysical model to optimize endoscopic targeting of magnetic nanoparticles for cancer treatment

Superparamagnetic iron oxide nanoparticles (SPION) may be used for local tumor treatment by coupling them to a drug and accumulating them locally with magnetic field traps, that is, a combination of permanent magnets and coils. Thereafter, an alternating magnetic field generates heat which may be used to release the thermosensitively bound drug and for hyperthermia. Until today, only superficial tumors can be treated with this method. Our aim was to transfer this method into an endoscopic setting to also reach the majority of tumors located inside the body. To find the ideal endoscopic magnetic field trap, which accumulates the most SPION, we first developed a biophysical model considering anatomical as well as physical conditions. Entities of choice were esophageal and prostate cancer. The magnetic susceptibilities of different porcine and rat tissues were measured with a superconducting quantum interference device. All tissues showed diamagnetic behavior. The evaluation of clinical data (computed tomography scan, endosonography, surgical reports, pathological evaluation) of patients gave insight into the topographical relationship between the tumor and its surroundings. Both were used to establish the biophysical model of the tumors and their surroundings, closely mirroring the clinical situation, in which we could virtually design, place and evaluate different electromagnetic coil configurations to find optimized magnetic field traps for each tumor entity. By simulation, we could show that the efficiency of the magnetic field traps can be enhanced by 38-fold for prostate and 8-fold for esophageal cancer. Therefore, our approach of endoscopic targeting is an improvement of the magnetic drug-targeting setups for SPION tumor therapy as it holds the possibility of reaching tumors inside the body in a minimal-invasive way. Future animal experiments must prove these findings in vivo.

Functional Liver Recovery After Bariatric Surgery--a Prospective Cohort Study with the LiMAx Test

BACKGROUND

Bariatric surgery provides long-term weight loss and improvement of obesity-associated diseases such as nonalcoholic steatohepatitis (NASH). Histologic improvement of NASH has been reported in some studies after bariatric surgery. This study was designed to assess the liver function in obese patients as well as its recovery after bariatric surgery with a noninvasive test method.

METHODS

In a prospective cohort study from October 2011 to May 2014, morbidly obese individuals receiving bariatric surgery were investigated for functional liver recovery (n = 34). Liver function was determined by the LiMAx test (enzymatic capacity of cytochrome P450 1A2) preoperatively, 6 and 12 months postoperatively. Liver biopsy specimens were obtained from 18 participants and classified according to the nonalcoholic fatty liver disease (NAFLD) activity score (NAS).

RESULTS

The mean age of participants was 44 years, and the mean body mass index (BMI) was 52 kg/m(2). The mean percent excess BMI loss (%EBMIL) was 53 % after 6 months and 68 % after 1 year. Mean liver function capacity increased significantly from 255 μg/kg/h preoperative to 324 μg/kg/h after 6 months and 342 μg/kg/h after 12 months. A negative correlation was observed between %EBMIL and alteration of liver function capacity in the first 6 months. Finally, the median NAS showed a negative correlation with liver function capacity.

CONCLUSIONS

Bariatric surgery leads to a significant functional recovery of the liver. An initial marked weight loss may negatively influence functional liver recovery.

Primary anastomosis with a defunctioning stoma versus Hartmann's procedure for perforated diverticulitis--a comparison of stoma reversal rates

PURPOSE

The ideal treatment of patients with perforated diverticulitis is still controversial. Hartmann's procedure has been the treatment of choice for decades, but primary anastomosis with a defunctioning stoma has become an accepted alternative. The aim of this study was to evaluate the stoma reversal rates after these two surgical strategies.

METHODS

A retrospective review of the data from patients with perforated sigmoid diverticulitis between 2002 and 2011 undergoing a Hartmann's procedure (HP) versus a primary anastomosis with a defunctioning stoma (PA) was performed. Additionally, patients were contacted by mail or telephone in March 2012 using a standardized questionnaire.

RESULTS

A total of 98 patients were identified: 72 undergoing HP and 26 patients receiving PA. The median follow-up time was 63 months (range 4-118). Whilst 85 % of patients with PA have had their stoma reversed, only 58 % of patients with an HP had a stoma reversal (p = 0.046). The median period until stoma reversal was significantly longer for HP (19 weeks) than for PA (12 weeks; p = 0.03). The 30-day mortality for PA was 12 % as opposed to 25 % for HP (p = 0.167). According to the Clavien-Dindo classification, surgical complications occurred significantly less frequently in patients with PA (p = 0.014).

CONCLUSION

The stoma reversal rates for PA are significantly higher than for HP. Thus, depending on the overall clinical situation, primary resection and anastomosis with a proximal defunctioning stoma might be the optimal procedure for selected patients with perforated diverticular disease.