Development of a dynamic model for ventral hernia mesh repair.

INTRODUCTION: The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall. MATERIALS AND METHODS: An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate. RESULTS: The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation. The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery. CONCLUSIONS: The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh.

Mannan-binding lectin (MBL) serum levels and post-operative infections.

Mannan-binding lectin (MBL) is a central component of the innate immune system. Here we investigated the role of MBL in surgical patients during the peri-operative phase. Basal and post-operative (days 1-3 post-surgery) serum samples were obtained prospectively from 156 patients undergoing major elective gastrointestinal surgery for malignant disease. In contrast to procalcitonin (a typical acute-phase protein), there was no significant difference in serum MBL between pre- and post-operative samples (P=0.62). Nevertheless, patients who developed post-operative infections showed significantly lower pre- and post-operative MBL levels than those who did not (P=0.013 and P=0.005, respectively). There was no significant difference in pre-operative procalcitonin between the two groups (P=0.56). We conclude (i) that serum MBL levels did not respond immediately to surgical trauma, and (ii) that lower MBL levels were associated with an increased occurrence of post-operative infections. Studies on larger patient groups are necessary, however, to assess the value of MBL measurements in identifying patients at risk of post-operative complications.

The prognostic inhomogeneity in pT3 rectal carcinomas.

To obtain data on locoregional recurrence and survival rates in prognostically inhomogeneous pT3 rectal carcinomas we analyzed the data on 853 patients of the Erlangen Registry for Colo-Rectal Carcinomas (ERCRC) and 600 patients of the Study Group for Colo-Rectal Carcinoma (SGCRC), stage I-III, treated by radical surgery alone. The category pT3 was subdivided according to the histological measurement of the maximal tumor invasion beyond the outer border of the muscularis propria: pT3a (up to 5 mm) and pT3b (more than 5 mm). In the ERCRC locoregional recurrence rates were 10.4% (95% confidence interval 6.0-14.6) for pT3a and 26.3% (20.6-31.6) for pT3b (P<0.0001). The cancer-related 5-year survival rates were 85.4% (80.6-90.5) for pT3a and 54.1% (48.5-60.5) for pT3b (P<0.0001). Lymph node negative pT3a and pT2 patients showed very similar 5-year survival rates (91.2% vs. 93.6%, respectively) as well as lymph node positive pT3a and pT2 patients (77.8% vs. 82.8%, respectively). In the SGCRC patients similar but statistically marginal differences between pT3a and pT3b tumors were observed. An extended pT classification (pT1, pT2, pT3a, pT3b, pT4) thus allows an improved prediction of outcome in rectal carcinoma patients. The subdivision of pT3 enables the identification of stage II patients (pT3a pNO) who might not benefit from adjuvant treatment.

Organ-preserving surgery for multicentric carcinoma of the pancreas.

Multicentric ductal carcinoma of the pancreas is usually treated by total pancreatectomy if surgically resectable. We present a case of metachrone, multicentric ductal carcinoma of the pancreas which was treated using an organ-preserving method. The reasons for doing so and the oncological and functional outcomes are discussed.

Culture of human peritoneum--a new method to measure the local cytokine response and the effect of immunomodulators.

The production of cytokines and chemokines, which are involved in cell activation and cell migration in native pieces of peritoneum, was measured to investigate immune regulatory reactions in the human peritoneum. The samples were obtained during abdominal surgery and cultured immediately afterwards. In order to test therapeutic options in vitro, the effect of IL-10 and IFN-gamma on the cytokine and chemokine production was also studied. The chemokine monocyte chemotactic protein-1 (MCP-1) was produced and released spontaneously. When lipopolysaccharide (LPS) was added, MCP-1 production increased. In addition, TNF-alpha production was induced by LPS. When IL-10 was added, LPS-stimulated TNF-alpha production was reduced towards baseline levels, LPS-induced MCP-1 production was reduced by 37%. IFN-gamma did not affect LPS-induced TNF-alpha and MCP-1 production, but increased baseline MCP-1 production. It can be concluded that short-time culture of native human peritoneum is a method to investigate peritoneal chemokine and cytokine production in patients undergoing abdominal surgery. Further studies are intended to detect cytokine patterns which identify patients at risk of developing peritonitis. In addition, the effects of medications may be tested in vitro in order to investigate options for preventive modulation of the peritoneal immune response in such patients.