[Pancreatic Transplantation: 2. Surgical technique and post-operative complications]

Fractal Behavior of the Pancreatic β-Cell Near the Percolation Threshold: Effect of the KATP Channel On the Electrical Response

The molecular system built with true chemical bonds or strong molecular interaction can be described using conceptual mathematical tools. Modeling of the natural generated ionic currents on the human pancreatic β-cell activity had been already studied using complicated analytical models. In our present contribution, we prove the same using our simple electrical model. The ionic currents are associated with different proteins membrane channels (K-Ca, K(v), K(ATP), Ca(v)-L) and Na/Ca Exchanger (NCX). The proteins are Ohmic conductors and are modeled by conductance randomly distributed. Switches are placed in series with conductances in order to highlight the channel activity. However, the KATP channel activity is stimulated by glucose, and the NCX's conductance change according to the intracellular calcium concentration. The percolation threshold of the system is calculated by the fractal nature of the infinite cluster using the Tarjan's depth-first-search algorithm. It is shown that the behavior of the internal concentration of Ca(2+) and the membrane potential are modulated by glucose. The results confirm that the inhibition of KATP channels depolarizes the membrane and increases the influx of [Ca(2+)]i through NCX and Ca(v)-L channel for high glucose concentrations.

[Total pancreas sampling and transplantation]

Pancreas removal and transplantation consists in three main steps: sampling, preparation of the transplant with reconstruction of vessels and finally transplantation. Sampling requires good anatomical knowledge and perfect synchronization between hepatic surgeons so as to ensure adequate dissection of liver and pancreas vessels: portal vein, splenic, upper mesenteric and hepatic arteries. Washing and conservation of organs require the use of University of Wisconsin solution. The preparation of the pancreatic graft consists in reconstructing the unique arterial axis using an iliac arterial fork sutured with upper mesenteric and splenic arteries. The portal vein is lengthened step by step, avoiding venous patch source of thrombosis. The transplantation is realized in the right flank, on the aorta and the vena cava near the iliac crossroads. The digestive anastomosis is performed between duodenum of the transplant and first bowel hail of the recipient. It must be done carefully to avoid any risk of pancreas fistula.