Laparoscopic versus robot-assisted surgery for median arcuate ligament syndrome

Background Median arcuate ligament syndrome (MALS) is an uncommon disorder characterized by postprandial abdominal pain, weight loss, and vomiting related to the compression of the celiac artery by the median arcuate ligament. This syndrome has been classically treated with an open surgical approach. More recently, laparoscopic and robotic approaches have been used. We present our outcomes with laparoscopic and robot-assisted treatment of MALS. Methods We performed a retrospective review of all patients treated for MALS from March 2006 to August 2012 at a single institution. Results A total of 16 patients with MALS were treated: 12 patients via a laparoscopic approach and 4 patients via a robot-assisted approach. Patient characteristics and comorbidities were similar between groups. We experienced no intraoperative or perioperative conversions, complications, or deaths. The mean operative time for the laparoscopic approach was significantly shorter than for the robotic approach (101.7 vs. 145.8 min; P = 0.02). However, we found no significant difference in length of hospital stay (1.7 vs. 1.3 days, P = 0.23). The mean length of follow-up for laparoscopically treated patients was 22.2 months and for robotically treated patients it was 20 months. Eight patients (67 %) in the laparoscopic group and two patients (50 %) in the robotic group had full resolution of their abdominal pain. Three patients in the laparoscopic group and two patients in the robotic group ceased chronic narcotic use after surgery. Conclusions Both laparoscopic and robotic approaches to MALS treatment can be performed with minimal morbidity and mortality. The laparoscopic approach was associated with a significantly shorter operative time. While innovative, the true advantages to robot-assisted MALS surgery are yet to be seen

Monodisperse Metal Nanoparticle Catalysts: Synthesis, Characterizations, and Molecular Studies Under Reaction Conditions

We aim to develop novel catalysts that exhibit high activity, selectivity and stability under real catalytic conditions. In the recent decades, the fast development of nanoscience and nanotechnology has allowed synthesis of nanoparticles with well-defined size, shape and composition using colloidal methods. Utilization of mesoporous oxide supports effectively prevents the nanoparticles from aggregating at high temperatures and high pressures. Nanoparticles of less than 2 nm sizes were found to show unique activity and selectivity during reactions, which was due to the special surface electronic structure and atomic arrangements that are present at small particle surfaces. While oxide support materials are employed to stabilize metal nanoparticles under working conditions, the supports are also known to strongly interact with the metals through encapsulation, adsorbate spillover, and charge transfer. These factors change the catalytic performance of the metal catalysts as well as the conductivity of oxides. The employment of new in situ techniques, mainly high-pressure scanning tunneling microscopy (HPSTM) and ambient-pressure X-ray photoelectron spectroscopy (APXPS) allows the determination of the surface structure and chemical states under reaction conditions. HPSTM has identified the importance of both adsorbate mobility to catalytic turnovers and the metal substrate reconstruction driven by gaseous reactants such as CO and O-2. APXPS is able to monitor both reacting species at catalyst surfaces and the oxidation state of the catalyst while it is being exposed to gases. The surface composition of bimetallic nanoparticles depends on whether the catalysts are under oxidizing or reducing conditions, which is further correlated with the catalysis by the bimetallic catalytic systems. The product selectivity in multipath reactions correlates with the size and shape of monodisperse metal nanoparticle catalysts in structure sensitive reactions.close11111