Ischemic Preconditioning Decreases Laparoscopy Induced Oxidative Stress in the Liver

Experimental studies indicate that oxidative stress during and after laparoscopic surgery may cause liver ischemia-reperfusion injury. The aim of the study was to assess the effect of ischemic preconditioning against liver damage during pneumoperitoneum on oxidative stress. Twenty one New Zealand rabbits were divided into three groups of seven animals. Control group (C) rabbits received anesthesia for 60 min alone; 15 mm Hg intra-abdominal pressure with CO2 for 60 min was used in the pneumoperitoneum group animals (PNP); and 15-min insufflation and 10-min desuflation followed by 60-min pneumoperitoneum were used in the ischemic preconditioning group animals (IP). Venous blood samples were obtained at different time points to measure lipid hydroperoxide, glutathione reductase and total antioxidant status as indicators of increased oxidative stress. Aspartate transaminase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels were evaluated as indicators of hepatocellular injury. The Kruskal-Wallis and Mann-Whitney U tests were used on statistical analysis. Elevated intra-abdominal pressure was found to produce significant increase in lipid hydroperoxide at the end of pneumoperitoneum and 30 min after desuflation in comparison with pre-insufflation period, and with both C and IP groups at the same time points. Total antioxidant status level decreased significantly in the PNP group at 24 h of desuflation. At 24h of desuflation, the AST, ALT and LDH levels were significantly increased in the PNP group in comparison with the levels measured before induction of anesthesia, and with the C and IP groups. Study results demonstrated that ischemic preconditioning prevented hepatocyte injury and oxidative stress during CO2 pneumoperitoneum

UV/IR duality in noncommutative quantum field theory

We review the construction of renormalizable noncommutative euclidean phi(4)-theories based on the UV/IR duality covariant modification of the standard field theory, and how the formalism can be extended to scalar field theories defined on noncommutative Minkowski space.Comment: 12 pages; v2: minor corrections, note and references added; Contribution to proceedings of the 2nd School on "Quantum Gravity and Quantum Geometry" session of the 9th Hellenic School on Elementary Particle Physics and Gravity, Corfu, Greece, September 13-20 2009. To be published in General Relativity and Gravitatio

Duality covariant quantum field theory on noncommutative Minkowski space

We prove that a scalar quantum field theory defined on noncommutative Minkowski spacetime with noncommuting momentum coordinates is covariant with respect to the UV/IR duality which exchanges coordinates and momenta. The proof is based on suitable resonance expansions of charged noncommutative scalar fields in a background electric field, which yields an effective description of the field theory in terms of a coupled complex two-matrix model. The two independent matrix degrees of freedom ensure unitarity and manifest CT-invariance of the field theory. The formalism describes an analytic continuation of the renormalizable Grosse-Wulkenhaar models to Minkowski signature.Comment: 32 pages; v2: Typos corrected; v3: Further typos corrected - Final version to appear in JHE

Residuated Kleene algebras

We show that there is no finitely axiomatizable class of algebras that would serve as an analogue to Kozen’s class of Kleene algebras if we include the residuals of composition in the similarity type of relation algebras