Anesthesia Adverse Events Voluntarily Reported in the Veterans Health Administration and Lessons Learned.

Background: Anesthesia providers have long been pioneers in patient safety. Despite remarkable efforts, anesthesia errors still occur, resulting in complications, injuries, and even death. The Veterans Health Administration (VHA) National Center of Patient Safety uses root cause analysis (RCA) to examine why system-related adverse events occur and how to prevent future similar events.

Environmental Temperature Drastically Affects Flexural Fatigue Resistance of Nickel-titanium Rotary Files.

Introduction: The aim of the present study was to analyze how a low environmental temperature can affect the fatigue life of instruments made by different types of heat-treated nickel-titanium alloys.

Methods: The flexural cyclic fatigue of 40 new specimens for each of the following systems was tested for cyclic fatigue resistance: ProTaper Universal F2 (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold F2 (Dentsply Tulsa Dental Specialties, Tulsa, OK), Twisted Files SM2 (SybronEndo, Orange, CA), Mtwo #25.06 (VDW, Munich, Germany), and Vortex Blue #30.

Theoretical QM/MM studies of enzymatic pericyclic reactions.

The chorismate to prephenate enzyme catalyzed reaction has been used in this review as the conduit to show different theoretical approaches that have been used over the years in our laboratory to explain its molecular mechanism. This pericyclic reaction has the advantage that other protein scaffolds such as catalytic antibodies or some promiscuous enzymes present certain chorismate mutase activity. The obtained results on all these protein environments, by comparison with the uncatalyzed reaction in solution, have been used to propose, as a general conclusion, that the origin of enzyme catalysis is in the relative electrostatic stabilization of the transition state with respect to the Michaelis complex.

Mechanism and plasticity of isochorismate pyruvate lyase: a computational study.

The isochorismate pyruvate lyase (IPL) from Pseudomonas aeruginosa, designated as PchB, catalyzes the transformation of isochorismate into pyruvate and salicylate, but it also catalyzes the rearrangement of chorismate into prephenate, suggesting that both reactions may proceed by a pericyclic mechanism. In this work, molecular dynamics simulations employing hybrid quantum mechanics/molecular mechanics methods have been carried out to get a detailed knowledge of the reaction mechanism of PchB. The results provide a theoretical rate constant enhancement by comparison with the reaction in solution, in agreement with the experimental data, and confirm the pericyclic nature of the reaction mechanism.

Computational design of biological catalysts.

The purpose of this tutorial review is to illustrate the way to design new and powerful catalysts. The first possibility to get a biological catalyst for a given chemical process is to use existing enzymes that catalyze related reactions. The second possibility is the use of immune systems that recognize stable molecules resembling the transition structure of the target reaction.