Clipping prevents perforation in large, flat polyps.

Aim: To determine if prophylactic clipping of post-polypectomy endoscopic mucosal resection (EMR) mucosal defects of large, flat, right sided polyps prevents perforations.

Methods: IRB approved review of all colonoscopies, and prospective data collection of grasp and snare EMR performed by 2 endoscopists between January 1, 2010 and March 31, 2014 in a community ambulatory endoscopy center. The study consisted of two phases.

Managing a surgical exsanguination emergency in the operating room through simulation: an interdisciplinary approach.

Objective: Operating room (OR) emergencies, such as fire, anaphylaxis, cardiac arrest, and exsanguination, are infrequent, but high-risk situations that can result in significant morbidity and mortality. An exsanguination scenario involving a pregnant trauma patient in the OR was developed for surgery residents with the objectives of improving overall team performance when activating an emergency response system, identifying a team leader, initiating an exsanguination protocol, following advanced cardiac life support guidelines, and recognizing the mother as the first patient.

Study Design: During 6 months, 171 OR staff members of the Hospital of the University of Pennsylvania participated in a prospective study in which randomly selected groups of surgery residents, anesthesia residents, and perioperative nurses were trained in a simulated exsanguination and cardiac arrest emergency.

Engineering and characterization of human manganese superoxide dismutase mutants with high activity and low product inhibition.

Human manganese superoxide dismutase is a mitochondrial metalloenzyme that is involved in protecting aerobic organisms against superoxide toxicity, and has been implicated in slowing tumor growth. Unfortunately, this enzyme exhibits strong product inhibition, which limits its potential biomedical applications. Previous efforts to alleviate human manganese superoxide dismutase product inhibition utilized rational protein design and site-directed mutagenesis.

Amino acid substitution at the dimeric interface of human manganese superoxide dismutase.

The side chains of His30 and Tyr166 from adjacent subunits in the homotetramer human manganese superoxide dismutase (Mn-SOD) form a hydrogen bond across the dimer interface and participate in a hydrogen-bonded network that extends to the active site. Compared with wild-type Mn-SOD, the site-specific mutants H30N, Y166F, and the corresponding double mutant showed 10-fold decreases in steady-state constants for catalysis measured by pulse radiolysis. The observation of no additional effect upon the second mutation is an example of cooperatively interacting residues.

Catalytic and structural effects of amino acid substitution at histidine 30 in human manganese superoxide dismutase: insertion of valine C gamma into the substrate access channel.

Catalysis of the disproportionation of superoxide by human manganese superoxide dismutase (MnSOD) is characterized by an initial burst of catalysis followed by a much slower region that is zero order in superoxide and due to a product inhibition by peroxide anion. We have prepared site-specific mutants with replacements at His30, the side chain of which lies along the substrate access channel and is about 5.8 A from the metal.