P53 levels in the evaluation of malignant/benign pancreaticobiliary disease: hope or hype?
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Antibodies↗
Biomedical subjects
C E Gessner
Publications and source records attributed to C E Gessner.
Novel methods for endoscopic training.
The development of past, present, and future endoscopic training methods is described. A historical perspective of endoscopy training guidelines and devices is used to demonstrate support for the use of novel endoscopic training techniques. Computer simulation of endoscopy, interactive learning, and virtual reality applications in endoscopy and surgery are reviewed. The goals of endoscopic simulation and challenges facing investigators in this field are discussed, with an emphasis on current and future research.
Computer Simulation↗
pH effects in the spontaneous reactivation of phosphinylated acetylcholinesterase.
Previous studies on the spontaneous reactivation of phosphorylated and phosphonylated cholinesterases report bell-shaped curves with reaction rate maxima between pH values of 7 and 9. By way of contrast, we found reactivation rate minima in the same pH region for a phosphinylated bovine erythrocyte acetylcholinesterase and three phosphinylated eel acetylcholinesterases. To further elucidate these observations, eel acetylcholinesterase was inhibited with racemic 4-nitrophenyl ethyl(phenyl)phosphinate. The spontaneous reactivation of the inhibited enzyme over the pH range 6.00 to 9.00 was monitored following 1. both inhibition and spontaneous reactivation at the same pH, and 2. inhibition at pH 7.60 followed by spontaneous reactivation at the selected pH. The combined plots of both studies gave overlapping pH curves with minima around pH 7.60. The results indicate that the minima in the rates of the spontaneous reactivation of phosphinylated acetylcholinesterases are not the consequence of a pH-controlled change in the relative inhibition rates of the P(+)- and P(-)-enantiomers participating in the inhibition reaction. Our results suggest that the orientation of the phosphinyl group in the active site of phosphinylated acetylcholinesterase is quite different from that of the inhibitor groups in phosphonylated or phosphorylated enzyme.
Acetylcholinesterase↗