Using molecular dynamics and quantum mechanics calculations to model fluorescence observables.

We provide a critical examination of two different methods for generating a donor-acceptor electronic coupling trajectory from a molecular dynamics (MD) trajectory and three methods for sampling that coupling trajectory, allowing the modeling of experimental observables directly from the MD simulation. In the first coupling method we perform a single quantum-mechanical (QM) calculation to characterize the excited state behavior, specifically the transition dipole moment, of the fluorescent probe, which is then mapped onto the configuration space sampled by MD. We then utilize these transition dipoles within the ideal dipole approximation (IDA) to determine the electronic coupling between the probes that mediates the transfer of energy.

Preoperative ultrasound measurements predict the feasibility of gallbladder extraction during transgastric natural orifice translumenal endoscopic surgery cholecystectomy.

Background: Extraction of a gallbladder through an endoscopic overtube during natural orifice translumenal endoscopic surgery (NOTES) transgastric cholecystectomy avoids potential injury to the esophagus. This study examined the rate of successful gallbladder specimen extraction through an overtube and hypothesized that preoperative ultrasound findings could predict successful specimen passage.

Methods: Gallbladder specimens from patients undergoing laparoscopic cholecystectomy were measured, and an attempt was made to pull the specimens through a commercially available overtube with an inner diameter of 16.

A comprehensive review of laparoscopic redo fundoplication.

Background: The last decade has seen the publication of multiple case series investigating the feasibility of performing reoperative fundoplications using laparoscopic techniques. Most of these studies are small and reflect initial experiences with the procedure. To examine the collective experience with laparoscopic redo fundoplications, a systematic review was conducted.

Fretting about FRET: correlation between kappa and R.

Molecular dynamics simulations were used to examine the structural dynamics of two fluorescent probes attached to a typical protein, hen egg-white lysozyme (HEWL). The donor probe (D) was attached via a succinimide group, consistent with the commonly-used maleimide conjugation chemistry, and the acceptor probe (A) was bound into the protein as occurs naturally for HEWL and the dye Eosin Y. The is found to deviate significantly from the theoretical value and high correlation between the orientation factor kappa and the distance R is observed.