Automated crystal mounting and data collection for protein crystallography.

To increase the efficiency of diffraction data collection for protein crystallographic studies, an automated system designed to store frozen protein crystals, mount them sequentially, align them to the X-ray beam, collect complete data sets, and return the crystals to storage has been developed. Advances in X-ray data collection technology including more brilliant X-ray sources, improved focusing optics, and faster-readout detectors have reduced diffraction data acquisition times from days to hours at a typical protein crystallography laboratory [1,2]. In addition, the number of high-brilliance synchrotron X-ray beam lines dedicated to macromolecular crystallography has increased significantly, and data collection times at these facilities can be routinely less than an hour per crystal. Because the number of protein crystals that may be collected in a 24 hr period has substantially increased, unattended X-ray data acquisition, including automated crystal mounting and alignment, is a desirable goal for protein crystallography. The ability to complete X-ray data collection more efficiently should impact a number of fields, including the emerging structural genomics field [3], structure-directed drug design, and the newly developed screening by X-ray crystallography [4], as well as small molecule applications.

Migration of an epicardial pacemaker to the pericardial space in an infant.

We report the case of a 4-month-old infant who was implanted with an epicardial ventricular pacing system at 6 days of age for the prolonged QT syndrome, who subsequently developed migration of the pulse generator to the pericardial space. Tracking of the pulse generator through the diaphragm and into the pericardium followed the route of the myocardial lead. The possibility of pulse generator migration, as well as disruption of the diaphragm and pericardium, should be considered by those who care for infants with implanted pacemakers.