Dynamic nuclear polarization on a hybridized hammerhead ribozyme: An explorative study of RNA folding and direct DNP with a paramagnetic metal ion cofactor.

While uniform isotope labeling of ribonucleic acids (RNA) can simply and efficiently be achieved by in-vitro transcription, the specific introduction of nucleotides in larger constructs is non-trivial and often ineffective. Here, we demonstrate how a medium-sized (67-mer), biocatalytically relevant RNA (hammerhead ribozyme, HHRz) can be formed by spontaneous hybridization of two differently isotope-labeled strands, each individually synthesized by in-vitro transcription. This allows on the one hand for a significant reduction in the number of isotope-labeled nucleotides and thus spectral overlap particularly under magic-angle spinning (MAS) dynamic nuclear polarization (DNP) NMR conditions, on the other hand for orthogonal C/N-labeling of complementary strands and thus for specific investigation of structurally or functionally relevant inter-strand and/or inter-stem contacts.

Sensor-based neuronavigation: evaluation of a large continuous patient population.

Objective: Navigation systems enable neurosurgeons to guide operations with imaging data. Sensor-based neuronavigation uses an electromagnetic field and sensors to measure the positions of the patient's brain anatomy and the surgical instruments. The aim of this investigation was to determine the accuracy level of sensor-based tracking in a large patient collection.