Lanthanide Tagging of Oligonucleotides to Nucleobase for Paramagnetic NMR.

Although lanthanide tags, which have large anisotropic magnetic susceptibilities, have already been introduced to enrich NMR parameters by long-range pseudoconact shifts (PCSs) and residual dipolar couplings (RDCs) of proteins, their application to nucleotides has so far been limited to one previous report, due to the high affinities of lanthanides for the phosphodiester backbone of nucleotides and difficult organic synthesis. Herein, we report successful attachment of a lanthanide tag to a chemically synthesized oligonucleotide via a disulfide bond. NMR experiments reveal PCSs of up to 1 ppm and H-H RDCs of up to 8 Hz at 950 MHz. Although weaker magnetic alignment was achieved than with proteins, the paramagnetic data could be fitted to the known structure of the DNA, taking the mobility of the tag into account. While further rigidification of the tag is desirable, this tag could also be used to measure heteronuclear RDCs of 13 C,15 N-labeled chemically synthesized DNA and RNA.

Prognostic value of coronary computed tomography angiography during 5 years of follow-up in patients with suspected coronary artery disease.

AIMS: Coronary computed tomography angiography (CCTA) has a high accuracy for detection of obstructive coronary artery disease (CAD). Several studies also showed a good predictive value for subsequent cardiac events. However, the follow-up period of these studies was limited to ~2 years and long-term follow-up data on prognosis out to 5 years are very limited. METHODS AND RESULTS: This study is based on 1584 patients with suspected CAD undergoing CCTA between December 2003 and November 2006. Among other CCTA parameters, the total plaque score defined as number of abnormal segments (having either a non-obstructive plaque or a stenosis) and the most severe stenosis were recorded. The primary endpoint was a composite of death and non-fatal myocardial infarction. Revascularization procedures later than 90 days after the CT study were assessed as secondary endpoints. During a median follow-up of 5.6 years (IQR: 5.1-6.3 years) 61 patients suffered death or myocardial infarction and 52 underwent late revascularization. The severity of CAD and the total plaque score were the best predictors of death and non-fatal myocardial infarction, both significantly improving prediction over standard clinical risk scores (multivariate c-index 0.60 and 0.66, respectively, P = 0.002 and <0.0001, respectively). The annual event rate ranged from 0.24% for patients with no CAD to 1.1% for patients with obstructive CAD and 1.5% for patients with CAD and extensive plaque load (>5 segments). Both parameters also improved prediction of need for subsequent revascularization (c-index 0.72 and 0.63, respectively, P < 0.0001 and P = 0.0013, respectively). CONCLUSION: Data from CCTA predict both death and myocardial infarction as well as need for subsequent revascularizations out to 5 years. CCTA imaging may be a valuable tool in the assessment of long-term prognosis in patients with suspected CAD.