The measurement of proton relaxation time & in a series of purine and pyrimidine 5'-nucleotides has been carried out to investigate their conformation in dilute neutral aqueous solutions.The interpretation of relaxation data has been performed with the help of computer calculations taking into account the different conformers of the ribose ring and of the exocyclic group. It has been found that all nucleotides under study show nearly the same preferential orientations of the base defined by Yo = 70" 10" in the syn range. A more elaborate treatment, using an angular distribution derived from calculated potentials on 5'-GMP gives theoretical relaxation times in close agreement with experimental ones.
Machine learning approaches using intravascular optical coherence tomography (OCT) to predict fractional flow reserve (FFR) have not been investigated. Both OCT and FFR data were obtained for left anterior descending artery lesions in 125 patients. Training and testing groups were partitioned in the ratio of 5:1. The OCT-based machine learning-FFR was derived for the testing group and compared with wire-based FFR in terms of ischemia diagnosis (FFR ≤ 0.8). The OCT-based machine learning-FFR showed good correlation (r = 0.853, P < 0.001) with the wire-based FFR. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the OCT-based machine learning-FFR for the testing group were 100%, 92.9%, 87.5%, 100%, and 95.2%, respectively. The OCT-based machine learning-FFR can be used to simultaneously acquire information on both image and functional modalities using one procedure, suggesting that it may provide optimized treatments for intermediate coronary artery stenosis.
2 mg) for 2 hr at room temperature gave 5 exclusively on the basis of its NMR spectrum.Methyl 4,6-O-Benzylidene-2-C-(dibenzoyl)methyl-2,3-dideoxy-3-nitro-a-D-mannopyranoside (9). Treatment of 2 (58.6 mg) with dibenzoylmethane (49 mg, ca. 0.22 mmol) under the conditions used to prepare 8 gave a pure crystalline residue of 9 (88 mg, 85%). The residue (176 mg) was recrystallized from ethanol: yield 149 mg (72%); mp 214°d ec; [a]20D -262°(c 1, CHCla); ir (KBr) 1690 (CO), 1550 cm'1 (N02).
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