BisPCBM is a molecule with two identical asymmetric addends bridging double bonds on the fullerene C60, giving rise to 58 nominal structural isomers. However, symmetry, chirality and steric hindrance reasons leave 19 possible isomers. Considering bond-type involved gives one C1 and one C2 isomers for the cis-3, trans-3 and trans-2 bonds; one C1 and two Cs isomers for the cis-2 and trans-4 bonds; two C1 isomers for the e bonds; one isomer of C2v and C2h symmetry for the trans-1 bonds. The mixture of bisPCBM was separated into individual components through high-pressure liquid chromatography. An initial single-pass HPLC treatment separated the mixture into 7 resolved fractions, of which three comprised a single isomer. A multi-stage peak-recycling HPLC process which involved several complimentary columns was devised to separate all isomers. The mixture was purified into 19 isomers (same number as possible isomers). Characterisation by UV-Vis absorption spectroscopy showed that some were similar, while others were different. This placed the isomers into 7 groups, two of which contained two isomers and the other five contained three isomers – the same in number and size for each bond-type as identified from the molecular structures, suggesting that there is a link between the shape of the spectra and the bond type of the isomer. A similar link was reported in the literature for symmetric fullerene bis-adducts, allowing assignment of the 7 isomer groups to their respective bond types. 13C NMR spectroscopy allowed for the C2v, C2h, and the unique (C1) isomers in each of the five three-membered bond-type groups to be associated with their corresponding ACKNOWLEDGMENTS 6 HPLC fraction. This left 6 groups, each two unidentified isomers with both being either C1, C2, or Cs, which cannot be distinguished by 13C NMR spectra. HPLC retention times for members of the three-membered groups had the order of symmetric-asymmetric-symmetric. Hence, the two same-symmetry isomers in each group had widely spaced retention times. As HPLC columns separate based on molecular polarity. By arranging the same-symmetry isomers in order of polarity inversely orders then in HPLC retention time, which allowed for their identification. By these analyses, every one of the 19 purified HPLC fractions was associated with its corresponding structural isomer. Structural identification via 13C NMR spectroscopy was aided by benchmarking several DFT methods against the spectrum of PCBM. The wB97X method performed particularly well, and Dunning-type, outperformed Pople-type, basis sets. Agreement between experiment and simulation allowed all resonances to be assigned to their corresponding carbon atoms with high confidence.
Yumin Li, Jia Liu, Yukun Cao, Xiaoyu Han, Guozhu Shao, Xiaoyue Zhou, Jin Gu, Tong Liu, Yue Cui, and Heshui Shi
Scientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
Medicine and Science
Abstract Myocardial fibrosis assessed by late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) is associated with cardiovascular outcomes in hypertrophic cardiomyopathy (HCM) patients, but little is known about the utility of non-invasive markers for detecting LGE. This study aims to explore the association between cardiac-specific biomarkers, CMR myocardial strain, left ventricular (LV) hypertrophy and LGE in HCM patients with preserved ejection fraction (EF) and investigate the predictive values of these indexes for LGE. We recruited 33 healthy volunteers and 86 HCM patients with preserved EF to undergo contrast-enhanced CMR examinations. In total, 48 of 86 HCM patients had the presence of LGE. The LGE-positive patients had significant higher serum high-sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro b-type natriuretic peptide (Nt-proBNP) levels and lower global longitudinal (GLS) and circumferential (GCS) strains than the LGE-negative group. The LGE% was independently associated with the Nt-proBNP levels, GCS, LV end-diastolic maximum wall thickness (MWT) and beta-blocker treatment. In the receiver operating characteristic curve analysis, the combined parameters of Nt-proBNP ≥ 108.00 pg/mL and MWT ≥ 17.30 mm had good diagnostic performance for LGE, with a specificity of 81.25% and sensitivity of 70.00%. These data indicate that serum Nt-proBNP is a potential biomarker associated with LGE% and, combined with MWT, were useful for identifying myocardial fibrosis in HCM patients with preserved EF. Additionally, LV GCS may be a more sensitive indicator for reflecting the presence of myocardial fibrosis than GLS.
Michael Efremidis, George Bazoukis, Konstantinos Vlachos, Efstathia Prappa, Athanasia Megarisiotou, Stylianos Dragasis, F. Daniel Ramirez, Felix Bourier, Panagiotis Mililis, Athanasios Saplaouras, Gary Tse, Tong Liu, Theodore Efremidis, Panagiotis Kitsoulis, Costas Thomopoulos, Antonios Sideris, and Konstantinos P. Letsas
Journal of Arrhythmia, Vol 37, Iss 1, Pp 28-32 (2021)
atrial fibrillation, catheter ablation, left atrial thrombus, stroke, transesophageal echocardiography, Diseases of the circulatory (Cardiovascular) system, and RC666-701
Abstract Background The need for pre‐ or peri‐procedural imaging to rule out the presence of left atrial thrombus in patients undergoing catheter ablation of atrial fibrillation (AF) is unclear in the era of uninterrupted direct oral anticoagulant (DOAC) regimen. We sought to examine the safety of catheter ablation in appropriately selected patients with paroxysmal AF without performing screening for left atrial thrombus. Patients and Methods Consecutive patients planned for radiofrequency AF catheter ablation between January 2016 and June 2020 were enrolled, and prospectively studied. All subjects were receiving uninterrupted anticoagulation with DOACs for at least 4 weeks before the procedure. All subjects were in sinus rhythm the day of the procedure. The primary outcome of the study was ischemic stroke or transient ischemic attack (TIA) during at 30 days. Results A total of 451 patients (age 59.7 ± 10.2 years, 289 males) with paroxysmal AF were included in the study. The mean CHA2DS2‐VASc score was 1.4 ± 1.2. The mean left ventricular ejection fraction and left atrial diameter were 60 ± 5% and 39.3 ± 4 mm, respectively. Regarding the anticoagulation regimen, apixaban was used in 197 (43.6%) patients, rivaroxaban in 148 (32.8%) patients, and dabigatran in 106 (23.5%) patients. None of the patients developed clinical ischemic stroke or TIA during the 30‐day post‐discharged period. Conclusions Catheter ablation can be safely performed in low‐risk patients with paroxysmal AF without imaging for the detection of left atrial thrombus in the era of uninterrupted DOAC anticoagulation.