Although tetraloops are one of the most frequently occurring secondary structure motifs in RNA, less than one-third of the 30 most frequently occurring RNA tetraloops have been thermodynamically characterized. Therefore, 24 stem-loop sequences containing common tetraloops were optically melted, and the thermodynamic parameters DH°, DS°, DG°3 7, and T M for each stem-loop were determined. These new experimental values, on average, are 0.7 kcal/mol different from the values predicted for these tetraloops using the model proposed by Vecenie CJ, Morrow CV, Zyra A, Serra MJ. 2006. Biochemistry 45: 1400-1407. The data for the 24 tetraloops reported here were then combined with the data for 28 tetraloops that were published previously. A new model, independent of terminal mismatch data, was derived to predict the free energy contribution of previously unmeasured tetraloops. The average absolute difference between the measured values and the values predicted using this proposed model is 0.4 kcal/mol. This new experimental data and updated predictive model allow for more accurate calculations of the free energy of RNA stem-loops containing tetraloops and, furthermore, should allow for improved prediction of secondary structure from sequence. It was also shown that tetraloops within the sequence 59-GCCNNNNGGC-39 are, on average, 0.6 kcal/mol more stable than the same tetraloop within the sequence 59-GGCNNNNGCC-39. More systemic studies are required to determine the full extent of non-nearest-neighbor effects on tetraloop stability.
Background Biventricular pacing for cardiac resynchronization therapy (CRT) is intended to improve left ventricular function by coordinating systolic activity of the septum and free walls. Optimal resynchronization should be manifested by 12-lead electrocardiogram (ECG) patterns consistent with resynchronized activation, a tall (≥4mm) R wave in V1 and predominant negative deflection in lead I (RV1SI). We investigated whether the presence or absence of RV1SI predicts heart failure outcomes within one year of CRT implant. Methods Two independent physicians reviewed the paced ECG of 213 patient post-CRT device implantation with disputes resolved by a third reviewer. The primary endpoints of all-cause death, unplanned hospitalization, left-ventricular assist device implant, or transplant within a one year follow-up were blindly adjudicated according to standard definitions. Groups were compared via Kaplan-Meier estimates and Cox proportional hazards models to determine association with event-free survival. Results Among CRT patients post-implantation, 56 (26.3%) exhibited the RV1SI pattern on ECG. Patients with the RV1SI pattern were significantly less likely to achieve the primary endpoint as compared to patients without the RV1SI pattern (33.9 v. 52.2%; Log Rank p=0.022). This difference was driven by a significantly lower risk for unplanned hospitalization among patients with the RV1SI pattern (HR = 0.510; CI [0.298, 0.876]). The predictive value remained after adjustment for potential confounders (p=0.004). Conclusions The 12-lead ECG post-implantation predicts clinical outcomes of biventricular pacing. Such prediction may be useful in predicting the need for alternative or advanced heart failure therapies. Further study into ECG patterns may help to prospectively guide CRT.
Aims Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has been shown to reduce angina and improve quality of life, but the frequency of new or residual angina after CTO PCI and its relationship with titration of anti-anginal medications (AAMs) has not been described. Methods and results Among consecutive CTO PCI patients treated at 12 US centres in the OPEN CTO registry, angina was assessed 6 months after the index PCI using the Seattle Angina Questionnaire (SAQ) Angina Frequency scale (a score <100 defined new or residual angina). We then compared the proportion of patients with AAM escalation (defined as an increase in the number or dosage of AAMs between discharge and follow-up) between those with and without 6-month angina. Of 901 patients who underwent CTO PCI, 197 (21.9%) reported angina at 6-months, of whom 80 (40.6%) had de-escalation, 66 (33.5%) had no change, and only 51 (25.9%) had escalation of their AAM by the 6-month follow-up. Rates of AAM escalation were similar when stratifying patients by the ultimate success of the CTO PCI, completeness of physiologic revascularization, presence or absence of angina at baseline, history of heart failure, and by degree of symptomatic improvement after CTO PCI. Conclusions One in five patients reported angina 6 months after CTO PCI. Although patients with new or residual angina were more likely to have escalation of AAMs in follow-up compared with those without residual symptoms, only one in four patients with residual angina had escalation of AAMs. Although it is unclear whether this finding reflects maximal tolerated therapy at baseline or therapeutic inertia, these findings suggest an important potential opportunity to further improve symptom control in patients with complex stable ischaemic heart disease.
A ruptured sinus of Valsalva aneurysm as a cause of aorto–atrial fistula is very rare. We present the case of a 53-year-old female who presented with symptoms of acute heart failure and suspicion of an aorto–atrial fistula found on a transthoracic echocardiogram, which was confirmed on transesophageal echocardiography. A coronary angiogram showed normal coronary arteries but confirmed the right aorto–atrial fistula on aortogram. She underwent successful surgical repair of the fistula. Her postoperative echocardiogram showed a normal right atrium and right ventricle with no shunt. A ruptured sinus of Valsalva aneurysm is a devastating event and presents as acute heart failure. Prompt diagnosis and surgical repair is necessary to prevent mortality.
Transcatheter mitral valve repair with MitraClip is a novel, intricate therapy for mitral regurgitation that improves survival and quality of life. Similar to other medical procedures, there is a relationship between procedural experience and clinical outcomes. MitraClip results and the efficiency and safety of the procedure all improved with increasing experience at both the institutional and operator level in two large studies from the Society of Thoracic Surgeons and American College of Cardiology Transcatheter Valve Therapy Registry. Patient selection was also found to have a significant role in procedure success. The old adage of “See one, do one, teach one” does not necessarily apply to complex interventions, such as MitraClip, given that the learning curve does not appear to plateau even as operators approach a 150-case experience.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.