A Note on the Connection Between Trek Rules and Separable Nonlinear Least Squares in Linear Structural Equation Models.

We show that separable nonlinear least squares (SNLLS) estimation is applicable to all linear structural equation models (SEMs) that can be specified in RAM notation. SNLLS is an estimation technique that has successfully been applied to a wide range of models, for example neural networks and dynamic systems, often leading to improvements in convergence and computation time. It is applicable to models of a special form, where a subset of parameters enters the objective linearly. Recently, Kreiberg et al. (Struct Equ Model Multidiscip J 28(5):725-739, 2021. https://doi.org/10.1080/10705511.2020.1835484 ) have shown that this is also the case for factor analysis models. We generalize this result to all linear SEMs. To that end, we show that undirected effects (variances and covariances) and mean parameters enter the objective linearly, and therefore, in the least squares estimation of structural equation models, only the directed effects have to be obtained iteratively. For model classes without unknown directed effects, SNLLS can be used to analytically compute least squares estimates. To provide deeper insight into the nature of this result, we employ trek rules that link graphical representations of structural equation models to their covariance parametrization. We further give an efficient expression for the gradient, which is crucial to make a fast implementation possible. Results from our simulation indicate that SNLLS leads to improved convergence rates and a reduced number of iterations.

miR-208b Reduces the Expression of Kcnj5 in a Cardiomyocyte Cell Line.

MicroRNAs (miRs) contribute to different aspects of cardiovascular pathology, among them cardiac hypertrophy and atrial fibrillation. Cardiac miR expression was analyzed in a mouse model with structural and electrical remodeling. Next-generation sequencing revealed that miR-208b-3p was ~25-fold upregulated. Therefore, the aim of our study was to evaluate the impact of miR-208b on cardiac protein expression. First, an undirected approach comparing whole RNA sequencing data to miR-walk 2.0 miR-208b 3'-UTR targets revealed 58 potential targets of miR-208b being regulated. We were able to show that miR-208b mimics bind to the 3' untranslated region (UTR) of voltage-gated calcium channel subunit alpha1 C and Kcnj5, two predicted targets of miR-208b. Additionally, we demonstrated that miR-208b mimics reduce GIRK1/4 channel-dependent thallium ion flux in HL-1 cells. In a second undirected approach we performed mass spectrometry to identify the potential targets of miR-208b. We identified 40 potential targets by comparison to miR-walk 2.0 3'-UTR, 5'-UTR and CDS targets. Among those targets, Rock2 and Ran were upregulated in Western blots of HL-1 cells by miR-208b mimics. In summary, miR-208b targets the mRNAs of proteins involved in the generation of cardiac excitation and propagation, as well as of proteins involved in RNA translocation (Ran) and cardiac hypertrophic response (Rock2).

10-Year Outcomes From a Randomized Trial of Polymer-Free Versus Durable Polymer Drug-Eluting Coronary Stents.

BACKGROUND: Outcome data after extended long-term follow-up of patients with coronary artery disease treated with drug-eluting stents (DES) in randomized clinical trials are scant. OBJECTIVES: Performance differences among devices may be expected to emerge over time depending on whether stenting is done with polymer-free or durable polymer DES. This study assessed the 10-year outcomes of patients enrolled in the ISAR-TEST-5 (Test Efficacy of Sirolimus- and Probucol-Eluting Versus Zotarolimus-Eluting Stents) trial. METHODS: A total of 3,002 patients were randomized to treatment with either polymer-free sirolimus- and probucol-eluting stents (n = 2,002) or durable polymer zotarolimus-eluting stents (n = 1,000). The primary endpoint was the composite of cardiac death, target vessel-related myocardial infarction, or target lesion revascularization (a device-oriented composite endpoint [DOCE]). Additional endpoints of interest were the patient-oriented composite endpoint (POCE), including all-cause death, any myocardial infarction, or any revascularization; individual components of the composite endpoints; and definite or probable stent thrombosis. RESULTS: The median age of the patients at randomization was 67.8 years. At 10 years, 63.9% of patients were alive. The rates of DOCE and POCE were high in both groups with no difference in the incidence between polymer-free sirolimus- and probucol-eluting stents and durable polymer zotarolimus-eluting stents (DOCE: 43.8% vs. 43.0%, respectively; hazard ratio: 1.01; 95% confidence interval [CI]: 0.89 to 1.14; p = 0.90; POCE: 66.2% vs. 67.7%, respectively; hazard ratio: 0.94; 95% CI: 0.86 to 1.04; p = 0.22). The rates of the individual components of the composite endpoints were comparable in both groups. The incidence of definite/probable stent thrombosis over 10 years was low and comparable in both groups (1.6% vs. 1.9%; hazard ratio: 0.85; 95% CI: 0.46 to 1.54; p = 0.58). CONCLUSIONS: At 10 years, there were no measurable differences in outcomes between patients treated with polymer-free versus durable polymer DES. The incidence of stent thrombosis was low and comparable in both groups. High overall adverse clinical event rates were observed during extended follow-up. (Test Efficacy of Sirolimus- and Probucol-Eluting Versus Zotarolimus-Eluting Stents [ISAR-TEST-5]; NCT00598533).