The value of speckle-tracking stratified strain combined with myocardial work measurement in evaluating left ventricular function in patients with heart failure with preserved ejection fraction.

Background: Heart failure with preserved ejection fraction (HFpEF) is a highly prevalent progressive disease accompanied by poor quality of life, high utilization of medical resources, morbidity, and mortality. However, the role of left ventricular (LV) systolic dysfunction has yet to be well elaborated despite the preservation of the LV ejection fraction. This study aimed to explore the diagnostic value of speckle-tracking stratified strain combined with myocardial work (MW) measurement in evaluating LV systolic dysfunction in patients with HFpEF. Methods: A total of 125 study consecutive individuals, 64 HFpEF patients, and 61 controls were prospectively enrolled in the Fourth Affiliated Hospital of Harbin Medical University. In addition to the conventional echocardiographic parameters, LV stratified strain and MW parameters were statistically compared between the HFpEF and control groups. The global longitudinal strain (GLS) of the subendocardium, myocardium, and subepicardium (GLSendo, GLSmyo, and GLSepi); the transmural gradient (ΔGLS); the global myocardial work index (GWI), global myocardial work efficiency (GWE), global myocardial constructive work (GCW), and the global myocardial wasted work (GWW) were included. Area under the receiver operating characteristic curve analysis was used to evaluate the diagnostic performance of these univariate and multivariable logistic models in detecting impaired LV systolic function in HFpEF. Ten-fold cross-validation was used to evaluate the generalizability of the predictive model. Results: Stratified strains values showed a gradient decline from GLSendo to GLSepi in both control and HFpEF patients. Compared with the control group, HFpEF patients had a significantly reduced GLSepi, GLSmyo, GLSendo, ΔGLS, GWI, GWE, and GCW and a significantly increased GWW (all P<0.001). In the derivation set, the optimal logistic model (combined stratified strain and MW variables) demonstrated the highest performance in predicting LV systolic function impairment in HFpEF patients. The best-performing model with a mean area under the curve (AUC) of 0.966 [95% confidence interval (CI): 0.88 to 1] accessed by 10-fold cross-validation. In the validation set, the AUC of the optimal logistic model was 0.933 (95% CI: 0.85 to 1), the sensitivity was 87%, and the specificity was 93%. Conclusions: Both speck-tracking stratified strain and MW measurement may sensitively detect impairment of LV myocardial function at an early stage for patients with HFpEF. Combining the two techniques may improve the quality of HFpEF diagnosis and may provide a reference value for the early diagnosis of HFpEF in the future.

Inorganic arsenic-mediated upregulation of TUG1 promotes apoptosis in human bronchial epithelial cells by activating the p53 signaling pathway.

Exposure to arsenic, an environmental contaminant, is known to cause arsenicosis and cancer. Although considerable research has been conducted to understand the underlying mechanism responsible for arsenic-induced cancers, the precise molecular mechanisms remain unknown, especially at the epigenetic regulation level. Long non-coding RNAs (LncRNAs) that have been shown to mediate various biological processes, including proliferation, apoptosis, necrosis, and mutagenesis. There are few studies on LncRNAs and biological damage caused by environmental pollutants. The LncRNAs taurine upregulated gene 1 (TUG1) regulates cell growth both in vitro and in vivo, and contributes its oncogenic role. However, the precise roles and related mechanisms of arsenic-induced cell apoptosis are still not fully understood owing to controversial findings in the literature. In this study, quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed higher expression levels of TUG1 in people occupationally exposed to arsenic than in individuals living away from the source of arsenic exosure (N = 25). In addition, the results suggested that TUG1 was involved in arsenic-induced apoptosis. Furthermore, knockdown experiments showed that silencing of TUG1 markedly inhibited proliferation, whereas depletion of TUG1 led to increased apoptosis. The TUG1-small interfering RNA (siRNA) combination with arsenic (3 µM/L) slightly increased apoptosis compared with the TUG1-siRNA. Additionally, the knockdown experiments showed that the silencing of TUG1 by siRNA inhibited proliferation and promoted apoptosis by inducing p53, p-p53 (ser392), FAS, BCL2, MDM2, cleaved-caspase7 proteins in 16HBE cells. These results indicated that arsenic mediates the upregulation of TUG1 and induces cell apoptosis via activating the p53 signaling pathway.

Involvement of a AS3MT/c-Fos/p53 signaling axis in arsenic-induced tumor in human lung cells.

Arsenite methyltransferase (AS3MT) is an enzyme that catalyzes the dimethylation of arsenite (+3 oxidation state). At present, the studies on arsenic carcinogenicity mainly focus on studying the polymorphisms of AS3MT and measuring their catalytic activities. We recently showed that AS3MT was overexpressed in lung cancer patients who had not been exposed to arsenic. However, little is known about the molecular mechanisms of AS3MT in arsenite-induced tumorigenesis. In this study, we showed that AS3MT protein expression was higher in the arsenic-exposed population compared to the unexposed population. AS3MT was also overexpressed in human lung adenocarcinoma (A549) and human bronchial epithelial (16HBE) cells exposed to arsenic (A549: 20-60 µmol/L; 16HBE: 2-6 µmol/L) for 48 h. Furthermore, we investigated the effects of AS3MT on cell proliferation and apoptosis using siRNA. The downregulation of AS3MT inhibited the proliferation and promoted the apoptosis of cells. Mechanistically, AS3MT was found to specifically bind to c-Fos, thereby inhibiting the binding of c-Fos to c-Jun. Additionally, the siRNA-mediated knockdown of AS3MT enhanced the phosphorylation of Ser392 in p53 by upregulating p38 MAPK expression. This led to the activation of p53 signaling and the upregulated expression of downstream targets, such as p21, Fas, PUMA, and Bax. Together, these studies revealed that the inorganic arsenic-mediated upregulation of AS3MT expression directly affected the proliferation and apoptosis of cells, leading to arsenic-induced toxicity or carcinogenicity.