Different physical exercise modalities have been widely studied in patients having heart failure with preserved ejection fraction (HFpEF) but with variably reported findings. We, therefore, conducted a systematic review and meta-analysis to evaluate whether the efficacy of physical activity in the management of HFpEF is related to exercise modalities. PubMed and Embase were searched up to July 2021. The eligible studies included randomized controlled trials that identified effects of physical exercise on patients with HFpEF. Sixteen studies were included to evaluate the efficiency of physical exercise in HFpEF. A pooled analysis showed that exercise training significantly improved peak oxygen uptake (VO 2 ), ventilatory anaerobic threshold, distance covered in the 6-minute walking test, the ratio of early diastolic mitral inflow to annular velocities, the Short Form 36 physical component score, and the Minnesota Living with Heart Failure Questionnaire total score. However, the changes in other echocardiographic parameters including the ratio of peak early to late diastolic mitral inflow velocities, early diastolic mitral annular velocity, and left atrial volume index were not significant. Both high-intensity and moderate-intensity training significantly improved exercise capacity (as defined by peak VO 2 ), with moderate-intensity exercise having a superior effect. Furthermore, exercise-induced improvement in peak VO 2 was partially correlated with exercise duration. Physical exercise could substantially improve exercise capacity, quality of life, and some indicators of cardiac diastolic function in patients with HFpEF. A protocol of moderate-intensity exercise training lasting a longer duration might be more beneficial compared with high-intensity training for patients with HFpEF.
Tenofovir disoproxil fumarate (TDF) is an antiretroviral medication with significant curative effects, so its quantitative detection is important for human health. At present, there are few studies on the detection of TDF by electrochemical sensors. This work can be a supplement to the electrochemical detection of TDF. Moreover, bare electrodes are susceptible to pollution, and have high overvoltage and low sensitivity, so it is crucial to find a suitable electrode material. In this work, zirconium oxide (ZrO2) that has a certain selectivity to phosphoric acid groups was synthesized by a hydrothermal method with zirconyl chloride octahydrate as the precursor. A composite modified glassy carbon electrode for zirconium oxide-chitosan-multiwalled carbon nanotubes (ZrO2-CS-MWCNTs/GCE) was used for the first time to detect the TDF, and achieved rapid, sensitive detection of TDF with a detection limit of sub-micron content. The ZrO2-CS-MWCNTs composite was created using sonication of a mixture of ZrO2 and CS-MWCNTs solution. The composite was characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV). Electrochemical analysis was performed using differential pulse voltammetry (DPV). Compared with single-material electrodes, the ZrO2-CS-MWCNTs/GCE significantly improves the electrochemical sensing of TDF due to the synergistic effect of the composite. Under optimal conditions, the proposed method has achieved good results in linear range (0.3~30 μM; 30~100 μM) and detection limit (0.0625 μM). Moreover, the sensor has the merits of simple preparation, good reproducibility and good repeatability. The ZrO2-CS-MWCNTs/GCE has been applied to the determination of TDF in serum and urine, and it may be helpful for potential applications of other substances with similar structures.
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