Objective:To investigate the effects of 10° head up tilt bed rest (HUT) on human cardiac function via 3D speckle tracking echocardiography (3D-STE), and to study the difference in cardiac function under the submaximal exercise load between the horizontal position and 10° HUBR.Methods:Thirty young healthy volunteers were recruited as the subjects, who were randomly divided into an 10° HUT exercise group and horizontal exercise group with 15 subjects in each. Subjects in both groups were asked to ride the bicycle ergometer in the 10° HUBR position and supine position respectively. The load started with 50 W and was increased by 25 W every 3 min until it reached the maximum of 125 W. Before the exercise (resting state), 1 min after the load was increased each time, and 3 min after exercise (recovery period), the following indices were collected: ①basic cardiac function indices: heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP), ②conventional cardiac ultrasound indices: left ventricular ejection fraction (LVEF), stroke volume (SV) and cardiac output (CO), ③left ventricular strain indices: global longitudinal strain (GLS), global circumferential strain (GCS), and global area strain (GAS) measured by 3D-SET. The changes of these indices in the 2 groups of subjects under different exercise loads were observed.Results:The differences in the major effect of the basic heart indices (HR, SBP and DBP), conventional cardiac ultrasound indices (LVEF, SV and CO) and left ventricular strain indices (GLS, GCS and GAS) in response to the exercise load were statistically significant ( F=194.90, 113.66, 17.19, P=0.017, 0.018, 0.001). With the increase of the exercise load, the basic heart indices and conventional cardiac ultrasound indices kept rising, the left ventricular strain indices reached the minimum under a moderate exercise load (75 W), HR, SBP and CO were higher than those of the resting state ( P<0.05 or 0.01). Both LVEF under exercise loads of 75, 100, 125 W and during recovery, and SV under exercise loads of 100, 125 W and during recovery were significantly higher than those of the resting state ( P<0.05 or 0.01), while GLS and GCS under exercise loads of 50, 75, 125 W ( P<0.05 or 0.01), and GAS under exercise loads of 50, 75 W ( P<0.01) were significantly lower. There were statistically significant differences not only in GCS across the groups ( F=4.60, P=0.026) but also in DBP due to the interactions between the grouping and exercise loads ( F=3.13, P=0.031). DBP was higher than that of the resting state when the exercise load was 125 W in both groups. Conclusions:During submaximal exercise, myocardial contractility shows sustained enhancement with the increase of the exercise load. The results of GLS, GCS and GAS indicate that myocardial strain reaches its lowest value under a moderate exercise load, suggesting that moderate exercise can be used to evaluate cardiac function via 3D-SET. Under a simulated lunar gravity of 10° HUT, there is less deformation in the short axis direction of the myocardium, indicating that GCS can be used as a sensitive indicator to detect changes in cardiac function under different gravities.

Objective:To investigate the effects of 10° head up tilt bed rest (HUT) on human cardiac function via 3D speckle tracking echocardiography (3D-STE), and to study the difference in cardiac function under the submaximal exercise load between the horizontal position and 10° HUBR.Methods:Thirty young healthy volunteers were recruited as the subjects, who were randomly divided into an 10° HUT exercise group and horizontal exercise group with 15 subjects in each. Subjects in both groups were asked to ride the bicycle ergometer in the 10° HUBR position and supine position respectively. The load started with 50 W and was increased by 25 W every 3 min until it reached the maximum of 125 W. Before the exercise (resting state), 1 min after the load was increased each time, and 3 min after exercise (recovery period), the following indices were collected: ①basic cardiac function indices: heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP), ②conventional cardiac ultrasound indices: left ventricular ejection fraction (LVEF), stroke volume (SV) and cardiac output (CO), ③left ventricular strain indices: global longitudinal strain (GLS), global circumferential strain (GCS), and global area strain (GAS) measured by 3D-SET. The changes of these indices in the 2 groups of subjects under different exercise loads were observed.Results:The differences in the major effect of the basic heart indices (HR, SBP and DBP), conventional cardiac ultrasound indices (LVEF, SV and CO) and left ventricular strain indices (GLS, GCS and GAS) in response to the exercise load were statistically significant ( F=194.90, 113.66, 17.19, P=0.017, 0.018, 0.001). With the increase of the exercise load, the basic heart indices and conventional cardiac ultrasound indices kept rising, the left ventricular strain indices reached the minimum under a moderate exercise load (75 W), HR, SBP and CO were higher than those of the resting state ( P<0.05 or 0.01). Both LVEF under exercise loads of 75, 100, 125 W and during recovery, and SV under exercise loads of 100, 125 W and during recovery were significantly higher than those of the resting state ( P<0.05 or 0.01), while GLS and GCS under exercise loads of 50, 75, 125 W ( P<0.05 or 0.01), and GAS under exercise loads of 50, 75 W ( P<0.01) were significantly lower. There were statistically significant differences not only in GCS across the groups ( F=4.60, P=0.026) but also in DBP due to the interactions between the grouping and exercise loads ( F=3.13, P=0.031). DBP was higher than that of the resting state when the exercise load was 125 W in both groups. Conclusions:During submaximal exercise, myocardial contractility shows sustained enhancement with the increase of the exercise load. The results of GLS, GCS and GAS indicate that myocardial strain reaches its lowest value under a moderate exercise load, suggesting that moderate exercise can be used to evaluate cardiac function via 3D-SET. Under a simulated lunar gravity of 10° HUT, there is less deformation in the short axis direction of the myocardium, indicating that GCS can be used as a sensitive indicator to detect changes in cardiac function under different gravities.

Objective:To explore the relationship between severe fever with thrombocytopenia syndrome virus (SFTSV) Gc and its N-glycosylation site and viral infectivity, a recombinant pseudovirus containing SFTSV Gc glycosylation site mutant was constructed.Methods:The eukaryotic expression vectors pcDNA3.1(+ )-GC, PCDNA3.1(+ )-GC(N291Q), PCDNA3.1(+ )-GC(N352Q) and PCDNA3.1(+ )-GC (N374Q) were constructed by site-directed mutagenesis and homologous recombination. After their successful expression in 293T cells, we infected VSVΔG-Fluc*G pseudovirus, constructed four recombinant pseudoviruses and tested their effects on the cell force of infection.Results:Double digestion identification and sequence determination confirmed the successful construction of eukaryotic expression vectors pcDNA3.1 (+ )-Gc, pcDNA3.1 (+ )-Gc(N291Q), pcDNA3.1 (+ )-Gc(N352Q) and pcDNA3.1 (+ )-Gc(N374Q). Indirect immunofluorescence and Western Blotting result indicated the successful expression of all the four recombinant plasmids. SFTSV Gc recombinant pseudoviruses are specific for infecting Vero cells. Pseudovirus infection capacity was decreased significantly after the glycosylation site mutation, and the mutant strain with the glycosylation site at position 352 had the lowest level of infectivity ( P<0.001, P=0.001). Conclusions:The glycosylation site of SFTSV Gc may be associated with the infectious effect of the viral infection, and the amino acid mutation at position 352 has the greatest effect on the viral infectivity.

Objective To evaluate the association between retinol-binding protein 4 (RBP4) and coronary artery disease (CAD) in Chinese.Methods A document retrieval was conducted by using retrieval systems,such as PubMed,Web of Science,Cochrane Library,Chinese National Knowledge Infrastructure (CNKI),CBM,VIP and WanFang Database,to collect the published papers of case-control studies on association between RBP4 and CAD in Chinese up to February,2015.Data collection and quality assessment were completed by two authors respectively.All the analyses were conducted with software RevMan 5.2.Results A total of 10 qualified studies were included in our meta-analysis.The pooled analysis showed that RBP4 might be associated with CAD in Chinese [WMD=7.17 (95％CI:3.56-10.78) μg/ml,P＜0.05].Clinical subtype specific subgroup analysis showed RBP4 might be also associated with both stable angina pectoris [WMD=4.81 (95％ CI:1.25-8.37) μg/ml,P＜0.05] and acute myocardial infarction [WMD=13.96(95％CI:6.12-21.80) μg/ml,P＜0.05].Age specific subgroup analysis showed the significant association between RBP4 and CAD was only found in patients aged ≤65 years [WMD=7.26(95％CI:2.73-11.79)μg/ml,P＜0.05].Sensitivity and publication bias analyses indicated that our results were stable and reliable.Conclusion The meta-analysis suggests that RBP4 might be associated with CAD in Chinese.