Value of two-dimensional speckle tracking imaging in quantitative assessment of left ventricular function in patients with OSAS

Objective: To research the clinical application of two-dimensional speckle tracking imaging (2D-STI) in quantitative assessment of left ventricular function in patients with obstructive sleep apnea-hypopnea syndrome (OSAS). Method: From July 2016 to December 2018, 86 patients with OSAS were selected as OSAS group. According to sleep apnea hypopnea index (AHI), they were divided into mild OSAS group (24 cases), moderate OSAS group (29 cases) and severe OSAS group (33 cases). Another 50 healthy volunteers who underwent physical examination in our hospital during the same period were selected as the control group. The left ventricular function of all patients was quantitatively assessed by 2D-STI. The left ventricular function of all patients was quantitatively assessed by 2D-STI. The results of routine echocardiography and left ventricular global strain parameters of the OSAS group, the control group and the OSAS patients with different severity were compared and analyzed. Result: There were no significant differences in the levels of left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDd), left ventricular end systolic diameter (LVESd) between the two groups and OSAS patients with different severity (P>0.05). The levels of IVST, LVPW and LVMI in the OSAS group were significantly higher than those in the control group, the levels of end-diastolic interventricular septal thickness (IVS), left ventricular posterior wall thickness (LVPW), left ventricular mass index (LVMI) in the severe OSAS group were significantly higher than those in the mild and moderate OSAS group, and the levels of IVST, LVPW and LVMI in the moderate OSAS group were significantly higher than those in the mild OSAS group, there were significant differences between groups (P<0.05). The levels of GLS, GRS and GCS in the OSAS group were significantly lower than those in the control group (P<0.05). GLS, GRS and GCS levels in the severe OSAS group were significantly lower than those in the mild OSAS group and the moderate OSAS group, while the levels of global longitudinal strain (GLS), global radial strain (GRS) and global circumferential strain (GCS) in the moderate OSAS group were significantly lower than those in the mild OSAS group (P<0.05). Conclusion: The left ventricular systolic function of OSAS patients is obviously impaired. Left ventricular function in OSAS patients can be assessed timely and accurately by two-dimensional speckle tracking imaging.

Disruption of Secondary Wall Cellulose Biosynthesis Alters Cadmium Translocation and Tolerance in Rice Plants

Tricheary elements （TEs）, wrapped by secondary cell wall, play essential roles in water, mineral, and nutrient transduction. Cadmium （Cd） is a toxic heavy metal that is absorbed by roots and transported to shoot, leaves, and grains through vascular systems in plants. As rice is a major source of Cd intake, many efforts have been made to establish ＇low- Cd rice＇. However, no links have been found between cellulose biosynthesis and cadmium accumulation. We report here a rice brittle culm13 mutant, resulting from a novel missense mutation （G101K） in the N-terminus of cellulose synthase subunit 9 （CESA9）. Except for the abnormal mechanical strength, the mutant plants are morphologically indistinguishable from the wild-type plants. Transmission electron microscopy （TEM） and chemical analyses showed a slight reduction in secondary wall thickness and 22% decrease in cellulose content in bc13 plants. Moreover, this mutation unexpectedly confers the mutant plants Cd tolerance due to less Cd accumulation in leaves. Expression analysis of the genes required for Cd uptake and transport revealed complicated alterations after applying Cd to wild-type and bc13. The mutants were further found to have altered vascular structure. More importantly, Cd concentration in the xylem saps from the bc13 plants was significantly lower than that from the wild-type. Combining the analyses of CESA9 gene expression and Cd content retention in the cell-wall residues, we conclude that CESA9^G101K mutation alters cell-wall properties in the conducting tissues, which consequently affects Cd translocation efficiency that largely contributes to the low Cd accumulation in the mutant plants.