Evaluation of right ventricular performance and impact of continuous positive airway pressure therapy in patients with obstructive sleep apnea living at high altitude.

Obstructive sleep apnea syndrome (OSAS) can lead to alterations in right ventricular (RV) performance and pulmonary vascular haemodynamics. Additionally, altitude-related hypoxia is associated with pulmonary vasoconstriction, and the effect of high-altitude on the pulmonary circulation in OSAS patients can be further altered. We sought to assess alterations in RV morphology and function in OSAS patients living at high altitude by way of 2-dimensional speckle tracking echocardiography (2D-STE), real-time 3- dimensional echocardiography (RT-3DE) and cardiac biomarkers. We also evaluate the impact of continuous positive airway pressure (CPAP) treatment on RV performance. Seventy-one patients with newly diagnosed OSAS and thirty-one controls were included in this study. All individuals were assessed for cardiac biomarkers as well as underwent 2D-STE and RT-3DE. Forty-five OSAS patients underwent CPAP therapy for at least 24 weeks and were studied before and after CPAP treatment. RT-3DE was used to measure RV volume, and calculate RV 3D ejection fraction (3D RVEF). Peak systolic strain was determined. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide, and cardiac troponin T were also measured. Right atrium volume index, RV volume, RV volume index, systolic pulmonary artery pressure (sPAP), pulmonary vascular resistance (PVR) and level of serum CRP were significantly higher in OSAS group, while OSAS patients showed lower 3D RVEF and RV longitudinal strains. Compared to the patients with sPAP < 40 mmHg, RV longitudinal strains in patients with sPAP ≥ 40 mmHg were lower. Both RV global longitudinal strain and sPAP were associated with apnea-hypopnea index. Patients treated with 6 months of CPAP therapy had significant improvement in RV geometry and performance. RV structural abnormalities and RV function impairments were observed in OSAS patients living at moderate high altitude compared to control highlanders. The reversibility of these changes after application of CPAP were further confirmed.

[Effects of rosiglitazone on cholesterol contents and scavenger receptor class B type I expression in RAW264.7 foam cells].

OBJECTIVE: To observe the effect of rosiglitazone on the content of cholesterol and expressions of Acy-coenzyme A: cholesterol acyltransferase 1 (ACAT-1) and scavenger receptor class B type I (SR-BI) in RAW264.7 macrophage-derived foam cells and explore the anti-atherosclerotic mechanism of rosiglitazone. METHODS: RAW264.7 macrophages were incubated with oxidized low-density lipoproteins (ox-LDL) or with both ox-LDL and rosiglitazone (5, 10, or 20 µmol/L). Oil red O staining was used to observe the formation of foam cells, and cholesterol oxidase was used to determine the content of cellular cholesterol contents. Western blotting was used observe the expressions of ACAT-1 and SR-BI in RAW264.7 foam cells. RESULTS: Compared with the control cells, RAW264.7 macrophage-derived foam cells showed significantly increased contents of total cholesterol and free cholesterol (P<0.01) and ACAT-1 expressions (P<0.05) with mildly increased SR-BI expression (P>0.05). Rosiglitazone treatments significantly lowered the contents of total cholesterol and free cholesterol (P<0.05), decreased the expression of ACAT-1 (P<0.05), and increased SR-BI expression (P<0.05) in the foam cells in a dose-dependent manner. CONCLUSION: Rosiglitazone can decrease the contents of total and free cholesterol, down-regulate ACAT-1 expression and up-regulate SR-BI expression in the foam cells produce the anti-atherosclerotic effect.