Background Elevated left ventricular filling pressure （LVFP） is an important cause of exercise intolerance in patients with atrial fib- dilation （AF）. Exercise stress echocardiography could assess LVFP during exer...Background Elevated left ventricular filling pressure （LVFP） is an important cause of exercise intolerance in patients with atrial fib- dilation （AF）. Exercise stress echocardiography could assess LVFP during exercise. The objective of this study was to investigate the relationship between exercise induced elevation of LVFP and exercise capacity in patients with AF. Methods This study included 145 con- secutive patients （81 men and 64 women; mean age 65.5 ± 8.0 years） with persistent non-valvular AF and normal left ventricular systolic function （left ventdcular ejection fraction 〉 50%）. All patients underwent a symptom-limited cardiopulmonary exercise test （CPET）. Doppler echocardiography was performed both at rest and immediately after exercise. Five consecutive measurements of early diastolic mitral inflow velocity （E） and early diastolic mitral annular velocity （e＇） were taken and averaged. E/e＇ ratio was calculated. Elevated LVFP was defined as E/e＇ 〉 9, and patients with elevated LVFP at rest were excluded. Results Patients were classified into two groups according to LVFP estimated by E/e＇ ratio after exercise： 39 （26.9%） with elevated LVFP after exercise and 106 （73.1%） with normal LVFP. As compared with patients with normal LVFP, the ones with elevated LVFP after exercise had significantly lower peak oxygen uptake （VO2 peak） （21.7 ± 2.3 vs. 26.4 ± 3.8 mL/min per kilogram, P 〈 0.001）, lower anaerobic threshold （19.9 ± 2.5 vs. 26.0± 4.0 mL/min per kilogram, P 〈 0.001）, and shorter exercise time duration （6.2± 0.8 vs. 7.0 ±1.3 min, P 〈 0.001）. Multivariate analysis showed that age, gender and E/e＇ after exercise were significantly correlated with VO2peak. Conclusion Elevated LVFP estimated by E/e＇ ratio after exercise is independently associated with reduced exercise capacity in AF patients.展开更多
Knowledge of cellular metal homeostasis will provide a better understanding of the mechanisms involved in metal tolerance and hyperaccumulation in metal-hyperaccumulating plants. Energy dispersive X-ray spectrometry ...Knowledge of cellular metal homeostasis will provide a better understanding of the mechanisms involved in metal tolerance and hyperaccumulation in metal-hyperaccumulating plants. Energy dispersive X-ray spectrometry （EDS） was used to determine the localization of cadmium （Cd） in leaves of the Zn/Cd hyperaccumulator Picris divaricata which had a shoot Cd concentration of 565 mg kg-1 after 2 weeks of growth in solution culture supplying 10μ tmol L^-1 CdCl2. The results indicated that Cd was distributed mainly in the trichomes, upper and lower epidermis and bundle sheath cells, with a relatively low level of Cd in mesophyll cells. Mesophyll protoplasts isolated from leaves remained viable after 24 h exposure to CdCl2 at a concentration up to 1 mmol L^-1, indicating their high tolerance to Cd. The intracellular Cd was visualized by staining with Leadmium Green dye, a cellular permeable Cd fluorescence probe. The results showed that the majority of protoplasts （〉 82%） did not accumulate Cd, with only a minority （〈 18%） showing Cd accumulation. In the Cd-accumulating protoplasts, Cd accumulation was depressed by the addition of Fe^2＋, Mn^2＋ and the metabolic inhibitor carbonyl cyanide m-chlorophenylhydrazone （CCCP）, but not by Ca^2＋ or Zn^2＋. Furthermore, the entire process of Cd uptake from external solution into the cytoplasm and subsequent sequestration into vacuoles was successfully recorded by confocal images. These results suggested that reduced cellular Cd accumulation and efficient Cd vacuolar sequestration in mesophyll cells might be responsible for cellular Cd tolerance and distribution in the leaves of P. divaricata.展开更多
基金Acknowledgements This work was supported by the National Natural Sciences Foundation of China （81400177, CHEN SM） and Beijing Natural Science Foundation （7154249, CHEN SM）. The authors have no financial disclosures.
文摘Background Elevated left ventricular filling pressure （LVFP） is an important cause of exercise intolerance in patients with atrial fib- dilation （AF）. Exercise stress echocardiography could assess LVFP during exercise. The objective of this study was to investigate the relationship between exercise induced elevation of LVFP and exercise capacity in patients with AF. Methods This study included 145 con- secutive patients （81 men and 64 women; mean age 65.5 ± 8.0 years） with persistent non-valvular AF and normal left ventricular systolic function （left ventdcular ejection fraction 〉 50%）. All patients underwent a symptom-limited cardiopulmonary exercise test （CPET）. Doppler echocardiography was performed both at rest and immediately after exercise. Five consecutive measurements of early diastolic mitral inflow velocity （E） and early diastolic mitral annular velocity （e＇） were taken and averaged. E/e＇ ratio was calculated. Elevated LVFP was defined as E/e＇ 〉 9, and patients with elevated LVFP at rest were excluded. Results Patients were classified into two groups according to LVFP estimated by E/e＇ ratio after exercise： 39 （26.9%） with elevated LVFP after exercise and 106 （73.1%） with normal LVFP. As compared with patients with normal LVFP, the ones with elevated LVFP after exercise had significantly lower peak oxygen uptake （VO2 peak） （21.7 ± 2.3 vs. 26.4 ± 3.8 mL/min per kilogram, P 〈 0.001）, lower anaerobic threshold （19.9 ± 2.5 vs. 26.0± 4.0 mL/min per kilogram, P 〈 0.001）, and shorter exercise time duration （6.2± 0.8 vs. 7.0 ±1.3 min, P 〈 0.001）. Multivariate analysis showed that age, gender and E/e＇ after exercise were significantly correlated with VO2peak. Conclusion Elevated LVFP estimated by E/e＇ ratio after exercise is independently associated with reduced exercise capacity in AF patients.
基金Supported by the National Natural Science Foundation of China(Nos.40901151 and 31000248)the NSFC-Guangdong Joint Foundation of China(No.U0833004)+1 种基金the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme,China(2011)the Fundamental Research Funds for the Central Universities,China(No.09lgpy23)
文摘Knowledge of cellular metal homeostasis will provide a better understanding of the mechanisms involved in metal tolerance and hyperaccumulation in metal-hyperaccumulating plants. Energy dispersive X-ray spectrometry （EDS） was used to determine the localization of cadmium （Cd） in leaves of the Zn/Cd hyperaccumulator Picris divaricata which had a shoot Cd concentration of 565 mg kg-1 after 2 weeks of growth in solution culture supplying 10μ tmol L^-1 CdCl2. The results indicated that Cd was distributed mainly in the trichomes, upper and lower epidermis and bundle sheath cells, with a relatively low level of Cd in mesophyll cells. Mesophyll protoplasts isolated from leaves remained viable after 24 h exposure to CdCl2 at a concentration up to 1 mmol L^-1, indicating their high tolerance to Cd. The intracellular Cd was visualized by staining with Leadmium Green dye, a cellular permeable Cd fluorescence probe. The results showed that the majority of protoplasts （〉 82%） did not accumulate Cd, with only a minority （〈 18%） showing Cd accumulation. In the Cd-accumulating protoplasts, Cd accumulation was depressed by the addition of Fe^2＋, Mn^2＋ and the metabolic inhibitor carbonyl cyanide m-chlorophenylhydrazone （CCCP）, but not by Ca^2＋ or Zn^2＋. Furthermore, the entire process of Cd uptake from external solution into the cytoplasm and subsequent sequestration into vacuoles was successfully recorded by confocal images. These results suggested that reduced cellular Cd accumulation and efficient Cd vacuolar sequestration in mesophyll cells might be responsible for cellular Cd tolerance and distribution in the leaves of P. divaricata.
