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Carbohydrates are the main energy materials for plant metabolic activities. Enough carbohydrates stored in roots are necessary for plant re-growth, its tolerance against environmental stress, and the maintenance of grassland ecosystem stability. This paper summarized the influences of grazing, nitrogen fertilization, salt stress, drought, low temperature, and low oxygen stress on the carbohydrates in grassland plants, and introduced the advanced methods of measuring root carbohydrates. It was suggested that the research emphasis in the future should be paid on the relationships between root soluble sugar components and root physio-ecological functions. [ABSTRACT FROM AUTHOR]

Objective: To compare the mortality, survival rate and the therapeutic efficacy between mitral valve repair and replacement as treatment for severe ischemic mitral regurgitation (IMR), and explore the middle- and long-term outcomes. Methods: Between January 2000 and January 2016, 378 patients with severe IMR underwent coronary artery bypass grafting (CABG) combined with mitral valve repair ( n =162) or mitral valve replacement ( n =216) in the Department of Cardiovascular Surgery of Nanjing First Hospital. Clinical data, in-hospital morbidity and mortality of patients were retrospectively reviewed. The patients were followed up for the long term survival rate, heart function and re-admission. Results: No statistically significant differences of baseline data and operation details were found between the two groups except for left ventricular end-diastolic diameter[(61.3±10.2)mm in replacement group vs (56.2±9.0)mm in repair group, P <0.001]. Seven patients died during the perioperative period, with a total operation mortality of 1.9%.No significant difference of mortality was found between the two groups (5 cases in the replacement group and 2 cases in the repair group). The early outcome after the surgery showed that the rate of low cardiac output and ventricular arrhythmia of patients were significantly higher in the replacement group compared with the repair group (both P <0.05). The mortality of patients received mitral valve replacement was better than who received mitral valve repair when left ventricular end-diastolic diameter was over 65 mm (5.9% vs 10.0%, P =0.036). No significant differences were observed between the two groups in the middle- and -long term survival rate (87% for replacement group vs 85% for repair group, P =0.568). The follow-up time was 1-85 (52.8±21.5) months and the follow-up rate was 93%. The rate of valve-related complications was significantly higher in the repair group compared with the replacement group (8.82% vs 3.82%, P =0.003). Conclusions: We should choose the surgical methods carefully (replacement or repair) for severe IMR patients according to degree of left ventricular remodeling and pathological changes of mitral valve. Mitral valve replacement with preservation of the subvalvular apparatus is a safe and effective surgical alternative for mitral valve repair, especially for patients with complications or complex reflux.