Background The influence of homocysteine （Hcy） on the migration and proliferation of vascular smooth muscle cells has been well established. However, the impact of Hcy levels on the progression of non-culprit corona...Background The influence of homocysteine （Hcy） on the migration and proliferation of vascular smooth muscle cells has been well established. However, the impact of Hcy levels on the progression of non-culprit coronary lesions （NCCLs） is controversial. This study aims to evaluate whether the plasma level of Hcy is related to the progression of NCCLs after percutaneous coronary stent implantation in elderly patients with acute coronary syndrome （ACS）. Methods A total of 223 elderly patients （〉 65 years old） with ACS undergoing stent im- plantation and follow-up coronary angiography were enrolled. Laboratory determination comprised of blood sample evaluation for Hcy was carried out before baseline coronary intervention. The patients were classified into two groups according to the blood Hcy tertiles （〉 15 mmol/L or 〈 15 mmol/L）. Patients were followed up for 12.2 months. NCCL progression was assessed by three-dimensional quantitative coronary angiography. Results A significantly higher ratio of NCCL progression was observed in the group with baseline Hcy concentrations above 15 mmol/L compared to the group with concentrations below 15 mmol/L （41/127, 32.3% vs. 14/96, 14.6%, P = 0.002）. Multivariate Cox regression analysis showed that Hcy and diabetes mellitus were independent risk factors for NCCL progression. The crude haz- ard ratio （HR） of NCCL progression for Hcy level was 1.056 （95% CI： 1.01-1.104, P = 0.015）. The adjusted HR of NCCL progression for Hcy level was 1.024 （95% CI： 1.007-1.042, P = 0.007）. The adjusted HR of NCCL progression for diabetes mellitus was 1.992 （95% CI： 1.15-3.44, P = 0.013）. Conclusions Hcy is an independent risk factor for NCCL progression after 12 months of follow-up in elderly patients with ACS who has undergone percutaneous coronary stenting.展开更多
Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the founda...Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the foundation of former studies. It was found that the coronary structure changed little whether in C4-Ala or C4-Ala-Xn, and the electrons transferred between C4-Ala and Xn at the mean time. There were coordinate bonds between Xn＋ and the nitrogen from -NH-, hydrogen bonds between Xa and the hydrogen from -NH-, and they became weaker when the radii of ions turned larger. Besides, the values of the single point bonding energy fluctuated gradually as a shape of saddle, but cations and anions located in opposite directions of the center of coronary structure when reach minimum, respectively.展开更多
Objective To investigate the relationship between vascular endothelial dysfunction and serum homocysteine (HCY) level in patients with coronary lesions. Methods Serum HCY, serum nitric oxide (NO), plasma endothelin-1 ...Objective To investigate the relationship between vascular endothelial dysfunction and serum homocysteine (HCY) level in patients with coronary lesions. Methods Serum HCY, serum nitric oxide (NO), plasma endothelin-1 (ET-1), and circulation endothelial cell (CEC) were measured in 76 patients who received coronary angiography. Fifty-four patients with a stenosis of 50% or more at least in one coronary atery were as coronary artery disease (CAD) group. Other 22 cases with no recognizable plaque and/or stenosis were as control group. HCY level was detected using an enzyme immunoassay kit. NO concentration was measured using a nitrate reductase kit. Radio-immunoassay was applied to analyse the ET-1 level, and CEC was measured by flow cytometry. Results The levels of HCY, ET-1, and CEC in patients with coronary lesions were significantly increased in comparison with control group (P < 0.01), while NO level in CAD group was significantly lower compared with that in control (P < 0.01). Using a multivariate stepwise regression analysis, HCY level had a positive correlation with ET-1 level (r = 0.420, P < 0.05) and CECs number (r = 0.423, P < 0.05); and had a negative correlation with NO/ET-1 (r = -0.403, P < 0.05). But there was no significant correlation between HCY and NO levels. Conclusions HCY might lead to endothelial cell injury, which would provide a plausible mechanism for the relationship between hyperhomocysteinemia and development of coronary artery disease. HCY can be considered as a predictor for preli-minary or active coronary lesion.展开更多
Metabolic syndrome had many different names, including syndrome X, insulin resistance syndrome. At present the cause of metabolic syndrome is unclear, it may come from two aspects： First, acquired, including being ov...Metabolic syndrome had many different names, including syndrome X, insulin resistance syndrome. At present the cause of metabolic syndrome is unclear, it may come from two aspects： First, acquired, including being overweight or obese, reduced physical activity and excessive carbohydrate diet; Second, genetic factors, involving multiple genes, not yet fully elucidated. The syndrome is generally believed to be the collection of a variety of cardiovascular risk factors caused by poor lifestyle under the genetic background, including hypertension, dyslipidemia, abdominal obesity, hyperinsulinemia, microalbuminuria, hypercoagulable state, hyperhomocysteinemia and so on. Hyperinsulinemia and insulin resistance is the central link, which is closely related to dyslipidemia, impaired glucose tolerance, and abdominal obesity. Metabolic syndrome may eventually lead to atherosclerosis： coronary artery disease, myocardial infarction, stroke, peripheral vascular disease and endothelial dysfunction. In 1999, the working definition of World Health Organization （WHO） to the metabolic syndrome is： glucose regulation impairment or diabetes, and / or insulin resistance, accompanied by the other two items or more ingredients, such as hypertension, high triglycerides esters hyperlipidemia and / or low HDL cholesterol, central obesity or microalbuminuria.展开更多
I have read with interest the paper by Hart, et al. re- porting that homocysteine （Hey） is an independent risk fac- tor for non-culprit coronary lesions progression after 12 months of follow-up in elderly patients w...I have read with interest the paper by Hart, et al. re- porting that homocysteine （Hey） is an independent risk fac- tor for non-culprit coronary lesions progression after 12 months of follow-up in elderly patients who has undergone percutaneous coronary stenting. Hcy-mediated increased lipid peroxidation and generation of free radicals results in in- flammation and endothelial dysfunction, which triggers atherosclerotic process. Coronary artery disease is also as- sociated with higher levels of Hcy.展开更多
The tree height-diameter at breast height(H-DBH)and crown radius-DBH(CR-DBH)relationships are key for forest carbon/biomass estimation,parameterization in vegetation models and vegetation-atmosphere interactions.Altho...The tree height-diameter at breast height(H-DBH)and crown radius-DBH(CR-DBH)relationships are key for forest carbon/biomass estimation,parameterization in vegetation models and vegetation-atmosphere interactions.Although the H-DBH relationship has been widely investigated on site or regional scales,and a few of studies have involved CR-DBH relationships based on plot-level data,few studies have quantitatively verifed the universality of these two relationships on a global scale.This study evaluated the ability of 29 functions to ft the H-DBH and CR-DBH relationships for six different plant functional types(PFTs)on a global scale,based on a global plant trait database.Results showed that most functions were able to capture the H-DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately,but slightly less for temperate PFTs and boreal broadleaf trees(BB).For boreal PFTs,the S-shaped Logistic function ftted the H-DBH relationship best,while for temperate PFTs the Chapman-Richards function performed well.For tropical needleleaf trees,the fractional function of DBH satisfactorily captured the H-DBH relationship,while for tropical broadleaf trees,the Weibull function and a composite function of fractions were the best choices.For CR-DBH,the ftting capabilities of all the functions were comparable for all PFTs except BB.The Logistic function performed best for two boreal PFTs and temperate broadleaf trees,but for temperate needleleaf trees and two tropical PFTs,some exponential functions demonstrated higher skill.This work provides valuable information for parameterization improvements in vegetation models and forest feld investigations.展开更多
Objective： To investigate whether elevated homocysteine levels were a predictor of subsequent coronary heart disease （CHD） mortality, cardiovascular mortality or all-cause mortality in the general population by a m...Objective： To investigate whether elevated homocysteine levels were a predictor of subsequent coronary heart disease （CHD） mortality, cardiovascular mortality or all-cause mortality in the general population by a meta- analysis. Methods： In a systematic search conducted in the databases of PubMed and Embase prior to October 2013, we identified relevant prospective observational studies evaluating the association between baseline homocysteine levels and CHD mortality, cardiovascular or all-cause mortality in the general population. Pooled adjust risk ratio （RR） and corresponding 95% confidence interval （CI） were calculated separately for categorical risk estimates and con- tinuous risk estimates. Results： Twelve studies with 23 623 subjects were included in the meta-analysis. Comparing the highest to lowest homocysteine level categories, CHD mortality increased by 66% （RR 1.66; 95% CI 1.12-2.47; P=-0.012）, cardiovascular mortality increased by 68% （RR 1.68; 95% CI 1.04-2.70; P=0.033）, and all-cause mortality increased by 93% （RR 1.93; 95% CI 1.54-2.43; P〈0.001）. Moreover, for each 5 pmol/L homocysteine increment, the pooled RR was 1.52 （95% CI 1.26-1.84; ,〈0.001） for CHD mortality, 1.32 （95% CI 1.08-1.61; P=0.006） for cardio- vascular mortality, and 1.27 （95% CI 1.03-1.55; P=-0.023） for all-cause mortality. Conclusions： Elevated homocysteine levels are an independent predictor for subsequent cardiovascular mortality or all-cause mortality, and the risks were more pronounced among elderly persons.展开更多
Forced response analysis of a rocket engine turbine blade was conducted by a decoupled fluid-structure interaction procedure.Aerodynamic forces on the rotor blade were obtained using 3D unsteady flow simulations. The ...Forced response analysis of a rocket engine turbine blade was conducted by a decoupled fluid-structure interaction procedure.Aerodynamic forces on the rotor blade were obtained using 3D unsteady flow simulations. The resulting aerodynamic forces were interpolated to the finite element(FE) model through surface effect elements prior to conducting forced response calculations.Effects of axial gap on aerodynamic forces were studied. In addition, influence of axial gap on the response of the shrouded blade was compared with that on the response of the unshrouded blade. Results demonstrated that as the axial gap increases,time-averaged pressure on the blade surface changes very little, while the pressure fluctuations decrease significantly. Pressure and aerodynamic forces on the blade surface display periodic variation, and the vane passing frequency component is dominant.Amplitudes of aerodynamic forces decrease with increasing axial gap. Restricted by the shroud, deformation and response of shrouded blade are much lower than those of the unshrouded blade. The response of unshrouded blade shows obvious beat vibration phenomenon, while the response of the shrouded blade does not have this characteristic because the shroud restrains multiple harmonics. Blade response in time domain was converted to frequency domain using fast Fourier transformation(FFT).Results revealed that the axial gap mainly affects the forced harmonic at the vane passing frequency, while the other two harmonics at natural frequency are hardly affected. Amplitudes of the unshrouded blade response decrease as the axial gap increases, while amplitudes of the shrouded blade response change very little in comparison.展开更多
文摘Background The influence of homocysteine （Hcy） on the migration and proliferation of vascular smooth muscle cells has been well established. However, the impact of Hcy levels on the progression of non-culprit coronary lesions （NCCLs） is controversial. This study aims to evaluate whether the plasma level of Hcy is related to the progression of NCCLs after percutaneous coronary stent implantation in elderly patients with acute coronary syndrome （ACS）. Methods A total of 223 elderly patients （〉 65 years old） with ACS undergoing stent im- plantation and follow-up coronary angiography were enrolled. Laboratory determination comprised of blood sample evaluation for Hcy was carried out before baseline coronary intervention. The patients were classified into two groups according to the blood Hcy tertiles （〉 15 mmol/L or 〈 15 mmol/L）. Patients were followed up for 12.2 months. NCCL progression was assessed by three-dimensional quantitative coronary angiography. Results A significantly higher ratio of NCCL progression was observed in the group with baseline Hcy concentrations above 15 mmol/L compared to the group with concentrations below 15 mmol/L （41/127, 32.3% vs. 14/96, 14.6%, P = 0.002）. Multivariate Cox regression analysis showed that Hcy and diabetes mellitus were independent risk factors for NCCL progression. The crude haz- ard ratio （HR） of NCCL progression for Hcy level was 1.056 （95% CI： 1.01-1.104, P = 0.015）. The adjusted HR of NCCL progression for Hcy level was 1.024 （95% CI： 1.007-1.042, P = 0.007）. The adjusted HR of NCCL progression for diabetes mellitus was 1.992 （95% CI： 1.15-3.44, P = 0.013）. Conclusions Hcy is an independent risk factor for NCCL progression after 12 months of follow-up in elderly patients with ACS who has undergone percutaneous coronary stenting.
文摘Under the method of density functional theory, the geometry structures, values of energy and population analysis of the combo of crown tetraalanylpeptide （C4-AIa） with ions （Xn） are calculated, based on the foundation of former studies. It was found that the coronary structure changed little whether in C4-Ala or C4-Ala-Xn, and the electrons transferred between C4-Ala and Xn at the mean time. There were coordinate bonds between Xn＋ and the nitrogen from -NH-, hydrogen bonds between Xa and the hydrogen from -NH-, and they became weaker when the radii of ions turned larger. Besides, the values of the single point bonding energy fluctuated gradually as a shape of saddle, but cations and anions located in opposite directions of the center of coronary structure when reach minimum, respectively.
文摘Objective To investigate the relationship between vascular endothelial dysfunction and serum homocysteine (HCY) level in patients with coronary lesions. Methods Serum HCY, serum nitric oxide (NO), plasma endothelin-1 (ET-1), and circulation endothelial cell (CEC) were measured in 76 patients who received coronary angiography. Fifty-four patients with a stenosis of 50% or more at least in one coronary atery were as coronary artery disease (CAD) group. Other 22 cases with no recognizable plaque and/or stenosis were as control group. HCY level was detected using an enzyme immunoassay kit. NO concentration was measured using a nitrate reductase kit. Radio-immunoassay was applied to analyse the ET-1 level, and CEC was measured by flow cytometry. Results The levels of HCY, ET-1, and CEC in patients with coronary lesions were significantly increased in comparison with control group (P < 0.01), while NO level in CAD group was significantly lower compared with that in control (P < 0.01). Using a multivariate stepwise regression analysis, HCY level had a positive correlation with ET-1 level (r = 0.420, P < 0.05) and CECs number (r = 0.423, P < 0.05); and had a negative correlation with NO/ET-1 (r = -0.403, P < 0.05). But there was no significant correlation between HCY and NO levels. Conclusions HCY might lead to endothelial cell injury, which would provide a plausible mechanism for the relationship between hyperhomocysteinemia and development of coronary artery disease. HCY can be considered as a predictor for preli-minary or active coronary lesion.
文摘Metabolic syndrome had many different names, including syndrome X, insulin resistance syndrome. At present the cause of metabolic syndrome is unclear, it may come from two aspects： First, acquired, including being overweight or obese, reduced physical activity and excessive carbohydrate diet; Second, genetic factors, involving multiple genes, not yet fully elucidated. The syndrome is generally believed to be the collection of a variety of cardiovascular risk factors caused by poor lifestyle under the genetic background, including hypertension, dyslipidemia, abdominal obesity, hyperinsulinemia, microalbuminuria, hypercoagulable state, hyperhomocysteinemia and so on. Hyperinsulinemia and insulin resistance is the central link, which is closely related to dyslipidemia, impaired glucose tolerance, and abdominal obesity. Metabolic syndrome may eventually lead to atherosclerosis： coronary artery disease, myocardial infarction, stroke, peripheral vascular disease and endothelial dysfunction. In 1999, the working definition of World Health Organization （WHO） to the metabolic syndrome is： glucose regulation impairment or diabetes, and / or insulin resistance, accompanied by the other two items or more ingredients, such as hypertension, high triglycerides esters hyperlipidemia and / or low HDL cholesterol, central obesity or microalbuminuria.
文摘I have read with interest the paper by Hart, et al. re- porting that homocysteine （Hey） is an independent risk fac- tor for non-culprit coronary lesions progression after 12 months of follow-up in elderly patients who has undergone percutaneous coronary stenting. Hcy-mediated increased lipid peroxidation and generation of free radicals results in in- flammation and endothelial dysfunction, which triggers atherosclerotic process. Coronary artery disease is also as- sociated with higher levels of Hcy.
基金supported by the National Natural Science Foundation of China(42275177)the National Key Scientifc and Technological Infrastructure project‘Earth System Science Numerical Simulator Facility’(EarthLab).
文摘The tree height-diameter at breast height(H-DBH)and crown radius-DBH(CR-DBH)relationships are key for forest carbon/biomass estimation,parameterization in vegetation models and vegetation-atmosphere interactions.Although the H-DBH relationship has been widely investigated on site or regional scales,and a few of studies have involved CR-DBH relationships based on plot-level data,few studies have quantitatively verifed the universality of these two relationships on a global scale.This study evaluated the ability of 29 functions to ft the H-DBH and CR-DBH relationships for six different plant functional types(PFTs)on a global scale,based on a global plant trait database.Results showed that most functions were able to capture the H-DBH relationship for tropical PFTs and boreal needleleaf trees relatively accurately,but slightly less for temperate PFTs and boreal broadleaf trees(BB).For boreal PFTs,the S-shaped Logistic function ftted the H-DBH relationship best,while for temperate PFTs the Chapman-Richards function performed well.For tropical needleleaf trees,the fractional function of DBH satisfactorily captured the H-DBH relationship,while for tropical broadleaf trees,the Weibull function and a composite function of fractions were the best choices.For CR-DBH,the ftting capabilities of all the functions were comparable for all PFTs except BB.The Logistic function performed best for two boreal PFTs and temperate broadleaf trees,but for temperate needleleaf trees and two tropical PFTs,some exponential functions demonstrated higher skill.This work provides valuable information for parameterization improvements in vegetation models and forest feld investigations.
文摘Objective： To investigate whether elevated homocysteine levels were a predictor of subsequent coronary heart disease （CHD） mortality, cardiovascular mortality or all-cause mortality in the general population by a meta- analysis. Methods： In a systematic search conducted in the databases of PubMed and Embase prior to October 2013, we identified relevant prospective observational studies evaluating the association between baseline homocysteine levels and CHD mortality, cardiovascular or all-cause mortality in the general population. Pooled adjust risk ratio （RR） and corresponding 95% confidence interval （CI） were calculated separately for categorical risk estimates and con- tinuous risk estimates. Results： Twelve studies with 23 623 subjects were included in the meta-analysis. Comparing the highest to lowest homocysteine level categories, CHD mortality increased by 66% （RR 1.66; 95% CI 1.12-2.47; P=-0.012）, cardiovascular mortality increased by 68% （RR 1.68; 95% CI 1.04-2.70; P=0.033）, and all-cause mortality increased by 93% （RR 1.93; 95% CI 1.54-2.43; P〈0.001）. Moreover, for each 5 pmol/L homocysteine increment, the pooled RR was 1.52 （95% CI 1.26-1.84; ,〈0.001） for CHD mortality, 1.32 （95% CI 1.08-1.61; P=0.006） for cardio- vascular mortality, and 1.27 （95% CI 1.03-1.55; P=-0.023） for all-cause mortality. Conclusions： Elevated homocysteine levels are an independent predictor for subsequent cardiovascular mortality or all-cause mortality, and the risks were more pronounced among elderly persons.
文摘Forced response analysis of a rocket engine turbine blade was conducted by a decoupled fluid-structure interaction procedure.Aerodynamic forces on the rotor blade were obtained using 3D unsteady flow simulations. The resulting aerodynamic forces were interpolated to the finite element(FE) model through surface effect elements prior to conducting forced response calculations.Effects of axial gap on aerodynamic forces were studied. In addition, influence of axial gap on the response of the shrouded blade was compared with that on the response of the unshrouded blade. Results demonstrated that as the axial gap increases,time-averaged pressure on the blade surface changes very little, while the pressure fluctuations decrease significantly. Pressure and aerodynamic forces on the blade surface display periodic variation, and the vane passing frequency component is dominant.Amplitudes of aerodynamic forces decrease with increasing axial gap. Restricted by the shroud, deformation and response of shrouded blade are much lower than those of the unshrouded blade. The response of unshrouded blade shows obvious beat vibration phenomenon, while the response of the shrouded blade does not have this characteristic because the shroud restrains multiple harmonics. Blade response in time domain was converted to frequency domain using fast Fourier transformation(FFT).Results revealed that the axial gap mainly affects the forced harmonic at the vane passing frequency, while the other two harmonics at natural frequency are hardly affected. Amplitudes of the unshrouded blade response decrease as the axial gap increases, while amplitudes of the shrouded blade response change very little in comparison.
