Our understanding of coronary syndromes has evolved in the last two decades out of the obstructive atherosclerosis of epicardial coronary arteries paradigm to include anatomo-functional abnormalities of coronary micro...Our understanding of coronary syndromes has evolved in the last two decades out of the obstructive atherosclerosis of epicardial coronary arteries paradigm to include anatomo-functional abnormalities of coronary microcirculation. No current diagnostic technique allows direct visualization of coronary microcirculation,but functional assessments of this circulation are possible. This represents a challenge in cardiology. Myocardial contrast echocardiography(MCE) was a breakthrough in echocardiography several years ago that claimed the capability to detect myocardial perfusion abnormalities and quantify coronary blood flow. Research demonstrated that the integration of quantitative MCE and fractional flow reserve improved the definition of ischemic burden and the relative contribution of collaterals in non-critical coronary stenosis. MCE identified no-reflow and low-flow within and around myocardial infarction,respectively,and predicted the potential functional recovery of stunned myocardium using appropriate interventions. MCE exhibited diagnostic performances that were comparable to positron emission tomography in microvascular reserve and microvascular dysfunction in angina patients. Overall,MCE improved echocardiographic evaluations of ischemic heart disease in daily clinical practice,but the approval of regulatory authorities is lacking.展开更多
Traumatic spinal cord injury is a devastating disorder chara cterized by sensory,motor,and autonomic dysfunction that seve rely compromises an individual's ability to perform activities of daily living.These adve ...Traumatic spinal cord injury is a devastating disorder chara cterized by sensory,motor,and autonomic dysfunction that seve rely compromises an individual's ability to perform activities of daily living.These adve rse outcomes are closely related to the complex mechanism of spinal cord injury,the limited regenerative capacity of central neurons,and the inhibitory environment fo rmed by traumatic injury.Disruption to the microcirculation is an important pathophysiological mechanism of spinal cord injury.A number of therapeutic agents have been shown to improve the injury environment,mitigate secondary damage,and/or promote regeneration and repair.Among them,the spinal cord microcirculation has become an important target for the treatment of spinal cord injury.Drug inte rventions targeting the microcirculation can improve the microenvironment and promote recovery following spinal cord injury.These drugs target the structure and function of the spinal cord microcirculation and are essential for maintaining the normal function of spinal neuro ns,axons,and glial cells.This review discusses the pathophysiological role of spinal cord microcirculation in spinal cord injury,including its structure and histopathological changes.Further,it summarizes the progress of drug therapies targeting the spinal cord mic rocirc ulation after spinal cord injury.展开更多
Here, a patient with chest pain and <50% stenosis on coronary angiography, where ATP stress myocardial contrast echocardiography (MCE) revealed that coronary flow reserve was reduced to 1.71 was presented. Perfusio...Here, a patient with chest pain and <50% stenosis on coronary angiography, where ATP stress myocardial contrast echocardiography (MCE) revealed that coronary flow reserve was reduced to 1.71 was presented. Perfusion delay occurred in the left ventricular wall of the apex of the heart before ATP stress, and the perfusion delay area was significantly reduced at peak stress. Similar to the characteristics of "reverse redistribution" of radionuclide myocardium perfusion in coronary vasospasm, the delayed perfusion area in the recovery period was larger than that detected before stress. Together with increased spectral resistance of the distal segment of left anterior descending coronary artery and chest pain, these findings indicated coronary microvascular disease with spasmodic characteristics in this patient. The perfusion characteristics on ATP stress determined by MCE and changes in coronary spectrum have value for the diagnosis and treatment of coronary microvascular disease with spasmodic characteristics.展开更多
Background:Angiopoietin-2(Ang-2)is a type of endothelial growth factor involved in angiogenesis and vascular remodeling.Circulating Ang-2 levels are elevated in patients with obstructive coronary artery disease(CAD).T...Background:Angiopoietin-2(Ang-2)is a type of endothelial growth factor involved in angiogenesis and vascular remodeling.Circulating Ang-2 levels are elevated in patients with obstructive coronary artery disease(CAD).This study aimed to evaluate the association between serum Ang-2 levels and coronary microvascular dysfunction in patients without obstructive CAD.Methods:A total of 125 patients with angina in the absence of obstructive CAD were included in this cross-sectional study.Coronary flow reserve(CFR)was measured in the distal left anterior descending coronary artery by trans-thoracic Doppler echocardiography.The patients were divided into the following two sub-groups according to CFR:the impaired CFR group with CFR values<2.5 and the preserved CFR group with CFR values≥2.5.Serum Ang-2 levels were determined using enzyme-linked immunosorbent assay.Independent predictors for impaired CFR were identified by binary logistic regression analysis.The receiveroperating characteristic curve was determined to evaluate the ability of serum Ang-2 in predicting impaired CFR.Results:We found that age,percentage of female sex,N-terminal pro-B-type natriuretic peptide levels,Ang-2 levels(763.3±264.9 vs.579.7±169.3 pg/mL,P<0.001),and the left atrial volume index were significantly higher in patients with impaired CFR than in patients with preserved CFR.Serum Ang-2 levels were negatively correlated with CFR(r=0.386,P<0.001).Binary logistic regression analysis showed that Ang-2(odds ratio:1.004,95%confidence interval[CI]:1.001–1.006,P=0.003)and age(odds ratio:1.088,95%CI:1.023–1.156,P=0.007)were independently associated with impaired CFR.Furthermore,Ang-2 was a significant predictor of impaired CFR on the receiver-operating characteristic curve(P<0.001).The area under the curve was 0.712(95%CI:0.612–0.813).Conclusions:High serum Ang-2 levels are independently associated with impaired CFR in patients with angina in the absence of obstructive CAD.展开更多
Physicians cannot rely solely on the angiographic appearance of epicardial coronary artery stenosis when evaluating patients with myocardial ischemia. Instead, sound knowledge of coronary vascular physiology and of th...Physicians cannot rely solely on the angiographic appearance of epicardial coronary artery stenosis when evaluating patients with myocardial ischemia. Instead, sound knowledge of coronary vascular physiology and of the methods currently available for its characterization can improve the diagnostic and prognostic accuracy of invasive assessment of the coronary circulation, and help improve clinical decision-making. In this article we summarize the current methods available for a thorough assessment of coronary physiology.展开更多
Background: Microvascular perfusion, a kind of regional perfusion, plays important roles in delivering oxygen and nutrients, and regulating blood pressure and responses to inflammation. Aim: The aim of this research i...Background: Microvascular perfusion, a kind of regional perfusion, plays important roles in delivering oxygen and nutrients, and regulating blood pressure and responses to inflammation. Aim: The aim of this research is to analyze the characteristics of microvascular perfusion by conducting pipe flow in a circular elastic tube. Methods: A model was established with circular elastic tube to mimic microvascular perfusion. The velocity of pressure waves was calculated according to the time that the liquid took to spilt over. What’s more, the characteristics and significance of microvascular flow and arteriovenous anastomoses (AVAs) were analyzed. Results: It took the liquid about 0.1 second to spill over from the model, and the velocity of pressure waves is greater than 100 m/s in the elastic pipe. A mechanical switch structure and the corresponding mechanism were proposed for microvascular perfusion in AVAs. Conclusion: Microvascular perfusion maintains a considerable constancy of hemodynamics in different tissues, when ventricular contraction changes perfusion pressure to meet metabolic demands appropriately. This theory will help us to gain a new perspective in microvascular flow.展开更多
The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompre...The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.展开更多
Insulin resistance(IR)is the common pathophysiological basis of many metabolic diseases.IR is characterized by decreased glucose uptake in skeletal muscle and adipose tissue,especially in skeletal muscle.Skeletal musc...Insulin resistance(IR)is the common pathophysiological basis of many metabolic diseases.IR is characterized by decreased glucose uptake in skeletal muscle and adipose tissue,especially in skeletal muscle.Skeletal muscle is the main target tissue of glucose uptake under insulin stimulation.Glucose uptake by skeletal muscle is complex,and it is controlled by many pathways.The PI3K/AKt/GSK-1 signaling pathway is not only the main pathway for insulin signal transduction but also an important mechanism for regulating blood glucose.From the binding of insulin to its receptors on the surface of target cells to the transportation of glucose from extracellular fluid to skeletal muscle,a series of signal transduction processes is completed,any of which potentially affects the physiological effects of insulin and leads to IR.Resistance exercise(RT)can reduce skeletal muscle IR and effectively improve blood glucose control and glycosylated hemoglobin level in patients with type 2 diabetes mellitus(T2DM).However,the exact mechanism by which RT improves skeletal muscle IR remains unclear.Therefore,this paper discusses the above problems by tracking the progress of the literature to deepen the correlation between RT and skeletal muscle insulin sensitivity and provide further evidence for the application of exercise therapy in IR.In conclusion,RT mainly improves insulin sensitivity of skeletal muscle by increasing muscle mass,microvascular blood flow,and glucose transporter-4 expression in skeletal muscle,as well as by reducing lipid accumulation and inflammation in skeletal muscle.Thus,it is potentially useful in the prevention and treatment of T2DM.展开更多
文摘Our understanding of coronary syndromes has evolved in the last two decades out of the obstructive atherosclerosis of epicardial coronary arteries paradigm to include anatomo-functional abnormalities of coronary microcirculation. No current diagnostic technique allows direct visualization of coronary microcirculation,but functional assessments of this circulation are possible. This represents a challenge in cardiology. Myocardial contrast echocardiography(MCE) was a breakthrough in echocardiography several years ago that claimed the capability to detect myocardial perfusion abnormalities and quantify coronary blood flow. Research demonstrated that the integration of quantitative MCE and fractional flow reserve improved the definition of ischemic burden and the relative contribution of collaterals in non-critical coronary stenosis. MCE identified no-reflow and low-flow within and around myocardial infarction,respectively,and predicted the potential functional recovery of stunned myocardium using appropriate interventions. MCE exhibited diagnostic performances that were comparable to positron emission tomography in microvascular reserve and microvascular dysfunction in angina patients. Overall,MCE improved echocardiographic evaluations of ischemic heart disease in daily clinical practice,but the approval of regulatory authorities is lacking.
基金supported by Key Project of China Rehabilitation Research Center,Nos.2022ZX-05,2018ZX-08(both to JB)。
文摘Traumatic spinal cord injury is a devastating disorder chara cterized by sensory,motor,and autonomic dysfunction that seve rely compromises an individual's ability to perform activities of daily living.These adve rse outcomes are closely related to the complex mechanism of spinal cord injury,the limited regenerative capacity of central neurons,and the inhibitory environment fo rmed by traumatic injury.Disruption to the microcirculation is an important pathophysiological mechanism of spinal cord injury.A number of therapeutic agents have been shown to improve the injury environment,mitigate secondary damage,and/or promote regeneration and repair.Among them,the spinal cord microcirculation has become an important target for the treatment of spinal cord injury.Drug inte rventions targeting the microcirculation can improve the microenvironment and promote recovery following spinal cord injury.These drugs target the structure and function of the spinal cord microcirculation and are essential for maintaining the normal function of spinal neuro ns,axons,and glial cells.This review discusses the pathophysiological role of spinal cord microcirculation in spinal cord injury,including its structure and histopathological changes.Further,it summarizes the progress of drug therapies targeting the spinal cord mic rocirc ulation after spinal cord injury.
基金supported by the Sichuan Provincial Science and Technology Department Funds of China (2019YFS0436).
文摘Here, a patient with chest pain and <50% stenosis on coronary angiography, where ATP stress myocardial contrast echocardiography (MCE) revealed that coronary flow reserve was reduced to 1.71 was presented. Perfusion delay occurred in the left ventricular wall of the apex of the heart before ATP stress, and the perfusion delay area was significantly reduced at peak stress. Similar to the characteristics of "reverse redistribution" of radionuclide myocardium perfusion in coronary vasospasm, the delayed perfusion area in the recovery period was larger than that detected before stress. Together with increased spectral resistance of the distal segment of left anterior descending coronary artery and chest pain, these findings indicated coronary microvascular disease with spasmodic characteristics in this patient. The perfusion characteristics on ATP stress determined by MCE and changes in coronary spectrum have value for the diagnosis and treatment of coronary microvascular disease with spasmodic characteristics.
基金This work was supported by grants from the National Natural Sciences Foundation of China(No.81400177)Natural Science Foundation of Beijing Municipality(No.7154249).
文摘Background:Angiopoietin-2(Ang-2)is a type of endothelial growth factor involved in angiogenesis and vascular remodeling.Circulating Ang-2 levels are elevated in patients with obstructive coronary artery disease(CAD).This study aimed to evaluate the association between serum Ang-2 levels and coronary microvascular dysfunction in patients without obstructive CAD.Methods:A total of 125 patients with angina in the absence of obstructive CAD were included in this cross-sectional study.Coronary flow reserve(CFR)was measured in the distal left anterior descending coronary artery by trans-thoracic Doppler echocardiography.The patients were divided into the following two sub-groups according to CFR:the impaired CFR group with CFR values<2.5 and the preserved CFR group with CFR values≥2.5.Serum Ang-2 levels were determined using enzyme-linked immunosorbent assay.Independent predictors for impaired CFR were identified by binary logistic regression analysis.The receiveroperating characteristic curve was determined to evaluate the ability of serum Ang-2 in predicting impaired CFR.Results:We found that age,percentage of female sex,N-terminal pro-B-type natriuretic peptide levels,Ang-2 levels(763.3±264.9 vs.579.7±169.3 pg/mL,P<0.001),and the left atrial volume index were significantly higher in patients with impaired CFR than in patients with preserved CFR.Serum Ang-2 levels were negatively correlated with CFR(r=0.386,P<0.001).Binary logistic regression analysis showed that Ang-2(odds ratio:1.004,95%confidence interval[CI]:1.001–1.006,P=0.003)and age(odds ratio:1.088,95%CI:1.023–1.156,P=0.007)were independently associated with impaired CFR.Furthermore,Ang-2 was a significant predictor of impaired CFR on the receiver-operating characteristic curve(P<0.001).The area under the curve was 0.712(95%CI:0.612–0.813).Conclusions:High serum Ang-2 levels are independently associated with impaired CFR in patients with angina in the absence of obstructive CAD.
文摘Physicians cannot rely solely on the angiographic appearance of epicardial coronary artery stenosis when evaluating patients with myocardial ischemia. Instead, sound knowledge of coronary vascular physiology and of the methods currently available for its characterization can improve the diagnostic and prognostic accuracy of invasive assessment of the coronary circulation, and help improve clinical decision-making. In this article we summarize the current methods available for a thorough assessment of coronary physiology.
文摘Background: Microvascular perfusion, a kind of regional perfusion, plays important roles in delivering oxygen and nutrients, and regulating blood pressure and responses to inflammation. Aim: The aim of this research is to analyze the characteristics of microvascular perfusion by conducting pipe flow in a circular elastic tube. Methods: A model was established with circular elastic tube to mimic microvascular perfusion. The velocity of pressure waves was calculated according to the time that the liquid took to spilt over. What’s more, the characteristics and significance of microvascular flow and arteriovenous anastomoses (AVAs) were analyzed. Results: It took the liquid about 0.1 second to spill over from the model, and the velocity of pressure waves is greater than 100 m/s in the elastic pipe. A mechanical switch structure and the corresponding mechanism were proposed for microvascular perfusion in AVAs. Conclusion: Microvascular perfusion maintains a considerable constancy of hemodynamics in different tissues, when ventricular contraction changes perfusion pressure to meet metabolic demands appropriately. This theory will help us to gain a new perspective in microvascular flow.
基金supported by the National Key Project of Scientific and Technical Supporting Programs of China(Grant No.2014BAI11B06)the National Natural Science Foundation of China(Grant No.11172156)
文摘The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.
基金National Natural Science Foundation of China Youth Project,No.31702024Shandong Province Higher Educational Science and Technology Plan Project,No.J17KA258.
文摘Insulin resistance(IR)is the common pathophysiological basis of many metabolic diseases.IR is characterized by decreased glucose uptake in skeletal muscle and adipose tissue,especially in skeletal muscle.Skeletal muscle is the main target tissue of glucose uptake under insulin stimulation.Glucose uptake by skeletal muscle is complex,and it is controlled by many pathways.The PI3K/AKt/GSK-1 signaling pathway is not only the main pathway for insulin signal transduction but also an important mechanism for regulating blood glucose.From the binding of insulin to its receptors on the surface of target cells to the transportation of glucose from extracellular fluid to skeletal muscle,a series of signal transduction processes is completed,any of which potentially affects the physiological effects of insulin and leads to IR.Resistance exercise(RT)can reduce skeletal muscle IR and effectively improve blood glucose control and glycosylated hemoglobin level in patients with type 2 diabetes mellitus(T2DM).However,the exact mechanism by which RT improves skeletal muscle IR remains unclear.Therefore,this paper discusses the above problems by tracking the progress of the literature to deepen the correlation between RT and skeletal muscle insulin sensitivity and provide further evidence for the application of exercise therapy in IR.In conclusion,RT mainly improves insulin sensitivity of skeletal muscle by increasing muscle mass,microvascular blood flow,and glucose transporter-4 expression in skeletal muscle,as well as by reducing lipid accumulation and inflammation in skeletal muscle.Thus,it is potentially useful in the prevention and treatment of T2DM.
