臂踝脉搏波速度与老年心血管病高危因素的相关性研究

目的:探讨臂踝脉搏波速度(brachial-ankle pulse wave velocity,BaPWV)和心血管高危因素的相关性.方法:选取2011年1月～2012年1月在我院体检的居民共122例,根据体检结果分为非糖尿病及高血压组(A组,25例),糖尿病组(为B组,22例),高血压组(C组,46例)和高血压合并糖尿病组(D组,29例).记录各组的年龄、体重指数(BMI)、收缩压(SBP),舒张压(DBP)、心率(HR)、左心房内径(LAD)、左室舒张末期内径(LVIDd)、左室收缩末期内径(LVIDs)、右心室舒张末期内径(IVSd)、肺动脉收缩压(SPAP)和射血分数(EF).并检测肌酐(Scr)、尿酸(UA)、血糖(BG)、总胆固醇(TC)、甘油三酷(TG)、高密度脂蛋白胆固醇(HDL)、低密度脂蛋白胆固醇(LDL)、餐后血糖和糖化血红蛋白(HbA1c)水平.结果:各组之间Scr、UA、BG、TC、LDL、HbA1c、LAD、LVIDd、IVSd、LVIDs、SPAP、IMT、SBP、DBP、EF和BaPWV的差异有统计学意义(P＜0.05或＜0.01),而各组之间年龄、BMI、TG、HDL、餐后血糖、IMT和HR差异无统计学意义(P＞0.05).多元逐步回归分析发现:年龄、BG、TC和SBP是影响BaPWV的独立因素.结论:BaPWV在心血管高危因素患者中显著增加,年龄、BG、TC和SBP与BaPWV呈正相关.     

高血压患者脉搏波参数与脉搏波传导速度的相关性研究

目的:探讨高血压患者脉搏波参数与脉搏波传导速度的相关性,为从脉图上辨识高血压病及脉搏波参数的拓展应用提供参考。方法:选择2012年6月至2013年6月在北京安贞医院和北京人民医院门诊和住院确诊的原发性高血压患者32例作为实验组,并招募健康成人志愿者29例作为对照组。利用中医四诊合参辅助诊疗仪与皮尺分别采集两组受试者的左侧寸口脉图信息和主动脉至桡动脉的血管长度,计算脉搏波参数及脉搏波传导速度,采用方差分析和皮尔逊简单相关的统计方法分析高血压患者不同的脉搏波参数与其脉搏波传导速度的相关性。结果:与对照组比较,实验组的PWV显著升高,有显著性差异(P0.05)。实验组H2/H1明显高于对照组(P0.05),但H4/H1、T1/T、T2/T比值均显著低于对照组(P0.05),差异均有显著性意义(P0.05)。高血压患者的H2/H1、T1/T、T2/T、H4/H1均与其PWV相关,其中H2/H1与PWV呈显著正相关(P0.05),T1/T、T2/T与PWV呈显著负相关(P0.05),H4/H1与PWV呈一般正相关(P0.05)。结论:高血压患者的脉搏波参数与脉搏波传导速度具有显著相关性,且潮波出现的幅值与脉搏波传导速度有显著正相关;脉搏波上升支和潮波的时值与脉搏波传导速度具有显著负相关,重搏波相对高度与脉搏波传导速度具有一般相关关系,因而可通过脉搏波参数的变化了解高血压患者血管弹性的状态。     

In vivo noninvasive measurement of spatially resolved corneal elasticity in human eyes using Lamb wave optical coherence elastography

Current elastography techniques are limited in application to accurately assess spatially resolved corneal elasticity in vivo for human eyes. The air‐puff optical coherence elastography (OCE) with an eye motion artifacts correction algorithm is developed to distinguish the in vivo cornea vibration from the eye motion and visualize the Lamb wave propagation clearly in healthy subjects. Based on the Lamb wave model, the phase velocity dispersion curve in the high‐frequency is calculated to obtain spatially resolved corneal elasticity accurately with high repeatability. It is found that the corneal elasticity has regional variations and is correlated with intraocular pressure, which suggests that the method has the potential to provide noninvasive measurement of spatially resolved corneal elasticity in clinical practice.     

Noninvasive determination of local pulse wave velocity and wave intensity: changes with age and gender in the carotid and femoral arteries of healthy human

We recently introduced noninvasive methods to assess local pulse wave velocity (PWV) and wave intensity ((n)dI) in arteries based on measurements of flow velocity (U) and diameter (D). Although the methods were validated in an experimental setting, clinical application remains lacking. The aim of this study was therefore to investigate the effect of age and gender on PWV and (n)dI in the carotid and femoral arteries of an existing population. We measured D and U in the carotid and femoral arteries of 1,774 healthy subjects aged 35-55 yr, a subgroup of the Asklepios population. With the use of the lnDU-loop method, we calculated local PWV, which was used to determine arterial distensibility ((n)Ds). We then used the new algorithm to determine maximum forward and backward wave intensities ((n)dI(+max) and (n)dI(-min), respectively) and the reflection index ((n)RI). On average, PWV was higher, and (n)Ds was lower in the femoral than at the carotid arteries. At the carotid artery, PWV increased with age, but (n)Ds, (n)dI(+max), and (n)dI(-min) decreased; (n)RI did not change with age. At the femoral artery, PWV was higher, and (n)Ds was lower in male, but all parameters did not change significantly with age in both women and men. We conclude that the carotid artery is more affected by the aging process than the femoral artery, even in healthy subjects. The new techniques provide mechanical and hemodynamic parameters, requiring only D and U measurements, both of which can be acquired using ultrasound equipment widely available today, hence their advantage for potential use in the clinical setting.     

Involvement of Helicobacter pylori infection and impaired glucose metabolism in the increase of brachial-ankle pulse wave velocity

BACKGROUND: The role of Helicobacter pylori in the pathogenesis of atherosclerosis remains controversial. The present study was designed to elucidate the pathogenic role of H. pylori in the early stages of atherosclerosis by measurement of brachial-ankle pulse wave velocity (baPWV) in relation to glucose metabolism. MATERIALS AND METHODS: baPWV level, anti-H. pylori antibody, fasting blood glucose (FBG), and glycosylated hemoglobin A1c (HbA1c) and other conventional risk factors for cardiovascular diseases were measured in 947 subjects who attended their annual medical check-up. RESULTS: Multiple regression analyses indicated that age, gender (male), body mass index, FBG, systolic blood pressure, and smoking habits were each independently related to baPWV values. In younger subjects (30-49 years), H. pylori seropositivity was significantly correlated with an increase of baPWV levels (r = 0.100, p = .0445). baPWV values in the H. pylori-positive subjects with impaired glucose metabolism (IG: FBG >or= 110 mg/dL and/or HbA1c >or= 5.9%) were significantly greater than those in the H. pylori-negative subjects with IG (p = .0078). Furthermore, H. pylori-positive subjects with IG were at higher risk for increase of baPWV, in younger (r = 0.203, p < .0001) as well as in older subjects (50-69 years, r = 0.099, p = .0009). CONCLUSIONS: These results suggest that H. pylori seropositivity is a potential risk factor for increased baPWV levels, and that H. pylori infection accelerates the effect of IG on an increase of baPWV, especially in younger subjects. Thus, the possible interaction between H. pylori infection and IG may contribute to the early development of atherosclerosis.     

In vivo non-contact measurement of human iris elasticity by optical coherence elastography

Quantifying the mechanical properties of the iris can offer valuable insights into the pathophysiology of primary angle closure glaucoma. However, current techniques for iris elastography remain ex vivo with limited clinical applications. This article describes a proposition for a non-contact and non-invasive air-puff optical coherence elastography (OCE) system that can evaluate iris elasticity in vivo. Ten eyes recruited from seven subjects underwent OCE imaging acquisition under three different illumination conditions. The Young's modulus of each eye was detected and shown to be inversely proportional to the iris length, indicating a relationship between mechanical properties and morphology of the iris. With its noninvasive and high-resolution features, this air-puff system shows great potential for applications in clinical ophthalmology.     

An innovative numerical approach to resolve the pulse wave velocity in a healthy thoracic aorta model

Aortic dissection and atherosclerosis are highly fatal diseases. The development of both diseases is closely associated with highly complex haemodynamics. Thus, in predicting the onset of cardiac disease, it is desirable to obtain a detailed understanding of the flowfield characteristics in the human cardiovascular circulatory system. Accordingly, in this study, a numerical model of a normal human thoracic aorta is constructed using the geometry information obtained from a phase-contrast magnetic resonance imaging (PC-MRI) technique. The interaction between the blood flow and the vessel wall dynamics is then investigated using a coupled fluid–structure interaction (FSI) analysis. The simulations focus specifically on the flowfield characteristics and pulse wave velocity (PWV) of the blood flow. Instead of using a conventional PC-MRI method to measure PWV, we present an innovative application of using the FSI approach to numerically resolve PWV for the assessment of wall compliance in a thoracic aorta model. The estimated PWV for a normal thoracic aorta agrees well with the results obtained via PC-MRI measurement. In addition, simulations which consider the FSI effect yield a lower predicted value of the wall shear stress at certain locations in the cardiac cycle than models which assume a rigid vessel wall. Consequently, the model provides a suitable basis for the future development of more sophisticated methods capable of performing the computer-aided analysis of aortic blood flows.     

In vivo dosimetry during DSA of the carotid and renal arteries. Deriviation of local DRLs

The Euratom directive 97/43 recommends the use of patient dose surveys in diagnostic radiology and the establishment of diagnostic reference dose levels (DRLs). The aims of this study are to perform measurements of the entrance surface dose (ESD) during diagnostic digital subtraction angiography (DSA) of the renal and carotid arteries using thermoluminescence dosemeters (TLDs), extraction of local DRLs, and calculation of the effective dose. Dose measurement for the staff was also performed. Dose measurements were performed on 48 participating patients. The mean effective dose was calculated to be 15.9 mSv and 8.9 mSv, for the renal and carotid DSA, respectively. The effective dose of the radiologist was calculated to be 0.022 mSv and 0.023 mSv per procedure for renal and carotid DSA respectively, when wearing a protective apron and using a movable ceiling mounted shield. Radiation dose variation depends on the physical characteristics of the patient, on the procedure preferences by radiologists and on the difficulties in conducting the procedures. The lack of DRLs for the specific examinations lead the research team to choose the DRL for DSA of the renal arteries to be 169 mGy for ESD at the pelvic region and for DSA of the carotid arteries to be 313 mGy for ESD at the region of the aortic arc.     

Combined effect of pulsed electromagnetic field and sound wave on In vitro and In vivo neural differentiation of human mesenchymal stem cells

Biophysical wave stimulus has been used as an effective tool to promote cellular maturation and differentiation in the construction of engineered tissue. Pulsed electromagnetic fields (PEMFs) and sound waves have been selected as effective stimuli that can promote neural differentiation. The aim of this study was to investigate the synergistic effect of PEMFs and sound waves on the neural differentiation potential in vitro and in vivo using human bone marrow mesenchymal stem cells (hBM–MSCs). In vitro, neural‐related genes in hBM–MSCs were accelerated by the combined exposure to both waves more than by individual exposure to PEMFs or sound waves. The combined wave also up‐regulated the expression of neural and synaptic‐related proteins in a three‐dimensional (3‐D) culture system through the phosphorylation of extracellular signal‐related kinase. In a mouse model of photochemically induced ischemia, exposure to the combined wave reduced the infarction volume and improved post‐injury behavioral activity. These results indicate that a combined stimulus of biophysical waves, PEMFs and sound can enhance and possibly affect the differentiation of MSCs into neural cells. Our study is meaningful for highlighting the potential of combined wave for neurogenic effects and providing new therapeutic approaches for neural cell therapy. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:201–211, 2017     

Perturbation approximation of solutions of a nonlinear inverse problem arising in olfaction experimentation

In this paper, a mathematical model of the diffusion of cAMP into olfactory cilia and the resulting electrical activity is presented. The model, which consists of two nonlinear differential equations, is studied using perturbation techniques. The unknowns in the problem are the concentration of cAMP, the membrane potential, and the quantity of most interest in this work: the distribution of CNG channels along the length of a cilium. Experimental measurements of the total current during this diffusion process provide an extra boundary condition which helps determine the unknown distribution function. A simple perturbation approximation is derived and used to solve this inverse problem and thus obtain estimates of the spatial distribution of CNG ion channels along the length of a cilium. A one-dimensional computer minimization and a special delay iteration are used with the perturbation formulas to obtain approximate channel distributions in the cases of simulated and experimental data.      

Thermomechanical behavior of human carotid arteries in the passive state

Localized heating or cooling is expanding the clinical procedures used to treat cardiovascular diseases. Advantageous implementation and development of these methods are linked indissolubly to a deeper understanding of the arterial response to combined mechanical and thermal loads. Despite this, the basic thermomechanical behavior of human blood vessels still remains largely unknown, primarily due to the lack of appropriate experimental data. In this work, the influence of temperature on the passive behavior of human carotid arteries was studied in vitro by means of inflation tests. Eleven carotid segments were tested in the range 0-200 mmHg at four different temperatures of 17, 27, 37, and 42 degrees C. The results show that the combined change of temperature and stress has a dramatic effect on the dilatation coefficient of the arterial wall, which is shifted from negative to positive depending on the stress state, whereas the structural stiffness of the arterial wall does not change appreciably in the range of temperatures tested.     

Dynamical properties of model gene networks and implications for the inverse problem

We study the inverse problem, or the "reverse-engineering" problem, for two abstract models of gene expression dynamics, discrete-time Boolean networks and continuous-time switching networks. Formally, the inverse problem is similar for both types of networks. For each gene, its regulators and its Boolean dynamics function must be identified. However, differences in the dynamical properties of these two types of networks affect the amount of data that is necessary for solving the inverse problem. We derive estimates for the average amounts of time series data required to solve the inverse problem for randomly generated Boolean and continuous-time switching networks. We also derive a lower bound on the amount of data needed that holds for both types of networks. We find that the amount of data required is logarithmic in the number of genes for Boolean networks, matching the general lower bound and previous theory, but are superlinear in the number of genes for continuous-time switching networks. We also find that the amount of data needed scales as 2(K), where K is the number of regulators per gene, rather than 2(2K), as previous theory suggests.     

The ultrastructure of peripheral arteries during the development of DOCA hypertension in the rat

Summary The ultrastructure of the unconstricted superficial epigastric and femoral arteries is described in normal rats and in animals with hypertension induced by unilateral nephrectomy, by subcutaneous injections of desoxycorticosterone acetate and drinking of 1% NaCl. The femoral artery showed by far the greater response to the DOCA-saline treatment. In both vessels, the smooth-muscle cells changed from the normal spindle shape to a blunt ended outline with numerous pinocytotic vesicles and prolific collagen production. With long term hypertension, particularly in the femoral artery, the smooth-muscle cell profiles became very irregular. Hypertrophy of the organelles of the smooth-muscle cells was associated with an increase in the intercellular material which gradually changed from a mainly collagenous character to mainly vesicular. Lysosomal activity indicated cell disintegration. White blood cells adhere to the endothelium in hypertensive rats and there was an increase in subendothelial material. The number of intimal smooth-muscle cells increased noticeably in the femoral artery. In both arteries, the adventitial fibroblasts hypertrophied in hypertensive rats. In animals with an elevated blood pressure the morphological response was observed as early as 4 to 7 days after initiation of treatment.This work was supported by grants from the British Columbia Heart Foundation and the Medical Research Council of Canada.The authors are indebted to Miyoshi Nakashima for her invaluable assistance with these experiments.     

In vivo quantification of cholesterol content in human carotid arteries by quantitative Gamma-camera imaging after injection of autologous low density lipoproteins (LDL)

Low density lipoprotiens (LDL) were isolated by immunoaffinity chromatography from 18 patients (31–70 years) suffering from primary hypercholesterolemia with angiographically proven atherosclerosis of either one or both carotid arteries. LDL were labeled with ¹²³I (1 mCi/mg LDL) by the iodine monochloride method followed by purification with dialysis and immediately reinjected thereafer. Gamma-camera serial controls over carotid regions allowed visual detection of uptake of the radiocompound uptake in 12 out of the 18 patients. The lipid entry ratio (LER; counts over the vascular region/pixel as compared to the contralateral side after background subtraction) confirmed the visual findings. Whole body images performed until 20 h after reinjection showed 3 different kinetic types of LDL-influx into the vessel wall: decreasing (type I), increasing and then decreasing (type II) and continuously increasing (type III) with time. Four patients underwent endarterectomy within 2–7 weeks after gamma-camera imaging. Histological control revealed an extensive amount of “foam cells” in tissue samples derived during surgery and an absence of endothelial lining in samples belonging to patients with type II kinetics.     

An inverse problem in estimating the laser irradiance and thermal damage in laser-irradiated biological tissue with a dual-phase-lag model

The aim of this study is to solve an inverse heat conduction problem to estimate the unknown time-dependent laser irradiance and thermal damage in laser-irradiated biological tissue from the temperature measurements taken within the tissue. The dual-phase-lag model is considered in the formulation of heat conduction equation. The inverse algorithm used in the study is based on the conjugate gradient method and the discrepancy principle. The effect of measurement errors and measurement locations on the estimation accuracy is also investigated. Two different examples of laser irradiance are discussed. Results show that the unknown laser irradiance and thermal damage can be predicted precisely by using the present approach for the test cases considered in this study.     

An ultrasound elastography method to determine the local stiffness of arteries with guided circumferential waves

Arterial stiffness is highly correlated with the functions of the artery and may serve as an important diagnostic criterion for some cardiovascular diseases. To date, it remains a challenge to quantitatively assess local arterial stiffness in a non-invasive manner. To address this challenge, we investigated the possibility of determining arterial stiffness using the guided circumferential wave (GCW) induced in the arterial wall by a focused acoustic radiation force. The theoretical model for the dispersion analysis of the GCW is presented, and a finite element model has been established to calculate the dispersion curve. Our results show that under described conditions, the dispersion relations of the GCW are basically independent of the curvature of the arterial wall and can be well-described using the Lamb wave (LW) model. Based on this conclusion, an inverse method is proposed to characterize the elastic modulus of artery. Both numerical experiments and phantom experiments had been performed to validate the proposed method. We show that our method can be applied to the cases in which the artery has local stenosis and/or the geometry of the artery cross-section is irregular; therefore, this method holds great potential for clinical use.     

Interdependence of pulse wave variables in the human fetal aorta

The problem of inferring the state of fetal circulation from diameter pulse waves in the descending aorta was studied with the aid of statistical methods in 12 fetuses in late uncomplicated gestation. By means of a phase-locked, echo-tracking ultrasound technique, aorta diameter-time waveforms and pulse propagation velocities were measured. In a factor analysis, three independent factors explained 75% of the total variance of variables in the waveforms. Relationships between some of the variables and biophysical events are suggested; they await confirmation from animal experiments, in order to develop a practical method for assessing fetal circulation.     

脉搏波传导速度检测在评价高血压病患者大动脉弹性中的应用 与影响因素分析

目的:探讨脉搏波传导速度(PWV)检测在评估高血压病患者大动脉弹性中的应用价值与影响因素分析 方法:采用分层整体抽样法随机抽取高血压病患者2178例,同时抽取非高血压2182人作为对照组.应用Complior SP VP-1000动脉硬化检测仪测定颈一股动脉脉搏波传导速度(C-FPWV)评估大动脉弹性.采用多元逐步线性回归分析性别、年龄、体质指数(BMI)、收缩压(SBP)、舒张压(DBP)、总胆固醇(TC)、甘油三脂(TG)、空腹血糖(FPG)和尿酸(UA)等指标与高血压痛患者大动脉弹性下降的影响因素.结果:C-FPWV平均值高血压组(1594± 264cm/s)显著高于对照组(1216± 231cm/s),两组差异有显著性意义(X2=31.659,P=0.00).＞40岁各年龄段PWV值上升程度,高血压组明显高于对照组(X2＝ 18.954～36.924,P=0.00),两组PWV值上升程度与年龄呈正相关.多元逐步线性回归分析表明:BMI≥28kg/m2、SBP≥ 140mmHg、DBP≥90mmHg、TC＞5.28± 0.62 mmol/L、TG＞ 1.68± 0.64mmol/L等指标高血压组明显高于对照组(t=14.314～17.428,P＜0.05).在性别、UA和FPG等指标两组无明显差异(X2=6.368～13.618,P＞0.05).结论:高血压痛患者PWV值上升程度显著高于非高血压者,BMI、SBP、TG、TC是高血压病患者大动脉弹性下降的主要影响因素.PWV值可作为评价大动脉弹性的可靠指标.     

On the possibility for computing the transmembrane potential in the heart with a one shot method: an inverse problem

We analyze the possibility for using body surface potential maps (BSPMs), a priori information about the voltage distribution in the heart and the bidomain equations to compute the transmembrane potential throughout the myocardium. Our approach is defined in terms of an inverse problem for elliptic partial differential equations (PDEs). More precisely, we formulate it in terms of an output least squares framework in which a goal functional is minimized subject to suitable PDE constraints. The problem is highly unstable and, even under optimal recording conditions, it does not have a unique solution. We propose a methodology for stabilizing and enforcing uniqueness for this inverse problem. Moreover, a fully implicit method for solving the involved minimization problem is presented. In other words, we show how one may solve it in terms of a system consisting of three linear elliptic PDEs, i.e. we derive a so-called one shot method (also commonly referred to as an all-at-once method). Finally, our theoretical findings are illuminated by a series of numerical experiments. These examples indicate that, in the presence of regional ischemia, it might be possible to approximately recover the transmembrane potential during the resting and plateau phases of the heart cycle. This is probably due to the fact that rather accurate a priori information is available during these time intervals. The problem of computing the transmembrane potential at an arbitrary time instance during a heart beat is still an open problem.