Inverse computation for cardiac sources using single current dipole and current multipole models

Two cardiac functional models are constructed in this paper. One is a single current model and the other is a current multipole model. Parameters denoting the properties of these two models are calculated by a least-square fit to the measurements using a simulated annealing algorithm. The measured signals are detected at 36 observation nodes by a superconducting quantum interference device (SQUID). By studying the trends of position, orientation and magnitude of the single current dipole model and the current multipole model in the QRS complex during one time span and comparing the reconstructed magnetocardiography (MCG) of these two cardiac models, we find that the current multipole model is a more appropriate model to represent cardiac electrophysiological activity.     

Effects of Cardiac Resynchronization Therapy on Cardio-Respiratory Coupling

In this study, the effect of cardiac resynchronization therapy (CRT) on the relationship between the cardiovascular and respiratory systems in heart failure subjects was examined for the first time. We hypothesized that alterations in cardio-respiratory interactions, after CRT implantation, quantified by signal complexity, could be a marker of a favorable CRT response. Sample entropy and scaling exponents were calculated from synchronously recorded cardiac and respiratory signals 20 min in duration, collected in 47 heart failure patients at rest, before and 9 months after CRT implantation. Further, cross-sample entropy between these signals was calculated. After CRT, all patients had lower heart rate and CRT responders had reduced breathing frequency. Results revealed that higher cardiac rhythm complexity in CRT non-responders was associated with weak correlations of cardiac rhythm at baseline measurement over long scales and over short scales at follow-up recording. Unlike CRT responders, in non-responders, a significant difference in respiratory rhythm complexity between measurements could be consequence of divergent changes in correlation properties of the respiratory signal over short and long scales. Asynchrony between cardiac and respiratory rhythm increased significantly in CRT non-responders during follow-up. Quantification of complexity and synchrony between cardiac and respiratory signals shows significant associations between CRT success and stability of cardio-respiratory coupling.     

基于实验的心肌被动力本构模型

在狗心脏外科手术和心肌力学性能试验的基础上,对心肌力学性能实验数据进行处理和拟合,并应用有限元方法对心肌的单拉实验、松弛实验进行数值模拟和计算. 得到不同心肌位点的本构模型的非线性弹性和黏性参数,从而发展了心肌被动力的非线性黏弹性本构模型,体现了心脏力学行为的非均匀性和黏弹性. 在理论模型和试验数据的基础上,开发了有限元软件ABAQUS的VUMAT材料子程序,应用于数值心脏的仿真研究.      

Laser-induced fluorescence of cardiac tissue with calcinosis

Investigations of laser-induced fluorescence spectra for human cardiac valve tissue with calcinosis are performed as compared to similar spectra of bone and myocardial tissue of an animal that are excited by an excimer laser with a 248-nm wavelength. It is shown that a healthy tissue has a laser-induced fluorescence maximum in the region of 300–400 nm which corresponds to protein tissue luminescence. For tissue affected by calcinosis, the laser-induced fluorescence spectra differ significantly from the spectra of healthy tissue and have a maximum in the region of 400–500 nm. The obtained results offer the prospects for using laser-induced fluorescence to diagnose tissue with calcinosis in open-heart surgery. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 539–541, July–August, 1997.     

Au/In2O3 Nanocubes Based Label-free Aptasensor for Ultrasensitive and Rapid Recognition of Cardiac Troponin I

Cardiac Troponin I (cTnI) is a preferred biomarker to diagnose acute myocardial infarction which is one of the leading risks to health globally due to its short term. However, clinical analyzers are difficult to achieve its on-site quantitative detection. A novel label-free aptasensor was constructed to realize ultrasensitive and rapid recognition of cTnI. A nanocubic AuNPs/In₂O₃ composite was designed to provide synergistic effects of abundant active sites and signal magnification for aptamers grafting. Relying on a conductance-dependence strategy, this aptasensor can achieve the quantitative detection within 10 min, which is much faster than state-of-the-art analyzers, as well as exhibiting an ultrawide linear range of 0.1–1000 ng/mL and a low detection limit of 0.06 ng/mL with an excellent selectivity in the analysis of human serum.     

Adult onset cardiac dilatation in a transgenic mouse line with Galβ1,3GalNAc α2,3-sialyltransferase II (ST3Gal-II) transgenes: a new model for dilated cardiomyopathy

Sugar chain abnormalities in glycolipids and glycoproteins are associated with various diseases. Here, we report an adult onset cardiac dilatation in a transgenic mouse line with Galβ1,3GalNAc α2,3-sialyltransferase II (ST3Gal-II) transgenes. The transgenic hearts at the end-stage, at around 7 months old, were enlarged, with enlarged cavities and thin, low-tensile walls, typical of dilated cardiomyopathy. Although no apparent change was found in heart gangliosides, glycosylation of heart proteins was altered. Interestingly, sugar moieties not directly related to the ST3Gal-II catalytic reaction were also changed. Significant increases in calreticulin and calnexin were observed in hearts of the transgenic mice. These results suggest that expression of ST3Gal-II transgenes induces abnormal protein glycosylation, which disorganizes the endoplasmic/sarcoplasmic reticulum quality control system and elevates the calreticulin/calnexin level, resulting in suppression of cardiac function. The transgenic mice showed 100% incidence of adult onset cardiac dilatation, suggesting great potential as a new model for dilated cardiomyopathy.     

Oxidative stress is associated with the number of components of metabolic syndrome: LIPGENE study

Previous evidence supports the important role that oxidative stress (OxS) plays in metabolic syndrome (MetS)-related manifestations. We determined the relationship between the number of MetS components and the degree of OxS in MetS patients. In this comparative cross-sectional study from the LIPGENE cohort, a total of 91 MetS patients (43 men and 48 women; aged between 45 and 68 years) were divided into four groups based on the number of MetS components: subjects with 2, 3, 4 and 5 MetS components (n=20, 31, 28 and 12, respectively). We measured ischemic reactive hyperemia (IRH), plasma levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), total nitrite, lipid peroxidation products (LPO), hydrogen peroxide (H₂O₂), superoxide dismutase (SOD) and glutathione peroxidase (GPx) plasma activities. sVCAM-1, H₂O₂ and LPO levels were lower in subjects with 2 or 3 MetS components than subjects with 4 or 5 MetS components. IRH and total nitrite levels were higher in subjects with 2 or 3 MetS components than subjects with 4 or 5 MetS components. SOD and GPx activities were lower in subjects with 2 MetS components than subjects with 4 or 5 MetS components. Waist circumference, weight, age, homeostatic model assessment-β, triglycerides (TGs), high-density lipoprotein and sVCAM-1 levels were significantly correlated with SOD activity. MetS subjects with more MetS components may have a higher OxS level. Furthermore, association between SOD activity and MetS components may indicate that this variable could be the most relevant OxS biomarker in patients suffering from MetS and could be used as a predictive tool to determine the degree of the underlying OxS in MetS.     

多腔体心脏磁场模型的研究与应用

利用核磁共振图像(MRI)中提取的人体和心脏边界,根据边界元方法(BEM)建立了一个考虑左、右心房和心室的多腔体心脏磁场模型.分析了用该模型得到的36通道心脏磁场数据和特定时刻的磁场图.并在此基础上,研究了完全性右束支传导阻滞(CRBBB)和完全性左束支传导阻滞(CLBBB)病人ST-T段的心脏电活动.结果显示,用移动单电流偶极子模拟的单束支电兴奋传导所产生的磁场图与用超导量子干涉器(SQUID)测量的CRBBB/CLBBB病人数据绘制的心脏复极时的心磁图(MCG)十分相似.结果表明,该多腔体心脏BEM模型可用于CLBBB/CRBBB病人心脏磁场逆问题的研究.此外,文中给出了两个评价指标:测量平面上多腔体与单腔体的心脏磁场强度极大值之比,以及两种模型的36个测量点上磁场强度均方根之比.分析表明,多腔体心脏模型更贴近人体心脏的实际情况.该模型中心脏组织电导率参数的取值,以及等效电流偶极子的位置和个数决定了磁场的强度和分布.     

Structure elucidation of phototransformation products of unapproved analogs of the erectile dysfunction drug sildenafil in artificial freshwater with UPLC‐Q Exactive‐MS

In this study, four unapproved analogues of Sildenafil (SDF) were photodegraded under synthetic sunlight in artificial freshwater. Homosildenafil (H‐SDF), hydroxyhomo‐sildenafil (HH‐SDF), norneosildenafil (NR‐SDF) and thiosildenafil (T‐SDF) were selected because they are frequently detected as adulterants in natural herbal products. Using UPLC‐Orbitrap (Q Exactive)‐MS, six photoproducts common to H‐SDF, HH‐SDF and T‐SDF and nine unique transformation products of different molecular weights were identified based on their high‐resolution (+)ESI product ion spectra. Mass spectral analysis of deuterated H‐SDF, labeled on the N‐ethyl group, allowed to gain mechanistic insight into the fragmentation pathway of the substituted piperazine ring and to support the postulated photoproduct structures. The mass spectral fragmentation confirmed the stepwise destruction of the piperazine ring eventually producing a sulfonic acid derivative (C₁₇H₂₀N₄O₅S: 392.1151 Da). In contrast, the photodegradation of NR‐SDF, which lacks a piperazine ring in its structure, formed only two prominent photoproducts originating from N,N‐dealkylation of the sulfonamide followed by hydrolysis. The current work constitutes the first study on the photodegradation of analogs of erectile dysfunction drugs and the first detection of two transformation products (m/z 449 and 489) in environmental samples. Copyright © 2014 John Wiley & Sons, Ltd.