心脏电活动的计算机仿真模型

一、前言 自从100多年前人们发现体表心电以来在心脏电生理学方面和心电诊断学方面进行了大量的研究和临床的实践。尤其是心脏电生理学方面的研究十分细致、深入。从心肌细胞的电生理特性到细胞的除极和复极。以致兴奋在整个心脏中的传播机理和过程等都进行了很仔细的研究。另一方面,心电诊断学的发展相对比较粗糙和缓慢。究其原因,可以认     

基于心脏电生理模型的心律失常机制研究进展

揭示发病机制是心律失常诊断、治疗、药物研发和设备设计的关键.整合当前在心脏分子生物学、生物化学、生理学及解剖学方面的最新成果,构建从离子通道、心肌细胞、心肌纤维、心肌组织、心脏器官到躯体各个层次的多尺度多模态心脏电生理模型,用于系统研究微观局部变化发生、发展、转化为宏观心律失常表现的过程,将彻底改变传统从基因突变、蛋白质表达、细胞电生理、临床表现单独研究心律失常的方式,实现微观与宏观研究的统一,使心脏电生理模型成为系统研究心律失常发病机制的有力手段.本文综述了心脏电生理模型的构建方法和研究进展,讨论了多尺度心脏电生理模型在揭示心律失常机制研究中的作用和地位,给出了基于心脏电生理模型心律失常研究的挑战和重要发展方向.     

建立心脏功能研究的计算机模型

用计算机模拟建立生物学模型在现代生物学研究中是一种非常重要的方法.就心脏而言,从基因到细胞到整个器官,现在都建立了大量的计算机模型.这些模型在帮助我们证实心脏功能机制的假说、预测和评估药物的作用以及诊断疾病等方面都起着重要作用.就心脏不同层面的计算机模型进行了简要的综述.     

基于心脏模型推断心肌病理状态的仿真研究

采用有限元方法建立了人体心脏力学模型, 并基于该仿真模型提出了一种无创推断心肌病理状态的新方案,并通过心肌梗塞定位试验加以验证。仿真研究表明这种基于模型参数优化解的方法能将心肌梗塞定位到模型基本单元的空间范围,可用于提取心肌疾病信息。     

南京地区蒸散发降尺度研究--基于增强型时空自适应反射融合模型

蒸散发是水文循环的重要组成部分,获取高时空分辨率的数据能够更加精细化蒸散发的时空变化规律,对于水资源管理、生态水文过程量化具有重要意义。由于单一传感器反演的蒸散发无法同时具有高空间和高时间分辨率,以南京地区为例,首先结合Landsat-8遥感影像数据和气象数据,采用基于能量平衡原理的SEBS模型估算日蒸散量。在此基础上,选取典型区域采用基于增强型时空自适应反射融合模型(ESTARFM)将估算的蒸散发结果与低空间分辨率的MOD16A2蒸散发产品数据进行时空融合降尺度研究,并评价模型的融合精度。结果表明：(1)SEBS模型估算的蒸散发结果与蒸发皿折算后的数据、MOD16A2产品数据的平均相对误差分别为0.14 mm/d和0.22 mm/d。(2)南京地区蒸散量季节差异明显,表现为夏季>秋季>冬季;各区在夏季的日平均蒸散量差异也较大,六合区蒸散量最大,秦淮区最小;另外,蒸散量分布受土地利用类型的影响,总体上表现为水域>林地>耕地>草地>其他,且植被覆盖度较高的区域蒸散量较大。(3)基于ESTARFM模型融合的蒸散发结果与基于Landsat-8遥感影像反演的...     

生理节律与日常活动对人体疲劳程度的影响

目的:研究生理节律和日常活动分别对人体疲劳程度的影响大小。方法:选取某校7名大学生志愿者,在军训期间对每日军训科目严格限制条件下进行该实验,以闪光临界融合频率、心率变异性、反应时、静态姿势图TLX-NASA量表评分作为指标,对每天分别在训练前和训练后疲劳程度的大小进行测量,以这些指标描述训练前后的疲劳程度。结果:反应时降低(0.60±0.09)、反应正确率提高(0.97±0.03);闪光临界光融合频率升高(40.84±2.14);心率变异性TP(3076.60±382.08)降低、心率变异性SDNN(55.28±16.85)降低;静态姿势图晃动减少,中低频率段(0.15±0.01)、前后方向重心变位(7.92±0.63),TLX-NASA量表评分降低(30.47±10.23)。以上差异均具有统计学意义(P<0.05)。结论:生理节律相对于日常活动对机体的疲劳状态有更大的影响。     

基于机制的生理药动- 药效学模型研究进展

生理药动- 药效学模型通过对生物学过程的描述,可预测体内药物的吸收、分布、代谢、排泄以及进一步的生理生化反应。这类模型是通过已知的生化/ 生理基础来构建,采用了一种“自下而上”的建模方法,并利用数学方法对生理过程及药物的作用机制作出准确的描述。其中药效学部分,根据预测目的和药物作用的复杂性,可进一步分为基于经验的和基于机制的效应模型,这两种模型均可与基于机制的生理药动学模型相连接,最终预测药物的体内处置和效应。基于机制的生理药动- 药效学模型的优势在于：可外推性、新的影响因素的可纳入性以及可用于未知领域的预测等。随着实验技术的不断革新,药物作用机制的逐渐明确,这类模型越来越多的被成功应用于药物研发及风险评估中。综述生理药动- 药效学模型的构建策略与分类以及在药物研发和风险评估中的应用研究。     

高原鼢鼠种群能量动态的研究 Ⅱ.每日能量收支模型的探讨

本文根据近年来国内外有关地下鼠种群能学研究的进展,结合地下鼠能量代谢的特点,提出了一个以平均每日代谢率为基础的估计地下鼠个体每日能量收支的经验模型。文中以高原鼢鼠为例,通过一系列的参数估计,采用本文提出的模型,计算出个体在春季的每日能收支为202.27千焦耳;日挖掘活动时间为2.61小时,相当于巢外总活动时间的80％;掘土价达57.93千焦耳/日。本文提出的模型避免了直接观测个体日挖掘活动时间这一仍难解决的问题,并把动物的能量需要同环境质量结合在一起,用定量的方式描述它们之间的关系,这不仅有助于地下鼠种群能学的研究,而且为探讨地下鼠的生境选择奠定了基础。     

基于生理发育时间的日光温室茄子发育模拟模型

本研究将温度对茄子发育速率影响效应的大小用相对热效应(RTE)来衡量,通过研究Beta函数的性质提出基于幂函数的模型来描述RTE与温度之间的关系.采用生理发育时间(Physiological Development'Time,PDT)作为定量发育进程的尺度,建立了温室茄子发育模拟模型.利用模型对日光温室2年3茬茄子生长发育期资料进行检验的结果表明:模型能较好地预测各个发育期(发芽、苗期、开花座果、结果和采收期)的出现时间和持续时间,各生育期模拟值与观测值的回归估计标准误差(RMSE)分别为1.0d,1.73d,0.82d,1.41d,2.38d,显著优于以有效积温模拟模型的预测精度(其生育期模拟的RMSE分别为2.38d,7.14d,1.73d,5.07d,8.25d).     

基于非线性控制模型的药物动力学的问题研究

在临床和临床前的研究中,确定最大的可允许的剂量水平可以避免化学药品导致的毒性．通过血流灌注限制性的消除隔室模型,完成对药物在人体中处置过程的预测,并能得到机体功能的生理或病理改变所引起的药物配置动力学的变化．本文针对生理药物动力学的特点,利用模糊控制模型,并结合生理药物动力学,给出其了动态输出反馈控制方法．     

大蒜功效成分蒜氨酸的提取与生理活性研究

目的:获取高纯度蒜氨酸并研究其部分功能。方法:采用改进的方法提取蒜氨酸。用体外实验检测其抗菌和抗肿瘤活性。结果:获得了高纯度的蒜氨酸,抑菌实验表明,高纯蒜氨酸对大肠杆菌(Eschrichia coli)、枯草芽孢杆菌(Bacillus subtilis)、金黄色葡萄球菌(Staphylococcus aureus)、痢疾杆菌(Shigella dysenteriae)、幽门螺旋杆菌(Helicobacter pylori)等测试菌株有极强的杀死作用,其MIC分别为4.06×10-3mg/mL、4.06×10-3mg/mL、4.06×10-3mg/mL、8.13×10-3mg/mL、1.63×10-2mg/mL,体外细胞实验结果显示,蒜氨酸对肿瘤细胞人急性早幼粒白血病细胞(HL-60)和人肝癌细胞(H-7402)有很高的抑制和杀死作用。结论:该提取方法适合于大规模生产,蒜氨酸在食品防腐、抗肿瘤药物开发和保健品的研制上有很好的应用潜力和应用前景。     

碳酸钙胁迫下枳壳愈伤组织的某些生理生化指标变化

测定碳酸钙(CaCO3)胁迫下枳壳愈伤组织的某些生理生化指标的结果表明:除全Fe含量外,CaCO3浓度与过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、活性Fe含量、可溶性蛋白质含量、愈伤组织增重均呈显著或极显著负相关,与培养液pH值呈显著正相关;随着培养的进程,POD活性、活性Fe和可溶性蛋白质含量、愈伤组织增重呈降低趋势,SOD和CAT活性先升后降,含高浓度CaCO3的培养液pH值仅在20日左右略有降低.     

农田生态系统能量投入产出模型及其应用研究

本文在分析农田生态系统能量转化规律的基础上,建立了农田生态系统的能量投入产出模型,提出了确定能量合理投入范围的方法,并结合德清县农业生产实际对此模型和方法进行了初步应用,提出了该县农田生态系统能量投入的优化对策。     

3D Printing of Tunable Energy Storage Devices with Both High Areal and Volumetric Energy Densities

Developing advanced supercapacitors with both high areal and volumetric energy densities remains challenging. In this work, self‐supported, compact carbon composite electrodes are designed with tunable thickness using 3D printing technology for high‐energy‐density supercapacitors. The 3D carbon composite electrodes are composed of the closely stacked and aligned active carbon/carbon nanotube/reduced graphene oxide (AC/CNT/rGO) composite filaments. The AC microparticles are uniformly embedded in the wrinkled CNT/rGO conductive networks without using polymer binders, which contributes to the formation of abundant open and hierarchical pores. The 3D‐printed ultrathick AC/CNT/rGO composite electrode (ten layers) features high areal and volumetric mass loadings of 56.9 mg cm^?2 and 256.3 mg cm^?3, respectively. The symmetric cell assembled with the 3D‐printed thin GO separator and ultrathick AC/CNT/rGO electrodes can possess both high areal and volumetric capacitances of 4.56 F cm^?2 and 10.28 F cm^?3, respectively. Correspondingly, the assembled ultrathick and compact symmetric cell achieves high areal and volumetric energy densities of 0.63 mWh cm^?2 and 1.43 mWh cm^?3, respectively. The all‐component extrusion‐based 3D printing offers a promising strategy for the fabrication of multiscale and multidimensional structures of various high‐energy‐density electrochemical energy storage devices.     

结扎冠状动脉后快速起搏方法建立急性心功能不全动物模型

目的探讨建立急性心功能不全动物模型的可行性。方法完全结扎犬前降支,进行快速右室起搏,使心输出量(CCO)较基础状态稳定地下降50%,分别测定基础及心输出量下降状态下的血压(AP)、血氧(SaO2)、平均右房压(mRAP)、平均肺毛压(mPCWP)、系统血管阻力(SVR)、心腔大小、左室射血分数(LVEF)、血浆肾素活性(PRA)、内皮素(ET)、尿量(UO)、血肌酐(Scr)、肌酐清除率(Ccr)。结果结扎LAD和快速右室起搏后,CCO较基础状态均稳定地下降50%,CCO降低后,AP、SaO2显著下降,mRAP、mPCWP、SVR显著升高;心脏各腔室明显扩大,LVEF显著降低;PRA、ET、Scr明显升高,UO、Ccr明显下降。结论结扎冠状动脉前降支及快速右心室起搏可成功制作急性心功能不全的动物模型。     

短期高温伤害蓝藻Anabaena7120的固氮活性恢复与生理条件的关系

蓝藻经短期高温处理后,其固氮活性显著下降,但在合宜条件下,这种受伤害的固氮活性可以有一定程度的恢复。光下不仅比暗中恢复快,而且活性也高得多。光合抑制剂和外源碳水化合物分别减缓和促进受高温伤害的蓝藻固氮活性恢复。在光、暗和供给外源碳水化合物的条件下,厌氧(氩和氮中)对受高温伤害的蓝藻固氮活性恢复不利。与正常蓝藻有异的是,H_2,CO_2及H_2与O_2,CO_2与N_2的加合都阻碍受高温伤害的蓝藻固氮活性的恢复。     

The Three-Dimensional Human Skin Reconstruct Model: a Tool to Study Normal Skin and Melanoma Progression

Most in vitro studies in experimental skin biology have been done in 2-dimensional (2D) monocultures, while accumulating evidence suggests that cells behave differently when they are grown within a 3D extra-cellular matrix and also interact with other cells (1-5). Mouse models have been broadly utilized to study tissue morphogenesis in vivo. However mouse and human skin have significant differences in cellular architecture and physiology, which makes it difficult to extrapolate mouse studies to humans. Since melanocytes in mouse skin are mostly localized in hair follicles, they have distinct biological properties from those of humans, which locate primarily at the basal layer of the epidermis. The recent development of 3D human skin reconstruct models has enabled the field to investigate cell-matrix and cell-cell interactions between different cell types. The reconstructs consist of a "dermis" with fibroblasts embedded in a collagen I matrix, an "epidermis", which is comprised of stratified, differentiated keratinocytes and a functional basement membrane, which separates epidermis from dermis. Collagen provides scaffolding, nutrient delivery, and potential for cell-to-cell interaction. The 3D skin models incorporating melanocytic cells recapitulate natural features of melanocyte homeostasis and melanoma progression in human skin. As in vivo, melanocytes in reconstructed skin are localized at the basement membrane interspersed with basal layer keratinocytes. Melanoma cells exhibit the same characteristics reflecting the original tumor stage (RGP, VGP and metastatic melanoma cells) in vivo. Recently, dermal stem cells have been identified in the human dermis (6). These multi-potent stem cells can migrate to the epidermis and differentiate to melanocytes.     

Biodegradation of C.I. Acid Blue 92 by Nasturtium officinale: Study of Some Physiological Responses and Metabolic Fate of Dye

The present study was conducted to evaluate the potential of aquatic vascular plant, Nasturtium officinale, for degradation of C.I. Acid Blue 92 (AB92). The effect of operational parameters such as initial dye concentration, plant biomass, pH, and temperature on the efficiency of biological decolorization process was determined. The reusability of the plant in long term repetitive operations confirmed the biological degradation process. The by-products formed during biodegradation process were identified by GC-MS technique. The effects of the dye on several plant physiological responses such as photosynthetic pigments content and antioxidant enzymes activity were investigated. The content of chlorophyll and carotenoids was significantly reduced at 20 mg/L of the dye. The activities of superoxide dismutase and peroxidase were remarkably increased in the plant root verifying their importance in plant tolerance to the dye contamination.     

Study on the Contact Stress Concentration and the Hyperplasia of the Canine Trachea Granulation Tissue after Stenting

Tracheal stenosis is a common respiratory disease and is usually treated by stent implantation. However, the implanted stent often causes excessive hyperplasia of trachea granulation tissue, leading to the restenosis. Although surgical removal or chemical suppression can be used to alleviate the restenosis, the efficacy is limited. Thus, restenosis remains a thorny complication. We investigated this issue from the perspective of the “tress-growth”relationship. Firstly, the lower airway of 5 experimental dogs were CT-scanned to reconstruct the 3D numerical models; secondly, the implantations of the Nitinol alloy stents were numerically simulated; thirdly, 45 days after the stenting, the dogs were evaluated for the hyperplasia of the trachea granulation tissue by CT imaging, bronchoscopy and histological sectioning; finally, the correlation analysis was performed between the contact stress and the hyperplasic thickness of the granulation tissue. Results show that the hyperplasia of the trachea granulation tissue and the local contact stress are positively correlated (R=0.82) and the high local dilation stress can promote the hyperplasia of the trachea granulation tissue, probably through the recombination of basic fibroblast growth factor or the dysfunction of plasminogen activator inhibitor-1. Therefore, contact stress concentration should be prevented in the future design of the tracheal stent.