Influence of Low-Intensity Laser Radiation on the Rheological Characteristics of Human Blood

The influence of low-intensity laser radiation (LLR) on the rheological characteristics of human blood has been investigated. The results of the investigation of the blood velocity in the human skin capillaries, the erythrocyte aggregation time, and the spectral width of scattering intensity fluctuations depending on the irradiation time are presented. It has been shown that laser irradiation leads to a decrease in the degree of aggregation of erythrocytes and, accordingly, to an increase in the velocity of blood microcirculation, which can be used for laser therapy and diagnostics and treatment of cardiovascular diseases (CVD). To explain the results obtained, a method of the LLR–biotissue interaction is proposed.     

狭窄流道中Fahraeus效应研究进展

本文详细论述了毛细管和二维狭缝中流过血液时的Fahraeus效应研究历史及现状,给出了迄今为止得到的全部结论,并报道了笔者对狭缝缝隙中Fahraeus效应研究的最新进展。本文所涉及的内容对于微循环的理论与应用以至有关流变学仪器的设计优化都有重要意义。     

内皮调节对小动脉管腔运动影响的模型分析1）

微循环是血液和组织之间发生物质交换的主要场所,它可以通过改变管径实现对血压、血流量的局部调节.血管内皮层对小动脉运动有重要的调节作用.本文基于连续介质假设,建立了内皮调节过程中主要活性物质在管壁中的扩散--反应动力学模型,并分析了非线性黏弹性血管的径向运动特性.利用该模型首先得到了内皮舒张因子一氧化氮（NO）、平滑肌细胞内钙离子（Ca²⁺）以及磷酸化肌球蛋白（actin-myosin complexes,AMC）在管壁内的的径向浓度分布;为分析内皮调节的动态过程,进一步对小动脉的被动舒张、血流量发生扰动时的管径响应分别进行了模拟.研究结果显示：当没有活性物质参与调节小动脉被动舒张时,管径无振荡发生;当血流量变化引起内皮调节时,内皮舒张因子NO浓度和管径均出现衰减振荡,振荡周期约60 s.分析认为内皮调节对壁面剪切力的反馈控制,可能是NO浓度和管径产生周期性振荡的原因.内皮调节过程呈现的频谱特征可以为血管内皮功能障碍的诊断提供帮助.     

基于大鼠背部视窗显微观测的微血管网的三维重建

微循环是循环系统中最基层的结构和功能单位,它在保持人体正常生理功能中占有突出地位,许多疾病的发生也是从微循环开始. 因此,利用脊背视窗技术,并通过体视显微镜观察视窗内的血管结构, 进一步对所获血管图像进行一系列图像处理,得到了血管边界和中心线等结构信息. 同时,根据血管分叉处相贯线的信息确定分叉血管的连接方式. 在网格划分时,采用了改进的超限插值算法,构建了三维血管网的有限元网格模型,实现了对任意分支血管网的三维重建. 为微循环的体外实验和数值分析奠定基础.      

微血管自律运动的流体力学及血液粘弹性质的影响

本文研究了微血管自律运动引起的血液流动,着重分析了血液的粘弹性质对压力升高及壁面摩阻的影响.结果表明,微血管自律运动具有人体“第二心脏”的作用,血液粘弹性质的影响与Weissenberg数及平均流量的大小有关.     

Subsurface Microscopical visualization of brain tissue in vivo: Present, problems and prospects

The location of the brain within the cranium has prevented in vivo studies with microscopical resolution for a long time. Cranial window techniques provide microscopical access to the brain surface, but subsurface structures cannot be visualized with conventional microscopy. Confocal microscopy with its increased depth of penetration and optical sectioning capabilities is ideally suited for the investigation of thick biological specimens. Due to the scanning process, however, temporal resolution is limited, a significant disadvantage in the in vivo setting. In this article we demonstrate that confocal laser scanning microscopy can be utilized to study brain cortex microvascular morphology, capillary hemodynamics, leukocyte behaviour and intracellular ion concentrations in anesthetized rats through a closed cranial window. Three different confocal microscopes are compared: a Biorad MRC-600 with multiline Kr/Ar-Laser (488/568/647 nm), a Noran Odyssey acousto-optic scanning microscope with multiline Ar-Laser (458/488/514/529 nm) and a Biorad Viewscan DVC-250 slit scanning microscope with Ar-Laser (488/514 nm). With all microscopes a Zeiss × 40 water immersion objective, n.a. 0.75 is used. A Laser-Doppler flowmeter continuously measures regional cerebral blood flow in the area of microscopical investigation. As fluorescent dyes we used: fluorescein sodium as blood plasma marker (given I.V.); rhodamine 6G to label leukocytes (given I.V.); and the AM-esters of BCECF (pH-sensitive), Fluo-3 and Calcium-Green (both calcium-sensitive) as intracellular ion-concentration markers (loaded via superfusion over the cranial window). With this setup, we are able to study the flow dynamics in the capillary network of the cortex (erythrocyte flow velocities and flux rates), the behaviour of leukocytes in capillaries and postcapillary veins (plugging of capillaries, adhesion to the endothelium, extravasation into the parenchyma), and intracellular changes of [H⁺] and [Ca²⁺] under physiological and pathophysiological conditions (cerebral ischemia and meningitis). The comparison between the conventional CLSM (Biorad 600) and the real time CLSMs revealed that the increase in temporal resolution afforded by the real time instruments is offset by a reduction in spatial resolution and, most importantly, in the signal to noise ratio, resulting in a lower depth of penetration into the tissue and necessitating frame averaging.     

THE DOUBLE POROSITY MODEL FOR MASS TRANSFER BETWEEN CAPILLARIES AND TISSUES IN LUNG MICROCIRCULATION

This paper proposes a double porosity model to deal with the mass transfer between capillaries and tissues in the lung microcirculation on the basis of Ref. [4]. Utilizing the analytic method of small parameter expansion and the numerical method, the nonlinear governing equations are solved. Comparison shows that the small parameter solution is accurate enough to illustrate the mass exchange between the lung capillary and tissues. Finally the results are used to discuss the mechanism of formation of lung edema.     

微循环表面网状形态对其润滑特性影响的研究

为研究微循环表面网状形态对其润滑特性影响,采用飞秒激光和数控加工方法,构建出不同滑动表面网格织构,并以此研究了其形态对润滑特性的影响.研究采用网格形态的参数化设计,并以无量纲长度Λ,无量纲宽度г和夹角α表征其结构特征,采用数值迭代求解和摩擦学试验相结合的方法,研究了不同形态的网格参数对其润滑的影响.研究结果表明:具有微循环网格形态的滑动表面可有效地改善其摩擦系数,当A大于0.45时会使得摩擦系数达到最佳优化值,而当Λ小于0.45时,则网格参数与摩擦系数的关系将变得较为复杂;较大的无量纲深度参数г和较小的夹角也可优化出改善润滑的最优组合;该研究可为滑动表面微循环网状织构优化设计提供了理论基础.     

正交偏振光谱微循环成像方法及装置

鉴于微循环图像成像质量的提高是微循环检测仪器实用化的关键，提出一种新的微循环检测方法及装置。利用基于该原理的正交偏振光谱成像仪器进行了实验，得到对比度清晰的甲襞微循环图像。用线性偏振光聚焦照射被测生物组织时，从组织表面反射回来的光保持了其偏振态，被放置在CCD前的偏振方向垂直的检偏器屏蔽掉；从组织内部返回的光发生复散射后退偏，通过检偏器成像。选择光源波长，使其落在红血球的吸收谱范围内，即可得到清晰的生物活体浅表面微循环图像。     

恶性肿瘤研究新进展——生理屏障的发现

近年来发明的生物疗法,如单克隆抗体(Mabs),增长因子(GFs)等,由于它们在体外对癌细胞有效的杀伤能力而被称为“突破性药物”,“神奇炮弹”.但当这些药物用于病人体内时则疗效较差.从事肿瘤结构研究达15年之久的Jain博士最近指出,药物在体内疗效不好的原因是肿瘤内部产生了三个生理屏障:①非均匀的血液供给;②组织间隙中的高压;③组织间隙中的大传质距离.这些屏障使药物很难到达肿瘤内核区.尤其是对于从人体免疫系统提取的象单克隆抗体这类药物更严重,因为免疫系统的细胞和分子比一般药物分子大得多.因此,要使治癌药物在体内完成预期医疗效果,必须发展克服生理屏障的方法. 本文对生理屏障进行了全面描述,希望引起我国癌症研究者的注意和生物力学工作者的兴趣.