纺织基人造血管几何特征表征的实验研究

人造血管的壁厚和松弛内径是其主要的几何特征参数。本文中首先依据国际标准ISO 7198的要求设计了测试人造血管松弛内径的测试定规,并对人造血管样品进行了测试。然后对人造血管壁厚的测试方法进行了初步探讨。     

人造血管轴向拉伸性能测试装置的实验研究

介绍了一种新的人造血管纵向拉伸强度的测试方法,通过分析新旧两种方法的原理,论证了新方法更具合理性。     

《上海生物医学工程》二○○五年总目次

研究论著肺结节检测算法研究王德杭汪家旺于立燕等(3)………………………………………………1600例重症心脏瓣膜置换术中的体外循环管理殷凤珍李欣徐新根等(8)…………………超声检测胎儿先天性心脏病存在问题分析陈萍常才刘启瑞等(10)………………………一种显微图像的拼接方法张旭峰严壮志刘书朋等(13)…………………………………………时间减影在静脉肾盂造影中的应用价值研究丁海岭汪军吴国胜等(17)……………………经编人造血管顺应性的实验研究邹菲王璐(20)…………………………………………………便携式脑循环功能分析仪的研究陆瑾龚…     

一种带有旋动流引导器的新型小口径人造血管流场的数值模拟

大尺寸人造血管的临床应用已取得很大成功,但用于冠状动脉等旁路搭桥的小口径人造血管的急性血栓堵塞问题,至今仍未解决．因此,本文设计了一种可装于小口径人造血管前的旋流导引器,以期使进入人造血管内的血流产生旋动．对带有旋流导引器的人造血管内的血流流场进行了计算机数值模拟分析,并与常规人造血管内的血流流场进行了比较．数值模拟分析揭示,这种旋流导引器的确能使人造血管内的血流产生旋动,从而改变人造血管内的血流流场和流速分布,使近壁面血液的流速和壁面剪切应力得到极大提高．本研究认为,血液在人造血管壁面的流速和壁面剪切应力的提高,可抑制小口径人造血管内急性血栓的形成,从而达到提高小口径人造血管的通畅率的目的．     

两种机织型人造血管管壁的均匀特性研究

针对一些纺织型人造血管管壁的临床选择性破损特征,本文报告两种机织型人造血管管壁的均匀特性研究。通过对其整体、纱线、纤维三个层次的纺织结构性能以及相应的生物力学性能的研究,揭示此类人造血管不同的管壁纺织结构对其生物力学性能整体均匀性的影响,并由此从纺织结构的角度预测该类人造血管在临床应用中可能导致提前降解或破损的原因。研究结果提示在新型人造血管的设计中,要避免此类纺织结构的弱节与不均匀性。     

人造血管内皮化旋转培养装置的设计及制作

人造血管内皮化研究需在人造血管内壁均匀粘附上一层内皮细胞。以往静态培养,细胞难以在其内壁均匀粘附生长,效果不理想。我们设计了一种内皮化人造血管旋转培养装置,很好地解决了上述问题。该装置体积小,整体可以放入二氧化碳培养箱,因而可维持细胞的生长环境不受影响。装置由三个部分组成:①旋转驱动器(蠕动泵)。②人造血管内皮细胞     

人造血管移植物自然内皮化的研究

人造血管移植作为自体血管代用品已被广泛使用了解内皮细胞的功能,来源,血管内皮化的过程,形成机理及影响内皮化的因素,对防治血栓形成,内膜增生,维持移植血管通畅率有重要意义。     

新型人造血管研制成功

近日,南京鼓楼医院研制成功血管腔内支架人造血管。这种新型人造血管采用钛镍记忆合金网状支架,内衬高分子硅胶类薄膜制成,通过输送导管导人移植于人体血管病变部位,能够有效地治疗动脉瘤、动静脉瘘、动脉闭塞、静脉闭塞以及大血管损伤等血管疾病。新型人造血管研制成功     

多聚环氧化合物预处理异体移植静脉顺应性实验研究

目的研究多聚环氧化合物(polyepoxy compound,PC)预处理的人离体大隐静脉的顺应性。方法PC与戊二醛(Glutaradehyde,GA)分别对人的离体大隐静脉预处理,并记录三种静脉随内压变化的投影几何参数(面积、周长、长轴和短轴),通过对三种静脉的投影几何参数在不同内压下的变化进行研究,比较两种方法处理的血管顺应性的差异,新鲜静脉(Fresh)作为对照。结果三种静脉在相同内压变化时的投影几何参数变化,各组之间的差异无统计学意义(P>0.05)。结论PC不影响血管的顺应性。     

基于日均温度的华山松径向生长敏感温度研究

树干木质部形成周期与温度密切相关,存在影响形成层活动的敏感温度,但是尚未研究尝试从树木年轮中探索影响径向生长的敏感温度。华山主峰的华山松径向生长对气候变化较敏感,且华山西峰的气象站记录了1953年以来气象资料,这为探索树木径向生长与温度的关系提供了宝贵的材料。以华山主峰的华山松年轮资料和日值温度资料为基础,通过分析历年日平均温度的变化过程和年轮宽度、早材宽度、晚材宽度、最小密度以及最大密度的相关性,尝试探索华山松径向生长与日均温度变化的关系。结果表明春季一定温度的初日时间对华山松径向生长有较大的影响,其中3 ℃和8 ℃初日时间和持续时间对年轮宽度的促进作用最明显,而3 ℃对早材宽度影响较大,8℃初日时间对晚材的影响较大;高于11 ℃的温度会对华山松的径向生长造成限制,其中以11 ℃的作用最明显;而温度的终日时间对年轮特征影响较小。说明3 ℃是早材形成的敏感温度,8 ℃是晚材形成的敏感温度,温度高于11 ℃会对华山松的径向生长构成胁迫。这证明华山松年轮特征中包含了较多的气候信息,形成层活动和木质部的生长存在阈值温度,通过分析不同温度的生长期与年轮特征的关系可以找到影响华山松径向生长的敏感温度。这些敏感的温度是通过什么生理过程影响木质部的形成尚无法得知,但是这为解释树木生长对全球温度升高的响应以及利用华山松年轮重建历史气候提供了重要依据。     

Measurement in vitro of pulsatile arterial diameter using a helium-neon laser

A noncontacting in vitro measurement of pulsatile arterial diameter using a scanning optical micrometer is described. The major component of this system is a He-Ne laser whose beam scans the pulsating artery to be measured. The laser micrometer was integrated into a pulsatile perfusion apparatus that imposed various hemodynamic conditions on excised canine vessels. The laser system reliably tracked the pulsating arterial diameter at a particular longitudinal site as well as at various increments in the presence of an experimentally created stenosis. The He-Ne laser measured the radial motion of canine arteries and various vascular substitutes anastomosed in an end-to-end fashion. From these novel measurements, calculations were made of arterial compliance and bending stress, two biomechanical parameters that are implicated as potential causes of anastomotic intimal hyperplasia and graft failure. Although this device is inherently limited to in vitro use, it is a potentially useful instrument for vascular physiology and biophysics.     

Microvascular pressures measured by micropuncture in isolated perfused lamb lungs

To investigate the influence of vasomotor tone and vessel compliance on pulmonary segmental vascular resistance, we determined the longitudinal distribution of vascular pressures in 15 isolated blood perfused lungs of newborn lambs. We measured pulmonary arterial and left atrial pressures and by micropuncture the pressures in 20- to 80-micron-diam subpleural arterioles and venules, both before and after paralyzing the vasculature with papaverine hydrochloride. In five lungs we also determined the microvascular pressure profile during reverse perfusion. In lungs with baseline vasomotor tone, approximately 32% of the total pressure drop was in arteries, approximately 32% in microvessels, and approximately 36% in veins. With elimination of vasomotor tone, arterial and venous resistances decreased to one-fifth and one-half of base-line values, respectively, indicating that vasomotor tone contributed mainly toward arterial resistance. During reverse perfusion, the pressure drop in veins was similar to that in arteries during forward perfusion, suggesting that the compliance of arteries and veins is comparable. We conclude that vascular tone and compliance are important factors that determine the distribution of segmental vascular resistance in lungs of the newborn.     

仿生技术构建小口径人造血管

目的：研究以改性猪小肠粘膜下层组织(SIS)为支架,利用仿生技术构建小口径人造血管的可行性。方法：自犬隐动脉分离出血管内皮细胞和平滑肌细胞,与胶原蛋白凝胶均匀混合,分别种植于改性SIS膜表面,制成3 mm 仿生三层人造血管为实验组;制成单层人造血管为对照组,分别植入修复15例犬双侧股动脉缺损,术后进行彩超、组织学检测和电镜检测鉴定。结果：植入12周,14个仿生人造血管保持通畅,通畅率93.3%,有血管样生物结构形成,管腔内壁有完整的内皮覆盖,管壁中层见大量平滑肌细胞;对照组通畅率60%,有少许内皮细胞覆盖。结论：仿生小口径人造血管具有良好的血液相容性,并能在体内保持良好通畅性, 修复动脉缺损效果满意。     

Localization of the sites of pulmonary vasomotion by use of arterial and venous occlusion

In this study, we present a new approach for using the pressure vs. time data obtained after various vascular occlusion maneuvers in pump-perfused lungs to gain insight into the longitudinal distribution of vascular resistance with respect to vascular compliance. Occlusion data were obtained from isolated dog lung lobes under normal control conditions, during hypoxia, and during histamine or serotonin infusion. The data used in the analysis include the slope of the arterial pressure curve and the zero time intercept of the extrapolated venous pressure curve after venous occlusion, the equilibrium pressure after simultaneous occlusion of both the arterial inflow and venous outflow, and the area bounded by equilibrium pressure and the arterial pressure curve after arterial occlusion. We analyzed these data by use of a compartmental model in which the vascular bed is represented by three parallel compliances separated by two series resistances, and each of the three compliances and the two resistances can be identified. To interpret the model parameters, we view the large arteries and veins as mainly compliance vessels and the small arteries and veins as mainly resistance vessels. The capillary bed is viewed as having a high compliance, and any capillary resistance is included in the two series resistances. With this view in mind, the results are consistent with the major response to serotonin infusion being constriction of large and small arteries (a decrease in arterial compliance and an increase in arterial resistance), the major response to histamine infusion being constriction of small and large veins (an increase in venous resistance and a decrease in venous compliance), and the major response to hypoxia being constriction of the small arteries (an increase in arterial resistance). The results suggest that this approach may have utility for evaluation of the sites of action of pulmonary vasomotor stimuli.     

Vascular prostheses with controlled release of antibiotics Part 2. In vitro biological evaluation of vascular prostheses treated by cyclodextrins

Viability tests by the colony forming method show no toxicity for all CDs (beta-CD, gamma-CD, HPbeta-CD and HPgamma-CD) and their associated polymer. A survival rate of 100% is observed for all CDs at high concentration 400 ppm. Proliferation tests revealed a low proliferation of L132 cells on grafted vascular prostheses and untreated prostheses and good proliferation on Melinex (film form of PET). A proliferation of 17% is observed after 3 days of incubation and decrease at 4% after 6 days on prostheses. Melinex exhibits a proliferation rate as the controls. Vitality tests confirm proliferation tests and show a good vitality of cells even for low cell amounts. From these experiments it becomes obvious that the decreasing proliferation rate is not a cytotoxic effect but is due to the chemical and/or physical surface characteristics. A similar result is obtained for cell adhesion kinetics between grafted vascular prostheses and control. After 2 h adhesion, a lower adhesion is observed on untreated prostheses. Theses results were confirmed by immunochemistry and morphology tests. This cell adhesion inhibiting effect of the PET prostheses contributes to a better "survival" of vascular prostheses without secondary obstruction or stenosis.     

Peripheral vascular decoupling in porcine endotoxic shock

Cardiac output measurement from arterial pressure waveforms presumes a defined relationship between the arterial pulse pressure (PP), vascular compliance (C), and resistance (R). Cardiac output estimates degrade if these assumptions are incorrect. We hypothesized that sepsis would differentially alter central and peripheral vasomotor tone, decoupling the usual pressure wave propagation from central to peripheral sites. We assessed arterial input impedance (Z), C, and R from central and peripheral arterial pressures, and aortic blood flow in an anesthetized porcine model (n = 19) of fluid resuscitated endotoxic shock induced by endotoxin infusion (7 μg·kg?1·h?1 increased to 14 and 20 μg·kg?1·h?1 every 10 min and stopped when mean arterial pressure <40 mmHg or Sv(O?) < 45%). Aortic, femoral, and radial artery pressures and aortic and radial artery flows were measured. Z was calculated by FFT of flow and pressure data. R and C were derived using a two-element Windkessel model. Arterial PP increased from aortic to femoral and radial sites. During stable endotoxemia with fluid resuscitation, aortic and radial blood flows returned to or exceeded baseline while mean arterial pressure remained similarly decreased at all three sites. However, aortic PP exceeded both femoral and radial arterial PP. Although Z, R, and C derived from aortic and radial pressure and aortic flow were similar during baseline, Z increases and C decreases when derived from aortic pressure whereas Z decreases and C increases when derived from radial pressure, while R decreased similarly with both pressure signals. This central-to-peripheral vascular tone decoupling, as quantified by the difference in calculated Z and C from aortic and radial artery pressure, may explain the decreasing precision of peripheral arterial pressure profile algorithms in assessing cardiac output in septic shock patients and suggests that different algorithms taking this vascular decoupling into account may be necessary to improve their precision in this patient population.     

Differentiation of vascular pseudointima under normal and disturbed blood flow conditions: Ultrastructural observations in the rat

Summary To study the effect of haemodynamic stress on the morphological differentiation of pseudointima, the ultrastructure of the cells lining normally shaped and aneurysmal polyurethane vascular prostheses implanted into the abdominal aorta of rats was examined. In the normally shaped vascular prostheses the pseudointima was composed of several layers of smooth muscle cells, which varied in differentiation from normal smooth muscle cells to myofibroblasts, and which were lined by a continuous sheet of endothelial cells. In the aneurysmal vascular prostheses, a pseudointima, composed of only layers of smooth muscle cells had developed. Those smooth muscle cells which lined the lumen had a typical morphology: they were polygonal, flat cells of unequal size, with a distinct organelle-free zone, containing myofilaments, at the luminal peripheral cytoplasmic side. The other smooth muscle cells varied in differentiation from normal smooth muscle cells to myofibroblasts. Under severe haemodynamic stresses, such as occur in the aneurysmal vascular prostheses, the regeneration of endothelial cells is impaired and smooth muscle cells undergo morphological changes to form a pseudoendothelial lining.