大鼠气管的零应力状态

大鼠气管存在残余应力,将无载荷状态的气管环径向剪开,气管环展开成扇形体,即得到气管的零应力状态。文章结果表明,对于大鼠无载荷状态气管环,软骨剪开与肌肉剪开所展成的张开角是不同的,软骨剪开对应的张开角明显大于肌肉剪开的张开角。而且肌肉剪开的张开角沿气管轴向变化不明显,而软骨剪开的张开角随着ｘ／Ｌ的增大而呈明显上升趋势。本文结果对分析气管在特定力学环境中的适应性生长是有帮助的。     

大鼠气管的周向残余应变及其非均匀分布

本文对大鼠气管的无载荷状态和零应力状态进行分析，发现肌肉剪开无载荷气管环所对应张开角较小，而且基本上不随气管轴向位置变化；与此不同，软骨剪开无载荷气管环所对应张开角较大，而且随气管轴向距离的增大有明显的上升趋势。结果表明，无载荷气管存在残余应变，内壁为压缩应变，外壁为拉伸应变，残余应变与气管张开角之间呈正相关的定量关系。本文所得结果对深入认识气管零应力状态，研究气管为适应所处力学环境产生的气管重建是十分必要的。     

肝内型门脉高压症形成中大鼠门静脉零应力状态的变化

用CCl4注射法制备大鼠肝内型门脉高压模型，通过观察门静脉张开角的大小，研究肝内型门脉高压大鼠在模型建立过程中不同时间点门静脉零应力状态的变化。结果发现，在门脉高压症形成中．大鼠门静脉张开角逐渐增大，从CCl4注射第10周起与对照组相比有显著性差异（P〈0．05）。表明在门脉高压形成过程中，门静脉存在非均匀性生长，门脉高压大鼠门静脉的残余应力和应变大于正常大鼠。     

狗主动脉的零应力状态

动脉中存在残余应变。先将血管沿轴线剪为短圆环，再将短圆环沿径向剪开，即可获得血管的零应力状态。血管的零应力状态常用张开角描述。本文研究了狗主动脉零应力状态张开角随位置的变化。结果显示，在主动脉升部，张开角为１２０°；到主动脉弓部，张开角降为９０°；在胸主动脉下部，张开角回升到１００°；在腹主动脉上，张开角又降为８０°。本文还将狗与猪、鼠主动脉零应力状态张开角的数据进行了比较，讨论了种属间的差异。     

人体四肢血管零应力状态的实验研究

血管在不受血压作用时，存在残余应力和残余应变。血管的零应力状态指它既不受外载，又没有内部残余应力的状态。先将血管切为短圆环，再将短圆环沿其径向剪开，即可释放其中的残余应力。剪开后的血管环迅速展开成“Ｃ”形，并逐渐趋于一个稳定状态，即零应力状态。零应力状态用其张开角来描述。本文研究了人体四肢主要动脉和静脉的零应力状态。结果表明，股动脉的零应力状态张开角在１１０°左右；而肱动脉、桡动脉、动脉和胫前动脉的零应力状态张开角在１３０°～１６０°之间；锁骨下动脉、髂动脉和胫后动脉的零应力状态张开角在８０°～１１０°之间。下肢静脉的零应力状态张开角明显比相应动脉分支的小。股静脉、静脉和胫后静脉的零应力状态张开角约在４０°～９０°之间；大隐静脉的零应力状态张开角较大，约是１５０°。     

狗主动脉弓无载荷状态与零应力状态的实验研究

目的 通过测量计算狗主动脉弓无载荷状态和零应力状态的几何参数,研究狗主动脉弓无载荷状态和零应力状态的几何形态和残余应变分布.方法 实验解剖取出3只狗的胸主动脉弓试样,结合计算机图像测量技术,用统计学方法得到狗主动脉弓的几何形态,用弧长分析法研究狗主动脉弓残余应变.结果 拟合得到无载荷状态和零应力状态下的主动脉内、外边界,获取了血管的弧长、厚度、张开角等信息,得到主动脉弓几何特征和残余应变的分布规律.结论 主动脉弓部血管是内外边界为椭圆状的均匀厚壁筒;主动脉张开角不沿主动脉环向坐标变化,动脉壁内的残余应变是均匀的.     

主动脉弓几何参数及残余应变分布变化的实验研究

提出了分析无载荷状态下动脉壁残余应变的弧长分析法.通过动物实验,图像测量白兔主动脉弓无载荷状态下动脉环长短半轴、平均壁厚和零应力状态下动脉弧内外边界弧长、平均壁厚等几何参数,并在此基础上,计算无载荷状态下主动脉弓周向残余应变的分布.结果表明:主动脉弓弯管段动脉壁无载荷状态几何形状近似为椭圆,而直管段近似为圆;不论在零应力状态还是在无载荷状态,动脉壁厚度均在弯管处变化较大,而直管段变化较小,同时,沿圆周方向厚度均匀;张开角沿主动脉弓的轴向分布与残余应变的轴向分布一致,在弯管段变化较大,而直管段变化较小;不论弯管段还是直管段,张开角和残余应变沿环向没有变化.     

大鼠肝内型门脉高压症形成中门静脉力学性质的变化

目的观察大鼠肝内型门脉高压症形成中门静脉零应力状态及轴向拉伸时张应力．伸长比关系的动态变化，探讨门静脉生物力学特性的变化在门脉高压症形成中的作用。方法以60％四氯化碳(CCl4)皮下注射法制备肝内型门脉高压症大鼠模型，采用生物力学技术测定CCl4注射第2、4、6、8、10周大鼠门静脉零应力状态张开角和轴向拉伸时张应力，伸长比关系，并同步监测大鼠门静脉压力(PVP)、门静脉流量(PVF)、平均动脉压(MAP)、门静脉阻力(PVR)和内脏血管阻力(SVR)等血液动力学指标的动态变化。结果随着CCl4注射时间的延长，实验组大鼠的血液动力学指标发生了显著的变化。与之相对应．大鼠门静脉张开角及轴向拉伸参数b亦逐渐增大，从注射第10周起与对照组相比具有统计学差异(P＜0．05)。结论门脉高压症大鼠存在高动力循环状态(HCS)。HCS可引起门静脉血管生物力学特性的变化。     

高血压大鼠动脉的零应力状态与内皮素的关系

本文通过观察胸主动脉、肾动脉主干张开角的大小,研究了SHR高血压建立前后胸主动脉和肾动脉零应力状态的变化,并于SHR高血压形成前,给予口服型ETA型受体拮抗剂BMS-182874,研究了内源性ET在SHR主动脉和肾动脉零应力状态变化中的作用.结果发现,在未建立高血压的SHR(4周),主动脉和肾动脉主干的张开角与同龄WKY相比,都没有显著的变化.在高血压已建立的SHR(16周),主动脉和肾动脉主干的张开角分别为69.0±27.0°和114.2±42.2°,显著大于同龄的WKY大鼠(45.9±25.7°和70.2±30.4°).给予SHRBMS-182874(4～16周),SHR主动脉张开角未发生明显变化(62.8±25.6°),而肾动脉主干的张开角显著减小(66.6±41.54°).结果表明,在已建立高血压的SHR,主动脉和肾动脉主干都存在非均匀生长,其残余应力、应变大于同龄的WKY,内源性ET在SHR肾动脉零应力状态的改变中起重要作用.     

自发性高血压大鼠胸主动脉的残余应变及酶抑制剂——依那普利的影响

为观察SHR胸主动脉残余应变及依那普利的影响,测量了SHR胸主动脉血管的零应力状态张开角θ、等效内径D、平均壁厚H,并计算血管的平均截面积S。结果表明与对照1组相比较:对照2组(加喂依那普利)各项指标均无明显差异;SHR 1组的θ与D值显著性减小(P均<0.01)、H与S值显著性增大(P均<0.01);SHR 2组(加喂依那普利)θ与H值增大(P_θ<0.01,P_H<0.05)、D值减小(P<0.05)、S值差异不明显。表明病变血管残余应变的变化过程为先增大至峰值,然后又逐渐减小;依那普利可延缓这种变化的进程。血管壁中应力的分布与大小的变化是引起血管组织重塑与生长的重要原因之一。     

A Mechanical Analysis of Conduit Arteries Accounting for Longitudinal Residual Strains

Identification of an appropriate stress-free reference configuration is critically important in providing a reasonable prediction of the intramural stress distribution when performing biomechanical analyses on arteries. The stress-free state is commonly approximated as a radially cut ring that typically opens into a nearly circular sector, relieving much of the circumferential residual strains that exist in the traction-free configuration. An opening angle is often used to characterize this sector. In this study, we first present experimental results showing significant residual deformations in the longitudinal direction of two commonly studied arteries in the pig: the common carotid artery and the left anterior descending coronary artery. We concluded that a radially cut ring cannot completely describe the stress-free state of the arteries. Instead, we propose the use of a longitudinal opening angle, in conjunction with the traditional circumferential opening angle, to experimentally quantify the stress-free state of an artery. Secondly, we propose a new kinematic model to account for the addition of longitudinal residual strains through employing the longitudinal opening angle and performed a stress analysis. We found that with the inclusion of longitudinal residual strains in the stress analysis, the predicted circumferential stress gradient was decreased by 3-fold and the predicted longitudinal stress gradient was increased by 5.7-fold. Thus, inclusion of longitudinal residual strains has a significant effect on the predicted stress distribution in arteries.     

鼾症动物模型的建立及其气管力学重建的实验研究

目的　建立阻塞性睡眠呼吸暂停低通气综合征(OSAHS)动物模型，研究咽腔力学环境改变对气管力学特性的影响。方法　利用低压舱饲养小型猪获得OSAHS 动物模型，测量其气管无载荷、零应力状态的几何尺寸及不同轴向伸长比下的压力(p)-容积(V)关系。进一步计算得到气管的零压顺应性，并与正常对照组比较。结果　模型猪出现了明显的类OSAHS表现。与正常对照组相比，模型猪气管无载荷、零应力状态几何尺寸增大，不同伸长比下的零压顺应性增大；模型猪气管黏膜组织的超微结构发生了明显改变。结论　提出的建立OSAHS动物模型的方法具有可行性，模型猪气管的形态与结构及力学特性均发生了重建。     

模拟正常动脉壁残余应变和应力的数值研究

目的 探讨残余应变对动脉壁周向应力-应变分布的影响.方法 构造残余应变数值施加方法,对在不同生理血压下的动脉壁应力-应变进行数值模拟,并且模拟了残余应变使动脉圆环张开的情形.结果 动脉壁的周向应力水平明显降低;周向应变沿壁厚的分布趋于均匀;动脉圆环的张开角α大致为7°.结论 残余应变降低了载荷状态下的应力水平;残余应变直接改变了载荷状态下动脉壁沿径向的周向应变分布;残余应变的存在会使无载荷状态的动脉圆环发生张开;血管壁优化状态体现了均匀应变优化标准.     

What are the residual stresses doing in our blood vessels?

We show that the residual strain and stress in the blood vessels are not zero, and that the zero-stress state of a blood vessel consists of open-sector segments whose opening angles vary along the longitudinal axis of the vessel. When the homeostatic state of the blood vessel is changed, e.g., by a sudden hypertession, the opening angle will change. The time constant of the opening angle change is a few hours (e.g., in the pulmonary artery) or a few days (e.g., in the aorta). From a kinematic point of view, a change of opening angle is a bending of the blood vessel wall, which is caused by a nonuniformly distributed residual strain. From a mechanics point of view, changes of blood pressure and residual strain cause change of stress in the blood vessel wall. Correlating the stress with the change of residual strain yields a fundamental biological law relating the rate of growth or resorption of tissue with the stress in the tissue. Thus, residual stresses are related to the remodeling of the blood vessel wall. Our blood vessel remodels itself when stress changes. The stress-growth law provides a biomechanical foundation for tissue engineering. Presented at the 1989 Annual Meeting of the Biomedical Engineering Society, “ALZA and Christie Distinguished Lectures,” Monday, March 20, 1989, New Orleans, Louisiana.     

自发性高血压大鼠肾动脉的零应力状态

通过观察动脉主干张开角的大小,研究了自发性高血压大鼠（Ｓｐｏｎｔａｎｅｏｕｓｌｙ ｈｙｐｅｒｔｅｎｓｉｖｅ,ｒａｔ,ＳＨＲ）高血压建立后肾动脉零应力状态的变化,并于ＳＨＲ高血压形成前,分别给予口服型ＡｎｇⅡ Ⅰ型受体拮抗剂Ｌｏｓａｒｔａｎ和ＥＴ Ａ型受体拮抗剂ＢＭＳ－１８２８７４,研究内源性ＡｎｇⅡ和ＥＴ在ＳＨＲ肾动脉零应力状态变化中的作用。 现,在高血压已建立的ＳＨＲ,肾动脉主干张开角（１１４．     

A comparative study of mammalian tracheal mucous glands

We have compared the distribution, numbers and volume of mucous glands in the tracheas of 11 mammalian species. No glands were present in the rabbit. The mouse only contained glands at the border between the trachea and larynx. In the rat, glands were commonest in the cephalad third of the trachea, but on average were much scarcer than in the larger species. Between species, there was a significant correlation between airway diameter and gland volume per unit surface area, suggesting that the rate of deposition of inhaled particles may increase in large airways. In the ventral portion of the trachea of about half the species, the glands were concentrated between the cartilaginous rings; in others they were evenly distributed over and between the rings. In most species in which the trachealis muscle attached to the internal surface of the cartilaginous rings, the glands were external to the muscle. In all species in which the muscle attached to the external surface of the cartilaginous rings, the glands were internal to the muscle. In the ox, goat, dog and sheep, the volume of glands per unit tracheal surface area was markedly greater in the ventral than the dorsal aspect of the trachea. The reverse was true of the pig. In humans, gland density in the 2 regions was similar. The frequency of gland openings was determined in the ox, goat, pig, dog and sheep tracheas, and ranged from 0.3 per mm² in the dorsal portion of the sheep trachea to 1.5 per mm² in the ventral portion of the ox trachea. For these 5 species, the volume of gland acini per unit luminal surface area varied linearly with the numbers of gland openings, with the volume of individual glands being constant at ∼ 120 nl.     

Unusual Combination of Tracheobronchopathia Osteochondroplastica and AA Amyloidosis

Tracheobronchopathia osteochondroplastica (TO) is a rare disorder of unknown cause characterized by the presence of multiple submucosal osseous and/or cartilaginous nodules that protrude into the lumen of the trachea and large bronchi. A simultaneous diagnosis of TO and amyloidosis is rarely reported. In this report, a case initially suspected to be asthma bronchiole that could not be treated, was radiologically diagnosed as TO, and also secondary amyloidosis is presented. A 53 years, man patient reported a 3 years history of dyspnea. Pulmonary function tests (PFTs) showed an obstructive pattern. Chest X-rays revealed right middle lobe atelectasis. FOB and CT detected nodular lesions in the trachea and in the anterior and lateral walls of the main bronchi. AA amyloidosis was confirmed by endobronchial biopsy. In the abdominal fat pad biopsy, amyloidosis was not detected. Asthma bronchiole was excluded by PFTs. This case illustrates that it is possible for TO and amyloidosis to masquerade as asthma. TO and amyloidosis should be suspected in patients of older ages with asthma and especially with poorly treated asthmatic patients. Although nodular lesions in the anterior and lateral tracheobronchial walls are typical for TO, a biopsy should be obtained to exclude amyloidosis.