血管支架在真实狭窄血管模型中扩张过程的模拟研究

目的 研究血管支架在真实狭窄血管模型中不同扩张阶段的形变与受力特性,为支架的介入治疗与设计提供科学的参考意见。方法 利用三维建模方法构建患者颈动脉血管模型以及斑块模型,利用Pro/E软件构建1种I型血管支架;在ABAQUS/Standard软件中分析支架在真实狭窄血管模型中径向扩张（第1阶段）和径向收缩（第2阶段）的扩张过程,同时建立斑块与血管为一体的对比实验。结果 在第1阶段,支架发生径向扩张,支架与斑块和血管内壁接触面积最大,支架、斑块、血管壁所受应力最大值分别为515.000、2.482、1.053 MPa;在第2阶段,支架发生径向收缩,形成“狗骨效应”,支架与血管壁之间形成较多的间隙,支架、斑块、血管壁所受应力最大值分别为464.500、0.954、0.316 MPa。在对比实验中,狭窄血管与支架在第2阶段所受应力最大值分别为0.9、414.1 MPa。结论 相对于对比实验,区分血管组织成分的模型更符合狭窄血管的真实情况,更能真实反映血管与支架的受力情况;在第1阶段支架对于斑块及血管内壁造成的损伤最大,在第2阶段支架的“狗骨效应”是造成支架与斑块、血管间产生空隙的重要影响因素。研究结果对支架在介入治疗中的选择与支架的改进设计具有指导意义。     

血管支架在真实狭窄血管模型中扩张过程的模拟研究

目的研究血管支架在真实狭窄血管模型中不同扩张阶段的形变与受力特性,为支架的介入治疗与设计提供科学的参考意见。方法利用三维建模方法构建患者颈动脉血管模型以及斑块模型,利用Pro/E软件构建1种I型血管支架;在ABAQUS/Standard软件中分析支架在真实狭窄血管模型中径向扩张(第1阶段)和径向收缩(第2阶段)的扩张过程,同时建立斑块与血管为一体的对比实验。结果在第1阶段,支架发生径向扩张,支架与斑块和血管内壁接触面积最大,支架、斑块、血管壁所受应力最大值分别为515.000、2.482、1.053 MPa;在第2阶段,支架发生径向收缩,形成"狗骨效应",支架与血管壁之间形成较多的间隙,支架、斑块、血管壁所受应力最大值分别为464.500、0.954、0.316 MPa。在对比实验中,狭窄血管与支架在第2阶段所受应力最大值分别为0.9、414.1 MPa。结论相对于对比实验,区分血管组织成分的模型更符合狭窄血管的真实情况,更能真实反映血管与支架的受力情况;在第1阶段支架对于斑块及血管内壁造成的损伤最大,在第2阶段支架的"狗骨效应"是造成支架与斑块、血管间产生空隙的重要影响因素。研究结果对支架在介入治疗中的选择与支架的改进设计具有指导意义。     

不同材质斑块的狭窄颈动脉模型中新型锌合金支架的支撑性能研究

目的研究在不同斑块类型的理想化狭窄颈动脉模型中新型锌合金支架的受力变形情况,为新型锌合金支架的设计与应用提供科学的参考意见。方法运用Pro/E三维建模软件构建理想化的50%狭窄率血管模型和一种I型连接筋血管支架;利用ABAQUS有限元分析软件,模拟支架受相同位移扩张条件作用下分别在钙化和非钙化斑块的理想化狭窄血管中的扩张过程。通过计算支架狗骨头率和残余狭窄率评估支架的支撑性能。结果在斑块材料属性分别为钙化和非钙化的模型中,支架扩张阶段的最大应力分别为433.4 MPa、432.4 MPa,回弹阶段的最大应力值分别为266.1 MPa、259.4 MPa;支架狗骨头率分别为44.5%、33.3%,血管残余狭窄率为40.8%、30.2%。结论支架在扩张过程中受到的von Mises应力都小于材料的应力强度极限,且血管狭窄率都有明显的下降。对于两种斑块类型的狭窄血管,新型锌合金支架都起到了一定的支撑作用。     

冠脉支架与血管耦合作用的有限元分析

目的研究支架扩张直径以及斑块硬化程度对支架与冠脉耦合扩张的影响,探究合理的支架扩张直径范围,以期对临床冠脉支架植入术提供科学的参考依据。方法首先采用三维设计软件建立支架和理想狭窄冠状动脉模型,再利用有限元分析软件,通过赋予冠脉斑块3种不同的材料属性(钙化、纤维化、脂质),参考健康冠脉内径尺寸,模拟分析支架分别扩张至冠脉直径的1.0、1.1、1.2、1.3倍时,支架和血管的应力、支架径向回弹率、冠脉最小腔径以及支架的贴壁情况。结果支架、血管壁和斑块上的最大应力、支架径向回弹率、冠脉最小腔径均随支架扩张直径增加而增加。当支架扩张至冠脉直径的1.3倍时,血管壁及钙化斑块上的最大应力已处于或超出极限应力范围;当支架扩张至冠脉直径的1.0倍时,支架卸载回弹后会出现明显的贴壁不良。相比其他两种斑块,钙化斑块导致更高的血管应力和更小的血管腔径增长。结论冠脉支架扩张比例范围在1.1~1.2倍较为合理;其中,含钙化斑块的冠脉,应将支架扩张比例控制在1.1倍更为合理。研究结果可为冠脉支架植入术中支架扩张直径的选择提供参考依据。     

斑块偏心率对可降解聚乳酸支架植入狭窄血管的影响

目的 研究支架在植入狭窄血管后,斑块偏心率对支架性能以及血管和斑块应力分布的影响.方法 构建支架和理想化狭窄血管模型,赋予斑块4种不同偏心率(0％、20％、40％、60％),采用有限元方法分析支架扩张至目标位移时,支架的径向回弹率和轴向缩短率、血管和斑块的应力变化情况.结果 随着斑块偏心率增加,支架的径向回弹率和轴向缩...     

冠脉重叠支架虚拟置入的有限元分析

在经皮冠状动脉介入治疗(PCI)中,重叠支架多运用于治疗弥漫长病变冠脉。关于重叠支架的临床研究有很多,虽提供手术效果和支架的临床疗效,但不能直观地揭示重叠支架置入过程中支架与支架、支架与血管之间的相互作用。通过对重叠支架置入弥漫长病变冠脉进行有限元分析,观察支架置入过程中支架与血管形态和应力的改变,并对其进行分析。通过计算机断层扫描血管造影(CTA),重建出真实的右冠状动脉(RCA)弥漫长病变模型。应用有限元方法,对重叠Resolute 药物洗脱支架(DES)置入冠脉长病变过程进行模拟,重叠长度3 mm,整个过程包括支架的压握与输送、远端支架与近端支架的置入。在支架虚拟置入过程中,通过观察支架与血管形态和应力的变化进行支架与支架、支架与血管间相互作用的分析。支架置入后,管腔截面积由最初的1.4 mm²增加到6.5 mm²,血管狭窄得到很好的治疗。在支架重叠区域,位于外层的远端支架由于过度扩张,其应力大于近端支架的应力。管壁在支架重叠处的应力(0.64～0.81 MPa)大于非重叠区域的应力(0.32~0.56 MPa),重叠处的血管过度扩张使得管腔截面积没有受到重叠支架的影响。研究表明,重叠支架可使血管血流得以通畅,但支架重叠区域支架与血管的受力较大。     

支架植入后趋直现象对血管壁局部生物力学环境的影响

目的研究支架植入后趋直现象对病变处血管壁力学环境变化的影响,探索支架植入后再狭窄的生物力学成因及支架优化方法。方法基于患者CT扫描图像,使用Mimics、Geomagic和Pro/E软件完成动脉、球囊以及理想与趋直两种支架模型的构建,应用ABAQUS软件建立球囊-支架-冠状动脉左前降至血管之间的力学模型,根据数值模拟计算结果,分析趋直对病变处血管壁力学环境的影响。结果在1.013 MPa充气压力下撑开支架后,与理想支架模型相比较,趋直支架模型的血管壁内表面出现Von Mises应力增大和明显的应力集中现象,尤其是在近心端、远心端及沿心肌表面区域。理想支架模型血管内壁平均和最大Von Mises应力分别0.39、5.12 MPa;趋直支架模型血管内壁平均和最大Von Mises应力分别为0.45、7.43 MPa。结论支架植入后发生的趋直现象将引起应力分布不均匀,出现应力集中,增大对血管壁造成的伤害,可能会引起血管的机械损伤及管壁重建,诱发支架内再狭窄的发生。研究结果可为术后支架内再狭窄的机理分析提供帮助,也为血管介入手术方案及支架优化设计提供参考。     

新型可降解锌合金支架的结构设计及其力学性能分析

目的对比分析一款新结构可降解支架和传统结构可降解支架力学性能和对狭窄血管的治疗效果。方法利用有限元数值模拟,将新结构支架和传统结构支架分别植入直径狭窄为30%的血管,对比分析两种支架的支撑性能及其对狭窄血管重构的影响。结果与传统结构支架相比,新结构支架的径向回弹率和狗骨头率分别降低了26.6%和34.7%。此外,植入新结构支架的狭窄血管回弹较小,拥有更平滑更大的管腔。结论对比传统结构支架,新结构支架具有更高的支撑性能,对狭窄血管的治疗效果更佳。具有高支撑性能的新结构支架有望成为临床介入治疗设备的新选择。     

位姿对支架虚拟释放结果影响的数值模拟研究

目前关于血管支架扩张的有限元分析并未将支架释放位姿这一因素对扩张结果的影响考虑在内。本研究利用Pro/E软件建立了支架和血管模型,通过ABAQUS软件构建了5种有限元装配模型,分别为0度无偏心模型、3度无偏心模型、5度无偏心模型、0度轴向偏心模型和0度径向偏心模型,分为角度和偏心两组实验进行扩张模拟。计算了各模型的轴向缩短率、径向回弹率、狗骨头率等力学参数,通过比较分析,得出支架虚拟释放时的角度、偏心对数值模拟的影响。计算得到5种模型支架扩张后的残余狭窄率分别为38.3%、38.4%、38.4%、35.7%、38.2%。研究表明位姿对数值模拟结果的影响较小,在对结果精度要求不高的情况下可以忽略这种影响,采用0角度无偏心的基本模型进行扩张模拟。     

颈动脉斑块的流固耦合数值模拟

目的 提出一种基于真实颈动脉狭窄患者的双向流固耦合计算方法,用于分析不同类型颈动脉斑块在病变处的血流动力学参数以及斑块自身的变形和应力变化。方法 对颈动脉中度狭窄病人CT血管造影数据进行3D建模,分离出颈动脉血管壁模型和斑块模型,并进行瞬态流固耦合计算。模拟颈动脉粥样硬化的早期到形成斑块,将斑块类型分为增厚斑块、脂质斑块、混合斑块和钙化斑块,其中增厚斑块视为无斑块的情况,代表血管内膜-中膜的增厚,并对不同斑块类型的狭窄颈动脉进行对比分析。结果 不同类型斑块对整体血流流动影响不大,但是脂质斑块病变处的壁面剪切应力低于其余斑块;以增厚斑块作为对照,斑块出现会抑制动脉的扩张,其中脂质斑块最为明显;钙化斑块有最高的平均结构应力,相反脂质斑块平均结构应力则是最低。结论 本文所提出的计算方法能够同时对流体和固体区域进行分析。研究结果有助于更好理解不同斑块类型对于颈动脉病变处的影响。     

Schizophrenia in a North Swedish geographical isolate, 1900–1977. Epidemiology, genetics and biochemistry

Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc² (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.     

Renal dysplasia and asplenia in two sibs

A family is reported in which two sibs, one male and the other female, both died within 24 hours of birth with enlarged polycystic kidneys. Postmortem histology in the second child showed gross renal dysplasia. In both children the pancreas was enlarged, nodular and cystic but the liver appeared macroscopically normal. In the second child, histological examination confirmed pancreatic fibrosis with cystic dilation of ducts, but showed portal fibrosis with bile duct proliferation in the liver.
This combination of findings is very reminiscent of those in a girl and her brother reported by Ivemark et al. (1959). The children reported here also showed absence or hypoplasia of the spleen, cardiac anomalies and other features of the Ivemark syndrome (Ivemark 1955), a quite different, usually sporadic, congenital disorder. It is suggested that the children described here have a distinct lethal congenital disorder, probably inherited in an autosomal recessive manner.     

The dominant diseases of modernized societies as omega-3 essential fatty acid deficiency syndrome: Substrate beriberi

About 1900, modern food selection and processing caused widespread $\text{epidemics}$ of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a $\text{panh}$ypovitaminosis B, i.e., a mixture of $\text{substrate}$ beriberi and $\text{substrate}$ pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse $\text{endemic}$ disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for $\text{primates}$. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.     

'Very sore nights and days': the child's experience of illness in early modern England, c.1580-1720

Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.     

Guidelines for the Validation and Use of Immunoassays for Determination of Introduced Proteins in Biotechnology Enhanced Crops and Derived Food Ingredients

Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.     

Ultracryotomy: development and application (with examples from the yeast cytology) (author's transl)

The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.     

HLA in North Colombia Chimila Amerindians

HLA-A,-B,-C,-DRB1 and -DQB1 alleles have been studied in Chimila Amerindians from Sabana de San Angel (North Colombian Coast) by using high resolution molecular typing. A frequent extended haplotype was found:HLA-A*24:02-B*51:10-C*15:02-BRB1*04:07-DQB1*03:02 (28.7%) which has also been described in Amerinndian Mayos Mexican population (Mexico, California Gulf, Pacific Ocean). Other haplotypes had already been found in Amerindians from Mexico (Pacific and Atlantic Coast), Peru (highlands and Amazon Basin), Bolivia and North USA. A geographic pattern according to HLA allele or haplotype frequencies is lacking in Amerindians, as already known. Also, five new extended haplotypes were found in Chimila Amerindians. Their HLA-A*24:02 high frequencies characteristic is shared with aboriginal populations of Taiwan; also, HLA-C*01:02 high frequencies are found in New Zealand Maoris, New Caledonians and Kimberly Aborigines from Australia. Finally, this study may show a model of evolutionary factors acting and rising one HLA allele frequency (-A*24:02), but not in others that belong to the same or different HLA loci.     

The universal muscular chamber. A basic unit of the genitourinary, cardiovascular, gastro-intestinal, skeletal, cutaneous, respiratory and other systems, endocameral hypertension; and spasm, the key to their idiopathic diseases and arthropathies

Starting with the integument, we see many organs are contractile sacs or multiples thereof, which tubes or bags constitute the major part of the entire body. Recognition of this basic unit and its characteristics sheds new light, individually and collectively, on many disorders previously considered unrelated. Muscular tears and perforations develop in the walls of these chambers, being no way peculiar to those organs, wherein, hydrochloric acid occurs. So, it is not necessary to explain the absence of excessive acid from patients who exhibit holes in the gastric, uterine, aortic, duodenal, rectal, pulmonary, retina, and other walls. Muscle, not acid is the great common factor relating idiopathic disorders in the gastrointestinal tract to each other and to similar diseases in other systems. When the units are linked together, the lesions tend to appear as arthropathies, i.e. at the joints. Rephrasing common-place observations, frees us from conventional, conceptual cul-de-sacs. An observation is only as good as its interpretation, so all possibilities must be considered, otherwise, we will remain blinded by our misconceptions.     

Der Einfluß von Nahrungsmitteln und Rauchen auf die klinisch-chemische Diagnostik von Phäochromozytom,Neuroblastom und Karzinoid-Syndrom

Zusammenfassung Der Einfluß von verschiedenen Nahrungsmitteln auf Methoden zur Bestimmung von Adrenalin (AD), Noradrenalin (NA), Vanillinmandelsäure (VMS), Metanephrinen (MN), Homovanillinsäure (HVS) und 5-Hydroxyindolessigsäure (5-HIE) im 24 h-Harn zur Diagnose des Phäochromozytoms bzw. Karzinoid-Syndroms wurde untersucht. Die in die Untersuchung einbezogenen Nahrungsmittel waren: Tee, Kaffee, Mandeln, Ananas, Käse, Walnüsse, Vanillepudding, Bananen, Tomaten und Milchschokolade. Außerdem wurde der Einfluß des Zigarettenrauchens auf die Bestimmung von AD, NA, VMS und MN untersucht.Walnüsse führten zu einer starken Erhöhung der 5-HIE-Ausscheidung. Bananen erhöhten die Ausscheidung von AD, NA, VMS, MN und 5-HIE. Kaffee und Ananas bewirkten eine geringe Zunahme der MN-Werte. Rauchen von 20–30 Zigaretten/Tag beeinflußte keine der vier Variablen.Wenn die beschriebenen Methoden benutzt werden, sollte lediglich auf den Verzehr von Bananen und Walnüssen vor und während der Harnsammelperioden verzichtet werden, da die oberen Normgrenzen im Harn überschritten werden könnten. Ein Verzicht auf Kaffee und Ananas in normalen Mengen ist nicht erforderlich. Es besteht kein Anlaß, weiterhin die bisherigen umfangreichen Restriktionen der übrigen Nahrungsmittel beizubehalten.