Three-dimensional organization of the elastic fibres in the rat lung

Background: The elastic framework of the distal lung has been studied by light microscopy (LM) and transmission electron microscopy (TEM). The preservation of the elastic fibres, for the three-dimensional observation in their relative positions, is difficult because they lack support when the normal methods of tissue processing are used. The goal of the present study was to understand the three-dimensional ultrastructure and organization of the elastic fibres of the lung preserved in their relative positions. Methods: A combination of intravascular resin injection and formic acid digestion was used. The resin cast of the microvasculature acted as a scaffold to preserve the in vivo arrangement of the elastic fibres that are, otherwise, easily collapsible. Scanning electron microscopy (SEM) samples were further processed for TEM in order to confirm that the fibres were indeed components of the elastic system. Results: SEM demonstrated a fine framework of elastic fibres, representing remnants of the alveolar walls, with the casted capillaries interwoven with the network of elastin. Each individual elastic fibre is composed of a small bundle of discrete fibrils. Some of these fibrils emerge from the fibre and join other fibres, producing an anastomosing appearance. Several elastic fibres link the walls of the intrapulmonary conducting airways, the vessels walls and the alveolar network, thus establishing an interrelated and interlaced framework. Conclusions: The method we have applied to visualize the elastic fibres of the lung is a unique approach to define the spatial organization of the pulmonary elastic fibres. We have demonstrated here the close relationship between the elastic fibres and the capillaries of the septal alveoli. The arrangement of the interwoven network of elastin and its relationship with the capillaries offers the structural setting for the distending capacity of the alveolar wall. © 1995 Wiley-Liss, Inc.     

小剂量放疗对弹性蛋白及弹性蛋白酶mRNA表达的影响

目的　探讨小剂量放射治疗对血管弹性蛋白及弹性蛋白酶mRNA基因表达的影响。方法　以 0、7、14和 2 8Gy6 0 Coγ射线照射培养的大鼠主动脉平滑肌细胞 ,用逆转录 竞争性聚合酶链反应观察照射培养的大鼠主动脉平滑肌细胞弹性蛋白和弹性蛋白酶mRNA水平。结果　 7Gy照射对血管平滑肌细胞弹性蛋白和弹性蛋白酶mRNA的表达无影响 ,14和 2 8Gy照射后细胞弹性蛋白mRNA水平较对照组增加了 80 7%及 10 2 3% (P <0 0 5 ) ,细胞弹性蛋白酶mRNA水平较对照组减少了 2 5 3%及 5 0 1% (P <0 0 5 )。结论　提示 14和 2 8Gy6 0 Coγ射线照射通过抑制弹性蛋白酶及增加弹性蛋白合成而影响血管细胞外基质的代谢。     

Effects of Ethanol on Intracorporeal Structures of the Rat

Objective: Previous studies demonstrated that acute in vitro exposure of corpus cavernosal tissue to ethanol decreased its response to field stimulation and pharmacological stimulation. In the present study we investigated the effects of chronic ethanol consumption on the ultrastructure of cavernosal smooth muscle cells, elastic fibres and collagen content. Material and methods: Fourteen adult wistar rats were divided into a control group (n = 7, fed a standard diet and tap water) and an alcoholic group (n = 7, fed a standard diet and 5% (v/v) ethanol in drinking water and by increasing the ethanol concentration for every week, at the end of 6th week 30% (v/v) ethanol concentration was attained. Same dose was given until 12th week. At the end of 12th week blood samples were obtained and the ethanol concentrations were determined. The cavernosal tissues were obtained and immunohistochemical examinations were performed. Results: Immunohistochemical analysis revealed that chronic ethanol exposure markedly decreased the content of smooth muscle cells, elastic fibres and collagen type 4. Conclusion: Our findings suggest that in this animal model chronic ethanol exposure decreases the percentage of staining for smooth muscle actin, elastin, and collagen type 4 which are the key structures fundamental for erection.     

肝癌自发性破裂患者血管超微结构研究

目的 通过透射电子显微镜对发生自发性破裂的肝癌小动脉壁进行超微结构检查,进一步证实小动脉病变在肝癌自发性破裂病理变化中的作用。方法 对11例肝癌自发性破裂患者的手术标本与同期随机选取的11例肝癌非破裂患者手术标本进行小动脉壁的透射电子显微镜检查。结果 3例肝癌自发性破裂的患者存在巨噬细胞吞噬功能活跃的现象,而该现象却存在于10例非破裂患者中。肿瘤破裂的患者中,9例患者的小动脉壁表现出血管受损现象,包括：血管内皮细胞发生细胞连接消失、窗口直径过大、血管内皮显示高蛋白合成征象;血管壁弹力膜断裂、弹性硬蛋白过度增生及胶原纤维结构受损,其弹力膜中可见电子沉淀物。在肿瘤非破裂的患者中,上述血管受损现象仅在2例患者中发现。二组患者的巨噬细胞功能受损及血管受损的发生率有显著性差异。结论 肝癌破裂患者中的小动脉病变使其管壁通透性增加、弹性消失及支撑力下降,是发生自发性破裂出血的重要原因。     

Effect of selective enzymatic digestions on skin biopsies from pseudoxanthoma elasticum: An ultrastructural study

Summary Skin biopsies from patients with pseudoxanthoma elasticum (PXE) were studied by electron microscopy either before or after selective digestions with collagenase, elastase, trypsin, hyaluronidase, chondroitinase AC and ABC, with the aim of identifying an eventual organic component associated with mineralization within the elastin fibers and the chemical nature of the enormous aggregates of filaments very often associated with, but distinct from mineralized elastin fibers. The results obtained, on both embedded thin sections and fresh tissue fragments, showed that (1) elastin fibers, whether mineralized or not, were sensitive only to elastase, and they did not contain significant amounts of materials different from elastin that could be accounted for by ion precipitation; (2) the aggregates of microfilaments in strict connection with altered elastin fibers were mostly sensitive to elastase and hyaluronidase, were partially removed by trypsin and chondroitinase, and were not modified by collagenase, which seems to indicate that the microfilaments consist mainly of abnormally aggregated elastin molecules together with low sulfated proteoglycans. It may be concluded that PXE is a complex genetic disorder of the connective tissue, and that mineralization of elastin is only one of the alterations of the extracellular matrix.     

Pre-eclampsia associated alterations of the elastic fibre system in umbilical cord vessels

Although pre-eclampsia (PE) is often associated with fetal hypoxia, hypertension and/or disturbed function of the fetal circulation, the effect of these altered hemodynamic parameters on the structure and composition of umbilical vessels has not been systematically investigated before. Therefore, this study focuses on PE-associated changes of the elastic fibre system in umbilical cord vessels investigated by light and electron microscopy, immunocytochemistry and biochemistry. In umbilical cord veins, no changes in thickness of the vessel wall or of any sublayer were observed. However, the internal elastic lamina of the veins was split in 80% of the PE-group in contrast to 20% in uncomplicated pregnancies. This effect was significant (α <0.01) from 36 weeks of gestation onwards. In umbilical cord arteries, the entire arterial vessel wall was found to be 15% thicker in PE than in uncomplicated pregnancies. The enlargement was caused by an increase of both the tunica intima and tunica media. The thickening of the tunica intima was attributed to a migration of smooth muscle cells towards the endothelium, accompanied by a splitting of the internal elastic lamina. Compared to uncomplicated pregnancies, smooth muscle cells of arteries and veins in PE showed a metabolic activation demonstrated by highly dilated endoplasmic reticulum. A semiquantitative score method as well as a quantitative dot blot assay indicated a PE-associated reduction of elastin expression in the arterial vessel walls. In summary, PE obviously induces a decrease of the elastin content accompanied by a thickening of the vessel wall in umbilical cord arteries. This remodeling of the elastic fibre system, together with an increased migration of smooth muscle cells, might represent part of the functional adaptation system of the umbilical cord arteries on the altered hemodynamic conditions in PE. Accepted: 29 November 1999     

Histologic and Histometric Study of the Aortic Media in Dissecting Aneurysm Comparison with True Aneurysm and Age-matched Controls

We studied the histologic and histometric features of the aortic media in cases of dissecting aneurysm in order to clarify the pathologic background of this condition. The results were then compared with cases of true aneurysm and control specimens of "normal" aging aorta. Most cases of dissecting aneurysm and true aneurysm, as well as a number of control specimens, showed severe cystic medial necrosis, and therefore this feature does not appear to be specific to dissecting aneurysm. Fibrosis was noted in the process of repair of medionecrosis in dissecting aneurysm, true aneurysm, and controls. The main pathologic features of the aortic media in dissecting aneurysm included a higher grade of elastin fragmentation (offensive factor) and less fibrosis (defensive factor). Our findings indicate that the pathologic balance between these offensive and defensive factors is an important consideration when evaluating the pathogenesis of dissecting aneurysm.     

Abnormal Elastic Fibers in Elastosis of Breast Carcinoma UItrastructuraI and ImmunohistochemicaI Studies

Elastosis in benign and malignant breast lesions was studied by light microscopic immunohistochemistry for elastin and by electron microscopy. Upon immunohistochemical examination for elastin, elastosis, particularly in scirrhous-type ductal carcinoma, showed two characteristic staining patterns: fibrously and intensely stained elastic fibers and evenly stained elastic masses. Elastic fibers showing increased fibrous staining occurred mainly in the stromal areas, and were considered to be newly formed because they consisted of tannic acid-positive amorphous components and abundant microfibrils. Evenly stained elastic masses were observed mainly in the periductal areas and showed less intense stainability. These masses consisted of numerous fine amorphous components with plentiful microfibrils. In some regions within these masses, there were condensed accumulations of irregularly arranged small amorphous components associated with only a few microfibrils. These amorphous components had an ill-defined outline and were occasionally associated with spiralling collagen fibrils and cell debris. On the basis of these findings, the periductal evenly stained elastic masses were thought to be formed by excessive production of elastic fibers and degradation of pre-existing and newly formed elastic fibers. Acta Pathol Jpn 39: 245–253, 1989.     

Pharmacological Inhibition of Cathepsin S Suppresses Abdominal Aortic Aneurysm in Mice

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Design and cellular internalization of genetically engineered polypeptide nanoparticles displaying adenovirus knob domain

Hepatocytes and acinar cells exhibit high-efficiency, fiber-dependent internalization of adenovirus; however, viral capsids have unpredictable immunological effects and are challenging to develop into targeted drug carriers. To exploit this internalization pathway and minimize the use of viral proteins, we developed a simple gene product that self assembles nanoparticles decorated with the knob domain of adenovirus serotype 5 fiber protein. The most significant advantages of this platform include: (i) compatibility with genetic engineering; (ii) no bioconjugate chemistry is required to link fusion proteins to the nanoparticle surface; and (iii) it can direct the reversible assembly of large nanoparticles, which are monodisperse, multivalent, and biodegradable. These particles are predominantly composed from diblock copolymers of elastin-like polypeptide (ELP). ELPs have unique phase transition behavior, whereby they self-assemble above a transition temperature that is simple to control. The diblock ELP described contains two motifs with distinct transition temperatures, which assemble nanoparticles at physiological temperatures. Analysis by non-denaturing-PAGE demonstrated that the purified knob-ELP formed trimers or dimers, which is a property of the native knob/fiber protein. Dynamic light scattering indicated that the diblock copolymer, with or without knob, is able to self assemble into nanoparticles ~ 40 nm in diameter. To examine the functionality of knob-ELP, their uptake was assessed in a hepatocyte cell-line that expresses the receptor for adenovirus serotype 5 fiber and knob, the coxsackievirus and adenovirus receptor (CAR). Both plain ELP and knob-ELP were bound to the outside of hepatocytes; however, the knob-ELP fusion protein exhibits more internalization and localization to lysosomes of hepatocytes. These findings suggest that functional fusion proteins may only minimally influence the assembly temperature and diameter of ELP nanoparticles. These results are a proof-of-principal that large fusion proteins (> 10 kDa) can be assembled by diblock ELPs without the need for bioconjugate chemistry, which greatly simplifies the design and evaluation of targeted drug carriers.