双侧峡部裂对腰椎稳定性影响的实验研究

目的：研究双侧峡部裂对腰椎三维稳定性的影响。方法：实验材料为８具成人新鲜腰椎标本,切断Ｌ２双侧峡部,通过脊柱三维运动试验机,对标本施加前屈／后伸、侧弯和轴向旋转等６种力偶矩（１０Ｎ．ｍ）,由脊柱三维运动分析系统得到腰椎节段的运动范围。结果：双侧峡部断裂后,腰椎前屈／后伸及左／右旋转运动范围分别增加２６．６％、５５．９％、１００．９％、１１５．８％,较正常标本有显著性增大,而左／右侧弯变化不大。结论：峡部对腰椎三维稳定具有重要的力学作用,双侧峡部裂导致腰椎不稳。     

Striated membranous structures in human hearts. An ultrastructural study.

Straited membranous structures (SMS), which consisted of sheets or ribbons of 130 to 220 A in thickness, showed variable patterns of periodic substructure, and resembled SMS described in renal and ocular tissues in various diseases, were found in extracellular locations in a) mitral valve (2 patients) and tricuspid valve (1 patient) of 2 patients with mitral valvular prolapse, b) mitral valve and femoral artery of 1 patient with Marfan's syndrome and prolapsed mitral valve, and c) myocardium (2 patients) and thickened endocardium (3 patients) of 3 patients with congenital heart disease associated with muscular obstruction to right ventricular outflow. Striated membranous structures measured up to several microns in diameter, often were highly folded and convoluted, and sometimes appeared circular in outline. Some SMS measured from 130 to 150 A in thickness and had indistinct edges and poorly defined periodicity. The majority of SMS, however, had greater thicknesses, in the range of 200 A, and a periodicity characterized by alternating light and dark bands with a spacing that varied from 100 to 160 A. The structures were associated with thickened basement membranes, elastic fibers, and membrane-bound bodies of the type thought to be involved in elastogenesis. Evidence available suggests that SMS results from an unusual pattern of arrangement of a component, possibly Type IV collagen, of basement membrane material.     

An ultrastructural study of lactation in the human breast

In this study the morphological features of lactation in the human breast were examined by scanning and transmission electron microscopy. The lactating lobules comprised large numbers of interconnecting acini which were lined by a single layer of epithelial cells with underlying myoepithelial cells. Marked variations were noted in the shape of the epithelial cells. The myoepithelial cells formed an open meshwork of interconnecting cytoplasmic processes packed with myofibrils. The basal cytoplasm of the epithelial cells was packed with rough endoplasmic reticulum while the apical cytoplasm contained a hypertrophic Golgi body, numerous vacuoles (a few of which contained casein micelles), a number of lipid droplets and small coated and uncoated vesicles. The lipid droplets were released by progressive protrusion from the apical surface. They remained covered by the plasmalemma and were finally budded off into the lumen. In certain cases a portion of cytoplasm was released with the lipid droplet. The vacuoles and small vesicles fused with the plasmalemma and released their contents by exocytosis. Within the samples the majority of epithelial cells were actively lactating although examples of undifferentiated "resting" and dead (lysed) cells were also identified.     

Computer visualisation of the moving human lumbar spine

Disorders of the spine which lead to back pain are often mechanical in origin and, despite extensive research, diagnosis of the underlying cause remains problematical, yet back pain is one of the most common rheumatological symptoms presented to the general practitioner. Diagnosis must frequently be based upon evidence gathered at the segmental level which invariably means that imaging is used in the process. In addition, surgical fixation is increasingly used when the spinal column is considered to exhibit instability. A solid model of the spine creates the possibility of visualising spine motion, of assessing the effects of loading of the spinal column in conjunction with finite element analysis to investigate the consequences of vertebral fusion, and of planning surgical intervention. Such a model could also be valuable in medical education and for demonstrating spine motion to a patient to highlight abnormalities or the effects of treatment.

This paper describes a three-dimensional visualisation of the human lumbar spine which runs on a personal computer operating under the Windows environment. The user interface enables the clinician to select the viewpoint for the spine model to allow the motion to be studied from different angles. Motion data are currently acquired from fluoroscopic image sequences but the model could be used to display data from different imaging modalities when they are developed sufficiently for spine motion studies.     

Fibroblastic reticulum cells in human lymph nodes. An ultrastructural study

The ultrastructural characteristics of the fibroblastic reticulum cell (FRC) in human reactive lymph nodes, which were studied electron microscopically, indicate a myofibroblastic cell with unique properties. Its contractile element is probably useful in controlling the volume of the lymph node and possibly in the movement of antigens and antibodies. The FRC may also play a role in other immunologic functions and seems to be preponderant in some lymphomas.     

An ultrastructural study of normal human thymic epithelium in primary cultures.

The ultrastructural study of a large series of samples of normal human thymic epithelial cells (TECs) in primary cultures is here presented. Cultured TECs are heterogeneous due to marked differences in their cytoplasmic organization. In particular, a spectrum of ultrastructural features have been observed, ranging from poorly-differentiated cells to secretory and epidermoid-like ones, as well as intermediate transitional forms and cells co-expressing both epidermoid-like and secretory features. Cells with peculiar secretory (neuroendocrine-like) characteristics have also been identified in the culture obtained from one of the donors. These data suggest the existence of a thymic epithelial cell type which may act as a dynamic unit, changing its cytoplasmic organization in response to microenvironmental signals. The types and interrelationships of cytoplasmic organelles observed in the secretory cells suggest that the production of thymic peptides involves the classical pathway of protein synthesis and secretion.     

The effect of phorbol myristate acetate on human lymphocytes. An ultrastructural study.

Phorbol myristate acetate (PMA), a tumour promoter, acts as an agglutinin and as a stimulator of human lymphocytes. Agglutination begins within 1 hr and is macroscopically evident within 24 hr. The ultrastructural findings in lymphocytes stimulated with PMA after 48 and 72 hr show blast transformation of the nucleus, increase in cytoplasm and in ribosomes, and occasional “annulate lamellae.” Apart from the finding of “annulate lamellae” the changes are generally similar to those found in PHA stimulated lymphocytes. The function and significance of the “annulate lamellae” are not known but as they have been most often seen in malignant and embryonal cells they may be representative of a more fundamental dedifferentiation of the cells with PMA as opposed to PHA.     

Mucoepidermoid carcinoma of the subglottis. An ultrastructural study

A well-differentiated mucoepidermoid carcinoma of the subglottis of a 77-year-old man was studied by light and electron microscopy. The tumor consisted of mucous cells, epidermoid cells, and intermediate cells of both differentiation. Mucous cells formed glands and cystic spaces filled with mucin. Abundant tonofibrils in aggregates were observed in tumor cell cytoplasms when they were differentiated into epidermoid cells. Epidermoid cells varied in differentiation.     

Exosomes in human atherosclerosis: An ultrastructural analysis study

Cell-to-cell communication, or signaling, is absolutely essential in orchestrating the activities of cells in multicellular organisms, to grow, develop, detect environmental changes and compensate for them in an internal, coordinated fashion. In the last few years, a considerable amount of new data have demonstrated the occurrence of a sophisticated intercellular signaling pathway based on the release of specialized vesicular structures, called exosomes, whose secretion appears to be regulated by various natural and experimental stimuli, physiological states, and disease processes. In the cardiovascular system, the study of exosomes is still in its infancy. Here, we aim to provide the first ultrastructural evidence for the presence of exosomes in human atherosclerotic plaque. We demonstrate by means of transmission electron microscopy that both lesional smooth muscle cells and endothelial cells are able to generate these membraneous microvesicles within specific compartments of the cell, called multivesicular bodies. Notably, in our series no signs of apoptosis have been detected in vascular cells secreting exosomes and no evidence of calcification has been observed associated with these structures in the extracellular space. Our results suggest the possible existence of a new mechanism of intercellular communication in the plaque milieu.     

Male breast carcinoma. An ultrastructural study.

A case of infiltrating ductal carcinoma of the male breast was studied by electron microscopy. The ultrastructure of the tumor is similar to that described in the female breast. Myofibroblasts are the preponderant cells in the stroma. Their significance and possible relation to hormonal stimuli are discussed.     

Leiomyomatosis peritonealis disseminata. An ultrastructural study

Electron microscopic features of the eighth documented case of leiomyomatosis peritonealis disseminata identify the main proliferative cell type as a mature leiomyocyte with all its associated ultrastructural features. The histogenesis of this neoplasm is considered to be a multicentric metaplastic change determined by an abnormal tissue response to the elevated hormonal levels occurring in pregnancy or ovarian functioning tumors. It is suggested that the cell of origin is the multipotent subcelomic mesenchymal cell, which retains the capacity to differentiate into several tissues, among them smooth muscle. To illustrate this possibility, myofibroblasts, cells with hybrid characters of fibroblasts and leiomyocytes, were observed; these may represent a transitional stage between the mesenchymal cell and the smooth muscle proliferating cell.     

The normal human thymic vasculature: An ultrastructural study

Electron microscopy of the normal human thymus demonstrates a characteristic vascular-parenchymal relationship. The vascular lumen is always separated from the thymic parenchyma by: the endothelial cell cytoplasm, a muscular coat in arterioles and veins, the vascular basal lamina, a perivascular space containing collagen fiber and cells, the epithelial-reticular cell basal lamina and the epithelial-reticular cell cytoplasm. The width of this perivascular space is proportional to the size of the vessel it surrounds; it is wide around the vessels in the septa and at the cortical-medullary junction, but narrow around capillaries. While many cells are present in this space around the larger vessels, only collagen is observed around the capillaries. Lymphocytes are the predominant cell type in the space; however, plasma cells, eosinophils, histiocytes, polymorphonuclear leukocytes, mast cells and unidentified granulated cells are also seen. The vascular complex described above may function as a blood-thymus barrier, as the initial site of exposure of the lymphocytes to circulating antigen and as the route of emigration of lymphocytes from the thymus.     

胸腰椎脊柱韧带拉伸性能的实验研究

目的：测试胸腰段脊柱韧带拉伸性能。方法：采用７例新鲜青年男性尸体胸腰椎脊柱韧带，进行解剖学观察和力学测试，每个韧带的测试除外其它因素单一进行。记录最大载荷－位移曲线和韧带的形态、力学改变，峰值为韧带断裂的标志。结果：前纵韧带、后纵韧带、棘间、棘上韧带最大破坏载荷依次为：６５４±６３Ｎ，２９１±４９Ｎ，９８±４３Ｎ，３８５±９３Ｎ；最大位移依次为：１１．４±２．６ｍｍ，４．５±１．５ｍｍ，３．８±１２．２ｍｍ，１６．０±５．０ｍｍ；结构刚度依次为：６０．４Ｎ／ｍｍ，５６．２Ｎ／ｍｍ，２５．０Ｎ／ｍｍ，４０．５Ｎ／ｍｍ。结论：不同种韧带的解剖形态和生理特点不同，具有不同的生物力学特性。