RESUMEN

Marked changes in mice pubic symphysis occur by the end of pregnancy. Tissue remodeling involves a dynamic balance between cell proliferation and programmed cell death as well as changes in the extracellular matrix components. Therefore, it is important to consider both of these cellular behaviors when investigating the mechanism that regulates interpubic tissue remodeling, growth during late pregnancy and partus ensuring involution during the postpartum period. Proliferating and programmed death cells were identified by immunohistochemistry (proliferating cell nuclear antigen and TUNEL detection, respectively) and the rates at which these processes occurred were determined by morphometric analysis. The results demonstrated that cellular proliferation was intense during the period of ligament formation, from D15 to D18, thereafter abruptly declining on D19. From parturition (D19) onwards, an ever-increasing decline in the cellular proliferation levels could be observed. The quantitative analyses of cellular death showed opposite results when compared to cellular proliferation. During early pregnancy the cycle of cellular renovation was clearly proliferative and during late mouse pregnancy the cycle was directed by programmed cellular death. Although the high levels of cellular death during postpartum involution could be shown by the TUNEL-positive cells, we were unable to observed picnotic nucleus at the light microscopy.

Asunto(s)

RESUMEN

During pregnancy, an interpubic ligament is formed in the mouse pubic symphysis. In late stages, this ligament undergoes "relaxation" to allow proper delivery, which is expected on the 19th day. Proteoglycans and hyaluronic acid play an important role in the remodeling of the extracellular matrix in these tissues. Glycosaminoglycans and proteoglycans were studied by electron microscopic, immunohistochemical and biochemical methods in samples of mouse pubic symphysis from the 12th to 18th day of pregnancy. At the ultrastructural level, using cuprolinic blue and enzymatic digestion by chondroitin lyases, two types of proteoglycan filaments were observed in the fibrocartilage on the 12th day, as well as in D 15, D 17 and D 18 pubic ligaments. The only sulfated glycosaminoglycan in these filaments was chondroitin sulfate, as shown by chondroitin lyase treatment. Their electrophoretic mobility, before and after enzymatic degradation, corroborated this inference. The ratio of chondroitin sulfate/dry weight of symphysis showed two phases of increase: between D12 and D 15, and between D 17 and D 18. We suggest that the first corresponds mainly to an increase in decorin when the ligament is formed, and the second to versican, during "relaxation". Versican and hyaluronic acid, working as water holding molecules would be responsible for the hydration of the ligament at the end of pregnancy, allowing an increase in resiliency. The presence of hyaluronic acid was confirmed by labeling with HA-probe in the perichondrium, fibrocartilage and ligament. The role of collagen fibers as physical restrictors of the complete expansion of glycosaminoglycans and hyaluronic acid in tissue is discussed.

Asunto(s)

RESUMEN

Reference is usually made to the parallel orientation towards the main line of exerted tension at the pubic joint in mice, for supporting forces applied to the joint. Despite the wealth of morphological information about the extracellular matrix in this joint, little is known regarding the involvement of the crimp of collagen fibers in the dramatic transformations occurring in this region during the last 3 days of pregnancy. Examination of the collagenous architecture suggests that the biomechanical properties are directly related to fibril diameters, composition of ground substance and changes in the bundle morphology, particularly in the crimp structure. The purpose of this study was to further describe the transformation of the collagen fibers of the pubic symphysis during late mouse pregnancy. We examined the architecture of collagen fibers in the symphysis and pubic ligament through the Picrosirius-polarization method and also through scanning electron microscopy to directly visualize and measure the crimping from pregnant and virgin mice. The crimp angle and the length of five consecutive crimps were measured according to Patterson-Kane et al. [Connect. Tissue Res. 36 (1997) 253]. It could be demonstrated that the angles progressively decreased and the crimp length increased, denoting that the fibers have untwisted during the relaxation process. Our findings suggest that a disruption of the helical arrangement of the collagen containing fibers may contribute to explaining the rapid remodeling that occurs at the end of pregnancy and that is responsible for an increase in pliancy and length of the pubic ligament in mice.

Asunto(s)

RESUMEN

We described the behaviour of 120 days rabbit knee-meniscus cells in monolayer culture. The cells were grown forming cellular aggregates resembling true cellular nodules. Three stages of development of these nodules could be observed: formation of the cellular nodules between days 1 and 3; nodular growth, with their maximal at day 5; and nodular regression beginning at day 8. Ultrastructural analysis of the extracellular matrix of these cellular nodules was assessed on days 3, 5 and 8. At the formation stage, we could observe striated collagen fibrils and small bundles of tubular microfibrils either interspersed with very low quantities of amorphous elastin, being morphologically identical to elaunin fibers, or without only trace of elastin, being morphologically identical to oxytalan fibers. By day 5, fibrillar elements with 100 nm periodic ladder-like collagen VI fibrillar aggregates could also be detected. At day 8, the striated collagen fibrils and oxytalan fibers could not be observed. During this same period, there was an increase of a dense matrix comprised of collagen VI and mature elastic fibers. Chondroitin/dermatan sulfate proteoglycans were synthesized and became essential for the arrangement of collagen type VI, since chondroitinase ABC treatment of the culture disrupted collagen VI assembly, associated with the large spaces near the cell surface. In addition, the cells lost their fusiform morphology and changed into rounded cells. The results show that primary cultures of rabbit meniscus fibrochondrocytes maintain their capacity to form chondro-like structures in vitro. The organization process was rapid and uniform throughout the entire culture presuming that the normal signal transduction pathways are maintained intact and that essential factors in some phases of tissue organization are present.

Asunto(s)

RESUMEN

The present study was designed to assess the influence of aqueous and nonaqueous fixatives on the quantitative estimation of collagen-proteoglycan interaction in tissue sections. Tissues containing different collagen types and distinct sulfated proteoglycan classes were isolated from pig costal cartilage, human skin, and the inner muscular layer of dog small intestine and fixed using aqueous or nonaqueous methods. The results showed that the best fixation method was exposure to paraformaldehyde gas. When using aqueous fixatives, proteoglycans were lost to different degrees among the various tissues analyzed, reflecting differences in chemical properties of proteoglycan classes and/or in their interactions with other matrix components such as collagen.

Asunto(s)

RESUMEN

Glycosaminoglycan composition of normal saphenous veins and atherosclerotic saphenous vein grafts is reported. Dermatan sulfate is the main glycosaminoglycan present in both normal saphenous veins and saphenous vein grafts. These tissues also contain chondroitin sulfate and heparan sulfate. Although the total amount of glycosaminoglycans decreased in the grafts (compared with normal saphenous veins), the grafts showed an increase in the relative amounts of dermatan sulfate and chondroitin sulfate. Heparan sulfate was decreased, compared with normal controls. These findings suggest the involvement of blood vessel glycosaminoglycans (not only the arterial glycosaminoglycans) in the process of atherosclerosis.

Asunto(s)

RESUMEN

A major proteoglycan (PG) in rabbit meniscal fibrocartilage was extracted with 4 M guanidine-HCl. It represented 63% of the total uronic acid originally present in the tissue. The non-extractable PG could be released by treating the guanidine HCl-extracted tissue with trypsin followed by alkaline hydrolysis. The glycosaminoglycan (GAG) chains from the non-extractable PGs are shown to be of a different type than the extractable forms since the relative amounts of chondroitin sulphate isomers differ from each other.

Asunto(s)

RESUMEN

In spite of the fact that the various anatomical regions of a given articular cartilage surface are subjected to different degrees of stress, the present observations strongly suggest that there exists a topographical homogeneity in the distribution of glycosaminoglycans in the same articular cartilage. In contrast to this age-related changes in the proportion of the different types of glycosaminoglycan species in articular cartilage are remarkable. Non-sulphated chondroitin could only be detected in very young articular cartilage. Dermatan sulphate, which has already been detected in young adult rabbits, was followed by the appearance of keratan sulphate in older rabbits. Chondroitin 4-6-sulphates were detected in all articular cartilages studied, the proportion of the 6-sulphated variably increasing with age. The present report suggests that the distribution of glycosaminoglycans in articular cartilage varies with species and age, and the data can further vary, depending on the methods used. It is therefore concluded that generalizations against the results reported in the literature should be considered skeptically.

Asunto(s)

RESUMEN

A simple method was used to isolate hyaluronic acid (HA) and sulfated glycosaminoglycans from synovial fluids obtained from children with juvenile rheumatoid arthritis (JRA) and from normal age-matched controls. The bulk of the glycosaminoglycans present in both normal and pathologic synovial fluids consisted of hyaluronic acid and chondroitin 6-sulfate. The diseased synovial fluids showed a sharp decrease in the concentration of glycosaminoglycans when compared with normal controls. These findings are similar to those reported for the synovial fluid of adult patients with rheumatoid arthritis.

Asunto(s)

RESUMEN

The guinea pig mesentery is a uniform, continuous, thin (18 micron) sheet of connective tissue covered by a single layer of flattened mesothelial cells on both surfaces. Tight and gap junctions provide for cell-to-cell adhesion among mesothelial cells. These cells possess numerous micropinocytotic vesicles; a conspicuous basal lamina separates the mesothelium from the underlying connective tissue. Most of the material found between the two serous coverings consisted of a three-dimensional meshwork of abundant collagenous fibers intermingled with a sparse net of very thin (0.4 micron) elastic fibers. Two distinct populations of collagen fibrils are segregated into different compartments of the mesentery. One population is formed of thick (56 nm) fibrils which associate to form closely packed fibers. The second population, composed of loosely arranged thin (38 nm) fibrils which do not become assembled into fibers, is found underlying the basal lamina that separates the mesothelium from the connective tissue. These observations strongly suggest that the mesentery contains both collagens type I and type III. The guinea pig mesentery contains 6.8 mg of sulfated glycosaminoglycans/g dry weight. Most of these glycosaminoglycans (78%) were identified as dermatan sulfate, whilst the rest (22%) corresponded to heparan sulfate.

Asunto(s)

RESUMEN

A 3a. cruz da ante-helice e uma deformidade congenita, raramente observada entre caucasianos. Consiste numa dobra congenita da cartilagem auricular, que se estende da ante-helice, atravessa a escafa e atinge a helice. Existem formas variadas da deformidade e o tratamento cirurgico esta indicado quando existe alteracao marcada da forma do pavilhao. Realizamos uma Z-plastia multipla na cartilagem, apos a resseccao da dobra, por uma abordagem retroauricular, a fim de evitar cicatrizes aparentes

Asunto(s)

Asunto(s)

Asunto(s)