PubMed Health⌕ Search

Biomedical subjects

O M Toledo

Publications and source records attributed to O M Toledo.

At least 19 recordsLinked to original sources
PubMed1996

Effect of aqueous and nonaqueous fixatives on the quantitative estimation of collagen-proteoglycan interaction in tissue sections.

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.

Animals↗
PubMed1995

Glycosaminoglycan distribution in atherosclerotic saphenous vein grafts.

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.

Aged↗
PubMed1994

Rabbit knee-joint meniscal proteoglycans.

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.

Animals↗
PubMed1993

Age-related changes in glycosaminoglycan distribution in different anatomical sites on the surface of knee-joint articular cartilage in young rabbits.

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.

Aging↗
PubMed1989

Analysis of the proteoglycans synthesized by corneal explants from embryonic chicken. I. Characterization of the culture system with emphasis on stromal proteoglycan biosynthesis.

Corneal explants with scleral rims were freshly prepared from day 18 chicken embryos and incubated in vitro for 3 h in the presence of various radioactive precursors. Radiolabeled proteoglycans were isolated from the stromal tissue and culture medium for analysis. Two predominant proteoglycans were identified in corneal stroma. One contains dermatan sulfate and the other contains keratan sulfate; a structural analysis of each is reported in the accompanying paper (Midura, R.J., and Hascall, V.C. (1989) J. Biol. Chem. 264, 1423-1430). A minor keratan sulfate proteoglycan distinct from the major form, a small amount of heparan sulfate proteoglycan, and some sulfated glycoproteins were also detected in stromal extracts. The biosynthesis of the dermatan sulfate proteoglycan was stable in vitro and in ovo, whereas that of the major keratan sulfate proteoglycan was stable only in ovo. Various treatments were tried to maintain a high rate of keratan sulfate synthesis with time in culture. Cooling the corneal explants to 5 degrees C was the only treatment that reduced this decline in keratan sulfate synthesis in vitro to any significant extent. Three major proteoglycans were observed in the culture medium. Two were dermatan sulfate proteoglycan and appeared to be mainly derived from the scleral tissue surrounding the corneal explant. The third proteoglycan contained keratan sulfate. It was smaller in size and lower in charge density compared to the keratan sulfate proteoglycan found in the stroma, but both appeared to have similar core protein sizes. It seems likely that this proteoglycan was synthesized in the stroma and secreted into the medium. A small amount of heparan sulfate proteoglycan and some sulfated glycoproteins were also detected in the medium.

Animals↗
PubMed1987

A morphologic and histochemical study of the mesentery in the guinea pig.

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.

Animals↗
PubMed1986

Morphological, histochemical and biochemical observations on the connective tissue matrix of in situ and isolated hepatic granulomas in experimental murine schistosomiasis.

The connective tissue matrix of hepatic granulomas from Swiss mice, each infected with 20 Schistosoma mansoni cercariae, was examined using morphological, histochemical and biochemical methods, during the evolution of the disease. Evidence was obtained by both light and electron microscopy that suggested the presence of two different collagen populations which appeared successively during granuloma evolution. Morphological features suggesting the occurrence of collagenolysis were observed at the final stage of granuloma development. The connective tissue matrix of schistosome granulomas was devoid of elastic system fibres. Schistosome egg granulomas contain dermatan sulphate-proteoglycan.

Animals↗
PubMed1983

Evidence for collagen molecular orientation in basement membranes.

The following basement membranes (BMs) from representative species of the main vertebrate classes were studied by the Picrosirius-polarization method: lens capsule, Reichert's membrane and glomerular BMs. A distinct birefringence was consistently observed in all BMs from all species studied by this method. The results reported provide a strong evidence for collagen macromolecular orientation in BMs. Heparitin sulphate was the only glycosaminoglycan detected in dogs lens capsules.

Animals↗
PubMed1983

Histochemical and morphological studies on a new type of acellular cartilage.

A new type of cartilage was found participating in a valve-like system inside the conus arteriosus of the fresh water sting ray, Potamotrygon sp.. This cartilage possesses no chondrocytes and its matrix is perforated by vascular channels that ramify dendritically forming canaliculi. The acellular cartilage does not possess perichondrium but, rather, it is attached to a basement membrane-like structure. The cartilaginous matrix contains collagen fibrils that strongly interact with the chondroitin sulfate of the ground substance. The histochemical and biochemical findings suggest that not all of the glycosaminoglycans present in the acellular cartilage are bound to protein cores to form proteoglycans.

Animals↗
PubMed1982

Fine structure and histochemistry of the tail fin ray in teleosts.

Ultrastructural and histochemical studies performed on the skeletal elements of the tail fins of six representative species of teleosts enabled the following observations to be made. The electron microscopic pattern of amorphous substance deposition, and the diameter of the collagen fibrils, in lepidotrichia closely resemble those which are typical of cartilage. In addition, lepidotrichia contain chondroitin sulfate AC as the only sulfated glycosaminoglycan, and this glycosaminoglycan shows high levels of interaction with collagen, both features being characteristic of cartilage. Furthermore, the histochemical data presented in this paper suggest that not all of the glycosaminoglycans present in lepidotrichia are bound to protein cores to form proteoglycans. Each actinotrichium consists of a single ultrastructural entity of remarkable width and, thus, is not composed of a bundle of discretely separated collagen fibrils but rather of hyperpolymerized collagen molecules. This aspect differs from the arrangement pattern of all the other interstitial collagens, suggesting that actinotrichia may contain a new type of collagen.

Animals↗
PubMed1981

Correlation of specific sulfated glycosaminoglycans with collagen types I, II, and III.

A qualitative and quantitative biochemical study of the glycosaminoglycans was performed in tissues constituted predominantly by one type of collagen, or in tissues containing mixtures of different types of collagen. The results obtained show the presence of dermatan sulfate, chondroitin sulfate, and heparin sulfate in tissues containing collagen types I, II, or III, respectively, suggesting a specific correlation of different glycosaminoglycans with these three types of collagen.

Animals↗
PubMed1981

Migrating mast cells in the gallbladder epithelium of cattle and sheep. A comparative morphologic and histochemical study.

This paper reports the existence of mast cells in an epithelial location in the gallbladders of both cattle and sheep. The histochemical studies performed on these cells showed that their cytoplasmic granules contain heparin and biogenic amines in both species. Optical- and electron microscopic observations demonstrated that, in both species, mast cells from the connective tissue of the gallbladder diapedese across the basal lamina and migrate through the epithelium all the way to the luminal surface, and that a degranulation process takes place during this migration. The biochemical results showed a correlation between the number of mast cells present in the epithelium and the amount of heparin detected in the different regions of the gallbladders of the species studied. Unusually high contents of heparin were found in both cattle and sheep gallbladders, suggesting that they should be studied as possible commercial sources of this polimer.

Animals↗
PubMed1980

Morphologic and histochemical evidence for the occurrence of collagenolysis and for the role of neutrophilic polymorphonuclear leukocytes during cervical dilation.

Biopsy specimens of nonpregnant and intrapartum human cervices were studied by electron microscopy, and by the Picrosirius-polarization method which is a specific procedure for the detection of collagen fibers in tissue sections. The results obtained demonstrate a marked reduction of collagen fibers in the intrapartum material as compared to the samples of nonpregnant cervices. Evidence that indicated the presence of a widespread collagenolysis in the intrapartum biopsy specimens was obtained by both optical and electron microscopy, thus suggesting that this might be the main cause of the changes in the cervix that permit it to dilate during parturition. The study of the neutrophilic polymorphonuclear leukocytes in the intrapartum biopsy specimens strongly suggested that these cells participate in this process.

Cervix Uteri↗
PubMed1980

Sulfated glycosaminoglycans of cultured fibroblasts from guinea-pig embryo kidney.

The sulfated glycosaminoglycan content of primary cultures of fibroblasts from guinea-pig embryo kidney is reported. A hybrid chondroitin sulfate comprises approx. 90% of these glycosaminoglycans from the cell coat. Changes in the proportion of labelled heparitin sulfate were also observed after successive subcultures. We postulate a possible correlation between the pattern of glycosaminoglycans and processes of cell selection and cell dedifferentiation in these cultures.

Animals↗
PubMed1980

Histochemical and morphological characterization of migrating mast cells in the bovine gallbladder epithelium.

This paper reports the existence of granulated cells in the bovine gallbladder epithelium. The histochemical studies performed on these cells showed that their cytoplasmic granules contain heparin. Optical- and electron microscopic observations demonstrated that these mast cells migrated from the adjacent connective tissue, and crossed the basal membrane in order to enter the epithelium and reach the luminal surface.

Animals↗
PubMed1979

Glycosaminoglycans and proteoglycans of normal and tumoral cartilages of humans and rats.

Differences in the glycosaminoglycans and proteoglycans synthesized by "young," "adult," and tumoral chondrocytes are reported. Young cartilage and human chondrosarcoma contain chondroitin 4- and 6-sulfates, whereas adult human cartilage contains almost exclusively chondroitin 6-sulfate. High keratan sulfate content is reported in adult cartilage, whereas it is almost absent in young and tumoral cartilages. The electrophoretic pattern and keratan sulfate content in these proteoglycans from adult cartilage are clearly distinct from those of the young and tumoral cartilages. The high molecular weight is the distinguishing property of the glycosaminoglycan synthesized by tumoral chondrocytes.

Animals↗
PubMed1977

Tissue specific distribution of sulfated mucopolysaccharides in mammals.

A comparative study on the distribution of sulfated mucopolysaccharides in several tissues of five mammalian species is reported. It is shown that each tissue has a characteristic composition differing from each other regarding the relative amount, type and molecular size of chondroitin sulfate A/C, chondroitin sulfate B and heparan sulfate. It is also shown that the same tissue from different mammals has the same types and proportions of sulfated mucopolysaccharides, but with different molecular weights. Exception to this rule was observed for the distribution of heparin which was present only in a few tissues of the five mammals studied. The possible involvement of the sulfated mucopolysaccharides in cell recognition and/or adhesiveness is discussed in view of this characteristic distribution.

Animals↗