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At least 1,621 records · Page 90Linked to original sources
PubMed2002

Tropoelastin expression by periodontal fibroblasts.

Elastic system fibers are load-bearing proteins found in periodontal tissue. There are three types--oxytalan, elaunin, and elastic fibers--which differ in their relative microfibril and elastin contents. Oxytalan fibers are known to be distributed in the periodontal ligaments and gingiva, whereas elaunin and elastic fibers are present only in the gingiva. We examined gene expression and accumulation of tropoelastin in the cell-matrix layers of human gingival fibroblasts (HGF) and periodontal ligament fibroblasts (HPLF) in vitro. HGF and HPLF were cultured in MEM containing 10% newborn calf serum for 8 wks. Northern blotting and RT-PCR analyses showed that only HGF expressed mRNA encoding tropoelastin. Western blotting analysis demonstrated 77-kDa protropoelastin and 68-kDa tropoelastin only in the cell-matrix layer of HGF cultured for 8 wks. These results suggest that the different tropoelastin expression patterns reflect the difference between HGF and HPLF phenotypes.

Adolescent↗
PubMed2002

Distribution of myocilin and extracellular matrix components in the juxtacanalicular tissue of human eyes.

PURPOSE: To examine ultrastructurally the composition of extracellular matrix (ECM) materials, the distribution of myocilin, and the colocalization of myocilin with ECM components in the juxtacanalicular tissue (JCT) of normal human eyes. METHODS: Postembedding immunoelectron microscopic studies were performed with antibodies specific for major ECM components, including fibronectin, laminin, vitronectin, tenascin, elastin, fibrillin-1, microfibril-associated glycoprotein (MAGP)-1, decorin, versican, and five types of collagen (I, III, IV, V, and VI). Hyaluronic acid was localized with the use of biotinylated hyaluronic acid-binding protein. Colloidal gold labeling was also performed using an anti-human myocilin polyclonal antibody. Colocalization of myocilin with ECM components was examined by double labeling, using different-sized gold particles. The possible interaction between myocilin and ECM molecules was evaluated by in vitro binding assays. RESULTS: Amorphous basement membrane-like materials in the JCT were confirmed to be made up chiefly of collagen type IV, laminin, and fibronectin. Elastin was localized to the central core of sheath-derived plaques. Fibronectin, fibrillin-1, MAGP-1, decorin, and type VI collagen were all localized to clusters of the banded material in the sheath surrounding the core, where several types of collagen, glycoproteins, and proteoglycans were also detected. Myocilin was found to associate mainly with the sheath material, overlapping extensively in distribution with fibronectin, fibrillin-1, and MAGP-1 and moderately with decorin and type VI collagen. Its localization was distinct from that of elastin. Interactions of myocilin with molecules such as fibronectin and fibrillin-1 were confirmed biochemically. CONCLUSIONS: This study illustrated ultrastructurally the composition of ECM materials in the JCT of normal human eyes. The key finding was the association of myocilin with microfibrillar architecture in sheath-derived plaques where pathologic changes have been documented to occur in eyes of patients with primary open-angle glaucoma.

Adult↗
PubMedDate not supplied

Skin ageing: clinical and histopathologic study of permanent and reducible wrinkles.

Wrinkles are modifications of the skin associated with cutaneous ageing and develop preferentially on sun-exposed skin. The aim of the study was to analyse the clinicopathological features of wrinkles, among the different types of skin relief modifications. Despite its importance in dermato-cosmetology and skin ageing, few studies have been specifically devoted to wrinkles. In the present study, we analyzed the histological features of the pre-auricular wrinkle compared to retro-auricular skin, obtained from sixteen patients undergoing facial surgery; skin samples were immediately processed for routine histology and histochemical staining. Four types of skin depressions could be defined according to their depth: folds, permanent wrinkles, reducible wrinkles and skin micro-relief. Two different types of pre-auricular wrinkles were observed: (i) permanent wrinkles which were conserved after sampling and, (ii) reducible wrinkles which required in vivo staining to be visible at histology. Histological analysis of the epidermis and dermis of the skin forming the pre-auricular wrinkle revealed a normal skin morphology, identical to that of the skin immediately adjacent to the wrinkle. This was particularly striking for the reducible wrinkles which could not be individualized in the absence of in vivo staining. Both types of wrinkles comprised skin modifications observed in sun-exposed skin, however, in the upper dermis, permanent wrinkles showed a more pronounced accumulation of basophilic fibers, i.e. actinic elastosis, than reducible wrinkles did. These data suggest that the development of wrinkles could be secondary to actinic elastosis and to the disappearance of microfibrils and collagen fibers at the dermal-epidermal junction.

Adult↗
PubMed1975

Sclerosing alveolitis induced by cyclophosphamide. Ultrastructural observations on alveolar injury and repair.

Adult rats received, intraperitoneally, 20 mg/100 g body weight of cyclophosphamide and were killed 1, 2, 3, 4, 7, 14, 21, and 28 days thereafter. Lung samples were studied by light and electron microscopy. Light microscopy revealed septal and intraalveolar hemorrhages at 2 days and hyaline membranes at 4 days. At 1 to 2 weeks the alveoli were reepithelialized; beyond these intervals there was septal thickening with increased septal cells and interstitial substance. Electron microscopy showed capillary endothelial blebs, membranous pneumocyte injury and sloughing, and severe septal edema at 1 to 2 days. At 4 days some granular pneumocytes appeared altered. At 1 week the alveoli were reepithelialized by prominent granular pneumocytes. Beyond these intervals there was septal thickening with abundant septal cells, debris, collagen, elastin and microfibrils. Some septal elements showed features consistent with "contractile interstitial cells." There was also alveolar collapse indicated by "trapped" granular pneumocytes surrounded by septal cells and fibers. Occasional granular pneumocytes showed large intracytoplasmic cavities. Cyclophosphamide can induce severe injury involving all alveolar components. The partly denuded alveoli are reepithelialized by proliferating granular pneumocytes, thus confirming their importance in alveolar repair. The subsequent development of sclerosing alveolitis suggests that cyclophosphamide may offer a useful experimental model for the study of alveolar injury and repair. The role of the septal "contractile interstitial cells" in the development of septal fibrosis and the possibility that these lesions are reversible remain to be clarified.

Animals↗
PubMed2002

[Cardiovascular pathology of Marfan syndrome].

In Marfan syndrome, mutations of the fibrillin gene lead to various cardiovascular lesions, such as aortic root dilatation, aortic dissection, and floppy mitral or aortic valve. Disorganization and fragmentation of elastic fibers, characteristic histologic findings of cardiac valves and aortas in Marfan syndrome, are similar to the changes of elastic fibers in non-Marfan dissected aortas and idiopathic floppy valves. Immunohistochemical study using antielastin antibody showed even and diffuse staining pattern in finely disrupted elastic fibers, which could result from either immaturity and incomplete cross-linking or proteolytic damage. Ultrastructurally, decrease of the microfibrils and round-shaped expansion of the amorphous components of elastic fibers were observed. These features, resembled those of the elastic fibers in animals treated with inhibitor of lysyl oxidase, suggest the abnormality of elastogenesis in Marfan syndrome. Recently, the changes in the activity of the matrix metalloproteinases are thought to be responsible for the damage to the elastic fibers in Marfan syndrome. However, these changes are also found in the idiopathic floppy valves. Further investigations are necessary to distinguish the pathogenesis between idiopathic cardiovascular disorders and cardiovascular lesions in Marfan syndrome.

Aorta↗
PubMed1975

[The origin and possible role of microvesicles in olfactory receptor cells].

Microvesicles and spherical particles have been described in the bulbs of receptor olfactory cells of Acipenser ruthenus. Two pathways of the origin of the above vesicles have been followed. These structures derive at the stage of differentiation from non-ciliary to ciliary cell type. The first of the pathways involves the autolysis of microfibril bundles produced during the regression of microvilli. The other one includes micropinocytosis induced on the basis of regressing microvilli. Taking into account the genesis of the microvesicles of the receptor cell bulb, it is concluded that they cannot contain a mediator able to modify membrane ion permeability in response to the specific stimulus of the odorant.

Animals↗
PubMed1975

[Development of elastin of human aortas during ontogenesis].

The formation of the elastic fiber was followed up in nine human aortas from foetus or newborn. During this period of ontogenesis an evolution of the elastic residue with increasing age was observed. There was a decrease in the association of structural glycoproteins or microfibrils with elastin. The insolubility of elastin increased with age, together with the increasing crosslinkage of the fiber, characterized by the ratio (sum of desmosines/lysine).

Aorta↗
PubMed2002

In vitro rapid organization of rabbit meniscus fibrochondrocytes into chondro-like tissue structures.

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.

Animals↗
PubMed2000

[Ultrastructure differences of in vitro cotton fiber and native cotton fiber].

Native cotton fiber and in vitro cotton fiber that was induced from cotton ovule callus by suspension culture were observed using transmission electron microscope and scanning electron microscope. The ovule surface on the first day preanthesis was quite smooth. On the anthesis, it had a lot of protuberances. Two kinds of callus, smooth and rough were found. The microfibrils of callus was vertical to the cell long axis and they changed their orientations with the development of the in vitro cotton fiber: from the vertical to shallow spiral and then to parallel to the cell long axis. So was the native cotton fiber. It suggests that in vitro cotton fiber and native cotton fiber have similar development process. Compared with the ovule surface cell, most callus cells had smaller nuclear. During the development of the fiber, the plasm of native cotton fiber was denser than that of in vitro fiber, and it has more cellular organ than in vitro fiber. The cell wall of native cotton fiber was thicker and denser than that of the in vitro cotton fiber too. It suggests that the physiological activity of in vitro cotton fiber was less active than native cotton fiber.

Cotton Fiber↗
PubMed2003

Degeneration of bioprosthetic heart valve cusp and wall tissues is initiated during tissue preparation: an ultrastructural study.

BACKGROUND AND AIM OF THE STUDY: Chronic tissue degeneration is a major factor in the failure of porcine bioprosthetic heart valves. Stabilization with glutaraldehyde (GA) has become the standard in preparation of bioprosthetic heart valves, but there is increasing evidence that GA does not effectively stabilize all tissue structures, specifically glycosaminoglycans (GAGs). The study aim was to establish the status of GAGs in bioprosthetic heart valves and to ascertain whether degeneration of the extracellular matrix (ECM) is initiated during preparation of porcine tissues for use as bioprosthetic heart valves. METHODS: Stentless porcine bioprosthetic heart valves were prepared by tissue harvesting, 24 h of storage in cold saline, and 14 days' fixation in buffered 0.6% GA. Tissue samples obtained from fresh and fixed aortic cusps and wall conduit were analyzed for ECM integrity and GAG localization by transmission electron microscopy combined with toluidine blue staining. RESULTS: Major degenerative changes occurred in the ECM ultrastructure of both porcine cusp and wall during tissue preparation for use as bioprosthetic heart valves. Modifications in the aortic cusp included loss of GAGs from the interfibrillary space and from the surface of the collagen fibers. In the aortic wall, GAGs were lost from the interfibrillary space and from the surface of collagen fibers. In addition, the surface of wall elastic fibers exhibited marked paucity of GAGs and elastin-associated microfibrils. CONCLUSION: The typical steps involved in the preparation of porcine aortic bioprosthetic heart valves induce, or cannot fully prevent, degeneration of some components of the ECM. Controlling the extent of this pre-implantation deterioration will open new gateways for improvement of the quality and durability of future cardiovascular bioprostheses.

Animals↗
PubMed2003

Association between fibrillin-1 gene exon 15 and 27 polymorphisms and risk of mitral valve prolapse.

BACKGROUND AND AIM OF THE STUDY: Fibrillin is one of the structural components of the elastin-associated microfibrils found in the mitral valve. Abnormalities of elastic fiber were found in floppy mitral valves. The role of fibrillin genetic variant in isolated mitral valve prolapse (MVP) has not been studied. Hence, a case-controlled study was performed to investigate the relationship between fibrillin-1 gene polymorphisms and risk of MVP in Taiwan Chinese. METHODS: One hundred patients with MVP diagnosed by echocardiography and 140 age- and sex-matched normal controls were studied. Polymorphisms of exon 15, 27 and intron C of the fibrillin-1 gene (FBN1) were identified by polymerase chain reaction-based restriction analysis. RESULTS: A significant difference was seen in genotype distribution or allelic frequency between MVP cases and controls for either FBN1 exon 15 polymorphism (p = 0.012 and 0.002, respectively) or exon 27 polymorphism (p = 0.04 and 0.02, respectively). Odds ratios (OR) for risk of MVP associated with FBN1 exon 15 TT and exon 27 GG genotypes were 2.40 (95% CI 1.32-4.39) and 3.61 (95% CI 1.01-12.89), respectively. OR for risk of MVP associated with FBN1 exon 15 T and exon 27 G alleles were 2.24 (95% CI 1.32-3.81) and 1.66 (95% CI 1.07-2.56), respectively. There was no significant difference in the distribution of FBN1 intron C genotypes (p = 0.58) and allelic frequency (p = 0.34) between MVP cases and controls. CONCLUSION: Patients with MVP have higher frequencies of FBN1 exon 15 TT and exon 27 GG genotypes, which supports a role of the FBN1 exon 15 and 27 polymorphisms in determining the risk of MVP among the Chinese population in Taiwan.

Adolescent↗
PubMed1992

Scanning electron microscopic study on dendritic cells and fibroblasts in connective tissue.

Perfusion fixation and intravascular resin injection were used to study in situ the cells of superficial fascia (loose connective tissue) of the rat limb by scanning and transmission electron microscopy. These procedures enabled us to differentiate fibroblasts, representative cells of the connective tissue and so-called "dendritic cells," the other cellular constituent of the tissue, known as possible antigen presenting cells. "Dendritic cells" were amoeboid with some spatular processes by which the cells clung to the collagen fiber bundles. The fine structures characteristics of macrophages; they contained abundant primary and secondary lysosomes and expressed factor XIIIa in their cytoplasm. Fibroblasts, on the other hand, were attenuated, sheet-like cells whose edges were juxtaposed closely to collagen and elastic fibers, and were further anchored by microfibrils. The cells were usually interconnected to each other with gap junctions, thus producing a cellular network in the connective tissue.

Animals↗
PubMed1992

[Observation on ultrastructure of sterile cysts of Echinococcus granulosus in mice].

The fine structure of sterile cysts of Echinococcus granulosus in mice was studied by TEM. The cyst wall consists of laminated layer and germinal membrane. At ultrastructural level, the laminated layer contains microfibrillate matrix and irregularly shaped electron-dense granules. The germinal membrane comprise of tegument and cell region. Plasmalemma invagination resembling the "pinocytotic vesicle" are seen between the microtriches of the tegument, and mitochondria are seen in the basal portion of the tegument. In the cell region, there are tegumental cells, muscle cells, and glycogen-containing cells. "Nucleolar channel system" can be observed in some of the glycogen-containing cells.

Animals↗
PubMed1976

[Study of the extracellular macromolecular meshwork elaborated by rat aortic cells in secondary culture].

Rat aortic smooth muscle cells isolated by digestion of the vessels by elastase and trypsin and grown in subculture, are examinated by phase, optic and electron microscopy for their ability to synthesize connective tissue components. Large amounts of extracellular material accumulates within the spaces between the cell; it consists of amorphous substance identified histochemically as elastin, of 110 A microfibrils and of periodic fibrils (430-490 A); the chemical nature of these two last components is discussed.

Animals↗
PubMed1992

Endo-xyloglucan transferase, a novel class of glycosyltransferase that catalyzes transfer of a segment of xyloglucan molecule to another xyloglucan molecule.

Xyloglucans are the major component of plant cell walls and bind tightly to the surface of individual cellulose microfibrils, thereby cross-linking them into a complex polysaccharide network of the cell wall. The cleavage and reconnection of xyloglucan cross-links are considered to play the leading role during chemical processes essential for wall expansion and, therefore, cell growth and differentiation. Although it is hypothesized that some transglycosylation is involved in these chemical processes, the enzyme responsible for the reaction was not identified. We have now purified a novel class of endo-type glycosyltransferase to apparent homogeneity from the extracellular space or the cell wall of the epicotyls of Vigna angularis, a bean plant. The enzyme is a glycoprotein with a molecular mass of about 33 kDa. The enzyme catalyzes both 1) endo-type splitting of a xyloglucan molecule and 2) linking of a newly generated reducing end of the xyloglucan to the nonreducing end of another xyloglucan molecule, thereby mediating the transfer of a large segment of the xyloglucan to another xyloglucan molecule. The transferase exhibits no glycosidase or glycanase activity. Substrate specificity of the enzyme was investigated using several polysaccharides with different glycosidic linkages as donor substrates and pyridylamino oligosaccharides as acceptor substrates, in which the reducing end of the carbohydrate was tagged with a fluorescent group. The enzyme required a basic xyloglucan structure, i.e. a beta-(1-->4)-glucosyl backbone with xylosyl side chains, for both acceptor and donor activity. Galactosyl or fucosyl side chains on the main chain were not required for the acceptor activity. The enzyme exhibited higher reaction rates when xyloglucans with higher M(r) were used as donor substrates. Xyloglucans smaller than 10 kDa were no longer the donor substrate. On the other hand, pyridylamino heptasaccharide acted as a good acceptor as did xyloglucan polymers. Based on these results we propose to designate this novel enzyme a xyloglucan: xyloglucano-transferase, to be abbreviated endo-xyloglucan transferase (EXT) or xyloglucan recombinase. This enzyme is the first enzyme identified that mediates the transfer of a high M(r) segment between polysaccharide molecules to generate chimeric polymers. We conclude that endo-xyloglucan transferase functions as a reconnecting enzyme for xyloglucans and is involved in the interweaving or reconstruction of cell wall matrix, which is responsible for chemical creepage that leads to morphological changes in the cell wall.

Carbohydrate Sequence↗
PubMed1992

Blood-brain barrier and cerebrospinal fluid circulation.

There are two distinctive regions in the central nervous system of all vertebrates: the common brain region possessing the blood-brain barrier, and a group of several brain regions (circumventricular organs (CVOs) including the choroid plexus) devoid of the blood-brain barrier. Of the first, the morphological basis in vertebrates higher than teleosts is the brain-type capillary endothelium, and in elasmobranchs the perivascular astrocytic end-feet sealed by tight junctions. Of the second, the morphological basis is the fenestrated capillary with perivascular space. The pial connective tissue directly continues to the propria of circumventricular organs, and thus offers sites of cerebrospinal fluid drainage through CVO venous capillaries of which the fenestrated endothelia are anchored to perivascular tissues by the microfibrils of elastic fibers. The arachnoid granulations, which increase in size and number in accordance with the increasing volume of the skull are safety balloons against a sudden rise in intracranial pressure. They are possibly also sites of immune responses.

Animals↗
PubMed2003

[Aortic aneurysms excluding Marfan's syndrome].

The causal factors of aneurysm are not the same in the ascending and abdominal aorta. Atheroma is the dominant lesion in the abdominal aorta and genetic abnormalities predisposing to "mediacystic necrosis" are more frequently observed in ascending aortic aneurysms. The causal genetic abnormalities are multiple: abnormalities of fibrillin type I in Marfan's syndrome, collagen abnormalities in the Ehlers-Danlos syndrome, abnormalities of microfibrils, possible metallo-proteases, with many gene candidates. Finally, some ascending aortic aneurysms are associated with bicuspid aortic valves, some of which are familial. Familial factors are less evident in abdominal aortic aneurysms: genes favoring atheroma may be responsible but the factors which predispose to dilatation and non stenosis are not well known: they would seem to be general factors because the tendency to arterial dilatation is diffuse. In all cases, because of the high risk of disease in a close relative, a familial enquiry would seem to be justified with echocardiography for close relatives of affected subjects, especially when young and female.

Aortic Aneurysm↗
PubMed1992

[Cytoskeletal changes in the endothelial cells of the rat aorta in the early periods of postnatal ontogeny].

The cytoskeleton of endothelial cells is a modulator of all the cell reactions. The formation of a definitive structure of the bearing-contracting apparatus of the rat aorta endothelium is finished in the postnatal development (up to the age about 3 months after birth), passing through some qualitative changes. Using the transmission and scanning electron microscopy of detergent extracting preparations, the structuring pattern (saturation) of the aorta endothelial cell cytoskeleton of newborn animals. From 10 days to 1 month after birth, the most important period takes place within peripheral dense microfilament bundles are formed responsible for the cell monolayer integrity for the contractility of cell boundaries (it is most important in recombination of endothelial monolayer in the processes of cell proliferation and vessel growth) and also for the integrity of longitudinal bundles of microfilaments, i.e. fibres of tightening. The increase in anisotropy of cytoskeleton frame during its maturation evidences on the establishment of orientation of microfibril bundles, whose main function being the opposition to haemodynamic loading.

Aging↗