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At least 217 records · Page 12Linked to original sources
PubMed1990

Titanium-coated micromachined grooves of different dimensions affect epithelial and connective-tissue cells differently in vivo.

A desirable feature of an implant surface which penetrates epithelium would be that the surface impedes epithelial downgrowth. Previous experiments have shown that the micromachined, horizontally oriented grooves on the percutaneous implant surface can impede epithelial downgrowth (Chehroudi et al., J. Biomed. Mater. Res., 22, 459 (1988) and 23, 1067 (1989)). However, little is known of the effect of varying groove parameters such as depth, spacing, and orientation on epithelial downgrowth and attachment of epithelial (E)-cells and fibroblasts (F) to percutaneous implants in vivo. Grooves were produced with a 30-micron pitch and depths of 22 microns, 10 microns, or 3 microns. In addition, 10-microns- and 3-microns-deep grooves were made with pitches of 39 microns and 7 microns, respectively. Implants with grooves oriented either horizontally or vertically to the long axis of the implant as well as smooth control surfaces were coated with 50 nm of titanium and placed in the parietal area of rats for a period of 7 days. Close attachment of E-cells was found on the smooth, 10-microns- and 3-microns-deep, horizontally or vertically aligned grooved surfaces; in contrast, E-cells bridged over the 22-microns-deep, horizontally oriented grooves. F formed a capsule on the smooth surface as well as the 10-microns- and 3-microns-deep horizontally oriented grooves, but F inserted obliquely into the 22-microns-deep, horizontally aligned grooved surface. Histomorphometric measurements indicated that the epithelial downgrowth was greatest on the vertically oriented grooved and smooth surfaces and was shortest on the 22-microns-deep and 10-microns-deep horizontally aligned grooved surfaces. These differences indicate that epithelial downgrowth was accelerated on the vertically oriented grooved surfaces and inhibited on the horizontally oriented grooved surfaces. Moreover, the mechanism of inhibition of the epithelial downgrowth may differ among these surfaces. E-cells bridged over the 22-microns-deep grooves and their migration appeared to be inhibited by the F that inserted into the implant surface. In the shallower horizontal grooves, however, epithelial downgrowth was probably inhibited by contact guidance because there was no evidence of F inserting obliquely into the implant surface.

Animals↗
PubMed1991

Differential binding, biological and biochemical actions of recombinant PDGF AA, AB, and BB molecules on connective tissue cells.

We have compared the biological and biochemical properties of recombinant PDGF AA, AB, and BB using three types of fibroblastic cells: NIH/3T3, human skin fibroblast, and fetal bovine aortic smooth muscle. PDGF binding, receptor autophosphorylation, phosphatidyl inositol hydrolysis, as well as chemotactic and mitogenic responses of the cells were analyzed. PDGF-AB and PDGF-BB showed similar receptor binding, receptor autophosphorylation, and potent biological activity for all three of the cell types tested. In contrast, PDGF-AA was biologically active only for the NIH/3T3 cells in which binding sites for PDGF-AA were abundant, but was inactive for bovine aortic smooth muscle cells and human skin fibroblasts in which binding sites for PDGF-AA were absent. PDGF-AA could not induce any biochemical changes in the human skin fibroblasts or smooth muscle cells. Western blot studies with anti-Type alpha and beta PDGF receptor antibodies indicate that the NIH/3T3 cells contained both PDGF alpha and beta receptors, whereas the human skin fibroblasts and bovine smooth muscle cells contained only detectable levels of beta receptors. These results indicate that cells possessing high levels of PDGF beta receptors only are capable of responding equally well to either PDGF AB or BB.

3T3 Cells↗
PubMed1999

Transcriptional control of the human MCP-2 gene promoter by IFN-gamma and IL-1beta in connective tissue cells.

Human monocyte chemotactic protein-2 (MCP-2) is a member of the CC chemokine family. It is produced by mononuclear leukocytes, diploid fibroblasts, and tumor cells after induction with IL-1beta or IFN-gamma. To understand the transcriptional regulation of the gene, we have analyzed the structure and function of the promoter region. The sequence of the 5'-flanking region was determined and the transcription start site was found to be located at 68 nucleotides upstream of the ATG translation start codon. 5'-Deletion mutants were generated and transfected into E6SM diploid fibroblasts and MG-63 osteosarcoma cells. Expression was measured by luciferase assay in transfected unstimulated cells and after stimulation with IL-1beta, IFN-gamma, or a combination. The region between nucleotides -143 and -73 (relative to the transcription initiation site), containing putative cis-elements for GATA-1, H-APF1, AP-1, and GAS, is important for basal transcription levels in both cell lines. Stimulation for 18 h with IL-1beta alone failed to affect expression of any of the constructs both in diploid fibroblasts and in osteosarcoma cells. In both cell lines IFN-gamma increased the activity of all mutants that possessed the region between -340 and -301. In MG-63 cells, stimulation with the combination of IL-1beta and IFN-gamma caused an additional increase in expression of the constructs from -340 onward. Finally, the presence of transcription factors in nuclear extracts of MG-63 cells and their specificity to bind to various oligonucleotide probes in this [-340; -301] region were evidenced by electromobility shift assays. These results show that IFN-gamma, produced by lymphocytes and NK cells, induces the transcription of the MCP-2 gene in fibroblasts and thereby can indirectly contribute to recruitment of various leukocyte cell types to inflammatory sites.

Base Sequence↗
PubMed1977

Influence of prostaglandins on connective tissue cell growth and function.

Prostaglandins (PGs) are synthesized by cultured fibroblasts. PGs regulate specific cellular functions by influencing cyclic nucleotide levels. PGE1 increases cAMP levels, thus enhancing glycosaminoglycan (GAG) synthesis and reducing proliferation. Exogenous cyclic nucleotides, on the other hand, affect PG formation. Glucocorticoids (GCs) decrease cAMP content, GAG synthesis and PG formation in fibroblasts, the latter effect occurring only after prolonged incubations. The decrease in endogenous PG levels causes a sensitization of the cells to exogenous PGE1, thus counteracting the initial inhibitory effect of GCs on cAMP content and GAG synthesis. Cell proliferation shows an inverse relationship to PG-induced changes in cAMP levels.

Animals↗
PubMed1977

[Interrelationship between the enterochromaffin and several connective tissue cells in the wall of the small intestine following sensitization with an organotropic antigen].

The problem of main cell elements in the intestinal mucosa and their interrelations at different terms of sensibilization (7, 14, 21, days), anaphylactic shock and during post-shock period (3, 7, 14, 21 days) are considered in the work. Some data on quantitative interrelations of enterchromaffine cells, macrophages, labrocytes and plasma cells in the control animals are presented. The amount macrophages under the organotropic sensibilization and during post-shock period increases, their functional activity is growing; the quantity of enterochromaffine cells correlates with that of labrocytes; the amount of plasma cells increases under sensibilization and decreases during the post-shock period.

Anaphylaxis↗
PubMed1988

Dolichos biflorus agglutinin (DBA) reacts selectively with mast cells in human connective tissues.

Dolichos biflorus agglutinin (DBA) binds to N-acetyl-D-galactosamine (GalNAc) residues in glycoconjugates and agglutinates erythrocytes carrying blood group antigen A. In cryostat sections of various tissues from blood group-specified humans, fluorochrome-coupled DBA bound preferentially to fusiform connective tissue cells and to certain epithelial cells. The connective tissue cells were identified as mast cells by their typical metachromasia in consecutive staining with toluidine blue. Double labeling with DBA and conjugated avidin revealed two distinct populations of mast cells. In several tissues the DBA-reactive cells likewise displayed uniform avidin reactivity. In intestinal mucosa, however, morphologically distinct DBA-binding mast cells were found, which were labeled with the avidin conjugates only in specially fixed paraffin sections. DBA did not bind to vascular endothelial cells, which could be identified by double staining with antibodies to factor VIII-related antigen. Labeling with Helix pomatia agglutinin (HPA), another blood group A-reactive lectin, resulted in distinct blood group-dependent fluorescence of the endothelia. Sophora japonica agglutinin (SJA), a blood group B-reactive lectin, labeled vascular endothelial cells in tissues from blood group A, AB, and B donors. HPA and SJA reacted with small mast cells in the gastrointestinal mucosa but failed to label large mast cells in any of the tissues. These results indicate that the blood group reactivity of lectins, as determined by erythroagglutination, is not necessarily consistent with their reactivity with blood group determinants in tissue sections. Moreover, DBA conjugates appear to be a reliable probe for detection of mast cells in various human connective tissues.

Breast↗
PubMed1987

Mutual phenotypic changes between connective tissue type and mucosal mast cells.

Connective tissue mast cells (CTMC) and mucosal mast cells (MMC) are apparently different, but the ontologic relationship between these two types of mast cells was unclear. We investigated the relationship by combining in vivo and in vitro techniques. Although bone marrow-derived mast cells developed in suspension culture resemble MMC, they acquired histochemical, electron microscopical, biochemical and immunological characteristics of CTMC after the transfer into the peritoneal cavity of genetically mast cell-deficient WBB6F1-W/Wv mice. On the other hand, when single peritoneal mast cells (typical CTMC) of WBB6F1-+/+ mice were injected into the stomach wall of WBB6F1-W/Wv mice, CTMC appeared in the muscularis propria and MMC in the mucosa. These results suggest that CTMC and MMC may interchange and that their phenotypes are determined by the anatomical microenvironment in which the final differentiation occurs.

Animals↗
PubMed1988

3T3 fibroblasts induce cloned interleukin 3-dependent mouse mast cells to resemble connective tissue mast cells in granular constituency.

As assessed by ultrastructure, histochemical staining, and T-cell dependency, in vitro-differentiated inter-leukin 3-dependent mouse mast cells are comparable to the mast cells that reside in the gastrointestinal mucosa but not in the skin or the serosal cavity of the mouse. We now demonstrate that when cloned interleukin 3-dependent mast cells are cocultured with mouse skin-derived 3T3 fibroblasts in the presence of WEHI-3 conditioned medium for 28 days, the mast cells acquire the ability to stain with safranin, increase their histamine content approximately equal to 50-fold and their carboxypeptidase A content approximately equal to 100-fold, and augment approximately equal to 45-fold their biosynthesis of proteoglycans bearing 35S-labeled heparin relative to 35S-labeled chondroitin sulfate glycosaminoglycans. Thus, fibroblasts induce interleukin 3-dependent mouse mast cells to change phenotype from mucosal-like to connective tissue-like, indicating that the biochemical and functional characteristics of this mast cell type are strongly influenced by the connective tissue microenvironment.

Animals↗
PubMed2000

Canine extracutaneous mast-cell tumours consisting of connective tissue mast cells.

Two cases of canine extracutaneous mast-cell tumours were encountered, originating from the mucosa of either the oral cavity or the small intestine. The dogs had no neoplasms in the skin. Immunohistochemical and ultrastructural studies demonstrated that the neoplastic cells had the features of connective tissue mast cells. It would seem, therefore, that at least some extracutaneous forms of the neoplasm originate from connective tissue mast cells. Heparin was a useful cytological marker to diagnose this type of mast-cell tumour.

Animals↗
PubMed1984

Electron microscopic comparison of the tunica media of the thoracic aorta between species.

Previous observations indicate that the tunica media of the thoracic aorta of chickens contains two populations of cells (smooth muscle cells and connective tissue cells), whereas that of the mammalian species only contains one cell type (smooth muscle cells). It was considered that this difference in chickens: a) might occur in other avian species; b) might be a common feature in other classes from phylum chordata which are inferior to mammalia; and c) might be a special adaptation for flying animals. In order to test these hypotheses, the cytology of the tunica media of thoracic aorta was studied in five mammals (human, pig, bat, rabbit, and rat), three avian species (chicken, turkey, and pigeon), one reptile (fresh water turtle), and one amphibian (frog). All animals exhibited smooth muscle cells in the tunica media of the aorta, but only the avian species demonstrated the second major cell type (interlamellar connective tissue cells). In the avian aorta the tunica media was composed of alternating layers of smooth muscle cells and fibroblast-like connective tissue cells separated by thick elastic lamellae. It is concluded that the presence of connective tissue cells in the tunica media of the aorta may be a distinctive characteristic of birds.

Animals↗