Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibrin adhesives have been advocated as a protective seal in colonic anastomosis to prevent leakage. In order to assess the effect of fibrin glue sealing we compared the healing of sutured colonic anastomosis in the rat (group 1) with the addition of human-derived fibrin sealant (group 2). As a control for a possible reaction to foreign protein, in group 3 the sutured anastomosis was sealed with specially prepared rat fibrin adhesive. On days 2, 4 and 7, ten animals in each group were killed. Adhesion formation was scored and the in situ bursting pressure was measured. The collagen concentration and degradation were estimated by measuring hydroxyproline. Adhesion formation was significantly increased in groups 2 and 3 compared with the control group. On days 2 and 7 the bursting pressure was not different between the groups. On day 4 the bursting pressure in groups 2 and 3 was significantly lower than in group 1 (P less than 0.001). These findings correspond with the results of collagen measurements. On day 4 the concentration of hydroxyproline was significantly reduced in groups 2 and 3. Histological examination showed infiltration of neutrophilic granulocytes into the sealant on days 2 and 4; on day 7 the sealant had vanished. From these results it is concluded that fibrin sealing of the colonic anastomosis in the rat does not improve healing, as demonstrated by bursting pressure and hydroxyproline concentration. On the contrary, it seems to have a negative influence.
 ...
PMID:Effect of fibrin sealant on the healing colonic anastomosis in the rat. 187 28

We have examined integrin expression and function in the human colon carcinoma cell line HT29, and in clonal sublines derived from the HT29 line. These cells express several different integrin subunits including beta 1, alpha 2, 3, 6 and alpha v, but do not express the classic alpha 5/beta 1 fibronectin receptor. Clonal variation in the pattern of integrin expression was quite limited. The profile of integrin expression correlates well with the adhesive behavior of HT29 cells. Thus the cells adhere well to vitronectin, laminin and type IV collagen, but not at all to fibronectin. Adhesion to collagen was completely blocked by an anti-beta 1 monoclonal antibody, indicating that beta 1 integrins mediate this process. Adhesion to laminin was strongly blocked by anti-beta 1 monoclonal or anti-beta 6 monoclonal, suggesting that the alpha 6/beta 1 complex functions in attachment to laminin; this was somewhat surprising since immunoprecipitation experiments indicate that most of the alpha 6 subunit seems to be associated with the beta 4 subunit. Despite their strong adherence to laminin, collagen and vitronectin, HT29 cells are not very motile and, in response to gradients of these proteins, do not migrate nearly as well as CHO cells tested under similar conditions. Since HT29 cells can undergo an enterocyte-like differentiation in glucose-free medium, we compared integrin expression in HT29 and its subclones during the process of differentiation. There was no correlation between the state of differentiation, as assessed by expression of brush-border hydrolases, and the level of expression of any of the integrin subunits measured. Thus the pattern of integrin expression in these colonic tumor cells seems to be a characteristic of the cell line, and is not readily modified by changes in cell growth or differentiation.
 ...
PMID:Expression and role of integrins in adhesion of human colonic carcinoma cells to extracellular matrix components. 203 21

Platelet adhesion to collagens immobilized on plastic has been measured, with the following results. (1) Human, but not rabbit, platelets adhered readily to pepsin-extracted monomeric collagens in an Mg2(+)-dependent manner. (2) Rabbit platelets adhered to a monomeric collagen extracted without pepsin by a process that was cation-independent; human platelet adhesion to this collagen exhibited a cation-independent element. (3) Human platelet adhesion to polymeric collagens, including intact native fibres and those reconstituted from pepsin-extracted monomeric collagens, exhibited appreciable cation-independence; adhesion of rabbit platelets to these collagens occurred only by a cation-independent process; pepsin treatment of the intact fibres caused a reduction in cation-independent binding. Two mechanisms of adhesion can therefore be distinguished, one Mg2(+)-dependent, expressed by human, but not rabbit, platelets, the other cation-independent and exhibited by platelets of both species. Mg2(+)-dependent and cation-independent adhesion sites are located within the triple helix of collagen, but the latter sites are only expressed in collagen in polymeric form. In neither case is the helical conformation of the sites essential for their binding activity. Cation-independent adhesion sites are also located in the pepsin-sensitive non-helical telopeptides of collagen and can be expressed in both monomeric and polymeric collagens. Chemical modification of collagen lysine residues indicates that specific lysine residues may be involved in Mg2(+)-dependent adhesion. Adhesion using human citrated platelet-rich plasma is Mg2(+)-independent. Plasma contains factors, conceivably the adhesive proteins fibronectin and von Willebrand factor, that promote the Mg2(+)-independent mechanism.
 ...
PMID:Platelet adhesion to collagen. Factors affecting Mg2(+)-dependent and bivalent-cation-independent adhesion. 211 94

Adhesion durability between dentin pretreated with 10-3 and 4-META/MMA-TBB resin was studied. Reduction of etching periods with 10-3 was not so effective as expected. The weakening of bond strength during immersion in water at 37 degrees C to the dentin pretreated for 1 sec occurred faster than those for either 5 sec or 10 sec. The strength decreased from 12 MPa at 1 day to 9 MPa at 3 months, 3 MPa at 6 months and finally 2 MPa at 1 year in the case of 1 sec pretreated dentin. On the other hand, the strength became half after the storage in water for 1 year in the cases of 5 and 10 sec pretreated dentins. Combination of 10-3 pretreatment and subsequent glutaraldehyde treatment could stabilize the decrease but not completely. SEM and TEM examinations suggested that dentinal collagen exposed by the etching but not entangled and impregnated by poly (4-META-co-MMA) easily deteriorated by water during the longer immersion. Collagen modified with 10-3 and then with glutaraldehyde was also changed by the longer immersion.
 ...
PMID:[Durability of bonding between 4-META/MMA-TBB resin to dentin pretreated with 10-3. The effect of 10-3 pretreating period and subsequent glutaraldehyde treatment]. 213 46

C1q binds through its collagen-like domain to specific surface receptors of fibroblasts and to adhesive elements of extracellular matrix including fibronectin, collagens, proteoglycans, and laminin. To determine whether C1q participates in fibroblast adhesion, cells in serum-free medium were plated on surfaces coated with purified C1q at physiologic ionic strength and pH. Surfaces coated with fibronectin or collagen type I served as positive controls, and those coated with BSA were negative controls. Substratum-adsorbed C1q promoted fibroblast adhesion to a maximum of 73% of available cells within 90 min at 37 degrees C. Adhesion was C1q concentration dependent, saturable, specific, and dependent on the collagen-like domain of the molecule. De novo protein synthesis plays a role in adhesion: pretreatment of fibroblasts with cycloheximide reduced adherence about 50% of controls. Addition of exogenous fibronectin, collagen type I, or C1q as soluble mediators did not affect adhesion of the cycloheximide-treated cells to C1q substrate. Adhesion could be accounted for primarily, although not completely, by the C1q receptors. Antibodies raised against the Raji cell C1q receptors (alpha C1qR Ab) specifically inhibited fibroblast adhesion to C1q substrates about 60% of controls. The binding of fibroblasts to C1q substrates could be inhibited about 24% of controls with the GRGDTP cell recognition peptide. GRGDTP and alpha C1q Ab had an additive effect on adhesion that was inhibited 77 to 80% of controls. We conclude from these data that aggregated rather than monomeric C1q may be the natural ligand of the fibroblast C1q receptor, and the biologic function of the receptor in cells of the connective tissue may be cell adhesion.
 ...
PMID:Participation of C1q and its receptor in adherence of human diploid fibroblast. 221 51

Following fragmentation of the collagen molecule with cyanogen bromide (CB), two major platelet-aggregatory sites were detected with human platelets in the alpha 1(I)-chain of human collagen I corresponding to those detected previously in bovine alpha 1(I)-chains. Two main sites were also detected in the human alpha 1(III)-chain, at locations different from those in the alpha 1(I)-chain. Only one of these had been previously recognised. The new site was found in the peptide alpha 1(III)CB3, the amino acid sequence of which does not contain the cell-recognition site RGD nor comparable sequences that might be supposed to serve this function such as KGD, RGE or KGE. The peptide does, however, contain the sequence GRPGRPGER which reflects a spacing of basic residues (at positions 2 and 9) we have previously postulated to be essential for collagen to cause platelet aggregation. None of the CB-derived peptides was able to cause an aggregation of rabbit platelets. Human platelet secretion, as aggregation, was only induced by CB-derived fragments in triple-helical, polymeric form. One fragment, peptide alpha 1(III)CB8, was able to induce secretion although lacking aggregatory activity. Platelet adhesion occurred to all of the fragments, including those lacking aggregatory activity. Adhesion also occurred to the collagen-like polypeptide (PGP) n. However, inhibition studies suggested that the GPP sequence which occurs frequently along the length of the collagen molecule is not responsible for platelet adhesion to collagen.
 ...
PMID:Platelet-reactive sites in human collagens I and III: evidence for cell-recognition sites in collagen unrelated to RGD and like sequences. 223 27

In vitro assays using endothelial cells (EC, bovine corneal) were performed to study adhesion and spreading on collagen types I and IV. Adhesion was quantitatively analyzed by counting the EC under a light microscope. Spreading was determined by measuring cell area using a scanning electron microscope (SEM). Collagen types I, IV, and IV-F, a mixture of 70, 120, and 140 KD fragments of type IV, all promoted EC adhesion, Types IV and IV-F showed evidence of giving a more marked adhesion than type I. A study of cell area, carried out under identical conditions, such as those in the adhesion assay, showed that types I and IV-F, but not type IV, promoted cell spreading. This provides evidence that cell adhesion and spreading are indeed separate biological phenomena. Furthermore, the ability of fragments of type IV collagen to promote both cell adhesion and spreading may represent an inherent repair mechanism in damaged endothelium.
 ...
PMID:Adhesion and spreading of corneal endothelial cells on collagens type I and IV in vitro: a model to study mechanisms of endothelial repair. 236 45

A method was developed to study the adhesion of platelets to fibrillar collagen at 37 degrees C in the absence of aggregation. Human platelets were labeled with [3H]-oleic acid, gel-filtered, and incubated with collagen in the presence of receptor antagonists to thromboxane A2, 5-hydroxytryptamine, and platelet-activating factor, as well as a fibrinogen/fibronectin inhibitor and an ADP-removing system. Those platelets that adhered to collagen were separated from those that did not by filtration through a 10-microns nylon mesh and the extent of platelet adhesion was quantitated by determination of the radioactivity retained by the mesh. The extent of platelet adhesion was proportional to the amount of collagen added up to 100 micrograms/ml and was essentially complete by 1 min. At least 80-90% of the platelets were capable of adhering to collagen. Adhesion was potentiated by the presence of extracellular Mg2+ and this potentiation was inhibited by extracellular Ca2+. Phosphatidic acid increased markedly in those platelets that adhered to collagen and this was associated with increases in cytosolic free Ca2+ levels that could be detected using the fluorescent Ca2+ indicator fura-2.
 ...
PMID:Determination of platelet adhesion to collagen and the associated formation of phosphatidic acid and calcium mobilization. 237 14

We recently described specific binding sites for Clq on human blood platelets that cross-react with antibodies against Clq receptors (ClqR) on lymphoblastoid cells. Inasmuch as Clq inhibits collagen-induced platelet aggregation, we compared the effects of ClqR occupancy by purified Clq, monoclonal (IIl/B5) and polyclonal anti-ClqR antibodies on collagen-induced platelet adhesion, release, and aggregation. Washed platelets in buffered Tyrode's solution containing 2 mM magnesium were preincubated (30 min, 22 degrees C) with antibodies, Clq, or appropriate control buffers and antiserum. Platelet aggregation and release measurements were made using 14C-serotonin-labeled platelets stimulated with type I collagen. Adhesion assays were performed in the presence of magnesium under static conditions at 22 degrees C with 51Cr-labeled platelets and collagen-coated microtiter wells. Concentrations of IIl/B5, polyclonal anti-Clq R antiserum, or Clq causing 82 to 92% (n = 7) inhibition of collagen-induced release and 67 to 98% inhibition of aggregation, failed to inhibit magnesium-dependent platelet adhesion to collagen. Inasmuch as divalent cation-independent platelet-collagen interactions have also been described, further studies were performed to compare the divalent cation requirement of ClqR occupancy by Clq and inhibition of platelet-collagen interactions. Whereas, Clq binding to platelets was divalent cation independent, neither Clq nor anti-ClqR antibodies prevented platelet adhesion to collagen in the presence of EDTA. These data suggest that under defined in vitro conditions, ClqR modulate collagen-induced platelet aggregation and secretion, but not platelet adhesion.
 ...
PMID:Modulation of platelet responses to collagen by Clq receptors. 240 63

Adhesion-defective EC cells were isolated from a population of mutagenized F9 cells by serial transfer of cells that did not adhere to gelatin-coated dishes. The variant cells grew in suspension as multicellular clusters of loosely aggregated cells. The cells adhered to, but did not flatten on, fibroblast monolayers and extracellular matrix produced by parietal-like endoderm. Two different mutant cell lines exhibited increased sensitivity to the lectin abrin and decreased sensitivity to wheat germ agglutinin, suggesting that changes in cell surface glycosylation are associated with the mutant phenotype. These adhesion-defective mutants were used to study the relationship between cell-cell adhesion and endodermal differentiation. Unlike wild-type cells, when cultured with low concentrations of retinoic acid (RA) in suspension culture, the mutant cells did not form embryoid bodies but remained as loosely adhering strings of cells. Electron microscopic examination revealed that most of the differentiated variant cells resembled parietal endoderm, and this was confirmed by immunofluorescent staining for TROMA-3 marker. The levels of some of the markers that characterize the differentiative pathways were examined by immunoprecipitation and by enzyme-linked immunosorbent assay (ELISA). The variant line produced higher levels of laminin and type IV collagen compared to the wild-type cells. alpha-Fetoprotein (AFP) was produced at a significantly lower level by the variant compared to wild-type F9 cells during the differentiative process. The results show that variant cells differentiated toward parietal endoderm but have a very much restricted ability to differentiate to visceral endoderm. We conclude that aggregation and/or compaction provide some essential signals during the differentiation of F9 cells into epithelial layers of visceral endoderm.
 ...
PMID:An adhesion-defective variant of F9 embryonal carcinoma cells fails to differentiate into visceral endoderm. 243 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>