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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Platelet adhesion to collagen. Factors affecting Mg2(+)-dependent and bivalent-cation-independent adhesion. 211 94

Polycationic polymers have been noted for their effects in promoting cell adhesion to various surfaces, but previous studies have failed to describe a mechanism dealing with this type of adhesion. In the present study, three polycationic polymers (chitosan, poly-L-lysine, and lysozyme) were tested for their effects on microbial hydrophobicity, as determined by adhesion to hydrocarbon and polystyrene. Test strains (Escherichia coli, Candida albicans, and a nonhydrophobic mutant, MR-481, derived from Acinetobacter calcoaceticus RAG-1) were vortexed with hexadecane in the presence of the various polycations, and the extent of adhesion was measured turbidimetrically. Adhesion of all three test strains rose from near zero values to over 90% in the presence of low concentrations of chitosan (125 to 250 micrograms/ml). Adhesion occurred by adsorption of chitosan directly to the cell surface, since E. coli cells preincubated in the presence of the polymer were highly adherent, whereas hexadecane droplets pretreated with chitosan were subsequently unable to bind untreated cells. Inorganic cations (Na+, Mg2+) inhibited the chitosan-mediated adhesion of E. coli to hexadecane, presumably by interfering with the electrostatic interactions responsible for adsorption of the polymer to the bacterial surface. Chitosan similarly promoted E. coli adhesion to polystyrene at concentrations slightly higher than those which mediated adhesion to hexadecane. Poly-L-lysine also promoted microbial adhesion to hexadecane, although at concentrations somewhat higher than those observed for chitosan. In order to study the effect of the cationic protein lysozyme, adhesion was studied at 0 degree C (to prevent enzymatic activity), using n-octane as the test hydrocarbon. Adhesion of E. coli increased by 70% in the presence of 80 micrograms of lysozyme per ml. When the negatively charged carboxylate residues on the E. coli cell surface were substituted for positively charged ammonium groups, the resulting cells became highly hydrophobic, even in the absence of polycations. The observed "hydrophobicity" of the microbial cells in the presence of polycations is thus probably due to a loss of surface electronegativity. The data suggest that enhancement of hydrophobicity by polycationic polymers is a general phenomenon.
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PMID:Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers. 221 2

The effects of added soluble glycosaminoglycans (GAGs) on adhesion and neurite formation by cultured PC12 pheochromocytoma cells on several substrates were tested. PC12 cells adhere more rapidly to Petri plastic coated with fibronectin, laminin, poly-L-lysine, or conA, than to either uncoated Petri plastic or tissue culture plastic. Adhesion to poly-L-lysine, fibronectin- and laminin-coated dishes was significantly inhibited by added dextran sulfate and to a lesser extent heparin--but not by chondroitin sulfate. PC12 adhesion to fibronectin could also be totally inhibited by the putative fibronectin cell binding tetrapeptide L-arginyl-glycyl-L-aspartyl-L-serine (Pierschbacher, MD & Ruoslahti, E, Nature 309 (1984) 30). The inhibitory effects of combinations of this tetrapeptide and heparin or dextran sulfate (but not chondroitin sulfate or hyaluronic acid) were additive. Nerve growth factor (NGF) pretreatment increased the percentage of PC12 cells adherent to all substrates and reduced the GAG inhibition of adhesion. PC12 cells previously treated with NGF to induce morphologic differentiation will rapidly re-extend neurites when plated on all four substrates. On fibronectin and poly-L-lysine-coated dishes this neurite growth is inhibited by added heparin and dextran sulfate, while on laminin it is not. Neurite formation on fibronectin-coated dishes was also inhibited by low concentrations of fibronectin tetrapeptide. In summary, PC12 adhesion and neurite formation can be inhibited by sulfated GAGs on some substrates, including fibronectin, but not other substrates, suggesting that these cells have at least two independent molecular adhesion mechanisms.
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PMID:PC12 adhesion and neurite formation on selected substrates are inhibited by some glycosaminoglycans and a fibronectin-derived tetrapeptide. 394 48

We have measured separation distances between live human red blood cells and simple or modified glass surfaces, using the finite aperture technique of microscope interferometry. In general, separation increases as the ionic strength falls, in isotonic solutions. Restriction on movement parallel to the glass in all except the most dilute salt solutions, coupled with the absence of Brownian motion, indicates direct molecular contact with the substratum. Thus increased separation must be due to swelling of the glycocalyx under electrostatic forces. However, at approximately less than to 2mM adherent cells show a separation greater than 100 nm, execute Brownian motion and the restriction on lateral motion is less evident. This suggests that secondary minimum adhesion by long-range forces with little or no direct molecular connection occurs at extreme dilution only. Treatment of cells with trypsin reduces separation by up to 40 nm, but the extent to which this reflects reduced double-layer repulsion due to loss of surface charge, as opposed to the reduced opportunity for swelling in a trimmed-down glycocalyx, is unclear. Adhesion at a separation approximately 100 nm in 1 mM buffer after trypsinization supports the view that adhesion can occur without very long glycoprotein connections, but does not prove it. Adhesion to unwettable methylated glass and completely wettable unmethylated glass, with an identical ionic strength dependence of the separation, shows that hydrophilicity is not an absolute requirement. Red cells interact closely at all ionic strengths with glass made polycationic with poly-L-lysine, owing to electrostatic attraction. The interference technique also shows that adherent cells can be spaced from the glass by an intervening layer of previously absorbed serum albumin.
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PMID:Conformational response of the glycocalyx to ionic strength and interaction with modified glass surfaces: study of live red cells by interferometry. 663 Mar 5

p130Cas (Cas) has been recently identified as a 130-kDa protein that is highly phosphorylated on tyrosine residues and is stably associated with p47v-crk (v-Crk) and p60v-src (v-Src) oncogene products in cells transformed by the respective genes. Cas is a novel signaling molecule having a single Src homology (SH) 3 domain and a cluster of multiple SH2-binding motifs. While the tight association of Cas with v-Crk and v-Src is strongly suggestive of a significant role in regulating cellular transformation, the function of Cas in normal untransformed cells is totally unknown. We report here that cell adhesion to fibronectin rapidly promotes tyrosine phosphorylation of Cas in human and rat fibroblast cell lines. The response was equally induced by cell adhesion to plates coated with vitronectin, laminin, and collagen but not by cell attachment to nonspecific substrate poly-L-lysine. The kinetic profile of Cas phosphorylation was almost identical with that of tyrosine phosphorylation of focal adhesion kinase pp125FAK (Fak), which is well known to be activated subsequent to integrin-mediated cell adhesion. Adhesion-dependent Cas phosphorylation was completely inhibited by treating cells with cytochalasin D, an agent that disrupts polymerization of actin stress fibers. These results suggest that tyrosine phosphorylation of Cas is stimulated by normal cell adhesion in close association with Fak phosphorylation and the formation of actin stress fibers. In v-Src- or v-Crk-transformed cells, however, the tyrosine phosphorylation of Cas is markedly increased in an adhesion-independent manner that is insensitive to treatment with cytochalasin D. Thus, Cas plays a role in signaling pathways mediated by cell adhesion as well as by transformation. We propose that Cas may amplify and propagate integrin-mediated signals by interacting with SH2-containing molecule(s).
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PMID:Integrin-mediated cell adhesion promotes tyrosine phosphorylation of p130Cas, a Src homology 3-containing molecule having multiple Src homology 2-binding motifs. 754 Oct 40

The adhesiveness of fibroblasts from the human anterior cruciate and medial collateral ligaments to the laminin molecule was studied, with particular emphasis on the intrinsic differences between fibroblasts from the two ligaments. Cellular adhesion strength, adhesion area, laminin concentration, and seeding time were examined. Cell adhesion to laminin anchored with poly-D-lysine to a cleaned cover glass was measured with a micropipette micromanipulation system after seeding. The adhesion strength of fibroblasts from the anterior cruciate ligament to laminin was greater than and significantly different from that of fibroblasts from the medial collateral ligament, depending on the laminin concentration. Fibroblasts from the anterior cruciate ligament also exhibited an increase in adhesion strength, dependent on laminin concentration of as much as 30 micrograms/ml, at which the laminin receptors were thought to be saturated. Fibroblasts from the medial collateral ligament did not show such an increase except at laminin concentrations of 5-10 micrograms/ml. There was no significant difference in adhesion area between fibroblasts from the two ligaments except after 45 minutes at a laminin concentration of 40 micrograms/ml. For both, the adhesion to laminin showed little correlation to seeding time during periods of as long as 60 minutes. Measurements of adhesion area also failed to show a significant correlation to seeding time for fibroblasts from either ligament at laminin concentrations of 20 and 40 micrograms/ml. Adhesion strength normalized by adhesion area had no correlation to seeding time.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adhesiveness of human ligament fibroblasts to laminin. 772 53

Model biomaterial surfaces with well defined chemistry were prepared from close-packed alkyltrichlorosilane monolayers on polished silicon and glass. The outermost molecular groups which come in direct contact with the biological environment were varied across a wide range of oxidation states by employing -CF3, -CH3, -CO2CH3, and -CH2OH terminal functionalities. Characterization by contact angles, surface spectroscopy, and ellipsometry verified that these model surfaces could be repeatedly prepared with good consistency for routine use to study biomolecule adsorption onto model surfaces. Adhesion of canine endothelial cells and the adsorption of proteins (human serum albumin and human fibrinogen) as well as series of synthetic defined oligopeptides to these model surfaces have been studied. Endothelial cells attachment and growth were in the rank order of: -CH2OH > -CO2Me > -CH3 > -CF3. The peptides were comprised of different alternating sequences of lysine, leucine, and tryptophan residues. These structural differences imparted different amphiphilic characters that led to measurable differences in the adsorption of these peptides to liquid-vapor interfaces. The adsorption to model surfaces was studied using ESCA, radiometry, and concentration-dependent contact angles. ESCA and radiometry measured irreversible biomolecules adsorption whereas the contact angle method measured steady-state adsorption. Radiometric results were inconsistent with ESCA, possibly due to artifacts associated with protein radiolabeling.
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PMID:Peptide, protein, and cellular interactions with self-assembled monolayer model surfaces. 811 33

Adhesion of human platelets to collagen under arterial flow conditions mediated by the alpha 2 beta 1 integrin increased tyrosine phosphorylation of several proteins, one of which was the focal adhesion tyrosine kinase, pp125FAK. Tyrosine phosphorylation of pp125FAK did not occur in non-adherent flowing platelets or in platelets attached to poly(L-lysine). Neither adhesion nor tyrosine phosphorylation was affected by pretreatment of platelets with GRGDSP peptide or by anti-alpha IIb beta 3 monoclonal antibody P2. Adherent platelets retained their discoid shape, suggesting that induction of pp125FAK precedes platelet spreading. The tyrosine kinase inhibitor erbstatin decreased tyrosine phosphorylation in non-stimulated platelets and blocked platelet adhesion. These results suggest that pp125FAK plays an important role in platelet adhesion to collagen via the alpha 2 beta 1 integrin.
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PMID:Platelet adhesion to collagen via the alpha 2 beta 1 integrin under arterial flow conditions causes rapid tyrosine phosphorylation of pp125FAK. 828 49

Urokinase-type plasminogen activator (u-PA) or its amino-terminal fragment (ATF) containing the u-PA receptor (u-PAR) binding domain, is known to promote monocyte adhesion. In the present study, U937 monocyte adhesion to a plastic surface was used to investigate the mechanism of its promotion by u-PA and ATF. Adhesion was found to be inhibited by cycloheximide or actinomycin D, implicating protein synthesis and gene expression in u-PA-induced monocyte adhesion. Adhesion was prevented by 2'-deoxyadenosine 3'-monophosphate, indicating that a cAMP-dependent pathway of signal transduction was involved. This concept was supported by the complementary finding that u-PA-induced adhesion was greatly promoted by forskolin, cholera toxin, or 8-bromo-cAMP, which by themselves induced little adhesion. Furthermore, similar to many other cAMP-dependent activities, cGMP diminished u-PA-induced adhesion. When u-PA or ATF was treated with immobilized carboxypeptidase B, its proadhesive effect was abolished, implicating the involvement of carboxyl-terminal lysine residues (Lys158 on u-PA and Lys135 on ATF). Moreover, when a carboxyl-terminal lysine analog was added, the proadhesive effect of carboxypeptidase B-treated u-PA or ATF was restored. In conclusion, the present study indicates that u-PA- or ATF-induced monocyte adhesion involves cAMP-dependent signal transduction, which is triggered by u-PAR binding. It is also critically dependent on the presence of a carboxyl-terminal lysine.
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PMID:Urokinase-type plasminogen activator-induced monocyte adhesion requires a carboxyl-terminal lysine and cAMP-dependent signal transduction. 853 Apr 48

Fluid shear stress modulates vascular function and structure by stimulating mechanosensitive endothelial cell signal events. Cell adhesion, mediated by integrin-matrix interactions, also regulates intracellular signaling by mechanosensitive events. To gain insight into the role of integrin-matrix interactions, we compared tyrosine phosphorylation and extracellular signal-regulated kinase (ERK1/2) activation in adhesion- and shear stress-stimulated human umbilical vein endothelial cells (HUVEC). Adhesion of HUVEC to fibronectin, but not to poly-L-lysine, rapidly activated ERK1/2. Fluid shear stress (12 dyn/cm2) enhanced ERK1/2 activation stimulated by adhesion, suggesting the presence of a separate pathway. Two differences in signal transduction were identified: focal adhesion kinase phosphorylation was increased rapidly by adhesion but not by shear stress; and ERK1/2 activation in response to adhesion was inhibited to a significantly greater extent when actin filaments were disrupted by cytochalasin D. Two similarities in activation of ERK1/2 were observed: protein kinase C (PKC) activity was necessary as shown by complete inhibition when PKC was downregulated; and an herbimycin-sensitive (genistein- and tyrphostin-insensitive) tyrosine kinase was required. c-Src was identified as a candidate tyrosine kinase as it was activated by both shear stress and adhesion. These findings suggest that adhesion and shear stress activate ERK1/2 via a shared pathway that involves an herbimycin-sensitive tyrosine kinase and PKC. In addition, shear stress activates ERK1/2 through another pathway that is partially independent of cytoskeletal integrity.
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PMID:Mitogen-activated protein kinase (ERK1/2) activation by shear stress and adhesion in endothelial cells. Essential role for a herbimycin-sensitive kinase. 895 27


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