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

In this paper, it is suggested that specificity and non-specificity in (oral) microbial adhesion are different expressions for the same phenomena. It is argued that the same basic, physicochemical forces are responsible for so-called 'non-specific' and 'specific' binding and that from a physico-chemical point of view the distinction between the two is an artificial one. Non-specific interactions arise from Van der Waals and electrostatic forces and hydrogen bonding, and originate from the entire cell. A specific bond consists of a combination of the same type of Van der Waals and electrostatic forces and hydrogen bonding, now originating from highly localized chemical groups, which together form a stereochemical combination. The absence or presence of specific receptor sites on microbial cell surfaces must therefore be reflected in the overall, non-specific surface properties of cells as well. This point is illustrated by showing that glucan-binding lectins on mutans streptococcal strains may determine the pH dependence of the zeta potentials of these cells. When studying microbial adhesion, a non-specific approach may be better suited to explain adhesion to inert substrata, whereas a specific approach may be preferred in case of adhesion to adsorbed protein films. Adhesion is, however, not as important in plaque formation in the human oral cavity as is retention, because low shear force periods, during which adhesion presumably occurs, are followed by high shear force periods, during which adhering cells must withstand these detachment forces. Evidence is provided that such detachment will be through cohesive failure in the pellicle mass, the properties of which are conditioned by the overall, non-specific substratum properties. Therefore, in vivo plaque formation may be more readily explained by a non-specific approach.
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PMID:On the relative importance of specific and non-specific approaches to oral microbial adhesion. 151 60

A burst of endothelial derived oxidants including hydrogen peroxide (H2O2) and superoxide (.O2-) occurs on reperfusion of ischemic tissues that directly causes injury; however, it is not known if this also triggers further injury due to subsequent leukocyte adhesion and adhesion molecule expression. Therefore, studies were performed in an isolated heart model developed to enable study of the role of isolated cellular and humoral factors in the mechanism of postischemic injury. Isolated rat hearts were subjected to 20 min of 37 degrees C-global ischemia followed by reperfusion with polymorphonuclear leukocytes (PMNs) and plasma in the presence or absence of superoxide dismutase (SOD), 200 U/ml, or catalase, 500 U/ml. Measurements of contractile function, coronary flow, high-energy phosphates, free radical generation, and PMN accumulation were performed. Adhesion molecule expression was measured on the surface of effluent PMNs by fluorescence flow cytometry and within the tissue using immunohistochemistry. SOD or catalase treatment resulted in 2- to 3-fold higher recoveries of contractile function, coronary flow, and high energy phosphates. EPR spin trapping measurements demonstrated that SOD totally quenched the free radical generation observed upon reperfusion while catalase prevented the formation of hydroxyl and alkyl radicals derived from superoxide. SOD or catalase treatment decreased PMN accumulation in the reperfused heart and prevented the marked upregulation of CD18 expression seen after reperfusion. These experiments demonstrate that in addition to their direct antioxidative actions, SOD and catalase each decrease PMN adhesion and CD18 expression resulting in marked suppression of PMN-mediated injury in the postischemic heart. Thus, endothelial derived H2O2 and .O2- further amplify postischemic injury by triggering CD18 expression on the surface of PMNs leading to increased PMN adhesion within the heart.
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PMID:Superoxide and hydrogen peroxide induce CD18-mediated adhesion in the postischemic heart. 878 38

Deferoxamine is a potent chelator of ferric iron. Past studies have shown that deferoxamine interferes with acute inflammatory tissue injury in a number of animal models. In cell culture, it inhibits neutrophil-medicated killing of endothelial cells. Both the animal model and cell culture data are thought to reflect the capacity of deferoxamine to interfere with the superoxide anion- and and ferric iron-dependent reduction of hydrogen peroxide to the hydroxyl radical (Fenton Reaction). The present study describes a second mechanism by which deferoxamine may interfere with the acute inflammatory response. Here it is shown that deferoxamine has the capacity to inhibit neutrophil adhesion to lung epithelial cells and vascular endothelial cells. Adhesion of phorbol ester-stimulated neutrophils to both cell types is reduced by 70-80%. The inhibitory effects are reversible and are overcome when ferric iron is present along with deferoxamine in a 2:1 molar ratio. Concentrations of deferoxamine that prevent neutrophil adhesion also prevent neutrophil-mediated killing of the same target cells. In contrast, deferoxamine does not significantly inhibit activation-induced up-regulation of neutrophil surface adhesion structures (CD11b/CD18) and does not prevent binding of a monoclonal antibody that recognizes beta 2 integrins in the high-affinity state. Release of proteolytic enzymes from activated cells is also not significantly inhibited by deferoxamine. Taken together, these data indicate that deferoxamine modulates neutrophil adhesive functions associated with the activated state. The ability of deferoxamine to interfere with neutrophil binding to target cells may contribute to its anti-inflammatory activity.
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PMID:Deferoxamine interferes with adhesive functions of activated human neutrophils. 879 50

The signal transduction pathways that are activated by cytokines and growth factors binding to their receptors on human neutrophils (PMN) are poorly understood. When PMN in suspension encounter many of these agonists they are not activated, but rather are primed for subsequent activation. We and others reported that when PMN are plated onto fibrinogen and stimulated with cytokines or with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) they respond by releasing hydrogen peroxide (H202) and the specific granule component lactoferrin. Transforming growth factor-beta1 (TGF-beta1) is released by many cells including PMN. It has been reported that TGF-beta1 stimulates chemotaxis but not exocytosis or superoxide production by cells in suspension. We hypothesized that TGF-beta1 would activate PMN to release H202 when they were adherent to fibrinogen, a response mediated by beta2++integrin receptors. In this study, we determined whether TGF-beta1 stimulated H202 and lactoferrin release by PMN adherent to fibrinogen. TGF-beta1 stimulated H202 and lactoferrin release from adherent PMN in a concentration-dependent manner, with effects seen in the range of 0.1 to 100 pg/mL. Both H202 and lactoferrin release were detected by 60 min and continued for at least 180 min. Adhesion and spreading of PMN paralleled H202 and lactoferrin release. Ethanol (200 mM) blocked both H202 and lactoferrin release, suggesting the involvement of the phospholipase D pathway. In PMN labeled with lyso-[3H]phosphatidylcholine, we observed that TGF-beta1 treatment caused an increase in [3H]phosphatidate. Propranolol (150 microM), an inhibitor of phosphatidate phosphohydrolase, blocked both H202 and lactoferrin release, suggesting that the conversion of phosphatidic acid to diradylglycerol is an important step in PMN activation by TGF-beta1. Overall, these results are similar to those reported for fMLP activation of adherent PMN and suggest that a common pathway is involved in both chemoattractant and cytokine activation.
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PMID:Transforming growth factor-beta1 stimulates degranulation and oxidant release by adherent human neutrophils. 897 81

Oxidants generated by endothelial xanthine oxidase (XO) can help trigger free radical-mediated tissue injury. An important event in oxidant-mediated tissue injury is neutrophil-endothelial adhesion. Although activation of endothelial XO increases adhesion, little is known about xanthine in the adhesive effect of XO. This study examined administered xanthine on the adhesion of neutrophils. Endothelial [human umbilical vein endothelial cells (HUVEC)] monolayers were exposed to xanthine (15 min), and neutrophils were allowed to adhere to HUVEC in an adhesion assay. Adhesion was dose dependently increased by xanthine (3-100 microM). Either catalase (1,000 U/ml), oxypurinol (XO inhibitor; 100 microM), or platelet-activating factor (PAF) receptor antagonist (WEB 2086; 10 microM) reduced neutrophil adhesion. Superoxide dismutase (1,000 U/ml) had no effect. Pretreatment of HUVEC with 50 microM tungsten also blocked xanthine-induced adherence. Adhesion was also inhibited by preincubation with 100 U/ml heparin. Finally, anti-P-selectin antibody (PB1.3; 20 micrograms/ml) attenuated adhesion. Our results indicate that xanthine may promote neutrophil-endothelial adhesion via a hydrogen peroxide- and PAF-mediated P-selectin expression.
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PMID:Exogenous xanthine promotes neutrophil adherence to cultured endothelial cells. 927 12

Adhesion of microcrystals that nucleate in tubular fluid to the apical surface of renal tubular cells could be a critical step in the formation of kidney stones, 12% of which contain uric acid (UA) either alone or admixed with calcium oxalates or calcium phosphates. UA crystals bind rapidly to monolayer cultures of monkey kidney epithelial cells (BSC-1 line), used to model the surface of the nephron, in a concentration-dependent manner. The urinary glycoproteins osteopontin, nephrocalcin, and Tamm-Horsfall glycoprotein had no effect on binding of UA crystals to the cell surface, whereas other polyanions including specific glycosaminoglycans blocked UA crystal adhesion. Specific polycations also inhibited adhesion of UA crystals and appeared to exert their inhibitory effect by coating cells. However, removal of anionic cell surface molecules with neuraminidase, heparitinase I, or chondroitinase ABC each increased UA crystal binding, and sialic acid-binding lectins had no effect. These observations suggest that hydrogen bonding and hydrophobic interactions play a major role in adhesion of electrostatically neutral UA crystals to renal cells, unlike the interaction of calcium-containing crystals with negatively charged molecules on the apical cell surface via ionic forces. After adhesion to the plasma membrane, subsequent cellular events could contribute to UA crystal retention in the kidney and the development of UA or mixed calcium and UA calculi.
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PMID:Adhesion of uric acid crystals to the surface of renal epithelial cells. 1083 87

During eosinophil (EOS) accumulation at sites of allergic inflammation, an initial step is the binding of EOS to adhesion molecules expressed on vascular endothelial cells (EC). We have previously observed that adhesion of peripheral blood EOS to recombinant human vascular cell adhesion molecule-1 (rh-VCAM-1) stimulates the respiratory burst of EOS. Although the biological consequence of this activation remains to be elucidated, reactive oxygen species such as hydrogen peroxide (H2O2) may modify the adhesive property of EOS. In the present study, we examined whether H2O2 modifies the adhesive property of EOS. EOS were isolated from the peripheral blood of healthy subjects. Adhesion of the EOS to paraformaldehyde-fixed human umbilical vein EC (HUVEC), stimulated or not stimulated with tumour necrosis factor-alpha (TNF-alpha; 100 pM for 24 hr), was examined in the presence or absence of H2O2. H2O2 significantly enhanced adhesion of EOS to both resting and TNF-alpha-stimulated fixed HUVEC (P < 0.01, respectively). Such enhancing effects were inhibited by anti-beta2 integrin antibody or anti-CD11b antibody, but not by anti-CD11a or anti-alpha4 integrin antibody. H2O2 also enhanced EOS adhesion to rh-intracellular cell adhesion molecule-1 (ICAM-1) but not to rh-VCAM-1. Finally, H2O2 enhanced the expression of both CD11b and CD18 on EOS. These results indicate that H2O2 directly augments the adhesive property of EOS through beta2 integrin.
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PMID:Hydrogen peroxide augments eosinophil adhesion via beta2 integrin. 1110 46

We report here on poly(amino acid)-based bioadhesives with potential to bond to soft tissues. The systems investigated included homopolymer poly(amino acids), mixtures of poly(amino acids) and amino acids, and blends of different poly(amino acids). Adhesive performance was tested in tension on glass surfaces, chondroitin sulfate surfaces, as well as bovine cartilage surfaces. The amino acid structural units contained acidic, basic, or polar side chains and were found to adhere reasonably well to the surfaces of glass and chondroitin sulfate. The formation of polymer-monomer complexes with the addition of a basic monomer such as L-lysine to negatively charged polymers such as poly(L-aspartic acid) and poly(L-glutamic acid) was found to result in greater adhesive strength relative to homopolymers. Further improvement in adhesion was observed in blends of poly(L-lysine) with polar poly(amino acids) such as poly(L-asparagine). Adhesion on wet cartilage surfaces was the weakest measured but a priming approach designed to form electrostatic or hydrogen bonds appears promising. We believe the strength of the adhesives studied here is based on the ability of their constituent polymers and monomers to form molecular entanglements and crosslinks for load transfer. We also believe hydrogen bonds and electrostatic forces play a role in the adhesion of the systems to the substrates probed in this work.
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PMID:Poly(amino acid) bioadhesives for tissue repair. 1121 Nov 55

Humans are commonly exposed to combinations of particles (occupational or environmental) and exogenous agents such as ozone and cigarette smoke that generate reactive oxygen species (ROS). Particles also evoke production of ROS from inflammatory cells and of mediators such as TNF-alpha that operate through ROS-related mechanisms. The interactions of particles and ROS-generating agents have been little explored. Adhesion of particles to the surface of pulmonary epithelial cells is increased by exposure to cigarette smoke, ozone, and TNF-alpha. Cigarette smoke and ozone increase the uptake of particles by epithelial cells, and both adhesion and uptake can be decreased by scavengers of ROS. Increased adhesion and uptake probably lead to increased levels of inflammatory and fibrogenic mediator production, and cigarette smoke definitely increases whole lung particle retention and enhances the fibrogenic effects of asbestos. In experimental models, the combination of particles plus ozone, cigarette smoke, or reagent hydrogen peroxide augments the inflammatory response to particles, increases cell proliferation, and leads to liberation of increased levels of chemoattractant mediators as well as vascular mediators such as endothelin. The small airways appear to be particular targets of coexposure to smoke or ozone and particles, a phenomenon that may produce chronic airflow obstruction.
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PMID:Interactions of exogenous or evoked agents and particles: the role of reactive oxygen species. 1272 10

Apatite crystal growth rate and morphology in mineralized tissues are considered to be controlled by surface interaction with extracellular matrix proteins. During enamel maturation where protein is finally removed from crystal surfaces to permit massive crystal growth, pH oscillates between approximately 5.8 and approximately 7.2. With this in mind, a study of enamel apatite surface chemistry in terms of local environmental pH was undertaken. Using atomic force microscopy adhesion force measurements were made between hydroxylated or carboxylated cantilever tips and maturation stage crystals between pH 2 and 10. Adhesion force increased from pH 10 to a maximum at pH 6.6 presumably due to increased hydrogen bonding due to replacement of surface cations (Na, Ca, Mg) with protons and/or protonation of phosphate per se. Below pH 6.6 adhesion force decreased and became very variable indicating that the surface had become unstable probably due to removal of fully protonated phosphate from the surface by adherence to the cantilever tip. Frictional force measurements also revealed 2-3, approximately 30 nm diameter high friction domains in bands across the crystal long axis. Their location mirrored the binding pattern of similarly sized amelogenin aggregates seen in vitro. The data suggests that specific protein binding sites may exist on crystal surfaces and may be released at lower pH by protonation which would lower cationic charge on both crystal surface and ionic charge on the protein. Instability of the crystal surface could also play a role.
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PMID:Surface chemistry of enamel apatite during maturation in relation to pH: implications for protein removal and crystal growth. 1572 Nov 60


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