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PubMed1981

[Studies of dental methacrylic resin. (Part 8) Flexural and impact adhesive strength of self-curing methacrylic resin to cross-linked polymethyl methacrylate resins (author's transl)].

Heat-curing methacylic resins cross-linked with three kinds of dimethacrylates, i.e. EDMA, tri-EDMA and nona-EDMA, were prepared, and the flexural and the impact adhesive strength of the dough moulding type and the pour type self-curing methacrylic resins to them were examined. The results obtained were as follows. (1) The flexural and the impact adhesive strength of the pour type self-curing resin were higher and more stable than those of the dough moulding type one. (2) The flexural and the impact adhesive strength of self-curing resins to cross-linked adherent resins rised in order of nona-EDMA greater than tri-EDMA greater than EDMA in the range of higher concentration of cross-linking agents. This tendency was marked for the pour type resin. (3) When the dough moulding type resin was used as adhesive resin, to adherent resin cross-linked with EDMA or tri-EDMA which had relatively short chain, the respective adhesive strength of that decreased with increasing the concentration of cross-linking agent. While, to adherent resin cross-linked with nona-EDMA, which had relatively long and more flexible chain, the respective adhesive strength of the dough moulding type resin increased with increasing the concentration of cross-linking agent. (4) When the pour type resin was used as adhesive resin, to adherent resin cross-linked with EDMA or tri-EDMA, the respective adhesive strength of that showed the maximum at the concentration near 2 to 5 mole% and decreased with increasing the concentration. While, to adherent resin cross-linked with nona-EDMA, the flexural adhesive strength of the pour type resin was approximately constant without the effect of the concentration, but the impact adhesive strength of that increased with increasing the concentration. (5) The flexural adhesive strength of the dough moulding and the pour type resin under the wet condition decreased about 30 to 60% compared with under the dry condition, but the percentage of the falling for the impact adhesive strength was about 15 to 30% and relatively small. (6) The flexural adhesive strength showed a similar adhesive tendency to the tensile adhesive strength, but the impact adhesive strength showed a different adhesive tendency from those.

Adhesiveness↗
PubMed1994

Stem cell factor induces mast cell adhesion to fibronectin.

Stem cell factor (SCF) or c-kit ligand is a growth factor cytokine produced by stromal cells that is known to influence mast cell proliferation and differentiation. We hypothesized that SCF may also influence the adhesion of mast cells to connective tissue matrix. To examine this hypothesis, we stimulated MCP5/L mast cells or murine bone marrow-derived cultured mast cells (BMCMC) with either SCF or PMA and observed adhesion to fibronectin (FN). As expected, 80 to 90% of PMA-activated MCP5/L cells or BMCMC adhered to FN. In addition, SCF promoted MCP5/L cell or BMCMC adhesion to FN in a dose-response fashion with 50 to 60% of BMCMC adhering to FN at a concentration 10 ng/ml of SCF. BMCMC adhesion was observed with as little as 200 pg/ml of SCF. Adhesion of SCF stimulated BMCMC to FN did not require IL-3, but was dependent on the concentration of FN used to coat the assay surface. Mast cell adhesion in the presence of SCF appeared to occur through an integrin receptor as adhesion was calcium dependent and could be blocked by an RGD (Ang, Gly, Asp)-containing peptide. SCF did not directly mediate adhesion through interaction with c-kit, as FN-coated surfaces exposed to SCF before initiation of the adhesion assay did not promote adhesion in the absence of soluble SCF. Rather, SCF appeared to stimulate adhesion to FN by activating mast cells through its interaction with c-kit. Thus, antibody to SCF blocked adhesion, and rat and murine SCF stimulated BMCMC adhesion to FN, but human SCF, which does not bind to murine c-kit, did not stimulate adhesion. Genistein, which inhibits tyrosine kinase activity, partially inhibited SCF-induced adhesion. SCF thus stimulates mast cell adhesion and, because SCF is produced normally in tissues, it may be a major factor responsible for the adhesion of mast cells to connective tissue matrix under physiologic conditions.

Amino Acid Sequence↗
PubMed1997

Circulating endothelial cell adhesion molecules as diagnostic markers for the early identification of pregnant women at risk for development of preeclampsia.

OBJECTIVE: The aim of the current study was to determine levels of circulating endothelial cell adhesion molecules during preeclampsia and to assess their predictive value as diagnostic markers for the early identification of pregnant women at risk of developing preeclampsia. STUDY DESIGN: Plasma samples were obtained from women with preeclampsia; the syndrome of hemolysis, elevated liver enzymes, and low platelets; uncomplicated pregnancy-induced hypertension; and women with normal pregnancy. In addition, longitudinal plasma profiles of pregnant women were randomly collected to determine individual profiles of circulating endothelial cell adhesion molecules. A sandwich enzyme-linked immunosorbent assay technique was used to quantitate concentrations of soluble intercellular adhesion molecule-1 (CD54), vascular cell adhesion molecule-1 (CD106), E-selectin (CD62E), platelet endothelial cell adhesion molecule (CD31), and P-selectin (CD62P). RESULTS: Plasma levels of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, and platelet endothelial cell adhesion molecule-1 were significantly elevated in women with preeclampsia compared with healthy control pregnant women. Longitudinal analysis of soluble plasma intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels during pregnancy revealed that these molecules (1) show little variation in healthy pregnant women, (2) do not vary during normal pregnancy, and (3) are significantly elevated in women with preeclampsia and the syndrome of hemolysis, elevated liver enzymes, and low platelets compared with control pregnant women and those with uncomplicated pregnancy-induced hypertension. Analysis of soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels in longitudinal profiles of pregnant women identified significantly elevated levels of these molecules in the plasma of preeclampsia-prone women 3 to 15 weeks before the onset of clinical symptoms. CONCLUSION: Elevated soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 measurements during pregnancy can be considered as major risk factors. Elevated levels of these substances in the plasma of pregnant women with preeclampsia support the concept of a primary endothelial cell involvement in the pathogenesis of preeclampsia. Although currently based on a limited database, significantly elevated levels of soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the plasma of otherwise healthy pregnant women suggest a very high predictive value of these molecules for the earliest identification of women at risk of developing preeclampsia.

Biomarkers↗
PubMed1991

Transmembrane signals generated through MHC class II, CD19, CD20, CD39, and CD40 antigens induce LFA-1-dependent and independent adhesion in human B cells through a tyrosine kinase-dependent pathway.

Transmembrane signals generated following mAb binding to CD19, CD20, CD39, CD40, CD43, Leu-13 Ag, and HLA-D region gene products induced rapid and strong homotypic adhesion in a panel of human B cell lines. Lower levels of adhesion were also observed after engagement of CD21, CD22, and CD23. Adhesion induced by mAb binding to these Ag was identical with respect to the kinetics of adhesion and the morphology of the resulting cellular aggregates, and was distinct from PMA-induced adhesion in both of these properties. Adhesion was not observed in response to mAb binding to MHC class I, CD24, CD38, CD44, CD45RA, or CD72. In contrast to B cell lines, homotypic adhesion was not induced in two pre-B cell lines, in spite of their high level expression of CD19 and HLA-D. Adhesion induced by suboptimal stimulation through these surface Ag or by PMA was mediated primarily through LFA-1 and ICAM-1. However, optimal stimulation through CD19, CD20, CD39, CD40, and HLA-D induced strong homotypic adhesion that was not blocked by anti-LFA-1 mAb. This alternate pathway of adhesion was also observed in LFA-1-deficient cell lines and in the presence of EDTA, suggesting that adhesion was not mediated by integrins. Adhesion in response to engagement of cell-surface Ag was unaffected by H7 or genestein, but was significantly inhibited by staurosporine, and was completely ablated by sphingosine and herbimycin. These studies indicate that engagement of multiple B cell-surface molecules initiates a signal transduction cascade that involves tyrosine kinases but not protein kinase C, and which leads to homotypic adhesion. Furthermore, adhesion was mediated by at least two distinct cell-surface adhesion receptors: LFA-1/ICAM-1 and a heretofore unknown adhesion receptor.

Adenosine Triphosphatases↗
PubMed2002

Effects of plasma treated PET and PTFE on expression of adhesion molecules by human endothelial cells in vitro.

The aim of this study was to evaluate the expression of adhesion molecules on the surface of human endothelial cells in response to the systematic variation in materials properties by the ammonia plasma modification of polyethylene terephthalate (PET) and polytetrafluorethylene (PTFE). These adhesion molecules act as mediators of cell adhesion, play a role in the modulation of cell adhesion on biomaterials and therefore condition the response of tissues to implants. First and second passage human umbilical vein endothelial cells (HUVECs) were cultured on plasma treated and untreated PET and PTFE. HUVECs grown on polystyrene tissue culture coverslips and HUVECs stimulated with tumour necrosis factor (TNF-alpha) were used as controls. After 1 day and 7 days, the expression of adhesion molecules platelet endothelial cell adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), Integrin alphavbeta3, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, P-selectin and L-selectin were evaluated using flow cytometry and immunohistochemistry. There was a slight increase in positive cell numbers expressing the adhesion molecules ICAM-1 and VCAM-1 on plasma treated PET and PTFE. A significant increase in E-selectin positive cells on untreated PTFE was demonstrated after 7 days. Stimulation with TNF-alpha demonstrated a significant increase in the proportion of ICAM-1. VCAM-1 and E-selectin positive cells. Almost all cells expressed PECAM-1 and integrin alphavbeta3, on both materials and controls but did not express P- and L-selectin on any surface. When second passage cells were used, the expression of the adhesion molecules ICAM-1 and VCAM-1 was markedly increased on all surfaces but not with TNF-alpha. These significant differences were not observed in other adhesion molecules. These results were supported by immunohistochemical studies. The effects of plasma treated PET and PTFE on cell adhesion and proliferation was also studied. There was a 1.3-fold increase in cell numbers adhered on ammonia plasma treated PET compared to untreated PET and a 5.5-fold increase in cell numbers on treated PTFE compared to untreated PTFE after 1 day. This is significantly different when analysed statistically. After 7 days, cell number increased significantly on all surfaces compared to 1 day, except for untreated PTFE which conversely reduced by 41%. Cell number on the surface of untreated PET was no different to treated PET on days 1 and 7 when second passage cells were used. The study has shown that the plasma treatment of PET and PTFE with ammonia improves the adhesion and growth of endothelial cells and slightly upregulates the expression of adhesion molecules. This surface modification should promote colonisation of an artificial vascular prosthesis by endothelial cells and make it less vulnerable to immune system cells of the recipient. In addition, it should be considered which passage of cells is used due to the different adhesion features of different passages of HUVECs on untreated PET.

Biocompatible Materials↗
PubMed2003

Microtensile bond strengths of one- and two-step self-etch adhesives to bur-cut enamel and dentin.

PURPOSE: To evaluate the bonding effectiveness of one- and two-step self-etch adhesives in comparison with a total-etch approach. METHODS: From 55 non-carious human third molars, mid-coronal dentin and enamel bur-cut surfaces were prepared. The bonding surfaces were treated strictly following the manufacturers' instructions with three one-step self-etch (all-in-one) adhesives, AQ bond, Reactmer and Xeno CF Bond; two two-step self-etch adhesives, experimental ABF and Clearfil SE Bond, one two-step total-etch adhesive, Prime & Bond NT, and one three-step total-etch adhesive, OptiBond FL. Composite built-ups were made using Z100. After storage overnight in 37 degrees C water, the bonded specimens were sectioned into rectangular slabs of approximately 2x2 mm width and 9 mm length. They were then trimmed into a round cross-sectional shape resulting in an interface area of approximately 1 mm2, and subsequently subjected to microtensile bond strength (microTBS) testing with a cross-head speed of 1 mm/minute. Differences in microTBS were determined for enamel and dentin using the Kruskal-Wallis test at P < 0.05. RESULTS: The microTBS to enamel varied from 10.3 MPa for the one-step self-etch adhesive AQ bond to 49.5 MPa for the total-etch adhesive Prime & Bond NT. The microTBS to dentin varied from 15.5 MPa for the one-step self-etch adhesive Reactmer to 59.6 for the three-step total-etch adhesive OptiBond FL. The microTBS of the total-etch adhesives to enamel was significantly higher than that of the one-step self-etch adhesives. Comparing the dentin microTBS, only OptiBond FL performed significantly better than the one-step self-etch adhesives. Specimen failure during preparation occurred with each one-step adhesive, but more frequently when bonding to enamel than to dentin. Most one-step self-etch adhesives failed predominantly adhesively between the tooth substrate and the bonding layer in contrast to the two- and three-step adhesives that revealed generally more mixed adhesive-cohesive failures.

Acid Etching, Dental↗
PubMed2006

Extracellular pressure stimulates tumor cell adhesion in vitro by paxillin activation.

Metastasizing colon cancer cells bind target tissues primarily via integrins. Extracellular pressure or shear stress stimulates integrin-mediated adhesion to matrix proteins or endothelial cells by activating the focal adhesion proteins FAK and Src. Because this effect is blocked by cytoskeletal perturbation and paxillin may link the cytoskeleton to the focal adhesion complex, we evaluated the role of paxillin in pressure-induced malignant colonocyte adhesion. We studied SW620 colon cancer cells and confirmed key results in Caco-2 colon cancer cells, primary human colon cancer cells, and a murine colonic adenocarcinoma. We evaluated adhesion to collagen at ambient and 15 mmHg increased pressure after 30 minutes, and paxillin, FAK, and Src phosphorylation in suspended cells prior to adhesion. Some cells were treated with siRNA to paxillin or FAK, or the Src inhibitor PP2. We also compared pressure-induced signals in suspended cells with adhesion-induced signals after adhesion to collagen. Pressure stimulated adhesion and paxillin phosphorylation in SW620 and Caco-2 cells and human primary colon cancer cells. Pressure also increased paxillin phosphorylation in murine carcinoma cells. SiRNA to paxillin decreased SW620 and Caco-2 paxillin without altering basal levels of phosphorylated paxillin. Paxillin reduction decreased basal adhesion to collagen, and inhibited pressure-stimulated adhesion, as well as paxillin, FAK397, FAK576, and Src476 phosphorylation. Neither PP2 nor siRNA to FAK inhibited induction of paxillin phosphorylation by pressure. In contrast, adhesion stimulated FAK, Src, and paxillin phosphorylation regardless of paxillin reduction. In summary, pressure induced paxillin phosphorylation in colon cancer cells. Paxillin reduction inhibited basal adhesion and blocked the pressure-mediated increase in adhesion, as well as pressure-induced FAK and Src signals, while adhesion-induced signals were preserved. Paxillin may be an upstream mediator of pressure-stimulated adhesion, important in metastasis.

Adenocarcinoma↗
PubMed1986

Neurite extension across regions of low cell-substratum adhesivity: implications for the guidepost hypothesis of axonal pathfinding.

According to the adhesive "guidepost" hypothesis, pioneer axons follow pathways marked by specific nonadjacent cells (guidepost cells). The hypothesis implies that high adhesivity between extending axons and guidepost cells facilitates axon extension across low-adhesivity tissues or spaces between guidepost cells. This study investigates the ability of a high-adhesivity substratum to promote axonal extension across a low-adhesivity substratum in vitro. Dissociated chick embryo dorsal root ganglion neurons are cultured on a substratum consisting of areas of high-adhesivity substratum-bound laminin (i.e., model adhesive guideposts) separated by a low-adhesivity agarose substratum. Increasing the cell-substratum adhesivity of these guideposts results in an increase in the percentage of neurites spanning a given width of the low-adhesivity substratum. Filopodial processes at the tips of neurites can extend over the low-adhesivity substratum. Apparently, filopodial contact with high-adhesivity guideposts enables neurites to extend across intervening low-adhesivity substrata. The maximum width of low-adhesivity substratum discontinuities spanned by some neurites in vitro is comparable to the distance between some putative guidepost cells in insects. Consistent with the adhesive guidepost hypothesis, these findings demonstrate neurite extension on a substratum of discontinuous cell-substratum adhesivity.

Albumins↗
PubMed1987

LFA-1 and other accessory molecules functioning in adhesions of T and B lymphocytes.

Adhesions of lymphocytes, among themselves or with other cell types, are necessary for most steps in immune responses including both induction and effector phases. Among adhesions of T cells involving specific immunological recognition, CTL-target adhesions have been the most studied. Although CTL-mediated killing is highly specific (specific/nonspecific lytic activity 50-fold), CTL-target adhesion (conjugation) is less so. In the mouse, specificity of conjugation has typically been four to eightfold. Two recent studies with cloned human CTL found much less specificity of conjugation, from one-fold (no specificity) to 1.5-fold. Thus, with cloned human CTL, adhesion may occur promiscuously with any potential target; recognition following adhesion is necessary for lethal hit delivery. The fact that antibodies to the antigen receptor (Ti or CD3) inhibit killing without inhibiting CTL-target conjugation supports this view. The ability of lymphocytes to form nonspecific adhesions, plus the dependence of even the specific mouse adhesions on temperature, metabolic energy, magnesium, and an intact cytoskeleton suggest that the bulk of the strength of T lymphocyte adhesions are not simply the sum of the bonds between antigen receptors (Ti) and antigen. Lymphocytes evidently possess separate "adhesion strengthening" mechanisms. The similarities in the properties of CTL-target adhesions and antigen-independent homotypic B lymphocyte adhesions (Table 2) suggest that at least some of these mechanisms are widely used among cells of hematopoietic origin. MoAbs to most lymphocyte surface molecules, when bound to the living lymphocyte membrane, have no evident functional effects on lymphocyte function. However, a minority can either activate or inhibit lymphocyte functions. Such antibodies identify "leukocyte (or lymphocyte) function-associated antigens," or LFAs (not all of which happen to have "LFA" in their names, Table 1). Most of the inhibitory antibodies inhibit lymphocyte adhesions, and this appears to account for their inhibitory effects on functions such as killing or proliferation. The fact that the binding of antibodies to a particular membrane glycoprotein inhibits adhesion does not guarantee that the glycoprotein in question is a direct participant in adhesion (one of the "glue" molecules). However, there is scanty evidence in support of indirect "negative signals" that may be induced by such antibodies, and direct participation of most LFAs in adhesion seems likely.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, Differentiation, T-Lymphocyte↗
PubMed1992

Expression of adhesion molecules by bladder cancer cells: modulation by interferon-gamma and tumour necrosis factor-alpha.

The constitutive expression by eight human bladder cancer cell lines of the cell adhesion molecules intercellular adhesion molecule-1 and intercellular adhesion molecule-2 was studied using monoclonal antibody probes in conjunction with flow-cytometry. Tumour lines of low grade (G1) did not constitutively express intercellular adhesion molecule-1, rather they were found to express intercellular adhesion molecule-2. The G2 cells expressed no intercellular adhesion molecule-2, however, a low percentage did express intercellular adhesion molecule-1. High grade cells (G3) only expressed intercellular adhesion molecule-1 on their cell surface but at higher levels than the G2 cell line. Exposure of the bladder cancer cell lines to interferon-gamma induced and augmented the expression of intercellular adhesion molecule-1 by all except one of the cell lines (UMUC3). Intercellular adhesion molecule-2 expression remained unaltered. The modulation of intercellular adhesion molecule-1 expression was dependent on the concentration of interferon-gamma and the duration of stimulus. De novo intercellular adhesion molecule-1 expression, induced by interferon-gamma, was rapid (< 4 hours) with only a short period of stimulation being required (< 10 seconds). The rapid increase in expression of intercellular adhesion molecule-1 required de novo protein synthesis and was not the result of release of intercellular adhesion molecule-1 from an intracellular pool. Interferon-gamma and tumour necrosis factor-alpha were found to act synergistically in the induction and augmentation of intercellular adhesion molecule-1 expression. Optimal induction occurred with 10 Uml-1 of both molecules. These results suggest a correlation between constitutive adhesion molecule expression and the histopathological grade of the tumour. The implications of these findings for Bacillus Calmette Guerin and interferon-gamma immunotherapy of bladder cancer is discussed.

Carcinoma, Transitional Cell↗
PubMed1998

A study of nerve fibers and histopathology of postsurgical, postinfectious, and endometriosis-related adhesions.

OBJECTIVE: To evaluate the presence of nerve fibers and histopathology of endometriosis-related adhesions, postsurgical adhesions, and postinfectious adhesions in women with and without pelvic pain. METHODS: We evaluated the presence of nerve fibers and histopathology of endometriosis-related adhesions, postsurgical adhesions, and postinfectious adhesions in 50 women. The nerve fibers were identified by immunocytochemistry staining with an antibody to neurofilament. RESULTS: Nerve fibers were found in the intraabdominal adhesions in 39 of the total 50 patients with such adhesions (78%). There was no significant difference in the proportion and the mean nerve score in adhesions due to previous intra-abdominal infection, endometriosis, and previous uninfected intra-abdominal surgery. The degree of lymphocytes and edema in endometriosis-related adhesions was significantly higher than in postsurgical adhesions and postinfectious adhesions (P < .05). No difference was found in the amount of nerve fibers and the mean nerve score in adhesions from women with pelvic pain and from those without pelvic pain. CONCLUSION: Nerve fibers are found commonly in intraabdominal adhesions, and their presence are not related to the underlying pathology or pelvic pain. Endometriosis-related adhesions contain more inflammatory cells and tissue edema than postsurgical or postinfectious adhesions.

Abdomen↗
PubMed2001

Adhesive secretions in the Platyhelminthes.

This review is the first to draw together knowledge about bioadhesives secreted by a group of parasites. Mechanisms of mechanical attachment are well known among parasites, but some can also attach to host surfaces by chemical means using a thin layer of adhesive material secreted at the parasite-host interface. Attachment by adhesives to living surfaces has not been studied in detail previously. A significant volume of research has determined much about the chemistry and nature of bioadhesives secreted by various marine macroinvertebrates from different phyla for attachment to inert substrates. Mussels and barnacles are sessile and adhere permanently, whereas starfish display temporary but firm adhesion during locomotion, feeding and burrowing. We focus on the Platyhelminthes that comprises the largely free-living Turbellaria and the wholly parasitic Monogenea, Cestoda, Digenea and Aspidogastrea. The term tissue adhesion is introduced to describe attachment by adhesives to epithelial surfaces such as fish epidermis and the lining of the vertebrate gut. These living layers regenerate rapidly, secrete mucus, are a site for immune activity and are therefore especially hostile environments for organisms that inhabit them, presenting a significant challenge for adhesion. Not all platyhelminths adhere to living surfaces and types of adhesion to inert substrates by the free-living turbellarians are also reviewed. Tissue adhesion is particularly well exemplified by monopisthocotylean monogeneans, parasites that are especially mobile as larvae, juveniles and adults on the epidermis of the body and gill surfaces of fish. These monogeneans secrete adhesives from the anterior end when they move from site to site, but some have secondarily developed adhesives at the posterior end to supplement or replace mechanical attachment by hooks and/or by suction. The temporary but tenacious anterior adhesives of monogeneans display remarkable properties of instant attachment to and detachment from their host fish surfaces. In contrast to the mobility of turbellarians and monopisthocotylean monogeneans and the simplicity of their direct life cycles, the largely endoparasitic Cestoda and Digenea are considered to be less mobile as adults. The complex cestode and digenean life cycles, involving intermediate hosts, place different demands on their various stages. Diverse, mostly anterior, gland cells in larvae, metacestodes and adults of the true tapeworms (Eucestoda), and in larval and adult Gyrocotylidea and Amphilinidea are reviewed. Conspicuous gland cells, mostly but not exclusively at the anterior end, in miracidia, cercariae and adults of digeneans and in cotylocidia and adults of aspidogastreans are also reviewed. Unlike turbellarians and monogeneans, accounts of unequivocal adhesive secretions in the Cestoda, but especially in the Digenea and Aspidogastrea, are relatively rare. The primary purpose of many conspicuous glands in the different stages of these mostly endoparasitic flatworms is for penetration into, or escape from, different hosts in their life cycle. We provide a detailed review of current knowledge about adhesion (in the sense of a thin layer of chemical material) in the Platyhelminthes including uses among eggs, larval, juvenile and adult stages. Information on structure, morphology and ultrastructure of the various adhesive systems that have been described is reviewed. Application of the 'duo gland' model is discussed. Comparisons are made between the little that is known about the chemistry of flatworm adhesives and the significant knowledge of the chemical nature of other invertebrate bioadhesives, especially those from marine macroinvertebrates. The potential importance of adhesives in parasitism is discussed. (ABSTRACT TRUNCATED)

Animals↗
PubMed2004

Effect of surface wettability on the adhesion of proteins.

Besides significantly broadening the scope of available data on adhesion of proteins on solid substrates, we demonstrate for the first time that all seven proteins (tested here) behave similarly with respect to adhesion exhibiting a step increase in adhesion as wettability of the solid substrate decreases. Also, quantitative measures of like-protein-protein and like-self-assembled-monolayer (SAM)-SAM adhesive energies are provided. New correlations, not previously reported, suggest that the helix and random content (as measures of secondary structure) normalized by the molecular weight of a protein are significant for predicting protein adhesion and are likely related to protein stability at interfaces. Atomic force microscopy (AFM) was used to directly measure the normalized adhesion or pull-off forces between a set of seven globular proteins and a series of eight well-defined model surfaces (SAMs), between like-SAM-immobilized surfaces and between like-protein-immobilized surfaces in phosphate buffer solution (pH 7.4). Normalized force-distance curves between SAMs (alkanethiolates deposited on gold terminated with functional uncharged groups -CH3, -OPh, -CF3, -CN, -OCH3, -OH, -CONH2, and -EG3OH) covalently attached to an AFM cantilever tip modified with a sphere and covalently immobilized proteins (ribonuclease A, lysozyme, bovine serum albumin, immunoglobulin, gamma-globulins, pyruvate kinase, and fibrinogen) clearly illustrate the differences in adhesion between these surfaces and proteins. The adhesion of proteins with uncharged SAMs showed a general "step" dependence on the wettability of the surface as determined by the water contact angle under cyclooctane (thetaco). Thus, for SAMs with thetaco < approximately 66 degrees, (-OH, -CONH2, and -EG3OH), weak adhesion was observed (>-4 +/- 1 mN/m), while for approximately 66 < thetaco < approximately 104 degrees, (-CH3, -OPh, -CF3, -CN, -OCH3), strong adhesion was observed (< or =8 +/- 3 mN/m) that increases (more negative) with the molecular weight of the protein. Large proteins (170-340 kDa), in contrast to small proteins (14 kDa), exhibit characteristic stepwise decompression curves extending to large separation distances (hundreds of nanometers). With respect to like-SAM surfaces, there exists a very strong adhesive (attractive) interaction between the apolar SAM surfaces and weak interactive energy between the polar SAM surfaces. Because the polar surfaces can form hydrogen bonds with water molecules and the apolar surfaces cannot, these measurements provide a quantitative measure of the so-called mean hydrophobic interaction (approximately -206 +/- 8 mN/m) in phosphate-buffered saline at 296 +/- 1 K. Regarding protein-protein interactions, small globular proteins (lysozyme and ribonuclease A) have the least self-adhesion force, indicating robust conformation of the proteins on the surface. Intermediate to large proteins (BSA and pyruvate kinase-tetramer) show measurable adhesion and suggest unfolding (mechanical denaturation) during retraction of the protein-covered substrate from the protein-covered AFM tip. Fibrinogen shows the greatest adhesion of 20.4 +/- 2 mN/m. Unexpectedly, immunoglobulin G (IgG) and gamma-globulins exhibited very little adhesion for intermediate size proteins. However, using a new composite index, n (the product of the percent helix plus random content times relative molecular weight as a fraction of the largest protein in the set, Fib), to correlate the normalized adhesion force, IgG and gamma-globulins do not behave abnormally as a result of their relatively low helix and random (or high sheet) content.

Adhesiveness↗
PubMed1999

Different adhesion properties of highly and poorly metastatic HT-29 colon carcinoma cells with extracellular matrix components: role of integrin expression and cytoskeletal components.

Integrin-mediated tumour cell adhesion to extracellular matrix (ECM) components is an important step in the development of metastatic lesions. Thus, integrin expression and integrin-mediated adhesion of colon carcinoma cells to various ECM components was examined. Poorly (HT-29P) and highly (HT-29LMM) liver-metastatic colon carcinoma cells were used to study the rates of adhesion to collagen I (C I), collagen IV (C IV), laminin (LN), fibronectin (FN), or vitronectin (VN) in a static adhesion assay (10-120 min). Cells were untreated or treated with oligopeptides (RGD, GRGDS, YIGSR, RGES), anti-integrin antibodies, or colchicine, nocodazole, cycloheximide, acrylamide or cytochalasin D (to disrupt cytoskeletal structures). Both cell lines expressed similar patterns of integrin expression (alpha2, alpha3, ,alpha6, alphav, beta1, beta4, and beta5) by immunocytochemistry and immunoprecipitation. HT-29LMM cells showed significantly higher rates of adhesion to LN (P < 0.001) and FN (P < 0.001), but significantly poorer rates of adhesion to C I (P < 0.05) and C IV (P < 0.001) than HT-29P cells, respectively, adhesion to VN was insignificant. RGD and GRGDS inhibited HT-29LMM cell adhesion to FN only. Pretreatment with anti-beta, or anti-alpha2 integrin subunits suppressed adhesion to C I and C IV, and adhesion to LN was inhibited with anti-beta1 or anti-alpha6 integrin. Anti-beta1 or anti-alphav blocked adhesion to FN. Pretreatment of cells with cytochalasin D, cycloheximide or acrylamide inhibited adhesive interactions of both cell lines to the ECM components. In contrast, colchicine and nocodazole had no effect. The results demonstrate that adhesion of HT-29 cells to ECM is mediated, in part, by different integrins, depending on the substrate. Poorly and highly metastatic HT-29 cells possessed different patterns of adhesion to the various ECM substrates, but these differences were not due to different expression of integrin subunits. The results also suggested that the initial adhesion of poorly or highly metastatic HT-29 cells to ECM components requires, in part, the presence of native action and intermediate filaments, but not of microtubules. Thus the adhesion of tumour cells to ECM components may be dependent on signal transduction and assembly of microfilaments.

Acrylamide↗
PubMed1998

Globoside-dependent adhesion of human embryonal carcinoma cells, based on carbohydrate-carbohydrate interaction, initiates signal transduction and induces enhanced activity of transcription factors AP1 and CREB.

Undifferentiated human embryonal carcinoma cells are characterized by high expression of lactoneotetraosylceramide (nLc4), globoside (Gb4), and extended globo-series glycosphingolipids (GSLs) termed "stage-specific embryonic antigens 3 and 4" (SSEA-3 and -4). Expression of these GSLs declines in association with a decline of homotypic adhesion during the differentiation process. Therefore, these GSLs may play an essential role in adhesion among these cells. As an example, human embryonal carcinoma 2102 cells display strong adhesion to plates coated with Gb4 ("Gb4-dependent cell adhesion"). This adhesion, which simulates homotypic 2102 cell aggregation, is based on interaction between Gb4 and nLc4, or between Gb4 and GalGb4 (IV3GalGb4; the major SSEA-3 epitope), as indicated by the following observations: (i) adhesion of 2102 cells or GSL-liposomes to GSL-coated plates in various combinations; (ii) inhibition of Gb4-dependent 2102 cell adhesion by preincubation of cells with anti-SSEA-3 or anti-nLc4 antibodies, or by pretreatment of Gb4-coated plates with aqueous micellar solution of nLc4 or GalGb4; (iii) decline of the cell adhesion in association with retinoic acid-induced differentiation, whereby SSEA-3 and nLc4 levels are reduced. Since cell adhesion is an essential prerequisite for induction of differentiation, as observed at each step of embryogenesis, expression of seven transcription factors following adhesion of 2102 cells to Gb4-coated plates, and to detergent-insoluble substrate adhesion matrix prepared from 2102 cells, were studied. In both types of adhesion, a strong enhancement of AP1 and CREB site binding activity was observed during the early stage (15-60 min following initial adhesion). Although 2102 cells showed strong adhesion to Gg3-coated plates, based on interaction between Gg3 and Gb4, adhesion of the cells to Gg3 did not cause changes of AP1 and CREB activity. No other transcription factors showed changes induced by Gg3- or Gb4-dependent adhesion.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1999

The carboxy-terminal cell-binding domain of thrombospondin is essential for sickle red blood cell adhesion.

Sickle red blood cells (SS-RBCs) have enhanced adhesion to the plasma and subendothelial matrix protein thrombospondin-1 (TSP) under conditions of flow in vitro. TSP has at least four domains that mediate cell adhesion. The goal of this study was to map the site(s) on TSP that binds SS-RBCs. Purified TSP proteolytic fragments containing either the N-terminal heparin-binding domain, or the type 1, 2, or 3 repeats, failed to sustain SS-RBC adhesion (<10% adhesion). However, a 140-kD thermolysin TSP fragment, containing the carboxy-terminal cell-binding domain in addition to the type 1, 2, and 3 repeats fully supported the adhesion of SS-RBCs (126% +/- 25% adhesion). Two cell-binding domain adhesive peptides, 4N1K (KRFYVVMWKK) and 7N3 (FIRVVMYEGKK), failed to either inhibit or support SS-RBC adhesion to TSP. In addition, monoclonal antibody C6. 7, which blocks platelet and melanoma cell adhesion to the cell-binding domain, did not inhibit SS-RBC adhesion to TSP. These data suggest that a novel adhesive site within the cell binding domain of TSP promotes the adhesion of sickle RBCs to TSP. Furthermore, soluble TSP did not bind SS-RBCs as detected by flow cytometry, nor inhibit SS-RBC adhesion to immobilized TSP under conditions of flow, indicating that the adhesive site on TSP that recognizes SS-RBCs is exposed only after TSP binds to a matrix. We conclude that the intact carboxy-terminal cell-binding domain of TSP is essential for the adhesion of sickle RBCs under flow conditions. This study also provides evidence for a unique adhesive site within the cell-binding domain that is exposed after TSP binds to a matrix.

Amino Acids↗
PubMed1987

Role of platelet membrane in enhancement of tumor cell adhesion to endothelial cell extracellular matrix.

Tumor cell adhesion to subendothelial matrix in the presence of platelets and plasma has been examined in vitro using an entirely homologous system of rat Walker 256 carcinosarcoma cells, matrix laid down by rat aortic endothelial cells and rat platelets and plasma. In the presence of platelets or platelets plus plasma, tumor cell adhesion was significantly enhanced when compared to adhesion in the absence of platelets. In the presence of plasma alone (0.1%), we observed no significant increase in tumor cell adhesion. In order to determine which platelet factors contribute to the enhancement of tumor cell adhesion by platelets, we subjected washed rat platelets to mechanical lysis or thrombin stimulation followed by centrifugation. The membrane fractions and supernatant fractions containing platelet attachment proteins were compared for their abilities to support tumor cell adhesion to subendothelial matrix. Platelet membranes were also recombined with platelet supernatant fractions to determine if platelet attachment proteins or platelet membranes required the presence of the other to enhance tumor cell adhesion. Platelet supernatant fractions which contained release reaction proteins (confirmed by polyacrylamide gel electrophoresis) did not enhance tumor cell adhesion. Purified thrombospondin, fibronectin, beta-thromboglobulin, platelet derived growth factor, and serotonin had no effect on tumor cell adhesion. Platelet membrane containing fractions affected tumor cell adhesion to subendothelial matrix as follows: (a) platelets formed an adhesive bridge between tumor cells and the subendothelial matrix as demonstrated by scanning electron microscopy; (b) intact platelets and thrombin stimulated platelets were the most effective at facilitating tumor cell adhesion; (c) preparations containing partially lysed platelet ghosts were more effective in supporting tumor cell adhesion to subendothelial matrix than were preparations containing completely lysed platelet membrane fragments; (d) recombination of platelet supernatant fractions with mechanically lysed platelets did not enhance their ability to support adhesion; (e) fixed platelets, either alone or in combination with platelet supernatant fractions, failed to enhance adhesion. These data indicate that platelet enhanced tumor cell adhesion appears to be dependent on platelet membrane factors including receptor mobility, rather than intraplatelet components.

Animals↗
PubMed1995

Adenosine activates A2 receptors to inhibit neutrophil adhesion and injury to isolated cardiac myocytes.

Inhibition of neutrophil-myocyte adhesion and adhesion-dependent myocyte injury by adenosine was evaluated using isolated TNF-alpha-activated canine cells. Adenosine inhibited adhesion of activated neutrophils to cardiac myocytes with an IC50 of 11 +/- 4 nM. Inhibition of neutrophil adhesion (92 +/-3% by 100 nM adenosine) led to inhibition of myocyte injury (by 90 +/- 6%, as assessed by dye exclusion). Inhibition of cell adhesion by adenosine was blocked by the A2 antagonist, 1,3-dimethyl-1-propylxanthine, but not by the A1 antagonist, 8-cyclopentyl-1,3-dipropylxanthine. Moreover, the A2 agonist, CGS21680 (2-[4-(2-carboxymethyl)phenethylamino]-5'-N-ethylcarboxamido adenosine), but not the A1 agonist, N6-cyclopentyladenosine, mimicked adenosine in preventing cell adhesion. These observations implicate the A2 receptor in the mechanism of inhibition of cell adhesion. pretreatment and washing of neutrophils, but not cardiac myocytes, with adenosine or CGS21680 led to inhibition of adhesion, suggesting that the neutrophil A2 receptor is the target of adenosine's action. In contrast, inhibition of cell adhesion by adenosine was poteniated by 8-cyclopentyl-1,3-dipropylxanthine (IC50 = 4 +/- 1 nM) and attenuated by N6-cyclopentyladenosine, suggesting that occupancy of A1 receptors can conversely increase cell adhesion. Neutrophil-myocyte adhesion was inhibited by acadesine (IC50 = 12 +/- 2 microM) also via an adenosine-dependent mechanism because it was blocked by 1,3-dimethyl-1-propylxanthine or adenosine deaminase, an enzyme that degrades any adenosine that is formed. Acadesine-induced inhibition if cell adhesion (83 +/- 4% by 100 microM) resulted in inhibition of myocyte injury (by 76 +/- 6%). Other adenosine-regulating agents, including the acadesine analogue, GP531 (5-amino-1 beta-D-(5-benzylamino-5-deoxyribofuranosyl) imidazole-4-carboxamide), and inhibitors of adenosine transport and intracellular metabolism also inhibited cell adhesion. These results indicate that exogenous or endogenous adenosine can inhibit neutrophil-myocyte adhesion and injury in cells activated with TNF-alpha by an A2-mediated mechanism. Although the predominant activity of adenosine is to attenuate cell adhesion, stimulation of A1 receptors has the opposite effect, i.e., to augment adhesive interactions.

Adenosine↗