[Acid etch and adhesives in dentistry II. Adhesion--capillarity--superficial tension--surfaces of high and low energy--high adhesion].
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Acid Etching, Dental↗
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[Adhesion mechanisms of adhesives and composites (or how do adhesive and composites adhere?)].
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Acid Etching, Dental↗
Tannin-bearing hydrogel adhesives with enhanced mechanical and adhesion strength in response to protein leakage.
Anastomotic leaks are among the most severe side effects following abdominal surgeries. Conventional surgical sealants and emerging hydrogel adhesives often lose mechanical and adhesion strength when exposed to leaked digestive enzymes. Here, we report a tannin-encapsulating tough hydrogel adhesive that exhibits enhanced mechanical and adhesive properties upon the encounter of leaked proteins. The hydrogel is composed of a gelatin-acrylate crosslinked network with encapsulated tannin and can adhere to a wet surface via amine-carboxyl chemistry. In the context of anastomotic leaks, tannin within the hydrogel can form a complex with proteins including the digestive enzymes, leading to increased gel stiffness and storage modulus. The enhanced mechanical strength confers improved adhesive properties on the hydrogel adhesive. Additionally, the tannin-bearing hydrogel adhesive shows excellent antibacterial properties. This adaptive and antibacterial hydrogel adhesive provides a promising sealant for gastrointestinal surgery and other applications.
Tannins↗
Intercellular adhesive selectivity. I. An improved assay for the measurement of embryonic chick intercellular adhesion (liver and other tissues).
An improved assay for measuring intercellular adhesive selectivity of embryonic chick liver cells is described. Three major improvements over earlier procedures are noted: (a) enhanced reproducibility of liver cell-liver cell aggregate adhesion (homotypic adhesion) was achieved; (b) 25-70% of the input cells adhered to the collecting aggregates during the course of routine experiments as compared to the 0.25% in earlier assays. This increase in cellular adhesion suggests that the observed cell pick-up is a characteristic of the majority of the dissociated liver cell population; (c) the rate of intercellular adhesion was increased 1,000-fold. The main feature of the assay is that it measures the tissue adhesive selectivities of the dissociated cell population. Studies were undertaken on three embryonic chick tissues (liver, neural retina, and mesencephalon) to determine the tissue selectivity of intercellular adhesion of these dissociated cell types. Some general properties of liver cell homotypic adhesion have been studied and are reported.
Animals↗
Intercellular adhesive selectivity. II. Properties of embryonic chick liver cell-cell adhesion.
Studies directed at understanding the molecular basis of liver cell homotypic adhesion are presented. An assay which measures the rate of adhesion of isotopically labeled (32PO4) embryonic chick liver cells to liver cell aggregates, described in a companion paper, has been used to investigate the problem of intercellular adhesive selectivity. Cation requirements, the effects of various inhibitors of metabolism and protein synthesis, of chelators (EDTA and EGTA), and the effects of temperature on liver cell adhesion are reported. Two mechanisms of inhibition of liver intercellular adhesion are suggested. One involves destruction of cell-surface adhesion receptors (sensitivity to proteases); the other is an energy-dependent step which may involve alterations in plasma membrane conformation and/or membrane fluidity. Finally, a model is suggested for liver cell-cell adhesion that incorporates the early tissue selectivity of intercellular adhesion previously reported, followed by a multistep process which leads to histogenic aggregation.
Animals↗
Intercellular adhesive selectivity. III. Species selectivity of embryonic liver intercellular adhesion.
A species difference in the intercellular adhesive selectivity of mixtures of embryonic liver cells is reported. This is first quantitative assessment of species differences in the intercellular adhesive properties of embryonic cells. A collecting aggregate assay, a new double-label assay procedure, and histological and autoradiographic procedures were used to elucidate the intercellular adhesive selectivity of developing mammalian and avian liver cells. Evidence is presented that the reported adhesive differences are not due to the different cell types composing the respective embryonic mammalian and avian livers. Finally, such heterolgous-homotypic selectivity of adhesion is not a property of all tissues, since it is shown that developing brain cells (mesencephalon) do not exhibit the avove intercellular adhesive selectivity (mammalian vs. avian). These findings provide further support for the hypothesis that generic identity as well as cell type may play an important part in determining the intercellular adhesive behavior of heterologous-homotypic mixtures of embryonic cells. A possible evolutionary divergence of morphogenetic mechanisms is discussed.
Animals↗
Selective adhesion and impaired adhesive properties of transformed cells.
Quantitative studies on the adhesive properties of transformed cells have yielded inconclusive and sometimes contradictory results. The present investigation has examined adhesive interactions between normal human fibroblasts, established as well as virus-transformed animal cell lines, and human tumour-derived cell lines by the cell-cell layer binding assay. The results of these investigations indicate that adhesive selectivity can be observed between normal human fibroblasts and 2 human tumour-derived cell lines, providing an in vitro system to study cell surface components involved in cellular interactions between normal and malignant cells. In addition it is demonstrated that cell layers of transformed cells form a poorly adhesive substratum for both trypsinized normal and transformed cells. Furthermore, it is confirmed that the adhesive properties of transformed cells, including adhesive selectivity, are affected by the dissociation procedure (trypsin or EDTA). In view of the observations made by other investigators, the present results suggest that transformed cells display adhesive properties which can be quantitatively and reproducibly measured but which are modulated by the dissociation procedure as well as by the configuration in which the cells are at the time of the assay.
Animals↗
Studies on intercellular adhesion. II. Promoting effect of serum and proteins on adhesion of neural retina cells to isotypic aggregates.
The quantitative assay described in the preceding paper (Pessac et al., '77) was used to study the effects of serum and various proteins on isotypic adhesion of chick embryo neural retina cells. Fetal bovine, chicken, horse, rabbit and human sera promoted cell adhesion to the same extent. The same sera also enhanced isotypic adhesion of cells from other organs showing that the cell adhesion promoting activity of sera was not organ specific. Neural retina (NR) cell collection in serum supplemented medium was not modified by protein synthesis or metabolic inhibitors and was temperature dependent with a maximum at 38 degrees C. The higher temperature does not seem to be required for repair of the cell surface after dissociation, but for the process of adhesion itself. Various serum fractions and egg albumin showed a cell adhesion promoting activity similar to that of sera.
Azides↗
[Application of 4-META on adhesive opaque resin. (Part 1) Adhesive strength and the stability (author's transl)].
Mechanical devices, which has been conventionally used for retaining thermo-setting acrylic resin veneers possesses disadvantage of poor marginal sealing and requires rather complicated procedure applying on the metal casting. An application of adhesive resins to overcome these disadvantages was studied. Adhesive opaque resin consisted of MMA, epoxy acrylate, TiO2 and adhesive monomer 4-META was prepared and the adhesive bonding strength between the opaque resin and Ni-Cr alloy which is for crown and bridge works, was measured. As the results, the opaque resin applied on the metal casting with proper surface treatment showed an excellent adhesive bonding strength of 260 kg/cm2. This value did not decreased even after subjected to 300 time thermal cyclings (4 degrees C and 60 degrees C). After a three months immersion in water at 37 degrees C, adhesive bonding strength decreased slightly to 190 kg/cm2.
Acrylic Resins↗
[Application of 4-META on adhesive opaque resin. (Part 2) Improvement of adhesive stability (author's transl)].
We had reported 4-META adhesive opaque resin for a metal casting etched with HC1. The bonding strength was as excellent as 260 kg/cm2 after 300 times thermal cycles between 4 degrees C and 60 degrees C but it decreased to 70 kg/cm2 when immersed in water at 37 degrees C for 30 weeks. It was required to improve the stability of bonding against water penetration into the adhesive junction before the clinical application. Preparation of the passive state on the metal casting adhesive stability between this film and the opaque resin were studied in this paper. When the metal casting was dipped in conc. HNO3 for fifteen minutes, adhesive strength was 260 kg/cm2 even after a 30 weeks immersion in water at 37 degrees C or the 10 weeks at 80 degrees C. It could be concluded that the adhesive opaque resin possesses enough adhesive strength and the stability for oral application.
Acrylates↗
Non-pressure adhesion of a new adhesive restorative resin.
Non-pressure adhesion of a new adhesive restorative resin was investigated employing a new tensile test. The material was adhesive to both enamel and dentin as well as to carious dentin and showed strong adhesion to all substrates tested. Etching further increased the adhesion even to dentin.
Acid Etching, Dental↗
Adhesion among neural cells of the chick embryo. III. Relationship of the surface molecule CAM to cell adhesion and the development of histotypic patterns.
We have previously identified a molecule (named cell adhesion molecule [CAM]) that is involved in the in vitro aggregation of neural cells from chick embryos. In the present report, specific anti-CAM antibodies have been used to demonstrated that CAM is localized in neural tissues, and is associated with the plasma membrane of retinal cells and neurites. Furthermore, it has been shown by antibody absorption techniques that the decreased adhesiveness of cultured retinal cells obtained originally from older embryos is correlated with a decrease in the density or accessibility of cell adhesion molecules on the surface of these cells. The central role of CAM in neural cell aggregation has been established by the observation that anti-CAM Fab' fragments inhibit adhesion between neural cells in a variety of assays. To investigate the function of CAM and cell adhesion in developing tissues, aggregates of retinal cells that are capable of forming histotypic patterns in vitro were cultured in the presence and absence of anti-CAM Fab'. The Fab' was found to inhibit sorting out of cell bodies and neurites and to decrease the number of membrane-membrane contacts, suggesting that CAM is associated with cell-cell, cell-neurite, and neurite-neurite interactions.
Animals↗
Adhesive properties of Vibrio cholerae: adhesion to isolated rabbit brush border membranes and hemagglutinating activity.
Adhesion of vibrios to the small intestine may occur (i) by association of the bacteria with secreted mucus gel or (ii) by adherence of the bacteria to the surface of epithelial cells. In the present study, vibrios readily adhered to isolated brush border membranes obtained from rabbit intestinal epithelial cells. Adhesion was temperature dependent and required the presence of divalent cations such as calcium. The agglutination of human O erythrocytes by Vibrio cholerae was observed also, and the hemagglutination test appeared to detect the same mechanism that was involved in the adhesion of vibrios to brush borders. When the bacteria were grown in broth they were adhesive and hemagglutinating, but vibrios grown on agar plates or suspended in buffer for 15 min at 37 C lacked these abilities, even though they retained undiminished motility. These two model systems differed, however, in that strontium promoted only adhesion to brush borders. The significance of this difference remains to be determined. Vibrios were observed to penetrate intestinal mucus gel and occasionally to become entrapped in it. However, there was no evidence that vibrios attached to mucus gel.
ABO Blood-Group System↗
Studies on intercellular adhesion. I. Adhesion of neural retina cells to isotypic aggregates in serum free medium.
A quantitative assay for intercellular adhesion, which is a modification of the collecting aggregate assay (Roth et al., '71) is described. The use of mechanically dissociated single cells labeled with 3H-leucine, and of a gyratory shaker increased considerably the efficiency of cell collection. With chick embryo neural retina, it was shown that isotypic cell adhesion occurs in simple synthetic media and even in sodium chloride solution suggesting that divalent cations do not play a major role in adhesion of these cells. Cell collection in media without serum was not affected by metabolic or protein synthesis inhibitors. However, cell adhesion was temperature-dependent since no collection occurred at 4 degrees C but was maximal at 38 degrees C.
Azides↗
Cell surface lipids and adhesion. II. The turnover of lipid components of the plasmalemma in relation to cell adhesion.
The preceding paper showed that those conditions that ought to stimulate reacylation of lysolipids in cells can increase cell adhesions. Similarly we found that conditions that would be expected to lead to the accumulation of lysolipids in the cell surface diminish cell adhesion. This paper reports on the answers to the following questions. (1) Is reacylation of lysolipids in the cells stimulated by an external supply of CoA, ATP and a fatty acid? (2) Does this reacylation lead to the incorporation of exogenous fatty acid in the plasmlemma? (3) What range of fatty acids can be incorporated into the plasmalemma and into what compounds? (4) Does the plasmalemma contain the enzyme systems to effect this turnover, namely phospholipase A2, a CoA-ligase and an appropriate acyl transferase(s)? (5) Do lysolipids accumulate in the plasmalemma under conditions which diminish cell adhesion? We find that saturated fatty acids in the range C14--C18, and some unsaturated fatty acids are incorporated into the plasmalemmae of these neural retina cells. About 20% of the plasmlemma content of fatty acids can be turned over in 30'. Incorporation is mainly into phosphatidyl choline, serine and ethanolamine in both R1 and R2 positions. The plasmalemmae contain the enzymes to effect the turnover. Isolated plasmalemmae are active in this turnover. Incubation of the plasmalemmae with phospholipase A2 leads to an accumulation of lysolipids. Very low levels of phospholipase stimulate turnover, possibly endogenous phospholipase activity is the rate-limiting step in the system. These findings are discussed in relation to the possible mechanisms by which lipids might affect adhesion.
Acyltransferases↗
The sorting out of embryonic cells in monolayer, the differential adhesion hypothesis and the non-specificity of cell adhesion.
It has been reported previously that sorting out of chick embryonic liver parenchyma and limb bud mesenchymal cells would take place in monolayer culture. The distribution of cell types obtained (liver formed the internal, discontinuous phase) was interpreted in terms of the differential adhesion hypothesis. It was suggested that, in monolayer, liver cells were more cohesive than limb bud cells. In this paper we set out to extend the previous observations with 2 particular questions in mind: (i) Is sorting out in monolayer a general phenomenon occurring between a wider range of cell types? (ii) Can evidence be provided for or against the interpretation of results in terms of the differential adhesion hypothesis? Sorting-out experiments were conducted on circular hydrophilic islands, on an otherwise hydrophobic substratum. Under these conditions, sorting-out in monolayer was obtained with binary combinations of 4 chick embryonic tissue types: liver parenchyma, limb bud mesenchyme, pigmented epithelium of the eye and corneal epithelium. With every combination but one, the cells of one type surrounded the cells of the other type, generating what we have called a 'circle-within-a-circle' configuration. With the remaining combination, liver parenchyma and corneal epithelium, only localized sorting was obtained. The 'circle-within-a-circle' configuration is consistent with an interpretation in terms of the differential adhesion hypothesis, according to which the distribution of cells is determined by the relative strengths of cohesions between their lateral surfaces. In direct support of this is the finding from plating the different cell types at sub-confluent density on hydrophilic substrata that limb bud is the cell tye having the weakest lateral cohesion in monolayer. Limb bud surrounded the other 3 tissues on hydrophilic island. A hierachy of lateral cohesiveness between the 4 cell types has been constructed. It is unlikely that the results can be explained in terms of specific cohesion. When plated together at subconfluent density, the 3 epithelial cell types aggregate together to form mixed monolayered islands, suggesting that they share common adhesive mechanisms.
Animals↗
Studies on intercellular adhesion. III. Adhesion of cells to isotypic or heterotypic collecting particles and monolayers.
Adhesion between cells of different tissues from chick embryos was studied by the modified collecting particle (Pessac et al., '77a) and stationary monolayer assays. These assays measure the number of 3H labeled cells that adhere to the surface of cell aggregates and tissue fragments or on top of cell monolayers. The numbers of cells from a given suspension that adhere to identical or different cells can be compared. Intercellular adhesion may be considered as tissue specific if, in identical conditions, more cells adhere to identical cells than to cells from different tissues. Neural retina, cerebrum, optic tectum, liver and kidney cells from 9-day-old chick embryos showed no tissue specificity of adhesion, while heart cells adhered preferentially to collecting heart fragments.
Animals↗
In vitro adhesion of Escherichia coli to porcine small intestinal epithelial cells: pili as adhesive factors.
Escherichia coli strains with pili (K99 or 987P) known to facilitate intestinal colonization adhered in vitro to porcine intestinal epithelial cells. These strains adhered equally to both ileal and jejunal epithelial cells. A laboratory E. coli strain that has type 1 pili also adhered to porcine intestinal epithelial cells. When nonpiliated cells derived from 987P+, K99+, or type 1 pilus+ strains were used for in vitro adhesion assays, they failed to adhere. The attachment of piliated bacteria to epithelial cells was a saturable process that plateaued at 30 to 40 bacterial cells attached per epithelial cell. Competitive inhibition of bacterial cell attachment to epithelial cells with purified pili showed that only purified 987P competed against the 987P+ strain and only purified type 1 pili competed against the type 1 pilus+ strain. Competition between a K99+ strain and K99 was not consistently achieved. K99+, 987P+, and type 1 pilus+ bacteria could be prevented from adhering to epithelial cells by Fab fragments specific for K99, 987P, or type 1 pili, respectively. Fab fragments specific for non-K99 bacterial surface antigens did not inhibit adhesion of the K99+ strain. It is concluded that adhesion of E. coli to porcine intestinal epithelial cells in vitro is mediated by pili and that the epithelial cells used apparently had different receptors for different pili.
Animals↗