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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

[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

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

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

[The effect of fluoride application following enamel etching on the adaptation and adhesiveness of adhesive fillings].

The application of fluoride to etched enamel and the subsequent influence upon the marginal adaptation and retention of adhesive restorations was examined in vitro. Results showed that amine fluoride (F- = 1.15%, I.E. 0.01%) and 8% SnF2 (F- = 1.94%) did not affect wetting of the conditioned enamel by sealer and composite material. However, a reduction in retentive potential evidenced by a partial loss of the restoration feather margin during circulation bathing was observed. Consequently, during adhesive restorative procedures, a fluoride treatment of etched enamel prior to sealer application and composite insertion is contraindicated. Upon completion of adhesive restorations a fluoride application, for example Elmex Fluid, to the entire operation field is, however, recommended.

Acid Etching, Dental

Kinetics of adhesion and de-adhesion of Chlamydomonas gametes.

In medium with low nitrogen content, vegetative strains of the unicellular biflagellate alga Chlamydomonas reinhardi form gametes. Mating type plus (mt+) and mating type minus (mt-) gametes adhere via their flagella to give aggregates in which the gametes eventually fuse to form zygotes. A quantitative assay has now been developed which measures aggregation and fusion by use of a Coulter electronic particle counter to determine loss of single gametes as they form aggregates in suspension. Determination of the rate and extent of cell fusion by microscopy agrees with the results obtained with the more rapid and convenient Coulter counter assay. By use of the assay it was found that aggregation and fusion occur at the same rate and to the same extent at 12 degrees C and 25 degrees C. Flagella from one of the mating types can specifically substitute for the corresponding live gametes; more than 70% of the gametes were aggregated and the extent of aggregation was proportional to the number of flagella added, until the ratio of cells to flagella exceeded 2. At 22 degrees C, in the flagella/gamete mixtures, adhesion was complete in less than 5 min, but at 5 to 10 min, gametes began to de-adhere from the clusters and, depending on the number of flagella added, essentially all of the gametes detached from the aggregates in 10 to 50 min. The gametes in such mixtures were fully competent to aggregate again, whereas the flagella recovered from such mixtures were shown by use of a radioactive flagella-binding assay to be inactive with fresh gametes. Inactivation of the flagella was temperature-dependent, was not catalyzed by soluble factors, and required adhesion of flagella to gametes of the opposite mating type. The potential physiological functions of the de-adhesion process are discussed.

Cell Adhesion