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

The ability of Candida albicans IFO 1385 to adhere to acrylic and the partial characterization of an adhesive substance, named AS, which was isolated from the yeast, were studied in vitro. The results obtained were as follows: 1. The cells cultured in the synthetic media (YNB) containing 500 mM galactose showed a much greater tendency to adhere than did those cells cultured in the YNB containing 500 mM glucose. 2. More cells prepared by the standing cultivation adhered to acrylic than did those prepared by the stirring cultivation. 3. A large number of the adherent cells was obtained when the acrylic plates were incubated at 37 degrees C for 90 min in the cell suspension at a concentration of 1.0 x 10(7) cells/ml. The plates were observed without staining. 4. AS was isolated from the surface of C. albicans, grown on different carbon sources (50 mM glucose, 500 mM glucose and 500 mM galactose), by treatment with ultrasonication. 5. Three different kinds of AS isolated from the three carbon sources were slightly soluble in distilled water. All were similar in composition to each other, and contained 62-68% carbohydrate (as glucose) and 23-26% protein (as BSA). 6. Silica particles adhered to acrylic coated with AS and pretreatment of acrylic with AS promoted C. albicans adhesion. However, similar pretreatment inhibited subsequent Candida glabrata and Candida krusei adhesion. As to subsequent adhesion of Candida tropicalis, no significant data were obtained. 7. Adhesion assay using the silica particles, the adhesive ability of the AS was significantly reduced by treatment with trypsin or pronase E, but not with papain, alpha-amylase, dextranase or zymolyase.
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PMID:[Adherence of Candida albicans to acrylic surfaces]. 248 1

Silica microspheres bearing a known surface charge were used to test the adhesive properties of support films and support film treatments commonly used in the electron microscopy of particulate specimens. Adhesion was strongly correlated with surface charge, negatively charged microspheres binding well only to positively charged support films and vice versa in solutions of low ionic strength. This charge dependency could be overcome by increasing the ionic strength to about 100 mmol with monovalent cations; under these conditions, it was not necessary to provide an oppositely charged film surface to obtain adhesion. Chromatin particles (nucleosomes) which have a net negative charge, behaved very much like the negatively charged silica with respect to adhesion, confirming that the microspheres provided an accurate indication of support film surface properties. The chromatin particles showed dramatic structural changes under conditions when adhesion was either poor, or very strong, indicating the need for careful selection of binding conditions for delicate biological specimens. A new and simple method for pretreating carbon films to improve adhesion was developed, and a preliminary account of this technique is presented.
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PMID:Adhesion of particulate specimens to support films for electron microscopy: a model system for assessing the surface properties of support films, and its application to chromatin particles. 626 Sep 56

Adhesion of bone and epithelial cells to the dental implant are vital to its retention in alveolar bone and to the prevention of infection via its 'gingival' margin. Studies of cytotoxicity, tissue irritability and carcinogenicity of implantable polymers, metals and ceramics and of tissue adhesion to them have been carried out in tissue culture and in animal experiments. The more similar the polymeric materials are chemically to living tissue the more easily are they dissolved and digested in the host. Therefore, implant materials having a molecular structure similar to protein or polysaccharide, e.g. Nylon, cannot be expected to function. On the other hand, silicones, polyethylene and Teflon (polytetrafluroethylene), which have molecular structures completely different from living substances, are generally more stable in the tissues. However, these polymers are hydrophobic and have little adhesion to living cells in spite of their high stability. They are not, therefore, suitable materials for the construction of implants. Studies on antithrombotic polymers have demonstrated the possibility of creating implantable polymers which have high stability as well as strong adhesion to the surrounding tissues. These properties may be conferred by grafting a hydrophilic polymer on to the surface of a hydrophobic polymer. Of the metals, Ti, Zr and Ta are fairly stable in living tissue, and allow cells to adhere strongly. Alloys of Co-Cr-Mo, Fe-Ni-Cr-Mo, Ti-Al-V, Ti-Mo, Ti-Pd and Ti-Pt deserve to be better evaluated because they are low in density, have high mechanical strength, stability and corrosion resistance in living tissue, and there is direct adhesion to the surrounding tissues. Biodegradable or bioactive ceramics which induce bone formation around the implant do not have sufficient mechanical strength. Implant ceramics have to be stable, e.g. crystal alumina, vitreous carbon, synthetic hydroxypatite and silicon nitrate. These exhibit high biocompatibility and excellent adhesion to tissue. Single crystal sapphire ceramics with high mechanical strength permit the delicate designs required for implants. Success with dental implants may depend upon combining the rigid retention of porous stable alloys or ceramics of suitable Young's modulus with a stress absorbing superstructure. A further development to be expected is the appearance of composite and polyphase materials which have tissue adhesiveness, stability in living tissues and various degrees of Young's modulus.
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PMID:Cellular responses to implant materials: biological, physical and chemical factors. 658 Nov 29

Use of porcelain denture teeth may be desirable in many clinical situations, including implant-supported prostheses. However, lack of space because of frameworks often precludes the use of conventional retention by diatorics and pins. Adhesion of porcelain denture teeth to denture resin could also stiffen and possibly strengthen dentures and decrease stain ingress between porcelain teeth and resin denture bases. Unlike previous studies that investigated the bond between conventional feldspathic metal-ceramic porcelain and bis-GMA based composite resin, this study investigated adhesion of denture tooth porcelain to polymethyl methacrylate (PMMA). High-energy air abrasion, hydrofluoric acid etching, and the use of a general purpose bonding agent resulted in an improved bond strength of heat-cured denture PMMA bonded to denture tooth porcelain. Silane coating did not improve bond strengths, and conventional air abrasion was no more effective than polishing with 600-grit silicon carbide. Storage in water and artificial aging substantially decreased bond strengths. The strongest bond strengths were achieved by a high-energy-abrasion + etching + multi-purpose bonding-agent treatment, but a simpler etching + multiple-purpose bonding-agent treatment also produced reliable results. A laboratory technique was suggested. The role of surface treatment in the mechanism of adhesion was examined with scanning electron microscopy. High-energy abrasion produced a slightly more detailed initial topography than conventional air abrasion, but after etching, the high-energy topography became much more detailed. Surface topography alone did not account for all differences found.
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PMID:Adhesion of denture tooth porcelain to heat-polymerized denture resin. 747 77

Adhesion of Staphylococcus aureus was investigated on flat silicon oxide surfaces that had been incubated in human plasma at different concentrations. Adhesion of bacteria did not occur at high incubation concentrations of plasma or when the surface had been incubated in egg albumin. However, significant adhesion was observed when plasma was diluted. With the use of antibody method, it was noted that the adhesion of the bacteria coincided with adsorbed fibrinogen, and possibly also with IgG. We also investigated the effect of "narrow space" on the adsorption of blood plasma and subsequent adhesion of S. aureus. In these experiments, blood plasma was incubated under a convex lens placed upside-down on the silicon oxide surface. This method creates a continuous gradient of space from the contact point of the lens and outward. After rinsing off the plasma and the lens, the surface was incubated with a suspension of S. aureus followed by quantification of the attached bacteria by means of optical methods. Adhesion of bacteria occurred in several circular zones that were easily detectable with the naked eye or by the means of simple optical methods. In addition, in these experiments, adhesion coincided with adsorbed fibrinogen or IgG at the surfaces. The increased bacterial adhesion to surfaces incubated in diluted plasma, or plasma incubated in narrow space, is a variant of the so-called "Vroman effect." With a model protein system consisting of fibrinogen and IgG and the corresponding antibodies, we demonstrate that "dilution" and "incubation in narrow space" are two phenomenologically similar methods.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lens-on-surface method for investigating adhesion of Staphylococcus aureus to solid surfaces incubated in blood plasma. 808 45

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

In order to exploit the ability of anaerobic bacteria to degrade certain contaminants for bioremediation of polluted subsurface environments, we need to understand the mechanisms by which such bacteria partition between aqueous and solid phases, as well as the environmental conditions that influence partitioning. We studied four strictly anaerobic bacteria, Desulfomonile tiedjei, Syntrophomonas wolfei, Syntrophobacter wolinii, and Desulfovibrio sp. strain G11, which theoretically together can constitute a tetrachloroethylene- and trichloroethylene-dechlorinating consortium. Adhesion of these organisms was evaluated by microscopic determination of the numbers of cells that attached to glass coverslips exposed to cell suspensions under anaerobic conditions. We studied the effects of the growth phase of the organisms on adhesion, as well as the influence of electrostatic and hydrophobic properties of the substratum. Results indicate that S. wolfei adheres in considerably higher numbers to glass surfaces than the other three organisms. Starvation greatly decreases adhesion of S. wolfei and Desulfovibrio sp. strain G11 but seems to have less of an effect on the adhesion of the other bacteria. The presence of Fe(3+) on the substratum, which would be electropositive, significantly increased the adhesion of S. wolfei, whereas the presence of silicon hydrophobic groups decreased the numbers of attached cells of all species. Measurements of transport of cells through hydrophobic-interaction and electrostatic-interaction columns indicated that all four species had negatively charged cell surfaces and that D. tiedjei and Desulfovibrio sp. strain G11 possessed some hydrophobic cell surface properties. These findings are an early step toward understanding the dynamic attachment of anaerobic bacteria in anoxic environments.
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PMID:Adhesion of biodegradative anaerobic bacteria to solid surfaces. 1054 26

The tarsi of the cricket Tettigonia viridissima bear flexible attachment pads that are able to deform, replicating the profile of a surface to which they are apposed. This attachment system is supplemented by a secretion produced by epidermal cells and transported onto the surface of the pad through the pore canals of the pad cuticle. This study shows that the secretion alone is necessary, but not sufficient, for adhesion. To account for the full adhesive force, the deformation of the pad and the resulting changes in contact area were considered. In two series of experiments, the adhesive properties of the secretion and the adhesion of the whole pad were measured using a force tester, the sensitivity of which ranged from micronewtons to centinewtons. The adhesive forces of the secretion measured between a smooth sapphire ball with a diameter of 1.47 mm and a flat silicon surface ranged from 0.1 to 0.6 mN. In a control experiment on the silicon surface without secretion, no adhesive force was measured. There was no dependence of the adhesive force on the applied compressive force. When an intact pad was pulled off a flat silicon surface, the adhesive force increased with increasing applied compressive force, but it did not increase further once the applied force exceeded a certain value. The saturated adhesive force, ranging from 0.7 to 1.2 mN, was obtained at applied forces of 0.7-1.5 mN. The hemispherical surface of the pad had a larger contact area and demonstrated greater adhesion under a larger applied force. Adhesion became saturated when a pad was deformed such that contact area was maximal. The tenacity (the adhesive force per unit area) was 1.7-2.2 mN mm(-)(2).
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PMID:Adhesion measured on the attachment pads of Tettigonia viridissima (Orthoptera, insecta). 1082 45

The atomic force microscopy (AFM) colloid probe technique was investigated as a method for the characterisation of adhesional properties of pharmaceutical powder surfaces. Lactose carriers used in dry powder inhaler (DPI) formulations were chosen for investigation since adhesion between the carrier surface and drug particles has been proposed to affect the dispersion of drug particles. Individual adhesion forces were determined by measuring the detachment forces in air between the colloid probe and the lactose particle surface. The colloid probe consisted of a silica sphere (10 microm diameter) attached to a V-shaped silicon nitride cantilever (spring constant, k=0.42 N/m). Adhesion forces were calculated from individual force-distance curves using Hooke's Law. Individual forces measured at various adhesion sites were observed to be reproducible and stable over 10 min (coefficient of variation, CV below 5%). The adhesion force distribution determined from measurements at multiple sites (n>50) on each sample followed a log-normal relationship (regression coefficient, r(2) ranged between 0.95 and 0.99). This enabled characterisation in terms of the geometric mean adhesion force and a geometric standard deviation (GSD). Significant differences (P<0.001) in adhesion force were observed between samples, ranging from 37.47+/-1.95 to 117.48+/-2.20 nN. This study demonstrates the suitability of AFM as sensitive technique for the characterisation of adhesional properties of pharmaceutical particles.
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PMID:Characterisation of adhesional properties of lactose carriers using atomic force microscopy. 1137 36

Microelectromechanical systems (MEMS) create an opportunity for the development of smaller, cheaper, and more precise biomedical instrumentation and devices. Little is known, however, about the hemocompatibility of the materials used to fabricate these devices. Because of the potentially harmful consequences of thrombus formation, a better understanding of blood interactions with bioMEMS materials is desirable. This study is an in vitro assessment of the hemocompatibility of silicon (Si), silicon dioxide (SiO2), silicon nitride (Si3N4), low-stress silicon nitride (Si(1.0)N(1.1)), SU-8 photoresist, and parylene thin films. A polycarbonate-based polyurethane, was used as a reference material. Experiments were carried out to detect differences in platelet adhesion or morphology after contact with these materials under static conditions. Platelet adhesion on Si, Si3N4, Si(1.0)N(1.1,) and SU-8 photoresist was significantly greater (P < 0.05) than platelet adhesion on polyurethane. Adhesion on parylene and SiO(2) was not significantly different from on polyurethane (P < 0.05). The median platelet area and circularity were higher on polyurethane than all other materials. Materials that showed higher levels of platelet adhesion tended to have platelets that showed less spreading, except for SiO2, where platelets exhibited relatively low adhesion and spreading. This data suggests that Si, Si3N4, Si(1.0)N(1.1), and SU-8 photoresist may be more reactive to platelets and therefore more thrombogenic than parylene, SiO2, and polyurethane. These results may be helpful in guiding the selection of materials for use in the development of blood-contacting microelectromechanical systems.
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PMID:Hemocompatibility of materials used in microelectromechanical systems: platelet adhesion and morphology in vitro. 1185 35


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