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

The role of lipopolysaccharides (LPS) in bacterial adhesion was investigated via atomic force microscopy (AFM). Adhesion between a silicon nitride tip and Escherichia coli JM109 was measured in water and 0.01 M phosphate-buffered saline (PBS) on untreated cells and on a sample of E. coli treated with 100 mM ethylenediaminetetraacetic acid (EDTA), which removes approximately 80% of the LPS molecules. LPS removal decreased the adhesion affinity between the bacterial cells and the AFM tip from -2.1 +/- 1.8 to -0.40 +/- 0.36 nN in water and from -0.74 +/- 0.44 to -0.46 +/- 0.23 nN in 0.01 M PBS (statistically different, Mann-Whitney rank sum test, P < 0.01). The distributions of adhesion affinities between E. coli LPS macromolecules and the AFM tip could be described by gamma distribution functions. Direct measurements of the adhesive force between E. coil and a surface were compared with adhesion in batch and column experiments, and agreement was observed between the influences of LPS on adhesion in each system. Bacterial batch retention to glass or in packed beds to quartz sand decreased after LPS removal. When interaction forces were measured during the approach of the AFM tip to a bacterium, steric repulsive forces were seen for both treated and untreated cells, but the repulsion was greater when the LPS was intact A model for steric repulsion predicted a reduction of the equilibrium length of the surface polymers from 242 to 64 nm in water and from 175 to 81 nm in buffer, after removal of a portion of the LPS. DLVO calculations based on conventional and soft-particle DLVO theories predicted higher energy barriers to adhesion for all surfaces after LPS removal, consistent with experimental findings. Adhesion forces between the AFM tip and bacterial polymers were correlated with bacterial attachment and retention, while measurements of interaction forces during the approach of the AFM tip to the bacterium did not correlate with subsequent adhesion behavior to glass or quartz sand.
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PMID:Role of lipopolysaccharides in the adhesion, retention, and transport of Escherichia coli JM109. 1278 23

Investigation of MR patients with 3p aberrations led to the identification of the translocation breakpoint in intron five of the neural Cell Adhesion L1-Like (CALL or CHL1) gene in a man with non-specific mental retardation and 46,Y, t(X;3)(p22.1;p26.3). The Xp breakpoint does not seem to affect a known or predicted gene. Moreover, a fusion transcript with the CALL gene could not be detected and no mutations were identified on the second allele. CALL is highly expressed in the central and peripheral nervous system, like the mouse ortholog 'close homolog to L1' (Chl1). Chl1 expression levels in the hippocampus of Chl1(+/-) mice were half of those obtained in wild-type littermates, reflecting a gene dosage effect. Timm staining and synaptophysin immunohistochemistry of the hippocampus showed focal groups of ectopic mossy fiber synapses in the lateral CA3 region, outside the trajectory of the infra-pyramidal mossy fiber bundle in Chl1(-/-) and Chl1(+/-) mice. Behavioral assessment demonstrated mild alterations in the Chl1(-/-) animals. In the probe trial of the Morris Water Maze test, Chl1(-/-) mice displayed an altered exploratory pattern. In addition, these mice were significantly more sociable and less aggressive as demonstrated in social exploration tests. The Chl1(+/-) mice showed a phenotypic spectrum ranging from wild-type to knockout behavior. We hypothesize that a 50% reduction of CALL expression in the developing brain results in cognitive deficits. This suggests that the CALL gene at 3p26.3 is a prime candidate for an autosomal form of mental retardation. So far, mutation analysis of the CALL gene in patients with non-specific MR did not reveal any disease-associated mutations.
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PMID:CALL interrupted in a patient with non-specific mental retardation: gene dosage-dependent alteration of murine brain development and behavior. 1281 75

The ideal surface of an artificial blood purification membrane needs hemocompatibility and durability of high performance; it should not adsorb any proteins or cells but should still have high permeability in the desired range of solute size. To improve the anti-fouling property of cellulose acetate (CA) membranes, a CA membrane blended with poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)) (PMB30) was designed as a blood purification membrane. The polymer solutions for preparing the membrane were prepared using a solvent mixture composed of N, N-dimethylformamide, acetone, 2-propanol or water. The CA and CA/PMB30 blend membranes with an asymmetric and porous structure were prepared by a phase inversion process. The characteristics of the CA/PMB30 blend membrane, such as structural properties, mechanical properties, and solute permeability were examined with attention to changes in the preparation conditions of the membrane. The CA/PMB30 blend membrane had good water and solute permeability and a sharp molecular weight cut-off property. Moreover, the amount of proteins adsorbed on the CA/PMB30 blend membrane surface was less than that of the original CA membrane and a conventional polysulfone membrane. Adhesion and activation of platelets on the CA/PMB30 blend membrane were reduced compared with that on a CA membrane. In addition, the CA/PMB30 blend membrane showed good permselectivity and an antifouling property during a long time ultrafiltration experiment with protein solutions.
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PMID:Antifouling blood purification membrane composed of cellulose acetate and phospholipid polymer. 1285 44

Adhesion partitioning is a method for progressively dismantling small biological entities for observation of their internal structures. The method is particularly well suited to use with the electron microscope. Objects to be partitioned are air-dried between two preformed plastic films resulting in envelopment of the objects. On separating the films the objects are partitioned. Partitioned E. coli bacteria reveal a variety of structures which change markedly with culture age. Organisms from young cultures have a water-retaining gelatinous matrix in which radially striated discs, fabric-like structures, and microsomes are found. Older cultures are less anatomically complex. The T2 bacteriophage is shown to be composed of an outer limiting membrane and a cohesive semisolid fibrillar body substance, presumably nucleic acid, which can be drawn as a strand from the bacteriophage body.
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PMID:Adhesion partitioning: intrasomatic observations on normal Escherichia coli and T2 bacteriophage. 1438 32

Self-assembling oligopeptides are novel materials with potential bioengineering applications; this paper explores the use of one of these oligopeptides, EAK 16 II, for modifying the surface properties of cell-supporting substrates. To characterize the surface properties, thermodynamic measurements of liquid contact angle and surface free energy were correlated to atomic force microscopy (AFM) observations. A critical concentration of 0.1 mg/ml was found necessary to completely modify the surface properties of the substrate with EAK 16 II. Adhesion of a yeast cell, Candida utilis, was modified by the coating of EAK 16 II on both hydrophobic (plastic) and hydrophilic (glass) surfaces: Cell coverage was slightly enhanced on the glass substrate, but decreased significantly on the plastic substrate. This indicates that the yeast cell adhesion was mainly determined via hydrophobic interactions between the substrate and the cell wall. However, on the EAK 16 II modified glass substrate, surface roughness might be a factor in causing a slightly larger cell adhesion than that on bare glass. The morphology of adhered cells was also obtained with AFM imaging, showing a depression at the center of the cell on all substrates. Small depressions on the oligopeptide-coated surfaces and plastic substrate may indicate good water-retaining ability by the cell. There was no apparent difference in cell adhesion and morphology among cells obtained from lag, exponential and stationary growth phases.
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PMID:Yeast cell adhesion on oligopeptide modified surfaces. 1449 22

This work has dealt with the in vitro physicochemical, elastic, and microbiological properties of polymer lining materials used in dental prosthetics. Representatives of two soft polymer groups were analyzed: Vertex Soft NF, a plastified acrylic polymer, and Molloplast B, a silicon elastomer. Vertex Rapid Simplified and Triplex--two acrylic polymers routinely used at the Department of Prosthetic Dentistry were chosen as representatives of rigid acrylic material. The laminar plates of the denture are lined with elastic material to reduce wear discomfort and eliminate symptoms associated with compression of the oral mucosa by the denture. Wear-dependent deterioration in physicochemical, elastic, and microbiological properties presents as prosthetic stomatopathies due to the combined action of mechanical lesions, fungal growth, and toxicity of components of the denture, necessitating replacement of the denture. Samples used in this study were prepared at the Department of Dental Prosthetics, Pomeranian Academy of Medicine. The process of polymerization was carried out strictly as recommended by the manufacturers. The in vitro analyses were done at the Polymer Institute, Technical University of Szczecin, and the Department of Microbiology and Immunology, Pomeranian Academy of Medicine. A special system was used to reproduce conditions in the oral cavity and study their effects on the elastic liners. Samples were placed in the chamber for varying periods, depending on the type of test and material. Thermodynamic analysis was done to confirm proper polymerization and hardening. Time-dependent loss of contact between the elastic liner and rigid denture under tangential (shear) and normal (tear) stress applied to the liner-denture interface was examined. Resistance was studied using INSTRON model 4206-006 universal testing machine. Compressive changes in elastic properties of the soft materials were examined by calculating Young's modulus. Changes in viscoelastic properties of the materials depending on temperature and frequency were followed using dynamic mechanical thermal analysis (DMTA). A precision microbalance from Sartorius (+/- 0.00001 g) was used to measure time-dependent changes in weight and sorption of water. Adhesion of Candida albicans to the rigid and soft acrylic materials was determined after incubation for 3, 6 or 24 h at 37 degrees C. The study has shown that adhesive strength is much greater for acryl-acryl than acryl-silicon interface. Elastic properties of Molloplast B are very stable and superior to those of Vertex Soft NF. Time-dependent sorption of water and changes in weight have confirmed the stable nature of Molloplast B. Adhesion of Candida albicans to Vertex Soft NF was less noticeable.
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PMID:[Comparative analysis of elastic materials for lining of removable dental prosthesis in vitro]. 1460 76

Adhesion promoting monomers for dental metals, 5-(4-vinylbenzyl)-2-thiobarbituric acid (5VS), 6- (4-vinylbenzyl-n-propyl) amino-1,3,5-triazine-2,4-dithione (VBATDT) and 9,10-epithiodecyl methacrylate (EP8MA), were synthesized and surface treatment agents were prepared by dissolving each monomer in ethanol or acetone. Four non-precious and three precious metal adherends treated with each agent were butt-jointed together with MMA-PMMA resins. After 2,000 thermal cyclings in water, tensile bond strengths were measured and the percentage of area of cohesive failure after the tensile test was determined. The bond strengths to precious metal alloys generally increased in the order of 5VS<VBATDT<EP8MA. Bonding durability against water based on overall failure mode analysis was improved in the following order: for precious metal alloys; 5VS<VBATDT< or =EP 8MA, and for non-precious metal alloys; EP8MA, VBATDT<<5VS.
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PMID:Chemical structures of adhesion promoting monomers for precious metals and their bond strengths to dental metals. 1462 Oct

Biocompatibility of biomaterials relates, amongst others, to the absence of adverse cellular reactions and modulation of cell adhesion and subsequent responses. With respect to tissue-engineering applications, most materials need to evoke cell adhesion and spreading, while potentially displaying differential cell function. Adhesion has frequently been studied in a controlled fashion, using adhesion-supporting and -inhibiting substrata. The aim of this study is to create a panel of related materials with gradually changing surface characteristics in order to sustain similar individual cell adhesion and spreading, yet different cell population behaviour. A series of polystyrene materials was created with increasing oxygen surface incorporation and, concurrently, decreasing water-contact angles. Individual cells adhered and spread on all surfaces whilst showing well-developed focal adhesions and stress fibres. Cell populations demonstrated a decreased growth on surfaces with lower wettability. The biochemical activity of cell populations was not influenced by the surface treatment, but cell proliferation on surfaces increased with increasing oxygen incorporation. Furthermore, surface coverage with assembled fibronectin matrix was higher on the substrata with higher wettability. Finally, the expression of the adhesion-related proteins cadherin-5, focal adhesion kinase and RhoA was increased on surfaces with higher wettability. Further explorations of the cell biological basis of the observed differential behaviour will give more detailed answers on the rules governing cell-material interactions.
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PMID:Plasma-treated polystyrene surfaces: model surfaces for studying cell-biomaterial interactions. 1473 36

Adhesion of three marine bacterial strains, i.e. Marinobacter hydrocarbonoclasticus, Psychrobacter sp. and Halomonas pacifica with different cell surface hydrophobicities was measured on glass in a stagnation point flow chamber. Prior to bacterial adhesion, the glass surface was conditioned for 1 h with natural seawater collected at different seasons in order to determine the effect of seawater composition on the conditioning film and bacterial adhesion to it. The presence of a conditioning film was demonstrated by an increase in water contact angle from 15 degrees on bare glass to 50 degrees on the conditioned glass, concurrent with an increase in the amount of adsorbed organic carbon and nitrogen, as measured by X-ray photoelectron spectroscopy. Multiple linear regression analysis on initial deposition rates, with as explanatory variables the temperature, salinity, pH and concentration of dissolved organic carbon (DOC) of the seawater at the time of collection, showed that the concentration of DOC was most strongly associated with the initial deposition rates of the three strains. Initial deposition rates of the two most hydrophilic strains to a conditioning film, increased with the concentration of DOC in the seawater, whereas the initial deposition rate of the most hydrophobic strain decreased with an increasing concentration of DOC.
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PMID:The effect of dissolved organic carbon on bacterial adhesion to conditioning films adsorbed on glass from natural seawater collected during different seasons. 1476 68

There is current concern about bacterial contamination of dental unit waterlines. This research hypothesized that the presence of increasing concentrations of bacteria in water used to wash etched enamel would result in a corresponding decrease in both shear bond strength (SBS) and critical surface tension (gammaC) of enamel. A further hypothesis was made that there is a correlation between SBS and gammaC. The effect of 3.5 ppm iodine in the water as a bacteriostatic agent was also assessed. Five groups of 10 samples of bovine enamel were etched, washed, and a resin composite bonded to them. The control group was washed with distilled water. Another group was washed with the dilute iodine solution. The remaining three groups used a different concentration of Escherichia coli DH5alpha as follows (in cfu mL(-1)): group 1: 10(2); group 2: 10(4); group 3: 10(6). Shear bond strength data were measured on an Instron testing machine at a crosshead speed of 1 mm min(-1). Adhesion data were (MPa): control: 24.6 +/- 6.0; with iodine: 20.8 +/- 2.7; group 1: 19.8 +/- 2.7; group 2: 13.5 +/- 3.0; group 3: 13.9 +/- 3.6. The F-test yielded a highly significant difference between control group, iodine group and group 1, compared with groups 2 and 3 (P < 0.0001). Tukey's Studentized Range Test was used for pairwise comparison testing between groups. Using a Cahn dynamic contact angle analyzer and linear regression analysis, the plots of surface tension versus costheta were extrapolated to costheta = 1 to give gammaC data for the control group and groups 1-3. In all cases reasonable linearity was observed (r2 > or = 0.87). Data (mN m(-1)) were: control group: 50.8; group 1: 45.1; group 2: 43.2; group 3: 39.5. The SBS and gammaC were then plotted against each other and linear regression analysis performed. It was concluded that increasing concentrations of bacteria in wash water decreased both SBS and gammaC and that a linear correlation (R2 = 0.84) was found between the values of these two parameters.
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PMID:The effect of washing water on bonding to etched enamel. 1512 3


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