Cell adhesion agent

The extracellular domain of cadherins consists of a variable number of a repeated sequence of about 110 amino acids. This sequence is termed the cadherin repeat and resembles in overall structure, but not in sequence, the Ig like domains. The cadherin repeat is the characteristic motive common to all members of the cadherin superfamily. Classical and desmosomal cadherins contain five cadherin repeats, but as many as 34 repeats have been found in the FAT cadherin (see below). Cadherins are calcium-dependent cell adhesion molecules, which means that removal of Ca2+, e.g., by chelating agents such as EDTA, leads to loss of cadherin function. The Ca2+-binding pockets are made up of amino acids from two consecutive cadherin repeats, which form a characteristic tertiary structure to coordinate a single Ca2+ion [1]. 

Some active materials are carriers for drugs (drug delivery systems), some have immobilized peptides to enable cell adhesion or migration, some are degradable by hydrolysis or by specific enzyme action. Some contain bioactive agents (e.g., heparin, thrombomodulin) to prevent coagulation or platelet activation while others incorporate bioactive groups to enhance osteo-conduction. Many include polyethylene oxide to retard protein adsorption and this is perhaps the closest we have come to a kind of inertness. 

This chapter will provide an overview of the research on anti-adhesion agents. Particular attention will be devoted to the anti-adherence agents derived from or foimd naturally in foods. In addition, the pathogen infection process, the architecture of host epithelial cell surfaces, and the chemistry and mechanisms involved in bacterial interactions with host cell surfaces will also be reviewed. 

The dimensional stability of low density, water blown rigid PU foams for pour-in-place thermal insulation applications was improved by the use of a phthalic anhydride based polyester polyol containing a dispersed cell opening agent. The foam systems obtained allowed some of the carbon dioxide to be released through the cell windows immediately after filling of the cavity, and to be rapidly replaced by air. Studies were made of the flowability, density, open cell content, dimensional stability, mechanical properties, thermal conductivity and adhesion (particularly to flame treated PE) of these foams. These properties were examined in comparison with those of HCFC-141b blown foams. 21 refs. 

Carbohydrate-mediated cell adhesion is an important event which can be initiated by tissue injury or infection and is involved in metastasis. One such adhesion process is the interaction between the glycoprotein E-selectin and oligosaccharides on the surface of neutrophils (white blood cells). The ligand that E-selectin recognizes is the tetrasaccharide sialyl Lewis X (SLe ). Since SLe competes with white blood cells for binding to E-selectin, thus inhibiting the adhesion process, it may useful as an anti-inflammatoiy and anticancer agent. 

Silva et al. (2006) studied starch-based microparticles as a novel strategy for tissue engineering applications. They developed starch-based microparticles, and evaluated them for bioactivity, cytotoxicity, ability to serve as substrates for cell adhesion, as well as their potential to be used as delivery systems either for anti-inflammatory agents or growth factors. Two starch-based materials were used for the development of starch-based particulate systems (1) a blend of starch and polylactic acid (SPLA) (50 50 w/w) and (2) a chemically modifled potato starch, Paselli II (Pa). Both materials enabled the synthesis of particulate systems, both polymer and composite (with BG 45S5). A simple solvent extraction method was employed for the synthesis of SPLA and SPLA/BG microparticles, while for Pa and Pa/BG... 

Jurkat cells have been lysed in a flow stream in a glass microchip for cell content analysis. After cell lysis, the two preloaded fluorescent dyes and their metabolites were released from the cells and separated by CE (see Figure 8.36). To prevent cell adhesion, the glass channel surface was modified by adsorbing Pluronic F-127 to the channels. In addition, to avoid blockage of adhered cell debris and to improve migration time stability, an emulsification agent, such as Pluronic P84, was added to the separation buffer [1176],... 

For the subculture of adherent cells, removal of culture medium and the detachment of cells from the monolayer are necessary. This detachment is usually performed with trypsin, but other proteases, such as pronase, dispase, and collagenase, can be employed. In general, a chelating agent, such as EDTA, is also added to capture the Ca2+ ions involved in the cell adhesion process. Some cell lines bind weakly to surfaces and, in small-scale cultures, can be removed mechanically by gently tapping or hitting the culture flask by hand. 

---