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

The adhesion of platelets to a series of segmented polyurethanes having sulfonate groups in the hard segment is reported. The polyurethanes were synthesized using sulfonated chain extenders of different structure. Analogous control materials without sulfonate groups also were studied. Adhesion was measured in vitro using washed human platelets in a carrier fluid consisting of Tyrode's buffer with apyrase, albumin, and red cells at normal concentration. The polymers were characterized by gel permeation chromatography and elemental analysis. Water absorption and thermal transitions also were determined. It was found that the sulfonated materials absorb significant amounts of water while the nonsulfonated analogs do not. The surfaces of polymer films were characterized by water contact angle and XPS. The contact angles of the sulfonated surfaces were relatively low. Platelet adhesion to the sulfonated polymers was found to be very high compared to the nonsulfonate analogs. The local environment of the sulfonate groups (different chain extenders) also appears to have an effect on platelet interactions. Albumin adsorption was high on all the materials and was not correlated with platelet adhesion. It appears from this work that platelets may have a binding site that is specific for sulfonate groups.
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PMID:Physicochemical properties and platelet interactions of segmented polyurethanes containing sulfonate groups in the hard segment. 905 28

Leukocyte beta2 integrins Mac-1 and p150,95 are promiscuous cell-surface receptors that recognise and mediate cell adhesion to a variety of adsorbed and denatured proteins. We used albumin as a model protein to study whether leukocyte adhesion and activation depended on the nm-scale topography of a protein adlayer. Albumin adsorbed from the native conformation gave rise to different adlayer topographies and different amounts of adsorbed protein on hydrophobic and relatively hydrophilic polystyrene and silanised silicon-wafer surfaces, whereas adsorption of pre-denatured Alb resulted in similar adlayer topographies and similar amounts of adsorbed protein on these surfaces. All three distinct protein-adlayer topographies supported adhesion of in vitro differentiated, macrophage-like U937 and THP-1 cells, but did not support adhesion of their promonocytic precursors. Human monocytes freshly isolated from peripheral blood did not adhere to adsorbed albumin, not even in the presence of monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha chemokines. Adhesion of the macrophage-like cells to albumin in any of the three topographies was inhibited by antibodies against beta2 integrins, but not by antibodies against beta1 integrins, and did not induce secretion of the proinflammatory cytokine tumour necrosis factor-alpha.
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PMID:The recognition of adsorbed and denatured proteins of different topographies by beta2 integrins and effects on leukocyte adhesion and activation. 1560 99

To prepare for shortage of blood components and to avoid side effects such as blood borne infectious disease, blood substitutes such as artificial red cell (artificial oxygen carrier) and artificial platelet are being developed. As for oxygen carriers, there are several candidates such as perfluorochemicals, modified hemoglobins and liposome encapsulated hemoglobins and albuimin heme. Perfluorochemicals have limited oxygen carrying capacity and oxygen inhalation is mandatory when they are used. Modified hemoglobins such as intermolecular or intramolecular cross linked hemoglobins have side effect to cause hypertension by scavenging nitro oxide (NO) which is produced by endothelial cells, because the size of these hemoglobins are small enough to go to the adjacent place near endothelial surface. Hemoglobin vesicles (HbV) in which hemoglobins are encapsulated in liposome is most possible candidate for oxygen carrier. Usefulness and safety of the HbV is evidenced by animal shock model or exchange transfusion model and they are now being prepared for clinical trials as red blood substitutes or oxygen therapeutics. Albumin heme in which recombinant human serum albumin incorporating synthetic heme is thought an ideal resuscitation fluid as this material has colloid oncotic pressure. Short time storage and viral infection are serious concern in platelet transfusion therapy for bleeding thrombocytopenic patients. Adhesion of the platelet to the collagen surface and aggregation at the bleeding sites to plug holes in blood vessels, and to facilitate the function of the remaining platelets is a starting point in developing platelet substitutes and several platelet substitutes have been proposed on this theory.
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PMID:[Artificial blood]. 1569 96

Self-assembled monolayers (SAMs) of alkanethiols, which can provide flat and chemically well-defined surfaces, were employed as model surfaces to understand cellular interaction with artificial materials. SAMs presenting a wide range of wettabilities were prepared by mixing two kinds of alkanethiols carrying terminal methyl (CH(3)), hydroxyl (OH), carboxylic acid (COOH), or amino (NH(2)) groups. Adhesion behavior of human umbilical vein endothelial cells (HUVECs) and HeLa cells on these mixed SAMs were examined. The number of adhered HUVECs reached a maximum on CH(3)/OH mixed SAMs with a water contact angle of 40 degrees , while cell adhesion increased with decreasing water contact angle up to 60-70 degrees and then leveled off on CH(3)/COOH and CH(3)/NH(2) mixed SAMs. Numbers of adhered HeLa cells showed a maximum on CH(3)/OH and CH(3)/COOH mixed SAMs with a water contact angle of 50 degrees . These facts suggest that cell adhesion is mainly determined by surface wettability, but is also affected by the surface functional group, its surface density, and the kinds of cells. The effect of exchange of adsorbed proteins on cell adhesion was also examined. HUVECs were cultured on the mixed SAMs preadsorbed with albumin. Cell adhesion was effectively prohibited on hydrophobic SAMs pretreated with albumin. Albumin strongly adsorbed and resisted replacement by cell adhesive proteins on hydrophobic SAMs. On the other hand, cells adhered to albumin-adsorbed hydrophilic SAMs. Displacement of preadsorbed albumin with cell adhesive proteins effectively occurs on these hydrophilic SAMs. This effect contributes to induce SAMs with moderate wettability to give suitable surfaces for cell adhesion.
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PMID:Effect of wettability and surface functional groups on protein adsorption and cell adhesion using well-defined mixed self-assembled monolayers. 1742 32