Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0268596 (EMA)
 2,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibrinogen adsorption from blood to biomaterials may regulate platelet adhesion and thrombus formation because of fibrinogen's central role in the coagulation cascade and its ability to bind specifically to the platelet membrane glycoprotein (GP) IIb-IIIa. Adsorption of fibrinogen from blood plasma to many materials exhibits a maximum with respect to plasma dilution and exposure time (the Vroman effect). In this study fibrinogen adsorption to several polymers was examined to ascertain the influence of controlled changes in surface chemistry on the Vroman effect. The materials included hydroxyethylmethacrylate-ethylmethacrylate (HEMA/EMA) copolymers, Biomer, and a series of segmented polyurethanes (PEUs), two of which contained fluorinated chain extenders. Each material exhibited maximal adsorption of fibrinogen at intermediate plasma concentrations. Little effect of soft-segment type or molecular weight was observed and no significant differences in fibrinogen adsorption to the fluorinated PEUs were seen. Changes in the strength of fibrinogen attachment to these materials with time after adsorption were also assessed. Fibrinogen adsorbed for 1 min was displaced more readily by blood plasma than that adsorbed for 1 h, regardless of the material. The more hydrophobic polymers exhibited greater retention of adsorbed fibrinogen. In addition, the fraction of fibrinogen retained by polyethylene depended on the amount of fibrinogen adsorbed to the surface, being greatest when the surface loading was the least. These studies indicate that spreading or transition of adsorbed fibrinogen molecules from a weakly to tightly bound state is a general consequence of protein adsorption to solid surfaces.
 ...
PMID:Changes in fibrinogen adsorbed to segmented polyurethanes and hydroxyethylmethacrylate-ethylmethacrylate copolymers. 148 67

Plasma protein adsorption is an important initial event in the response of tissue to foreign materials. Little is known about the way in which the chemical properties of materials influence the nature of the adsorbed layer and thus the later cellular responses. In this study, the amounts of fibrinogen, immunoglobulin G, albumin, and hemoglobin adsorbed from plasma to a series of HEMA-EMA random copolymers varying in hydrophilicity was measured. The adsorption of each protein varied in a characteristic way with copolymer composition probably reflecting a different affinity of the proteins for the various copolymers. A complex variation in the composition of the adsorbed protein layer on polymers varying in hydrophilicity was thus evident. Surface enrichment of the proteins, calculated as the ratio of the surface and bulk fraction of each protein, also varied with copolymer composition, and indicated substantial differences in the composition of the surface and bulk phases. Surface area variations among the copolymers, preferential adsorption of 125I proteins, and the possibility of structural degradation of 1,25I proteins in plasma were investigated but did not appear to influence the adsorption results. The ability of polymers to fractionate plasma proteins and concentrate them at their surface is concluded to be a key factor in the complex processes which determine the compatibility of polymers in vivo.
 ...
PMID:Adsorption of proteins from plasma to a series of hydrophilic-hydrophobic copolymers. II. Compositional analysis with the prelabeled protein technique. 1265 35