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Biomedical subjects

Tarek M Fahmy

Publications and source records attributed to Tarek M Fahmy.

2 recordsLinked to original sources

Surface modification of biodegradable polyesters with fatty acid conjugates for improved drug targeting.

We describe a general method for incorporating target ligands into the surface of biocompatible polyester poly(lactic-co-glycolic acid) (PLGA) 50/50 materials using fatty acids. Avidin-fatty acid conjugates were prepared and efficiently incorporated into PLGA. Avidin was chosen as an adaptor protein to facilitate the attachment of a variety of biotinylated ligands. We show that fatty acid preferentially associates with the hydrophobic PLGA matrix, rather than the external aqueous environment, facilitating a prolonged presentation of avidin over several weeks. We successfully applied this approach in both microspheres encapsulating a model protein, bovine serum albumin, and PLGA scaffolds fabricated by a salt-leaching method. Because of its ease, generality and flexibility, this strategy promises widespread utility in modifying the surface of PLGA-based materials for applications in drug delivery and tissue engineering.

Absorbable Implants↗

Probing T cell membrane organization using dimeric MHC-Ig complexes.

In this report, we review a novel method for probing the membrane organization of T cells using dimeric major histocompatibility complexes (MHC), MHC-Ig. MHC-Ig complexes are useful reagents for quantitative analysis of binding data since their valency is controlled. These complexes can be easily labeled and loaded with a variety of peptides. A binding assay using these dimers and quantitative analysis of the MHC-Ig dimer-T cell binding curves is described in detail. Using this approach, we show that the organization of TCR on activated T cells is different from TCR organization on nai;ve T cells. The implications of these findings are discussed with regards to current models of T cell recognition. This analysis offers insight into how T cell controls their biological range of responsiveness. Specifically, these findings reveal the biophysical basis of the ability of activated T cells to recognize low amounts of antigen independent of costimulation.

Animals↗