Biomedical Engineering Reference
In-Depth Information
Fig. 7.1 PS externalization [ 9 , 10 ] in the apoptotic cell membrane. Early in the apoptotic process
there is a rapid redistribution and exposure of phosphatidylserine (PS) on the cell surface mediated
by the enzyme scramblase. Due to specific lipid properties, especially intrinsic curvature, the PS
concentration varies between inner and outer leaflets on lipid monolayers in a membrane. PS is
normally restricted to the inner leaflet of the lipid bilayer by an ATP dependent enzyme called
flippase (translocase). Flippase, in concert with a second ATP-dependent enzyme, floppase, that
pumps cationic phospholipids such as phosphatidylcholine (PC) and sphingomyelin to the cell
surface, maintains an asymmetric distribution of different phospholipids between the inner and
outer leaflets of the plasma membrane. This figure is redrawn in light of the model diagram and
description of the general apoptosis process presented in Refs. [ 9 , 10 ]
other human health situations (e.g. transplantation) and human pathologies including
neurological disorders and cardiovascular disease. In addition, we envision a role for
an animal-based apoptosis imaging model in drug development of novel aptamer-
based therapies. It is worth stressing that computational design of aptamers is not
restricted to targets relevant to apoptosis, but can be employed in any situation where
a well-characterized molecular target is known.
7.2 Lipid Membrane Binding of Prion Proteins
Creutzfeldt-Jakob disease (CJD) is a neurodegenerative disease that is incurable and
invariably fatal. CJD is sometimes called a human form of the mad cow disease, given
that bovine spongiform encephalopathy is believed to be the cause of variant CJD
in humans. CJD is the most common among the types of transmissible spongiform
encephalopathy found in humans. In CJD, the brain tissue develops holes and takes
 
Search WWH ::




Custom Search