Biomedical Engineering Reference
In-Depth Information
Fig. 3
Mechanism of adhesion molecule expression in endothelial cells by oxidized LDL.
Oxidized LDL binds to endothelial receptors (including scavenger receptors) and activates an
intracellular signal transduction pathway that induces the expression of adhesion molecules on
endothelial cells. LDL, low-density lipoprotein; PA
, protein kinase A; PKB, protein kinase B;
NF-kB, nuclear factor-kappaB.
LDL receptors and instead is recognized only by scavenger receptors. Cu-LDL is
obtained by incubating LDL with CuSO
4
in phosphate-buf ered saline at 37°C. h e
concentration of LDL and CuSO
4
and the incubation time required for reaction
vary among studies (Gebuhrer
et al
. 1995, Cominacini
et al
. 1997a, b, Takei
et al
.
2001, Matsumoto
et al
. 2003).
Minimally modii ed/oxidized LDL (MM-LDL) is LDL that is less drastically
oxidized than Cu-LDL.
In contrast to Cu-LDL, MM-LDL is recognized by
LDL receptors but not scavenger receptors. MM-LDL is produced by enzyme
modii cation using soybean lipoxygenase and phospholipase A
2
or by mild
oxidation with iron. h e levels of thiobarbituric acid-reactive substances are
assayed to determine the lipid peroxide levels in the Ox-LDL samples. h e level
seen in MM-LDL is dei ned as less than 10 nmol malondialdehyde/mg LDL
protein.
