Skin graft or skin flap. Skin grafts or skin flaps are done after the scar tissue is removed. Skin grafts involve replacing or attaching skin to a part of the body that is missing skin. Skin grafts are performed by taking a piece of healthy skin from another area of the body (called the donor site) and attaching it to the needed area. Skin flaps are similar to skin grafts, where a part of the skin is taken from another area, but with the skin flaps, the skin that is retrieved has its own blood supply. The section of skin used includes the underlying blood vessels, fat, and muscles. Flaps may be used when the area that is missing the skin does not have a good supply of blood because of the location or because of damage to the vessels.
Bile acids, in particular chenodeoxycholic acid (CDCA) and cholic acid (CA), can regulate the expression of genes involved in their synthesis, thereby, creating a feed-back loop. The elucidation of this regulatory pathway came about as a consequence of the isolation of a class of receptors called the farnesoid X receptors, FXRs . The FXRs belong to the superfamily of nuclear receptors that includes the steroid/thyroid hormone receptor family as well as the liver X receptors (LXRs) , retinoid X receptors (RXRs), and the peroxisome proliferator-activated receptors (PPARs) .