It has always been argued that breakdown in homeostasis is the real cause of disease. This point is amply illustrated by the recent PNAS article that correlated the miniscule amounts of copper in the mice diet with A-beta clearance and would have an implication for Alzheimer’s disease. In this case, the presence of copper affected the low-density lipoprotein receptor-related protein 1 activity which is responsible for clearing Ab- across the blood brain barrier. Additionally, the copper inside the brain, affected the inflammation tone in the brain and may further accentuate the effect of copper.
However, copper is an essential nutrient. It is a critical cofactor for many enzymes: oxidase such as catechol oxidase, galactose oxidase, bilirubin oxidase and the important superoxide dismutase. How the right balance of copper is achieved and maintained may be the critical factor in disease vs normal individuals.
As we look across biological systems, homeostasis seems to be the critical factor in the balancing act. Wonder how much attention should an engineer pay to homeostasis when creating a robotic systems? Right now the check and balance is primarily regulated by the operator but sensors regulating the activity of critical components might be important as our design systems get complex.