SUNDAY POST- JAN 4-10
SANJAY SATPATHY
Every living being has a fixed life span. A living organism consists of different organs which are built up of billions of cells which undergo dying and multiplying process every hour every minute. The balance between cell production and cell death (apoptosis) is the key to a healthy system. A German scientist Karl Vogt Karl was first to describe the principle of apoptosis in 1842. We are most grateful to Professor James Cormack of the Department of Greek, University of Aberdeen, for suggesting this term. The word “apoptosis” is used in Greek to describe the “dropping off” or “falling off” of petals from flowers, or leaves from trees.
In a healthy adult human being billions of cells die in the bone marrow, skin and intestine every hour. It seems remarkably wasteful for so many cells to die, especially as the vast majorities are perfectly healthy at the time they kill themselves. What purposes does this massive cell death serve, we do not know? Excessive apoptosis causes shrinkage, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer.
In healthy adult tissues, cell death exactly balances cell division. Just as you scrape your tongue every morning with your tongue cleaner the number of cells you remove are replaced exactly by the same number of cell by next morning. If this were not so, the tissue would grow or shrink. Just to site an example we would remove a part of a liver in a rat, liver cell proliferation increases to make up the loss. Conversely, if a rat is treated with a drug called Phenobarbital, which stimulates liver cell division (and thereby liver enlargement)—and then the Phenobarbital treatment is stopped, apoptosis in the liver greatly increases until the liver has returned to its original size, usually within a week or so. Thus, the liver is kept at a constant size through the regulation of both the cell death rate and the cell birth rate.
Programmed cell death in plants has a number of molecular similarities to that of animal apoptosis, but it also has differences, notable ones being the presence of a cell wall and lack of an immune system that removes the pieces of the dead cell.
To understand a disease process let’s see what would happen if apoptosis become wayward. As a pathway is more or less sequential in nature, it is a victim of causality; removing or modifying one component leads to an effect in another. In a living organism, this can have disastrous result, often in the form of disease or disorder. A discussion of every disease caused by modification of the various apoptotic pathways would be impractical, but the concept overlying each one is the same. The normal functioning of the pathway has been disrupted in such a way as to impair the ability of the cell to undergo normal apoptosis. This results in a cell that lives past its “use-by-date” and is able to replicate and pass on any faulty machinery to its progeny, increasing the likelihood of the cell’s becoming cancerous or diseased. Many think gene, stress, environment and food habits play a vital role in this.
To simplify this cellular death or mass suicide or apoptosis let’s try to understand that nature/God has his own system of bidding farewell to the old and bring in new life for a better environment and a young ,fit and exciting world. In multi-cellular organisms, cells that are no longer needed or are a threat to the organism are destroyed by a tightly regulated cell suicide process known as programmed cell death or apoptosis. Apoptosis is a very complex process (caspases) beyond the scope of this article. The activation process and the breaking system of cells are a mystery of God, like so many living or non living objects of the world. The medical man should not boast off as a very intelligent being to know the mysteries of life but we must remember that we the medical men know only 0.01% of the universe.
The writer was joint director (medical) SAIL