Aging: Interesting facts
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Michelle Magid
{a 2nd year med student, whose site I could not find again}
What is Biological aging?  Ex. At 20, a top athlete is #1 in the world at his sport.  At 35, he is #150. What happened?  Ans. He underwent BIOLOGICAL AGING.

Biological aging is not the same as disease.  What is the cause of Biological aging?  Ans. Unknown

As aging proceeds, the ability to ADAPT becomes impaired. 
If we could eliminate all premature deaths, we would all still die at about 85.  MAXIMUM LIFESPAN IS NOT CHANGED BECAUSE WE WILL ALL UNDERGO BIOLOGICAL AGING.
Trends:  Life expectancy in the US has increased for children under 2, increased for people age 30-40, but has barely increased for people of about age 75.
Why???  We have combated birth complications leading to death of babies, and we can treat illnesses leading to death of middle-aged adults, but we CANNOT GET RID OF BIOLOGICAL AGING.

All organ functions and abilities decrease with age.
Ex. At age 25, we have 6% bone mineral.  At age 70, we have 5% bone mineral.  Thus, as we get older, we are naturally more likely to get osteoporosis.
Ex. An aged mouse will not be able to adapt to increased cold stress.  It's heart will slow down, it won't shiver as much etc? thus it will get sick and die.  A younger mouse will be able to ADAPT better to stressful environments.
Ex. As we age, our vascular system doesn't adapt as well.  Ex-our blood pressure rises as we get older.
Ex. As we age, we cannot ADAPT to increased blood sugar (our blood sugar concentrations will show increase in a cortisone glucose tolerance test.)
Ex. Females are born with 733,000 oocytes. At about age 15, they have 389,300 oocytes.  At age 45, they only have 10,900 oocytes.  Although some of the oocytes are lost in the menstrual cycle, most of the loss of oocytes is due to Biological Aging in the Ovary.

Two mice strains were examined.  The strain with more chromosomal abnormalities had a shorter lifespan.  It was thought that more environmental stress= more chromosomal damage=more biological aging= decreased lifespans.
This theory hasn't held up.  If this theory were true, pilots, who are exposed to radiation, should have decreased lifespans, but they don't.

Lipofuscin increases with age.  Caused by lipid peroxidation (by free radicals for ex.). The accumulation of lipofuscin= Biological aging.  Lipofuscin build-up is a good indicator of free radical oxidation damage being done to cells.  Cells get rid of free radicals via various mechanisms.  If the radicals aren't destroyed, they will slowly cause cell damage.  This may be a factor in Biological aging.

Ex. Non-identical twins have a much larger difference in lifespan than identical twins.  Regular siblings have a larger difference in lifespan than non-identical twins.
A genetic component may be DNA repair mechanisms.  If you increase the amount of DNA repair enzymes, you will increase your lifespan.

HAYFLICK PHENOMENON- normal fibroblasts will grow and divide in a cell culture, BUT at some point, the cells will stop growing (ex at about fifty doublings) regardless of nutrients etc? This is a normal process. (Side note: if you transform the cell with radiation or something, the cell becomes immortal and will NOT stop growing after 50 doublings.  Cell is actually cancerous.  This is not a normal process)
Is Biological aging merely due to the cessation of cells dividing?
Ans: Probably not.  Aging takes its greatest toll on cells that DON'T divide (terminally differentiated cells) such as brain cells.  Aging is not as relevant with continuously dividing cells such as fibroblasts and Gastric mucous cells.
However, there IS a correlation between lifespan and population doublings in vitro. Hmmmm?.

DISEASES: Progeria and Werners- Children age very quickly. They are bald and wrinkled by age 12.
The fibroblasts of these sick children have a fibroblast doubling of about 5, not 50.  Again, there is a correlation between lifespan and population doublings of dividing cells.

There is also something about chromosome 1 that has to do with biological aging.  We are not sure what it is, but it adds evidence that there is a genetic component to Biological aging.

There is a progressive shortening of chromosomes with each chromosomal replication.  You reach a point where the shortening of chromosomes infringes upon the CODING SEQUENCES in the gene.  Thus, the loss of coding sequences may lead to or cause biological aging.  TELOMERASE prevents the shortening of chromosomes with replication.  Coincidentally, there is a lot of telomerase in cancer cells.  Perhaps increased telomerase in a person hinders biological aging, but may also cause cancer.

If we could eliminate all premature deaths, we would all still die at about 85.  MAXIMUM LIFESPAN IS NOT CHANGED BECAUSE WE WILL ALL UNDERGO BIOLOGICAL AGING.


Also on longevity is the article WHY WOMEN LIVE LONGER

Comments by JK

Aging has many causes.  I first seriously studied this topic in 1984, when on a visit to my mother-in- law's, I spent two afternoons at the University of Colorado and purchased there a medical school book which examined the research on aging and the conclusion that could reasonable drawn therefrom.    From my reading of it, I produced typed notes.  Periodically, I returned to this topic.

            Aging is a product of a variety of causes.  At the most basic level it is the product of chemical reactions that occur randomly, at a low frequency, and for which there are imperfect biological mechanism to reduce their frequency, their effect, or to undo their effect.  There are certain reactive chemicals produced as bi-products of reactions (super-oxides, acids, bases, and various oxidizing and reducing agents).  These chemical agents affect the structure of  proteins and thus their shape by breaking certain weak bonds, such as hydrogen bonding and the sulfur-to-sulfur bond between  amino acids.  The result of these changes is a reduction in functions of the proteins and thus of the cells.  A second similar process goes on in the mitochondria, a encapsulated body within the cell where the reactive process of generating ADPTs (our body's energy molecule) occurs.  With age the ability to generate ADPTs declines.  This gradual reduction in functions because of these changes produce the visible and functional changes observed in the aging process.  Blood vessels and skin lose their elasticity, bone become brittle, muscles contract with less force, blood cells survive less days, the number of cells in senescence increase, the production of ADPTs declines, and so on.  Aging is a cumulative process wherein all systems decline. 
     Given that there is no simple cause, there is no magic bullet simple fix.  


Given this fact, those who claim that there are life-extending nutritional supplements should be taken skeptically.  In fact a group of 50 scientists, concerned with the minimally supervision of “food supplements” and the unscientific claims made, a statement was issued to the press then published by Scientific American..