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kenel

Why do we age?

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I've just encountered two different theories on why we age, which are as follows:

 

(a) Our cells are programmed to make us grow, and at a certain point they are programmed to make us die.

 

and

 

(b) Our DNA is constantly being assaulted and damaged by reactive oxygen species. As we age, this damage reaches critical mass and our spoiled cells essentially commit suicide, taking us with them.

 

Which do you agree with, and why?

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My theory is... since telomeres (the caps of DNA that prevents unwinding (aka degrading)) are constantly becoming shorter, when they become very short, apoptosis (cell suicide) is triggered, in turn causing aging. It is my contention that treating cells with viruses programmed to increase telomerase production will inhibit apoptosis without causing tumors, as is associated with extreme cell growth. It's a bit more than a theory, it's already been shown to dramatically increase cell life, and is under review to treat signs of aging. I believe this may be applied to all cells that have shortening telomeres as an apoptosis activator, and in turn slow down the aging process.

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Do you think it is possible to achieve immortality by engineering these cells not to die off?

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It would take a lot more than just stopping cell suicide, but it's an important step.

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Um, well, in pre-flood times people lived alot longer. This of course, has no scientific basis other than the hebrew Bible and a few summarian texts.

 

--:cool:

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Guest Optimus B

fafalone is right on the money about the telomeres. all "normal" cells have telomeres that are shortened every time a cell divides such that the maximum number of replications is ~50 (the Hayflick limit). tumor cells are so prolific since they can replicate far past the Hayflick limit.

 

B

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Blike, about the "pre-flood" times, age had no relevance, and was not counted like it is today. In the bible, age is used to show wisdom, the older the person, the more wise he/she is. They actually (most likely) lived shorter lives than today's generations.

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What about injections of young stem cells to regenerate organs that are wearing out? Even brain cells could could be used to keep us alert as we age long past our normal lifespan.

Just aman

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It will be "unethical" to prolong human life in healthy people using stem cells and telomerase therapy for the forseeable future. Not that I'm going to let ethics stop me from researching it tho :)

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I don't have any problem with extending the lives of exceptionally useful people. I hate to see a lifetime of scientific experience lost just because a researcher gets old.

Just aman

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What about head transplants ;) A monkey lived a couple weeks once after having its head transplanted... hmm...

 

lol

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I think when we beat cancer and alzhimers, we have an open door to keeping people potentially healthy for very extended lifetimes. Next would be the problem of traumatic death.

Just aman

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As we get older our hypothalamus atrophies. Apparently there is now some evidence that aging may be a result of this. ie. The hypothalamus is no longer boosting the immune system and cell repair and growth diminishes.

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I think a hypothalamus could be transplanted without changing the personality of the recipient. Also a medula oblongota since it is lower brain. The upper brain though needs all its original connections.

Just aman

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Originally posted by aman

What about injections of young stem cells to regenerate organs that are wearing out? Even brain cells could could be used to keep us alert as we age long past our normal lifespan.

Just aman

 

This can never be used to fix problems in nerve cells (neurons), because their wearing off has nothing to do with telomers and proliferation. It might, however, help correcting neurological disorders caused by the limited proliferation of glial cells.

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Originally posted by aman

I think a hypothalamus could be transplanted without changing the personality of the recipient. Also a medula oblongota since it is lower brain. The upper brain though needs all its original connections.

Just aman

 

Actually, all parts of the brain need their original connections. These connections are vital for the internal regulation and functioning of the organs (e.g.: regulating heart beat). The cells of the nervous tissue are unique in their structure. They are very long with a cell body in one part of the brain and an ending in another part or even outside the brain and spinal cord. You can't just cut a part that contains an arbitrary number of cells and replace it with others. Each cell is unique in the brain because of it's path and connections.

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Pleased to meet you Ahmad,

If a body was on major life support while a damaged medula oblongata was removed and a new one was transplanted in with stem cells at the old connection sites, do you think the connections could regenerate and the transplant be useful?

Granted this is in the future a ways since we are still working on stem cell therapy and also the life support would involve regulating every organ and gland from the upper brain down for a substantial time.

Maybe stem cells could just rebuild an entire medula oblongota? Trying to rebuild anything higher might make you younger also but it would risk making you a different person.

Just aman

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Hi aman, pleased to meet you too.

 

The major problem in such a transplant would be restoring the original connections. If you could do that, you will be probably able to restore the problems.

 

What makes any part of the brain disticnt and unique is its connections. When you call a certain part of the brain a "cardiovascular center", for example, you mean that it is where specific connections are made from and two specific parts of the brain and viscera, and these connections are what determines the properties of that center.

 

So if you want to transplant any part of the brain, you must make sure that each and every nerve fiber is connected in the right manner and the right place. Any small change means that you'll get bizarre effect. Imagine how can you survice if when you try to send a nerve impulse to your hand to move it, it will be sent to the heart increasing its rate!

 

Besides, if you cut nerve fibers in the middle, you are actually cutting neurons' axons. In order for the axons to come back together, they must be really accuratly aligned. When you have a lot of cut axonds on two sides, how would you make each axon find its other part and connect with it correctly?

 

Now, regarding stem cells, you must first understand that connections between the brain parts and the viscera are made because of the varying rates of development of the different parts of the body and the effect that each part creates on the other parts. It is like a very advanced unpacking mechanism. The simplist part to understand is how each nerve fiber finds its organ? Actually, it doesn't. Nerve fibers are already there in the organs in the first place, and as the embryo (or the born child) grows in size, the organs start to move away in different directions, each dragging with it its nerve fibers.

 

So nerve cells do not contain specific directions that tech them how to form the different connections, eliminating the possibility of using stem cells.

 

Now think about the kidney. It is a highly modularized organ. It has all its mass of cells in a single specific place, with a specific entrance and exit for blood and an exit for urine. You can easily remove a kidney from one person and put it in another and all you have to do is to make the three connections (artery, vein, ureter). Of course, i'm being very general. Kidney transplats are not something that easy to do successfully.

 

The same thing for using stem cells to replace the kidney tissue. It has a specific place and a very general organization, so if you can just put some cells in that place they will function without so much need for any special arrangement.

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Thanks Ahmad,

It seems we have a lot of ways of cheating aging with most of the organs and a little promise with parts of the nervous system where connections are clear or simpler out of the major bundles.

Kenels question started with what causes aging. Since the nervous system is the main stumbling block, and it starts out with such vast reserves of cells to begin with, why doesn't the brain last forever?

Just aman

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You forgot to include that brain cells cannot be replicated, and that they self destruct all the time...either that or I have overlooked it,....many many posts and I'm a slow reader, so sorry if it's been said.

 

When you think about it it makes sense. You live longer you may systematically overpopulate the world, likke now for example.

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Strife, you are wrong.

 

Brain cells do replicate. A study was done which discovered newly made brain cells within a 40 year old man, don't ask me about the specifics.

 

Nature evens itself out, any one species cannot overpopulate the world before its resources run out and its numbers decrease.

 

We die because natural processes cannot support a life form for so long. There is no need for a feble creature that must be supposred by others.

 

When women enter metapause (beofre which they would have had children if it weren't for society) the body begins to decay... as if saying, "okay, you have served your purpose, chances are you won't at this age, its time to go".

 

Does anybody oppose this view point?

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Fully differentiated brain cells do not divide at all. Neurogenesis is the result of a very small number of neural stem cells that persist in adulthood, particularly in the hippocampus.

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