" Fame may be fleeting but obscurity is forever ".
----- Original Message -----
From: Jerry W. Decker <jdecker@keelynet.com>
To: <interact@keelynet.com>
Sent: Thursday, February 17, 2000 3:24 PM
Subject: More on Telomerase & immortal cells
> Hi Folks!
>
> More information about using telomerase to 'immortalize'
> cells to treat various diseases;
>
>
http://my.netscape.com/news/TopStories/02_17_2000.rontz1412-story-bcnewsscie
nceliver.html?cp=aim
>
> Immortal Cells May Be Key to Cirrhosis-Researchers
>
> WASHINGTON (Reuters) - Helping liver cells to become a
> little more immortal may be the key to treating liver
> disease, two teams of researchers reported on Thursday.
>
> One team made liver cells live longer by renewing little
> caps that protect the genetic material in cells, while a
> second team gave liver cells temporary immortality to help
> make a grow-your-own liver transplant for rats.
>
> This could mean that intense study aimed at understanding
> the aging process might also lead to new treatments for
> liver cirrhosis and other chronic diseases, the researchers
> said.
>
> The caps are called telomeres, and they are found on the
> ends of the chromosomes that carry the genes. Each time a
> cell divides, the telomeres become a little more frayed.
> Eventually, they becomes so damaged that the cell dies.
>
> Sometimes cells can secrete an enzyme called telomerase that
> helps prevent this damage. It seems to be linked to the
> out-of-control cell growth that marks cancer, but
> researchers are also looking at ways to use telomerase to
> reverse some aspects of the aging process.
>
> Dr. Ron DePinho of the Dana-Farber Cancer Institute and
> Harvard Medical School in Boston and colleagues showed that
> telomere damage may be the cause of cirrhosis of the liver,
> the world's seventh leading cause of death by disease.
>
> ``Telomerase therapy may be useful for a wide spectrum of
> chronic diseases, including cirrhosis,'' he said in a
> statement.
>
> DePinho said more work needs to be done, but it offers a new
> approach to treating not only cirrhosis, but a whole range
> of degenerative diseases, including AIDS and leukemias.
>
> Liver cirrhosis is caused by hepatitis, heavy drinking,
> parasitic infections and other damage to the liver. It takes
> years to develop because liver cells, known as hepatocytes,
> can regenerate many times.
>
> But eventually they become scarred and worn and the liver
> loses its ability to filter out toxins. Fluids can build up,
> causing swelling known as edema, the heart can be damaged
> and even brain damage can result.
>
> Scientists have wondered whether the telomeres in the
> hepatocytes were becoming worn out as they frantically
> regenerated to repair the damage caused by disease or
> drinking.
>
> ``The effects of alcohol or infection create so many cycles
> of cell damage and regeneration that the cells essentially
> run out of telomeres,'' DePinho said.
>
> ``The cells can no longer divide and, when they die, they
> stimulate the production of scar tissue.''
>
> His team experimented with mice, damaging their livers with
> chemicals and seeing how long it took the liver cells to
> stop regenerating and for cirrhosis to begin.
>
> Then they genetically engineered mice to make their liver
> cells produce extra telomerase. The mice did not develop
> cirrhosis when chemicals were used to damage their livers,
> they reported in the journal Science.
>
> They said they believed their findings would translate to
> humans.
>
> Currently, the only option for patients with advanced liver
> disease is a transplant, but not enough livers are
> available.
>
> A second team at Harvard and Brigham and Women's Hospital in
> Boston, along with a group at Okayama Medical School in
> Japan, thought along similar lines.
>
> They made human liver cancer cells ``immortal'' not with
> telomerase, but with another gene taken from a virus. Taking
> into account the risk of cancer, they used a second gene to
> reverse this process after they had grown a lot of cells.
>
> Transplanted into rats who had 90 percent of their livers
> removed, the cells worked to keep the rats alive. One
> obvious worry would be that turning on telomerase production
> could cause cells to become cancerous. DePinho said more
> study would be needed to answer that fear.
>
> ``It's possible that if you deliver telomerase early, before
> the telomeres get too short, you may be able to prevent
> cells from becoming cancerous,'' he said.
>
> ``That's because chromosomes with short telomeres are more
> likely to break and rearrange themselves in abnormal ways,
> resulting in a scrambling of the genetic code that can set
> the stage for cancer. From that standpoint, rebuilding
> telomeres may actually confer a protective cushion against
> cancer. ``
>
> --
> KeelyNet - From an Art to a Science
> Jerry W. Decker - http://www.keelynet.com/
> Interact discussion list http://www.keelynet.com/discuss.htm
> KeelyNet - PO BOX 870716 - Mesquite, TX 75187
>
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