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I thought this might interest some of you....
NEW YORK (Reuters) -- Scientists may have a biochemical clue
as to how exposure to light can destroy cells in the retina --
the fragile, light-sensitive membrane that lines the back of the
eye.
The new findings by researchers in Switzerland suggest that
if a way could be found to block production of a protein called
c-fos, retinal degeneration could be halted. Retinal
degeneration is thought to be due to the destruction of the rod
and cone cells in the retina that convert light energy into
nerve impulses that travel to the brain.
Cell biologist, Dr. Farhad Hafezi, and colleagues at the
University of Zurich, made the decision to focus on c-fos
because a recent study indicated that the gene that codes for
the protein is involved in retinitis pigmentosa (RP), a
condition in which rods and cones in both eyes degenerate. RP,
which may lead to blindness, seldom appears before adolescence
and is an inherited disease.
In their experiment, the Swiss scientists exposed two groups
of mice to bright light, including some that were genetically
bred not to produce c-fos (c-fos "knockout" mice).
At 12 and 24 hours following exposure to the same light
intensity, virtually no retinal cell death was observed in the
knockout mice who lacked the protein, whereas normal mice showed
extensive rod and cone death.
The researchers say their findings suggest that c-fos may be
crucial to the biochemical cascade of events associated with
vision loss due to retinal degeneration as occurs in RP.
But the study may raise more questions than it answers. Dr.
Fintan Steele, news editor of the journal Nature Medicine which
carries the Swiss report, says it is still unclear "if the lack
of light-induced cell death in the c-fos knockout mice is a
direct or indirect effect of c-fos absence."
And looking at what he says are "bigger questions
unintentionally raised by the study," Steele asks why it is
that human retinas carrying c-fos take years to undergo
degeneration.
"The biggest question -- therapeutic intervention -- goes
begging entirely," he says.
Steele points out that attempts to fix degenerating retinas
have been largely unsuccessful. "It is one thing to suggest
that targeting the retina with either therapeutic genes or
agents to reduce some biological cascade could retard retinal
degeneration. It is quite another to achieve this goal."
According to Steele, "Much of the effort and money put into
'gene therapy' of the retina... would be far better spent on
answering fundamental questions posed by this beautiful
tissue."
SOURCE: Nature Medicine (1997;3(3):346-349, 280)
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"Reach high, for the stars lie hidden in your soul. Dream deep, for
every dream precedes the goal."
-Pamela Vaull Starr
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