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APS Presentation 12:30 p.m. EDT, Monday, April 30
Pressroom presentation 10:30 a.m. EDT, Monday, April 30
Embargoed to the date and time above
Media Contact
Sarah Goodwin
(202) 249-4165 April
28-May 2
Patients Smelling For First Time In Their Lives
Results From First Characterization Of Abnormalities In Congenital Loss Of
Smell
New discoveries about the biochemical basis of the
majority of cases of the congenital inability to smell any odor, no matter
how strong, have enabled their discoverer, Dr. Robert I. Henkin, director of
The Taste and Smell Clinic in Washington, DC, to treat such patients,
enabling them to smell something for the first time in their lives.
These patients respond with amazement, Dr. Henkin told
fellow scientists gathered at Experimental Biology 2007 meeting in
Washington. “Until the treatment began to take effect, they had never
experienced the olfactory world that surrounds us all, and it is with
excitement that they quickly begin to learn what different things smell like
and to relate those odors to objects they have known all their lives,” says
Dr. Henkin.
Dr. Henkin’s Experimental Biology presentation, on
April 30, is part of the scientific program of The American Physiological
Society. His study is the first to characterize the biochemical
abnormalities in these patients and the first to successfully treat patients
using this new understanding.
In the United States alone, there are about 400,000
people who have never smelled anything in their lives. (This does not
include those who lose their once normal smell function because of illness
or accident.) A relatively small percentage - 12 percent - of individuals
with congenital smell loss have multiple anatomical abnormalities of the
brain and other organs. The vast majority - 88 percent - of individuals with
congenital smell loss, however, do not have any such obvious organ
abnormalities and their olfactory nerves and the brain regions that process
olfactory information are intact.
Why, then, have they never been able to smell?
In order to answer that question, Dr. Henkin examined
these seemingly normal patients’ nasal mucus, the fluid that bathes the
olfactory nerve receptors. From earlier studies in his laboratory, Dr.
Henkin knew that the nasal mucus contains growth factors responsible for
olfactory stem cell maturation and function. Without these growth factors,
olfactory receptor cells can not maintain normal cell function. As he
suspected, the nasal mucus from these patients was deficient in these
important growth factors.
The studies also found a double whammy in these
patients’ nasal mucus. Normal mucus contains not only growth factors to
allow new olfactory receptor cells to function, it also contains death
factors that kill the aging receptor cells (a normal process of programmed
cell death, or apoptosis), making way for the new. The congenital smell loss
patients had five to 10 times the concentration of these death factors as do
people who can smell. That guaranteed that the high concentration of death
factor would destroy any receptor cell growth that was able to take place.
After determining the family of enzymes to which the
growth and death factors belong and defining the biochemical pathway
responsible for these factors, Dr. Henkin was able to treat these patients
with PDE inhibitors that increase the concentration of growth factors and
inhibit the secretion o death factors in nasal mucus. The treatment has been
successful in restoring smell function in some of these patients, with the
higher the dose and longer the use having the greatest effect.
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