`Too Clean' Environments Have A Price
News Desk
By WILLIAM HATHAWAY, Courant Staff Writer
Lab animals and people who live in developed countries have something
in common: They tend to live in unnaturally clean environments.
Researchers at Duke University Medical Center say this may explain why
people in industrialized societies have higher rates of allergies and
autoimmune diseases than people in poorer countries.
In a study published in the current online edition of the Scandinavian
Journal of Immunology, scientists compared levels of antibodies known
as immunoglobulins in mice and rats trapped in the wild to those in
rodents raised in Duke laboratories.
Different types of immunoglobulins have been linked to both allergies,
in which the immune system reacts to harmless allergens, and to
autoimmune diseases, in which the immune system attacks the host's own
tissue.
The "hygiene hypothesis" posits that these disorders are increasing in
the developed world because people's immune systems are no longer
challenged by environmental microbes, so they react too vigorously to
perceived threats.
The Duke study did find that animals raised in the wild had
significantly higher levels of both IgG and IgE, immunoglobulin types
associated with autoimmune diseases and allergies, respectively. The
wild mice, however, showed no ill effects.
"Their production seemed to represent a nonpathogenic, protective
response to the environment by the wild rodents," said William Parker,
assistant professor of experimental surgery at Duke and a study author.
"We would expect that the targets of the auto-reactive IgG and IgE in
hygienic laboratory rodents would be substantially different from the
targets of the same antibodies in the wild animals."
The Duke researchers also are studying genetic and environmental
factors that may play a role in the development of the immune system.
Acupuncture Relief
Acupuncture reduces symptoms of fibromyalgia, researchers report in the
June issue of the Mayo Clinic Proceedings. Fibromyalgia is a chronic,
debilitating disorder characterized by widespread musculoskeletal pain
and fatigue. There is no known cure, and treatment is often difficult.
Mayo Clinic researchers used acupuncture or sham acupuncture treatment
on 50 fibryomyalgia patients. They found that symptoms in patients who
received acupuncture substantially improved compared with subjects who
got sham treatments.
"The results of the study convince me there is something more than the
placebo effect to acupuncture," said Dr. David Martin, a Mayo
anesthesiologist and author of the study.
The value of acupuncture in the treatment of fibromyalgia has been
controversial. In two other studies, one found acupuncture to be
effective, while another found it offered no pain relief.
Finding A Home For Neurons
Scientists have found at least one of the key chemical ingredients that
help guide nervous system cells to their proper locations in the
developing spinal cord and brain.
A versatile molecule called FGF acts as a siren for migrating motor
neurons in the embryo, while other chemical signals repulse them when
they wander off path, scientists at the Salk Institute for Biological
Studies report in the current issue of the journal Neuron.
Understanding how nerve cells reach proper locations may help
scientists treat spinal cord injuries and intractable diseases such as
ALS, or Lou Gehrig's disease. Also, failure of brain cells to make
proper connections may contribute to autism and mental retardation,
scientists said.
Axons, the thread-like ends of nerve cells, reach out searching to make
connections with specific nerve cells. Scientists have discovered
several molecules that act as repellants to exploring axons, but the
chemical attractant has been elusive.
The Salk researchers say their study shows that the lure for motor
neurons in development is a member of the FGF family of growth factors.
These growth factors perform many tasks, among them regulating blood
vessel formation, wound repair, lung maturation.
"Our study emphasizes that the nervous system does not necessarily rely
on an entirely new set of molecules to govern axon navigation, but
instead uses growth factors already involved in embryonic development
in clever and novel ways," said Samuel Pfaff, a professor in Salk's
gene expression laboratory.
Contact William Hathaway at hath...@courant.com