Off topic - weird, fascinating discovery relating to asthma.
March 21, 2000
Acidic Breath of Asthmatics Hints at Better
Treatments
By SANDRA BLAKESLEE
In a startling discovery that could radically alter the way asthma patients
are monitored and treated, doctors at the University of Virginia have
found that the breath of asthmatics who are having an attack is a
thousand times as acidic as normal.
This increase in acidity -- never before detected in asthma patients -- may be
central to the disease process, the researchers said. While it is not yet known
what causes the imbalance, the finding could open an entirely new avenue of
research to explain the disease.
When acutely ill asthma patients are given steroids, their breath pH,
measuring acidity or alkalinity, quickly returns to normal, said Dr. Benjamin
Gaston, an associate professor of pediatric pulmonary medicine at the
University of Virginia in Charlottesville, who helped make the discovery.
If the defect in asthma turns out to be a problem maintaining normal pH, Dr.
Gaston said, less toxic therapies to neutralize excess acid may one day stave
off or stop attacks.
The finding, in the March issue of the American Thoracic Society's American
Journal of Respiratory and Critical Care Medicine, fits well with recent
theories about how humans fight off lung pathogens like the tuberculosis
bacterium and why rates of asthma are increasing in the industrialized world.
It also helps explain why air pollution often brings on asthma attacks.
Dr. Martin Tobin, editor of the journal and chief of the division of pulmonary
clinical medicine at Loyola University in Chicago, said the findings were
"potentially very important."
"It's difficult to know how this will play out," he said, "but most of the most
important discoveries in medicine are made serendipitously. You look back at
a difficult problem and realize the solution was something very simple."
Dr. Jonathan Stamler, who wrote an editorial about the findings in the
journal, agreed on the potential importance. "It's really rare when you look at
a study and realize it could be a landmark," said Dr. Stamler, a professor of medicine at Duke University Medical Center in Durham, N.C. Asthma affects some 12 million people in the United States,
and the number of patients is increasing, according to the American Thoracic
Society. The disease is the leading cause of hospitalization for children.
Dr. Gaston said that he and his colleagues made their discovery a year ago by
accident.
In looking for ways to figure out what was wrong with airway chemistry in
asthma patients, they were measuring nitric oxide and related compounds to
see if they played a role in airway inflammation. Nitric oxide is a simple gas
that has been associated with critical body functions, like the delivery of
oxygen to tissues. But because the researchers knew pH could affect nitric
oxide reactions they decided to measure pH directly.
The pH scale is measured from 0 to 14. Acidic solutions like vinegar fall in
the range of 3 to 5.
Alkaline solutions like baking soda in water measure above 7.
People without asthma or asthmatics who have the disease under control
usually have a breath pH above 7, Dr. Gaston said. But the asthmatics the
researchers studied who were sick and wheezing had a pH of about 5. "We
were shocked to see how acidic their breath was," he said.
The pH fell drastically in each person suffering an asthma attack, Dr. Gaston
said. There was no mistaking the excess acid. The biological mechanisms
that explain the sudden increase in acidity are not yet known, Dr. Gaston
said.
But it is clear that acidity inflames lung tissue and plays a role in closing
down airways.
The ability to raise or lower airway acidity makes sense in evolutionary
terms, Dr. Gaston said.
Some organs, including the stomach and kidneys, increase their acid content
to fight pathogens. Dogs can eat the vile things they do because they are
champions at producing stomach acid, he said. It may be that the lungs have
evolved a similar self-defense mechanism against airborne pathogens.
A recent theory proposed by Dr. Stephen Holgate from the University of
Southampton in Britain says that asthma rates are increasing in industrialized
countries because good hygiene prevents children under the age of 5 from
falling prey to serious lung diseases seen in the less developed world. Without
early episodes of lung infection, Dr. Holgate said, the pulmonary immune
system fails to mature. The result is increased vulnerability to asthma.
The new findings about high acidity during asthma attacks may be a clue to
what is missing in the lungs of those with the disease, Dr. Gaston said.
Asthma may be a disease in which a natural host defense mechanism, which
would produce acid when challenged by a microbe, has gone awry, with
lungs producing too much acid at the wrong time.
Some strains of tuberculosis contain genes that help them neutralize acid, Dr.
Gaston said. No one has ever known the reason. The fact that human lungs
produce their own acid may also help explain why smoggy air brings on
asthma attacks, he said.
The extra acid from the air pushes the lung pH too low and airways shut
down.
While the findings are preliminary, their first practical use may be helping
asthma patients know when they are vulnerable to attacks by breathing into a
monitor to decide if they need to bring their pH back to a normal range.
There may be ways to neutralize pH with a simple spray. Such treatments
could be cheap and, unlike steroids, would be nontoxic. While pharmaceutical
companies spend billions on finding new drugs to fight lung inflammation, the
answer may be as simple as resetting the pH in a hot tub or fish pond, only
this time it is in the lungs.
Copyright 2000 The New York Times Company |
