FYI from the NHLBI Index
September 2001: Vol. 2, Issue 2
In the News
On July 25, Congressman Clifford Stearns (R-FL) introduced a resolution
(H. Con. Res. 197) to establish Chronic Obstructive Pulmonary Disease (COPD) Awareness Month. The
goal would be to raise public awareness about the prevalence of the disease and the serious problems
associated with it. COPD is a slowly progressive disease of the airways characterized by gradual
loss of lung function. In the United States, the term COPD includes chronic bronchitis, chronic
obstructive bronchitis, or emphysema, or a combination of these conditions. Approximately 16 million
Americans have COPD. In 2000, COPD ranked as the fourth leading cause of death both in the United States
As of July 30, the House and Senate Appropriations Committees were in the process of finalizing
their recommendations for the Fiscal Year 2002 budget. Once the committees have completed their work,
the bills will go to their respective chambers for debate and approval. After a conference committee
resolves any differences between the bills, the House and the Senate must approve the conference
committee's version before it can be sent to the President to be signed into law.
Early results from the NHLBI-supported National Emphysema Treatment Trial (NETT) show that
emphysema patients who have severe lung obstruction with either limited ability to exchange gas
when breathing or damage that is evenly distributed throughout their lungs receive little benefit
from lung volume reduction surgery (LVRS) and are at high risk of death from the procedure. This is
the first time that researchers have identified scientifically based selection criteria for patients
seeking LVRS as a treatment for advanced emphysema. When discussing the result, Dr. Lenfant stated
"Identifying which patients should not undergo this surgery is a key goal of this study. We expect
the final results of NETT will guide us further in
determining if and when this procedure should be used to treat emphysema."
People who are following the DASH (Dietary Approaches to Stop Hypertension) diet to lower
their blood pressure will be pleased to know that they are lowering their risk of heart disease
and stroke in more ways than one. In addition to lowering blood pressure in hypertensive patients
and reducing elevated levels of the amino acid homocysteine (a risk factor for heart disease, stroke,
and peripheral vascular disease), the DASH diet significantly reduces a person's levels of total
cholesterol and of low density lipoprotein (LDL) or "bad" cholesterol. This
effect was seen in both black and white study participants.
The diet, which is low in saturated fat and cholesterol and promotes the use of low fat dairy
foods, is much higher in fruits and vegetables than a typical cholesterol-lowering diet. However,
it is consistent with the NCEP's new guidelines, and adds one more tool to the
armament of interventions known to help lower a person's risk for CHD.
Recent Advances from the NHLBI
One More Reason to Achieve and Maintain a Healthy Weight
Investigators studying nearly 700 adults found that weight gains of 5 to 20 percent increase
the risk of developing sleep apnea by 2.5 to 37 times, respectively. More important, weight
loss was associated with reduced sleep apnea severity and decreased likelihood of developing
moderate to severe sleep apnea. Sleep apnea, a prevalent and potentially serious medical
condition, is characterized by repeated episodes of airway obstruction during sleep and excessive
daytime sleepiness. These results strongly suggest that weight loss and prevention of weight gain,
through diet or exercise, offer an effective approach for its prevention and treatment.
Researchers Identify Novel Approach for Predicting Pulmonary Complications from Sickle Cell Disease
A pneumonia-like illness known as acute chest syndrome (ACS) is the leading cause of
morbidity and early death in patients with sickle cell disease. Researchers have shown that
elevated levels of an enzyme called secretory phospholipase A2 are associated with the
development of acute chest syndrome. If confirmed by larger clinical studies, enzyme
measurements could be used to identify patients with impending ACS, thereby allowing them to
receive therapies that will reduce the severity of ACS or prevent its development.
Heart Muscle Regenerates After a Heart Attack
Challenging one of medicine's long-standing beliefs, a team of scientists funded by the NHLBI
and the National Institute on Aging has found the strongest evidence to date that human heart
muscle cells regenerate after a heart attack. The scientists found muscle cells dividing in two
regions of the heart, and identified several other key indicators of cell regeneration. "It has long
been assumed that when the heart is damaged - such as after a heart attack - heart muscle cells do not
regenerate and the damage is permanent. Now, this latest research provides the most dramatic and clear-cut
demonstration to date of heart cell regeneration after cardiac injury," said Dr. Lenfant. "With
this landmark study, we have a new understanding of the heart that opens up
the possibility of repairing heart muscle damage after a heart attack."
According to the study's principal investigator, Dr. Piero Anversa, the next
challenge is to find the source of the dividing cells and establish if they truly
are cardiac stem cells. "If we can prove the existence of cardiac stem cells and
make these cells migrate to the region of tissue damage, we could conceivably improve
the repair of damaged heart muscle and reduce heart failure," said Anversa. Research on
animal models supports this possibility. Anversa also has published research showing that
adult stem cells isolated from mouse bone and injected into a damaged mouse heart became functioning
heart muscle by developing into myocytes and coronary vessels. Moreover,
the new tissue partially restored the heart's ability to pump blood.
Researchers Uncover a Secret of Burning Fat
Researchers recently discovered that perilipin, a protein associated with fat metabolism
and weight gain in mice and humans, acts by preventing a "fat-burning" enzyme from entering
fat cells where it can break down fat molecules and convert them to energy. They also showed
that mice genetically modified to lack perilipin had about half as much body fat, 8 percent
more muscle, and higher metabolic rates than did normal mice, despite eating 25 percent more
food. Moreover, a mutation for perilipin deficiency prevented obesity in mice that had been
genetically programmed to be obese. Since perilipin has been found only on fat cells, researchers
hope new anti-obesity drugs can be developed that will reduce perilipin activity and will work
exclusively on adipose tissues without side effects on other tissues.
Identifying Ideal Candidates for Revascularization
A heart attack involves injury to heart muscle that occurs when arteries supplying blood
to the heart become blocked. Sometimes patients improve if the blood flow can be restored via
a revascularization procedure such as angioplasty or bypass surgery. However, the procedures
are not risk-free; patients have a 2 to 5 percent chance of experiencing serious complications,
including death. Therefore, it is critical that patients do not undergo the revascularization
procedures needlessly, but it
is equally important to treat those for whom the benefits outweigh the risks.
One such patient would be someone experiencing cardiogenic shock, the leading cause of
death for patients hospitalized due to heart attacks. As demonstrated by the NHLBI's SHOCK
Trial, heart attack patients who received revascularization immediately after developing cardiogenic
shock were significantly more likely to be alive one year after their heart attacks than were those who
developed cardiogenic shock but did not receive the procedure. Therefore, the American College of Cardiology
and the American Heart Association recommend revascularization for patients younger
than 75 years who develop cardiogenic shock within 36 hours of a heart attack.
Due to recent advances in magnetic resonance imaging (MRI) technologies, physicians may
soon be able to identify other people for whom the risks of these invasive procedures outweigh
the benefits. For example, a new MRI technique using contrast agents helps distinguish between
patients with irreversibly damaged left ventricles and those in whom damage can be reversed by
revascularization. Moreover, the technique is powerful enough to identify damaged tissue even in
patients who are not aware that they had ever experienced a heart attack.
Long-Acting Beta-Agonists not as Effective as Inhaled Corticosteroids in Treating Persistent Asthma
Researchers recently completed two studies addressing whether long-acting beta-agonists (LABs)
should replace or supplement inhaled corticosteroids (ICS) as treatment for adults with mild-to-moderate
persistent asthma. The results, published in the May 23, 2001 issue of the Journal of the American Medical
Association, showed that LABs alone are not as effective as ICS alone in treating adults with mild-to-moderate
persistent asthma. However, many patients with asthma were treated successfully with lower doses of
steroids if they also took LABs. In a statement announcing the results Dr. Lenfant said "These two
studies provide new and important scientific information about treatment questions that clinicians
face every day in managing adult patients with mild-to-moderate persistent asthma: can they switch
patients to long-acting beta-agonists from inhaled corticosteroids
or use long-acting beta-agonists to reduce steroid doses? Now we have the answer."
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