Link Between Iron, Heart Disease Disputed
Reducing the amount of iron stored in the body does not allow men to reduce their risk of heart attack, according to a team from the Harvard School of Public Health.
Men generally have higher levels of iron in their bodies than women do because women lose iron during menstruation. It has been widely speculated that the lower iron levels are the reason why women have lower levels of coronary heart disease, but the new study suggests that is not the case.
Dr. Alberto Ascherio and his colleagues studied the relationship between blood donation and heart disease in 38,244 men who participated in the Health Professionals Follow-up Study between 1992 and 1996. They focused on blood donation because men who donate one unit of blood per year can cut their iron stores in half, while those who donate two or three units cut their iron levels to those of premenopausal women.
The team reported in the Jan. 2 issue of Circulation: Journal of the American Heart Assn. that they found no reduction in risk of heart disease among men who donated blood regularly, even if the men had high cholesterol. Iron stores were thought to present a particular risk in such men. The researchers concluded that iron stores are not an important risk factor for heart disease.
Risks Outweigh Benefits of Steroid to Preemies
Treating premature infants with the steroid dexamethasone provides modest benefits in preventing chronic lung disease, but the side effects of the treatment outweigh the benefits, according to researchers in the National Institute of Child Health and Human Development’s Neonatal Research Network.
About 70% of extremely low-birth-weight infants (those weighing 2.2 pounds or less) survive to be discharged from the hospital, and 30% of these develop chronic lung disease requiring supplemental oxygen. Researchers had believed that dexamethasone could help such infants.
The new study enrolled 220 infants in the 13 centers participating in the network. About half received dexamethasone and half a placebo. The team reported in the Jan. 11 New England Journal of Medicine that about 10% fewer of those receiving the drug needed oxygen at 28 days. But those receiving the drug were also more likely to have high blood pressure, to need insulin treatment for high blood sugar levels and to have decreased growth and head circumference. About 13% of those receiving the drug also developed a spontaneous perforation of their intestines, compared with only 4% of those receiving the placebo.
Pain Can Be Managed With Little Morphine
A new study in mice shows that it is possible to obtain powerful pain relief with much lower doses of morphine than previously used, sharply reducing the possibility of developing tolerance and addiction to the drug.
Dr. Stanley Crain and Dr. Ke-Fei Shan of the Albert Einstein College of Medicine in New York City demonstrated in the animals that very low doses of morphine actually increase pain by exciting nerve cells, a process know as hyperalgesia. At higher doses, this excitation continues, but is overwhelmed by the pain-relieving, or analgesic, properties of the drug.
The pair report in the January issue of Brain Research that the hyperalgesia and analgesia result from two different biological pathways in pain-sensing nerve cells. They also found that the pathway leading to hyperalgesia could be blocked by very small doses of the opioid antagonist naltrexone, which is commonly used to treat morphine overdose. With this pathway blocked, low doses of morphine produce much stronger analgesia.
Their finding in mice was corroborated in a preliminary human study looking at post-surgical pain. Low doses of morphine that produced no benefit when given alone showed a remarkable degree of pain relief when combined with an ultra-low dose of naltrexone, they said. A larger trial is now in progress.
Ginkgo Biloba Doesn’t Alleviate Tinnitus
The popular herbal supplement ginkgo biloba is not better than a placebo for treating tinnitus, or ringing in the ears, according to British physicians. Dr. Shelley Drew and associates at the University of Birmingham studied 1,121 otherwise healthy people with tinnitus. For 12 weeks, 559 were treated with ginkgo and 562 with a placebo. The team reported in the Jan. 13 British Medical Journal that the group receiving the supplement showed no more improvement than the group receiving a placebo.
Hormones Make Cancer Detection Harder
Hormone replacement therapy increases the density of breast tissue, making it more difficult for mammograms to detect tumors, according to researchers from the University of Washington.
That is not a sufficient reason to stop taking the hormones, they conclude, but women should be aware of the problem and increase their vigilance, the team recommended in the Jan. 10 Journal of the American Medical Assn.
Dr. Carolyn Rutter and her associates studied 5,212 naturally menopausal women between the ages of 40 and 96. Women who started replacement therapy during the study were about 2 1/2 times more likely to show an increase in breast density than those who did not. Dense, opaque tissue shows up white on mammograms, obscuring tumors. Density eventually returns to normal in women who stop taking the hormones.
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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com.
