Study Links Vaccine to Slight Risk of Bleeding Disorder
The measles, mumps and rubella vaccine can occasionally produce a rare bleeding disorder in children, according to British researchers. But physicians said that the risk of the disorder is very small and parents should not be afraid to vaccinate their children.
The finding comes at a time when the MMR vaccine is already controversial because of purported links to autism.
The bleeding disorder, called idiopathic thrombocytopenic purpura (ITP), is caused by a shortage of platelets, the white cells that give blood its “stickiness” and trigger clotting, and is characterized by bleeding under the skin. About one in every 10,000 people has the condition. In children, it is often preceded by a viral infection.
Dr. Elizabeth Miller and her colleagues at the Public Health Laboratory Service in London analyzed the records of hospital admissions for all children under age 5 admitted for ITP within six weeks of MMR vaccination in the East Thames region of London. They concluded that two out of every three cases of ITP occurring in the six weeks after immunization are caused by MMR, according to the report in the March Archives of Disease in Childhood. About one in every 22,300 MMR vaccinations will result in admission to a hospital for ITP, they calculated.
The children whose illness was associated with ITP tended to have milder symptoms and spent less time in the hospital than those whose ITP was not associated with the vaccine. And children who had already had ITP were at no greater risk of recurrence when they were vaccinated.
The MMR vaccine has been a focus of controversy recently because some parents believe that the vaccination triggered autism in their children. Several large studies have failed to find such a link, however.
Beware, Those Who Drink and Ride
Perhaps it seems obvious: Drinking alcohol and riding a bicycle don’t mix. But a new study by researchers in Baltimore is the first to quantify the risk.
Drinking one drink and riding a bicycle increased the risk of a fatal accident fivefold while four or five drinks increased the risk 20-fold, according to a study by Dr. Guohua Li and colleagues at the Johns Hopkins University School of Medicine.
“Riding a bike requires a higher level of psycho-motor skills and physical coordination than driving a car, so alcohol has an even stronger effect on bicyclists than drivers,” Li said.
The researchers studied the death records of 124 bicyclists--ages 15 and older--who were killed in Maryland from 1985 to 1997. They also performed breath tests on 342 other cyclists riding in the same areas where the fatalities occurred.
The results were reported in the Feb. 21 Journal of the American Medical Assn. Previous studies have shown that about a third of all U.S. bicycling fatalities are alcohol-related.
They also found that 30% of injured cyclists had a prior conviction for driving a car under the influence.
Too-High Iron Levels May Pose Health Risks
Physicians often worry that elderly patients do not get enough iron in their diets, but a new study suggests that too much iron may be a bigger problem than not enough.
Dr. Dianne Fleming of Tufts University in Boston and her colleagues studied 1,016 healthy people ages 67 to 96. They reported in the Feb. 21 Journal of the American Medical Assn. that only 3% of the subjects had low iron levels, putting them at risk for anemia, while 12.9% had too much iron. Some studies have suggested that higher-than-normal iron levels increase the risk of heart attack, cancer and diabetes.
Heartening Findings on Breast Cancer Drug
Canadian researchers say they have found a new way to administer a drug to breast cancer patients while lessening potential adverse effects on the heart.
The drug doxorubicin is one of the most effective chemotherapies available for breast cancer. But it can lead to heart failure in as many as 5% of patients.
Dr. Gerald Batist of McGill University in Montreal studied a new formulation in which doxorubicin is enclosed in tiny oil droplets called liposomes. The liposomes pass readily through the heart and lodge in areas where the drug can be released to the tumor.
Batist and his colleagues studied 297 breast cancer patients, half of whom received conventional doxorubicin therapy and half the new formulation. They reported in the March Journal of Clinical Oncology that 21% of the women receiving standard doxorubicin had at least some heart damage, contrasted with only 6% of those who received the new formulation.
Oxygen Doses May Not Ease Cerebral Palsy
Children with cerebral palsy do not benefit from high-pressure oxygen therapy, according to Canadian researchers. Several centers in the United States, Canada and the United Kingdom now use the oxygen therapy, but there have been no previous studies of its effectiveness.
Dr. Jean-Paul Collet and his associates at McGill University studied 111 children with cerebral palsy. Half received oxygen at about 1.75 times atmospheric pressure, while the rest were exposed to room air at about 1.3 times atmospheric pressure. All the children received 40 one-hour treatments during a two-month period.
The team reported in the Feb. 24 Lancet that both groups showed some improvement in measures of motor function, daily living, memory and speech, but that there were no significant differences between them. Ear problems occurred in 27 children treated with the hyperbaric oxygen, compared to only 15 of those treated with hyperbaric air.
DiGeorge Syndrome Gene Isolated
Three separate groups have independently discovered the defective gene that causes DiGeorge syndrome, which affects about one in every 4,000 children. The disorder has a broad range of symptoms, including facial abnormalities, heart defects, immune system malfunction and learning disabilities. The severity also varies widely. Some victims die soon after birth, while others have symptoms so mild that they are virtually unnoticed.
Researchers have long known that DiGeorge syndrome is caused by the deletion of a segment of chromosome 22, one of the 23 pairs of chromosomes that make up the human genetic blueprint. But that segment contains several genes, and researchers were not sure which was responsible.
The teams report in the March issues of Cell and Nature Genetics and in the March 2 Nature that the most important gene is called Tbx1, one of the so-called T-box genes that control development. Removing this gene from mice, the teams reported, produces the most important symptoms of DiGeorge syndrome.
Chromosome 22 is particularly unstable and prone to deletions. Another deletion in the chromosome is one of the major causes of congenital heart defects.
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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com.
