June 2001
MEDICAL NEWS TIPS FROM JOHNS HOPKINS MEDICAL INSTITUTIONSTo pursue any of these stories, please contact the media representative listed.
FAULTY BEE TESTS MAKE FOR STINGING SURPRISES
Summer has arrived and so have the bees. So what's the latest buzz on the matter? According to a recent study in the Journal of Allergy and Clinical Immunology, even the usually reliable bee allergy tests may leave some people fear-free when, in fact, they are allergic to the nectar-gathering insects.
In a study of 307 people who previously had allergic reactions to bees, doctors discovered 99 who skin-tested "negative" for the allergy --- their skin did not become ruddy or swollen when exposed to bee venom. Fifty-six of these, however, tested positive in a RAST (radioallergosorbent) test that exposes a sample of the patient's blood to concentrated allergens. And of the 51 with negative skin tests who agreed to undergo a sting challenge, 11 suffered an allergic reaction.
Although skin tests are more than 90 percent accurate, they are not 100 percent accurate. Skin and RAST tests need to be repeated when negative, and doctors should forewarn patients who have had prior reactions that both tests might be faulty, said David Golden, M.D, an associate professor of medicine at Johns Hopkins. "We need better tests that provide more accurate diagnoses but until we get them, retesting is a must," he continued.
Over 2 million Americans are allergic to stinging insects. Reactions can range from mild to life-threatening, and can involve hives, itchiness, swelling, difficulty breathing, dizziness, a sharp drop in blood pressure, nausea, cramps, diarrhea, unconsciousness and cardiac arrest. People who have had such a reaction should tell their doctor and see an allergy specialist for testing; an immunization for insect stings (venom immunotherapy) is 98 percent successful in preventing allergic reactions.
For more information or to interview Golden, contact Kate O'Rourke at 410-955-8665 or [email protected].
MEXICAN-AMERICANS AT HIGH RISK FOR DIABETIC RETINOPATHY
Hispanics over the age of 40 are twice as likely to have diabetes as non-Hispanic whites, according to a study led by Johns Hopkins researchers. This population also is at high risk for developing diabetic retinopathy, a leading cause of blindness.
The study, funded by the National Eye Institute, was called Proyecto VER (Vision Evaluation and Research). It looked at vision problems among 4,774 Mexican-Americans age 40 and older living in Tucson and Nogales, Ariz. Participants were randomly selected based on information from the 1990 census. They filled out a health questionnaire and were evaluated in a clinic.
Study results, published in the July issue of the journal Diabetes Care, showed the incidence of diabetes among this population to be 22 percent, ranging from 12 percent in participants ages 40 to 49 to 34 percent in participants ages 70 to 79. Forty-eight percent of those with diabetes also had diabetic retinopathy, 32 percent of whom had moderate to severe cases. In addition, eye exams given during the study detected diabetic retinopathy in 15 percent of those who said they did not have diabetes. Within this group, 9 percent had advanced retinopathy and were in danger of losing vision.
"The finding that 15 percent of diabetic cases in this community were unknown before our survey indicates just how important it is to identify and control diabetes among this population," says Sheila K. West, Ph.D., professor of ophthalmology and epidemiology at Hopkins' Wilmer Eye Institute.
For more information or to interview one of the study authors, contact Karen Blum at 410-955-1534 or [email protected].
NOVEL MEASURE OF BLOOD CHOLESTEROL BETTER PREDICTS DEATH FROM HEART DISEASE
The amount of non-high-density lipoprotein (non-HDL) cholesterol circulating in the blood predicts whether a person is likely to die of heart disease, according to a study led by Johns Hopkins researchers.
Non-HDL cholesterol is defined as the difference between total cholesterol and HDL or "good" cholesterol. It includes triglycerides (blood fats), low-density lipoprotein (LDL) or "bad" cholesterol, and intermediate density lipoprotein.
In a study of 4,462 adults ages 40 to 64, increasing non-HDL cholesterol level was associated with an increased risk for death related to heart disease. Men with high non-HDL cholesterol levels were twice as likely to die of heart disease as their counterparts with lower levels; in women, the risk was nearly two and a half times higher. Elevated LDL cholesterol was a weaker predictor, especially in women.
Researchers looked at the patient population in the Lipid Research Clinics Program Follow-up Study, a mortality study with baseline data gathered from 1972 to 1976. Death rates were followed through 1995. Study results were published in the June 11 issue of the Archives of Internal Medicine.
"Given the increased accuracy in predicting cardiovascular disease-related death by non-HDL cholesterol versus LDL cholesterol, blood analyses should look at total cholesterol and HDL levels when trigylcerides are elevated," says Roger S. Blumenthal, M.D., study author and director of Hopkins' Ciccarone Center for the Prevention of Heart Disease. "This study strongly supports the recent national Adult Treatment Panel III cholesterol guidelines that in patients with elevated triglycerides (greater that 200 milligrams per deciliter), non-HDL cholesterol should be a target of therapy."
In patients with diabetes, known cardiovascular disease or high risk scores on cardiovascular disease measurement scales, the target LDL should be less than 100 mg/dL and the non-HDL cholesterol should be less than 130 mg/dL, Blumenthal says.
LDL levels can be calculated falsely low, he adds: "Doctors should strive to optimize not only their patients' LDL levels but also their non-HDL values."
An added advantage of non-HDL measurements, Blumenthal says, is that they can be taken even when the patient has eaten. By comparison, LDL measurements can be taken only when the patient fasts, as food intake can raise triglycerides and lower LDL.
For more information or to interview Blumenthal, contact Karen Blum at 410-955-1534 or [email protected].
WOMEN FACING CANCER TREATMENT MAY STILL HAVE FERTILITY OPTIONS
Young women today are more likely to beat cancer and should be advised about ways to preserve their fertility before undergoing treatment, a Johns Hopkins study suggests.
"Many adolescent and childhood lymphomas and leukemias, as well as solid tumors, can now be cured ... but the long-term consequences of chemotherapy regimens on reproductive potential were not anticipated," says M. Natalia Posada, M.D., a reproductive endocrinology fellow and lead author of the study. "All patients -- especially women ages 30 or younger undergoing high-dose chemotherapy and bone marrow transplant -- should be counseled about fertility preservation options."
Posada and colleagues searched through medical literature, looking for studies relating to such options.
The most promising opportunity, they say, is freezing ovarian tissue, banking it and having it re-implanted after cancer treatments are finished. This is possibly the only alternative for child and adolescent patients. Posada cautions that frozen tissue needs to be scrutinized before re-implantation to make sure it harbors no cancer cells.
Another possibility is undergoing in vitro fertilization before chemotherapy to preserve embryos to be used later. This is a good option for women who have a partner and are willing to cryopreserve embryos, Posada says. A future opportunity is drugs called GnRH analogs, which can protect eggs from the effects of chemotherapy. These have done well in tests of animal models; more studies need to be done in humans.
The report was published in a recent issue of the journal Fertility and Sterility.
For more information or to interview Posada, contact Karen Blum at 410-955-1534 or [email protected].
--JHMI--
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