The value of allergy shots and screening for birth defects.

The value of allergy shots and screening for birth defects.

The value of allergy shots and screening for birth defects.

Health and medicine explained.
Feb. 13 2007 1:28 PM

Your Health This Month

Where intimacy comes from, the value of allergy shots for treating hay fever, and more.

This month, Dr. Sydney Spiesel discusses where love and intimacy come from, disappointing results for an AIDS barrier, the value of allergy shots for treating hay fever, a new and noninvasive method for screening for birth defects, and evidence that the smell of food shortens fruit flies' lives.

Love in the lab

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Origins of love: A science question for Valentine's Day: How is it that love and intimacy come to be? Ten years ago, Dr. Arthur Aron, an eminent researcher in social psychology at the State University of New York in Stony Brook, designed an experiment to answer these questions. It may sound unromantic, but it has great implications for understanding how people fall in love.

Illustration by Robert Neubecker. Click image to expand.

Experiment: The Aron team's method was simple. They put together pairs of students from a college psychology course, either mixed-sex pairs or same-sex pairs of two women. (More women were signed up for the course; a small side experiment suggested that pairs of men behave pretty much the same way.) Half were given a set of small-talk scripts to follow for 45 minutes (chitchat about one's favorite holiday, preference in watches, etc.). The other pairs were given 45-minute scripts that led them toward increasingly intense self-disclosure. They were pushed to reveal whether they rehearse phone calls before making them, say, or to describe the qualities or abilities they would most like to have, or to share their best and worst memories. They were also asked what they liked about the person they were paired with and what qualities they thought they shared with him or her. The pairs were then tested in several ways to determine the closeness they felt.

Results: The pairs prompted toward self-disclosure felt closer to each other than the small-talk pairs. It made little difference whether the pairs were pre-matched for similar attitudes or had been led to expect that they would like each other. It also made little difference if the participants were told in advance that the goal of the exercise was to generate intimacy.

Conclusion: Maybe Aron's research provides a recipe for the perfect Valentine's Day date: Reveal something of yourself. One of his lab pairings even ended in a wedding!

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AIDS barrier update

Goal: Condoms break the cycle of AIDS by interrupting transmission of the virus. But, of course, not everyone who should use them wants to. So, a nonphysical barrier that blocks the HIV agent (or even deactivates the virus) would be a wonderful addition to our AIDS-fighting arsenal.

Setback: Now, alas, the test of a promising material, Ushercell (a form of high-molecular-weight cellulose sulfate), has been stopped because it seems to increase rather than decrease the risk of infection. The test was conducted by a research agency, CONRAD, in India and Africa. Its halt follows similarly disappointing results for the spermicide nonoxynol-9, a common ingredient in contraceptive gels. Nonoxynol-9 was tried first because it's inexpensive, thought to be nontoxic, and deactivated the AIDS virus in the lab. A test of a vaginal gel containing nonoxynol-9 was conducted in four countries using more than 700 women at substantial risk for HIV exposure. But instead of decreasing the risk for HIV transmission, nonoxynol-9 increased it.

Next tests: At least four other similar products are currently being tested. One is a gel that maintains the normal vaginal acidity, which deactivates the AIDS virus, after intercourse. (Semen often decreases vaginal acidity.) Another is a polymer that attaches to the outer layer of the AIDS virus and blocks infection of cells in the vagina. (This one is somewhat effective at blocking herpes transmission as well). The third is a gel made from an edible seaweed product that blocks HIV infection in laboratory models. The fourth is an HIV-deactivating detergent.

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Conclusion: No one expects these products to be as effective as condoms at preventing HIV transmission. But if any turn out to be safe and fairly effective, they could help reduce AIDS transmission in places where women often find it hard to negotiate condom use.

Allergy shots and hay fever

I hate it when I'm wrong, and I especially hate to give up long-held prejudices. But it looks like I've been wrong in dismissing the value of allergy shots for treating hay fever. I scoffed because of the experience of my great-aunt Razel, which seemed typical. She suffered from a chronic runny nose and finally went to a doctor. This was in the old days and he did 400 skin tests before triumphantly announcing that he had found the cause of her troubles: She was allergic to shrimp and to beer. Except that Razel was a teetotaler who kept kosher. Modern immunology offers alternate food-based explanations (her allergies might have been caused by the yeast proteins in bread, rather than beer). Still, I've remained a skeptic.

New research: Now, Dr. M. A. Calderon, of Brompton Royal Hospital, London, and a group of colleagues have done a serious and extensive systematic review of the literature on immunotherapy (allergy shots) for seasonal allergic rhinitis (hay fever). After reviewing more than 1,000 research reports, Calderon's team found about 50 that asked the right question in a right enough way to make their conclusions worth comparing. These 50 reports included almost 3,000 patients. Just fewer than 60 percent were treated with active allergy shots and the rest with placebo injections. Neither the patients nor the doctors knew which kind of shot was being administered. This is the double-blind study model (though the blinding may be more apparent than real, since anyone who has ever administered the shots will tell you that the patients almost always know what they are getting).

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Results: In any case, according to both patients' self-reports and objective measures like decreased need for medications like antihistamines and nasal steroids, immunotherapy was shown to be unquestionably beneficial. And, contrary to the expectations of some doctors, it was also pretty safe. Fewer than 1 percent of the injections required for active treatment caused a significant adverse reaction. None of the adversely affected patients died, and they all chose to continue treatment.

Caveat: The big question this study does not address has to do with cost and benefit. Immunotherapy treatment is costly and time consuming. In the studies described in Dr. Calderon's review, each participant received an average of 18 injections. In my experience, this seems like a pretty low number. Hay fever can be awfully annoying, but it isn't lethal, and it can often be controlled to some degree by medications like antihistamines. I've certainly known patients who were all but incapacitated by hay fever and who were not helped a bit by the existing medications. For them, the cost-benefit balance favors allergy shots. But for most hay-fever patients, immunotherapy probably represents overkill. (Though the cost-benefit considerations may well favor immunotherapy to prevent more dangerous allergic reactions, like the potentially lethal effects sometime caused by bee stings).

Screening for birth defects

Standard tests: For many years, the standard way to screen in utero for problems like Down syndrome has been to remove amniotic fluid through the wall of the uterus and analyze it for evidence of metabolic or chromosomal problems. Another method involves collecting a tiny bit of tissue from the sac surrounding the developing embryo using a thin tube passed through the vagina and through the cervix. Both of these tests are quite accurate in diagnosing a chromosomal defect but invasive. And each comes with a small risk of miscarriage.

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New research: A promising alternative is described in recent research reported in the British medical journal the Lancet by a group led by Dr. R. Dhallan of Ravgen Inc., a company developing new methods of prenatal diagnosis. Dhallan's used fetal DNA, which is always present in the liquid portion of maternal blood during pregnancy. By comparing DNA from the liquid portion of the mother's blood with DNA from the father's blood cells and DNA from the mother's blood cells, it is possible to determine which DNA in the mother's blood belongs to the fetus. That fetal DNA can then be tested for abnormal genes or chromosomes associated with known diseases. In the Lancet report, this method identified Downsyndrome with good, though not perfect, accuracy. (Down syndrome represents a particularly difficult challenge for a method like this one, because the abnormality is an extra copy of a normal chromosome, not the presence of an abnormal one. The laboratory thus must not only differentiate the fetal DNA from the DNA of the mother, but also determine an overabundance of fetal DNA from one particular chromosome—quite a challenge.)

Conclusion: A noninvasive method of prenatal diagnosis represents a real advance. But further research is needed to improve accuracy before it is suitable for clinical use.

Smell yeast paste, and live forever

Longevity: It's been known for about 70 years that nutritional deprivation can sometimes lead to increased longevity. For instance, fruit flies kept semistarved by being deprived of yeast and sugar, their favorite nibblies, live longer than flies with free access to these treats. The mechanism of this phenomenon is still being debated. Meanwhile, here's another twist.

New research: A recent report by Sergiy Libert, Scott Pletcher, and colleagues at the Baylor College of Medicine in Houston shows that just giving flies their favorite food, yeast paste, to smell shortens their lifespan—while genetically modifying the flies to diminish their sense of smell increases longevity. This is the case even if the flies are given free access to food they cannot smell. (Though they eat plenty, anyway.)

Conclusion: I have long been convinced that I can put on weight just by smelling food. Now it seems I have to contemplate the painful idea that the aroma of last night's apple cake is working to shorten my life in two different ways—by stimulating my appetite and blocking that mysterious longevity mechanism. Oh, well, I was never cut out for semistarvation, anyway.

Sydney Spiesel is a pediatrician in Woodbridge, Conn., and clinical professor of pediatrics at Yale University's School of Medicine.