Of allergy, pets, and breast milk

Results of new studies challenge long-held beliefs

"PAINTICIPATION"

CHICAGO

Infants learn to anticipate pain after their first few encounters with a needle.

    A University of Toronto-Hospital for Sick Children study found newborn babies of diabetic mothers had been sensitized to the sharp pain that comes with being jabbed in the foot with a needle after just 24 hours of life.

    By that time the babies had had blood taken several times so physicians could monitor their blood glucose level. So when these babies were being prepped for routine blood collection at the one-day mark, they reacted more intensely than regular babies because they recognized the cues that went with the procedure.

    The babies grimaced much more than the normal infants when the back of their hands were being cleansed in preparation for the venipuncture-in which blood is taken from the back of the infant's hand for routine disease-screening purposes-than the babies of nondiabetic mothers. And they grimaced, squirmed, and cried much harder during and after the procedure than the control babies.

    "We suggest that throughout the course of repeated exposure to skin cleansing followed by heel lancing, skin cleansing became a conditioned stimulus, reliably signaling the impending painful event and inducing anticipatory pain behaviors and possibly even pain," wrote Anna Tadio, an assistant professor of pharmacy at the University of Toronto.

    The findings suggest doctors should find more effective ways of managing neonatal pain during invasive procedures to prevent them from becoming extrasensitive to pain, they added.

FIRST STICK IS ALL IT TAKES

PARIS

Children can get hooked on nicotine within days, with addiction perhaps starting with the first cigarette, according to a new American study published in the specialist Tobacco Control publication. Not only can children get hooked on nicotine with amazing speed and but at levels of tobacco that are so low that nobody had even considered it possible, say the researchers.

    Joseph DiFranza of the University of Massachusetts Medical School and his team followed 679 12- to 13-year-olds over a period of 30 months. Among 332 students who had ever tried tobacco-even just a puff-40 percent reported symptoms of addiction (strong cravings, really needed a cigarette, irritable, nervous or anxious because you couldn't smoke, hard to quit).

    Among 237 students who had inhaled, 53 percent reported symptoms. For teenage girls who got hooked, it only took an average of three weeks from when they started to smoke occasionally. Among the boys, half were hooked within six months of the start of occasional smoking.

    "Some of these kids were hooked within a few days of starting to smoke," said Dr DiFranza. "Perhaps even more surprising than the speed with which symptoms of addiction appeared was the very small amount of tobacco required," added the authors. Until now, scientists have assumed that addiction does not begin until youths are smoking at least ten cigarettes per day.

    But according to this study, half of youths who showed signs of being hooked were smoking an average of only two cigarettes per week, and in two-thirds of youths, addiction appeared prior to daily smoking, suggesting that addiction comes before tolerance to nicotine.

    The authors used the term "juvenile onset nicotine dependence" to emphasize that children are different from adults when it comes to the effects of nicotine. "Because the adolescent brain is still developing, adolescents may be more vulnerable to addiction than adults. The impact of nicotine on the brain is also stronger and longer lasting on adolescents," suggested the authors.

    "Data from human and animal studies lead me to suspect that addiction to nicotine begins, in many cases, with the first cigarette," concluded DiFranza.

WEAPON VERSUS CANCER

WASHINGTON

For generations burns have been soothed by aloe, pain taken away by poppies; now researchers have found the corn lily may be a weapon against children's brain cancer.

    In a study published in Science Magazine, researchers found that the chemical agent cyclopamine found in corn lilies blocked the growth of medulloblastomas, malignant tumors in the central nervous system. The incurable cancer usually takes hold at the base of a child's cerebellum and usually spread rapidly.

    Researchers from Johns Hopkins and Howard Hughs medical schools found that cyclopamine destroyed samples of these cancerous cells and even tumors transplanted into mice.

    But Philip Beachy, who directed the study, said "it will be difficult to obtain sufficient quantities of cyclopamine, since it must be extracted and purified from the plant source, Veratrum californicum, the corn lily." Nevertheless, he added "the evidence is in place to justify an effort to develop a supply so that it can be tested in humans."

"PETTY" TRUTHS

WASHINGTON

Young children raised with cats and dogs are at much less risk of developing common pet allergies, according to a US study in The Journal of the American Medical Association.

    "We simply started looking at our data to see whether exposure to dogs and cats really increases the risk, and the data didn't look the way it was supposed to. As a matter of fact, it was very strongly the opposite of what we expected to find," said study co-author Dennis Ownby, chief of the Medical College of Georgia Section of Allergy and Immunology.

    Over seven years the researchers compared 184 children exposed to a minimum of two dogs or cats with 220 children whose families had no such animals. They discovered 15.5 percent of children in families with no cats or dogs developed cat allergies, 50 percent more than the 7.7 percent of those with two or more cats or dogs. The same results proved true for dog allergies, with 8.6 percent developing the allergy in households without dogs and cats, versus only 2.6 percent in the other group.

    "The bottom line is that maybe part of the reason we have so many children with allergies and asthma is we live too clean a life," Ownby said. "What happens when kids play with cats or dogs? The animals lick them. The lick is transferring a lot of bacteria and that may be changing the way the child's immune system responds in a way that helps protect against allergies," he explained.

    He added: "Allergists have been trained for generations that dogs and cats in the house were bad because they increased the risk of you becoming allergic to them; we know that before you become allergic to something, you have to be repeatedly exposed to it. This is exactly the opposite of what we would have predicted from the beginning, and it's very significant."

BREAST ISN'T FOR ASTHMA

PARIS

The widespread notion that breast milk helps keep babies from developing asthma and allergies has run into flak from a new study that suggests it may in fact do the exact opposite.

    The research published in The Lancet found that New Zealand babies who had been breast-fed for more than four weeks ran almost double the risk of contracting asthma or allergies in their childhood compared with babies who had been fed on infant formula, "contrary to expectations," said Otago University's Professor Robin Taylor. "These effects were seen whether or not there was a family history of asthma and allergies," Taylor said.

    The study was conducted among 1,037 infants, born in 1972 and 1973 in Dunedin, on New Zealand's South Island, 49 percent of whom had been breast-fed. They were assessed for respiratory function and asthma symptoms every two to five years up to the age of 26, and allergies, tested by skin prick, were done at the ages of 13 and 21.

    "Breast-feeding could be promoted for many reasons, including optimum nutrition and reduction of risk of infant infections," said co-author Malcolm Sears of McMaster University in Hamilton, Ontario. "However, the role of breast-feeding in protection of children against atopy and asthma cannot be supported on the basis of the present balance of evidence."

BUT ENDOTOXINS ARE

WASHINGTON

Children more exposed to environmental bacteria, like those who live in rural areas, are less prone to develop asthma and other allergies, according to researchers who compared 812 children between the ages of six and 13 living in 319 rural and 493 urban households in Switzerland, Germany and Austria. Samples of endotoxins were vacuumed up from the children's mattresses and compared with the frequency of asthma and allergy occurrence.

    The scientists found an inverse relationship between the endotoxins and the sicknesses. "The greater the endotoxin exposure, the less likely it was that children had asthma," said study co-author Charlotte Braun-Fahrlander of the Institute of Social and Preventive Medicine at the University of Basel in Switzerland.

    The study involved a total of 15 authors from seven institutions across the three countries. They concluded that "a subject's environmental exposure to endotoxins may have a crucial role in the development of tolerance to ubiquitous allergens found in natural environments" such as asthma, hay fever, and other allergies.

    Among children living in rural households, where the exposure to endotoxins was almost twice as high, only 10 percent developed allergic asthma and five percent nonallergic asthma versus 29 percent and 13 percent of the other group. The difference is even more drastic with hay fever with only 13 percent of the farming group developing the allergy, versus 52 percent of the nonfarming group.