Puppy love

Pet theory Could a baby who grows up among dogs and cats be less likely to later suffer from allergies and asthma than those in pet-free homes? It sounds counterintuitive, but preliminary research suggests so. Several studies on pet exposure during infancy hint that animals may help children build up their defenses. Scientists are considering the hypothesis and several studies have provided surprising results. Christine C. Johnson, a researcher with the Henry Ford Health System in Detroit, found that children living with two or more pets at age 1 were less susceptible to other allergens by age 7. In another study, Dr. Thomas Platts-Mills, a University of Virginia allergy research specialist, studied 226 children aged 12 to 14 in New Mexico and Virginia. He found that early exposure to cat dander decreased the asthma risk but may not have affected other allergies. A team of Swedish researchers reached the same conclusion. Dr. Platts-Mills says he's a long way from a definitive conclusion: "Are we proposing that if every house in the county had cats, everything would be all right? I doubt it." The pet studies seem to confirm what scientists call "hygiene hypothesis." It holds that our society has been cleaned out by widespread vaccination, antibiotics, and overall heightened health standards. While this has improved life overall, it has a downside: people who can't build tolerances to potential toxins and become hypersensitive to contamination. The "hygiene hypothesis" is a popular explanation for asthma's boom in recent years. Cases have more than doubled since 1980-and 5,000 people die from it each year. Millions have less serious problems: runny noses, swollen eyes, and itchy skin. About 40 million Americans suffer from allergies today. Take heart Established medical science says damage to the heart is irreversible. New research suggests a reason to believe otherwise, and that has positive implications for the one in four Americans who lives with heart disease. A report in the New England Journal of Medicine suggests damaged hearts may be able to repair themselves by growing new cells. Researchers led by Dr. Piero Anversa, director of the Cardiovascular Research Institute, examined hearts of 13 patients who had died four to 12 days after suffering a heart attack and found a significant amount of new cardiac muscle being formed. They found that heart muscle cells called myocytes had begun dividing after the heart attack. "We didn't know before. Now we know that heart cells divide. It's obviously highly significant," said David Finkelstein of the National Institute on Aging, which helped fund the research. "If one could find a way to turn on this division, it would be very important." The Journal noted that these findings challenge established medical dogma. Experts hope to discover more about this mysterious mechanism that repairs heart tissue and use it to fight heart disease. They would like to stimulate hearts to mend themselves after a heart attack or heart failure. Dr. Anversa hopes to find the existence of certain cardiac cells that can multiply to regenerate tissue: "There are preliminary indications that primitive cells like stem cells exist in the human heart." Hold the mayo Smoking may be America's most vilified public-health nightmare, but a study says obesity is even worse. Those considered heavily overweight have more chronic health problems than smokers, heavy drinkers, or the poor, according to a RAND institute report-and average nearly two times the health trouble of people with normal weight. A 1998 telephone survey of 9,585 adults found that three of five were either overweight or obese. RAND's Roland Sturm and Kenneth Wells, authors of the survey, which was published in the British journal Public Health, say obesity is "on the rise in all segments of the population." Last April, the World Health Organization (WHO) reported a link between cancer and obesity, reporting that up to one-third of cancers of the colon, breast, kidney, and digestive tract are attributable to too much weight gain and too little exercise. In addition, obesity increases the risk of heart disease and diabetes. Obesity is defined by one's body mass index, or BMI, which is determined by multiplying a person's weight in pounds by 703 and dividing that result by height in inches squared. Normal BMIs are between 18.5 and 24.9, overweight scores are from 25 and 29.9; obese people fall between 30 and 34.9 and the very obese are over 35. So a six-footer needs to stay below 185 pounds to be in the safe range. Both the RAND researchers and the WHO recommend public anti-obesity campaigns. RAND's Mr. Sturm called for a crusade equal to the war against tobacco. Critics of such efforts complain about a "nanny culture" of creeping government paternalism-including such measures as advertising restrictions, "fat taxes" on junk food, and strict labeling requirements.