It's a startling fact: An analgesic we regularly give babies and children is the No. 1 cause of acute liver failure in the United States, ahead of viral hepatitis. Acetaminophen - Tylenol, Tempra, Anacin-3 - is safe when given in proper therapeutic doses. But an overdose of acetaminophen can cause serious liver injury, or even kill. Dr. Laura James, 40, of Arkansas Children's Hospital, has seen what acetaminophen overdose can do. One of 15 ER physicians who staff the Emergency Room at Children's, James has treated teen-agers - making what she calls "suicidal gestures or attempts," ignorant of the danger the over-the-counter drug can pose - and children whose caregivers mistakenly given too much of the drug. Two children she treated died. Others have been referred for liver transplants. Drugs are James principal interest, and the 10-year veteran of Children's now devotes three-fourths of her time to clinical and laboratory research into pharmaceuticals. She is co-principal investigator of Children's NIH-funded Pediatric Pharmacology Unit, one of only 13 in the country. These units were created in the mid-1990s response to the lack of pediatric drug dosing information - a study showed that 70 percent of the drugs listed in the Physician's Desk Reference do not include dosage information for children. Now, the FDA requires that new drugs on the market that will likely be used on children must be tested in children, as part of the complete evaluation of the drug. In time, pediatricians will no longer have to rely on experience and collective knowledge to determine what medicines are safe for their young patients. James and principal investigator Dr. Tom Wells are looking at the efficacy and proper dosage of drugs used to treat children, including acid-lowering drugs, high blood pressure medicines and antibiotics. In the near future, their research will expand to studies on sedatives for children in intensive care and to evaluate the best drugs for the treatment of seizures in children. James said the unit's success derives from its ability to collaborate with numerous subspecialists at ACH - pediatric neurologists, rheumatalogists, critical care specialists, infectious disease specialists and gastroenterologists. James also collaborates with toxicologist Dr. Jack Hinson of the University of Arkansas for Medical Sciences in research on mouse models to study how acetaminophen damages liver tissue. She hopes to take her studies from "bench to bedside," to promote new therapies for acetaminophen overdose. Sitting in the resuscitation room at the Children's ER, James reflected on what it is about pediatrics that attracted here to the field. "It's easy to be excited about pediatrics," she said, a field that provokes "the full range of human emotion." The greatest rewards come at those times, she said, in which she thinks " I really made a difference, I turned things around." The work can be wrenching, and the professionals of the ER do at times shed tears and get angry. James, who's married to radiologist Dr. Charles James, said being a mother has made it even harder to see injured or ill children. They come to the ER with trauma, asthma, gunshot wounds (18 last year, two fatal), viral infections, chest pains, vomiting. Some injuries could have been avoided, by the use of a car seat, a bike helmet, a lock on the kitchen supply door. They've been thrown off jet skis, four-wheelers (66 last year), hit by cars. Some 40,000 children a year come to the ER (first through its metal detectors, a sad comment on society); 14 percent are admitted. Unlike doctors for adults, pediatric ER doctors and nurses must assume an advocacy role for their patients. Children's ER is so busy at night ("the crazy time," she said) that three attending physicians are on hand to oversee the residents' evaluation of patients. These doctors must both treat the child and, if necessary, address the circumstance that landed him in the hospital. Do the bruises and broken bones and bleeding match the accident described by the adult who brought them in? Or should the social worker be called in to investigate the likelihood of abuse? "We see it commonly," James said, in children of all racial and economic backgrounds. The other difference from the adult emergency room: Child-sized equipment - little boards just inches long to brace a baby's arm, little needles, and more. At bedside, though, James notes, hearts and patience must be big. Doctors and nurses - James especially credits those who can calm a child with talk and a soft touch - must have just the right manner.