Jewish World Review

Researchers may have found clue to SIDS | (KRT) Researchers at the University of Chicago believe they have found a clue to why children die of sudden infant death syndrome, or SIDS, by examining how the brain regulates gasping for air when it doesn't get enough oxygen.

The new finding, published Thursday in the journal Neuron, may one day help identify children at risk for the syndrome, which in the United States is the leading killer of children under the age of one, said Jan-Marino Ramirez, the lead researcher of the study.

Some experts believe that children die of SIDS because they fail to gasp - or inhale - when they sleep on their stomach and don't get enough oxygen.

In 2001, 2,236 children died of SIDS in the United States, according to the Centers for Disease Control and Prevention. The deaths have been more than cut in half since 1992, when the government and private organizations started a campaign telling parents to put their babies to sleep on their backs.

For their experiments, Ramirez and his colleagues cut tissue from mouse brain stems - the part of the brain known to regulate breathing. Working with these tissues in petri dishes, they showed that the healthy cells fired when deprived of oxygen - which would prompt gasping. But if the cells were also inhibited with chemicals, the cells did not function.

That leads the researchers to conclude that if similar cells are not functioning properly in babies, the child might not gasp when oxygen levels fall.

Some researchers hailed the finding as promising but cautioned that further studies are needed.

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"If correct, this is a spectacular result," said Jack Feldman, a neurobiologist at UCLA. But, he said, further experiments are needed to prove that it is really these pace maker neurons that generate the rhythm.

Others said it is not even clear whether SIDS results from a problem with breathing or the failure to gasp in the first place. "I think it is hard to quantify whether there are fewer (gasps in children with SIDS), although that is certainly possible," said Dr. George Richerson of Yale University. "The problem is that none of these possibilities have been well proven, and there is data to suggest other systems (temperature control, blood pressure control, etc.) may be abnormal (in SIDS children)."

Ramirez said the new findings point to a lower level in serotonin in the nerve cells as one possible cause for SIDS.

Serotonin is a chemical that regulates nerve cell activity in the brain, and Ramirez's team had shown in 2002 that the nerve cells required for gasping need the chemical to operate.

Based on autopsy studies, researchers at Harvard University found in 2001 that serotonin is less active in the brain stem of SIDS victims.

Ramirez said the new findings provide the missing link between problems with gasping and the lower serotonin activity in the brain stem of SIDS children.

"We knew that SIDS starts because you have no gasping, and we knew that in the brain stem there is little serotonin," Ramirez said. "Now we can show that (these children) don't gasp because these nerve cells need serotonin to do the gasping."

But Ramirez said there could be other things wrong with the pace maker cells. He said that sodium has to enter the cells through channels in the membrane, which may be defective in children with SIDS.

"It could also be a mutation of the sodium channel that would make you develop SIDS," Ramirez said, adding that heart problems in SIDS children have been linked to sodium channel mutations.

One day, he said, it may be possible to do genetic screening for such mutations to identify children susceptible to SIDS.

Ramirez said he was "surprised" by this comment. "For many years people suspected that SIDS has something to do with breathing and gasping," he said. "That was the prevailing view as far as I know."

To physicians, SIDS remains a rather mysterious disease, diagnosed by excluding all other causes of death, said Dr. Debra Weese-Mayer, who studies SIDS children at Rush University Hospital in Chicago.

Ramirez said this uncertainty often leaves the mothers of children that die of SIDS wondering if it is their fault that their child died.

"I think looking for the biological cause (of SIDS) is really an important task for the mothers that love their baby," Ramirez said. "They really want to know what happened."

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© 2004, Chicago Tribune Distributed by Knight Ridder/Tribune Information Services