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Review raises questions about drug studies on rats


PAUL TAYLOR

Each week, it seems, there's another study showing that scientists have found a "cure" for some disease in laboratory rats. But are these animal experiments really useful in predicting which new treatments will be safe and effective for people?

A team of British researchers recently completed a scientific review that raises troubling questions about the merits of rodent studies.

In particular, the team analyzed the scientific literature for six drugs used to treat a variety of conditions including head injuries, strokes and osteoporosis.

They looked at the results from the human trials and compared them with the earlier animal experiments.

It turns out that the animal studies didn't jibe with the human results in half the cases, according to the findings published in the British Medical Journal.

One of the researchers, Ian Roberts, a professor at the University of London, said the team would need to review a lot more drugs to come up with a reliable estimate of how often animal studies fail to accurately predict human outcomes.

However, he added, it is clear that those who run animal experiments could be doing a better job.

"In general, the methodological quality is very poor," he said. The animal studies are often done in such a way that the results can't be applied to humans. "Some of the models just didn't make sense."

In the case of a drug for head injuries, "we found they would bash a rat on the head and give the treatment five minutes later," he said.

In reality, a person would not likely receive the treatment until several hours after an accident.

But the biggest problem is so-called "publication bias." The studies that get published are those showing that a drug works. The failed experiments for the same drug tend to be buried.

"If the people who do [human] clinical trials are only seeing good news because the bad news is withheld . . . then they will go off on the wrong tangent," wasting patients' time and research dollars.

Dr. Roberts noted that opinion polls show the public supports animal experimentation, "provided the studies improve human health, there is no unnecessary suffering and there are no alternatives."

To maintain public confidence, those who conduct animal studies need to "wake up" to the "big problems in their area," he said.

Doing harm to others

Diana, Princess of Wales's death in a car crash nine years ago can be partly blamed on the fact that she wasn't wearing a seat belt. But unbuckled back-seat passengers, such as Diana, aren't just putting their own lives in jeopardy. In a head-on crash, they can become flying projectiles and can do harm to other passengers -- even those who are wearing their seat belts.

U.S. researchers demonstrated these risks during simulated accidents using crash-test dummies. In their study, published in the Journal of Trauma, they found that unbuckled rear seat-passengers will slam into the seat in front with a huge force. That impact can harm the person in the front seat, said the lead researcher, James Mayrose, who teaches mechanical engineering at the University of Buffalo.

During a front-end collision, he noted, the airbag inflates in a split second with an explosive energy. Under normal conditions, the seat belt and shoulder strap will hold the front-seat passenger far enough back to avoid serious injury from the expanding air bag.

"But if someone hits your seat, they can push you closer to the air bag and you can get injured," Dr. Mayrose said.

In the case of drivers, the thrust from behind can slam them into the steering column, leading to major chest injuries.

However, unbuckled passengers aren't the only threat to those in the front seat. "Anything that is not restrained or tied down will be thrown forward," he said.

"We've coined the phrase 'back-seat bullets.' "

People should use common sense to make sure everything is safely stowed away, he said.

"Rather than leaving an object on the back seat, put it on the floor behind you where it is less likely to do harm."

Preventing ear infections

The list of the benefits of mother's milk keeps getting longer. Now, new research suggests it might also help some children avoid ear infections.

Researchers at the University of Texas have pinpointed several genes that make some prone to ear infections.

They estimated that about 19 per cent of children are born with a genetic susceptibility to chronic or frequent ear infections, medically known as otitis media.

Janak Patel, who led the research team, believes these specific genes cause an overproduction of certain immune cells, called cytokines, which can sometimes result in excess inflammation in the ears.

The elevated inflammation, in turn, could block the ear tubes and spur an invasion of bacteria from the nasal passages.

In their latest study, the researchers found breastfeeding seems to partly "neutralize" this natural tendency to develop ear infections among these genetically vulnerable children.

The added protection continued even after the youngsters were weaned.

"Children who were not breastfed or breastfed very little [less than one month] . . . had 1.4-fold and 2.2-fold, respectively, higher risk for OM," he said in an e-mail.

They don't know why breastfeeding helps prevents ear troubles. But, Dr. Patel speculates, "breast milk . . . contains certain molecules that protect the mouth and nasal passages from infections."
 

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