The researchers conducted a series of psychological tests on 120 volunteers as they were exposed to mobile phone emissions for half an hour.

Another set of tests was conducted on volunteers who were not exposed to mobile phone radiation but thought they were.

The results, published in April's edition of the journal Neuropsychologia, showed a small but discernable change in brain function among those who were exposed to the electromagnetic fields that mobile phones generate.

"The study showed evidence of slower response times for participants undertaking simple reactions and more complex reactions, such as choosing a response when there is more than one alternative," lead researcher Con Stough said.

"This could equate to driving a car and being distracted by another car pulling out in front of you. The drivers reaction time to chose between braking, turning or sounding the horn, could be affected, albeit slightly.

"The study also found that radiation from mobile phones seems to improve working memory, used for example when remembering a phone number long enough to dial it."

He said further work was needed using magnetic resonance imaging to clarify the way mobile phones alter on the way the brain works.

Stough said further, as-yet-unpublished, research by his team suggested the impact of mobile phone radiation on the brain was cumulative.

"People, for instance, who use the mobile phone a lot seem to have more of an impairment than people who are more naive users," he said.

However, he stressed that the impact on brain function was small and the study did not find that mobile phones caused a health problem.

"We haven't established that there's negative health consequences -- that's a different type of study," he said.

"We're just showing that the radiation is actually active on the brain. But the impairment is small. The convenience and the way that we communicate now these days outweighs that effect."

For example, condom use in Ghana and Senegal seems to have helped in the reduction of the spread of the HIV, which in those countries is particularly prevalent among commercial sex workers and their partners. However, condom use in South Africa and Botswana has had little effect in reducing those countries' HIV epidemics -- which have reached the general population -- because regular sex partners rarely use condoms consistently. In comparison, faithfulness to one partner has worked at reducing HIV prevalence in Uganda and Kenya, according to Halperin.

Because a person is more likely to transmit HIV during the first three weeks of contracting the virus, an HIV-positive person who has just one partner during that time is likely to pass the disease to that one person. But if an HIV-positive person in the highly infectious stage has many sexual partners at a time, "the virus spreads like wildfire" as those people in turn have sex with other people, Halperin said.

In addition, circumcision has been shown to reduce male-to-female HIV transmission by 60% to 75% (Goering, Chicago Tribune, 4/23). A study published in the November 2005 issue of PLoS Medicine of men living in South Africa finds that male circumcision might reduce the risk of men contracting HIV through sexual intercourse with women by about 60%. Male circumcision might also reduce the risk of HIV transmission from HIV-positive men to their female partners, according to a study of couples in Rakai, Uganda (Kaiser Daily HIV/AIDS Report, 2/9).

Poverty Reduction, Status Awareness

In addition, poverty does not appear necessarily to make a person more susceptible to HIV. "[C]ontrary to popular wisdom, as income levels go up in both men and women, we see higher rates of HIV," Halperin said, adding that people who make more money tend to have more sexual partners. Other HIV prevention methods such as encouraging people to know their status and treating secondary sexually transmitted infections also have not proven effective, Halperin said (Chicago Tribune, 4/23).

The use of animal thyroid extract in slimming pills is banned in the French medical profession's code of ethics, but it is not against the law.

Normally prescribed to help patients with over-active thyroid glands or diabetes, the treatment is supposed to boost metabolism and limit the body's absorption of fats and sugars.

Analysis of the suspect capsules showed that they contain accepted amounts of dried pig thyroid extract, but also large amounts of "another substance of thyroid origin which was not part of the prescribed preparation," the health ministry said.

Further tests were under way to determine the nature of this substance.

The alarm was raised after a person -- whose name and sex have not been made public -- died in a Paris hospital on April 18.

Since then 16 people have been hospitalised after experiencing symptoms including palpitations, fever, vomiting and diarrhoea.

The five in intensive care are either in a coma or suffering from "neurological difficulties," according to Didier Houssin, director-general at the health ministry.

A judicial investigation has been opened, and the Order of Doctors -- the medical profession's official body -- has also launched an enquiry. The pharmacy where the capsules were prepared has been provisionally closed.

The affair has focussed critical attention on the fashion for quick-fix weight cures, many accessible via the Internet, and prompted calls for more effective regulation.

Those who took the white-and-blue capsules were all prescribed them by an endocrinologist -- a gland and hormone specialist -- as an effective way of losing weight.

"In normal doses this treatment is not at all dangerous. Of course if there are 20 times the correct amounts of thyroid extract, it will act as a poison. But I prescribed a normal treatment," the specialist -- named only Olivier C. -- told Le Parisien newspaper.

But senior health officials said unscrupulous doctors were making money out of a treatment that should be confined to genuine medical disorders.

"This affair shows how some doctors are prepared to take leave of the rules and do whatever they like. ... It is revolting behaviour," said Patrick Pelloux, president of the Association of Emergency Hospital Doctors.

"Many women fall victim to these practices because they are ruled by the slimming dictatorship. But these irregular weight treatments are extremely dangerous for the health, and now we have the startling proof. We urgently need tighter controls," he said.

"We try to promote healthy behavior for a lifetime," said Dr. Goutham Rao, clinical director of the Weight Management and Wellness Center at Children's Hospital of Pittsburgh where Trevor got help.

Rao said that when the hospital began planning for the clinic about three years ago, there were about half a dozen similar programs across the country. Now, there are around 50 and more on the way, he said.

The clinics are opening at a time of skyrocketing obesity rates among U.S. children. Nearly 1 out of 5 is obese, according to government figures, putting them at a greater risk for diabetes, heart disease and a host of other problems.

Dr. Sandra Hassink, director of the weight management program at the Alfred I. duPont Hospital for Children in Wilmington, Del., said she's seen patients getting younger and heavier since she helped start the program 18 years ago. Her youngest patient was 5 months old.

"It's scary and we're going to end up with young adults who should be healthy who are bearing the burden of a chronic illness," she said.

A member of the American Academy of Pediatrics' obesity task force and lead editor of the "Parent's Guide to Obesity," Hassink said parents must be involved if a child is going to succeed at keeping weight under control.

Children usually aren't shopping for food or making decisions about what to eat for dinner, said Dr. Christopher Bolling of Cincinnati Children's Medical Center.

"You're not going to have any success if you approach just the child because the child doesn't have complete regulation over the environment. You have to go after the family," said Bolling, medical director for the Cincinnati hospital's weight management center.

Bolling said one of the biggest challenges is finding a way to pay for the weight programs, which usually aren't covered by insurance. Thanks to a $3 million federal grant, the Pittsburgh clinic doesn't charge its patients for the service.

But doctors say no matter what the cost, it's far less than the expense of treating problems from obesity. According to the Centers for Disease Control and Prevention, hospitals spent $127 million in 1999 on obesity-related illnesses, up from $35 million in 1981.

At the Pittsburgh hospital program, children see exercise physiologists and behavioral psychologists, along with medical doctors.

Children and their parents are asked to sign a "contract" promising to pursue healthy habits - from changing the way they eat to being more physically active. The words obesity and fat are avoided.

Located in a medical building near the hospital, the clinic's waiting room offers some larger-than-normal chairs for bigger frames.

A nervous Abigail Auria sat in one of the clinic's patient rooms recently, clad in her bathing suit under a paper hospital gown. It was the 12-year-old's first visit and she was waiting to get into the BodPod, an oval, space-age looking contraption that checks kids' body-mass index.

Abigail was referred to the hospital by her pediatrician, who noticed she had been steadily gaining weight.

"It embarrasses me," the girl said.

Her mom, Jamie Auria, who is a diabetic, hopes the center will help her daughter change her lifestyle and avoid getting diabetes herself.

"We don't want to add any risk to what she already has to deal with," Auria said. "But knowing and understanding and actually doing are two different things."

Down the hall, Trevor and his mom proudly talk about all he's accomplished with the center's help. Trevor said talking with doctors about weight loss was different from discussing it with his parents.

"I heard it all the time," Trevor said, "but something like this really motivates you to do it."