Fasting may reduce chemo side-effects

A few days of fasting might help protect patients from some of the unpleasant and dangerous side-effects of cancer chemotherapy, researchers reported on Tuesday.

They said mice given a high dose of chemotherapy after fasting thrived while half of a group of well-fed mice died, they reported in the Proceedings of the National Academy of Sciences.

The researchers stressed that people should not try this on their own yet but said the findings might lead to a way to use chemotherapy to more effectively kill tumors while sparing healthy cells.

Valter Longo of the University of Southern California and colleagues first tested yeast cells, then human cells in lab dishes. They found healthy cells starved of nutrients survived the ravages of chemotherapy -- but not cancer cells.

"In theory, it opens up new treatment approaches that will allow higher doses of chemotherapy. It's a direction that's worth pursuing in clinical trials in humans," cancer researcher Pinchas Cohen of the University of California, Los Angeles, who was not involved in the study, said in a statement.

Longo and colleagues said animals fed a low-calorie diet live longer, in part because their cells can resist stress better. They also noticed that starved cells go into a kind of hibernation mode, while cancer cells form tumors because they lack an "off" position, growing uncontrollably.

Longo wondered if the starvation response might be a way to differentiate healthy cells from cancer cells. One reason chemotherapy causes side-effects is that it affects all active and growing cells -- tumors, but also hair follicles, the lining of the intestines and other cells.

"Here, we tested the hypothesis that short-term starvation or low glucose/low serum can protect mammalian cells but not or to a lesser extent cancer cells, against high doses of oxidative damage or chemotherapy," they wrote.

"We administered an unusually high dose of etoposide (80 mg/kg) to ... mice that had been starved for 48 hours. In humans, one-third of this concentration of etoposide is considered to be a high dose and therefore in the maximum allowable range," they wrote.

The high dose killed 43 percent of the mice that were fed normally but just one starved mouse. The starved mice regained their lost weight within four days.

An even higher dose killed all of the well-fed mice from a different genetic strain but none of the starved mice, and again the mice that fasted regained their weight.

Other cancer experts said a few days of fasting would not harm most cancer patients.

"This could have applicability in maybe a majority of patients," said Dr. David Quinn of the University of Southern California.

"We have passed the stage where patients arrive at the clinic in an emaciated state. Not eating for two days is not the end of the world," agreed Felipe Sierra, director of the Biology of Aging Program at the National Institute on Aging.

Growth hormone no benefit to athletes

People who take human growth hormone in the hope of boosting athletic performance are not only breaking the law and risking their health, but likely are not even achieving their objective, U.S. researchers reported on Monday.

While some reports show that some illegal steroids may help athletes bulk up and train harder, human growth hormone is not one of them, the report in the Annals of Internal Medicine suggests.

"What we saw is that while there was a change in body composition, we didn't find evidence that growth hormone improves athletic performance," Dr. Hau Liu of Stanford University in California, who led the study, said in a telephone interview.

Liu's team looked at 27 studies covering 303 people aged 13 to 45. They found that, overall, those who took growth hormone did develop more lean body mass, but this did not translate to either more strength or exercise capacity.

People who took growth hormone had swelling of their tissues and more fatigue compared to people not taking the drug, they added.

Use of growth hormone is banned by the International Olympic Committee, Major League Baseball and the National Football League. U.S. law prohibits its use for sports enhancement.

When the hormone is given to people with growth hormone deficits caused by pituitary tumors or other conditions, it can improve strength. But it does not enhance strength in normal, healthy people.

For example, people given hormone generated more lactate, a byproduct of exercise that can cause pain and muscle fatigue. In one study meant to see if human growth hormone might boost strength or endurance, two cyclists given the hormone stopped a workout because of fatigue.

"The key takeaway is that we don't have any good scientific evidence that growth hormone improves athletic performance," Dr. Andrew Hoffman, a professor of endocrinology, gerontology and metabolism who worked on the study, said.

Hoffman noted that other hormones have been shown to benefit athletes -- notably testosterone.

"Athletes probably take much more hormone than the investigators felt that they could ethically try to give to healthy people; in addition, some athletes combine growth hormone with other anabolic hormones like testosterone," Hoffman added in an e-mail.

Hoffman said people get side-effects from high doses of hormones. "You you get fluid accumulating in the legs, you get pain in the joints," he said in a telephone interview.

"From what we hear the athletes are taking very, very large doses," he added.

Other hormones do, however bulk up athletes -- although not without risk, Hoffman said. "The findings with growth hormone absolutely do not extend to other hormones like testosterone which work through entirely different mechanisms," he said.

Hospital tests for 'superbug' effective

Testing every hospital patient to find and treat carriers of a drug-resistant bacteria can curtail outbreaks of dangerous infections, according to a study released on Monday, but some researchers questioned whether universal screening is the solution to the problem.

The authors of the four-year study conducted in three suburban Chicago hospitals concluded that universal patient screening for methicillin-resistant Staphylococcus aureus, or MRSA, reduced infection rates by 70 percent.

But another researcher who wrote an editorial accompanying the study, which was published in the Annals of Internal Medicine, said credit for fewer illnesses could be due to better hand-washing and cleaning practices by hospital staff.

The study compared MRSA infection rates when no screening protocol was in place, to when only intensive care unit patients were tested, and to when nearly all patients were screened over a 21-month period.

Without the screening there were nearly nine new infections per 10,000 days of patient care. After universal testing was put in place, infections declined to about four per 10,000 patient-days, a 70 percent drop.

"The program we began in August of 2005 had a major patient safety impact for all our patients and demonstrated that a comprehensive effort to reduce MRSA infection can be accomplished," Dr. Lance Peterson of Evanston Northwestern Healthcare in Illinois, who worked on the study, said in a statement.

Among the authors of the study were several researchers with financial ties to Becton Dickinson & Co, a manufacturer of a test for MRSA.

Dr. Ebbing Lautenbach of the University of Pennsylvania, commenting on the study in an editorial in the journal, said it was premature to recommend universal MRSA screening.

Lautenbach said pressure on hospital staff to perform the screening consequently focused attention on following proper hygiene practices.

He also cautioned that extensive use of an antibiotic ointment to treat MRSA carriers may promote additional drug resistance. Only a few antibiotics are effective against MRSA, which is resistant to common infection-fighting medications.

As many as 1.5 percent of Americans carry MRSA, and they may spread it to others while not developing an infection themselves. Most dangerous infections occur in hospitals, where weakened patients are susceptible, and it was blamed for 19,000 U.S. deaths in 2005.

A Geneva, Switzerland, hospital study published in the Journal of the American Medical Association last week concluded universal patient screening did not curtail in-hospital MRSA infections, and found screening was costly because of the need to isolate and treat patients.

But critics of that study said the screening test used was too slow, taking nearly a day to produce results, a gap that might have allowed the contagious bug to spread.

Newer tests can identify carriers in two hours.

Monday's study credited universal screening with preventing 85 MRSA infections, Lautenbach wrote. But he suggested less costly approaches to universal screening, such as testing only at-risk patients and strict adherence to proper hygiene.

A few U.S. states have called for universal patient screening for MRSA, and some hospitals have adopted it. Hospitals face an added financial risk in October when the Medicare and Medicaid health insurance programs plan to halt reimbursements for treating hospital-acquired infections and other "preventable" conditions.

Pain lasts long after traumatic injury

A surprising number of people -- more than 60 percent -- still suffer significant pain a year after a traumatic injury in a car crash or other cause, showing the need for better pain treatment, researchers said.

In a study published on Monday in the journal Archives of Surgery, researchers tracked 3,047 patients ages 18 to 84 from 14 U.S. states who survived an acute traumatic injury.

A year after the injury, 63 percent reported that they still experienced pain related to the injury, with most having pain in more than one region of the body.

On average, the patients assessed their pain at 5.5 on a 10-point scale -- a level at which they would be expected to have moderate to severe interference with daily activities.

"I was surprised that the pain was as common and as severe as they reported it to be," said Dr. Frederick Rivara of the University of Washington in Seattle, who led the study.

"The implications are that we need to do a much better job of identifying pain in these patients, treating it adequately and treating it early," Rivara added in a telephone interview.

The people in the study sustained head injuries, broken limbs, chest or abdominal trauma and other injuries in motor vehicle crashes, falls and other circumstances.

Pain was most commonly seen in joints and limbs (44 percent of patients), the back (26 percent), the head (12 percent) and neck (7 percent).

Rivara noted that people who experience chronic pain are at higher risk for depression and for being unable to work or function normally.

"The focus up until now in a lot of our care is on whether you live or die, which is obviously important. But we can't just stop there. And I think we need to look at what are the things we can do to improve people's lives after serious illness or injury," Rivara added.

The American Pain Foundation, a Baltimore-based advocacy group, said the financial cost exacted by chronic pain in the United States -- including health-care expenses, lost income and lost productivity -- is estimated at $100 billion a year.

The group said back pain is the leading cause of disability in Americans under 45 years old.

"There are hundreds of thousands, if not millions, of people who have had traumatic injury when the focus has been the injury and the destruction of tissue and not the pain. Pain has been a secondary consideration (during treatment)," said Will Rowe, American Pain Foundation chief executive officer.

"In many instances, the injury heals and the pain persists. That's the story that needs to be told," Rowe said.

Better to walk away than punish

Harvard study

Punishing a lazy team member can be counterproductive and it may be better to simply walk away, researchers said on Wednesday.

The researchers at Harvard University found that people who go to the trouble of punishing colleagues, co-workers or others in one-on-one situations do not profit from their revenge.

Such behavior does not pay off for a group, either, they reported in the journal Nature.

"Put simply, winners don't punish," said David Rand, who worked on the study. "Punishment can lead to a downward spiral of retaliation with destructive outcomes for everybody involved."

Rand works in Harvard's Program for Evolutionary Dynamics and Department of Systems Biology, which combines the study of evolution with economics.

His team studied people playing the so-called prisoner's dilemma computer-based game, in which 104 Boston-area students could choose to cooperate, defect or punish.

"Cooperation meant paying one unit for the other person to receive two units," the researchers wrote. So if both players cooperated, each got two units. Defectors could take off with three units, unless the other player defected too, in which case both ended up with only one.

"That makes defection tempting for most people and cooperation generally breaks down at some point in a prisoner's dilemma game," Manfred Milinski and Bettina Rockenbach of the Max-Planck-Institute for Evolutionary Biology in Ploen, Germany wrote in a commentary.

The Harvard game added two dimensions -- punishment and familiarity. The five top-ranked players never used costly punishment, while players who won the least amount had punished the most often.

An equivalent situation might be in the workplace, Rand said.

"Say you have a project that you have to complete with someone else and you feel like someone else is not contributing as much as they should; they are not pulling their weight," Rand said in a telephone interview.

"The thing that is best for you is to stop contributing, to walk away, as opposed to expending a lot of effort insulting them, threatening them or taking aggressive action."

Punishing someone else in a situation where both parties are equal creates an "opportunity cost," Rand said. "The time that you are spending being punitive toward the other person could be spending doing things that are more productive."

But it also does not pay to let the freeloader ride along. "It's not quite turn the other cheek," Rand said. "We are saying you should only do as much as the other person is doing."

He said the findings only apply in one-on-one situations -- not to societies or cultures as a whole, or situations in which one person is more powerful than the other.

Popcorn ingredient causes lung disease

A chemical used to give butter flavor to popcorn can damage the lungs and airways of mice, U.S. government experts reported on Thursday.

Tests on mice show that diacetyl, a component of artificial butter flavoring, can cause a condition known as lymphocytic bronchiolitis, said the team at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.
A popcorn seller stocks up in Barnes, southwest London July 5, 2007. A chemical used to give butter flavor to popcorn can damage the lungs and airways of mice, U.S. government experts reported on Thursday. (REUTERS/James Boardman)

The condition can lead to obliterative bronchiolitis -- or "popcorn lung" -- a rare and debilitating disease seen in workers at microwave popcorn packaging plants and at least one consumer.

At least two microwave popcorn makers -- ConAgra Foods Inc and Weaver Popcorn Co Inc -- have said recently they would stop using diacetyl.

Laboratory mice made to inhale diacetyl vapors for three months developed lymphocytic bronchiolitis, the NIEHS team said.

"This is one of the first studies to evaluate the respiratory toxicity of diacetyl at levels relevant to human health," Daniel Morgan at NIEHS, whose team led the study, said in a statement.

Writing in the journal Toxicological Sciences, the researchers said findings suggest that workplace exposure to diacetyl contributes to the development of obliterative bronchiolitis.

The hard-to-treat condition causes vague symptoms such as cough and shortness of breath, and steadily worsens, according to the U.S. Centers for Disease Control and Prevention.

Congress has been working on a bill to order quick action by the Occupational Safety and Health Administration to limit exposure to diacetyl. The House of Representatives passed a bill last year but the Senate has not acted.

The Food and Drug Administration said last September it was investigating a report of a man who came down with the life-threatening disease after eating several bags of butter-flavored microwave popcorn each day.

DEET works by masking body odor from bugs

The bug repellent DEET works by making mosquitoes and their brethren unable to smell the sweet aroma of human sweat that alerts them that a meal of blood is nearby, scientists said on Thursday.

This knowledge may help guide the creation of new repellents based on the same principle but without possible health worries, they said.

The chemical was first produced by government scientists in 1946 after the jungle warfare of World War II hammered home the need to prevent mosquito and other insect bites. It has been available to the public since 1957.

It is the world's most widely-used topical agent against mosquitoes and other blood-eating insects. It repels mosquitoes which spread malaria, a leading killer in parts of the developing world, as well as ticks which spread Lyme disease. But it does not kill them.

Until now scientists had not grasped exactly how it works.

Mosquitoes are crazy for two human scents: sweaty body odor and the carbon dioxide in breath. They use different receptors in their olfactory system -- the sensing system for smell -- to detect these odors to locate their prey.

"Humans are very smelly, so there's a large number of compounds that attract mosquitoes," Leslie Vosshall, head of Rockefeller University's Laboratory of Neurogenetics and Behavior, said in a telephone interview.

In experiments on mosquitoes and fruit flies, her team determined that DEET serves sort of a chemical cloak, masking certain human odors.

"You become invisible to them," Vosshall said.

The scientists tracked the electrical activity of cells in the mosquito olfactory system while exposing them to DEET. They found that it blocked bugs from smelling body odor but not the carbon dioxide in breath.

Without the scent of body odor, the bugs cannot figure out that a succulent person is nearby, the scientists said.

"Lots of things out in nature will release carbon dioxide -- swamps, for example -- and that's not a good thing to go after if you're a mosquito," said Vosshall, whose findings were published in the journal Science.

The U.S. Environmental Protection Agency said about a third of the U.S. population is expected to use DEET annually. The agency said about 140 products containing DEET are registered with the EPA by about 39 different companies.

A safety review concluded in 1998 that insect repellents containing DEET are not a health threat, but DEET should not be used on children under two months old, the EPA said.

"There are problems with DEET," Vosshall said. "It's oily, it melts plastic, you can't use it on babies, you have to reapply it on every piece of exposed skin frequently. It does actually penetrate your skin and enter your blood stream."

She said there have been rare cases in which people had seizures after putting on too large a dose.

Factors behind head and neck cancer revealed

There are two distinct culprits behind head and neck cancer -- the long-recognized heavy tobacco and alcohol use as well as a common sexually transmitted virus, researchers said on Tuesday.

The risk factors are so dramatically different in head and neck cancer in people infected with the human papillomavirus, or HPV, that it should be considered a separate disease from cases in which patients are not infected, researchers at Johns Hopkins University in Baltimore said.

Head and neck cancer includes tumors in the mouth, tongue, nose, sinuses, throat and lymph nodes in the neck.

"These are completely different cancers and we need to view them as such. They just happen to occur in the same place. The risk factors didn't appear to overlap at all, and there didn't appear to be any interaction between them," Dr. Maura Gillison, a professor of oncology and epidemiology, said in a telephone interview.

More than 35,000 people are diagnosed with head and neck cancer annually in the United States alone. If found early, such cancer may respond well to treatment with surgery, radiation therapy and chemotherapy.

Not only are the patient populations different in HPV-positive and HPV-negative head and neck cancer, but the tumors look different under a microscope, Gillison said. People with the viral-linked cancer also tend to respond better to treatment than those not HPV-infected, she added.

HPV is a common sexually transmitted virus. It is well known for causing cervical cancer and genital warts.

Since 2000, researchers have also known that HPV infection was linked to some cases of head and neck cancer, particularly in the upper throat and back of the tongue.

The new study, published in the Journal of the National Cancer Institute, focused on 240 people diagnosed with head and neck cancer between 2000 and 2006.

Nearly 40 percent of them had an HPV infection. Those patients did not have the well-known risk factors for head and neck cancer -- tobacco smoking, alcohol use and poor oral hygiene, the researchers found.

The people with viral-linked cancer cases had a completely different set of risk factors, including certain sexual behaviors and marijuana use, the researchers found.

Sexual behaviors linked to these patients included increasing numbers of lifetime sex partners including oral sex, and the presence of a sexually transmitted disease, they said.

Gillison said it is possible other behaviors linked with marijuana use could be responsible, but said chemicals in marijuana called cannabinoids could affect the immune system's ability to clear a viral infection.

Limit patient screening for infection, study says

Screening all incoming hospital patients for a dangerous drug-resistant staph infection and isolating those infected did not curtail its spread, and proved costly, Swiss researchers said on Tuesday.

Some hospitals and a few U.S. states have called for the controversial approach of testing every incoming patient for methicillin-resistant Staphylococcus aureus, known as MRSA, which was blamed for an estimated 19,000 U.S. deaths in 2005.

But a 1-1/2-year study at the University of Geneva Hospitals and Medical School, where MRSA has occasionally been a problem, found screening did not reduce the number of patients who caught the infection during their hospital stays.

Roughly 85 percent of MRSA cases, which is treatable only with a few antibiotics, occur in hospitals, where infection can kill weakened patients.

Hospitals undertake several approaches to combat outbreaks such as strict hand-washing by staff, frequent equipment changes, and extensive cleaning of operating rooms. MRSA outbreaks struck roughly one-quarter of U.S. hospitals in 2003.

As many as 1.5 percent of Americans carry the highly contagious infection and may spread it to others without developing a serious infection themselves.

In the study published in the Journal of the American Medical Association, 515 of the 21,754 surgical patients tested positive for MRSA. Of those, 337 might not have been caught because they had not been previously identified as MRSA carriers.

Infected patients received five days of treatment and special precautions such as isolated hospital rooms that strained hospital resources and raised costs considerably.

During the initial nine-month period when the screening was done in selected hospital wards, 93 patients contracted MRSA infections while in the hospital. That compared to 76 infected in the wards where standard prevention efforts were in place.

"Overall, our real-life trial did not show an added benefit for widespread rapid screening on admission compared with standard MRSA control alone in preventing (hospital) MRSA infections in a large surgical department," study leader Dr. Stephan Harbarth wrote.

The report recommended targeting the screening to patients undergoing elective surgery with a high risk of MRSA infection.

Two U.S. researchers agreed in an accompanying commentary that a multifaceted approach, and not universal patient screening, was likely to be more effective in combating MRSA and other types of hospital germs that infect a total of 1.7 million Americans and kill 100,000 each year.

Being overweight can damage your career

Being overweight or obese is not only bad for your health but can also be bad for your career, according to a U.S. study.

As obesity rates in the United States rise, researchers at Detroit's Wayne State University looked at over 25 years of research on weight-based bias in the workplace to see whether being overweight hindered the chance of getting a job or moving up the work ladder.

After examining the results of 25 separate studies, they concluded that obesity does have a denigrating effect in the workplace, with the weight-based bias stronger for sales positions than for managerial positions.

"There are a whole set of stereotypes that go along with being overweight, and a lot of them transfer into the workplace in terms of people's judgment about others' abilities and appearance in relation to job performance," researcher Cort Rudolph said in a statement.

The researchers found the results of all the studies examined were consistent in finding that people who are overweight are viewed more negatively in the workplace than those who are of average weight.

The bias was felt most when overweight people applied for a job and went through the initial selection process with body weight found to be less of a factor at the performance evaluation stage, and with stereotypes having a minimum influence when it comes to promotions.

Rudolph said this was not surprising based on what was known about weight-based stereotypes.

"Some of the basic stereotypes associated with being overweight include laziness, sloppiness, untidiness and lack of self-discipline and control," he said.

"Overweight people are also regularly labeled as having increased health problems, which is an issue often considered cumbersome by organizations."

But Rudolph, who will present the study's findings at a conference of the Society for Industrial and Organizational Psychology in San Francisco in April, said there was good news for overweight employees.

"The bias effect tends to decrease as people's tenure with an organization increases," he said.

Rudolph said this was an issue that could become more a problem as Americans became heavier.

"Considering this growth, stigmas associated with body weight can become more and more of an issue," he said.

Gene studies confirm "out of Africa" theories

Two big genetic studies confirm theories that modern humans evolved in Africa and then migrated through Europe and Asia to reach the Pacific and Americas.

The two studies also show that Africans have the most diverse DNA, and the fewest potentially harmful genetic mutations.

One of the studies shows European-Americans have more small mutations, while the others show Native Americans, Polynesians and others who populated Australia and Oceania have more big genetic changes.

The studies, published in the journal Nature on Wednesday, paint a picture of a population of humans migrating off the African continent, and then shrinking at some point because of unknown adversity.

Later populations grew and spread from this smaller genetic pool of founder ancestors -- a phenomenon known as a bottleneck.

Populations that remained in Africa kept their genetic diversity -- something seen in many other studies.

"The one thing that I think we cannot say from this study is that any one person's genome is any healthier or evolutionarily fit than another person's genome," said Carlos Bustamante of Cornell University in New York, who worked on one study.

"You have to think of this at the population level," Bustamante said in a telephone interview.

Bustamante's team has been looking at the DNA sequences of 15 African-Americans and 20 European-Americans, examining tiny one-letter changes in the DNA code called single-nucleotide polymorphisms or SNPs (pronounced "snips").

FIT OR EXTINCT

They tested these changes to qualify them as benign, or potentially affecting genes, amino acids and eventually proteins in a way that could damage health or make people less "fit" -- in evolutionary terms, less likely to survive and reproduce.

"Like every other study ... the African-American panel as a whole showed more variation than the European-American panel," Bustamante said.

Then his team did a computer simulation of a bottleneck, and found it predicted this pattern.

Bustamante said it is possible some of the SNPs are beneficial, and he said his team and others should compare the genetic changes they found to known genetic changes linked with diseases.

"I wish we had done that (already)," he admitted.

In the other study, Noah Rosenberg and colleagues at the University of Michigan and the National Institute on Aging analyzed DNA from 485 people around the world.

They looked for three types of genetic variation, including SNPs and larger changes that involve duplications, deletions and repetitions of large segments of DNA.

The patterns they found produced what they call the highest-resolution map yet of human genetic variation.

They also reinforce the idea that humans originated in Africa, then spread into the Middle East, followed by Europe and Asia, the Pacific Islands and finally to the Americas.

"Diversity has been eroded through the migration process," Rosenberg said in a statement.

People of African descent are the most genetically diverse, followed by people from the Middle East, and then Asians and Europeans. Native Americans resemble one another the most on a DNA level.

The study also found it is sometimes possible to trace a person's ancestry to a small group within a geographic region.

Memory loss declining among U.S. seniors

Older Americans are having less trouble with their memories, and it may be because they spent more time in school, U.S. researchers said on Wednesday.

They found the rate of cognitive impairment -- which includes a range of ills from significant memory loss to Alzheimer's disease -- fell 3.5 percentage points among people 70 and over between 1993 and 2002.

"We found a clear relationship. The more education people had, the better they performed on cognitive tests," said Dr. Ken Langa of the University of Michigan, whose study appears in the journal Alzheimer's & Dementia.

Langa said the research reinforces other studies that suggest people who do mentally challenging tasks early on build up a reserve of brain power that helps them withstand later injuries to the brain, such as a mini-stroke.

"Your brain is wired up differently. You can sustain more insults over your lifetime," Langa said in a telephone interview.

To test this, Langa and colleagues looked to see if there was a relationship between education and mental agility in older Americans.

They used data on 11,000 people from the Health and Retirement Study, a national survey of U.S. adults. The researchers compared data gathered in 1993 with data from 2002.

They found that in in 2002, 8.7 percent of those aged 70 or older had cognitive impairment, down from 12.2 percent in 1993. "We think education is part of the story here," Langa said.

In 1993, people who were 70 or older on average had 11 years of education. By 2002, those 70 and older had 12 years of education. "That is a relatively significant increase in the level of education," he said.

They also found that older adults with more education who did develop cognitive problems were more likely to die within two years.

Langa said the thinking is that people who have more education have developed different brain circuits that have allowed them to continue functioning at a high level.

"Once you put it off as long as you can, you are more likely to have a quicker decline and death," he said.

Langa said the results may also reflect better cardiovascular health, which can reduce strokes or other injuries that affect brain function. He said rising rates of obesity and diabetes could offset those gains.

"Cardiovascular risks have a close link to brain health," he said.

Langa said people should exercise their bodies to protect their cardiovascular health, and exercise their brains with puzzles and books.

Stem cells help rats recover function after stroke

Transplanting brain cells produced from human embryonic stem cells helped fix stroke damage in the brains of rats, according to scientists who hope to test the same thing in people whithin about five years.

Researchers have been looking for ways to repair the brain damage from a stroke, which can cause permanent disability. In a study published on Tuesday, researchers at Stanford University School of Medicine in California reported that treatment involving human embryonic stem cells may be a solution.

Embryonic stem cells are the master cells that give rise to every cell and tissue in the body.

The Stanford team reported they restored lost limb function in rats that had stroke-related brain damage. They induced human embryonic stem cells to develop into neural stem cells that, once transplanted in the rats, developed into neurons and two other important types of brain cells.

The researchers hope to use this approach within about five years in studies involving people who have had strokes.

"We have a lot of evidence that we'll be able to use this kind of stem cell regenerative therapy in patients, including stroke patients," Stanford's Dr. Gary Steinberg, who helped lead the study, said in a telephone interview.

Writing in the Public Library of Science journal PLoS ONE, Steinberg's team described how they caused strokes in 10 rats and then transplanted neural stem cells into their brains.

The cells made their way to the damaged brain region and incorporated themselves into surrounding brain tissue.

The cells never grew uncontrollably into tumors in lab dishes or inside the rats, the scientists said. The transplanted cells helped repair the stroke damage and enabled the rats to recover lost function in front legs weakened as a result of the stroke, they added.

"It was not quite back to normal but, at least in the rat, it looks like it's going to be close to normal -- very impressive," Steinberg said.

"Now remember, this is a rat, not a human. We still have to make that step. But if we could achieve that kind of recovery in humans, we would have a great therapy," Steinberg added.

In a stroke, the blood supply to any part of the brain is blocked. This can occur when a blood vessel bringing blood to the brain is blocked by a blood clot, or when a blood vessel bursts, causing blood to leak into the brain.

If blood flow is halted for more than a few seconds, the brain is deprived of blood and oxygen, brain cells die and permanent damage can result.

Some people oppose the use of human embryonic stem cells on ethical grounds because creating the reservoirs of these cells for use in research involves the destruction of human embryos.

Music matters for stroke patients, study finds

A little Beethoven is good for the brain, according to a Finnish study published on Wednesday showing that music helps people recover more quickly from strokes.

And patients who listened to a few hours of music each day soon after a stroke also improved their verbal memory and were in a better mood compared to patients who did not listen to music or used audio books, the researchers said.

Music therapy has long been used in a range of treatments but the study published in the journal Brain is the first to show the effect in people, they added.

"These findings demonstrate for the first time that music listening during the early post-stroke stage can enhance cognitive recovery and prevent negative mood," the researchers wrote.

Strokes, which occur when blood flow to the brain is blocked, can kill brain tissue and are one of the worldwide leading causes of death and permanent disability. Treatments include blood thinning drugs and attempts to lower cholesterol.

The study involved 60 people who recently had a stroke of the middle cerebral artery in the left or right side of the brain. This is the most common stroke and can affect motor control, speech and a range of other cognitive functions.

One group listened to their favourite music every day or used audio books while another did not listen to any music. All volunteers received standard rehabilitation treatment.

Three months after stroke music listeners showed a 60 percent better improvement in verbal memory compared to an 18 percent benefit for those using audio books and 29 percent for people who did not listen to either.

The ability to focus attention also improved by 17 percent in music listeners, said Teppo Sarkamo, a psychologist at the Cognitive Brain Research Unit at the University of Helsinki, who led the study.

"We can't say what is happening in the brain but based on previous research and theory it may be music listening could actually activate the brain areas that are recovering," he said in a telephone interview.

Music might also in some way activate more general mechanisms that repair and renew the brain's neural networks after stroke, Sarkamo said.

Larger studies are needed to better understand exactly what is going on but these findings show that music may offer a cheap, easy additional treatment for stroke patients, he said.

"This could be considered a pilot study," Sarkamo said. "It is a promising start.

Cardiac arrest: avoid nights, weekend

People who have a cardiac arrest in the hospital at night or on the weekend are far less likely to survive than those who suffer one during the day, U.S. researchers said on Tuesday.

Studies suggest this may be at least partly because of inadequate staffing at off-peak hours.

The researchers found only 14.7 percent of people whose hearts stop pumping during the night survive, compared with nearly 20 percent of people during the day.

Those who had a cardiac arrest at around 3 p.m. had the survival rate, Dr. Mary Ann Peberdy of Virginia Commonwealth University in Richmond and colleagues reported in the Journal of the American Medical Association.

The only part of the hospital with difference in survival day or night was the emergency department. "That survival difference by time of day was there regardless of where we looked, except in the emergency department," Peberdy said.

She said emergency departments are the one place in hospitals constantly staffed by senior-level physicians.

Cardiac arrest occurs when the heart stops circulating blood. Without cardiopulmonary resuscitation or CPR and often a shock from a defibrillator, patients can die within minutes.

"Doing the right thing and doing it quickly is very important," Peberdy said.

She said studies at individual hospitals suggested staffing played a role in whether a patient survived a cardiac arrest.

Other studies have shown that doctors make more mistakes at night, hospitals have fewer nurses per patient working at night and that fewer experienced supervisors work the night shift.

TIME TRUMPS OTHER FACTORS

Peberdy wanted to see how this affected survival of cardiac arrest. Her team scoured the National Registry of Cardiopulmonary Resuscitation, which included survival data for more than 86,000 adults who had heart attacks in more than 500 U.S. hospitals between January 2000 and February 2007.

They split up the data by time of day, with the day/evening defined as 7 a.m.-10:59 p.m., night as 11 p.m.-6.59 a.m. and weekends starting at 11 p.m. Friday and running through 6.59 a.m. Monday.

"We factored in how sick people were, what their initial rhythms were. None of that overshadowed the time of day," Peberdy said in a telephone interview.

"Weekend nights were pretty much the same as week nights. Weekend days were kind of in between week days and nights," she said.

She said the difference by time of day held regardless of whether a patient was in a bed with a heart monitor or even in the intensive care unit.

"I think the study confirms what some of us have suspected for a while: That how we staff the hospital determines how well patients do," said Dr. Graham Nichol who helps oversee the NRCPR registry for the American Heart Association.

Peberdy said the study suggests hospitals need to focus on improving their resuscitation systems in off-hours

Migrating people had 20,000-year campout

People who migrated from Asia to the New World camped out for 20,000 years on land now submerged under the Bering Strait between Alaska and Siberia, according to a genetic analysis published on Tuesday.

A team at the University of Florida combined studies of DNA, archeological evidence, climate data and geological data to come up with their new theory, which describes a much longer migration than most other researchers have proposed.

"We sort of went out onto a limb, incorporating all this nongenetic data," molecular anthropologist Connie Mulligan said in a telephone interview.

Mulligan's team proposes that the people who left Central Asia to eventually populate the Americas passed quickly through Siberia, and then got stuck in Beringia -- a former land mass that now lies under the frigid Bering Sea.

There they stayed for 20,000 years, until glaciers melted about 15,000 years ago, opening a route to the Americas.

"The reason there is no archeological evidence for that occupation is that the area is under water," Mulligan said.

The researchers used sequences of mitochondrial DNA taken from Asians and Native Americans for their analysis. This type of DNA is passed along virtually unchanged from mother to child.

The small mutations that occur can be used as a genetic clock to track the descent and the sizes of ancient populations.

"After a long period of little change in population size in greater Beringia, Amerinds (American Indians or native Americans) rapidly expanded into the Americas less than 15,000 years ago either through an interior ice-free corridor or along the coast," they wrote in their report.

"This rapid colonization of the New World was achieved by a founder group with an effective population size of 1,000 to 5,400 individuals."

WAITING AND MUTATING

The University of Florida's Michael Miyamoto said the DNA suggests a 20,000-year "waiting period" during which generations passed and genetic changes accumulated.

"By looking at the kinds and frequencies of these mutations in modern populations, we can get an idea of when the mutations arose and how many people were around to carry them," he said.

Other theories have suggested one single expansion of people from the Old World to the New around 15,000 years ago.

"If you think about it, these people didn't know they were going to a new world. They were moving out of Asia and finally reached a landmass that was exposed because of lower sea levels during the last glacial maximum, but two major glaciers blocked their progress into the New World," Mulligan said in a statement.

"So they basically stayed put for about 20,000 years. It wasn't paradise, but they survived. When the North American ice sheets started to melt and a passage into the New World opened, we think they left Beringia to go to a better place."

Anthropologist and genetics expert Henry Harpending of the University of Utah, who did not work on the study, said it made sense.

"The idea that people were stuck in Beringia for a long time is obvious in retrospect, but it has never been promulgated," he said. "It's very plausible that a bunch of them were stuck there for thousands of years."

Whites to become minority in U.S. by 2050: report

Non-Hispanic whites will become a minority in the United States by 2050, with immigrants and their children driving 82 percent of U.S. population growth in coming years, a new study said on Monday.

The U.S. population will grow to 438 million in 2050 from 296 million in 2005 if current population trends continue, the Pew Research Center study found.

Non-Hispanic whites would account for 47 percent of the total in 2050, it concluded.

By that time, one in every five Americans will be a foreign-born immigrant, compared to one in eight in 2005.

"Of the 117 million people added to the population in this period due to the effect of new immigration, 67 million will be the immigrants themselves and 50 million will be their U.S.-born children or grandchildren," the study said.

While the white population, with its lower fertility rate, ages, the Latino population, the nation's largest minority, will triple in size. Latinos will be responsible for 60 percent of the population growth until 2050.

They will account for 29 percent of the population, or 128 million in 2050, up from 14 percent now, the study said.

"The number of whites will increase, but only by 4 percent," said D'Vera Cohn, one of the report's authors.

The Asian population will almost double in percentage terms, from 5 to 9 percent, while blacks will remain around 13 percent of the total, the report said.

At the same time, the elderly population will more than double as the baby boom generation retires. The number of children and working-age people will grow more slowly.

Almost half of the new immigrants arriving the country will be from Latin American countries, said the other author of the study, Jeffrey S. Passel from the Pew Hispanic Center.

Healthy elderly lifestyle key to longer life

You're never too old to reap the benefits of a healthful lifestyle, according to researchers who found that doing things like exercising and not smoking at age 70 greatly raises one's chances of living to age 90.

The researchers focused on what people can do in their early elderly years to live longer while maintaining good health and physical function -- a vital issue as the population ages in the United States and many other countries.

For 25 years, they tracked about 2,400 male doctors whose average age was 72 when they entered the study in the early 1980s.

Those who exercised two to four times per week, did not smoke, maintained normal body weight and blood pressure, and avoided diabetes had a 54 percent chance of living to 90.

Doing any one or combination of them also were beneficial. But men who did none of them had only a 4 percent chance of reaching age 90, the researchers reported on Monday in the Archives of Internal Medicine.

"This isn't surprising so much as it's reassuring," said Dr. Laurel Yates of Brigham and Women's Hospital and Harvard Medical School in Boston, who led the study.

"All of these factors are considered common sense -- good medical management -- in terms of emphasizing: don't smoke, let's do blood pressure control and weight management, and do exercise," Yates said in a telephone interview.

'DON'T SMOKE, DO EXERCISE'

Yates said the lifestyle message commonly has been aimed at middle-aged people, so it is helpful to see that such lifestyle factors can also help the elderly add healthy years.

"Lifestyle changes are the hardest ones to make. It's a lot easier to take a pill. So the onus is on an individual," Yates said. "If you're going to ask what's the one thing that I could do, I would say do two things: don't smoke and do exercise."

The researchers also found that the men who lived to at least 90 enjoyed better physical function and mental well-being late in their lives than men who died at a younger age.

Yates said research has shown that genetics counts for only about 25 to 30 percent in determining how long people live, with other factors playing a bigger role.

"Most people would say they don't want to have extra years added to their life if those years are going to be ones of disability and disease. And I think it is reassuring that there is something a person can do to help increase the probability of having extra years that are good ones," Yates said.

Another study in the same journal, led by Dr. Dellara Terry of Boston University School of Medicine and Boston Medical Center, looked at 523 women and 216 men age 97 or older.

Terry's team found that about a third of these people got to this advanced age despite having developed age-associated disease before age 85 such as chronic obstructive pulmonary disease, dementia, diabetes, heart disease, high blood pressure, osteoporosis, Parkinson's disease or stroke.

Other recent research has quantified how certain behaviors affect longevity. British researchers who tracked 20,000 people said last month those who exercised, avoided smoking, drank moderately and ate lots of fruit and vegetables lived 14 years longer on average than people who did none of these things.

Autopsies forecast surge in U.S. heart disease

Autopsies of adults who died young of unnatural causes show many already had clogged arteries, U.S. and Canadian researchers said on Monday in a study that suggests heart disease may be on the upswing.

The researchers said their findings suggest a four-decade-long trend of declines in heart disease may be about to come to a screeching halt.

They studied autopsy reports from younger people in one Minnesota county who died from accidents, suicide and murder and found most had clogged arteries and more than 8 percent had significant disease.

"What they observed was a bit shocking," said S. Jay Olshansky of the University of Illinois at Chicago, who wrote an editorial on the research, published in the Archives of Internal Medicine.

"It is the most definitive evidence I've seen suggesting that today's younger and middle-aged generations may be heading for an increase in their risks of heart disease," he said.

The researchers from the Mayo Clinic in Minnesota and the University of British Columbia in Vancouver looked at autopsy data from residents of Olmsted County, Minnesota, who died between 1981 and 2004 from unnatural causes.

During that time, 8.2 percent of 425 people aged 16 to 64 had high-grade disease and 83 percent had the beginnings of coronary artery disease.

Mayo's Cynthia Leibson and colleagues found declines in the grade of coronary artery disease ended after 1995 and began to climb after 2000.

"Declines in coronary artery disease appear to have ended and there is some suggestion that they might be increasing," Leibson said in a telephone interview.

She said it is not yet clear to what extent obesity and diabetes contributed to this, but the researchers plan to study this in the same group of patients.

'PERFECT STORM'

Olshansky, in a telephone interview, said rates of heart disease in the United States climbed steadily in the 20th century until the 1960s, and then began falling, helped by changes in lifestyle and declines in smoking. But then, a confluence of changes occurred.

"It was more or less a perfect storm," he said, citing the introduction of computers and a more sedentary lifestyle, the growth of fast-food chains and larger portion sizes, reduced physical education in schools and increased consumption of high-fructose corn syrup.

"It led to this explosion of obesity," Olshansky said.

A second study in the same journal confirms the trends.

Dr. Philip Mellen of the Hattiesburg Clinic in Mississippi analyzed national diet and nutrition data from a large federal study to see if patients with high blood pressure were adhering to a diet known to help control high blood pressure, a known cause of heart attacks and strokes.

They looked at data collected from 1988-1994, a period before a study in 1997 showed a diet high in fruits, vegetables and low-fat dairy products could significantly lower blood pressure. They compared this to data from 1999 to 2004.

What they found was people with hypertension were eating worse, not better. "The dietary quality has deteriorated over the last 15 years," Mellen said in a telephone interview.

"In our study, the youngest age group was the age group with the worse disease," he said. "This age group will have major problems as they continue to age."

FACTBOX - Key facts about the U.S. State of the Union

When U.S. President George W. Bush gives his State of the Union speech on Monday, he will continue a constitutionally mandated tradition begun over 200 years ago by George Washington.

Following are some key facts about presidential State of the Union messages:

ORIGINS:

* State of the Union messages to Congress by the president are required by Article II, Section 3 of the U.S. Constitution which says, "He shall from time to time give to the Congress information of the state of the union, and recommend to their consideration such measures as he shall judge necessary and expedient."

* The State of the Union has become an annual speech given before a joint session of Congress in the House of Representatives chamber at the U.S. Capitol.

* George Washington gave the first State of the Union speech on Jan. 8, 1790 in New York City, then the provisional U.S. capital.

* Starting with Thomas Jefferson's first State of the Union in 1801 until William Howard Taft's last message in 1912, the State of the Union was a written report sent to Congress. Woodrow Wilson resumed the tradition of giving the State of the Union message in a speech to Congress.

* The phrase "State of the Union" did not become widely used until after 1935, when Franklin Roosevelt started using the term.

* SOME QUOTES:

- "We look forward to a world founded upon four essential human freedoms. The first is freedom of speech and expression -- everywhere in the world. The second is freedom of every person to worship God in his own way -- everywhere in the world. The third is freedom from want -- which, translated into world terms, means economic understandings which will secure to every nation a healthy peacetime life for its inhabitants -- everywhere in the world. The fourth is freedom from fear." -- Franklin Roosevelt, Jan. 6, 1941.

- "As you know, I have provided to the special prosecutor voluntarily a great deal of material. I believe that I have provided all the material that he needs to conclude his investigations ... I believe the time has come to bring that investigation and the other investigations of this matter to an end. One year of Watergate is enough." -- Richard Nixon, Jan. 30, 1974.

- "Yes, we will have our differences. But let us always remember -- what unites us far outweighs whatever divides us. Those who sent us here to serve them -- the millions of Americans watching and listening tonight -- expect this of us. Let's prove to them and to ourselves that democracy works even in an election year." -- Ronald Reagan, Jan. 25, 1988.

- "Some time in the next 10 to 20 years, the major security threat this country will face will come from the enemies of the nation state: the narco-traffickers and the terrorists and the organized criminals, who will be organized together, working together, with increasing access to ever-more sophisticated chemical and biological weapons." -- Bill Clinton, Jan. 27, 2000.

- "States like these, (Iran, Iraq and North Korea) and their terrorist allies, constitute an axis of evil, arming to threaten the peace of the world. By seeking weapons of mass destruction, these regimes pose a grave and growing danger. They could provide these arms to terrorists, giving them the means to match their hatred. They could attack our allies or attempt to blackmail the United States. In any of these cases, the price of indifference would be catastrophic." -- George W. Bush, Jan 29, 2002