NEW YORK (Reuters Health) - Exposure to air pollution later in pregnancy may raise a woman's risk of delivering her baby too soon, a new study suggests.

The findings, reported in the journal Epidemiology, do not prove that air pollution, per se, triggers preterm labor in some women. But they do provide "limited support" for that theory, the researchers say.

Some previous studies have linked air pollution exposure in both the first and third trimester of pregnancy to an increased risk of preterm delivery.

In the current study, researchers looked at the relationship between air pollution levels and the risk of preterm delivery among more than 476,000 women who gave birth in the Atlanta metropolitan area between 1994 and 2004.

The researchers tracked daily pollution levels using data from various air-quality monitors in five counties.

They found that while there were no clear connections between preterm birth and most of the air pollutants they studied, three particular air pollutants were related to a higher risk.

Specifically, the daily rate of preterm births inched upward when levels of fine particulate matter were elevated over the previous week. The increase was seen among women who lived within 4 miles of an air-quality monitoring site.

Car exhaust is the prime source of fine particulate matter, but it is also produced by power plants and certain other industrial sources. The particles are small enough to be inhaled deeply into the lungs.

The strongest evidence was for a role of nitrogen dioxide (NO2), a marker of motor vehicle exhaust, noted lead researcher Dr. Lyndsey A. Darrow, of Emory University in Atlanta.

NO2 was linked to an increase in the daily preterm-birth rate when levels were elevated in the previous six weeks.

In theory, Darrow told Reuters Health in an email, exposure to air pollution later in pregnancy could activate an inflammatory response in the body that, in turn, might trigger early labor. She noted that there is increasing evidence that inflammation is involved in preterm birth.

Still, the role of air pollution in premature birth remains unclear.

"The scientific evidence is mixed as to whether or not urban air pollution has an effect on fetal development," Darrow said.

She suggested that pregnant women who want to "err on the side of caution" try to avoid air pollution sources like high-traffic areas.

SOURCE: Epidemiology, September 2009.

Copyright © 2009 Reuters Limited.

NEW YORK (Reuters Health) - Female athletes are at greater risk of a potentially serious knee ligament injury than their male counterparts -- but a fairly simple training regimen might help reduce those odds, a small study suggests.

The injury in question affects the knee's anterior cruciate ligament, or ACL. ACL tears are common in certain sports and are a particular threat to female athletes -- who have four to six times the risk of their male counterparts in the same sport.

In the new study, Korean researchers found that among 22 high school basketball players they followed, girls who followed the training regimen for eight weeks showed changes in jumping ability that could lower their odds of tearing the ACL.

The researchers, led by Dr. Bee-Oh Lim of Seoul National University, report the findings in the American Journal of Sports Medicine.

The ACL is a tough band of tissue that runs from the thigh bone to shin bone and plays an important part in stabilizing the knee joint. When it tears, it's often the result of a sudden, forceful twist -- such as an awkward landing from a jump that torques the knee.

Athletes in sports that require quick pivots and jumps -- including basketball, soccer and volleyball -- have the highest rates of ACL injury.

Experts are not certain why female athletes are more vulnerable, but the general consensus is that differences in biomechanics may play a role.

Compared with males, for instance, female athletes tend to have a greater imbalance in the quadricep and hamstring muscles at the front and back of the thigh, respectively. Females typically have more strength in the quadriceps and greater flexibility in the hamstrings.

Research also suggests that females tend to bend their knees less deeply and have a less stable joint alignment when landing from jumps.

For the current study, Lim's team tested a training program designed to address these differences.

The researchers randomly assigned 22 female high school basketball players to one of two groups: one that added the training to their regular team practice and one that did not.

Girls in the former group spent the first 20 minutes of their practice time performing exercises designed to improve their jumping ability and strengthen and stretch the various muscles of the legs and hips.

After eight weeks, the researchers found, girls in the training group were showing better form on a standard jumping test. They also had a more balanced activation of their quadriceps and hamstrings while jumping -- measured via electrodes placed on the muscles.

The researchers did not study whether all of this translates into a lower rate of ACL tears. However, other studies have shown that similar training regimens may cut the risk.

Still unclear is how long athletes have to train to lower their risk of ACL injury, Lim's team notes. Girls in this study trained for eight weeks, but some research suggests that six weeks may be enough.

SOURCE: American Journal of Sports Medicine, September 2009.

Copyright © 2009 Reuters Limited.

NEW YORK (Reuters Health) - Low levels of vitamin D appear to increase the risk of death in older adults, researchers report in the Journal of the American Geriatrics Society.

Skin produces vitamin D when directly exposed to the sun. But older people, particularly those living in northern regions, rarely obtain sufficient sun exposure for adequate vitamin D production and need supplements to achieve healthy vitamin D levels.

Increasingly, evidence points to health risks from inadequate vitamin D.

In the current study, Dr. Adit A. Ginde, at the University of Colorado Denver, in Aurora, and colleagues assessed the risk for death, according to vitamin D levels, in 3,408 men and women who were 73 years old on average when they participated in the Third National Health and Nutrition Examination Survey, or NHANES III.

During more than 7 years of follow-up, 1,493 people died -- nearly 44 percent. A little more than half of the deaths were due to heart disease.

After taking into account a variety of factors that could influence the results, low vitamin D was independently associated with an increased risk of death from any cause, but particularly from heart disease, the researchers found.

Optimal vitamin D levels are considered to be somewhere between 80 and 110 or 120 nmol/L (nanomoles per liter) of blood, although there are no set guidelines. On average, people in the current study had vitamin D levels of 66.0 nmol/L of blood.

Ginde's team found that, the risk of death from any cause was 83 percent higher among people with vitamin D levels less than 25 nmol/L, compared with people with vitamin D levels of 100 nmol/L or higher.

The risk of death was 47 percent higher among those with vitamin D levels between 25 and 49.9 nmol/L, relative to those with vitamin D levels of 100 or higher.

Low vitamin D levels, were particularly hard on the heart, the researchers note, with the risk of death due to heart disease more than twofold higher in people with vitamin D levels less than 25 nmol/L.

Current vitamin D recommendations for people 65 years and older appear inadequate, Ginde and colleagues note in their report, and they suggest large scale research to determine the effects of higher-dose vitamin D supplementation.

SOURCE: Journal of the American Geriatrics Society, September 2009

Copyright © 2009 Reuters Limited.

WASHINGTON (Reuters) - An experimental AIDS vaccine made from two older versions has made major progress in finding an effective way to combat the illness, researchers said on Thursday.

But its application may be limited and a commercial vaccine may require more time.

The health minister of Thailand, where the trials were conducted, called the outcome a "very important step for developing an AIDS vaccine." Two U.N. agencies said they gave "new hope" in battling the disease but more work was needed.

At least one researcher suggested the vaccine might not be effective in areas and in instances where AIDS is most prevalent.

The vaccine is a combination of Sanofi-Pasteur's ALVAC canary pox vaccine and the failed HIV vaccine AIDSVAX, made by a San Francisco company called VaxGen and now owned by the nonprofit Global Solutions for Infectious Diseases.

The trial was sponsored by the U.S. army and conducted by the Thai Ministry of Public Health. Officials from the two countries told a news conference in Bangkok the risk of infection had been cut by 31.2 percent among 16,402 volunteers.

"The result of the study is a very important step for developing an AIDS vaccine," Thai health minister Withaya Kaewparadai said. "It's the first time in the world that we have found a vaccine that can prevent HIV infection."

The result puzzled researchers, who said they could not understand why the vaccine combination was working.

TRIAL SUPPORTERS JUBILANT

But it was a triumph for supporters, who went ahead with the giant trial despite criticism it was unethical or a waste of money because the vaccine was widely expected to have no effect.

"Myself, like others, did not think there was a very high chance that this would give any degree of efficacy," said Dr. Anthony Fauci of the U.S. National Institute of Allergy and Infectious Diseases, which helped pay for the study.

"But nonetheless, we went ahead with the trial and it was controversial to go ahead with it."

In Geneva, the World Health Organization and the Joint United Nationals Programme on HIV/AIDS said: "The study results, representing a significant scientific advance, are the first demonstration that a vaccine can prevent HIV infection in a general adult population and are of great importance."

The two agencies, in a joint statement, described the efficacy as "modestly productive."

"We see no commercial vaccine available for some time yet, but the prospect has finally been raised (after 30 years of trying) that an effective vaccine is possible," said Michael Leacock, an analyst at ABN AMRO research.

More extensive work was needed, he said, before a vaccine could be suitable for regulatory approval.

RESULTS REMAIN INCONCLUSIVE

Muddying the waters of the trial result, people who got the vaccine and who became infected anyway had just as much virus in their blood and just as much damage to their immune systems as HIV patients who went unvaccinated.

That meant the vaccine helped prevent infection but did nothing to affect the virus once it is in the body.

"We had 74 infections in the placebo group and 51 in the vaccine group," Dr. Jerome Kim, a U.S. Army colonel at the Walter Reed Army Institute of Research in Maryland, who helped lead the trial, said by telephone.

"Although the level of protection that we saw was clearly modest, the study is a major scientific advance," Kim said.

"It is the first evidence that the development of a safe and effective vaccine is possible. Although we don't have all the answers now, it does have important implications for the future of HIV vaccine design."

Kim said the vaccine might not work in the people and places where HIV is most common -- in Africa, among men who have sex with men and among injecting drug users.

"The vaccine was tested in Thailand and it is really specific for the strains that are circulating in Thailand now," Kim said.

Both Fauci and Kim noted that the vaccine was formulated specifically to work against two subtypes of the human immunodeficiency virus -- E, which circulates in Thailand and Southeast Asia, and B, common in the United States and Europe.

In a statement, Sanofi-Aventis Chief Executive Chris Viehbacher said that the company would continue its research into HIV in partnership with academics, governments, non-governmental organizations and other vaccine makers.

The volunteers in the trial got six immunizations over six months, four with ALVAC and two with AIDSVAX.

ALVAC is a genetically engineered canarypox virus that has spliced into it synthetic versions of three HIV genes. AIDSVAX is made using two versions of one HIV gene, one from the B subtype and one from the E subtype.

The AIDS virus infects an estimated 33 million people globally and has killed 25 million since it was identified in the 1980s. It affects immune cells called T-cells.

Cocktails of drugs can control the virus but there is no cure. In 2007, Merck & Co ended a trial of its vaccine after it was found not to work, and in 2003, AIDSVAX used alone was found to offer no protection, either.

Copyright © 2009 Reuters Limited.

NEW YORK (Reuters Health) - If you feel as though you drool too much, studies suggest you should seriously consider surgery to take care of it, say researchers.

Drooling is tough to treat, point out authors of a paper from Walter Reed Army Medical Center in Washington, DC. That's because some of it is due to physical problems, and some is due to faulty wiring in the brain.

However, among those patients who have surgery, most feel that they have a positive result, according to the new examination of more than 50 previously published studies.

There are a number of such operations, such as removing saliva-producing glands and re-routing ducts that carry saliva. The researchers found that for any given procedure, more than half of patients reported seeing an improvement.

Still, "To date, there is no one procedure that is regarded as the most effective," note Dr. Scott E. Brietzke and colleagues in their paper in the journal Archives of Otolaryngology, Head and Neck Surgery.

"Surgical therapy for problematic drooling can be very successful and should be considered for patients with long-term drooling problems," Dr. Brietzke said. "Although less invasive procedures may still be considered initially, pre-operative counseling should include discussion that success rates may be lower with these types of procedures."

SOURCE: Archives of Otolaryngology, Head and Neck Surgery, September 2009.

Copyright © 2009 Reuters Limited.