WEDNESDAY, Aug. 5 (HealthDay News) -- U.S. scientists have decoded the structure of an entire HIV genome, a breakthrough which could improve understanding of how the virus infects humans and could lead to the development of new antiviral drugs.

Like viruses that cause influenza, hepatitis C and polio, HIV carries its genetic information as single-stranded RNA rather than double-stranded DNA. Information encoded in RNA is more complex.

The HIV RNA genome is huge, composed of two strands of almost 10,000 nucleotides each. Previously, scientists had managed to model only small regions of the HIV RNA genome.

In this study, University of North Carolina at Chapel Hill researchers used specially developed technology to analyze the architecture of HIV genomes. They found that the RNA structures influence multiple steps in HIV's infection cycle.

"There is so much structure in the HIV RNA genome that it almost certainly plays a previously unappreciated role in the expression of the genetic code," study leader Kevin Weeks, a professor of chemistry, said in a news release.

He and his colleagues said the findings would help unlock additional roles of RNA genomes that are important to the life cycle of HIV and other viruses.

"One approach is to change the RNA sequence and see if the virus notices," co-author Ron Swanstrom, a professor of microbiology and immunology, said in the release. "If it doesn't grow as well when you disrupt the virus with mutations, then you know you've mutated or affected something that was important to the virus."

The study appears in the Aug. 6 issue of the journal Nature.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about HIV/AIDS.

MONDAY, Aug. 3 (HealthDay News) -- Labor should be induced after 37 weeks in pregnant women with mild hypertension disorders such as high blood pressure and mild preeclampsia, according to a new study in The Lancet.

The study included 756 pregnant women in the Netherlands. All had been pregnant 36 to 41 weeks and had gestational hypertension or mild preeclampsia. Some of the women underwent induced labor and others were monitored as their pregnancies continued.

The two groups were compared on a number of measures that the researchers labeled as poor maternal outcome, including death, eclampsia, pulmonary edema, progression to severe high blood pressure, major post-birth bleeding (loss of a liter or more of blood), and what's known as HELLP syndrome (hemolysis, elevated liver enzymes and low platelet, or red blood cell, count).

Poor maternal outcome occurred in 31 percent of the women who had induced labor and in 44 percent who were monitored. For women who had induced labor, that equated to a 29 percent lower risk for developing poor maternal outcome than those who were monitored, the study reported.

The findings appear online Aug. 3 in The Lancet.

The researchers also found that women who had induced labor had fewer cesarean sections than those in the monitored group.

"The results of our trial are important for both developed countries in which induction of labor in women with hypertensive disease beyond 36 weeks' gestation has been controversial, and for developing countries in which maternal morbidity and mortality rates are substantially increased," wrote Dr. Corine M. Koopmans, of the University Medical Centre Groningen, and colleagues.

"Our finding that induction of labor was associated with a reduced risk of severe hypertension or HELLP syndrome and subsequent need for cesarean section emphasizes the importance of frequent blood pressure monitoring during the concluding weeks of pregnancy," they added.

The study authors concluded that "induction of labor should be advised for women with gestational hypertension and a diastolic blood pressure of 95 mm Hg or higher or mild preeclampsia at a gestational age beyond 37 weeks."

More information

The U.S. National Heart, Lung, and Blood Institute has more about high blood pressure during pregnancy.

TUESDAY, Aug. 4 (HealthDay News) -- In an effort to help people vulnerable to prolonged grief disorder, researchers have developed an accurate process to diagnose the mental condition so it can be officially recognized and treated by medical professionals.

Prolonged grief disorder is thought to exist when a person becomes stuck for months or years in what mental health professionals would consider an otherwise normal grief and loss cycle, and are unable to move on in their lives. While often discussed in recent decades, professionals have differed on criteria, symptoms and how to diagnose.

Prolonged grief disorder is not recognized in the current edition of the Diagnostic and Statistical Manual of Mental Disorders or the International Statistical Classification of Diseases and Related Health Problems, which are the standard guides for diagnostic criteria.

In the study appearing online Aug. 3 in the journal PLoS Medicine, researchers from Dana-Farber Cancer Institute in Boston developed and tested an algorithmic system for diagnosing the condition based on long-term symptoms that were agreed upon by experts in bereavement, mood and anxiety disorders. These symptoms -- including suffering caused by yearning for the deceased, and at least five of nine other symptoms, such as emotional numbness -- need to have existed for at least six months and impair the person's functionality.

The authors say their findings confirm the disorder is "a distinct mental disorder on the grounds that it is a clinically significant form of psychological distress associated with substantial disability."

More information

The U.S. National Cancer Institute has more about loss, grief and bereavement.

THURSDAY, July 30 (HealthDay News) -- Women who are prone to the common vaginal infection, bacterial vaginosis, are less likely to have a recurrence if they take hormonal contraception, whether it be birth control pills or Depo-Provera injections, new research suggests.

In the study, researchers examined medical records for 330 women with a mean age of nearly 25 who visited two sexually transmitted disease clinics in Baltimore between April 2005 and October 2006. About 133, or 40.3 percent, were diagnosed with bacterial vaginosis.

The women were prescribed a contraceptive, either progestin only (such as Depo-Provera) or estrogen-progestin combination (a birth control pill).

Women who were taking an oral contraceptive that included estrogen and progestin were 34 percent less likely to have a recurrence of bacterial vaginosis than women not taking a contraceptive. Women who were on a progestin-only contraceptive were 58 percent less likely to have a recurrence, the researchers found.

Though the reduction attributed to the combined pill was not statistically significant, "it's fair to say a benefit is suggested," said senior study author Dr. Emily Erbelding, an associate professor of medicine at Johns Hopkins Bayview Medical Center.

The study appears in the July issue of Contraception: An International Reproductive Health Journal.

The study authors said they would not recommend that women who are prone to bacterial vaginosis start taking birth control for the sole purpose of warding off bacterial vaginosis.

"If you have other reasons for choosing birth control, it could be an added benefit," Erbelding said.

Dr. Jennifer Wu, an obstetrician-gynecologist at Lenox Hill Hospital in New York City, called the findings "encouraging."

"It supports that birth control pills possibly have additional advantages that can be used for treating bacterial vaginosis," Wu said.

Bacterial vaginosis occurs when the normal bacterial flora of the vagina is disrupted and replaced by an overproduction of other types of bacteria. Symptoms include a fishy odor and discharge, as well as itching, burning or pain. Women can also have bacterial vaginosis without symptoms.

It's the most common vaginal infection in women of childbearing age and is associated with preterm delivery and low birth weight babies, according to the U.S. Centers for Disease Control and Prevention.

Though treatable by antibiotics, bacterial vaginosis tends to recur, Erbelding said.

Previous research has shown that 15 percent to 30 percent of women have symptomatic bacterial vaginosis within three months after taking antibiotics, and 70 percent have a recurrence within nine months.

"As a clinician, we are always frustrated by the fact that our treatments aren't very good," Erbelding said. "They may ameliorate the symptoms for some time, but often bacterial vaginosis recurs."

Racial minorities are at greater risk of bacterial vaginosis, Erbelding said. In the study, about 82 percent of participants were black and 69 percent had been diagnosed with bacterial vaginosis before.

Bacterial vaginosis is also associated with sexual activity, douching and sexually transmitted diseases, including chlamydia, gonorrhea, herpes simplex virus and HIV.

Researchers aren't sure if bacterial vaginosis makes a woman more susceptible to the other infections or if the other infections make vaginosis more likely, Erbelding said.

"Nobody really knows which comes first," Erbelding said.

Hormonal contraceptives may help ward off a recurrence by altering the vaginal ecology or by reducing menstruation, which is also associated with changes to vaginal bacteria levels, according to the study.

More information

The U.S. Centers for Disease Control and Prevention has more on bacterial vaginosis.