WEDNESDAY, May 2 (HealthDay News) -- Finding out who the father is in paternity cases may become easier with the emergence of a simple blood test for women that can be given in the first trimester of pregnancy.

The paternity screening, developed at a private biotech company in Maryland, is intended to replace more invasive, risky tests that are done later in the pregnancy, its developer says.

"It's not knowing who the father is that makes a pregnancy challenging and stressful for the mother," said Dr. Ravinder Dhallan, chairman, CEO and founder of Ravgen Inc., the Columbia, Md.-based company that developed the test. "Knowing who the father is allows them to make informed decisions about their pregnancies. We've found it can be done very simply and eventually, inexpensively."

Scientists at Ravgen use a chemical "fixative," such as formaldehyde, to stabilize fetal DNA in the mother's blood and produce larger analyzable amounts. Of blood samples collected from 30 pregnant women, the researchers said they correctly determined paternity for all of them.

Dhallan is co-author of a letter about the procedure published in the May 3 issue of the New England Journal of Medicine.

About 5 percent of women who are raped become pregnant, producing an estimated 32,000 unintended pregnancies each year in the United States, according to Dhallan. Currently available prenatal paternity tests include amniocentesis and chorionic villus sampling -- which extract fetal cells from a pregnant woman's amniotic fluid or placenta and pose a small risk of producing a miscarriage.

The 30 blood tests were carried out between October 2007 and January 2010, and results were confirmed after babies were delivered by swabbing the inside of their cheeks to analyze their DNA. The mothers' average age was 30, and the average length of the pregnancy was 10 weeks when blood tests were done.

Each maternal blood sample was paired with blood from the stated biological father and then randomly grouped with one of 29 samples from unrelated men. Processing the three samples in each group, researchers correctly determined paternity for all 30 by comparing the genetic profile of fetal DNA in maternal blood with those of the two "paternal" samples, one genuine and one not.

Traditional invasive tests can't be done until between 10 and 15 weeks of pregnancy, but 80 percent of abortions occur before 10 weeks' gestation, Dhallan explained.

Dhallan said a test like this might prevent some women from aborting before finding out whether their baby was conceived through rape or consensual sex with their partners.

"A quarter of women tell me straight up that my answer will impact whether they keep the pregnancy," said Dhallan, adding that he and his team have since performed the test on more than 200 women. "By the time I did four cases, we had saved one baby. To me, every case is about life and death."

Dr. Jill Rabin, chief of ambulatory care, obstetrics and gynecology at Long Island Jewish Medical Center in New York, praised the test as "really exciting" because of its noninvasive nature.

"Unfortunately, we do have a certain percentage of pregnancies that are complicated by alleged sexual assault," Rabin said. "Those would be the first patients who would want to know [paternity] as early as possible. But we do have people every week . . . who request paternity testing for different reasons. A lot has to do with child support."

U.S. Food and Drug Administration approval of the paternity blood test is not required, Dhallan said. Although he has not had it licensed for widespread use, he said he will make the test available on a limited basis through patients' physicians.

Dhallan said the cost of the procedure is comparable to the current cost of amniocentesis -- about $1,600 -- but that he hopes to price the test lower as it becomes more widely used.

More information

The American Academy of Family Physicians has more information on prenatal diagnosis  .

WEDNESDAY, May 2 (HealthDay News) -- New research shows that gene therapy can have long-lasting effects on the immune cells of HIV patients -- a promising sign -- even though the specific treatment being studied did not eradicate the virus.

This approach is one of several gene therapy strategies that are being investigated by scientists as possible ways to keep the AIDS virus from spreading in the blood.

In this case, "people were treated by gene therapy and nothing bad happened. It was safe," said study co-author Frederic Bushman, a professor of microbiology at the University of Pennsylvania.

In addition, he said, the treated immune cells managed to remain around for about a decade. "The general picture that emerges about genetic alterations to human immune cells is that they can persist for a long time if you do it right."

The study appears in the May 2 issue of Science Translational Medicine.

Researchers have long been exploring gene therapy -- in which cells in the body are genetically modified -- as a possible treatment for infection with HIV, the virus that causes AIDS. The idea is that the therapy would offer a permanent alternative to costly medications that come with potentially disabling side effects.

"Just think about what an HIV patient has to do: take drugs every day for the rest of his life, and the minute he stops taking them, the virus starts coming back," said John Rossi, chair of the department of molecular and cellular biology at the Beckman Research Institute of the City of Hope, in Duarte, Calif. He was not associated with the new research.

The study looks at 43 HIV-positive patients. Between 1998 and 2002, researchers removed blood from the patients, genetically modified it, and injected it back into them.

The plan was to program immune cells known as T cells to kill HIV cells.

Up to 11 years later, researchers found that all 43 patients are healthy, and 41 still have modified T cells in their bodies. That means the modified cells didn't cause leukemia, as has happened with some similar gene -therapy treatments.

The treatment, however, didn't seem to have had a major impact on the HIV in the patients and "may not have worked at all" on that front, study co-author Bushman said.

Dr. David Looney, director of the Center for AIDS Research at the University of California, San Diego, said the research is still "exciting and promising" since it shows that modified immune cells can last a long time, potentially decades.

Several research projects are continuing to examine gene therapy for HIV patients. There's a caveat, however: If gene therapy treatments become available, they seem likely to be extremely expensive.

But Bushman said that if the gene therapy could someday replace antiretroviral medicines, the cost might still be lower than keeping patients on drugs for rest of their lives.

More information

For more about HIV, visit the U.S. National Library of Medicine.

FRIDAY, April 27 (HealthDay News) -- The U.S. Food and Drug Administration on Friday announced that it had approved Stendra, a new medication for erectile dysfunction.

Stendra (avanafil) joins Viagra, Cialis and Levitra, all from a class of drugs known as phosphodiesterase type 5 inhibitors that help boost blood flow to the penis.

According to the FDA, fast-acting Stendra is designed to be taken 30 minutes before sexual activity and at the lowest effective dose.

Whether the new drug adds any value to the existing range of impotence medications is unclear, one expert said.

Dr. Bruce Kava, acting chairman of urology at the University of Miami School of Medicine, said that "the only advantage Stendra may have is a more rapid onset of action over the other drugs. The question is whether there are any advantages to a more rapid onset."

He noted that many patients don't respond to one or another of these drugs. But there is no way right now of telling who will respond to which drug. "Sometimes it's hit or miss," he explained.

Men will have to try these drugs to find the one that best suits their lifestyle, Kava said. For example, for some men Cialis works best because its effects seem to last much longer than that of the other drugs, he said.

The FDA said Stendra's approval means one more option for patients.

"This approval expands the available treatment options to men experiencing erectile dysfunction, and enables patients, in consultation with their doctor, to choose the most appropriate treatment for their needs," Dr. Victoria Kusiak, deputy director of the Office of Drug Evaluation III in the FDA's Center for Drug Evaluation and Research, said in a statement.

Stendra comes with the same warnings as its companions in this drug class. It should not be taken by men who take nitrates -- drugs used to treat chest pain (angina). This combination can cause a sudden drop in blood pressure, the FDA cautioned.

The agency also warned that these drugs can, in rare cases, cause color vision changes and in rare instances, men have also reported a sudden loss of vision in one or both eyes. Sudden loss or decrease in hearing has also been reported in patients taking these drugs. "Patients who experience a sudden loss of vision or hearing should stop taking PDE5 inhibitors, including Stendra, and call a doctor right away," the FDA said.

The most common side effects reported with Stendra include headache, redness of the face and other areas, nasal congestion, cold-like symptoms and back pain.

In rare cases, patients taking these drugs may get an erection lasting four hours or longer that will not go away. "If this happens, patients should seek immediate medical care," the agency said.

Erectile dysfunction occurs when a man has trouble getting or maintaining an erection. An estimated 30 million American men in are affected by erectile dysfunction, according to the FDA.

Stendra's safety and efficacy were established in three double-blind, placebo-controlled clinical studies. A total of 1,267 patients were randomly assigned to take Stendra for up to 12 weeks at doses of 50 milligrams (mg), 100 mg or 200 mg, or a placebo as needed about 30 minutes before sexual activity.

Stendra is marketed by Mountain View, Calif.-based Vivus Inc.

More information

For more information on erectile dysfunction, visit the U.S. National Library of Medicine.