Here are some of the latest health and medical news developments, compiled by editors of HealthDay:

Sodium Nitrite Stimulates Blood Vessel Growth

Daily injections of sodium nitrite stimulated the growth of new blood vessels and restored blood flow to tissues damaged by simulated vascular disease in just three to seven days, a new U.S. study found.

Researchers induced ischemia (reduced blood flow) in the hind legs of mice by tying off the rodents' femoral arteries. The mice then received twice-a-day injections of low-dose sodium nitrite, Agence France-Presse reported.

Within three days, the animals' hind legs were showing signs of new blood vessel growth (angiogenesis). Within seven days, the blood supply in their hind legs was almost back to normal. In a group of mice that received no treatment, it took 28 days for circulation in their hind legs to return to normal.

Ischemia occurs in people with conditions such as peripheral artery disease and diabetes.

"The treatment has tremendous potential for stimulating angiogenesis to alleviate the discomfort caused by ischemia, and at the dosages we used, sodium nitrite is safe and far below any toxicity threshold," said Christopher Kevil, an associate professor of pathology at Louisiana State University Health Science Center in Shreveport, AFP reported.

"Moreover, our work suggests that sodium nitrite therapy could be beneficial for stimulating angiogenesis and tissue healing after ischemic events seen in stroke and heart attacks," Kevil said.

The study appears in the journal Proceedings of the National Academy of Sciences.

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Evolving Bird Flu Viruses May Pose Pandemic Threat

U.S. researchers have identified certain strains of bird flu that appear to be moving closer to developing traits that could trigger a human pandemic.

They found that a few of the H7 virus strains that caused minor, non-transmissible infections among people in North America between 2002 and 2004 may be evolving the same human tracheal cell sugar-binding properties seen in flu viruses that caused global pandemics in 1918, 1957 and 1968, Agence France-Presse reported.

"These findings suggest that the H7 class of viruses are partially adapted to recognize the receptors that are preferred by the human influenza virus," said Terrence Tumpey, a senior microbiologist with the U.S. Centers for Disease Control and Prevention.

If these H7 viruses continue this type of evolution, they may be able to pass more easily between animals and people, said the researchers, who called for strict surveillance of avian flu viruses, AFP reported.

The study appears in the journal Proceedings of the National Academy of Sciences.

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Warm Weather Workouts Require Common-Sense Precautions

Memorial Day is considered the unofficial start of summer, and that means more people will be heading outdoors to pursue favorite exercises and physical activities.

With that in mind, the American College of Sports Medicine, the American Medical Association and more than 50 supporting organizations, including the National Athletic Trainers' Association, have launched the "Exercise is Medicine" initiative. It includes a list of tips that people of all ages can follow to enjoy physical activity and exercise while reducing the risk of "exertional heat illness."

"Many cases of heat illness are preventable and can be successfully treated if such conditions are properly recognized and appropriate care is provided in a timely manner," said certified athletic trainer Brendon McDermott, of the University of Connecticut. "We're hoping to educate athletes, coaches, parents and health-care providers about what can be done to prevent and treat heat illnesses."

To guard against heat illnesses, the trainers' association recommends the following steps:

  • Gradually increase activity in terms of intensity and duration in the heat. This prepares your body for more intense, longer duration exercise in warm conditions, and helps prevent injury and heat illness.
  • Mix in periods of rest during activity and assure adequate rest between exercise bouts. Rest breaks are an important defense against heat illness, and proper sleeping habits decrease your risk as well.
  • Begin outdoor activities only after you're properly hydrated. Drink water or sports drinks throughout physical activity in the heat.
  • A darker urine color is a quick sign of dehydration. Your urine should look more like lemonade than apple juice.
  • Exercise during cooler portions of the day -- early morning or late evening, if possible.
  • Don't participate in intense exercise if you show signs of an existing illness, such as fever, diarrhea or extreme fatigue. These can decrease your body's tolerance for heat and increase your risk of a heat illness.

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Poll: Wounded Iraq Soldiers Get Substandard Care From VA

A considerable majority of Americans believes that Veteran's Administration hospitals and other military health facilities are not giving wounded Iraq war veterans the quality of care they deserve.

The latest poll from the Harvard Opinion Research Program at the Harvard School of Public Health (HSPH) and the Harris Interactive® polling organization finds that 62 percent of Americans believe medical care for returning wounded U.S. soldiers from Iraq isn't adequate. In the same poll, 65 percent said that mental health care for returning vets was substandard, according to a HSPH news release.

The poll found that this opinion ran across the spectrum of American society. Those who had a family member serving in Iraq were just as likely as respondents with no family ties to the Iraq war to believe VA hospital care was substandard.

Yet, the poll also found that 60 percent of the respondents believed that medical treatment for wounded Iraq war veterans in military and VA hospitals is better (10 percent) or the same (50 percent) as the type of care they would receive in what the pollsters called "other major U.S. hospitals."

The poll is part of a continuing series by Harris Interactive and the Harvard School of Public Health: Debating Health: Election 2008.

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Caressing Preemies May Help With Pain of Medical Procedures

It's never too early for parents to hold, touch and caress their offspring, even if the baby is born very prematurely.

According to BBC News, researchers from McGill University in Montreal found that parents who cuddle with babies born as early as 28 weeks help lessen the stress of painful medical procedures the infants will have to endure. The normal term of pregnancy before delivering a baby is between 37 and 42 weeks, according to the U.S. government's National Institutes of Health.

In fact, reports the BBC, the McGill scientists believe the skin-to-skin contact between parents and baby is so important that it might aid in the recovery process from the medical procedures.

The researchers used a common test for newborns --- the heel pin prick to obtain blood to check blood sugar levels -- as a test for stressful reaction.

This test is almost always painful for newborns, BBC News reported. The result: For premature babies who were cuddled after having a heel pin prick, pain scores after 90 seconds were much lower than for the babies not held and caressed by an adult.

Lead researcher Celeste Johnson said she found that cuddling seemed to assist in the baby's recovery from a painful experience. "The pain response in very preterm neonates appears to be reduced by skin-to-skin maternal contact," she told the BBC.

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New York City Man Dies After Taking Aphrodisiac From Toad Venom

An illegal aphrodisiac sold on the street under a variety of names has killed a 35-year-old New York City man, prompting health officials to issue an alert.

According to the Associated Press, the man, who officials did not identify, was admitted to a New York City hospital earlier this month complaining of pain in his chest and abdomen. Health officials were able to determine he had taken a poisonous substance that comes in a hard, brown form, and is known as Love Stone, Jamaican Stone, Black Stone and Chinese Rock.

It is sold in many New York City neighborhoods in neighborhood stores, the AP reported, and the writing on the package is usually in a foreign language.

The warning from New York City's top dangerous substances officer was pointed: "There is no definitely safe way to use it," Dr. Robert Hoffman, director of the city's poison control center, told the wire service. "Don't buy it. Don't sell it. If you have it, don't use it. Throw it out."

Some people eat the substance, the AP reported, instead of applying it to the skin, as it is intended to be used. But even external application can be dangerous. The active ingredient comes from the venom of toads of the Bufo genus, and it can disrupt the heartbeat, the wire service said.