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

U.S. Scientists Win Nobel Prize for Work on Cell Receptors

Two American scientists have been awarded the 2012 Nobel Prize in chemistry for their work on protein receptors that enable body cells to sense and respond to outside signals -- research that plays an important role in developing more effective drugs.

Robert Lefkowitz and Brian Kobilka made groundbreaking discoveries on an important family of receptors called G-protein-coupled receptors, according to the Royal Swedish Academy of Sciences, the Associated Pressreported.

About half of all medications act on these receptors, so knowing more about them helps scientists create better drugs.

Lefkowitz, 69, is an investigator at the Howard Hughes Medical Institute and professor at Duke University Medical Center in Durham, North Carolina. Kobilka, 57, is a professor at Stanford University School of Medicine in California, the APreported.

It was long a mystery how cells interact with their surroundings and adapt to new situations, such as when adrenaline boosts blood pressure and heart rate, the academy noted. It was believed that cell surfaces had some type of receptor for hormones.

Lefkowitz identified such receptors, including the receptor for adrenaline, and started delving into how it works. Kobilka's research helped scientists realize that there is an entire family of receptors that look alike - the family of G-protein-coupled receptors, the APreported.

The Nobel Prize is "fantastic recognition for helping us further understand the intricate details of biochemical systems in our bodies," said American Chemical Society President Bassam Z. Shakhashiri.

"They both have made great contributions to our understanding of health and disease," Shakhashiri told the AP. "This is going to help us a great deal to develop new pharmaceuticals, new medicines for combating disease."

The important role played by receptors is now taken for granted, noted Mark Downs, chief executive of Britain's Society of Biology.

"This ground breaking work spanning genetics and biochemistry has laid the basis for much of our understanding of modern pharmacology as well as how cells in different parts of living organisms can react differently to external stimulation, such as light and smell, or the internal systems which control our bodies such as hormones," Downs said in a statement, the APreported.

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Feds Ask for Full Appeals Court Rehearing on Cigarette Warning Labels

A petition asking a federal appeals court to rehear a challenge to a Food and Drug Administration requirement that cigarette packages carry large graphic health warnings was filed Tuesday by the U.S. Justice Department.

The warnings are meant to show consumers that smoking can disfigure and kill people. In August, a three-judge panel of the U.S. Court of Appeals in Washington affirmed a lower court ruling blocking the requirement, saying it contradicted the First Amendment's free speech protections, the Associated Pressreported.

The federal government wants the full appeals court to rehear the case, but the court rarely grants such appeals.

Some of the nation's largest tobacco companies sued to block the requirement for the nine graphic warnings, which included photos of dead and diseased smokers, such as a man exhaling cigarette smoke through a tracheotomy hole in his throat and a cloud of cigarette smoke surrounding an infant receiving a mother's kiss, the APreported.

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Graco High Chairs Recalled

Graco Classic Wood high chairs are being recalled in the United States and Canada because the chair's seat can loosen or detach from the base, posing a fall hazard to the child.

The recall by Graco Children's Products Inc. of Atlanta, Ga. covers about 86,000 chairs in the U.S. and 3,400 in Canada. The company has received 58 reports of chair seats loosening or detaching from the base, the U.S. Consumer Product Safety Commission said.

There have been nine reports of children falling when the seat detached from the base, resulting in injuries such as bumps, bruises and scratches. There was one report of a child in Canada suffering a concussion.

The recalled chairs have the following model numbers printed on a label on the underside of the seat assembly: 3C00BPN, 3C00BPN TC, 3C00CHY, 3C00CHY TC, 3C00CPO or 3C00CPO TC. The chairs were sold at retail stores across the U.S. and online between September 2007 and December 2010.

Consumers with the high chairs should immediately stop using them and contact Graco for a free repair kit. For more information, phone Graco at 1-800-345-4109 or go to the company's website, the CPSC said.

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Dengue Epidemic Declared in Puerto Rico

A dengue epidemic was declared Monday by Puerto Rico's health department.

At least six people have died, including two children younger than 10, according to Health Secretary Lorenzo Gonzalez. There have been 4,816 cases reported, including 21 cases of potentially fatal hemorrhagic dengue, the Associated Pressreported.

There were 342 new cases reported in one week last month, twice the number of cases during the same period last year, the U.S. Centers for Disease Control and Prevention said.

The dengue virus is transmitted by mosquitoes. Symptoms include fever, headaches and joint and muscle pain. In 2010, a dengue epidemic in Puerto Rico resulted in more than 12,000 suspected cases and claimed a record 31 lives, the APreported.

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