Health Highlights: June 6, 2006

Cancer of the Larynx Linked to Asbestos Exposure Harvard Scientists Begin Experiments to Clone Human Embryos Medicaid Recipients Will Need Proof of Citizenship New Test Spots Bird Flu in Birds Within 4 Hours, Official Says Pot Impairs Learning in Adolescent Rats: Study

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

Cancer of the Larynx Linked to Asbestos Exposure

Asbestos, already generally accepted as a cause of a number of respiratory ailments including lung cancer, may also be a source for laryngeal cancer, the U.S. government's Institute of Medicine says.

The Associated Press reports that a series of studies have found that certain cancers of the throat and lungs are similar, so the U.S. Senate asked the institute to investigate a potential link between asbestos and other upper-body cancers.

In addition to lung cancer, asbestos, historically used to insulate buildings, is also linked to mesothelioma, a rare cancer that attacks the lining of the chest.

But the institute said there was not enough evidence of a connection between asbestos and other malignancies, including cancers of the upper throat and esophagus.


Harvard Scientists Begin Experiments to Clone Human Embryos

U.S. scientists said Tuesday they have begun work on cloning human embryos to create stem cells, a goal that some find ethically objectionable, according to the Associated Press.

Dr. George Daley, a leading expert in blood diseases and an executive committee member of the Harvard Stem Cell Institute, is overseeing the work at Children's Hospital Boston, the main pediatric teaching hospital of Harvard Medical School. Daley said he had begun experiments but declined to describe the results, AP reported.

The Children's Hospital team's goal is to create stem cells for treating blood diseases like sickle-cell anemia, leukemia and other blood disorders. Two other researchers, Douglas Melton and Kevin Eggan, have received approval from a series of review boards to begin similar work, the institute said. Melton plans to focus on diabetes. Eggan plans to work on neurodegenerative conditions like Lou Gehrig's disease.

By cloning embryos, scientists hope to produce transplant material to treat a variety of diseases. Stem cells can give rise to more specialized cells and tissues that can be genetically matched to patients, avoiding the problem of rejection.

The University of California, San Francisco, is also pursuing the cloning of human embryos, according to AP, joining the race among a small group of researchers in this controversial pursuit.


Medicaid Recipients Will Need Proof of Citizenship

Starting July 1, millions of low-income Americans will have to show proof of United States citizenship, such as a birth certificate or a U.S. passport, if they seek health care through their state Medicaid programs. The new requirement will apply to all Medicaid applications, as well as all applications to renew Medicaid coverage after that date, the Associated Press reported Tuesday.

Health analysts and advocacy groups for the poor and mentally ill say they fear the provision, designed to root out cases of illegal immigrants getting their care paid for by the government, could prevent some citizens from getting their own care. The advocates have asked the Bush administration to presume those seeking care are eligible and be given time to get the necessary documentation.

Mark McClellan, administrator for the Centers for Medicare and Medicaid Services, said the agency was sensitive to the consumer groups' concerns and was crafting a process for exceptions, according to AP.

Federal law says a person must be a citizen to receive Medicaid benefits; however, emergency care cannot be denied. Forty-six states now can accept a signed declaration as proof of U.S. citizenship, but only Montana, New York, New Hampshire and Texas require applicants to submit documents verifying citizenship, the AP said.


New Test Spots Bird Flu in Birds Within 4 Hours, Official Says

U.S. Agriculture Secretary Mike Johanns said Tuesday that scientists have a new test that can tell within four hours if a bird is infected with bird flu, but it still will take about a week to know if it has the deadly Asian strain.

Bird flu hasn't yet reached North America, but testing of migrating wild birds has begun in an attempt to catch it early if it does, Johanns told the Associated Press, in a joint interview with U.S. Health and Human Services Secretary Mike Leavitt.

Leavitt added that four hours also is how long it takes to get preliminary results in people infected with the H5N1 virus, too. But if bird flu ever begins spreading easily among people, that's too long, he told the AP. 'If it occurs anywhere in the world, it's just a matter of weeks until it appears in the United States,' Leavitt said.

Bird flu has killed at least 127 people worldwide since it began spreading in Asia in late 2003. Though it is difficult for people to catch the virus, experts fear it could mutate into a form easily spread between people, potentially sparking a worldwide outbreak.


Pot Impairs Learning in Adolescent Rats: Study

The main active ingredient in marijuana leads to short-term impairment of learning in adolescent rats, but doesn't seem to affect adults similarly, Duke University Medical Center researchers report.

Their study compared the effects of delta9-tetrahydrocannabinol (THC) on the memory ability of adolescent and adult rats to see if the animals, and perhaps humans, are more sensitive to THC at certain stages. Researchers found that chronic exposure to THC during adolescence may not lead to long-term damage persisting into adulthood, but said the finding should be interpreted cautiously, since other studies have suggested the damage may be longer-lasting.

The study tested the effects of THC exposure on memory and learning by dosing rats with varying amounts, training them to navigate a "water maze," and then measuring how well the rats remembered how to get to a stationary platform in the water. After the THC had cleared the rats' systems and the adolescents had reached full maturity, the researchers tested how well they performed in the water maze. The chronic exposure appeared to have no effect on the rats' later learning abilities, the study found.

The findings appear in the March 2006 issue of the journal Pharmacology, Biochemistry and Behavior, which is expected to be published June 8.

"There are plenty of good reasons for adolescents to not smoke pot," said H. Scott Swartzwelder, a professor of psychiatry at Duke and the Durham Veterans Affairs Medical Center and the senior author on the study. "The teen years require a lot of learning and preparation for adulthood."


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