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NEW YORK (AP) -- Two huge international studies show that people who lack certain chunks of DNA run a dramatically higher risk of getting schizophrenia, a finding that could help open new doors to understanding and diagnosing the disease.

These deletions are rare, each found in less than 1 percent of schizophrenia patients. But each one boosts the risk of disease by as much as 15-fold, by one estimate.

Scientists said studying such abnormalities may help them find new medications by shedding light on what causes the disease. And if enough rare aberrations can be found eventually, they may be combined into a test to help in diagnosis, said Kari Stefansson, chief executive officer of deCode Genetics of Reykjavik, Iceland, and an author of one of the studies.

Schizophrenia is currently diagnosed by its symptoms.

The human DNA can be thought of as a very long string of letters - about 3 billion of them - that sometimes form words (genes). Each newly identified deletion removes a section of about half a million to 2 million letters.

In the past, scientists have found specific genes and deletions linked to schizophrenia risk. But the new work is notable because two large studies independently identified the same two DNA deletions, and those aberrations have such a big impact on disease risk. Stefansson's paper also reports evidence for a third deletion.

While the DNA deletions are linked to only a tiny fraction of schizophrenia cases, it's not unusual that a very rare cause of a disease provides insights that apply more generally, said Dr. Pamela Sklar of Massachusetts General Hospital, an author of the other paper. She said such knowledge can lead to treatments for many people.

Both papers were published online Wednesday by the journal Nature. Experts not connected with the work praised the results.

"This is tremendous" for basic research into the disease, said Dr. Linda Brzustowicz of Rutgers University. But since the deletions found so far are related to such a small fraction of schizophrenia cases, she said it's too early for companies to offer to test people for them.

Stefansson's paper, which included authors from more than a dozen centers in the United States, Europe and China, reported findings from DNA tests in about 4,700 people with schizophrenia and more than 40,000 healthy people. Sklar's paper, which included scientists from 11 institutes in the United States, Europe and Australia, tested about 3,400 people with schizophrenia and 3,200 others.

Both papers found that while the deletions were rare in schizophrenia patients, they were even rarer in people without the disease. Scientists say the disease results from a combination of genetic predisposition and environmental influences.

The two deletions found by both research groups boost schizophrenia risk 12-fold and 15-fold, Stefansson's group calculated. A third deletion his group found appears to raise risk about threefold.

Sklar said she was "absolutely delighted" that the papers found the two deletions independently, using different methods.

Anne Pulver, a schizophrenia genetics expert at Johns Hopkins University, said the papers represent a welcome shift in focus for finding genetic variants that affect risk of schizophrenia.

Traditionally, that search has centered on relatively common variants, each with little effect on an individual's risk. The new approach seeks rare variants that play a larger role. The new approach should help identify subgroups of patients with different genetic causes for their disease, she said. Eventually that could lead to treatments that are tailored to the differing biological causes, with improved outcomes, she said.

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On the Net:

Nature: http://www.nature.com/nature

Information on schizophrenia: http://www.nimh.nih.gov/health/topics/schizophrenia

© 2008 The Associated Press.

WASHINGTON (AP) -- The salmonella strain linked to a nationwide outbreak has been found in irrigation water and in a sample from a batch of serrano peppers at a Mexican farm, federal health officials said Wednesday.

Dr. David Acheson, the Food and Drug Administration's food safety chief, called the finding a key breakthrough in the case, as did another health official.

"We have a smoking gun, it appears," said Dr. Lonnie King, who directs the center for foodborne illnesses at the Centers for Disease Control and Prevention.

Acheson said the farm is in Nuevo Leon, Mexico. Previously, the FDA had traced a contaminated jalapeno pepper to a farm in the Mexican state of Tamaulipas. Both farms shipped through a packing facility in Nuevo Leon, raising the possibility that contamination could have occurred there.

The FDA advised consumers to avoid raw serrano peppers from Mexico, in addition to raw jalapeno peppers from Mexico, and any foods that contain them.

In a statement Wednesday, Mexico's Agriculture Department said it "rejects" the FDA's conclusion that the source of the salmonella outbreak had been located in the Mexican farm's irrigation water.

"The farm unit in question ended its harvest more than a month ago, so the sample they say they have lacks scientific validity" because the sample "was taken recently from a tank holding rain water that was not used in production," the statement said.

"The government reiterates its call for the FDA to use information responsibly and, above all, to base it on scientific evidence," the statement concluded.

Acheson and other officials were grilled at a congressional hearing about why the investigation originally focused on tomatoes. Industry representatives complained that they have lost more than $300 million and had to dump tons of perfectly good tomatoes they could not sell because of government warnings. The probe was slowed even more because FDA investigators were unfamiliar with the workings of the tomato industry and were reluctant to share information, they said.

"For weeks and weeks, investigators were on the trail of the wrong product," Thomas Stenzel, president of the United Fresh Produce Assn., told the House Agriculture Committee.

But federal officials insisted that tomatoes still cannot be ruled out and that it is quite possible the outbreak was caused by several different kinds of contaminated produce.

"I don't think we can say that (tomatoes) were needlessly dumped," Acheson told reporters after the hearing. "The early part of the investigation clearly implicated tomatoes."

The outbreak has sickened more than 1,300 people since April.

Tomatoes had been the prime suspect in the nationwide outbreak for weeks. But last week, the FDA said only jalapeno peppers grown in Mexico were currently implicated in the nationwide salmonella outbreak. The FDA said then it had found the same strain of salmonella responsible for the outbreak on a single Mexican-grown jalapeno in a south Texas produce warehouse. The agency explained that any contaminated tomatoes would be out of the food supply chain by now.

For now, the focus of the investigation is on the two farms in Mexico, which Acheson said are quite far from each other.

The Tamaulipas farm also grew tomatoes and peppers, said Acheson. But the tainted pepper traced to that farm was found at a warehouse facility in McAllen, Texas, raising the possibility it could have been contaminated along the way. Acheson said samples have been taken from the Tamaulipas farm, and lab results are pending.

The Nuevo Leon farm did not grow tomatoes.

Lawmakers are considering a range of reforms to prevent future outbreaks and speed their investigation. These include improving communication between investigators and the industry, imposing standards for good agricultural practices and improving traceability.

"You could describe our current food safety system as 'outbreak roulette,'" said Rep. Dennis Cardoza, D-Calif., chairman of the subcommittee holding the hearing. "One spin of the outbreak wheel, and your industry may be bankrupt, your loved ones sickened."

© 2008 The Associated Press.

WASHINGTON (AP) -- The Food and Drug Administration on Wednesday ordered changes in the prescribing information for two widely used anemia drugs, saying the risks of the medications outweigh the benefits for certain cancer patients.

Anemia is a frequent side effect of cancer treatment, and can leave already frail patients in an even more debilitated condition. The drugs at issue, Aranesp and Procrit, are commonly used to treat such patients and are made by California-based Amgen. But recent studies have indicated that the treatments could worsen some cancers, and might even shorten patients' lives.

Dr. Richard Pazdur, head of the FDA's oncology section, said Wednesday's directive was the first time the agency has invoked new powers Congress granted it last year to order drug makers to make changes in their prescribing literature, also known as the drug label. Previously, such changes had to be negotiated.

The FDA ordered two specific changes:

The agency said the drugs should not be used with patients who are expected to be cured of cancer. Amgen had pressed for language that would have allowed the medications to be used for some patients who are expected to be cured, but who are not able to receive transfusions of red blood cells.

The second change said patients should not be treated with the drugs unless their hemoglobin levels drop below 10 grams per deciliter of blood. The company had asserted the drugs should also be an option for treating some patients with a slightly higher hemoglobin level.

The FDA's action brings the agency into line with a new Medicare policy that restricts payment for the drugs.

Amgen said in a statement the changes ordered by the FDA were "consistent" with the company's expectations.

© 2008 The Associated Press.

The slow economy is taking its toll on a vital segment of the workforce: home health aides. Some caregivers commute as far as 100 miles to assist a patient, but gas prices are forcing them to reevaluate their job, Seth Doane reports.

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