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

Researchers Spot Key to Aggressive Breast Cancer

The overproduction of a protein responsible for cell growth may be crucial to the origin and rapid spread of the most aggressive breast cancers, according to a team of scientists at the Dana-Farber Cancr Institute, Boston.

Increased levels of the protein, called cyclin D, overstimulate a molecular switch known as CDK4 kinase, which in turn triggers the uncontrolled proliferation of malignant cells, the scientists report in the current Cancer Cell. If those cancer cells also contain an oncogenic form of the HER2 gene, they can be especially virulent.

However, the drug Herceptin has shown potent activity in blocking HER2 cells, and other anti-cancer agents such as Gleevec work by blocking kinases.

As reported by the BBC Saturday, the Boston researchers say it should be possible to develop a drug targeted specifically to CDK4. Using that drug in combination with Herceptin could be highly effective therapy for women with very aggressive breast tumors, they said.

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FDA Mulls Over-The-Counter Sale of Diet Pill

Concerns over the potential for abuse and vitamin deficiencies will weigh heavily on an upcoming U.S. Food and Drug Administration decision on the over-the-counter sale of GlaxoSmithKline's popular weight-loss drug, Xenical (orlistat), to be marketed as Alli.

Alli (pronounced "ally") would be half the dose of prescription Xenical, which won FDA approval as a prescription weight loss medication in 1999, the Associated Press reported Friday.

FDA reviewer Dr. Karen Feibus said Alli is "a safe and effective weight loss agent" but has not yet recommended the drug for OTC sale.

The drug works by blocking the absorption of about one-quarter of the fat users consume, passing it through the body via the stool. But Feibus noted that the drug would raise the risk of vitamin deficiencies, since it also blocks absorption of fat-soluble nutrients such as vitamins D, E, K and beta-carotene. GlaxoSmithKline currently recommends that Xenical users take a multivitamin to help compensate for this loss.

According to the FDA, the drug may also block absorption of certain drugs, and should not be used by diabetic patients. However, one recent study found that 65 percent of diabetes patients were unaware that they should not take the drug.

The FDA expert also voiced concerns about the potential for abuse of an OTC form of orlistat. However, the drug's unpleasant side-effects -- such as oily stools and "involuntary leakage" of undigested fat -- should "limit the potential for abuse," Dr. Howard Eisenson, director of the Duke Diet and Fitness Center in Durham, N.C., told the AP.

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Medicare Drug Benefit Mix-Ups Harming Mentally Ill

The error-prone roll-out of Medicare's Part D drug benefit is keeping many mentally ill patients across the U.S. from getting the drugs they need, mental health workers say. In many cases, patients are ending up hospitalized because they are either not covered by the new plan, or are forced to contribute drug co-pays that many cannot afford.

In an interview with the New York Times, Birmingham, Ala., psychiatrist Dr. Jacqueline M. Feldman said "relapse is becoming more frequent" among her low-income Medicare patients since the Jan. 1 launch of the new program, which is aimed at getting prescription drugs to patients at lower cost through link ups with private insurers.

In many cases, pharmacists receive conflicting or inadequate information on patient eligibility and must wait hours while they try and reach insurers by phone, the Times reported. In other cases, patients who may be on multiple psychiatric and other drugs must pay co-pays of about $3 per prescription.

For the residents of Dayspring Village, a Florida assisted-living center for the mentally ill, those co-pays can quickly eat up the bulk of a resident's monthly $54 cash allowance. "How are these people going to get the money for a co-payment? They don't have it," the center's executive director Douglas D. Adkins told the Times.

In a memorandum to local social service agencies, Eunice Medina, a policy analyst with Florida's Department of Elder Affairs, said "We are all aware that the next couple months will be difficult for these clients, and that the possibility of a transition to a nursing home is their only option if prescriptions are not covered in assisted living facilities."

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FDA Warns of Fake Bird Flu Drugs

The U.S. Food and Drug Administration on Friday issued a warning on the sale of unlicensed, unapproved and often fraudulent products marketed as drugs against either seasonal or avian influenza.

These products, which include fake versions of the antiviral Tamiflu (oseltamivir), "may endanger the well-being and safety of consumers who take them without providing any therapeutic benefits or protection against any type of influenza," the agency said in a statement.

Officials noted that the agency and U.S. Customs officials have already intercepted products at the border purporting to be generic Tamiflu, but which on closer inspection contained nothing more than vitamin C and "other ineffective substances."

In other cases, the FBI has arrested individuals in Texas and Minnesota for running bogus flu vaccine clinics, where duped patients received little more than saline injections.

"These cases illustrate the dangers of buying drugs from unknown sources," the agency said.

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Antibiotic Linked to Liver Damage: Report

The antibiotic Ketek, used to treat lung and sinus infections, may be linked to liver damage that led to the death of a 26-year-old man and transplant surgery for a 51-year-old woman, according to a report published online Friday in the journal Annals of Internal Medicine.

Doctors at the Carolinas Medical Center in Charlotte, N.C., reported that three patients developed liver failure within days of being given Ketek, Bloomberg News reported.

All three cases occurred within a few months of each other last year, said report co-author Dr. John Hanson, a liver transplant doctor at the medical center.

"That struck us. We were quite shocked when we encountered the three cases. When we started comparing notes, we said we better put this together and report it. Drug reactions don't always get reported. That's why we felt obligated to report it so it would at least raise antennas," Hanson told Bloomberg.

He and his fellow authors urge caution in prescribing the drug, which was approved by the U.S. Food and Drug Administration in 2004.

The doctors sent their findings to the FDA and discussed them with Sanofi-Aventis SA, which makes Ketek. The company is currently reviewing the data, the news report said.

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