News in brief - Aug. 23/30, 2004

Fifth disease puts pregnancies at risk - Advances in psoriasis treatments - Cancer vaccine shows promise - Prions can replicate

Fifth disease puts pregnancies at risk

As the school year approaches, women not previously infected with parvovirus B19, or "fifth disease," should be made aware of the risk of miscarriage or stillbirth if they should contract this common childhood illness. Schools are breeding grounds for fifth disease, making pregnant teachers and parents of school-age children most at risk. An FDA-approved test is available to establish whether a woman has immunity.

Women previously infected are not at risk. However, those never infected have a 30% risk of becoming so if exposed and a 5% to 9% risk of losing their child if they become infected.

Advances in psoriasis treatments

Psoriasis patients who have given up in frustration on treating their disease should be encouraged to check in with a physician because significant advances have been made over the past five years, said Gail M. Zimmerman, president and CEO of the Psoriasis Foundation. Some of the new treatments were highlighted at the Foundation's national conference held earlier this month in San Diego.

For example, the first drug for treating psoriatic arthritis has been approved, as have three biologic drugs that target portions of the immune system implicated in psoriasis. Some older treatments have also been improved in recent years, she said.

A new method of administering ultraviolet light has been devised that uses a narrower range of light to maximize effectiveness. A laser that directs light to small, problematic patches of skin is also available.

In addition, a foam-based topical treatment has been developed.

Cancer vaccine shows promise

A new approach in cancer vaccine development that includes killing healthy skin cells to trigger a healing immune response was effective in eradicating skin tumors of mice, according to a research team from the Mayo Clinic and several British institutions. Their work appears in this month's Nature Biotechnology.

Multiple rounds of "heat shock" vaccine therapy inflicted a stress known as "inflammatory cell death" on skin cells to which researchers attached an unusual protein called heat shock protein 70. They were then able to trigger a healing immune response aimed at the skin cancer tumors that was so strong it eradicated the tumors.

Normally the destruction of healthy cells is avoided, as the goal of conventional toxic chemotherapy is to kill only the cancer cells.

"We hope our novel approach will be a more specific and therefore gentler therapy for patients," said Richard Vile, PhD, Mayo immunologist and lead researcher.

Skin cancer is the most common form of cancer in the United States, with an estimated 1 million new cases diagnosed annually.

Prions can replicate

New research findings show that prions can make disease-causing copies of themselves without the presence of viral DNA or RNA.

Researchers produced a prion protein that can trigger the development of a neurological disorder in mice that is similar to mad cow disease, according to a study published in the July 30 Science.

For their study, researchers, including Stanley B. Prusiner, MD, of the University of California, San Francisco, who won the 1997 Nobel Prize in Medicine for his discovery of prions, produced prion protein fragments in bacteria, folded them into larger protein structures called amyloid fibrils and then injected them into the brains of susceptible mice.

The mice began exhibiting signs of disease in their central nervous systems between 380 and 660 days after the injections. The amyloid form of the prion protein, which is thought to cause prion disease, was also found in the brains of the diseased mice.

Unlike viruses, bacteria, fungi and parasites, prions contain no DNA or RNA.

Instead, they are a type of protein normally found within cells in humans and other organisms. In some cases the structure of prions can change into a folded, disease-causing form. These abnormal proteins appear to convert other, normal prions to the abnormal shape.

Many scientists believe this conversion process leads to several dementing diseases in humans, including Creutzfeldt-Jakob disease. Similar diseases in animals include mad cow disease in cattle and scrapie in sheep. Misfolded proteins also contribute to other age-related neurological diseases such as Alzheimer's and Parkinson's diseases.