Transplant Procedure Helps Restore Sight
Giving new hope to people blinded by fire, chemical burns or certain illnesses, doctors are restoring victims' sight by transplanting special tissue-making cells into the eye.
The procedure, pioneered a decade ago but refined since then, cannot help people who were born blind or lost their sight because of nerve or retina damage. It is only for patients who are legally blind but can still sense light.
In the first long-term study of the procedure, Japanese researchers restored sight to half of the eyes on which they performed surgery, though some needed as many as four operations.
From 1992 through 1996, the Japanese doctors did 70 transplant operations on 43 eyes in 39 patients who had become legally blind in one or both eyes, meaning they could, at best, count fingers held up in front of them. The patients' blindness was caused by heat or chemical burns, blistering from a severe reaction to medication, or an eye-attacking immune disorder that afflicts the elderly. Tens of thousands of Americans are legally blind for these reasons.
Surgeons first removed the damaged eye surface, then sewed on tissue from an eye bank: a new cornea, if necessary, and tissue that rings the cornea and is called the limbus.
After an average of 39 months, the transplanted tissue was still generating epithelium in 51 percent of the patients. Their vision improved, on average, from only being able to distinguish motion or count fingers to being able to read the top letter on an eye chart from about 3 feet away.
Disappointment In AIDS Fight
Several people in Australia who caught a weakened form of HIV in the early 1980s are beginning to show AIDS-like damage to their immune systems, a development that has disappointing implications for the development of a vaccine.
Between 1980 and 1984, 13 people in Australia received blood donated by an HIV-infected man, and eight of them caught the virus. When none got sick, researchers analyzed the virus and found that it was missing a working copy of a gene called nef, which boosts HIV reproduction.
Over the years, three of the infected people died of other causes, and none has gotten AIDS. Some researchers had hoped that a vaccine modeled on this weak virus could be an effective AIDS vaccine, protecting people for life without making them sick. The idea would be to create a vaccine using a weakened version of HIV that is missing nef and probably other genes, as well.
However, of the donor and five surviving transfusion recipients, three have falling levels of helper T cells, a hallmark of AIDS damage, according to a report in today's New England Journal of Medicine. In January, the donor whose blood infected the others began taking AIDS drugs because of his low blood count.
New Drug May Aid Marrow Transplants
A new, highly selective immune-suppressing drug may allow cancer victims to receive bone marrow transplants from poorly matched donors without suffering life-threatening complications.
The drug suppresses only that part of the immune system that causes these complications. Doctors say this could allow patients to receive marrow transplants without the need for drugs that broadly suppress the body's immune defenses. These broad drugs raise the risk of infections and other health problems.
In today's New England Journal of Medicine, researchers reported that the approach worked surprisingly well in the first experimental use on terminally ill cancer patients. They predicted it may also make it easier to transplant hearts, kidneys and other organs.
The new treatment, called CTLA4-Ig, blocks development of a dangerous complication called graft versus host disease, which occurs when foreign tissue is placed in the body. The drug stops only the category of white blood cells that promote this response, leaving intact the rest of the immune function of the newly transferred marrow. Doctors treat the donated marrow with CTLA4-Ig outside the body before transplanting it.
Doctors tested the approach on 12 young victims of advanced leukemia for whom only poorly matched marrow was available. No severe graft versus host disease occurred. Five have survived for five to 29 months, while the rest died of treatment complications and cancer relapse.