WHIPPANY, N.J. — Jay Feinberg, the 26-year-old resident of New Jersey who underwent a bone marrow transplant late last month, appears to be doing well, according to the Fred Hutchinson Cancer Research Center in Seattle, where the operation took place.

"Everyone is extremely hopeful," said a representative of Friends of Jay, an organization that began the search to find a suitable donor for the leukemia patient. "He's getting the best care available."

A full analysis of Feinberg's condition will take several weeks.

Jacob Feinberg, his father, said his son's vital signs are positive.

In 50 percent of transplant patients, the marrow rejects the patient by attacking major organs such as the skin, liver and gut. The reaction, called graft-vs.-host disease, is usually apparent within two to three weeks of the transplant.

The marrow extracted from Feinberg's miracle match was transported to the research center from the donor's hometown and transplanted into Feinberg's chest July 28.

The Feinbergs have spoken with the donor, a woman from Chicago, but wish to keep her identity concealed.

Feinberg's match came after a four-year worldwide search for a donor; through the Friends of Jay organization, 55,000 people were screened. Their results will stay on file with the National Marrow Donor Program, headquartered in Minneapolis.

According to the Hutchinson center, only 14 percent of those searching for an unrelated donor find a match.

"The support we've received from communities [internationally] has been unbelievable," said Arlene Feinberg, Jay's mother. "I can't begin to express our gratitude. We're speechless. Words seem so inadequate, they can't express how we feel."