Ripples from last week's terrorist attacks on the East Coast were felt throughout Stanford University Medical Center, reflecting both the best and worst in human nature.

Among the bright spots was the overwhelming desire of Bay Area residents to donate blood to aid victims of the attacks. To ensure that there is an ongoing, adequate supply of blood products in the months ahead, officials at Stanford Blood Center are encouraging potential donors to 30 days.

Donors must wait 56 days between donations and blood has a shelf life of only 35 days. That means there is a gap between the time when the blood donated last week will expire and when those donors will be able to make another donation. "We're trying to prevent what happened after the '89 earthquake, when 35 days after the earthquake we had a critical shortage because everyone had donated already," said Vince Yalon, administrator of the Stanford Blood Center.

The blood center shipped several hundred units of blood to its affiliate in Sacramento, which sent 500 units to New York.

On the grimmer side, the terrorist attacks and resulting stoppage of the nation's airlines disrupted plans for a liver transplant for a 10-year-old girl at Lucile Packard Children's Hospital.

A donated liver for the girl was to be flown to Stanford from New Mexico the morning of the attacks, but the plane that was to deliver the organ could not take off because of the air stoppage.

The patient was scheduled to undergo a transplant yesterday afternoon at Packard with a different liver.

Tensions in the wake of the disasters were heightened Thursday when Stanford and Packard hospitals were partially after a threatening call.

An unidentified man phoned Stanford Hospital at about 10:30 a.m. and indicated that a bomb was set to explode in its emergency room ­ or at the children's hospital ­ in an hour, said Detective Lori Kratzer of the Palo Alto Police Department.

The bomb squad of the Santa Clara County Sheriff's Department searched the emergency room area and the first two floors of Packard hospital after most patients in those sections had been evacuated, Kratzer said.

No bomb was discovered, but hundreds of people ­ including visitors, nurses, doctors and patients ­ were affected by the threat, Kratzer said. Traffic on roads leading to the hospitals was diverted, and the incident kept police and other emergency officials tied up for about three hours.

The buildings were reopened around 2 p.m.

"It's unthinkable that someone could do this at this time," Kratzer said, referring to the attacks in the East Coast. She acknowledged that the response to the hospital threat was unusually extensive in light of those twin disasters.

"If we find out who made this call, we will seek criminal prosecution," she added.

Despite the disruption caused by the evacuations, the chaplaincy offices of the two hospitals proceeded with a "moment of silence" observance at 3 p.m. Thursday to honor victims of the tragedies. The ceremonies took place in the Stanford Hospital atrium and the rainbow garden at Packard Children's Hospital.