Johns Hopkins Gazette: February 10, 1997

In Brief:
Medical News

Reducing nitric oxide may lessen brain injury risk

A drug that stops overproduction of nitric oxide may reduce the risk of brain damage during heart surgery, a Johns Hopkins animal study suggests.

Results show that apoptosis--the self-destruction of cells-- is widespread in hypothermic circulatory arrest, when body temperature is lowered, the heart stopped and a heart-lung bypass machine employed. An excess of nitric oxide apparently plays a significant role in brain cell damage that occurs in some of these cases.

Prolonged hypothermic circulatory arrest may increase the risk of brain damage, resulting in learning and memory problems and involuntary movements.

"Our findings suggest that strategies to protect the brain during hypothermic circulatory arrest may include preventing runaway production of nitric oxide," said Elaine Tseng, the study's lead author and a surgery fellow.

Results of the study were presented Feb. 3 at the Society of Thoracic Surgeons' annual meeting in San Diego.

Two disorders reveal new complexities in genes

School of Medicine researchers studying the genetic changes underlying some cancers and genetic disorders have shown how a single gene can play a role in two very different inherited disorders, a heart rhythm disturbance and a rare growth ailment.

The key is a genetic phenomenon called imprinting which selectively silences one of the two copies of a gene that every person receives--either the copy from their father or the copy from their mother.

In a paper in this month's Nature Genetics, Maxwell Lee, an instructor of medicine, and Andrew Feinberg, King Fahd Professor of Medicine, report on imprinting and the gene KVLQT-1, identified by another research group and linked to an inherited disorder of the heartbeat, long Q-T syndrome.

They found new connections between KVLQT-1 and Beckwith-Weidemann syndrome, a genetic imprinting disorder. Babies born with BWS are unusually large, have differences in tongue and ear formation and are at an increased risk for childhood tumors.

"We found that KVLQT-1 is imprinted nearly everywhere you look in the body," Feinberg said, "but it's usually not imprinted in the cells of the heart."

This selective imprinting may explain why changes to the gene have one effect in the heart and another elsewhere in the body, he said.

Imprinting errors can lead to unchecked growth and possibly to cancer. Normally, though, imprinting helps the body differently use the maternal and paternal copies of genes.

The study revealed that KVLQT-1 is found in the same area of chromosome 11 and contains many BWS "breakpoints," spots where gene damage linked to BWS often occurs. It's possible, Feinberg noted, that all four genes are imprinted in some coordinated fashion.

"We have several genes that can be part of a disease, and they're probably therefore part of the same genetic or biochemical pathway," Feinberg said.

Other News

Hubble repair mission will be available for viewing

The Hopkins community and the general public may view this week's Hubble Space Telescope repair mission live in the Schafler Auditorium at the Bloomberg Center for Physics and Astronomy.

Astronauts and scientists will upgrade the Hubble Space Telescope, installing two new instruments, the Space Telescope Imaging Spectrograph and the Near Infrared Camera and Multi-Object Spectrograph.

Hopkins astronomers Warren Moos and Mary Beth Kaiser are members of the STIS "instrument definition team," which provided guidelines about how to gauge the instrument's scientific capabilities.

The astronauts will remove and replace various components in space walks. Live mission coverage, provided by the Maryland Space Grant Consortium, is scheduled at Schafler on the following days and times:

  • From 2 to 6 a.m. on Tuesday and Thursday

  • From 11 p.m. Thursday to 5 a.m. on Friday

  • From 11 p.m. Friday to 5 a.m. on Saturday

  • From 11 p.m. Saturday to 5 a.m. on Sunday

  • From 11 p.m. Sunday to 5 a.m. on Monday

  • From midnight next Monday to 4 a.m. on Tuesday

  • From 2 to 6 a.m. on Friday, Feb. 21, for the shuttle landing at Kennedy Space Center

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