Fw: News release from UT Southwestern, January 24, 2001

[Guest guest]

Martha Murdock, Director

National Silicone Implant Foundation

Dallas, Texas Headquarters

-----Original Message-----

From: Robin Amerine <Robin.Amerine@...>

UTSWNEWS@... <UTSWNEWS@...>

Date: Wednesday, January 24, 2001 4:04 PM

Subject: News release from UT Southwestern, January 24, 2001

Media Contact: Cofer

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PROTEIN LINKED TO 'MIRROR MOVEMENT' DISORDER; RESEARCH PROVIDES INSIGHT INTO

BRAIN/SPINAL CORD CONNECTION

DALLAS - Jan. 25, 2001 - A UT Southwestern Medical Center at Dallas

researcher has found that mutated mice bred without an essential protein

exhibit symptoms of a rare disorder that causes involuntary " mirror

movement " in people.

The findings, published in the January issue of Neuron,

demonstrate the importance of the protein ephrin-B3 in making the connection

between the brain and the spinal cord.

Dr. Mark Henkemeyer, assistant professor in the Center for Developmental

Biology, said the findings should help researchers understand how the brain

forms its axonal connections with the spinal cord. Such knowledge could

someday prove helpful in the regeneration of nerves in people with

spinal-cord injuries. More immediately, the research elucidates how the

brain becomes " hard-wired " to the spinal cord.

First described in 1889, mirror-movement disorder is characterized by an

involuntary symmetrical movement of limbs. For example, when people with the

disorder move their right hand, their left hand involuntarily moves with it.

Typically, they cannot perform complex activities like tying shoes and

typing, and even running and walking can be difficult. Mirror movement is

natural in infants, but over time people normally develop the motor

coordination to control their limbs and digits more independently.

Researchers have believed for some time that mirror movement is caused by

defects in the corticospinal tract, which connects the brain's cortex with

motor neurons and interneurons in the spinal cord. Playing pivotal roles in

forming these connections are ephrins, which regulate cortical nerve growth

to help form their proper circuits with the spinal cord.

" Ephrin-B3 is a very important molecule as it is expressed down the middle

of the spinal column, " Henkemeyer said. " It serves as a repulsive barrier

that keeps the left axons on the left side of the nervous system and the

right axons on the right. "

The mice used in the study were genetically engineered to

completely lack ephrin-B3 protein, which caused each side of the motor

cortex to connect to both sides of the spinal cord. These mice display a

kangaroo-like hopping gait involving both their forelimbs and hind limbs. In

addition to such unusual locomotion, other mirror movements are evident,

such as when the mutant mice groom themselves and swim.

Henkemeyer's research was funded by the Reeve National Paralysis

Foundation, the Muscular Dystrophy Association and the National Institutes

of Health.

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This news release is available on our World Wide Web home page at

http://www.utsouthwestern.edu/home_pages/news/