Faculty Bibliography

Neuronal circuits involved in left-right coordination are a fundamental feature of rhythmic locomotor movements. These circuits necessarily include commissural interneurons (CINs) that have axons crossing the midline of the spinal cord. The properties of CINs have been described in some detail in the spinal cords of a number of aquatic vertebrates including the Xenopus tadpole and the lamprey. However, their function in left-right coordination of limb movements in mammals is poorly understood. In this review we describe the present understanding of commissural pathways in the functioning of spinal cord central pattern generators (CPGs). The means by which reciprocal inhibition and integration of sensory information are maintained in swimming vertebrates is described, with similarities between the three basic populations of commissural interneurons highlighted. The subsequent section concentrates on recent evidence from mammalian limbed preparations and specifically the isolated spinal cord of the neonatal rat. Studies into the role of CPG elements during drug-induced locomotor-like activity have afforded a better understanding of the location of commissural pathways, such that it is now possible, using whole cell patch clamp, to record from anatomically defined CINs located in the rhythm-generating region of the lumbar segments. Initial results would suggest that the firing pattern of these neurons shows a greater diversity than that previously described in swimming central pattern generators. Spinal CINs play an important role in the generation of locomotor output. Increased knowledge as to their function in producing locomotion is likely to provide valuable insights into the spinal networks required for postural control and walking.

Federal health officials issued their most comprehensive plan for containing an outbreak of smallpox in the event of a bioterrorist attack

In releasing their most comprehensive smallpox preparedness plan to date, officials at the federal Centers for Disease Control and Prevention said publicly for the first time that even one case of smallpox might result in a nationwide program of voluntary vaccinations. That is in part because even a single case could be a harbinger of a larger outbreak and in part because even one case would undoubtedly spark panic and a clamor for vaccine. The new document does not supplant the ''ring vaccination'' plan, Dr. [Julie Gerberding] said. But Dr. Bill Bicknell, a professor of international health at Boston University critical of that strategy, said the guide was undoubtedly influenced by recent studies showing that ring vaccination would not contain a large outbreak. He said studies had found that if 1,000 people were infected in a large city like New York and ring vaccination were used, within three months there would be 300,000 cases of smallpox and 100,000 deaths and the epidemic would not be contained. But mass vaccination, he said, would contain such an epidemic in 40 to 45 days, with 1,500 cases and 500 deaths. Federal officials began building a smallpox vaccine stockpile after last year's anthrax attacks. Mr. [Tommy G. Thompson], the health secretary, signed contracts with two companies to buy 209 million doses to add to the existing stockpile of vaccine, some of which dates to the 1950's. In the interim, studies have shown that the existing stockpile could be diluted

Because the vaccine is classified as ''investigational'' permission is required from any patient before receiving it. In the event mass vaccinations are offered, Dr. [Julie L. Gerberding] said, the C.D.C. has prepared a videotape in which she explains the risks and benefits of the vaccine with the hope that the tape will ease the permission process

Dr. [James E. Darnell] helped scientists understand that genes could work differently in bacteria from the way they work in animals and plants. He later discovered a simple path by which cells of mammals transmit signals from the environment to the nucleus. The process helps cells program their genes to respond to signals from their environment. For example, Dr. Darnell discovered in the 1980's that a liver cell could remain a liver cell only when it stayed in the liver. He found that without constant signals from their normal place in the organ, liver cells lost a crucial molecular component known as messenger RNA that helps give them their identity. Dr. Darnell also found the clearest example of how the surface of a cell signals genes in its nucleus. The signaling shows how cells directly respond to a type of hormone known as cytokines and to growth factors. The signaling is important in resisting infections and in inducing production of proteins known as STAT's, which play major roles in the origin and survival of cancer cells