Handle with care. Schizophrenia, a chronic, severe, and disabling disease of the brain, affects more than two million Americans in any given year, just over one percent of the population. While genetic vulnerability is known to be a risk factor, recent studies of twins, including studies by Cassandra Smith, an ENG professor of biomedical engineering, point to the interplay of genetic and nongenetic factors such as environmental stresses during fetal development as possible key forces in the development of the disease.
Over the course of many years, Smith has studied the DNA of identical (monozygotic) twins, and discovered minor but significant differences in their genomes. In a recent study she specifically looked for DNA differences relevant to schizophrenia. She examined the DNA of 12 pairs of twins and 18 unrelated pairs of siblings. Among the twins, eight pairs were affected by schizophrenia, four concordantly (both twins had the disease), and four discordantly (only one twin was ill).
Smith developed genetic profiles of the subjects, using a method developed in her laboratory known as targeted genomic differential display (TGDD). It allows multiple occurrences of a variety of DNA sequences to be compared. In this case, repeated sequences of the base pairs’ CAG (cytosine, adenine, and guanine) were examined. The researchers also compared “fragile sites,” areas on the chromosomes that have been identified as especially prone to breaking under adverse conditions.
The profiles of the discordant pairs of twins revealed significantly more genomic differences than did the concordant pairs. Also, the data established a link between the chromosomal abnormalities associated with schizophrenia and fragile site locations.
Smith speculates that overall genome instability, especially expressed at fragile sites, is associated with schizophrenia. She suspects that there may be a window of susceptibility during embryonic brain development during which stresses at fragile sites can produce genetic abnormalities associated with schizophrenia. She notes that cancer is also associated with genetic instability at fragile sites, and proposes that similar mechanisms may be at work.
Smith’s study will be published in an upcoming issue of the American Journal of Medical Genetics.
Pint-sized pain. Most people are well aware of the perils of working at a computer workstation that is not set up to accommodate the user’s needs. Incorrect positioning of keyboard, monitor, or mouse can result over time in serious neck and back problems and repetitive stress injuries such as carpal tunnel syndrome. But in most cases, people do not realize the serious consequences to children’s health of computers that are improperly set up, according to Karen Jacobs, a clinical professor of occupational therapy in Sargent College’s department of rehabilitation sciences.
More and more children are using computers, and at earlier ages — as young as age two in some cases. The U.S. Census Bureau estimates that more than 30 million elementary school children in the United States have computers in their home, and almost all children are spending more time using a computer in school. In a recent three-year longitudinal study of students in the sixth and seventh grades, Jacobs found that nearly half of the participants reported computer-related musculoskeletal discomfort or pain after working on a computer. “This preliminary study raises many questions about children and computer use,” she says. “Children may be at an even greater risk because computers and computer accessories are designed largely for adults. Unless we learn more, and make appropriate adaptations, these children could become the next generation of walking wounded.”
In the interim, Jacob advises parents to buy or create child-sized computer furniture and accessories. Among the items now available are child-sized desks, adjustable keyboard trays and chairs, and kid-sized keyboards and mice. Since children grow quickly, look for items that have a large range of adjustable features. And, she stresses, parents should put the workstation where they can see it, so they can keep track of how long their children have been sitting. Enforcing a two-minute break every half hour or so is crucial to avoid big problems for small bodies, Jacobs says.
This work was reported at the 2002 Annual International Occupational Ergonomics and Safety Conference.
Briefs" is written by Joan Schwartz in the Office of the Provost. To read
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