Walking and biking to school can be an important part of a healthy lifestyle, yet most US children do not start their day with these activities. The Safe Routes to School Program in Marin County, California, is working to promote walking and biking to school. Using a multipronged approach, the program identifies and creates safe routes to schools and invites communitywide involvement. By its second year, the program was serving 4665 students in 15 schools. Participating public schools reported an increase in school trips made by walking (64%), biking (114%), and carpooling (91%) and a decrease in trips by private vehicles carrying only one student (39%).

Previous work based on the relative tissue content of glucose-6-phosphate dehydrogenase isoenzymes suggested that parathyroid adenomas, like primary hyperplasia, may be multicellular (not clonal) in origin. We have reexamined this issue by using two independent molecular genetic methods. We report tumor-cell-specific restriction-fragment-length alterations involving the parathyroid hormone gene from two human parathyroid adenomas. These abnormal restriction fragments indicate that in each case a clonal proliferation of cells was present and also suggest that DNA alterations involving the parathyroid hormone locus may be important in the tumorigenesis or clonal evolution of some parathyroid adenomas. In addition, we used a restriction-fragment-length polymorphism in an X-linked gene (hypoxanthine phosphoribosyltransferase) to examine the clonality of eight parathyroid adenomas in women. Of these eight adenomas, six had the DNA hybridization pattern of monoclonality, and two had an equivocal pattern. None of five hyperplastic parathyroid glands had a monoclonal pattern. We conclude that some (and perhaps many) single parathyroid adenomas are monoclonal neoplasms. Our observations suggest that there is a fundamental biologic difference between parathyroid adenomas and primary hyperplasia--a difference that could prove useful in distinguishing these entities clinically.

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