Attentive readers of the bylines that follow most TIME stories have probably noticed that occasionally the name of a reporter contributing to a story is not on the masthead at the front of the magazine. The reason is that the name belongs to a "stringer," one of the more than 300 mostly part-time reporters across the U.S. and round the world who supplement the work of TIME'S corps of correspondents. They usually serve in cities, or even countries, where the magazine has no news bureaus. Often they are staff journalists with news agencies or local newspapers. Some are freelancers, working for several publications or primarily for TIME. The name stringer derives from the old and long-abandoned practice of paying freelance reporters according to the length of their pasted-together columns, or strings, of clippings. Today stringers are paid by the hour or the day or in some cases under a long-term contract.

The bylines for this week's Medicine cover story on the dangers and mysteries of cholesterol include those of Associate Editor Claudia Wallis, who wrote the story, and Washington Correspondent Patricia Delaney; other contributions came from Correspondents Dick Thompson and Elizabeth Taylor and Reporter-Researcher Mary Carpenter. The credits also include the names of two stringers: Chicago's Sheila Gribben, a 6 1/2-year general-assignment veteran, and Los Angeles' Cheryl Crooks, a stringer for the past five years. Another stringer who helped report the story was Houston's Lianne Hart.

For this story, Gribben sought out experts at the University of Cincinnati Lipid Research Clinic, interviewed food-industry spokesmen and talked to Milwaukee doctors studying heart-disease risk factors such as smoking and job-related stress. Crooks interviewed scientists at universities and medical centers, spoke with teachers participating in a health-improvement scheme and talked to National Institutes of Health researchers about the amazing Pima Indians, who have very low heart-attack rates. Since last year, when she covered the progress of Artificial Heart Recipient Barney Clark for TIME, Crooks has become something of an expert on medical subjects, although her degree from Arizona State in 1977 is in music history. "Medical reporting is exciting," she says. "There are still so many questions about cholesterol requiring proven answers. But things change so fast. When I go to the medical dictionary to check a word's spelling, it often isn't even in there yet. And I've just come from talking with the people who are helping to write that word's very definition."