To you the reader, the joy of discovery begins, for We continue in our goal of providing a text which us the job is done. In this edition, we have corrected is useful, not only to the clinician, but of equal interest past deficiencies, added new topics, expanded infor- to the investigator. The selection of content has been mation regarding the pediatric age group, provided directed at topics of current interest rather than those up to date (March 2003) references, while remaining of histor...