This continuing series gathers and presents original research results on the leading edge of medicine and biology. Each article has been carefully selected in an attempt to present substantial topical data across a broad spectrum. Topics discussed include the study of ceramics in biomedical research applications; HtrA as a chaperone and protease in bacterial pathogenesis; the role of the unfolded protein response in cell physiology, inflammation, hepatic disease, and renal transplantation; stroke prevention after cardiac surgery; recent developments in total hip arthroplasty; the effect of sonar on human hearing and fracture fixation in orthopedic trauma surgery.