Built in 1978, strategically located at the center of the Health Sciences Region on the campus of the University of California, San Diego, the Medical Teaching Facility vivarium includes 26 mouse housing rooms capable of holding 69 racks and over 11,000 boxes of research mice. Funds are requested to purchase an innovative new housing system comprised of high-density individually ventilated disposable/recyclable cages. The proposed housing expansion will enable established and newly recruited faculty to conduct seminal studies in cardiology, gastroenterology, respiratory physiology and neurobiology. Discoveries in these areas will advance the prevention and safe treatment of important human diseases such as Alzheimer's and myocardial infarction. Top goals for the Animal Care and Use Program at UCSD are to maximize successful research, optimize animal well being, and ensure human health. We are now focusing on upgrading mouse housing systems at "conventional-type" facilities used in highly interactive PHS funded experiments. Our specific aims are to 1) expand mouse housing capacity at the centrally located MTF facility, 2) improve the health of mice by improving the primary housing environment and minimizing exposure to pathogens, and 3) reduce the need for mouse caging sanitation facilities and the associated natural resources within the MTF. To address these aims we are requesting 42 of the 69 high density individually ventilated mouse housing racks that are needed to support critical research on animals sensitive to relatively minor changes in associated microflora. The University will provide the remaining 27 racks as funds become available.