Evaluation of an independent prestin mouse model derived from the 129S1 strain.

Studies using the prestin knockout mouse indicate that removal of the outer hair cell (OHC) motor protein is associated with loss of sensitivity, frequency selectivity and somatic electromotility. Here we provide data obtained from another prestin mouse model that was produced commercially. In vivo electrical recordings from the round window indicate that the phenotype is similar to that of the original knockout generated by the Zuo group at St. Jude Children's Research Hospital. Hence, compound action potential (CAP) thresholds are shifted in a frequency-dependent manner and CAP tuning curves at 12 kHz are flat for masker frequencies between 3 and 18 kHz. Although CAP input-output functions at 6 kHz show a shift in sensitivity at low levels, responses approach wild-type magnitudes at high levels where the cochlear amplifier has less influence. In order to confirm that the loss of sensitivity and frequency selectivity is due to loss of prestin, we performed immunohistochemistry using a prestin antibody. Cochlear segments from homozygous mutant mice showed no fluorescence, while wild-type mice displayed a fluorescent signal targeted to the OHC's lateral membrane. Absence of prestin protein was confirmed using LDS-PAGE/Western blot analysis. These results indicate that the loss of function phenotype is associated with loss of prestin protein. Lack of prestin protein also results in a shortening of OHC length to approximately 60% of wild-type, similar to that reported previously by Liberman's group. The linkage shown between the loss of prestin protein and abnormal cochlear function validates the original knockout and attests to the importance of OHC motor function in the auditory periphery.

The development of a community breast center.

Maximum capacity for mammography has been reached at Kaweah Delta Health Care District Imaging Center. Increased need and support in the community for access to care was a driving force in development of a Breast Center. What follows is a case study of implementing a Breast Center in a semi-rural community in Central California, which involves a collaborative effort between Cancer Program and Imaging Services.

The development of a community breast center.

Maximum capacity for mammography services had been reached at the Kaweah Delta Health Care District, a 504-bed, multicampus hospital district in Visalia, Calif., so the community supported the idea of better and easier access to cancer care. Kaweah Delta Foundation, the hospital's development arm, helped raise funds for a new community breast center after hearing from local women that they disliked traveling to Los Angeles or San Francisco for state-of-the-art technology in diagnosis. They also requested better education and quicker exam results. The new Center was the result of a collaborative effort between imaging services and the cancer care program at Kaweah Delta. A nearby hospital, with more space for parking and room to offer an education program, became the site of the new Center. New equipment that met MQSA guidelines was purchased. An architectural firm designed a layout for patient comfort and privacy and efficient throughput for high volume work. The purchase of a second mammography unit allowed the Center to offer same-day and next-day appointments, which increased both physician and patient satisfaction. Consultation services with a radiologist are now offered. An education program that includes group support meetings and referrals to an oncology clinical nurse specialist are also offered. A new mobile mammography unit, housed at a newly acquired hospital 13 miles away, serves the needs of women in the two-county rural area who have no transportation. With careful planning and collaboration, the volume of mammography services has doubled in a year. Customer service ratings have soared.

Morphology of the unfixed cochlea.

Our knowledge of cochlear geometry is based largely upon anatomical observations derived from fixed, dehydrated, embedded and/or sputter-coated material. We have now developed a novel preparation, the hemicochlea, where for the first time living cochlear structures can be observed in situ and from a radial perspective. The experiments were performed on the Mongolian gerbil. Ion substitution experiments suggest that no significant swelling or shrinkage occurs when the preparation is bathed in normal culture medium, so long as calcium concentration is kept at endolymph-like (20 microM) levels. The tectorial membrane-reticular lamina relationship appears to remain well preserved. Hensen's stripe maintains a close relationship with the inner hair cell stereociliary bundle, unless the mechanical coupling becomes disturbed. In addition, standard fixation and/or dehydration procedures are used to quantify changes due to shrinkage artifacts. Various morphometric gradients are examined in unfixed specimens from apical, middle, and basal turns.

Continuing education at reasonable cost: a case study.

Since January 1, 1995, the American Registry of Radiologic Technologists (ARRT) has mandated that radiologic technologists earn 24 units of continuing education every 24 months. Enforcement will begin in 1997, but the credits must be earned in the two-year period preceding the technologist's birth-month in 1997. Those who have earned 24 credits between their birth-months in 1993 and 1995 will be recognized for voluntary compliance. This article describes how a local affiliate of the California Society of Radiologic Technologists and a hospital in-service program provide continuing education for technologists in a semi-rural area. In 1986 two technologists from Kaweah Delta Hospital organized the Sequoia District Study Group (now called Sequoia District Affiliate). In 1992 that group recognized the need to meet upcoming continuing education requirements and made plans to provide 12 continuing education units per year. The Kaweah Health Care District offers financial support of the group's program and pays an annual fee to the ASRT to receive designated providership of continuing education. Individuals who pay a small annual membership fee to the Sequoia District Affiliate attend meetings for free and receive a discount on registration for an annual seminar. Staff involvement in soliciting speakers generates greater interest and better attendance. Cooperation between staff and management can facilitate the implementation of a low-cost education program that meets ARRT requirements.