Time-dependent changes in spontaneous respiratory activity in turtle brainstems in vitro

Our goal was to determine whether time-dependent changes in respiratory motor output in vitro could be minimized by altering bath solution composition. Adult turtle brainstems were bathed in standard solution, nutrient-rich Dulbecco's Eagle media (100 or 25% concentration), or standard solution with phenylbiguanide (PBG, 5-HT3 agonist which increases respiratory drive). Except for a 63% frequency increase in PBG solution, hypoglossal bursts were unaltered within 100 min of observation. Respiratory activity was abolished within 7 h in 100% Dulbecco's compared with a mean of 24-31 h in other test solutions. At 12 h, burst frequency decreased faster in standard solution and 25% Dulbecco's (-0.28+/-0.07 and -0.13+/-0.05 bursts/h, respectively) compared with PBG solution (-0.09+/-0.04 bursts/h); amplitude declined at approximately 2%/h in all solutions. The tendency for episodic discharge decreased gradually in standard solution, but was eliminated in 25% Dulbecco's and PBG solution. Certain bath solutions may minimize time-dependent frequency reductions but may also cause breathing pattern changes.     

Emergence of a new neotropical malaria vector facilitated by human migration and changes in land use

In a region of northeastern Amazonia, we find a species previously of minor importance, Anopheles marajoara, to be the principal malaria vector. In a total of five collections during 1996-97 in three replicated sites near the city of Macapá, Amapá state, this species occurs in much greater abundance compared with the presumed vector Anopheles darlingi. Also, a significantly higher proportion of An. marajoara is infected with malaria parasites, determined by the ELISA technique. This appears to be the result of increased abundance of An. marajoara due to alterations in land use, invasion of its primary breeding sites by human immigrants, and its anthropophilic behavior. This discovery highlights one of the challenges of Neotropical malaria control, namely that the targeting of specific vectors may be complicated by a changing mosaic of different locally important vectors and their interactions with human populations.     

Fluoroscopy-assisted dual-catheter thromboembolectomy: a new technique useful in patients with embolization to arteries of disproportionate diameters

Distal embolization is a complication of aortoiliac aneurysm repair. Fluoroscopy-assisted catheter thromboembolectomy is useful in removing popliteal and tibial emboli from the femoral approach. Concomitant presence of aortoiliac and popliteal aneurysms, a known association, may present a difficult challenge to embolus extraction. Currently available embolectomy catheters large enough for thrombus extraction from a popliteal aneurysm are too large for safe tibial artery cannulation, and tibial balloon catheters cannot be enlarged sufficiently to transfer the thrombus through the aneurysmal popliteal segment. We treated a patient who embolized to his popliteal aneurysm and distal tibial circulation following aortoiliac aneurysm repair. A fluoroscopy-assisted dual-catheter technique was used to extract the thrombus through the femoral approach, eliminating the need for direct popliteal or tibial exploration. This technique uses two balloon catheters of graduated size, maneuvered concurrently under fluoroscopic guidance into the tibial and popliteal circulation. The smaller tibial catheter is inflated, and thrombus is withdrawn into the popliteal segment. The larger popliteal balloon catheter is then inflated distal to the smaller catheter, and both catheters are withdrawn simultaneously to deliver the clot through the femoral arteriotomy. This technique can be useful for successful balloon catheter extraction of thrombus via remote access, in an arterial system with variable diameter, eliminating the need for direct popliteal or tibial exploration.     

Charles W. Dohner,PhD: an evaluator and mentor in medical education

As one of the first generation medical education pioneers, Charles W. Dohner, PhD established the ninth office of medical education at the University of Washington (UW) where he served as chairman from 1967–1996. With a background in education and measurement, he focused his work on evaluation of educational programs and faculty development. The Department of Medical Education went through three distinct stages of development: path finding 1967–1972 focused on developing working relationships with the faculty and clarifying identity, integration into academic affairs 1972–1980, and direct leadership by department faculty 1980–1996. Dohner helped to create and evaluate the WAMI program, a regional medical education program for the states of Washington, Alaska, Montana, and Idaho. He served as a consultant to aspecialty board, the founding president of the Society of Directors of Research in Medical Education, and a frequent consultant in international medical education. Dohner identified three important innovations in medical education: educators in academic medicine, simulations and performance assessment, and community-based medical education. Success factors for professional education include technical competence in education, interpersonal communication and collaboration skills, a plan for personal growth, and use of mentors. Future trends in medical education will involve information technology, professionalism, wellness and complementary medicine, and performance assessment. He has been a passionate spokesman for excellence in medical education and most noted for his roles as an evaluator, program developer, and mentor of academic leaders.This revised version was published online in October 2005 with corrections to the Cover Date.     

Exogenous lung surfactant: effect on radiographic appearance in premature infants

At birth, premature infants of 25-29 weeks gestation, at high risk for development of neonatal respiratory distress syndrome (RDS), were given a single dose (90 mg) of calf lung surfactant extract (CLSE) by intratracheal instillation. The frequency and severity of RDS were assessed with use of a simple radiographic scoring system in which pulmonary parenchymal densities and the prominence of the air-bronchogram effect were used as indicators of widespread atelectasis. Radiographs were obtained in surfactant-treated and control infants within the first 90 minutes of life as part of an initial evaluation of their pulmonary status. Subsequent examinations were performed at less than 24 hours and less than 48 hours of age. Radiographic assessment of lung disease compared consistently with coordinated data on oxygen and mean airway pressure requirements of the infants. Both indicated a significantly decreased frequency and severity of RDS in the infants treated with surfactant. The results provide supporting evidence of the effectiveness of exogenous lung surfactant replacement in mitigating RDS in very premature infants.     

Thrombosis at venous insertion sites after inferior vena caval filter placement

Color Doppler flow imaging or compression ultrasound (US) was used to prospectively determine frequency of thrombosis at 54 venous insertion sites (47 in common femoral veins, seven in right internal jugular veins) after percutaneous placement of Greenfield filters for interruption of the inferior vena cava. Fifty-one filters were successfully placed in 51 patients with a dilator set or a balloon angioplasty catheter. Nine focal thrombi were detected in the common femoral vein (19%) and one in the right internal jugular vein (14%). Use of dilators induced eight thrombi (24%), compared with two (10%) from balloon catheters. The left common femoral vein had a high frequency of thrombosis, regardless of dilation technique (five of nine). Of nine patients with acute common femoral vein thrombosis, four became symptomatic within 10 days after the procedure. Patients may remain asymptomatic or have delayed symptoms; thus, US is valuable for determining patients at risk of thrombosis of the common femoral vein.