Reproductive status of western mosquitofish inhabiting selenium-contaminated waters in the Grassland water district, Merced county, California.

This study was implemented to determine if western mosquitofish (Gambusia affinis) populations in the Grassland Water District suffer from impaired reproduction because of seleniferous inflows of agricultural drainwater from the Grassland Bypass Project. During June to July 2001, laboratory trials with pregnant female fish collected from two seleniferous treatment sites exposed to selenium-laden drainwater and two nonseleniferous reference sites yielded fry that averaged > 96% survival at birth. In addition, none of the newborn fry exhibited evidence of teratogenesis, a typical consequence of selenium toxicity. Chemical analysis of postpartum female fish and their newborn fry indicated that mosquitofish from seleniferous sites accumulated relatively high body burdens of selenium (3.96 to 17.5 microg selenium/g in postpartum female fish and 5.35 to 29.2 microg selenium/g in their fry), whereas those from nonseleniferous sites contained lower body burdens (0.40 to 2.72 microg selenium/g in postpartum female fish and 0.61 to 4.68 microg selenium/g in their fry). Collectively, these results strongly suggest that mosquitofish inhabiting selenium-contaminated waters are not experiencing adverse reproductive effects at current levels of selenium exposure.

Cortical, auditory, evoked potentials in response to changes of spectrum and amplitude.

The acoustic change complex (ACC) is a scalp-recorded negative-positive voltage swing elicited by a change during an otherwise steady-state sound. The ACC was obtained from eight adults in response to changes of amplitude and/or spectral envelope at the temporal center of a three-formant synthetic vowel lasting 800 ms. In the absence of spectral change, the group mean waveforms showed a clear ACC to amplitude increments of 2 dB or more and decrements of 3 dB or more. In the presence of a change of second formant frequency (from perceived /u/ to perceived /i/), amplitude increments increased the magnitude of the ACC but amplitude decrements had little or no effect. The fact that the just detectable amplitude change is close to the psychoacoustic limits of the auditory system augurs well for the clinical application of the ACC. The failure to find a condition under which the spectrally elicited ACC is diminished by a small change of amplitude supports the conclusion that the observed ACC to a change of spectral envelope reflects some aspect of cortical frequency coding. Taken together, these findings support the potential value of the ACC as an objective index of auditory discrimination capacity.

Quality improvement in an integrated urban healthcare system: a necessary journey.

Public hospitals and clinics in the United States provide health care for the needs of large numbers of people who are medically indigent, homeless, chronically mentally ill, and suffer medical and social disorders associated with poverty. These "safety-net" healthcare providers traditionally struggle with barriers to providing high-quality, patient-sensitive care, including decaying physical facilities, burdensome bureaucracies, underfunded capital equipment and construction programs, and complex, politically driven budgets and governance. However, these same institutions now must compete for their own Medicaid and Medicare clientele because the private sector is marketing to those patients. They also must continue to provide increasing services to growing numbers of uninsured patients. To accomplish this, these institutions must reinvent themselves as patient-focused, high-quality, cost-effective healthcare providers. The Denver Health system is the public safety-net provider for the city and county of Denver. This large public institution has instituted a multifaceted performance-improvement program. The program includes training employees for patient-focused service, implementing continuous quality-improvement practices, instituting clinical pathways, revising the preexisting ambulatory quality-management program, reengineering key aspects of ambulatory clinic services, and redesigning the hospital-based patient-care services. Major successes have been achieved in some initiatives, but not in all. Many key "lessons learned" may guide others.

The effect of body temperature on leukocyte kinetics during cardiopulmonary bypass.

Leukocyte kinetics were investigated in 22 patients undergoing cardiopulmonary bypass to determine the nature of the changes in the white blood cell count associated with this procedure. Both polymorphonuclear leukocytes and lymphocytes were taken up by the lung as pulmonary blood flow was lowered, but only polymorphonuclear leukocytes were taken up as blood flow was restored. The complement 3a level was increased approximately twice the control value within 2 minutes of going on bypass and remained elevated throughout the procedure. The peripheral white blood cell count doubled during the bypass procedure owing to a release of polymorphonuclear leukocytes and their precursors from the bone marrow. The increase in polymorphonuclear leukocytes was prevented by hyperthermia but reappeared quickly when the body temperature was restored to 36 degrees to 37 degrees C.

Platelet sequestration in lung with hemorrhagic shock and reinfusion in dogs.

We compared red blood cell (RBC) and platelet transit through the pulmonary vascular bed under control conditions (n = 8) and during hemorrhagic shock (n = 8) in anesthetized spontaneously breathing dogs, using a modification of the indicator-dilutor technique. Platelets and RBCs from each animal were labeled with 51Cr and 99mTc, respectively, and were rapidly injected into the right atrium while blood was sampled from the ascending aorta. The mean transit time (MTT), volume of distribution, and percent recovery for RBCs and platelets were calculated, as was the percent extraction of platelets. We found 1) the the difference between RBC and platelet MTT increased (p less than 0.01), 2) that the percent extraction of platelets increased (p less than 0.001), and 3) that the percent recovery of platelets fell (p less than 0.01) during the shock period. These values all returned to control levels after reinfusion of the shed blood. The relationship between a transient reduction in blood flow and platelet extraction was then studied in a third group of dogs (n = 5) where inflation of a balloon in the inferior vena cava was used to reduce cardiac output (CO). These studies showed that platelet extraction was inversely related to CO. We conclude that the increased platelet sequestration seen in the lung during hemorrhagic shock is primarily related to decreased blood flow.