Effects of freshwater release on oyster reef density, reproduction, and disease in a highly modified estuary.

Few estuaries remain unaffected by water management and altered freshwater deliveries. The Caloosahatchee River Estuary is a perfect case study for assessing the impact of altered hydrology on natural oyster reef (Crassostrea virginica) populations. The watershed has been highly modified and greatly enlarged by an artificial connection to Lake Okeechobee. Accordingly, to generate data to support water management recommendations, this study monitored various oyster biometrics over 15 years along the primary salinity gradient. Oyster reef densities were significantly affected by both prolonged high volume freshwater releases creating hyposaline conditions at upstream sites and by a lack of freshwater input creating hypersaline conditions at downstream sites. Low freshwater input led to an increase in disease caused by Perkinsus marinus and predation. Moderate (< 2000 cfs) and properly timed (winter/spring) freshets benefited oysters with increased gametogenesis, good larval mixing, and a reprieve from disease. If high volume freshets occurred in the late summer, extensive mortality occurred at the upstream site due to low salinity. These findings suggest freshwater releases in the late summer, when reproductive stress is at its peak and pelagic larvae are most vulnerable, should be limited to < 2000 cfs, but that longer freshets (1-3 weeks) in the winter and early spring (e.g., December-April) benefit oysters by reducing salinity and lessening disease intensity. Similar strategies can be employed in other managed systems, and patterns regarding the timing of high volume flows are applicable to all estuaries where the management of healthy oyster reefs is a priority.

Veterans' attitudes to influenza vaccination in the setting of shortage of vaccine, 2004-2005.

OBJECTIVES: To inform strategies for vaccinating elderly veterans, the objectives were to determine the proportion of veterans > or =65 years old vaccinated against influenza during the 2004-05 vaccine-shortage, the place they received vaccine, the reasons why they were/were not vaccinated and their attitudes to the shortage. RESULTS: Among 682 respondents, 87% were vaccinated during 2004-05. More participants received vaccine at the Veterans' Administration hospital than previously (67% vs. 57%, p < 0.0001). Only 28% perceived themselves as being at high risk from influenza even though all participants met > or =1 high-risk criteria. Among unvaccinated participants, 21% were unvaccinated so that someone else could have their dose ("altruism"). For 61%, the shortage led to feeling heightened urgency for vaccination; those participants were more apt to be vaccinated (96% v. 77%, p < 0.001). Of those not vaccinated during the previous season, only 20% reported feeling urgency associated with the shortage, versus 65% of those vaccinated previously (p < 0.0001). METHODS: Survey-questionnaire mailed to a random sample of veterans > or =65 years-old. The questionnaire was derived from qualitative interviews during December 2004. CONCLUSION: The climate of shortage led to a heightened sense of urgency for vaccination that was most prominent among veterans who were vaccinated in the past. It also may have led to vaccination for a small proportion not previously vaccinated against influenza. In contrast, other elderly veterans may have been motivated to avoid vaccination for altruistic reasons or because of confusion about their risk-status. Outreach and communication about vaccination should target both those who may feel urgency to be vaccinated as well as those who may inappropriately avoid vaccination.

Effect of ozone exposure on airway responses to inhaled allergen in asthmatic subjects.

BACKGROUND: Controlled human exposure studies have produced conflicting results regarding the effect of ozone on the early bronchoconstrictor response to inhaled allergen in specifically sensitized asthmatic subjects. Spirometric parameters do not necessarily reflect the airway inflammatory effects of inhaled ozone or allergen. OBJECTIVE: This study was designed to investigate whether exposure to ozone enhances the late airway inflammatory response, as well as the early bronchoconstrictor response, to inhaled house dust mite allergen in sensitized asthmatic subjects. DESIGN: Randomized, counter-balanced, cross-over study. SETTING: Human exposure laboratory. METHODS: Fourteen subjects were exposed to 0.2 ppm O(3) or filtered air, on separate days, for 1 h during exercise. After each exposure, the subjects were challenged with doubling doses of Dermatophagoides farinae (DF) allergen (provocative concentration of DF causing a 15% decrease in FEV(1) [PC(15)]). At 6 h after allergen challenge, bronchoscopy with BAL, proximal airway lavage (PAL), and endobronchial biopsy were performed. The second exposure/allergen challenge/bronchoscopy sequence was performed at least 4 weeks after the first sequence. RESULTS: No significant difference in cellular or biochemical markers of the late inflammatory response after allergen was found between the ozone and air exposures (although a trend toward increased neutrophils was noted after ozone exposure in the PAL fluid, p = 0.06). For the group as a whole, no significant difference in PC(15) was demonstrated after ozone exposure compared to air exposure. However, subjects with the greatest ozone-induced decrements in FEV(1) tended to have lower PC(15) values after ozone exposure. CONCLUSION: Exposure to a relatively low-level concentration of ozone does not enhance the late inflammatory or early bronchoconstrictor response to inhaled antigen in most allergic asthmatic subjects. Our results do suggest, however, that a subgroup of asthmatics may acquire increased sensitivity to aeroallergens after exposure to ozone.