Combined and independent effects of hypoxia and tributyltin on mRNA expression and physiology of the Eastern oyster (Crassostrea virginica).

Oyster reefs are vital to estuarine health, but they experience multiple stressors and globally declining populations. This study examined effects of hypoxia and tributyltin (TBT) on adult Eastern oysters (Crassostrea virginica) exposed either in the laboratory or the field following a natural hypoxic event. In the laboratory, oysters were exposed to either hypoxia followed by a recovery period, or to hypoxia combined with TBT. mRNA expression of HIF1-α and Tß-4 along with hemocyte counts, biomarkers of hypoxic stress and immune health, respectively, were measured. In field-deployed oysters, HIF1-α and Tß-4 expression increased, while no effect on hemocytes was observed. In contrast, after 6 and 8 days of laboratory-based hypoxia exposure, both Tß-4 expression and hemocyte counts declined. After 8 days of exposure to hypoxia + TBT, oysters substantially up-regulated HIF1-α and down-regulated Tß-4, although hemocyte counts were unaffected. Results suggest that hypoxic exposure induces immunosuppression which could increase vulnerability to pathogens.

Proximity of pediatric genetic services to children with birth defects in Texas.

BACKGROUND: Families of children with major structural malformations often benefit greatly from genetic services. However, these services may not be readily available in all areas. The purpose of this study was to use data from a statewide birth defects registry and geographic information system methodology to compare the spatial distribution and to summarize the distance of pediatric clinical genetic service providers in relation to residential addresses of children with selected birth defects in Texas. METHODS: Live-born children delivered between 1999-2004 in the Texas Birth Defects Registry with major structural defects and chromosomal anomalies were selected by a clinical geneticist according to diagnosis code. Mother's address at delivery of the case infants was geocoded as was the location of offices where clinical geneticists in Texas see pediatric patients. Using geographic information system tools, the authors then computed distance from each case mother's residence to the location of the nearest office where pediatric patients can be seen by clinical geneticists, summarized these distances, and graphically plotted the location of each case in relation to the nearest provider. RESULTS: Nearly 25,000 Registry cases met the criteria for selection for geocoding. Of those, 22,875 (91.8%) were successfully geocoded to street level. CONCLUSIONS: Although 82% of addresses were within 30 miles of the nearest pediatric genetic clinic, 14% lived 31-100 miles from the nearest facility, and 4% of case families would need to drive more than 100 miles, including some who live in midsized cities, indicating geographic disparities in access to these necessary services.