Construction of a fluorescent biosensor family.

Bacterial periplasmic binding proteins (bPBPs) are specific for a wide variety of small molecule ligands. bPBPs undergo a large, ligand-mediated conformational change that can be linked to reporter functions to monitor ligand concentrations. This mechanism provides the basis of a general system for engineering families of reagentless biosensors that share a common physical signal transduction functionality and detect many different analytes. We demonstrate the facility of designing optical biosensors based on fluorophore conjugates using 8 environmentally sensitive fluorophores and 11 bPBPs specific for diverse ligands, including sugars, amino acids, anions, cations, and dipeptides. Construction of reagentless fluorescent biosensors relies on identification of sites that undergo a local conformational change in concert with the global, ligand-mediated hinge-bending motion. Construction of cysteine mutations at these locations then permits site-specific coupling of environmentally sensitive fluorophores that report ligand binding as changes in fluorescence intensity. For 10 of the bPBPs presented in this study, the three-dimensional receptor structure was used to predict the location of reporter sites. In one case, a bPBP sensor specific for glutamic and aspartic acid was designed starting from genome sequence information and illustrates the potential for discovering novel binding functions in the microbial genosphere using bioinformatics.

Process evaluation of an environmental walking and healthy eating pilot in small rural worksites.

Small Steps are Easier Together (SS) was a pilot environmental intervention in small rural worksites in Upstate New York in collaboration with Extension educators. Worksite leaders teamed with co-workers to select and implement environmental changes to increase walking steps over individual baseline and to choose healthy eating options over 10 weeks. Participants were 226 primarily white, women employees in 5 sites. A mixed methods process evaluation, conducted to identify determinants of intervention effectiveness and to explain differences in outcomes across worksites, included surveys, self-reports of walking and eating, interviews, focus groups, and an intervention log. The evaluation assessed reach, characteristics of recruited participants, dose delivered, dose received, and context and compared sites on walking and eating outcomes. Emergent elements of participant-reported dose received included: active leadership, visible environmental changes, critical mass of participants, public display of accomplishments, accountability to co-workers, and group decision making. Participants at sites with high reach and dose were significantly more likely than sites with low reach and dose to achieve intervention goals. Although this small pilot needs replication, these findings describe how these evaluation methods can be applied and analyzed in an environmental intervention and provide information on trends in the data.

Isoflavones and antioxidant capacity of commercial soy-based beverages: effect of storage.

Samples of 11 different brands of commercially available soy-based beverages (n = 65), including products made from soy protein isolate (SPI) and soy milk, mixed with fruit juice and/or flavoring, were analyzed for their isoflavone content and in vitro antioxidant activity. There was a large variation in isoflavone and total phenolics contents ranging from 0.7 to 13 mg of isoflavones/200 mL and from 6 to 155 mg equivalents of catechin/200 mL, respectively. The antioxidant activity also varied significantly among products. Storage of the beverages at room temperature caused a significant decrease of antioxidant capacity, soluble phenolics, and isoflavone contents after 9 months. When soybeans used for beverage production were stored for up to 6 months in silos, the resulting products were not affected. However, a decrease of malonyl and a proportional increase of free glucosidic forms of isoflavones were observed after storage of both the raw material and the beverages.

Epidemiology and outcomes of clostridium difficile-associated disease among patients on prolonged acute mechanical ventilation.

PURPOSES: Patients receiving prolonged acute mechanical ventilation (PAMV), although comprising a third of all mechanical ventilation (MV) patients, consume two-thirds of all the resources allocated to MV, and their numbers are projected to double by 2020. By virtue of their prolonged hospital length of stay (median LOS, 17 days), they are subject to such nosocomial infections as Clostridium difficile-associated disease (CDAD), the incidence and age-adjusted case fatality rate of which doubled between 2000 and 2005. We examined the rates and outcomes of CDAD among adult PAMV patients. METHODS: We analyzed 2005 data from the Health Care Utilization Project/Nationwide Inpatient Sample from the Agency for Healthcare Research and Quality. PAMV and CDAD were identified using the International Classification of Diseases, ninth revision, clinical modification codes 96.72 and 008.45, respectively. RESULTS: Among 64,910 adult PAMV patients who were discharged in 2005, 3,468 patients (5.34%) had a concurrent diagnosis of CDAD (PAMV patients who were discharged with concomitant diagnosis of CDAD [CDAD+]). CDAD+ patients who were discharged were older (mean [+/- SD] age, 66.7 +/- 15.9 vs 63.7 +/- 16.9 years, respectively; p < 0.001) and were more likely to have been admitted to the hospital from a long-term care facility (5.7% vs 2.9%, respectively; p < 0.001) than PAMV patients who were discharged without CDAD (CDAD-). Although crude hospital mortality rates did not differ among PAMV patients who were discharged from the hospital by CDAD status (CDAD+, 32.6%; CDAD-, 33.0%; p = 0.598), both unadjusted calculations and propensity-score adjustment showed a substantial increase in LOS (6.1 days; 95% confidence interval [CI], 4.9 to 7.4) and total costs ($10,355; 95% CI, $7,540 to $13,170) among CDAD+ patients. CONCLUSIONS: PAMV patients have an order of magnitude higher risk of having CDAD than other hospitalized patients. Concurrent CDAD infection is associated with increased hospital LOS and costs. The PAMV population is an attractive target for aggressive measures aimed at CDAD prevention.