Periphyton bioconcentrates pesticides downstream of catchment dominated by agricultural land use.

Periphyton provides important ecosystem services in aquatic environments, including supporting diverse consumers. We studied pesticide bioconcentration in periphyton in a coastal marsh on Lake Erie. The marsh is within a protected area (Rondeau Provincial Park) but receives discharge from tributaries draining intensively farmed land. Periphyton bioconcentrated 20 pesticide chemicals above levels observed in adjacent water or sediment. Average bioconcentration factors ranged from 12 times for the herbicide dicamba to 6864 times for the fungicide boscalid on a dry-weight basis. Bioconcentration factors were not linearly related to pesticides' log Kow, log Koc, or water solubility (simple linear regressions, p > 0.43). The removal of pesticides from ambient water represents another valuable ecosystem service provided by periphyton. However, we caution that bioconcentration of pesticides in periphyton provides a mechanism through which contemporary and legacy pesticides may enter wetland food webs.

Identifying the core bacterial and fungal communities within four agricultural biobeds used for the treatment of pesticide rinsates.

AIMS: This study evaluated the variability of bacterial and fungal communities within unique pesticide remediation biobeds. METHODS AND RESULTS: Four biobeds receiving different applied pesticide rinsates, were sampled throughout an operational season to determine pesticide removal efficacy and microbial communities. Biomixture samples collected from different biobed depths, were subjected to Illumina sequencing of the 16S rRNA (bacteria) and ITS2 (fungi) genes. Pesticide removal rates for all biobeds averaged 99%, with microbial community analysis revealing biobeds shared 60-70% of the most abundant bacterial and fungal orders, respectively. Though biobed depth did not greatly impact microbial community profile or diversity, bacterial and fungal taxa profiles between biobeds notably diverge at levels of genera and OTU. Biobed bacterial communities exhibited greater diversity than fungal communities between and within all biobeds. CONCLUSIONS: Biobeds receiving variable pesticide rinsates share a 'core' microbial community, exhibiting greater bacterial diversity relative to fungal diversity. Pesticide exposure increased bacterial diversity throughout the biobeds, while fungal diversity was variable, meriting further understanding of fungicide application to biobed fungal community stability. SIGNIFICANCE AND IMPACT OF THE STUDY: Biobeds achieve high treatment efficacy of unique pesticide rinsates, regardless of differentiation of specific genera in response to specific compounds; supporting biobeds as a robust engineered system for pesticide rinsates bioremediation.

Genetic characterization and antimicrobial susceptibility of Mannheimia haemolytica isolated from the nasopharynx of feedlot cattle.

A surveillance study was undertaken to examine the population dynamics and antimicrobial resistance of Mannheimia haemolytica isolated from feedlot cattle. A total of 416 isolates were collected from the nasopharynx either upon entry or exit from two feedlots in southern Alberta, Canada. Isolates were serotyped, characterized by pulsed-field gel electrophoresis and tested for susceptibility to ten antimicrobial agents via disk diffusion. Resistant isolates were screened by PCR for select antimicrobial-resistance gene determinants. Isolates were highly diverse, with 335 unique pulsed-field profiles identified among 147 strongly related clusters (similarity ≥ 85%). Clonal spread of isolates throughout the feedlots was limited and no clear association was found between genetic relatedness of M. haemolytica and sampling event (entry or exit). Pulsed-field profiles sharing a common serotype and resistance phenotype tended to cluster together. The majority of isolates were identified as serotype 2 (74.5%) although both serotype 1 (11.9%) and 6 (12.7%) were detected. Only 9.54% of isolates exhibited antimicrobial resistance. Resistance to oxytetracycline was most prevalent (n=16), followed by ampicillin (n=10), and amoxicillin/clavulanic acid (n=7). Multi-drug resistance was observed in five isolates. The tetH gene was detected in all but two oxytetracycline resistant isolates. Other detectable resistance determinates included ermX and bla(ROB-1). In the two feedlots examined, M. haemolytica exhibited considerable genetic diversity and limited resistance to common veterinary antibiotics. Garnering further information on the linkage between genotype and phenotype should contribute toward a better understanding of the pathogenesis and dissemination of M. haemolytica in feedlots.

Immunoaffinity purification of chlorimuron-ethyl from soil extracts prior to quantitation by enzyme-linked immunosorbent assay.

A competitive-indirect enzyme-linked immunosorbent assay (CI-ELISA) was developed to quantify chlorimuron-ethyl in soil. The linear working range of the assay was from 1 to 1000 ng mL(-)(1). The assay had an I(50) value of 54 ng mL(-)(1), with a limit of detection of 2 ng mL(-)(1) and a limit of quantification of 27 ng mL(-)(1). Three soils were extracted using a carbonate buffer (pH 9.0) and the extracts spiked with chlorimuron-ethyl. Because of the effects of coextractants (matrix effects) from soil on the accuracy and precision of the ELISA, immunoaffinity chromatography (IAC) was used to purify chlorimuron-ethyl from soil extracts prior to analysis. The immunoaffinity columns, which had a total binding capacity of 1350 ng of chlorimuron-ethyl mL(-)(1) of immunosorbent, were prepared by binding anti-chlorimuron-ethyl antibodies to protein G Sepharose 4B. Although the matrix effects were largely removed using the affinity column, they could be completely removed by first passing the extract through a column containing epoxy-coupled 1,6-diaminohexane (EAH) Sepharose 4B to remove organic acids prior to IAC. Assay sensitivity was increased 100-fold using IAC to purify and simultaneously concentrate chlorimuron-ethyl from soil extracts. The purification strategy (EAH followed by IAC chromatography) removed matrix effects from all three soils and allowed for the accurate quantitation of chlorimuron-ethyl in soil extracts.

Predictors of acute hospital costs for treatment of ischemic stroke in an academic center.

BACKGROUND AND PURPOSE: We sought to determine predictors of acute hospital costs in patients presenting with acute ischemic stroke to an academic center using a stroke management team to coordinate care. METHODS: Demographic and clinical data were prospectively collected on 191 patients consecutively admitted with acute ischemic stroke. Patients were classified by insurance status, premorbid modified Rankin scale, stroke location, stroke severity (National Institutes of Health Stroke Scale score), and presence of comorbidities. Detailed hospital charge data were converted to cost by application of department-specific cost-to-charge ratios. Physician's fees were not included. A stepwise multiple regression analysis was computed to determine the predictors of total hospital cost. RESULTS: Median length of stay was 6 days (range, 1 to 63 days), and mortality was 3%. Median hospital cost per discharge was $4408 (range, $1199 to $59 799). Fifty percent of costs were for room charges, 19% for stroke evaluation, 21% for medical management, and 7% for acute rehabilitation therapies. Sixteen percent were admitted to an intensive care unit. Length of stay accounted for 43% of the variance in total cost. Other independent predictors of cost included stroke severity, heparin treatment, atrial fibrillation, male sex, ischemic cardiac disease, and premorbid functional status. CONCLUSIONS: We conclude that the major predictors of acute hospital costs of stroke in this environment are length of stay, stroke severity, cardiac disease, male sex, and use of heparin. Room charges accounted for the majority of costs, and attempts to reduce the cost of stroke evaluation would be of marginal value. Efforts to reduce acute costs should be monitored for potential cost shifting or a negative impact on quality of care.

Relation between social problem-solving ability and subsequent level of psychological stress in college students.

A prospective design was used to examine the relation between social problem-solving ability and later psychological stress in college students during the first semester of the academic year. A new social problem-solving inventory measured not only general ability, but also more specific components of the problem-solving process (e.g., problem orientation, problem-solving skills; D'Zurilla & Nezu, 1990). The results of a hierarchical multiple regression analysis showed that general problem-solving ability was negatively related to later stress, even after prior stress level and number of life problems were controlled. More specific analyses indicated that subjects' problem orientation was a better predictor of stress than their problem-solving skills. Results are discussed in terms of the possible stress-reducing effects of perceived control and successful problem resolution.